Printing apparatus, control method, and storage medium

Abstract

To complement non-ejection in consideration of a nozzle ejection condition of a recording head without increasing the scale of an electric circuit for complementing non-ejection more than necessary.SOLUTION: According to an aspect of the present invention, there is provided an image processing apparatus including a printhead in which a plurality of nozzle arrays are grouped in advance for each group nozzle array including at least two nozzle arrays, and an array distribution unit configured to execute array distribution processing of distributing print data to the plurality of nozzle arrays, wherein the array distribution unit executes the array distribution processing so as to satisfy a nozzle discharging condition even if allocation of the print data is changed in the same group nozzle array. A non-ejection complementation unit configured to perform non-ejection complementation processing of moving, based on the array distribution unit and non-ejectable nozzle information, print data allocated to a non-ejectable nozzle array including a non-ejectable nozzle so as to be ejected by another nozzle array not including the non-ejectable nozzle, wherein the non-ejectable nozzle array and the other nozzle array belong to a same group nozzle array.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a printing apparatus, a control method, and a program, and more particularly to a technique for complementing non-ejection nozzles in an inkjet printing apparatus, that is, a non-ejection complement technique. [Background technology]

[0002] In full-line single-pass inkjet recording devices, one way to increase the recording speed is to increase the ejection frequency per nozzle. However, in thermal inkjet recording heads, the ink refill time, i.e., the time it takes for ink to be ejected again after it has been ejected from the nozzle, depends on the nozzle structure, ink ejection volume, ink viscosity, etc., and it is difficult to increase the ejection frequency beyond a certain level.

[0003] One way to address this issue is to increase the number of nozzle rows per color without changing the ejection frequency per nozzle, thereby achieving both the ink refill time constraint and faster printing speed.However, as the number of nozzle rows increases, the number of non-ejecting nozzles also increases proportionally, and the amount of data that must be processed also increases, so it is necessary to speed up the non-ejection compensation process.

[0004] Patent Document 1 discloses a method for complementing non-ejection nozzles in a full-line inkjet recording device, taking into account the ejection characteristics of the nozzles. In detail, the complement destination for the non-ejection nozzle is determined by taking into account factors such as the effect of fluid crosstalk between adjacent nozzles and the refill time of the nozzles. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-024144 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the discharge failure compensation method described in Patent Document 1 is applied to a printhead with an increased number of nozzle arrays per color, the following problem arises. Specifically, while the print medium movement speed increases, the ink refill time per nozzle remains almost constant, resulting in a wider discharge interval per nozzle on the paper. This requires a larger search range for nozzles and nozzle arrays to compensate for discharge failures, which increases the amount of computational processing. Furthermore, in on-demand printing, because each printed image is different, it is difficult to perform discharge failure compensation processing in advance. Therefore, software-based discharge failure compensation processing is inappropriate, and hardware (ASIC or FPGA) capable of performing discharge failure compensation in real time and at high speed is often used. In other words, as the number of nozzle arrays per color increases with the speed of printing devices, the amount of computational processing required for discharge failure compensation increases, leading to an increase in the size of the hardware circuitry and ultimately to increased costs.

[0007] In view of the above problems, the present disclosure aims to enable non-discharge complementation that takes into account the nozzle ejection conditions of the recording head without increasing the electrical circuit size or memory capacity for non-discharge complementation more than necessary. [Means for solving the problem]

[0008] One embodiment of the present invention is a recording device comprising: a recording head having a plurality of nozzle arrays, the plurality of nozzle arrays being pre-grouped into group nozzle arrays each including at least two or more nozzle arrays; an array distribution means that performs an array distribution process to distribute recording data to the plurality of nozzle arrays, the array distribution means performing the array distribution process so that nozzle ejection conditions are satisfied even if the allocation of recording data is swapped within the same group nozzle array; and a non-discharge complement means that performs a non-discharge complement process that moves recording data assigned to a non-discharge nozzle array including a non-discharge nozzle so that it is ejected by another nozzle array that does not include the non-discharge nozzle, based on non-discharge nozzle information indicating whether each nozzle is non-dischargeable or not, the non-discharge nozzle array and the other nozzle array belonging to the same group nozzle array. [Effects of the Invention]

[0009] According to the present disclosure, discharge failure complementation can be performed taking into account the nozzle ejection conditions of the print head, without increasing the electrical circuit scale or memory capacity for discharge failure complementation more than necessary. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a recording apparatus; [Figure 2] Block diagram showing the overall system configuration of the recording device [Figure 3] Diagram showing an overview of a recording head [Figure 4] Flowchart of image processing in the first embodiment [Figure 5] A diagram explaining the concept of INDEX expansion processing [Figure 6] Detailed flowchart of complementary column distribution process [Figure 7] Diagram showing nozzle discharge conditions [Figure 8] Diagram for explaining the concept of pair nozzle array setting [Figure 9] A diagram showing the process of distributing nozzle pairs to nozzle arrays [Figure 10] A diagram showing the column allocation results after column allocation of all recorded data is completed. [Figure 11] Detailed flowchart of complementary discharge failure compensation processing [Figure 12] FIG. 10 is a diagram showing a discharge failure compensation priority table. [Figure 13] A diagram showing the results of complementary discharge failure complementation [Figure 14] Flowchart of image processing in the second embodiment [Figure 15] 10 is a detailed flowchart of recovery processing when paired nozzle array discharge failure complementation is unsuccessful in the second embodiment. [Figure 16] FIG. 10 is a diagram for explaining the setting of paired nozzle arrays and the setting of non-discharge complement priority nozzle arrays in the second embodiment; [Figure 17]FIG. 10 is a diagram showing a column distribution result in the second embodiment. [Figure 18] FIG. 11 is a diagram for explaining group nozzle array setting and discharge failure compensation priority nozzle array setting in the third embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0011] [First embodiment] <Configuration of recording device> FIG. 1 is a diagram showing the schematic internal configuration of a full-line inkjet recording apparatus employed in this embodiment. A recording medium P supplied from a recording medium supply unit 101 is conveyed at a predetermined speed in the +X direction while being sandwiched between a pair of conveying rollers 103 and 104, and is then discharged from a discharge unit 102. In the conveying direction (+X direction) of the recording medium P, recording heads 105-108 are arranged between the upstream pair of conveying rollers 103 and the downstream pair of conveying rollers 104, and eject ink in the -Z direction according to recording data. The recording heads 105-108 eject cyan, magenta, yellow, and black ink, each of which is supplied via a tube (not shown). For simplicity, hereinafter, "inkjet recording apparatus" will be abbreviated to "recording apparatus."

[0012] In this embodiment, the recording medium P may be continuous paper held in a roll in the recording medium supply unit 101, or may be cut paper cut into standard sizes in advance. In the case of continuous paper, after the recording operation by the recording heads 105 to 108 is completed, it is cut into predetermined lengths by a cutter 109 and sorted into output trays by size by the output unit 102. The recording control unit 110 controls the overall mechanism of the recording device, including the driving of the recording heads 105 to 108, the conveyance motor for rotating the conveyance roller pairs 103 and 104, the recording medium supply unit 101, and the output unit 102.

[0013] <System configuration> FIG. 2 is a block diagram showing the overall system configuration of the printing apparatus according to this embodiment. The CPU 216 executes programs stored in the ROM 250 and controls the printing control unit 110, which is composed of the ASIC 260 or the general-purpose memory 203, and the entire printing apparatus. The receive buffer 204 receives image data from the host PC 201 via a receive interface (hereinafter, interface will be referred to as "I / F") 202. The general-purpose memory 203 is composed of a portion of a general-purpose memory such as a DRAM and is used as an area for temporarily storing various data. This general-purpose memory does not necessarily need to be a high-speed SRAM; any memory that falls within the category generally referred to as RAM, such as an SRAM, can be used as appropriate. The image processing unit 210 reads the image data received from the receive buffer 204 and performs various image processing operations on the image data, such as rasterization, color separation, and quantization. The image buffer 205 stores the multi-value quantized data for each ink color after quantization processing has been performed on the image data. The print data generation unit 211 reads multi-level quantized data from the image buffer 205 and performs resolution conversion, nozzle array distribution, and other processes. The print buffer 206 holds binary print data distributed to each nozzle array for each color. The non-discharge complement processing unit 212 executes non-discharge complement processing on the print data held in the print buffer 206 while referencing non-discharge nozzle information stored in the non-discharge nozzle information buffer 207 and a non-discharge complement priority table 231. Non-discharge complement processing is a process of transferring print data assigned to a non-discharge nozzle array containing a non-discharge nozzle to another nozzle array capable of normal discharge (i.e., not including a non-discharge nozzle). The printhead control unit 217 reads the binary data for each array that has undergone non-discharge complement processing and drives the print heads 105-108. At this time, the ejection timing generation unit 218 provides the printhead control unit 217 with the transport speed of the print medium P obtained from the encoder 219. The printhead control unit 217 controls the ink ejection and ejection timing from each nozzle based on this information. As a result, ink is ejected from the nozzles corresponding to the designated color ink at the designated timing, forming a desired image on the recording medium.

[0014] <Recording head configuration> FIG. 3 is a diagram showing an overview of the full-line printhead employed in this embodiment. In FIG. 3(a), each circle represents a nozzle, and the letters and numbers inside the circles represent the "nozzle array name" and "nozzle number within the nozzle array," respectively. For example, "A0" means the 0th nozzle in array A. Each of the printheads 105-108 of this embodiment has a total of 16 nozzle arrays, numbered from array A to array P. The same color ink is supplied to the multiple nozzle arrays via ink flow path R. The ink flow paths R are bundled into a common flow path within the printhead, and ink corresponding to the printheads 105-108 is supplied from an ink tank (not shown). Each nozzle is equipped with a pressure generation mechanism (not shown), which generates pressure in response to commands from the printhead control unit 217 to eject ink appropriately. In this embodiment, a thermal type pressure generation mechanism using a heater is employed as the pressure generation mechanism, but various other types of pressure generation mechanisms, such as a piezo type, can also be employed.

[0015] Next, the nozzle layout will be described in detail. The nozzles in each nozzle array are arranged at a 1-pixel pitch (approximately 42 μm intervals) at 600 dpi in the Y direction. For example, the A1 nozzle and the A2 nozzle are spaced 600 dpi apart in the Y direction. Furthermore, the nozzles in arrays A, E, I, and M are arranged at the same position in the Y direction. In contrast, the nozzles in arrays B, F, J, and N are arranged at positions offset by 1 / 4 pixel at 600 dpi in the Y direction. Furthermore, the nozzles in arrays C, G, K, and O are arranged at positions offset by 2 / 4 pixel at 600 dpi in the Y direction. Furthermore, the nozzles in arrays D, H, L, and P are arranged at positions offset by 3 / 4 pixel at 600 dpi in the Y direction. In this embodiment, a printhead having such nozzle arrays is used to print dots at a resolution of 600 dpi in the Y direction for each nozzle array, for a total of 16 nozzle arrays, for a total of 2400 dpi in the Y direction.

[0016] Meanwhile, in the X direction, the nozzles corresponding to numbers 0 to 7 in each nozzle row are arranged in the +X direction at distances equal to the division of 1200 dpi, i.e., 1 / 8 pixel at 1200 dpi, with a stepwise offset. As a result, the 0th and 8th nozzles are offset exactly one pixel at 1200 dpi in the +X direction. For simplicity's sake, only nozzles 0 to 9 are shown in Figure 3(a), but in reality, a large number of nozzles are arranged in the Y direction, corresponding to the width of the recording paper. For nozzles 10 and beyond, the layout shown for nozzles 0 to 9 is repeated in the Y direction.

[0017] FIG. 3B is a diagram illustrating the block division drive performed in this embodiment. The diagram schematically illustrates the relationship between the block division drive timing of each nozzle in column A and the ink droplet landing position. Block division drive is performed by the printhead control unit 217. In this embodiment, ink droplets are ejected at eight divided drive timings. Specifically, the nozzles corresponding to A0, A8, A16, A24, etc. are driven at the latest timing (block 0). The adjacent nozzles A1, A9, A17, A25, etc. are driven at an earlier timing (block 1) by an amount corresponding to the nozzle position offset in the X direction. Similarly, the nozzles corresponding to A7, A15, A23, A31, etc. are driven at the earliest timing (block 7). In this way, ejection is performed by appropriately combining nozzles shifted in the X direction with block division drive. As a result, on the recording medium P, the deviation amount of the nozzle position in the X direction and the deviation amount of the drive timing are offset, and the landing positions of the ink droplets ejected from the nozzles can be aligned to the same position in the X direction.

[0018] <Fluid crosstalk effects> Fluid crosstalk refers to the effect of vibrations from the ejection operation of individual nozzles in a print head on adjacent nozzles that share the same ink supply path. As explained above, block-division drive can shift the ejection timing of adjacent nozzles and distribute simultaneously driven nozzles, thereby reducing the fluid crosstalk effect propagating to adjacent nozzles through the ink flow path R to some extent. However, as printing speeds increase, even block-division drive becomes necessary because the drive interval between adjacent nozzles is very short, resulting in fluid crosstalk effects. For example, if nozzle A0 and nozzle A1 eject with a timing difference of only one block time interval (on the order of microseconds), the crosstalk effect of nozzle A0 (pressure wave due to ejection) will cause fluctuations in the meniscus interface of nozzle A1. As a result, the ejection volume and ejection velocity of ink droplets ejected from nozzle A1 deviate from the desired values. If we assume that the propagation pattern of the pressure wave generated when ink droplets are ejected from the nozzles is spherical, the fluid crosstalk effect attenuates inversely proportional to the distance between the nozzles. In other words, the crosstalk effect is greatest in the first adjacent nozzles, which are closest to each other in the nozzle array, and the crosstalk effect diminishes as the distance to the second and third adjacent nozzles increases. Therefore, when performing dot arrangement and array distribution, measures can be taken to prohibit adjacent nozzles from ejecting to prevent consecutive printing dots between first adjacent nozzles in the same column in the X direction. However, even if such a restriction is adopted to prohibit adjacent nozzle ejection in advance, a situation may arise in which adjacent nozzles are continuously driven when ejection data is transferred from another nozzle array through non-ejection compensation processing. Therefore, there are cases in which the crosstalk effect prevents optimal ejection operation, which poses a problem.

[0019] <Ink refill time> In the thermal print head used in this embodiment, ink refill into the nozzles between the ejection of one ink droplet and the ejection of the next ink droplet is achieved by the capillary force of the nozzle wall and the surface tension of the ink. Therefore, the ink refill time takes several tens of microseconds. When the transport speed of the print medium P is increased, the transport distance in the X direction on the paper surface during the ink refill time (the idle travel distance during which ink cannot be re-ejected due to waiting for ink refill) increases. Therefore, there is a problem in that increasing the speed increases the size of the non-ejection complement circuitry for searching for the nozzle row to complement the non-ejection.

[0020] <Features of this embodiment> 4 is a flowchart showing the processing steps performed by each functional block of the recording control unit 110 in this embodiment. Image processing according to this flowchart is performed by the CPU 216 loading a program stored in the ROM 250 into the general-purpose memory 203, and then executing the loaded program in appropriate cooperation with the ASIC 260, etc. Below, the image processing steps performed by the recording control unit 110, which is a feature of this embodiment, will be described in detail with appropriate reference to the drawings.

[0021] First, in step S101, image input processing is executed. Specifically, image data transmitted from the host PC 201 to the recording device is transferred to the receiving buffer 204 via the receiving I / F 202, and the transferred image data is input to the image processing unit 210. Note that, hereinafter, the image data input to the image processing unit 210 will be described as having an image resolution of 600 dpi x 600 dpi and an image data format of RGB 3 plane 8 bit (256 gradations). However, this image data is an example and is not limited to this format. Also, hereinafter, for simplicity, "step S~" will be abbreviated to "S~".

[0022] In S102, ink color separation processing is performed on the image data input in S101. Specifically, the image processing unit 210 converts the RGB 3-plane 8-bit image data into CMYK 4-plane 8-bit image data by referring to a color separation table (not shown) stored in the ROM 250.

[0023] In S103, quantization processing is performed on the image data acquired in S102. Specifically, the image processing unit 210 performs quantization (reduction of gradation) processing to convert CMYK 4-plane 8-bit (256 gradations) image data into 2-bit (3 gradations) data. Here, a dithering method is used as the quantization method, but an error diffusion method or the like can also be used. When the quantization processing by the image processing unit 210 in this step is completed, the CMYK 2-bit (3 gradations) data is transferred to the general-purpose memory 203 and stored in the image buffer 205 within the general-purpose memory 203.

[0024] In S104, an INDEX expansion process is performed on the quantized data stored in the image buffer 205 in S103. Specifically, the recording data generation unit 211 performs the INDEX expansion process on the quantized data stored in the image buffer 205 while referring to the INDEX expansion table stored in the ROM 250.

[0025] FIG. 5 is a conceptual diagram for explaining the INDEX expansion process. The INDEX expansion process is a process for converting resolution, determining the number of print dots, and determining the print dot arrangement. In FIG. 5(a), quantized data 400, quantized data 401, and quantized data 402 each represent quantized data of 1 pixel in the X direction by 1 pixel in the Y direction at 600 dpi. The numbers in the rectangles indicate the quantization levels, with the quantization level of quantized data 400 being 0, the quantization level of quantized data 401 being 1, and the quantization level of quantized data 402 being 2.

[0026] Next, INDEX expansion table 403, INDEX expansion table 404, and INDEX expansion table 405 each represent an INDEX expansion table stored in ROM 250, and are tables of 2 pixels in the X direction by 2 pixels in the Y direction at 1200 dpi. In these tables, a white-filled square represents 0-dot printing (non-ejection), and a black-filled square represents 1-dot printing (ejection). In other words, it can be seen that quantized data 400 with quantization level 0 is INDEX-expanded to 0 dots in a table of 2 pixels in the X direction by 2 pixels in the Y direction. Similarly, quantized data 401 with quantization level 1 is INDEX-expanded to 1 dot, and quantized data 402 with quantization level 2 is INDEX-expanded to 2 dots.

[0027] In addition to the number of dots described above, the dot arrangement in 1200 dpi units is also determined at the same time by applying an INDEX expansion table. In this embodiment, the dot arrangement of INDEX expansion table 405 (quantization level 2) is a table that includes the lower levels, INDEX expansion table 404 (quantization level 1) and INDEX expansion table 403 (quantization level 0). Therefore, if a column distribution table that can distribute the dot arrangement of INDEX expansion table 405 (quantization level 2) is prepared, it is possible to distribute the lower levels using the same column distribution table.

[0028] FIG. 5(b) is an example of quantized data of 16 pixels in the X direction and 4 pixels in the Y direction, read out from the image buffer 205 by the print data generation unit 211. FIG. 5(c) is data after the print data generation unit 211 has performed INDEX expansion processing on the quantized data of FIG. 5(b). From FIG. 5(c), it can be seen that a pixel group of 32 pixels in the X direction and 8 pixels in the Y direction at 1200 dpi has been expanded into two values: ejection / non-ejection. For the sake of future explanation, the 1200 dpi pixels will be explained by adding coordinates such as (X0, Y0) to (X7, Y31) with the upper left corner as the origin.

[0029] Returning to the explanation of the flowchart in Fig. 4, in S105, a complementary column allocation process is performed on the data that has been subjected to the INDEX expansion process in S104. Specifically, the recording data generation unit 211 performs the complementary column allocation process on the data after INDEX expansion, while referring to the column allocation table stored in ROM 250.

[0030] The complementary column allocation process will now be described with reference to Fig. 6. Fig. 6 is a flowchart showing the subroutine of the complementary column allocation process in S105.

[0031] First, in S105-1, the conditions relating to nozzles that can eject (referred to as nozzle ejection conditions) are read from the ROM 250.

[0032] Here, the nozzle discharge conditions will be explained using Fig. 7. Fig. 7 is a diagram showing an overview of the nozzle discharge conditions in this embodiment. The table in Fig. 7(a) lists the refill time constraint, adjacent crosstalk constraint, unit, and number of pixels as items that define the nozzle discharge conditions.

[0033] The refill time constraint is 7 pixels at 1200 dpi. This means that after a nozzle ejects one dot of ink droplet, it takes the time equivalent to 7 pixels at 1200 dpi for that nozzle to be refilled with ink, and during that time, no ink droplets can be ejected from that nozzle.

[0034] Next, the adjacent nozzle crosstalk constraint is one pixel at 600 dpi. This constraint prevents adjacent nozzles from ejecting ink droplets at close timing to the nozzle in question, since crosstalk can cause the ejection volume or ejection speed of the adjacent nozzle to deviate from the specified value when a nozzle ejects one dot of ink. To prevent this, the adjacent nozzles cannot eject ink droplets at similar timing. Figure 7(b) conceptually illustrates the nozzle ejection conditions defined by the refill time constraint and the adjacent nozzle crosstalk constraint. Here, it is assumed that print data exists at coordinates (X13, Y3) and is ejected by any nozzle in any column. The upward-pointing triangle mark in the frame represents the area where print data cannot be added for ejection by the nozzle in question due to the refill time constraint. This area is seven pixels in the +X direction and seven pixels in the -X direction at 1200 dpi. Next, the downward-facing triangle mark in the frame represents the area where, due to the adjacent nozzle crosstalk constraint, it is not possible to add print data for ejection by the two adjacent nozzles on either side of the nozzle in question; at 600 dpi, this is an area of ​​one pixel in the +Y direction and an area of ​​one pixel in the -Y direction.

[0035] Note that, although this embodiment has shown a configuration in which the nozzle ejection conditions are defined by both the refill time constraint and the adjacent nozzle crosstalk constraint, this is not limiting and this embodiment can also be applied to a configuration in which the nozzle ejection conditions are defined by at least one of the refill time constraint and the adjacent nozzle crosstalk constraint.

[0036] Returning to the explanation of Figure 6, in S105-2, the settings of the paired nozzle arrays are read. The concept of paired nozzle arrays will now be explained using Figure 8. The concept of paired nozzle arrays is that two nozzle arrays are treated as one group, and when a nozzle in one nozzle array fails to eject, the nozzle in the other nozzle array in that group compensates for the ejection failure. Figure 8 shows a list of paired nozzle array settings in this embodiment.

[0037] 8, for example, paired nozzle array 0 is made up of array A and array I. This means that when array A fails to eject, non-ejection complement is carried out using array I, and when array I fails to eject, non-ejection complement is carried out using array A. In this embodiment, there are a total of 16 nozzle arrays per color, and so they are divided into eight groups, numbered 0 to 7.

[0038] Returning to the explanation of Figure 6, in step S105-3, the target paired nozzle array is initialized. "Initializing the target paired nozzle array" in this step means that when distributing the print data after INDEX expansion to each nozzle array, the process starts from paired nozzle array 0 (array A, row I).

[0039] In S105-4, the INDEX-expanded data is read. Note that, for simplicity, the following description will be given using as an example a case in which data obtained by INDEX-expanding quantized data in which all pixels have quantization level 2 as described in FIG. 5C is read (hereinafter referred to as this case). However, this does not mean that the present embodiment is limited to this case. If quantization level 2 data can be expanded to each nozzle array, there will be no print duty that exceeds that, so this is sufficient as an assumption of the print duty that should be considered.

[0040] In S105-5, the coordinates of interest are initialized. "Initializing the coordinates of interest" in this step means that when the print data after INDEX expansion is distributed to each nozzle array, the coordinates of interest start from (X0, Y0).

[0041] In S105-6, it is determined whether unassigned data exists at the target coordinates. If the determination result in this step is Yes, proceed to S105-7; if the determination result is No, proceed to S105-10. Figure 9 conceptually illustrates the process of column allocation to paired nozzle arrays. Figure 9(a) is a re-explanation of the data obtained by index-expanding the quantized data in which all pixels are at quantization level 2, as described in Figure 5(c). When the index-expanded data shown in Figure 9(a) is checked for the presence or absence of data at the target coordinates (X0, Y0), it is found that data to be printed exists. At this time, this print data has not yet been assigned to any nozzle array. Therefore, the determination result in this step is Yes (S105-6 Yes → S105-7).

[0042] In S105-7, it is determined whether the recording data of interest satisfies the conditions for canceling the refill time constraint. If the determination result in this step is Yes, proceed to S105-8, and if the determination result is No, proceed to S105-11. In this case, the recording data has not yet been assigned to any column, so the determination result in this step is Yes (S105-7 Yes → S105-8).

[0043] In S105-8, it is determined whether the print data of interest satisfies the conditions for removing the adjacent nozzle crosstalk constraint within the same column. If the determination result in this step is Yes, proceed to S105-9, and if the determination result is No, proceed to S105-11. Note that in this case, the print data has not yet been assigned to any column, so the determination result in this step is Yes (S105-8 Yes → S105-9).

[0044] In S105-9, the paired nozzle array that was not previously selected is assigned to the print data of interest. In this case, since the print data has not yet been assigned to any array, nozzle array 1 (array A) of paired nozzle array group 0 is assigned.

[0045] Figure 9(b) shows the column allocation results after executing steps S105-6 to S105-9 only once. Figure 9(b) shows that the print data at coordinates (X0, Y0) is assigned to column A. As mentioned above, the upward-pointing triangle mark and downward-pointing triangle mark represent the refill time constraint and adjacent nozzle crosstalk constraint that define the nozzle ejection conditions. In other words, column A cannot be assigned to the print data at the positions of these marks.

[0046] Returning to the explanation of Fig. 6, in S105-10, it is determined whether the coordinate of interest has reached the maximum value in the X direction of the column distribution table. If the determination result in this step is Yes, the process proceeds to S105-12, and if the determination result is No, the process proceeds to S105-11. Note that in this embodiment, the size of the column distribution table is X = 32 pixels and Y = 8 pixels in 1200 dpi units, and in this case, the determination result in this step is No (S105-10 NO → S105-11).

[0047] In S105-11, the coordinate of interest is incremented in the X direction. In this case, the coordinate of interest becomes coordinate (X1, Y0). The process returns to S105-6, where it is determined whether an unassigned recording dot exists at the coordinate of interest (X1, Y0), and it is determined that there is no unassigned recording dot (S105-6 NO). Then, the process proceeds from S105-10 NO to S105-11, and in S105-11, the coordinate of interest is incremented in the X direction, and the coordinate of interest becomes coordinate (X2, Y0). Then, the process returns to S105-6, where it is determined whether a recording dot exists at the coordinate of interest (X2, Y0), and it is determined that there is a recording dot (S105-6 Yes). Then, in S105-7, it is determined whether the recording data of interest satisfies the condition for releasing the refill time constraint. In this case, the condition for releasing the refill time constraint for row A will not be satisfied until the coordinate of interest reaches coordinates (X8, Y0), so the result of the determination in S105-7 here is No (S105-7 NO → S105-11). Since the loop process is repeated from here on, the explanation of the steps will be omitted, and it will be assumed that the coordinate of interest reaches coordinates (X8, Y0) as a result of the loop process. At this time, the determination results in each determination step from S105-6 to S105-8 are all Yes. Therefore, in S105-9, the row of the paired nozzle array that was not previously selected is assigned to the print data of interest. Since nozzle array 1 (row A) of paired nozzle array group 0 was assigned to the previous print dot (X0, Y0), nozzle array 2 (row I) of paired nozzle array group 0 is assigned to the current print dot (X8, Y0). Figure 9(c) shows the intermediate progress of column allocation performed until the target coordinates become (X31, Y0) by continuing the loop in complementary column allocation S105 in Figure 6. Figure 9(c) shows that nozzle column 1 (column A) and nozzle column 2 (column I) of paired nozzle column 0 are alternately arranged.

[0048] Returning to the explanation of FIG. 6, processing resumes from S105-10, which follows S105-9 in the present case described above. Because the coordinate of interest has reached coordinate (X31, Y0), the determination result of S105-10 is Yes. In this case, in S105-12, the CPU 216 determines whether the coordinate of interest has reached the maximum value in the Y direction of the column allocation table. In this case, the determination result of this step is No. Therefore, in S105-13, the coordinate of interest is incremented in the Y direction, and processing returns to S105-6. At coordinates of interest (X0, Y1) to (X31, Y1), there are unassigned printing dots, but there are no nozzles in paired nozzle array group 0 (row A, row I). This is because, in this embodiment, the nozzle resolution within a nozzle array is 600 dpi, and therefore, there are no nozzles of the same group in adjacent pixels spaced 1200 dpi apart in the Y direction. Therefore, according to the flowchart of S105, the loop processing continues until the coordinate of interest becomes coordinate (X0, Y2). When the coordinate of interest becomes coordinate (X0, Y2), the determination results of S-105-6 and S-105-7 are Yes, but in S-105-8 it is determined that the condition for removing the adjacent nozzle crosstalk constraint is not met. Referring to FIG. 9C, because there is a downward-pointing triangle mark at coordinate (X0, Y2), allocation to column A is not possible. Then, according to the flowchart of S105, the loop processing continues until the coordinate of interest becomes coordinate (X2, Y2). Since the previous printing dot (X24, Y0) was assigned to nozzle column 2 (column I) of paired nozzle array group 0, the current printing dot (X2, Y2) is assigned to nozzle column 1 (column A) of paired nozzle array group 0. FIG. 9D shows the progress of the column allocation process proceeding through the flow of S105 until the coordinate of interest becomes coordinate (X31, Y7). From FIG. 9(d), it can be seen that of the recording dots in the INDEX expansion result shown in FIG. 9(a), 16 recording dots are assigned to paired nozzle array group 0 (arrays A and I).

[0049] FIG. 10 shows the column distribution result after completing the column distribution of all print data by proceeding through the flow of S105 in the same manner as described above. This column distribution has the following characteristics. First, the nozzle discharge conditions (defined by the adjacent nozzle crosstalk constraint and the refill time constraint) described above are satisfied for all nozzles assigned to print dots. Second, between two nozzle arrays belonging to a paired nozzle array group, print dot data to be printed by one nozzle array can be exchanged so that it is printed by the other nozzle array. This type of column distribution is defined as "complementary column distribution" or sometimes referred to as "complementary column distribution." The binary data after column distribution, which has been subjected to complementary column distribution by the print data generation unit 211 (see FIG. 2), is stored in the print buffer 206. While this embodiment describes a configuration in which the column distribution table is generated by the print data generation unit 211 in the ASIC 260, another configuration is also possible in which the column distribution table 230 is generated externally in advance, stored in the ROM 250, and read out as needed.

[0050] Returning to the explanation of Figure 4, after the complementary column distribution process is completed in S105, complementary discharge failure complement process is executed in S106. The complementary discharge failure complement process will now be explained using Figure 11. Figure 11 is a flowchart showing the subroutine of the complementary discharge failure complement process in S106.

[0051] First, in S106-1, non-discharge nozzle information indicating whether each nozzle in each of the multiple nozzle arrays is non-dischargeable is read. Specifically, the non-discharge complement processing unit 212 (see FIG. 2) reads the non-discharge nozzle information from the non-discharge nozzle information buffer 207. The non-discharge nozzle information buffer 207 stores non-discharge nozzle information for the print heads 105 to 108 obtained by non-discharge detection means (not shown in FIG. 2). In this step, the CPU 216 or ASIC 260 functions as non-discharge nozzle information acquisition means.

[0052] In S106-2, the print dot data is read in. Specifically, the discharge failure complement processing unit 212 reads the column-distributed binary data from the print buffer 206 as the print dot data.

[0053] In S106-3, paired nozzle array setting information is read. Specifically, the discharge failure complement processing unit 212 reads the discharge failure complement priority table 231 stored in the ROM 250 as the paired nozzle array setting information. FIG. 12 is an example of the discharge failure complement priority table read in this step. As shown in FIG. 12, a discharge failure complement priority nozzle array is defined for each nozzle array. When compared with the paired nozzle array setting in FIG. 8, it can be seen that, in the nozzle arrays constituting the paired nozzles, one nozzle array sets the other nozzle array as the discharge failure complement priority nozzle array. This type of discharge failure complement is defined as "complementary discharge failure complement."

[0054] In S106-4, the print dot data read in S106-2 is used to determine whether one of the paired nozzle arrays to which the print dots are assigned is a non-discharge nozzle. If the determination result in this step is Yes, proceed to S106-5; if the determination result is No, the series of processes ends.

[0055] In S106-5, the discharge failure complement processing unit 212 (see FIG. 2) executes discharge failure complement processing, and print data from one of the paired nozzle arrays that has been determined to be discharge failure is moved to the other nozzle array.

[0056] Figure 13 shows an example of the results of complementary discharge failure complementation in this embodiment. Fig. 13(a) shows only columns A and I of paired nozzle array group 0 for ease of explanation, regarding the results of complementary discharge failure complementation being performed on binary data after column distribution. It can be seen that as a result of nozzle A0 and nozzle I1 failing to eject, the A0 nozzle is complemented by nozzle I0, and the I1 nozzle is complemented by nozzle A1. Fig. 13(b) shows all nozzle arrays as a result of completing complementary discharge failure complementation on binary data after column distribution.

[0057] <Effects of this embodiment> As explained above, in this embodiment, complementary discharge failure complementation is performed on binary data that has been subjected to complementary column distribution. As a result, even if one of a pair of nozzles fails to discharge, discharge failure complementation can be performed while maintaining a state in which the nozzle discharge conditions are met for all recording dots (i.e., there are no adjacent nozzle crosstalk constraints or refill time constraints). Therefore, discharge failure complementation that takes into account the nozzle discharge characteristics can be performed without increasing the electrical circuitry or memory capacity for discharge failure complement more than necessary.

[0058] [Second embodiment] In this embodiment, we will deal with the case where two nozzles in a paired nozzle array fail to eject at the same time. For ease of explanation, referring to S106-5 of the complementary ejection failure complement process in the first embodiment (see FIG. 11), if both nozzles in a paired nozzle array for a given Y pixel fail to eject, ejection failure complement cannot be performed for that Y pixel alone. In such a case, the first embodiment has the problem that data that should have been printed by both nozzle arrays will be lost.

[0059] Therefore, in this embodiment, when two nozzles in a paired nozzle array fail to eject at the same time, the paired nozzle array setting table, array distribution table, and ejection failure complement priority table are rewritten, thereby enabling ejection failure complement without data loss. Note that, in the following, to avoid duplication of explanation, only the differences from the first embodiment will be explained.

[0060] 14 is a flowchart of image processing in this embodiment. Image processing according to this flowchart is performed by the CPU 216 loading a program stored in the ROM 250 into the general-purpose memory 203, and then executing the loaded program in appropriate cooperation with the ASIC 260, etc. The difference between this embodiment and the first embodiment is that in S201, recovery processing is executed when paired nozzle array discharge failure complementation cannot be performed (defined as paired nozzle array discharge failure complementation NG recovery processing).

[0061] FIG. 15 is a flowchart showing a subroutine of the recovery process (S201 in FIG. 14) when paired nozzle array discharge failure complementation is NG, for making it possible to carry out discharge failure complementation processing that is not possible to carry out.

[0062] First, in S201-1, the pair nozzle array setting is read in. This step is the same as S105-2 (see FIG. 6) in the first embodiment.

[0063] In S201-2, non-discharge nozzle information is read in. This step is the same as S106-1 in the first embodiment (see FIG. 11).

[0064] In S201-3, it is determined whether there are any Y pixels where both nozzles in the paired nozzle array are non-ejecting nozzles. If the determination result in this step is Yes, the process proceeds to S201-4. On the other hand, if the determination result in this step is No, the series of processes ends. In this case, the subsequent processes are the same as in the first embodiment. At the stage when the determination in this step is made, the relationship between the pixels (Y0, Y1, Y2, etc.) with a resolution of 1200 dpi in the Y direction and the nozzle numbers (A0, B0, E0, F0, etc.) is known. Therefore, by combining the information obtained up to this point, it is possible to check whether there are any Y pixels that meet the conditions in this step.

[0065] In S201-4, candidates for rewriting the paired nozzle array setting are determined. FIG. 16 is an explanatory diagram of the paired nozzle array setting and the non-discharge complement priority nozzle array setting in this embodiment. FIG. 16(a) shows the paired nozzle setting before rewriting. For example, as shown in FIG. 16(a), consider the case where, at the Y0 pixel, rows A and I are non-discharge, and there are no non-discharges at the other Y pixels. Note that the white characters in FIG. 16(a) represent non-discharge nozzle arrays.

[0066] Figure 16(b) also shows the non-discharge complement priority nozzle array before rewriting. As with Figure 16(a), this shows that non-discharge complement priority nozzle arrays A and I are non-discharge, and therefore non-discharge complement is not possible. As candidates for rewriting the paired nozzle array of array A, it is desirable to have arrays whose nozzle array arrangement is not misaligned in the Y direction, i.e., arrays E, I, and M. This is because, when non-discharge complement is performed, it is desirable to minimize the deviation in the impact position of ink droplets in the Y direction compared to before non-discharge complement. However, in this case, array I is non-discharge, and therefore cannot be selected as a candidate for rewriting the paired nozzle array of array A, so array E is selected here as a candidate. Next, as candidates for rewriting the paired nozzle candidate of array I, it is desirable to have arrays A, E, and M whose nozzle array arrangement is similarly not misaligned in the Y direction. However, in this case, array A is non-discharge, and array E has already been selected as the paired nozzle candidate for array A, so array M is selected as a candidate. It is possible that other nozzle arrays that are not misaligned in the Y direction are also non-ejecting and cannot be selected as candidates for rewriting paired nozzles, but in that case it is possible to select a nozzle array that is misaligned by 2400 dpi in the Y direction as a candidate. The reason for this is that misalignment of the ink droplets is more acceptable than being unable to perform non-ejection complement and losing data that should be printed.

[0067] Returning to the explanation of Figure 15, in S201-5, the paired nozzle array setting table and the discharge failure complement priority table are rewritten. Figures 16(c) and 16(d) show examples of the rewriting results of this step, with Figure 16(c) showing the paired nozzle array setting table after rewriting and Figure 16(d) showing the discharge failure complement priority table after rewriting. Referring to Figure 16(c), it can be seen that paired nozzle array 0 has been rewritten to a combination of arrays A and E, and paired nozzle array 4 has been rewritten to a combination of arrays I and M. Referring also to Figure 16(d), it can be seen that the discharge failure complement priority table has been rewritten in a similar manner.

[0068] As shown in Figures 16(a) to (d), in this embodiment, when changing the pair nozzle settings (i.e., grouping settings), priority is given to selecting nozzle rows that have as little positional deviation as possible in the Y direction as a combination of nozzle rows that belong to a certain pair nozzle.

[0069] In S201-6, the column distribution table is rewritten. The reason for rewriting in this step is that when the paired nozzle array setting is changed, it is necessary to rewrite the column distribution table accordingly. The column distribution table may be rewritten using a table recalculated by the CPU 216 or ASIC 260 in accordance with the complementary column distribution flow described in the first embodiment (see FIG. 6). Alternatively, a method may be used in which a plurality of combinations of column distribution tables are stored in advance in the ROM 250, and a column distribution table that matches the changed paired nozzle setting is selected from these.

[0070] After S201-6, the process proceeds to S105 (see FIG. 14). In S105, complementary column allocation processing is executed. FIG. 17 shows an example in which the complementary column allocation processing of this step is executed based on the rewritten pair nozzle array setting shown in FIG. 16(c).

[0071] In S106, complementary ejection failure complementation processing is performed. Prior to performing the complementary ejection failure complementation processing of this step, the paired nozzle array setting table, array distribution table, and ejection failure complementation priority table were rewritten by the recovery processing of S201. Therefore, by performing processing similar to that of the first embodiment from this step onwards, ejection failure complementation of paired nozzle arrays can be performed.

[0072] As explained above, in this embodiment, when two nozzles in a paired nozzle array simultaneously fail to eject, the paired nozzle array setting table, array distribution table, and ejection failure complement priority table are rewritten, thereby enabling ejection failure complement without data loss.

[0073] [Third embodiment] In this embodiment, a group nozzle array will be described as an expanded concept of the pair nozzle array. Note that, in the following, to avoid duplication of explanation, only the differences from the previous embodiment will be described.

[0074] FIG. 18 is an explanatory diagram of group nozzle array setting and discharge failure compensation priority setting in this embodiment. FIG. 18(a) is an example of group nozzle array setting. As shown in the figure, 16 nozzle arrays (arrays A to P) in this example are grouped into four groups (group nozzle arrays 0 to 3). Each of these group nozzle arrays consists of four nozzle arrays (nozzle arrays 1 to 4). Nozzle arrays 1 to 4 belonging to the same group nozzle array are nozzle arrays with no deviation in nozzle position in the Y direction, as shown in FIG. 3(a). The array distribution process is performed so that the nozzle discharge conditions are met even if the allocation of print data is swapped within the same group nozzle array.

[0075] 18(b) is an example of non-discharge complement priority setting. As shown in the figure, the non-discharge complement priority nozzles in row A are row E, the non-discharge complement priority nozzles in row E are row I, the non-discharge complement priority nozzles in row I are row M, and the non-discharge complement priority nozzles in row M are row A, so there is a relationship in which the non-discharge complement priority nozzles are referenced in a circular manner.

[0076] Although the nozzle array grouping has been described in the above embodiment, in which one group is defined to include four nozzle arrays, the present invention is not limited to this embodiment. This embodiment can be applied to a group of nozzle arrays that includes at least N, where N is equal to or greater than two, nozzle arrays.

[0077] As described above, according to this embodiment, the complementary array distribution and complementary ejection failure complementation can achieve similar effects not only for the pair nozzle arrays (two nozzle arrays) described in the first and second embodiments, but also for group nozzle arrays (N nozzle arrays (N≧2)).

[0078] [Other embodiments] The present disclosure can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0079] Furthermore, the techniques described in the above embodiments may be combined as appropriate.

[0080] [Technical Features of the Disclosure] The present disclosure includes the following configurations.

[0081] <Configuration 1> A recording device comprising: a recording head having a plurality of nozzle arrays, the plurality of nozzle arrays being pre-grouped into group nozzle arrays each including at least two or more nozzle arrays; an array distribution means that performs an array distribution process to distribute recording data to the plurality of nozzle arrays, the array distribution means performing the array distribution process so that nozzle ejection conditions are satisfied even if the allocation of recording data is swapped within the same group nozzle array; and a non-discharge complementation means that performs a non-discharge complementation process that moves recording data assigned to a non-discharge nozzle array including a non-discharge nozzle so that it is ejected by another nozzle array that does not include the non-discharge nozzle, based on non-discharge nozzle information indicating whether each nozzle is non-dischargeable or not, the non-discharge nozzle array and the other nozzle array belonging to the same group nozzle array. <Configuration 2> The recording device according to Configuration 1, further comprising a non-discharge nozzle information acquisition means for acquiring the non-discharge nozzle information, and the non-discharge complement means executes the non-discharge complement process based on the non-discharge nozzle information acquired by the non-discharge nozzle information acquisition means. <Configuration 3> A recording device according to configuration 1 or 2, characterized in that the nozzle ejection conditions are defined by at least one of a first constraint based on the time it takes for the nozzles to be refilled with ink, and a second constraint for suppressing deviation of the ejection volume or ejection speed from a predetermined value due to the influence of fluid crosstalk between adjacent nozzles. <Configuration 4> A recording device according to any one of configurations 1 to 3, further comprising recovery means for, when the non-discharge complement process cannot be executed based on the non-discharge nozzle information acquired by the non-discharge nozzle information acquisition means and the grouped group nozzle arrays, changing the combination of nozzle arrays and changing the grouping settings, thereby making it possible to execute the non-discharge complement process. <Configuration 5> The recording device described in any one of Configurations 1 to 4, wherein the plurality of nozzle rows are arranged with a predetermined amount of misalignment, and when changing the grouping settings, the recovery means preferentially selects nozzle rows with a small amount of misalignment as a combination of nozzle rows belonging to the same group of nozzle rows. <Configuration 6> The recording apparatus according to any one of configurations 1 to 5, wherein the group nozzle array is a pair nozzle array. <Configuration 7> The recording apparatus according to any one of Configurations 1 to 6, wherein each of the plurality of nozzle rows has a plurality of nozzles for ejecting ink. <Control Method> A control method for a recording device having a recording head having a plurality of nozzle arrays, the plurality of nozzle arrays being grouped in advance into group nozzle arrays each including at least two or more nozzle arrays, the control method comprising: a column distribution step of executing a column distribution process to distribute recording data to the plurality of nozzle arrays, the column distribution process being executed so that nozzle ejection conditions are satisfied even if the allocation of recording data is swapped within the same group of nozzle arrays; and a non-discharge complement step of executing a non-discharge complement process of moving recording data assigned to a non-discharge nozzle array including a non-discharge nozzle so that it is ejected by another nozzle array not including the non-discharge nozzle, based on non-discharge nozzle information indicating whether each nozzle is non-dischargeable or not, the non-discharge nozzle array and the other nozzle arrays belonging to the same group of nozzle arrays. <Program> A program for causing a computer to execute a control method for a recording device having a recording head having a plurality of nozzle arrays, the plurality of nozzle arrays being grouped in advance into group nozzle arrays each including at least two or more nozzle arrays, the control method comprising: a column distribution step of executing a column distribution process to distribute recording data to the plurality of nozzle arrays, the column distribution process being executed so that nozzle ejection conditions are satisfied even if assignment of recording data is swapped within the same group nozzle array; and a non-discharge complement step of executing a non-discharge complement process of moving recording data assigned to a non-discharge nozzle array including a non-discharge nozzle so that it is ejected by another nozzle array not including the non-discharge nozzle, based on non-discharge nozzle information indicating whether each nozzle is non-dischargeable or not, the non-discharge nozzle array and the other nozzle array belonging to the same group nozzle array. [Explanation of symbols]

[0082] 105 Recording head 110 Recording control section 212 Non-discharge complement processing section 216 CPU 260 ASIC

Claims

1. a print head having a plurality of nozzle arrays, the plurality of nozzle arrays being grouped in advance into groups each including at least two nozzle arrays; an array distribution unit that executes an array distribution process for distributing print data to the plurality of nozzle arrays, the array distribution unit executing the array distribution process so that nozzle ejection conditions are satisfied even when the allocation of print data is swapped within the same group of nozzle arrays; a non-discharge complementing means for executing a non-discharge complementing process that moves recording data assigned to a non-discharge nozzle array including a non-discharge nozzle so that it is ejected by another nozzle array that does not include the non-discharge nozzle, based on non-discharge nozzle information indicating whether each nozzle is non-dischargeable or not, the non-discharge nozzle array and the other nozzle array belonging to the same group of nozzle arrays; having A recording device characterized by:

2. a non-ejection nozzle information acquisition means for acquiring the non-ejection nozzle information, the discharge failure complement means executes the discharge failure complement process based on the discharge failure nozzle information acquired by the discharge failure nozzle information acquisition means.

2. The recording apparatus according to claim 1, wherein the recording apparatus is a recording medium.

3. the nozzle ejection condition is defined by at least one of a first constraint based on the time until the nozzle is refilled with ink, and a second constraint for suppressing deviation of the ejection amount or ejection speed from a predetermined value due to the influence of fluid crosstalk between adjacent nozzles; 3. The recording apparatus according to claim 2.

4. further comprising recovery means for, when the discharge failure complement process cannot be executed based on the discharge failure nozzle information acquired by the discharge failure nozzle information acquisition means and the grouped group nozzle arrays, changing the combination of nozzle arrays to change the grouping settings, thereby making it possible to execute the discharge failure complement process; 4. The recording apparatus according to claim 2 or 3.

5. The plurality of nozzle rows are arranged with a predetermined amount of offset in position, when changing the grouping settings, the recovery means preferentially selects nozzle rows with small positional deviation as a combination of nozzle rows belonging to the same group of nozzle rows; 5. The recording apparatus according to claim 4.

6. the group nozzle array is a pair nozzle array, 6. The recording apparatus according to claim 5.

7. each of the plurality of nozzle rows has a plurality of nozzles for ejecting ink; 7. The recording apparatus according to claim 6.

8. A method for controlling a recording apparatus having a recording head having a plurality of nozzle arrays, the plurality of nozzle arrays being grouped in advance into groups each including at least two nozzle arrays, the method comprising: a column distribution step of executing a column distribution process for distributing print data to the plurality of nozzle columns, the column distribution process being executed so that nozzle ejection conditions are satisfied even when the allocation of print data is swapped within the same group of nozzle columns; a non-discharge complement step of performing a non-discharge complement process of moving recording data assigned to a non-discharge nozzle array including a non-discharge nozzle so that the recording data is ejected by another nozzle array not including the non-discharge nozzle, based on non-discharge nozzle information indicating whether each nozzle is non-dischargeable or not, wherein the non-discharge nozzle array and the other nozzle array belong to the same group of nozzle arrays; having A control method comprising:

9. A program for causing a computer to execute the method according to claim 8.

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