JP6448315B2 - Inkjet recording apparatus and recording control method - Google Patents

Description

  The present invention relates to an ink jet recording apparatus and a recording control method for performing multipass recording.

  Conventionally, in an ink jet recording apparatus that performs multi-pass recording, when one or more malfunctioning printing elements (hereinafter, elements are referred to as ejection ports or nozzles) are identified, the print mask data is corrected. It has been known. In Patent Document 1, when the malfunctioning nozzle is non-zero entry (recording), another print nozzle that processes a specific pixel position that is zero entry (non-recording) is found. The found print nozzle is then replaced with a non-zero entry for the malfunctioning nozzle.

Japanese Patent Laid-Open No. 2003-175592

  However, in Patent Document 1, the above replacement cannot be performed when there is no other nozzle that is zero entry (non-recording) for replacement. The case where there is no other nozzle that is zero entry (non-recording) may be in the following case. For example, when a plurality of dots are recorded at a specific pixel position by low-pass printing with a small number of passes, the possibility increases. In addition, for example, when there are a plurality of malfunctioning nozzles and the number of other nozzles that are zero entry (non-recording) is smaller than the malfunctioning nozzles, the above possibility is increased.

  An object of the present invention is to solve such conventional problems. The present invention provides an ink jet recording apparatus and a recording control method that appropriately set ejection / non-ejection data even when there are no non-ejection nozzles instead of malfunctioning nozzles in view of the above points. With the goal.

In order to solve the above problems, an ink jet recording apparatus according to the present invention performs ink jet recording in which a recording head having a plurality of nozzles is scanned a plurality of times with respect to an area corresponding to one pixel and one pixel is recorded with a plurality of recording dots. The apparatus is based on image data that expresses one pixel by a pixel value of n bits (n ≧ 2), and corresponds to the recording head corresponding to the pixel value, and the recording head corresponds to the pixel. A recording control unit that performs recording by scanning the region a plurality of times, a pixel value that can be taken by the one pixel, and a correspondence relationship between the pixel value and each ink droplet of the plurality of nozzles in each of the plurality of times of scanning for determining the ejection / non-ejection, storage means for storing a code value represented by m bits (m ≧ 2 integer), if the ejection failure occurs in any of said plurality of nozzles Among the plurality of nozzles, nozzle and determining means for determining an alternative nozzle of a nozzle in which the discharge failure has occurred, the code value corresponding to the alternate nozzles determined by the determination means, that the ejection failure occurs Setting means for setting based on the code value corresponding to the number of pixel values determined to eject ink droplets by the code value corresponding to the alternative nozzle in the correspondence relationship. When the number of pixel values determined to eject ink droplets by the code value corresponding to the nozzle in which the ejection failure has occurred in the correspondence relationship, the code value corresponding to the alternative nozzle is not changed, and In the correspondence relationship, the number of pixel values determined to eject ink droplets by the code value corresponding to the alternative nozzle is the previous number. If the in correspondence discharge failure is not more than the number of pixel values determined to discharge ink droplets by the code value corresponding to the nozzle occurs, the code values corresponding to the nozzle in which the discharge failure has occurred It is set as the code value corresponding to the alternate nozzle, characterized in that.

  According to the present invention, it is possible to appropriately set ejection / non-ejection data even when there is no non-ejection nozzle in place of a malfunctioning nozzle.

1 is a block diagram illustrating a schematic configuration of a recording control system of an inkjet recording apparatus. FIG. 3 is a perspective view illustrating a configuration around a recording head. FIG. 3 is a diagram illustrating a nozzle array configuration of a recording head. It is a figure which shows the block configuration of a recording control part. It is a figure for demonstrating the 4 multipass recording method. It is a figure which shows a decoding table. It is a figure which shows each data of the 1st path | pass. It is a figure which shows each data in 2nd-4th pass. It is a figure which shows the result recorded by the recording data produced | generated by FIG.7 and FIG.8. It is a figure which shows each data when there exists a malfunctioning nozzle. It is a figure which shows the number of dots of each pixel position when there exists a malfunctioning nozzle. It is a flowchart which shows the procedure of the correction process of print mask data. It is a figure which shows the print mask data before correction and after correction. It is a figure which shows the recording data produced | generated with the print mask data after correction. It is a figure which shows the number of dots of each pixel position by the print mask data after correction. It is a figure for demonstrating the correction effect of print mask data. It is a flowchart which shows the procedure of the correction process of print mask data. It is a figure which shows a decoding table. It is a flowchart which shows the procedure of the correction process of print mask data. It is a figure for demonstrating the correction effect of print mask data. It is a figure for demonstrating the correction effect of print mask data. It is a figure which shows a decoding table.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments do not limit the present invention according to the claims, and all combinations of features described in the embodiments are not necessarily essential to the solution means of the present invention. . The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.

[First Embodiment]
FIG. 1 is a block diagram showing a schematic configuration of a recording control system of the ink jet recording apparatus. The inkjet recording apparatus 100 is connected to an external host computer (host PC) 108 via an interface 107 so as to be able to communicate with each other. The host PC 108 is a data supply device and transmits image data to be recorded, control commands, and the like to the inkjet recording device 100. Various data and control commands transmitted from the host PC 108 are input to the recording control unit 101 of the inkjet recording apparatus 100. The recording control unit 101 controls a recording unit (printer engine) such as the recording head 111 so as to perform recording based on the input image data. The recording control unit 101 performs various image processing (color space conversion, resolution conversion, binarization processing, etc.) for converting the image data transmitted from the host PC 108 into recording data. The recording control unit 101 includes a memory 110 that stores print mask data to be described later, a CPU 109 (which may be an ASIC), a ROM, and a RAM. The CPU 109 comprehensively controls each unit of the ink jet recording apparatus 100 and controls the motor drivers 102 to 103 and the recording head driver 106 in accordance with a control command input via the interface 107, for example.

  The conveyance motor 104 is a conveyance motor for rotating a conveyance roller 202 that conveys a recording medium 201 such as printing paper. The carriage motor 105 is a carriage motor for reciprocating the carriage 205 on which the recording head 111 is mounted in the main scanning direction. Here, the main scanning direction is a direction that intersects the conveyance direction of the recording medium 201. Motor drivers 102 and 103 are drivers for driving the transport motor 104 and the carriage motor 105, respectively. The recording head driver 106 is a driver for driving the recording head 111, and a plurality of recording head drivers 106 may be provided corresponding to the number of recording heads. The recording head driver 106 includes various control circuits such as a selector and a decoder for controlling the supply voltage to the heater provided in the nozzle. The recording control unit 101 and the recording head driver 106 are connected by, for example, a flexible cable.

  FIG. 2 is a perspective view showing a configuration around the recording head 111 of the inkjet recording apparatus 100. The recording head 111 in this embodiment is a so-called serial type recording head that performs recording by ejecting ink droplets from nozzles while scanning in a direction X that intersects the conveyance direction Y of the recording medium 201. In the present embodiment, for example, the ink tanks 206 to 209 store four colors of ink (black, cyan, magenta, yellow: CMYK), respectively, and these four colors of ink are stored in the recording heads 210 to 213. It can be supplied. The recording heads 210 to 213 are provided so as to correspond to the four color ink tanks 206 to 209 and are configured to be able to discharge ink supplied from the ink tanks 206 to 209 from nozzles (discharge ports). The recording heads 210 to 213 correspond to the recording head 111 in FIG. Hereinafter, the recording heads 210 to 213 may be collectively referred to as the recording head 111.

  The conveying roller 202 rotates while sandwiching the recording medium 201 together with the auxiliary roller 203 to convey the recording medium 201 and also has a role of holding the recording medium 201. The carriage 205 can mount ink tanks 206 to 209 and recording heads 210 to 213, and these recording heads and ink tanks are mounted so as to be reciprocally movable along the main scanning direction X. An image is recorded on the recording medium 201 by ejecting ink droplets from the nozzles of the recording heads 210 to 213 during the reciprocating movement of the carriage 205. During a non-recording operation such as a recovery operation of the recording heads 210 to 213, the carriage 205 is controlled to stand by at a home position h indicated by a dotted line in the drawing.

  When the recording heads 210 to 213 waiting in the home position h shown in FIG. 2 receive the recording start command, the recording heads 210 to 213 move in the main scanning direction X together with the carriage 205 to eject ink droplets and image onto the recording medium 201. Record. By one movement (scanning) of the recording heads 210 to 213, recording is performed on an area having a width corresponding to the nozzle arrangement range (arranged in the direction intersecting the main scanning direction X) of the recording heads 210 to 213. Is called. When the recording associated with one scan of the carriage 205 in the main scanning direction X is completed, the carriage 205 returns to the home position h and performs recording by the recording heads 210 to 213 while scanning in the main scanning direction X again. The conveyance roller 202 rotates and the recording medium 201 is conveyed in the sub-scanning direction Y intersecting with the main scanning direction X from the end of the previous recording scan to the start of the subsequent recording scan. Thus, an image is recorded on the entire surface of the recording medium 201 by repeating the recording scanning of the recording heads 210 to 213 and the conveyance of the recording medium 201. The ejection operation for ejecting ink droplets from the nozzles of the recording heads 210 to 213 is performed under the control of the recording head driver 106 by the recording control unit 101.

  In the above description, the case where so-called one-way recording is performed, in which the recording operation is performed only when the recording head 111 scans in the forward direction, has been described. However, the recording head 111 may perform so-called bidirectional recording in which recording is performed both when scanning in the forward direction and when scanning in the backward direction. In the above description, the configuration in which the ink tanks 206 to 209 and the recording heads 210 to 213 are detachably mounted on the carriage 205 is shown. However, a cartridge in which the ink tanks 206 to 209 and the recording heads 210 to 213 are integrated may be mounted on the carriage 205. Furthermore, a configuration in which a recording head of a plurality of color integrated types capable of discharging a plurality of colors of ink from one recording head is mounted on the carriage 205 may be employed.

  FIG. 3 is a diagram illustrating an example of a nozzle array configuration of the recording heads 210 to 213. A nozzle 301 indicates an ink droplet ejection port, and each recording head has 16 nozzles arranged in a row. In the present embodiment, the number of nozzles and the number of nozzle rows are determined as shown in FIG. 3, but the number of nozzles and the number of nozzle rows shown in FIG.

  FIG. 4 is a diagram illustrating a block configuration related to print mask control of the recording control unit 101. The CPU 109 and the memory 110 are connected via the bus 404. The memory 110 stores image data 401 to be recorded, print mask data 402 described later, and malfunctioning nozzle data 403. The CPU 109 reads each data from the memory 110 and corrects the print mask data 402 corresponding to the malfunctioning nozzle. The ROM 405 stores a program executed by the CPU 109 and the like. The RAM 406 is used as a working memory for the CPU 109. The CPU 109 reads out and executes the program stored in the ROM 405, thereby realizing the operation of each embodiment.

  FIG. 5 is a diagram for explaining, as an example, a four-multipass printing method in which the number of scans is four out of multipass printing in which one recording target region is scanned a plurality of times. The print mask data 500 is used when generating recording data for recording by discharging ink droplets from the nozzles from the image data 401. The X direction in FIG. 5 corresponds to the main scanning direction X in FIG. 2, and the Y direction corresponds to the transport direction (sub-scanning direction) Y in FIG. As shown in FIG. 5, the size of the print mask data 500 corresponds to 4 pixels in the X direction and the number of pixels corresponding to the number of nozzles in the Y direction. That is, the print mask data 500 is data having a size corresponding to 4 pixels × 16 pixels. Since the print mask data 500 is associated with each nozzle position of the recording head 111, if the relative position of the recording head 111 with respect to the recording medium 201 is changed, the print mask data 500 is relative to the recording medium 201. The position also changes.

  Although multi-pass printing is performed by transporting the recording medium 201, FIG. 5 shows relative movement of the recording head 111 and the print mask data 402 as viewed from the recording medium 201 for explanation. That is, the relative positions of the recording head 111 and the print mask data 402 with respect to the recording medium 201 change from the position 501 to the position 504.

  First, at a position 501, the recording head 111 is scanned in the X direction, thereby recording an area 510 on the recording medium 201. At that time, print data is generated from the data corresponding to the area 505 of the print mask data 402 and the image data 401. This is the first pass recording. Thereafter, the recording medium 201 is conveyed, and the relative positions of the recording head 111 and the print mask data 402 with respect to the recording medium 201 are set to a position 502 shifted by “−4” pixels in the Y direction. While the recording medium 201 is being conveyed, the recording head 111 is located at the home position h.

  Next, at the position 502, the recording head 111 is scanned in the X direction, thereby recording the area 510 on the recording medium 201. At that time, print data is generated from the data corresponding to the area 506 of the print mask data 402 and the image data 401. This is the second pass recording.

  As described above, the recording medium 201 is transported, and the recording head 111 is scanned in the X direction at the position 503 to record the area 510 on the recording medium 201. At that time, print data is generated from the data corresponding to the area 507 of the print mask data 402 and the image data 401. This is the third pass recording.

  Further, the recording medium 201 is conveyed as described above, and the recording head 111 is scanned in the X direction at the position 504, thereby recording the area 510 on the recording medium 201. At that time, print data is generated from the data corresponding to the area 508 of the print mask data 402 and the image data 401. This is the fourth pass recording. By performing the recording from the first pass to the fourth pass, the image in the area 501 is completed. In the above description, four multi-pass printing has been described, but the number of passes may not be four. Further, the number of pixels may differ depending on the number of passes, and the size of the print mask data 402 is not limited to the size shown in FIG.

  Processing for generating recording data from the image data 401 and the print mask data 402 will be described with reference to FIGS. 6 and 7. In the present embodiment, the image data 401 and the print mask data 402 are both 1-pixel n-bit (n is an integer of 2 or more) data. Hereinafter, description will be made assuming that one pixel is 2 bits as an example. In the present embodiment, “recording” or “non-recording” (ejection / non-ejection) for the target pixel is determined based on the decoding table shown in FIG. 6 from the combination of the pixel values of the image data 401 and the print mask data 402. The

  FIG. 6 is a diagram illustrating an example of a decoding table (code information). The vertical axis in FIG. 6 indicates the pixel value of the image data 401, and the horizontal axis indicates the code value of the print mask data 402. In FIG. 6, “◯” marks indicate “recording” (ejection) in which ink droplets are ejected from the nozzles of the recording head 111, and “x” marks indicate that no ink droplets are ejected from the nozzles of the recording head 110 “Non-recording” (non-ejection). For example, in FIG. 6, if the code value of the print mask data 402 is “00” for the pixel value “00” of the image data 401, no ink droplet is ejected.

  The relationship between the pixel value of the image data 401 and ink droplet ejection will be described. A pixel value “00” means that no ink droplet is ejected to the pixel. The pixel value “01” means that one dot of ink droplet is ejected to the pixel. The pixel value “10” means that two dots of ink droplets are ejected to the pixel. The pixel value “11” means that 3 dots of ink droplets are ejected to the pixel.

  Referring to the decoding table of FIG. 6, for the pixel value “00” of the image data 401, ink droplets are not ejected regardless of the code value of the print mask data 402. For the pixel value “01” of the image data 401, ink droplets are ejected only when the code value “11” of the print mask data 402 is set (recording of one dot). For the pixel value “10” of the image data 401, ink droplets are ejected in the case of the code values “10” and “11” of the print mask data 402 (2-dot recording). For the pixel value “11” of the image data 401, ink droplets are ejected in the case of the code values “01”, “10”, and “11” of the print mask data 402 (3-dot recording).

  That is, the code values of the print mask data 402 in the decoding table of FIG. 6 are assigned four types of unique code values in the case of 4 multi-pass printing. In the case of 4-multipass printing, four types of unique code values of print mask data are assigned to each pixel in order. At that time, ink droplets are ejected as described above based on the decoding table as shown in FIG. 6 and the pixel values of the image data. In the case of 4-multipass printing, the print mask data 402 is data of 2 bits per pixel in order to assign four types of unique code values. In general, the code value is m-bit (m ≧ 2) data regardless of the number of passes.

  FIG. 7 is a diagram showing image data 401 and print mask data 402 at the position 501 (first pass recording) of the recording head 111 and recording data. Here, for the sake of explanation, it is assumed that the image data 401 has a size of 4 pixels in both the X direction and the Y direction. When the image data 401 is larger than 4 pixels in the X direction, the print mask data 402 is repeatedly used in units of 4 pixels in the X direction. FIG. 7A shows each pixel position, and all the pixel positions of pixels 700 to 715 are shown. FIG. 7B shows image data 401, FIG. 7C shows print mask data 402, and FIG. 7D shows print data.

  Description will be made by paying attention to the pixel position 700. As shown in FIG. 7B, the pixel value of the image data 401 is “11”. This means that 3 dots are recorded at the pixel position 700 as described above. As shown in FIG. 7C, the code value of the print mask data 402 is “11”. Therefore, referring to the decoding table in FIG. 6, since the mark is “◯” indicating recording, the recording data is “1” indicating “recording”. Similarly, recording “1” or non-recording “0” is determined for all the pixel positions 701 to 715 with reference to the decoding table of FIG. 6, and the recording data shown in FIG. 7D is generated. .

  FIG. 8 is a diagram showing image data 401 and print mask data 402 and recording data at positions 502 (second pass recording) to 504 (fourth pass recording) of the recording head 111. FIG. 8A shows data corresponding to the area 506 of the print mask data 402 at the position 502 and generated print data. FIG. 8B shows data corresponding to the area 507 of the print mask data 402 at the position 503 and print data to be generated. FIG. 8C shows data corresponding to the area 508 of the print mask data 402 at the position 504 and print data to be generated.

  FIG. 9 is a diagram illustrating a result recorded by the recording data generated in FIGS. 7 and 8. The number in the frame indicates the number of dots recorded in each pixel. Compared with the image data 401 in FIG. 7B, it can be seen that 3 dots are recorded for the pixel value “11”. It can also be seen that 2 dots are recorded for the pixel value “10”. It can also be seen that one dot is recorded for the pixel value “01”. Further, it can be seen that the pixel value “00” is recorded as 0 dots (that is, not recorded). As described above, recording of 0 to 3 dots corresponding to the image data is performed by 4-multipass printing for each of the pixel positions 700 to 715.

  As can be seen from the print mask data 402 in FIG. 7 and FIG. 8, “00”, “01”, “10”, “11” at the pixel positions 700 to 715 in the areas 505 to 508 of the print mask data 402 used in this embodiment. "Is set one by one. Thereby, in the 4-multipass printing, the dot value is recorded only when the pixel value “01” of the image data 401 is the code value “11” of the print mask data 402 (the number of times of ejection is one), and the one-dot recording Is possible. For the pixel value “10” of the image data 401, since dots are recorded when the code values “10” and “11” of the print mask data 402 (the number of ejections is two), two-dot recording is possible. Become. Further, with respect to the pixel value “11” of the image data 401, dots are recorded when the code values “01”, “10”, and “11” of the print mask data 402 (the number of ejections is three), and three-dot recording is performed. It becomes possible. As described above, 1 to 3 dots can be recorded according to the pixel value of the image data 401.

  Next, the case where there is a malfunctioning nozzle such as ejection failure will be described with reference to FIG. FIG. 10 is a diagram showing print mask data 402 and generated print data when there is a malfunctioning nozzle. The decoding table, image data, and print mask data used are the same as those shown in FIGS. FIG. 10A shows the position of the discharge failure nozzle. FIG. 10B shows print mask data 402 and print data to be generated in the first pass printing. FIG. 10C shows the print mask data 402 and the generated print data in the second pass printing. FIG. 10D shows print mask data 402 and print data to be generated in the third pass printing. FIG. 10E shows print mask data 402 and print data to be generated in the fourth pass printing.

  A nozzle 1001 in FIG. 10A indicates a malfunctioning nozzle that has failed to discharge. Since the nozzle 1001 has failed to discharge, recording cannot be performed for the row 1002 in the data corresponding to the area 505 of the print mask data 402. That is, all the data of the first pass of the pixel positions 704 to 707 corresponding to the record data row 1003 in FIG. 10B are not recorded. If the nozzle 1001 is not discharged, the row 1003 is recorded as “0” “1” “0” “0” as shown in FIG. However, since the nozzle 1001 does not discharge, the row 1003 is not actually recorded, the number of dots at each pixel position 700 to 715 is as shown in FIG. 11, and the number of dots 1100 at the pixel position 705 is originally 2. It should be 1 as it should be.

  FIG. 12 is a flowchart showing the procedure of the correction process of the print mask data 402 in the present embodiment. Each process illustrated in FIG. 12 is realized, for example, by the CPU 109 reading out a program stored in the ROM 405 to the RAM 406 and executing the program.

  In step S1201, the CPU 109 reads the malfunctioning nozzle data 403 from the memory 110, acquires information about the malfunctioning nozzle, and identifies the malfunctioning nozzle. The malfunction nozzle data 403 describes information for identifying malfunction nozzles due to non-ejection or the like. For example, the malfunctioning nozzle may be specified based on information detected in a recovery operation or the like of the recording head 111 at the home position h.

  In step S1202, the CPU 109 acquires print mask data A corresponding to the specified malfunctioning nozzle. Here, the print mask data A is, for example, print mask data corresponding to the area 1002 in FIG. In step S <b> 1203, the CPU 109 acquires print mask data B corresponding to another alternative nozzle for which a code value is to be set. The selection of the alternative nozzle will be described later.

  In step S1204, the CPU 109 refers to the decoding table in FIG. 6 and, for one of the pixels corresponding to the malfunctioning nozzle, the number of dots α that the print mask data A can be recorded and the number of dots that the print mask data B can record. β and get. In S1205, the CPU 109 compares the dot number α acquired in S1204 with the dot number β, and determines whether α is smaller than β. If it is determined that α is smaller than β, the process proceeds to S1207. If it is determined that α is not smaller than β, the process proceeds to S1206.

  In step S1206, the CPU 109 employs the code value of the print mask data A as the code value of the replacement print mask data B corresponding to the pixel to be processed. On the other hand, in S1207, the CPU 109 adopts the code value of the print mask data B as it is as the code value of the replacement print mask data B corresponding to the pixel to be processed.

  In step S1208, the CPU 109 determines whether or not the determination process in step S1205 has been performed for all the pixels of the print mask data A acquired in step S1202. Here, if it is determined that the determination process of S1205 has been performed for all pixels, the process of FIG. 12 ends. On the other hand, if it is determined that the determination process of S1205 has not been performed for all pixels, another pixel is selected and the process from S1205 is repeated.

  FIG. 13A is a diagram showing print mask data of FIGS. 10B to 10E (that is, before correction). FIG. 13A shows a pixel position to be replaced. Black frame data 1002 in the area 505 of the print mask data 402 is mask data corresponding to a malfunctioning nozzle. Since data 1002 is a malfunctioning nozzle, recording is not actually performed. Therefore, the code value of the print mask data corresponding to other alternative nozzles is corrected (set), and the number of dots to be ejected by the malfunctioning nozzle is interpolated.

  FIG. 13A shows code values corresponding to the pixel positions to be set in the regions 506, 507, and 508. FIG. The pixel position to be set corresponds to the alternative nozzle. In the present embodiment, for the pixel position 704 corresponding to the malfunctioning nozzle, the code value of the corresponding pixel position 1301 in the region 506 is selected as the setting target. For the pixel position 705 corresponding to the malfunctioning nozzle, the code value of the corresponding pixel position 1302 in the region 507 is selected as the setting target. For the pixel position 706 corresponding to the malfunctioning nozzle, the code value of the corresponding pixel position 1303 in the region 508 is selected as the setting target. For the pixel position 707 corresponding to the malfunctioning nozzle, the code value of the corresponding pixel position 1304 in the region 506 is selected as the setting target. As long as the pixel position to be set is a nozzle other than the malfunctioning nozzle among a plurality of nozzles corresponding to each scan (four nozzles in the case of four passes), the selection method may be arbitrary. For example, if there is a code value smaller than the code value of the pixel position corresponding to the malfunctioning nozzle, the nozzle corresponding to the pixel position of the code value may be determined as an alternative nozzle. In that case, as shown in FIG. 16 described later, the probability of correction to the normal number of recording dots increases.

  FIG. 13B shows print mask data after the code value is set (that is, after correction). Hereinafter, the pixel position 705 will be described. In S1202 of FIG. 12, the code value “11” of the print mask data corresponding to the pixel position 705 in the region 505 is acquired. In S1203 of FIG. 12, the code value “01” of the print mask data corresponding to the pixel position 705 in the region 507 is acquired.

  In S1204 of FIG. 12, the printable dot number α of the print mask data corresponding to the pixel position 705 in the area 505 is compared with the printable dot number β of the print mask data corresponding to the pixel position 705 in the area 507. . Here, the code value “11” of the print mask data corresponding to the pixel position 705 in the region 505 is recorded for the pixel values “01”, “10”, and “11” of the image data 401 in the decoding table of FIG. Is set to Therefore, the recordable dot number α (the number of ejections) is 3. Also, the code value “01” of the print mask data corresponding to the pixel position 705 in the area 507 is set to record the pixel value “11” of the image data 401 in the decoding table of FIG. Accordingly, the recordable dot number β (the number of ejections) is 1. Therefore, as a result of the comparison in S1204, it is determined that α is larger than β, and the process proceeds to S1206.

  When one pixel of image data is represented by a pixel value of n bits (n ≧ 2), the number of possible pixel values is 2n. In the determination of S1205, the code value of the defective nozzle and the code value of the alternative nozzle to be set are compared, and the one with the larger number of times of ejecting ink droplets for 2n pixel values is determined. Adopt as code value. By such an operation, it is possible to prevent an excessive ink droplet having an appropriate number of recording dots or more determined by the pixel value of one pixel to be recorded from being ejected from the alternative nozzle.

  In S1206, the code value “11” of the print mask data A is adopted as the code value of the print mask data B corresponding to the pixel to be processed. That is, the code value “01” of the print mask data B is corrected to the code value “11” of the print mask data A. Similar processing is performed for the pixel positions 1301, 1303, and 1304. As a result, as shown in FIG. 13B, the code values of the pixel positions are corrected to “11”, “11”, and “01”.

  As shown in the data 1002 in FIG. 13B, the code values of the print mask data A corresponding to the malfunctioning nozzle are all set to “00”. However, other methods may be used as long as the ink droplets are set not to be ejected from the malfunctioning nozzle.

  FIG. 14 is a diagram showing print data generated from the image data 401 of FIG. 7B using the corrected print mask data 402 shown in FIG. 13B. As shown in FIG. 14, the pixel position 1400 was “recorded” before the nozzle malfunctioned, but the pixel position 1400 was “not recorded” due to malfunction. In the original state where there is no malfunction, the total number of dots recorded by the pixel position 1400 and the pixel position 1402 should be two. However, since the recording is not performed at the pixel position 1400 due to an operation failure, the total number of dots is 1, as shown in FIG.

  However, by using the print mask data modified as shown in FIG. 13B by the processing shown in FIG. 12, the pixel position 1401 was set to “non-recording”, but changed to “recording”. Yes. As a result, the total number of dots to be recorded can be originally set to 2 by the pixel position 1402 and the pixel position 1401 as shown in the pixel position 1500 in FIG.

  FIG. 16 is a diagram for explaining the effect of correcting print mask data by all combinations of code values for print mask data corresponding to malfunctioning nozzles and print mask data corresponding to setting target nozzles.

  The first column of FIG. 16 shows code values “00”, “01”, “10”, and “11” of print mask data assigned to a predetermined pixel position for 4-multipass printing. The second column shows the code value of the print mask data corresponding to the malfunctioning nozzle. The third column shows the code value of the print mask data corresponding to the setting target nozzle. The fourth column shows the code values of the print mask data for the remaining three passes after the print mask correction. The fifth to tenth columns indicate the number of recorded dots before and after the correction of the print mask data for the pixel values “01”, “10”, and “11” of each image data.

  The line 1601 will be described. A row 1601 is a case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “00” and the code value of the print mask data B of the setting target nozzle is “01”. In this case, from the decoding table of FIG. 6, the printable dot number α of the print mask data A is 0, and the printable dot number β of the print mask data B is 1. Accordingly, the process proceeds to S1207 as a result of the determination in S1205 in FIG. 12, and the code value of the print mask data B of the setting target nozzle is corrected to “01” (although it is a correction, there is no change in this case). Accordingly, the code values “00”, “01”, “10”, and “11” of the print mask data A in the first to fourth passes become code values “00”, “01”, “10”, and “11”. The code values of the print mask data for the passes are “01”, “10”, and “11”.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “01”, the pixel value “01” of the image data and the code values “00” “01” “10” of the print mask data before correction. From the combination with “11”, the number of dots to be recorded is one. In addition, after the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before the correction, the number of dots to be recorded is 2 from the combination of the pixel value “10” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. In addition, after the correction, the number of dots to be recorded is 2 from the combination of the pixel value “10” of the image data and the code values “00” “01” “10” “11” of the print mask data.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “11”, the pixel value “11” of the image data and the code values “00” “01” “10” of the print mask data before correction. From the combination with “11”, the number of dots to be recorded is three. After the correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data.

  The lines 1602 and 1603 will be described. Lines 1602 and 1603 are cases where the code value of the print mask data A corresponding to the malfunctioning nozzle is “00” and the code value of the print mask data B of the setting target nozzle is “10” or “11”. is there. In this case, from the decoding table of FIG. 6, the printable dot number α of the print mask data A is 0, and the printable dot number β of the print mask data B is 2 or 3. Accordingly, the process proceeds to S1207 according to the determination in S1205 of FIG. 12, and the code value of the print mask data B of the setting target nozzle is corrected to “10” or “11” (although it is a correction, there is no change in this case). Accordingly, the code values “00”, “01”, “10”, and “11” of the print mask data A in the first to fourth passes become code values “00”, “01”, “10”, and “11”. The code values of the print mask data for the passes are “01”, “10”, and “11”.

  Similar to the line 1601, in the lines 1602 and 1603, the combinations of code values for four passes of the corrected print mask data are the same as before the correction. This is because the code value of the print mask data A corresponding to the malfunctioning nozzle is “00”, and any code value of the print mask data B corresponding to the other nozzles can be printed. This is because the code value of the mask data A is never adopted.

  Therefore, when the pixel value of the image data is “01”, the number of dots to be recorded is 1 before and after the correction. When the pixel value of the image data is “10”, the number of dots recorded before and after the correction is two. When the pixel value of the image data is “11”, the number of dots recorded before and after the correction is 3.

  The line 1604 will be described. A row 1604 is a case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “01” and the code value of the print mask data B of the setting target nozzle is “00”. In this case, from the decoding table of FIG. 6, the printable dot number α of the print mask data A is 1, and the printable dot number β of the print mask data B is 0. Therefore, the process proceeds to S1206 according to the determination in S1205 of FIG. 12, and the code value of the print mask data B of the setting target nozzle is corrected to “01”. Accordingly, the code values “00”, “01”, “10”, and “11” of the print mask data A in the first to fourth passes become the code values “01”, “01”, “10”, and “11”. The code values of the print mask data for the passes are “01”, “10”, and “11”.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “01”, the pixel value “01” of the image data and the code values “00” “01” “10” of the print mask data before correction. From the combination with “11”, the number of dots to be recorded is one. In addition, after the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “01”, “01”, “10”, and “11” of the print mask data.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “10”, the pixel value “10” of the image data and the code values “00” “01” “10” of the print mask data are before correction. From the combination with “11”, the number of dots to be recorded is two. In addition, after the correction, the number of dots to be recorded is 2 from the combination of the pixel value “10” of the image data and the code values “01”, “01”, “10”, and “11” of the print mask data.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Actually, it is 2 because of a defective nozzle. However, after the correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “01”, “01”, “10”, and “11” of the print mask data.

  The line 1605 will be described. A line 1605 is a case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “01” and the code value of the print mask data B of the setting target nozzle is “10”. In this case, from the decoding table of FIG. 6, the printable dot number α of the print mask data A is 1, and the printable dot number β of the print mask data B is 2. Accordingly, the process proceeds to S1207 as a result of the determination in S1205 of FIG. Accordingly, the code values “00”, “01”, “10”, and “11” of the print mask data A in the first to fourth passes become code values “00”, “01”, “10”, and “11”. The code values of the print mask data for the pass are “00”, “10”, and “11”.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “01”, the pixel value “01” of the image data and the code values “00” “01” “10” of the print mask data before correction. From the combination with “11”, the number of dots to be recorded is one. In addition, after the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “10”, the pixel value “10” of the image data and the code values “00” “01” “10” of the print mask data are before correction. From the combination with “11”, the number of dots to be recorded is two. In addition, after the correction, the number of dots to be recorded is 2 from the combination of the pixel value “10” of the image data and the code values “00” “01” “10” “11” of the print mask data.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Due to the defective nozzle, the number of dots actually recorded is two. Further, after the correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00” “01” “10” “11” of the print mask data. Actually, it becomes 2.

  Similar to the line 1605, also in the line 1606, the combination of code values for four passes of the corrected print mask data is not changed from that before the correction. This is because the code value of the print mask data A corresponding to the malfunctioning nozzle is “01”. Even if the code value of the print mask data B is “10” or “11”, the print mask data A This is because the code value of is not adopted.

  Therefore, when the pixel value of the image data is “01”, the number of dots to be recorded is 1 before and after the correction. When the pixel value of the image data is “10”, the number of dots recorded before and after the correction is two. In addition, when the pixel value of the image data is “11”, the number of dots recorded before and after the correction is 3 but actually becomes 2 (the code value “01” of the print mask data). The corresponding nozzle is malfunctioning.

  The line 1607 will be described. A line 1607 is a case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “10” and the code value of the print mask data B of the setting target nozzle is “00”. In this case, from the decoding table of FIG. 6, the printable dot number α of the print mask data A is 2, and the printable dot number β of the print mask data B is 0. Accordingly, the process proceeds to S1206 according to the determination in S1205 of FIG. 12, and the code value of the print mask data B of the setting target nozzle is corrected to “10”. Accordingly, since the code values “00”, “01”, “10”, and “11” of the print mask data A in the first to fourth passes become the code values “10”, “01”, “10”, and “11”, the remaining three The code values of the print mask data for the passes are “01”, “10”, and “11”.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “01”, the pixel value “01” of the image data and the code values “00” “01” “10” of the print mask data before correction. From the combination with “11”, the number of dots to be recorded is one. In addition, after the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “10” “01” “10” “11” of the print mask data.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. It becomes 1. After the correction, the number of dots to be recorded is 3 from the combination of the pixel value “10” of the image data and the code values “10” “01” “10” “11” of the print mask data. Actually, it becomes 2.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Will be 2. Further, after the correction, the number of dots to be recorded is 4 from the combination of the pixel value “11” of the image data and the code values “10” “01” “10” “11” of the print mask data. Actually, it becomes 3.

  The line 1608 will be described. A row 1608 indicates a case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “10” and the code value of the print mask data B of the setting target nozzle is “01”. In this case, from the decoding table of FIG. 6, the printable dot number α of the print mask data A is 2, and the printable dot number β of the print mask data B is 1. Accordingly, the process proceeds to S1206 according to the determination in S1205 of FIG. 12, and the code value of the print mask data B of the setting target nozzle is corrected to “10”. Accordingly, since the code values “00”, “01”, “10”, and “11” of the print mask data A in the first to fourth passes become the code values “00”, “10”, “10”, and “11”, the remaining three The code values of the print mask data for the pass are “00”, “10”, and “11”.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “01”, the pixel value “01” of the image data and the code values “00” “01” “10” of the print mask data before correction. From the combination with “11”, the number of dots to be recorded is one. In addition, after the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “00”, “10”, “10”, and “11” of the print mask data.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. The number of dots to be recorded is 1. Further, after correction, the number of dots to be recorded is 3 from the combination of the pixel value “10” of the image data and the code values “00”, “10”, “10”, and “11” of the print mask data. Actually, the number of dots to be recorded is two.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. The number of dots to be recorded is 2. In addition, after correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “10”, “10”, and “11” of the print mask data. Actually, the number of dots to be recorded is two.

  The line 1609 will be described. A line 1609 is a case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “10” and the code value of the print mask data B of the setting target nozzle is “11”. In this case, from the decoding table of FIG. 6, the printable dot number α of the print mask data A is 2, and the printable dot number β of the print mask data B is 3. Accordingly, the process proceeds to S1207 as a result of the determination in S1205 of FIG. 12, and the code value of the print mask data B of the setting target nozzle is corrected to “11” (although it is a correction, there is no change in this case). Accordingly, the code values “00”, “01”, “10”, and “11” of the print mask data A in the first to fourth passes become code values “00”, “01”, “10”, and “11”. The code values of the print mask data for the pass are “00”, “01”, and “11”.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “01”, the pixel value “01” of the image data and the code values “00” “01” “10” of the print mask data before correction. From the combination with “11”, the number of dots to be recorded is one. In addition, after the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. The number of dots to be recorded is 1. Further, after the correction, the number of dots to be recorded is 2 from the combination of the pixel value “10” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Actually, the number of dots to be recorded is one.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. The number of dots to be recorded is 2. After the correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Actually, the number of dots to be recorded is two.

  The row 1610 will be described. A row 1610 is a case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “11” and the code value of the print mask data B of the setting target nozzle is “00”. In this case, from the decoding table of FIG. 6, the printable dot number α of the print mask data A is 3, and the printable dot number β of the print mask data B is 0. Accordingly, the process proceeds to S1206 according to the determination in S1205 of FIG. 12, and the code value of the print mask data B of the setting target nozzle is corrected to “11”. Accordingly, the code values “00”, “01”, “10”, and “11” of the print mask data A in the first to fourth passes become the code values “11”, “01”, “10”, and “11”, so the remaining 3 The code values of the print mask data for the passes are “01”, “10”, and “11”.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “01” will be described. Before the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. The number of dots to be recorded is zero. Further, after correction, the number of dots to be recorded is 2 from the combination of the pixel value “01” of the image data and the code values “11”, “01”, “10”, and “11” of the print mask data. Actually, it becomes 1.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. The number of dots to be recorded is 1. Further, after correction, the number of dots to be recorded is 3 from the combination of the pixel value “10” of the image data and the code values “11”, “01”, “10”, and “11” of the print mask data. Actually, the number of dots to be recorded is two.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. The number of dots to be recorded is 2. Further, after correction, the number of dots to be recorded is 4 from the combination of the pixel value “11” of the image data and the code values “11”, “01”, “10”, and “11” of the print mask data. Actually, the number of dots to be recorded is three.

  The row 1611 will be described. A row 1611 is a case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “11” and the code value of the print mask data B of the setting target nozzle is “01”. In this case, from the decoding table of FIG. 6, the printable dot number α of the print mask data A is 3, and the printable dot number β of the print mask data B is 1. Accordingly, the process proceeds to S1206 according to the determination in S1205 of FIG. 12, and the code value of the print mask data B of the setting target nozzle is corrected to “11”. Accordingly, the code values “00”, “01”, “10”, and “11” of the print mask data A in the first to fourth passes become the code values “00”, “11”, “10”, and “11”. The code values of the print mask data for the pass are “00”, “10”, and “11”.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “01” will be described. Before the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. The number of dots to be recorded is zero. Further, after correction, the number of dots to be recorded is 2 from the combination of the pixel value “01” of the image data and the code values “00”, “11”, “10”, and “11” of the print mask data. Actually, it becomes 1.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. The number of dots to be recorded is 1. Further, after correction, the number of dots to be recorded is 3 from the combination of the pixel value “10” of the image data and the code values “00”, “11”, “10”, and “11” of the print mask data. Actually, the number of dots to be recorded is two.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. The number of dots to be recorded is 2. After the correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “11”, “10”, and “11” of the print mask data. Actually, the number of dots to be recorded is two.

  The row 1612 will be described. A row 1612 is a case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “11” and the code value of the print mask data B of the setting target nozzle is “10”. In this case, from the decoding table of FIG. 6, the printable dot number α of the print mask data A is 3, and the printable dot number β of the print mask data B is 2. Accordingly, the process proceeds to S1206 according to the determination in S1205 of FIG. 12, and the code value of the print mask data B of the setting target nozzle is corrected to “11”. Accordingly, the code values “00”, “01”, “10”, and “11” of the print mask data A in the first to fourth passes become code values “00”, “01”, “11”, and “11”. The code values of the print mask data for the pass are “00”, “01”, and “11”.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “01” will be described. Before the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. The number of dots to be recorded is zero. In addition, after correction, the number of dots to be recorded is 2 from the combination of the pixel value “01” of the image data and the code values “00”, “01”, “11”, and “11” of the print mask data. Actually, the number of dots to be recorded is one.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. The number of dots to be recorded is 1. Further, after correction, the number of dots to be recorded is 2 from the combination of the pixel value “10” of the image data and the code values “00”, “01”, “11”, and “11” of the print mask data. Actually, the number of dots to be recorded is one.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. The number of dots to be recorded is 2. Further, after correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “01”, “11”, and “11” of the print mask data. Actually, the number of dots to be recorded is two.

  In FIG. 16, a portion not surrounded by a frame is a portion where the number of recording dots is normal before the correction of the print mask data, and there is no change before and after the correction. A portion surrounded by a thick frame is a portion in which the number of recording dots is increased by the correction of the print mask data and becomes a normal number of recording dots. Further, a portion surrounded by a thick dotted line frame is a portion where the number of recording dots does not increase and the number of recording dots is not normal.

  From the above, it can be seen that, regardless of the image data, the portion where the code value of the set print mask data is “00” finally has a normal number of recording dots. On the other hand, the number of dots of at least one dot or more is also present in a portion other than the portion where the code value of the print mask data corresponding to the malfunctioning ejection port is “00” or the code value of the set print mask data is “00” You can see that it is recorded. For example, for the pixel values “01” and “10” of the image data, the number of dots of at least one dot is recorded, and for the pixel value “11” of the image data, the number of dots of at least two dots is recorded.

  Therefore, according to the print mask data correction method of the present embodiment, it is possible to reduce the occurrence of streaks due to malfunctioning discharge ports regardless of the print mask data of the setting destination.

[Second Embodiment]
This embodiment is different from the first embodiment in the flowchart shown in FIG. In the first embodiment, with reference to the decode table shown in FIG. 6 in S1204, the determination is made based on the number of dots α that the print mask data A can be recorded and the number of dots β that the print mask data B can record. It was. In the flowchart of FIG. 17, the determination is made by comparing the code values of the print mask data.

  Referring to the decoding table of FIG. 6, it can be seen that as the code value of the print mask data increases, the types of pixel values of the image data for which the code value of the print mask data is to be recorded increase. For example, when the code value of the print mask data is “00”, the number of pixel values of image data for which “00” is to be recorded is zero. When the code value of the print mask data is “01”, the type of pixel value of the image data for which “01” is to be recorded is 1. When the code value of the print mask data is “10”, the type of pixel value of the image data for which “10” is to be recorded is 2. When the code value of the print mask data is “11”, the type of the pixel value of the image data for which “11” is recorded is 3.

  The flowchart of FIG. 17 will be described by taking the pixel position 705 of FIG. 13 as an example. Each process shown in FIG. 17 is realized, for example, by the CPU 109 reading out a program stored in the ROM 405 to the RAM 406 and executing it.

  In step S <b> 1701, the CPU 109 reads out malfunctioning nozzle data 403 from the memory 110, acquires information about malfunctioning nozzles, and identifies malfunctioning nozzles. The malfunction nozzle data 403 describes information for identifying malfunction nozzles due to non-ejection or the like. For example, the malfunctioning nozzle may be specified based on information detected in a recovery operation or the like of the recording head 111 at the home position h.

  In step S <b> 1702, the CPU 109 acquires print mask data A corresponding to the specified malfunctioning nozzle. Here, the print mask data A is, for example, the code value “11” of the pixel position 705 in the region 1002 of FIG. In step S <b> 1703, the CPU 109 acquires print mask data B corresponding to other nozzles to be set. Here, the print mask data B is, for example, the code value “01” at the pixel position 705 in the region 1002 in FIG.

  In step S <b> 1704, the CPU 109 compares the code value “11” of the print mask data A with the code value “01” of the print mask data B. Here, since the code value “11” of the print mask data A is larger, the process proceeds to S1705, and the code value of the print mask data A is adopted as the code value of the print mask data B corresponding to the pixel to be processed. . If it is determined in step S1704 that the code value of the print mask data B is larger, the CPU 109 keeps the code value of the print mask data B as it is, and the print mask data B corresponding to the pixel to be processed. Is adopted as the code value.

  In step S1707, the CPU 109 determines whether or not the determination processing in step S1704 has been performed for all the pixels of the print mask data A acquired in step S1702. If it is determined that the determination process of S1704 has been performed for all pixels, the process of FIG. On the other hand, if it is determined that the determination process of S1704 has not been performed for all the pixels, another pixel is selected and the process from S1704 is repeated.

[Third Embodiment]
This embodiment is different from the first embodiment in the point of the print mask data conversion table shown in FIG. FIG. 18 is a table for specifying the print mask data used for setting from the print mask data corresponding to the setting destination nozzle and the print mask data corresponding to the malfunctioning nozzle.

  The flowchart of FIG. 19 will be described by taking the pixel position 705 of FIG. 13 as an example. Each process illustrated in FIG. 19 is realized, for example, by the CPU 109 reading out a program stored in the ROM 405 to the RAM 406 and executing the program.

  In step S1901, the CPU 109 reads the malfunctioning nozzle data 403 from the memory 110, acquires information about the malfunctioning nozzle, and identifies the malfunctioning nozzle. The malfunction nozzle data 403 describes information for identifying malfunction nozzles due to non-ejection or the like. For example, the malfunctioning nozzle may be specified based on information detected in a recovery operation or the like of the recording head 111 at the home position h.

  In step S1902, the CPU 109 acquires print mask data A corresponding to the specified malfunctioning nozzle. Here, the print mask data A is, for example, the code value “11” of the pixel position 705 in the region 1002 of FIG. In step S1903, the CPU 109 acquires print mask data B corresponding to another nozzle to be set. Here, the print mask data B is, for example, the code value “01” at the pixel position 705 in the region 1002 in FIG.

  In step S1904, the CPU 109 refers to the table in FIG. Then, from the code value “11” of the print mask data A and the code value “01” of the print mask data B corresponding to the other nozzle to be set, the code value “11” of the print mask data used for setting. (Code value of print mask data C) is specified. In step S1905, the CPU 109 sets the code value of the print mask data B corresponding to the pixel to be processed as the code value of the specified print mask data C.

  In step S1906, the CPU 109 determines whether the processing in step S1904 has been performed for all the pixels of the print mask data A acquired in step S1902. If it is determined that the process of S1904 has been performed for all pixels, the process of FIG. 19 is terminated. On the other hand, if it is determined that the determination process of S1904 has not been performed for all pixels, another pixel is selected, and the process from S1904 is repeated.

[Fourth Embodiment]
As shown in FIG. 16, regardless of the image data, the portion where the code value of the setting destination print mask data is “00” finally becomes the normal number of recording dots. That is, when “00” is present in the code value of the print mask data at the setting destination, the correction is ideal. However, there is a case where “00” does not exist in the code value of the print mask data. Hereinafter, as such an example, there will be described a case where there are two malfunctioning nozzles in four print mask data referred to when recording each pixel in four multi-pass printing, with reference to FIG.

  The first column of FIG. 20 shows code values “00”, “01”, “10”, and “11” of print mask data assigned to a predetermined pixel position for 4-multipass printing. The second column shows the code value of the print mask data corresponding to the malfunctioning nozzle. The third column shows the code value of the print mask data corresponding to the setting target nozzle. The fourth column shows code values of print mask data for the remaining two passes after the print mask correction. The fifth to tenth columns indicate the number of recorded dots before and after the correction of the print mask data for the pixel values “01”, “10”, and “11” of each image data.

  The row 2001 will be described. A row 2001 indicates a case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “00” “01”, and the code value of the print mask data B of the setting target nozzle is “10” “11”. is there. In this case, the code values “00”, “01”, “10”, and “11” of the print mask data in the first to fourth passes become code values “00”, “01”, “10”, and “11”. The code values of the print mask data for the pass are “10” and “11”.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “01”, the pixel value “01” of the image data and the code values “00” “01” “10” of the print mask data before correction. From the combination with “11”, the number of dots to be recorded is one. In addition, after the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “10”, the pixel value “01” of the image data and the code values “00” “01” “10” of the print mask data are before correction. From the combination with “11”, the number of dots to be recorded is two. In addition, after the correction, the number of dots to be recorded is 2 from the combination of the pixel value “10” of the image data and the code values “00” “01” “10” “11” of the print mask data.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Is 2 due to a malfunctioning nozzle. Further, after the correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00” “01” “10” “11” of the print mask data. Actually, it becomes 2 because of a malfunctioning nozzle.

  The rows 2002 and 2003 will be described. That line is when the code value of the print mask data A corresponding to the malfunctioning nozzle is “00” “10”, and the code value of the print mask data B of the setting target nozzle is “01” “11”. is there. In this case, a case where the setting target of the code value “00” of the print mask data A is set to the code value “01” of the print mask data B (hereinafter referred to as the first setting) can be considered. A case where the setting target of the code value “00” of the print mask data A is the code value “11” of the print mask data B (hereinafter referred to as the second setting) is also conceivable. In the case of the first setting, the code value “10” of the print mask data A is set to the code value “11” of the print mask data B. In the case of the second setting, the setting target of the code value “10” of the print mask data A is set to the code value “01” of the print mask data B.

  In the case of the first setting, the code values “00” “01” “10” “11” of the print mask data in the first to fourth passes should be the code values “00” “01” “10” “11”. Therefore, the code values of the print mask data for the remaining two passes are “01” and “11”.

  When the code value of the image data corresponding to the malfunctioning nozzle is “01”, the pixel value “01” of the image data and the code values “00” “01” “10” of the print mask data before the correction. From the combination with “11”, the number of dots to be recorded is one. In addition, after the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. It is actually 1 because of a defective nozzle. In addition, after correction, the number of dots to be recorded is 1 from the combination of the pixel value “10” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Actually, it is 1 because of a malfunctioning nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Actually, it is 2 because of a defective nozzle. Further, after the correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00” “01” “10” “11” of the print mask data. Actually, it is 2 because of a malfunctioning nozzle.

  In the case of the second setting, the code values “00”, “01”, “10”, and “11” of the print mask data in the first to fourth passes become the code values “00”, “10”, “10”, and “11”. Therefore, the code values of the print mask data for the remaining two passes are “10” and “11”.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “01”, the pixel value “01” of the image data and the code values “00”, “10”, “10” of the print mask data before correction. From the combination with “11”, the number of dots to be recorded is one. In addition, after the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “00”, “10”, “10”, and “11” of the print mask data.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. It is actually 1 because of a defective nozzle. In addition, after correction, the number of dots to be recorded is 3 from the combination of the pixel value “10” of the image data and the code values “00”, “10”, “10”, and “11” of the print mask data. Actually, it is 2 because of a malfunctioning nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Actually, it is 2 because of a defective nozzle. Further, after the correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00” “10” “10” “11” of the print mask data. Actually, it is 2 because of a malfunctioning nozzle.

  The rows 2004 and 2005 will be described. That line is when the code value of the print mask data A corresponding to the malfunctioning nozzle is “00” “11”, and the code value of the print mask data B of the setting target nozzle is “01” “10”. is there. Setting the code mask “00” of the print mask data A to be the code value “01” of the print mask data B is referred to as a first setting. Also, setting the code mask “00” of the print mask data A to be the code value “10” of the print mask data B is referred to as a second setting. In the case of the first setting, the setting target of the code value “11” of the print mask data A is the code value “10” of the print mask data B. In the case of the second setting, the code value “11” of the print mask data A is set to the code value “01” of the print mask data B.

  In the case of the first setting, the code values “00”, “01”, “10”, “11” of the print mask data in the first to fourth passes become the code values “00”, “01”, “11”, “11”. Therefore, the code values of the print mask data for the remaining two passes are “01” and “11”.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “01” will be described. Before correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Actually, it is 0 because of a defective nozzle. In addition, after correction, the number of dots to be recorded is 2 from the combination of the pixel value “01” of the image data and the code values “00”, “01”, “11”, and “11” of the print mask data. Actually, it is 1 because of a malfunctioning nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. It is actually 1 because of a defective nozzle. In addition, after correction, the number of dots to be recorded is 2 from the combination of the pixel value “10” of the image data and the code values “00”, “01”, “11”, and “11” of the print mask data. Actually, it is 1 because of a malfunctioning nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Actually, it is 2 because of a defective nozzle. Further, after correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00” “01” “11” “11” of the print mask data. Actually, it is 2 because of a malfunctioning nozzle.

  In the case of the second setting, the code values “00”, “01”, “10”, and “11” of the print mask data in the first to fourth passes become the code values “00”, “11”, “10”, and “11”. Therefore, the code values of the print mask data for the remaining two passes are “10” and “11”.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “01” will be described. Before correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Actually, it is 0 because of a defective nozzle. After the correction, the number of dots to be recorded is 2 from the combination of the pixel value “01” of the image data and the code values “00”, “11”, “10”, and “11” of the print mask data. Actually, it is 1 because of a malfunctioning nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. It is actually 1 because of a defective nozzle. Further, after correction, the number of dots to be recorded is 3 from the combination of the pixel value “10” of the image data and the code values “00”, “11”, “10”, and “11” of the print mask data. Actually, it is 2 because of a malfunctioning nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Actually, it is 2 because of a defective nozzle. Further, after correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “11”, “10”, and “11” of the print mask data. Actually, it is 2 because of a malfunctioning nozzle.

  The rows 2006 and 2007 will be described. That line is when the code value of the print mask data A corresponding to the malfunctioning nozzle is “01” “10”, and the code value of the print mask data B of the setting target nozzle is “00” “11”. is there. A case where the setting target of the code value “01” of the print mask data A is the code value “00” of the print mask data B is the first setting. The second setting is a case where the code value “01” of the print mask data A is set to the code value “11” of the print mask data B. In the case of the first setting, the setting target of the code value “10” of the print mask data A is the code value “11” of the print mask data B. In the second setting, the code value “10” of the print mask data A is set to the code value “00” of the print mask data B.

  In the case of the first setting, the code values “00” “01” “10” “11” of the print mask data in the first to fourth passes become the code values “01” “01” “11” “11”. Therefore, the code values of the print mask data for the remaining two passes are “01” and “11”.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “01”, the pixel value “01” of the image data and the code values “00” “01” “10” of the print mask data before correction. From the combination with “11”, the number of dots to be recorded is one. Further, after correction, the number of dots to be recorded is 2 from the combination of the pixel value “01” of the image data and the code values “01”, “01”, “11”, and “11” of the print mask data. Actually, it is 1 because of a malfunctioning nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 from the combination of the pixel value “10” of the image data and the code values “01”, “01”, “10”, and “11” of the print mask data. It is actually 1 because of a defective nozzle. In addition, after the correction, the number of dots to be recorded is 2 from the combination of the pixel value “10” of the image data and the code values “01” “01” “11” “11” of the print mask data. Actually, it is 1 because of a malfunctioning nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. It is actually 1 because of a defective nozzle. Further, after the correction, the number of dots to be recorded is 4 from the combination of the pixel value “11” of the image data and the code values “01”, “01”, “11”, and “11” of the print mask data. Actually, it is 2 because of a malfunctioning nozzle.

  In the case of the second setting, the code values “00”, “01”, “10”, and “11” of the print mask data in the first to fourth passes become the code values “10”, “01”, “10”, and “11”. Therefore, the code values of the print mask data for the remaining two passes are “10” and “11”.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “01”, the pixel value “01” of the image data and the code values “00” “01” “10” of the print mask data before correction. From the combination with “11”, the number of dots to be recorded is one. After the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “10” “01” “10” “11” of the print mask data.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. It is actually 1 because of a defective nozzle. Further, after correction, the number of dots to be recorded is 3 from the combination of the pixel value “10” of the image data and the code values “10”, “01”, “10”, and “11” of the print mask data. Actually, it is 2 because of a malfunctioning nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. It is actually 1 because of a defective nozzle. Further, after correction, the number of dots to be recorded is 4 from the combination of the pixel value “11” of the image data and the code values “10” “01” “10” “11” of the print mask data. Actually, it is 2 because of a malfunctioning nozzle.

  The lines 2008 and 2009 will be described. That line is when the code value of the print mask data A corresponding to the malfunctioning nozzle is “01” “11”, and the code value of the print mask data B of the setting target nozzle is “00” “10”. is there. The case where the setting target of the code value “01” of the print mask data A is the code value “00” of the print mask data B is the first setting. In addition, the case where the setting target of the code value “01” of the print mask data A is the code value “10” of the print mask data B is set as the second setting. In the case of the first setting, the setting target of the code value “11” of the print mask data A is the code value “10” of the print mask data B. In the case of the second setting, the code value “11” of the print mask data A is set to the code value “00” of the print mask data B.

  In the case of the first setting, the code values “00” “01” “10” “11” of the print mask data in the first to fourth passes become the code values “01” “01” “11” “11”. Therefore, the code values of the print mask data for the remaining two passes are “01” and “11”.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “01” will be described. Before correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Actually, it is 0 because of a defective nozzle. Further, after correction, the number of dots to be recorded is 2 from the combination of the pixel value “01” of the image data and the code values “01”, “01”, “11”, and “11” of the print mask data. Actually, it is 1 because of a malfunctioning nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 from the combination of the pixel value “10” of the image data and the code values “01”, “01”, “10”, and “11” of the print mask data. It is actually 1 because of a defective nozzle. In addition, after the correction, the number of dots to be recorded is 2 from the combination of the pixel value “10” of the image data and the code values “01” “01” “11” “11” of the print mask data. Actually, it is 1 because of a malfunctioning nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. It is actually 1 because of a defective nozzle. Further, after the correction, the number of dots to be recorded is 4 from the combination of the pixel value “11” of the image data and the code values “01”, “01”, “11”, and “11” of the print mask data. Actually, it is 2 because of a malfunctioning nozzle.

  In the case of the second setting, the code values “00”, “01”, “10”, and “11” of the print mask data in the first to fourth passes become the code values “11”, “01”, “10”, and “11”. Therefore, the code values of the print mask data for the remaining two passes are “10” and “11”.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “01” will be described. Before correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Actually, it is 0 because of a defective nozzle. In addition, after correction, the number of dots to be recorded is 2 from the combination of the pixel value “01” of the image data and the code values “11”, “01”, “10”, and “11” of the print mask data. Actually, it is 1 because of a malfunctioning nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. It is actually 1 because of a defective nozzle. Further, after correction, the number of dots to be recorded is 3 from the combination of the pixel value “10” of the image data and the code values “11”, “01”, “10”, and “11” of the print mask data. Actually, it is 2 because of a malfunctioning nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. It is actually 1 because of a defective nozzle. Further, after correction, the number of dots to be recorded is 4 from the combination of the pixel value “11” of the image data and the code values “11” “01” “10” “11” of the print mask data. Actually, it is 2 because of a malfunctioning nozzle.

  The row 2010 will be described. That line is when the code value of the print mask data A corresponding to the malfunctioning nozzle is “10” “11”, and the code value of the print mask data B of the setting target nozzle is “00” “01”. is there.

  Since the code values “00”, “01”, “10”, and “11” of the print mask data in the first to fourth passes become the code values “10”, “11”, “10”, and “11”, the remaining two passes The code values of the print mask data are “10” and “11”.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “01” will be described. Before correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. Actually, it is 0 because of a defective nozzle. In addition, after the correction, the number of dots to be recorded is 2 from the combination of the pixel value “01” of the image data and the code values “10”, “11”, “10”, and “11” of the print mask data. Actually, it is 1 because of a malfunctioning nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 from the combination of the pixel value “10” of the image data and the code values “01”, “01”, “10”, and “11” of the print mask data. Actually, it is 0 because of a defective nozzle. In addition, after the correction, the number of dots to be recorded is 4 from the combination of the pixel value “10” of the image data and the code values “10”, “11”, “10”, and “11” of the print mask data. Actually, it is 2 because of a malfunctioning nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before correction, the number of dots to be recorded is 3 from the combination of the pixel value “11” of the image data and the code values “00”, “01”, “10”, and “11” of the print mask data. It is actually 1 because of a defective nozzle. In addition, after correction, the number of dots to be recorded is 4 from the combination of the pixel value “11” of the image data and the code values “10”, “11”, “10”, and “11” of the print mask data. Actually, it is 2 because of a malfunctioning nozzle.

  In FIG. 20, the number of recorded dots that is normal before the correction of the print mask data and the portion that does not change before and after the correction are indicated by a portion that is not surrounded by a frame. In addition, the number of recording dots is increased by the print mask data correction, a portion where the number of normal recording dots is normal is indicated by a thick frame, and a portion which is less than normal recording dots is indicated by a double frame. Further, a portion where the number of recording dots does not increase and the number of recording dots is not normal is indicated by a thick dotted frame.

  As shown in FIG. 20, the number of dots of at least one dot is recorded regardless of the image data. For example, the number of dots of at least one dot is recorded in the image data “01” and “10”, and the number of dots of at least two dots is recorded in the image data “11”. Therefore, according to the print mask data correction method of this embodiment, it is possible to reduce the occurrence of streaks due to malfunctioning nozzles regardless of the print mask data of the setting destination.

[Fifth Embodiment]
As shown in FIG. 16, regardless of the image data, the portion where the code value of the setting destination print mask data is “00” finally becomes the normal number of recording dots. That is, when “00” is present in the code value of the print mask data at the setting destination, the correction is ideal. However, there is a case where “00” does not exist in the code value of the print mask data. Hereinafter, as such an example, a case where there is one malfunctioning nozzle in three print mask data referred to when recording each pixel in three multi-pass printing will be described with reference to FIG.

  The first column of FIG. 21 shows code values “01”, “10”, and “11” of print mask data assigned to predetermined pixel positions for three-pass printing. The second column shows the code value of the print mask data corresponding to the malfunctioning nozzle. The third column shows the code value of the print mask data corresponding to the setting target nozzle. The fourth column shows code values of print mask data for the remaining two passes after the print mask correction. The fifth to tenth columns indicate the number of recorded dots before and after the correction of the print mask data for the pixel values “01”, “10”, and “11” of each image data.

  The row 2101 will be described. The row corresponds to the case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “01” and the code value of the print mask data B of the setting target nozzle is “10”.

  Since the code values “01”, “10”, and “11” of the print mask data for the first to fourth passes become the code values “01”, “10”, and “11”, the code values of the print mask data for the remaining two passes Becomes “10” and “11”.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “01”, the pixel value “01” of the image data and the code values “01”, “10”, and “11” of the print mask data before correction. The number of dots to be recorded is 1 from the combination. After the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “01”, “10”, and “11” of the print mask data.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “10”, the pixel value “10” of the image data and the code values “01”, “10”, and “11” of the print mask data are before the correction. The number of dots to be recorded is 2 based on the combination. After the correction, the number of dots to be recorded is 2 from the combination of the pixel value “10” of the image data and the code values “01”, “10”, and “11” of the print mask data.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “01”, “10”, and “11” of the print mask data. Therefore, it is actually 2. In addition, after the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “01”, “10”, and “11” of the print mask data. Actually, it is 2 because of the nozzle.

  The row 2102 will be described. The row corresponds to the case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “01” and the code value of the print mask data B of the setting target nozzle is “11”.

  Since the code values “01”, “10”, and “11” of the print mask data for the first to fourth passes become the code values “01”, “10”, and “11”, the code values of the print mask data for the remaining two passes Becomes “10” and “11”.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “01”, the pixel value “01” of the image data and the code values “01”, “10”, and “11” of the print mask data before correction. The number of dots to be recorded is 1 from the combination. After the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “01”, “10”, and “11” of the print mask data.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “10”, the pixel value “10” of the image data and the code values “01”, “10”, and “11” of the print mask data are before the correction. The number of dots to be recorded is 2 based on the combination. After the correction, the number of dots to be recorded is 2 from the combination of the pixel value “10” of the image data and the code values “01”, “10”, and “11” of the print mask data.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “01”, “10”, and “11” of the print mask data. Therefore, it is actually 2. In addition, after the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “01”, “10”, and “11” of the print mask data. Actually, it is 2 because of the nozzle.

  The row 2103 will be described. The row corresponds to the case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “10” and the code value of the print mask data B of the setting target nozzle is “01”.

  The code values “01”, “10”, and “11” of the print mask data for the first to fourth passes become the code values “10”, “10”, and “11”. Therefore, the code values of the print mask data for the remaining two passes Becomes “10” and “11”.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “01”, the pixel value “01” of the image data and the code values “01”, “10”, and “11” of the print mask data before correction. The number of dots to be recorded is 1 from the combination. After the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “10”, “10”, and “11” of the print mask data.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “01”, “10”, and “11” of the print mask data. Therefore, it is actually 1. In addition, after the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “10” of the image data and the code values “10”, “10”, and “11” of the print mask data. Actually, it is 2 because of the nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “01”, “10”, and “11” of the print mask data. Therefore, it is actually 2. Further, after the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “10”, “10”, and “11” of the print mask data. Actually, it is 2 because of the nozzle.

  The row 2104 will be described. The row corresponds to the case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “10” and the code value of the print mask data B of the setting target nozzle is “11”.

  Since the code values “01”, “10”, and “11” of the print mask data for the first to fourth passes become the code values “01”, “10”, and “11”, the code values of the print mask data for the remaining two passes Becomes “01” and “11”.

  When the pixel value of the image data corresponding to the malfunctioning nozzle is “01”, the pixel value “01” of the image data and the code values “01”, “10”, and “11” of the print mask data before correction. The number of dots to be recorded is 1 from the combination. After the correction, the number of dots to be recorded is 1 from the combination of the pixel value “01” of the image data and the code values “01”, “10”, and “11” of the print mask data.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “01”, “10”, and “11” of the print mask data. Therefore, it is actually 1. In addition, after the correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “01”, “10”, and “11” of the print mask data. It is actually 1 because of the nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “01”, “10”, and “11” of the print mask data. Therefore, it is actually 2. In addition, after the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “01”, “10”, and “11” of the print mask data. Actually, it is 2 because of the nozzle.

  The row 2105 will be described. The row corresponds to the case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “11” and the code value of the print mask data B of the setting target nozzle is “01”.

  Since the code values “01”, “10”, and “11” of the print mask data for the first to fourth passes become the code values “11”, “10”, and “11”, the code values of the print mask data for the remaining two passes Becomes “10” and “11”.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “01” will be described. Before correction, the number of dots to be recorded is 1 based on the combination of the pixel value “01” of the image data and the code values “01”, “10”, and “11” of the print mask data. Therefore, it is actually 0. Further, after the correction, the number of dots to be recorded is 2 based on the combination of the pixel value “01” of the image data and the code values “11”, “10”, and “11” of the print mask data. It is actually 1 because of the nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “01”, “10”, and “11” of the print mask data. Therefore, it is actually 1. In addition, after the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “10” of the image data and the code values “11”, “10”, and “11” of the print mask data. Actually, it is 2 because of the nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “01”, “10”, and “11” of the print mask data. Therefore, it is actually 2. In addition, after the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “11”, “10”, and “11” of the print mask data. Actually, it is 2 because of the nozzle.

  The row 2106 will be described. The row corresponds to a case where the code value of the print mask data A corresponding to the malfunctioning nozzle is “11” and the code value of the print mask data B of the setting target nozzle is “10”.

  Since the code values “01”, “10”, and “11” of the print mask data for the first to fourth passes become the code values “01”, “11”, and “11”, the code values of the print mask data for the remaining two passes Becomes “01” and “11”.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “01” will be described. Before correction, the number of dots to be recorded is 1 based on the combination of the pixel value “01” of the image data and the code values “01”, “10”, and “11” of the print mask data. Therefore, it is actually 0. Further, after the correction, the number of dots to be recorded is 2 based on the combination of the pixel value “01” of the image data and the code values “01”, “11”, and “11” of the print mask data. It is actually 1 because of the nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “10” will be described. Before correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “01”, “10”, and “11” of the print mask data. Therefore, it is actually 1. Further, after the correction, the number of dots to be recorded is 2 based on the combination of the pixel value “10” of the image data and the code values “01”, “11”, and “11” of the print mask data. It is actually 1 because of the nozzle.

  A case where the pixel value of the image data corresponding to the malfunctioning nozzle is “11” will be described. Before the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “01”, “10”, and “11” of the print mask data. Therefore, it is actually 2. Further, after the correction, the number of dots to be recorded is 3 based on the combination of the pixel value “11” of the image data and the code values “01”, “11”, and “11” of the print mask data. Actually, it is 2 because of the nozzle.

  In FIG. 21, the number of recorded dots is a normal number before the print mask data correction, and a portion that does not change before and after the correction is indicated by a portion not surrounded by a frame. Further, the number of recording dots is increased by the print mask data correction, and the portion where the number of recording dots is normal is indicated by a thick frame. Further, a portion where the number of recording dots does not increase and the number of recording dots is not normal is indicated by a thick dotted frame. As shown in FIG. 21, the number of dots of at least one dot or more is recorded regardless of the image data. For example, the number of dots of at least one dot is recorded in the image data “01” and “10”, and the number of dots of at least two dots is recorded in the image data “11”. Therefore, according to the print mask data correction method of the present embodiment, it is possible to reduce the occurrence of streaks due to malfunctioning discharge ports regardless of the print mask data of the setting destination.

[Other examples of decode table]
FIG. 22 is a diagram showing a decoding table different from the decoding table shown in FIG. Compared with the decoding table of FIG. 6 used in the first to fifth embodiments, the difference is that the number of image data to be recorded does not increase as the code value of the print mask data increases. When the decoding table as shown in FIG. 6 is set, the print mask data correction method as in the second embodiment cannot cope. However, if the print mask data correction method as in the first embodiment or the third embodiment is used, the same effects as those in the first to fifth embodiments can be obtained. That is, in the print mask data correction process of FIG. 12 in the first embodiment and the print mask data correction process of FIG. 19 in the third embodiment, a decode table as shown in FIG. 22 can be used. The degree of freedom in designing the decoding table can be increased.

  The present invention is also realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

  100 inkjet recording apparatus, 101 recording control unit, 109 CPU, 110 memory, 405 ROM, 406 RAM

Claims (7)

An inkjet recording apparatus that scans a recording head having a plurality of nozzles a plurality of times with respect to a region corresponding to one pixel and records one pixel with a plurality of recording dots,
Based on image data in which one pixel is represented by a pixel value of n bits (n ≧ 2), a plurality of dots corresponding to the pixel value are recorded with respect to the area corresponding to the pixel. Recording control means for performing recording by scanning twice, and
M bits (integer of m ≧ 2) for determining ejection / non-ejection of each ink droplet of each of the plurality of nozzles in each of the plurality of scans according to the correspondence between the pixel value that can be taken by the one pixel and the pixel value Storage means for storing the code value represented by
When a discharge failure occurs in any of the plurality of nozzles, a determining unit that determines an alternative nozzle of the nozzle in which the discharge failure has occurred among the plurality of nozzles;
Setting means for setting the code value corresponding to the alternative nozzle determined by the determining means based on the code value corresponding to the nozzle in which the ejection failure has occurred,
The setting means is configured such that the number of pixel values determined to eject ink droplets by the code value corresponding to the alternative nozzle in the correspondence relationship is an ink according to the code value corresponding to the nozzle in which the ejection failure has occurred in the correspondence relationship. If there are more pixel values than the number of pixel values determined to eject drops, the code value corresponding to the alternative nozzle is not changed,
The number of pixel values determined to eject ink droplets by the code value corresponding to the alternative nozzle in the correspondence relationship is determined to eject ink droplets by the code value corresponding to the nozzle in which the ejection failure has occurred in the correspondence relationship. If not more than the number of pixel values to be set, the code value corresponding to the nozzle in which the ejection failure has occurred is set as the code value corresponding to the alternative nozzle ,
An ink jet recording apparatus.   When the determination unit includes a nozzle other than the nozzle in which the ejection failure has occurred and ejects the ink droplet less frequently than the nozzle in which the ejection failure has occurred, the number of ejections of the ink droplet is small. The inkjet recording apparatus according to claim 1, wherein a nozzle is determined as the alternative nozzle.   3. The ink jet recording apparatus according to claim 1, wherein each of the plurality of nozzles is used for discharging at least once with respect to any of pixel values that the one pixel can take. Wherein the storage unit, you memorize the pixel value 1 pixel can take and the combination of the code value can take a value, the discharge / non-discharge of ink droplets, a table is associated as the relationship The ink jet recording apparatus according to claim 1 , wherein the ink jet recording apparatus is an ink jet recording apparatus. When the code value is larger, the number of times ink droplets are ejected with respect to the pixel value is increased.
The setting means compares the code value corresponding to the alternative nozzle with the code value corresponding to the nozzle in which the ejection failure has occurred, and sets the larger one as the code value corresponding to the alternative nozzle. The ink jet recording apparatus according to claim 1, wherein: If the number of scans performed on a region corresponding to the pixel is 4, the pixel value and the code value, one of the claims 1 to 5, characterized in that a value expressed by 2 bits 2. An ink jet recording apparatus according to item 1. An inkjet recording apparatus that scans a recording head having a plurality of nozzles a plurality of times with respect to an area corresponding to one pixel and records one pixel with a plurality of recording dots, and each pixel has n bits (n ≧ 2) based on the image data representing the pixel value, a dot of a recording dot number corresponding to the pixel value, a recording control means for the recording head performs recording by scanning a plurality of times for the region corresponding to the pixel a recording control method that will be executed in the inkjet recording apparatus,
When a discharge failure occurs in any of the plurality of nozzles, a determination step of determining an alternative nozzle of the nozzle in which the discharge failure has occurred among the plurality of nozzles;
M for determining ejection / non-ejection of each ink droplet of each of the plurality of nozzles in each of the plurality of scans according to the correspondence between the pixel value that can be taken by the one pixel and the pixel value stored in the storage unit. based on the code value represented by bits (m ≧ 2 integer), the code value corresponding to the alternate nozzles determined in said determining step, wherein the code value corresponding to a nozzle the discharge failure has occurred A setting step for setting based on
Wherein in the setting step, the ink by the code value number of the code values pixel value determined to eject ink droplets by corresponding to the alternative nozzle in the correspondence relationship corresponding to the nozzle of the ejection failure occurs in the correspondence relation If there are more pixel values than the number of pixel values determined to eject drops, the code value corresponding to the alternative nozzle is not changed,
The number of pixel values determined to eject ink droplets by the code value corresponding to the alternative nozzle in the correspondence relationship is determined to eject ink droplets by the code value corresponding to the nozzle in which the ejection failure has occurred in the correspondence relationship. If not more than the number of pixel values to be set, the code value corresponding to the nozzle in which the ejection failure has occurred is set as the code value corresponding to the alternative nozzle ,
And a recording control method.

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