JP2008093982A - Inkjet recording device and recording control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the reduction of a throughput while keeping the deterioration of a recording quality to the minimum even if all the nozzles for recording one line in a multi-pass recording are in the state of non-delivery. <P>SOLUTION: In the multi-pass recording, if all the nozzles for forming the dot of a same line are in the state of non-delivery and the portion corresponding to those nozzles is "0" (S104), the line number S is measured and compared with a threshold value N (S105). If the line number S is larger than the threshold value N, the change propriety of the number of recording passes is judged (S106). If it is judged that the changing is possible, a mask table corresponding to the number of recording passes after changing is made out while changing the number of recording passes. Thereby, the dot to be recorded by the non-deliver nozzle is complementarily formed with other nozzle according to a changed another scan. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus and a recording control method, and more particularly to recording control for performing recording by complementing ejection failure nozzles such as non-ejection of a recording head.

  The recording apparatus is known as a printer, a copier, a facsimile, or the like, and is also used as an output device such as a computer, a word processor, or a workstation. Such a recording apparatus is configured to record an image (including characters and symbols) on a recording medium such as paper or a plastic thin plate (OHP paper or the like) based on image information. As a recording mechanism, an ink jet method, a wire dot method, a thermal method, a thermal transfer method, a laser beam method, and the like are known. Further, there are a full line method and a serial method as a method of moving the recording head and the recording medium relative to each other during recording. In a serial type recording apparatus, an image (including characters and symbols) is recorded by ejecting ink from a recording head mounted on a carriage that moves (main scans) along the surface of the recording medium. After the main scanning for one row is completed, a predetermined amount of paper feed (sub scanning) is performed in a direction crossing the main scanning direction, and the main scanning for the next row is performed. By repeating these main scanning and sub scanning, an image is recorded in a desired range of the recording medium.

  Among the above-described recording mechanism methods, the ink jet method is one of non-impact recording methods in which ink is ejected and ink is directly adhered to a recording medium. Piezo methods and bubble jets (registered trademarks) are further added depending on the ink droplet formation method. ) System is broadly classified. The ink jet method has an advantage that the running cost is low and it is possible to cope with color recording relatively easily by providing a recording head or nozzle row for a plurality of ink colors.

  In such ink jet recording heads, in recent years, higher image quality and improved throughput are achieved by increasing the nozzle density and increasing the number of nozzles. However, when a large number of nozzles are formed with high density, there may be nozzles with poor discharge such as dust and bubbles mixed in, or deterioration of actuators for applying pressure to ink and discharging it, or non-ejection due to service life. Increases the nature. As a result, the frequency at which the recording quality is lowered also increases.

  A so-called multi-pass printing method solves this problem of ejection failure. In this recording method, dots forming a line in the main scanning direction are formed by being shared by different nozzles corresponding to the number of passes. As a result, even if an ejection failure occurs in a certain nozzle, the resulting dot failure such as a dot not being formed can be distributed according to the number of passes and made inconspicuous in the entire recorded image. However, for example, when non-ejection occurs in a plurality of nozzles among the nozzles forming one line, the ratio of blank dots (no dots are formed) in one line increases. As a result, the entire recorded image is recognized as a white thin line (whitening). In addition, when the lines including the non-ejection nozzles are adjacent to each other, the area where the density decreases is widened even if the ratio of blank dots in one line does not increase, so the line is recognized as a thick line with a light color, Similarly, the recording quality is lowered.

  On the other hand, in Patent Document 1, in multi-pass printing, if there are non-ejection nozzles in a nozzle group that forms dots on the same line or adjacent lines, the number of printing passes is changed, or the printing pass It is described to prompt the user to change the number. According to this, by changing the number of recording passes, the combination of nozzles in the nozzle group that forms one line or adjacent lines can be changed, and as a result, the ratio of blank dots in one line and adjacent lines can be reduced. As a result, the positions of the blank dots due to the non-ejection nozzles can be dispersed on the recorded image so that the blank dots are not conspicuous, and the degradation of the recording quality can be minimized.

  On the other hand, Patent Document 2 describes that when a non-ejection nozzle is present in a nozzle group that forms dots of the same line, the dots are complemented by other nozzles in that nozzle group. According to this, the proportion of blank dots in the same line can be reduced without changing the number of recording passes. As a result, it is possible to minimize a decrease in recording quality and throughput.

JP 2004-042432 A JP 2000-094662 A

  However, the above prior art has the following problems.

  That is, in recent years, awareness of running costs has increased, so even if there are non-ejection nozzles, there are many users who continue to use the recording head without replacing it. In such a usage, all of the plurality of nozzles forming the same line may not discharge in multi-pass printing. In this case, the complementing method described in Patent Document 2 is not effective. That is, there are no normal nozzles that should complement the non-ejection nozzles, and as a result, all the lines become blank dots, and white spots may be conspicuous in the recorded image.

  On the other hand, the method of changing the number of passes described in Patent Document 1 has a certain effect when all the nozzles that form dots of the same line do not discharge. However, depending on the type of recording medium used for recording, even if recording is performed in a state where all the dots to be recorded on a certain line are not formed without changing the number of passes, there are cases where it is not so noticeable in the recorded image. This is not limited to the case where the non-ejection nozzle corresponds to one line. That is, even when all nozzles forming dots for a plurality of lines have non-ejection, depending on the number of lines and the type of recording medium, even if not all dots to be recorded on those lines are formed, There may be no significant impact on recording quality. In such a case, changing the number of recording passes uniformly does not substantially suppress the deterioration of recording quality, but also causes a decrease in throughput.

  In addition, with the increasing desire for high-definition and high-resolution images for recorded matter, the size of dots formed on a recording medium tends to be further miniaturized. In such a case, even if all of one line is a blank dot, a person who observes the recorded matter cannot visually recognize it, and the image quality may not deteriorate. Even in such a case, changing the number of recording passes uniformly has a problem that the throughput is lowered as described above.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording apparatus capable of minimizing a decrease in recording quality and suppressing a decrease in throughput even when all the nozzles for recording one line in multi-pass recording are non-ejection. And a control method thereof.

  To this end, the present invention is an ink jet recording apparatus that performs recording by scanning a recording medium in which a plurality of nozzles for ejecting ink are arranged, and performs recording. In an ink jet recording apparatus capable of performing multi-pass recording in which dots constituting one line in the scanning direction are formed by a plurality of different nozzles by relative conveyance with respect to the non-ejection nozzle information in the recording head. According to the non-ejection nozzle detection means to be acquired and the information acquired by the non-ejection nozzle detection means, all of the plurality of different nozzles used for forming dots constituting the one line are non-ejection. A non-ejection line number detection means for detecting and detecting the number of lines in which all of the plurality of different nozzles are non-ejection; According to the number of lines detected by the number-of-lines detection means, the number-of-passes changing means for changing the number of scans for forming dots constituting one line, and the number of scans changed by the number-of-passes changing means. And a first nozzle setting means for determining different nozzles used for forming dots constituting the one line so that dots to be formed by the non-ejection nozzles are formed by other nozzles. Features.

  In addition, an inkjet recording apparatus that performs recording by scanning a recording head in which a plurality of nozzles that eject ink are arrayed and performs recording, and the recording head is configured to perform a plurality of scans of the recording head relative to the recording head. Information on non-ejection nozzles in the recording head is acquired in a recording control method of an inkjet recording apparatus capable of performing multi-pass recording in which dots constituting one line in the scanning direction are formed by different nozzles by conveyance. According to the non-ejection nozzle detection step and the information acquired in the non-ejection nozzle detection step, it is detected that all of the different nozzles forming the dots constituting the one line are non-ejection, and the different Non-ejection line number detection process for detecting the number of lines where all nozzles are non-ejection, and the non-ejection line number detection process The pass number changing step of changing the number of scans for forming dots constituting one line in accordance with the number of lines, and the non-ejection nozzle according to the number of scans changed by the pass number changing means And a first nozzle setting step for determining different nozzles used for forming the dots constituting the one line so that the dots to be formed by other nozzles are formed.

  According to the above configuration, in multi-pass printing, when it is detected that all of the different nozzles forming one line constitute a non-ejection, each of the number of such lines corresponds to one line. The number of scans for forming the dots constituting the line is greatly changed. Thereby, the dots to be recorded by the non-ejection nozzles are complementarily formed by the other nozzles in another changed scan.

  As a result, even when all of the nozzles that record one line in multi-pass printing are non-ejection, it is possible to minimize the degradation of the recording quality and suppress the degradation of the throughput.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram schematically showing a schematic configuration of a recording unit of the ink jet recording apparatus according to the first embodiment of the present invention. In FIG. 1, reference numeral 301 denotes a print head unit, and ink tanks each containing ink of four colors (black: Bk, cyan: Cy, magenta: Mg, yellow: Ye), and four print heads corresponding to each. Is composed of an integrated multi-recording head. Reference numeral 302 denotes a carriage on which the recording head unit 301 is mounted and moved. The carriage 302 moves to the home position 310 during standby such as a non-recording state. Reference numeral 303 denotes a paper feed roller, which rotates together with the auxiliary roller 304 in the direction of the arrow while holding down the recording paper 306, and conveys the recording paper 306 in the direction of arrow Y as needed. Reference numeral 305 denotes a paper feed roller that feeds the recording paper 306 and plays a role of keeping the recording paper 306 flat with the paper feed roller 303 and the auxiliary roller 304. Here, the recording head 301 has 64 nozzles arranged in the paper feed direction for the four ink colors Bk, Cy, Mg, and Ye. Each nozzle can be referred to by assigning nozzle numbers # 0 to # 63 as will be described later.

  The basic recording operation in the above configuration is as follows. During standby, the carriage 302 at the home position 310 performs recording by ejecting ink onto the recording paper 306 from a plurality of nozzles of the recording head 301 according to the recording data while scanning in the X direction according to a recording start command. When the scanning up to the end of the recording paper 306 is completed, the carriage 302 returns to the home position 310. At the same time, the paper feed roller 303 rotates in the direction of the arrow, thereby feeding the paper by a predetermined width in the Y direction and starting scanning in the X direction again. By repeating such scanning and paper feeding operation, recording is performed on a predetermined area of the recording medium 306. Multi-pass recording, which will be described later with reference to FIG.

  Note that the ink jet recording apparatus of the present embodiment includes a control unit including a CPU, a ROM, a RAM, a dedicated circuit, and the like for executing recording control such as processing described later in FIG. 7 and image processing. (Not shown). Also provided is an interface unit (not shown) for transferring image information and various control information (number of recording passes) with an external host computer. Furthermore, a carriage motor for driving the carriage, a paper feed motor for driving the paper feed roller, a transport motor for driving the paper transport, and a motor driver for driving them are provided. In addition, a recording head driving driver for driving the recording head 301, an operation panel for inputting control information by the user, and the like are provided.

  The ink jet recording apparatus according to the present embodiment can also perform multipass recording in which an image is recorded by scanning the same recording area a plurality of times. In multipass printing, dots forming one line are formed using a plurality of different nozzles. As a result, it is possible to suppress density unevenness due to slight differences in the ink ejection amount and ejection direction for each nozzle, and at the same time to reduce the recording duty for each pass to prevent image quality deterioration due to ink bleeding or the like. In the present embodiment, print data for multipass printing is generated using a mask table.

  FIG. 2 is a block diagram showing a schematic configuration of recording data generation for performing the multi-pass recording control and the recording data generation processing related to the multi-pass recording control of the present embodiment, and executes the processing described later in FIG. Specifically, these configurations are configured by the CPU, ROM, RAM, and the like in the recording apparatus of the present embodiment as described above.

  In FIG. 2, reference numeral 102 denotes a memory unit which temporarily stores image data input from the outside after being subjected to predetermined image processing. Reference numeral 101 denotes an input control unit, which performs recording data writing processing on the memory unit 102. Reference numeral 103 denotes an output control unit, which performs recording data read processing according to the position of the recording head 301 on the surface of the recording paper 306. A table storage unit 104 stores a mask table created according to the number of passes of multi-pass printing. Details of the mask table will be described later. Reference numeral 105 denotes a mask processing unit, which performs mask processing of image data using a mask table stored in the table storage unit 104, and generates print data for each pass.

  Reference numeral 106 denotes an original table storage unit configured in the control unit 110, and stores table data serving as a basis for generating a mask table. Details of the table data will be described later. Reference numeral 107 denotes a table generation unit configured in the control unit 110, which generates a mask table based on the original table data stored in the original table storage unit 106 and stores it in the table storage unit 104. Reference numeral 108 denotes a non-ejection complement control unit configured in the control unit 110. The mask table generation process executed by the table generation unit 107 is changed according to a detection result input from a non-ejection nozzle detection unit (not shown). Take control. Reference numeral 110 denotes a control unit that manages each unit and performs various types of control related to generation of print data for each pass.

  Next, recording data generation processing for each pass in the above configuration will be described. When the binary scanned image data is input, it is temporarily stored in the memory unit 102 via the input control unit 101. Based on the print area control from the control unit 110, the output control unit 103 outputs the binary image data stored in the memory unit 102 for each scan according to the position of the nozzle group corresponding to each ink color on the recording paper 306 surface. Read and output sequentially. Here, one data transfer unit is data for 64 pixels corresponding to the number of nozzles. The mask processing unit 105 executes mask processing of image data using the mask table stored in the table storage unit 104, and generates and outputs print data for each pass of multipass printing.

  3A to 3D are diagrams showing an example of the mask table of the present embodiment, and show a mask table (hereinafter also simply referred to as “mask”) used in 4-pass multi-pass printing.

  Masks A, B, C, and D shown in FIGS. 3A to 3D are masks used in the first pass, the second pass, the third pass, and the fourth pass, respectively, and they are complementary to each other. Is. Each of the mask tables A to D is a mask having a size corresponding to 1024 pixels in the main scanning direction × 16 pixels in the sub scanning direction, and this is repeatedly developed in each direction and used as a mask. In the case of this embodiment, since the number of nozzles provided in the recording head 301 is 64, the number of pixels corresponding to the recording paper conveyance amount in 4-pass recording is 64/4 = 16, which is in the sub-scanning direction of the mask table. Match the size. In other words, in four scans (four passes), recording of an area having a width of 16 pixels in the sub-scanning direction is completed.

  FIG. 4 is a diagram for explaining the operation of 4-pass multi-pass printing using the mask shown in FIG.

  For 64 lines of image data corresponding to 64 nozzles arranged in the recording head 301, the mask tables A, B, C, and D are sequentially applied every 16 lines according to scanning (pass). In other words, corresponding to all of the 64 nozzles of the recording head, mask processing using the masks A, B, C, and D is performed from the lower side of the nozzle array to generate 64 lines of recording data, The 64 lines are recorded by scanning the recording head. Then, paper feeding in the sub-scanning direction for 16 lines is performed for each scan. By repeating this scanning and paper feeding, recording of a scanning area having a width of 16 lines is completed in four scans.

  Next, mask table generation control executed by the table generation unit 107 described with reference to FIG. 2 will be described.

Normal Mask Table Generation First, a normal mask table generation method will be described. The table generation unit 107 generates four mask tables A, B, C, and D based on the original table data stored in the original table storage unit 106 and outputs them to the table storage unit 104 in the case of four passes. The original table data has a size of 1024 pixels in the main scanning direction × 32 pixels in the sub-scanning direction. 8-bit data is described in each pixel, and the 8-bit data is arranged as a random number in the above-described array of 1024 pixels × 32 pixels.

  In 4-pass printing, first, 8-bit data is divided by 4 for each pixel to generate remainders 0, 1, 2, and 3. When the remainder is 0, “1” is written in the mask pixel corresponding to the mask A, when the remainder is 1, the mask B, when the remainder is 2, the mask C is written, and when the remainder is 3, the mask D is written. When the mask pixel is “1”, recording by the recording data of the corresponding pixel is permitted, and when it is “0”, recording by the recording data of the corresponding pixel is not permitted. In the case of 4-pass printing, since the mask table size is 16 pixels in the sub-scanning direction, all of the original table data (32 pixels in the sub-scanning direction) is not used. 16 pixels are used. In the case of 2-pass printing, similarly, two mask tables A and B are created using the remainders 0 and 1 obtained by dividing each 8-bit data by 2. In this case, the size of each generated mask table in the sub-scanning direction is 32 pixels.

Mask table generation when a line where a non-ejection nozzle is detected is a complementable line Next, a mask table generation method when a non-ejection nozzle is detected will be described.

  The basic generation procedure is the same as the normal mask table generation described above. Here, the non-ejection nozzles are not limited to nozzles that cannot eject ink at all, but are nozzles in which ejection failure has occurred, such as the size and flying direction of ink droplets being extremely unstable or not being ejected normally. Point to.

  The non-ejection nozzle detection unit detects non-ejection of ink in units of nozzles, and this detection operation is executed at the start of page recording. A known configuration can be used for this detection. For example, a predetermined pattern is actually recorded, and the user detects a nozzle that has failed from the recorded pattern. Then, the user inputs the information directly to the recording apparatus or via the host apparatus. This input information can be used in the above detection operation. Alternatively, the non-ejection nozzle may be automatically detected from the pattern by, for example, optical means, and the information may be stored in a predetermined memory.

  When a non-ejection nozzle is detected, the non-ejection complement control unit 108 of the control unit 110 is notified of the nozzle number of the non-ejection nozzle. The non-ejection complement control unit 108 is a period of time until non-ejection is avoided and resumption of a good ejection operation is confirmed, and one of the other nozzles that forms dots of the same line as the non-ejection nozzle according to the notified nozzle number. Instructs the generation and modification of the mask table applied to each. In response to this, the table generation unit 107 generates a mask table corresponding to the number of passes based on the original table data. For example, in 4-pass printing, a line in a main scanning direction is complementarily printed by different nozzles in four scans to complete image formation. For this reason, the lines that are recorded by the nozzles that have been detected as non-ejection involve the other three nozzles in recording in another three scans. Then, one of these three nozzles is controlled so as to realize normal image formation by forming dots to be recorded by the non-ejection nozzle.

  This will be described in detail with a specific example.

  FIG. 5 is a diagram illustrating the correspondence between the 64 nozzles arranged in the recording head 301 and the nozzle numbers (# 0 to # 63). This figure shows the case of 4-pass printing, in which the print head 301 is divided into broken lines for each area corresponding to the masks A, B, C, and D. That is, nozzles # 0 to 15 correspond to mask A, nozzles # 16 to 31 correspond to mask pattern B, nozzles # 32 to 47 correspond to mask pattern C, and nozzles # 48 to 63 correspond to mask pattern D. It corresponds.

  FIGS. 6A to 6D show an example of a mask table generated when non-ejection is detected by nozzle # 20 with respect to the mask table shown in FIGS. 3A to 3D. FIG.

  The mask tables shown in FIGS. 6A to 6D show the case of the nozzle # 20 in which non-ejection has occurred, and the nozzle # 36 that can normally eject the dot to be recorded by the nozzle # 20 is complemented. The table data is generated to be recorded. Specifically, since printing cannot be performed with nozzle # 20, all positions corresponding to nozzle # 20 in table B in FIG. 6B are set to “0”. For the pattern corresponding to the nozzle # 36 of the table C in FIG. 6C, “1” (indicating printing permission) corresponding to the nozzle # 20 of the table B in FIG. The pattern is added to the position corresponding to the nozzle # 36 of the table C in c).

  As described above, it is assumed that ink ejection failure is detected at the nozzle # 20. In this case, the nozzle of nozzle number # 20 is a nozzle area to which the mask table B is applied, and corresponds to the fifth line of the mask table B. Other nozzles that form dots on the same line as the dots recorded by the nozzle # 20 are nozzle # 4 (applying mask table A), nozzle # 36 (applying mask table C), nozzle # 52 (mask table) D is applied). In the example shown in the figure, the dot to be formed by the non-ejection nozzle # 20 is complementarily recorded using the nozzle of nozzle number # 36 to which the mask table C is applied.

  For this reason, the table data generation process for the fifth line of the mask table C applied to the nozzle # 36 is controlled differently from the normal generation described above. That is, when the mask data for the fifth line of the mask table C is generated from the original table data, in addition to the dot position corresponding to the remainder 2 divided by 4 as usual, the mask pixel corresponding to the remainder 1 is applied to the mask pixel. Also describes 1. As a result, the dots to be recorded by the nozzle of nozzle number # 20 that has become a non-ejection nozzle can be distributed to the nozzle of nozzle number # 36 that can be ejected normally, and normal image formation can be realized. Further, for the fifth line of the mask table B corresponding to the nozzle # 20 which has become a non-ejection nozzle, control is performed so that all the recording dots are not given regardless of the value stored in the original table storage unit 106.

  In the above example, the recording dots of the non-ejection nozzles of the mask table B are distributed to the mask table C corresponding to the nozzles on the same line. Similarly, the non-ejection nozzles corresponding to the mask table C are allocated to the mask table D, the nozzles corresponding to the mask table D are allocated to the mask table A, and the nozzles corresponding to the mask table A are allocated to the mask table B. Can do.

Next, a method for generating a mask table when a line that cannot be complemented by other nozzles that form the same line as described above will be described. That is, a description will be given of mask table creation when all of the nozzles used to form one line of dots are non-ejection.

  FIG. 7 is a flowchart showing a mask table generation process when a complementary record impossible line is detected according to the first embodiment of the present invention.

  In FIG. 7, the processes of steps S101 to S103 are the processes described above with reference to FIGS. That is, this process is started when a non-ejection nozzle is detected at the start of recording of a predetermined amount such as one page. Then, the table generation unit 107 reads the original table from the original table storage unit (S101). Further, the non-ejection complement control unit 108 performs change control of the table generation process in response to the detection result input from the non-ejection detection unit (S102). In addition, a mask table is created so that the nozzles that can perform normal ejection are complementarily recorded by the nozzles that can eject normally (S103).

  Next, the control unit 110 determines whether or not all of the portions corresponding to the plurality of nozzles forming one line of dots are “0” in the created mask table (S104). When the dots to be formed by the non-ejection nozzles can be distributed to other nozzles that can be ejected normally by the processing described in FIGS. 6A to 6D, the portions corresponding to all the nozzles are “ It does not become “0”. That is, the portion corresponding to the other nozzles thus distributed is a pattern in which the original “1” and the complementary “1” are added, and the portions corresponding to all the nozzles are “0”. do not become. In that case, the mask table is directly output to the table storage unit (S108).

  On the other hand, when the portions corresponding to all the nozzles that form dots of the same line are “0” in all the mask tables, the number of lines S is measured. And it compares with the threshold value N mentioned later in FIG. 9 (S105).

  If the comparison result is equal to or less than the threshold value N, the created mask table is output as it is to the table storage unit (S108). On the other hand, if the number of lines S is larger than the threshold value N, it is determined whether or not the number of recording passes can be changed (S106). This determination is performed in consideration of the case where it is not desirable to change the number of passes to a larger number of passes due to the relationship between the type of recording medium to be used and its conveyance accuracy, as will be described later in Embodiment 3. In the embodiment, the recording medium type is used as a reference.

  If it is determined in step S106 that it can be changed, the control information is changed to change the number of recording passes, and the process returns to step S101 so that a mask table corresponding to the changed number of recording passes is created again. .

  On the other hand, when it is determined that the number of recording passes cannot be changed, the user is prompted to determine whether or not to continue recording via the operation unit (S107). If the user does not wish to continue recording, the table generation process is temporarily terminated and the control information is cancelled. If it is desired to continue recording, the mask table created so far is output to the table storage unit (S108).

  FIGS. 8A to 8D are diagrams showing mask tables that are referred to in order to determine whether or not the mask data for one line in step S104 is all “0”. Specifically, it is generated when it is detected that nozzles # 4, # 20, # 36, and # 52 are not ejecting simultaneously with respect to the mask table shown in FIGS. An example of a mask table is shown. In this case, since the recording data by the non-ejection nozzles cannot be complementarily recorded, the mask data of the lines corresponding to these non-ejection nozzles are all “0”, that is, the recording is performed regardless of the values stored in the original table storage unit 106. The data is not allowed.

  In step S104, the control unit 110 compares the mask tables A to D and confirms that all the mask data corresponding to the nozzle # 4 of the mask table A are “0”. Then, it is checked whether or not all the mask data corresponding to the nozzles # 20, # 36, and # 52 forming the same line as the nozzle # 4 is “0”. In this way, it is determined that all the data in the mask table corresponding to one line is “0”. The mask data corresponding to other lines is similarly examined, and the number S of lines in which the mask table data corresponding to one line is all “0” is detected.

  FIG. 9 is a diagram illustrating the threshold value N used in step S105. Specifically, an example of a threshold value table of the allowable number of non-ejection lines corresponding to the type of seed recording medium and the number of passes of multi-pass printing stored in a ROM (not shown) of the control unit 110 is shown.

  In a recording medium such as plain paper in which ink is likely to bleed on the medium, even if a non-ejection line exists, dots of other lines bleed into the non-ejection line and are difficult to be visually recognized. On the other hand, when a recording medium such as coated paper or glossy paper is provided with an ink receiving layer, the ink droplets are fixed on the receiving layer and are difficult to bleed. Therefore, the non-ejection line is easily visually recognized as a white line with missing dots. In particular, in a recording medium such as glossy paper that requires high-quality photographic quality, if even one non-ejection line exists in a recording mode with a small number of passes, such as four passes, streaks are visually recognized and image quality is degraded. End up.

  From the above points, as shown in FIG. 9, for example, in the 4-pass printing mode using glossy paper, the threshold value N is set to 0 in order to change the number of passes if even one line has a non-ejection line.

  In the present embodiment, the number of passes to be changed is changed to the number of passes in the recording mode in which the number of one-step passes is large in the recording mode for each recording medium shown in FIG. Accordingly, in the 4-pass printing mode for glossy paper, if there are one or more non-ejection lines, the mode is changed to the 8-pass mode.

  FIGS. 10A to 10H are diagrams showing the mask table generated again in steps S101 to S103 when the mode is changed to the 8-pass printing mode.

  10A to 10H, the size of each mask table in the sub-scanning direction is 8 pixels. As shown in FIG. 11, the mask tables A1, A2, B1, B2,. C1, C2, D1, and D2 are applied in this order. Non-ejection nozzles # 4, # 20, # 36, and # 52 shown in FIGS. 8A to 8D correspond to the mask tables A1, B1, C1, and D1 in FIGS. 10A to 10H. Mask data exists, and these are set to “0” and recording is not permitted. On the other hand, in the mask tables A2, B2, C2, and D2, nozzles # 12, # 28, # 44, and # 60 that can normally eject dots to be formed by the nozzles # 4, # 20, # 36, and # 52. Are generated to complement each other.

  Thus, even when ink ejection failure is detected and complementary recording cannot be performed with nozzles that form the same line in different scans, ejection failure should be recorded by changing the number of recording passes. A dot can be distributed to another dot. As a result, image omission due to ejection failure can be avoided and normal image formation can be realized.

  As described above, according to this embodiment, in multi-pass printing, it is possible to avoid image defects even when all the nozzles forming the same line are defective in ejection. is there. That is, the number of complementary recording impossible lines is detected, and when it is determined that the predetermined threshold is exceeded, the number of recording passes is changed. At the same time, a part of the mask table generation is changed and controlled, and the dots to be recorded by the nozzles in which non-ejection has been detected are assigned to the nozzles forming the same line in another scan and complementarily recorded. As a result, a normal recording function can be continued without replacing the recording head. Also, in this case, when the number of complementary recording impossible lines is less than or equal to the threshold value, recording is performed as it is without changing the number of passes because there is little decrease in recording quality due to non-ejection, so the number of passes increases more than necessary. A decrease in throughput can also be avoided. As a result, it is possible to provide an excellent ink jet recording apparatus that realizes a low running cost by increasing the reliability of the apparatus and extending the apparent life of the recording head without adding a large-scale dedicated circuit.

  In this embodiment, when the number of non-ejection lines is larger than the threshold value, the control is made to automatically change the number of recording passes. However, before changing the number of recording passes, the user is prompted to change manually or automatically. The change mode and the manual change mode may be switched.

(Embodiment 2)
The second embodiment relates to a configuration in the case where the number of complementary record impossible lines is equal to or less than the threshold value of the allowable non-ejection line number. Specifically, it relates to details of processing when it is determined in step S105 of FIG.

  FIGS. 12A to 12D show nozzles # 0, # 4, # 16, # 20, # 32, # 36, and # 48 with respect to the mask table shown in FIGS. 3A to 3D. , # 52 is a diagram showing an example of a mask table generated when it is detected that no ejection is performed simultaneously.

  In this example, since the recording data from the non-ejection nozzles cannot be complementarily recorded, the mask data corresponding to these nozzles is set to 0 regardless of the values stored in the original table storage unit 106, and the mask table is not allowed to be recorded. It becomes.

  In this case, in step S104, the control unit compares the mask tables A to D, and all the mask tables corresponding to the nozzles # 0 and # 4 of the mask table A and the other nozzles that record the lines recorded by these nozzle tables. Is determined to be “0”. In step S104, it is detected that the number of lines is two.

  As shown in FIG. 9, when plain paper is used, the number of allowable non-ejection lines for four-pass printing is three. Therefore, the control unit compares the threshold value = 3 with the number of complementary record impossible lines = 2, and determines that the number of complementary record impossible lines is smaller than the threshold value. At this time, although the created mask table has two complementary recording impossible lines, it is output to the table storage unit as it is (S108).

  By performing the process associated with mask table generation, when it is difficult to visually recognize non-ejection lines such as plain paper as missing images, throughput is maintained while maintaining the image quality without changing the number of recording passes. It is not necessary to lower the Further, since recording can be performed in a recording mode that is optimal for the state of the recording head, it is effective in that an increase in running cost can be suppressed without performing head replacement.

(Embodiment 3)
The third embodiment relates to a mode in which the number of complementary recording impossible lines is larger than the threshold value in the threshold table of allowable non-ejection lines, but the number of recording passes cannot be changed. Specifically, mask table generation control will be described in detail with respect to an ink jet printing apparatus having the same configuration as in the first embodiment except that it is determined in step S106 in FIG. 7 that the number of passes cannot be changed.

  FIGS. 13A to 13D show nozzles # 0, # 2, # 4, # 5, # 16, # 18, # 20, # 21, # 32, # 34, # 36, # 37, # 48. , # 50, # 52, # 53 shows an example of a mask table generated when non-ejection is simultaneously detected.

  In this example, in this example, since the recording data by the non-ejection nozzles cannot be complementarily recorded, the mask data corresponding to these nozzles is set to 0 regardless of the values stored in the original table storage unit 106, and recording is allowed. It becomes a mask table so as not to.

  In this case, in step S104, “0” is set in all the mask tables corresponding to the nozzle # 0, nozzle # 2, nozzle # 4, and nozzle # 5 of the mask table A, and other nozzles that record the lines recorded by these nozzles. Is determined. In step S104, it is detected that the number of lines is four.

  As shown in FIG. 9, when plain paper is used, the number of allowable non-ejection lines for four-pass printing is three. Therefore, the control unit compares threshold = 3 with the number of complementary record impossible lines = 4, and determines that the number of complementary record impossible lines is larger than the threshold.

  Accordingly, it is next determined in step S106 whether the number of passes can be changed. In this determination, it is sometimes difficult for a slippery recording medium such as plain paper to have many passes in order to ensure the accuracy of paper conveyance. In that case, it is determined that the number of recording passes cannot be changed. Then, the user is prompted to determine whether or not to continue recording via the interface unit (S107). If the user does not wish to continue recording, the table generation process is temporarily terminated and the control information is cancelled. If it is desired to continue recording, the created mask table is output to the table storage unit (S108).

  By performing the process associated with the mask table generation, the user can select an appropriate recording method according to the type of the recorded image even when the number of lines that cannot be complemented is large. For example, in the case of a recorded image with a plurality of inks where image omission due to non-ejection lines is not noticeable, recording without reducing image quality and reducing throughput even if recording is selected as it is. It can be performed. In addition, in a solid image or the like with a single ink in which image omission due to a non-ejection line is conspicuous, it is possible to prevent misprinting by selecting the recording stop and prevent waste of the recording medium and ink.

FIG. 2 is a diagram schematically illustrating a configuration of a recording unit of the ink jet recording apparatus according to the first embodiment of the present invention. FIG. 3 is a block diagram illustrating a schematic configuration of print data generation for performing multi-pass print control and print data generation processing related thereto according to the first embodiment. (A)-(d) is a figure which shows an example of the mask table of 1st Embodiment. It is a figure explaining the multipass printing using the mask table shown in FIG. FIG. 4 is a diagram illustrating a correspondence between nozzles and nozzle numbers of a recording head according to an embodiment of the present invention. (A)-(d) is a figure which shows an example of the mask table produced | generated when a non-ejection is detected with nozzle # 20 with respect to the mask table shown to Fig.3 (a)-(d). is there. It is a flowchart which shows the mask table production | generation process at the time of detecting the complementary recording impossible line which concerns on 1st embodiment of this invention. (A)-(d) is a figure which shows the mask table referred in order to judge whether the mask data of 1 line of FIG.7 S104 are all "0". It is a figure explaining the threshold value N used by step S105 of FIG. (A)-(h) is a figure which shows the mask table produced | generated again by step S101-S103 of FIG. 7 when it changes from 4 pass to 8 pass recording mode. It is a figure explaining the multipass printing using the mask table shown in FIG. (A) to (d) are nozzles # 0, # 4, # 16, # 20, # 32, # 36, # 48, # 48 to the mask table shown in FIGS. It is a figure which shows an example of the mask table produced | generated when it detects that 52 is non-ejection simultaneously. (A) to (d) are nozzles # 0, # 2, # 4, # 5, # 16, # 18, # 20, # 21, # 32, # 34, # 36, # 37, # 48, # It is a figure which shows an example of the mask table produced | generated when non-ejection is detected simultaneously in 50, # 52, and # 53.

Explanation of symbols

301 Recording Head 101 Input Control Unit 102 Memory Unit 103 Output Control Unit 104 Table Storage Unit 105 Mask Processing Unit 106 Original Table Storage Unit 107 Table Generation Unit 108 Non-ejection Control Unit 110 Control Unit

Claims (6)

An ink jet recording apparatus that performs recording by scanning a recording medium in which a plurality of nozzles for ejecting ink are arranged, and performing recording, by performing multiple scanning of the recording head and relative conveyance of the recording medium to the recording head. In the ink jet recording apparatus capable of performing multi-pass recording in which dots constituting one line in the scanning direction are formed by a plurality of different nozzles,
Non-ejection nozzle detection means for acquiring information on non-ejection nozzles in the recording head;
According to the information acquired by the non-ejection nozzle detection means, it is detected that all of the plurality of different nozzles used for forming dots constituting the one line are non-ejection, and the plurality of different nozzles are detected. A non-ejection line number detecting means for detecting the number of all non-ejection lines;
Pass number changing means for changing the number of scans for forming dots constituting one line in accordance with the number of lines detected by the non-ejection line number detecting means;
In accordance with the number of scans changed by the pass number changing means, different nozzles used for forming dots constituting the one line are determined so that dots to be formed by the non-ejection nozzles are formed by other nozzles. First nozzle setting means;
An ink jet recording apparatus comprising:   The non-ejection line number detection means includes a second nozzle setting means for determining different nozzles used for forming dots constituting the one line according to the information acquired by the non-ejection nozzle detection means. 2. The ink jet recording apparatus according to claim 1, wherein it is detected that all of different nozzles used for forming dots constituting the one line defined by the means are non-ejection.   When all the different nozzles used for forming the dots constituting the one line are not non-ejection and some of the nozzles are non-ejection, the non-ejection nozzle is a non-ejection nozzle. 3. The ink jet recording apparatus according to claim 2, further comprising third nozzle setting means for determining different nozzles used for forming dots constituting the one line so as to form dots to be formed. .   Each of the first, second, and third nozzle setting means has a mask corresponding to the nozzle for each of the plurality of scans, each mask defines mask data corresponding to the nozzle, and the mask data is 4. The ink jet recording apparatus according to claim 2, wherein different nozzles used for forming dots constituting the one line are determined by generating the same.   5. The path number changing unit changes the number of times of scanning when the number of lines detected by the non-ejection line number detecting unit is larger than a predetermined threshold. The ink jet recording apparatus described. An ink jet recording apparatus that performs recording by scanning a recording medium in which a plurality of nozzles for ejecting ink are arranged, and performing recording, by performing multiple scanning of the recording head and relative conveyance of the recording medium to the recording head. In the recording control method of an ink jet recording apparatus capable of performing multipass recording in which dots constituting one line in the scanning direction are formed by different nozzles,
A non-ejection nozzle detection step of acquiring information on non-ejection nozzles in the recording head;
According to the information acquired in the non-ejection nozzle detection step, it is detected that all the different nozzles forming the dots constituting the one line are non-ejection, and all the different nozzles are non-ejection. A non-ejection line number detection process for detecting the number of lines,
According to the number of lines detected in the non-ejection line number detecting step, a pass number changing step for changing the number of scans for forming dots forming the one line,
According to the number of scans changed by the pass number changing means, different nozzles used for forming dots constituting the one line are determined so that dots to be formed by the non-ejection nozzles are formed by other nozzles. 1 nozzle setting process;
A recording control method characterized by comprising:

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