Liquid discharge device, method of the same and program

Abstract

To prevent banding from occurring.SOLUTION: A CPU of a printer repeatedly executes a discharge step of making nozzle rows N1 and N2 arranged to deviate from each other in a longitudinal direction D1 discharge ink and a conveying step of conveying a recording medium forward by a predetermined distance. A first region R1 which is an overlapping region where the nozzle row N1 overlaps in a lateral direction D2 with the nozzle row N2 in the first discharge step is included in a second region R2 (a region other than the first region R1) for the nozzle row N1 in a second discharge step. A third region R3 (excluding nozzles of No. 13-15 that are not used for discharging) which is a non-overlapping region other than the overlapping region where the nozzle row N2 overlaps in the lateral direction D2 with the nozzle row N1 in the first discharge step is not included in an arrangement region of the nozzle row N2 in the second discharge step but included in the second region R2 of the nozzle row N1 in a third discharge step.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection apparatus including a first nozzle row and a second nozzle row, and a control method and program for the same. [Background technology]

[0002] The liquid ejection device described in Patent Document 1 includes a head unit in which a plurality of nozzle rows, each including a plurality of nozzles aligned in a first direction, are aligned in a second direction. The nozzle rows aligned on one side of the second direction are offset in the first direction relative to the nozzle rows aligned on the other side of the second direction. A control unit of the liquid ejection device alternately repeats a main scan, which moves the head unit in the second direction while ejecting ink from the nozzles, and a sub scan, which transports the medium in the first direction. This forms an image on the medium. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-122470 Summary of the Invention [Problem to be solved by the invention]

[0004] It is known that multi-pass printing is performed in an overlapping area in the second direction between two nozzle arrays that are offset in the first direction (see Patent Document 1), or in adjacent areas that are adjacent to each other in the first direction. Multi-pass printing refers to ejecting ink droplets from different nozzles onto a predetermined area on a printing medium.

[0005] Another known technique is interlace printing, which reduces the transport distance in the first direction during sub-scanning and causes the printing areas of multiple main scans to overlap. This allows dots to be formed at a pitch smaller than the nozzle pitch in the first direction, achieving high-resolution printing. Even with this interlace printing technique, multi-pass printing is performed in the overlapping printing areas, with ink droplets being ejected from different nozzles.

[0006] In overlapping areas or adjacent areas where multi-pass printing is performed and areas where multi-pass printing is performed using interlace technology, the number of times ink droplets are ejected onto a predetermined area of ​​the image is greater than in other areas (areas where multi-pass printing is not performed, areas where only multi-pass printing is performed in overlapping or adjacent areas, and areas where only multi-pass printing is performed using interlace technology).As a result, it may appear as if banding has occurred between the overlapping areas and other areas across the entire image.

[0007] An object of the present invention is to provide a liquid ejection apparatus that can prevent the occurrence of banding, and a control method and program therefor. [Means for solving the problem]

[0008] A liquid ejection device according to the present invention includes a first nozzle row including a plurality of first nozzles aligned in a first direction, a second nozzle row including a plurality of second nozzles aligned in the first direction and disposed in a second direction perpendicular to the first direction with respect to the first nozzle row, wherein at least one of the plurality of second nozzles is shifted in the first direction with respect to the first nozzle row, a movement unit that moves a recording medium in the first direction relative to the first nozzle row and the second nozzle row, and a control unit, wherein the control unit performs a first ejection step of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto the recording medium, a first movement step of moving the recording medium a first distance in the first direction by the movement unit after the first ejection step, a second ejection step of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto the recording medium after the first movement step, a second movement step of moving the recording medium a second distance in the first direction by the movement unit after the second ejection step, and and a third ejection step of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto the recording medium after the step, wherein the first movement step is performed at a first distance such that a first region in the first ejection step, which is an overlapping region where the first nozzle row overlaps with the second nozzle row in the second direction or an adjacent region where the first nozzle row is adjacent to the second nozzle row in the first direction, is included in a second region other than the first region of the first nozzle row in the second ejection step, and the first movement step and the second movement step are performed at the first distance and the second distance such that a third region in the first ejection step, which is a non-overlapping region other than the overlapping region where the second nozzle row overlaps with the first nozzle row in the second direction or a non-adjacent region other than an adjacent region where the second nozzle row is adjacent to the first nozzle row in the first direction, is not included in the arrangement region of the second nozzle row in the second ejection step and is included in the second region of the first nozzle row in the third ejection step.

[0009] a control method for a liquid ejection device including a first nozzle array including a plurality of first nozzles aligned in a first direction; a second nozzle array including a plurality of second nozzles aligned in the first direction and disposed in a second direction perpendicular to the first direction with respect to the first nozzle array, wherein at least one of the plurality of second nozzles is shifted in the first direction with respect to the first nozzle array; and a movement unit that moves a recording medium in the first direction relative to the first nozzle array and the second nozzle array, the control method including a first ejection step of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto the recording medium; a first movement step of, after the first ejection step, moving the recording medium a first distance in the first direction relative to the first nozzle array and the second nozzle array by the movement unit; a second ejection step of, after the first movement step, ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto the recording medium; and, after the second ejection step, moving the recording medium a second distance in the first direction relative to the first nozzle array and the second nozzle array by the movement unit. and a third ejection step, after the second movement step, of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto the recording medium, wherein the first movement step is performed at a first distance such that a first region in the first ejection step, which is an overlapping region where the first nozzle row overlaps with the second nozzle row in the second direction or an adjacent region where the first nozzle row is adjacent to the second nozzle row in the first direction, is included in a second region other than the first region of the first nozzle row in the second ejection step, and the first movement step and the second movement step are performed at the first distance and the second distance such that a third region in the first ejection step, which is a non-overlapping region other than the overlapping region where the second nozzle row overlaps with the first nozzle row in the second direction or a non-adjacent region other than an adjacent region where the second nozzle row is adjacent to the first nozzle row in the first direction, is not included in the arrangement region of the second nozzle row in the second ejection step, and is included in the second region of the first nozzle row in the third ejection step.

[0010] The program according to the present invention provides a control device for a liquid ejection device including: a first nozzle array including a plurality of first nozzles aligned in a first direction; a second nozzle array including a plurality of second nozzles aligned in the first direction and disposed in a second direction perpendicular to the first direction with respect to the first nozzle array, wherein at least one of the plurality of second nozzles is shifted in the first direction with respect to the first nozzle array; and a movement unit that moves a recording medium in the first direction relative to the first nozzle array and the second nozzle array, the control device comprising: a first ejection step of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto the recording medium; a first movement step of, after the first ejection step, moving the recording medium a first distance in the first direction relative to the first nozzle array and the second nozzle array by the movement unit; a second ejection step of, after the first movement step, ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto the recording medium; and a second ejection step of moving the recording medium a second distance in the first direction relative to the first nozzle array and the second nozzle array by the movement unit. and a third ejection step of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto a recording medium after the second movement step, wherein the program functions as a control means capable of executing the first movement step at a first distance such that a first region in the first ejection step, which is an overlapping region where the first nozzle row overlaps with the second nozzle row in the second direction or an adjacent region where the first nozzle row is adjacent to the second nozzle row in the first direction, is included in a second region other than the first region of the first nozzle row in the second ejection step, and the program executes the first movement step and the second movement step at a first distance and a second distance such that a third region in the first ejection step, which is a non-overlapping region other than the overlapping region where the second nozzle row overlaps with the first nozzle row in the second direction or a non-adjacent region other than the adjacent region where the second nozzle row is adjacent to the first nozzle row in the first direction, is not included in the arrangement region of the second nozzle row in the second ejection step, and is included in the second region of the first nozzle row in the third ejection step. [Effects of the Invention]

[0011] According to the present invention, by performing the first movement step and the second movement step in this manner, it is possible to prevent the overlap of the area where multi-pass printing is performed in the overlapping area or adjacent area with the area where multi-pass printing is performed using interlace technology, thereby preventing banding. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view of a printer according to an embodiment of the present invention; [Figure 2] FIG. 2 is a plan view showing the internal structure of the printer in FIG. [Figure 3] 2 is a bottom view of a carriage included in the printer of FIG. 1. FIG. [Figure 4] FIG. 2 is a block diagram showing the electrical configuration of the printer in FIG. [Figure 5] 2 is a flowchart showing a program executed by a CPU of the printer of FIG. 1. [Figure 6] 6 is a schematic diagram showing a discharge step and a transport step in FIG. 5. FIG. [Figure 7] FIG. 7 is a diagram corresponding to FIG. 6 in a comparative example of the present invention. [Figure 8] 2 is a bottom view of a carriage included in the printer of FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Embodiment> The printer 1 shown in Figure 1 is one embodiment of a liquid ejection device according to the present invention. In the following description, the up-down direction, the front-back direction D1, and the left-right direction D2 are defined based on the state of Figure 1 in which the printer 1 is installed and ready for use. The up-down direction, the front-back direction D1, and the left-right direction D2 are perpendicular to one another. The front-back direction D1 corresponds to the "first direction" of the present invention, and the left-right direction D2 corresponds to the "second direction" of the present invention.

[0014] As shown in FIG. 1, the printer 1 includes a housing 8, a platen 12, and a transport unit 15.

[0015] The housing 8 has a substantially rectangular parallelepiped shape, and has an opening 13 formed in the front surface thereof.

[0016] The platen 12 is made of a substantially rectangular plate member. An upper surface 12a of the platen 12 is a support surface that supports a recording medium. The recording medium is fabric (for example, a T-shirt containing polyester fibers).

[0017] The transport unit 15 includes a transport motor 152 (see FIG. 4). Driven by the transport motor 152, the transport unit 15 transports the platen 12, which supports the recording medium, in the front-to-rear direction D1 between the outside and the inside of the housing 8 via the opening 13. The transport unit 15 moves the recording medium in the front-to-rear direction D1 relative to the nozzle rows N1 to N4, which will be described later, and corresponds to the "moving unit" of the present invention.

[0018] The platen 12 can be selectively positioned among a set position P1, a standby position P2, and a recording position P3 by the transport of the transport unit 15 (see FIG. 2). The set position P1 is located in the front of the housing 8. The standby position P2 is located in the rear of the housing 8. The recording position P3 is located in the front of the housing 8. The user of the printer 1 supports a recording medium on the top surface 12a of the platen 12 when it is in the set position P1.

[0019] As shown in FIG. 2, the printer 1 further includes four heads 31 to 34, a carriage 4 that holds the heads 31 to 34, and a scanning unit 50.

[0020] The carriage 4 is supported by a front shaft 41 and a rear shaft 42. The front shaft 41 and the rear shaft 42 each extend in the left-right direction D2.

[0021] The scanning unit 50 includes a belt 51 and a scanning motor 52. The belt 51 is connected to the rear end of the carriage 4 and extends in the left-right direction D2 on the rear shaft 42. The scanning unit 50 moves the carriage 4 in the left-right direction D2 along the front shaft 41 and the rear shaft 42 by driving the scanning motor 52.

[0022] The carriage 4 and the heads 31 to 34 held thereby can be selectively placed at a first maintenance position B1, a discharge position B2, and a second maintenance position B3 by being driven by the scanning unit 50 (see FIG. 2).

[0023] The first maintenance position B1 is a position where the heads 31 to 34 are maintained by maintenance units such as wipers and caps, and is located on the left side within the housing 8. The second maintenance position B3 is a position where the user can clean the heads 31 to 34, and is located on the right side within the housing 8. The first maintenance position B1 is located at the left end of the movement range of the carriage 4, and the second maintenance position B3 is located at the right end of the movement range of the carriage 4. The ejection position B2 is located between the first maintenance position B1 and the second maintenance position B3 in the left-right direction D2, and is located approximately in the center of the housing 8 in the left-right direction D2. The ejection position B2 overlaps with the recording position P3 in the vertical direction.

[0024] Of the four heads 31 to 34, the two heads 31 and 32 located at the rear eject white ink, while the two heads 33 and 34 located at the front eject color inks. The white ink is used to record an image as the white portion of the image or as a base for the color inks. The color inks are ejected onto the white ink base and are used to record a color image. The heads 31 to 34 communicate with an ink tank (not shown) via a flow path such as a tube, and ink is supplied from the ink tank to the heads 31 to 34. The ink tank may be either a cartridge type that is detachable from the housing 8, or a fixed type that is fixed to the housing 8 and can be replenished with ink.

[0025] Heads 33 and 34 are positioned forward relative to heads 31 and 32. Head 32 is shifted forward relative to head 31. Head 34 is shifted forward relative to head 33. The four heads 31 to 34 have the same structure.

[0026] As shown in Figure 3, eight nozzles 31N are opened on the underside of the head 31. The eight nozzles 31N are aligned in the front-rear direction D1 and form a nozzle row N1. Eight nozzles 32N are opened on the underside of the head 32. The eight nozzles 32N are aligned in the front-rear direction D1 and form a nozzle row N2. The nozzle row N2 is provided to the left of the nozzle row N1, and six of the eight nozzles 32N are shifted forward from the nozzle row N1.

[0027] Eight nozzles 33N are opened in the lower surface of the head 33. The eight nozzles 33N are aligned in the front-to-rear direction D1 and form a nozzle row N3. Eight nozzles 34N are opened in the lower surface of the head 34. The eight nozzles 34N are aligned in the front-to-rear direction D1 and form a nozzle row N4. The nozzle row N4 is provided to the left of the nozzle row N3, and six of the eight nozzles 34N are shifted forward relative to the nozzle row N3.

[0028] Nozzle 31N corresponds to the "first nozzle" of the present invention, nozzle 32N corresponds to the "second nozzle" of the present invention, nozzle row N1 corresponds to the "first nozzle row" of the present invention, and nozzle row N2 corresponds to the "second nozzle row" of the present invention. Alternatively, nozzle 33N corresponds to the "first nozzle" of the present invention, nozzle 34N corresponds to the "second nozzle" of the present invention, nozzle row N3 corresponds to the "first nozzle row" of the present invention, and nozzle row N4 corresponds to the "second nozzle row" of the present invention.

[0029] The number of nozzles 31N constituting nozzle row N1, the number of nozzles 32N constituting nozzle row N2, the number of nozzles 33N constituting nozzle row N3, and the number of nozzles 34N constituting nozzle row N4 are all the same (8).

[0030] In an area A1 where the nozzle rows N1 and N2 overlap in the left-right direction D2, the positions of two nozzles 31N and two nozzles 32N in the front-rear direction D1 are aligned. In an area A2 where the nozzle rows N3 and N4 overlap in the left-right direction D2, the positions of two nozzles 33N and two nozzles 34N in the front-rear direction D1 are aligned.

[0031] 4, the printer 1 further includes a control device 80. The control device 80 is electrically connected to the driver ICs 130, scanning motors 52, and transport motors 152 of the heads 31 to 34, and is also communicatively connected to an external device (such as a personal computer) 90. The driver ICs 130 send signals to actuators 131 provided for the nozzles 31N to 34N, driving the actuators 131. As the actuators 131 are driven, ink is ejected from the nozzles 31N to 34N.

[0032] The control device 80 includes a CPU 81, a ROM 82, and a RAM 83. The ROM 82 stores programs and data for the CPU 81 to perform various controls. The RAM 83 temporarily stores data (image data, etc.) used when the CPU 81 executes the programs. The CPU 81 executes various controls based on data input from the external device 90 or the input unit of the printer 1, data stored in the ROM 82 and RAM 83, etc. The CPU 81 corresponds to the "control unit" of the present invention.

[0033] Next, the program executed by the CPU 81 will be described with reference to FIG.

[0034] The CPU 81 first determines (S1) whether or not a recording command has been received from the external device 90 or the input unit of the printer 1. If it determines that a recording command has not been received (S1: NO), the CPU 81 repeats the processing of S1.

[0035] When it is determined that a recording command has been received (S1: YES), the CPU 81 causes the conveying unit 15 to convey the platen 12 from the set position P1 to the standby position P2 and then to the recording position P3 (see FIG. 2) (S2). At this time, the conveying unit 15 first conveys the platen 12 backward from the set position P1 to the standby position P2, and then conveys the platen 12 forward from the standby position P2 to the recording position P3.

[0036] After S2, the CPU 81 sets n=1 (S3).

[0037] After S3, the CPU 81 executes the n-th ejection step (S4). In S4, the CPU 81 ejects ink from the nozzles 31N-34N onto the recording medium on the platen 12, which is stationary at recording position P3, while moving the carriage 4 in the left-right direction D2. Note that in S4, the CPU 81 may eject white ink from the nozzles 31N and 32N without ejecting color ink from the nozzles 33N and 34N, or may eject color ink from the nozzles 33N and 34N without ejecting white ink from the nozzles 31N and 32N, or may eject color ink from the nozzles 33N and 34N and eject white ink from the nozzles 31N and 32N.

[0038] After S4, the CPU 81 executes the n-th transport step (S5). In S5, the CPU 81 causes the transport unit 15 to transport the platen 12 forward a predetermined distance. The transport step corresponds to the "moving step" of the present invention.

[0039] After S5, the CPU 81 sets n=n+1 (S6).

[0040] After S6, the CPU 81 determines whether n>x (S7), where x is the number of ejection steps required to print an image based on a print command, and is an integer of 3 or greater in this embodiment.

[0041] If it is determined that n>x is not true (S7: NO), the CPU 81 returns the process to S4 and executes the processes from S4 onwards again. The ejection step (S4) and the transport step (S5) are repeatedly executed, thereby recording an image on the recording medium.

[0042] If it is determined that n>x holds (S7: YES), the CPU 81 causes the conveying unit 15 to convey the platen 12 from the recording position P3 to the set position P1 (see FIG. 2) (S8).

[0043] After S8, the CPU 81 ends the program.

[0044] Next, the ejection step (S4) and the transport step (S5) will be described in detail with reference to Figure 6. Note that although the following description will focus on the ejection patterns of the nozzles in the nozzle rows N1 and N2, the same applies to the ejection patterns of the nozzles in the nozzle rows N3 and N4.

[0045] 6 shows the relative positions of each nozzle in the nozzle arrays N1 and N2 with respect to the recording medium when the first, second, and third discharge steps are performed. Pixel positions on the recording medium are numbered 1 to 46 in order from rear to front. Nozzles in the nozzle array N1 are numbered 0 to 7 in order from rear to front. Nozzles in the nozzle array N2 are numbered 8 to 15 in order from rear to front.

[0046] The No. 6 nozzle of nozzle row N1 and the No. 8 nozzle of nozzle row N2 are aligned in the front-to-back direction D1 and are side by side in the left-to-right direction D2. The No. 7 nozzle of nozzle row N1 and the No. 9 nozzle of nozzle row N2 are aligned in the front-to-back direction D1 and are side by side in the left-to-right direction D2.

[0047] The nozzles in nozzle row N2 are classified into a first group G1 consisting of nozzles No. 8 to No. 12, and a second group G2 consisting of nozzles No. 13 to No. 15. The second group G2 is farther away from nozzle row N1 in the front-to-rear direction D1 than the first group G1. In this embodiment, in each ejection step, ink is ejected from the nozzles in the first group G1, while ink is not ejected from the nozzles in the second group G2.

[0048] In the first transport step, the platen 12 and the recording medium supported thereon are transported a first distance L1. In the second transport step, the platen 12 and the recording medium supported thereon are transported a second distance L2. In this embodiment, the first distance L1 and the second distance L2 are both the distance of nine pixels.

[0049] In each ejection step, ink is ejected from nozzles Nos. 0, 1, 6, and 7 of nozzle array N1 and nozzles Nos. 8, 9, 11, and 12 of nozzle array N2 at a mask ratio of 50%, and ink is ejected from nozzles Nos. 2 to 5 of nozzle array N1 and nozzle No. 10 of nozzle array N2 at a mask ratio of 100%. The mask ratio is the ratio of the ejection amount to the amount of ink required to form each pixel of an image based on a print command. As described above, the mask ratio of the nozzles of the second group G2 of nozzle array N2 (nozzles Nos. 13 to 15) is 0%, and no ink is ejected from these nozzles.

[0050] For example, the pixel at pixel position No. 13 is formed by an ink droplet (mask ratio 50%) ejected from the No. 6 nozzle of nozzle array N1 in the first ejection step and an ink droplet (mask ratio 50%) ejected from the No. 8 nozzle of nozzle array N2 in the first ejection step. The pixel at pixel position No. 14 is formed by an ink droplet (mask ratio 100%) ejected from the No. 2 nozzle of nozzle array N1 in the second ejection step. The pixel at pixel position No. 15 is formed by an ink droplet (mask ratio 50%) ejected from the No. 7 nozzle of nozzle array N1 in the first ejection step and an ink droplet (mask ratio 50%) ejected from the No. 9 nozzle of nozzle array N2 in the first ejection step.

[0051] In the overlapping area where the two nozzle rows N1 and N2 overlap in the left-right direction D2, multi-pass printing is performed, and ink is ejected from nozzles No. 6 and No. 7 of nozzle row N1 and nozzles No. 8 and No. 9 of nozzle row N2 at a mask ratio of 50% each.

[0052] In addition, in this embodiment, interlace technology is adopted, and multi-pass printing processing is performed in a printing area that is partially overlapped by multiple ejection steps, so ink is ejected at a mask ratio of 50% each from nozzles No. 0 and No. 1 in nozzle row N1 and nozzles No. 11 and No. 12 in nozzle row N2.

[0053] With multi-pass printing, one pixel is formed by ink droplets ejected from multiple nozzles, preventing banding caused by differences in the size of ink droplets ejected from each nozzle and manufacturing errors in the distance between nozzles.

[0054] A first region R1, which is an overlapping region where the nozzle row N1 overlaps with the nozzle row N2 in the left-right direction D2 in the first discharge step, is included in a second region R2 (region other than the first region R1) of the nozzle row N1 in the second discharge step. A third region R3 (excluding nozzles No. 13 to No. 15 that are not used for discharge), which is a non-overlapping region other than the overlapping region where the nozzle row N2 overlaps with the nozzle row N1 in the left-right direction D2 in the first discharge step, is not included in the arrangement region of the nozzle row N2 in the second discharge step, and is included in the second region R2 of the nozzle row N1 in the third discharge step.

[0055] As described above, according to this embodiment, by performing the first transport step and the second transport step as described above, it is possible to prevent the overlapping area X1 where multi-pass printing is performed in the left-right direction D2 of the two nozzle rows N1 and N2 from overlapping with the area X2 where multi-pass printing is performed using interlace technology (see FIG. 6), thereby preventing banding from occurring.

[0056] For example, in FIG. 6, region X1 corresponds to pixel positions No. 22 to No. 24. In the second discharge step, ink is discharged onto pixel positions No. 22 to No. 24 from nozzles 31N and 32N included in region A1 in FIG. 3, and in the third discharge step, ink is discharged from nozzle 31N included in a region other than region A1 in FIG. 3. The pixels at pixel positions No. 22 to No. 24 are formed by ink droplets (mask ratio 50%) discharged from nozzles No. 6 and No. 7 of nozzle array N1 in the second discharge step, ink droplets (mask ratio 50%) discharged from nozzles No. 8 and No. 9 of nozzle array N2 in the second discharge step, and ink droplets (mask ratio 100%) discharged from nozzle No. 2 of nozzle array N1 in the third discharge step. Meanwhile, in FIG. 6, region X2 corresponds to pixel positions No. 19 to No. 21. No ink is ejected from nozzles 31N and 32N in region A1 of FIG. 3 onto pixel positions No. 19-21 in any of the first to third ejection steps. The pixels at pixel positions No. 19-21 are formed by ink droplets (mask ratio 50%) ejected from nozzles No. 11 and No. 12 of nozzle array N2 in the first ejection step, ink droplets (mask ratio 100%) ejected from nozzle No. 5 of nozzle array N1 in the second ejection step, and ink droplets (mask ratio 50%) ejected from nozzles No. 0 and No. 1 of nozzle array N1 in the third ejection step. In this way, ink is ejected to both the pixels in region X1 and the pixels in region X2 at a total mask ratio of 200%, combining a mask ratio of 100% + 50% × 2. This prevents banding.

[0057] 7, if the mask ratio for each nozzle is set, the recording medium is transported a first distance L11 different from the first distance L1 in the first transport step, and the recording medium is transported a second distance L21 different from the second distance L2 in the second transport step, part of the third region R3 of the nozzle row N2 in the first ejection step will be included in the arrangement region of the nozzle row N2 in the second ejection step. In this case, the region X1 and the region X2 will overlap, and banding may occur.

[0058] For example, in FIG. 7, the area X1 corresponds to pixel positions No. 26 to No. 28, and the area X2 corresponds to pixel positions No. 25 to No. 27, and the areas X1 and X2 overlap. For example, to pixel positions No. 26 to No. 28, in the first discharge step, ink is discharged from nozzle 32N included in an area other than area A1 in Fig. 3, in the second discharge step, ink is discharged from nozzles 31N and 32N included in area A1 in Fig. 3, and in the third discharge step, ink is discharged from nozzle 31N included in an area other than area A1 in Fig. 3. The pixels at pixel positions No. 26 to No. 28 are formed by ink droplets (mask ratio 50%) discharged from nozzle No. 15 of nozzle array N2 in the first discharge step, ink droplets (mask ratio 50%) discharged from nozzles No. 6 and 7 of nozzle array N1 in the second discharge step, ink droplets (mask ratio 50%) discharged from nozzles No. 8 and 9 of nozzle array N2 in the second discharge step, and ink droplets (mask ratio 50%) discharged from nozzle No. 1 of nozzle array N1 in the third discharge step. On the other hand, no ink is ejected from nozzles 31N and 32N included in area A1 in FIG. 3 onto pixel positions No. 22-24 in any of the first to third ejection steps. The pixels at pixel positions No. 22-24 are formed by ink droplets (mask ratio 100%) ejected from nozzle No. 13 of nozzle row N2 in the first ejection step and ink droplets (mask ratio 100%) ejected from nozzles No. 4 and No. 5 of nozzle row N1 in the second ejection step. In this way, ink is ejected onto pixels at pixel positions No. 26-28 with a mask ratio of 50% x 4, while ink is ejected onto pixels at pixel positions No. 22-24 with a mask ratio of 100% x 2. This may result in banding.

[0059] In each of the first ejection step, second ejection step, and third ejection step, the CPU 81 ejects ink from some of the nozzles in the nozzle row N2 (first group G1) and does not eject ink from the remaining nozzles in the nozzle row N2 (second group G2) (see FIG. 6). By setting the nozzles in the nozzle row N2 that will not be used in each ejection step in this way and then performing the first transport step and the second transport step, it is possible to more reliably prevent the regions X1 and X2 from overlapping. This makes it possible to more reliably prevent banding from occurring.

[0060] In each of the first, second, and third ejection steps, the CPU 81 does not eject ink from the nozzles of the second group G2 (a group that is farther away from the nozzle row N1 in the front-rear direction D1 than the first group G1) (see FIG. 6). This more reliably prevents the regions X1 and X2 from overlapping. In other words, it more reliably prevents banding from occurring.

[0061] The number of nozzles 31N (8) that make up nozzle row N1 is the same as the number of nozzles 32N (8) that make up nozzle row N2 (see FIG. 3). This allows the heads 31 that make up nozzle row N1 and the heads 32 that make up nozzle row N2 to have the same configuration, thereby reducing manufacturing costs.

[0062] In an area A1 where the nozzle rows N1 and N2 overlap in the left-right direction D2, the positions of the nozzles 31N and 32N in the front-rear direction D1 are the same (see FIG. 3). In this case, it is easy to control the multi-pass printing process in the area X1.

[0063] <Modification> Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design modifications are possible within the scope of the claims.

[0064] For example, in the above-described embodiment, some of the nozzles 32N constituting the nozzle row N2 (second nozzle row) are shifted forward relative to the nozzle row N1 (first nozzle row). However, as shown in Fig. 8, all of the nozzles 32N constituting the nozzle row N2 (second nozzle row) may be shifted forward relative to the nozzle row N1 (first nozzle row). In this case, the adjacent region of the nozzle row N1 in the first discharge step adjacent to the nozzle row N2 in the front-to-rear direction D1 is defined as a first region R11, and the non-adjacent region of the nozzle row N2 in the first discharge step other than the adjacent region adjacent to the nozzle row N1 in the front-to-rear direction D1 is defined as a third region R31, as long as the relationship between the first to third regions R1 to R3 shown in Fig. 6 is satisfied. The same applies to the nozzle rows N3 and N4.

[0065] In the above-described embodiment, four nozzle rows N1 to N4 are provided, but at least two nozzle rows may be provided. For example, nozzle rows N3 and N4 may be omitted. Furthermore, of the eight nozzles 32N that make up nozzle row N2, nozzles No. 13 to No. 15 may be omitted.

[0066] In the above-described embodiment, the moving unit is exemplified as a transport unit that transports the recording medium in a first direction, but this is not limited to this and the moving unit may be configured to move a head having a first nozzle row and a second nozzle row in the first direction.

[0067] The recording medium is not limited to fabric, but may be paper, a resin material, or the like.

[0068] The present invention is not limited to printers, but can also be applied to facsimiles, copiers, multifunction machines, etc. The present invention can also be applied to liquid ejection devices used for purposes other than image recording (for example, liquid ejection devices that eject conductive liquid onto a substrate to form a conductive pattern).

[0069] The program according to the present invention can be distributed by recording it on a removable recording medium such as a flexible disk or a fixed recording medium such as a hard disk, or can be distributed via a communication line. [Explanation of symbols]

[0070] 1. Printer (liquid ejection device) 15 Transport section (moving section) 31~34 heads 31N Nozzle (1st Nozzle) 32N Nozzle (2nd Nozzle) 81 CPU (control unit) D1 Anteroposterior direction (first direction) D2 Left / right direction (second direction) G1 Group 1 G2 2nd group L1 1st distance L2 2nd distance N1 nozzle row (first nozzle row) N2 nozzle row (second nozzle row) R1;R11 1st area R2 2nd area R3;R31 Third area

Claims

1. a first nozzle row including a plurality of first nozzles aligned in a first direction; a second nozzle row including a plurality of second nozzles aligned in the first direction, the second nozzle row being provided in a second direction perpendicular to the first direction with respect to the first nozzle row, wherein at least one of the plurality of second nozzles is shifted in the first direction with respect to the first nozzle row; a moving unit that moves a recording medium relatively to the first nozzle row and the second nozzle row in the first direction; a control unit, The control unit a first ejection step of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto a recording medium; a first moving step of moving the recording medium by the moving unit relative to the first nozzle row and the second nozzle row in the first direction by a first distance after the first ejection step; a second ejection step of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto a recording medium after the first movement step; a second moving step of moving the recording medium by the moving unit relative to the first nozzle row and the second nozzle row in the first direction by a second distance after the second ejection step; a third ejection step of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto a recording medium after the second movement step; performing the first movement step at the first distance such that a first region, which is an overlap region where the first nozzle row overlaps with the second nozzle row in the second direction or an adjacent region where the first nozzle row is adjacent to the second nozzle row in the first direction, in the first ejection step is included in a second region other than the first region of the first nozzle row in the second ejection step; A liquid ejection device characterized in that the first movement step and the second movement step are performed at the first distance and the second distance such that a third region in the first ejection step, which is a non-overlapping region other than an overlapping region where the second nozzle row overlaps with the first nozzle row in the second direction or a non-adjacent region other than an adjacent region where the second nozzle row is adjacent to the first nozzle row in the first direction, is not included in the arrangement region of the second nozzle row in the second ejection step and is included in the second region of the first nozzle row in the third ejection step.

2. 2. The liquid ejection device according to claim 1, wherein the control unit ejects liquid from some of the second nozzles and does not eject liquid from the remaining second nozzles in each of the first ejection step, the second ejection step, and the third ejection step.

3. the plurality of second nozzles are classified into a first group and a second group that is farther away from the first nozzle row in the first direction than the first group, The liquid ejection device according to claim 2 , wherein the part is the first group and the remainder is the second group.

4. The liquid ejection device according to claim 1 , wherein the number of the first nozzles and the number of the second nozzles are the same.

5. A liquid ejection device as described in any one of claims 1 to 4, characterized in that in the region where the first nozzle row and the second nozzle row overlap in the second direction, the positions of the first nozzles and the second nozzles in the first direction are the same.

6. a control method for a liquid ejection device including: a first nozzle row including a plurality of first nozzles aligned in a first direction; a second nozzle row including a plurality of second nozzles aligned in the first direction and provided in a second direction perpendicular to the first direction with respect to the first nozzle row, wherein at least one of the plurality of second nozzles is shifted in the first direction with respect to the first nozzle row; and a moving unit that moves a recording medium in the first direction relatively to the first nozzle row and the second nozzle row, a first ejection step of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto a recording medium; a first moving step of moving the recording medium by the moving unit relative to the first nozzle row and the second nozzle row in the first direction by a first distance after the first ejection step; a second ejection step of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto a recording medium after the first movement step; a second moving step of moving the recording medium by the moving unit relative to the first nozzle row and the second nozzle row in the first direction by a second distance after the second ejection step; a third ejection step of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto a recording medium after the second movement step; performing the first movement step at the first distance such that a first region, which is an overlap region where the first nozzle row overlaps with the second nozzle row in the second direction or an adjacent region where the first nozzle row is adjacent to the second nozzle row in the first direction, in the first ejection step is included in a second region other than the first region of the first nozzle row in the second ejection step; A control method characterized in that the first movement step and the second movement step are performed at the first distance and the second distance such that a third region in the first ejection step, which is a non-overlapping region other than an overlapping region where the second nozzle row overlaps with the first nozzle row in the second direction or a non-adjacent region other than an adjacent region where the second nozzle row is adjacent to the first nozzle row in the first direction, is not included in the arrangement region of the second nozzle row in the second ejection step and is included in the second region of the first nozzle row in the third ejection step.

7. a control device used in a liquid ejection device, the control device including: a first nozzle row including a plurality of first nozzles aligned in a first direction; a second nozzle row including a plurality of second nozzles aligned in the first direction and provided in a second direction perpendicular to the first direction with respect to the first nozzle row, wherein at least one of the plurality of second nozzles is shifted in the first direction with respect to the first nozzle row; and a moving unit that moves a recording medium in the first direction relatively to the first nozzle row and the second nozzle row, a first ejection step of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto a recording medium; a first moving step of moving the recording medium by the moving unit relative to the first nozzle row and the second nozzle row in the first direction by a first distance after the first ejection step; a second ejection step of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto a recording medium after the first movement step; a second moving step of moving the recording medium by the moving unit relative to the first nozzle row and the second nozzle row in the first direction by a second distance after the second ejection step; a third ejection step of ejecting liquid from the plurality of first nozzles and the plurality of second nozzles onto a recording medium after the second movement step, performing the first movement step at the first distance such that a first region, which is an overlap region where the first nozzle row overlaps with the second nozzle row in the second direction or an adjacent region where the first nozzle row is adjacent to the second nozzle row in the first direction, in the first ejection step is included in a second region other than the first region of the first nozzle row in the second ejection step; A program characterized by executing the first movement step and the second movement step at the first distance and the second distance such that a third region in the first ejection step, which is a non-overlapping region other than an overlapping region where the second nozzle row overlaps with the first nozzle row in the second direction or a non-adjacent region other than an adjacent region where the second nozzle row is adjacent to the first nozzle row in the first direction, is not included in the arrangement region of the second nozzle row in the second ejection step and is included in the second region of the first nozzle row in the third ejection step.

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