CN105142913A - Techniques for print ink droplet measurement and control to deposit fluids within precise tolerances - Google Patents

Abstract

An ink printing process employs process software that measures drop volume per nozzle and plans drop combinations to achieve a specific aggregate ink fill per target area, ensuring compliance with minimum and maximum ink fills set by specifications. In various embodiments, different droplet combinations are produced by different printhead/substrate scan offsets, offsets between printheads, use of different nozzle drive waveforms, and/or other techniques. These combinations may be based on repeated rapid droplet measurements that yield an average and expanded understanding for each nozzle for expected droplet volume, velocity, and trajectory, where the droplet is planned based on these statistical parameters combination. Optionally, random fill variations can be introduced, thereby mitigating speckle effects in the fabricated display device. The disclosed technology has many possible applications.

Description

Techniques for measurement and control of printing ink droplets to deposit fluid within precise tolerances

Cross References to Related Applications

The application requests "Techniques For Print Ink Droplet Volume Measurement And Control Over Deposited Fluids Within Precise Tolerances," U.S. Provisional Patent Application No. 61/950,820. This application is also in part representative of "Techniques for A continuation of U.S. Utility Patent Application No. 14/162525 for Print Ink Volume Control To Deposit Fluids Within Precise Tolerances". U.S. Utility Patent Application No. 14/162525 is claimed on behalf of first named inventor Nahid Harjee on December 26, 2013 Day on "Techniques for Print Ink Volume Control To Deposit Fluids Within Precise Tolerances" the priority of Taiwan Patent Application No. 102148330, and also on behalf of the first named inventor Nahid Harjee on December 24, 2013 on "Techniques for A continuation of PCT Patent Application No. PCT/US2013/077720 filed for Print Ink Volume Control To Deposit Fluids Within Precise Tolerances. PCT Patent Application No. PCT/US2013/077720 claims priority to each of the following patent applications: U.S. Provisional Patent Application No. 61/746,545, filed December 27, 2012, on "Smart Mixing" on behalf of first named inventor Conor Francis Madigan; on behalf of first named inventor Nahid Harjee, May 13, 2013 on “Systems and Methods Providing Uniform Printing of OLED Panels" U.S. Provisional Patent Application No. 61/822855; filed on July 2, 2013 on behalf of first named inventor Nahid Harjee for "Systems and Methods Providing Uniform Printing of OLED Panels" U.S. Provisional Patent Application No. 61/842351; filed on July 23, 2013 on behalf of first named inventor Nahid Harjee for "Systems and Methods Providing Uniform Printing of OLED Panels" U.S. Provisional Patent Application No. 61/857298; filed on Nov. 1, 2013 on behalf of first named inventor Nahid Harjee for "Systems and Methods Providing Uniform Printing of OLED Panels” U.S. Provisional Patent Application No. 61/898769; and “Techniques for Print Ink Volume Control To Deposit Fluids Within Precise Tolerances," U.S. Provisional Patent Application No. 61/920,715. This application also claims a patent application filed on April 26, 2014 on behalf of first named inventor Alexander Sou-Kang Ko for "OLED Printing Systems and Methods Using Laser Light Scattering for Measuring Ink Drop Size, Velocity and Trajectory," U.S. Provisional Patent Application No. 61/816696, and "OLED Printing Systems and Methods Using Laser Light Scattering for Measuring Ink Drop Size, Velocity and Trajectory," U.S. Provisional Patent Application No. 61/866,031. Each of the foregoing patent applications is hereby incorporated by reference.

technical field

This disclosure relates to techniques for measuring with high statistical accuracy the volume of inkjet droplets used in the fabrication of organic light emitting diode ("OLED") devices, for delivering droplets of fluid ink in precise aggregate quantities Print processing to a target area of a substrate, and relates to related methods, apparatus, improvements and systems. In one non-limiting application, the techniques provided by this disclosure can be applied to fabrication processes for OLED display panels.

Background technique

In a printing process where a printhead has multiple nozzles, not every nozzle reacts in the same way to a standard drive waveform, ie each nozzle may produce a drop of slightly different volume. Where nozzles are relied upon to deposit fluid droplets into respective fluid deposition zones ("target zones"), the lack of uniformity can cause problems. This is especially true for manufacturing applications where ink transfers to materials will become permanent thin film structures within electronic devices. An example application where this problem arises is in the manufacture of displays (such as organic light-emitting diode (“OLED”) displays) for use in small and large electronic devices, such as for portable devices, large-scale high-definition television panels, and others ) in the manufacturing process. Where the printing process is used to deposit the ink-borne light-generating material of these displays, volumetric differences across rows or columns of pixels contribute to visible lighting or color artifacts in the displayed image. Note that "ink" as used herein refers to any fluid that is applied to a substrate by the nozzles of a printhead, regardless of color characteristics; for example, in the mentioned OLED display fabrication application, ink is typically deposited in place and then Treated, dried or cured to directly form a layer of permanent material, and the treatment may be repeated with the same ink or different inks to form several such layers.

FIG. 1A is used to introduce this nozzle droplet inconsistency problem by way of an illustrative diagram generally indicated by reference numeral 101 . In FIG. 1A , printhead 103 can be seen as having five ink nozzles, each numbered (1 )-(5), each depicted with a small triangle at the bottom of the printhead. Note that in a typical manufacturing application, there may be many greater than five nozzles (eg, 24-10,000), depending on the application; in the case of FIG. 1A , simply five nozzles are referred to for ease of understanding. It should be assumed that, in the example application, it is desired to deposit fifty picoliters (50.00 pL) of fluid into each of the five specific target zones of the array of these zones, and that in addition, each of the five nozzles of the printhead Ten picoliters (10.00 pL) of fluid should be ejected into each of the respective target zones with each relative movement ("pass" or "scan") between the printhead and the substrate. The target area may be any surface area of the substrate, including adjacent non-separated areas (eg, such that deposited fluid ink partially spreads to mix together between areas) or corresponding fluidically isolated areas. These regions are generally represented in FIG. 1A using ovals 104-108, respectively. Therefore, it can be assumed that exactly five passes of the printhead are necessary to fill each of the five specific target zones as described. However, the printhead nozzles will actually have some slight variation in structure or actuation such that a given drive waveform applied to each nozzle transducer produces a slightly different drop volume for each nozzle. As depicted in FIG. 1A , for example, the firing pass of nozzle ( 1 ) produces a drop volume of 9.80 picoliters (pL) per pass, where five 9.80 pL drops are depicted within oval 104 . Note that each of the droplets is represented in the figure by a different location within the target zone 104, but in reality, the location of each of the droplets may be the same or may overlap. By way of comparison, nozzles (2)-(5) produced slightly different corresponding droplet volumes of 10.01 pL, 9.89 pL, 9.96 pL and 10.03 pL. With five passes between the printhead and the substrate where each nozzle deposits fluid into the target areas 104-108 on a mutually exclusive basis, this deposition will produce 1.15 pL of fluid across the five target areas. Total deposited ink volume varies; this may not be acceptable for many applications. For example, in some applications, as little as a percentage (or even far less) variance in the deposited fluid can cause problems; in the case of OLED display fabrication, this variation could potentially lead to image artifacts observable in displays.

Manufacturers of televisions and other forms of displays will thus effectively specify with high precision the exact volume ranges that must be observed (e.g. 50.00pL, ±0.25pL) in order for the resulting product to be considered acceptable; note that in In this exemplary case, the specified tolerance must be within 0.5 percent of the target of 50.00 pL. In an application represented by Figure 1A where each nozzle deposits into pixels in a corresponding horizontal row of a high-definition television ("HDTV") screen, the depicted variation of 49.02pL-50.17pL may thus yield unacceptable quality , as this would represent approximately ±1.2% variation (eg, not the desired maximum tolerance of ±0.5% variation). While display technology has been cited as an example, it should be understood that nozzle droplet inconsistency issues may arise in other situations.

In FIG. 1A , nozzles are specifically aligned with target areas (eg, wells) such that specific nozzles print into specific target areas. In FIG. 1B an alternative case 151 is shown, in which the nozzles are not specifically aimed, but the nozzle density is high relative to the target zone density; Any one nozzle is used to print into these target zones, with potentially several nozzles traversing each target zone in each pass. In the example shown, the visible printhead 153 has five ink nozzles, and the visible substrate has two target zones 154-155, each positioned such that: nozzles (1) and (2) will traverse target zone 154, Nozzles (4) and (5) will traverse target zone 155 and nozzle (3) will not traverse any target zone. As shown, in each pass, one or two droplets are deposited into each well, as depicted. Note again that the droplets may be deposited in an overlapping fashion, or at discrete points within each target zone, and that the particular illustration in FIG. 1B is illustrative only; as for the example presented in FIG. 1A , again Assume that fifty picoliters (50.00 pL) of fluid are desired to be deposited into each of the target zones 154-155, and that each nozzle has a nominal drop volume of approximately 10.00 pL. Utilizing the same per-nozzle droplet volume variation observed with respect to the example of FIG. 1A , and assuming that each nozzle that overlaps a target zone on a given pass delivers a droplet into that zone until it has delivered For a total of five drops, the target area was observed to be filled in three passes, and there was a total deposited ink volume change of 0.58 pL across the two target areas from the 50.00 pL target and a further change outside the specified tolerance. difference; again, this may not be acceptable for many applications.

Note that, in relation to the above example, even for a given nozzle and a given drive waveform, the problem of drop consistency may be further exacerbated by the problem that drop volume may vary statistically. Thus, in the example discussed above, although it was assumed that the nozzle (1) from the printhead of Figures 1A and 1B would produce a droplet volume of 9.80 pL in response to a given drive waveform, in practice, in real-world situations In this case, it can be assumed that drop volume varies to such an extent that it depends on various factors such as process, voltage, temperature, printhead aging, and many others, such that the actual drop volume may not be known precisely.

While techniques have been proposed to address the droplet consistency problem, in general, these techniques either still do not reliably provide fill volumes that stay within desired tolerances, or they dramatically increase manufacturing time and cost, i.e., they are not the same as The goal of having high quality at a low consumer price point is misaligned; such quality and low price point may be critical for applications focused on commercial products such as HDTV.

Accordingly, what is needed are techniques useful for depositing fluid onto target areas of a substrate using a printhead having nozzles. More specifically, what is needed is a method for ideally precisely controlling the response of a substrate despite variations in nozzle droplet ejection volume on a cost-effective basis that allows rapid fluid deposition operations and thus improves the speed of device fabrication. The technique of the deposited fluid volume in the target zone. The techniques described below meet these needs and provide further related advantages.

Description of drawings

Figure 1A is a diagram presenting a hypothetical problem of depositing ink in target areas of a substrate using a printhead with five nozzles to deposit 50.00 pL of target in each of five specific target areas filling.

Figure 1B is another diagram presenting the hypothetical problem of depositing ink in target areas of a substrate using a printhead with five nozzles to deposit 50.00 pL in each of two specific target areas target padding.

2A is an illustrative diagram showing a drop measurement system capable of measuring drop volume for each nozzle of a large printhead assembly.

2B is a method diagram illustrating various processes and options associated with measuring drop volume for each nozzle.

2C is a method diagram illustrating various processes and options associated with measuring drop volume for each nozzle for achieving a high confidence understanding of expected drop volume.

Figure 2D is a schematic diagram illustrating the layout of various components used in one embodiment for performing droplet measurements.

Figure 2E is a schematic diagram showing the layout of various components used in another embodiment for performing droplet measurements.

FIG. 3A provides an illustrative view showing a series of optional tiers, products, or services that may each independently embody the techniques described above.

3B is an illustrative diagram showing a hypothetical arrangement of a printer and a substrate in an application where the substrate is ultimately used to form a display panel having pixels.

3C is a cross-sectional close-up view of the printhead and substrate of FIG. 3B taken from perspective from line C-C of FIG. 3B.

Figure 4A is a diagram similar to Figure 1A, but showing the use of drop volume combinations to reliably produce ink fill volumes for each target zone within predetermined tolerances; The set of firing waveforms produces different combinations of drop volumes and, in another optional embodiment, relative motion between the printhead and substrate (405) is used to produce different combinations of drop volumes from corresponding nozzles of the printhead.

Figure 4B is a diagram illustrating relative printhead/substrate motion and ejection of different drop volume combinations into corresponding target areas of the substrate.

Figure 4C is a diagram illustrating the use of different nozzle drive waveforms at each nozzle to produce different drop volume combinations into respective target regions of the substrate.

Figure 4D is a diagram similar to Figure 1B, but showing the use of drop volume combinations to reliably produce ink fill volumes for each target zone within predetermined tolerances; in an alternative embodiment, firing from predetermined nozzles The set of waveforms produces different combinations of drop volumes, and in another optional embodiment, the relative motion between the printhead and the substrate is used (472) to produce different combinations of drop volumes from corresponding nozzles of the printhead.

Figure 5 provides a block diagram illustrating a method of planning droplet combinations for each target area of a substrate; this method may be applied to any of the alternative embodiments described in Figures 4A-4D.

Figure 6A provides a block diagram for selecting a particular set of acceptable droplet combinations for each target region of a substrate that may be used, for example, with any of the previously described embodiments.

Figure 6B provides a block diagram for iteratively planning printhead/substrate motion and using nozzles based on droplet combinations for each print zone.

Figure 6C provides a block diagram illustrating further optimization of printhead/substrate motion and use of nozzles, specifically to sequence scans in such a way as to perform printing as efficiently as possible.

Figure 6D is a hypothetical plan view of a substrate that would ultimately result in multiple flat panel display devices (e.g. 683); as labeled area 687, printhead/substrate motion can be optimized for specific regions of a single flat panel display device, where Optimization is used on a repeatable or periodic basis across each display device (eg, the four depicted flat panel display devices).

7 provides a block diagram for intentionally varying fill volumes within acceptable tolerances to reduce visual artifacts in a display device.

FIG. 8A provides a block diagram showing how drop measurement can be used to accommodate statistical variation in drop volume per nozzle and per drive waveform and still allow accurate polymeric ink filling within a given target zone.

FIG. 8B provides a block diagram showing how drop measurement can be planned to accommodate statistical variation in drop volume per nozzle and per drive waveform and still allow accurate aggregate ink filling within a given target zone.

Figure 9A provides a graph showing the change in target zone fill volume without adjustment for the printhead's inter-nozzle drop volume change.

Figure 9B provides a graph showing the variation in target zone fill volume where different nozzles are used randomly to statistically compensate for drop volume variation across nozzles of a printhead.

Figure 9C provides a graph showing the change in target zone fill volume using one or more droplets of different volumes to achieve the target zone fill volume within precise tolerances on a planned basis.

Figure 10A provides a graph showing the change in target zone fill volume without adjustment for the printhead's inter-nozzle drop volume change.

FIG. 10B provides a graph showing the variation in target zone fill volume when different nozzles are used randomly to statistically compensate for drop volume variation across nozzles of a printhead.

FIG. 10C provides a graph showing the change in target zone fill volume using one or more droplets of different volumes to achieve the target zone fill volume within precise tolerances on a planned basis.

Figure 11 shows a plan view of a printer used as part of the fabrication apparatus; the printer may be within an air enclosure allowing printing to take place in a controlled atmosphere.

FIG. 12 provides a block diagram of a printer; such a printer may optionally be employed, for example, in the preparation apparatus described in FIG. 11 .

Figure 13A shows an embodiment using multiple print heads (each having nozzles) to deposit ink on a substrate.

Figure 13B illustrates rotating multiple printheads to better align the nozzles of the respective printheads with the substrate.

Figure 13C shows the offset of individual printheads of a plurality of printheads associated with smart scanning to intentionally produce specific drop volume combinations.

Figure 13D shows a cross-section of a substrate including layers that may be used in an organic light emitting diode (OLED) display.

Figure 14A shows a number of different ways of customizing or changing the nozzle firing waveform.

Figure 14B illustrates the manner in which a waveform is defined in terms of discrete waveform segments.

Figure 15A shows an embodiment where different combinations of drop volumes can be achieved using different combinations of predetermined nozzle firing waveforms.

Figure 15B shows the circuitry associated with generating a programming waveform at a programming time (or position) and applying it to the nozzles of a printhead; One possible implementation of each of 1533.

Figure 15C shows a flow diagram of one embodiment using different nozzle firing waveforms.

Figure 15D shows a flow diagram associated with nozzle or nozzle waveform qualification.

Figure 16 shows a perspective view of an industrial printer.

Figure 17 shows another perspective view of the industrial printer.

Figure 18A presents a schematic diagram showing the layout of components in an embodiment of a shadow map based droplet measurement system.

Figure 18B presents a schematic diagram showing the layout of components in an embodiment of an interferometry-based droplet measurement system.

19 shows a flowchart associated with one illustrative process of integrating a drop measurement system with an industrial printer, optionally for the fabrication of OLED devices.

The subject matter defined by the enumerated claims may be better understood by referring to the following detailed description which should be read in conjunction with the accompanying drawings. The description of one or more specific examples of the various implementations set forth below to enable one to make and use the claimed technology is not intended to limit the enumerated claims, but rather to illustrate their application. Without limiting the foregoing, the present disclosure provides methods for fabricating layers of material by planning printhead movements such that the deposited ink volume remains within predetermined tolerances without unduly increasing the number of printhead passes (and thus A number of different examples of techniques for the time it takes to complete a deposited layer). Associated with these technologies, precise drop measurement can be performed, allowing precise planning of synthetic ink fill in any target zone with measurements highly integrated with production printing. The various techniques may be embodied in the form of software for carrying out these techniques, in the form of a computer, a printer or another device running the software, in the form of control data (such as printing images) for forming layers of material, in deposition mechanisms, or as such In the form of an electronic device or another device (such as a flat panel device or other consumer end product) produced as a result of the technology. While specific examples are presented, the principles described herein are equally applicable to other methods, devices, and systems.

Detailed ways

This disclosure relates to the use of a printing process to transfer layer material to a substrate, techniques for drop measurement with high precision, and related methods, improvements, devices and systems.

The nozzle uniformity problem described above can be addressed by measuring the per-nozzle drop volume of a printhead (or the variation in drop volume across nozzles) for a given nozzle firing waveform. This allows planning of printhead firing patterns and/or movements to deposit precisely aggregated fill volumes of ink in each target zone. With an understanding of how drop volumes vary across nozzles, printheads/grounds can be planned in a way that accommodates differences in drop volumes but still simultaneously deposits drops in adjacent target zones with each pass or scan Positional offset and/or droplet emission pattern. Viewed from a different perspective, instead of normalizing or averaging the nozzle-to-nozzle variation in drop volume, the specific drop volume characteristics of each nozzle are measured and used in a programmatic fashion to simultaneously achieve Aggregate volumes within a specified range; in many embodiments, this task is performed using an optimization process that reduces the number of scans or printhead passes according to one or more optimization criteria.

A number of different embodiments contributing to achieving these results are presented below. Each embodiment may be used on its own, and it is also expressly contemplated that features of any embodiment may optionally be mixed and matched with features of different embodiments.

One embodiment proposes systems and techniques that provide personalized drop measurement on very large (eg, with hundreds to thousands of nozzles or more) printhead assemblies. Using a deposition-plane measurement technique (i.e. redirecting light away from the vicinity of the printhead by going beyond the relative distance at which the substrate would normally be positioned for deposition), for example using light that can be actuated in up to three dimensions Device assembly such that (e.g. within a confined space) a large printhead assembly can optionally be docked (e.g. at a printer service station) and the drop measurement device precisely coupled relative to the large printhead assembly, addressing issues with optics The logical difficulty of locating associations. Precise placement of the optics assembly below the deposition plane enables drop volume measurements of the packaged nozzle array at the required distance from the nozzle plate despite the confined space (printhead assemblies are typically at a distance from the substrate operating on the order of 1 mm of the surface). In an optional embodiment, the optics system employs shadow maps and repeated measurements of droplets (and optionally, altered nozzle drive waveforms) emitted from specific nozzles to increase statistical confidence in expected droplet volumes . In another optional embodiment, the optics system employs interferometry and repeated measurements of droplets emitted from specific nozzles (and optionally, altered nozzle drive waveforms) to increase statistical confidence in the expected droplet volume Spend.

Note that in a production line it is typically desirable to have as little downtime as possible in order to maximize productivity and minimize manufacturing costs. In another alternative embodiment, the drop measurement time is thus "hidden" or "stacked" behind other line processing. For example, in an optional flat panel display manufacturing line, as each new substrate is loaded or otherwise handled, processed, or transferred, a drop measurement process is used to analyze the printer's printhead assembly to facilitate per-nozzle (and and/or precise statistical understanding of drop volume per nozzle, per drive waveform. For printhead assemblies with tens of thousands of nozzles, repeated drop measurements (e.g. large number of drops per nozzle, per drive waveform if multiple drive waveforms are used) can be time consuming; optional system control processing and associated software can thus optionally perform droplet measurements on a dynamic, incremental basis. For example, if a hypothetical load/unload process requires, say, 30 seconds, where each print process takes 90 seconds, the printhead assembly can be measured during the load/unload process in a two-minute period, updating the drop measurements to use the A sliding window of nozzles/droplets analyzed during the loading/unloading process associated with each two-minute period was used to obtain droplet volume averages and confidence intervals per nozzle. Note that many other processes are possible, and not all embodiments require continuous dynamic processing. However, it is believed that, in practice, not only will the drop volume for a given nozzle and drive waveform vary relative to other nozzles and drive waveforms, but further, due to factors such as subtle changes in ink properties, nozzle aging and Factors such as degradation and others, typical values will also change over time; a process of periodically updating measurements eg every few hours to days may thus advantageously further improve reliability.

In yet another alternative embodiment, the droplet measurement system uses interferometry and non-imaging techniques to obtain very fast droplet measurements, for example, performing per-droplet measurements in a few microseconds and in less than thirty minutes Repeated drop measurement is performed across a printhead assembly with several thousand nozzles. In contrast to imaging techniques (which use a camera and captured image pixel processing techniques to derive volumetric measurements), interferometry techniques can detect the spacing of an interference pattern representing the shape of a droplet by using multiple light sensors and relate this spacing to the volume of the droplet. Correlation is performed to provide accurate drop volume measurements. In one implementation, the laser source and/or associated optics and/or sensors are mechanically mounted for down-plane measurement and active linkage relative to the large printhead assembly. Due to the very fast measurements achievable by such systems, interferometry techniques are especially useful in embodiments where dynamic incremental measurements are performed as described, and by such techniques, at each print cycle Here, tens to hundreds of nozzles can be subjected to repeated drop measurements (eg, measurements of thirty drops per nozzle) to achieve high statistical confidence around each expected drop volume.

In yet another alternative embodiment, many droplet measurements are taken per nozzle and per nozzle drive waveform (for embodiments using altered nozzle drive waveforms). As the number of measurements increases, the mean and standard deviation (assuming a normal random distribution) for each combination of nozzle waveforms becomes more distinct. Using mathematical processing implemented by the software, statistical models for each droplet can be created and precisely combined to derive a statistical model for composite ink fill per target zone. To provide an example, for each drive waveform, many measurements were taken for each nozzle. If a given single measurement of droplet volume is expected to be accurate with a standard deviation of two percent, by taking many measurements, a satisfactorily accurate mean is obtained with reduced variance or standard deviation; That is, again assuming a normal random distribution, the standard deviation decreases according to σ/(n) ^1/2 for the number n of measurements, so four measurements of the droplet volume will halve the standard deviation, and so on. Thus, in one embodiment, software is used to achieve much higher confidence intervals around the expected droplet volume through specifically planned repeated measurements, which helps to substantially reduce measurement errors. Many different measures of satisfaction can be used, but for example, for an embodiment where the resultant fill is expected to fall within ±x%, such as ±0.5% of the target fill, then a measure can be taken for each nozzle and for each different drive waveform. Droplet measurements were obtained with a 3σ (99.73%) confidence interval around the expected droplet volume within the same range (eg ±0.5%) of the mean droplet volume. Perhaps additionally stated, with an accurate statistical model constructed for each of the distinct droplets, it is possible to use known techniques to plan drop combinations based on mathematical combinations of associated statistical models to obtain the aggregated ink fill per target area Nearby higher accuracy (despite drop volume variations from nozzle to nozzle or waveform to waveform). Note that while a normal random distribution is used for the chosen embodiments, any statistical model (e.g., Poisson, Student's-T, etc.) can be used, where the individual distributions can be combined (e.g., by software) to obtain aggregate distribution. Note also that while in some embodiments a 3σ (99.73%) measure is used, in other contemplated embodiments other types of statistical measures are used, such as 4σ, 5σ, or 6σ or not specifically associated with a random distribution measure.

Note that similar techniques can be applied to derive a model of droplet velocity and flight trajectory for each combination of nozzle waveforms. These variables may be further applied in other alternative embodiments.

Any permutations and subsets of the techniques and embodiments described above can be applied to accurately plan for polymeric ink fill in the target zone (ie in a manner planned for a specific composite volume based on per-nozzle droplet volume variation). That is, rather than attempting to average volume differences across nozzles, these differences are understood and used specifically in the print control process to combine different drops (eg from different nozzles or using different drive waveforms) and obtain very Precise ink filling.

In an alternative embodiment, the printhead and/or substrate are "stepped" in a variable amount to appropriately vary the nozzle or nozzles used for each target zone in individual passes to specifically Dispense the desired droplet volume. For example, droplets from one nozzle (eg, having an average drop volume of 9.95 pL) can be compared to droplets from another nozzle (eg, having a mean drop volume of 10.05 pL) by selectively offsetting the printhead or printhead assembly relative to the substrate. pL of mean droplet volume) combined (to obtain an aggregated synthesis of 20.00 pL). Multiple passes are planned such that each target zone receives a specific aggregate fill that matches the desired target fill. That is, each target area (e.g., each well in a row of wells that will form the pixelated features of the display) receives one or more combinations of drop volumes programmed to use different geometric steps of the printhead relative to the substrate. Amplitude to achieve aggregate volume within specified tolerances. In a more detailed feature of this embodiment, given the positional relationship of the nozzles to each other, a Pareto-optimized solution can be calculated and applied, allowing a tolerable amount of volume variation for each target zone within specification, but at the same time, The printhead/substrate movement is planned to maximize the average simultaneous usage of the nozzles for the corresponding target deposition area. The statistical techniques discussed above can be used to ensure that the statistical model of composite (ie, multiple droplet) ink fill falls within any desired tolerance. In an optional refinement, functions are applied such that the number of printhead/substrate passes required for printing is reduced and even minimized to achieve these goals. Reflecting briefly on these various features, since the printing of layers of material on a substrate can be performed quickly and efficiently, fabrication costs are substantially reduced.

Note that in a typical application, the ink-receiving target areas are arrayed, that is, laid out in rows and columns, where the swath described by relative printhead/substrate motion will be in the (array's Ink is deposited in a subset of all rows of the target area but in a manner that covers all columns of the array in a single pass; in addition, the number of rows, columns and printhead nozzles can be very large, for example involving hundreds or thousands Rows, columns and/or printhead nozzles.

Another alternative embodiment addresses the nozzle uniformity problem in a slightly different manner. Make available for each nozzle a set of multiple pre-arranged alternative nozzle firing waveforms with known (and different) drop volume characteristics; for example, four, eight, or another set may be hardwired or otherwise predefined A number of sets of alternate waveforms to provide alternative sets of corresponding sets of slightly different droplet volumes. The per-nozzle volume data (or different data) and any associated statistical models are then used to plan for simultaneous deposition of multiple target zones by determining a set of nozzle waveform combinations for each target zone of the substrate. Again, relying on the specific volume characteristics of each nozzle (and in this case, each combination of nozzle waveforms) and associated distributions, confidence intervals, etc. to achieve a specific fill volume with high confidence; that is, not trying to Instead of correcting for per-nozzle volume variation, the variation is used specifically in combinations to obtain a specific fill volume within a well-understood statistical range. Note that to meet these objectives there will typically be a number of alternative combinations that can be used to deposit the desired range of droplets in each target area of the substrate. In a more detailed embodiment, a "common set" of nozzle waveforms may be shared across some (or even all) of the printhead's nozzles, where per-nozzle drop volumes are stored and available for mixing and matching different drop volumes , to achieve specific padding. As a further option, a calibration stage can be used to select different waveforms in an offline process such as the dynamic incremental measurement process described above, where a specific set of nozzle firing waveforms is selected based on the calibration to achieve a corresponding specific desired volume A collection of properties. Again, in a further detailed embodiment, optimization can be performed to plan in such a way as to improve print time by, for example, maximizing simultaneous nozzle usage or by optimizing some other criterion to minimize the number of scans or printhead passes Print.

Yet another embodiment relies on the use of multiple printheads in a printhead assembly, where each printhead and its nozzles can be offset relative to each other (or equivalently, printing structures with print structures that can each be offset relative to each other) multi-row nozzles). Using such intentional offsets, per-nozzle volume changes can be intelligently combined across the printhead (or row of nozzles) with each pass or scan. Again, there will typically be a large number of alternative combinations that can be used to deposit droplets in each target area of the substrate to achieve the desired range, and in a detailed embodiment, optimization is performed to achieve the desired range by, for example, passing a scanning or printing head through Plan the use of offsets in a way that minimizes the number of nozzles or improves print time by minimizing simultaneous nozzle usage.

Note that one benefit of the technique described above is that by combining droplet volume variations to achieve a specific predetermined target zone fill volume not only in the presence of drop volume variations, but also in the ability to meet desired fill tolerance ranges can be achieved. A high degree of control over precise volumetric quantities and intentional controlled (or injected) variations in those quantities. The inhomogeneity or presence (or speckle) of the geometric pattern from the deposition process that may cause observable patterns can be mitigated by a number of techniques presented herein. That is, slight differences in the target fill volume even at low spatial frequencies may introduce unwanted geometric artifacts that are visible to the human eye and are therefore undesirable. Therefore, in some embodiments, it is desirable to intentionally but randomly vary the resultant fill volume of each target zone or the particular combination of droplets used to achieve the resultant fill in a manner that is still within specification. Using an exemplary tolerance of 49.75pL-50.25pL, rather than simply arbitrarily arbitrarily ensuring that all target zone fills are within that tolerance, it may be desirable for such applications to introduce intentional variation within that range, for example, Any pattern in such a way that changes or differences are not observable to the human eye as a pattern in the resulting operational display. When applied to color displays, an exemplary embodiment deliberately incorporates such fill volume variation in a manner that is statistically independent of at least one of: (a) the x-dimension (e.g., along a row of target regions direction), (b) the y-dimension (e.g., along the direction of a column of target areas), and/or (c) across one or more color dimensions (e.g., for a red target area versus a blue target area, a blue target area to green target area, red target area to green target area independently). In one embodiment, the changes are statistically independent across each of these dimensions. Such variations are believed to represent any fill volume variation imperceptible to the human eye, and thus contribute to the high image quality of such displays. Note that for embodiments using a planned combination of drops from different nozzles produced by a repeatable set of "geometric steps" or offsets in the scan path, for each nozzle (i.e., by The use of subtle but deliberate drop volume variations (generated by multiple alternate firing waveforms for each nozzle) provides a powerful technique for suppressing the potential for speckle without changing the scan path. In one contemplated embodiment, for example, each nozzle is assigned a set of alternate waveforms that produce a corresponding mean volume within ±10.0% of the ideal volume; this can then be determined by using the injected variation of the droplet pattern (either In the case of spots suppressed by the planned combination of drop volumes from different nozzle waveform pairings, or by the injected waveform variation after selecting/programming the nozzle drop combination to achieve a specific fill) according to the exact mean value ( i.e. to achieve the exact intended fill) to plan the combination of droplets from different nozzles. In other embodiments, intentionally different synthetic drop volumes may be pre-placed for each target zone to produce a convergent fill, or different combinations of nozzle drops may be applied along the scan path, or a non-linear scan path may be used, either achieve the same effect. Other variations are also possible.

In addition, whereas conventional drop measurement techniques can take many hours or days and thus lead to errors in the printing process due to possible changes in drop characteristics during long measurement cycles, fast techniques (such as interferometry techniques) and The use of an associative structure (introduced above) facilitates more updates, and thus a more precise dynamic understanding of inter-nozzle and inter-drop volume changes allows the previously described planned combinations to be used with high confidence. For example, while conventional droplet measurement techniques may take many hours to perform, by using non-imaging techniques such as interferometry, droplet measurements can be kept continuously updated, thus enabling precise tracking of process, voltage and temperature (PVT variations ), printhead nozzle degradation, ink changes, and other dynamics that can affect the accuracy of the measurement. By using, for example, a rolling measurement process that hides incremental droplet measurements in the aforementioned substrate loading and unloading times, it is expected that retakes can be made almost continuously (eg, less than every 3-4 hours for each nozzle) and The droplet measurement is updated and thus rendered an accurate model enabling the aforementioned synthetic fill planning. In one embodiment, each nozzle or nozzle is remeasured (eg, from the start) on a periodic basis (eg, every 2 hours to 24 hour period) and preferably at shorter intervals (eg, two hours). Droplets produced by nozzle waveform pairing. Note that not all embodiments require a rolling process, ie, in one embodiment measurements may be taken (or re-taken) during a dedicated calibration process for all nozzles during which printing was interrupted. To provide an example, in one possible embodiment, a printhead assembly with 6,000 nozzles and a combination of 24,000 nozzle waveforms can be measured for 15 seconds during the substrate loading and unloading phases for each 90 second printing cycle, the following case Yes, each iteration checks a different rolling subset of the 24,000 nozzle waveform combinations until all nozzle waveform combinations have been processed, then returns to repeat processing on a round-robin basis; instead, use dedicated In an embodiment of the calibration process, such a printhead assembly may be parked for a certain period of time (eg, 30 minutes) to derive a statistical model for all nozzle waveform combinations before returning to active printing.

Note again that each of the optional techniques and embodiments described above are considered optional to each other, and conversely, it is contemplated that such techniques may be used in any possible permutation or combination in various embodiments optionally be combined. As an example, measurements of drop velocity and/or angle of flight per nozzle/drive waveform may be used to determine a particular combination of nozzle waveforms that produces a distorted drop "average" or a drop that exceeds a threshold based on determining a particular combination of nozzle waveforms. Drop statistics extension to disqualify "wrong" drops for a given combination of nozzle waveforms. To provide another non-limiting example, interferometry or other non-imaging techniques may be used to perform such measurements incrementally and dynamically by combining windows of the nozzle waveform at intermittent intervals (i.e., as the printhead assembly "parking" during substrate loading and/or unloading) to dynamically update velocity and/or flight angle behavior. Clearly, many combinations and permutations are possible based on the permutations presented above.

The examples will help introduce some concepts about intelligent planning of fill volumes for each target zone. Simultaneous deposition of multiple target zones can be planned using per nozzle volume data (or difference data) for a given nozzle firing waveform by determining the set of possible nozzle drop volumes for each target zone. There will generally be many possible combinations of nozzles that can be used to deposit ink drops in multiple passes to fill each target zone to the desired fill volume within narrow tolerances meeting specifications. Returning for a moment to the assumptions introduced in Figure 1A, if the acceptable fill volume per specification is between 49.75pL and 50.25pL (i.e., within 0.5% of the target), many different sets of nozzles/passes could also be used to Achieving an acceptable fill volume includes, without limitation: (a) five passes of nozzle 2 (10.01 pL) to achieve a total of 50.05 pL; (b) a single pass of nozzle 1 (9.80 pL) and nozzle 5 (10.03pL) for a total of 49.92pL; (c) a single pass for nozzle 3 (9.89pL) and four passes for nozzle 5 (10.03pL) for a total of 50.01pL; (d) nozzle 3 ( 9.89pL) with a single pass of nozzle 4 (9.96pL) and a single pass of nozzle 5 (10.03pL) for a total of 49.80pL; and (e) a single pass of nozzle 2 (10.01pL), nozzle Two passes of 4 (9.96 pL) and two passes of nozzle 5 (10.03 pL), for a total of 49.99 pL. Obviously other combinations are possible. Despite the relatively larger statistical error (eg, ±2% of volume) associated with single droplet measurements, the droplet measurement techniques described above can be used to obtain these expected (eg, mean) droplet volumes. Thus, even if only one choice of nozzle drive waveform is available for each nozzle (or all nozzles), the first embodiment described above can be used to cause the printhead to move in a series of planned offsets or "geometric steps." ” is relative to the substrate offset, which applies as many nozzles as possible to deposit droplets during each scan (e.g., in different target zones), but which applies in a specific predetermined way to the already Deposition droplet combination. That is, many combinations of nozzle drop volumes in this assumption can be used to achieve a desired fill volume within a well-understood range of statistical variance that meets specification tolerances, and certain embodiments effectively pass the scanning motion and/or nozzle its selection of drive waveforms to select a specific one of the acceptable droplet combinations for each target zone (i.e., for each specific set of zones), thereby facilitating the use of different rows of target zones for each nozzle and /or simultaneous padding of columns. By selecting the pattern relative to the printhead/substrate motion in such a way that the time for printing to occur is minimized, this first embodiment provides substantially increased manufacturing throughput. Note that this improvement can optionally be in the form of minimizing the number of printhead/substrate scans or "passes", minimizing the original distance moved relative to the printhead/substrate or otherwise making the overall print time way to minimize. That is, printhead/substrate movement (e.g., scanning) can be preplanned and used to fill the target area in a manner that satisfies predefined criteria, such as minimum printhead/substrate pass or scan, in defined dimension(s) Minimum printhead and/or substrate movement, printing in a minimum amount of time, or other criteria.

This approach all applies equally to the assumption of FIG. 1B where the nozzles are not specifically aimed at each target zone. Again, if the acceptable fill volume per specification is between 49.75pL and 50.25pL (i.e. within 0.5% either side of the target), this can also be achieved with many different sets of nozzles/passes Acceptable fill volumes include, without limitation, all of the examples listed above for Figure 1A and an additional example specific to the assumption of Figure 1B where two adjacent nozzles are used in a single pass to fill a specific target Zone, for example, two passes of nozzle 4 (4) (9.96 pL) and nozzle (5) (10.03 pL) and one pass of nozzle (2) (10.01 pL), for a total of 49.99 pL. Again, each such volume may correspond to a statistical average based on many droplet measurements. For example, if nozzles (4), (5) and (2) in this example were associated with characterizing the quoted mean and a 3σ value equal to or less than 0.5% of the quoted mean, then the aggregate fill would also have a value equal to or A 3σ value of ±0.5% less than 49.99 pL usually meets the specified tolerances with high statistical accuracy. Note that for high-definition OLED displays (i.e., with several million pixels), it may not be sufficient to closely match the 3σ (99.73%) value of the fill-tolerance, for example, which statistically indicates that potentially several thousand pixels may Still outside the desired tolerance; for this reason, in many embodiments, a larger measure of expansion (such as 6σ) is matched to the composite fill tolerance, effectively ensuring that each pixel of the high-definition display is substantially compliant with the manufacturer's specification.

These same principles also apply to multiple per-nozzle drive waveform embodiments. For example, in the assumptions set forth in FIG. 1A , each of the nozzles can be driven by five different firing waveforms as identified by firing waveforms A through E, such that the resulting volumetric properties of the different nozzles for the different firing waveforms are given by Table 1A description. Considering only the target zone 104 and only the nozzle (1), it would be possible, for example, by using the predefined firing waveform D (to generate 9.96pL drops from the nozzle (1)) through the first printhead and using the predefined Four subsequent passes of firing waveform E (to generate a 10.01 pL droplet from the nozzle (1)) deposited the 50.00 pL target in five passes, all without any offset in the scan path. Similarly, different combinations of firing waveforms can be used simultaneously in each pass for each nozzle to generate a volume close to the target value in each of the target zones without any shift in the scan path. Table 1A.

These methods all apply equally to the assumptions of FIG. 1B . For example, considering only target zone 104 and nozzles (1) and (2) (i.e., the two nozzles that overlap target zone 154 during the scan), 50.00 can be achieved in three passes pL, for example, the first printhead by using nozzle (1) with predefined waveform B (to achieve a droplet volume of 9.70 pL) and the second nozzle (2) with predefined waveform C (to achieve a droplet volume of 10.10), p. The second printhead (reaches a drop volume of 10.01 pL) by using nozzle (1) and predefined waveform E (reaches a droplet volume of 10.01 pL) and nozzle (2) and a predefined waveform D (reaches a droplet volume of 10.18 pL), and the third printhead by using Nozzle (1) and predefined waveform E (up to a droplet volume of 10.01 pL).

Note that in both the assumption of FIG. 1A and the assumption of FIG. 1B , each target volume may be deposited in a single row of the target zone in a single pass. For example, it would be possible to rotate the printhead ninety degrees and deposit exactly 50.00pL with a single droplet from each nozzle for each target zone in a row, such as using waveform (E) for nozzle (1) and waveform (E) for nozzle (2 ), (4) and (5) using waveform (A) and using waveform (C) for nozzle (3) (10.01pL+10.01pL+9.99pL+9.96pL+10.03pL=50.00pL). It may also be possible to deposit all the drops necessary to achieve the target volume in one pass, even without rotating the print head. For example, nozzle ( 1 ) may be capable of dispensing a drop with waveform D and 4 droplets from waveform E into zone 104 in a single pass.

These same principles also apply to the printhead offset embodiments described above. For example, for the assumptions presented by FIG. 1A , volumetric properties may reflect nozzles for a first printhead (e.g., “Printhead A”) that is combined with four additional printheads (e.g., Printhead A). Heads "B" through "E") are integrated, each driven by a single firing waveform and having individual drop volume characteristics per nozzle. The printheads are collectively organized such that when performing a scan pass, each nozzle identified as a nozzle (1) for the printhead is aligned to travel into a target zone (eg, target zone 104 from FIG. 1A ). printing, each nozzle identified as nozzle (2) from the various printheads is aligned to print into a second target zone (e.g., target zone 105 from FIG. Describe the volume characteristics of different nozzles for different printheads. Alternatively, the printheads may be offset relative to each other using motors that adjust eg the spacing between scans. Considering only the target zone 104 and nozzles (1) on each printhead, it would be possible to deposit 50.00 pL in four passes, e.g. One printhead pass and three subsequent passes in which only printhead E fires drops into the target zone. There can be other combinations using even higher passes which can still produce closer to 50.00 in the target zone The volume of the pL target, for example at 49.75 pL and 50.25 within the pL range. Considering again only the target zone 104 and nozzles (1) on each printhead, it would be possible to deposit 49.83 pL in two passes, e.g. One printhead pass and a second printhead pass in which printheads D and E both fire drops into the target zone. Likewise, different combinations of nozzles from different printheads can be used simultaneously in each pass to produce a volume close to the target value in each target zone without any offset in the scan path. Thus, using multiple passes in this manner would be advantageous for embodiments where it is desired to simultaneously deposit droplets in different target regions (ie, for example, in different rows of pixels). Again, statistical accuracy can be ensured by planning drop measurements in a manner that is calculated to obtain desired statistical properties associated with drop volumes per nozzle and/or per drive waveform and associated average values. Table 1B.

All of this approach applies equally to the assumptions of FIG. 1B . Considering again only target zone 154 and nozzles (1) and (2) on each printhead (i.e. nozzles that overlap target zone 154 during scanning), 50.00 can be deposited in two passes pL, e.g. the first printhead where printheads C and E fire nozzle (1) and printheads B and C fire nozzle (2) passes and the second printhead where printhead C fires nozzle (2) pass. also deposited 49.99 pL in a single pass (obviously, at 49.75 pL and 50.25 pL), for example, where printheads C, D, and E fire nozzle (1) and printheads B and E fire nozzle (2).

It should also be apparent that the use of alternate nozzle firing waveforms, optionally in combination with scan path offsets, dramatically increases the number of drop volume combinations achievable for a given printhead, and by using multiple A printhead (or equivalently, multiple rows of nozzles) further increases these options. For example, in the hypothetical example conveyed by the discussion of Figure 1 above, the combination of five nozzles with their respective intrinsic ejection characteristics (e.g., drop volumes) and eight alternate waveforms could provide nearly thousands of possible drop volume combinations. different collections. Optimizing each set of nozzle waveform combinations and selecting a specific set of nozzle waveform combinations for each target zone (or for each row of print wells in the array) enables further optimization of printing according to desired criteria. In embodiments using multiple printheads (or rows of printhead nozzles), selectively offsetting those printheads/rows also further increases the number of combinations that can be applied per printhead/substrate scan. Again, for these embodiments, this second embodiment selects "acceptable" individual values for each target zone, assuming multiple sets (one or more) of nozzle waveform combinations could alternatively be used to achieve the specified fill volume. A particular one of the group, this selection across the particular one of the target zones generally corresponds to simultaneous printing of multiple target zones using multiple nozzles. That is, by varying parameters to minimize the time that printing takes place, each of these embodiments increases manufacturing throughput and facilitates the number, along(s), of printhead/substrate scans or "passes" required The original distance relative to the printhead/substrate movement of a particular dimension, the total print time is minimized, or to help satisfy some other criterion.

Many other processes can be used or combined with the various techniques introduced above. For example, nozzle drive waveforms can be "tuned" on a per-nozzle basis to reduce variations in droplet volume per nozzle (e.g., by varying drive voltage, ramp-up or down-slope, pulse width, delay time, number of drops used per droplet, etc.) The number of pulses and the corresponding level of the driving pulse are shaped).

While certain applications discussed herein refer to fill volumes in discrete fluidic containers or "wells," the techniques can also be used to deposit other structures relative to a substrate (such as, for example, relative to transistors, vias, diodes, and other electronic components) with a large layout of the "overcoat". In such contexts, the fluid transfer layer material (e.g., will need to cure in place, dry or harden to form a permanent device layer) will spread to some extent, but will ( Given ink viscosity and other factors) still maintain specific characteristics. The techniques herein in this context can be used, for example, to deposit a cover layer, such as a seal or other layer, with specific localized control over the ink fill volume for each target zone. The techniques discussed herein are not limited to specific presented applications or embodiments.

Other variations, advantages and applications from the techniques introduced above will be apparent to those skilled in the art. That said, these techniques can be applied in many different fields, and they are not limited to manufacturing display devices or pixelated devices. A print "well" as used herein refers to any container of a substrate that will receive deposited ink, and thus has chemical or structural properties suitable to restrict the flow of that ink. As will be exemplified below for OLED printing, this may include situations where the fluid containers will each receive respective volumes and/or types of ink; for example, where the technique is used to deposit different colored luminescent In display applications of the material, successive print processes can be performed for each color using each printhead and each ink—in this case, each process can be applied to "every second well" in the array (e.g., for each "blue" color components) or equivalently every second array of each well (which intersperses wells with overlapping arrays for other color components). Each print well is an example of one possible type of target area. Other variations are also possible. Note also that "row" and "column" are used in this disclosure without implying any absolute direction. For example, a "row" of printed wells may extend the length or width of the substrate, or take another approach (linear or non-linear); generally, "row" and "column" will be used herein to refer to each representation direction of at least one independent dimension, but this need not be the case for all embodiments. Also, note that since modern printers can use relative substrate/printhead motion that involves multiple dimensions, the relative motion does not have to be linear in path or velocity, that is, the printhead/substrate relative motion doesn't have to follow a straight line or even Continuous path or constant speed. Thus, a "pass" or "scan" of a printhead relative to a substrate simply refers to iterations involving relative printhead/substrate motion using multiple nozzles to deposit droplets on multiple target areas. However, in many of the embodiments described below for the OLED printing process, each pass or scan may be a substantially continuous linear motion, with each subsequent pass or scan parallel to the next, offset relative to each other by geometric steps. shift. This offset or geometric step may be a difference in pass or scan start position, average position, end position, or some other type of position offset, and does not imply necessarily parallel scan paths. It should also be noted that various embodiments discussed herein refer to the "simultaneous" use of different nozzles to deposit in different target areas (e.g., different rows of target areas); the term "simultaneously" does not Simultaneous droplet ejection is required, rather, simply refers to the concept that different nozzles or groups of nozzles may be used during any scan or pass to mutually exclusively fire ink into target zones. For example, a first set of one or more nozzles may be fired during a given scan to deposit a first droplet in a first row of fluid wells while a second set of one or more nozzles may be fired during this given scan. nozzles fire to deposit a second droplet in the second row of fluid wells. The term "printhead" refers to a monolithic or modular device having one or more nozzles for printing (ejecting) ink toward a substrate. "Printhead assembly" refers by contrast to an assembly or modular element that supports one or more printheads as a group for co-location with respect to a substrate; thus, a printhead assembly in some embodiments may include only a single printhead head, while in other embodiments, such an assembly includes six or more print heads. In some implementations, individual printheads can be offset relative to each other within such an assembly. Note that in typical embodiments used for large-scale manufacturing processes such as flat-panel displays for televisions, the printhead assembly can be very large, incorporating several thousand print nozzles; depending on the implementation, such an assembly can be very large, where , the droplet measurement mechanism discussed here is designed to link around such components to obtain per-droplet measurements. For example, in the case of a printhead assembly having six printheads and approximately 10,000 or more print nozzles, the printhead assembly can be "parked" within the printer, within an off-axis (printing) service station, for use including Various support operations for droplet measurement.

With the major parts of several different embodiments thus presented, this disclosure will be roughly organized as follows. Figures 2A-2E will be used to describe specific droplet measurement configurations for imaging large-scale printhead assemblies. These arrangements may optionally be integrated within a printer (eg a flat panel display fabrication device that prints ink material that will form a permanent thin film layer on a flat panel device substrate). In alternative implementations, these configurations may use three-dimensional linkage of some or all of the optics associated with droplet measurement, for example, in relation to a printer with multiple printheads and thousands of inks already parked in a printer's service station. The printhead assembly that ejects the nozzles is connected. Figures 3A-4D will be used to introduce some general principles related to nozzle uniformity issues, OLED printing/fabrication, and how embodiments address nozzle uniformity issues. These techniques can optionally be used with the mentioned droplet measurement configurations. Figures 5-7 will serve to illustrate the software process that can be used to plan droplet assembly for each target area of a substrate. 8A-8B are used to illustrate the principles associated with building statistical models of drop volume for each nozzle/waveform combination and for using these models to produce aggregated ink fills for each target zone. Notwithstanding the issue of nozzle consistency, these principles can optionally be used in conjunction with droplet measurement to provide a measureable degree of certainty (e.g., 99% or better confidence per target area). ) reliably produces a synthetic ink fill that meets the specified tolerance range (ie, by using the planned droplet combination). Figures 9A-10C are used to present some experimental data, ie, which demonstrate the effectiveness of the proposed planned droplet combination technique in improving target zone filling consistency. Figures 11 - 12 will be used to discuss exemplary applications to OLED panel fabrication and associated printing and control mechanisms. 13A-13C are used to discuss printhead offsets that can be used to vary the combination of droplets deposited by each scan. 14A-15D are used to further discuss different alternative nozzle firing waveforms applied to provide different droplet volumes or combinations. Figures 16-17 will provide additional details regarding the structure and configuration of an industrial printer including a drop measurement device. Figures 18A and 18B, respectively, will be used to discuss certain detailed embodiments of a drop measurement system integrated with the industrial printer, for example. Finally, Figure 19 will be used to discuss techniques for hiding droplet measurement time after other system processing to maximize production time.

2A-2E are used to generally describe techniques for per-nozzle droplet measurement.

More specifically, FIG. 2A provides an illustrative view depicting an optics system 201 and a relatively large printhead assembly 203; the printhead assembly has multiple printheads (205A/205B) each with a large number of individual nozzles (e.g., 207) , where there are hundreds to thousands of nozzles. An ink supply (not shown) is fluidically connected to each nozzle (such as nozzle 207), and piezoelectric transducers (also not shown) are used to eject droplets of ink under the control of per-nozzle electronic control signals . The nozzle design maintains a slightly negative ink pressure at each nozzle (such as nozzle 207) to avoid flooding of the nozzle plate, where an electrical signal for a given nozzle is used to activate the corresponding piezoelectric transducer, for Ink for a given nozzle is pressurized and droplets are thereby expelled from the given nozzle. In one embodiment, the control signal for each nozzle is normally at zero volts at a positive pulse or signal level of a given voltage used for that particular nozzle to eject a droplet for that nozzle (one per pulse); in another embodiment, different correction pulses (or other more complex waveforms) may be used across nozzles. However, in connection with the example provided in FIG. 2A , it should be assumed that it is desired to measure the ejected droplets to be collected by the vessel 209 downwards from the printhead (i.e. in the direction "h" representing the height of the z-axis relative to the three-dimensional coordinate system 208). The droplet volume produced by a particular nozzle (such as nozzle 207) of . Note that in typical applications, the dimension of "h" is typically on the order of 1 millimeter or less, and there are several thousand nozzles to have the corresponding drops measured individually in this way within an operating printer ( eg 10,000 nozzles). Therefore, in order to optically accurately measure each droplet (i.e., a droplet originating from a specific nozzle out of several thousand nozzles in the environment of a large printhead assembly within the approximate millimeter measurement window just described above), at the Certain techniques are used in the disclosed embodiments to precisely position elements of optics assembly 201, printhead assembly 203, or both, relative to each other for optical measurements.

In one embodiment, these techniques utilize a combination of: (a) for precisely positioning the measurement region 215 (e.g., within the dimension plane 213 a) x-y motion control ( 211A ) of at least a portion of the optical system and (b) in-plane optical recovery ( 211B ) (e.g., thereby allowing easy placement of measurement regions next to each other despite the large printhead surface area any nozzle). Thus, in an exemplary environment with approximately 10,000 or more print nozzles, the motion system is capable of positioning the optical nozzles in, for example, 10,000 or more discrete positions near the discharge path of each respective nozzle of the printhead assembly. at least part of the system. As will be discussed below, two contemplated optical measurement techniques include shadow graphics and interferometry. With each technique, optics are typically adjusted in place to maintain precise focus over the measurement region to capture droplets in flight (eg, to effectively image the drop's shadow in the case of a shadow map). Note that typical droplets can be on the order of microns in diameter, so optical placement is typically quite precise and presents challenges with respect to the relative positioning of the printhead assembly and measurement optics/measurement zone. In some embodiments, to assist with this positioning, optics (mirrors, prisms, etc.) are used to orient the light capture path for sensing originating below the dimension plane 213 of the measurement region 215 so that the measurement optics can be placed must be close to the measurement area without interfering with the relative positioning of the optics system and printhead. This allows effective position control under supervision in a manner not limited to the millimeter scale deposition height h at which the drop is imaged, or the large scale x and y width occupied by the printhead. With interferometry-based droplet measurement techniques, the split beams are incident from different angles as small droplets create interference patterns that are detectable from viewing angles that are generally orthogonal to the optical path; The path of α leaves an angle of approximately ninety degrees but also traps light in a way that utilizes in-plane optical recovery to measure droplet parameters. Other optical measurement techniques may also be used. In yet another variation of these systems, it is optional and advantageous to have the motion system 211A be an xyz-motion system, which allows selective engagement and release of the drop measurement system without moving the printhead assembly during drop measurement. Briefly, in industrial manufacturing with one or more large printhead assemblies, in order to maximize manufacturing uptime, it is expected that each printhead assembly will be "parked" in a service station at any time to perform one or more maintenance Function; given the sheer size of the printhead and the number of nozzles, it may be expected to perform multiple maintenance functions at once on different parts of the printhead. For this reason, in this embodiment it may be advantageous to move the measurement/calibration device around the printhead, but not vice versa. [This then also allows the engagement of other non-optical maintenance treatments, eg as desired, in relation to another nozzle. ] To assist these actions, the printhead assembly can optionally be "parked" by a system that identifies the particular nozzle or range of nozzles to be subjected to optical alignment. Once the printhead assembly, or a given printhead, is stationary, the motion system 211A is engaged to move at least a portion of the optics system relative to the "parked" printhead assembly to detect a drop ejected from a particular nozzle The measurement zone 215 is precisely positioned at the location of ; the use of a moving z-axis allows selective engagement of light recovery optics from just below the plane of the printhead, instead of or in addition to optical alignment to facilitate other maintenance operations. Perhaps stated otherwise, the use of the xyz motion system allows the droplet measurement system to be selectively engaged independently of other testing or testing equipment used in the service station environment. Note that not all embodiments require this configuration; for example, movement of both the measurement assembly and the printhead assembly (e.g., for drop measurement purposes, the printhead assembly relative to the Measuring x-y motion of the z-axis motion of the component) mechanism. Other alternatives are also possible, wherein only the printhead assembly moves and the measurement assembly is fixed, or wherein parking of the printhead assembly is unnecessary.

Typically, the optics used for droplet measurement will include a light source 217, an optional set of light delivery optics 219 that direct light from the light source 217 to the measurement region 215 as desired, one or more light sensors 221 And a set of recovery optics 223 directing light for measuring the drop(s) from the measurement zone 215 to one or more photosensors 221 . While also providing a container, such as the vessel 209, to collect the ejected ink, the motion system 211A is optionally associated with the vessel 209 in a manner that allows post-drop measurement light to be directed from the measurement zone 215 around the vessel 209 to a sub-plane location. Move one or more of these elements together. In one embodiment, light delivery optics 219 and/or light recovery optics 223 use mirrors that direct light to/from measurement region 215 along a vertical dimension parallel to droplet travel, wherein the motion system Each of the elements 217 , 219 , 221 , 223 and vessel 209 as an integral unit is moved during the measurement; this arrangement has the advantage of not requiring recalibration of the focus with respect to the measurement zone 215 . As noted at 211C, the light delivery optics are also used to optionally supply source light from a location below the dimension plane 213 of the measurement region, for example, where, for measurement purposes, the light source 217 and (a plurality of ) light sensors 221 direct light on either side of the vessel 209, as generally shown. As noted at 225 and 227, the optics system may optionally include lenses for focusing purposes and photodetectors (eg, for non-imaging techniques that do not rely on processing many pixelated "pictures"). Note again that the optional use of z-motion control for the optics assembly and vessel allows for the optional engagement and release of the optics system, as well as the proximity of the measurement zone 215 to any nozzle at any point in time while the printhead assembly is "parked". accurate locating. Not all embodiments require such parking of the printhead assembly 203 and xyz movement of the optics system 201 . For example, in one embodiment, laser interferometry is used to measure drop properties where either printhead assembly (and/or optics system) is within or parallel to the deposition plane (e.g., within plane 213 or parallel to plane 213) to image droplets from each nozzle; other combinations and permutations are possible.

Figure 2B provides a flow of processing associated with droplet measurement for some embodiments. This process flow is designated generally in FIG. 2B using reference numeral 231 . More specifically, as indicated by reference numeral 233, in this particular process, the printhead assembly is first parked in a service station (not shown), such as a printer or deposition device. The drop measurement device is then engaged with the printhead assembly by selective engagement of some or all of the optics system by moving from below the deposition plane to a position where the optics system is capable of measuring individual droplets (235). Such movement relative to one or more optics system components opposite the parked printhead can optionally be performed in the x-, y-, and z-dimensions, at 237 .

As previously noted, even a single nozzle and associated drive waveform (i.e., the pulse(s) or signal level(s) used to eject the droplet) can produce droplet volumes, trajectories that vary slightly from droplet to droplet and speed. In accordance with the teachings herein, in one embodiment, a drop measurement system indicated at 239 obtains n measurements per drop of a desired parameter to derive a statistical confidence level regarding the desired property of the parameter. In one implementation, the measured parameter may be volume, while for other implementations, the measured parameter may be flight speed, flight trajectory, or another parameter, or a combination of multiple of these parameters. In one implementation, "n" may vary for each nozzle, while in another implementation, "n" may be a fixed number of measurements to be performed for each nozzle (eg, "24"); In an implementation, "n" refers to the minimum number of measurements so that additional measurements can be performed to dynamically adjust the statistical properties of the measured parameters, or to refine confidence levels. It is clear that many variations are possible. For the example provided in FIG. 2B , it should be assumed that drop volumes are being measured so that an exact mean value and tight confidence intervals representing the expected drop volume from a given nozzle are obtained. This enables (using multiple nozzles and/or drive waveforms) the ability to optionally map drops to Combine for planning. As noted in optional processing blocks 241 and 243, interferometry or shadow mapping are contemplated optical measurement processes that ideally enable instantaneous or near-instantaneous measurement and calculation of volume (or other desired parameter); by With such rapid measurements, it becomes possible to frequently and dynamically update volume measurements, for example, to account for changes over time in ink properties (including viscosity and constituent materials), temperature, power supply fluctuations, and other factors. Depending on this, a shadow map typically characterizes the image of a droplet captured using, for example, a high-resolution CCD camera as the light sensor mechanism; where a droplet can be precisely imaged at multiple locations (e.g. using a strobe light source) on a single Image processing software typically involves a finite amount of time for calculating droplet volume while the image is capturing the frame, so imaging of sufficient droplet population from a large printhead assembly (e.g., with thousands of nozzles) can take several hours. Hour. Interferometry, which relies on multiple binary photodetectors and the detection of the interferometric pattern spacing based on the outputs of these detectors, is a non-imaging technique (i.e. does not require image analysis) and is therefore much faster than shadowmap or other techniques by many amounts of time Drop volume measurements are produced at the scale (e.g. 50x); for example, with a 10,000 nozzle printhead assembly, it is expected that a large measured population for each of several thousand nozzles can be obtained in minutes, which is presented for It is feasible to perform droplet measurements frequently and dynamically. As mentioned above, in an alternative embodiment, droplet measurement (or measurement of other parameters such as trajectory and/or velocity) may be performed as a periodic intermittent process, wherein the droplet measurement system is controlled according to a schedule. Bonded, or between substrates (eg, as substrates are loaded or unloaded), or stacked relative to other components and/or other printhead maintenance processes. Note that for embodiments that allow alternate nozzle drive waveforms to be used in a manner specific to each nozzle, a fast measurement system (such as an interferometer system) readily allows for each nozzle and for each alternate The statistical population of the drive waveforms is derived, thereby facilitating the planned drop combination of droplets produced by the individual nozzle waveform pairings, as mentioned above. According to reference numerals 245 and 247, by nozzle-to-nozzle (and/or nozzle-waveform pair-to-pair) measurement of the expected droplet volume to an accuracy better than 0.01 pL, it becomes possible for very Accurate droplet assembly planning, where synthetic filling can also be planned to 0.01pL resolution, and where the target volume can be maintained within a specified error (e.g., tolerance) of 0.5% of the target volume or better; as As indicated by reference numeral 247, the measured population for each nozzle or pair of nozzle waveforms is planned in one embodiment to generate a reliability distribution model for each such nozzle or pair of nozzle waveforms, i.e. , with a 3σ confidence level (or another statistical measure such as 4σ, 5σ, 6σ, etc.) less than the normative maximum filling error. Once sufficient measurements have been taken for individual drops, the fill involving combinations of these drops can be estimated and used to plan printing in the most efficient manner possible ( 248 ). As indicated by separation line 249, drop measurement may be performed by intermittently switching back and forth between active printing processing and measurement and calibration processing.

FIG. 2C shows a flow 251 of one possible process associated with planning of droplet measurements per nozzle (or per nozzle waveform pairing) and/or initialization of statistics used to model the behavior of each nozzle. As indicated at reference numeral 253, first in the process is received data specifying a desired tolerance range, which may be established, for example, according to manufacturer specifications. In one embodiment, for example, the tolerance or acceptability range may be specified as ±5.0% of a given target; in another embodiment, another range may be used (e.g., ±2.5% of the desired target droplet size , ±2.0%, ±1.0%, ±0.6% or ±0.5%). It is also possible to specify a range or set of acceptable values in alternative ways. Regardless of the canonical approach, depending on the desired tolerance and droplet system measurement error, a threshold amount of measurement is then identified ( 255 ). Note that, as indicated above, this number can be chosen to achieve several goals: (a) to obtain a population of droplet measurements large enough to provide a reliable estimate of the desired droplet parameters (e.g. mean volume, velocity, or trajectory). measure; (b) obtain a population of droplet measurements large enough to model variations in droplet parameters (such as standard deviation or σ for a given parameter); and/or (c) obtain sufficient data , thereby identifying nozzles or nozzle waveform pairs that have a greater than expected error in order to disqualify the use of a particular nozzle/nozzle waveform pair during the print process. Measurements are then performed ( 257 ) using droplet measurement system 259 (eg, using the optical techniques discussed herein) using any planned number of droplet measurements or desired measurement criteria or associated minimums defined thereby. Per process decision block 261, measurements for each nozzle (or nozzle waveform) are then performed until specified criteria are met. If the measured quantity satisfies the programmed criteria, the method then ends with processing block 269 . If additional measurements need to be performed, the measurement process loops until sufficient measurements have been obtained, as indicated in Figure 2C.

Figure 2C illustrates a number of exemplary processing variations. First, as indicated by reference numeral 263, the measurement process is optionally applied to all nozzles (and/or all possible nozzle/waveform combinations) of the printhead assembly. This is not required for all embodiments. For example, in one embodiment (see discussion of FIGS. 14A-15C below), a potentially infinite number of drive waveform changes may be used to affect parameters of ejected droplets for a given nozzle; instead of exhaustively testing For each possible waveform, the droplet measurement process can experiment with a predetermined set of waveforms representing a broad distribution of possible waveforms, through an iterative interpolation search process for selecting a small number of waveforms (e.g., it is possible to generate ± 10% of the mean droplet volume). In another embodiment, if based on initial measurements, a given nozzle is considered defective (e.g., drop volume has a distribution greater than 20% from the desired mean), then that nozzle may optionally be excluded upon further consideration. Nozzles (or nozzle waveform pairs). In yet another example, if a print scan that does not actually use a particular nozzle is planned, it may be advantageous to perform dynamic additional drop measurements only for nozzles that are actively used in the planned scan, at least until a certain type of error or variance criterion. Again, many possibilities exist; function block 263 simply indicates that the processing applied need not involve all nozzles (or nozzle waveform pairs). Next, reference numeral 265 indicates that, in one embodiment, the minimum criterion may relate to a minimum threshold that may be different for each nozzle or pair of nozzle waveforms. To cite some examples pertinent to this functionality, in one embodiment, droplet measurements are performed for a given nozzle or pair of nozzle waveforms, and a measure of distribution spread (such as variance, standard deviation, or another measure) is calculated, wherein performing over Measurement of the raw threshold until the spread metric satisfies predetermined criteria; as should be appreciated, if the minimum is, for example, 10 drop measurements per nozzle, and if 10 drop measurements for a particular nozzle yields a variance greater than expected, Additional measurements may then be performed uniquely for a given nozzle until the desired expansion is achieved (eg 3σ < 1.0% of mean volume), or until some maximum number of measurements have been performed. This embodiment may, for example, result in a different number of measurements per nozzle, ie where the measurement iterations are planned to achieve some minimum criteria (eg, in this example, a minimum number of measurements and an expansion measure less than a threshold). Again, as indicated at 267, it is also possible to use position extrapolation in drop measurement planning, for example, to obtain "exact 24" drop measurements per nozzle (or nozzle waveform), or to obtain x Quantities are measured, and so on. Ultimately, regardless of the measurement management technique, it is possible to apply measurements to qualify (pass) or disqualify a particular nozzle or combination of nozzle waveforms. Referring again to possible implementation options, following performing a threshold number of measurements, particular nozzles or nozzle waveforms may be qualified or disqualified based on the measurement data at reference numeral 270 . For example, if the ideal drop volume in an application is 10.00pL, nozzle/nozzle waveform pairs that do not produce an average drop volume of 9.90pL-10.10pL can be immediately disqualified; the same approach can be taken for statistical extensions, e.g. , following a minimum number of measurements, can immediately disqualify any nozzle/nozzle waveform pairing that produces a droplet spread (eg, variance, standard deviation, etc.) greater than 0.5%, and so on. Again, many implementation examples exist.

FIG. 2D is a schematic diagram of one implementation of a droplet measurement system as predicted by optical techniques, generally designated by reference numeral 271 . More specifically, printhead 273 is shown in cross section with five enumerated print nozzles arranged as a row of nozzles that will eject fluidic ink downward in the z-direction (as indicated by label legend 274 ). . A light source 275A is arranged to one side of the printhead so as to illuminate a measurement zone 278 through which the drop will pass for measurement; in the case of FIG. 2D this measurement zone (and some or all of the optics system) is arranged to measure Droplets originating from the nozzles (3) of the printhead. Light source 275A is depicted as being external to one lateral side of printhead 273, thereby generating a light path 277 that will direct light into the light measurement zone (i.e., within a height on the order of millimeters represented by the variable h to illuminate any number of nozzles , without disturbing the print head 273). As indicated by reference numeral 275B, in one embodiment, the light source may instead be advantageously mounted below the deposition plane 289 (and the upper periphery of the vessel 286), thereby providing visibility of the optics relative to the path of the droplets from any nozzles. Relatively easy fixed distance positioning; again, while five nozzles are depicted in FIG. 2D, in one embodiment, there are several hundred to several nozzles or more. The below deposition plane light generation facilitates easy positioning of the optics system relative to any nozzle of the depicted printhead 273 with optics for directing illumination to the drop measurement zone 278, and for selection of the drop measurement system Sexual engagement and release (e.g. with respect to optional service stations, as described above). In the depicted example, mirror 285A is used to redirect light from light source 275B to be incident on droplets within measurement zone 278 traveling from printhead 273 toward vessel 286 . Other means of positioning the path of the optics relative to the light source 275B may also be used, such as, by way of non-limiting example, prisms, fiber optic cables, and the like. For implementations using imaging measurement techniques such as shadow mapping, the light source 275A/275B may be a strobe thermal light source or a monochromatic source. Note that FIG. 2D also shows a path 275C along which the source is outside the page of the figure and light is directed into or out of the page of the figure with or without the aid of light path routing optics (such as along numbered legend 274 The light from the third origin position directed by the described y-dimension); for example, where relying on interferometry, this localization framework can be used, where the detection of the interference pattern arises from the path orthogonal to the illumination (or at another angle to it). Regardless of the relative arrangement of the illumination sources, it should be noted that the light is directed along the light path 277 and the illumination plane 290 intermediate the location of the printhead 273 and the deposition plane 290, and is directed by the light path routing optics 285B to the measurement light ( ie from the measured droplet) is routed from the imaging plane to a photodetector mounted below the deposition plane 289 . Again, this allows narrow direction and focusing of light despite the large print head size and relatively small height h. Additionally, as with the light path routing optics 285A, mirrors, prisms, fiber optics, or other light redirecting devices and techniques can be used to accomplish this light-recovery sub-plane routing of deposition. As can be seen in FIG. 2D , the measurement light is directed to focusing optics 279 (eg a lens) and onto a light detector 280 . The distance of the light path between the focusing optics and the measurement region is identified by the distance f, representing the focal length of the optics system. As mentioned previously, droplet measurement (depending on optics technology) is expected to provide the precise focus required to properly image the droplet, and for this reason, for the system represented in FIG. Optics 279 , drop measurement zone 278 and vessel 286 lens all move as an integral unit to measure drops from different nozzles, as represented by the depicted connection to common chassis 283 . Light sources 275A/275B and light source guide lights may optionally also be coupled to the chassis depending on the embodiment.

Note that in an interferometry-based system, also conceptually represented in FIG. 2D , the light sources 275A/275B (or generating optical path 275C) may be lasers used to generate an interference pattern, wherein the beams at some point along the optical path is divided into two or more different components, which are used to generate interference patterns. Additional details regarding these optics and the use of multiple beams for creating interferometric patterns will be discussed further below in connection with FIG. 18B; source.

FIG. 2E shows another schematic diagram of an implementation of a droplet measurement system as predicted by optical techniques, generally designated by reference numeral 291 . More specifically, the implementation seen in FIG. 2E relies on interferometry to measure droplet parameters such as volume. As before, this configuration relies on printhead 273 , measurement zone 278 , chassis 283 and vessel 286 . In this embodiment, however, a laser is used specifically as light source 292 to generate a beam of light directed via illumination path 293 to the measurement region. Note that typically two or more beams are steered in this way, as will be explained further below. An interference pattern is generated in the droplet in the measurement zone 278 and is observed from a direction substantially orthogonal to the illumination path 293 , as indicated by reference numeral 297 . This same relationship (measurements from directions not parallel to the illumination path) is also represented by FIG. 2D (for example using path 275C), but in FIG. Next, the measuring light is guided negatively downwards. Note that photodetector 295 is non-imaging in the sense that (although multiple photodetectors are typically used), no camera is used, and image processing is not used to identify droplet outlines within the pixelated image, essentially This improves the speed of detection and measurement; that is, the interferometric method simply measures the change in the interference pattern as the drop passes through the region of overlapping beams, where the drop volume can be deduced from the obtained results. Using more than two beams (or increased number of detectors) facilitates measuring droplet trajectories and velocities, among other parameters. As before, the light source 292, vessel 286 and light detector 295 can be moved as a unit (ie, via the common chassis 283), facilitating preservation of precise optical path parameters. In one implementation, movement of the optics system is again performed in three dimensions relative to the "parked" printhead assembly to selectively engage and release the drop measurement device while the printhead assembly is in the service station , and easily and precisely position a drop measurement device to measure any one of the thousands of nozzles of a large-scale printhead.

As mentioned above, with a suitable configuration of the droplet measurement device or system, industrial printers (such as those used for OLED device fabrication) can enable the nozzles and the droplets they bring to be reproducibly calibrated, allowing very precise planning in any target zone droplet combination. That is, measurement equipment can be used to quickly derive an accurate, tightly grouped statistical distribution of volumes for each nozzle and for each waveform used by the nozzle, which enables precise planning for achieving the composite fill droplet combination. In other embodiments, these same techniques are used to build models for drop velocity and flight angle so that models for these parameters can be applied in the printing process.

Note that any of these various techniques (as well as any printing or synthetic filling techniques introduced in this disclosure) may appear in different products and/or different layers of fabrication. For example, Figure 3A represents a number of different implementation levels, designated collectively by the reference numeral 301, each of which represents a possible discrete implementation of the techniques introduced above. First, the techniques described above can be embodied as instructions stored on a non-transitory machine-readable medium, as represented by graph 303 (eg, software for controlling a computer or a printer). Second, according to computer icon 305, these technologies may be implemented as part of a computer or network, such as within a company that designs or manufactures components for sale or for use in other products. For example, the techniques described above could be implemented as design software by a company that consults with or performs designs for high-definition television (HDTV) manufacturers; alternatively, the techniques can be used directly by such manufacturers to Make TVs (or displays). Third, as previously described and exemplified using storage medium graphic 307, the previously described techniques may take the form of printer instructions, such as stored instructions or data, which, when acted on, will cause the printer to program fluid flow as discussed above. Drop polymerization techniques are used to fabricate one or more component layers. Fourth, as represented by manufacturing equipment icon 309, the techniques disclosed above may be implemented as part of a manufacturing device or machine, or in the form of a printer within such a device or machine. For example, a printer in which drop measurements as well as externally supplied "layer data" is automatically converted by the machine (e.g., by using software) to print using the techniques described here transparently optimizes/accelerates the printing process Command way to sell crafting machines or customize them. Such data can also be computed offline and then reapplied in a reproducible manner in a scalable, pipelined manufacturing process that manufactures many units. It should be noted that the particular depiction of the manufacturing device icon 309 represents one exemplary printer device that will be discussed below (eg, with reference to FIGS. 11-12 ). The techniques described above may also be embodied as an assembly, such as an array 311 of multiple parts that would be sold separately; for example, in FIG. are separated and sold for incorporation into final consumer products. The depicted device may have one or more layers (eg, color component layers, semiconductor layers, sealing layers, or other materials) deposited, for example, according to the methods described above. The technology described above can also be embodied in the form of, for example, the mentioned end consumer products, for example, in the form of a portable digital device 313 (such as an electronic board or a smart phone, for example), as a television display 315 (for example, an HDTV ) or other types of devices in the form of display screens. For example, FIG. 3A uses a solar panel graphic 317 to indicate that the processes described above can be applied to other forms of electronic devices, for example to deposit each target area structure such as one or more layers that make up an individual unit of an aggregated device, or Covering layers (e.g. sealing layers for TVs or solar panels). Obviously, there can be many examples.

Without limitation, the techniques described above may be applied to any of the layers or components shown in FIG. 3A. For example, one embodiment of the technology disclosed herein is an end-consumer device; a second embodiment of the technology disclosed herein is one that includes fabrication of combined control layers that will use specific nozzle volumes to obtain data specific to each target zone fill. device; the nozzle volume can be predetermined or measured and applied in situ. Another embodiment is a deposition machine that prints one or more inks using the techniques described above, eg, using a printer. These techniques can be implemented on one machine or on more than one machine, such as a network or train of machines where different steps are applied at different machines. All such embodiments and others may, individually or collectively, utilize the techniques presented in this disclosure.

As represented in Figure 3B, in one application, a printing process may be used to deposit one or more layers of material onto a substrate. The techniques discussed above can be used to generate printing control instructions (eg, electronic control files that can be transmitted to the printer) for subsequent use in manufacturing the device. In one particular application, these instructions can be adapted to an inkjet printing process useful in printing a layer of low-cost, scalable organic light-emitting diode ("OLED") displays. More specifically, the techniques described can be applied to deposit one or more light-emitting or other layers of such OLED devices, such as "red", "green" and "blue" (or other) pixelated color components or such devices other light-emitting layers or components. This exemplary application is non-limiting, and the techniques can be applied to the fabrication of many other types of layers and/or devices, whether those layers are light emitting or not and whether the device is a display device or not. In this exemplary application, various conventional design constraints of inkjet printheads challenge the processing efficiency and film coverage uniformity of the various layers of OLED stacks that can be printed using various inkjet printing systems. Those challenges can be addressed through the teachings in this article.

More specifically, FIG. 3B is a plan view of one embodiment of a printer 321 . The printer includes a printing assembly 323 for depositing fluid ink onto a substrate 325 . Unlike a printer that prints text and graphics, printer 321 in this example is used in the manufacturing process to deposit fluid ink that will have a desired thickness. That is, in a typical manufacturing application, the ink bears the material that will be used to form a permanent layer of the finished device, where the layer has a specific desired thickness. The thickness of the layer produced by depositing fluid ink depends on the volume of ink applied. Inks typically feature one or more materials that will form part of the finished layer, formed as monomers, polymers, or materials carried by a solvent or other delivery medium. In one embodiment, these materials are organic. After ink is deposited, the ink is dried, cured, or hardened to form a permanent layer; for example, some applications use ultraviolet (UV) curing to convert liquid monomers into solid polymers, while other treatments dry the ink to remove Solvent and leave conveyed material in a permanent location. Other treatments are also possible. Note that there are many other variations that differentiate the depicted printing process from conventional graphics and text applications; for example, in some embodiments, the ambient atmosphere is controlled to be something other than air or Deposition of the desired material layer is performed in an environment that additionally excludes unwanted particulates. For example, as will be described further below, one contemplated application uses a fabrication mechanism that encloses the printer 321 within a gas chamber such that printing is performed in the presence of a controlled atmosphere, such as an inert environment such as Including but not limited to nitrogen, any inert gas, and any combination thereof.

As further seen in FIG. 3B , printhead assembly 323 includes a number of nozzles, such as nozzle 327 . Note that in FIG. 3B, the printhead assembly 323 and nozzles are depicted as opening outward from the top of the page for purposes of illustration, but in fact these nozzles are facing down toward the substrate, and from the perspective of FIG. 3B Views are hidden from view (ie, Figure 3B shows what is actually a cross-sectional view of printhead assembly 323). The nozzles are seen arranged in rows and columns (such as the exemplary row 328 and column 329 ), but this is not required for all embodiments, ie some implementations use only a single row of nozzles (such as row 328 ). In addition, individual rows of nozzles may be provided on individual printheads, each printhead being (optionally) individually shiftable relative to each other, as introduced above. In applications where a printer is used to manufacture part of a display device, such as materials for each of the red, green, and blue color components of a display device, the printer typically uses a dedicated print for each different ink or material head assemblies, and the techniques discussed herein can be applied individually to each corresponding printhead or printhead assembly.

FIG. 3B illustrates one printhead assembly 323 (ie, with one or more individual printheads not separately depicted). In this example, printer 321 includes two distinct motion mechanisms that may be used to position printhead assembly 323 relative to substrate 325 . First, a traveler or carriage 331 may be used to mount the printhead assembly 323 and allow relative movement as indicated by arrow 333 . If present, the motion mechanism may also optionally transport the printhead assembly 323 to a service station; such a service station is indicated at 334 in FIG. 3B. Second, however, a substrate transport mechanism may be used to move the substrate relative to the slip ring along one or more dimensions. For example, as represented by arrow 335, the substrate transport mechanism may allow movement in each of two orthogonal directions, such as according to x and y Cartesian dimensions (337), and may optionally support substrate rotation. In one embodiment, the substrate transport mechanism includes an air bearing table for selectively securing and permitting movement of the substrate on gas bearings. Note also that the printer optionally allows rotation of printhead assembly 323 relative to slip ring 331 , as represented by rotation graphic 338 . Such rotation allows the apparent spacing and relative configuration of the nozzles 327 to be changed relative to the substrate; And/or rotation of the substrate may change the relative spacing of the nozzles in a direction along or perpendicular to the scan direction. In an embodiment, the height of the printhead assembly 323 relative to the substrate 325 may also be varied, for example along the z Cartesian dimension into or out of the view direction of FIG. 3B .

The two scan paths are illustrated separately in FIG. 3B with directional arrows 339 and 340 , respectively. Briefly, the substrate motion mechanism moves the substrate back and forth in the directions of arrows 339 and 340 as the printhead moves in geometric steps or offsets in the direction of arrow 333 . Using these combinations of movements, the nozzles of the printhead assembly can reach any desired area of the substrate to deposit ink. As previously mentioned, ink is deposited into discrete target areas of the substrate in a controlled manner. These target areas may be arranged in an array, ie arranged in rows and columns, such as optionally along the depicted y and x dimensions, respectively. Note in this figure that each row of nozzles (such as row 328) is seen to be perpendicular to the rows and columns of the target area, i.e., such that a row of nozzles is swept with each scan in the direction of each row of target area, across the target area of the substrate Each column of (for example, along direction 339). This need not be the case for all embodiments. To gain motion efficiency, subsequent scans or passes then reverse this motion direction, addressing the target areas of the columns in reverse order, ie along direction 340 .

The placement of the target zone in this example is depicted with the highlighted area 341 seen on the right side of the figure in the enlarged view. That is, numeral 343 is used to designate each of the two rows of pixels, each pixel having red, green and blue color components, and numeral 345 is used to designate the pixel in the column orthogonal to the scan direction (339/340). of each. In the top left pixel, it is seen that the red, green and blue components will occupy different target regions 347, 349 and 351 as part of respective overlapping arrays of regions. Each color component in each pixel may also have associated electronics, such as indicated by numeral 353 . In cases where the device to be manufactured is a backlit display (for example, as part of a conventional type LCD television), these electronics can control the selective masking of light filtered with red, green and blue regions. In case the device to be manufactured is a new type of display, i.e. the red, green and blue regions directly generate their own light with corresponding color characteristics, these electronics 353 may include patterned electrodes and controls for the desired light generation and light Additional material layers that contribute to the properties.

FIG. 3C provides a closed cross-sectional view of printhead 373 and substrate 375 taken with respect to the printhead assembly of FIG. 3B from the viewpoint of line C-C. . More specifically, numeral 371 generally designates a printer, while numeral 378 designates a row of print nozzles 377 . Designate each nozzle using a number in parentheses such as (1), (2), (3), etc. A typical printhead typically has a plurality of such nozzles, such as 64, 128 or another number; in one embodiment, 1000-10000 or more nozzles may be arranged in one or more rows. As before, the printhead in this embodiment is moved relative to the substrate to achieve a geometric step or offset between scans in the direction referenced by arrow 385 . Depending on the substrate motion mechanism, the substrate may be moved orthogonally to this direction (e.g., into and out of the page with respect to the view of FIG. 3C ), and in some embodiments, also in the direction indicated by arrow 385 . Note that Figure 3C also shows columns 383 of each target area 379 of the substrate, in this case arranged as "wells" that will receive deposited ink and keep the deposited ink within the structural confines of each well . For the purposes of FIG. 3C it will be assumed that only one ink is represented (eg, each depicted well 379 represents only one color of the display, such as a red color component, other color components and associated wells are not shown). Note that the drawings are not to scale, for example, see the nozzles numbered from (1) to (16) while seeing the wells lettered from (A) to (ZZ), representing 702 wells. In some embodiments, nozzles will be aligned to each well such that the depicted printhead with 16 nozzles will simultaneously scan using relative printhead/substrate motion into and out of the page from the perspective of FIG. 3C Ink is deposited in the direction of arrow 381 in up to 16 wells. In other embodiments, as previously described (see, for example, FIG. 1B ), the nozzle density will be much greater than the target area density, and with any scan or pass, a subset of nozzles (for example, a group of one to many , depending on which nozzles pass through each target zone) will be used for deposition to each respective target zone. For example, again using the illustrative example of sixteen nozzles, nozzles (1)-(3) may be used to deposit ink in a first target zone and nozzles (7-10) may be used simultaneously to deposit ink in a second target zone. It is possible to deposit ink in a mutually exclusive manner for a given pass.

Conventionally, it is possible to operate the printer using the sixteen depicted nozzles to simultaneously deposit ink in up to sixteen rows of wells, moving back and forth with subsequent scans as necessary until, for example, five are deposited in each well. Droplets, the printhead advances as needed using a fixed stride that is an integer multiple of the width of the swath across which the scan is made. However, the techniques provided by this disclosure take advantage of the inherent variation in droplet volume produced by different nozzles in combinations suitable to produce specific fill volumes for each well. Different embodiments rely on different techniques to achieve these combinations. In one embodiment, the geometric strides are varied to achieve different combinations, and are freely something other than an integer multiple of the width described by the printhead swath. For example, the geometric step may be 1/160th of the ^swath of the printhead, which in this example actually represents well The relative displacement between the substrate and the printhead is one-tenth of the pitch of a row. Depending on the specific combination of droplets desired in each well, the downshift offset or geometric step can be different, e.g. an assumed offset of 5/16 ^ths of the swath of the printhead, corresponding to an integer pitch of the wells ; This change can be continued in positive and negative steps as needed to deposit ink to achieve the desired fill volume. Note that offsets of many different types or sizes are possible, and that the step size need not be fixed between scans or be a specific fraction of the well spacing. In many manufacturing applications, however, it is desirable to minimize print time in order to maximize production rate and, where possible, minimize cost per unit of manufacturing; to this end, in certain embodiments, such that the total number of scans, geometric Printhead motion is planned and sequenced in such a way that the total number of steps, the size of the offset or geometric steps, and the cumulative distance traversed by the geometric steps are minimized. These and other measures can be used individually, together, or in any desired combination to minimize the total printing time. In embodiments where independently shiftable rows of nozzles are used (e.g., multiple printheads), the geometric stride may be represented in part by offsets between printhead or nozzle rows; Combinations of offsets (eg, for a fixed stride of a printhead assembly) such offsets can be used to achieve variable size geometry strides and thus deposit combinations of droplets into each well. In embodiments where variations in nozzle drive waveforms are used solely, conventional fixed steps may be used, drop volume variations are achieved using multiple printheads and/or multiple printhead passes. As will be noted below, in one embodiment, the nozzle drive waveform can be programmed for each nozzle between drops, thus allowing each nozzle to generate and contribute individual drop volumes to each well within a row of wells .

Figures 4A-4D serve to provide additional detail regarding the dependence on a particular droplet volume in achieving a desired fill volume.

FIG. 4A presents an illustrative view 401 of a printhead 404 and two related illustrations seen below the printhead 401 . This printhead is optionally used in embodiments that provide a non-fixed geometric stride of the printhead relative to the substrate, and therefore uses numeral 405 to denote that a particular printhead nozzle (e.g., with nozzle (1) depicted in FIG. 1 - Offsets of (a total of 16 nozzles of 5) aligned with different target zones (five in this example, 413, 414, 415, 416 and 417). Returning attention to the example of Figure 1A, if the nozzles (1)-(16) respectively produce 9.80, 10.01, 9.89, 9.96, 10.03, 9.99, 10.08, 10.00, 10.09, 10.07, 9.99, 9.92, 9.97, 9.81 Drop volumes of 10.04 and 9.95 pL (e.g., average drop volume), and if it is desired to deposit 50.00 pL per target area, ±0.5 percent of this value, the printhead can be used to medium-deposited droplets, using geometric strides of 0, -1, -1, -2, and -4, respectively, resulting in (expected mean) total fill values per region of 49.82, 49.92, 49.95, 49.90, and 50.16 pL , as depicted in the figure; clearly this is within the expected tolerance range of 49.75-50.25 pL for each delineated target zone. Each stride in this example is expressed incrementally relative to the previous position, although other measures could be used. Depending on the desired variation in volume per droplet, it is still possible to virtually ensure that the fill will be within the desired tolerance range; for example, by taking as many droplet measurements as described above (e.g. 20-30 droplet measurements per nozzle or more), The expected variance of the volumes per droplet can be made very small, allowing high confidence in the distribution of the expected resultant volumes. Thus, as seen, precise tuned filling can be achieved with a high degree of reliability using droplet combination in a deliberate manner dependent on the individual droplet volumes and the desired filling for each target zone.

Note that this graph can be used to represent nozzle drive waveform variations and/or the use of multiple printheads. For example, if nozzle reference numbers (1)-(16) refer to the droplet volumes for a single nozzle produced by sixteen different drive waveforms (i.e., using waveforms 1-16), then theoretically one can simply use Different drive waveforms, eg, waveform numbers 1, 2, 3, 5, and 9 for the target zone 413, are used to achieve each region fill volume. In practice, since process variations can result in different per-nozzle characteristics, the system will measure the drop volume for each nozzle for each waveform, and will intelligently plan drop combinations based on this. where nozzle references (1)-(15) refer to a plurality of printheads (eg, references (1)-(5) refer to a first printhead, references (6)-(10) refer to a second printhead and In the embodiments of reference numerals (11)-(15) referring to the third printhead), the offset between the printheads can be used to reduce the number of passes or scans; for example, the rightmost target zone 417 can have Three droplets deposited in , including droplet volumes of 10.03, 10.09, and 9.97 pL (printhead (1), offset 0; printhead (2), +1 offset; and printhead (3), +2 offset). It should be apparent that combinations of these different techniques facilitate many possible combinations of specific volume droplets to achieve specific fill volumes within tolerances. Note that in Figure 4A, the variation in polymerized ink fill volume between target zones is small and within tolerance, ie in the range of 49.82 pL to 50.16 pL.

Figure 4B shows an illustrative view 421 of a series of printhead scans, where each scan is perpendicular to the direction of arrow 422, where the nozzles are represented by different rectangles or bars, for example by reference numerals 423-430. In conjunction with this figure, it should be assumed that the printhead/substrate relative motion proceeds in a sequence of variable-sized geometric steps. Note again that, in general, each stride will specify a sweep across multiple columns of target areas (e.g., pixels) over a single column of five regions represented on the plane of the page (and denoted by reference numerals 413-417) . The scans are shown in top-down order, including the first scan where the printhead is seen shifted to the right relative to the substrate such that only nozzles (1) and (2) are aligned with target zones 416 and 417 respectively 423. Within each print scan description (such as box 423), each nozzle is represented by a circle filled with solid black to indicate that the nozzle will fire when it is over a specifically delineated target area during the scan, or "hollow". ”, that is filled with white, to indicate that the nozzle will not be firing at the relevant time (but it may be for other target areas encountered on the scan). Note that in this embodiment, each nozzle is fired in a binary fashion, that is, each nozzle is made to fire or not fire according to any adjustable parameter, such as to deposit a predetermined Droplet volume. A "binary" firing scheme is optionally employed for any of the embodiments described herein (ie, eg, adjusting waveform parameters between droplets where multiple firing waveforms are used). In the first pass 423, nozzle (1) is seen firing to deposit a 9.80 pL droplet into the second rightmost target zone while nozzle (2) is fired to deposit 10.01 pL into the rightmost target zone 417 drop. Scanning continues across other columns of target areas (eg, other rows of pixel wells), depositing drops as appropriate. After the first pass 423 is complete, the printhead advances a geometric step of -3, which moves the printhead to the left relative to the substrate, so that the nozzle (1) will now be in the second scan in the opposite direction to the first scan Go through target zone 413 during 424 . During this second scan 424 the nozzles ( 2 ), ( 3 ), ( 4 ) and ( 5 ) will also pass through regions 414 , 415 , 416 and 417 respectively. The black filled circles see that nozzles (1), (2), (3) and (5) will be fired at the appropriate times to deposit droplet volumes of 9.80pL, 10.01pL, 9.89pL and 10.03pL respectively, Corresponds to the intrinsic properties of nozzles (1), (2), (3) and (5). Also note that in any one pass, nozzles in a row of nozzles used to deposit ink will do so in a mutually exclusive manner into each target zone, e.g. for pass 424 nozzle (1) is used to 413 (but none of target areas 414-417), use nozzle (2) to deposit ink in target area 414 (but none of areas 413 or 415-417), use nozzle (3) to Ink is deposited in zone 415 (but none of areas 413-414 or 416-417), and the nozzle (5) is used to deposit ink in target zone 417 (but none of areas 413-416). The third scan, represented by numeral 425, advances the printhead effectively by one line of the target zone (-1 geometric steps), so that nozzles (2), (3), (4), (5) and (6) will respectively Areas 413, 414, 415, 416, and 417 are traversed during the scan; the solid filled nozzle graphic indicates that during this pass, each of the nozzles (2)-(6) will be actuated to fire droplets, respectively producing Desired droplet volumes of 10.01, 9.89, 9.96, 10.03 and 9.99 pL.

If the printing process were to stop at this point in time, area 417 would for example have a fill of 30.03 pL (10.01 pL + 10.03 pL + 9.99 pL) corresponding to three droplets, while area 413 would have a fill of 19.81 pL (9.80 pL + 10.01 pL) pL), corresponding to two droplets. Note that the scanning pattern in one embodiment follows a back and forth pattern represented by arrows 339 and 340 of Figure 3B. After passing 426-430 (or multiple columns of scans of such areas) across these target areas, respectively deposit: (a) 10.01 pL, 0.00 pL, 0.00 pL, 10.08 pL, and 10.09 pL of liquid in area 413 drops, corresponding to the passage of nozzles (2), (3), (4), (7) and (9) in successive scans; (b) 0.00pL, 0.00pL, 10.03pL, 10.00pL and 10.07pL droplets, corresponding to each pass of nozzles (3), (4), (5), (8) and (10) in consecutive scans; (c) 9.89pL, 9.96pL, 10.03pL in region 415 , 9.99pL, 10.09pL and 0.00pL droplets, corresponding to the passage of nozzles (4), (5), (6), (9) and (11) in successive scans; (d) 0.00pL in region 416 , 9.99pL, 10.08pL, 10.07pL and 0.00pL droplets, corresponding to the passage of nozzles (5), (6), (7), (10) and (12) in successive scans; and (e) area 417 The 9.99pL, 0.00pL, 10.00pL, 0.00pL and 0.00pL droplets in , correspond to the passage of nozzles (6), (7), (8), (11) and (13) in successive scans. Again, note that the nozzle in this example is used with only a single firing waveform (i.e. such that its drop volume characteristics do not change between scans) and in a binary fashion, such as in the fifth scan 427 , the nozzle ( 7 ) did not fire, producing no droplet (0.00 pL) for region 417 , while on subsequent scans it fired, producing 10.08 pL droplet for region 416 .

As seen in the graph at the very bottom of the page, this hypothetical scan process produces the desired aggregate fill of 49.99pL, 50.00pL, 49.96pL, 49.99pL, and 50.02pL, easily added at the target value (50.00pL). Or minus ½ percent (49.75pL—50.25pL) within the desired range. Note that in this example, nozzles are used to deposit ink substantially simultaneously into multiple target areas for each scan, planned for each delineated area (i.e., as identified by the graphics at numerals 413-417) The specific combination of droplet volumes allows for the deposition of multiple droplets in each target zone over multiple passes. Together the eight depicted passes are related to drop volumes for particular sets (or combinations) that produce fill volumes within specified tolerances (e.g., in the case of region 413 from nozzles (1), (2), (2), (7) and (9)), but it is also possible to use other possible sets of droplets. For example, for region 413, five droplets (5 x 10.01pL = 50.05pL) from nozzle (2) would alternatively be used; however, this substitution would be inefficient as an additional scan would be required because (eg) Nozzle (3) (9.89pL) cannot be used extensively at the same time during this time (i.e. the result from five droplets from this nozzle would be 5 x 9.89 = 49.45pL, within the desired tolerance range outside). In the example taken over from Figure 4B, specific scans and their sequences are chosen to use less printing time, fewer passes, smaller geometric strides and potentially small aggregated geometric stride distances or according to some other criteria. Note that the depicted example is for illustrative discussion only, and that it may be possible to further reduce the number of scans using the presented liquid volume to less than eight scans to achieve the target fill. In some embodiments, the scan process is planned in a manner to avoid a worst case scenario with the required number of scans (eg, one scan per row of target areas with the printhead rotated ninety degrees). In other embodiments, this optimization is applied to an extent based on one or more maxima or minima, e.g. Schedule scans in a way that results in the fewest number of scans possible.

Figure 4C presents a diagram similar to Figure 4B, but corresponding to the use of different nozzle drive waveforms for each nozzle. As will be appreciated, in inkjet printheads ink is typically ejected using piezoelectric actuators that extend and contact fluid reservoirs to eject ink from respective print nozzles. Ink is typically held in the reservoir at slightly negative pressure to avoid flooding the nozzle plate, where a voltage pulse is applied to the actuator to eject a droplet with properties dependent on the size and shape of the voltage pulse. Different pulse characteristics can thus produce different volumes, velocities and other characteristics of the ejected droplets. In Figure 4C, it should be assumed that different pre-planned voltage pulse waveforms have been determined to produce a range of different drop volumes (and associated drop volume probability distributions). Scans are generally referred to by reference numeral 441, wherein each of scans 443-447 occurs in a direction perpendicular to bars 443-447; within each scan bar (e.g., box 443), the reference designation represents a particular print Head nozzles, letter designations denote different waveforms for a particular nozzle. For example, the designation "1-A" indicates the first drive waveform "A" used for the actuator for nozzle (1), and the designation "1-C" indicates the first driving waveform "A" for the actuator for nozzle (1). The third drive waveform "C". Note that any desired number of waveforms may be tested during the calibration process to select a waveform that produces a desired drop volume (or collection of drops) that matches the ideal target drop volume. In Figure 4C, for example, testing multiple waveforms for nozzle (1) can yield results for two particular waveforms (e.g., "A" and "C" each yielding close to the desired 10.00pL average (e.g., 9.94pL average and expected droplet volume of 10.01 pL average). That is, if testing to exactly match the ideal drop volume (e.g. 10.00pL) does not yield the expected average, there is an option to include the desired idealized volume (e.g. for nozzles (1), (3), (4) and two or more waveforms of 9.94pL/10.01pL, 9.99pL/10.01pL, 10.03pL/9.95pL, and 9.95/10.04pL as described in (5). Notwithstanding the above examples, different nozzle drive waveforms may be used to combine different droplets to specifically plan aggregate fill for each target zone within desired tolerances. Note that for the example of FIG. 4C, it is not necessary to offset the printhead assembly between scans to achieve these combinations; however, in many embodiments, the use of multiple nozzle waveforms can be combined with fractional trace width offsets to achieve A number of possible droplet combinations are found that can be used to produce the target fill using the minimum number of scans (and thus minimum print time per substrate). In FIG. 4C , it can be seen that the described process produces very neatly grouped hypothetical fills (eg, 49.99 pL - 50.02 pL expected fill volumes).

Figure 4D presents an illustrative view 471 of a printhead 474 and two related illustrations seen below the printhead 474 similarly to Figure 4A, but here with nozzles not specifically aligned to a particular well. This printhead is optionally used in embodiments that provide a non-fixed geometric stride of the printhead relative to the substrate, and therefore uses numeral 472 to denote that a particular printhead nozzle (eg, having nozzle (1) depicted in the figure - A total of 16 nozzles of (5)) are aligned with different target zones (two in this example, 474 and 475). Again following the assumption of Figure 4A, if the nozzles (1)-(16) respectively produce 9.80, 10.01, 9.89, 9.96, 10.03, 9.99, 10.08, 10.00, 10.09, 10.07, 9.99, 9.92, 9.97, 9.81 , 10.04, and 9.95 pL drop volumes, and if it is desired to deposit 50.00 pL per target area, ±0.5 percent of this value, the printhead can be used to deposit droplets in three passes or scans, respectively, using 0 , -1 and -3 geometric steps, and each scan fired one or two droplets into each target zone. This would result in total fill values per region of 49.93 and 50.10, as depicted in the figure, again clearly within the desired tolerance range of 49.75 - 50.25 pL for each depicted target region. Thus, as seen, the method is equally applicable to the case of nozzles that are not aligned to the well, and can be used in a deliberate manner that depends on the individual droplet volumes and the desired fill for each target zone. drop combination to achieve precise adjusted fill. Additionally, as described above for the assumptions of FIG. 4A , this graph can be used to represent nozzle drive waveform changes and/or the use of multiple printheads. For example, if nozzle reference numbers (1)-(16) refer to the droplet volumes for a single nozzle produced by sixteen different drive waveforms (i.e., using waveforms 1-16), then it is theoretically possible simply by using the different drive waveforms to obtain the fill volume for each region. Those skilled in the art will see that the same approach as described above with reference to FIGS. Droplets are deposited simultaneously into each well. Finally, note that Figures 4A-4D also represent relatively simple examples; in a typical application, there may be hundreds to thousands of nozzles and millions of target zones. For example, in the fabrication of color components per pixel (e.g., each pixel has red, green and blue wells, pixels are arranged at 1080 horizontal lines of vertical resolution and horizontally resolved In 1920 vertical lines at the rate of 1920) applying the disclosed technique, there are approximately six million wells (ie, three overlapping arrays each of two million wells) that may receive ink. Next-generation televisions are expected to quadruple or more this resolution. In such processes, in order to improve the speed of printing, a printhead may use thousands of nozzles for printing, for example, there will typically be a surprising number of possible print process variations. The simplified examples presented above serve to introduce the concepts, but it should be noted that given the astonishing number presented in typical combinations, the changes represented by reality television applications are quite complex, and print optimization is often done by software and using complex mathematics operation to apply. Figures 5-7 serve to provide non-limiting examples of how these operations may be applied.

Exemplary processing for planning printing is described using FIG. 5 . The number 501 is used generally to refer to this process and associated methods and apparatus.

More specifically, the droplet volume for each nozzle (and for each waveform if multiple drive waveforms are applied) is specifically determined (503). Such measurements can be performed, for example, using a variety of techniques including, without limitation, optical imaging or laser imaging or non-imaging devices built into the printer (or factory resident machine) that image the droplets during flight. Measure (eg, during a calibration print operation or a real-time print operation) and accurately calculate volume based on drop shape, velocity, trajectory, and/or other factors. In particular embodiments, as described, each measurement is only approximately accurate since the drop volume from a single nozzle produced using even a single drive waveform may vary from drop to drop. To this end, droplet measurement techniques can be used to derive a statistical model for the droplet from each nozzle and for each combination of nozzle waveforms, each specific droplet volume expressed as The mean of the waveform is expected for the droplet volume. Other measurement techniques may also be used, including printing the ink and then using post-print imaging or other techniques to calculate individual droplet volumes based on pattern identification. Alternatively, the identification may be based on data supplied by the printer or printhead supplier, eg based on measurements taken at the factory and supplied machine (or online) long before the manufacturing process. In some applications, drop volume characteristics may change over time, such as depending on ink viscosity or type, temperature, nozzle clogging or other degradation, or due to other factors; thus, in one embodiment, dynamic Droplet volume measurements are performed, for example, upon power-up (or upon the occurrence of other types of power cycling events), with each new print of a substrate, upon expiration of a predetermined time, or based on another calendar or non-calendar time. In one embodiment, as described above, the measurement is performed continuously on an intermittent basis by performing the measurement for a moving window of print nozzle and nozzle waveform combinations each time a new flat panel substrate is loaded or unloaded, to obtain dynamic renew. As represented by numeral 504, this data (measured or provided) is stored for use in the optimization process.

In addition to per-nozzle (and optionally per drive waveform) drop volume data, information about the desired fill volume for each target zone is received (505). This data can be a single target fill value to be applied to all target areas, individual target fill values to be applied to individual target areas, each row target area, or each column target area, or a value broken down in some other way. For example, when applied to fabricate a single "coverage" layer of material that is large relative to an individual electronic device structure (such as a transistor or via), such data could consist of a single thickness to be applied to the entire layer (e.g., software then This is converted into the desired ink fill volume for each target zone based on predetermined conversion data specific to the relevant ink); in this case, the data can be converted into Equivalent to the common value for each target zone or consisting of multiple target zones). In another example, the data may represent a specific value (eg, 50.00 pL) for one or more wells, providing or interpreting range data based on context. As should be understood from these examples, the desired fill may be specified in many different forms, including, without limitation, as thickness data or volume data. Additional filtering or processing criteria may also optionally be provided to or performed by the receiving device; for example, as previously mentioned, random variations in fill volume may be injected by the receiving device into one or more provided thickness or volume parameters Medium to render the linear pattern invisible to the human eye in the finished display. Such variations can be performed in advance (and provided as per-target zone fills that differ from zone to zone), or can be derived intelligently and transparently from the receiving device (eg, by a downstream computer or printer).

Based on the target fill volume for each zone and the individual drop volume measurements (i.e., each printhead nozzle and each nozzle drive waveform), the process then optionally proceeds to calculating various droplet combinations, which The sum is the fill volume within the desired tolerance (ie, per processing block 506 ). As mentioned, target population data can be provided for this range, or can be "understood" based on the context. In one embodiment, the range is understood to mean ± one percent of the fill value provided. In another embodiment, the range is understood to be ±0.5 percent of the fill value provided. Clearly, many other possibilities exist for tolerance ranges, both larger and smaller than these exemplary ranges.

Here, examples will help convey one possible method for computing each set of possible droplet combinations. Returning to the simplified example described earlier, it should be assumed that there are five nozzles, each with a corresponding assumed average droplet volume of 9.80pL, 10.01pL, 9.89pL, 9.96pL, and 10.03pL, and that it is desired to deposit Target volume of 50.00pL±½% (49.75pL—50.25pL). This method begins by determining the number of droplets that can be combined to achieve but not exceed the tolerance range, and for each nozzle the minimum and maximum number of droplets from that nozzle that can be used in any acceptable variation. For example, in this assumption, given the minimum and maximum droplet volumes of the nozzles under consideration, no more than a single droplet from nozzle (1), two droplets from nozzle (3) and The four drops will be expected to be available in any combination. This step limits the number of combinations that need to be considered. Providing such constraints on the ensemble considerations, the method then considers combinations of the required number (five in this example) of droplets, taking each nozzle in turn. For example, the method starts with nozzle (1) first, it being understood that the only acceptable combinations involving this nozzle are those with one droplet or less from this nozzle given the calculated average value as a feature. Considering combinations involving a single drop from this nozzle, the method then considers the minimum and maximum drop volumes for the other corresponding nozzle waveform combinations under consideration; for example, suppose nozzle (1) is determined to be Yielding an average drop volume of 9.80pL, no more than one drop from nozzle (3) or two drops from nozzle (4) can be used in combination with a drop from nozzle (1) to achieve the desired tolerance range. The method proceeds to consider the combination of the droplet from nozzle (1) and four droplets from other nozzles, for example four droplets from nozzles (2) or (5), three droplets from nozzle (2) combination of a droplet and a droplet from the nozzle (4) and so on. Considering a combination involving only nozzle (1), to simplify the discussion, any of the following different combinations involving the first nozzle could potentially be used within tolerance:

{1(1), 4(2)}, {1(1), 3(2), 1(4)}, {1(1), 3(2), 1(5)}, {1(1) ), 2(2), 1(4), 1(5)}, {1(1), 1(2), 1(3), 2(5)}, {1(1), 1(2) , 1(4), 2(5)}, {1(1), 1(2), 3(5)}, {1(1), 1(3), 3(5)}, {1(1 ), 2(4), 2(5)}, {1(1), 1(4), 3(5)} and {1(1), 4(5)}.

In the mathematical expressions set forth above, the use of parentheses indicates a set of five droplets representing a combination of droplet volumes from one or more nozzles, each parenthesis within these parentheses identifying a specific nozzle; for example, The expression {1(1), 4(2)} represents one droplet from nozzle (1) and four droplets from nozzle (2), 9.80pL+(4×10.01pL)=49.84pL, which is expected Produces a composite fill within the specified tolerance. In fact, based on various average values, the method in this example considers the highest number of droplets from the nozzle (1) that can be used to generate the desired tolerance, evaluates combinations involving this highest number, and reduces the number by one , and repeated consideration of the processing. In one embodiment, this process is repeated to determine all possible sets of non-redundant droplet combinations that can be used. When combinations involving nozzle (1) have been fully explored, the method advances to combinations involving nozzle (2) instead of nozzle (1) and repeats the process, and so on, testing the combined to determine whether it can achieve the desired tolerance range. For example in this example, the method has determined that combinations of two or more droplets from nozzle (1) cannot be used, so it is never considered in various combinations involving one droplet from nozzle (1) and Combination of four droplets from other nozzles begins. The method actually evaluates whether four droplets from nozzle (2) can be used, determines that it can {1(1), 4(2)}, then decreases this number by one (three droplets from nozzle 2) , and it is determined that this number can be used in combination with a single droplet from nozzle (4) or (5), providing acceptable sets of {1(1), 3(2), 1(4)}, {1( 1), 3(2), 1(5)}. The method then further reduces the number of acceptable droplets from the nozzle (2) by one, and evaluates {1(1), 2(2)....} and then {1(1), 1(2)....} and so on. Once the combination involving (2) is considered in combination with the droplets from nozzle (1), the method then takes the next nozzle, nozzle (3), and considers the combination, and determine the only acceptable combination given by {1(1), 1(3), 3(5)}. Once all combinations involving droplets from nozzle (1) have been considered, the method then considers 5-droplet combinations involving droplets from nozzle (2) but not nozzle (1), e.g. {5(2) }, {4(2), 1(3)}, {4(2), 1(4)}, {4(2), 1(5)}, {3(2), 2(3)}, {3(2), 1(3), 1(4)} etc.

It should also be noted that the method works equally well in cases where the nozzle can be driven with multiple firing waveforms, each producing a different droplet volume. These additional nozzle waveform combinations simply provide additional drop volume averages for use in selecting a set of drop combinations that are within target volume tolerances. The use of multiple firing waveforms can also improve the efficiency of the printing process by making available a larger number of acceptable drop combinations and thereby increasing the likelihood that drops will be fired simultaneously from a majority of the nozzles on each pass. In the case of nozzles with multiple drive waveforms and also using geometric strides, the selection of a set of drop combinations will combine both the geometric offset to be used in a given scan and the nozzle waveform to be used for each nozzle .

Note that the brute force approach has been described for narrative purposes, and that in practice a surprising number of possible combinations will often be presented, e.g. where the number of nozzles and target zones is large (e.g. more than 128 each) . However, such calculations are well within the capabilities of high-speed processors with appropriate software. And, note that there are various mathematical shortcuts that can be applied to reduce calculations. For example, in a given embodiment, the method may exclude from consideration any combination that would correspond to using less than half of the available nozzles in any one pass (or alternatively, may limit consideration to Combinations that minimize volume differences across the target region (TR). In one embodiment, the method determines only certain sets of droplet combinations that will yield an acceptable composite fill value; in a second embodiment, the method exhaustively computes the droplet combinations that will yield an acceptable composite fill value every possible set of . An iterative approach may also be used, where, in multiple iterations, a print scan is performed and the volume of ink still to be deposited to achieve the desired tolerance range(s) is taken into account for the purpose of optimizing the next subsequent scan. Other treatments are also possible.

Note also that, as an initial operation, if the same fill value (and tolerance) applies to each target zone, compute combinations once (for example, for one target zone) and store these possible droplet combinations for each target zone The initial use of the case is sufficient. This is not necessarily the case for all ensemble calculation methods and for all applications (eg, in some embodiments, acceptable fill ranges may vary for each target zone).

In another embodiment, the method uses mathematical shortcuts such as approximation, matrix mathematics, random selection, or other techniques to determine the set of acceptable droplet combinations for each target zone.

As represented by process block 507, once the set of acceptable combinations has been determined for each target zone, the method then effectively Schedule scans. This particular set selection is performed in a manner where a particular geometry (one for each target zone) saves processing by using at least one scan to simultaneously deposit drop volumes in multiple target zones. That is, ideally, the method selects for each target zone a specific set that represents a particular combination of drop volumes in such a way that the printhead can simultaneously print into multiple rows of target zones at once. A particular drop selection in the selected combination represents a print process that matches predetermined criteria, such as minimum print time, minimum number of scans, minimum size of geometric stride, minimum aggregated geometric stride distance, or other criteria. These criteria are indicated by numeral 508 in FIG. 5 . In one embodiment, the optimization is Pareto optimal, selecting the particular set in such a way that each of the scan coefficient, the aggregated geometric stride distance, and the geometric stride size are minimized, in that order. Again, this selection of a particular set may be performed in any desired manner, a number of non-limiting examples being discussed further below.

In one example, the method selects from each set for each target region a droplet corresponding to a particular geometric stride or waveform applied to all regions under consideration, and then it divides this droplet from the available The set subtracts and determines the remainder. For example, if the selection of available sets is initially {1(1), 4(2)}, {1(1), 3(2), 1(4)}, { 1(1), 3(2), 1(5)}, {1(1), 2(2), 1(4), 1(5)}, {1(1), 1(2), 1 (3), 2(5)}, {1(1), 1(2), 1(4), 2(5)}, {1(1), 1(2), 3(5)}, { 1(1), 1(3), 3(5)}, {1(1), 2(4), 2(5)}, {1(1), 1(4), 3(5)} and {1(1), 4(5)}, then this embodiment will subtract one droplet (1) from this initial set to obtain the remainder specified by the first of the five target regions, from which initial set Subtract one droplet (2) from this initial set to obtain the remainder specified by the second of the five target regions, and subtract one droplet (3) from this initial set to obtain the remainder specified by the third of the five target regions. the rest of and so on. This evaluation will represent a geometry stride of "0". The method will then evaluate the remainder and repeat the process for the other possible geometric strides. For example, if a geometry stride of "-1" is then applied, the method will subtract one droplet (2) from the initial set for the first of the five target regions, and from Subtract one droplet (3) etc. from the initial set, and evaluate the remainder.

Upon selecting a specific geometry step (and nozzle firing) as part of print planning, the method analyzes the various remainders according to a score or priority function and selects the geometry step with the best score. In one embodiment, a score is applied to weight more heavily the stride that (a) maximizes the number of simultaneously used nozzles and (b) maximizes the minimum number of remaining combinations for the affected target zone. For example, scanning using droplets from four nozzles during scanning would be more advantageous than scanning using droplets from only two nozzles. Likewise, if one is considering the remaining combinations of 1, 2, 2, 4 and 5 for each target zone for one possible stride and 2, 2, 2 for each target zone for a second possible stride , 3, and 4 remaining combinations using the subtraction process discussed above, the method will weight the latter more heavily (ie, the largest minimum number is "2"). In practice, appropriate weighting coefficients can be gradually generated empirically. Obviously, other algorithms can be applied, and other forms of analysis or algorithmic shortcuts can be applied. For example, matrix mathematics (eg, using eigenvector analysis) can be used to determine particular droplet combinations and associated scan parameters that satisfy predetermined criteria. In another variation, other formulas may be used that take into account, for example, the use of planned random fill variations to mitigate the linear pattern.

Once a particular set and/or scan path has been selected as per number 507 , the printer actions are sequenced, via number 509 . For example, it should be noted that if the aggregate fill volume is the only consideration, a set of droplets can generally be deposited in any order. If printing is planned to minimize the number of scans or passes, the order of the geometric strides can also be chosen to minimize printhead/substrate motion; for example, if the acceptable scan in the example is assumed to involve {0, +3, Relative geometric strides of -2, +6 and -4}, then these scans can be reordered to minimize printhead/substrate motion and thus further improve printing speed, e.g. order scans as {0, +1 , +2, 0 and +4} stride sequence. The second sequence of geometric strides {0, +1, +2, 0 and +4} involved an aggregate stride increment of 7 compared to the first sequence of geometric strides involving an aggregate stride increment distance of 15 distance, which promotes a faster printer response.

As represented by numeral 510, for applications involving a large number of rows of target areas that will receive the same target population, a particular solution can also be represented as a repeatable pattern that is then reproduced within a subset of areas of the substrate. For example, if in an application there are 128 nozzles arranged in a single row and 1024 rows of targets, it is expected that the optimal scan pattern can be determined for a subset of the 255 rows of targets or less; thus, in this example, The same print pattern can be applied to four or more subset areas of the substrate. Certain embodiments thus utilize repeatable patterns as represented by optional processing block 510 .

Note the use of the non-transitory machine-readable medium icon 511; this icon indicates that the methods described above are optionally implemented as instructions for controlling one or more machines (e.g., software or firmware for controlling one or more processors) ). The non-transitory media can include any machine-readable physical media such as flash drives, floppy disks, tape, server storage or mass storage, dynamic random access memory (DRAM), compact disks (CDs), or other local or remote storage. This storage can be embodied as part of a larger machine (such as resident memory in a desktop computer or printer) or isolated (such as a flash drive or standalone storage that will later transfer files to another computer or printer) . Each of the functions described with reference to FIG. 5 may be implemented as part of a combined program or as independent modules, stored together on a single media representation (eg, a single floppy disk) or on multiple separate storage devices.

As represented by numeral 513 in FIG. 5, once the planning process is complete, data effectively representing a set of printer instructions will have been generated, including nozzle firing data for the printheads and printheads that will support the firing pattern. Instructions for moving relative to the base. Effectively representing scan paths, scan sequences, and other data, this data is an electronic file (513) that can be stored for later use (e.g., as depicted by non-transitory machine-readable medium icon 515), or immediately Applied to control the printer (517) to deposit ink representing the selected combination (specific set of nozzles per target zone). For example, the method could be applied to a stand-alone computer, with the instruction data being stored in RAM for later use or downloaded to another machine. Alternatively, the method can be implemented by the printer and dynamically applied to the "incoming" data to automatically plan scans based on printer parameters such as nozzle-drop-volume data. Many other alternatives are possible.

6A-6D provide diagrams generally related to the nozzle selection and scan planning process. Note again that the scan does not have to be continuous or linear in direction or speed of movement, and does not have to go all the way from one side of the substrate to the other.

A first block diagram is indicated by numeral 601 in FIG. 6A; this diagram represents many of the exemplary processes discussed in the preceding description. The method first begins by retrieving from memory a set of acceptable drop volume combinations for each target zone, via number 603 . These sets may be computed dynamically, or may be precomputed using software on different machines, for example. Note the use of a database icon 605, which represents a locally stored database (eg, stored in local RAM) or a remote database. The method then effectively selects for each target zone (607) a particular one of the acceptable sets. In many embodiments, this selection is indirect, that is, the method processes acceptable combinations to select specific scans (eg, using the techniques mentioned above), and it is these scans that actually define the specific set. However, by planning the scan, the method selects a specific set of combinations for each respective target zone. This data is then used to sequence scans and finalize motion and shot patterns (609), as mentioned above.

The middle and right diagrams of Figure 6A illustrate several processing options for planning scan paths and nozzle firing patterns, and indeed, selecting specific droplet combinations for each target zone in a manner indicative of print optimization. As represented by numeral 608, the illustrated technique represents only one possible method for performing this task. Via number 611 , the analysis may involve determining the minimum and maximum usage of each nozzle (or nozzle-waveform combination, in those cases where the nozzle is driven by more than one firing waveform) in acceptable combinations. If a particular nozzle is bad (eg, does not fire or fires at an unacceptable trajectory), that nozzle can optionally be excluded from use (and consideration). Second, if a nozzle has a very small or very large desired drop volume, this can limit the number of drops that can be used from that nozzle in acceptable combinations; numeral 611 represents a pre-processing that reduces the number of combinations that will be considered . As represented by numeral 612, processing/shortcuts may be used to limit the number of sets of droplet combinations to be evaluated; for example, instead of considering "all" possible droplet combinations for each nozzle, the method may be configured to Combinations involving less than half of the nozzles (or another number of nozzles, such as ¼), where more than half of the nozzles are from any particular nozzle waveform, are optionally excluded, or indicate high variance in droplet volume or indicate application of A combination of simultaneous large differences in droplet volume. Other metrics may also be used.

Subject to any limitations on the number of sets to be calculated/considered, the method then proceeds to calculate and consider acceptable droplet combinations, via number 613 . As mentioned with numbers 614 and 615, various processes may be used to plan the scan and/or otherwise efficiently select a particular set of droplet volumes per target region (TR). For example, as introduced above, one approach takes a scan path (e.g., a specific geometric stride selection) and then considers the maximum selected across the least remaining set of all TRs under consideration; this approach can be advantageous for making subsequent Those scan paths (alternative geometry strides) are weighted to maximize their ability to cover multiple target areas in one scan. Alternatively or additionally, the method may advantageously weight the geometric stride that maximizes the number of nozzles used at one time; returning to the simplified five-nozzle discussed above, versus a scan that would fire only three nozzles in a pass or By comparison, a scan that would apply five nozzles to a target zone can be more advantageously weighted. Therefore, in one embodiment, the following algorithm may be applied by software:

.

In this exemplary equation, "i" represents a particular choice of geometric stride or scan path, w ₁ represents one empirically determined weight, w ₂ represents a second empirically determined weight, #_RemCombs _{TR , i} represents the The number of remaining combinations for each target zone for scan path i, and #_Simult.Nozzles _i represents a measure of the number of nozzles used for scan path i; note that this latter value need not be an integer, e.g. if each TR (for example, to hide potentially visible artifacts in display devices), a given scan path can be characterized by a varying number of nozzles used per column of target areas, for example an average value or a certain other metrics. Note also that these factors and weightings are illustrative only, i.e. weightings and/or considerations different from these could be used, using only one variable instead of the other, or using completely different algorithms.

Figure 6A also shows many other options. For example, via numeral 617, the consideration of a collection of droplets in one embodiment is performed according to an equation/algorithm. The comparative measure can be expressed as a score that can be calculated for each possible alternative geometric stride in order to select a particular stride or offset. For example, another possible algorithmic approximation involves an equation with three terms, as follows:

S _i = W _v (S _v,min / S _v ) + W _e (S _e / S _e,max ) + W _d (S _d,min / S _d ),

where the terms based on S _v , _Se and S _d are fractions calculated for the difference in deposited droplet volume, efficiency (maximum number of nozzles used per pass) and change in geometric stride, respectively. In one formula, the term "( S _v,min / S _v )" seeks to minimize the variation in fill volume compared to the per-pass target value in a manner dependent on the total number of droplets.

Numeral 619 in FIG. 6A indicates that in one embodiment, drop combination selection may be performed using matrix mathematics, such as by using a mathematical technique that simultaneously considers all drop volume combinations and uses an eigenvector analysis to select scan paths. .

As represented by numeral 621, an iterative process may be applied to reduce the number of droplet combinations considered. That is, geometric strides can be calculated one at a time, for example, as indicated by the previous description of one possible processing technique. Whenever a particular scan path is planned, the method determines the incremental volume still required in each target zone under consideration, and then proceeds to determine the aggregate volume best suited to produce each target zone within desired tolerances Or scan or geometric offset of filled volumes. This process is then repeated for iterations until all scan paths and nozzle firing patterns have been planned.

Via number 622, hybrid processing can also be used. For example, in one embodiment, a first set of one or more scans or geometric strides may be selected and used, e.g., based on minimizing deviation and maximizing efficiency in terms of droplet volume per nozzle (e.g., the number of scans used per scan). nozzle). Once a certain number of scans have been applied, eg 1, 2, 3 or more, different algorithms may be invoked eg maximizing the nozzle used per scan (eg regardless of deviations in applied droplet volume). Any of the particular equations or techniques discussed above (or other techniques), optionally applying one of the algorithms, may be applied in such a hybrid process, and other variations will no doubt occur to those skilled in the art.

Note that, as previously mentioned, in the exemplary display fabrication process, each target area fill volume may have a deliberate implant (623) to ease planned randomization of the filiform pattern. In one embodiment, a generator function (625) is optionally applied to intentionally vary the target fill volume (or to make the number of drops generated for each target zone combination) in a manner that achieves this planning randomization or other effects. aggregate volume skew). As previously stated, in various embodiments, such variations can also be calculated into the target fill volume and tolerance, i.e. even before analyzing the droplet combination, and for example applying an algorithmic approximation as previously indicated to satisfy each target area filling requirements. As will be discussed below in conjunction with FIG. 8B , it is also possible to consider the randomization as a probability distribution and plan droplet measurements dependent on it (and find the per-nozzle, per-waveform distributed). For example, if the randomization of the planned fill is to vary normally between ±0.2% of the target composite fill, and the specified tolerance is ±0.5% of the target composite fill, then one can plan for each nozzle and Droplet measurements were combined for each nozzle waveform to yield 3σ values for each nozzle/nozzle waveform that were within 0.3% of the target (0.2%+0.3%=0.5%).

FIG. 6B and numeral 631 refer to a more detailed block diagram related to the above-mentioned iterative drop combination selection process. As represented by numerals 633 and 635, first, possible droplet combinations are again suitably identified, stored and retrieved for evaluation by the software. For each possible scan path (or geometry step), via number 637, the method stores a footprint identifying the scan path (639) and applied nozzle, and it subtracts each nozzle shot from each target zone geometry (641 ) to determine the remainder combination (643) for each target zone. These are also stored. Then, via numeral 645, the method evaluates the stored data according to predefined criteria. For example, as indicated by optional (dashed) block 647, a method that seeks to maximize the minimum number of droplet combinations across all relevant target regions may assign an indication that the combination just stored is better than the previously considered alternative. Better or worse scores. If specified criteria ( 645 ) are met, then a particular scan or geometric step may be selected, stored or otherwise marked for use in consideration of another printhead/substrate scan or by using the remainder of the combination, as represented by numerals 649 and 651 . If the criterion is not met (or the consideration is not complete), another stride may be considered and/or the method may adjust consideration of the geometric stride (or previously selected portion) under consideration, via number 653 . Again, many variations are possible.

It was previously noted that the order in which the scans are performed or the droplets are deposited is not important to the final composite value for each target zone. While this is true, to maximize printing speed and throughput, scans are preferably ordered to result in the fastest or most efficient printing possible. Thus, classification and/or ordering of scans or strides can then be performed if not previously calculated into the geometric stride analysis. This processing is represented by Fig. 6C.

In particular, numeral 661 is used to generally designate the method of FIG. 6C. For example, software running on a suitable machine causes the processor to retrieve (663) the selected geometric step, specific set, or other data identifying the selected scan path (and the appropriate nozzle firing pattern, which may be driven by more than one firing waveform In those embodiments for certain nozzles, it may also include data specifying which of a plurality of firing waveforms is to be used for each droplet). These steps or scans are then sorted or ordered in such a way that the incremental step distance is minimized. For example, referring again to the hypothetical example presented earlier, if the chosen strides/sweep paths were {0, +3, -2, +6, and -4}, these might be reordered so that each incremental step Minimize the amplitude and minimize the total (aggregated) distance traversed by the motion system between scans. In the case of e.g. no reordering, the incremental distances between these offsets would be equal to 3, 2, 6 and 4 (so that in this example the aggregated distance traversed would be "15"). If the scans (for example, scans "a", "b", "c", "d", and "e") are reordered in the manner described (for example, by "a", "c", "b", "e" and "d" order), then the incremental distances would be +1, +2, 0, and +4 (so that the aggregated distance traversed would be "7"). Here, as indicated by numeral 667, the method may distribute motion to the printhead motion system and/or the substrate motion system, and reverse the order of nozzle firing (e.g., if alternate round-trip scan path directions are used, via FIG. 3B's numbers 339 and 340). As previously described and represented by optional processing block 669, in some embodiments, planning and/or optimization may be performed on a subset of the target region, and the solution then applied in a spatially iterative manner over a large base.

This repetition is represented in part by Figure 6D. As implied by Figure 6D, it should be assumed for this description that it is desired to fabricate an array of flat panel devices. The common base is indicated by numeral 681, and a set of dashed boxes, such as box 683, represent the geometry for each tablet device. Fiducials 685 having a two-dimensional nature are formed on the substrate and used for positioning and alignment for various fabrication processes. After these processes are finally completed, each panel 683 is separated from the common base using cutting or similar process. Where the array of panels represents each OLED display, the common substrate 681 will typically be glass, with the substrate deposited on top of the glass, followed by one or more sealing layers; each panel is then inverted so that the glass substrate forms the back of the display. Glowing surface. For some applications, other substrate materials may be used, such as transparent or opaque flexible materials. As noted, many other types of devices can be fabricated from the techniques described. Solutions can be computed for a specific subset 687 of slabs 683 . This solution is then repeated for other similarly sized subsets 689 of panels 683, and then the entire set of solutions may be repeated for each panel to be formed from a given substrate.

Recalling the various techniques and considerations introduced above, a manufacturing process can be performed to mass produce products quickly and at low cost per unit. Applied to display device manufacturing (for example, flat panel displays), these techniques enable fast per-panel print processing, producing multiple panels from a common substrate. By providing fast repeatable printing techniques (for example, using common inks and printheads between panels), it is believed that printing can be substantially improved, for example, reducing the printing time per layer to what would be required without the above techniques A fraction of the time, all while ensuring each target zone fill volume is within specification. Returning again to the example of a large HD television display, it is believed possible in one hundred eighty seconds or less, or even ninety seconds or less, for large substrates (e.g., producing an 8.5 substrate, which is about 220cm x 250cm) Accurately and reliably printing each color part layer represents a significant process improvement. Improving the efficiency and quality of printing paves the way for a dramatic reduction in the cost of producing large HD television displays and thus the cost of low-end consumer devices. As previously stated, while display manufacturing (and OLED manufacturing in particular) is one application of the techniques presented in this paper, these techniques can be applied to a variety of processes, computers, printers, software, manufacturing equipment, and end devices, and do not Limited to display panels.

One benefit of the ability to deposit precise target region volumes (eg, well volumes) within tolerances is the ability to implant intentional variations within tolerances as described. These techniques facilitate significant quality improvements in displays because they provide the ability to hide pixelation artifacts of the display, making such "linework" imperceptible to the human eye. Figure 7 provides a block diagram 701 associated with one method for injecting this change. As with the various methods and block diagrams discussed above, block diagram 701 and related methods may optionally be implemented as software, on a stand-alone medium or as part of a larger machine.

As represented by numeral 703, changes may be made according to certain criteria. For example, it is generally understood that the sensitivity of the human eye to contrast changes is related to brightness, intended viewing distance, display resolution, color, and other factors. As part of the specified criteria, a measure is used to ensure that given the typical human eye sensitivity to spatial variations in contrast between colors between different brightness levels, such variations will be detected in a manner that is invisible to the human eye. Smoothing, such as changing in a manner that does not contribute to a human-observable pattern (a) in any one or more directions or (b) between color components given expected viewing conditions. This can optionally be achieved using a planning randomization function, as mentioned previously. Where a minimum criterion is specified, the target fill volume for each color component and each pixel, as represented by numeral 705 , can be intentionally varied in a manner suitable to hide any visible artifacts from the human eye. Note that the right side of Figure 7 represents various processing options, eg the variation can be independent across color components (707), based on an algorithm applying a test for a perceivable pattern to ensure that the fill variation did not cause a perceivable pattern. As described with numeral 707, for any given color component (e.g., any given ink), the variation can also be made independent (709) in each of a plurality of spatial dimensions (e.g., x and y dimensions). ). Again, in one embodiment, not only is the variation smoothed for each dimension/color component so that it is not perceptible, but any pattern of difference between each of these dimensions is suppressed so that it is not visible. Via number 711, one or more generator functions may be applied to ensure that these criteria are met, for example by assigning a small target fill variation to the fill of each target zone prior to droplet volume analysis, optionally using any desired criteria. As represented by numeral 713, in one embodiment, this variation can optionally be made random.

Via number 715, the selected variation criteria are thus facilitated to weight the selection of a particular combination of droplets for each target zone. As noted, this can be performed via a target fill change or at a selected time of droplet (eg, scan path, nozzle waveform combination, or both). There are other methods for imparting this variation as well. For example, in one contemplated embodiment, via numeral 717, the scan path is varied in a non-linear fashion, effectively varying the droplet volume across the direction of the average scan path. Via number 719, it is also possible to vary the nozzle firing pattern, for example by adjusting the firing pulse rise time, fall time, voltage, pulse width or using multiple signal levels per pulse (or other forms of pulse shaping techniques) to provide tiny droplets Volume changes; in one embodiment, these changes can be pre-calculated, and in a different embodiment, only waveform changes that produce very small volume changes are used, with other measures taken to ensure aggregate fill remains within specified tolerances. In one embodiment, for each target zone, a number of droplet combinations that fall within a specified tolerance range are calculated, and for each target zone, a change (e.g., randomly or based on a mathematical function) The choice of which droplet combination to use, or to vary a particular waveform (i.e., used to produce a droplet of a given volume) for one nozzle contributing to the selected combination, for example, to provide a small change in volume, effectively changing the droplet volume in the target area without changing the planned scan path. Such variations can be effected along the scan path direction over a row of target areas, over a column of target areas, or both.

The use of Figures 8A-8B is used to explain the formula for estimating the drops produced by each nozzle or combination of nozzle waveforms and optionally planning the combination of multiple drops based on the statistical average determined from the measurements. approach to statistical modeling. Note that in the example of FIGS. 8A-8B , a statistical model is constructed for the drop volume that can be expected from a given pair of nozzle drive waveforms; normal) or construct a similar statistical model for some other parameter.

The method depicted in FIG. 8 is generally designated by reference numeral 801 . Per functional block 803, the method in this embodiment begins by establishing specification ranges (eg, maximum and minimum fills for a given target area that will receive ink). In the example presented earlier, this specification range could be expressed as the mean plus or minus a specific value (eg, 50.00pL ± 0.5%), but almost any range or expression of acceptable values could be used. In one contemplated implementation, the specified tolerance on the target is ±0.5%, although other values (such as, but not limited to, 1.0% or 2.0%) may also be used. In keeping with the previous example, for this example it will be assumed that the target is 50.00pL and the tolerance is ±0.5% (so that the acceptable range is 49.75pL-50.25pL), although almost any range or acceptance criterion could be used.

At reference numeral 805, one or more candidate waveforms are selected for each nozzle of a printhead or printhead assembly. In embodiments where only a single drive waveform is used (eg, a square voltage pulse of a fixed voltage), there is no selection that needs to be performed. In embodiments that allow for customized waveform definitions (see, for example, the discussion below in association with FIGS. Several selectable waveforms under the range of values of the multiple acceptable waveforms for each nozzle. At reference numeral 809, this selection (807) may be performed according to a manual design process (ie, through waveforms selected by the designer and pre-programmed into the system), or the selection process may be automated.

With one or more waveforms defined for each nozzle, drop measurements are planned for different drop ejections for a given nozzle waveform pairing. For example, in one embodiment, multiple droplets (eg, "24") may be required per nozzle, for each droplet to provide a basis for estimating the measured statistical distribution. As discussed herein, a droplet measurement device (eg, imaging or non-imaging) may be used for this purpose. The 24 (or another number) of measurements may be scheduled for immediate measurements or for runs in corresponding or multiple measurement cycles or iterations. Furthermore, in one embodiment, a threshold number of measurements may be programmed for initialization, wherein the system then increases the set of measurement data over time to obtain a strong confidence in the statistical distribution of the measurements; in an alternative embodiment, Each measurement may be scheduled for a moving window of time (e.g., a re-measurement may be scheduled "every 3 hours", or measurement data may only be retained for some limited time interval used for analysis); thus, in one embodiment, each Measurements are stored with timestamps to indicate their validity and expiration during estimation. Regardless of the measurements and/or measurement retention criteria used, the number of measurements can be programmed (811) for each nozzle wave pairing for purposes of statistical analysis. Advantageously, the corresponding measurements for droplets originating from each nozzle waveform pairing are grouped into sets and in a manner that facilitates finding a known common distribution using well-understood rules for mathematical processing (including aggregation) Formatted way to plan. For example, the normal distribution, the Student's-T distribution, and the Poisson distribution all have associated parameters that can be combined according to known mathematical treatments to predict the probability of a fill volume that will result from a combination of individual droplets (for corresponding nozzle waveform pairings). Aggregated or synthetic distributions. Measurement planning can thus be performed according to the techniques described herein to derive a droplet data set that allows a statistical combination of drops associated with potentially different nozzle waveform pairs to utilize a very high degree of confidence (e.g., Accurate filling is achieved within specified tolerances, reference numeral 813, typically greater than 99% confidence. Accordingly, in one implementation of the described technique, droplet measurements for each combination of nozzle waveforms are planned to satisfy a set of parameters describing a known type of probability distribution (e.g., in the case of a normal distribution, Number of measurements or members n, statistical mean μ and standard deviation σ), where the measurement data (once obtained) are stored for each possible nozzle and nozzle waveform pairing under consideration. In one embodiment, the planning and measurements may be iterative (i.e. repeated) until some desired criterion is reached (e.g. minimum number (n) of raw measurements, minimum number of measurements satisfying some criterion, minimum statistical extension (e.g. satisfying some criterion or the 3σ value of the desired confidence interval) or other criterion). Whatever planning criteria are applied (e.g. by software), the system comprising the drop measurement device and printhead assembly under consideration is then subjected to application to each nozzle (and each drive waveform for a given nozzle) individually The droplet measurements to find a statistically significant number of droplet measurements ( 815 ). As noted at 817 and 819, optionally performed in situ (e.g., optionally in a printer or OLED device fabrication facility in the presence of a controlled atmosphere) and in a manner sufficient to derive statistical confidence The measurement. The collected data may then be stored as an aggregated probability distribution ( 821 ) and/or optionally in a manner that retains individual measurement data (eg including any timestamps for the per-nozzle measurement windows).

As previously mentioned, in one embodiment, drops from potentially different nozzles and/or nozzle drive waveforms are intelligently combined to obtain accurate fills within a high degree of statistical confidence. This combination (and the associated planning) is achieved by combining the statistical parameters for the corresponding droplets, with a probability distribution of common format constructed for each nozzle, to obtain an exact filling (and a good Probability distributions for understanding). This case is indicated by reference numerals 823, 825 and 827 in FIG. 8A. More specifically, droplet averages are combined in one embodiment (eg, corresponding to an associated normal distribution) to obtain a predicted aggregate fill for the target zone. As an example, if for a given pair of first and second nozzle waveforms, the average drop volume is measured to be 9.98 pL and 10.03 pL, respectively, then the average aggregate fill based on one drop associated with each pair is expected to be 20.01 pL ( In the case involving a normal distribution, μ _c = μ ₁ + μ ₂ ); if in this same hypothetical example the standard deviations are 0.032pL (σ ₁ ) and 0.035pL (σ ₂ ) for the corresponding droplets, then the aggregation The expected standard deviation of will be 0.0474pL (i.e. based on σ ² _c = σ ² ₁ + σ ² ₂ ), and the aggregated 3σ value will be approximately 0.142pL (note that 1σ equals a confidence interval of approximately 68.27%, and 3σ equals Approximate 99.73% confidence interval). Similar techniques can be applied to any common distribution format via the processing of droplet measurements for each nozzle waveform pair as independent random variables. Accordingly, the technique employed herein uses drop measurement techniques to construct a statistical model for each nozzle waveform pairing, planning for each drop combination (in a normally distributed case). Almost any distribution type can be used, provided the type of probability distribution is amenable to aggregation of random variables. As indicated by functional block 827 , given a desired specification range (eg, about 0.5% of the target), the proposed combination is analyzed (eg, by software) to ensure that the desired range is met with a high degree of statistical confidence. For example, in one embodiment, as mentioned, an expected confidence criterion (eg, 3σ representing a 99.73% confidence interval) is tested to ensure that it fits within expected tolerances. As an example, if the desired tolerance is 49.75pL - 50.25pL as per the example presented above, and the possible droplet combinations are represented as an average of 49.89pL with a 3σ value equal to 0.07pL, this would translate to aggregate fill being at a good Between 49.82 pL and 49.96 pL within the desired tolerance range and with 99% confidence that the particular combination would be considered an acceptable combination (per-droplet combination analysis function as described above). Again, any desired statistical criterion or goodness of fit data may be used; in another embodiment, 4σ values (99.993666%) or other values are analyzed against desired tolerance ranges. With the acceptable drop combinations determined for each print well, a specific specific combination of drops for each well (representing simultaneous deposition by multiple nozzles of the printhead assembly) can then be planned (see Fig. 5-FIG. 7), where printing is then performed (829) according to the pre-planned drop combination for each well.

FIG. 8B provides another method 851 for accommodating intentional target zone fill variations according to desired criteria and optionally also for performing a variable number of droplet measurements per nozzle (or per nozzle waveform). More specifically, the methods may again be implemented as instructions stored on a non-transitory machine-readable medium that control at least one processor to perform the set of functions commanded by the instructions. At reference numeral 853, a desired tolerance range is received as a first operand "x"; for example, one can specify that the target area (eg, pixel well) fill should be within a given percentage of the target volume (eg, 50.00 pL ± 0.5%). This tolerance range may be dictated by consumer or industry specifications, as indicated by function 855 . If it is desired to plan for intentional variation of the composite volume (e.g. random variation over a small range to avoid line effects or other noticeable artifacts in the resulting display), then by function 857, this range is received as Second operand "y". Based on these two operands, at block 859, the method calculates the effective allowable maximum variation, standard deviation, or other measure. In one embodiment, y is subtracted from x as depicted in the figure and is equal to the effective allowable fill variation; for example, if the specification calls for fill within ±0.5% as in the example above, and ±0.1% of Injecting intentional random variation into the planned synthetic average for well filling (e.g. 49.95pL-50.05pL), then again using the example of a target of 50.00pL ± 0.5%, the allowed variation (before random variation) can be Restricted to 49.80pL-50.20pL. Note that other techniques are also possible, e.g. instead of simply subtracting these measures, another set of bound criteria may be used, e.g. based on mathematics associated with statistical combinations of standard deviations or variances for independent random variables; depends on implementation For example, many other criteria can be applied. Per block 859, the remaining range (e.g., ±0.4% of target) may then be equal to a desired confidence interval (e.g., a 3σ interval or other statistical measure) and used to assess whether a possible droplet combination is acceptable or per the example given above to be excluded from consideration.

Alternatively, as indicated by function blocks 861 and 863, the remaining ranges and associated confidence intervals may be applied as criteria governing droplet measurements to construct a desired statistical model for each droplet. For example, as represented by block 861, with a defined desired confidence interval (e.g., 3σ <= 0.4% of target), the desired variance or maximum allowable variance can be identified, effectively to produce a statistical model that satisfies the desired statistical criteria Rather, it is calculated in a manner to define the number of baselines n of drop measurements that need to be taken for each combination of nozzle waveforms. For example, the desired effective tolerance range can be used to identify the number of measurements (such as 24, 50, or another number) computed to produce a statistical distribution that will be strict, regardless of whether the filling is intentionally varied, and thus result in a value that can be calculated with A large number of possible droplet combinations for printing planning. This calculation can be applied in a number of ways, such as (a) identifying a threshold number of measurements to be applied to each combination of nozzle waveforms (e.g., 24 droplet measurements for each), or (b) identifying the number of measurements for each A threshold statistical criterion that a combination of nozzle waveforms must satisfy (eg, where a potentially varying number of measurements are performed per nozzle or nozzle waveform, up to a threshold criterion (eg, variance, standard deviation, etc.)). A drop test function is then applied ( 863 ) using the drop measurement device to perform measurements, with various exemplary functions represented by such tests set forth in function block 865 . For example, _ni drops may be measured for each nozzle (or nozzle waveform pair) “i”, as indicated in block 865 . For each measurement, the software controlling the drop measurement device may perform incremental drop volume measurements (867) and store the data in memory (869). Following each measurement (or after a threshold number of measurements), the joint measurements for a given combination of nozzle waveforms may be aggregated to compute (871) statistical parameters for a particular combination of nozzle waveforms (e.g. in the case of a normal distribution type Below, mean and standard deviation μ and σ). These values can then be stored in memory (873). Optionally, per functional block 874, these same or different measurement techniques may be applied to store one or more droplet measurements for velocity v and x- and y-dimensional trajectories (α and β). As reflected by reference numeral 875, a decision criterion may be applied to determine whether sufficient measurements have been taken for a given parameter (eg, volume) for a particular nozzle waveform combination (i), or whether additional measurements are desired. If additional measurements are required, the method loops by flow arrow 877 to generate these additional measurements, ie, so that a statistical model that satisfies the desired robustness criteria can be constructed for a particular combination of nozzle waveforms. If no additional measurements are required, the method may then continue to the next nozzle 879, looping appropriately at flow arrow 881 until all nozzles and/or nozzle waveform combinations have been processed. Note that not all embodiments require this order; for example, loops 877 and 881 are changed in order (e.g., where drop measurements are performed sequentially for each nozzle), where the process repeats until sufficiently robust data has been obtained ; for example, this process provides particular advantages for embodiments where droplet measurements are to be performed incrementally in the same way that stacking is handled for other systems (see eg discussion of FIG. 19 below). At reference numeral 883, once all nozzles or combinations of nozzle waveforms have been sufficiently tested, the method ends, or is temporarily paused if run on an intermittent basis. For the drop testing described, the data obtained, including measured data and/or calculated statistical parameters, is stored in machine readable memory 885 for use in drop combination planning, for example, as discussed above. . The acquired data may alternatively be used in other ways instead of or in addition to intelligent mixing of different droplet volumes. In one embodiment, as mentioned, the stored data may again be represented in the form of individual measured and/or statistical parameters including one or more of drop volume, drop volume, and/or drop trajectory. any desired droplet parameters.

Figures 9A-10C are used to provide simulation data for the techniques discussed here. 9A-9C represent the expected composite fill volume based on five droplets, while FIGS. 10A-10C represent the expected composite fill volume based on ten droplets. For each of these figures, the letter designation "A" (eg, FIGS. 9A and 10A ) indicates the case where a nozzle is used to deposit droplets without consideration regarding volume differences. Conversely, the letter designation "B" (eg, FIGS. 9B and 10B ) indicates that the expected volume difference between pairs of nozzles is "averaged" where random combinations of (5 or 10) droplets are selected. Finally, the letter designation "C" (eg, FIGS. 9C and 10C ) indicates where scanning and nozzle firing depend on each target zone specific aggregated ink volume trying to minimize aggregate fill variation across the target zone. In these various figures, each vertical axis represents the aggregate fill volume in pL and each horizontal axis represents the number of target zones, assuming that the variation for each nozzle will be consistent with that observed in the actual device, Examples are pixel wells or pixel color components. Note that the emphasis on these figures will show the change in the aggregate fill volume, taken around the assumed average random distribution of droplets. For Figures 9A-9C, assume the average volume per nozzle is slightly below 10.00 pL per nozzle, and for Figures 10A-10C, assume the average droplet volume per nozzle is slightly above 10.00 pL per nozzle .

A first graph 901 represented in FIG. 9A shows each well volume variation taking differences in nozzle droplet volumes without attempting to mitigate these differences. Note that these variations can be extreme (eg, 903 per peak), with an aggregate fill volume range of about ±2.61%. As noted, the mean of the five droplets was slightly below 50.00 pL; Figure 9A shows the tolerance ranges for the two sets of samples centered on this mean, including the range representing ±1.00% centered on this value. A first range 905 and a second range 907 representing a range of ±0.50% centered on this value. As seen with many peaks and troughs that exceed the range (eg, peak 903 ), such a printing process results in many wells that will not meet the specification (eg, one or the other of these ranges).

A second graph 911 represented in FIG. 9B shows per-well volume changes using a randomized set of five nozzles per well in an attempt to statistically average the effect of drop volume changes. Note that such techniques do not allow for the precise generation of a specific volume of ink in any particular well, nor do such processes guarantee aggregated volumes within range. For example, while the percentage of fill volume that falls outside specification represents a much better case than that represented in FIG. For example ±1.00% and ±0.50% variations denoted by numerals 905 and 907, respectively. In this case, the min/max error was ±1.01%, reflecting an improvement over the case of random mixing relative to the data presented in Figure 9A.

Figure 9C represents a third case, using a specific combination of drops per nozzle according to the technique described above. In particular, graph 921 shows that the variation is well within the ±1.00% range and fairly close to meeting the ±0.50% range for all indicated target regions; again, these ranges are denoted by numbers 905 and 907, respectively. In this example, five specifically selected drop volumes are used to fill the wells in each scanline, with the printhead/substrate shifted appropriately for each pass or scan. The min/max error is ±0.595%, reflecting a further improvement in the case of this form of "smart blending". Note that this improvement and data observation is consistent for any form of smart drop volume combination to achieve a specific fill or tolerance range, such as in the case of using offsets between nozzle rows (or multiple printheads) or where multiple preselected drive waveforms are used to allow for combinations of specifically selected droplet volumes.

As noted, Figures 10A-10C present similar data, but taking a combination of 10 droplets per well, with an average droplet volume of about 10.30 pL per nozzle. In particular, graph 1001 in FIG. 10A represents the case where no care has been taken to mitigate droplet volume differences, and graph 1011 in FIG. 10B represents the case where droplets are applied randomly in an attempt to statistically "average" the volume difference, And the graph 1021 in FIG. 10C represents the case of the planned mixing of a particular droplet (to achieve the average fill volume of FIGS. 10A/10B , ie about 103.10 pL). The various graphs show tolerance ranges around ±1.00% and ±0.50% variations of this mean value, indicated using range arrows 1005 and 1007, respectively. Each of the graphs further shows respective peaks 1003, 1013 and 1023 represented by changes. Note however that FIG. 10A represents a variation of ±2.27% around the target, FIG. 10B represents a variation of ±0.707% around the target, and FIG. 10C represents a variation of ±0.447% around the target. By averaging over a larger number of droplets, the "random droplets" seen in Figure 10B will achieve a ±1.00% tolerance around the mean rather than a ±0.50% range. Conversely, seeing that the solution described in Figure 10C will satisfy both tolerance ranges, illustrates that variation in droplet combination between wells can be constrained to fall within specification while still allowing for variation in droplet composition between wells.

An alternative embodiment of the technology described in this disclosure is as follows. For printing processes that use nozzles with a standard deviation of drop volume of x% to deposit aggregated fill volumes with a maximum variation of ±y%, there are conventionally few means of ensuring that the aggregated fill volume will vary by ±y%. This presents potential problems. The droplet aggregation technique (such as represented by the data visible in FIGS. 9B and 10B ) statistically reduces the standard deviation of aggregated volumes across the target region to x%/(n) ^1/2 , where n is the The average number of droplets required to achieve the desired fill volume. However, even with this statistical approach, especially if y and n are small, there is no mechanism for reliably ensuring that the actual target zone fill volume will actually lie within the maximum error bound of ±y%. The techniques discussed here provide a mechanism for providing this reliability by ensuring a known percentage of the target area, and achieving a resultant fill within ±y%. An alternative embodiment thus provides a method of generating control data or controlling a printer, and related devices, systems, software and improvements, wherein the standard deviation across the volume of the target zone is better than x%/(n) ^1/2 ( For example, substantially better than x%/(n) ^1/2 ). In a particular implementation, this condition is met in case the printhead nozzles are simultaneously used to deposit droplets in respective rows (eg respective pixel wells) of the target area with each scan.

Using a basic set of techniques for combining droplets such that the sum of their volumes is specifically chosen to meet the specific goals thus described, this paper will now turn to a more detailed discussion of specific devices and applications that can benefit from these principles. This discussion is intended to be non-limiting, ie to describe a small number of specifically contemplated implementations for implementing the methods presented above.

As seen in FIG. 11 , multi-chamber fabrication apparatus 1101 includes a number of general modules or subsystems, including transfer module 1103 , printing module 1105 , and processing module 1107 . Each module maintains a controlled environment such that printing, for example, can be performed by the printing module 1105 in a first controlled atmosphere, and other processing, such as, for example, inorganic sealing layer deposition or curing processes (e.g., Another deposition process such as for printed materials). Apparatus 1101 uses one or more mechanical handlers to move substrates between modules without exposing the substrates to an uncontrolled atmosphere. Within any given module, other substrate handling systems and/or specific equipment and control systems appropriate to the process to be performed for that module may be used.

Various embodiments of the transfer module 1103 may include an input load lock 1109 (i.e., a chamber that provides a buffer between different environments while maintaining a controlled atmosphere), a transfer chamber 1111 (also having a carrier for transferring substrates) ) and the atmosphere buffer chamber 1113. Within the printing module 1105, other substrate handling mechanisms such as floating tables may be used for stable support of the substrate during the printing process. Additionally, an xyz motion system such as a split axis or gantry motion system may be used for precise positioning of at least one printhead relative to the substrate as well as providing a y-axis transport system for transport of the substrate through the printing module 1105 . It is also possible to use multiple inks for printing within the printing chamber, for example using individual printhead assemblies, so that for example two different types of deposition processes can be performed within the printing module in a controlled atmosphere. The printing module 1105 may include an air enclosure 1115 that houses the inkjet printing system, with features for introducing an inert atmosphere (e.g., nitrogen, a noble gas, another similar gas, or a combination thereof) and additionally for environmental regulations (e.g., temperature and pressure) , gas composition and particle presence to control the atmosphere of the device.

The processing module 1107 may include, for example, a transfer chamber 1116; this transfer chamber also has a handler for transferring substrates. In addition, the processing module may further include an output load lock 1117 , a nitrogen stack buffer 1119 and a curing chamber 1121 . In some applications, a curing chamber may be used to cure the monomeric film into a homogeneous polymeric film, for example using thermal or UV radiation curing processes.

In one application, the apparatus 1101 is suitable for mass production of large volumes of LCD or OLED displays, for example an array of eight screens at a time on a single large substrate. These screens can be used in televisions and as display screens for other forms of electronic equipment. In a second application, the device can be used in much the same way for the mass production of solar panels.

Applied to the droplet volume combination technique described above, the print module 1105 can be advantageously used in display panel manufacturing to deposit one or more layers such as filter layers, light emitting layers, barrier layers, conductive layers, organic or inorganic layers, sealing layers and other types of materials. For example, the described apparatus 1101 can be loaded with a substrate and controlled to move back and forth between the various chambers to deposit and/or cure or harden one or more printed layers, all without being exposed to an uncontrolled atmosphere. The way interrupted by the middle exposure. Optionally, ink droplet measurement (if used in conjunction with the described system) can be performed as the substrate is moved or processed in any chamber. For example, a first substrate may be loaded via input load lock 1109, and during this process, a printhead assembly within print module 1105 may engage a drop measurement device to perform drop measurement for a subset of print nozzles; In the print nozzle embodiment, the drop measurement can be made periodic and intermittent, so that between each printing cycle, different nozzles representing a circular-progressive subset of all nozzles of the printing assembly are calibrated, measuring Droplets are correlated to derive statistical models for each of droplet volume, angle of ejection (relative to normal), and velocity. A manipulator located in the transfer module 1103 can move the first substrate from the input load lock 1109 to the print module 1105 at which point the drop measurement is disengaged and the printhead assembly is moved into position for active printing. After the printing process is complete, the first substrate may then move to the processing module 1107 for curing. Again, a new cycle of droplet measurement can be performed, and a second substrate can optionally be loaded into the input load lock 1109 (if supported by the system). Many other alternatives and combinations of treatments are possible. By repeatedly depositing subsequent layers (eg, by moving the first substrate back and forth for repeated iterations of printing and curing), each of the controlled volume per target area, polymeric layer properties can be tailored to suit any desired application. In an alternative embodiment, an output load lock 1117 may be used to transfer the first substrate to a second printer (eg for subsequent in-line printing of new layers (eg new layers of OLED material or encapsulation or other layers)). Note again that the techniques described above are not limited to display panel manufacturing processes, and many different types of tools can be used. For example, the configuration of apparatus 1101 may be varied to place individual modules 1103, 1105, and 1107 in different juxtapositions; furthermore, additional modules or fewer modules may be used. As indicated by reference numerals 1121 and 1123, a computing device (such as a processor) running suitable software may be used to control the individual processes and to perform the optional droplet measurements described above in series with other processes, i.e., to enable downtime of the device. Minimize, keep droplet measurements as simultaneously as possible while maintaining a robust statistical model, and stack as many droplet measurements as possible to overlap other system processing.

While Figure 11 provides one example of a set of linked chambers or fabrication components, it is apparent that many other possibilities exist. The drop measurement and deposition techniques described above can be used with the apparatus described in Figure 11, or indeed, to control the manufacturing process performed by any other type of deposition apparatus.

Figure 12 provides a block diagram illustrating various subsystems of one apparatus that may be used to fabricate a fabrication apparatus having one or more layers as specified herein. Coordination for the various subsystems is provided by the processor 1203, acting on instructions provided by software (not shown in Figure 12). During the preparation process, the processor feeds data to the printhead 1205 to cause the printhead to eject various volumes of ink according to nozzle firing instructions. Printhead 1205 typically has a plurality of inkjet nozzles arranged in rows (or arrays of rows) and associated reservoirs that allow ejection of ink in response to activation of piezoelectric or other transducers for each nozzle; such transducers The nozzles are caused to eject a controlled amount of ink in an amount controlled by an electronic nozzle drive waveform signal applied to a corresponding piezoelectric transducer. If there are multiple printheads, there may be a processor for each printhead, or one processor may control the entire printhead assembly. Other transmission mechanisms may also be used. Each printhead applies ink to substrate 1207 at various x-y positions corresponding to grid coordinates within various printing units, as represented by the halftone printed image. Changes in position are accomplished by both the printhead motion system 1209 and the substrate handling system 1211 (eg, causing printing to trace one or more swaths across the substrate). In one embodiment, the printhead motion system 1209 moves the printhead(s) back and forth along the slip ring, while the substrate handling system provides stable substrate support and "y" dimension transport of the substrate to enable any portion of the substrate to "Separate axis" printing; the substrate handling system provides relatively fast y-dimension transport, while the printhead motion system 1209 provides relatively slow x-dimension transport. In another embodiment, the substrate handling system 1211 can provide transport in both x and y dimensions. In another embodiment, the primary transport may be provided entirely by the substrate handling system 1211. Image capture device 1213 may be used to locate any fiducials and aid in alignment and/or error detection.

The apparatus also includes an ink delivery system 1215 and a printhead maintenance system 1217 to aid in printing operations. Printheads may be periodically calibrated or subjected to maintenance treatments; to this end, during the maintenance sequence, printhead maintenance system 1217 is used to perform appropriate priming, ink or gas purges, testing and calibration, and other operations , depending on the specific processing.

As previously introduced, the printing process can be performed in a controlled environment, ie in a manner that presents a reduced risk of contamination that might reduce the effectiveness of the deposited layer. To this end, the apparatus includes a chamber control system 1219 that controls the atmosphere within the chamber, as represented by functional block 1221 . An optional process variation as described may include performing the sparging of the deposition material in the presence of an ambient nitrogen atmosphere.

As previously stated, in embodiments disclosed herein, the individual droplet volumes are combined to achieve a specific fill volume for each target zone selected according to the target fill volume. Specific fill volumes can be planned for each target zone, with fill values varying around target values within acceptable tolerances. For such embodiments, drop volume is specifically measured in a manner that depends on ink, nozzle, drive waveform, and other factors. To this end, reference numeral 1223 denotes an optional drop volume measurement system in which drop volume 1225 is measured for each nozzle and for each drive waveform and then stored in memory 1227 . Such a drop measurement system could be an optical strobe camera or a laser scanning device (or other volumetric measurement tool) incorporated into a commercial printing device as previously described. In one embodiment, the device uses non-imaging techniques (such as image processing software that uses simple optical detectors rather than operating on pixels) to achieve real-time or near-real-time measurements of individual droplet volume, deposition flight angle or trajectory, and droplet velocity. Measured in real time. . This data is provided to processor(s) 1203 during printing or during one-time, intermittent or periodic calibration operations. As indicated by numeral 1229, a prearranged set of firing waveforms may also optionally be associated with each nozzle for later use in generating specific per-target-zone droplet combinations; if such a set Waveforms are used in this embodiment, then drop volume measurements are advantageously calculated during calibration for each waveform using the drop measurement system 1223 for each nozzle. Providing a real-time or near-real-time drop volume measurement system greatly enhances reliability in providing target zone volume fill within desired tolerances, as measurements can be taken and processed (e.g., averaged) as needed to make the statistical volume Measurement errors are minimized.

Numeral 1231 refers to the use of print optimization software running on processor 1203 . More specifically, this software uses this information based on a statistical model of drop volume 1225 (measured in situ or otherwise provided) to plan printing in such a way that the drop volumes are appropriately combined to obtain a specific fill volume for each target zone. In one embodiment, the aggregated volume can be programmed to a resolution of 0.01 pL or better, at a certain within a margin of error; that is, by using the technique used here to construct a statistical model of drop volume per nozzle and per nozzle/waveform combination, statistical accuracy can be derived rather than determined by the droplet measurement system's Accuracy representation. Once printing has been planned, the processor(s) calculates printing parameters such as number and sequence of scans, drop size, relative drop firing times, and similar information, and builds the nozzle firing for each scan of the printed image. In one embodiment, the printed image is a halftone image. In another embodiment, the printhead has multiple nozzles, up to 10,000. As will be described below, each droplet may be described in terms of a time value and a firing value (eg, data describing a firing waveform or data indicating whether a droplet is to be fired "digitally"). In embodiments where the drop volume per well is varied in dependence on the geometric stride and binary nozzle firing decisions, it can be determined by one bit of data, the stride value (or number of scans), and The position value to define each droplet. In implementations where a scan represents continuous motion, a time value may be used as the equivalent of a position value. Whether in time/distance or absolute position, this value describes position relative to a reference (eg, sync mark, position, or pulse) that specifies exactly where and when the nozzle should be fired. In some embodiments, multiple values may be used. For example, in one specifically contemplated embodiment, synchronization pulses are generated for each nozzle in a manner corresponding to each micron of relative printhead/substrate motion during scanning; with respect to each synchronization pulse, each The nozzle is programmed with: (a) an offset value describing the delay of an integer number of clock cycles before the nozzle fires, (b) a 4-bit waveform select signal to describe the fifteen waveform selections programmed into memory dedicated to a particular nozzle driver (i.e., one of sixteen possible values specifying the "off" or non-firing state of the nozzle), and (c) a repeatability value specifying that the nozzle should fire only once, once for each sync pulse Or once for every n sync pulses. In this case, the address and waveform selection for each nozzle is associated by the processor(s) 1203 with the specific drop volume data stored in the memory 1227, the firing representation of the specific waveform from the specific nozzle will use Specific corresponding droplet volumes are used to plan decisions for supplying polymeric ink to specific target areas of the substrate.

Figures 13A-15D will serve to introduce other techniques that can be used to combine different droplet volumes to obtain precise in-tolerance fill volumes for each target zone. In a first technique, rows of nozzles can be selectively offset relative to each other within the printhead assembly during printing (eg, between scans). This technique is described with reference to Figures 13A-13B. In a second technique, the nozzle drive waveform can be used to adjust the piezoelectric transducer firing and thus the properties (including volume) of each ejected droplet. Figures 14A-14B are used to discuss several options. Finally, in one embodiment, a set of multiple alternate drop firing waveforms is precomputed and made available for each print nozzle. This technique and associated circuitry is discussed with reference to Figures 15A-15B.

FIG. 13A provides a layout 1301 of a printhead 1303 across a substrate 1305 in the scan direction indicated by arrow 1307 . Here it is seen that the substrate will consist of a number of pixels 1309, each pixel having wells 1309-R, 1309-G and 1309-B associated with respective color components. Note again that this description is merely an example, that the techniques as used herein can be applied to any layer of the display (e.g., not limited to individual color components and not limited to color-imparting layers); these techniques can also be used to make Display something outside of the device. In this case, the intent is that the printhead deposits one ink at a time, and assuming the ink is color part specific, a separate print process will be performed for each well of the display, one for each of the color parts. Thus, if the first process is being used to deposit ink specific to red light generation, only the first well of each pixel will receive ink in the first print process, such as well 1309-R for pixel 1309 and well 1309-R for pixel 1311. Similar to a well. In the second printing process, only the second well (1309-G) of pixel 1309 and a similar well of pixel 1311 will receive the second ink, and so on. The various wells are thus shown as three different overlapping arrays of target regions (in this case fluidic containers or wells).

Printhead 1303 includes a number of nozzles, such as indicated using numerals 1313 , 1315 , and 1317 . In this case, each number refers to a separate row of nozzles, with each row extending along the column axis 1318 of the substrate. It is seen that nozzles 1313, 1315, and 1317 will form a first column of nozzles relative to substrate 1305, and nozzle 1329 represents a second column of nozzles. As described with Figure 13A, the nozzles are not aligned with the pixels, and as the printhead scans across the substrate, some nozzles will pass over the target area while others will not. Also, in the figure, while print nozzles 1313, 1315, and 1317 will be aligned exactly to the center of a row of pixels starting at pixel 1309, and at the same time print nozzle 1329 will also pass over the row of pixels starting at pixel 1311, the print nozzles The alignment of 1319 is not exactly to the center of pixel 1311 and its associated row. This alignment/misalignment of columns of nozzles with rows of wells is described by lines 1325 and 1327, respectively, representing the centers of the printed wells to receive ink. In many applications, where the precise location of the deposited droplet within the target zone is not critical, and such misalignment is acceptable (for example, it may be desirable to align a certain group of multiple nozzles with each row roughly standard, as discussed in conjunction with Figure 1B and Figure 4D).

FIG. 13B provides a second view 1331 where it is seen that all three rows of nozzles (or individual printheads) have been rotated about thirty degrees relative to axis 1218 . This optional capability was previously referenced by numeral 338 in FIG. 3B. More specifically, as a result of the rotation, the spacing of the nozzles along the column axis 1318 has now changed, with each column of nozzles aligned with well centers 1325 and 1327, or otherwise adjusted to increase the apparent density of nozzles per target print area during scanning. Note, however, that due to such rotational and scanning motion 1307, the nozzles from each column of nozzles will pass through a column of pixels at different relative times (e.g., 1309 and 1311), and thus potentially have different positions to emit data (e.g. , for different timings of firing droplets). Methods for adjusting the firing data for each nozzle are discussed below in conjunction with FIGS. 15A-15B .

As represented in Figure 13C, in one embodiment, a printhead assembly optionally endowed with multiple printheads or rows of nozzles may selectively offset such rows from one another. That is, FIG. 13C provides another plan view in which each of printheads (or nozzle rows) 1319 , 1321 , and 1323 are offset relative to one another, as indicated by offset arrows 1353 and 1355 . These rows represent the use of optional motion mechanisms, one nozzle per row, to allow selective offsetting of the corresponding row relative to the printhead assembly. This provides a different combination of nozzles (and associated specific drop volumes) with each scan and thus for a different specific drop combination (eg, via numeral 1307 ). For example, in such an embodiment, and as depicted with FIG. 13C , such an offset allows both nozzles 1313 and 1357 to be aligned with centerline 1325 and thus their respective drop volumes to be combined in a single pass. . Note that this embodiment is considered a specific example of an embodiment that varies the geometric stride, e.g. even if the geometric stride size between successive scans of the printhead assembly 1303 relative to the substrate 1305 is fixed, a given row of nozzles Each such scan movement is also effectively at a variable offset or stride in the other scans using a motion mechanism relative to the position of a given row. Additionally or alternatively, such offsets may be performed to adjust the effective printing grid to provide varying spacing between deposited droplets. Consistent with the principles presented previously, the use of optional offsets allows individual per-nozzle drop volumes to be aggregated in specific combinations (or sets of drops) for each well, but with a reduced number of scans or passes. For example, with the embodiment depicted in Figure 13C, three droplets can be deposited in each target region (e.g., a well for the red component) with each scan, and furthermore, the offset allows the droplet volume and/or planning changes in space mix.

Figure 13D illustrates a cross-section of the finished display for one well (eg, well 1309-R from Figure 13A) taken in the scan direction. In particular, this view shows the substrate 1352 of a flat panel display, particularly an OLED device. The cross-section depicted shows active region 1353 and conductive terminals 1355 that will receive electrical signals to control the display, including the color of each pixel. The small oval area 1361 where the view is seen is enlarged at the right side of the figure to illustrate the layers in the active area above the substrate 1352 . These layers include, respectively, an anode layer 1369, a hole injection layer ("HIL") 1371, a hole transport layer ("HTL") 1373, an emissive or light emitting layer ("EML") 1375, an electron transport layer ("ETL") 1377 and cathode layer 1378. Additional layers such as polarizers, barrier layers, primers, and other materials may also be included. In some cases, OLED devices may only include a subset of these layers. When the depicted stack is finally manipulated after fabrication, the electrical current causes a recombination of electrons and "holes" in the EML, resulting in the emission of light. Anode layer 1369 may include one or more transparent electrodes common to multiple color components and/or pixels; for example, the anode may be formed from indium tin oxide (ITO). The anode layer 1369 can also be reflective or opaque, and other materials can be used. Cathode layer 1378 typically consists of patterned electrodes to provide selective control of the color components for each pixel. The cathode layer may include a reflective metal layer, such as aluminum. The cathode layer may also comprise an opaque or transparent layer, such as a thin layer of metal combined with a layer of ITO. Together, the cathode and anode serve to supply and collect electrons and holes entering and/or passing through the OLED stack. HIL 1371 is commonly used to transport holes from the anode into the HTL. HTL 1373 is typically used to transport holes from the HIL into the EML, while also blocking the transport of electrons from the EML into the HTL. The ETL 1377 is typically used to transport electrons from the cathode into the EML while also blocking electron transport from the EML into the ETL. These layers are thus used together to supply electrons and holes into the EML 1375 and to confine those electrons and holes in the layer so that they can recombine to produce light. Typically, an EML consists of individually controlled active materials for each of the three primary colors, red, green, and blue, for each pixel of the display, and, as mentioned, in this case with a material that produces red light To represent.

Layers in the active region can be degraded by exposure to oxygen and/or moisture. It is therefore desirable to enhance OLED lifetime by sealing those layers on their faces and sides (1362/1363) and lateral edges opposite the substrate. The purpose of the seal is to provide an oxygen and/or moisture resistant barrier. Such a seal may be formed wholly or partly via the deposition of one or more thin film layers.

The techniques discussed herein can be used to deposit any of these layers and combinations of such layers. Thus, in one contemplated application, the techniques discussed herein provide ink volumes for the EML layer for each of the three primary colors. In another application, the techniques discussed herein are used to provide ink volumes for HIL layers, among other things. In another application, the techniques discussed herein are used to provide an ink volume for one or more OLED encapsulation layers. The printing techniques discussed here can be used to deposit organic or inorganic layers (depending on the process technology) as well as layers for other types of display and non-display devices.

Figure 13A is used to illustrate nozzle drive waveform adjustments and the use of alternate nozzle drive waveforms that will provide different ejected drop volumes from each nozzle of the printhead. The first waveform 1403 is viewed as a single pulse consisting of a rest interval 1405 (0 volts), a rising slope 1413 associated with the determination that the nozzle will be fired at time t2, a voltage pulse or signal level 1407, and a falling slope at time t3 1411 composed. The effective pulse width, represented by numeral 1409, has a duration approximately equal to t3 - t2, depending on the difference between the rising slope and falling slope of the pulse. In one embodiment, any of these parameters (eg, ramp up slope, voltage, down ramp, pulse duration) can be varied to potentially change the drop volume ejection characteristics for a given nozzle. The second waveform 1423 is similar to the first waveform 1403 except that it represents a larger drive voltage 1425 relative to the signal level 1407 of the first waveform 1403 . It will take longer to reach this higher voltage due to the larger pulse voltage and limited rising slope 1427, and as such, the falling slope 1429 typically lags relative to the similar slope 1411 from the first waveform. Third waveform 1433 is also similar to first waveform 1403, except that in this case a different rising slope 1435 and or a different falling slope 1437 may be used instead of slopes 1413 and 1411 (eg, by adjustment of nozzle firing path impedance). The different slopes can be made steeper or shallower (in the depicted case, steeper). Conversely, in the case of the fourth waveform 1443, the pulse is made longer, such as using a delay circuit (eg, a voltage controlled delay line) to increase the time of the pulse at a given signal level (as represented by numeral 1445) and the falling edge of the delayed pulse (as represented by numeral 1447). Finally, fifth waveform 1453 represents the use of multiple discrete signal levels which also provides a means of pulse shaping. For example, seeing that this waveform would include time at the first described signal level 1407, but then apply a ramp up to the second signal level 1455 halfway between times t3 and t2. The trailing edge of this waveform 1457 is seen to lag behind the falling edge 1411 due to the larger voltage.

Any of these techniques may be used in combination with any of the embodiments discussed herein. For example, drive waveform adjustment techniques may optionally be used to vary droplet volume over a small range to alleviate line patterning after the scanning motion and nozzle firing have been planned. Designing the waveform variation in such a way that the second tolerance is within specification facilitates deposition of high quality layers with programmed non-random or programmed random variation. For example, returning to the previously introduced assumptions where the TV manufacturer specifies a fill volume of 50.00pL ± 0.50%, it is possible to have 50.125pL), applying non-stochastic or stochastic techniques to waveform changes where the change statistically contributes no more than ±0.025pL volume change per droplet (given that the aggregation achieved 5 droplets required to fill the volume). Alternatively or additionally, drive waveform variations may be used to affect the velocity or trajectory (angle of flight) of the ejected droplets. For example, in one process, droplets are required to meet a predetermined set of criteria regarding volume and/or velocity and/or trajectory; if the droplet falls outside the accepted criteria, the nozzle drive waveform may be adjusted until compliance is achieved . Alternatively, a set of predetermined waveforms may be measured, wherein a subset of these waveforms is selected based on compliance with a desired standard. Obviously, there are many variations.

As noted above, in one embodiment represented by the fifth waveform 1453 from Figure 14A, multiple signal levels may be used to shape the pulse. This technique is discussed further with reference to Figure 14B.

That is, in one embodiment, the waveform may be predefined as, for example, a sequence of discrete signal levels defined by digital data, the driving waveform being generated by a digital-to-analog converter (DAC). Numeral 1451 in FIG. 14B refers to waveform 1453 having discrete signal levels 1455 , 1457 , 1459 , 1461 , 1463 , 1465 , and 1467 . In this embodiment, each nozzle driver includes circuitry to receive and store up to sixteen different signal waveforms, each waveform being defined by a series of up to sixteen signal levels, each represented as a multi-bit voltage and duration. That is, in such embodiments, the pulse width can be effectively varied by defining different durations for one or more signal levels, and the drive voltage can be varied in a manner selected to provide microdroplet size variation. Waveforming is performed, eg, drop volume is measured to provide specific volume-level increments, such as in units of 0.10 pL. Thus, with such embodiments, waveform shaping provides the ability to shape droplet volumes close to target droplet volume values; when combined with other specific droplet volumes, such as using the techniques exemplified above, these techniques facilitate Exact fill volume for each target zone. In addition, however, these wave-shaping techniques also facilitate strategies for reducing or eliminating stringing; for example, in an alternative embodiment, specific volumes of droplets are combined, as discussed above, but in an order relative to The bounds of the desired tolerance range provide varying ways to select the last droplet (or drops). In another embodiment, a predetermined waveform may be applied with optional further waveform shaping or timing applied as appropriate to adjust droplet volume, velocity and/or trajectory. In another example, the use of jet group drive waveform alternatives provides a mechanism to plan volumes such that no further waveform shaping is required.

Typically, the effect of different drive waveforms and the resulting droplet volume is measured in advance. For each nozzle, up to sixteen different drive waveforms are then stored in each nozzle's 1k synchronous random access memory (SRAM) for later selective use when providing software-selected discrete volume changes. With different drive waveforms at hand, each nozzle is then commanded drop by drop as to which waveform to apply via data programming implementing a particular drive waveform.

Such an embodiment, generally indicated by numeral 1501, is illustrated in FIG. 15A. In particular, processor 1503 is used to receive data defining predetermined fill volumes for each target zone for the particular layer of material to be printed. As represented by numeral 1505, this data may be a layout file or a bitmap file that defines the droplet volume for each grid point or location address. A series of piezoelectric transducers 1507, 1508, and 1509 produce associated ejected drop volumes 1511, 1512, and 1513, respectively, that depend on a number of factors, including nozzle drive waveforms and printhead-to-print manufacturing variations. During a calibration operation, each of a set of variables is tested for their effect on drop volume, including nozzle-to-nozzle variation and the use of different drive waveforms, assuming a particular ink will be used; this calibration operation can be made if desired Is dynamic, for example in response to temperature changes, nozzle clogging, or other parameters. This calibration is represented by a drop measurement device 1515, which provides measurement data to the processor 1503 for use in managing print planning and subsequent printing. In one embodiment, after taking as much as several minutes (e.g., thirty minutes for a few thousand nozzles and preferably much less (e.g., for a few thousand printhead nozzles and potentially dozens of possible nozzle firing waveforms)) Measured data are calculated during operation. In another embodiment, as described, the measurement may be performed iteratively, that is, different subsets of nozzles are updated at different points in time. Non-imaging (eg interferometer) techniques can optionally be used as described above, potentially resulting in dozens of droplet measurements per nozzle, covering tens to hundreds of nozzles per second. This data and any associated statistical models (and averages) may be stored in memory 1517 for use in processing layout or bitmap data 1505 as it is received. In one embodiment, the processor 1503 is part of a computer remote from the actual printer, while in a second embodiment, the processor 1503 is integrated with the manufacturing facility for the product (e.g., a system for manufacturing a display) or with the printer .

To perform droplet firing, a set of one or more timing or synchronization signals 1519 is received for use as a reference, and these are passed through a clock tree 1521 for distribution to each nozzle driver 1523, 1524, and 1525 to generate (1527, 1528 and 1529, respectively) driving waveforms. Each nozzle driver has one or more registers 1531 , 1532 and 1533 respectively, which receive multi-bit programming data and timing information from processor 1503 . Each nozzle driver and its associated registers receive one or more dedicated write enable signals (we _n ) for the purpose of programming registers 1531 , 1532 and 1533 respectively. In one embodiment, each of the registers includes a large amount of memory including Ik SRAM to store a number of predetermined waveforms and programmable registers to select between those waveforms and additionally control waveform generation. The data and timing information from the processor is described as multi-bit information, and this information can however be provided to each nozzle via serial or parallel bit connections (as will be seen in Figure 15B, discussed below, in a In an embodiment, this connection is serial, as opposed to the parallel signal representation seen in Figure 15A).

For a given deposit, printhead, or ink, the processor selects, per nozzle, a set of sixteen drive waveforms that can be selectively applied to droplet generation; note that this number is arbitrary, e.g. Four waveforms are used, and four thousand can be used in another. These waveforms are advantageously selected to provide a desired variation in output drop volume for each nozzle, for example to cause each nozzle to have at least one waveform selection that produces a near-ideal drop volume (e.g., an average drop volume of 10.00 pL) And provide a range of intentional volume changes for each nozzle. In various embodiments, the same set of sixteen drive waveforms is used for all nozzles, but in the depicted embodiment, each of the sixteen potentially unique waveforms is pre-defined individually for each nozzle, Each waveform yields individual droplet volume characteristics.

During printing, data to select one of the predefined waveforms is then programmed into each nozzle's respective register 1531, 1532 or 1533 on a nozzle-by-nozzle basis in order to control the deposition of each droplet. For example, given a target volume of 10.00 pL, nozzle driver 1423 may be configured by writing data into register 1431 to set one of sixteen waveforms corresponding to one of sixteen different drop volumes. The volume produced by each nozzle will have been measured with the drop measurement device 1515, wherein the nozzle-by-nozzle (and waveform-by-waveform) droplet volumes and associated distributions are registered by the processor 1503 and stored in memory to assist in generating the desired Target fill. The processor can define by programming register 1531 whether it wants a particular nozzle driver 1523 to output a processor-selected one of sixteen waveforms. Additionally, the processor can program the registers to have a per-nozzle delay or offset for nozzle firing for a given scanline (e.g., to align each nozzle with the grid traversed by the printhead, corrections include velocity or trajectory error, and for other purposes); this offset is implemented by a counter that deviates a specific nozzle (or firing waveform) by a programmable number of timing pulses per scan. To provide an example, if the results of the droplet measurements indicate that one particular droplet tends to have a lower than expected velocity, then it may be possible earlier (e.g. by reducing the dead time before the effective signal level used for piezoelectric excitation) earlier in time) trigger the corresponding nozzle waveform; conversely, if the results of the droplet measurement indicate that a particular droplet has a relatively high velocity, the waveform can be triggered later, and so on. Other examples are obviously possible—for example, in some embodiments, slow droplet velocities can be combated by increasing the drive strength (ie, the signal level and associated voltage used to drive the piezo actuator for a given nozzle). In one embodiment, synchronization signals distributed to all nozzles occur at defined time intervals (e.g., one microsecond) for synchronization purposes, and in another embodiment, this is adjusted relative to printer motion and substrate layout. Synchronization signals, eg, are emitted for every micron of incremental relative motion between the printhead and substrate. The high-speed clock ( φ _hs ) runs thousands of times faster than the sync signal, e.g. at 100 MHz, 33 MHz, etc.; in one embodiment, multiple different clocks or other timing signals (e.g., strobe signals ). The processor also programs values defining the grid spacing; in one embodiment, the grid spacing is common to the entire pool of available nozzles, although this need not be the case for every implementation. For example, in some cases it is possible to define a regular grid where each nozzle will fire "every five microns". The grid can be unique to the printing system, the substrate, or both. Thus, in an alternative embodiment, the grid can be defined for a particular printer with a synchronous frequency or nozzle firing pattern to efficiently transform the grid to match the a priori unknown substrate geography. In another contemplated embodiment, the memory is shared across all nozzles, which allows the processor to pre-store a number of different grid pitches (eg, 16) shared across all nozzles, so that the processor can (on demand) select a new grid spacing, which is then read out to all nozzles (eg to define an irregular grid). For example, in an embodiment where the nozzle will fire for each color component well of the OLED (e.g. to deposit a non-color specific layer), three or more different grids may be applied consecutively in a cyclic fashion by the processor spacing. Clearly, many design alternatives are possible. Note that the processor 1403 can also dynamically reprogram each nozzle's registers during operation, i.e. apply the sync pulse as a trigger to start any programmed waveform pulses set in its registers, and if at the next sync If new data is received asynchronously prior to a sync pulse, the new data will be applied with the next sync pulse. In addition to setting parameters for sync pulse generation (1536), processor 1503 also controls the initiation and speed of scanning (1535). In addition, the processor controls the rotation of the printhead (1537) for various purposes described above. This way, each nozzle can fire concurrently (or simultaneously) with any of sixteen different waveforms for each nozzle at any time (i.e., with any "next" sync pulse), and can use sixteen any other of the two different waveforms dynamically, between shots, during a single sweep to switch the selected shot waveform.

Figure 15B shows additional details of the circuitry (1541) used in such an embodiment to generate output nozzle drive waveforms for each nozzle; the output waveforms are denoted " nzzl-drv.wvfm " in Figure 15B. More specifically, circuit 1541 receives inputs of synchronization signals, unit lines carrying serial data ("data"), a dedicated write enable signal (we), and a high speed clock ( φ _hs ). Register file 1543 provides data for at least three registers, which convey initial offsets, mesh definition values, and drive waveform IDs, respectively. This initial offset is a programmable value that adjusts each nozzle to align with the starting point of the grid, as described. For example, given implementation variables such as multiple printheads, multiple rows of nozzles, different printhead rotations, nozzle firing speeds and patterns, and other factors, an initial offset can be used to align each nozzle's drop pattern with the web The starting point of the grid is aligned to account for delays and other factors. Offsets can be applied differently across multiple nozzles, for example to rotate a grid or anilox pattern relative to substrate geography or to correct for substrate misalignment. Similarly, as mentioned, offsets may also be used to correct for abnormal speeds or other effects. This grid definition value is a number that represents the number of sync pulses that "count" before the programmed waveform is triggered; in the case of an implementation that prints a flat panel display (e.g., an OLED panel), presumably the target in which to print The zones have one or more regular pitches with respect to the different printhead nozzles, corresponding to a regular (constant pitch) or irregular (multiple pitch) grid. As previously stated, in one embodiment, the processor maintains its own sixteen-entry SRAM to define up to sixteen different grid pitches that can be read out to the register circuits for all nozzles as needed. So, if the Grid Spacing value is set to two (for example, two per micron), each nozzle will fire at this interval. The drive waveform ID represents a selection of one of the pre-stored drive waveforms for each nozzle, and can be programmed and stored in a number of ways depending on the embodiment. In one embodiment, the drive waveform ID is a four-bit select value, and each nozzle has its own dedicated 1 kbyte SRAM to store up to sixteen predetermined nozzle drive waveforms, stored as 16x16x4B entries. Briefly, each of the sixteen entries for each waveform contains four bytes representing the programmable signal level, the four bytes representing the two-byte resolution voltage level and the two-byte programmable duration Time, used to count the number of pulses of the high-speed clock. Each programmable waveform can thus consist of (zero to one) discrete pulses up to sixteen discrete pulses, each with programmable voltage and duration (e.g., with a duration equal to 1-255 pulses of a 33 MHz clock ).

Numerals 1545, 1546 and 1547 designate one embodiment of a circuit showing how a given waveform may be generated for a given nozzle. The first counter 1545 receives a sync pulse to initiate a countdown of the initial offset triggered by the start of a new scan line; the first counter 1545 counts down in micron increments and when zero is reached, the The second counter 1546 outputs a trigger signal; this trigger signal essentially starts the firing process for each nozzle for each scan line. The second counter 1546 then implements a programmable grid pitch in micron increments. The first counter 1545 is reset in conjunction with a new scan line, while the second counter 1546 is reset with the next edge of the high-speed clock following its output flip-flop. The second counter 1546, when triggered, activates the waveform circuit generator 1547, which generates the selected drive waveform shape for the particular nozzle. This latter circuit is based on a _high speed digital to analog converter 1548, counter 1549 and high voltage amplifier 1550, as represented by dashed boxes 1548-1550 seen below the generator circuit. Upon receipt of a trigger from the second counter 1546, the waveform generator circuit retrieves the digital pair (signal level and duration) represented by the drive waveform ID pair and generates a given output analog voltage according to the signal level value, The counter 1549 effectively holds the DAC output for a certain duration according to the counter. The relevant output voltage level is then applied to the high voltage amplifier 1550 and output as a nozzle drive waveform. The next digital pair is then latched out from register 1543 to define the next signal level value/duration etc.

The depicted circuitry provides an efficient means of defining any desired waveform from data provided by processor 1503 . The duration and / or voltage level. As mentioned, in one embodiment, the processor predetermines a set of waveforms (e.g., 16 possible waveforms per nozzle), and then it writes the definitions for each of these selected waveforms into the In the SRAM of the driver circuit of each nozzle, the "firing time" judgment of the programmable waveform is realized by writing the four-bit driving waveform ID into each nozzle register.

Figure 15C provides a flowchart 1551 discussing a method of using different waveforms and different configuration options for each nozzle. As indicated at 1553, a system (eg, one or more processors acting upon instructions from appropriate software) selects a set of predetermined nozzle drive waveforms. For each waveform and for each nozzle ( 1555 ), the droplet volume is measured and a statistical model is built, in particular eg using eg a laser measuring device or a CCD camera. These volumes are stored in processor-accessible memory, such as memory 1557 . Again, measurement parameters may vary depending on the choice of ink and many other factors; therefore, calibration is performed based on those factors and planning deposition activities. For example, in one embodiment 1561, calibration may be performed at the factory where the printhead or printer is manufactured, and this data may be programmed into the vending device (eg, printer) or made available for download. Alternatively, for printers having an optional droplet measurement device or system, these volume measurements (1562) may be performed on first use, such as during initial device configuration. In another embodiment, the measurement (1563) is performed with every power cycle, eg, whenever the printer is turned on or wakes from a low power state or otherwise enters a state where it is ready to print. As previously mentioned, for embodiments where ejected droplet volume is affected by temperature or other dynamic factors, calibration ( 1564 ) may be performed intermittently or periodically, such as after expiration of a defined time interval, when detected On error, at the state of each new substrate operation (eg, during substrate loading and/or loading), daily, or in some other way. Other calibration techniques and schedules (1565) may also be used.

Calibration techniques may optionally be performed in offline processing or during a calibration mode, as represented by processing separation line 1556 . As noted, in one embodiment, such processing is accomplished in less than thirty minutes for potentially thousands of print nozzles and one or more associated nozzle firing waveforms. During online operation (or during print mode) represented below this process separation line 1556, the measured drop volumes are used in selecting groups of drops for each target zone based on specific measured drop volumes such that for each group The droplet volumes total up to the specified aggregate volume within defined tolerances, via 1567. The volume of each region, as represented by numeral 1568, may be selected based on a layout file, bitmap data, or some other representation. Based on these drop volumes and the allowable combinations of drop volumes for each target zone, a shot pattern and/or scan path is selected that effectively represents the specific pattern of droplets for each target zone that will be used in the deposition process. combination (i.e., one of an acceptable set of combinations), as indicated by the number 1569. As part of this selection or planning process 1569, an optimization function 1570 may optionally be employed, e.g., to reduce the number of scans or passes to less than the average number of droplets per target zone multiplied by the number of rows (or columns) of target zones. The product of the number (e.g., less than a row of nozzles turned 90 degrees would be required so that all nozzles in the row can be used in each scan for each affected target zone, and multiple times for each row of target zones depositing droplets in the pass, advancing one row at a time). For each scan, the printhead can be moved and each nozzle waveform data can be programmed into the nozzles to implement drop deposition instructions from a bitmap or layout file; variously represented by numerals 1571, 1573 and 1575 in FIG. 15C these functions. After each scan, the process is repeated for subsequent scans, via number 1577 . Optionally, these techniques and their implementations may be implemented in a printer control file 1579 that is later derived or reused in controlling the ejection of ink at a specific time.

Note again that a number of different embodiments have been described above, which are optional with respect to each other. First, in one embodiment, the drive waveform is not changed, but kept constant for each nozzle. Combinations of drop volumes are created by covering different nozzles with different rows of target areas, as desired, using variable geometric steps representing printhead/substrate offsets. Using the measured drop volumes for each nozzle with high confidence that any drop volume variation can be accommodated within the desired tolerance, this process allows the combination of specific drop volume averages to achieve very specific values for each target zone Fill volumes (e.g., to 0.01pL resolution). The process can be planned so that with each pass multiple nozzles are used to deposit ink in different rows of target areas. In one embodiment, the printing solution is optimized to produce the fewest scans possible and the fastest possible print time. Second, in another embodiment, again using specific measured droplet volumes, different drive waveforms may be used for each nozzle. The printing process controls these waveforms so that specific drop volumes are polymerized in specific combinations. Again, using the measured per-nozzle drop volumes, this process allows the combination of specific drop volume averages to achieve very specific fill volumes for each target zone (eg, to 0.01 pL resolution). The process can be planned so that with each pass multiple nozzles are used to deposit ink in different rows of target areas. In both embodiments, a single row of nozzles may be used or multiple rows of nozzles may be used, arranged as one or more printheads of a printhead assembly; for example, in one contemplated embodiment, thirty printheads may be used , each printhead has a single row of nozzles, each row has 256 nozzles. The printheads can also be organized into various groupings; for example, the printheads can be organized into printhead assemblies each having five printheads mechanically mounted together, and the resulting six The components are separately installed into the printing system. In another embodiment, a converging printhead assembly is used having multiple rows of nozzles that may be further offset in position from one another. This embodiment is similar to the first embodiment described above in that different droplet volumes can be combined using variable effective positional offsets or geometric strides. Again, using the measured per-nozzle drop volumes, this process allows the combination of specific drop volume averages to achieve very specific fill volumes per target zone (eg, to 0.05pL, or even 0.01pL resolution) . This does not necessarily mean that the measurement results are free of statistical uncertainties, such as measurement errors; in one embodiment, such errors are small and accounted for in the target zone fill planning. For example, if the droplet volume measurement error is ± a%, then the fill volume variation across the target zone can be programmed to be within ± (b-an ^-1/2 )% of the target fill tolerance, where ± (b ) % represents the specification tolerance range, and n ^1/2 represents the square root of the mean number of droplets per target zone or well. Unless otherwise stated, ranges smaller than the specification tolerances can be planned such that the resulting aggregated fill volume for the target zone can be expected to fall within the specification tolerances when accounting for expected measurement errors, e.g., as above As described in conjunction with FIG. 8A-FIG. 8B. Naturally, the techniques described herein can optionally be combined with other statistical treatments.

Droplet deposition can optionally be planned so that with each pass multiple nozzles are used to deposit ink in different rows of target areas, optionally optimizing the print solution to produce the fewest scans possible and the fastest print possible time. As previously stated, any combination of these techniques with each other and/or with other techniques may also be employed. For example, in one specifically envisioned situation, variable geometry steps are used with per-nozzle drive waveform changes and per-nozzle, per-drive waveform volume measurements to achieve very specific volume combinations per target zone plan. For example, in one specifically envisioned situation, fixed geometry steps are used with per nozzle drive waveform variation and per nozzle, per drive waveform volumetric measurements to achieve a very specific combination of volumes per target zone plan.

These embodiments ensure a high-quality display by maximizing the number of nozzles that can be used simultaneously during each scan and by planning drop volume combinations such that they must meet specifications; by also reducing print time, these embodiments help facilitate Ultra-low printing cost per unit, and thus a lower price point for the end consumer.

Figure 15D provides a flow chart related to nozzle qualification. In one embodiment, drop measurements are performed to generate statistical models (e.g., distributions and averages) for each nozzle and for each waveform applied to any given nozzle for drop volume, velocity, and Any and/or each of the trajectories. Thus, for example, if there are two options for waveforms for each of twelve nozzles, there are up to 24 combinations or pairs of waveform nozzles; Measurements for each parameter (eg volume) are taken in pairs of nozzles or wave nozzles. Note that, for deposition planning, it is conceptually possible that a given nozzle or pairing of nozzle waveforms may produce exceptionally wide distributions or sufficiently unusual averages that they should be specifically addressed. Figure 15D conceptually represents this special processing applied in one embodiment.

More specifically, reference numeral 1581 is used to denote the overall method. Data generated by the droplet measurement device is stored in memory 1585 for later use. During the apply method 1581, the data is recalled from memory, and the data for each nozzle or pair of nozzle waveforms is extracted and processed individually (1583). In one embodiment, as mentioned, for each variable to be qualified, construct the Normal random distribution. Note again that other distribution formats (eg, Student's-T, Poisson, etc.) can be used. The measured parameters are compared ( 1587 ) to one or more ranges to determine whether the appropriate droplet can be used in practice. In one embodiment, at least one range is applied to disqualify the droplet from use (e.g., if the droplet has a sufficiently large or small volume relative to the desired target, the nozzle or nozzle waveform pairing may be excluded from short-term use ). To provide an example, if 10.00 pL droplets are desired, nozzles or nozzle waveforms linked to a droplet average greater than, eg, 1.5% away from that target (eg, <9.85pL or >10.15pL) may be excluded from use. Range, standard deviation, variance, or another measure of spread may also or instead be used. For example, if it is desired to have a statistical model of droplets with a narrow distribution (eg, 3σ < 1.005% of mean), then droplets with measurements that do not meet this criterion can be excluded. It is also possible to use an elaborate/complex set of criteria that takes into account multiple factors. For example, an unusual mean combined with a very narrow spread may be good, eg if the spread (eg 3σ) away from the measured (eg abnormal) mean μ is within 1.005% then the associated droplet may be used. For example, if it is desired to use droplets with a 3σ volume within 10.00pL ± 0.1pL, one can exclude nozzle waveform pairs that produce a 9.96pL average value with a 3σ value of ± 0.8pL, but nozzles that produce 9.93pL with a 3σ value of ± 0.3pL Waveform pairing may be acceptable. Clearly, many possibilities are possible according to any desired rejection/exception criterion (1589). Note that this same type of processing can be applied to per-droplet flight angles and velocities, i.e., it is expected that flight angles and velocities paired per nozzle waveform will exhibit a statistical distribution and depend on measurements and statistical models derived from droplet measurement devices , some droplets can be excluded. For example, droplets with an average velocity outside 5% of normal or a variance in flight trajectory or velocity outside a specific target may be assumed to be excluded from use. Different ranges and/or estimation criteria may be applied to each drop parameter measured and provided by storage 1585 .

Note that depending on the rejection/exception criteria 1589, droplets (and nozzle waveform combinations) may be handled and/or disposed of in different ways. For example, as mentioned, specific droplets that do not meet desired criteria can be excluded (1591). Alternatively, it is possible to perform additional measurements selectively for the next measurement iteration of a particular pair of nozzle waveforms; as an example, if the statistical distribution is too broad, it is possible to perform additional measurements specifically for a particular pair of nozzle waveforms, thereby improving The tightness of the statistical distribution (such as variance and standard deviation depending on the number of data points being measured). According to reference number 1593, it is also possible to adjust the nozzle drive waveform, for example, to use higher or lower voltage levels (for example, to provide greater or less speed or a more consistent flight angle), or to reshape the waveform , resulting in an adjusted nozzle waveform pair that satisfies the specified criteria. At reference numeral 1594, the timing of the waveforms may also be adjusted (eg, to compensate for abnormal average velocities associated with particular nozzle waveform pairs). As an example (mentioned previously), slow droplets may be fired earlier in time relative to other nozzles, and fast droplets may be fired later in time to compensate for faster flight times. Many such substitutions are possible. Finally, at reference numeral 1595, any adjusted parameters (such as firing time, waveform voltage level or shape) can be stored, and optionally, if desired, the adjusted parameters can be applied to re-measure one or more associated liquids. drop. After each nozzle waveform pair (modified or otherwise) is qualified (passed or rejected), the method then proceeds to the next nozzle waveform pair at reference numeral 1597 .

As should be appreciated, the nozzle drive structure just described provides flexibility in printing different sized droplets. Use of fill volumes, drop volumes, drop velocities, and drop trajectories with precision per target zone enables use of defined criteria (within specification) with respect to nozzle/waveform and/or drop usage to vary fill volume and planning advanced technology. This provides a further quality improvement over conventional methods.

Figures 16-18B will now be used to provide further details on two contemplated droplet measurement devices (or systems) (ie predicted with respect to shadow plots and interferometry, respectively). Figures 16-17 will be used to illustrate one embodiment of a printer with a drop measurement system, while Figures 18A and 18B will be used to discuss shadow graphics and interferometry, respectively.

As mentioned previously, the present teachings disclose various embodiments of an industrial inkjet thin film printing system that includes a drop measurement device integrated into the printing system. Various embodiments of inkjet thin film printing systems of the present teachings may utilize imaging techniques such as shadow mapping or non-imaging techniques such as Phase Doppler Analysis (PDA) (an interferometry-based technique) that may be useful for inkjet printing Rapid measurement of multiple nozzles of a head provides a distinct advantage in that various embodiments of printhead assemblies used in thin film inkjet printing systems according to the present teachings may have multiple printheads. This rapid measurement can be performed in situ at any time during the printing process and can provide data that can include volume, velocity and trajectory for each droplet from each nozzle of each printhead. Joint data obtained from drop measurement devices integrated into inkjet thin film printing systems can be utilized to provide uniformity of ink volume delivered to each of the millions of pixels on an OLED panel display.

When depositing films in the manufacture of OLED panels, it is generally desirable to deposit a film material with a uniform thickness across the panel, as the thickness of the deposited film material generally affects panel performance, and good display uniformity is important for a good OLED panel Attributes. When inkjet printing methods are used to deposit films, droplets of ink are ejected from the printing device onto the panel substrate, and the thickness of the deposited film in each area of the panel is typically the same as the thickness of the film dispensed on that area of the panel. The volume of the ink is related, which is further related to the volume and placement of the droplets on the panel surface. It is therefore generally desirable to distribute the volume of ink evenly across the OLED panel display with respect to the volume and location of the dispensed droplets.

As noted above, an inkjet printing system may typically have at least one printhead with a plurality of inkjet nozzles, each nozzle capable of dispensing droplets of ink onto the panel surface. Typically, there are variations across the multiple nozzles of the printhead with respect to the volume, trajectory and velocity of the dispensed droplets. Such variations can arise from a number of sources including, but not limited to, variations in nozzle operating conditions, variations in inherent nozzle actuator behavior including aging of piezoelectric nozzle drivers, variations in ink, and variations in inherent nozzle size and shape. The effects of these variations may cause non-uniformity in volume loading across the panels. For example, a change in droplet volume may directly result in a change in the deposited volume, while a change in droplet velocity and trajectory may indirectly cause a change in the deposited volume of ink by causing a change in droplet placement on the OLED panel surface. In theory, these variations could be avoided by using only a single nozzle when printing, but printing with a single nozzle is too slow to be practical in real world manufacturing applications. In light of these variations in ink droplets dispensed from different nozzles and the design necessity of using multiple nozzles to obtain reasonable process speeds when using inkjet printing for manufacturing applications, it is desirable to have a method for providing uniform distribution across the OLED panel area. methods and associated devices for the volume of ink, regardless of the droplet variation between these nozzles.

A measurement device integrated into a thin film inkjet printing system according to the present teachings can be used to provide the volume for each nozzle of an inkjet printhead at any time during the run of the print process or upon interruption to the run of the print process , actual measurement of velocity and trajectory. Such measurements can provide mitigation of droplet-to-nozzle variation, allowing inkjet methods to achieve more uniform deposition of film materials. In some embodiments, such measurements can be used to tune printhead performance by adjusting the drive waveforms for each of the individual nozzles to directly reduce nozzle-to-nozzle drop variation. In some embodiments, such measurements can be used as input to a print pattern optimization system that can reduce nozzle-to-nozzle variation by adjusting nozzle selection for droplet deposition, thereby averaging out nozzle-to-nozzle variation in the deposited film. droplet changes. Various embodiments of measurement devices integrated into thin film inkjet printing systems of the present teachings may utilize various imaging techniques (eg, shadow mapping) or non-imaging techniques (eg, PDA). PDAs in particular can offer the distinct advantage of rapidly analyzing multiple nozzles of inkjet printheads, especially useful for systems with many nozzles and/or printheads.

In this regard, inkjet thin film printing systems according to various embodiments of the present teachings may include several devices and devices that allow for the reliable placement of ink droplets onto specific locations on a substrate. These devices and devices may include, by way of non-limiting example, printhead assemblies, ink delivery systems, motion systems, substrate support devices (such as floating tables or chucks), substrate loading and unloading systems, printhead maintenance systems, and printhead measurement systems. device. Additionally, the inkjet thin film printing system may be mounted on a stable support assembly which may include, for example, a granite or metal base. The printhead assembly may include at least one inkjet printhead wherein at least one orifice is capable of ejecting droplets of ink at a controlled rate; such ejected droplets are further characterized by their volume, velocity and trajectory.

Since printing requires relative motion between the printhead assembly and the substrate, the printing system may include a motion system (such as a gantry or split-axis XYZ system). Either the printhead assembly can move on a fixed substrate (gantry style), or both the printhead and substrate can move eg in a split-axis configuration. In another embodiment, the print station may be stationary and the substrate movable in the X-axis and Y-axis relative to the printhead, with Z-axis motion provided at either the substrate or the printhead. As the printhead moves relative to the substrate, droplets of ink are ejected at the correct time to deposit at the desired location on the substrate. Substrates are inserted and removed from the printer using the substrate loading and unloading system. Depending on the printer configuration, this can be done with mechanical conveyors, substrate floating stages, or robots with end effectors. Printhead measurement and maintenance systems can include permit measurements (e.g. drop volume verification, drop volume, velocity and trajectory measurements) as well as printhead maintenance procedures (e.g. wiping of inkjet nozzle surfaces, Substrates) of several subsystems. Given the various components that can be included in an inkjet thin film printing system, various embodiments of inkjet thin film printing systems according to various embodiments of the present teachings can have various footprints and form factors.

As a non-limiting example, FIG. 16 depicts an inkjet thin film printing system that may be used to print substrates such as, but not limited to, OLED panels, according to various embodiments. In FIG. 16, an inkjet thin film printing system 1600 utilizes a split axis motion system. Inkjet thin film printing system 1600 may be mounted on printing system support assembly 1610 , which may include tray 1612 carried by support frame 1614 . A base 1616 is mounted on the pan, wherein the base may optionally be constructed from granite or metal. An inkjet thin film printing system may include a motion system 1620, such as the indicated split axis motion system.

The motion system 1620 can be seen to include a bridge 1622 supporting an X-axis gantry 1624 which in turn mounts a Z-axis mounting plate 1626 . The Z-axis mounting plate in turn supports a printhead mount and clamp assembly 1628 for mounting an interchangeable printhead assembly 1640 . For the split-axis motion system 1620, the Y-axis rail 1623 may be mounted on the base 1616 to provide support for the Y-axis stage 1625, which in turn carries the base support assembly 1630; these various components provide support for mounting on the base Y-axis travel of the substrate on assembly 1630. As shown in FIG. 16, for various embodiments of the thin film printing system, the substrate support assembly 1630 may be a chuck. The substrate support assembly may be provided by a flotation table, for example, as described in detail in US Patent No. 8,383,202, which is hereby incorporated by reference. Inkjet thin film printing system 1600 may utilize system components that support one or more modular inkjet printhead assemblies, such as the individual printhead assemblies shown mounted in tool carousel 1645 . Providing for selective interchange of individual printhead assemblies can provide end users with flexibility regarding efficient sequential printing of various inks of various formulations on substrates during the printing process, such as during printing of OLED panel substrates. Note that this is not required for all embodiments, ie, other embodiments may feature a single printhead assembly that does not change between different printing processes. For example, one contemplated embodiment features component lines of multiple printers each performing a corresponding print process (eg, using a corresponding ink); the techniques described herein may be applied to each such printer.

The printhead assembly can include a fluidics system having an ink reservoir in fluid communication with at least one inkjet printhead for, for example, delivering OLED film-forming material to a substrate. In this regard, as shown in FIG. 16 , printhead assembly 1640 may include at least one printhead 1642 . In various embodiments, the printhead assembly may optionally include fluidic and electrical connections for each printhead. Each printhead in turn may have a plurality of nozzles or orifices capable of ejecting ink droplets at a controlled rate with measurable drop volume, velocity and trajectory. Various embodiments of printhead assembly 1640 may have between about 1 and about 30 printheads per printhead assembly. The printhead 1642 can have between about 16 and about 2048 nozzles, each of which can eject a drop volume between about 0.10 pL and about 200.00 pL.

Measuring the performance of each nozzle of a given printhead can include checking nozzle firing, and measuring drop volume, velocity, and trajectory. As mentioned before, having such measurement data can provide the ability to tune the head before printing to provide more uniform performance for each nozzle, or use the measurement data to provide printing algorithms that can compensate for differences during printing or these methods combination. Clearly, having a reliable and attainable data set of measured data provides a variety of ways in which the measured data can be used to compensate for droplet volume variations between nozzles, and allows combinations (from the same nozzle or from corresponding nozzles using different drive waveforms) of different The planned printing process of the volume of droplets. As mentioned above, measurement data is advantageously collected to derive a measured population representing the distribution for each nozzle, so that with a well-formed understanding of the expected variation for each such droplet parameter, Expectations for mean drop volume, trajectory and velocity can be derived and used in print planning.

In this regard, the depicted inkjet thin film printing system may include a drop measurement device or system 1650 , which may be mounted on a support 1655 . It is contemplated that various embodiments of the droplet measurement system 1650 may be based on the mentioned imaging or non-imaging techniques (such as shadow map or interferometry based methods). Embodiments utilizing non-imaging PDA technology may provide the distinct advantage of rapid analysis of between about 16 and about 2048 nozzles per printhead (eg, printhead 1642) (eg, approximately 50 times faster than typical imaging techniques) . Recalling that a printhead assembly may include, for example, thirty printheads (i.e., where the printing system uses more than 10,000 nozzles), this allows for all nozzles (and Fast in-situ dynamic measurements within the printer of all alternative drive waveforms, if appropriate for the embodiment. Additionally, various embodiments of systems and methods according to the present teachings may utilize PDA measurement devices integrated into air enclosure assemblies and systems that may house printing devices. These systems and methods utilizing PDA measurement devices integrated into air enclosure assemblies and systems housing printing devices can provide rapid in-situ measurement of multiple nozzles in a printhead. This is especially useful to ensure uniform deposition volumes on large substrates eg with one or more OLED devices, and to reduce any speckle effects.

Reference numeral 1617 is used to designate the zone of the inkjet printing device associated with the drop measurement system 1650 . This area is shown in enlarged detail in FIG. 17 .

As shown in FIG. 17, a printhead mount and jaw assembly 1728, itself again carried by the motion system's Z-axis mount 1726, can hold the printhead assembly 1740 during printing. In this regard, the motion system is used to position the printhead assembly 1740 for measurement near the drop measurement system 1750 (eg, in a service area or station). As previously described, drop measurement system 1750 can be designed for selective engagement and disengagement while printhead assembly 1740 is in this position. In the case of large printhead assemblies (e.g., with several thousand nozzles), this configuration allows the drop measurement system to perform tests while the printhead assembly 1740 is "parked" with other testing or calibration equipment or processing (not shown). out) while performing other tests. For example, the printhead nozzles can be purged, cleaned or otherwise managed using a simultaneous process applied to help minimize any downtime of the entire inkjet printing system; this helps to maximize manufacturing productivity. As previously described (and as explained below with respect to FIG. Other unavoidable tasks associated with the operation stack the droplet measurement to minimize any system downtime. Each nozzle of printhead 1742 of printhead assembly 1740 may be aligned to measurement zone 1756 for measuring droplets ejected from each nozzle using drop measurement system 1750 . Note that in this embodiment, individual printheads 1742 may move relative to the other printheads for analysis, but again, this is not required for all embodiments. For example, it is also possible to have each printhead mounted statically during measurement, wherein the drop measurement system advances to each printhead position and to each nozzle position within a given printhead; as previously described, such Allows simultaneous processing or "stacking" of multiple servicing operations while the printhead assembly is parked. It is also possible to use multiple drop measurement systems to independently measure eg different nozzles of different spatially separated print heads.

For illustration purposes, it should be assumed that the droplet measurement system is a PDA device (i.e., an interferometry-based device) with a light source (such as a laser source and light-transmitting optics beam splitter and transmissive lens). In addition, such a PDA device can also have a light-receiving means with a receiving lens and a plurality of photodetectors. For example, first optical side 1752 of droplet measurement system 1750 can source one or more light beams for measurement and focus light on measurement region 1756, as indicated by dashed lines, while second optical side 1754 can place The measurement light that has been scattered from the droplets in the measurement region 1756 is passed to the light receiving device and one or more photodetectors.

Droplet measurement system 1750 may interface directly or remotely to a computer or computing device (not shown). Such a computing device may be configured to receive signals from each printhead 1742 of printhead assembly 1740 representing the measured drop volume, velocity, and trajectory for each drop produced by a nozzle (or combination of nozzle waveforms) . Again, multiple measurements of many drops from each nozzle/nozzle waveform pairing are advantageously performed to derive a statistical population representative of each producible drop.

As previously described in connection with Figures 11 and 12, various embodiments of the printing system may be housed in an air enclosure that provides an inert, low particle environment in which droplet measurement preferably occurs. In one embodiment, the droplet measurement is performed in the normal atmosphere used for printing, eg in the same normal (closed) chamber. In a second embodiment, a separate fluidically isolated chamber is used for the measurements as part of the service station area.

Figure 18A shows the layout of a droplet measurement system 1801 specifically configured to use the shadow map technique. In particular, printhead 1803 is seen at a position where it will eject droplets 1805 into vessels (not shown in Figure 18A). During the flight of the droplet 1805, the droplet traverses the measurement region where the droplet is illuminated by a light source; in FIG. A flash of light 1807 is directed into the measurement region (eg, from below the measurement plane as previously exemplified in connection with FIGS. 2A-2E or 16-17 ). The optics direct light to illuminate a relatively large area represented by focus or redirection path 1811 to repeatedly expose droplets at different locations in rapid succession for capture in a single image frame. Figure 18A thus shows three different positions of the same droplet jointly imaged together representing different flickers of the strobe. So, for example, the image frame under analysis will show multiple droplets that appear to be at different locations (i.e., multiple instances by reference numeral 1805), but these are actually at different locations along the flight trajectory same droplet. A second set of optics 1813 provides light collection and focusing so that the captured image clearly depicts the droplet outlines used by the image processing software to calculate the droplet volume and the shading that represents the variable amount of droplet diameter. As should be appreciated, by imaging the same drop during its flight at multiple locations, a drop measurement system can use the resulting one image to calculate drop volume, velocity, and trajectory; The drop mass, and therefore, the volume and relative position of the drop is used to calculate both velocity and trajectory. For example, at a "lower position" within the captured image frame, a droplet that is apparently increasing in diameter is traveling towards the light receiving light device 1813, and conversely, a droplet that is decreasing in diameter is traveling away. The light-receiving light device 1813 in turn delivers the captured light to a camera 1815 (eg, a high-resolution CCD camera that images the drop outline and shadow depicted by graphic 1817). The droplet measurement system optionally provides control over the zoom/focus (1819) and/or XY position (1821) of the light receiving device, all within the supervisory computer system 1823 (and in one or more of the computer systems used for such control under the control of instructions stored on a non-transitory machine-readable medium used by multiple processors). In one embodiment, as previously mentioned, the light receiving device and light source are mounted to a common chassis and transported together, providing a fixed focal length path, but this is not required for every embodiment. The depicted system captures the travel of each droplet in microseconds while the droplet parameters are then calculated by image processing application software 1825 run by computer system 1823 . As an example, the computer may provide display and visualization (1827) of droplets and/or measured parameters, and may calculate values for various parameters such as volume, velocity, and trajectory (1829, 1831, and 1833) or other parameters . Note that computer system 1823 may be part of an inkjet printing system, or it may also be remote (e.g., connected by a local area network "LAN" or wide area network "WAN" (e.g., the Internet) to collect data on a remote basis); similar Alternatively, display and visualization 1827 may also be provided at a location remote from computer system 1823 via a LAN or WAN. As indicated by reference numeral 1835, the computer system 1823 compiles the measured parameters to form a given nozzle (and a waveform for a given nozzle if a particular embodiment of the printing system uses an alternate drive waveform) for producing droplets. paired) measure the statistical population. Computer system 1823 optionally stores in database 1837 the individual measurements themselves and/or statistical summaries (e.g., mean and standard deviation or variance in the case of a normal distribution, and comparable metrics if other distribution types are supported) ). With sufficiently robust measured populations, the database can then be used in the planning and/or optimization of the printing process described above, for example using a specific combination of droplet averages to obtain a composite fill per target area, wherein the composite fill can be Based on different droplet volumes (eg from different nozzles and/or drive waveforms).

Figure 18B shows the layout of a droplet measurement system 1851 specifically configured to use PDA (interferometry) technology. The printhead is shown in the position for the measurement indicated at 1853 . The printhead will eject a drop (eg, using a particular drive waveform) from a particular nozzle down into the drop measurement zone, as indicated by reference numeral 1855 . As with the previous embodiments, the drop measurement system may optionally be designed for three-dimensional transport relative to the parked printhead so that the drop measurement region is effectively "brought into" the drop flight path of a particular nozzle. A light source (in this case a laser 1857 ) generates a beam of light 1859 which is directed to become incident on a beam splitter 1861 . The beam splitter generates two or more optical beams 1863 and 1864 (only two are shown in FIG. 18B ), which the optical device 1865 then redirects in a converging manner, i.e. The locations of the drops intersect as indicated by reference numerals 1866 and 1867 . Note that optics 1865 optionally provide laser light 1857 to be mounted below the measurement plane (see discussion of FIGS. One or more of the light paths) are redirected around the periphery of the vessel to the measurement region. Note that reference numeral 1869 is used to denote the generally continuous dimension of the illuminating optics (eg, light paths 1866 and 1867). As previously described, using interferometry-based techniques, the diffraction pattern is captured from a directional angle offset to the continuous dimension 1869 , as represented by the angle measurement 1873 . This angular offset is typically ninety degrees, but other capture orientations may also be used. Accordingly, measurement light 1871 is received by a second set of optics 1875 (labeled "Optics 2") offset at this angle from the incident light, and redirected by non-imaging detector 1877 with respect to the deposition-plane measurement. These detectors produce data representing a diffraction pattern, as shown in graph 1879; as will be appreciated (e.g., by comparing this graph 1879 with graph 1817 from FIG. 18A ), the spacing of the lines in the diffraction pattern provides the droplet volume where the spacing is processed to measure droplet volume much more quickly than in the case of the imaging technique represented in Figure 18A. Note that while FIG. 18B shows the use of one light source 1857 and two incident beams 1866 and 1867, other embodiments use more than one light source and more than one incident beam, for example, to capture droplet velocity, trajectory and other parameter. As for the embodiment of Figure 18A, in Figure 18B the computer (1881) optionally provides the zoom/focus (1883) and XY transport of the measurement optics, runs the appropriate software (1887) to calculate the various droplet parameters, and provides Display and Visualization (1889). As before, these various elements may be integrated with the printer or manufacturing equipment, or may be distributed across a WAN or LAN, controlled by separate processors of respective computers or servers. As before, measured parameters may include droplet volume (1891), velocity (1893) and trajectory (1895), where the data represent statistical population (1897) stored in a database (1899) for scan planning purposes ). The scan plan can again combine drop parameters from different nozzles and/or waveforms to perform precise filling of the target zone intentionally based on multiple different drop volumes.

It was mentioned before that the droplet parameters may change over time, eg depending on system parameters, ambient conditions or ink properties. Industrial printing systems therefore advantageously update drop measurements not only for individual drops but also for the statistical population of each drop (and the expected average volume/velocity and trajectory of each drop) on a relatively frequent basis; this has Helps ensure always accurate and up-to-date precise drop data, allowing reliable adherence to planned drop combinations for maximum tolerances for synthetic ink fills. It has been found that the droplet parameters actually change somewhat slowly, for example with a detectable change every 2 to 12 hours. The use of in situ droplet measurements makes it possible to repeatedly perform dynamic measurements and construction of new statistical populations of the measured parameters in this time frame; note that with conventional techniques many hours may be consumed to measure large-scale printing head or printhead assembly; by using rapid technology (such as the PDA described above), update all Statistical measurements become possible. A system utilizing some or all of the above techniques thus facilitates and enables industrial printers with recalibrated droplet measurement parameters based on statistical distribution within the mentioned 2 to 12 hour time frame, and thus facilitates use in target zones More accurate printing within the maximum tolerance of fill variations.

As previously stated, in one contemplated embodiment, the printer is controlled intermittently or continuously to perform drop parameter measurements any time the printer is not actively printing. This helps to maximize the uptime of the manufacturing line. As noted, in one embodiment, the printhead assembly may be diverted for drop parameter measurements any time the printhead assembly of the printer is not in use. For example, any time a substrate is loaded or unloaded, advanced between chambers, or dried, cured, or otherwise processed, the print gantry can transport the printhead assembly to the service station for drop measurement and/or other service operations. Such operation helps further to provide frequent dynamic updates of the droplet statistical population for each nozzle, as described; optionally employed as a PDA-based droplet measurement device (e.g. interferometry-based techniques) , such a control scheme can render the drop measurement task transparent to any desired printing operation. Note that in contemplated systems, this control is effected by control software running on at least one processor that manages the print process; up.

FIG. 19 shows an example 1901 of a flow for such control processing. As mentioned, the process may optionally be implemented by instructions stored on a non-transitory machine-readable medium, which when executed cause at least one processor to perform/provide the recited steps.

Figure 19 is divided into three general areas 1903, 1905, and 1907 representing startup and offline initialization processing, online printing, and offline special operations, respectively. As the system is powered on, the system typically undergoes an initialization process 1909 in which new measurements are taken for each nozzle to find the statistical population, as already described above. At the same time, a calibration process (not shown) may also be invoked to select multiple nozzle firing waveforms for each nozzle (e.g., using the aforementioned iterative process to select the one that yields drop volumes within ±10.0% of the target drop volume). 16 waveforms). A statistical population is thus derived for each such waveform and/or nozzle including the mean drop volume and expected spread. As before, in one embodiment a fixed number of measurements are performed per droplet, while in another embodiment the number can vary from nozzle to nozzle (or per nozzle waveform pair) to achieve a sufficiently stringent In addition, in one embodiment, a validation or qualification process may optionally be applied, wherein nozzles (or nozzle waveform pairs) that do not produce drops with the desired parameters may be disqualified from use in print planning qualifications. Measurements and/or statistics are then stored ( 1911 ), as applicable, for each nozzle and for each nozzle waveform pairing. Note that this startup calibration can be performed right when the system is first turned on (or on a one-time basis), and in other embodiments, the calibration is performed every time the system is powered up again. For example, it may be advantageous (if the production line is only running during a part of the day) to store previously calculated droplet parameters (and then update these parameters according to the process discussed below). Alternatively, new parameters can be recalculated with each power cycle.

The system also optionally receives parameters defining the printing process and substrate parameters (1913), and automatically plans the drop combination and scanning process (1915) as previously described. In other contemplated implementations, such as where the printer is part of a component line for a particular OLED display product, these parameters and schedules may be constant. However, if the droplet parameters may change, the print schedule may also change, and thus process 1915 may optionally be re-executed any time the statistical parameters change (e.g., each time the droplet measurement system is engaged as an automated background process) (eg, as indicated by designation 1917).

Using the system print parameters and averages for available drop parameters (ie, for each nozzle or pair of nozzle waveforms), at reference numeral 1919, the system can then enter an online mode where it performs printing as desired. That is, the substrate can be loaded or transferred into a printer, and printing of one or more thin film layers of the OLED device can then be performed as desired. However, to minimize equipment downtime, each printhead nozzle is subjected to updated drop measurements each time printing is stopped (eg, to load or unload a substrate) to update the statistical drop pattern on an intermittent or periodic basis. live. For example, it is expected that a typical print process for a large HDTV substrate (representing several large sized TV screens) can be completed in about 90 seconds, where the completed substrate is then unloaded or Proceed to another chamber (1920). During this 15-30 second interval, the printer is not used for printing, and accordingly drop measurements can be performed during this time. For example, the control software for the printer controls the substrate transport mechanism to move the old substrate out of reach of the printhead carriage, and at the same time, the control software moves the printhead assembly to the service station for drop measurement and/or other service functions. Once the printhead assembly is parked (1921), the control software selectively engages the drop measurement system at reference numeral 1923 to perform drop measurement. As previously described, the measurements can yield statistical populations for droplets produced by different nozzles or pairs of different nozzle waveforms. To replenish any previously stored measurements, the drop measurement system is cycled, taking as many drop measurements as possible until the next substrate is loaded, or otherwise it is time to restart printing. For example, per function blocks 1925, 1927, 1929, and 1931, the drop measurement system: (1) measures multiple drops for a given nozzle or nozzle/waveform pairing; (2) stores or updates the results in memory (i.e. , either store new additional measurement data as raw data, or store updated averages or statistical summaries, or both); (3) identify the nozzle address (or nozzle waveform identifier for subsequent measurement cycles); and (4) Then continue with another nozzle or pair of nozzle waveforms as appropriate for another set of measurements. The process of loading/unloading substrates may potentially take a variable amount of time, and therefore, when the system is ready for a new print cycle, the control software issues an interrupt or function call (1933) to appropriately break out of service operations (1935) ( For example including a drop measurement system), and return the printhead assembly to active printing (1919). As mentioned, the control software also transparently updates or recalculates drop combinations that may no longer be valid due to updates to the drop per nozzle average. Note that since the drop measurement cycle stores the address or position (1930) for subsequent measurement cycles, the system effectively performs drop measurement for a small window of nozzles/droplets, continuing on a loop basis through the Thousands of different nozzle/nozzle waveform pairs are available for use in . Printing is then performed until the next substrate iteration is complete, at which point the substrate is unloaded and the measurement/service cycle continues. By stacking drop measurements as described after other printer operations, these techniques help to substantially reduce any system downtime, again maximizing manufacturing throughput. Note that while the depicted method engages the droplet measurement system every loading cycle, not all embodiments require this, i.e. it may be desirable to update the droplet measurement at a certain rate (e.g., every 8 hours), and thus, if using the proposed To more quickly build a statistical population of droplets due to a given stacking operation, it may be desirable to instead run a different service operation during substrate loading and/or transfer and/or Curie operations. Figure 19 also shows a special maintenance box 1937 associated with special ad-hoc actions, such as requiring a printhead change or another off-line process.

As should be appreciated, the mentioned techniques facilitate high uniformity over the fabrication process, especially the OLED device fabrication process, and thus enhance reliability. These techniques in some embodiments are facilitated, at least in part, using drop measurement techniques that enable precise drop combination and spot suppression by using dissimilar combinations of nozzles and drop volumes. Furthermore, the teachings set forth above help to provide control efficiencies in a manner that is calculated to reduce overall system downtime, particularly with regard to the speed of droplet measurements and the stacking of such measurements for other system processes. Faster and cheaper manufacturing processes designed for both flexibility and precision.

In the foregoing description and drawings, specific terms and drawing symbols have been set forth to provide a thorough understanding of the disclosed embodiments. In some cases, the terms and symbols may imply specific details not required to practice those embodiments. The terms "exemplary" and "embodiment" are used to indicate an example rather than a preference or requirement.

As indicated, various modifications and changes may be made to the embodiments presented herein without departing from the broader spirit and scope of the disclosure. For example, a feature or aspect of any embodiment may be applied in combination with any other embodiment or in place of an equivalent feature or aspect thereof, at least where practicable. Thus, for example, not all features are shown in every figure and, for example, a feature or technique shown according to an embodiment of one figure should be assumed to be alternatively usable as an element or combination of features of any other figure or embodiment , even if not specifically indicated in this specification. Accordingly, the specification and drawings are to be considered in an illustrative rather than a restrictive sense.

Claims (as amended under Article 19 of the Treaty)

1. A method of generating control data for nozzles of a printhead to deposit an aggregated volume of ink in at least one target area of a substrate, said aggregated volume being within a predetermined volume tolerance, each of said nozzles A method of generating at least one corresponding droplet volume, the method comprising:

receiving information indicative of a statistical population representing the volume of each corresponding droplet;

computing droplet combinations for which mean values representing corresponding droplet volumes sum to a value confined within said predetermined tolerance range; and

generating control data dependent on the combination, the control data being sufficient to command relative movement between the printhead and the substrate such that each of the nozzles associated with the combination aligns with the first target in the at least one target zone The zones are approached, and each of the nozzles associated with the combination is commanded to fire to deposit each droplet volume associated with the combination in the first target zone.

2. The method of claim 1, wherein the predetermined tolerance range comprises a range centered on the target volume, wherein the range is represented by the target volume plus or minus two percent of the target volume Contemplated is, and wherein, generating control data comprises generating control data in a manner suitable for using a combination of droplets from at least two of the nozzles to produce an aggregated target volume for a target zone of said at least one target zone.

3. The method of claim 2, wherein the method is embodied as a method of controlling an inkjet printing mechanism, wherein the method further comprises controlling the inkjet printing mechanism to perform the same operation as the control data depending on the control data. The firing and relative movement of the nozzles associated with the above combinations.

4. The method of claim 3, wherein the inkjet printing mechanism includes a drop measurement device, and wherein receiving the information includes engaging the drop measurement device to empirically determine each of the drop volumes, And wherein receiving information includes receiving information from a plurality of measurements for each nozzle with the drop measurement device.

5. The method of claim 1 embodied as a method of generating control data for nozzles of a printhead to deposit within said predetermined tolerances in respective target areas of said substrate The aggregated volume of the ink, where:

performing a combined calculation for each of the corresponding target zones; and

performing generation of control data to generate said control data in relation to each combination, said control data being sufficient to command relative movement between said printhead and said substrate to simultaneously correlate with each combination The at least one nozzle associated with each combination is proximate to the corresponding target zone and is sufficient to command the at least one nozzle associated with each combination to fire to simultaneously deposit a drop volume in the corresponding target zone.

6. The method of claim 1, wherein:

The method further includes: identifying a set of predetermined nozzle control waveforms, each predetermined nozzle control waveform, when applied to the nozzle, produces a corresponding ink drop volume; and

The combination for each of the respective target zones is associated with an integer number of droplets and is adapted to cover at least two different ones of the nozzles and at least two different ones of the predetermined nozzle control waveforms .

7. The method of claim 1, wherein the at least one target zone comprises target zones, each of the target zones is configured to achieve a predetermined volume tolerance range, wherein each target zone is on a first axis wherein the relative motion comprises at least two scans each in a direction substantially perpendicular to the first axis, the at least two scans being mutually offset according to a sequence of at least one geometric step, wherein each of said nozzles has a positional relationship relative to each other, and wherein:

The method further comprises calculating at least one combination of droplets for which corresponding droplet volume averages sum to a value confined within a predetermined tolerance range for each of the target zones;

generating control data is performed in a manner associated with a particular combination of droplets for each of the target zones; and

The method further includes selecting each geometric stride in a variable-sized and combination-specific manner.

8. The method of claim 1, wherein:

said printhead has not less than one hundred and twenty-eight print nozzles;

The method is further embodied as a method of controlling a split-axis inkjet printing mechanism including a printhead, a printhead motion control mechanism, and a substrate motion control mechanism; and

Generating the control data further includes causing the machine to control the inkjet printing mechanism to perform relative motion between the printhead and the substrate such that the substrate motion control mechanism moves the substrate in a first direction relative to the printhead, and the printhead motion control mechanism causes The printhead moves relative to the substrate in a second direction independent of the first direction.

9. The method of claim 1, embodied as a method of forming an organic light-emitting layer for an electronic device, wherein the ink comprises an organic material carried by a solvent, an organic monomer or an organic polymer at least one.

10. A printer, comprising:

a printhead having nozzles for printing ink onto an array of target areas on a substrate;

at least one motion mechanism to provide relative movement between the printhead and the substrate, including scanning for each of the substantially continuous movements between the printhead and the substrate;

storage to store data identifying drop volume averages for each of the nozzles; and

Instructions stored on a non-transitory machine-readable medium that, when executed, cause the printer to

receiving an electronic file defining a desired fill volume for each target zone that will be achieved within associated volume tolerances for each target zone, and

Controlling the kinematics and printhead to extract one or more print fluids from one or more nozzles for each target zone based on data identifying drop volume averages for each nozzle and a file defining a fill volume for each target zone. drop combinations, wherein the corresponding drop volume averages sum to fill values within the associated volume tolerance;

Wherein, the instructions will control the motion mechanism and the print head to deposit fill values for corresponding target areas, so as to fill all target areas.

11. The printer of claim 10, further comprising an air enclosure to contain the printhead and the substrate, and an atmosphere control system to inject a controlled atmosphere into the air enclosure during printing.

12. A printer as claimed in claim 10, wherein the substrate is to form a display device and has three arrays of target areas of the substrate, each array of target areas representing a corresponding color component of a pixel of the array, and wherein , the printer includes at least three print heads, each color component includes at least one, to print a corresponding ink onto a target area of a corresponding one of the three arrays.

13. The printer of claim 10 , further comprising: a drop measurement device, the instructions, when executed, further cause the printer to engage the drop measurement device for each of the nozzles for a given The nozzles measure the drop volume a plurality of times to obtain a statistical population for a given one of the nozzles, this data identifying measurements obtained from the drop measurement device for each of the nozzles Droplet volume average.

14. The printer of claim 13 , wherein the instructions, when executed, further cause the printer to engage the drop measurement device on an intermittent basis to update the average droplet volume.

15. A method of controlling an inkjet printer having a printhead having nozzles controlled to eject respective droplets of ink, the method comprising:

measuring a parameter associated with a plurality of corresponding droplets from one of the nozzles to find a statistical population of parameters for the one of the nozzles;

repeatedly measuring the parameters for each of the other nozzles to find a corresponding statistical population for each of the nozzles; and

Each statistical population is processed to associate a corresponding mean value for the parameter and a corresponding spread measure representing the distribution of the parameter.

16. The method of claim 15, wherein the parameter is one of drop volume, drop velocity, or drop trajectory angle.

17. The method of claim 15, wherein the inkjet printer is adapted to use a plurality of alternate firing drive waveforms per nozzle, wherein:

performing the measurement of said parameter for said one of said nozzles for a particular one of a plurality of alternative fire drive waveforms available for use with said one of said nozzles, to finding a statistical population corresponding to said one of said nozzles and said particular alternate firing drive waveform; and

The method further includes repeatedly measuring the parameter for each other of the plurality of alternative fire drive waveforms available for use with one of the nozzles to find Corresponding statistical population;

Repeating measuring the parameter for each of the other nozzles includes: for each other of the plurality of alternative fire drive waveforms available for use with each other of the nozzles. waveforms, repeatedly measuring said parameters to find individual statistical populations; and

For each of the plurality of alternative firing drive waveforms available for use with each respective one of the nozzles, processing each statistical population is performed to combine the Means are associated with extended measures for distributions.

18. The method of claim 15, wherein the method further comprises: controlling printing to deposit a selected plurality of droplets from corresponding nozzles within a given substrate target area, the selected plurality of droplets The droplets are selected to produce a composite ink fill volume for the target zone equal to the sum of the average values associated with the droplets produced by respective ones of the nozzles.

19. The method of claim 15, wherein the measuring and repeating are performed to obtain a measured threshold population for each of the nozzles, and wherein the measured threshold population represents At least 24 measurements.

20. An inkjet printer comprising:

a print head having nozzles for ejecting corresponding droplets of ink;

a drop measurement device for measuring a parameter associated with a drop of ink ejected from a corresponding nozzle by collecting light from a measurement zone through which the drop of ink travels;

wherein the inkjet printer includes a service station and means for selectively moving the printhead to the service station; and

Wherein the inkjet printer further comprises means for selectively moving the measurement zone in each of the three dimensions independently.

21. An inkjet printer comprising:

a printhead having nozzles for ejecting respective droplets of ink;

a service area, and a printhead transport mechanism for selectively moving the printhead to the service area; and

a drop measurement device for selectively engaging the printhead when the printhead is in the service zone, the drop measurement device for collecting the flow from the measurement zone through which a droplet of ink travels light to measure parameters associated with droplets of ink ejected from corresponding nozzles, the droplet measurement device further comprising a movement mechanism operable to link the measurement zones in each of three dimensions, thereby The measurement zone is positioned adjacent to any of the nozzles after the printhead has been moved into the service area.

22. The inkjet printer of claim 21 , wherein the drop measurement device includes at least one optical detector and hardware or software to measure an interference pattern of light detected by the at least one optical detector at least one of the

23. The inkjet printer of claim 21 , wherein the drop measurement device includes at least one image sensor and at least one of hardware or software to measure shadows detected by the at least one optical detector .

24. The inkjet printer of claim 21 , wherein the printhead is positioned in a parked position when moved to the service area, wherein the nozzles of the printhead are adapted to A droplet of ink is ejected within a distance h of a position, wherein the moving mechanism is adapted to selectively move the measurement zone in a direction substantially parallel to the dimension of the distance h, such that the measurement zone is at within said distance h to perform drop measurement, and wherein said movement mechanism is operable to selectively move between two dimensions parallel to a nozzle bearing surface of said printhead and substantially orthogonal to said distance h The measurement zone is moved independently in each of the three dimensions to measure droplets from the corresponding nozzles.

25. The inkjet printer of claim 24, wherein said drop measurement device includes at least one light path routing mechanism to direct measurement light from a drop traveling through said measurement zone away from said nozzle bearing surface-directed to an optical detector located at a distance along a dimension of distance h greater than distance h, wherein the droplet measurement apparatus includes at least one optical path routing mechanism to direct source light from a light source to a traveling The light source is also located at a distance along the dimension of distance h greater than distance h through the droplet of the measurement zone, and wherein each light path routing mechanism comprises one of a mirror, a prism or a fiber optic cable.

26. An inkjet printer comprising:

a printhead for printing ink onto a substrate, the printhead having nozzles;

a service area and a printhead transport mechanism for selectively transporting the printheads to the service area;

Droplet measuring equipment; and

a control mechanism for causing the printer to print ink as a thin film onto the substrate on a continuous basis, and between periods when the printhead is caused to print ink onto the substrate, causing the the printhead transport mechanism transports the printhead to the service area and causes the drop measurement device to measure a corresponding drop volume from each of the nozzles;

Wherein said control mechanism is adapted to control said droplet measurement device so as to construct a statistical population representing each respective droplet volume in between successive ones of said substrates, and thereby calculate at least one representative of each Statistical parameter of droplet population.

27. The inkjet printer of claim 26, wherein the inkjet printer is embodied as adapted to produce one or more layers of the same product on respective ones of the substrates according to a common set of printing instructions production apparatus, and adjusts said common set of print instructions in dependence on an updated statistical population of drop volumes from said drop measurement device that have been measured between successive ones of said substrates.

27. A method of controlling an inkjet printer having a printhead with nozzles, comprising:

using a drop measurement device of the inkjet printer to construct a statistical distribution of drop parameters for each of the nozzles via repeated measurements of drops produced by each of the nozzles;

comparing at least one statistical measure associated with said statistical distribution for each of said nozzles to a threshold;

validating or rejecting droplets produced by respective ones of the nozzles depending on the comparison; and

A print process is planned that excludes use of drops produced by respective ones of the rejected nozzles.

Claims (27)

1. the control data generating the nozzle being used for printhead is with the method for the polymerization volume of ink deposition at least one target area of substrate, described polymerization volume is in predetermined volume marginal range, each in described nozzle generates at least one corresponding droplet size, and described method comprises:

Receive the information representing statistics population, statistics population represents each corresponding droplet size;

Calculating drop combines, and represents that the mean value of corresponding droplet size adds up to the value be limited in described predetermined marginal range to it; And

Depend on that described combination is to generate control data, described control data is enough to order printhead with the relative motion between substrate to make the first object district in each and at least one target area described of the nozzle be associated with described combination close, and orders each the carrying out of the nozzle be associated with described combination to launch in first object district, deposit each droplet size be associated with this combination.

2. the method for claim 1, wherein, described predetermined marginal range comprises the scope centered by target volume, wherein, described scope by represented by target volume scope plus-minus target volume 2 percent contain, and wherein, generating control data comprises being suitable for using the mode of the combination of the drop from least two in nozzle to generate control data to produce the polymerization target volume for the target area of at least one target area described.

3. method as claimed in claim 2, wherein, described method is embodied as the method controlling ink jet printing mechanism, and wherein, described method comprises control ink jet printing mechanism further to depend on described control data to perform transmitting and the relative motion of the nozzle be associated with described combination.

4. method as claimed in claim 3, wherein, described ink-jet printer structure comprises drop measurement device, and wherein, receive this information and comprise that to engage drop measurement device each with what determine in droplet size by rule of thumb, and wherein, reception information comprises and utilizes drop measurement device from the multiple measurements for each nozzle to receive information.

5. the method for claim 1, is embodied as following method: the control data generating the nozzle being used for printhead, to be deposited on the polymerization volume of the ink in described predetermined marginal range in the corresponding target area of described substrate, wherein:

For each calculating performing combination in corresponding target area; And

Perform the generation of control data, described control data is generated in the mode relevant to each combination, described control data is enough to printhead described in order and the relative motion between described substrate, with side by side make at least one nozzle of being associated to each combination and corresponding target area close, and be enough at least one nozzle that order is associated with each combination launch, with side by side deposit fluid drop volume in corresponding target area.

6. the method for claim 1, wherein:

Described method comprises further: the set identifying predetermined Jet control waveform, and each predetermined Jet control waveform produces corresponding ink drop volumes when being applied to nozzle; And

Be associated with the integer of drop for each combination in corresponding target area, and the Jet control waveform that at least two different spray nozzles being suitable for containing in nozzle and described predetermined Jet control waveform at least two are different.

7. the method for claim 1, wherein, at least one target area described comprises each target area, each in order to realize predetermined volume marginal range in each target area, wherein, each target area offsets from each other on the direction of the first axle, wherein, relative motion comprises each at least twice sweep substantially on the direction vertical with the first axle, described at least twice sweep offsets from each other according to the sequence of at least one geometric pace, wherein, each in described nozzle relative to each other has position relationship, and wherein:

Described method comprises further: at least one combination calculating drop, and droplet size mean value corresponding for it adds up to and is limited to for the value in each predetermined marginal range in each target area;

With to combine relevant mode for each certain droplet in each target area and perform generation control data; And

Described method comprise further with variable-size and each geometric pace of the way selection relevant to particular combination.

8. the method for claim 1, wherein:

Described printhead has and is no less than 128 printing nozzles;

Described method is embodied as a kind of method controlling declutch shaft ink jet printing mechanism further, and declutch shaft ink jet printing mechanism comprises printhead, printhead motion control mechanism and basement movement controlling organization; And

Generate control data to comprise further and cause apparatus control ink jet printing mechanism to perform the relative motion between printhead and substrate, to make basement movement controlling organization make substrate move relative to printhead in a first direction, and printhead motion control mechanism makes printhead move relative to substrate independent of in the second direction of first direction.

9. the method for claim 1, is embodied as the method for a kind of formation for the organic luminous layer of electronic equipment, and wherein, described ink comprises at least one in the organic material carried by solvent, organic monomer or organic polymer.

10. a printer, comprising:

There is the printhead in order to the nozzle of pad-ink on based target area array;

At least one motion, in order to provide the relative movement between printhead and substrate, comprises each scanning in the motion of continuous print substantially between printhead and substrate;

Holder, is used for the data of each droplet size mean value in nozzle in order to storaging mark; And

Be stored in the instruction on non-transient state machine readable media, this instruction causes printer when being performed

Receive e-file, its definition is used for the expectation packing volume of each target area, and the expectation packing volume of each target area will realize in association volume marginal range, and

Controlled motion mechanism and printhead are used for the droplet size mean value of each nozzle data based on mark are come for each target area from the one or more printed droplets combinations nozzle with the file of definition for the packing volume of each target area, wherein, corresponding droplet size mean value adds up to the Filling power in the volume marginal range of association;

Wherein, controlled motion mechanism and printhead are deposited Filling power, to fill all target areas for corresponding target area by described instruction.

11. printers as claimed in claim 10, comprise further: in order to comprise the gas inclusion of described printhead and described substrate and the atmosphere control system in order to inject controlled atmosphere during printing in gas inclusion.

12. printers as claimed in claim 10, wherein, described substrate will form display device, and there are three arrays of the target area of substrate, the target area of each array represents the corresponding color components of the pixel of array, and wherein, described printer comprises at least three printheads, each color components comprises at least one, to print corresponding ink on the target area of of the correspondence in three arrays.

13. printers as claimed in claim 10, comprise further: drop measurement device, described instruction causes described printer to engage described drop measurement device further when being run, with for each given nozzle repetitive measurement droplet size in described nozzle, in the hope of the statistics population for the given nozzle in described nozzle, this Data Identification carries out measuring and the droplet size mean value obtained from described drop measurement device for each described nozzle.

14. printers as claimed in claim 13, wherein, described instruction causes described printer on interrupted basis, engage described drop measurement device further when being run, to upgrade for each droplet size mean value in described nozzle.

15. 1 kinds of controls have the method for the ink-jet printer of the printhead of the nozzle with the corresponding drop being controlled as ejection ink, and described method comprises:

Measure the parameter associated to the multiple corresponding drop from described nozzle, to obtain the statistics population of the parameter for described in described nozzle;

Duplicate measurements is used for each parameter in other nozzle, to obtain for each corresponding statistics population in described nozzle; And

Process each statistics population, with for described parameter corresponding mean value and represent that the respective extension of distribution of described parameter is estimated and be associated.

16. methods as claimed in claim 15, wherein, described parameter is one in droplet size, liquid drop speed or droplet trajectory angle.

17. methods as claimed in claim 15, wherein, described ink-jet printer is applicable to the transmitting drive waveforms using multiple replacement for each nozzle, wherein:

For specific one the transmitting drive waveforms of replacing that can be used in the transmitting drive waveforms of the multiple replacements used together with the nozzle of in described nozzle, the measurement of described parameter is performed, to obtain the statistics population corresponding to the transmitting drive waveforms of the described nozzle in described nozzle and described specific replacement for the described nozzle in described nozzle; And

Described method comprises further: the transmitting drive waveforms of replacing for each another one that can be used in the transmitting drive waveforms of the described multiple replacement used together with the nozzle of in described nozzle, parameter described in duplicate measurements, adds up population accordingly to obtain;

Comprise for parameter described in each duplicate measurements in other nozzle: the transmitting drive waveforms of replacing for each another one that can be used in the transmitting drive waveforms of the described multiple replacement used together with each another one nozzle in described nozzle, parameter described in duplicate measurements, to obtain each statistics population; And

For each waveform that can be used in the transmitting drive waveforms of the described multiple replacement used together to each corresponding nozzle in described nozzle, performing process to each statistics population, being associated so that the mean value for described parameter is estimated with the expansion for distributing.

18. methods as claimed in claim 15, wherein, described method comprises further: control to print, to deposit the multiple drops selected from corresponding nozzle in given substrate target area, described in multiple drops of selecting be selected as producing the synthetic ink packing volume for described target area equaling the mean value sum associated to the drop produced by the corresponding each nozzle in described nozzle.

19. methods as claimed in claim 15, wherein, perform described measurement and repetition, and to obtain the threshold value population of the measurement for each nozzle in described nozzle, and wherein, the threshold value population of described measurement represents at least 24 measurements.

20. 1 kinds of ink-jet printers, comprising:

Printhead, has the nozzle of the corresponding drop spraying ink;

Drop measurement device, in order to the light by collecting passed through measurement zone of advancing from the drop of ink, measures the parameter associated to the drop of the ink sprayed by corresponding nozzle;

Wherein, described ink-jet printer comprises service station and the parts for selecting described printhead to move to service station; And

Wherein, described ink-jet printer comprises the parts for moving described measurement zone in each selectively in three dimensions independently further.

21. 1 kinds of ink-jet printers, comprising:

Printhead, has the nozzle of the corresponding drop spraying ink;

Coverage and the printhead connecting gear for selectively described printhead being moved to described service area; And

Drop measurement device, in order to engage described printhead selectively when described printhead is in described coverage, described drop measurement device is in order to the light by collecting passed through measurement zone of advancing from the drop of ink, measure the parameter associated to the drop of the ink sprayed by corresponding nozzle, described drop measurement device comprises travel mechanism further, be operable as in each in three dimensions and link described measurement zone, thus described measurement zone is orientated as adjacent with any one in described nozzle after described printhead has been moved to described coverage.

22. ink-jet printers as claimed in claim 21, wherein, described drop measurement device comprises at least one fluorescence detector and in order at least one in the hardware of measuring the interference figure of light detected by least one fluorescence detector described or software.

23. ink-jet printers as claimed in claim 21, wherein, described drop measurement device comprises at least one imageing sensor and in order to measure at least one in the hardware of shade or software that are detected by least one fluorescence detector described.

24. ink-jet printers as claimed in claim 21, wherein, described printhead is positioned in parking place when being moved to described coverage, wherein, the described nozzle of described printhead is applicable to relative to the drop spraying ink in the distance h of parking place, wherein, described travel mechanism is applicable to selectively at the described measurement zone that substantially moves up with the side of the dimension parallel of described distance h, be in described distance h to make described measurement zone, measure to perform drop, and wherein, described travel mechanism is operable as in each selectively in two parallel with the nozzle load-bearing surface of described printhead and substantially orthogonal with the dimension of described distance h dimensions and moves described measurement zone independently, to measure the drop from corresponding nozzle.

25. ink-jet printers as claimed in claim 24, wherein, described drop measurement device comprises at least one light path routing mechanisms, in order to the measurement light from the drop being advanced through described measurement zone is directed to being away from described nozzle load-bearing surface the fluorescence detector of the distance being positioned at the dimension along distance h being greater than distance h, wherein, described drop measurement device comprises at least one light path routing mechanisms, in order to source light to be directed to the drop being advanced through described measurement zone from light source, described light source is also positioned at the distance of the dimension along distance h being greater than distance h, and wherein, each light path routing mechanisms comprises mirror, one in prism or Connectorized fiber optic cabling.

26. 1 kinds of ink-jet printers, comprising:

Printhead, in order to by ink print in substrate, described printhead has nozzle;

Coverage and the printhead connecting gear in order to selectively described printhead to be sent to described coverage;

Drop measurement device; And

Controlling organization, on a continuous basis ink is printed in described substrate as film in order to cause described printer, and when cause described printhead by ink print to described substrate time day part between, cause described printhead connecting gear that described printhead is sent to described coverage, and cause described drop measurement device to measure corresponding droplet size from each described nozzle.

27. 1 kinds of controls have the method for the ink-jet printer of the printhead with nozzle, comprising:

The drop measurement device of described ink-jet printer is used to build the statistical distribution of the drop parameter for each in described nozzle via the duplicate measurements to the drop produced by each in described nozzle;

At least one statistical measurement associated with the described statistical distribution for each in described nozzle and threshold value are compared;

Depend on comparative result, the drop that checking or refusal are produced by the corresponding each nozzle in described nozzle; And

The print processing of the use to the drop produced by the corresponding each nozzle in unaccepted described nozzle is got rid of in planning.