JP2008260220A - Inkjet recording apparatus, and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an increase in the discharging amount resulting from the temperature rising of a recording head by an ink discharge which occurs when a high-speed recording is performed, to reduce unevenness in the concentration in the same direction with the main scanning direction of a recording region resulting from the increase in the discharging amount, and to reduce the deterioration of the picture quality. <P>SOLUTION: This inkjet recording method or this recording apparatus is equipped with a counting means or process, a holding means or process, and a changing means or process. In this case, in the counting means or process, the scanning region of the recording head 101 is divided into a plurality of counting areas and a recording area in the scanning direction, and a recording dot quantity in the counting area is counted. In the holding means or process, the counted dot quantity is held. In the changing means or process, image data in a next recording area is changed in response to the counted dot quantity. Then, an image is formed by changing the image data in the main scanning direction. The image data is one for which the unit of the image expressing a tone is constituted of a cluster type area tone. The inkjet recording method or inkjet recording apparatus is equipped with a means or process which changes the image data with priority from the (outer peripheral section) region with the clusters concentrated when the image data are changed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus and an ink jet recording method, and more particularly, to an ink jet printing method and apparatus for performing reciprocal printing on a print object such as a printing paper by reciprocating an ink jet head. More specifically, the present invention relates to an ink jet recording apparatus and an image data correction method that can reduce density unevenness that occurs in the scanning direction of a recording area.

  Recording devices used as printing means for images, etc. in printers, copiers, facsimiles, etc., or recording devices used as print output devices, such as composite electronic devices and workstations, including computers and word processors, have image information (character information, etc.). (Including all output information), an image or the like is recorded on a recording material (hereinafter also referred to as a recording medium) such as paper or a plastic thin plate.

  Such a recording apparatus can be classified into an inkjet method, a wire dot method, a thermal method, a laser beam method, and the like depending on the recording method. Among these, an ink jet recording apparatus (hereinafter referred to as an ink jet recording apparatus) performs recording by ejecting ink from a recording means including a recording head onto a recording material, which is higher than other recording systems. It has various advantages such as easy definition, high speed, excellent quietness, and low cost. On the other hand, in recent years, the importance of color output such as color images has increased, and many high-quality color ink jet recording apparatuses comparable to silver salt photography have been developed.

  In such an ink jet recording apparatus, in order to improve the recording speed, a recording head in which a plurality of recording elements are integrated and arranged uses a plurality of ink discharge ports and a plurality of liquid passages, and moreover, a plurality of color correspondences are provided. The one provided with the above recording head is generally used.

  Various types of printer recording methods are known, but the inkjet method has recently been used for reasons such as non-contact recording on recording media such as paper, easy colorization, and quietness. It has attracted particular attention, and as its configuration, a serial head that performs recording while mounting a recording head that ejects ink according to desired recording information and reciprocating scanning in a direction perpendicular to the feeding direction of a recording medium such as paper In general, the recording method is widely used because it is inexpensive and easy to downsize.

  Recently, the performance of such an ink jet printer has been remarkably improved, and a recording speed as high as that of a laser beam printer has been realized. In addition, with the increase in the processing speed of personal computers and the widespread use of the Internet, the desire for higher recording speeds for color images is also increasing.

  Among the inkjet methods, the bubble jet (registered trademark) recording method (BJ method) is a method in which ink is rapidly heated and vaporized by a heating element, and ink droplets are ejected from an orifice by the pressure of the generated bubbles. Bubbles generated in a bubble jet (registered trademark) type recording head having such a structure are cooled by the surrounding ink, and the vapor of the ink in the bubbles is condensed and returned to the liquid. On the other hand, ink consumed by ejection is filled (refilled) from an ink tank that stores ink through an ink supply path.

  FIG. 1 is a diagram illustrating an arrangement example of nozzles of such an ink jet recording head 101, and has a plurality of nozzle rows 102 so that different inks can be ejected. In each nozzle row 102, an even number of ejection rows are arranged on the left side of the ink supply path 105, and an odd number of ejection rows are arranged on the right side. Ink is supplied from an ink supply path 105 through an ink flow path 104 provided corresponding to each nozzle 103.

  FIG. 2 shows the configuration of the main part of the apparatus for performing recording (hereinafter also simply referred to as recording) on the paper surface using the recording head. In the figure, reference numeral 201 denotes an ink jet cartridge (recording means). These are composed of ink tanks each storing four color inks, that is, black, cyan, magenta and yellow inks, and recording heads 202 corresponding to the respective inks.

  Reference numeral 203 denotes a paper feed roller (sub-scanning means) that rotates in the direction of the arrow while sandwiching the recording paper P together with the auxiliary roller 204, and intermittently conveys the recording paper P in the Y direction. Reference numeral 205 denotes a pair of paper feed rollers that feed recording paper. The pair of rollers 205 rotates while pinching the recording paper P, similarly to the rollers 203 and 204, but generates a tension on the recording paper by making its rotational speed lower than that of the paper feed roller 203, and does not bend. Is possible.

  Reference numeral 206 denotes a carriage (main scanning means) that supports the four inkjet cartridges 201 and reciprocates (hereinafter also referred to as scanning or scanning) in the main scanning direction orthogonal to the Y direction. The carriage 206 waits at the home position h at the position indicated by the broken line in the drawing when the recording operation by the recording head is not performed or when the recovery process of the recording head 202 is performed.

  When the carriage 206 at the home position h before the start of recording is instructed to start recording, the carriage 206 scans in the X direction, while N (N is an arbitrary integer) nozzles of the recording head 202. / Records with a width of 1200 inches. When the recording up to the end of the sheet is completed, the carriage returns to the original home position h and scans again for recording in the X direction. Before the second recording starts after the end of the first recording, the paper feeding roller 203 rotates in the direction of the arrow to feed the paper in the Y direction by a width of N / 1200 inches.

  In this way, for each scan of the carriage 206, recording of a width of N / 1200 inches by the recording head 202 and paper feeding are repeatedly performed, for example, recording for one page can be completed. Such a recording mode is referred to as a one-pass recording mode.

  Another recording mode used in the ink jet recording apparatus is a multipass recording mode. This multi-pass recording mode is a recording mode in which recording is completed by performing overprinting in a plurality of times on the same recording area, and generally the image quality improves as the number of passes increases. Are known.

  Here, the case of unidirectional recording in which the recording operation is performed only during the forward movement of the carriage is shown. However, when performing higher speed recording, both the recording operation is performed in both the forward movement and the backward movement of the carriage. It is common to use direction recording.

  In the first place, when an image is formed using the ink jet recording method, it is known that when the same drive pulse is continuously applied to the heating element, density unevenness occurs due to the temperature rise of the head due to the continuous heating of the heater. This density unevenness will be described in detail later.

  For this reason, it is important to reduce this density unevenness in order to perform high-quality recording in the ink jet recording system. As this reduction means, a means for uniformly controlling the discharge amount or a means for correcting the recording data has been proposed. In addition, although there is an adverse effect of using the above-described multi-pass printing or a reduction in printing speed, a reduction in scanning speed is a known technique as means for reducing density unevenness.

  The ejection amount of the recording head depends on the temperature of the ink in the vicinity of the heating element when the same drive pulse is applied to the heating element. Therefore, it is necessary to manage the temperature of the ink. However, since it is difficult in practice, a technique for controlling the ejection amount of the recording head by managing the temperature of the recording head as a substitute for the ink temperature has become widespread.

  For example, in Patent Document 1, a sensor for detecting the temperature of the head is arranged in the head, and the output of this sensor is monitored by an MPU (CPU) as a detection means. For example, a control method (PWM control) has been proposed in which the heating time of the heater is shortened by changing the pulse width to suppress the head temperature rise and the ink discharge amount is constant.

  However, since the sensor is attached in the vicinity of the head and the output cannot be monitored by the MPU (CPU) due to noise due to the drive of the recording head, there is a problem that accurate temperature control cannot be performed and the discharge amount control is not sufficient. It was.

  On the other hand, in addition to the configuration in which the temperature sensor is provided in the recording head, proposals have been made to use a method such as a mechanism for amplifying the detected temperature output and measures against noise in the detection result. In consideration of reliability, a method for estimating the temperature of the recording head from the image data to be recorded has been proposed, and a proposal for substituting or combining this method has been made.

  For example, before performing the next recording scan as a method for estimating the temperature from the recording data, temporarily store the image data for one main scanning in a memory area such as an image buffer, and count the number of effective data in the image buffer, A method of performing the next recording scan by performing control to change the pulse width of the head drive pulse signal from the count result is known.

  Further, as disclosed in Patent Document 2 and Patent Document 3, the temperature of the recording apparatus or the vicinity of the inkjet head is acquired by a sensor or the like, and the amount of heat input to the inkjet head per unit time is increased. A method of acquiring the temperature of an inkjet head by means for estimating the temperature is known.

  In recent years, there has been a strong demand to use a technique that is more accurate than the conventional temperature estimation method due to an increase in ejection frequency accompanying an increase in recording speed and an increase in the number of nozzles per nozzle row.

  High accuracy of temperature estimation is achieved by shortening the time interval of the temperature estimation calculation. However, the calculation load of the recording apparatus main body increases as the calculation time interval is shortened. ) Needs to be improved, or the throughput is reduced.

  With respect to this problem, Patent Document 3 estimates the temperature of the printhead as a temperature estimation method with high accuracy and low calculation load from the drive conditions of the printhead, and implements the aforementioned PWM control according to this estimated temperature. A technique for performing discharge amount control more accurately is disclosed.

  Specifically, it converts the input heat amount accumulated in the print head from the drive conditions of the print head, calculates the heat storage amount after the heat radiation after unit time from the heat storage amount of the inkjet head until the previous print scan, The recording head heat storage is stored for each constant, and the temperature rise of the recording head is calculated by adding each input heat amount and the heat amount after heat release.

  On the other hand, in Patent Document 4, as a method for estimating temperature and controlling discharge amount from image data in real time especially for large format printers, when valid data is counted from the image data and the count value reaches a predetermined value, the head A method of changing the width of a driving pulse signal or a method of recording data corrected by thinning a predetermined amount of recording data has been proposed.

Furthermore, in recent years, the demand for improving the image quality of recorded images has been very strong with the increase in recording speed, and using a recording head with a smaller ink droplet size and improved nozzle density in order to satisfy these requirements, Development of printers capable of recording images with high definition is in progress.
JP-A-5-31905 Japanese Patent Laid-Open No. 5-208505 JP 7-125216 A JP-A-8-156258 U.S. Pat. No. 4,723,129 U.S. Pat. No. 4,740,796 US Pat. No. 4,463,359 U.S. Pat. No. 4,345,262 US Pat. No. 4,558,333 U.S. Pat. No. 4,459,600 JP 59-123670 A JP 59-138461 A JP-A-54-56847 JP-A-60-71260

  When recording is performed with a recording head having a small ink droplet size, the number of ink dots that should cover the recording area greatly affects the size of the recording area. The case where the droplet size is simply 1/2 will be described. The number of dots to be arranged for recording the same recording area is doubled in the vertical and horizontal directions as shown in FIG. When the number of nozzles of the recording head and the nozzle density are the same and the ejection frequencies are the same, the recording speed is naturally lowered.

  As a means for improving the performance of the recording head itself in order to maintain the same recording speed using a recording head having such a small droplet size, a method for increasing the number of nozzles and increasing the recording width, ink droplets Improvement of the image forming method by increasing the ejection frequency of the recording area, increasing the recording speed for each main scan to reduce the recording time of the recording area, and reducing the number of passes during multi-pass recording, etc. The

  Since the recording time required for one scan is shortened by improving the ink ejection frequency of the recording head, the temperature rise of the recording head accompanying the ink ejection during the scanning increases, resulting in an increase in the ejection amount. Furthermore, since the number of ink dots to be recorded in the recording area is increased by reducing the droplet size, the discharge amount is further increased.

  For this reason, the head temperature rise in one printing scan is increased more than ever, and as a result, the density of the printing area is uneven for each scanning due to the increase in the discharge amount.

  Also, when performing high-speed printing by reducing the number of passes, the number of ink dots ejected in one scan increases with the number of passes. In this case as well, density unevenness in the recording area occurs due to an increase in the ejection amount due to the temperature rise of the recording head. Of course, when both high-speed ejection of ink and reduction in the number of passes are performed, the effect becomes very large.

  On the other hand, the detection of the head temperature by the temperature sensor is insufficient in terms of responsiveness due to the increase in the recording speed, and the means by the temperature estimation means from the recording data also within one discharge timing due to the increase in the discharge frequency. Since the maximum pulse width is reduced, the controllable range of the discharge amount within the changeable range of the pulse width is also narrowed, and the control capability is not sufficient.

  When recording by high-speed ink ejection in the one-pass recording mode as described above is performed by the bidirectional recording method, the entire area recorded for each scan is recorded with a density distribution in the same direction as the main scanning direction.

  Specifically, as shown in FIG. 4, band-like density unevenness occurs for each scan, and particularly noticeably occurs at both ends of the recording area.

  FIG. 5 is a schematic diagram showing the state of the recording area when a solid image of the same gradation is recorded by any one main scanning in the one-pass recording mode, and the relationship between the temperature of the recording head and the ejection amount at that time. .

  In FIG. 5, the head temperature rises as shown in FIG. 5B as the recording head prints in the main scanning direction, and the discharge amount increases as shown in FIG. 5C as this temperature rises. . As a result, density unevenness occurs in the same direction as the main scanning direction as shown in FIG.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to generate ink when performing high-speed recording in an inkjet recording apparatus that performs recording by discharging ink from a recording head. Ink jet recording apparatus and ink jet capable of reducing increase in discharge amount due to temperature rise of recording head due to discharge, reducing density unevenness in the same direction as the main scanning direction of the recording area, and reducing image quality deterioration due to the increase in discharge amount It is to provide a recording method.

In order to achieve the above object, the present invention uses a recording head having a plurality of recording element portions for ejecting ink, and scans the recording head with respect to the recording medium in a direction different from the arrangement direction of the recording elements. In an inkjet recording apparatus or inkjet recording method for forming and completing an image based on data,
The scanning area of the recording head is divided into a plurality of count areas and recording areas in the scanning direction, and the counting means or process for counting the number of recording dots in the count area, and the holding means or process for holding the counted number of dots And a recording apparatus or a recording method for forming an image by changing the image data in the main scanning direction, comprising means or a step for changing the image data in the next recording area according to the counted number of dots,
Image data is image data in which the unit of an image expressing gradation is composed of cluster-type area gradations, and a cluster of image data is concentrated (outer peripheral part) when changing the image data It is characterized by the provision of means or process for preferentially changing from the above.

  Further, according to the present invention, in the above-described ink jet recording apparatus or recording method, the image data is image data in which a unit of an image expressing gradation is composed of distributed area gradation, and the image data is changed when the image data is changed. The image processing apparatus is characterized by comprising means or a process for preferentially changing from an area where the image data is concentrated (outer peripheral portion).

  According to the present invention, in an ink jet recording apparatus that performs recording by ejecting ink from a recording head, an increase in the ejection amount due to temperature rise of the recording head due to ink ejection, which occurs when performing high-speed recording, is reduced. It is possible to provide an ink jet recording method and a recording apparatus that can reduce density unevenness in the same direction as the main scanning direction of the recording area due to an increase in the amount, reduce image quality deterioration, and further prevent cost increase.

  FIG. 6 is a block diagram showing a control configuration of the ink jet recording apparatus according to the embodiment of the present invention. The mechanical configuration of the ink jet recording apparatus of the present embodiment is the same as that shown in FIG.

  In FIG. 6, a CPU 600 executes control of each part of the apparatus and data processing via a main bus line 605. That is, the CPU 600 performs control and data processing of each unit described later including the head drive control circuit 615 and the carriage drive control circuit 616 in accordance with a program stored in the ROM 601. The RAM 602 is used as a work area for data processing by the CPU 600.

  In addition, examples of other storage devices include a hard disk (not shown). The image input unit 603 has an interface with the host device, and temporarily holds an image input from the host device. The image signal processing unit 604 includes a data conversion unit 618 that performs color conversion, binarization, mask processing, and the like, and a data correction unit 619 that executes data processing described below. The operation unit 606 includes keys and the like, thereby enabling control input by the operator. The recovery system control circuit 607 controls a recovery operation such as preliminary ejection in accordance with a recovery processing program stored in the RAM 602. That is, the recovery system motor 608 drives the recording head 613, the cleaning blade 609 facing the space, the cap 610, the suction pump 611, and the like. The head drive control circuit 615 controls the drive of the ink ejection electrothermal transducer of the recording head 613 and normally causes the recording head 613 to perform ink ejection for preliminary ejection and recording. Further, the carriage drive control circuit 616 and the paper feed control circuit 617 similarly control the movement of the carriage and the paper feed according to the program. In addition, a heat retention heater is provided on the substrate on which the electrothermal transducer for ink ejection of the recording head 613 is provided, and the ink temperature in the recording head can be adjusted by heating to a desired set temperature. Similarly, the thermistor 612 is provided on the substrate, and is used to measure the substantial temperature of the ink in the recording head. Similarly, the thermistor 612 may be provided outside the substrate, or may be provided near the periphery of the recording head.

  Based on the above apparatus configuration, the first and second embodiments of the present invention will be described in detail.

(First embodiment)
First, a first embodiment of the present invention will be described. The recording head used in the first embodiment has the same nozzle arrangement as that of the above-described recording head shown in FIG. 1, and the configuration of each nozzle is the same as the conventional one. In the first embodiment, the apparatus configuration is the same as that of the prior art shown in FIG. 2, and one main recording scan is performed bi-directionally on the same recording area to complete an image 1 Pass recording is performed, and this is also the same as that shown in the prior art.

  In addition, as the binarized image data, image data in which the unit of an image expressing a gradation is configured by a cluster type area gradation is used.

As a factor for determining the ejection amount of the ink jet recording head, there is an ink temperature of the ejection section (the temperature of the recording head may be substituted). FIG. 7 is a schematic diagram showing the temperature dependence of the ejection amount when the drive pulse condition is fixed. As shown by a curve A in FIG. 9, the discharge amount Vd increases linearly with an increase in the print head temperature T _H (in this case, it is a static temperature characteristic and is equal to the ink temperature of the discharge portion). If the slope of this straight line is defined as a temperature dependence coefficient, the temperature dependence coefficient is K _T = ΔVd _T / ΔT _H (pl / ° C. · dot). This coefficient _KT is determined by the ink physical properties of the head, etc., regardless of the driving conditions. In FIG. 7, curves B and C are similarly shown for other recording heads.

  In the first embodiment, the recording density on the recording medium is controlled to be constant by using the image correction for changing the total number of dots of the image data for recording the variation in the ejection amount due to the ink temperature variation described above. As a data correction method, binarized data is corrected. Specifically, the processing is performed by the data correction unit 619 in the image signal processing unit 604 in the device control block shown in FIG. 6, and the processing performed by the data processing unit 619 will be described in detail. To go.

  FIG. 8 is a diagram schematically illustrating the concept of a count area for counting the number of recording dots and a recording area for changing the number of dots of recording data used in the present embodiment. In FIG. 8, the recording area is set to have the same size with respect to the dot count area for the sake of easy understanding, and in the present invention, this setting is used for all subsequent descriptions.

  Further, in the first embodiment, when the entire recording area is recorded by l = L scanning, the recording data for one main scanning of the recording head 102 in the l-th scanning, that is, (nozzle number) × (scanning direction). As shown in FIG. 9, the data for (number of pixels in one row) is divided into n pieces in the nozzle arrangement direction (paper feed direction) and m pieces in the scanning direction, each of which includes the same number of pixels. The area is divided into M count areas.

  Specifically, in the first embodiment, when a head having 256 nozzles is used, 256 nozzles are divided in the vertical direction (nozzle arrangement direction) with N = 1, and the horizontal direction (scanning direction) is divided. A recording width of 8 inches is divided into M = 10 pieces. When the recording resolution is 1200 dpi, the recording width is 9600 pixels (= 8 × 1200 dpi), each count area size is 256 × horizontal 960, and the horizontal direction is simply set to 1/10 of the total recording width. Assume that each pixel in the count area corresponds to ejection “1” or non-ejection “0” data.

  Further, as a count result in each count area, the number of droplet discharges in that area obtained by counting only the discharge “1” data in the m-th count area in the horizontal direction and the n-th count area in the vertical direction is the dot count value E. (M, n), the cumulative number of droplet ejections in the horizontal direction of the number of droplet ejections in the n-th count area in the vertical direction, the cumulative dot count value Sm (m, n), recording from the start of printing to the previous scan The total number of droplet discharges by the total dot count value Sa (l−1), and the correction amount calculated for each recording area is represented by H (m, n).

  Specifically, the value indicated by Sm (3, 1) is a dot count value up to the fifth count area in the horizontal direction of the first count area in the vertical direction in FIG. ) To E (3, 1), and Sa (3) is the third time from the start of recording Sm (10, 1), which is the accumulated dot count value of all the horizontal count areas in each scan. Represents the sum added up to the scanning of H, and H (1, 1) represents the print data correction amount (number of dots) in the first print area in the horizontal direction and the first print area in the vertical direction.

  FIG. 10 is a flowchart showing a process of counting the number of dots of print data performed for each scan in the first embodiment and a process for correcting print data based on the counted result.

  This process is started for each scan. First, in step S100, the target count area E (m, n) related to the process is determined as m = 1, n = 1, l = 1, and Sm (1, 1). A memory area such as a register for storing values of .about.Sm (M, N) and Sa (0) to Sa (L) is initialized.

  In step S101, the count start head position of the count area is matched with the data head position of the l-th recording data.

  In step S102, the number of data “1” in the target count area specified by the values of the first count area m = 1 and n = 1 in the horizontal direction is counted, and the dot count value of the count area is set to E ( 1, 1) and temporarily stored in the memory area.

  In step S103, it is determined whether the count area of interest is the first in the horizontal direction, that is, whether it is the head position in the scanning direction. If the count area of interest is the first in the horizontal direction, the process proceeds to step S104. Otherwise, the process proceeds to step S105.

  In step S104, the total dot count value Sa (0) discharged from the start of printing to the printing of the immediately preceding scan (at this time, the first printing scan, i.e., l = 1, so there is no previous discharge, so 0 times). ) Is used to calculate a density increase predicted value due to an increase in the ejection amount, and the correction amount H () of the recording data in the area specified by the values of the first horizontal recording area m = 1 and n = 1. 1, 1) is calculated, and the count value obtained by calculating the correction amount H (1, 1) calculated for E (1, 1), which is the same value as the count value in the recording area, is calculated as a new E (1, 1). 1).

  In step S106, E (1,1) obtained above is added to the value of the accumulated dot count value Sm (m, n) in the horizontal direction, and the corresponding memory area is obtained as a new value of Sm (1,1). To store.

  In steps S107 and S108, correction corresponding to the correction amount H (1, 1) is performed on the recording data in the first recording area in the horizontal direction, and the number of recording data in the recording area is changed.

  First, in step S107, the correction target of the recording data is selected. The correction target is selected by performing pattern analysis of the recording data in the recording area and selecting the target data.

  In step S108, the recording data selected in S107 is changed. To change the recording data, the data “1” portion is changed to “0” by a numerical value corresponding to the correction amount.

In step S109, m <M (= 10) is determined. If m <M, the value of m is incremented by 1, and the count area is shifted by one in the recording scanning direction. (Step S110)
Next, m = 2 is repeated, and the processing from step S102 to step S110 is repeated to correct the recording data in the recording area.

  First, in step S102, the dot count value of the second attention count area in the horizontal direction is set to E (2, 1) and temporarily stored in the memory area.

  In step S103, since the count area of interest is the second in the horizontal direction, the process proceeds to step S105.

  In step S105, the two types of count values E (1, 1) and Sm (1, 1) and the total dot count value Sa (0) (l = 1) discharged from the start of printing to the printing of the immediately preceding scan. Based on the three types of count data (e.g., there is no previous ejection, it is 0), a density increase predicted value due to an increase in ejection amount is calculated, and the value of the second horizontal recording area m = 2, n = 1 The correction amount H (2, 1) of the recording data in the area specified by is calculated, and the correction amount H (2, 1) calculated to E (2, 1), which is the same value as the count value in this recording area. ) Is calculated as a new E (2, 1).

  In the next step S106, E (2, 1) obtained above is added to the previous accumulated dot count value Sm (1, 1) in the horizontal direction to obtain a new accumulated dot count value Sm (2, 1 in the horizontal direction). ) Is stored in the corresponding memory area.

  In steps S107 and S108, correction corresponding to the correction amount H (2, 1) is performed on the recording data in the second recording area in the horizontal direction, and the number of recording data in the recording area is changed.

  First, in step S107, the correction target of the recording data is selected. The correction target is selected by performing pattern analysis of the recording data in the recording area and selecting the target data.

  Next, in step S108, the change of the recording data selected in S107 is changed to a value "0" corresponding to the correction amount for the data "1" portion.

In step S109, m <M (= 10) is determined. If m <M, the value of m is incremented by 1, and the count area is shifted by one in the recording scanning direction. (Step S110)
Thereafter, similarly, the processing from step S102 to step S110 is repeated for all m (1 to M), and the recording data in the corresponding recording area is corrected.

  Next, in step S111, the accumulated dot count value Sm (m, n) in the horizontal direction (which coincides with Sm (10, 1) at this time) is replaced with a new total dot count value Sa (l) (at this time). In this case, l = 1) is stored in the memory area, and the corrected data is transferred to the recording head. Simultaneously with this recording operation, correction processing for recording data for the next main scanning is started.

In step S112, l <L is determined. If l <L, the value of l is incremented by 1, and the count area is shifted by 1 in the vertical direction. (Step S113)
In step S114, among the values counted in the previous scan, the count value E (m, n) in the target count area and the accumulated dot count value Sm (m, n) in the horizontal direction are temporarily stored. Is initialized to 0.

  Thereafter, by repeating the processing from step S101 to step S114, the recording head is ejected from the recording head based on the corrected recording data while the recording data is counted and corrected sequentially, thereby completing the image.

  Next, the recording data correction method used in the first embodiment will be described in detail.

  In the first embodiment, as a method for correcting image data, pattern analysis is performed on image data composed of dot-concentrated clusters (S107), and correction target data is determined based on the pattern analysis result. At this time, the correction target data is selected from data corresponding to the peripheral portion of the dot concentrated cluster. Then, the recording data selected in S108 is corrected.

  FIG. 11 and FIG. 12 are diagrams showing processing for reducing the number of recording dots of the recording data.

  First, the degree of cluster concentration in the recording data is judged (detection of the aggregate), and the periphery of the aggregate is detected. Specifically, edge detection is performed on the recording data, and the size of the aggregate (number of dots) and the peripheral pixel position are specified. FIG. 11 is a schematic diagram when the cluster aggregate is detected and the edge of the aggregate is detected for the recording data in an arbitrary area in the recording area.

  For example, when the total number of dots of the recording data is calculated as 100,000 dots and the number of dots to be reduced as the correction amount is calculated as 2000 dots, a specific image of the size (number of dots) and number of the aggregate and the surrounding pixel positions is obtained by pattern analysis. Next, the data value of the peripheral portion is changed from “1” to “0” in order from the largest aggregate size. This process is repeated until the number of dots reaches 2000 dots. As an aggregate whose data is to be changed, an aggregate composed of 20 or more data “1” is targeted, and the number of changes in the peripheral portion is set differently depending on the size of the aggregate. The number of aggregates increases from 20 to 50, 2 from 51 to 100, 5 from 101 to 200, 10 from 201 to 300, and so on. It is set as follows.

  FIG. 12 is a diagram showing the state before and after the change of the recording data in a part of the area in the recording area shown in FIG. 11, and the data in the peripheral part of the aggregate of the recording data is changed.

  As described above, according to the first embodiment, the print data in the scanning direction of the print head nozzles is divided into a plurality of areas, and the number of discharge data is counted for each area, and the DUTY of the counted discharge data is counted. By changing the number of ejection dots in the recording area according to the recording, it is possible to reduce the density unevenness due to the increase in the ejection amount occurring in the horizontal direction (main scanning direction). It is possible to reduce image quality degradation by performing data correction with priority from the data crowding section.

  As an example of a method for correcting binary data in the correction method of recorded data in the first embodiment, correction is performed with priority from a cluster cluster in which data is dense. However, as a method for selecting a data correction target, Is not limited to this.

  For example, there is a technique using a pattern mask which is a general correction technique.

  Calculate the ratio of the number of dots to be reduced from the correction amount calculated in advance, prepare a mask pattern in which data “0” and data “1” are set to a predetermined ratio in advance, select the closest pattern from them, and record In this method, recording data is thinned out by masking the data.

  In this case, since the data is masked and thinned regardless of “0” or “1” of the recording data, the corrected image is slightly deteriorated, but the effect of reducing the apparatus cost is high. Therefore, the apparatus cost and the image quality are taken into consideration. It is possible to apply.

  In the first embodiment, the case where the number of count areas is set to 10 in the horizontal direction has been described. However, the number of count areas can be arbitrarily divided according to the temperature rise characteristics of the recording head and the droplet size. It can be set to a number.

  For example, as shown in FIG. 13, the number of divisions and the size of the count area may be different for each scan, or the count area may be set to have a different size as shown in FIG. Further, even when the sizes of the count areas are equal, the boundary position of each area may be set to be different for each scanning as shown in FIG.

  Furthermore, in the first embodiment, the case where the size of the count area is equal to the size of the corresponding recording area has been described. However, for example, as shown in FIG. It is. In this case, when correcting the image data in the recording area based on the data counted by the count area, the correction effect at the boundary can be improved because either area overlaps and is corrected. It is.

  Further, in the first embodiment, the calculation method of the correction amount of the image data includes the dot count number in the target count area, the cumulative dot count number in the horizontal direction, and the total dot count number discharged from the start of printing to the printing of the immediately preceding scan. The correction amount is calculated based on these three types of count results. However, it is desirable to select the optimum correction amount calculation method in consideration of calculation accuracy and apparatus cost.

  Further, the correction timing has been described with respect to the method of starting the recording operation after correcting all the recording data for one main scan as in the first embodiment. However, the present invention is not limited to this. For example, it is possible to use a method in which data for a plurality of scans is always processed in advance, or a method in which recording data is transferred to the head at the same time as correction of recording data is completed and recording is performed in real time. It is desirable to use an optimum method according to conditions such as speed, count area size, and number of nozzles.

  Furthermore, in the first embodiment, the case where the recording is performed in the so-called one-pass recording mode in which an image is completed by repeatedly recording the entire head width by the recording head 102 and paper feeding as the recording mode has been described. It is also possible to apply to the multi-pass recording mode used. When applied to this multi-pass printing mode, conditions such as the completion of printing by performing multiple hits in the same printing area, and the small number of printing dots per scan in the first place. It is desirable to calculate the correction amount of the recording data in each pass in consideration.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. The recording head used in the second embodiment has the same nozzle arrangement as the recording head shown in the first embodiment, and the configuration of each nozzle is the same.

  The apparatus configuration and the image recording method are the same as those shown in the first embodiment.

  The relationship between the head temperature and the discharge amount of the recording head is as shown by a curve B in FIG. 7, and a head having a characteristic that the discharge amount increase is larger than the head temperature is used as compared with the first embodiment. .

  In the second embodiment, the method of changing the total number of dots of image data for recording the variation in ejection amount is used as in the first embodiment, and the unit of the image expressing the gradation as the image data is a cluster type area gradation. A method of changing the binarized data is similarly used as the correction method using the configured image data.

  A difference from the first embodiment is that a method of selecting data to be corrected in consideration of the frequency of nozzle use is used.

  Based on the above configuration, in the second embodiment, the case where the 256 nozzles of the head are divided into a predetermined number of areas will be described with reference to the drawings.

  FIG. 9 shows the case where the count area size is set to 256 × vertical 960 in the case where the entire recording area is printed by l = L scans as in the first embodiment. Assume that each pixel in the count area corresponds to ejection “1” or non-ejection “0” data.

  Each count value and integrated value are represented by E (m, n), Sm (m, n), Sa (l-1), and H (m, n), as in the first embodiment.

  FIG. 10 is a flowchart showing a process of counting the number of dots of print data performed for each scan as in the first embodiment, a process for correcting print data based on the counted result, and the like.

  This process is started for each scan. First, in step S100, the target count area E (m, n) related to the process is determined as m = 1, n = 1, l = 1, and Sm (1, 1). A memory area such as a register for storing values of .about.Sm (M, N) and Sa (0) to Sa (L) is initialized.

  In step S101, the count start head position of the count area is matched with the data head position of the l-th recording data.

  In step S102, the number of data “1” in the target count area specified by the values of the first count area m = 1 and n = 1 in the horizontal direction is counted, and the dot count value of the count area is set to E ( 1, 1) and temporarily stored in the memory area.

  In step S103, it is determined whether the count area of interest is the first in the horizontal direction, that is, whether it is the head position in the scanning direction. If the count area of interest is the first in the horizontal direction, the process proceeds to step S104. Otherwise, the process proceeds to step S105.

  In step S104, the total dot count value Sa (0) discharged from the start of printing to the printing of the immediately preceding scan (at this time, the first printing scan, i.e., l = 1, so there is no previous discharge, so 0 times). ) Is used to calculate a density increase predicted value due to an increase in the ejection amount, and the correction amount H () of the recording data in the area specified by the values of the first horizontal recording area m = 1 and n = 1. 1, 1) is calculated, and the count value obtained by calculating the correction amount H (1, 1) calculated for E (1, 1), which is the same value as the count value in the recording area, is calculated as a new E (1, 1). 1).

  In step S106, E (1,1) obtained above is added to the value of the accumulated dot count value Sm (m, n) in the horizontal direction, and the corresponding memory area is obtained as a new value of Sm (1,1). To store.

  In steps S107 and S108, correction corresponding to the correction amount H (1, 1) is performed on the recording data in the first recording area in the horizontal direction, and the number of recording data in the recording area is changed.

  First, in step S107, the correction target of the recording data is selected. The correction target is selected by performing pattern analysis of the recording data in the recording area and selecting the target data.

  In step S108, the recording data selected in S107 is changed. The recording data is changed by changing the data “1” portion to “0” by a numerical value corresponding to the correction amount.

In step S109, m <M (= 10) is determined. If m <M, the value of m is incremented by 1, and the count area is shifted by one in the recording scanning direction. (Step S110)
Next, m = 2 is repeated, and the processing from step S102 to step S110 is repeated to correct the recording data in the recording area.

  First, in step S102, the dot count value of the second attention count area in the horizontal direction is set to E (2, 1) and temporarily stored in the memory area.

  In step S103, since the count area of interest is the second in the horizontal direction, the process proceeds to step S105.

  In step S105, the two types of count values E (1,1) and Sm (1,1) and the total dot count value Sa (0) (l = 1) discharged from the start of printing to the printing of the immediately preceding scan. Based on the three types of count data (e.g., there is no previous ejection, it is 0), a density increase predicted value due to an increase in ejection amount is calculated, and the value of the second horizontal recording area m = 2, n = 1 The correction amount H (2, 1) of the recording data in the area specified by is calculated, and the correction amount H (2, 1) calculated to E (2, 1), which is the same value as the count value in this recording area. ) Is calculated as a new E (2, 1).

  In the next step S106, E (2, 1) obtained above is added to the previous accumulated dot count value Sm (1, 1) in the horizontal direction to obtain a new accumulated dot count value Sm (2, 1 in the horizontal direction). ) Is stored in the corresponding memory area.

  In steps S107 and S108, correction corresponding to the correction amount H (2, 1) is performed on the recording data in the second recording area in the horizontal direction, and the number of recording data in the recording area is changed.

  First, in step S107, the correction target of the recording data is selected. The correction target is selected by performing pattern analysis of the recording data in the recording area and selecting the target data.

  In step S108, the recording data selected in step S107 is changed by changing the data "1" portion to "0" corresponding to the correction amount.

In step S109, m <M (= 10) is determined. If m <M, the value of m is incremented by 1, and the count area is shifted by one in the recording scanning direction. (Step S110)
Thereafter, similarly, the processing from step S102 to step S110 is repeated for all m (1 to M), and the recording data in the corresponding recording area is corrected.

  Next, in step S111, the accumulated dot count value Sm (m, n) in the horizontal direction (which coincides with Sm (10, 1) at this time) is replaced with a new total dot count value Sa (l) (at this time). In this case, l = 1) is stored in the memory area, and the corrected data is transferred to the recording head. Simultaneously with this recording operation, correction processing for recording data for the next main scanning is started.

In step S112, l <L is determined. If l <L, the value of l is incremented by 1, and the count area is shifted by 1 in the vertical direction. (Step S113)
In step S114, among the values counted in the previous scan, the count value E (m, n) in the target count area and the accumulated dot count value Sm (m, n) in the horizontal direction are temporarily stored. Is initialized to 0.

  Thereafter, by repeating the processing from step S101 to step S114, the recording head is ejected from the recording head based on the corrected recording data while the recording data is counted and corrected sequentially, thereby completing the image.

  Next, a recording data correction method used in the second embodiment will be described in detail.

  In the second embodiment, as in the first embodiment, pattern analysis is performed on binary image data in which an image unit is a cluster type area gradation, and correction target data is determined based on the pattern analysis result. .

  At this time, the correction target data is determined by calculating the use frequency of each nozzle from the data in the recording area, giving priority to the data of the nozzles with the high use frequency, and changing the data in order from the periphery of the image. .

  FIGS. 17 and 18 are diagrams showing processing when the number of recording dots of the recording data is reduced in the second embodiment.

  FIG. 17 is a schematic diagram when the dot count value for each nozzle is calculated for print data in an arbitrary area of the print area.

  For example, when the total number of dots of the recording data is calculated as 80000 dots and the number of dots to be reduced as the correction amount is calculated as 2750 dots, the dot count value for each nozzle of the recording data is calculated at the same time. Next, the recording data value is changed from “1” to “0” in descending order of dot count value. This process is repeated until the number of dots reaches 2750 dots. At this time, as a method for determining data to be changed in the scanning direction, the change position is data located at the end of a portion where a plurality of data “1” s are continuous. That is, the data corresponds to the peripheral portion of the recording data.

  Further, the allocation of the number to be changed is changed from 100 data “1” to data “0” for the first to fifth nozzles in the descending order of the dot count value, and the sixth to tenth nozzles of the dot count value are changed. Change 90 data, change 80 data for the 11th to 15th nozzles of the dot count value, change 70 data for the 16th to 20th nozzles of the dot count value, ... The nozzle counts from the 46th to the 50th dot count value are set to change 10 data, and the nozzles from the 51th dot count value onward are not changed. The data change is repeated until the above number is reached for each nozzle.

  FIG. 18 is a diagram illustrating a state before and after the change of the print data in a part of the area in the print area according to the second embodiment, and the data of the nozzle that is frequently used of the print data is changed.

  As described above, according to the second embodiment, the print data in the scanning direction of the print head nozzles is divided into a plurality of areas, and the number of discharge data is counted for each of these areas, and the DUTY of the counted discharge data is counted. By changing the number of ejection dots in the recording area according to the recording, it is possible to reduce the density unevenness due to the increase in the ejection amount occurring in the horizontal direction (main scanning direction). Precise correction from the area where data is concentrated reduces the image quality degradation. Furthermore, by correcting the data priority from frequently used nozzle recording data, the frequency of use is distributed and the life of the nozzle is reduced. Can be prolonged.

  As the print data correction method in the second embodiment, the method shown in the first embodiment and the method of correcting print data with priority given to frequently used nozzles are used in combination, but of course these methods are also limited. It is not a thing. Any method can be applied as long as it can reduce image quality degradation and has the same effect.

  Further, as in the first embodiment, a technique using a pattern mask, which is a general correction technique, can be applied.

  Further, as in the first embodiment, it is desirable to set optimally according to conditions such as the number of divisions of the count area, the cost of the apparatus such as the size, the temperature rise characteristics of the recording head, and the droplet size.

  In addition, the present invention is provided with means (for example, an electrothermal converter, a laser beam, etc.) for generating thermal energy as energy used for performing ink discharge, particularly in the ink jet recording system, and the ink is generated by the thermal energy. In the recording head and the recording apparatus of the type that causes the state change, excellent effects are brought about.

  As its typical configuration and principle, for example, those performed using the basic principle disclosed in US Pat. Nos. 4,723,129 and 4,740,796 are preferable. This method can be applied to both a so-called on-demand type and a continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or liquid path holding the liquid (ink). By applying at least one drive signal corresponding to the recorded information and applying a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, the thermal energy is generated in the electrothermal transducer, and the recording head This is effective because film boiling occurs on the heat acting surface of the liquid and, as a result, bubbles in the liquid (ink) corresponding to the drive signal on a one-to-one basis can be formed. By the growth and contraction of the bubbles, liquid (ink) is ejected through the ejection opening to form at least one droplet. It is more preferable that the drive signal has a pulse shape, since the bubble growth and contraction is performed immediately and appropriately, and thus liquid (ink) discharge with particularly excellent responsiveness can be achieved. As this pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further excellent recording can be performed by employing the conditions described in US Pat. No. 4,313,124 of the invention relating to the temperature rise rate of the heat acting surface.

  As the configuration of the recording head, in addition to the combination configuration (straight liquid channel or right angle liquid channel) of the discharge port, the liquid channel, and the electrothermal transducer as disclosed in each of the above-mentioned specifications, the heat acting part The configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose the configuration in which the lens is disposed in the bending region, are also included in the present invention. In addition, for a plurality of electrothermal transducers, Japanese Patent Application Laid-Open No. Sho 59-123670 that discloses a configuration in which a common slit is used as a discharge portion of the electrothermal transducer or an aperture that absorbs pressure waves of thermal energy is provided. The effect of the present invention is also effective as a configuration based on Japanese Patent Application Laid-Open No. 59-138461 which discloses a configuration corresponding to the discharge unit. That is, regardless of the form of the recording head, according to the present invention, recording can be performed reliably and efficiently.

  Furthermore, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium that can be recorded by the recording apparatus. As such a recording head, either a configuration satisfying the length by a combination of a plurality of recording heads or a configuration as a single recording head formed integrally may be used.

  In addition, even the serial type as shown in the above example can be connected to the main body of the recording head or attached to the main body of the device so that electrical connection with the main body of the device and ink supply from the main body are possible. The present invention is also effective when a replaceable chip type recording head or a cartridge type recording head in which an ink tank is integrally provided in the recording head itself is used. In addition, it is preferable to add a recording head ejection recovery means, a preliminary auxiliary means, and the like as the configuration of the recording apparatus of the present invention, since the effects of the present invention can be further stabilized. Specifically, heating is performed using a capping unit, a cleaning unit, a pressurizing or suction unit, an electrothermal transducer, a heating element different from this, or a combination thereof. Examples thereof include a preliminary heating unit for performing the discharge and a preliminary discharge unit for performing discharge different from the recording.

  Also, regarding the type or number of recording heads to be mounted, for example, a plurality of recording heads are provided corresponding to a plurality of inks having different recording colors and densities, in addition to one provided corresponding to a single color ink. May be used. That is, for example, as a recording mode of the recording apparatus, not only a recording mode of only a mainstream color such as black, but also a recording head may be configured integrally or by a combination of a plurality of different colors, Alternatively, the present invention is extremely effective for an apparatus having at least one of full-color recording modes by color mixing. In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, ink that is solidified at room temperature or lower and that softens or liquefies at room temperature may be used. In the ink jet method, the temperature of the ink itself is generally adjusted within a range of 30 ° C. or higher and 70 ° C. or lower to control the temperature of the ink so that it is in the stable discharge range. A liquid material may be used. In addition, it is solidified and heated in an untreated state in order to actively prevent the temperature rise caused by thermal energy from being used as the energy for changing the state of the ink from the solid state to the liquid state, or to prevent the ink from evaporating. You may use the ink which liquefies by. In any case, by applying thermal energy according to the application of thermal energy according to the recording signal, the ink is liquefied and liquid ink is ejected, or when it reaches the recording medium, it already starts to solidify. The present invention can also be applied to the case where ink having a property of being liquefied for the first time is used. The ink in such a case is in a state of being held as a liquid or a solid in a porous sheet recess or through-hole as described in JP-A-54-56847 or JP-A-60-71260. Alternatively, the electrothermal converter may be opposed to the electrothermal converter. In the present invention, the most effective one for each of the above-described inks is to execute the above-described film boiling method.

  In addition, the ink jet recording apparatus according to the present invention may be used as an image output terminal of an information processing device such as a computer, a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmission / reception function. It may be a thing.

  Hereinafter, the present invention will be described more specifically with reference to examples.

  The recording head used in Example 1 has the same nozzle arrangement as that of the above-described recording head shown in FIG. 1, and the configuration of each nozzle is the same as the conventional one. In the first embodiment, similarly to the above-described prior art, so-called one-pass printing is performed in which an image is completed by performing one main printing scan (pass) on the same printing area. It has become. Specifically, 256 nozzles are arranged at a pitch of 1200 dpi (about 21.2 μm).

  The recording apparatus used in Example 1 has the same configuration as that of the above-described recording apparatus shown in FIG.

  In FIG. 2, reference numeral 201 denotes an ink jet cartridge (recording means). These are constituted by four color inks, that is, ink tanks in which black, cyan, magenta, and yellow ink are respectively stored, and recording heads 102 corresponding to the respective inks.

  Reference numeral 203 denotes a paper feed roller (sub-scanning means) that rotates in the direction of the arrow while sandwiching the recording paper P together with the auxiliary roller 204, and intermittently conveys the recording paper P in the Y direction. Reference numeral 205 denotes a pair of paper feed rollers that feed recording paper. The pair of rollers 205 rotates while pinching the recording paper P, similarly to the rollers 203 and 204, but generates a tension on the recording paper by making the rotation speed lower than that of the paper feeding roller 203, and is transported without bending. Is possible.

  Reference numeral 206 denotes a carriage (main scanning means) that supports the four inkjet cartridges 201 and reciprocates (hereinafter also referred to as scanning or scanning) in the main scanning direction orthogonal to the Y direction. The carriage 206 waits at the home position h at the position indicated by the broken line in the drawing when the recording operation by the recording head is not performed or when the recovery process of the recording head 202 is performed.

  Next, the 1-pass recording mode used in the first embodiment will be described.

  In one-pass printing, the carriage 206 at the home position h before the start of recording moves in the X direction when a recording start command is issued, and is first made 256/1200 inches (about 5.42 mm) onto the paper surface by the recording head 202. ) Record width. When the recording up to the end of the sheet is completed, the carriage 206 stops while decelerating and moves again for recording in the X direction. The paper feed roller 203 rotates in the direction of the arrow between the end of the first recording and before the start of the second scan, and feeds the paper by a width of 256/1200 inches along the Y direction. Even after the second scan, printing is performed with a width of all nozzle widths 256/1200 inches (about 5.42 mm) of the recording head 102. All the recording areas are completed by recording the recording data by one scan of the recording head of each color.

  Each ink droplet was driven to be ejected at 3.0 ± 0.5 pl. As the ink containing the color material, a commercially available ink for inkjet printer PIXSUS860i (manufactured by Canon Inc.) was used.

  As a printing material, A4 size inkjet plain paper (super white paper, SW-101: manufactured by Canon Inc.) was prepared.

  The print head and the printing method will be described in further detail. As a driving speed, the ink droplet ejection driving frequency was set to 30 kHz. An image 1 having a graphic image was prepared as an image to be printed. The image size is as follows.

<Image 1>
Graphic image: 8 inches × 10 inches FIG. 19 schematically shows an image arrangement image of the image 1 on the paper surface.

  Further, the first embodiment uses image data in which a unit of an image expressing a gradation is configured by a cluster type area gradation as image data, and a correction method is similarly a method of changing binarized data. Is used.

  FIGS. 11 and 12 are diagrams schematically showing data states before and after correction when the recording data is changed in the first embodiment.

  For example, when the total number of dots of the recording data is calculated as 100,000 dots and the number of dots to be reduced as the correction amount is calculated as 1000 dots, the size of the aggregate is large based on the detected recording data aggregate size and edge position. The data value of the peripheral part is changed from “1” to “0” in order. At this time, as an aggregate whose data is changed, an aggregate composed of 20 or more data “1” is targeted, and one size is 20 to 100, 5 is from 101 to 200, and 10 is from 201 to 300. The number to be changed according to the size is set to be large.

  Next, FIG. 20 is a diagram for schematically explaining the concept of a count area for counting the number of recording dots used in the first embodiment.

  In the first embodiment, the entire recording area is recorded by scanning for l = 48 times, and recording data for one main scan of the head 102, that is, (number of nozzles) × (number of pixels in one row in the scanning direction). For the minute data, the 256 nozzles of the recording head 102 are not divided in the vertical direction (nozzle row direction), and the recording width of 8 inches is divided into 10 in the horizontal direction (scanning direction). When the recording resolution is 1200 dpi, the recording width is 9600 pixels (= 8 × 1200), and each count area size is set to 256 × width 960. Assume that each pixel in the count area corresponds to ejection “1” or non-ejection “0” data.

  As each count value and integrated value, E (m, n) is the dot count value of the area obtained by counting only the discharge “1” data in the m-th count area in the horizontal direction, and the integrated count area in the horizontal direction. The number of droplet discharges is calculated for each recording area as the cumulative dot count value Sm (m, n), and the total number of cumulative droplet discharges in the horizontal direction for all recording widths is the total dot count value Sa (l-1). It is assumed that the correction amount is represented by H (m, n).

  FIG. 10 is a flowchart illustrating a process for counting the number of dots of print data performed for each scan in the first embodiment, a process for correcting print data based on the counted result, and the like.

  This process is started for each scan. First, in step S100, the target count area E (m, n) related to the process is determined as m = 1, n = 1, l = 1, and Sm (1, 1). A register which is a memory area for storing values of .about.Sm (M, N) and Sa (0) to Sa (L) is initialized.

  In step S101, the count start head position of the count area is matched with the data head position of the l-th recording data.

  In step S102, the number of data “1” in the first count area in the horizontal direction is counted, and the dot count value in the count area is set to E (1, 1) and stored in the register.

  At this time, E (1,1) = 100000 dots.

  In step S103, it is determined whether the count area of interest is the first in the horizontal direction, that is, whether it is the head position in the scanning direction. If the count area of interest is the first in the horizontal direction, the process proceeds to step S104. Otherwise, the process proceeds to step S105.

  In step S104, the total dot count value Sa (0) discharged from the start of printing to the printing of the immediately preceding scan (at this time, the first printing scan, i.e., l = 1, so there is no previous discharge, so 0 times). ) To calculate the density increase predicted value due to the increase in the discharge amount, calculate the correction amount H (1, 1) of the recording data in the first recording area in the horizontal direction, and count within this recording area. A count value obtained by calculating the correction amount H (1, 1) calculated for E (1, 1), which is the same value as the value, is defined as a new E (1, 1).

The correction amount H (1, 1) calculated at this time was 0 dot, and the new count value was E (1, 1) = 100000 dots (= 100000-0).

  In step S106, E (1, 1) obtained above is added to the value of the accumulated dot count value Sm (m, n) in the horizontal direction, and a new value of Sm (1, 1) is added to the corresponding register. Store.

  Sm (1,1) = E (1,1) = 100000 dots.

  In steps S107 and S108, correction corresponding to the correction amount H (1, 1) is performed on the recording data in the first recording area in the horizontal direction, and the number of recording data in the recording area is changed. The recording data is changed by changing the data “1” portion to “0” corresponding to the correction amount. Since the correction amount H (1, 1) = 0 dot at this time, the data No changes are made.

In step S109, m> M (= 10) is determined. If m <M, the value of m is incremented by 1, and the count area is shifted by 1 in the recording scanning direction. (Step S110)
Next, m = 2 is repeated, and the processing from step S102 to step S110 is repeated to correct the recording data in the recording area.

  First, in step S102, the dot count value of the second target count area in the horizontal direction is set to E (2, 1) and stored in the register.

  At this time, E (2, 1) = 80000 dots.

  Since the count area of interest in step S103 is the second in the horizontal direction, the process proceeds to step S105. In step S105, the two types of count values E (1, 1), Sm (1, 1) and the start of recording are counted. Based on the three types of count data of the total dot count value Sa (0) ejected up to the recording of the immediately preceding scanning (0 because there is no preceding ejection because l = 1), the density increase prediction due to the increased ejection amount The value is calculated to calculate the recording data correction amount H (2, 1) of the second recording area in the horizontal direction, and calculated to E (2, 1), which is the same value as the count value in this recording area. The count value obtained by calculating the correction amount H (2, 1) is set as a new E (2, 1).

The correction amount H (2, 1) calculated at this time was 2000 dots, and the new count value was E (2, 1) = 78000 dots (= 80000−2000).

  In the next step S106, E (2, 1) obtained above is added to the previous accumulated dot count value Sm (1, 1) in the horizontal direction to obtain a new accumulated dot count value Sm (2, 1 in the horizontal direction). ) Value in the corresponding register.

  Sm (2, 1) = 178000 dots (= 100000 + 78000).

  In steps S107 and S108, correction corresponding to the correction amount H (2, 1) is performed on the recording data in the second recording area in the horizontal direction, and the number of recording data in the recording area is changed.

  First, in step S107, the correction target of the recording data is selected. The correction target is selected by performing the above-described pattern analysis and selecting target data.

  Next, in step S108, the recording data selected in S107 is changed by changing the portion of data "1" to "0" corresponding to the correction amount.

Specifically, the dot count number of the recording data is calculated as E (2,1) = 80000 dots, and the number of dots to be reduced as the correction amount is calculated as H (2,1) = 2000 dots. The body size and number and the edge position are specified. Next, the data value of the peripheral portion is changed from “1” to “0” in order from the largest aggregate size up to a value corresponding to the correction amount H (2, 1). (Fig. 12)
In step S109, m> M (= 10) is determined. If m <M, the value of m is incremented by 1, and the count area is shifted by 1 in the recording scanning direction. (Step S110)
Thereafter, similarly, the processing from step S102 to step S110 is repeated for all m (1 to M), and the recording data in the corresponding recording area is corrected.

  Next, in step S111, the value of the accumulated dot count value Sm (m, n) in the horizontal direction (which coincides with Sm (10, 1) at this time) is set as a new total dot count value Sa (1) (this time In this case, l = 1) is stored in the register, and the corrected data is transferred to the recording head. Simultaneously with this recording operation, correction processing for recording data for the next main scanning is started.

  Sa (1) = Sm (10,1) = 9050000 dots.

In step S112, l> L is determined. If l <L, the value of l is incremented by 1, and the count area is shifted by 1 in the vertical direction. (Step S113)
In step S114, among the values counted in the previous scan, the count value E (m, n) in the target count area and the accumulated dot count value Sm (m, n) in the horizontal direction are temporarily stored. Initialize registers to zero.

  Thereafter, the process from step S101 to step S114 is repeated up to 48 times, which is the total number of recording scans, so that the recording head counts and corrects the recording data while performing the correction process sequentially. The image was completed by discharging.

  The image 1 formed in this way was able to obtain good image quality with no density difference and density unevenness in the vicinity of both ends as seen in the entire image and no deterioration in image quality.

  The recording head used in the second embodiment has the same nozzle arrangement as that of the above-described recording head shown in FIG. 1 as in the first embodiment, and each nozzle has 256 nozzles at a 1200 dpi (about 21.2 μm) pitch. The arrangement is also the same. The recording method using one pass and the configuration of the recording apparatus are the same. Further, as in Example 1, each ink droplet was driven to be ejected at 3.0 ± 0.5 pl. As the ink containing the color material, a commercially available ink for inkjet printer PIXSUS860i (manufactured by Canon Inc.) was used.

  As the printing material, A4 size inkjet plain paper (Super White Paper, SW-101: manufactured by Canon Inc.) was prepared.

  The print head and the printing method will be described in further detail. As a driving speed, the ink droplet ejection driving frequency was set to 30 kHz. As an image to be printed, an image 2 which is a graphic image in which a photograph exists is prepared. The image size is as follows.

<Image 2>
Graphic image: 8 inches × 6 inches FIG. 21 schematically shows an image arrangement image of the image 2 on the paper surface.

  In the second embodiment, as in the first embodiment, image data in which a unit of an image expressing a gradation is configured by a cluster area gradation is used as the image data, and the correction method is 2 as in the first embodiment. A method of changing quantified data is used. The difference from the first embodiment is that the selection method of data to be corrected is selected in consideration of the frequency of nozzle use. The correction target data is determined by calculating the use frequency of each nozzle from the data in the recording area and changing the data of the nozzles having a high use frequency with priority.

  FIGS. 17 and 18 are diagrams schematically showing processing for changing the recording data in the second embodiment.

  FIG. 17 is a schematic diagram when the dot count value for each nozzle is calculated for print data in an arbitrary area within the print area.

  For example, when the total number of dots of the print data is calculated as 100,000 dots and the number of dots to be reduced as the correction amount is calculated as 2750 dots, the dot count value for each nozzle of the print data is calculated at the same time. Next, the recording data value is changed from “1” to “0” in descending order of dot count value. This process is repeated until the number of dots reaches 2750 dots. At this time, as a method for determining data to be changed in the scanning direction, the change position is data located at the end of a portion where a plurality of data “1” s are continuous. That is, the data corresponds to the peripheral portion of the recording data.

  Further, the allocation of the number to be changed is changed from 100 data “1” to data “0” for the first to fifth nozzles in descending order of the dot count value, and the sixth to tenth nozzles of the dot count value. Changes 90 data, the 11th to 15th nozzle of the dot count value changes 80 data, the 16th to 20th nozzle of the dot count value changes 70 data, ············································································································ The data change is repeated until the above number is reached for each nozzle.

  FIG. 18 is a diagram illustrating a state before and after the change of the print data in a part of the area in the print area according to the second embodiment, and the data of the nozzle that is frequently used of the print data is changed.

  Next, FIG. 22 is a diagram schematically illustrating the concept of a count area for counting the number of recording dots used in the second embodiment.

  In the second embodiment, the entire print area is printed by l = 29 scans, and print data for one main scan of the head 102, that is, (number of nozzles) × (number of pixels in one row in the scan direction). For the minute data, the 256 nozzles of the recording head 102 are not divided in the vertical direction (nozzle row direction), and the recording width of 8 inches is divided into 10 in the horizontal direction (scanning direction). When the recording resolution is 1200 dpi, the recording width is 9600 pixels (= 8 × 1200), and each count area size is set to 256 × width 960. The discharge “1” or non-discharge “0” data is associated with each pixel in the count area.

  Each count value and integrated value are represented by E (m, n), Sm (m, n), Sa (l-1), and H (m, n), as in the first embodiment.

  FIG. 10 shows a process for counting the number of dots of print data performed for each scan in the second embodiment, a process for correcting print data based on the counted result, and the like as in the first embodiment. It is a flowchart.

  This process is started for each scan. First, in step S100, the target count area E (m, n) related to the process is determined as m = 1, n = 1, l = 1, and Sm (1, 1). A register which is a memory area for storing values of .about.Sm (M, N) and Sa (1) to Sa (L) is initialized.

  In step S101, the count start head position of the count area is matched with the data head position of the l-th recording data.

  In step S102, the number of data “1” in the first count area in the horizontal direction is counted, and the dot count value in the count area is set to E (1, 1) and stored in the register.

  At this time, E (1,1) = 100000 dots.

  In step S103, it is determined whether the count area of interest is the first in the horizontal direction, that is, whether it is the head position in the scanning direction. If the count area of interest is the first in the horizontal direction, the process proceeds to step S104. Otherwise, the process proceeds to step S105.

  In step S104, the total dot count value Sa (0) discharged from the start of printing to the printing of the immediately preceding scan (at this time, the first printing scan, i.e., l = 1, so there is no previous discharge, so 0 times). ) To calculate the density increase predicted value due to the increase in the discharge amount, calculate the correction amount H (1, 1) of the recording data in the first recording area in the horizontal direction, and count within this recording area. A count value obtained by calculating the correction amount H (1, 1) calculated for E (1, 1), which is the same value as the value, is defined as a new E (1, 1).

The correction amount H (1, 1) calculated at this time was 0 dot, and the new count value was E (1, 1) = 100000 dots (= 100000-0).

  In step S106, E (1,1) obtained above is added to the value of the accumulated dot count value Sm (m, n) in the horizontal direction, and a new value of Sm (1,1) is added to the corresponding register. Store.

  Sm (1,1) = E (1,1) = 100000 dots.

  In steps S107 and S108, correction corresponding to the correction amount H (1, 1) is performed on the recording data in the first recording area in the horizontal direction, and the number of recording data in the recording area is changed. The recording data is changed by changing the data “1” portion to “0” corresponding to the correction amount. Since the correction amount H (1, 1) = 0 dot at this time, the data No changes are made.

In step S109, m> M (= 10) is determined. If m <M, the value of m is incremented by 1, and the count area is shifted by 1 in the recording scanning direction. (Step S110)
Next, m = 2 is repeated, and the processing from step S102 to step S110 is repeated to correct the recording data in the recording area.

  First, in step S102, the dot count value of the second target count area in the horizontal direction is set to E (2, 1) and stored in the register.

  At this time, E (2, 1) = 80000 dots.

  Since the count area of interest in step S103 is the second in the horizontal direction, the process proceeds to step S105. In step S105, the two types of count values E (1, 1), Sm (1, 1) and the start of recording are counted. Based on the three types of count data of the total dot count value Sa (0) ejected up to the recording of the immediately preceding scanning (0 because there is no preceding ejection because l = 1), the density increase prediction due to the increased ejection amount The value is calculated to calculate the recording data correction amount H (2, 1) of the second recording area in the horizontal direction, and calculated to E (2, 1), which is the same value as the count value in this recording area. The count value obtained by calculating the correction amount H (2, 1) is set as a new E (2, 1).

The correction amount H (2, 1) calculated at this time is 2750 dots, and the new count value is E (2, 1) = 77250 dots (= 80000-2750).

  In the next step S106, E (2, 1) obtained above is added to the previous accumulated dot count value Sm (1, 1) in the horizontal direction to obtain a new accumulated dot count value Sm (2, 1 in the horizontal direction). ) Value in the corresponding register.

  Sm (2, 1) = 177250 dots (= 100000 + 77250).

  In steps S107 and S108, correction corresponding to the correction amount H (2, 1) is performed on the recording data in the second recording area in the horizontal direction, and the number of recording data in the recording area is changed.

  First, in step S107, the correction target of the recording data is selected. The correction target is selected by performing the above-described pattern analysis and selecting target data.

  Next, in step S108, the recording data selected in S107 is changed by changing the portion of data "1" to "0" corresponding to the correction amount.

Specifically, the dot count number of the recording data is calculated as E (2, 1) = 80000 dots, and the dot number to be reduced as the correction amount is calculated as H (2, 1) = 2750 dots, and the dot count value for each nozzle is simultaneously calculated. Calculate and specify the data change nozzle. Next, the data value is changed from “1” to “0” in order from the largest dot count value up to a value corresponding to the correction amount H (2, 1). At this time, the method for determining the data to be changed in the scanning direction changed the position of the continuous data edge. (Fig. 18)
In step S109, m> M (= 10) is determined. If m <M, the value of m is incremented by 1, and the count area is shifted by 1 in the recording scanning direction. (Step S110)
Thereafter, similarly, the processing from step S102 to step S110 is repeated for all m (1 to M), and the recording data in the corresponding recording area is corrected.

  Next, in step S111, the accumulated dot count value Sm (m, n) in the horizontal direction (which coincides with Sm (10, 1) at this time) is replaced with a new total dot count value Sa (l) (at this time). In this case, l = 1) is stored in the register, and the corrected data is transferred to the recording head. Simultaneously with this recording operation, correction processing for recording data for the next main scanning is started.

  Sa (1) = Sm (10,1) = 9050000 dots.

In step S112, l> L is determined. If l <L, the value of l is incremented by 1, and the count area is shifted by 1 in the vertical direction. (Step S113)
In step S114, among the values counted in the previous scan, the count value E (m, n) in the target count area and the accumulated dot count value Sm (m, n) in the horizontal direction are temporarily stored. Initialize registers to zero.

  Thereafter, the processing from step S101 to step S114 is repeated up to 29 times, which is the total number of recording scans, so that the recording head counts and corrects the recording data while performing the correction processing sequentially, and ink is supplied from the recording head. The image was completed by discharging.

  The image 2 formed in this way was able to obtain good image quality with no density difference and density unevenness in the vicinity of both ends as seen in the entire image and no deterioration in image quality.

  Furthermore, as an example 3, an example in which an image pattern in which the binary image data format is not a cluster type area gradation but a distributed area gradation in the same configuration as the example 1 is shown.

  The recording head used in the third embodiment has the same nozzle arrangement as that of the above-described recording head shown in FIG. 1 as in the first embodiment, and each nozzle has 256 nozzles at a 1200 dpi (about 21.2 μm) pitch. The arrangement is also the same. The recording method using one pass and the configuration of the recording apparatus are the same. Further, as in Example 1, each ink droplet was driven to be ejected at 3.0 ± 0.5 pl. As the ink containing the color material, a commercially available ink for inkjet printer PIXSUS860i (manufactured by Canon Inc.) was used.

  As the printing material, A4 size inkjet plain paper (Super White Paper, SW-101: manufactured by Canon Inc.) was prepared.

  The print head and the printing method will be described in further detail. As a driving speed, the ink droplet ejection driving frequency was set to 30 kHz. As an image to be printed, an image 1 which is a graphic image was prepared as in the first embodiment. The image size is as follows.

<Image 1>
Graphic image: 8 inches × 10 inches The recording data correction method was performed in the same manner as in Example 1 for the recording data correction method. Based on the detected recording data aggregate size and edge position, The data value in the peripheral portion is changed from “1” to “0” in order from the largest size.

  FIG. 20 schematically shows the concept of a count area for counting the number of recording dots and a recording area for changing the number of dots of recording data used in the third embodiment as in the first embodiment.

  In the third embodiment, the method for dividing the entire recording area and the number of divisions are set in the same manner as in the first embodiment.

  Each count value and integrated value are represented by E (m, n), Sm (m, n), Sa (l-1), and H (m, n), as in the first embodiment.

  FIG. 10 shows a process for counting the number of dots of print data performed for each scan in the third embodiment and a process for correcting print data based on the counted result, as in the first and second embodiments. It is a flowchart to show.

  This process is started for each scan. First, in step S100, the target count area E (m, n) related to the process is determined as m = 1, n = 1, l = 1, and Sm (1, 1). A register which is a memory area for storing values of .about.Sm (M, N) and Sa (1) to Sa (L) is initialized.

  In step S101, the count start head position of the count area is matched with the data head position of the l-th recording data.

  In step S102, the number of data “1” in the first count area in the horizontal direction is counted, and the dot count value in the count area is set to E (1, 1) and stored in the register.

  At this time, E (1,1) = 130,000 dots.

  In step S103, it is determined whether the count area of interest is the first in the horizontal direction, that is, whether it is the head position in the scanning direction. If the count area of interest is the first in the horizontal direction, the process proceeds to step S104. Otherwise, the process proceeds to step S105.

  In step S104, the total dot count value Sa (0) discharged from the start of printing to the printing of the immediately preceding scan (at this time, the first printing scan, i.e., l = 1, so there is no previous discharge, so 0 times). ) To calculate the density increase predicted value due to the increase in the discharge amount, calculate the correction amount H (1, 1) of the recording data in the first recording area in the horizontal direction, and count within this recording area. A count value obtained by calculating the correction amount H (1, 1) calculated for E (1, 1), which is the same value as the value, is defined as a new E (1, 1).

The correction amount H (1, 1) calculated at this time is 0 dot, and the new count value is E (1, 1) = 130,000 dots (= 100000-0).

  In step S106, E (1,1) obtained above is added to the value of the accumulated dot count value Sm (m, n) in the horizontal direction, and a new value of Sm (1,1) is added to the corresponding register. Store.

  Sm (1,1) = E (1,1) = 130,000 dots.

  In steps S107 and S108, correction corresponding to the correction amount H (1, 1) is performed on the recording data in the first recording area in the horizontal direction, and the number of recording data in the recording area is changed. The recording data is changed by changing the data “1” portion to “0” corresponding to the correction amount. Since the correction amount H (1, 1) = 0 dot at this time, the data No changes are made.

In step S109, m> M (= 10) is determined. If m <M, the value of m is incremented by 1, and the count area is shifted by 1 in the recording scanning direction. (Step S110)
Next, m = 2 is repeated, and the processing from step S102 to step S110 is repeated to correct the recording data in the recording area.

  First, in step S102, the dot count value of the second target count area in the horizontal direction is set to E (2, 1) and stored in the register.

  At this time, E (2, 1) = 90000 dots.

  Since the count area of interest in step S103 is the second in the horizontal direction, the process proceeds to step S105. In step S105, the two types of count values E (1, 1), Sm (1, 1) and the start of recording are counted. Based on the three types of count data of the total dot count value Sa (0) ejected up to the recording of the immediately preceding scanning (0 because there is no preceding ejection because l = 1), the density increase prediction due to the increased ejection amount The value is calculated to calculate the recording data correction amount H (2, 1) of the second recording area in the horizontal direction, and calculated to E (2, 1), which is the same value as the count value in this recording area. The count value obtained by calculating the correction amount H (2, 1) is set as a new E (2, 1).

The correction amount H (2, 1) calculated at this time was 10,000 dots, and the new count value was E (2, 1) = 80000 dots (= 90000-10000).

  In the next step S106, E (2, 1) obtained above is added to the previous accumulated dot count value Sm (1, 1) in the horizontal direction to obtain a new accumulated dot count value Sm (2, 1 in the horizontal direction). ) Value in the corresponding register.

  Sm (2, 1) = 210,000 dots (= 130,000 + 80000).

  In steps S107 and S108, correction corresponding to the correction amount H (2, 1) is performed on the recording data in the second recording area in the horizontal direction, and the number of recording data in the recording area is changed.

  First, in step S107, the correction target of the recording data is selected. The correction target is selected by performing the above-described pattern analysis and selecting target data.

  Next, in step S108, the recording data selected in S107 is changed by changing the portion of data "1" to "0" corresponding to the correction amount.

More specifically, the dot count number of the recording data is calculated as E (2,1) = 90000 dots, and the number of dots to be reduced as the correction amount is calculated as H (2,1) = 10000 dots. The body size and number and the edge position are specified. Next, the data value of the peripheral portion is changed from “1” to “0” in order from the largest aggregate size up to a value corresponding to the correction amount H (2, 1). (Fig. 23)
Unlike the first embodiment, the image data is formed with distributed area gradation, and therefore, an aggregate composed of 10 or more data “1” is targeted as an aggregate for changing data. Furthermore, when there was no difference in the size of the aggregates, it was set to change in order from the beginning in the scanning direction.

In step S109, m> M (= 10) is determined. If m <M, the value of m is incremented by 1, and the count area is shifted by 1 in the recording scanning direction. (Step S110)
Thereafter, similarly, the processing from step S102 to step S110 is repeated for all m (1 to M), and the recording data in the corresponding recording area is corrected.

  Next, in step S111, the accumulated dot count value Sm (m, n) in the horizontal direction (which coincides with Sm (10, 1) at this time) is replaced with a new total dot count value Sa (l) (at this time). In this case, l = 1) is stored in the register, and the corrected data is transferred to the recording head. Simultaneously with this recording operation, correction processing for recording data for the next main scanning is started.

  Sa (1) = Sm (10,1) = 9850000 dots.

In step S112, l> L is determined. If l <L, the value of l is incremented by 1, and the count area is shifted by 1 in the vertical direction. (Step S113)
In step S114, among the values counted in the previous scan, the count value E (m, n) in the target count area and the accumulated dot count value Sm (m, n) in the horizontal direction are temporarily stored. Initialize registers to zero.

  Thereafter, the process from step S101 to step S114 is repeated up to 48 times, which is the total number of recording scans, so that the recording head counts and corrects the recording data while performing the correction process sequentially. The image was completed by discharging.

  The image 1 formed in this way was able to obtain good image quality with no density difference and density unevenness in the vicinity of both ends as seen in the entire image and no deterioration in image quality.

  Further, as Example 4, another example in the case of using an image pattern in which the binary image data format is not a cluster type area gradation but a distributed type area gradation in the same configuration as that of Example 2 is shown.

  The recording head used in the fourth embodiment has the same nozzle arrangement as that of the above-described recording head shown in FIG. 1 as in the second embodiment, and each nozzle has 256 nozzles at a 1200 dpi (about 21.2 μm) pitch. The arrangement is also the same. The recording method using one pass and the configuration of the recording apparatus are the same. Further, as in Example 2, each ink droplet was driven to be ejected at 3.0 ± 0.5 pl. As the ink containing the color material, a commercially available ink for inkjet printer PIXSUS860i (manufactured by Canon Inc.) was used.

  As the printing material, A4 size inkjet plain paper (Super White Paper, SW-101: manufactured by Canon Inc.) was prepared.

  The print head and the printing method will be described in further detail. As a driving speed, the ink droplet ejection driving frequency was set to 30 kHz. As an image to be printed, an image 2 that is a graphic image in which a photograph exists is prepared as in the second embodiment. The image size is as follows.

<Image 2>
Graphic image: 8 inches × 6 inches The recording data correction method is also performed in the same manner as in the second embodiment, and the pattern analysis of the recording data is performed, and the correction target data is determined by calculating the usage frequency of each nozzle from the data in the recording area. A method of preferentially changing nozzle data that is frequently used is used.

  FIG. 22 schematically illustrates the concept of the count area for counting the number of recording dots and the recording area for changing the number of dots of the recording data used in the fourth embodiment as in the second embodiment.

  In the fourth embodiment, the method for dividing the entire recording area and the number of divisions are set in the same manner as in the second embodiment.

  Each count value and integrated value are represented by E (m, n), Sm (m, n), Sa (l-1), and H (m, n), as in the second embodiment.

  FIG. 10 is a flowchart showing a process of counting the number of dots of print data performed for each scan, a process for correcting print data based on the counted result, and the like, as in the other embodiments.

  This process is started for each scan. First, in step S100, the target count area E (m, n) related to the process is determined as m = 1, n = 1, l = 1, and Sm (1, 1). A register which is a memory area for storing values of .about.Sm (M, N) and Sa (0) to Sa (L) is initialized.

  In step S101, the count start head position of the count area is matched with the data head position of the l-th recording data.

  In step S102, the number of data “1” in the first count area in the horizontal direction is counted, and the dot count value in the count area is set to E (1, 1) and stored in the register.

  At this time, E (1,1) = 80000 dots.

  In step S103, it is determined whether the count area of interest is the first in the horizontal direction, that is, whether it is the head position in the scanning direction. If the count area of interest is the first in the horizontal direction, the process proceeds to step S104. Otherwise, the process proceeds to step S105.

  In step S104, the total dot count value Sa (0) discharged from the start of printing to printing of the immediately preceding scan (at this time, the first printing scan, i.e., l = 1, so there is no immediately preceding discharge, so 0). ) To calculate the density increase predicted value due to the increase in the discharge amount, calculate the correction amount H (1, 1) of the recording data in the first recording area in the horizontal direction, and count within this recording area. A count value obtained by calculating the correction amount H (1, 1) calculated for E (1, 1), which is the same value as the value, is defined as a new E (1, 1).

The correction amount H (1, 1) calculated at this time is 0 dot, and the new count value is E (1, 1) = 80000 dots (= 800,000-0).

  In step S106, E (1,1) obtained above is added to the value of the accumulated dot count value Sm (m, n) in the horizontal direction, and a new value of Sm (1,1) is added to the corresponding register. Store.

  Sm (1,1) = E (1,1) = 80000 dots.

  In steps S107 and S108, correction corresponding to the correction amount H (1, 1) is performed on the recording data in the first recording area in the horizontal direction, and the number of recording data in the recording area is changed. The recording data is changed by changing the data “1” portion to “0” corresponding to the correction amount. Since the correction amount H (1, 1) = 0 dot at this time, the data No changes are made.

In step S109, m> M (= 10) is determined. If m <M, the value of m is incremented by 1, and the count area is shifted by 1 in the recording scanning direction. (Step S110)
Next, m = 2 is repeated, and the processing from step S102 to step S110 is repeated to correct the recording data in the recording area.

  First, in step S102, the dot count value of the second target count area in the horizontal direction is set to E (2, 1) and stored in the register.

  At this time, E (2, 1) = 70000 dots.

  Since the count area of interest in step S103 is the second in the horizontal direction, the process proceeds to step S105. In step S105, the two types of count values E (1, 1), Sm (1, 1) and the start of recording are counted. Based on the three types of count data of the total dot count value Sa (0) ejected up to the recording of the immediately preceding scanning (0 because there is no preceding ejection because l = 1), the density increase prediction due to the increased ejection amount The value is calculated to calculate the recording data correction amount H (2, 1) of the second recording area in the horizontal direction, and calculated to E (2, 1), which is the same value as the count value in this recording area. The count value obtained by calculating the correction amount H (2, 1) is set as a new E (2, 1).

The correction amount H (2, 1) calculated at this time is 4000 dots, and the new count value is E (2, 1) = 66000 dots (= 70000-4000).

  In the next step S106, E (2, 1) obtained above is added to the previous accumulated dot count value Sm (1, 1) in the horizontal direction to obtain a new accumulated dot count value Sm (2, 1 in the horizontal direction). ) Value in the corresponding register.

  Sm (2, 1) = 146000 dots (= 80000 + 66000).

  In steps S107 and S108, correction corresponding to the correction amount H (2, 1) is performed on the recording data in the second recording area in the horizontal direction, and the number of recording data in the recording area is changed.

  First, in step S107, the correction target of the recording data is selected. The correction target is selected by performing the above-described pattern analysis and selecting target data.

  Next, in step S108, the recording data selected in S107 is changed by changing the portion of data "1" to "0" corresponding to the correction amount.

Specifically, the dot count number of the recording data is calculated as E (2,1) = 70000 dots, and the number of dots to be reduced as the correction amount is calculated as H (2,1) = 4000 dots, and the dot count value for each nozzle is simultaneously calculated. Calculate and specify the data change nozzle. Next, the data value is changed from “1” to “0” in order from the largest dot count value up to a value corresponding to the correction amount H (2, 1). At this time, the method for determining the data to be changed in the scanning direction changes the position of the end of the continuous data. (Fig. 24)
Since the image data is formed with distributed area gradation unlike the second embodiment, the case where 10 or more pieces of data “1” continue in the specified nozzle is set as a change target.

In step S109, m> M (= 10) is determined. If m <M, the value of m is incremented by 1, and the count area is shifted by 1 in the recording scanning direction. (Step S110)
Thereafter, similarly, the processing from step S102 to step S110 is repeated for all m (1 to M), and the recording data in the corresponding recording area is corrected.

  Next, in step S111, the accumulated dot count value Sm (m, n) in the horizontal direction (which coincides with Sm (10, 1) at this time) is replaced with a new total dot count value Sa (l) (at this time). In this case, l = 1) is stored in the register, and the corrected data is transferred to the recording head. Simultaneously with this recording operation, correction processing for recording data for the next main scanning is started.

  Sa (1) = Sm (10,1) = 8650000 dots.

In step S112, l> L is determined. If l <L, the value of l is incremented by 1, and the count area is shifted by 1 in the vertical direction. (Step S113)
In step S114, among the values counted in the previous scan, the count value E (m, n) in the target count area and the accumulated dot count value Sm (m, n) in the horizontal direction are temporarily stored. Initialize registers to zero.

  Thereafter, the processing from step S101 to step S114 is repeated up to 29 times, which is the total number of recording scans, so that the recording head counts and corrects the recording data while performing the correction processing sequentially, and ink is supplied from the recording head. The image was completed by discharging.

  The image 1 formed in this way was able to obtain good image quality with no density difference and density unevenness in the vicinity of both ends as seen in the entire image and no deterioration in image quality.

It is a schematic diagram which shows the example of arrangement | positioning of the inkjet recording head discharge port of this invention. FIG. 2 is a diagram illustrating a configuration of a main part of a recording apparatus for performing recording on a paper surface using the recording head of the present invention. It is a figure which shows typically the number of the ink dots which should cover the recording area by the droplet size in this invention. FIG. 6 is a diagram schematically showing a recording state when recording is performed by high-speed ink ejection in the conventional one-pass recording mode in the present invention. In the present invention, the state of the recording area when a solid image of the same gradation with different recording density is recorded by any one scan in the one-pass recording mode, and the recording position of the recording head, the change in the head temperature, and the discharge amount at that time It is a schematic diagram which shows the relationship. It is a block diagram which shows the control structure of the recording device concerning embodiment of this invention. FIG. 7 according to the embodiment of the present invention is a schematic diagram showing the temperature dependence of the ejection amount when the drive pulse condition is fixed. FIG. 3 is a diagram schematically illustrating the concept of a count area for counting the number of recording dots used in Embodiment 1 of the present invention and a recording area for changing the number of dots of recording data. FIG. 5 is a diagram schematically illustrating a division state of a count area for counting the number of recording dots and a recording area for changing the number of dots of recording data used in the first embodiment of the present invention. 5 is a flowchart illustrating a process of counting the number of dots of print data performed for each scan in Embodiment 1 of the present invention and a process for correcting print data based on the counted result. FIG. 5 is a schematic diagram when a cluster aggregate is detected and an edge of the aggregate is detected for recording data in an arbitrary area within the recording area in the first embodiment of the present invention. It is a figure which shows the state before and behind the change of the recording data in a part of area | region in a recording area in Embodiment 1 of this invention. As another division method of the count area in the present invention, the division state of the print area for changing the count area and the number of dots of print data when the division number and size are set to be different for each scan is schematically described. It is a figure to do. FIG. 6 is a diagram schematically illustrating a count state and a print area division state in which the number of dots of print data is changed when the division size is set to be different in scanning as another count area division method in the present invention. It is. As another division method of the count area in the present invention, the division state of the count area and the print area in which the number of dots of the print data is changed when the boundary position between the count area and the print area is set to be shifted for each scan is schematically shown. FIG. FIG. 5 is a diagram schematically illustrating a division state of a recording area in which the count area and the number of dots of recording data are changed when the count area and the recording area are set to have different sizes in the present invention. FIG. 10 is a schematic diagram when a dot count value for each nozzle is calculated for print data in an arbitrary area of a print area in Embodiment 2 of the present invention. It is a figure which shows the state before and behind the change of the recording data in a part of area | region in the recording area in Embodiment 2 of this invention. FIG. 2 schematically shows an image arrangement image on a paper surface of an image 1 used in Embodiment 1 of the present invention. FIG. It is a figure which illustrates typically the concept of the count area for counting the number of recording dots used in Example 1 of the present invention. FIG. 6 schematically shows an image arrangement image on a paper surface of an image 2 used in Embodiment 2 of the present invention. It is a figure which illustrates typically the concept of the count area for counting the number of recording dots used in Example 2. FIG. It is a figure which shows the state before and behind the change of the recording data in a part of area | region in the recording area in Example 3 of this invention. It is a figure which shows the state before and behind the change of the recording data in a part of area | region in the recording area in Example 4 of this invention.

Explanation of symbols

101 Printhead 102 Ink outlet (nozzle array) of printhead
DESCRIPTION OF SYMBOLS 103 Ink ejection port 104 Ink flow path 105 Ink supply path 201 Inkjet cartridge 202 Recording head 203 Paper feed roller 204 Auxiliary roller 205 Paper feed roller 206 Carriage 600 CPU
601 ROM
602 RAM
603 Image input unit 604 Image signal processing unit 605 Main bus line 606 Operation unit 607 Recovery system control circuit 608 Recovery system motor 609 Cleaning blade 610 Cap 611 Suction pump 612 Thermistor 613 Recording head 614 Head temperature control circuit 615 Head drive control circuit 616 Carriage Drive circuit 617 Paper conveyance control circuit 618 Data conversion unit 619 Data correction unit

Claims (4)

Using a recording head having a plurality of recording element units for ejecting ink, an image is formed and completed based on image data while the recording head scans the recording medium in a direction different from the arrangement direction of the recording elements. In the inkjet recording method,
The scanning area of the recording head is divided into a plurality of count areas and recording areas in the scanning direction, and a counting process for counting the number of recording dots in the counting area, a holding process for holding the counted number of dots, and counting A step of changing the image data in the next recording area according to the number of dots, and a recording method for forming an image by changing the image data in the main scanning direction,
Image data is image data in which the unit of an image expressing gradation is composed of cluster-type area gradations, and a cluster of image data is concentrated (outer peripheral part) when changing the image data An ink jet recording method comprising a step of preferentially changing the process. Using a recording head having a plurality of recording element units for ejecting ink, an image is formed and completed based on image data while the recording head scans the recording medium in a direction different from the arrangement direction of the recording elements. In an inkjet recording apparatus,
The scanning area of the recording head is divided into a plurality of count areas and recording areas in the scanning direction, and counting means for counting the number of recording dots in the count area, holding means for holding the counted number of dots, and counting Means for changing the image data in the next recording area according to the number of dots, and a recording apparatus for forming an image by changing the image data in the main scanning direction,
Image data is image data in which the unit of an image expressing gradation is composed of cluster-type area gradations, and a cluster of image data is concentrated (outer peripheral part) when changing the image data An ink jet recording apparatus comprising means for preferentially changing from the above. The inkjet recording method according to claim 1,
Image data is image data in which the unit of an image expressing gradation is composed of distributed area gradation, and when changing the image data, priority is given to the area where the image data is concentrated (outer peripheral part) An ink jet recording method comprising the step of changing automatically. The inkjet recording apparatus according to claim 2,
Image data is image data in which the unit of an image expressing gradation is composed of distributed area gradation, and when changing the image data, priority is given to the area where the image data is concentrated (outer peripheral part) An ink jet recording apparatus comprising a means for automatically changing.

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