JP2005014453A - Ink liquid drop controller and ink jet recorder comprising it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recorder ensuring an image having high image quality by realizing an ink liquid drop controller controlling the weight of ink liquid drops being ejected from all nozzles and the landing position thereof on a recording medium accurately. <P>SOLUTION: The ink liquid drop controller comprises a recording head having a plurality of nozzles, and an optical device having a light emitting part and a light receiving part located on the opposite sides of the passage of an ink liquid drop being ejected from the nozzle, and controls the weight or diameter of the ink liquid drop and the landing position thereof on a recording medium by an electric signal transmitted from the light receiving part of the optical device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet recording apparatus that records ink onto a recording medium by ejecting ink droplets from a recording head having a plurality of nozzles, and more particularly to an ink droplet control apparatus that controls the weight of ink droplets and the landing position on the recording medium. The present invention relates to an inkjet recording apparatus including
[0002]
[Prior art]
[Patent Document 1] JP-A-2001-260350
As an ink jet recording apparatus for performing high-speed recording, a multi-nozzle ink jet recording apparatus having one or a plurality of recording heads in which a large number of nozzles are linearly arranged has been conventionally known. This is because a single nozzle has a limit in recording frequency and ink droplet weight to be ejected, so that the number of nozzles is increased to realize high-speed recording.
[0003]
In such a recording apparatus having a large number of nozzles, there is a problem in that the weight and speed of ink droplets discharged from each nozzle, the discharge direction, and the like vary. When recording an image, these variations cause non-uniform image density and degradation of landing position accuracy, as well as streaking in the scanning direction within the uniform density region, image collapse in image details, and jaggedness called jaggy. The image quality is significantly degraded.
[0004]
As one cause of the weight of the ink droplet and the fluctuation of the landing position, there may be an influence due to a manufacturing accuracy defect or dust. Crosstalk (mutual interference between nozzles) also causes ink droplet weight and landing position error. That is, there is a problem that the weight of ink droplets and the landing position change when, for example, all the nozzles are ejected simultaneously and when only one nozzle is ejected. As described above, there are various causes, and the phenomenon is complicated. Therefore, it is not easy to eliminate the error.
[0005]
As a countermeasure against this, Patent Document 1 discloses a technique for individually adjusting the driving method of piezoelectric elements corresponding to individual nozzles and the control of charging deflection of ink droplets for each nozzle.
[0006]
[Problems to be solved by the invention]
However, in the above known technique, it is a big problem to accurately and quickly measure the weight and landing position of the ink droplet.
[0007]
That is, the ink droplet weight is usually about 10 ng to several tens of ng, and about 1 million ejected droplets must be collected to measure the weight with a balance or the like. There is a problem that it takes a long time. In particular, in an inkjet recording apparatus for high-speed recording, it usually takes 100 or more nozzles, so that a long time is required for measurement. In addition, when using ink that is easy to dry, there is also a problem that measurement itself is difficult.
[0008]
An object of the present invention is to provide an ink droplet control apparatus that solves the above-described problems and an ink jet recording apparatus using the ink droplet control apparatus.
[0009]
Specifically, an object of the present invention is to realize an ink droplet control apparatus that can accurately control the weight of ink droplets ejected from all nozzles and the landing position on a recording medium, whereby high-quality images can be obtained. An object of the present invention is to provide an obtained ink jet recording apparatus.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a recording head having a plurality of nozzles, an optical device in which a light emitting unit and a light receiving unit are arranged at positions sandwiching a passage of ink droplets ejected from the nozzles, and the optical device And a control device for controlling the weight or diameter of the ink droplets by an electrical signal from the light receiving unit.
[0011]
Another feature of the present invention is that a recording head having a plurality of nozzles, an optical device in which a light emitting portion and a light receiving portion are arranged at positions sandwiching a passage of ink droplets ejected from the nozzles, and a light receiving portion of the optical device. And a control device for controlling the landing position of the ink droplet by the electrical signal.
[0012]
Another feature of the present invention resides in that the electric signal of the light receiving unit when a plurality of ink droplets are ejected is integrated, and the weight or landing position of the ink droplets is controlled by the integrated value.
[0013]
Another feature of the present invention is that the weight or landing position of the ink droplet is controlled in accordance with a signal in which the electrical signal from the light receiving unit exceeds a predetermined threshold value.
[0014]
Another feature of the present invention is that the control device calculates a weight of the ink droplet based on an electric signal from the light receiving unit, a means for comparing the calculated weight value with a target value, and a comparison result. And a means for increasing / decreasing the weight of the droplet ejected from the nozzle, and controlling the weight of the ink droplet to converge within a predetermined range.
[0015]
Another feature of the present invention is that the control device calculates a landing position of the ink droplet based on an electric signal from the light receiving unit, a means for comparing the calculated value with a target value, and a comparison result. And a means for controlling the landing position of the liquid droplets discharged from the nozzle, and the landing position is controlled to converge within a predetermined range.
[0016]
Another feature of the present invention is that a recording head having a plurality of nozzles, an optical device having a light emitting unit that generates parallel light and a light receiving unit that receives the parallel light, and ink droplets ejected from the nozzle are parallel to each other. Means for moving the recording head to a position where light passes, and a control device for controlling at least one of the weight of the ink droplet and the landing position of the ink droplet by an electric signal from the light receiving portion of the optical device. There is.
[0017]
Another feature of the present invention is that the recording head includes means for rotating the recording head to a first position that forms a predetermined angle with the parallel light and to a second position that forms an angle different from the angle. .
[0018]
Another feature of the present invention resides in that the weight or diameter of the ink droplet is controlled by an electric signal from the light receiving portion when the recording head is at the first position.
[0019]
Another feature of the present invention is based on an electrical signal from the light receiving unit when the recording head is in the first position and an electrical signal from the light receiving unit when the recording head is in the second position. The purpose is to control at least one of the weight of the ink droplet and the landing position of the ink droplet.
[0020]
Another feature of the present invention is that a recording head having a plurality of nozzles, an optical device having a light emitting unit that generates parallel light and a light receiving unit that receives the parallel light, and ink droplets ejected from the nozzle are the parallel light. A control device that controls at least one of the weight of the ink droplet and the landing position of the ink droplet from the signal of the light receiving portion when passing through the nozzle, and the control device has a plurality of ejection patterns of the ink droplet ejected from the nozzle And a memory for storing the weight of the ink droplet and the correction value of the landing position corresponding to each pattern, and the control is performed using the correction value corresponding to the ejection pattern.
Other features and advantages of the present invention will be more clearly understood from the following description.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
First, an ink jet nozzle used in an on-demand ink jet recording apparatus according to the present invention will be described with reference to FIGS.
[0022]
FIG. 3 shows an example of a nozzle structure. 301 is an orifice (nozzle hole), 302 is a pressurizing chamber, 303 is a vibration plate, 304 is a piezoelectric element, 305 is a signal input terminal, 306 is a piezoelectric element fixing substrate, and 307 is The common ink supply path 308 and the pressurizing chamber 302 are connected by a restrictor, and the ink flow rate to the pressurizing chamber 302 is controlled. 309 is an elastic material (for example, silicon adhesive) that connects the diaphragm 303 and the piezoelectric element 304, 310 is a restrictor plate that forms the restrictor 307, 311 is a pressurizing chamber plate that forms the pressurizing chamber 302, Reference numeral 312 denotes an orifice plate for forming an orifice (nozzle hole) 301, and reference numeral 313 denotes a support plate for reinforcing the diaphragm. The diaphragm 303, the restrictor plate 310, the pressurizing chamber plate 311, and the support plate 313 are made of, for example, stainless steel, and the orifice plate 312 is made of nickel. The piezoelectric element fixing substrate 306 is made of an insulator such as ceramics or polyimide.
[0023]
In the ink jet nozzle configured as described above, the ink flows in the order of the common ink supply path 308, the restrictor 307, the pressurizing chamber 302, and the orifice 301 from the upper side to the lower side of the paper surface. The piezoelectric element 304 is attached such that it expands and contracts when a voltage is applied to the signal input terminal 305 and does not deform when no voltage is applied. An analog drive signal, which will be described later, is connected to the signal input terminal 305, a voltage is applied according to the discharge timing, and a part of the ink in the pressurizing chamber 302 is discharged from the orifice 301 (nozzle hole).
[0024]
FIG. 4 is a schematic configuration diagram of a recording head apparatus in which 128 ink jet nozzles are arranged in a straight line. Reference numeral 401 denotes a recording head, in which 128 nozzle holes 301 are arranged in a straight line. The pitch of the nozzle holes 301 is 75 nozzles / inch in this example.
[0025]
A piezoelectric element driver 402 is connected to the recording head 401. The configuration of the piezoelectric element driver 402 itself is known and includes an analog switch 403, a latch 404, and a shift register 405.
[0026]
The shift register 405 receives the digital ejection signal 407 and the shift clock S-CLK. The digital ejection signal 407 is 128-bit serial data corresponding to the 128 nozzle holes 301, respectively. Here, it is defined as ejection when logic 1 and non-ejection when logic 0.
[0027]
The latch 404 receives the 128-bit parallel data and the latch clock L-CLK from the shift register 405. The output from the latch 404 is input to the switch terminals of the 128 analog switches 403, and the analog drive signal 406 is input to the input terminals of the analog switches 403.
[0028]
The analog switch 403 outputs the analog drive signal 406 of the input terminal as it is to the output terminal when the logic 1 is applied to the switch terminal, and opens the output terminal when the logic 0 is applied. The output terminal of the analog switch 403 is output to one side of the signal input terminal 305 of each nozzle 301. The other side of the signal input terminal 305 is grounded.
[0029]
That is, the analog drive signal 406 is a drive signal applied in common to 128 piezoelectric elements 304 for ejecting ink from the nozzles in the recording head 401. For example, a trapezoidal waveform voltage of 24V is used. Various other driving waveforms are also known.
[0030]
FIG. 2 is a timing chart of signals applied to the piezoelectric element driver 402. The digital discharge signal 407 is sequentially stored in the shift register 405 periodically with the shift clock S-CLK, and when 128 pieces are prepared, this time, the digital discharge signal 407 is stored in the latch 404 all together with the latch clock L-CLK. Is output.
[0031]
The latch clock L-CLK is generated in synchronization with the position of the recording medium. The analog drive signal 406 is input while the digital ejection signal 407 is held. As a result, the digital ejection signal 407 is ejected from the logic 1 nozzle and is not ejected from the logic 0 nozzle.
[0032]
Next, an embodiment of the ink jet recording apparatus of the present invention equipped with the recording head 401 will be described with reference to FIGS.
[0033]
As shown in FIG. 5, the recording head 401 is mounted downward on a stage that can move in the xyz direction via a θ rotation shaft 503. 502 is an x direction moving stage, 505 is a y direction moving stage, 506 is a z direction moving stage, and 504 is a recording medium. The height of the recording head 401 is controlled by the z-direction moving stage 506, and the inclination θ in the xy plane is controlled by the rotating shaft 503.
[0034]
The present invention is characterized in that it includes an ink droplet control device as will be described later, but a droplet measuring unit 507 for performing the control is formed on the x-direction moving stage 502.
[0035]
FIG. 6 is an explanatory diagram of the θ rotation shaft 503, and is a view of the recording head 401 of FIG. 5 as viewed from above. With respect to the x and y coordinate systems of the stage, the angle θ is defined by the stage y-axis direction and the nozzle row direction 509 of the recording head 401 as shown in the figure. During recording, the recording medium 504 fixed to the x-direction moving stage 502 performs main scanning, and the recording head 401 fixed to the y-direction moving stage 505 performs sub-scanning. The inclination θ of the recording head 401 at the time of recording may be 0 degree, or may be inclined to an angle that is the purpose of matching the resolution.
[0036]
Next, an embodiment of the ink droplet control apparatus according to the present invention will be described with reference to FIG. As shown in the figure, the ink droplet control device is roughly divided into a measurement unit 507 and a control unit 508, and the inkjet recording unit 501 is controlled by the output of the control unit 508. The measuring unit 507 is a device that optically detects a droplet, and includes a light emitting optical system 507a and a light receiving optical system 507b. Diffused light from a light source 601 such as an LED becomes a plane parallel light 603 through a collimator lens 602, and forms an image on a CCD linear sensor 605 through a telecentric optical system 604. As shown in the drawing, when the liquid droplet 606 as the measurement object crosses the plane parallel light 603, the CCD linear sensor 605 corresponding to that portion is not exposed for that time. The configuration of the sensor unit 507 itself is publicly known, and the specifications of the CCD linear sensor 605 of the apparatus used in this embodiment are a repeatability accuracy of ± 0.06 μm and a minimum exposure time of 400 μsec. However, the accuracy is improved only when the measurement object 606 is brought near the center of the lenses 602 and 604.
[0037]
The control unit 508 includes a central processing unit (hereinafter abbreviated as CPU) 508A, a read-only memory (hereinafter abbreviated as ROM) 508B, and a random access memory (hereinafter abbreviated as RAM), and the ROM 508B controls according to the flowchart of FIG. A program is stored for this purpose.
[0038]
Next, the ink droplet control method will be described with reference to the flowchart of FIG. This method is performed at any time immediately before starting the recording or coating operation, or at an appropriate time during the operation, and is not a recording flow. The overall configuration and operation of the printer system at the time of recording are the same as described in Patent Document 1.
[0039]
First, the inclination θp of the recording head 401 during recording scanning is defined. As described above, this inclination is determined by the coating conditions (scanning line density). Further, the allowable error ranges Sdlim and Svdlim of the ink droplet weight and the landing position are determined. The method for determining the allowable error range is known in the art.
[0040]
When measurement is started, the recording head 401 is moved to the position shown in FIG. 8 by the xyz stage in step 101.
[0041]
That is, the recording head 401 is moved to a position between the light emitting unit 507 a and the light receiving unit 507 b of the measuring device 507 so that the droplet 701 passes the parallel light 701. Hereinafter, an xyz coordinate system fixed to the recording head 401 as shown in FIG. The central part of the parallel light 603 is arranged at a position 1 to 1.5 mm away from the nozzle to be measured in the downward direction, that is, in the z direction. This distance is equal to the distance between the recording medium and the recording head 401 when recording after measurement. After the arrangement, the recording head 401 is rotated using the θ rotation shaft 503.
[0042]
FIG. 9 shows the position of the recording head 401 after rotation. The figure is a view from above. For measurement, the recording head 401 is rotated in the positive direction by θm with respect to the x-axis. This is called the first position, and the rotated x-axis at that time is defined as the x1-axis. The rotation angle θm is preferably 45 degrees, but of course the present invention is not limited to this.
[0043]
Next, returning to FIG. 1, the ink droplet 701 ejected and tested in step 102 passes through the parallel light 603 and is then adsorbed by an ink adsorbent (not shown). In step 103, the recording head 401 for one nozzle is moved in the nozzle row direction. In the case of the first measurement, when the recording head 401 is moved to the position of FIG. One nozzle is set as a measurement target. In step 104, a weight correction routine is executed.
[0044]
Prior to the description of the weight correction routine, how the ink droplet 701 is measured by the measuring device 507 will be described with reference to the principle diagram of FIG.
[0045]
The horizontal axis in the figure indicates the position in the x direction on the CCD linear sensor 605. It indicates the position in the x direction of the ink droplet 701 shown in FIG. 8, and its value is s1 here. The horizontal axis indicates the exposure amount accumulated in each element of the CCD linear sensor 605. The exposure time is variable at a minimum of 400 μs.
[0046]
If there is nothing to block the parallel light 603 during exposure, the exposure amount is assumed to be 100%. However, for example, if the ink droplet 701 having an elliptical cross section as shown in FIG. 12 is interrupted, the exposure amount is reduced from the 100% exposure amount by an amount proportional to half of the ellipse. The exposure amount decrease ΔE of one droplet is proportional to the speed of the ink droplet 701 but is quite small. Therefore, when about 10 shots are measured in synchronization with the ejection timing of the ink droplet, the result is integrated and the SN ratio is also increased. Get higher. Thereafter, as shown in FIG. 12, for example, the threshold Eth is set at a position where the exposure amount is about 95%, and the left edge S11 and the right edge S12 are obtained. From this, the ink droplet diameter Sd1 and the ink droplet position Sc1 are calculated by the following equations.
Sd1 = S12-S11 (1)
Sc1 = (S12 + S11) / 2 (2)
Such arithmetic processing is performed by the CPU 508A of the control unit 508 based on the detection signal from the CCD linear sensor 605 of the measurement unit 507.
[0047]
In the above measurement method, the exposure amount reduction ΔE depends on the speed of the ink droplet, but is binarized with the threshold value Eth set at an appropriate exposure amount position, and therefore the measured values Sd1 and Sc1 include There is a feature that the influence of speed does not appear. Even when the shape of the ink droplet 701 is divided into other shapes or small droplets called satellite droplets and two droplets, the measurement is performed at the outermost edges S11 and S12 that have a large influence on the weight. There is a feature with less error for measurement. Actually, coupled with the effect of the integration, the repeatability of the measured values Sd1 and Sc1 can be obtained at about several μm.
[0048]
The relationship between the actual ink droplet weight m and the measured ink droplet diameter Sd1 is previously measured with a representative nozzle for each head using a conventional balance method to create a table. The ink droplet weight is controlled by adjusting a piezoelectric element driving voltage waveform, which will be described later, but the ink droplet velocity and shape change depending on this waveform adjusting method, so that the ink droplet weight m and the ink droplet diameter Sd1 The relationship will also change. Therefore, after determining the waveform adjustment method, data in the vicinity of the set value is collected. Since this characteristic is generally constant within the same head, it is desirable to keep it for each head. At this time, the weight target value Sdr corresponding to the weight setting value and the weight error range Sdlim corresponding to the allowable weight error are obtained as the value of the ink droplet diameter Sd1.
[0049]
Next, returning to FIG. 1, the weight correction routine shown in step 104 will be described. FIG. 10 shows an example of this weight correction routine. First, in step 901, the ink droplet diameter Sd1 and the ink droplet position Sc1 are obtained according to the principle described above.
[0050]
Further, at step 902, the control deviation Sdd is obtained by taking the difference between a predetermined droplet diameter reference value Sdr and the measured droplet diameter Sd1. In step 903, the magnitude (absolute value) of the control deviation Sdd is compared with the weight error allowable range Sdlim. If | Sdd | <Sdlim is YES, the process proceeds to step 907. If NO, the process proceeds to step 904. .
[0051]
In step 904, whether the control deviation Sdd is positive or negative is determined. If the control deviation Sdd is positive, the process proceeds to step 906, and if negative, the process proceeds to step 905. When Sdd is negative, it indicates that the measured droplet diameter Sd1 is larger than the reference value Sdr. Therefore, in step 905, the predetermined value d is subtracted from the control value Driv for changing the ink droplet weight. Control by the subtracted value. Here, as a method of changing the weight of the ink droplet, a method of changing the magnitude of the driving voltage of the piezoelectric element or changing the pulse width is known. There is also a method disclosed in Patent Document 1.
[0052]
In step 906, on the contrary, a predetermined value d is added to the control value Driv for changing the ink droplet weight, and control is performed by the added value.
[0053]
As a result of such control, the ink droplet weight, that is, the droplet diameter changes, and the process returns to step 901 to repeat the same measurement. By repeating the above loop, when the measured droplet diameter Sd1 enters the weight error allowable range Sdlim, the process proceeds from step 903 to step 907, and the last measured ink droplet position Sc1 is stored in the RAM 508C of the control unit 508. The This value Sc1 is used in the landing position correction described later. Although not shown in the figure, error processing is performed if convergence does not occur even if the measurement of Sd1 and Sc1 is repeated a specified number of times.
[0054]
Thus, the ink droplet diameter Sd1 ejected from the nozzle to be measured becomes a value near the target value Sdr, and as a result, the ink droplet weight is also set to a value near the target value. Since this measurement time is about 400 μs per time, it usually takes only a few milliseconds to exit the routine, and the correction time is shortened to the extent that comparison with conventional balance measurement is not possible.
[0055]
Returning to the description of FIG. 1 again, when the above-described weight correction is performed in step 104, it is next determined in step 105 whether or not the weight correction has been completed for all the nozzles.
When the weight correction for all the nozzles is not completed, the process returns to step 103 to move the recording head 401 to set the adjacent nozzle as the measurement target. When the weight correction of all the nozzles of the recording head 401 is completed, the process proceeds to step 106, and the ejection of droplets from the nozzles is stopped. At this time, the droplet position Sc1 from each nozzle is stored in the RAM 508C of the control unit 508.
[0056]
In step 107, the recording head 401 is moved to the position indicated by x2 in FIG. This position is a position obtained by rotating the recording head 401 in the negative direction by θm with respect to the x axis, and is referred to as a second position here. The rotated x-axis is taken as x2 axis as shown. In general, since the measurement unit 507 has a y-axis target structure, the rotation angle in the negative direction is the same as the rotation angle θm in the positive direction, but the positive and negative rotation angles need not be equal.
[0057]
In step 108, the ejection of ink droplets from the nozzles is started again, and after moving by one nozzle in step 109, the landing position correction routine in step 110 is executed.
[0058]
FIG. 11 is a flowchart of the landing position correction routine. First, in step 1001, the ink droplet position Sc1 stored in the RAM 508C is read. In step 1002, the ink droplet position Sc2 is newly measured. In step 1003, the x and y coordinates (x0, y0) of the ink droplet landing position are calculated from these two values as follows.
x0 = (Sc1 + Sc2) / (2cos θm) (3)
y0 = (Sc1 + Sc2) / (2sin θm) (4)
In this embodiment, the droplet position Sc1 when the angle θ of the recording head 401 is set to θm and the droplet position Sc2 when −θm are set are measured, and the ink droplet landing position is determined from these two values Sc1 and Sc2. One feature is that the coordinates (x0, y0) are obtained to obtain a two-dimensional landing position on the recording medium.
[0059]
After calculating (x0, y0) as described above in step 1003, the landing position correction process is started. Before explaining this process, the landing position correction method will be described with reference to FIG.
[0060]
The x-axis and y-axis in FIG. 13 are the same as the x- and y-axes in FIG. 9, and the nozzle surface is viewed from below with the origin of the nozzle to be measured being O.
[0061]
If the landing position of the ink droplet obtained as a result of the measurement is P0 (x0, y0), it is necessary to correct the landing position of the ink droplet from P0 to O by correcting the landing position. In general, there are several methods for correcting the landing position of ink droplets. In this embodiment, the landing position is corrected by the charge deflection electric field method disclosed in Patent Document 1. According to this method, the direction that can be corrected is the direction orthogonal to the row direction in which the nozzles are arranged, that is, the y-axis direction in FIG. That is, as shown in the figure, the point P0 can be corrected parallel to the y-axis, but cannot be corrected in other directions. Therefore, the point P0 cannot be simply corrected to the origin O.
[0062]
Therefore, in this embodiment, the angle between the paper conveyance direction and the x axis is α, a straight line L with an inclination α passing through the origin O is drawn and corrected so as to land on the straight line L. If this is the point Q, the distance spd from the origin O is expressed by the following equation.
spd = x0 / cos α (5)
As disclosed in Patent Document 1, since the landing position correction on the straight line L can generally be dealt with by adjusting the discharge time, this value spd is stored in the discharge time memory area of the RAM 508C in the control unit 508 in step 1004. To do. If the landing position can be moved to the point Q by using this value spd in the above-mentioned charge deflection electric field method at the time of recording, the landing position can be moved to the origin O by correcting the distance spd on the straight line L by the conventional discharge time adjustment. it can.
[0063]
Next, a method for specifically correcting the point P0 to the point Q by the charge deflection electric field method will be described. When a perpendicular foot from the point P0 to the straight line L is set as a point Q0, a distance svd between P0 and Q0 is expressed by the following equation (6).
svd = y0 cos α−x0 sin α (6)
In step 1005 of the same 11, the magnitude (absolute value) of the value svd is compared with the landing position allowable error range Svdlim, and if it is not within the allowable range, the process proceeds to step 1006.
[0064]
In step 1006, whether the control deviation svd is positive or negative is determined. If positive, the process proceeds to step 1008, and if negative, the process proceeds to step 1007. In step 1007, the predetermined value C is subtracted from the control value Dev value for controlling the ink droplet landing position, and the charge deflection electric field of the ink jet recording unit 501 is controlled according to the subtracted value. A method of controlling the ink droplet landing position based on the control value Dev is disclosed in Patent Document 1.
[0065]
Similarly, in step 1008, the predetermined value C is added to the control value Dev for controlling the ink droplet landing position, and the charge deflection electric field is controlled according to the added value.
Since the ink droplet landing position immediately changes when the Dev value is changed, the ink droplet position Sc2 is immediately measured again in step 1009, and a new svd is calculated in step 1010.
[0066]
In this case, as shown in FIG. 13, the landing position point P0 moves to the point P. At this time, since x0 does not change due to the definition of the charge deflection direction, a new svd is obtained from only the measured value Sc2 as follows. .
svd = (x0 cos (θm + α) −
Sc2 cos α) / sin θ (7)
In this way, the new landing position P after correction only needs to be measured from the second direction, so that the correction operation can be repeated continuously after entering Step 1005. This enables high-speed measurement and correction.
[0067]
After repeating the above loop several times, the process exits from the step 1005 to the lower path and ends the landing position correction routine. Although not shown in the figure, if the convergence does not occur after the prescribed number of times, error processing is performed.
[0068]
As a result, the ink droplet landing position of the measurement target nozzle is set in the vicinity of the target point Q. Therefore, the landing position can be moved to the origin O by correcting the distance spd on the straight line L by adjusting the discharge time during recording. As described above, since the measurement time is about 400 μs per time, it usually takes only a few ms to get out of the landing position correction routine. That is, according to the present invention, the correction time can be greatly shortened and the recording medium is not wasted compared to the conventional method of recording a test pattern on a recording sheet, reading it, and correcting it.
[0069]
Although the deflection method in this embodiment uses an electric field, other deflection methods using a magnetic field, gravity, airflow, etc. are known, and these deflection methods can also be used. For example, in this embodiment, if a magnetic pole is attached instead of the electrode, the deflection direction by the Lorentz force becomes the nozzle row direction, and the correction direction can be changed.
[0070]
Returning to FIG. 1 again, when the landing position correction is completed in step 110, the routine proceeds to step 111, where it is determined whether or not the landing position correction has been completed for all nozzles. When correction has been performed for all the nozzles, the process proceeds to step 112, and the ejection of droplets from the nozzles is stopped. Further, in step 113, the head is moved to a predetermined position, and all the processes are completed.
[0071]
In the above description, when ink droplets are ejected from the nozzles in steps 102 and 108, it is desirable that the ejection pattern for the test ejection is a pattern actually used for recording. When recording in various patterns, a test discharge is performed using a representative pattern. However, in the case of patterning a display, there are many cases where the number of ejection patterns to be applied is limited to several types. Therefore, in such a case, measurement is performed by performing test ejection with all or almost all patterns to be ejected, and storing the Drive value, Dev value, and spd value in a memory and actually recording them. Can be controlled using these values Driv, Dev and spd.
[0072]
FIG. 14 shows a configuration example of a control device for performing such control. In the figure, reference numeral 1301 denotes an ejection information device, 1303 denotes an ejection control device, and 501 denotes an ink jet recording unit.
[0073]
The above-described ejection pattern data is stored in advance in a memory in the ejection information device 1301. When recording is actually performed, the ejection pattern data 1302 and the corresponding Drive value, Dev value, and spd value for each nozzle are output to the recording control device 1303. The recording control device 1303 changes the piezoelectric element driving voltage waveform 406, the ejection timing 407, and the deflection voltage 1304 in accordance with those values as disclosed in Patent Document 1, whereby the inkjet recording device 501 uses the target ink liquid. Obtain drop weight and landing position. When the ejection pattern is changed, that is, when the ejection pattern data 1302 is changed, at the same time, the Drive value, Dev value, and spd value for each corresponding nozzle are output to the recording control device 1303. It is possible to always obtain a desired ink droplet weight and landing position according to the ejection pattern data 1302.
[0074]
Therefore, according to the present embodiment, ink droplets are ejected under conditions corresponding to all or most ejection timings actually recorded, so that the influence of the crosstalk can be corrected.
[0075]
【The invention's effect】
As described above, according to the present invention, there is provided a recording head having a plurality of nozzles, and an optical device in which a light emitting unit and a light receiving unit are arranged at positions sandwiching a passage of ink droplets ejected from the nozzles. Since the weight or diameter of the ink droplet and the landing position of the ink droplet on the recording medium are controlled by the electrical signal from the light receiving unit of the optical device, the weight and landing of the ink droplet discharged from all the nozzles It is possible to realize an ink droplet control apparatus that can accurately control the position, thereby providing an ink jet recording apparatus that can obtain a high-quality image.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a droplet control method of an ink droplet control apparatus according to the present invention.
FIG. 2 is a timing chart of a piezoelectric element driver in the ink jet recording apparatus according to the present invention.
FIG. 3 is a cross-sectional view showing an embodiment of a nozzle structure in the recording apparatus of the present invention.
FIG. 4 is a schematic configuration diagram showing an embodiment of a recording head in the recording apparatus of the present invention.
FIG. 5 is a configuration diagram showing an embodiment of a recording head in the recording apparatus of the present invention.
FIG. 6 is an explanatory diagram of the operation of the recording head.
FIG. 7 is a schematic diagram showing an embodiment of a droplet measurement unit in the ink droplet control apparatus according to the present invention.
FIG. 8 is a schematic diagram showing a relationship between a recording head and a droplet measuring unit.
FIG. 9 is a schematic diagram for explaining a rotation direction of a recording head.
FIG. 10 is a flowchart of a weight correction routine in the ink droplet control method.
FIG. 11 is a flowchart of a landing position correction routine in the ink droplet control method.
FIG. 12 is a diagram illustrating the principle of a droplet measuring method according to the present invention.
FIG. 13 is an explanatory diagram of a landing position correction method according to the present invention.
FIG. 14 is a block diagram showing a configuration of a control unit in the ink jet recording apparatus according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 301 ... Orifice (nozzle hole), 302 ... Pressurizing chamber, 303 ... Diaphragm, 304 ... Piezoelectric element, 305 ... Signal input terminal, 306 ... Piezoelectric element fixed substrate, 307 ... Restrictor, 309 ... Elastic material, 310 ... List Rector plate, 311 ... Pressure chamber plate, 312 ... Orifice plate, 313 ... Support plate, 401 ... Recording head, 402 ... Piezoelectric element driver, 403 ... Analog switch, 404 ... Latch, 405 ... Shift register, 406 ... Analog drive Signal: 407: Digital ejection signal, 501: Inkjet recording device, 502: x-direction moving stage, 503 ... θ rotation axis, 504 ... recording medium, 505 ... y-direction moving stage, 506 ... z-direction moving stage, 507 ... measuring device 508: Control unit, 508A ... CPU, 508B ... ROM, 508C ... RA 601 ... light source such as LED, 602 ... collimator lens, 603 ... plane parallel light, 604 ... telecentric optical system, 605 ... CCD linear sensor, 606 ... measuring object, 701 ... ink droplet, 1301 ... ejection information device, 1302 ... Discharge pattern data, 1303 ... recording control device, 1304 ... deflection voltage, 1305 ... CCD linear sensor,

Claims (11)

A recording head having a plurality of nozzles, an optical device in which a light emitting portion and a light receiving portion are arranged at a position sandwiching a passage of ink droplets ejected from the nozzles, and an ink droplet generated by an electric signal from the light receiving portion of the optical device. An ink droplet control device, comprising: a control device that controls weight or diameter; and an ink jet recording device including the ink droplet control device. A recording head having a plurality of nozzles, an optical device in which a light emitting portion and a light receiving portion are arranged at a position sandwiching a passage of ink droplets ejected from the nozzles, and an ink droplet generated by an electric signal from the light receiving portion of the optical device. An ink droplet control device comprising: a control device that controls a landing position; and an ink jet recording device including the ink droplet control device. 3. The ink liquid according to claim 1, wherein the electric signal of the light receiving unit when a plurality of ink droplets are ejected is integrated, and the weight or landing position of the ink droplet is controlled by the integrated value. Drop control device and ink jet recording apparatus provided with the same. 3. An ink droplet control apparatus according to claim 1, wherein the weight or landing position of the ink droplet is controlled in accordance with a signal in which an electrical signal from the light receiving unit exceeds a predetermined threshold value. An inkjet recording apparatus provided. 2. The control apparatus according to claim 1, wherein the control device calculates a weight of the ink droplet based on an electric signal from the light receiving unit, a means for comparing the calculated weight value with a target value, and the nozzle based on the comparison result. An ink droplet control apparatus, and means for controlling the weight of the ink droplets so as to converge within a predetermined range. . 3. The control device according to claim 2, wherein the control device calculates a landing position of the ink droplet based on an electric signal from the light receiving unit, a means for comparing the calculated value with a target value, and the nozzle based on the comparison result. An ink droplet control apparatus, and an ink jet recording apparatus including the ink droplet control apparatus. The ink droplet control apparatus includes: a control unit configured to control a landing position of a discharged droplet; An optical apparatus having a recording head having a plurality of nozzles, a light emitting unit for generating parallel light and a light receiving unit for receiving the parallel light, and the recording at a position where ink droplets ejected from the nozzle pass the parallel light. An ink droplet comprising: means for moving the head; and a control device for controlling at least one of the weight of the ink droplet and the landing position of the ink droplet by an electric signal from the light receiving unit of the optical device. Control device and ink jet recording apparatus provided with the same. 8. The ink liquid according to claim 7, further comprising means for rotating the recording head to a first position that forms a predetermined angle with the parallel light and a second position that forms an angle different from the first angle. Drop control device and ink jet recording apparatus provided with the same. 9. An ink droplet control apparatus according to claim 8, wherein the weight or diameter of the ink droplet is controlled by an electric signal from the light receiving portion when the recording head is at the first position, and an ink jet equipped with the ink droplet control device. Recording device. 9. An ink droplet according to claim 8, wherein an electric signal from the light receiving portion when the recording head is in the first position and an electric signal from the light receiving portion when the recording head is in the second position. An ink droplet control device that controls at least one of the weight of the ink and the landing position of the ink droplet, and an ink jet recording apparatus including the ink droplet control device. An optical device having a recording head having a plurality of nozzles, a light emitting unit that generates parallel light and a light receiving unit that receives the parallel light, and a light receiving unit when ink droplets ejected from the nozzle pass the parallel light. A control device that controls at least one of the weight of the ink droplet and the landing position of the ink droplet from the signal, the control device including a plurality of ejection patterns of the ink droplets ejected from the nozzle, and ink corresponding to each pattern; An ink droplet control apparatus having a memory for storing a weight of a droplet and a correction value of a landing position, and controlling using the correction value according to the ejection pattern, and an ink jet recording apparatus including the ink droplet control apparatus .

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