JP2013256003A - Printing device and printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a difference in density between an OL region and a non-OL region while overlap-printing.SOLUTION: A printing device performs overlap-printing for forming dots by a plurality of scans on raster lines directing in a main scanning direction by controlling a printing head capable of scanning to discharge ink from a nozzle in accordance with movement in the main scanning direction. A mask in which assignment to one of the plurality of scans is defined for each region is acquired. The mask is applied to a bundle of the raster lines to be overlap-printed among respective raster lines included in image data comprising a plurality of pixels, whereby each pixel of the raster line to be overlap-printed is assigned to one of the plurality of scans. The printing head performs overlap-printing according to the assignment. The mask has an area twice or more larger than one pixel constituting the image data as a unit of the region.

Description

  The present invention relates to a printing apparatus and a printing method.

  Repeating scanning in a direction (main scanning direction) perpendicular to the certain direction of the print head having a plurality of nozzles for discharging ink arranged along a certain direction and transporting the print medium in the certain direction Thus, a printer that ejects ink droplets (dots) from each nozzle to print an image on a print medium is known. On the print medium, a plurality of raster lines facing the main scanning direction are arranged in the certain direction to complete one image. In addition, the printer can execute so-called overlap printing (see Patent Document 1) in which one raster line is printed by using different nozzles in a plurality of scans.

Japanese Patent Laid-Open No. 10-278247

In some cases, the overlap printing is performed on a part of the raster lines constituting the image, and in this case, other raster lines that are not overlapped and normally printed are present in the same image. Become. Normal printing means processing for forming all the dots for expressing one raster line on a printing medium by one nozzle in one scan.
Here, in the case of overlap printing, the dots formed adjacent to each other in the raster line direction are basically landed on the print medium by another scan, and thus are formed with a time difference. On the other hand, in the case of normal printing, the adjacent dots land on the print medium continuously in one scan, and thus are formed with almost no time difference (substantially simultaneously).

As described above, when adjacent dots are formed with a time difference, after a dot (first dot) on the printing medium has landed, another dot (second dot) has landed on a pixel position adjacent to the dot. By the time, the first dot is dried and fixed on the print medium. Thereafter, the second dot that has landed so that a part of the second dot is superimposed on the first dot is suppressed to some extent by the diffusion and penetration of the ink into the print medium. Stay on the surface). On the other hand, when adjacent dots are formed with almost no time difference, the first dot and the second dot land on the print medium almost simultaneously, and both diffuse and penetrate into the print medium.
Therefore, the density of the first dots and the second dots observed on the surface of the print medium is formed when the time is longer than when they are formed without a time difference (when normal printing is performed) (when overlapping printing is performed). Tends to be darker. For this reason, the density of the overlap-printed raster line is different from that of the normal-printed raster line, and color unevenness may be seen in the printed image due to the density difference.

  The present invention has been made to solve the above problems, and provides a printing apparatus and a printing method capable of suppressing the occurrence of the density difference as described above and obtaining a higher-quality printing result than before. To do.

  One of the aspects of the present invention is to control a print head capable of performing a scan for ejecting ink from a nozzle in accordance with a movement in the main scanning direction, thereby performing dot scanning by a plurality of scans for a raster line facing the main scanning direction. A mask that defines the allocation to any one of the plurality of scans for each region, and is included in image data composed of a plurality of pixels. By applying the mask to a bundle of raster lines to be overlap-printed among the raster lines, each pixel of the raster line to be overlap-printed is scanned one of the plurality of times. Assigned to one, and causes the print head to execute overlap printing according to the assignment, and the mask constitutes the image data. More than twice the area of one pixel that is a unit of the area.

  According to the present invention, by applying the mask, the pixels of the raster line to be overlap-printed are grouped in a region unit having an area that is at least twice as large as one pixel, and the plurality of scans are performed. Assign to any one. For this reason, when the raster line to be overlap-printed is overlap-printed, a certain number of adjacent dots can be formed by one scan. Therefore, it is possible to alleviate the phenomenon that the density of the overlap printed portion is higher than that of the other portions. The mask may be a rectangle having a length that is at least twice as long as the one pixel in the main scanning direction and the direction orthogonal to the main scanning direction, that is, an area corresponding to at least four pixels may be used as the unit of the region. Good.

  In one aspect of the present invention, the mask may vary the generation ratio of each region associated with different scanning along a direction orthogonal to the main scanning direction. According to this configuration, the ratio of the areas assigned to different scans in the bundle of raster lines to be overlap-printed smoothly transitions along the orthogonal direction. For this reason, the image area formed by the bundle of raster lines to be overlap-printed and the image areas on both sides sandwiching the bundle in the orthogonal direction are smoothly connected with almost no shading between them.

  In one aspect of the present invention, the mask may have irregularity in the generation pattern of each region associated with different scans. According to this configuration, each region assigned to different scans in a bundle of raster lines to be subjected to overlap printing is generated at random, so that shading unevenness in the image region due to the bundle is further suppressed.

  One aspect of the present invention is configured such that when the image data is printed in a band unit including a predetermined number of raster lines, a connection portion between bands is a target of the overlap printing. According to this configuration, even if the positional relationship between the band images on the print medium is shifted due to a conveyance error of the print medium, white streaks due to the shift (the print medium is caused by a gap between the bands). Occurrence of a phenomenon in which part of the surface is exposed in a streak shape can be avoided.

  The technical idea according to the present invention is not realized only in the form of a printing apparatus, but may be embodied by another object (apparatus). In addition, an invention of a method (printing method) including a process corresponding to the characteristics of the printing apparatus according to any one of the above-described aspects, an invention of a program for causing a predetermined hardware (computer) to execute the method, or a recording of the program The invention of the computer-readable recording medium can also be grasped. Further, the printing apparatus may be realized by a single apparatus or a combination of a plurality of apparatuses.

It is a figure which shows a hardware configuration and a software configuration. It is a figure which illustrates the nozzle arrangement in a print head. 6 is a flowchart illustrating print control processing. FIG. 4 is a diagram for explaining an example of a relationship between each pass of a print head and each band. It is a figure for demonstrating a mode that the mask for OL printing is applied to OL area | region. It is a figure which shows an example of the mask for OL printing. It is a figure which shows the other example of the mask for OL printing.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1. FIG. 1 schematically shows a hardware configuration and a software configuration according to the present embodiment. In FIG. 1, a computer 10 as a personal computer (PC) and a printer 50 are shown. The combination of the computer 10 and the printer 50 or the printer 50 corresponds to a printing device or a printing control device. It can also be said that the computer 10 and the printer 50 constitute one printing system 1. In the computer 10, the CPU 11 controls the printer 50 by expanding the program data 21 stored in the hard disk drive (HDD) 20 or the like to the RAM 12 and performing calculations according to the program data 21 under the OS. The printer driver 13 is executed. The printer driver 13 is a program for causing the CPU 11 to execute functions such as an image data acquisition unit 13a, a color conversion processing unit 13b, a halftone (HT) processing unit 13c, and a rasterization processing unit 13d. Each of these functions will be described later.

  A display 30 as a display unit is connected to the computer 10, and a user interface (UI) screen necessary for each process is displayed on the display 30. In addition, the computer 10 appropriately includes an operation unit 40 realized by, for example, a keyboard, a mouse, a touch pad, a touch panel, and the like, and instructions necessary for each process are input by the user via the operation unit 40. A printer 50 is connected to the computer 10. As will be described later, in the computer 10, a print command is generated based on image data representing an image to be printed by the function of the printer driver 13, and the print command is transmitted to the printer 50.

  In the printer 50, the CPU 51 expands the program data 54 stored in the memory such as the ROM 53 into the RAM 52 and performs a calculation according to the program data 54 under the OS, thereby controlling the firmware FW for controlling the device itself. Is executed. The firmware FW can execute printing based on the drive data by interpreting the print command transmitted from the computer 10 and extracting the drive data and sending it to the ASIC 56. The firmware FW acquires image data representing an image to be printed from a memory card mounted on an external connection connector (not shown), an external device (for example, the computer 10), and the like, and is driven based on the acquired image data. Data can also be generated. In this way, even when drive data is generated by the function of the firmware FW, the drive data is sent to the ASIC 56.

  The ASIC 56 acquires drive data, and generates a drive signal for driving the transport mechanism 57, the carriage motor 58, and the print head 62 based on the drive data. The printer 50 includes a carriage 60, and the carriage 60 is loaded with ink cartridges 61 for each of a plurality of types of ink. In the example of FIG. 1, ink cartridges 61 corresponding to various inks of cyan (C), magenta (M), yellow (Y), and black (K) are mounted.

  The specific types and number of inks used by the printer 50 are not limited to those described above. For example, various inks such as light cyan, light magenta, orange, green, gray, light gray, white, metallic ink, etc. It can be used. Further, the ink cartridge 61 may be installed at a predetermined position in the printer 50 without being mounted on the carriage 60. The carriage 60 includes a print head 62 that ejects (discharges) ink supplied from each ink cartridge 61 from a number of nozzles.

  FIG. 2 shows an example of the arrangement of nozzles on the lower surface of the print head 62 (the surface facing the print medium). On the lower surface of the print head 62, a nozzle row KN composed of a plurality of nozzles Nz for ejecting K ink as achromatic ink, a nozzle row CN composed of a plurality of nozzles Nz for ejecting C ink, and M A nozzle row MN composed of a plurality of nozzles Nz for ejecting ink and a nozzle row YN composed of a plurality of nozzles Nz for ejecting Y ink are formed. Each nozzle row KN, CN, MN, YN is composed of the same number of nozzles Nz that are parallel to each other and aligned along a second direction (see FIG. 2) that is substantially orthogonal to the first direction. . The first direction is the main scanning direction of the print head 62, and the second direction is the print medium conveyance direction in the printer 50. The second direction is also called a sub-scanning direction.

  The density (number of nozzles / inch) of the nozzles Nz in each of the nozzle arrays KN, CN, MN, and YN is equal to the printing resolution (dpi) of the printer 50 in the sub-scanning direction. Note that each nozzle row KN, CN, MN, YN is not only composed of one nozzle row arranged in the sub-scanning direction, but is, for example, parallel and shifted by a predetermined pitch in the sub-scanning direction. Alternatively, it may be composed of a plurality of nozzle rows.

In the print head 62, a piezoelectric element for ejecting ink droplets (dots) from the nozzles is provided for each nozzle. The piezoelectric element is deformed when the drive signal is applied, and ejects dots from the corresponding nozzle.
The transport mechanism 57 (FIG. 1) includes a paper feed motor and a paper feed roller (not shown), and is driven and controlled by the ASIC 56 to transport the print medium along the transport direction.

  By controlling the driving of the carriage motor 58 by the ASIC 56, the carriage 60 (and the print head 62) moves along the main scanning direction, and the ASIC 56 moves from each nozzle to the print head 62 at a predetermined timing along with the movement. Ink is ejected. Thereby, dots adhere to the print medium, and the print target image indicated by the print command is reproduced on the print medium. The printer 50 further includes an operation panel 59. The operation panel 59 includes a display unit (for example, a liquid crystal panel), a touch panel formed in the display unit, various buttons and keys, and accepts input from the user and displays a necessary UI screen on the display unit. .

  In the present embodiment, assuming the above-described configuration, processing for printing an image to be printed by the printer 50 will be described below. In the printing, for each scan (also referred to as a pass) of the print head 62 with respect to the print medium, an image of a band (area having a certain width in the sub-scanning direction) constituting the print target image is recorded on the print medium. .

2. Print Control Process FIG. 3 is a flowchart showing the print control process. Here, description will be made assuming that the CPU 11 executes the flowchart by the printer driver 13 (printing control program). Assuming that the flowchart is started, it is assumed that the printer driver 13 accepts selection of an arbitrary print target image by the user via the operation unit 40.

  In step S100, the image data acquisition unit 13a acquires image data representing an image to be printed from a predetermined storage area such as a memory card mounted on the HDD 20 or an external connection connector (not shown). Here, the image data is, for example, RGB data in which each pixel constituting the image has gradation values (for example, 256 gradations from 0 to 255) for each of red (R), green (G), and blue (B). is there. When the image data is a file described in another format such as PDL, the image data acquisition unit 13a analyzes the file and develops it into RGB data. Further, the image data acquisition unit 13a appropriately executes resolution conversion processing for matching the print resolution in the printer 50 with respect to the image data (RGB data).

  In step S110, the color conversion processing unit 13b performs color conversion on the image data acquired by the image data acquisition unit 13a using a color conversion lookup table (LUT) stored in advance in the HDD 20 or the like. The color conversion LUT defines the correspondence between the input color system (RGB color system) and the output color system (ink amount space corresponding to the ink type used by the printer 50) for a plurality of input grid points. . In the case of the present embodiment, in the color conversion LUT, the ink amount (tone value) for each of the C, M, Y, and K inks is defined as an output value associated with each input grid point. At the time of color conversion, interpolation calculation or the like is executed as necessary. As a result, the image data as RGB data is converted into ink amount data (image data) having gradation values (for example, 256 gradations from 0 to 255) for each pixel, C, M, Y, and K. .

  In step S120, the HT processing unit 13c performs a halftone process on the ink amount data, thereby defining a halftone that defines dot recording (ON) or non-recording (OFF) for each ink type and each pixel. Data (image data) is generated. Halftone processing is executed by a known method such as a dither method or an error diffusion method.

  In step S130, the rasterization processing unit 13d rearranges the halftone data in the order in which the halftone data should be transferred to the printer 50 by assigning the information for each ink type and each pixel of the halftone data to each pass and each nozzle of the print head 62. A print command including the drive data is generated (rasterization processing). In other words, according to the rasterizing process, it is determined in which pass and by which nozzle each dot defined in the halftone data is formed in accordance with its pixel position and ink type.

  FIG. 4 is a diagram for explaining the relationship between each pass of the print head 62 and the band in the image data IM recorded on the print medium S by each pass in the present embodiment. FIG. 4 shows a state in which the positions of the print head 62 and the print medium S relatively change for each pass on the left side. Here, a total of four passes from pass 1 to pass 4 are illustrated. doing. FIG. 4 illustrates the positions of the bands (bands 1 to 4) recorded by the passes on the right side. For convenience of explanation, FIG. 4 shows a relative position change between the print head 62 and the print medium S by changing the position of the print head 62 in the opposite direction of the second direction for each pass. Actually, the print head 62 does not move along the first direction, and the print medium S moves in the second direction by conveyance as described above. In FIG. 4, the transport distance of the print medium S that is transported after the band is printed by one pass and before the band is printed by the next pass is indicated by a symbol D.

  In the present embodiment, as shown in FIG. 4, when printing one band (for example, band 2), the front end of the band is behind the band (for example, band 1) that has been printed in the immediately preceding pass (for example, pass 1). Print so that it overlaps the edges. Here, an end portion of the band facing the front side in the transport direction is called a front end, and an end portion facing the rear side of the transport direction is called a rear end. A region where two bands overlap in this way is called an overlap (OL) region. In FIG. 4, the region where band 1 and band 2 overlap is described as OL region 1, the region where band 2 and band 3 overlap is described as OL region 2, and the region where band 3 and band 4 overlap is described as OL region 3. That is, the transport distance D is set to a distance that generates such an OL area.

  Band width Wb (number of raster lines composing one band × length in the transport direction of one dot) and width Wo of OL region (number of raster lines composing one OL region × length in the transport direction of one dot) ) Is also set in advance, and can be expressed as transport distance D = Wb−Wo. A raster line corresponding to the OL area in the image data IM is a target for overlap printing, and a raster line constituting an area (non-OL area) not corresponding to the OL area in the image data IM is a target for normal printing. . As described above, in the present embodiment, the connecting portion between the bands is an OL region, thereby preventing the occurrence of white streaks as described above.

  The process of step S130 will be further described with reference to FIGS. In step S130, the OL printing mask M1 (stored in the HDD 20 or the like in advance) for a bundle of raster lines corresponding to the OL area among the raster lines (pixel rows facing the main scanning direction) constituting the halftone data. Hereinafter, the dot of each pixel is assigned to any one of a plurality of passes for printing the OL region by applying the mask M1. In the present embodiment, since one OL area is completed in two passes (preceding pass and succeeding pass), each pixel in the OL area is placed in either the preceding pass or the succeeding pass for that OL area. Assigned. According to the example of FIG. 4, since the paths for completing the OL area 1 are the path 1 and the path 2, for the OL area 1, the path 1 is the preceding path and the path 2 is the subsequent path. Similarly, for the OL area 2, the path 2 is a preceding path, the path 3 is a succeeding path, the path 3 is a preceding path, and the path 4 is a succeeding path.

  FIG. 5 is a diagram for explaining how the mask M1 is applied to a bundle of raster lines corresponding to the OL area in the rasterizing process. In FIG. 5, as an example, a raster line (one raster line defining ON / OFF of C ink dots for each pixel) in the C ink halftone data among the halftone data for each CMYK ink. ) Is applied with the mask M1. Of course, the application of the mask M1 to the OL area is performed for each halftone data for each ink type.

  6 and 7 each show an example of the mask M1. The mask M1 is a mask having a predetermined number of pixels in each of the vertical direction (direction to match the transport direction) and the horizontal direction (direction to match the main scanning direction), and one of the preceding pass and the subsequent pass for each region in the mask. It stipulates allocation to one side. The “region” in the mask is set in units of an area that is at least twice as large as one pixel constituting the image data. 6 and 7, each cell in the mask M1 indicates a pixel, and a rectangle surrounded by a thick line indicates one “region” in the mask. Here, one “region” has a size of 4 pixels of 2 × 2 in the vertical and horizontal directions. In the mask M1, for each such region, either a value indicating a preceding path (“0” in the examples of FIGS. 6 and 7) or a value indicating a subsequent path (“1” in the examples of FIGS. 6 and 7). One side is stored. Of course, each pixel in the same area stores a common value. In FIGS. 6 and 7, for the sake of easy viewing, the area that defines the assignment to the preceding path is given a gray color, and the area that specifies the assignment to the following path is not given a gray color. .

Note that the mask M1 in FIG. 6 is a mask in which the area to which the preceding path is assigned and the area to which the subsequent path is assigned are alternately generated in the vertical and horizontal directions.
On the other hand, in the mask M1 in FIG. 7, the generation ratio of the area to which the preceding path is assigned and the area to which the succeeding path is assigned is varied along the vertical direction. Specifically, the mask M1 in FIG. 7 has a higher ratio of the area allocated to the preceding path on the front side in the transport direction among both ends in the vertical direction, and a ratio of the area allocated to the subsequent path on the rear side in the transport direction. Higher. In addition, in the mask M1 in FIG. 7, the area to which the preceding path is allocated and the area to which the subsequent path are allocated are randomly generated in the horizontal direction while observing the change in the generation ratio. In the mask M1 in FIG. 7, it is assumed that at least the number of pixels in the vertical direction matches the number of raster lines constituting one OL region.

  In any of these masks M1, the ratio of the area to which the preceding path is assigned and the area to which the succeeding path is assigned is 1: 1 as a whole. In step S130, any of the masks M1 shown in FIGS. 6 and 7 may be used. The generation pattern of each area in the mask M1 may be a pattern other than that shown in FIGS. 6 and 7, for example, the generation of the area assigned the preceding path and the area assigned the subsequent path in the entire mask M1. The position may be irregular. Further, the user may be able to select the mask M1 used for each OL area.

  As a result of applying (superimposing) the mask M1, in the raster line constituting the OL region, as illustrated on the right side of FIG. 5, each pixel is either the preceding pass or the succeeding pass in the area unit of the “region”. Assigned to either. On the right side of FIG. 5, for ease of viewing, the pixels to which the preceding path is assigned are assigned a gray color, and the pixels to which the subsequent path is assigned are not assigned a gray color. On the right side of FIG. 5, a numerical value “1” is assigned to each pixel, but this numerical value “1” means dot ON. That is, FIG. 5 shows an example in which at least C ink halftone data is a solid image. Of course, in the configuration shown on the right side of FIG. 5, a numerical value “0” indicating dot OFF may be assigned to each pixel. It is not a target for ink ejection.

  The print command generated by the rasterization process is output to the printer 50 (step S140). The printer 50 executes printing of the print target image on the print medium based on the transmitted print command. In this case, the printer 50 assigns dots for each ink type to each pass and each nozzle of the print head 62, reproduces a plurality of bands as described above on the print medium, and completes one print target image. Of course, for each dot corresponding to the OL area, ejection is performed in the allocation destination pass by application of the mask M1.

According to this embodiment, the following effects are exhibited.
First, by applying the mask M1 to the OL area, a certain number of adjacent dot groups can be formed in the same pass for each dot corresponding to the OL area. That is, while OL printing is performed for the OL area, adjacent dots (for example, 4 dots of 2 × 2 in length and width) are formed simultaneously or continuously in each of the preceding and succeeding passes constituting the overlapping printing. can do. Therefore, the behavior of ink diffusion and penetration into the print medium for these adjacent dots is the same as that of the dots formed adjacent to each other in normal printing, which is similar to conventional overlap printing. In contrast, it is possible to suppress a phenomenon in which a density difference occurs (color unevenness occurs) as compared with a portion that is normally printed (non-OL region).

  In addition, according to the present embodiment, it is possible to suppress the phenomenon of density variation between the OL region and the non-OL region due to the difference in dot ejection frequency. The discharge frequency mentioned here means the dot discharge frequency per unit time by one nozzle, and the discharge frequency when performing overlap printing is lower than the discharge frequency when performing normal printing. Such a discharge frequency corresponds to the frequency of a pulse waveform appearing in a drive signal supplied to a piezoelectric element provided corresponding to one nozzle in the print head 62 (in other words, the frequency of the drive signal). doing. In the printer 50, there is a design ideal value for the ink amount per dot. However, the difference in dot formation frequency may affect the amount of ink per dot. That is, the amount of ink per dot ejected from the nozzle is desired to be a constant value (ideal value) regardless of the dot formation frequency, but in reality, if the formation frequency is different, the print head 62 The amount of ink per ejected dot is subtle due to various factors (for example, the shape of the ink flow path, the characteristics of the ink itself, and the state of the meniscus formed by the ink at the nozzle tip). Can change. For this reason, in a printing result in which an OL area and a non-OL area coexist, conventionally, variations in density occur between these areas. However, in this embodiment, even in the OL region, a certain number of dots adjacent in the main scanning direction are formed in the same pass (that is, the same nozzle). Therefore, the local ejection frequency at each location in the OL region is close to the ejection frequency in the non-OL region, and as a result, the variation in concentration between the OL region and the non-OL region is alleviated.

  Furthermore, according to this embodiment, the prevention effect of the said white stripe increases. That is, when the adjacent dots are landed on the print medium with almost no time difference and when the respective dots are landed on the print medium with a time difference, the ink diffusion range combining the dots is the former. The case tends to be wider. Therefore, as in the present embodiment, by forming a certain number of adjacent dots in each overlap printing pass, ink can be diffused in a larger range in the OL area, and ink can be used in the OL area. Locations that are not covered can be reduced as much as possible.

  When the mask M1 as shown in FIG. 7 is employed, the ratio of the area allocated to the preceding path and the area allocated to the subsequent path in the OL area smoothly changes along the transport direction. Therefore, the OL area and the non-OL areas on both sides sandwiching the OL area in the transport direction are smoothly connected in a state where there is almost no unevenness in density in the print result. In addition, in the mask M1, by giving irregularity to the generation pattern of the area allocated to the preceding path and the area allocated to the subsequent path, areas allocated to different paths in the OL area are randomly generated. Unevenness or the like in the OL region can be appropriately suppressed while enhancing the muscle prevention effect.

3. Modifications The present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible. Further, the contents of the above-described embodiment and modification examples combined as appropriate are also within the scope of disclosure of the present invention.

The unit of the “region” in the mask M1 is not limited to the size of 2 × 2 4 pixels, and for example, the size of 3 × 2 pixels in length and width, the size of 2 × 3 pixels in length and width, and other sizes, It may be a shape.
Further, as described above, the print target image is printed by a plurality of passes, but these passes may be unidirectional or bidirectional. That is, the print head 62 can move in the forward direction and return direction in the main scanning direction. However, the print head 62 may realize all paths only by the forward direction movement (or only in the backward direction movement). Each path may be realized.

  Although the case where the computer 10 executes the print control process has been described above as an example, the print control process (including each modified example) may be performed in the printer 50. That is, when the CPU 51 of the printer 50 executes the firmware FW (printing control program), the above functions such as the image data acquisition unit 13a, the color conversion processing unit 13b, the HT processing unit 13c, and the rasterization processing unit 13d are performed in the printer 50. And the flowchart of FIG. 3 may be realized. In this case, information necessary for processing such as the mask M1 is stored in the ROM 53 in the printer 50 in advance. Further, the CPU 51 receives various information and instructions necessary for printing, such as an operation of a print execution instruction, from the user via the operation panel 59. As a result, drive data is generated by the function of the firmware FW as described above. Alternatively, the flowchart of FIG. 3 may be realized by sharing the printer driver 13 and the firmware FW.

DESCRIPTION OF SYMBOLS 1 ... Printing system, 10 ... Computer, 11 ... CPU, 12 ... RAM, 13 ... Printer driver, 13a ... Image data acquisition part, 13b ... Color conversion processing part, 13c ... HT processing part, 13d ... Rasterization processing part, 20 ... HDD, 30 ... display, 40 ... operation unit, 50 ... printer, 51 ... CPU, 52 ... RAM, 53 ... ROM, 59 ... operation panel, 61 ... ink cartridge, 62 ... print head, M1 ... OL printing mask

Claims (6)

By controlling a print head capable of executing a scan that ejects ink from the nozzles in accordance with the movement in the main scanning direction, overlap printing is executed in which dots are formed by a plurality of scans on a raster line that faces the main scanning direction. A printing device,
A raster line that is a target of overlap printing among raster lines included in image data that is obtained by obtaining a mask that defines, for each region, allocation to any one of the plurality of scans. By applying the mask to the bundle, each pixel of the raster line that is the target of the overlap printing is assigned to any one of the plurality of scans, and the overlap printing according to the assignment is performed as described above. Let the print head run,
The printing apparatus according to claim 1, wherein the mask has a unit of the area that is at least twice as large as one pixel constituting the image data.   2. The mask according to claim 1, wherein a rectangle having a length that is at least twice as long as the one pixel in the main scanning direction and a direction orthogonal to the main scanning direction is used as the unit of the region. Printing device.   3. The printing apparatus according to claim 1, wherein the mask is configured such that a generation ratio of each region associated with a different scan is varied along a direction orthogonal to the main scanning direction.   The printing apparatus according to claim 1, wherein the mask has irregularity in a generation pattern of each region associated with different scanning.   5. When the image data is printed in a band unit including a predetermined number of raster lines, a connecting portion between bands is a target of the overlap printing. 6. Printing device. By controlling a print head capable of executing a scan that ejects ink from the nozzles in accordance with the movement in the main scanning direction, overlap printing is executed in which dots are formed by a plurality of scans on a raster line that faces the main scanning direction. Printing method,
A raster line that is a target of overlap printing among raster lines included in image data that is obtained by obtaining a mask that defines, for each region, allocation to any one of the plurality of scans. By applying the mask to the bundle, each pixel of the raster line that is the target of the overlap printing is assigned to any one of the plurality of scans, and the overlap printing according to the assignment is performed as described above. Let the print head run,
The printing method according to claim 1, wherein the mask has an area that is at least twice as large as one pixel constituting the image data.