Image processing device, image processing method, and program

Abstract

To provide a technique that can obtain a high-quality image, without enhancing accuracy in arranging a chip in a recording head.SOLUTION: A first chip having a first nozzle row N10 and a second chip having a second nozzle row N20 are arranged in a recording head. Overlapping parts overlapping in a second direction (y) which is orthogonal to a first direction (w) are formed in areas of respective end part sides of the first and second nozzle rows. Image processing means comprises allocating means that allocates recording data to respective nozzles of the first and the second nozzle rows, on a basis of a distance between the nozzles. The allocating means performs shift processing for shifting positions where the recording data are allocated to the nozzles, from positions where the recording data are allocated thereto when the distance between the nozzles is equal to a standard distance, and changes distribution processing for distributing the recording data to the nozzles positioned at the overlapping positions, in accordance with the distance between the nozzles.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention uses a recording head in which multiple chips are arranged. Notes The present invention relates to an image processing device, an image processing method, and a program used for recording operations. [Background technology]

[0002] Currently, inkjet printing devices are known to be equipped with so-called "tethered heads," in which multiple chips with nozzle arrays that eject ink are arranged in a predetermined direction. The multiple chips in a tethered head are typically arranged so that the nozzle arrays of adjacent chips partially overlap. In the overlapping portions OL of these nozzle arrays, variations in nozzle spacing can occur due to alignment errors between adjacent chips, resulting in misalignment of the relative positions of dots formed on the printing medium. In such cases, streaky density variations occur in the areas printed by the overlapping portions OL, resulting in reduced image quality. Therefore, high-precision chip installation is required, but this requires high-precision manufacturing equipment, which incurs enormous costs. Therefore, a technology is needed that can suppress image quality degradation in the overlapping portions OL without increasing chip installation precision.

[0003] Patent document 1 discloses a technology for reducing the visibility of density streaks at the joints of heads, in which the pattern printed at the joint is analyzed to detect the spacing between the heads, and the input image signal is corrected before being input to the printing element based on the results. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-122546 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology of Patent Document 1 mentioned above has a problem in that it cannot properly correct image data printed by the joint portion when there is a misalignment between adjacent chips that is greater than the nozzle resolution (nozzle spacing). For example, if the spacing between chips is shifted in the direction of separation, dots are printed only by either the end nozzles of the first nozzle row or the end nozzles of the second nozzle row located in the overlapping portion OL, which may result in white stripes. Furthermore, if the spacing between chips is shifted in the direction of separation, there is a possibility that some of the end nozzles of the first nozzle row or the end nozzles of the second nozzle row in the overlapping portion OL may apply ink to the same area on the printing medium in an overlapping manner, which may result in black stripes.

[0006] In view of the above-mentioned problems, an object of the present invention is to provide a technique that can obtain a high-quality image even when there is a misalignment of nozzles of adjacent chips that is greater than the resolution. [Means for solving the problem]

[0007] The present invention provides an image processing apparatus that uses a printhead in which a first chip having a first nozzle row in which a plurality of nozzles are arranged and a second chip having a second nozzle row in which a plurality of nozzles are arranged is disposed, and that includes image processing means that processes image data in order to print an image on the printhead by ejecting the same ink from the first nozzle row and the second nozzle row while scanning the printhead and a print medium relatively in a first direction, wherein the first chip and the second chip provided on the printhead are disposed so that an area on an end side of the first nozzle row and an area on an end side of the second nozzle row form an overlapping area when viewed from the first direction, and the image processing means processes binary print data in which ejection or non-ejection is determined for each pixel based on multi-value input image data. a second acquisition means for acquiring an inter-nozzle distance, which is an amount of deviation from a standard distance in a second direction perpendicular to the first direction, between a first end nozzle of the first nozzle row and a second end nozzle of the second nozzle row when the first chip and the second chip are properly arranged; and an allocation means for allocating the print data to each nozzle of the first nozzle row and the second nozzle row based on the inter-nozzle distance, wherein the allocation means performs a shift process for shifting an allocation position of the print data for each nozzle from the allocation position when the inter-nozzle distance is the standard distance, based on the inter-nozzle distance, and changes a distribution process for distributing the print data to nozzles located in the overlapping portion according to the inter-nozzle distance. When the distance in the second direction between the first chip and the second chip is greater than an appropriate distance and the inter-nozzle distance is smaller than the arrangement interval of the nozzles, the allocation means performs the distribution process so as to increase the amount of ink applied to the area on the recording medium corresponding to the overlapping portion compared to when the inter-nozzle distance matches the arrangement interval of the nozzles. It is characterized by: [Effects of the Invention]

[0008] According to the present invention, even when there is a misalignment of nozzles on adjacent chips that is greater than the resolution, it is possible to obtain a high-quality image. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram illustrating the internal configuration of the recording apparatus. [Figure 2] FIG. 2 is a diagram illustrating a configuration of a recording head. [Figure 3]FIG. 2 is a control configuration diagram of the recording apparatus. [Figure 4] FIG. 2 is a diagram showing the recording device in a recording state. [Figure 5] FIG. 10 is a diagram showing a transport path of a recording medium fed from a first cassette. [Figure 6] 10 is a flowchart of a control program for data processing. [Figure 7] FIG. 10 is a diagram showing an index pattern. [Figure 8] 3A and 3B are schematic diagrams showing examples of nozzle rows and nozzle arrangements in each chip. [Figure 9] 10 is a flowchart showing image processing according to the chip-to-chip distance. [Figure 10] FIG. 10 is a diagram showing the relationship between pixel numbers and nozzle numbers of nozzles. [Figure 11] 3A and 3B are diagrams showing image data, a mask, print data, and a nozzle row in charge. [Figure 12] FIG. 10 is a diagram showing the positional relationship between pixel numbers, nozzle numbers, and selected masks. [Figure 13] FIG. 10 is a diagram showing a mask set corresponding to a mask rank. DETAILED DESCRIPTION OF THE INVENTION

[0010] (First embodiment) 1 is a diagram showing the internal configuration of an inkjet recording apparatus 1 (hereinafter referred to as recording apparatus 1) used in this embodiment. In the figure, the x direction indicates the horizontal direction, the y direction (perpendicular to the paper surface) indicates the direction in which nozzles that eject ink (nozzles) are arranged in a recording head 8 (described later), and the z direction indicates the vertical direction.

[0011] Recording device 1 is a multifunction device equipped with a printing unit 2 and a scanner unit 3, and various processes related to recording and reading operations can be performed by the printing unit 2 and the scanner unit 3 individually or in conjunction with each other. The scanner unit 3 is equipped with an ADF (automatic document feeder) and an FBS (flatbed scanner), and can read documents automatically fed by the ADF and read (scan) documents placed on the platen of the FBS by the user. Note that although this embodiment is a multifunction device equipped with both the printing unit 2 and the scanner unit 3, a configuration without the scanner unit 3 is also possible. FIG. 1 shows recording device 1 in a standby state in which neither recording nor reading operations are being performed.

[0012] In the printing unit 2, a first cassette 5A and a second cassette 5B for storing recording media (cut sheets) S are removably installed at the bottom vertically below the housing 4. The first cassette 5A stores relatively small recording media up to A4 size, while the second cassette 5B stores relatively large recording media up to A3 size, stacked flat. A first feeding unit 6A is provided near the first cassette 5A for separating and feeding the stored recording media one by one. Similarly, a second feeding unit 6B is provided near the second cassette 5B. When a recording operation is performed, the recording media S is selectively fed from one of the cassettes.

[0013] The transport rollers 7, discharge rollers 12, pinch rollers 7a, spurs 7b, guides 18, inner guides 19, and flapper 11 constitute a transport mechanism for guiding the recording medium S in a predetermined direction. The transport rollers 7 are disposed upstream and downstream of the recording head 8 and are drive rollers driven by a transport motor (not shown). The pinch rollers 7a are driven rollers that rotate together with the transport rollers 7 while nipping the recording medium S. The discharge rollers 12 are disposed downstream of the transport rollers 7 and are drive rollers driven by a transport motor (not shown). The spurs 7b, together with the transport rollers 7 and discharge rollers 12 disposed downstream of the recording head 8, pinch and transport the recording medium S.

[0014] Guide 18 is provided on the transport path of the recording medium S and guides the recording medium S in a predetermined direction. Inner guide 19 is a member extending in the y direction, has curved sides, and guides the recording medium S along these sides. Flapper 11 is a member for switching the direction in which the recording medium S is transported during double-sided recording. Discharge tray 13 is a tray for stacking and holding the recording medium S discharged by discharge rollers 12 after the recording operation is completed.

[0015] The print head 8 is a full-line type print head, and has a plurality of nozzles arranged in the y direction in FIG. 1, each of which ejects ink in accordance with print data, the number of which corresponds to the width of the print medium S.

[0016] Here, the configuration of the print head 8 used in this embodiment will be described with reference to FIG. 2. FIG. 2(a) is a diagram showing the print head 8 used in this embodiment. The print head 8 is a so-called spliced ​​print head in which a plurality of parallelogram chips CH, each having a nozzle row aligned in the y direction, are arranged in a direction perpendicular to the conveyance direction (w direction) of the print medium S. Each chip has the same configuration. In this embodiment, the arrangement positions of adjacent chips CH are shifted by a predetermined distance in the y direction in a staggered arrangement.

[0017] Figure 2(b) is an enlarged view of region IIb shown in Figure 2(a), showing adjacent chips CH1 and CH2. As shown in Figure 2(b), each of chips CH1 and CH2 has multiple nozzle rows arranged parallel to each other, each corresponding to multiple ink colors. In this example, each nozzle row corresponds to four ink colors: cyan (C), magenta (M), yellow (Y), and black (K).

[0018] The chip CH1 and the chip CH2 are arranged so as to form a joint portion T where they overlap in the transport direction (w direction) of the recording medium S. In the nozzle arrays N of the chip CH1 and the chip CH2 that eject the same ink, in the same positionThere is an overlapping portion OL consisting of nozzles. For example, the nozzle row N1 provided on chip CH1 and the nozzle row N2 provided on chip CH2 each have an overlapping portion OL consisting of nozzles that are located at the same position in the y direction. Note that this overlapping portion OL can also be said to be a portion consisting of nozzles where both the nozzle row N1 and the nozzle row N2 overlap when viewed from the recording medium transport direction w.

[0019] As described above, in this embodiment, the nozzle rows of the adjacent chips CH are Viewed from the w direction The chips are arranged so that an overlapping portion OL is formed. Therefore, even if the position of the chip CH deviates from the predetermined position, the nozzle drive (ink ejection) in the overlapping portion OL can be controlled by a process specific to this embodiment, which will be described later, to suppress the occurrence of density unevenness such as black streaks and white streaks in the printed image.

[0020] Referring again to Figure 1, when the recording head 8 configured as described above is in the standby position, the surface 8a on which the nozzles of the recording head 8 are formed (nozzle surface) faces vertically downward as shown in Figure 1 and is capped by a cap unit 10. When performing a recording operation, a print controller 202 (described later) changes the orientation of the recording head 8 so that the nozzle surface 8a faces a platen 9. The platen 9 is formed of a flat plate extending in the y direction and supports, from the rear, the recording medium S on which the recording operation is performed by the recording head 8. The movement of the recording head 8 from the standby position to the recording position will be described in detail later.

[0021] The ink tank unit 14 stores each of the four colors of ink to be supplied to the recording head 8. The ink supply unit 15 is provided in the middle of the flow path connecting the ink tank unit 14 and the recording head 8, and adjusts the pressure and flow rate of the ink inside the recording head 8 to an appropriate range. In this embodiment, a circulation type ink supply system is used, and the ink supply unit 15 adjusts the pressure of the ink supplied to the recording head 8 and the flow rate of the ink collected from the recording head 8 to an appropriate range.

[0022] The maintenance unit 16 includes a cap unit 10 and a wiping unit 17, and operates these at a predetermined timing to perform maintenance operations on the recording head 8.

[0023] 3 is a block diagram showing the control configuration of the recording apparatus 1. The control configuration is mainly composed of a print engine unit 200 that controls the print section 2, a scanner engine unit 300 that controls the scanner section 3, and a controller unit 100 that controls the entire recording apparatus 1. This controller unit functions as an image processing device that performs image processing, which will be described later. A print controller 202 controls various mechanisms of the print engine unit 200 in accordance with instructions from a main controller 101 of the controller unit 100. Various mechanisms of the scanner engine unit 300 are controlled by the main controller 101 of the controller unit 100. The control configuration will be described in detail below.

[0024] In the controller unit 100, a main controller 101 configured by a CPU controls the entire recording device 1 using a RAM 106 as a work area in accordance with programs and various parameters stored in a ROM 107. For example, when a print job is input from a host device 400 via a host I / F 102 or a wireless I / F 103, an image processing unit 108 as an image processing means performs predetermined image processing on the received input image data in accordance with instructions from the main controller 101. The main controller 101 then transmits the image data (recording data) that has undergone image processing to a print engine unit 200 via a print engine I / F 105.

[0025] The recording device 1 may acquire image data from the host device 400 via wireless or wired communication, or may acquire image data from an external storage device (such as a USB memory) connected to the recording device 1. There are no limitations on the communication method used for wireless or wired communication. For example, Wi-Fi (Wireless Fidelity) (registered trademark) and Bluetooth (registered trademark) can be used as communication methods for wireless communication. Furthermore, USB (Universal Serial Bus) or the like can be used as a communication method for wired communication. Furthermore, for example, when a read command is input from the host device 400, the main controller 101 transmits the command to the scanner unit 3 via the scanner engine I / F 109.

[0026] The operation panel 104 is a mechanism that allows the user to input and output data to and from the recording device 1. The user can use the operation panel 104 to instruct operations such as copying and scanning, set print modes, and view information about the recording device 1.

[0027] In the print engine unit 200, a print controller 202, which is configured by a CPU, controls various mechanisms of the print unit 2 in accordance with programs and various parameters stored in a ROM 203, using a RAM 204 as a work area. When various commands and image data are received via a controller I / F 201, the print controller 202 temporarily stores them in the RAM 204. The print controller 202 then causes an image processing controller 205 to convert the stored image data into print data so that the print head 8 can use it for printing. Once the print data is generated, the print controller 202 causes the print head 8 to perform a printing operation based on the print data via a head I / F 206. At this time, the print controller 202 drives the feed units 6A and 6B, the conveyance roller 7, the discharge roller 12, and the flapper 11 shown in FIG. 1 via a conveyance control unit 207 to convey the printing medium S. In accordance with instructions from the print controller 202, the print head 8 performs a printing operation in conjunction with the conveyance operation of the printing medium S, and printing processing is performed.

[0028] The head carriage control unit 208 changes the orientation and position of the recording head 8 depending on the operating state, such as the maintenance state or recording state, of the recording device 1. The ink supply control unit 209 controls the ink supply unit 15 so that the pressure of the ink supplied to the recording head 8 falls within an appropriate range. The maintenance control unit 210 controls the operation of the cap unit 10 and the wiping unit 17 in the maintenance unit 16 when performing maintenance operations on the recording head 8.

[0029] In the scanner engine unit 300, the main controller 101 controls the hardware resources of the scanner controller 302 in accordance with the programs and various parameters stored in the ROM 107, using the RAM 106 as a work area. This controls various mechanisms of the scanner unit 3. For example, the main controller 101 controls the hardware resources in the scanner controller 302 via the controller I / F 301, so that a document placed on the ADF by a user is transported via the transport control unit 304 and read by a sensor 305. The scanner controller 302 then stores the read image data in the RAM 303. The print controller 202 converts the image data acquired as described above into print data, thereby enabling the print head 8 to perform a print operation based on the image data read by the scanner controller 302.

[0030] 4 shows the recording apparatus 1 in a recording state. Compared to the standby state shown in FIG. 1, the cap unit 10 is spaced apart from the nozzle surface 8a of the recording head 8, and the nozzle surface 8a faces the platen 9. In this embodiment, the plane of the platen 9 is inclined at approximately 45 degrees relative to the horizontal, and the nozzle surface 8a of the recording head 8 in the recording position is also inclined at approximately 45 degrees relative to the horizontal so that the distance from the platen 9 is maintained constant.

[0031] 1 to the recording position shown in FIG. 4, the print controller 202 uses the maintenance control unit 210 to lower the cap unit 10 to the retracted position shown in FIG. 3. This separates the nozzle surface 8a of the recording head 8 from the cap member 10a. The print controller 202 then uses the head carriage control unit 208 to rotate the recording head 8 by 45 degrees while adjusting the vertical height of the recording head 8, so that the nozzle surface 8a faces the platen 9. When the recording operation is completed and the recording head 8 moves from the recording position to the standby position, the print controller 202 performs the above steps in reverse.

[0032] Next, we will explain the transport path of the recording medium S in the printing unit 2. When a recording command is input, the print controller 202 first uses the maintenance control unit 210 and the head carriage control unit 208 to move the recording head 8 to the recording position shown in Fig. 3. Then, the print controller 202 uses the transport control unit 207 to drive either the first feeding unit 6A or the second feeding unit 6B in accordance with the recording command, and feeds the recording medium S.

[0033] 5(a) to 5(c) are diagrams showing the conveyance path when A4-sized recording media S stored in the first cassette 5A are fed. The topmost recording medium S in the first cassette 5A is separated from the second and subsequent recording media by the first feeding unit 6A, and is conveyed toward the recording area P between the platen 9 and the recording head 8 while being nipped between the conveyance roller 7 and the pinch roller 7a. FIG. 5(a) shows the conveyance state of the recording medium S just before the leading edge thereof reaches the recording area P. The traveling direction of the recording medium S is changed from the horizontal direction (x direction) to a direction tilted at approximately 45 degrees relative to the horizontal direction while being fed by the first feeding unit 6A and reaching the recording area P.

[0034] In the recording region P, ink is ejected toward the recording medium S from multiple nozzles provided in the recording head 8. The back surface of the recording medium S in the region where ink is applied is supported by a platen 9, and the distance between the nozzle surface 8a and the recording medium S is maintained constant. After ink is applied, the recording medium S is guided by the transport roller 7 and spur 7b, passes to the left of the flapper 11, whose leading edge is tilted to the right, and is transported vertically upward in the recording device 1 along the guide 18. Figure 5(b) shows the state in which the leading edge of the recording medium S passes through the recording region P and is transported vertically upward. The traveling direction of the recording medium S is changed vertically upward by the transport roller 7 and spur 7b from the position in the recording region P, where it is tilted approximately 45 degrees from the horizontal.

[0035] The recording medium S is transported vertically upward, and then discharged onto the discharge tray 13 by the discharge rollers 12 and spurs 7b. Figure 5(c) shows the state in which the leading edge of the recording medium S passes through the discharge rollers 12 and is discharged onto the discharge tray 13. The discharged recording medium S is held on the discharge tray 13 with the side on which the image has been recorded by the recording head 8 facing downward.

[0036] Similarly, the A3 size recording media S stored in the second cassette 5B are transported toward the recording area P between the platen 9 and the recording head 8. That is, the topmost recording medium S in the second cassette 5B is separated from the second and subsequent recording media by the second feeding unit 6B, and is transported toward the recording area P between the platen 9 and the recording head 8 while being nipped between the transport roller 7 and the pinch roller 7a.

[0037] Furthermore, when performing double-sided recording on an A4-sized recording medium S, recording is performed on the first side (front side) and then the recording operation is performed on the second side (back side). The transport process when recording on the first side is the same as in Figures 5(a) to (c), so a description thereof will be omitted here. When the recording operation on the first side by the recording head 8 is completed and the trailing end of the recording medium S passes the flapper 11, the print controller 202 reverses the rotation of the transport roller 7 to transport the recording medium S into the recording device 1. At this time, the flapper 11 is controlled by an actuator (not shown) so that its leading edge is tilted to the left, and therefore the leading edge of the recording medium S (the trailing edge in the recording operation on the first side) passes the right side of the flapper 11 and is transported vertically downward.

[0038] The recording medium S is then transported along the curved outer peripheral surface of the inner guide 19 and is transported again to the recording region P between the recording head 8 and the platen 9. At this time, the second side of the recording medium S faces the nozzle surface 8a of the recording head 8. The transport path thereafter is the same as in the case of first side recording shown in Figures 5(b) and (c). When the leading edge of the recording medium S passes through the recording region P and is transported vertically upward, the flapper 11 is controlled by an actuator (not shown) to move to a position where the leading edge is tilted to the right.

[0039] Fig. 6 is a flowchart of a control program for data processing in this embodiment. The processes shown in Fig. 6 and Fig. 9 are executed in the image processing unit 108 in accordance with commands from the main controller 101 of the controller unit 100 shown in Fig. 2. Therefore, the image processing unit 108 functions as an image processing means, an acquisition means, an allocation means, and a control means as set forth in the claims. Note that the "S" attached to each process number in the flowcharts shown in Figs. 6 and 8 indicates a step.

[0040] In S61, the controller unit 100 receives multi-value input image data (RGB data) composed of 8-bit information for each RGB value from the host device 400 via the host IF 102 or wireless IF 103. In this embodiment, the input image data has a data resolution of 600 dpi x 600 dpi. The input image data indicates one of values ​​from 0 to 255 for each pixel of the 600 dpi x 600 dpi data resolution. The main controller 101 transfers the received image data to the image processing unit 108, and causes the image processing unit 108 to sequentially execute the following processes of S62 to S66.

[0041] In S62, the image processing unit 108 executes color conversion processing to convert the image data into ink color data corresponding to the colors of ink used for printing. In this embodiment, four colors of ink are used: C (cyan), M (magenta), Y (yellow), and K (black), and the color conversion processing generates ink color data (CMYK data) in which each of C, M, Y, and K has 8-bit information. The ink color data indicates one of 256 values ​​(integer values) from 0 to 255 for each pixel at a resolution of 600 dpi x 600 dpi.

[0042] Next, in S63, each ink color data is quantized to generate gradation data in which each of C, M, Y, and K is composed of 3-bit information. Dithering, error diffusion, or the like can be used for this quantization process. In this embodiment, gradation data with a data resolution of 600 dpi x 600 dpi is generated by the quantization process. The gradation data indicates one of five values ​​(five levels of gradation value), from level 0 to 4, for each pixel of the 600 dpi x 600 dpi data resolution.

[0043] Next, in S64, the gradation data is subjected to index expansion processing to generate binary data consisting of 1 bit of information for each of C, M, Y, and K. The binary data generated by the index expansion processing has a data resolution of 1200 dpi x 1200 dpi. This binary data indicates whether ink is to be ejected or not for each pixel with a resolution of 1200 dpi x 1200 dpi, and hereinafter will also be referred to as print data.

[0044] In this embodiment, in the index expansion process in S64, different index patterns are used depending on the gradation value indicated by the gradation data. Here, the index pattern is, as shown in FIG. (level) These index patterns define the number and positions of pixels onto which ink is ejected according to the pattern. Details of these index patterns and the index expansion process in S64 will be described later.

[0045] Next, in S65, the main controller 101 acquires information indicating the amount of deviation (hereinafter referred to as the inter-chip distance) from the appropriate distance between the nozzles at the ends of adjacent chips in the overlapping portion OL of the print head. This information indicating the inter-chip distance is stored in advance for each overlapping portion OL in RAM 106, which is a storage unit. The main controller 101 reads out the inter-chip distance in the overlapping portion OL stored in RAM 106. Then, in accordance with the information indicating the inter-chip distance read from RAM 106, the main controller 101 performs image processing on the print data corresponding to the inter-chip distance, and sends the processed print data to the print engine unit 200.

[0046] The chip-to-chip distance stored in RAM 106 can be identified by various conventionally known methods. For example, the chip-to-chip distance can be acquired (calculated) by recording a test chart using a recording device and performing an analysis process on the recording data captured from the test chart using scanner unit 3. It is also possible to measure the chip-to-chip distance information during the process of manufacturing the recording head and store the measured information in a predetermined storage medium provided in the recording head body.

[0047] Thereafter, in S66, print data to be allocated to each nozzle of each chip is generated based on the print data after image processing transmitted in S65 from the controller unit 100. Details of the image processing according to the inter-chip distance in S65 and the print data generation process in S66 will be described later.

[0048] After the above processing, the print controller 202 drives each print head 8 based on the generated binary print data, and executes a printing operation on the print medium.

[0049] Although the above describes a mode in which the data processing of S61 to S66 is executed, other modes of processing may be executed as long as it is possible to generate data that specifies whether or not each nozzle will eject. For example, the received image data may be converted to a data resolution of 1200 dpi x 1200 dpi, and then binary data (print data) may be generated by dithering.

[0050] (index expansion process) The index expansion process executed in this embodiment will be described in detail below. 7 is a diagram showing a schematic diagram of the index patterns used in the index expansion process in this embodiment. In this embodiment, there are four index patterns that define the number and positions of pixels to which ink should be ejected according to the gradation values ​​of the gradation data in a pixel group consisting of 2 pixels x 2 pixels with a data resolution of 600 dpi x 600 dpi. These index patterns are then selected and applied according to the position of the pixel group.

[0051] 7A to 7D are diagrams illustrating the four index patterns used in this embodiment. The number in each pixel indicates a threshold value that is compared with the gradation value of the gradation data to determine whether or not to eject ink. In detail, if the gradation value is equal to or greater than the threshold value in each pixel, it is determined that ink is to be ejected from that pixel, and if it is less than the threshold value, it is determined that ink is not to be ejected from that pixel.

[0052] For example, in the index pattern shown in Figure 7(A) (hereinafter referred to as index pattern A), the threshold values ​​are set as "1" for the bottom right pixel, "2" for the top left pixel, "3" for the bottom left pixel, and "4" for the top right pixel.

[0053] Therefore, when gradation data with a gradation value of level 0 is input, it is determined that no ink will be ejected from any of the 2 pixels x 2 pixels in the pixel group (FIG. 7(A0)). When gradation data with a gradation value of level 1 is input, it is determined that ink will be ejected only from the lower right pixel, which is assigned a threshold value of "1" (FIG. 7(A1)). When gradation data with a gradation value of level 2 is input, it is determined that ink will be ejected from the lower right pixel, which is assigned a threshold value of "1," as well as the upper left pixel, which is assigned a threshold value of "2" (FIG. 7(A2)). When gradation data with a gradation value of level 3 is input, it is determined that ink will be ejected from the lower right and upper left pixels, which are assigned threshold values ​​of "1" and "2," as well as the lower left pixel, which is assigned a threshold value of "3" (FIG. 6(A3)). When gradation data with a gradation value of level 4 is input, it is determined that ink will be ejected from any of the 2 pixels x 2 pixels in the pixel group (FIG. 6(A4)).

[0054] The same applies to the index patterns shown in FIGS. 7(B), (C), and (D) (hereinafter referred to as index pattern B, index pattern C, and index pattern D, respectively).

[0055] For example, when index pattern B is used, at level 0, no ink is ejected to any pixel (Fig. 7(B0)). At level 1, ink is ejected only to the top left pixel (Fig. 7(B1)), at level 2 to the top left and bottom right pixels (Fig. 7(B2)), and at level 3 to the top left, bottom right, and top right pixels (Fig. 7(B3)). At level 4, ink is ejected to any pixel (Fig. 7(B4)).

[0056] Furthermore, when index pattern C is used, at level 0, no ink ejection is determined for any pixel (Fig. 7(C0)). At level 1, ink ejection is determined for only the upper right pixel (Fig. 7(C1)), at level 2 for the upper right and lower left pixels (Fig. 7(C2)), and at level 3 for the upper right, lower left, and lower right pixels (Fig. 7(C3)). At level 4, ink ejection is determined for all pixels (Fig. 7(C4)).

[0057] Furthermore, when index pattern D is used, at level 0, no ink is ejected to any pixel (Fig. 7(D0)). At level 1, ink is ejected only to the bottom left pixel (Fig. 7(D1)), at level 2 to the bottom left and top right pixels (Fig. 7(D2)), and at level 3 to the bottom left, top right, and top left pixels (Fig. 7(D3)). At level 4, ink is ejected to any pixel (Fig. 76(D4)).

[0058] In this embodiment, the index patterns A to D are arranged according to a predetermined arrangement pattern, and the gradation data is index-expanded according to each arranged index pattern to generate binary data (print data).

[0059] (Nozzle row and nozzle arrangement within the chip) Figure 8 is a diagram specifically showing an example of the arrangement of nozzle rows and nozzles within each chip in the recording head 8 used in this embodiment, and shows an enlarged portion of the connecting portion T between chip CH1 (first chip) and chip CH2 (second chip) shown in Figure 2 above.

[0060] In this embodiment, each chip CH provided in the recording head 8 has the same configuration. Therefore, chip CH1 and chip CH2 each have a nozzle array that ejects ink of the same color, arranged along a predetermined arrangement direction. In this embodiment, the arrangement direction of chip CH1 and chip CH2 is the y direction. Furthermore, the nozzle array N10 (first nozzle array) in chip CH1 and the nozzle array N20 (second nozzle array) provided in chip CH2 are nozzle arrays that eject ink of the same color. As shown in FIG. 8, the nozzle array N10 and the nozzle array N20 are arranged at different positions in the transport direction (w direction) of the recording medium S, but the first nozzle array N10 and the second nozzle array N20 are nozzle arrays responsible for forming one line extending in the w direction. In other words, the nozzle array N10 and the nozzle array N20 are driven at different timings based on the difference in their arrangement positions in the w direction (first direction), and eject ink onto the recording medium S. y Ink droplets are deposited at the same position in the direction of the arrow, forming a continuous line.

[0061] Each nozzle array provided on each chip is composed of multiple nozzles arranged at a predetermined nozzle spacing t1 along a nozzle arrangement direction (y direction), which is a second direction intersecting with the recording medium transport direction (w direction), which is a first direction. In this example, the nozzle arrangement direction (y direction) is set to a direction perpendicular to the transport direction (w direction). In each nozzle array N, the distance (nozzle spacing) t1 between adjacent nozzles in the y direction is 1200 dpi.

[0062] (distance between chips) Next, the distance between adjacent chips (chip-to-chip distance) in the print head 8 will be described with reference to FIG. 8. FIG. 8(a) shows a state in which chips CH1 and CH2 in the print head 8 are properly positioned. Multiple end nozzles 1e, 1f, 1g, and 1h (first end nozzles) located at the end of nozzle row N10 and multiple end nozzles 2a, 2b, 2c, and 2d (second end nozzles) located at the end of nozzle row N20 overlap in the y direction. That is, nozzle 1e and nozzle 2a, nozzle 1f and nozzle 2b, nozzle 1g and nozzle 2c, and nozzle 1h and nozzle 2d are each arranged on the same line parallel to the w direction. In this way, in two adjacent nozzle rows, nozzles located at overlapping portions OL that overlap each other in the y direction are referred to as overlapping nozzles, and a nozzle group consisting of overlapping nozzles is referred to as an overlapping nozzle group. In the example shown in FIG. 8(a), end nozzles 1e, 1f, 1g, and 1h in the first nozzle row N10 are overlapping nozzles, and these overlapping nozzles form an overlapping nozzle group G1. Similarly, in the second nozzle row N20, end nozzles 2a, 2b, 2c, and 2d are overlapping nozzles, and these overlapping nozzles form an overlapping nozzle group G2. In this embodiment, the state in which chips CH1 and CH2 are arranged so as to obtain the nozzle arrangement shown in FIG. 8(a) is considered to be an ideal chip arrangement, and the chip-to-chip distance in this chip arrangement is set to "0." In contrast, if at least one of chips CH1 and CH2 is shifted in the y direction from the ideal arrangement, the chip-to-chip distance will be a value other than "0."

[0063] In this embodiment, the chip-to-chip distance is the average value of the inter-nozzle distances between overlapping nozzles 1e and 2a, 1f and 2b, 1g and 2c, and 1h and 2d measured by a measuring device (not shown). The inter-nozzle distance refers to the distance in the y direction between a corresponding pair of overlapping nozzles (e.g., overlapping nozzles 1e and 2a). When chips CH1 and CH2 are properly positioned, the inter-nozzle distance is zero. In other words, a non-zero inter-nozzle distance indicates the amount of misalignment between a pair of overlapping nozzles in the y direction. Therefore, the inter-nozzle distance corresponds to the distance in the y direction between the pixel position of the image to be formed on the recording medium S and the nozzle position responsible for forming that pixel. Furthermore, the chip-to-chip distance calculated based on the inter-nozzle distance is defined as the + (plus) direction, which is the direction in which the first nozzle row N10 and the second nozzle row N20 move relatively apart, i.e., the direction in which chips CH1 and CH2 move apart. Furthermore, the - (minus) direction, which is the direction in which the first nozzle row N10 and the second nozzle row N20 move relatively closer to each other, i.e., the direction in which chips CH1 and CH2 move closer to each other. The inter-nozzle distance and the inter-chip distance are stored in the RAM 106, which serves as a first storage means.

[0064] FIG. 8(b) shows a state in which the inter-chip distance is shifted in the positive direction. In this state, the dot density in the area printed by the end nozzles (1e to 1h and 2a to 2d) tends to be locally low, which may result in white streaks. FIG. 8(c) shows a state in which the inter-chip distance is shifted in the negative direction. In this state, the dot density in the area printed by the overlapping nozzles tends to be locally high, which may result in black streaks. Therefore, in this embodiment, the following image correction process is performed depending on the inter-chip distance.

[0065] (Image correction processing according to chip distance) 9 is a flowchart showing image processing according to the chip-to-chip distance executed in this embodiment. The processing shown in this flowchart is executed by the image processing unit 108, which functions as an image processing means, under the instruction of the main controller 101. The processing described below corresponds to the processing executed in S65 shown in FIG.

[0066] In S91, the chip-to-chip distance pre-stored in RAM 106 of the controller unit 100 is acquired. Next, in S92, a process is performed to set the nozzle shift amount and mask rank according to the chip-to-chip distance acquired in S91. Nozzle shift refers to moving the nozzle position in the y direction relative to the print data, and the nozzle shift amount refers to the amount of this movement. The mask rank will be described later.

[0067] Here, we will explain the relationship between chip distance and image quality. (μm) " to "+30 (μm) " to 5 μm The relationship between the distance between the nozzles and the visibility of density unevenness (streaks) that appears in the image and the distance between the tips is summarized in Table 1, where the distance between the nozzles is changed in increments and a specified image is recorded on plain paper, which is the recording medium S. In Table 1, the state where no streaks are visible indicates that there is no degradation in image quality.

[0068] In Table 1, column A lists the inter-chip distance values, and column B lists the evaluation results for streak visibility. When the inter-chip distance is "0," the nozzle position between the chips is not deviated from the ideal arrangement, so no streaks are visible in the image. When the inter-chip distance is "+5" or "-5," there is some misalignment between adjacent chips, but the streaks are not visible in the printed sample. Note that streak visibility varies depending on the type of printing medium S, the ink droplet dot diameter, and the wetting and spreading of the ink on the printing medium. Under the conditions of this verification experiment, when the inter-chip distance is +5 and -5, i.e., when the inter-chip distance is about 1 / 4 pixel, no image defects such as streaks are visible.

[0069] On the other hand, when the chip-to-chip distance was +10, i.e., when the chip-to-chip distance was about 1 / 2 pixel, slight white streaks were visible. Furthermore, when the chip-to-chip distance was +15, +20, +25, and +30, i.e., when the chip-to-chip distance was 1 / 2 pixel or more, noticeable white streaks were visible. On the other hand, when the chip-to-chip distance was -10, slight black streaks were visible, and when the chip-to-chip distance was -15, -20, -25, and -30, noticeable black streaks were visible.

[0070] In this embodiment, in order to reduce such visually noticeable streaks, a nozzle shift process is performed to shift the allocation destination of each pixel data from the default nozzle. JPEG0007818968000001.jpg94150

[0071] The nozzle shift amount in the nozzle shift process is listed in column C of Table 1. The nozzle shift amount listed here indicates the amount by which the position of the nozzles used is shifted in the direction that reduces the visibility of streaks based on the experimental results described above.

[0072] At chip-to-chip distances of -5, 0, and +5, no image defects are visible, so the nozzle shift amount is set to 0 and nozzle shift processing is not performed. Furthermore, at a chip-to-chip distance of +10, slight white streaks are visible, but because nozzle shift can only be performed in one-pixel increments, i.e., in increments of approximately 20 μm, performing nozzle shift processing would result in the opposite occurrence of black streaks equivalent to those occurring at a chip-to-chip distance of -10. Similarly, at a chip-to-chip distance of -10, performing nozzle shift processing in the positive direction would result in the opposite occurrence of white streaks equivalent to those occurring at a chip-to-chip distance of +10. Therefore, for chip-to-chip distances where nozzle shifting is not expected to improve streaks, the nozzle shift amount is set to 0 and nozzle shift processing is not performed. As such, nozzle shift processing may not improve image quality for deviations of less than 20 μm, which is the minimum correction accuracy for nozzle shift. For this reason, in this embodiment, mask data setting and mask selection processing are performed according to the nozzle shift amount and mask rank set in S92.

[0073] When the chip-to-chip distances are +15, +20, +25, and +30, significant white streaks are visible, so the nozzle shift amount is set to "-1." This allows the apparent chip-to-chip distance to be -5, 0, +5, or +10, which is the actual chip-to-chip distance minus 20. As a result, as shown in Table 1, it is possible to keep the distance within a range where no streaks are visible or where only minor white streaks are visible. When the chip-to-chip distances are -15, -20, -25, and -30, significant black streaks are visible, so the nozzle shift amount is set to "+1." This allows the apparent chip-to-chip distance to be +5, 0, -5, or -10, which is the actual chip-to-chip distance plus 20. As a result, as shown in Table 1, it is possible to keep the distance within a range where no streaks are visible or where only minor black streaks are visible.

[0074] Next, in S93 shown in Figure 9, a nozzle shift process (allocation process) is performed to determine the nozzle positions (allocation positions) to which print data in each nozzle array is assigned, depending on the nozzle shift amount set in S92 above. The nozzle shift process for print data will be explained below with reference to Figures 8 and 10. Figures 10(a), (b), and (c) are diagrams showing the relationship between pixel numbers indicating the positions of each of multiple pixel data in the image data and the nozzle numbers assigned to the nozzles.

[0075] As mentioned above, when the chip-to-chip distance is "0," the relative positions of nozzle arrays N10 and N20 are as shown in Figure 8(a). In this case, nozzles 1e and 2a, 1f and 2b, 1g and 2c, and 1h and 2d are each arranged on the same line parallel to the recording medium transport direction (direction w). The nozzle arrangement shown in Figure 8(a) is the ideal nozzle arrangement, and the nozzle shift amount in this case is "0."

[0076] FIG. 10(a) shows the relationship between nozzle numbers and pixel numbers indicating the positions of pixel data when the nozzle shift amount is "0." In the figure, 1a to 1h indicate nozzle numbers in nozzle array N10, and 2a to 2h indicate nozzle numbers in nozzle array N20. Of these nozzles, nozzles 1e to 1h in nozzle array N10 and nozzles 2a to 2d in nozzle array N20 are overlapping nozzles in their respective nozzle arrays. FIG. 10(a) also shows pixel numbers A to M indicating the positions of each pixel in the image area formed on the recording medium S. The print data (pixel data) corresponding to these pixel numbers is assigned to each nozzle as follows: That is, print data for pixel number B is assigned to nozzle 1a in nozzle array N10, and print data for pixel numbers C, D, E, F, G, H, and I are sequentially assigned to nozzles 1b to 1h. Furthermore, print data corresponding to pixel number F is assigned to nozzle 2a of nozzle row N20, and print data (pixel data) of image numbers G, H, I, J, K, L, and M are sequentially assigned to nozzles 2b to 2h. As a result, for example, print data for pixel number E is printed by nozzle 1d. Print data for pixel number F is printed by either nozzle 1e or 2a, and print data for pixel number I is printed by either nozzle 1h or 2d. Print data for pixel number J is printed by nozzle 2e.

[0077] FIG. 8(b) shows the relative positions of nozzle array N10 and nozzle array N20 when the chip-to-chip distance is "+20". In this case, nozzles 1f and 2a, 1g and 2b, and 1h and 2c are arranged on the same line parallel to the recording medium transport direction (direction w). Furthermore, nozzles 1e and 2d do not have a nozzle at the same position in the y direction. When the chip-to-chip distance is "+20" in this way, the nozzle shift amount is set to "-1" based on Table 1.

[0078] FIG. 10(b) shows the relationship between nozzle numbers and pixel numbers when the nozzle arrangement is that of FIG. 8(b). As mentioned above, in the nozzle arrangement of FIG. 8(b), the nozzle shift amount is set to "-1," resulting in one less overlapping nozzle than in FIG. 10(a). Print data corresponding to the image with pixel number A is assigned to nozzle 1a of nozzle array N10, and print data corresponding to pixel numbers B, C, D, E, F, G, and H are sequentially assigned to nozzles 1b through 1h. Print data corresponding to pixel number F is assigned to nozzle 2a of nozzle array N20, and print data for image numbers G, H, I, J, K, L, and M are sequentially assigned to nozzles 2b through 2h. As a result, the print data for pixel number E is shifted so that it is printed by nozzle 1e. The print data for pixel number F is printed by either nozzle 1f or 2a, and the print data for pixel number I is shifted so that it is printed by nozzle 2d.

[0079] 8(c) shows the relative positions of nozzle array N10 and nozzle array N20 when the chip-to-chip distance is "-20". In this case, nozzles 1e and 2b, 1f and 2c, and 1g and 2d are respectively arranged on the same line parallel to the conveyance direction (w direction) of the recording medium. Furthermore, nozzles 1h and 2a are arranged on the same line parallel to the conveyance direction (w direction) with non-overlapping nozzles 2e and 1d. In this way, when the chip-to-chip distance is "-20", the nozzle shift amount is set to "+1" based on Table 1.

[0080] FIG. 10(c) shows the relationship between nozzle numbers and pixel numbers when the nozzle arrangement is that of FIG. 8(c). As described above, in the nozzle arrangement of FIG. 8(c), the nozzle shift amount is set to "+1," so the number of overlapping nozzles is one more than in the case of FIG. 12(a). Print data corresponding to the image with pixel number C is assigned to nozzle 1a of nozzle array N10, and print data corresponding to pixel numbers D, E, F, G, H, I, and J are sequentially assigned to nozzles 1b through 1h. Print data corresponding to pixel number F is assigned to nozzle 2a of nozzle array N20, and print data (pixel data) for image numbers G, H, I, J, K, L, and M are sequentially assigned to nozzles 2b through 2h. As a result, the print data for pixel number E is shifted so that it is printed by nozzle 1c. The print data for pixel number F is shifted so that it is printed by either nozzle 1d or 2a, and the print data for pixel number I is shifted so that it is printed by either nozzle 1g or 2d.

[0081] Next, the process of S94 shown in Fig. 9 is performed. In S94, a mask selection process is performed according to the inter-chip distance acquired in S91. In this embodiment, a print data distribution process using a mask is performed for each overlapping nozzle of nozzle arrays N10 and N20. That is, a process is performed to distribute the print data of the overlapping portion to each overlapping nozzle using masks corresponding to overlapping nozzles 1e, 1f, 1g, and 1h of nozzle array N10 and overlapping nozzles 2a, 2b, 2c, and 2d of nozzle array N20.

[0082] Here, the mask used in this embodiment will be described with reference to the schematic diagram of Fig. 11. The mask is made up of mask data for distributing print data to overlapping nozzles (first overlapping nozzles) in a nozzle row provided on one of two adjacent chips, and overlapping nozzles (second overlapping nozzles) on the other chip. In Fig. 11, Recorded Data D represents the print data of the image printed by the first overlapping nozzle and the second overlapping nozzle, Mask 1A corresponds to the first overlapping nozzle mask of, Mask 1B corresponds to the second overlapping nozzle Mask, respectively.

[0083] In print data D, mask 1A, and mask 1B, the address numbers of four pixels in the y direction (nozzle arrangement direction) are y1 to y4, and the address numbers of four pixels in the w direction (conveyance direction) are w1 to w4. As shown in the figure, the print data and each mask have an area defined by the y direction (nozzle arrangement direction) and the w direction (conveyance direction of the print medium). Recorded Data D In the 16 pieces of print data (pixel data) defined by the y and w directions, pixel data containing "1" represents data that instructs ink ejection (hereinafter also referred to as ejection data). Pixel data containing "0" represents data that does not instruct ink ejection (hereinafter also referred to as non-ejection data). Each mask data in masks 1A and 1B is data for calculating the logical product with the print data. Mask data 1A and 1B In "1" is , which is data that allows ink to be ejected from the nozzles (hereinafter also referred to as "allowance data"). "0" is , data that does not permit ink ejection (hereinafter also referred to as non-permission data).

[0084] That is, if the data obtained by ANDing the pixel data and the mask data is "1", that data becomes print data (ejection data) that causes ink to be ejected from the nozzle, and a dot is formed in the pixel corresponding to that pixel data. On the other hand, if the data obtained by ANDing the pixel data and the mask data is "0", that data becomes print data (non-ejection data) that does not cause ink to be ejected from the nozzle, and no dot is formed in the pixel corresponding to that pixel data.

[0085] 8(a) will be described assuming that nozzle row N10 is the first nozzle row, the overlapping nozzles of the first nozzle row are the first overlapping nozzles, nozzle row N20 is the second nozzle row, and the overlapping nozzles of the second nozzle row are the second overlapping nozzles. In this case, first overlapping nozzle 1e of first nozzle row N10 corresponds to print data D and data at address y1 in mask 1A, and first overlapping nozzle 1f corresponds to print data D and data at address y2 in mask 1A. Furthermore, first overlapping nozzle 1g corresponds to print data D and data at address y3 in mask 1A, and first overlapping nozzle 1h corresponds to print data D and data at address y4 in mask 1A.

[0086] Mask data indicating all "1"s is placed at address y1 of mask 1A corresponding to the first nozzle row N10. Therefore, by taking the logical AND of the print data D corresponding to address y1 and the mask data, the "1"s and "0"s in the print data D directly become ejection data or non-ejection data for the first overlap nozzle 1e. Furthermore, mask data of "1"s and "0"s are mixed at addresses y2 and y3. Therefore, at the address corresponding to mask data of "1," the "1"s and "0"s in the print data D directly become ejection data or non-ejection data for nozzles 1f and 1g. Furthermore, print data D corresponding to mask data of "0" becomes non-ejection data for the first overlap nozzles 1f and 1g. Furthermore, mask data indicating all "0"s is placed at address y4. Therefore, by taking the logical AND of the print data D corresponding to address y4 and the mask data, all print data D becomes non-ejection data for the first overlap nozzle 1h.

[0087] Meanwhile, the second overlap nozzle 2a of the second nozzle row N20 corresponds to the print data D and data at address y1 in mask 1B, and the second overlap nozzle 2b corresponds to the print data D and data at address y2 in mask 1B. Furthermore, the second overlap nozzle 2c corresponds to the print data D and data at address y3 in mask 1B, and the second overlap nozzle 2d corresponds to the print data D and data at address y4 in mask 1B.

[0088] Mask data indicating all "0"s is placed at the position of address y1 of mask 1B corresponding to the second nozzle row N20. Therefore, by taking the logical product of the print data D corresponding to address y1 and the mask data, "1" and "0" of the print data D become non-ejection data for nozzle 2a. Furthermore, mask data of "1" and "0" are mixed at the positions specified by addresses y2 and y3. Therefore, at the address corresponding to mask data of "1", "1" and "0" of the print data D become ejection data or non-ejection data for nozzles 2b and 2c. Furthermore, print data D corresponding to mask data of "0" becomes non-ejection data for nozzles 2b and 2c. Furthermore, at the position of address y4, 「1」 Therefore, by taking the logical product of the recording data D corresponding to address y4 and the mask data, the recording data D The "1" and "0" are the discharge data for the second overlapping nozzle 2d. This becomes non-ejection data.

[0089] As described above, the recording data created by taking the logical product of the recording data D, the mask 1A, and the mask 1B is As recorded data DA and recorded data DB show. Recorded data DA is for the first overlapping nozzles 1e, 1f, 1g, and 1d Recorded data indicates, Recorded Data DB is the second overlapping nozzle 2a, 2b, 2c, 2d Recorded data This shows: Recorded data DA and recorded data DB In the figure, data for which the logical product is "1" is represented by a "◯", and data for which the logical product is "0" is represented by an "X". In this way, ink is ejected from the first overlapping nozzles of the first nozzle row N10 and the second overlapping nozzles of the second nozzle row N20 based on the print data DA and print data DB obtained by the logical product of the print data D and the mask data.

[0090] FIG. 11(f) shows the nozzles responsible for each pixel. In a rowIn the figure, the symbol i indicates a pixel on which a dot is recorded using ink ejected from the first overlapping nozzle of the first nozzle row N10, and the symbol ii indicates a pixel on which a dot is recorded using ink ejected from the second overlapping nozzle of the second nozzle row N20. Note The symbol (x) indicates a pixel where no dot is formed. y 2 and y The area corresponding to 3 is a complementary print area where printing is performed by overlapping nozzles of the first nozzle array N10 and the second nozzle array N20. In this way, print data DA for the first nozzle array N10 and print data DA for the second nozzle array N20 are printed. DB and printing is performed in the overlapping portion based on the generated print data. Of the image areas printed on the printing medium S in the overlapping portion, the image areas where complementary printing is performed to complete the image by both the first nozzle row N10 and the second nozzle row N20 are referred to as complementary image areas. Figure 11 In the example shown in FIG. 1, the area of ​​2 pixels horizontally by 4 pixels vertically defined by addresses y2 and y3 is the complemented image area.

[0091] The above is the relationship between the mask data and print data corresponding to the nozzle groups (overlapping nozzle groups G1 and G2) fixedly determined at the ends of the first nozzle array N10 and the second nozzle array N20. The relationship between the mask data and print data shown in FIG. 11 is determined assuming a state in which two adjacent chips are properly arranged, i.e., the chip-to-chip distance is "0" and no nozzle shift processing is performed. However, the arrangement relationship between adjacent chips may deviate from the proper state (a state in which the chip-to-chip distance is "0"). If mask data created assuming a properly arranged chip state is used when a chip misalignment occurs, the relationship between the distributed print data and the nozzles may deviate, potentially resulting in density unevenness and other problems in the printed image due to the overlapping portions. Therefore, in this embodiment, multiple masks corresponding to the chip-to-chip distance are prepared, and the mask to be used is selectively set according to the nozzle shift amount determined based on the chip-to-chip distance, thereby reducing image problems. The mask data setting process taking the nozzle shift amount into account is described in detail below.

[0092] (Mask data setting according to nozzle shift amount) In this embodiment, multiple types of masks corresponding to the nozzle shift amount determined by the chip-to-chip distance are stored in advance in RAM 106 as second storage means, and a mask corresponding to the nozzle shift amount is selected and used from among these masks. Below, the process of setting a mask according to the nozzle shift amount will be described with reference to Figure 12.

[0093] FIG. 12(a) shows the positional relationship between the pixel numbers of the print data, the nozzle numbers of the nozzle arrays N10 and N20, and the selected mask when the chip-to-chip distance is "0." Because the chip-to-chip distance is "0," the nozzle shift amount is set to "0" based on Table 1. Furthermore, because the chip-to-chip distance is "0," in the overlapping portion (overlapping nozzle groups G1 and G2) defined for the nozzle arrays N10 and N20, nozzles 1e and 2a, 1f and 2b, 1g and 2c, and 1h and 2d are aligned in the y direction, which is perpendicular to the print medium transport direction (w direction). This state represents the proper positional relationship between the nozzle arrays N10 and N20. At this time, the nozzle shift process of S93 assigns print data with pixel number B to nozzle 1a of the nozzle array N10, and print data (pixel data) with pixel numbers C to I are sequentially assigned to nozzles 1b through 1h.

[0094] In this way, when the nozzle arrays N10 and N20 are in the correct positional relationship, mask 1A is selected for the overlapping portion of nozzle array N10 (overlapping nozzle group G1), and mask 1B is selected for the overlapping portion of nozzle array N20 (overlapping nozzle group G2). Overlapping nozzles 1e-1h of nozzle array N10 perform printing based on print data obtained by masking print data F-I with mask 1A. Overlapping nozzles 2a-2d of nozzle array N20 perform printing based on print data obtained by masking print data F-I with mask 1B. Specifically, based on print data obtained by masking print data for pixel number G, nozzle 1f and nozzle 2b perform complementary printing of the corresponding image area. Based on print data obtained by masking print data for pixel number H, nozzle 1g and nozzle 2c perform complementary printing of the corresponding image area. Based on print data obtained by masking print data for pixel number F, nozzle 1e performs printing of the corresponding image area. Furthermore, based on the print data obtained by masking the print data of pixel number I, the nozzle 2d prints the corresponding image area.

[0095] Figure 12(b) shows the positional relationship between the pixel number, the nozzle numbers of nozzle rows N10 and N20, and the selected mask when the chip-to-chip distance is "+20." Because the chip-to-chip distance is "+20," the nozzle shift amount is set to "-1" based on Table 1. At this time, of the nozzles in the overlapping area, nozzles 1f and 2a, 1g and 2b, and 1h and 2c are aligned in the y direction, which is perpendicular to the recording medium transport direction (w direction).

[0096] When the nozzle shift amount is "-1", the nozzle shift process of S93 assigns print data of pixel number A to nozzle 1a of nozzle row N10, and print data (pixel data) of pixel numbers B to H to nozzles 1b to 1h in sequence. This assignment of print data to nozzles differs from the case shown in FIG. 12(a). For this reason, the mask must also be switched in accordance with the nozzle shift. In this example, when the chip-to-chip distance is +20, the nozzle shift amount is set to "-1" according to Table 1, and when the nozzle shift amount is "-1", mask 2A and mask 2B are selected. Here, mask 2B is the same as mask 1B described above, but mask 2A is different from mask 1A described above. Mask 2 In A, the address y 1 and y All mask data for pixel numbers E and F are set to a gradation value of 1. 2 The print data after mask processing at A will be the same as print data E and F before mask processing.

[0097] On the other hand, the address in mask 2A y 3 and y The mask data for 4 is set to a mixture of "1" and "0". Therefore, the print data obtained by logically multiplying the print data and mask data for pixel numbers G and H determines whether or not to eject in accordance with the print data for pixels where the mask data is "1", and all pixels where the mask data is "0" are non-ejected. Note that the address of this mask 2A y 3 and y Mask data 4 is the address of mask 2B y 2 andy It is complementary to the mask data in 3.

[0098] By selecting masks 2A and 2B, overlapping nozzles 1e to 1h of nozzle row N10 perform printing based on print data obtained by masking print data E to H with mask 2A. Also, overlapping nozzles 2a to 2d of nozzle row N20 perform printing based on print data obtained by masking print data F to I with mask 2B. Specifically, the print data for pixel numbers G and H and the address in mask 2A are y 3 and y Nozzles 1g and 1h print the corresponding image area based on the print data obtained by logical AND with the mask data of No. 4. Furthermore, the print data of pixel numbers G and H and the address in mask 2B are y 2 and y Based on the print data obtained by logical AND with the mask data of No. 3, nozzles 2b and 2c print the corresponding image area. As a result, the print data of image numbers G and H are complementarily printed by nozzles 1g and 2b, and nozzles 1h and 2c, respectively. In addition, in mask 2B, address y Since all mask data for pixel number I is set to "1", the print data after masking with mask 2B is the same as print data I before masking. This print data I is printed by nozzle 2d.

[0099] Even when the chip-to-chip distance is +20 in this way, misalignment of the ink landing position on the recording medium can be suppressed by performing nozzle shift processing and selecting a mask according to the nozzle shift amount. As a result, an appropriate image can be formed in the overlapping areas with reduced density unevenness such as white streaks.

[0100] Figure 12(c) shows the positional relationship between the nozzle numbers of nozzle rows N10 and N20 and the selected mask when the chip-to-chip distance is "-20." Because the chip-to-chip distance is "-20," the nozzle shift amount is set to "+1" based on Table 1. At this time, of the nozzles in the overlapping area, nozzles 1e and 2b, 1f and 2c, and 1g and 2d are aligned in the y direction, which is perpendicular to the recording medium transport direction (w direction).

[0101] When the nozzle shift amount is "+1", the nozzle shift process of S93 sets print data (pixel data) for pixel number C to nozzle 1a of nozzle row N10, and print data (pixel data) for pixel numbers D to J are sequentially assigned to nozzles 1b to 1h. This assignment of print data to nozzles differs from the case shown in FIG. 12(a). Therefore, the mask data must also be switched in accordance with the nozzle shift. When the chip-to-chip distance is "-20", mask 3A and mask 3B are selected. Mask 3B is the same as mask 1B described above, but mask 3A is different from mask 1A described above. In mask 3A, all mask data for addresses y3 and y4 are set to "0". Therefore, when pixel number I and J The print data is masked with the mask 3A to become print data instructing non-ejection.

[0102] On the other hand, the address in mask 3A y1 and y2 The mask data for y1 and y2 in mask 3A is set to a mixture of "1" and gradation value "0". Therefore, the print data obtained by logically multiplying the print data and the mask data at addresses y1 and y2 in mask 3A determines whether or not to eject in accordance with the print data at pixels where the mask data is "1", and all pixels where the mask data is "0" are non-ejected. The mask data at addresses y1 and y2 in mask 3A is complementary to the mask data at addresses y2 and y3 in mask 3B.

[0103] By selecting mask 3A and mask 3B, nozzles 1e-1h of nozzle array N10 print based on print data obtained by masking print data G-J with mask 3A. Furthermore, nozzles 2a-2d of nozzle array N20 print based on print data obtained by masking print data F-I with mask 3B. Specifically, nozzles 1e and 1f print their corresponding image areas based on print data obtained by ANDing the print data for pixel numbers G and H with the mask data for addresses y1 and y2 in mask 3A. Furthermore, nozzles 2b and 2c print their corresponding image areas based on print data obtained by ANDing the print data for pixel numbers G and H with the mask data for addresses y2 and y3 in mask 3B. As a result, the print data for image numbers G and H are complementary printed by nozzles 1e and 2b, and nozzles 1f and 2c, respectively. Note that print data for pixel number I is printed by nozzle 2d.

[0104] Even when the nozzle distance between nozzle rows is -20, misalignment of the ink landing position on the recording medium can be suppressed by performing nozzle shift processing and selecting a mask according to the nozzle shift amount. As a result, a good image can be formed in the overlapping areas with reduced density unevenness such as black streaks.

[0105] In the above explanation, the shift processing and mask selection were described when the chip-to-chip distance was "0" and "±20." However, when the chip-to-chip distance is "±15," "±25," or "±30," the nozzle shift amount is set to ±1, and processing similar to that performed when the chip-to-chip distance is "±20" is performed. Furthermore, the set value of the nozzle shift amount is not limited to the values ​​shown in Table 1 ("0" or "±1"), and other values, such as ±2 or ±3, can also be set depending on the chip-to-chip distance. In this case, a mask appropriate for each nozzle shift amount can be prepared. Furthermore, the mask is not limited to one that corresponds to four nozzles, and may correspond to other numbers of nozzles.

[0106] As described above, in this embodiment, even if the placement positions of adjacent chips are shifted by more than the nozzle resolution (nozzle arrangement spacing), it is possible to form a good image in which the occurrence of density unevenness is suppressed in the overlapping areas of the nozzle rows.

[0107] In the above explanation, a means for selecting multiple types of masks is used, but the read position (address) of each mask data in the mask stored in a storage means such as the RAM 106 may be changed according to the nozzle shift amount. This makes it possible to realize multiple types of mask processing corresponding to the nozzle shift amount, just as in the case of using one mask to select a mask from multiple masks.

[0108] (Processing when the chip-to-chip distance is less than the nozzle resolution) Next, we will explain the processing performed when the chip-to-chip distance is less than the nozzle resolution. As mentioned above, when the chip-to-chip distance is less than the nozzle resolution, sufficient image correction may not be possible simply by performing the nozzle shift processing and mask selection described above. For example, when the chip-to-chip distance is "+10," even if a one-pixel nozzle shift is performed, the nozzle resolution is 1200 dpi (approximately 20 μm), resulting in the same state as when the chip-to-chip distance is "-10." In this case, the density unevenness that may occur will change from a tendency toward white streaks to a tendency toward black streaks, but image defects will still occur.

[0109] Therefore, in this embodiment, the amount of ink applied in the overlapping portions of adjacent nozzle rows is increased or decreased based on the distance between chips that is less than the nozzle resolution. Specifically, a mask ranked according to the distance between chips that is less than the nozzle resolution is prepared, and the amount of ink applied in the overlapping portions is controlled using this mask. In this example, masks with different numbers of allowable data (mask data "1") corresponding to the complementary image area are prepared, and the amount of ink applied in the overlapping portions is increased or decreased using this mask.

[0110] The mask shown in FIG. 12 shows that when a solid image is printed in the complementary image area by the overlapping portion of the nozzle arrays N10 and N20, the area printed by the overlapping nozzle group G1 is different from the area printed by the overlapping nozzle group G2. Duplication The masks for nozzle array N10 and N20 are configured so that the area printed by nozzle group G1 and N20 has the same ink application amount. That is, the masks for nozzle array N10 and N20 are configured so that the allowable data for ink ejection are complementary to each other. For example, when the ejection allowable data in mask 1A and the allowable data in mask 1B are added together, one allowable data is allocated to each of the eight pixel areas of two pixels horizontally and four pixels vertically that make up the complementary image area. As a result, when a solid image is printed, one ink droplet lands on each pixel of the complementary image area. This ink application state in which one ink droplet lands on each pixel area is referred to as 100 percent (%) ink application.

[0111] In contrast, the mask used when the chip-to-chip distance is less than the nozzle resolution is a mask that allows printing to be performed with an ink application amount other than 100% in the complementary image area when printing a solid image. This will be explained in detail below.

[0112] FIG. 13 is a diagram showing masks used in this embodiment. In this embodiment, three types of mask sets MS1, MS2, and MS3, which are classified into mask ranks of 0.75, 1.0, and 1.25, are stored in the RAM 106. Masks with the same reference numerals (1A, 1B, 2A, 2B, 3A, 3B) included in each of the three types of mask sets are B ) is the mask data (address) corresponding to the complement image area of ​​2 pixels horizontally x 4 pixels vertically. (y2,y3)(y3,y4)(y1,y2) The only difference between the masks is the total number of allowable data (mask data "1") in the mask data.

[0113] Ma The mask set MS1 for Scrunk 1.0 includes three pairs of masks (1A and 1B, 2A and 2B, 3A and 3B) Each mask is the same as the mask shown in FIG. 12, and the two masks in a pair are complementary. Therefore, in the area of ​​2 pixels horizontally by 4 pixels vertically, which corresponds to the complementary image area, adding the allowable data of the mask for nozzle row N10 and the allowable data of the mask for nozzle row N20 together results in a total of 8 pixels of allowable data. For this reason, when a solid image is printed in the complementary image area, the amount of ink applied to that area is 100%.

[0114] on the other hand, Ma The mask set MS2 for the 1.25 scribe line has three pairs of masks (1A, 1B, 2A, 2B, 3A, 3B) for nozzle shift processing, similar to the mask set MS1. Corresponding to the complementary image area Adding the allowable data of the mask for nozzle row N10 and the allowable data of the mask for nozzle row N20 together gives ejection data for a total of 10 pixels. Therefore, when a solid image is printed in the complementary image area, the amount of ink applied to that area is 125%.

[0115] Similarly, a mask with a mask rank of 0.75 also has three pairs of masks (1A and 1B, 2A and 2B, and 3A and 3B) to accommodate nozzle shift processing. Adding the allowable data of the mask for nozzle array N10, which corresponds to the image complementation area, and the allowable data of the mask for nozzle array N20 in each pair of masks results in ejection of a total of six pixels. Therefore, when a solid image is formed in the complementation image area, the amount of ink applied to that area is 75%.

[0116] As described above, by using masks of different mask ranks, it is possible to increase or decrease the amount of ink applied to the complementary image area.

[0117] Here, the procedure for selecting a mask that takes into account the nozzle shift as shown in FIG. 12 and the procedure for selecting a mask that takes into account the increase or decrease in the amount of ink applied to the complementary image area will be described with reference to Table 2 below.

[0118] Table 2 shows examples of nozzle shift amounts and mask rank settings for chip-to-chip distances ranging from "+30" to "-30". JPEG0007818968000002.jpg83150

[0119] First, we will explain how to set the nozzle shift amount. The above In this case, as shown in columns A and B of Table 2, the nozzle shift amount is set to "-1" and the nozzle shift is performed by one pixel in the direction in which the adjacent chips move relatively closer to each other. below In this case, the nozzle shift amount is set to "+1" and the nozzle is shifted by one pixel in the direction in which the chips move relatively apart, as shown in columns A and B of Table 2. This nozzle shift process is executed in S93 of FIG.

[0120] Next, the mask selection process will be described. When the chip-to-chip distance after the nozzle shift is "+10" or "-10," a mask for a mask rank of 1.25 or a mask for a mask rank of 0.75 is selected to increase or decrease the amount of ink applied to the complementary image area, as shown in columns C and E of Table 2. That is, when the chip-to-chip distance after the nozzle shift is "+10," slight white streaks tend to be visible, as shown in column D of Table 2. Therefore, the ink application amount is increased to approximately 125% of the standard amount using a mask for mask rank 1.25. This reduces the visibility of white streaks, as shown in column F of Table 2. On the other hand, when the chip-to-chip distance after the nozzle shift is "-10," slight black streaks tend to be visible, as shown in column D of Table 2. Therefore, the ink application amount is reduced to approximately 75% of the standard amount using a mask for mask rank 0.75. This reduces the visibility of black streaks, as shown in column F of Table 2.

[0121] Furthermore, when the chip-to-chip distance is "+30", the nozzle shift amount is "-1", so the chip-to-chip distance is corrected by -20 μm. As a result, the chip-to-chip distance after correction becomes "+10", and slight white streaks are visible in the complement image area, as shown in column D of Table 2. Therefore, a mask rank of 1.25 is selected, Complementary Image Area The ink application amount is increased. This reduces the visibility of white streaks, as shown in column F of Table 2. The masks selected in this case are mask 2A and mask 2B in mask set MS2 for mask rank 1.25, as shown in Figure 13(b). In mask 2A of mask set MS2, mask data corresponding to the complementary image area is set to nozzles 1g and 1h in nozzle array N10. In addition, in mask 2B of mask set MS2, mask data corresponding to the complementary image area is set to nozzles 2b and 2c in nozzle array N20. In masks 2A and 2B of mask set MS2, the mask data corresponding to the complementary image area contains a total of 10 pixels of allowable data. Therefore, when a solid image is printed using nozzle arrays N10 and N20, the ink application amount to the complementary image area is 125%. Increasing the ink application amount to the complementary image area in this way reduces the visibility of even minor white streaks in the complementary image area, resulting in the formation of a higher quality image.

[0122] Furthermore, when the chip-to-chip distance is "-30", the nozzle shift amount is "+1", so the chip-to-chip distance is corrected by +20 μm. As a result, the chip-to-chip distance after correction becomes "-10", and slight black streaks are visible in the complement image area, as shown in column D of Table 2. Therefore, a mask rank of 0.75 is selected, Complementary Image Area This reduces the amount of ink applied. This makes it possible to reduce the visibility of black streaks, as shown in column F of Table 2. The masks to be selected at this time are mask 3A and mask 3B in mask set MS3 for mask rank 0.75, as shown in FIG. 13(c).

[0123] In mask 3A of mask set MS3, mask data corresponding to the complementary image area is set to nozzles 1e and 1f in nozzle array N10. In mask 3B of mask set MS3, mask data corresponding to the complementary image area is set to nozzles 2b and 2c in nozzle array N20. In masks 3A and 3B of mask set MS3, the mask data corresponding to the complementary image area contains a total of six pixels of allowable data. Therefore, when a solid image is printed using nozzle arrays N10 and N20, the amount of ink applied to the complementary image area is 75%. By reducing the amount of ink applied to the complementary image area in this way, it is possible to reduce the visibility of even minor black streaks in the complementary image area, resulting in a higher quality image.

[0124] The setting of the nozzle shift amount and the mask processing according to the mask rank are performed on the overlapping portions of all nozzle rows provided in the print head 8. These processes are executed by the image processing unit 108 shown in FIG. 2 in S95 of FIG.

[0125] After executing the image correction process, the image processing unit 108 of the controller unit 100 generates print data from the corrected print data in a format suitable for printing by the print head 8 (FIG. 6: S66) and transmits it to the print engine unit 200. The print engine unit 200 drives the print head 8 based on the received print data to perform printing on the printing medium S.

[0126] As described above, in this embodiment, mask data is selected taking into consideration the nozzle shift amount determined from the chip-to-chip distance and the chip-to-chip distance after nozzle shift processing. This makes it possible to suppress the occurrence of density unevenness even when the chips in a print head having multiple chips are attached with low precision. In this embodiment, it is possible to suppress the occurrence of density unevenness in both cases where the chip misalignment causes the nozzle-to-nozzle distance to be equal to or greater than the nozzle arrangement interval, and where the nozzle-to-nozzle interval is less than the nozzle arrangement interval, thereby obtaining high-quality images.

[0127] (Second embodiment) Next, a second embodiment of the present invention will be described. In the first embodiment described above, the ink application amount in the complementary image region is increased or decreased based on fixed mask data stored in RAM 106. In this case, depending on the gradation values ​​of the input image, excessive increase or decrease in the ink application amount may be performed, which may actually impair image quality. For example, in the above embodiment, if adjacent chips are arranged with a shift in the direction away from each other, a mask that increases the ink application amount based on the distance between the chips may be selected, even if the image is a low-gradation image (an image with a low ink application amount). In this case, there is a risk that the increased ink application amount will be perceived as a black streak. In other words, white streaks are difficult to see in low-gradation areas where the ink application amount is originally low. However, if a mask that increases the ink application amount is selected for such an image, there is a concern that the increased ink application amount will be perceived as a black streak.

[0128] Furthermore, in the above embodiment, if adjacent chips are arranged with a shift in the direction toward each other, even if the image is a high-gradation image (an image with a large amount of ink applied), there is a possibility that a mask that reduces the amount of ink applied will be selected based on the distance between the chips. black Although the streaks are difficult to see, if a mask that reduces the amount of ink applied is selected for the image, there is a concern that the areas where the amount of ink applied has been reduced will be recognized as white streaks.

[0129] Therefore, in this embodiment, among the multi-value input image data (RGB data) received from the host device 400 and consisting of 8-bit information for each RGB value, pixels corresponding to the complementary image area are subjected to tone correction for each tone.

[0130] Table 3 shows the gradation values ​​of the image to be formed, Gradation In the correction table GradationThe relationship with the correction coefficient is shown. The 256 tone values ​​indicate the darkness assigned to each ink color, with tone value "255" being the darkest and tone value "0" being the lightest. The larger the tone value, the higher the tone, and the smaller the tone value, the lower the tone. Table 3 also shows: Gradation As a correction table, Gradation Correction table T0.8, Gradation Correction table T0.9, Gradation Correction table T1.0, Gradation Correction table T1.1, Gradation The correction table T1.2 is shown. Gradation The larger the number in the correction table T, the larger the correction coefficient. Gradation It is a correction table. Gradation The correction table T1.2 has the largest correction coefficient "1.2", Gradation The correction table T0.8 has the smallest correction coefficient of "0.8".

[0131] If the value of the density correction coefficient is "1.0", no gradation correction is performed. If the value of the density correction coefficient is greater than "1.0" (for example, 1.1), the gradation value of the received image is increased by a specified ratio. If the value of the density correction coefficient is less than "1.0" (for example, 0.9), the gradation value of the received image is decreased by a specified ratio. JPEG0007818968000003.jpg107150

[0132] Next, Table 4 shows an example of the nozzle shift amount, MaskRank, and tone correction table settings corresponding to the chip-to-chip distance. JPEG0007818968000004.jpg108150

[0133] In this embodiment, the chip-to-chip distance listed in column A of Table 4 is obtained, and the nozzle shift amount, MaskRank, and gradation correction table corresponding to the obtained chip-to-chip distance are set. Based on the set values, the ink application amount increase / decrease process in the complementary image region, as performed in the first embodiment, and the gradation correction of the image based on the correction coefficient values ​​of the gradation correction table are performed. This gradation correction is performed between the color conversion process of S62 and the quantization process of S63 in Figure 6. Here, when using mask data that increases the ink application amount in the complementary image region based on the chip-to-chip distance, the gradation value of the complementary image region, which is a high-gradation area, is lowered to reduce the amount of ink applied to the complementary image region. This makes it possible to prevent black streaks from occurring due to an excessive increase in the amount of ink applied.

[0134] Furthermore, when printing a high-gradation image, if mask data is used that reduces the amount of ink applied to the complementary image area, the occurrence of white streaks caused by an excessive reduction in the amount of ink applied can be suppressed by increasing the gradation value of the pixels corresponding to the complementary image area and increasing the amount applied.

[0135] In this embodiment, an example has been shown in which the tone values ​​of print data are corrected, but it is also possible to configure the mask data to be switched in the conveyance direction of the recording medium, and to switch the MaskRank of the mask according to the tone value. (Other embodiments) In the above embodiment, a nozzle shift process is performed based on the chip-to-chip distance, a process of selecting a mask corresponding to the amount of nozzle shift, and a process of increasing or decreasing the amount of ink applied to the complementary image area. Therefore, it is possible to suppress both density unevenness that occurs when the chip-to-chip distance is equal to or greater than the nozzle resolution and density unevenness that occurs when the chip-to-chip distance is less than the nozzle resolution, but this is not limiting. It is also possible to suppress density unevenness that occurs when the chip-to-chip distance is large by performing a nozzle shift process and a process of selecting a mask corresponding to the amount of nozzle shift based on the chip-to-chip distance.

[0136] In the above embodiment, the chip-to-chip distance is stored in memory, and the nozzle shift amount and mask are set based on the read-out chip-to-chip distance, but this is not limiting. The memory may store a nozzle shift amount and mask corresponding to a pre-measured chip-to-chip distance. Furthermore, in step S92, the chip-to-chip distance may be acquired by analyzing an actually printed pattern, as in Patent Document 1.

[0137] In addition, in the above embodiment, an example was shown in which the recording medium transport direction and the nozzle arrangement direction were orthogonal to each other, but this is not limiting. That is, a configuration may be used in which multiple nozzle rows, in which nozzles are arranged at a predetermined angle with respect to a line orthogonal to the recording medium transport direction, are arranged along the nozzle row arrangement direction.

[0138] Furthermore, in the above embodiment, an example was given in which a recording head is provided with a plurality of chips arranged in a staggered pattern, but the arrangement of the chips is not limited to a staggered pattern. For example, a so-called in-line arrangement may be used in which a plurality of chips are arranged linearly along a direction intersecting the transport direction of the recording medium. In this case, the intersecting direction is not limited to a direction perpendicular to the transport direction. In the above embodiment, the planar shape of the chip is a parallelogram, but this is not limited to this and may be, for example, a rectangle, a trapezoid, or other shape. In this way, the shape, arrangement, and nozzle arrangement direction of the plurality of chips can take various forms. However, in any form, the nozzle rows of adjacent chips are arranged in a direction intersecting the transport direction of the recording medium. From the perspective They must be arranged so as to form overlapping portions that overlap each other.

[0139] Furthermore, in the above embodiment, a full-line type printing apparatus has been described as an example in which ink is ejected from a long print head held in a fixed position while the printing medium is continuously transported, but the present invention is not limited to this. The present invention can also be applied to a serial type printing apparatus in which a relatively long print head made up of multiple connected chips is scanned in a direction intersecting the transport direction of the printing medium while printing.

[0140] The present invention 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. [Explanation of symbols]

[0141] 1. Recording device 8 recording head 100 Controller unit (image processing device) 108 Image Processing Unit CH1 1st chip CH2 2nd chip N10 1st nozzle row N20 Second nozzle row OL overlap part S Recording media w First direction y second direction

Claims

1. an image processing device including an image processing means for processing image data in order to record an image on a recording medium by using a recording head in which a first chip having a first nozzle row in which a plurality of nozzles are arranged and a second chip having a second nozzle row in which a plurality of nozzles are arranged, and ejecting the same ink from the first nozzle row and the second nozzle row while scanning the recording head and a recording medium relatively in a first direction, the first chip and the second chip provided on the recording head are arranged so that an area on an end side of the first nozzle row and an area on an end side of the second nozzle row form an overlapping portion where they overlap when viewed from the first direction; The image processing means a first acquisition means for acquiring binary print data in which ejection or non-ejection is determined for each pixel based on multi-value input image data; a second acquisition means for acquiring an inter-nozzle distance, which is an amount of deviation from a standard distance in a second direction perpendicular to the first direction, between a first end nozzle of the first nozzle row and a second end nozzle of the second nozzle row when the first chip and the second chip are properly arranged; an allocation unit that allocates the print data to each nozzle of the first nozzle row and the second nozzle row based on the nozzle-to-nozzle distance; the allocation means performs a shift process to shift an allocation position of the print data for the nozzles from the allocation position when the inter-nozzle distance is the standard distance based on the inter-nozzle distance, and also changes a distribution process to distribute the print data to the nozzles located in the overlapping portion according to the inter-nozzle distance, The image processing device is characterized in that, when the distance in the second direction between the first chip and the second chip is greater than the appropriate distance and the nozzle-to-nozzle distance is smaller than the nozzle arrangement interval, the allocation means performs the distribution process so as to increase the amount of ink applied to the area on the recording medium corresponding to the overlapping portion compared to when the nozzle-to-nozzle distance matches the nozzle arrangement interval.

2. 2. The image processing device according to claim 1, wherein the allocation means shifts the recording data so that the distance in the second direction between the position of a pixel of an image to be formed on the recording medium and the position of the nozzle responsible for forming that pixel is equal to or less than the arrangement interval of the nozzles.

3. 2. The image processing device according to claim 1, wherein the allocation means performs the distribution process so as to complete an image to be recorded in an area on the recording medium corresponding to the overlapping portion using ink ejected from nozzles of the first nozzle row located in the overlapping portion and ink ejected from nozzles of the second nozzle row located in the overlapping portion.

4. An image processing device as described in any one of claims 1 to 3, characterized in that when the distance in the second direction between the first chip and the second chip is smaller than the appropriate distance and the nozzle-to-nozzle distance is smaller than the nozzle arrangement interval, the allocation means performs the distribution processing so as to reduce the amount of ink applied to the area on the recording medium corresponding to the overlapping portion compared to when the nozzle-to-nozzle distance matches the nozzle arrangement interval.

5. An image processing device as described in any one of claims 1 to 3, characterized in that when the distance in the second direction between the first chip and the second chip is greater than an appropriate distance and the distance in the second direction between the position of a pixel of an image to be formed on the recording medium after shifting the recording data by the shift processing and the position of the nozzle responsible for forming the pixel is smaller than the arrangement spacing of the nozzles, the allocation means performs the distribution processing so as to increase the amount of ink applied to the area on the recording medium corresponding to the overlapping portion compared to other cases.

6. An image processing device as described in any one of claims 1 to 3, characterized in that when the distance in the second direction between the first chip and the second chip is smaller than the appropriate distance and the distance in the second direction between the position of a pixel of an image to be formed on the recording medium after shifting the recording data by the shift processing and the position of the nozzle responsible for forming the pixel is smaller than the arrangement spacing of the nozzles, the allocation means performs the distribution processing so as to reduce the amount of ink applied to the area on the recording medium corresponding to the overlapping portion compared to other cases.

7. An image processing device according to any one of claims 1 to 6, characterized in that the allocation means performs complementary recording using the first nozzle row and the second nozzle row for a complementary image area defined in an image area corresponding to the overlapping portion, while performing the distribution process so as to record an image using either the first nozzle row or the second nozzle row for an area other than the complementary image area.

8. 8. The image processing device according to claim 7, wherein the allocation unit performs the distribution process so as to increase or decrease the amount of ink applied to the complementary image area in accordance with the nozzle distance compared to the amount of ink applied to an area other than the complementary image area.

9. The image processing means a first storage means for storing the inter-nozzle distance; a second storage means for storing a plurality of masks made up of mask data indicating whether ink ejection from the nozzles is permitted or not permitted, 9. The image processing device according to claim 1, wherein the allocating unit sets a shift amount for performing the shift processing based on the inter-nozzle distance acquired from the first storing unit, selects a predetermined mask from among the plurality of masks in accordance with the shift amount, and performs the distribution processing using the selected mask.

10. the second storage means includes a plurality of masks ranked according to whether the inter-nozzle distance is equal to the arrangement interval of the nozzles, whether the inter-nozzle distance is greater than the arrangement interval of the nozzles, or whether the inter-nozzle distance is smaller than the arrangement interval of the nozzles, 10. The image processing device according to claim 9, wherein the allocation means selects a rank according to the distance in the second direction between the position of a pixel of the image to be formed on the recording medium after the shift process and the position of the nozzle responsible for forming the pixel, and performs the distribution process using a mask corresponding to the selected rank.

11. further comprising a control means for controlling the gradation value of the input image data; The image processing device described in claim 9 or 10, characterized in that the control means, when the mask for increasing the amount of ink applied to the recording medium by the nozzles located in the overlapping portion is selected, reduces the gradation value of the high gradation portion of the input image data, and, when the mask for decreasing the amount of ink applied to the recording medium by the nozzles located in the overlapping portion is selected, increases the gradation value of the low gradation portion of the input image data.

12. an image processing method for processing image data in order to record an image on a recording medium by using a recording head in which a first chip having a first nozzle row in which a plurality of nozzles are arranged and a second chip having a second nozzle row in which a plurality of nozzles are arranged are arranged so that an area on an end side of the first nozzle row and an area on an end side of the second nozzle row overlap when viewed from a first direction, and ejecting the same ink from the first nozzle row and the second nozzle row while scanning the recording head and a recording medium relatively in the first direction, a first acquisition step of acquiring binary print data in which ejection or non-ejection is determined for each pixel based on multi-value input image data; a second acquisition step of acquiring an inter-nozzle distance, which is an amount of deviation from a standard distance in a second direction perpendicular to the first direction, between a first end nozzle of the first nozzle row and a second end nozzle of the second nozzle row when the first chip and the second chip are properly arranged; an allocating step of allocating the print data to each nozzle of the first nozzle row and the second nozzle row based on a distance between nozzles, the allocating step performs a shift process to shift an allocation position of the print data for the nozzles from the allocation position when the inter-nozzle distance is the standard distance based on the inter-nozzle distance, and also changes a distribution process to distribute the print data to the nozzles located in the overlapping portion according to the inter-nozzle distance, The allocation process is an image processing method characterized in that, when the distance in the second direction between the first chip and the second chip is greater than an appropriate distance and the nozzle-to-nozzle distance is smaller than the nozzle arrangement interval, the distribution process is performed so as to increase the amount of ink applied to the area on the recording medium corresponding to the overlapping portion compared to when the nozzle-to-nozzle distance matches the nozzle arrangement interval.

13. A program for causing a computer to execute the steps recited in claim 12.

Images