JP2013256008A - Printing device and printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further improve print image quality by improving the coloring of ink discharged to a print medium and preventing bleeding.SOLUTION: A printing device includes: a printing head including an achromatic nozzle line for discharging achromatic ink and a plurality of chromatic nozzle lines for discharging chromatic inks and movable along a first direction; and a transport mechanism for transporting a print medium in a second direction approximately orthogonal to the first direction. The printing head can perform path processing for discharging the ink from the nozzle lines to a common region of the print medium during forward movement and return movement along the first direction respectively. While the path processing takes place an integral multiple of times of the number of the chromatic inks on the common region, the achromatic ink is not discharged from the achromatic nozzle line during at least one path processing, and in addition a ratio of the amount of the achromatic ink discharged during the path processing for discharging the achromatic ink from the achromatic ink nozzle line is made to be different.

Description

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

  2. Description of the Related Art There is known a printer equipped with a print head having nozzle rows that discharge chromatic inks such as cyan, magenta, and yellow and nozzle rows that discharge achromatic ink such as black. In such a printer, a color image is reproduced in the area by scanning (movement accompanied by ink ejection, also referred to as a pass) with respect to a certain area of the print medium by each nozzle row. As a related technique, cyan recording is performed from the color recording head in the first scan, and at the same time, recording is performed for 50% of the total number of dots of data for recording black from the black recording head. In the ink jet recording method, the remaining 50% of magenta and black are recorded in the area where cyan and black are recorded in the first scan, and further yellow is recorded in the area in the third scan. (See Patent Document 1).

Japanese Patent Laid-Open No. 7-237346

  In the printer as described above, when a plurality of colors of ink are ejected onto the print medium during one scan of the print head, the color developed by each ink landed on the print medium is influenced by each other. Specifically, the degree of color development of the chromatic color ink differs depending on the amount of the black ink ejected together, and the degree of the influence of the black ink ejected together varies depending on the chromatic ink. In addition, when the ink is adhered to the ink adhered to the print medium, the realization of a good image quality without blurring may be influenced by whether or not the adhering ink can be dried to some extent. Therefore, appropriately controlling the amount of black ink discharged together with each chromatic color ink has been an important issue in obtaining good printing results.

  The present invention has been made in order to solve the above-described problems, and by achieving improved color development and suppression of bleeding of ink ejected onto a print medium, it is possible to obtain a higher-quality print result than before. A possible printing apparatus and printing method are provided.

  One aspect of the present invention is an achromatic nozzle array composed of a plurality of nozzles for ejecting achromatic ink and a chromatic nozzle array composed of a plurality of nozzles for ejecting chromatic color ink. A print head provided with a plurality of chromatic nozzle rows provided for each chromatic ink and movable in the first direction; a transport mechanism for transporting the print medium in a second direction substantially perpendicular to the first direction; The print head is capable of executing a pass process for ejecting ink from a nozzle row to a common range of the print medium in each of the forward movement and the backward movement along the first direction. And achromatic ink is ejected from the achromatic nozzle row in at least one pass process in the process of executing the pass process for the common range a number of times the integer number of the chromatic inks. Without and varying the ratio of the amount of ink achromatic ink discharged between achromatic ink path to eject the processing from achromatic nozzle array.

  According to the present invention, in the process of executing the pass process by an integer multiple of the number of chromatic color inks with respect to the common range, the discharge of the achromatic ink is stopped in at least one pass process. Therefore, it is possible to appropriately secure the drying time for the achromatic color ink and to suppress the bleeding about the achromatic color ink. In addition, in order to vary the ratio of the discharge amount of the achromatic color ink in the pass processing for discharging the achromatic color ink from the achromatic color nozzle row, for example, the ratio is changed according to the type of the chromatic color ink discharged together with the achromatic color ink. Is possible. As a result, the color development for each chromatic ink can be appropriately controlled. Specifically, the plurality of chromatic color inks are cyan ink, magenta ink, and yellow ink, and the print head executes a pass process for the common range three times in total, and once in the three pass processes. In this pass process, achromatic ink is not ejected from the achromatic nozzle row, and in the other two pass processes, the ratio of the achromatic ink ejection amount is varied.

  One aspect of the present invention is a pass process for ejecting chromatic color ink from a first chromatic color nozzle row that ejects chromatic color ink having the highest luminance among the plurality of chromatic color inks with respect to the common range. The achromatic ink is not ejected from the achromatic nozzle row or the chromatic color ink is ejected from the second chromatic nozzle row that ejects a chromatic ink different from the chromatic ink having the highest luminance. A less amount of achromatic ink is ejected from the achromatic nozzle row than the achromatic ink ejected in other pass processing for ejecting achromatic ink to the common range. High-luminance chromatic ink has a characteristic that color development on a print medium tends to be low due to the influence of the achromatic ink ejected together. According to this configuration, the amount of achromatic ink ejected together with the chromatic ink having the highest luminance is set to 0 or relatively small even if it is not 0. Therefore, it can be avoided that the chromatic color ink having the highest luminance is largely suppressed by the influence of the achromatic color ink ejected together.

  In one aspect of the present invention, the first chromatic nozzle row is configured to eject yellow ink. That is, the chromatic color ink having the highest luminance is yellow ink. When yellow ink is ejected onto a print medium together with achromatic ink, the observed degree of color reduction is greater than that of other chromatic ink. In other words, the yellow ink that has landed on the print medium together with the achromatic color ink tends to be erased by the achromatic color ink. Therefore, according to the said structure, the fall of the coloring degree of yellow ink can be avoided appropriately.

  According to one aspect of the present invention, the print head has a configuration in which the pass process for discharging the achromatic color ink from the achromatic nozzle row to the common range is unified to either the forward movement or the backward movement. is there. When the print head performs bidirectional printing, a positional deviation along the first direction between the image recorded with the forward movement and the image recorded with the backward movement with respect to the common range. Can occur. According to the present invention, since the achromatic ink is ejected by either one of the forward movement and the backward movement, it is difficult to cause such a positional shift, and it is possible to obtain a sharp print result in which blurring is suppressed.

  In one aspect of the present invention, the plurality of chromatic color nozzle rows are arranged in parallel with the achromatic color nozzle row and are shifted in the tangential direction of the rows, and the print head is used once. In the pass processing, ink is supplied from any one of the plurality of chromatic color nozzle rows and the one chromatic color nozzle row to form a part of the achromatic color nozzle row in the common range. It is set as the structure which can discharge. According to this configuration, when the pass processing by a pair of one chromatic nozzle row and the achromatic nozzle group for the common range is performed a plurality of times while changing the pair, achromatic ink bleed suppression and each chromatic color are suppressed. Improves color development of ink, and can obtain high-quality printing results.

  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. It is a figure for demonstrating an example of allocation of the halftone data with respect to each pass and each nozzle. It is a figure which shows an example of the mask for nozzle groups. It is a figure for demonstrating the other example of allocation of the halftone data with respect to each pass and each nozzle. It is a figure for demonstrating the other example of allocation of the halftone data with respect to each pass and each nozzle.

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, an achromatic nozzle row 62a composed of a plurality of nozzles Nz (K nozzles) for discharging K ink as achromatic ink, and a plurality of CMY inks for discharging chromatic ink. A chromatic nozzle row 62b composed of the nozzles Nz is formed. The achromatic color nozzle row 62a and the chromatic color nozzle row 62b are each constituted by a plurality of nozzles Nz that are parallel to each other and aligned along a second direction (see FIG. 2) substantially orthogonal to the first direction. Yes. 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 achromatic nozzle row 62a and the chromatic nozzle row 62b is equal to the printing resolution (dpi) of the printer 50 in the sub-scanning direction. Note that the achromatic color nozzle row 62a and the chromatic color nozzle row 62b are not only composed of one nozzle row aligned along the sub-scanning direction, but are also parallel and have a predetermined pitch in the sub-scanning direction. You may be comprised by the nozzle row | line | column which shifted | deviated. The chromatic color nozzle row 62b further includes a nozzle row (C nozzle row) composed of a plurality of nozzles Nz (C nozzles) for ejecting C ink and a plurality of nozzles Nz (M nozzles) for ejecting M ink. A nozzle row (Y nozzle row) including a plurality of nozzles Nz (Y nozzles) for ejecting Y ink. In other words, the C nozzle row, the M nozzle row, and the Y nozzle row are formed so as to be shifted from each other in the tangential direction thereof, and constitute a chromatic nozzle row 62b as a whole. The C nozzle row, the M nozzle row, and the Y nozzle row each have the same number of nozzles Nz.

  Further, each of the C nozzle row, the M nozzle row, and the Y nozzle row forms a nozzle group G1, G2, and G3 together with a part of the achromatic nozzle row 62a that forms a pair. Here, “pairing” means being in the same range in the sub-scanning direction. Specifically, the C nozzle row and a portion (achromatic nozzle group) which is a part of the achromatic nozzle row 62a and forms a pair with the C nozzle row (achromatic color nozzle group) form the nozzle group G1. Similarly, a part (achromatic nozzle group) which is part of the M nozzle row and the achromatic nozzle row 62a and forms a pair with the M nozzle row (achromatic nozzle group) constitutes the nozzle group G2, and the Y nozzle row and the achromatic nozzle row 62a. A portion (achromatic nozzle group) that forms a part of the Y nozzle row and forms a nozzle group G3. In this embodiment, since Y ink corresponds to the ink having the highest luminance among chromatic color inks (CMY inks), the Y nozzle row corresponds to the first chromatic color nozzle row and the other C nozzle rows. , M nozzle row corresponds to the second chromatic nozzle row.

  In such a print head 62, an area (band) having a certain width in the sub-scanning direction on the print medium can be printed by each of the nozzle groups G1, G2, and G3. That is, by performing printing with each of the nozzle groups G1, G2, and G3 on one band, a color image by CMYK is completed in the one band. The width of one band is equivalent to the length of one nozzle group (length in the sub-scanning direction). One band corresponds to the common range described in the claims.

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 sub-scanning direction. The transport mechanism 57 can transport the width of the band in order to cause each of the nozzle groups G1, G2, and G3 to perform printing on the same band.

  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, a process for bidirectionally printing a print target image by the printer 50 will be described below. In the printing, recording is performed by a number of passes that is an integral multiple of the number of chromatic color inks (including 1) for each band that constitutes an image to be printed. One pass (pass process) means a process in which the print head 62 ejects dots in accordance with either one forward movement or one backward movement in the main scanning direction. In bidirectional printing, the odd-numbered (or even-numbered) path is realized by the forward movement, and the even-numbered (or odd-numbered) path is realized by the backward movement. It should be noted that the selection of a printing method such as unidirectional printing (printing performed only in one of the forward movement and backward movement of the print head 62) or bidirectional printing is set in advance in accordance with a user operation or the like. Shall.

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 RGB data in which each pixel constituting the image has gradation values (for example, 256 gradations of 0 to 255) for each of red (R), green (G), and blue (B). And 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 RGB data with the print resolution in the printer 50.

  In step S110, the color conversion processing unit 13b converts the RGB 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 RGB data is converted into ink amount data having gradation values (for example, 256 gradations from 0 to 255) for each pixel in C, M, Y, and K.

  In step S120, the HT processing unit 13c performs halftone processing on the ink amount data, thereby defining halftone data that defines dot recording (ON) or non-recording (OFF) for each ink type and for each pixel. 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. In step S130, among the halftone data for each ink type, for the K ink halftone data, nozzle group masks M1, M2, M3... (Hereinafter referred to as masks M1, M2) stored in the HDD 20 or the like in advance. , M3...) To assign (distribute) the recording timing of each dot to a plurality of passes.

  FIG. 4 is a diagram for explaining an example of the above assignment of halftone data for each pass and each nozzle of the print head 62. FIG. 4 shows a state in which the position of the print head 62 changes relative to the print medium for each pass on the left side. Here, a total of six passes from pass 1 to pass 6 are illustrated. Yes. Further, in FIG. 4, a portion (C nozzle row) marked with “C” in the chromatic nozzle row 62 b and an achromatic nozzle row 62 a marked with “K” paired with the “C” portion. The part corresponds to the nozzle group G1. Similarly, the “M” portion (M nozzle row) of the chromatic color nozzle row 62b and a part of the achromatic nozzle row 62a paired with the “M” portion and marked “K” are a nozzle group. A portion of the achromatic nozzle row 62a corresponding to G2 and marked with “K” in a pair with the “Y” portion of the chromatic nozzle row 62b (Y nozzle row) and the “Y” portion. This corresponds to the nozzle group G3.

  FIG. 4 illustrates the positions of the bands (bands 1 to 6) on the print medium recorded by the above passes on the right side. In FIG. 4 (and FIGS. 6 and 7 described later), for convenience of explanation, the relative position change between the print head 62 and the print medium is changed by changing the position of the print head 62 in the opposite direction of the second direction. In practice, however, the print head 62 does not move along the first direction, and the print medium moves in the second direction by conveyance as described above. Further, FIG. 4 shows a state in which the masks M1, M2, and M3 are applied to K ink halftone data for printing each band and assigned to three passes near the center. In such bi-directional printing, out of the total of three passes by the nozzle groups G1, G2, and G3 for printing one band, the first pass and the third pass become the forward movement (or the backward movement), and the second time This path is the return path movement (or forward path movement).

  FIG. 5 shows an example of the masks M1, M2, and M3 used in the present embodiment. Each mask has the same size with a predetermined number of vertical and horizontal pixels, and holds “0” or “1” for each pixel. The pixel positions of “1” held by the respective masks are different from each other, and all the pixels are set to “1” when all the masks are combined (superimposed). “1” in each mask means that the dot at that position is assigned to the nozzle group to which the mask corresponds. The mask M1 is prepared in advance for the nozzle group G1, the mask M2 is prepared for the nozzle group G2, and the mask M3 is prepared in advance for the nozzle group G3. In the present embodiment, the masks M1, M2, and M3 have different ratios of “1”, and the ratio is the largest in the mask M2 and about 60% of all pixels, and then the mask M1 has the largest number of all pixels. It is about 40%, and 0% of all pixels in the mask M3.

  According to FIGS. 4 and 5, the halftone data of K ink for printing band 1 is the first (pass 1) of the three passes when band 1 is printed as a result of applying mask M1. ) And the result of applying the mask M2 is assigned to the second pass (pass 2) for printing the band 1, and the result of applying the mask M3 is the third pass (pass 3) for printing the band 1. ). As a result, the halftone data of K ink for printing band 1 (assuming that all the pixels of the halftone data are dots ON (that is, a solid image). The same applies hereinafter.) About 40% of the dots pass. About 60% of the dots are assigned to the K nozzles of the nozzle group G1 of pass 2 and the K nozzles of the nozzle group G1 of pass 2 are assigned to the K nozzles of the nozzle group G1. Note that K ink halftone data for printing band 1 is not assigned to pass 3 as a result (allocation amount 0).

  The same idea applies to the other bands. For example, halftone data of K ink for printing band 2 is the result of applying mask M1 (about 40% of the dots) three times when band 2 is printed. The nozzle group G2 in the second pass (pass 3) in which the result (approx. 60% of the dots) assigned to the nozzle group G1 in the first pass (pass 2) and the mask M2 is applied is the band 2 is printed. Assigned to. As a result, the halftone data of K ink for printing band 2 is not allocated to pass 4 (allocation amount 0).

  In the example of FIG. 4 (and FIGS. 6 and 7 to be described later), the halftone data for each ink type (CMY) other than K ink is the corresponding ink type among a plurality of passes for printing one band. 100% is allocated to one pass printed by a nozzle group having a nozzle row. For example, the halftone data of C ink for printing band 1 is 100% of the dots to the C nozzle of the nozzle group G1 of pass 1, and the halftone data of M ink for printing band 1 is the dot 100% of the Y ink halftone data for printing band 1 is assigned to the M nozzles in the nozzle group G2 in pass 2 and 100% of the dots are assigned to the Y nozzles in the nozzle group G3 in pass 3.

  The print command generated by the rasterization process is output to the printer 50 (step S140). As a result, the printer 50 prints 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 as described above, and completes an image composed of a plurality of bands.

  As described above, according to the present embodiment, when a band on the print medium is printed by a plurality of passes of the print head 62, the ejection of K ink is stopped in at least one pass process. Therefore, it is possible to appropriately secure the drying time for K ink, and it is possible to suppress bleeding for K ink. Also, with respect to the ink (Y ink in the example of FIG. 4) ejected at the timing when the ejection of the K ink is absent, there is no other color ink ejected at the same time (in the same pass). Stable color development can be obtained with less blurring and the like. Further, the ratio of the discharge amount of the K ink is different between the passes in which the K ink is ejected to the band (in the example of FIG. 4, the printing is performed with the nozzle group G1 and the printing with the nozzle group G2). In the example of FIG. 4, 40% and 60%). Therefore, these ratios can be changed according to the type of chromatic color ink discharged together with the K ink, and the color development for each chromatic color ink can be controlled appropriately.

  For example, chromatic color ink with high luminance has a feature that color development on a print medium tends to be low due to the influence of K ink ejected together. In the present embodiment, when the K ink is ejected together with the C ink to one band as described above, and the K ink is ejected together with the M ink, the amount of the K ink ejected together with the C ink having higher luminance is set. Keep it low. Therefore, it is possible to sufficiently secure the color development of the Y ink having the highest luminance among the CMY inks as described above, and at the same time, the color development of the C ink having the next highest luminance is prevented from being excessively suppressed. A high-quality printing result with little color unevenness (small difference in color density between chromatic colors) with a well-balanced color development can be obtained.

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. In the following, differences from the above-described embodiment will be mainly described. 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.

Modification 1:
FIG. 6 is a diagram for explaining an example of the above assignment of the halftone data for each pass and each nozzle of the print head 62, and shows an example different from FIG. In FIG. 6, the mask M1 is prepared for the nozzle group G1, the mask M2 is prepared for the nozzle group G2, and the mask M3 is prepared in advance for the nozzle group G3. In the masks M1, M2, and M3 in the first modification, when one band is focused, either the mask applied to the forward movement path or the mask applied to the backward movement path is “1”. The ratio is set to be 0%. Specifically, in the example of FIG. 6, the sum of the ratios of “1” in the mask M1 and the mask M3 is 100% (about 60% + about 40%) of all the pixels, and the ratio of “1” in the mask M2. Is 0% of all pixels.

  According to FIG. 6, for example, the halftone data of K ink for printing band 1 is the result of applying the mask M1 (about 60% of the dots) in the nozzle group of pass 1 (forward movement). The result of applying the mask M3 to the K nozzle of G1 (about 40% of the dots) is assigned to each K nozzle of the nozzle group G3 of pass 3 (forward movement) (half of K ink for printing band 1) As a result, tone data is not allocated to path 2 (return movement) (allocation amount 0)). The same applies to other bands. For example, halftone data of K ink for printing band 2 has a result of applying mask M1 (about 60% of dots) as pass 2 (return movement). The result of applying the mask M3 to the K nozzles in the nozzle group G1 (about 40% of the dots) is assigned to the K nozzles in the nozzle group G3 in pass 4 (return movement) (for printing band 2). As a result, K ink halftone data is not assigned to pass 3 (forward movement) (assignment amount 0)).

  Here, in the printer 50 that prints an image with a plurality of passes of the print head 62 for one band, the position in the main scanning direction of each image by each pass is completely caused by a mechanical error of the carriage 60 and the like. It may not match. Such misregistration in the main scanning direction can lead to deterioration in image quality (blurred printing result) when printing is completed. Further, the positional deviation is more likely to occur in bidirectional printing than in unidirectional printing because the positions of printing by forward movement and printing by backward movement can be misaligned. However, according to the first modification, the passes for discharging K ink from the achromatic nozzle row 62a to the band are limited to the first pass and the third pass for the band. That is, the path for ejecting K ink to the band is unified to either the forward movement or the backward movement for each band. For this reason, the occurrence of the above-described misregistration is suppressed, and a print result without blur (less) can be obtained. That is, according to the first modification, a sharper printing result can be obtained, and in particular, a good image quality (sharp characters) can be obtained when printing characters that use a lot of K ink.

  Also in the first modification, when printing a band on the print medium by a plurality of passes of the print head 62, the K ink is not ejected in at least one pass process, so the drying time for the K ink is set appropriately. Can be ensured, and bleeding of K ink can be suppressed. Further, also in the first modified example, the K ink is ejected between passes in which K ink is ejected to the band (in the example of FIG. 6, the printing is performed by the nozzle group G1 and the printing is performed by the nozzle group G3). The amount ratio is different. Specifically, when the K ink is ejected together with the C ink to one band, and the K ink is ejected together with the Y ink, the amount of the K ink ejected together with the Y ink having higher luminance is kept low. In other words, the higher the brightness of the ink, the smaller the amount of K ink discharged when K ink is simultaneously discharged, so that the color development is not suppressed excessively. For this reason, it is possible to obtain a high-quality printing result with little color unevenness (small difference in shade between chromatic colors) in which the color development of each chromatic color ink is secured in a well-balanced manner.

Modification 2:
FIG. 7 is a diagram for explaining an example of the above assignment of halftone data to each pass and each nozzle of the print head 62, and shows an example different from FIGS. 7, masks M1, M2, and M3 (referred to as first mask groups) illustrated in FIGS. 4 and 5 and masks M1, M2, and M3 (referred to as second mask groups) illustrated in FIG. 6 are used. The case where it applies to each band alternately is shown. That is, for example, halftone data of K ink for printing band 1 is obtained by applying the mask M1 of the second mask group (about 60% of the dots) to the K nozzle of the nozzle group G1 of pass 1. The result of applying the mask M2 of the second mask group (assignment amount 0) is the result of applying the mask M3 of the second mask group (about 40% of the dots) to the K nozzle of the nozzle group G2 of pass 2. Assigned to the K nozzles of the three nozzle groups G3. The halftone data of K ink for printing the next band 2 is the result of applying the mask M1 of the first mask group (about 40% of the dots) to the K nozzle of the nozzle group G1 of pass 2. The result of applying the mask M2 of the first mask group (about 60% of the dots) is the result of applying the mask M3 of the first mask group to the K nozzle of the nozzle group G2 of pass 3 (allocation amount 0). Each of the four nozzle groups G3 is assigned to a K nozzle.
That is, it is not necessary to apply the same masks M1, M2, and M3 in any band to the halftone data of K ink for printing each band, and it is applied for each band as shown in FIG. The masks M1, M2, and M3 may be changed.

Other:
As illustrated in FIG. 5, “1” in each of the remaining masks excluding any one of the masks M1, M2, and M3 described so far is arranged in a dispersive manner in the mask. To do. As described above, if the disposition of “1” in each mask is made dispersive, each location where the landing order of the chromatic ink and the achromatic ink is reversed by the printing of the forward movement and the printing of the backward movement is printed. Even in the case where they coexist on the medium (except in the case of FIG. 6), these portions are present at random, and the uneven color caused by the inversion is alleviated.

  However, the arrangement mode of “1” in each mask can be changed as appropriate, and may be arranged with a certain regularity. In addition, the specific numerical value indicating the ratio of “1” in each of the masks M1, M2, and M3 described so far is merely an example, and any numerical value may be used as long as the numerical value matches the idea of the above-described embodiment or modification. Can be adopted. Further, the number of passes for printing one band need not be the same number (3) as the number of nozzle groups G1, G2, G3. For example, one band may be printed with more passes such as six times.

  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 masks M1, M2, and M3 is stored in advance in the ROM 53 in the printer 50. In addition, the CPU 51 displays various information and instructions necessary for printing, such as selection of a printing method for an image to be printed (selection of unidirectional printing and bidirectional printing, etc.) and an operation for instructing printing execution on the operation panel 59. Accept from the user via. 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, 62a ... Achromatic nozzle row, 62b ... chromatic nozzle row, G1, G2, G3 ... nozzle group, M1, M2, M3 ... mask

Claims (7)

An achromatic nozzle array composed of a plurality of nozzles for ejecting achromatic color ink and a chromatic nozzle array composed of a plurality of nozzles for ejecting chromatic color ink, and a plurality of chromatic color ink arrays provided for each of the plurality of chromatic color inks A printing apparatus comprising: a chromatic nozzle row; a print head that is movable along a first direction; and a transport mechanism that transports a print medium in a second direction substantially orthogonal to the first direction.
The print head can execute a pass process for ejecting ink from a nozzle row to a common range of the print medium in each of the forward movement and the backward movement along the first direction. In the process of executing the integral multiple of the number of the chromatic color inks for the range, the achromatic color ink is not ejected from the achromatic color nozzle row and the achromatic color ink is not ejected from the achromatic color nozzle row in at least one pass process. A printing apparatus, wherein the ratio of the amount of achromatic ink to be ejected is different between the ejected pass processes.   In the pass process of ejecting chromatic color ink from the first chromatic color nozzle row that ejects the chromatic color ink having the highest luminance among the plurality of chromatic color inks relative to the common range, the achromatic color from the achromatic color nozzle row Achromatic color ink is discharged to the common range together with the discharge of the chromatic color ink from the second chromatic color nozzle row which discharges the chromatic color ink different from the chromatic color ink having the highest luminance. The printing apparatus according to claim 1, wherein the achromatic color ink is ejected from the achromatic color nozzle row in a smaller amount than the achromatic color ink ejected in the other pass processing.   The printing apparatus according to claim 2, wherein the first chromatic color nozzle row discharges yellow ink.   The plurality of chromatic color inks are cyan ink, magenta ink, and yellow ink, and the print head executes a pass process for the common range three times in total, and one pass process among the three pass processes. The printing apparatus according to claim 1, wherein achromatic ink is not ejected from the achromatic nozzle row.   2. The printing head according to claim 1, wherein a pass process for discharging achromatic ink from the achromatic nozzle row to the common range is unified to either the forward movement or the backward movement. 5. The printing apparatus according to any one of 4. The plurality of chromatic color nozzle rows are arranged in parallel with the achromatic color nozzle row, and are shifted in the tangential direction of the rows,
The print head is paired with any one of the plurality of chromatic color nozzle rows and the one chromatic color nozzle row for the common range in one pass process, and a part of the achromatic color nozzle row is formed. The printing apparatus according to any one of claims 1 to 5, wherein ink can be ejected from a group of achromatic nozzles. An achromatic nozzle array composed of a plurality of nozzles for ejecting achromatic color ink and a chromatic nozzle array composed of a plurality of nozzles for ejecting chromatic color ink, wherein a plurality of chromatic color inks are provided for each of the plurality of chromatic color inks. A printing method using a printing apparatus comprising: a chromatic nozzle row; a print head that is movable in a first direction; and a transport mechanism that transports a print medium in a second direction substantially orthogonal to the first direction. And
The print head can execute a pass process for ejecting ink from a nozzle row to a common range of the print medium in each of the forward movement and the backward movement along the first direction. In the process of executing the integral multiple of the number of the chromatic color inks for the range, the achromatic color ink is not ejected from the achromatic color nozzle row and the achromatic color ink is not ejected from the achromatic color nozzle row in at least one pass process. A printing method, wherein the ratio of the amount of achromatic ink to be ejected is different between the ejecting pass processes.

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