JP5448528B2 - Recording apparatus and recording method - Google Patents

Description

  The present invention relates to a recording apparatus and a recording method for reducing image quality degradation caused by a recording position shift in a recording scan unit when performing multipass recording using a serial type recording apparatus.

  A serial type ink jet recording apparatus uses a recording head provided with a plurality of recording elements (nozzles) for ejecting ink. Then, recording is performed by repeating the recording scan in which ink is ejected while moving the recording head with respect to the recording medium with the conveyance operation interposed. Between a plurality of recording elements, there is inevitably some variation in the amount and direction of ink ejection, and this variation may cause uneven density in the image. As a method for reducing such density unevenness and lines, a multi-pass printing method as disclosed in, for example, Patent Document 1 is conventionally known.

  FIG. 1 is a schematic diagram for explaining a general multi-pass printing method disclosed in Patent Document 1. In FIG. P0001 denotes a recording head. Here, for simplicity, it is assumed that it has 16 recording elements (nozzles). As shown in the drawing, the nozzles are divided into first to fourth nozzle groups, and each nozzle group includes four nozzles. P0002 indicates a mask pattern, and a recording permissible area (black) that allows dot recording and a non-recording permissible area (white) that does not allow dot recording are determined in advance. The mask patterns recorded by each nozzle group are complementary to each other. When these are overlapped, the unit area corresponding to the 4 × 4 area is recorded.

  Each pattern indicated by P0003 to P0006 shows a state in which an image is completed by overlapping recording scans. When each recording scan is completed, the recording medium is conveyed by the width of the nozzle group in the direction of the arrow in the figure. Therefore, the unit area of the recording medium (area corresponding to the width of each nozzle group) is configured such that an image is completed by four recording scans.

  If such multi-pass printing is performed, each region of the recording medium is recorded by a plurality of nozzle groups in a plurality of scans, so that dispersion unique to the nozzles and variation in transport accuracy of the recording medium are dispersed, resulting in uneven density. Streaks can be reduced.

  In FIG. 1, the mask pattern P0002 is shown as an example. However, in such a mask pattern, various effects can be obtained by devising the arrangement of the print permitting area.

  For example, Patent Document 2 discloses a technique for outputting a uniform image with a suppressed graininess by determining the arrangement of the printable area using a repulsive potential and enhancing the dispersibility of the recorded dots. ing.

Japanese Patent Laid-Open No. 5-31922 JP 2006-44258 A JP 2001-322262 A JP 2003-237141 A

  However, in recent years, by performing the multi-pass printing, a change in density caused by a shift in printing position (registration) in printing scan units has been newly regarded as a problem.

  FIG. 2 is a diagram for conceptually explaining a recording position shift state in a case where 4-pass multi-pass printing is performed. In the figure, the relative positional relationship between a plurality of unit areas including A to C and the recording head when a uniform halftone image is recorded on the recording medium by the first to eighth recording scans is shown.

  In the case of performing 4-pass multi-pass printing, a plurality of dots are recorded in each unit area of the printing medium in each of four printing scans (1 to 4 passes). At this time, the plurality of dots recorded in each recording scan can be considered as a group of dots arranged in one plane. The recording position deviation in the recording scanning unit can be regarded as a relative recording position deviation between the dot groups recorded in different recording scans. In the figure, a case where a conveyance deviation occurs between the fourth recording scan and the fifth recording scan is shown.

  At this time, in the unit area A, a conveyance shift has occurred between the third pass and the fourth pass in the four recording scans. In this case, in the unit area A, the dot group recorded in the fourth pass is arranged so as to be shifted relative to the dot group recorded in the first to third passes. That is, about 25% of the dot group is shifted from about 75% of the dot group.

  Further, in the unit area B, conveyance deviation occurs between the second pass and the third pass among the four printing scans. In this case, the dot groups recorded in the first pass and the second pass are arranged so as to be shifted relative to the dot groups recorded in the third pass and the fourth pass. That is, two sets of dots of about 50% are shifted from each other.

  Further, in the unit area C, a conveyance deviation occurs between the first pass and the second pass among the four printing scans. In this case, the dot group recorded in the first pass is arranged so as to be shifted relative to the dot group recorded in the second to fourth passes. That is, about 25% of the dot group is shifted from about 75% of the dot group.

  When such a shift between the dot groups occurs, there are places where dots that are determined to be printed at different positions by different printing scans depending on the mask pattern overlap each other. As a result, the dot coverage (area factor) with respect to the recording medium decreases and the density decreases. Among the three unit areas, the unit area B in which the dot groups of 50% are shifted from each other is the area where the variation of the area factor is the largest and the density is the lowest. When the unit areas A to C in which such a recording position deviation occurs and the unit areas in which no recording position deviation occurs are mixed on the same recording medium, the above phenomenon is recognized as density unevenness in the image.

  The mask pattern disclosed in Patent Document 2 and the like has been devised so as to arrange dots in a state where the dispersibility is as high as possible as much as possible in order to emphasize graininess in a normal state where there is no recording position shift. . For this reason, when a recording position shift occurs between the dot groups due to a sudden transport shift or the like, the dispersibility of the dots is lost, and the above-described image adverse effect due to the decrease in density is also conspicuous.

  On the other hand, for example, Patent Document 3 discloses a technique for avoiding a decrease in density and banding even if a recording medium conveyance shift occurs by providing an area that allows dot recording to be overlapped. Has been. According to this method, even if the recording position shift occurs, the area factor is increased to some extent by separating the overlapping dots from each other, so that it can be expected to suppress the decrease in density.

  However, Patent Document 3 does not pay attention to the fact that the degree of density reduction differs in each unit region. As a result, the number of overlapping dots separated from each other for each unit region is almost equal, and the variation in density variation between unit regions cannot be made uniform. In the case of FIG. 2, the state in which the density of the unit region B is lower than that of other unit regions has not yet been solved.

  In other words, in view of any of the conventional techniques, when a recording position shift due to a sudden transport shift or the like occurs, it is not possible to reliably and reliably suppress density fluctuations for all unit areas. It was a possible situation.

  The present invention has been made to solve the above problems. Therefore, the purpose is to reduce the density fluctuation in the unit area reliably and to an appropriate amount even if printing position deviation occurs between a plurality of printing scans when performing multi-pass printing, and to produce an image without density unevenness. To provide a recording apparatus and a recording method for outputting. Also, it is possible to output such a high-quality image in any of various recording modes with different numbers of multi-passes.

Therefore, in the present invention, a recording head having a nozzle row in which nozzles for recording dots of the same color on the recording medium are arranged in the first direction is crossed with the unit direction of the recording medium in the first direction. A recording apparatus that records an image in the unit area by scanning a plurality of times in the second direction, wherein the image is recorded in the unit area by scanning 2N times (N is an integer of 2 or more) . Setting means for setting one recording mode from a plurality of recording modes including one recording mode and a second recording mode in which the number of scans for recording the unit area is larger than that in the first recording mode. When, in accordance with the multi-tone image data representing a tone of the image corresponding to the unit region, the second respectively about by dot recording or non plurality of areas arranged in a direction corresponding to the direction A plurality of column data is determined so that a dot arrangement pattern for which recording is determined is determined, and data corresponding to each area of the determined dot arrangement pattern is collected as column data for recording in different scans every predetermined number of areas. generating means for generating a plurality of types of column data by partitioning, the plurality of types of the respective column data, by using a mask pattern defining a recording allowable or non printable dots with respect to the column data, a plurality of times Recording is performed in a unit area by scanning a plurality of times by the recording head so that the plurality of types of column data are overlapped on the recording medium in accordance with the recording data and distribution means that distributes the recording data corresponding to scanning. comprising a recording unit, a case where the first recording mode is set, the generation unit, the Odd column data and even column data are generated from the first dot arrangement pattern determined in accordance with gradation image data, and the distribution unit is configured such that the recording unit includes dots corresponding to the odd column data. The number of overlapping dots that are recorded with overlapping dots on the recording medium between the Nth scan and the N + 1th scan when the dots corresponding to the even-numbered column data are recorded on the recording medium. However, each of the odd-numbered column data and the even-numbered column data is set to print data corresponding to 2N scans so that the number of the overlapped dots is larger than the number of the overlapping dots printed between other successive print scans. partitioned, when the second recording mode is set, the generating means, the dot which the recording means corresponding to said plurality of types of column data by duplicated in the recording medium When recording, the first dot arrangement pattern having a larger number of areas than the first dot arrangement pattern in which the dot arrangement is determined so that two dots recorded by different scans are recorded adjacently occurs. 2 dot arrangement patterns are determined according to the multi-gradation image data, and the distribution means uses a mask pattern having higher dispersibility of print permitting dots than the mask pattern used in the first print mode. Each of the plurality of column data is distributed to the print data corresponding to the plurality of scans .

Further, a recording head having a nozzle row in which nozzles for recording dots of the same color on the recording medium are arranged in a first direction is arranged in a second direction intersecting the first direction with respect to the unit area of the recording medium. A recording method for recording an image in the unit area by scanning a plurality of times,
The first recording mode for recording an image in the unit area by 2N (N is an integer of 2 or more) times, and the number of scans for recording the unit area is larger than that in the first recording mode. According to the setting step of setting one recording mode from a plurality of recording modes including the second recording mode, and the multi-gradation image data indicating the gradation of the image corresponding to the unit area, the first determine the recording or dot arrangement pattern non-recording is defined dots with a plurality of areas arranged in a direction corresponding to the second direction, the predetermined data corresponding to each area of the determined dot arrangement patterns A generation process for generating multiple types of column data by distributing the data to multiple column data so that the data is recorded in different scans every other number of areas. , Each of the plurality of types of column data, by using a mask pattern defining a recording allowable or non printable dots with respect to the column data, and the distribution process for distributing the print data corresponding to a plurality of scans, the recording data And a recording step of recording in a unit area by scanning a plurality of times by the recording head so that the plurality of types of column data are overlapped on the recording medium, and the first recording mode is set In the generation step, odd column data and even column data are generated from the first dot arrangement pattern determined according to the multi-tone image data, and in the distribution step, the recording step , The dots corresponding to the odd-numbered column data and the dots corresponding to the even-numbered column data are recorded on the recording medium in an overlapping manner. In this case, the number of overlapping dots that are recorded by overlapping dots on the recording medium with the interval between the Nth scan and the N + 1th scan being recorded between other consecutive recording scans. When the odd-numbered column data and the even-numbered column data are each distributed to print data corresponding to 2N scans and the second print mode is set so as to be larger than the number of overlapping dots , In the generating step, when the recording unit records dots corresponding to the plurality of types of column data by overlapping them on a recording medium, a place where two dots recorded by different scans are recorded adjacently occurs. Thus, a second dot arrangement pattern composed of a larger number of areas than the first dot arrangement pattern in which the dot arrangement is determined is determined according to the multi-tone image data, and the distribution In the step, each of the plurality of column data is distributed to the print data corresponding to the plurality of scans by using a mask pattern having higher dispersibility of print-allowable dots than the mask pattern used in the first print mode. It is characterized by being.

  According to the present invention, it is possible to stably output an image that is hardly affected by the recording position shift regardless of the number of multi-passes.

FIG. 10 is a schematic diagram for explaining a general multi-pass printing method disclosed in Patent Document 1. It is a figure for demonstrating notionally the state of a recording position shift at the time of performing 4-pass multipass printing. It is a schematic block diagram of the principal part of the inkjet recording device F102 applied by embodiment of this invention. FIG. 5 is a perspective view for explaining the configuration of a recording cartridge H1001 applicable to the embodiment of the present invention. It is a schematic block diagram for demonstrating the structure of the control system in the recording device F102 of embodiment of this invention. FIG. 3 is a block diagram for explaining a series of image processing steps of a recording system including a recording apparatus F102 according to an embodiment of the present invention and a host apparatus F101 that supplies image data to the recording apparatus F102. The handling of odd-numbered column data and even-numbered column data in the first recording mode is schematically described. FIG. 10 is a schematic diagram for explaining an example of a dot arrangement pattern that is referred to by a dot arrangement pattern setting unit F119 in the first recording mode in the first embodiment. It is a figure for demonstrating the relationship between the nozzle row 1000 of a certain color, and the mask pattern 1001 corresponding to a nozzle row. (A) And (b) is a figure which shows the ratio of the combination of the recording scan (pass) in which the overlapping dot in the mask pattern produced by the conventional method is recorded. It is the figure which compared the ratio by which the overlapping dot is recorded on both sides of each pass with the mask pattern used in this embodiment shown in FIG. 23, and the conventional mask pattern demonstrated in FIG. (A) And (b) is a figure explaining the influence on the density | concentration of the recording position shift when all the dots are single dots. (A) And (b) is a figure explaining the influence on the density | concentration of a recording position shift when all the dots are overlapping dots. It is a figure for demonstrating concretely the handling of the data in a dot arrangement pattern setting process at the time of using a 2nd dot arrangement pattern. FIG. 15 is a diagram for explaining another example of a dot arrangement pattern that is easily affected by a recording position shift, as compared with FIG. 14. FIG. 8 is a diagram showing the handling of odd-numbered column data and even-numbered column data when performing 8-pass multi-pass printing in comparison with FIG. 7. (A) And (b) is a figure for demonstrating the ratio of the combination of the printing scan (pass) in which the overlapping dot is recorded in the mask pattern for 8 passes produced by the conventional method, qualified with FIG. . It is the figure which compared the ratio by which the overlapping dot is recorded on both sides of each pass with the conventional three types of mask patterns from which the number of multipass differs. 6 is a flowchart for explaining a process in which the host apparatus F101 and the recording apparatus F102 in the first embodiment switch between the two recording methods according to a recording mode. The handling of data in the dot arrangement pattern setting unit F117 according to the embodiment of the present invention is schematically described. It is a schematic diagram for demonstrating an example of the dot arrangement pattern which the dot arrangement pattern setting means F119 of the 2nd Embodiment of this invention refers. 10 is a flowchart for explaining a process in which the host apparatus F101 and the recording apparatus F102 according to the second embodiment of the present invention switch between the two recording methods according to a recording mode. FIGS. 10A and 10B show the ratio of the combination of print scans in which overlapping dots of the mask pattern used in the first embodiment of the present invention are printed, as shown in FIGS. 10A and 10B. It is a figure for demonstrating compared with the mask pattern of a method. It is a figure showing level 1 in the 2nd dot arrangement pattern in a 1st embodiment. FIG. 25 is a diagram illustrating an arrangement state of print data when print data is duplicated according to the dot arrangement pattern shown in FIG. 24. FIG. 6 is a diagram illustrating a dot recording state on a recording medium.

(First embodiment)
The first embodiment of the present invention will be described in detail below. First, the main body configuration of the ink jet recording apparatus applied in the present embodiment will be described.

  FIG. 3 is a schematic configuration diagram of a main part of the ink jet recording apparatus F102 applied in the present embodiment. The chassis M3019 housed in the exterior member of the recording apparatus is composed of a plurality of plate-like metal members having a predetermined rigidity, and constitutes the skeleton of the recording apparatus, and holds each mechanism described below. The automatic feeding unit M3022 automatically feeds paper (recording medium) into the apparatus main body. The transport unit M3029 guides the recording medium sent one by one from the automatic feeding unit M3022 to a predetermined recording position, and guides the recording medium from the recording position to the discharge unit M3030. An arrow Y is the recording medium conveyance direction (sub-scanning direction). On the recording medium conveyed to the recording position, desired recording is performed by the recording unit. Recovery processing is performed on the recording unit by the recovery unit M5000. M2015 is a paper gap adjusting lever, and M3006 is a bearing for the conveying roller M3001.

  In the recording unit, the carriage M4001 is supported by the carriage axis M4021 so as to be movable in the main scanning direction (second direction) indicated by an arrow X that intersects the sub-scanning direction. A recording head cartridge H1001 capable of ejecting ink is detachably mounted on the carriage M4001.

  FIG. 4 is a perspective view for explaining the configuration of a recording cartridge H1001 applicable to the present embodiment. A recording head cartridge H1001 (hereinafter also simply referred to as a recording head) is composed of a recording head portion having a recording element for performing ejection and an ink tank holder. Each of the ink tanks H1900 can be attached to and detached from the recording head cartridge H1001 as shown in the figure, and supplies ink from the respective tanks to the corresponding recording element array. In the present embodiment, a recording head configuration is used in which four colors of black, cyan, magenta, and yellow are used, and a plurality of levels of ink can be ejected for each color.

  The recording element of the recording head in this embodiment has a mechanism in which film boiling occurs by applying a voltage to a heater provided in the ink path, and a predetermined amount of ink is ejected as droplets. The ejection ports that eject the same color and the same amount are arranged at a predetermined pitch in the sub-scanning direction (first direction), and the ejection port arrays that eject inks of different colors are in the main scanning direction (second scanning direction). Direction).

  Refer to FIG. 3 again. The carriage M4001 is provided with a carriage cover M4002 for guiding the recording head H1001 to a predetermined mounting position on the carriage M4001. Further, the carriage M4001 is provided with a head set lever M4007 that engages with the tank holder of the recording head H1001 to set the recording head H1001 at a predetermined mounting position. The head set lever M4007 is provided so as to be rotatable with respect to a head set lever shaft positioned at the upper part of the carriage M4001, and a spring-biased head set plate is provided at an engaging portion that engages with the recording head H1001. (Not shown) is provided. With the spring force, the head set lever M4007 attaches the recording head H1001 to the carriage M4001 while pressing it. The recording head H1001 mounted on the carriage H4001 obtains a head driving signal necessary for recording via a flexible cable E0012 from a main board (not shown).

  The recovery unit M5000 includes a cap (not shown) that caps the ink discharge port formation surface of the recording head cartridge H1001. A suction pump capable of introducing a negative pressure into the cap may be connected to the cap. In that case, a negative pressure is introduced into the cap covering the ink discharge port of the recording head cartridge H1001, and the ink is sucked and discharged from the ink discharge port. Accordingly, a recovery process (also referred to as “suction recovery process”) can be performed to maintain a good ink discharge state of the recording head H1001. Further, by discharging ink that does not contribute to image recording from the ink discharge port toward the inside of the cap, a recovery process (“discharge recovery process” or “preliminary discharge” is performed to maintain a good ink discharge state of the recording head H1001. ”).

  FIG. 5 is a schematic block diagram for explaining the configuration of the control system in the recording apparatus F102 of the present embodiment. The CPU B100 executes operation control of the entire recording apparatus, image data processing, and the like. The ROM B101 stores programs necessary for the CPU B100 to perform control and data necessary for recording such as dot arrangement patterns and mask patterns unique to the present invention. The CPU B100 appropriately refers to programs and data stored in the ROM B101, and executes various processes while using the RAM B102 as a work area. In addition to such a work area, the RAM B102 includes a reception buffer F115 that temporarily stores received image data, a print buffer F118 that stores recording data for driving the recording head H1001, and the like. ing.

  The recording apparatus F102 of the present embodiment receives image data from an externally connected host apparatus F101 via an interface (I / F) F114. The CPU B100 temporarily stores the received image data in the reception buffer F115 in the RAM B102, and performs image processing using various parameters stored in the ROM B101. The image data that has undergone a series of image processing is stored in the print buffer F118 in the RAM B102, and sequentially transferred to the head driver H1001A as the recording operation of the recording head H1001 proceeds. The head driver F1001A drives the recording head H1001 based on the received recording signal. Ink is ejected from the recording head H1001 by the CPU B100 supplying drive data (recording data) and a drive control signal (heat pulse signal) for the electrothermal transducer to the head driver H1001A. The CPU B100 drives the carriage motor B103 via the carriage motor driver B103A and scans the carriage M4001 at a predetermined speed together with the ejection operation of the recording head H1001. Thereby, one recording main scan is executed. When one recording main scan is completed, the CPU B100 drives the conveyance motor B104 via the conveyance motor driver B104A to convey (sub-scan) the recording medium in the first direction by a predetermined amount. By alternately repeating the main recording scan in the second direction and the sub-scanning in the first direction, the image received from the host device F101 can be recorded on the recording medium.

  FIG. 6 is a block diagram for explaining a series of image processing steps of a recording system including the recording apparatus F102 of this embodiment and a host apparatus F101 that supplies image data to the recording apparatus F102. In the present embodiment, the host device F101 first converts RGB multi-value (8 bits (256 values)) luminance data F110 into CMYK multi-values (CMYK multi-value (corresponding to ink colors) provided in the printing apparatus by the printing element separation unit F111. It is converted into density data of 8 bits (256 values). The density data at this time is assumed to have an image resolution of 600 dpi. Next, the n-value (n is an integer equal to or greater than 2) processing unit F112 is used to convert the multi-value density data into n values (2 ≦ n <256) for each ink color while maintaining the resolution. In this embodiment, 256 values are quantized into 6 values or 16 values using, for example, a multi-value error diffusion method. Further, the recording encoding unit F113 converts the n-valued 600 dpi image data into a command code that can be recognized by the inkjet recording apparatus F102. The encoded density data is transferred to the recording apparatus F102 via the interface F114.

  In the recording device F102, the received image data is temporarily stored in the reception buffer F115, and then the code stored in the reception buffer F115 is analyzed using the code analysis means F116. The analyzed image data is represented by 6 or 16 values of 600 dpi, and the dot arrangement patterning means F117 applies dot arrangement patterning processing to the multi-tone image data. That is, a plurality of types of dot arrangement patterns for recording one pixel (one pixel of 600 dpi) are stored in the ROM B101 according to the density level expressed by six or sixteen levels of density (n gradations). Select from patterns. Thereby, the multi-tone image data of each color is converted into binary recording data that determines whether or not to record dots for each area corresponding to one recording pixel (1200 dpi), and the print buffer F118 for each ink color. Expanded to

  The binary print data developed in the print buffer F118 is further subjected to mask data conversion processing by the mask data conversion means F119, and each nozzle is converted into binary print data that is actually printed in each print scan. The Thereafter, the binary print data is transferred to the print head driver H1001A. The recording head driver H1001A drives the recording elements corresponding to the ink colors on the recording head according to the received recording data. The above is a series of image processing steps executed in the present embodiment.

  In the present embodiment, in order to suppress the density fluctuation even when the recording position shift occurs, a place where a plurality of dots are recorded by overlapping different recording scans in the same area (one pixel of 1200 dpi) of the recording medium. Prepare in advance. Hereinafter, dots that are recorded two by two on the recording medium in this way are referred to as overlapping dots. On the other hand, a dot that is recorded alone without overlapping on the recording medium is referred to as a single dot.

  12A and 12B are diagrams for explaining the influence of the recording position deviation on the density when all the dots are single dots. The dots shown in black are the first dot group recorded in the first recording scan, and the dots shown in white are the second dot group recorded in the second recording scan different from the first recording scan. To do. When there is no recording position deviation between the two recording scans, the dot arrangement is as shown in FIG. 12A, and the first dot group and the second dot group are in the single dot state, and in the sub-scanning direction. Are arranged so as to complement each other. However, when a recording position shift in the sub-scanning direction occurs between two recording scans, the second dot group shifts in the sub-scanning direction with respect to the first dot group, and the complementary relationship of dots is lost. As a result, when the number of single dots decreases and the number of overlapping dots increases, there are places where the recording medium is not covered with dots as shown in FIG. 12B, and the density is lower than in the case of FIG.

  On the other hand, FIGS. 13A and 13B are diagrams for explaining the influence of the recording position deviation on the density when all the dots are overlapping dots. White dots recorded in the second recording scan are recorded in duplicate in all of the first dot group (black dots) recorded in the first recording scan. When there is no recording position deviation between the two recording scans, the dot arrangement is as shown in FIG. 13A, and the first dot group and the second dot group are uniformly arranged in the overlapping dot state. To do. However, when a recording position shift in the sub-scanning direction occurs between two recording scans, the second dot group shifts in the sub-scanning direction with respect to the first dot group, and the two overlapping dots are mutually connected. To separate. As a result, as shown in FIG. 13B, the area of the recording medium covered with dots increases, and the density increases as compared with the case of FIG.

  As described above, the density fluctuation due to the occurrence of the recording position shift is caused by the change in the coverage area of the recording medium between the case where the recording position is shifted and the case where the recording position is not shifted during the plurality of scans. This covering area is affected by the number and ratio of single dots and overlapping dots in the unit region. Therefore, even if the recording position deviation occurs, if the coverage area equivalent to the case where the recording position deviation does not occur, that is, the number and ratio of single dots and overlapping dots in the unit area can be maintained, the density accompanying the recording position deviation Variation can be suppressed. In this embodiment, in order to realize such recording, the above-described dot arrangement patterning process and mask data conversion process are used.

  FIG. 8 is a schematic diagram for explaining an example of the dot arrangement pattern referred to by the dot arrangement pattern setting unit F119 in the first recording mode of the present embodiment. The left side of the drawing shows 0 to 5 level values input from the code analysis means F116, and the right side shows four types of dot arrangement patterns prepared for each level. Each dot arrangement pattern is composed of 4 columns × 2 rasters on the data, black indicates that dots are recorded (1) in the corresponding area of the recording medium, and white indicates that dots are not recorded (0). Show. It can be seen that the dot recording area (black) increases as the level value increases.

  The four dot arrangement patterns prepared for each level are used in place of the main scanning direction and the sub-scanning direction, and consideration is given to avoid biasing to one pattern even when the same level value continues. Such a plurality of dot arrangement patterns are stored in advance in the ROM B101 of the recording apparatus. The binary image data obtained by the dot arrangement pattern setting unit F117 is then classified into odd column data and even column data.

  FIG. 7 schematically illustrates handling of odd column data and even column data in the first recording mode. Here, a case where level 3 4-bit data 601 is input to the dot arrangement pattern setting unit F117 is shown as an example. The level 3 4-bit data 601 is converted into a dot arrangement pattern 602 having an area of 4 columns × 2 rasters by referring to the dot arrangement pattern shown in FIG.

  Here, the dot arrangement pattern 602 includes odd column data 603 composed of odd columns (first column and third column) and even column data 604 composed of even columns (second column and fourth column). being classified. The odd column data 603 and the even column data 604 are recorded by different recording scans. That is, the dot arrangement pattern setting unit F117 converts the multi-value gradation data into two types (N1 types) of dot arrangement patterns for printing with different scans. Further, the odd column data 603 is distributed to image data corresponding to two (M1) printing scans of the first pass and the third pass for the unit area. On the other hand, the even column data 604 is distributed to image data corresponding to two (M1) printing scans of the second pass and the fourth pass for the unit area. Distribution of such odd-numbered column data and even-numbered column data to each print scan is performed by the mask data conversion means F119. That is, the dot arrangement pattern setting unit F117 and the mask data conversion unit F119 distribute multi-tone image data to four (N1 × M1) printing scans.

  FIG. 9 is a diagram for explaining a relationship between a nozzle row 1000 of a certain color and a mask pattern 1001 corresponding to the nozzle row. Here, for the sake of simplicity, a nozzle array 1000 having 64 nozzles will be described as an example. The mask pattern 1001 has an area in the sub-scanning direction corresponding to the number of nozzles 64 and an area in the main scanning direction (32 areas here) of a predetermined amount, and each area allows dot recording (1) or allowance. No (0) is predetermined. Such a mask pattern may be used in common for a plurality of nozzle rows provided in the recording head, but a plurality of mask patterns may be prepared corresponding to each nozzle row.

  In the case of 4-pass multi-pass printing as in the present embodiment, 64 nozzles can be divided into 16 four nozzle groups (first to fourth nozzle groups). The recording medium is transported in the sub-scanning direction by a distance (16 nozzles) corresponding to one nozzle group every recording scan. Thus, the area of the recording medium corresponding to the width of each nozzle group (16 nozzle width) is referred to as a unit area. In each unit region, dots are recorded by four recording scans from the first-pass recording scan by the first nozzle group to the fourth-pass recording scan by the fourth nozzle group.

  A mask pattern corresponding to each nozzle group is assigned to each nozzle group. Hereinafter, a mask pattern that is addressed to the first nozzle group and is used in the first recording scan (first pass) for the unit area is referred to as a first pass mask pattern. Similarly, the second pass mask pattern used in the second print scan (second pass), the third pass mask pattern used in the third print scan (third pass), and the fourth print scan (4 The fourth pass mask pattern used in the (pass) is determined as shown in the figure. Here, the first-pass mask pattern and the third-pass mask pattern are complementary to each other. The second-pass mask pattern and the fourth-pass mask pattern are complementary to each other.

  Each of the odd-numbered column data and the even-numbered column data described with reference to FIG. 7 is ANDed with such a mask pattern, and the image data is recorded (1) and the mask pattern allows recording (1) area. Only a dot is recorded (1), and a recording scan is executed. By performing such logical product processing and recording scanning alternately for odd-numbered column data and even-numbered column data, binary image data output from the dot arrangement pattern setting means F117 is expressed on a recording medium. Is done.

  In this case, for example, even column data is recorded by the second pass and the fourth pass in the unit area where the odd column data is recorded by the first pass and the third pass. Further, odd column data is recorded by the second pass and the fourth pass in the unit area where the even column data is recorded by the first pass and the third pass.

  In this embodiment, the odd-numbered column data and the even-numbered column data of the dot arrangement pattern are recorded by different recording scans, and the dots corresponding to the respective column data are overlapped on the recording medium. Specifically, the recording operation is performed so that the data in the first column and the second column overlap each other, and the data in the third column and the fourth column overlap each other.

  That is, by using the dot arrangement pattern shown in FIG. 8 or by adjusting the position of the recording area in the dot arrangement pattern, overlapping dots and single dots can be mixed in advance at a certain ratio. Therefore, even if a recording position shift occurs, a place where two single dots overlap or a place where overlapping dots are separated can be mixed, so that a large density fluctuation is avoided. Further, by using the mask pattern shown in FIG. 9 or adjusting the position of the print allowable area in the mask pattern, the timing (pass) for recording individual dots on the print medium can be controlled.

  As already described with reference to FIG. 2, when a recording position shift has occurred, the degree of density fluctuation differs depending on the unit area. In the case of the 4-pass multi-pass printing described with reference to FIG. 2, the unit area B where the printing position shift occurs between the second pass and the third pass has the largest density reduction. Accordingly, in this unit area B, if two dots forming overlapping dots are recorded in two passes between the second pass and the third pass (between the central passes) as much as possible, the density decreases. Can be suppressed. Specifically, if the overlapping dot in the unit area B is recorded in a duplicated manner by the combination of either the first pass or the second pass and either the third pass or the fourth pass, it is high. good. In this way, no matter what timing the conveyance deviation occurs, this conveyance operation is performed between the second pass and the third pass (having the interval between the central passes) in the unit area where the density reduction is most concerned. It is possible to alleviate the decrease in concentration.

  However, when a general mask pattern created by the conventional method is used, such an effect cannot be obtained.

  FIGS. 10A and 10B are diagrams showing the ratio of combinations of print scans (passes) in which overlapping dots are printed in a mask pattern created by the conventional method. In general, the first pass and the third pass having a complementary relationship have a recording allowance of 50%. On the other hand, it is possible to record dots in the second pass and the fourth pass in an overlapping manner in the area where recording is permitted in the first pass. In the conventional mask pattern, these also have a print permitting area at a ratio of half each other. Is provided. As a result, the area where recording is allowed in the first pass and the second pass is 25% (701), and similarly, the area where recording is allowed in the first pass and the fourth pass is also 25% (702). It becomes. Considering in this way, the ratio of the print allowable area in each pass combination is 25% as shown in FIG.

  FIG. 10B is a diagram showing a ratio of overlapping dots recorded with a transport operation performed between each pass, based on the ratio of FIG. For example, the ratio at which overlapping dots are recorded across the transport operation between the first pass and the second pass is the ratio of the overlapping dots recorded at the first pass and the second pass, and the first pass and the fourth pass. Since it is the sum of the ratios of overlapping dots to be recorded, 25% + 25% = 50%. In addition, the ratio of overlapping dots recorded between the second pass and the third pass is the ratio of overlapping dots recorded in the first pass and the fourth pass, and the second pass and the third pass. Since this is the sum of the ratios of overlapping dots to be recorded, it is 25% + 25% = 50%. Further, regarding the ratio of overlapping dots recorded across the transport operation between the third pass and the fourth pass, the ratio of overlapping dots recorded in the first pass and the fourth pass, and the third pass and the fourth pass Similarly, 25% + 25% = 50% because it is the sum of the ratios of overlapping dots recorded in the above. As can be seen from the above, in the mask pattern created according to the conventional method, more overlapping dots are recorded between the second pass and the third pass, that is, with the conveyance operation between the central passes. Absent.

  On the other hand, in the present embodiment, the ratio at which overlapping dots are recorded across the transport operation between the second pass and the third pass is the ratio at which overlapping dots are recorded across the transport operation between other passes. A mask pattern set higher than that is prepared.

  23 (a) and 23 (b) show the ratio of the combination of print scans in which overlapping dots of the mask pattern used in this embodiment are printed, and the conventional mask shown in FIGS. 10 (a) and 10 (b). It is a figure for comparing with a pattern and explaining. In this embodiment, the area where recording is allowed in the first pass and the second pass is 12.5% (801) of the whole, and is suppressed to about half compared to the conventional method shown in FIG. Accordingly, the area in which recording is allowed in the first pass and the fourth pass is 37.5% (802) of the total, which is larger than the conventional method. Similarly, the area where recording is allowed in the second pass and the third pass is increased to 35.5%, and the area where recording is allowed in the third pass and the fourth pass is 12.5%. Reduced.

  FIG. 23B is a diagram showing a ratio of overlapping dots recorded with a transport operation performed between the passes, based on the ratio of FIG. According to the figure, the ratio of overlapping dots recorded across the conveying operation between the first pass and the second pass is the ratio of the overlapping dots recorded in the first pass and the second pass, and the first pass and the fourth pass. Since it is the sum of the ratio of overlapping dots recorded in the pass, 12.5% + 37.5% = 50%. In addition, the ratio of overlapping dots recorded between the second pass and the third pass is the ratio of overlapping dots recorded in the first pass and the fourth pass, and the second pass and the third pass. Since it is the sum of the ratios of the overlapping dots to be recorded, 37.5% + 37.5% = 75%. Furthermore, the ratio at which overlapping dots are recorded across the transport operation between the third pass and the fourth pass is the ratio of overlapping dots recorded at the first pass and the fourth pass, and the third pass and the fourth pass. Since this is the sum of the ratios of the overlapping dots to be recorded, 37.5% + 12.5% = 50% is similarly obtained.

  FIG. 11 is a diagram in which the ratio of overlapping dots recorded between each pass is compared between the mask pattern used in the present embodiment shown in FIG. 23 and the conventional mask pattern described in FIG. is there. The broken line indicates the conventional mask pattern, and as shown in FIG. 10B, the ratio of the overlapping dots recorded across any pass is equally 50%. On the other hand, the solid line indicates the mask pattern used in this embodiment, and as shown in FIG. 23B, the ratio of overlapping dots recorded between the second pass and the third pass is 75%. The ratio of overlapping dots recorded across other passes is 50%.

  Note that the mask pattern as in the present embodiment is created by, for example, repeatedly performing the work of replacing the recording allowable area and the non-recording allowable area of the mask pattern generated by the conventional method until the above ratio is realized. I can do it. In addition, it is possible to create a mask pattern according to a conventional mask pattern creation method after the above-mentioned ratio is realized.

  Regardless of which method is used, if a mask pattern as shown by the solid line in FIG. 11 is used, the density decreases in the unit area where the transport deviation occurs in the transport operation between the second pass and the third pass. Can be expected to ease. That is, by performing 4-pass multi-pass printing using the dot arrangement pattern shown in FIG. 8 and the above-described mask pattern, even if a sudden print position shift occurs, the density variation is kept low. It is possible to acquire a simple image.

  As described above, the method of increasing the number of overlapping dots recorded across the central pass by preparing a characteristic mask pattern is particularly suitable for multipass printing with as few as four passes among multipass printing. The effect appears. On the other hand, when the number of multi-passes is large, the ratio of overlapping dots recorded between the central passes tends to increase even with the conventional mask pattern.

  FIG. 16 is a diagram showing the handling of odd-numbered column data and even-numbered column data when performing 8-pass multi-pass printing in comparison with FIG. In the case of 8-pass printing, the odd column data 603 is distributed to image data corresponding to the first pass, the third pass, the fifth pass, and the seventh pass for the unit area. On the other hand, the even column data 604 is distributed to image data corresponding to the second pass, the fourth pass, the sixth pass, and the eighth pass with respect to the unit area.

  FIGS. 17A and 17B are diagrams for explaining the ratio of the combination of printing scans (passes) in which overlapping dots are recorded in the 8-pass mask pattern created by the conventional method, in comparison with FIG. It is. The first pass, the third pass, the fifth pass, and the seventh pass, which are in a complementary relationship, have a recording allowance of 25%. On the other hand, it is possible to record dots in the second pass, the fourth pass, the sixth pass, and the eighth pass in an area where printing is allowed in the first pass, and these are also equal in the conventional mask pattern. The recording allowable area is provided at a rate of 25%. As a result, the area where recording is allowed in the first pass and the second pass is 6.25% (1701) of the whole, and the area where recording is allowed in the first pass and the fourth pass is also 6.25% ( 1702). Furthermore, the area where recording is allowed in the first pass and the sixth pass and the area where recording is allowed in the first pass and the eighth pass are all 6.25% (1703 and 1704).

  FIG. 17B is a diagram showing a ratio of overlapping dots recorded with a transport operation performed between the passes, based on the ratio of FIG. For example, the ratio at which overlapping dots are recorded across the transport operation between the first pass and the second pass is the first pass and the second pass, the first pass and the fourth pass, the first pass and the sixth pass, and Since it is the sum of the ratio of overlapping dots recorded in the first pass and the eighth pass, 6.25% × 4 = 25%. Also, the ratio of overlapping dots recorded between the second pass and the third pass is the first pass and the fourth pass, the first pass and the sixth pass, the first pass and the eighth pass, and the second pass. And the third pass, the second pass, the fifth pass, the second pass, and the seventh pass ratio, 6.25% × 6 = 37.5%. When the ratio of overlapping dots recorded between passes is calculated in this way, the result is as shown in FIG. According to the figure, in 8-pass multi-pass printing, the ratio of overlapping dots (50%) sandwiching between the fourth pass and the fifth pass (between the central passes) even with a mask pattern created according to the conventional method. However, it can be seen that it is higher than between other passes.

  FIG. 18 is a diagram comparing the ratio of overlapping dots recorded between each pass with three conventional mask patterns with different numbers of multi-passes. Here, the cases of 4 passes, 8 passes, and 16 passes are calculated by the method described with reference to FIG. 10, and are shown in the same manner as FIG. However, since the number of multipaths is different from each other on the horizontal axis, the width is adjusted and displayed so that the distance between the central paths is “0.5”. As shown in the figure, in the case of 4 passes, the rate at which overlapping dots are recorded in any pass is constant, but as the number of multi-passes increases, such as 8 passes and 16 passes, The rate at which overlapping dots are recorded is greater than during other passes. Therefore, in the case of a larger number of multipaths, the mask pattern created by the conventional method can sufficiently fulfill its role without preparing a mask pattern as shown by the solid line in FIG. . Rather, if a mask pattern is created with the condition “ratio of overlapping dots recorded between the central passes” as a condition, the effect of the mask pattern on other purposes (for example, the effect on high dispersion) is impaired. There is also the danger of causing Therefore, in this embodiment, only when performing 4-pass multi-pass printing, the dot arrangement pattern setting process is performed using the dot arrangement pattern (first dot arrangement pattern) shown in FIG. 8, and is shown in FIG. Mask data conversion processing is performed using the mask pattern. Hereinafter, such a recording mode is referred to as a first recording mode.

  By the way, the mask pattern having the characteristics shown in FIG. 23 is effective at a gradation higher than the level where overlapping dots are generated, that is, at a halftone of level 2 or higher shown in FIG. In the highlight area of level 1 or lower, since the overlapping dots themselves are not included, it is difficult to suppress the decrease in density by using the recording position shift. However, even in the highlight area, when the dispersibility between dots is lost due to the recording position shift, and the dots that are separated from each other become adjacent, a partially overlapping area occurs, and the density is lowered to some extent. Is invited. In this case, even in the highlight area, the emphasis is not only on the dispersibility of the dots, but in places where two dots recorded by different recording scans are recorded adjacent to each other. It is effective to provide it. In this way, even if the recording position shift occurs, a part where the distanced dots partially overlap is also generated, but a part where the partly overlapping dots are separated also occurs. This is because it can be kept within a predetermined range.

  However, in the configuration in which the four types of dot arrangement patterns consisting of 4 columns × 2 areas shown in FIG. 8 are arranged in order, in the highlight area of level 1 or lower, the dots are recorded adjacently in a wide range. Difficult to do.

  Therefore, in the present embodiment, a second dot arrangement pattern for dealing with such a problem is prepared separately from the first dot arrangement pattern shown in FIG.

  FIG. 14 is a diagram for specifically explaining the handling of data in the dot arrangement pattern setting process when the second dot arrangement pattern is used. However, the dot arrangement pattern itself is not the characteristic second dot arrangement pattern of the present embodiment, and FIG. 14 will first describe an example of a dot arrangement pattern that is easily affected by a recording position shift.

  The second dot arrangement pattern 100 corresponding to one pixel of 600 dpi is composed of 8 columns × 2 rasters as shown in the figure. Here, for each area determined by the column and raster, a convenient name is given by a combination of numbers and alphabets. The second dot arrangement pattern 100 converts 600 dpi 17-value gradation data into 1200 dpi binary print data. FIG. 14 shows an example of a dot arrangement pattern 100 for level 4 image data of level 0 to level 16, black dots indicate that dots are recorded (1) in the corresponding area, and blanks indicate dots. Indicates that the area (0) is not recorded.

  The first dot arrangement pattern is classified into two (N1 types) of even-numbered raster data and odd-numbered raster data, but the binary data corresponding to each area of the second dot arrangement pattern 100 includes four areas A to D. Classify into types (N2 types). And these are overlapped and recorded on the recording medium by different recording scans. If the binary data A to D are recorded by the same recording scan, four-pass multi-pass recording is performed. In the present embodiment, each of the four groups is further divided into two (M2) recording scans. Multi-pass printing is performed for a total of 8 passes (N2 × M2 times). More specifically, the data 1A, 1B, 1C and 1D in the column represented by 4n + 1 are classified as recording data 101, and are recorded in two recording scans by 50% mask patterns which are complementary to each other. The Data 2A, 2B, 2C, and 2D of the column represented by 4n + 2 are classified as print data 102, and are recorded in two print scans by 50% mask patterns that are complementary to each other. Column data 3A, 3B, 3C, and 3D represented by 4n + 3 are classified as recording data 103, and are recorded in two recording scans by 50% mask patterns that are complementary to each other. Further, the data 1A, 1B, 1C and 1D of the column represented by 4n (+4) are classified as recording data 104, and are recorded in two recording scans by 50% mask patterns which are complementary to each other. The

  In the classified recording data of 101 to 104, dots are recorded in the arrangement shown in the figure in a state of overlapping each other. That is, 1A, 2A, 3A, and 4A data are overlapped and recorded at the upper left position of the 2 × 2 area on the recording medium. In this example, one dot by 4A is recorded at the upper left position. In addition, a dot by 1B is recorded at the upper right position, a dot by 2C is recorded at the lower left position, and a dot by 3D is further recorded at the lower right position, and the recording state on the recording medium is 105.

  Here, the case where the input data to the dot arrangement pattern setting unit F117 is level 4 is described as an example. However, in the case of a larger level, at least one of the 2 × 2 areas includes two or more. The dot is recorded in duplicate. In the case of the highest level, four dots are overlapped and recorded in all areas.

  Here, when there is no deviation in the transport operation performed during the eight passes and the dots are recorded at the target positions in all passes, the relative positional relationship of the four dots is 105 Become. However, for example, if a deviation occurs in one transport operation and the dots 3D and 4A are shifted from the dots 1B and 2C, the relative positional relationship between these four dots becomes 106.

  Comparing 105 and 106, in 106, since the 4A and 2C dots partially overlap, the area covered with the recording medium is reduced, and the blank portion is conspicuous. That is, the dot arrangement state such as 106 is detected to have a lower density than the dot arrangement state 105.

  On the other hand, FIG. 15 is a diagram for explaining another example of a dot arrangement pattern that is easily affected by a recording position shift, as compared with FIG. Here, the dot arrangement pattern for the same level 4 is shown, but in the dot arrangement pattern 200 of this example, the area where the dots are actually arranged is different from the comparative example described in FIG. In the case of this example, when the four recording data 201, 202, 203 and 204 are recorded in an overlapping state, the dot arrangement state on the recording medium becomes 205. That is, the upper left position of the 2 × 2 area is recorded with two dots 1A and 4A superimposed, the lower right position is recorded with two dots 2D and 3D, and the lower left and upper right positions are recorded. No single dot is recorded.

  When a recording position shift similar to that in the comparative example described with reference to FIG. 14 occurs in such a dot arrangement state, the relative positional relationship between the four dots becomes 206. That is, the 1A dot and the 4A dot that are recorded in duplicate are separated from each other, and the 2D dot and the 3D dot that are also recorded in duplicate are separated from each other. As a result, the coverage area on the recording medium is increased as compared with the state 205 in which no recording position deviation occurs, and the density is detected to be high.

  That is, in a state where all dots are recorded without overlapping each other as shown in FIG. 14, the density decreases when a recording position shift occurs, and all dots are recorded overlapping each other as shown in FIG. In this state, the density tends to increase when the recording position shift occurs. In view of such a situation, the present inventors have reached the following findings. In other words, in order to prevent a decrease in density and an increase even if a recording position shift occurs, the number of dots that are overlapped at the same position or adjacently and partially overlapped is adjusted to an appropriate amount in advance. It was judged that it was effective to prepare the dot arrangement pattern.

  In particular, in the highlight area, as described above, it is necessary to provide in advance a wide range of locations where two dots recorded by different recording scans are adjacently recorded. Therefore, in the present embodiment, a dot arrangement pattern in a wider range than 8 columns × 2 rasters is prepared as the second dot arrangement pattern.

  FIG. 24 is a diagram showing level 1 in the second dot arrangement pattern. A region surrounded by a thick line corresponds to one pixel region of 600 dpi, and each square in the region represents the region of 8 columns × 2 rasters shown in FIGS. As described above, the second dot arrangement pattern of the present embodiment has an area of 16 pixels (600 dpi) in which 16 areas of 8 columns × 2 rasters are further arranged in parallel four by four.

  FIG. 25 is a diagram showing a print data arrangement state when the print data is duplicated according to the dot arrangement pattern shown in FIG. The 16 areas of 8 columns × 2 rasters shown in FIG. 24 are classified into four print data according to the configuration described with reference to FIGS. 14 and 15, and are recorded on the print medium by different print scans. As a result, in the area of 8 areas × 8 areas, as shown in FIG. 25, the areas determined to be recorded are dispersed while adjoining in the horizontal or oblique directions, and in the recording medium, as shown in FIG. The dots positioned in the same manner are recorded partially overlapping each other. The second dot arrangement pattern in the present embodiment is created so that there are places where two dots recorded by different recording scans are recorded adjacent to each other.

  The level 1 focusing on the highlight area has been described above, but the same effect can be realized even at a level higher than this. In other words, by preparing a dot arrangement pattern that has a somewhat wide area so that a predetermined number of dots to be recorded at adjacent positions in different recording scans are prepared, density fluctuations can be suppressed even if a recording position shift occurs. Is possible. For a halftone level at which overlapping dots are generated, it is possible to prepare a dot arrangement pattern in which overlapping dots are recorded as much as possible between the central passes as in the above-described four-pass recording. That is, a dot arrangement pattern for controlling dot arrangement in a somewhat wide area, such as the second dot arrangement pattern, is prepared, and all forms can be recorded in a multipass of four or more passes by four or more data groups. It is possible to suppress density fluctuation at the gradation level.

  Further, in this case, since the number of multi-passes is set high in advance by the dot arrangement pattern, as described with reference to FIG. Concentration fluctuations associated with can be kept low. Specifically, since the mask pattern is used to further distribute the data already divided into 4 passes according to the dot arrangement pattern into 8 passes, the recording allowance as shown by the broken lines in FIGS. 10 and 11 is 50. % Of a conventional mask pattern. Even in such a mask pattern, if the number of multi-passes is large, the ratio of overlapping dots recorded between the central passes is as follows. It is because it becomes higher than the ratio recorded.

  Therefore, in the present embodiment, when performing multi-pass printing of 8 passes or more, the dot arrangement pattern setting process is performed using the second dot arrangement pattern described above, and a highly dispersive mask created by the conventional method. Mask data conversion processing is performed using the pattern. Hereinafter, such a recording mode is referred to as a second recording mode.

  FIG. 19 is a flowchart for explaining a process in which the host apparatus F101 and the recording apparatus F102 according to this embodiment switch between the two recording methods according to the recording mode. When causing the recording apparatus F102 to execute a recording operation, the user sets a recording medium, an image type, a desired image quality, and the like via a printer driver, and inputs a recording start command to the host apparatus. When receiving the recording command, the host device analyzes the content and sets the recording mode (step S1).

  In step S2, the host device checks the number of multi-passes in the set recording mode, and if it is 4-pass multi-pass, it proceeds to step S3, and if it is multi-pass of 8 or more, it proceeds to step S4.

  In step S3, a recording operation is executed according to the first recording mode. Specifically, referring to FIG. 6, the n-value conversion processing unit F112 converts multi-value density data into six values, the dot arrangement pattern setting unit F117 uses the first dot arrangement pattern, and mask data. The conversion means F119 uses the first mask pattern shown in FIG. Then, according to the obtained recording data, 4-pass multi-pass recording is executed.

  On the other hand, in step S4, the recording operation is executed according to the second recording mode. Specifically, the n-value conversion processing unit F112 converts multi-value density data into 16 values, the dot arrangement pattern setting unit F117 uses the second dot arrangement pattern, and the mask data conversion unit F119 A general second mask pattern is used. Then, 8-pass multi-pass printing is executed according to the obtained print data. This process is completed.

  As described above, in the present embodiment, a characteristic dot arrangement pattern and a mask pattern are prepared so that the coverage area with respect to the recording medium is maintained within a predetermined range even if a recording position shift occurs. Then, by making the dot arrangement pattern and the mask pattern different according to the number of multi-passes, it is possible to stably output an image that is hardly affected by the recording position shift regardless of the recording mode. .

(Second Embodiment)
Also in this embodiment, the recording system including the recording apparatus and the host apparatus shown in FIGS. 3 to 6 is used as in the first embodiment. However, the recording head used in the present embodiment is provided with two rows of nozzle rows for ejecting 5 pl of ink and the nozzle rows for ejecting 2 pl of ink that are the same color in parallel in the main scanning direction. And In this embodiment, the multi-value data is converted into 4-bit 9-value data by the n-value conversion processing means, and dot arrangement patterns for levels 0 to 8 are prepared for 5 pl and 2 pl, respectively. It shall be.

  FIG. 21 is a schematic diagram for explaining an example of a dot arrangement pattern referred to by the dot arrangement pattern setting unit F119 of the present embodiment. Here, for simplicity, dot arrangement patterns corresponding to level 0 to level 4 are shown. The left side of the figure shows 0 to 4 level values input from the code analysis means F116, and the right side shows two types of dot arrangement patterns prepared for each level for 5pl and 2pl. . Each dot arrangement pattern is composed of 2 columns × 2 rasters on the data, black indicates that dots are recorded (1) in the corresponding area of the recording medium, and white indicates that dots are not recorded (0). Show. It can be seen that the dot recording area (black) increases as the level value increases.

  The two dot arrangement patterns prepared for the individual ejection amounts and the individual levels are used instead of in the main scanning direction, and consideration is given to avoid biasing to one pattern even when the same level value continues.

  FIG. 20 schematically illustrates the handling of data in the dot arrangement pattern setting unit F117 of the present embodiment. Here, a state in which 4-bit data 2001 of level 2 is input to the dot arrangement pattern setting unit F117 and converted into binary data 2002 for 5 pl and binary data 2003 for 2 pl is shown. The dot arrangement pattern for 5 pl and the dot arrangement pattern for 2 pl are recorded in an overlapping manner on the recording medium.

  The binary data 2002 for 5 pl is distributed to image data corresponding to two printing scans by the mask data conversion means F119. On the other hand, binary data for 2 pl is also distributed to image data corresponding to two print scans. In the configuration in which the 5 pl nozzle array and the 2 pl nozzle array are arranged in parallel in the main scanning direction as in the present embodiment, the recording for ejecting 5 pl ink and the recording for ejecting 2 pl ink for the unit area are the same. It can be executed by recording scan. That is, in the case of this example, the recording of the binary data 2002 for 5 pl and the binary data for 2 pl are completed by two-pass multi-pass recording.

  By adopting such a configuration, it is possible to overlap the 5 pl dots and the 2 pl dots or to record them independently even if they are at the same level by devising various dot arrangement patterns. Further, by devising the distribution of the mask pattern recording allowable area, it is possible to control the number of areas in which printing is allowed by dividing the 5 pl dots and the 2 pl dots into the first pass and the second pass. . For example, if the mask pattern for 5 pl of the first pass and the mask pattern for 2 pl of the second pass are completely complementary, all overlapping dots are divided into the first pass and the second pass, that is, the central pass It is possible to create a state that is recorded with a gap. That is, according to the configuration of the present embodiment, it is possible to prevent density fluctuations from being caused even if a recording position shift occurs.

  In the present embodiment, as described above, recording using the dot arrangement pattern shown in FIG. 21 and performing two-pass multipass printing using a mask pattern in which the recording timing (pass) of overlapping dots by 5 pl and 2 pl is controlled. The mode is referred to as a first recording mode. On the other hand, while using the dot arrangement pattern shown in FIG. 21, a recording mode in which multi-pass printing using a conventional mask pattern in which overlapping dot recording timing (pass) is not particularly controlled is referred to as a second recording mode.

  FIG. 22 is a flowchart for explaining a process in which the host apparatus F101 and the recording apparatus F102 of the present embodiment switch between the two recording methods according to the recording mode. When causing the recording apparatus F102 to execute a recording operation, the user sets a recording medium, an image type, a desired image quality, and the like via a printer driver, and inputs a recording start command to the host apparatus. Is received (step S21).

  In step S22, the host device checks the information set in step S21. If the recording medium is a high-quality medium such as glossy special paper and high-speed recording is set, the process proceeds to step S23. On the other hand, if the type of the recording medium is a high-quality medium and high-quality recording is set, and if the type of the recording medium is a low-quality medium such as plain paper, the process proceeds to step S24.

  In step S23, the recording operation is executed according to the first recording mode. That is, using the dot arrangement pattern shown in FIG. 21, 2-pass multi-pass printing is performed using a mask pattern in which the recording timing (pass) of overlapping dots by 5 pl and 2 pl is controlled.

  On the other hand, in step S4, the recording operation is executed according to the second recording mode. That is, using the dot arrangement pattern shown in FIG. 21, general multi-pass printing is performed using a conventional mask pattern in which the printing timing (pass) of overlapping dots is not particularly controlled. This process is completed.

  As described above, according to the present embodiment, in the configuration including the two nozzle rows that eject 5 pl of ink and the nozzle row that ejects 2 pl of ink, even if a recording position shift occurs, It becomes possible to maintain the covering area within a predetermined range. Further, it is possible to stably output an image that is hardly affected by the recording position shift regardless of the recording mode.

  Note that Patent Document 4 discloses a configuration in which a plurality of dots are arranged in one area (super pixel) in order to express a given gradation, as in the present invention. According to Patent Document 4, a plurality of stages are prepared for each of the dot size, density, and overlapping area, and more precise density expression is achieved by switching these in stages. However, Patent Document 4 does not mention multi-pass printing, and does not pay attention to the recording position shift in the main scanning direction or sub-scanning direction during multi-pass printing. Therefore, when multipass printing is performed using the technique of Patent Document 4, when a recording position shift occurs, the dot arrangement in the superpixel or between the superpixels is greatly collapsed, resulting in density fluctuations. Concerned.

  As described above, according to the present invention, even when a recording position shift occurs between a plurality of recording scans when multi-pass recording is performed, the density variation in the unit area is reliably suppressed to an appropriate amount, and there is no density unevenness. An image can be output. In addition, it is possible to output such a high-quality image in any of various recording modes with different multipass numbers.

100 Second dot arrangement pattern
101-104 Recorded data
105 dot recording status
106 dot recording status
200 Second dot arrangement pattern
201-204 Recorded data
205 dot recording status
206 dot recording status
601 4-bit data
602 dot arrangement pattern
603 Odd column data
604 Even column data
F101 Host device
F102 recording device
F112 n-value processing means
F117 Dot arrangement pattern setting means
F119 Mask data conversion means

Claims (6)

A plurality of recording heads each having a nozzle row in which nozzles for recording dots of the same color on the recording medium are arranged in the first direction are arranged in a second direction intersecting the first direction with respect to the unit area of the recording medium. A recording apparatus for recording an image in the unit area by scanning the image;
The first recording mode for recording an image in the unit area by 2N (N is an integer of 2 or more) times, and the number of scans for recording the unit area is larger than that in the first recording mode. Setting means for setting one recording mode from among a plurality of recording modes including the second recording mode;
Depending on the multi-tone image data representing a tone of the image corresponding to the unit area, the recording or non-recording of information on each dot of the plurality of areas arranged in the direction corresponding to the second direction Decide a predetermined dot arrangement pattern and distribute it to multiple column data so that the data corresponding to each area of the decided dot arrangement pattern is collected as column data to be recorded in different scans every predetermined number of areas Generating means for generating a plurality of types of column data ,
Distributing means for distributing each of the plurality of types of column data to print data corresponding to a plurality of scans using a mask pattern that determines dot print allowance or non-print allowance for the column data ;
In accordance with the recording data, a recording means for recording in a unit area by scanning a plurality of times by the recording head so that the plurality of types of column data are overlapped on a recording medium,
When the first recording mode is set,
The generation means generates odd column data and even column data from the first dot arrangement pattern determined according to the multi-tone image data,
The distribution unit is configured to perform an interval between an N-th scan and an (N + 1) -th scan when the recording unit records the dots corresponding to the odd-numbered column data and the dots corresponding to the even-numbered column data on the recording medium. The odd columns so that the number of overlapping dots that are recorded with overlapping dots on the recording medium across the recording medium is greater than the number of overlapping dots that are recorded across the other successive recording scans. Distributing each of the data and the even-numbered column data to print data corresponding to 2N scans;
When the second recording mode is set,
When the recording unit records the dots corresponding to the plurality of types of column data in an overlapping manner on the recording medium, the generation unit generates a location where two dots recorded by different scans are recorded adjacent to each other. A second dot arrangement pattern composed of a larger number of areas than the first dot arrangement pattern in which the dot arrangement is determined as described above according to the multi-gradation image data,
The distribution means uses the mask pattern having higher dispersibility of print-allowable dots than the mask pattern used in the first print mode, and uses the print data corresponding to the plurality of scans to each of the plurality of column data. A recording device characterized in that the recording device is distributed . The recording head includes a plurality of nozzle rows that record dots of the same color and different sizes,
The generation means generates the plurality of types of column data for printing in different scans corresponding to the plurality of nozzle rows based on the multi-gradation image data,
The distribution unit distributes each of the plurality of types of column data to print data corresponding to a plurality of scans, corresponding to each of the plurality of nozzle rows,
It said recording means in accordance with the recording data corresponding to each of the plurality of nozzle rows, as the plurality of types of column data corresponding to each of the plurality of nozzle rows are duplicated in the recording medium, by the plurality of nozzle rows The recording apparatus according to claim 1, wherein recording is performed in the unit area by scanning a plurality of times. The recording apparatus according to claim 1, wherein the recording medium is transported in the first direction by an amount corresponding to the width of the unit area during each of the plurality of scans .   3. The setting unit sets one recording mode from a plurality of recording modes including a first recording mode and a second recording mode according to a type of the recording medium. The recording device described in 1.   The setting means sets one recording mode from a plurality of recording modes including a first recording mode and a second recording mode according to the quality of an output image. 2. The recording apparatus according to 2. A plurality of recording heads each having a nozzle row in which nozzles for recording dots of the same color on the recording medium are arranged in the first direction are arranged in a second direction intersecting the first direction with respect to the unit area of the recording medium. A recording method for recording an image in the unit area by scanning twice,
The first recording mode for recording an image in the unit area by 2N (N is an integer of 2 or more) times, and the number of scans for recording the unit area is larger than that in the first recording mode. A setting step for setting one recording mode from among a plurality of recording modes including the second recording mode;
Depending on the multi-tone image data representing a tone of the image corresponding to the unit area, the recording or non-recording of information on each dot of the plurality of areas arranged in the direction corresponding to the second direction Decide a predetermined dot arrangement pattern and distribute it to multiple column data so that the data corresponding to each area of the decided dot arrangement pattern is collected as column data to be recorded in different scans every predetermined number of areas A generation step for generating a plurality of types of column data ,
A distribution step of distributing each of the plurality of types of column data to recording data corresponding to a plurality of scans using a mask pattern that determines dot recording allowance or non-recording allowance for the column data ;
A recording step of recording in a unit area by scanning a plurality of times by the recording head so that the plurality of types of column data are overlapped in a recording medium according to the recording data,
When the first recording mode is set,
In the generation step, odd column data and even column data are generated from the first dot arrangement pattern determined according to the multi-tone image data,
In the distribution step, when the dots corresponding to the odd-numbered column data and the dots corresponding to the even-numbered column data are recorded on the recording medium by overlapping in the recording step, the interval between the Nth scan and the N + 1th scan The odd columns so that the number of overlapping dots that are recorded with overlapping dots on the recording medium across the recording medium is greater than the number of overlapping dots that are recorded across the other successive recording scans. Each of the data and the even-numbered column data is distributed to print data corresponding to 2N scans,
When the second recording mode is set,
In the generating step, when the recording unit records dots corresponding to the plurality of types of column data by overlapping them on a recording medium, a place where two dots recorded by different scans are recorded adjacently occurs. A second dot arrangement pattern composed of a larger number of areas than the first dot arrangement pattern in which the dot arrangement is determined as described above is determined according to the multi-tone image data,
In the distribution step, the print data in which each of the plurality of column data corresponds to the plurality of scans using a mask pattern having higher dispersibility of print-allowable dots than the mask pattern used in the first print mode. A recording method characterized in that the recording method is distributed .

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