Inkjet printer

Abstract

To provide an inkjet printer that performs bidirectional printing on a printing medium by a multi-pass method, which can secure a quality of printing by the inkjet printer.SOLUTION: In the inkjet printer, nozzle rows 13-16, which are arranged in a main scanning direction to discharge a plurality of color inks, are formed in an inkjet head. The nozzle rows 13-16 are constituted of a plurality of pass rows 13a-13h, 14a-14h, 15a-15h and 16a-16h partitioned with a certain band width in a sub-scanning direction. In at least two different nozzle rows of the nozzle rows 13-16, discharged quantities of inks that are discharged by the pass rows 13a-13h, 14a-14h, 15a-15h and 16a-16h are different from one another. The pass rows 13a-13h, 14a-14h, 15a-15h and 16a-16h which discharge largest discharge quantities of inks are deviated for each of the nozzle rows 13-16.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an inkjet printer that performs bidirectional printing on a print medium using a multi-pass method. [Background technology]

[0002] Conventionally, inkjet printers that print on a print medium using a multi-pass method are known (see, for example, Patent Document 1). The inkjet printer described in Patent Document 1 includes four inkjet heads that eject ink, a carriage on which the four inkjet heads are mounted, a carriage drive mechanism that moves the carriage in the main scanning direction, and a medium feed mechanism that feeds the print medium in the sub-scanning direction. Each inkjet head is formed with one nozzle row consisting of multiple nozzles arranged in the sub-scanning direction, and the four inkjet heads mounted on the carriage have a total of four nozzle rows. The four nozzle rows formed on the four inkjet heads are aligned in the main scanning direction and are positioned at the same position in the sub-scanning direction. The nozzle row is composed of, for example, four pass rows separated by a fixed bandwidth.

[0003] In the inkjet printer described in Patent Document 1, the printing area, or the area on the printing medium where printing is performed, is made up of multiple divided printing areas separated by band widths in the sub-scanning direction. This inkjet printer prints each divided printing area, for example, in four passes. That is, this inkjet printer performs bidirectional printing on the printing medium, for example, by repeatedly moving the carriage to one side in the main scanning direction, feeding the printing medium in the sub-scanning direction relative to the carriage, moving the carriage to the other side in the main scanning direction, and feeding the printing medium in the sub-scanning direction relative to the carriage, in that order, to print four times in each divided printing area, and printing on each divided printing area is completed.

[0004] In the inkjet printer described in Patent Document 1, if any one of the multiple divided print areas is designated as the first divided print area and the divided print area adjacent to the first divided print area in the sub-scanning direction is designated as the second divided print area, in this inkjet printer, the carriage moves to one side in the main scanning direction during first and third pass printing on the first divided print area, and moves to the other side in the main scanning direction during second and fourth pass printing on the first divided print area. Meanwhile, the carriage moves to the other side in the main scanning direction during first and third pass printing on the second divided print area, and moves to one side in the main scanning direction during second and fourth pass printing on the second divided print area. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-62788 Summary of the Invention [Problem to be solved by the invention]

[0006] In the inkjet printer described in Patent Document 1, the direction of carriage movement during the first pass printing in the first divided print area is opposite to the direction of carriage movement during the first pass printing in the second divided print area. Similarly, in this inkjet printer, the direction of carriage movement during each of the second through fourth passes printing in the first divided print area is opposite to the direction of carriage movement during each of the second through fourth passes printing in the second divided print area. Therefore, in the inkjet printer described in Patent Document 1, the landing order of ink ejected from each of the four nozzle arrays arranged in the main scanning direction is opposite between the first divided print area and the second divided print area.

[0007] Therefore, in the inkjet printer described in Patent Document 1, for example, if each of the four nozzle rows ejects a different color ink, there is a risk that a difference will occur between the color tone of the first divided print area and the color tone of the second divided print area after printing is complete. In other words, in this inkjet printer, for example, if each of the four nozzle rows ejects a different color ink, there is a risk that a color shift will occur, in which a difference in color tone will occur between divided print areas adjacent in the sub-scanning direction, and print quality will not be ensured.

[0008] Therefore, an object of the present invention is to provide an inkjet printer that can ensure the printing quality of an inkjet printer that performs bidirectional printing on a printing medium using a multi-pass method by repeatedly moving the carriage to one side in the main scanning direction, feeding the printing medium relative to the carriage in the sub-scanning direction, moving the carriage to the other side in the main scanning direction, and feeding the printing medium relative to the carriage in the sub-scanning direction. [Means for solving the problem]

[0009] In order to solve the above problems, the inkjet printer of the present invention includes one or more M inkjet heads, each formed with a plurality of nozzles capable of ejecting ink toward a print medium, a carriage on which the M inkjet heads are mounted, a carriage drive mechanism for moving the carriage in a main scanning direction, and a feed mechanism for feeding the print medium relatively to the carriage in a sub-scanning direction perpendicular to the up-and-down direction and the main scanning direction, and performs printing on the print medium by a multi-pass method by repeatedly moving the carriage to one side in the main scanning direction, feeding the print medium relatively to the carriage in the sub-scanning direction, and moving the carriage to the other side in the main scanning direction, and feeding the print medium relatively to the carriage in the sub-scanning direction. An inkjet printer, wherein the inkjet head has a nozzle row formed of a plurality of nozzles arranged in the sub-scanning direction, and M inkjet heads mounted on the carriage have a total of N nozzle rows, two or more, arranged in the main scanning direction and ejecting a plurality of color inks, and the nozzle rows are made up of N or more path rows separated by a certain band width in the sub-scanning direction, and the feed mechanism feeds the printing medium in the sub-scanning direction relative to the carriage by an amount equal to the band width when printing on the printing medium, and the path rows eject different amounts of ink in at least two different nozzle rows, and the path row ejecting the greatest amount of ink is shifted for each nozzle row.

[0010] In the present invention, the nozzle arrays are composed of ink ejection path arrays, which are path arrays that eject ink when printing on a print medium, and non-ink ejection path arrays, which are path arrays that do not eject ink, and each of the N nozzle arrays has the same number of ink ejection path arrays.If each of the N nozzle arrays has multiple ink ejection path arrays, in each of the N nozzle arrays, all of the ink ejection path arrays are arranged in a row in the sub-scanning direction, and in each of the N nozzle arrays, the ink ejection path array that is located closest to one side in the sub-scanning direction is defined as the one-end path array, it is preferable that the one-end path arrays of each of the N nozzle arrays are arranged at positions offset from each other in the sub-scanning direction.

[0011] In the present invention, the nozzle array is composed of N+2 or more path arrays, and each of the N nozzle arrays has three or more ink ejection path arrays. In each of the N nozzle arrays, the ink ejection path array that is located furthest to the other side in the sub-scanning direction among the multiple ink ejection path arrays is defined as the other-end path array, and a predetermined ink ejection path array that is located between the one-end path array and the other-end path array in the sub-scanning direction is defined as a specific path array. In each of the N nozzle arrays, the amount of ink ejected by the specific path array is greater than the amount of ink ejected by the other ink ejection path arrays excluding the specific path array. Furthermore, the amount of ink ejected by the ink ejection path array gradually increases from the one-end path array toward the specific path array, and the amount of ink ejected by the ink ejection path array gradually decreases from the specific path array toward the other-end path array. It is preferable that the specific path arrays of the N nozzle arrays are positioned at positions offset from each other in the sub-scanning direction, and are offset in the sub-scanning direction in the same order as the one-end path arrays of the N nozzle arrays are offset.

[0012] In the present invention, if the direction of relative movement of the printing medium with respect to the carriage is defined as the first direction side, for example, M inkjet heads are formed with nozzle rows consisting of a dark ink nozzle row that ejects relatively dark color ink and a light ink nozzle row that ejects relatively light color ink, and the path row on one end of the dark ink nozzle row is arranged on the first direction side of the path row on one end of the light ink nozzle row.

[0013] In the present invention, if the direction of relative movement of the printing medium with respect to the carriage is defined as the first direction side, the M inkjet heads are formed with nozzle rows consisting of a dark ink nozzle row that ejects relatively dark color ink and a light ink nozzle row that ejects relatively light color ink, and the path row on one end of the light ink nozzle row may be positioned on the first direction side of the path row on one end of the dark ink nozzle row.

[0014] In the present invention, for example, a total of four nozzle rows are formed on the M inkjet heads mounted on the carriage, each of which ejects color inks of different colors. [Effects of the Invention]

[0015] As described above, the present invention makes it possible to ensure the printing quality of an inkjet printer that performs bidirectional printing on a printing medium using a multi-pass method by repeatedly moving the carriage to one side in the main scanning direction, feeding the printing medium relative to the carriage in the sub-scanning direction, and moving the carriage to the other side in the main scanning direction and feeding the printing medium relative to the carriage in the sub-scanning direction. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram illustrating a configuration of an inkjet printer according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram for explaining the configuration of the inkjet head shown in FIG. [Figure 3] FIG. 3 is a schematic diagram for explaining the configuration of the nozzle row shown in FIG. [Figure 4] 2 is a diagram for explaining the operation of the inkjet printer shown in FIG. 1 during printing. FIG. [Figure 5] 2 is a diagram for explaining the operation of the inkjet printer shown in FIG. 1 during printing. FIG. [Figure 6] 2 is a diagram for explaining the operation of the inkjet printer shown in FIG. 1 during printing. FIG. [Figure 7] 2 is a diagram for explaining the operation of the inkjet printer shown in FIG. 1 during printing. FIG. [Figure 8] 1. (A) is a diagram for explaining the order in which ink is deposited at specific locations in the divided printing areas shown in FIGS. 4 to 7, and (B) is a diagram for explaining the effect of the inkjet printer shown in FIG. [Figure 9] FIG. 2 is a schematic diagram for explaining the configuration of a nozzle row according to a reference embodiment of the present invention. [Figure 10] FIG. 10 is a schematic diagram for explaining the configuration of a nozzle row according to another embodiment of the present invention. [Figure 11] FIG. 10 is a schematic diagram for explaining the configuration of a nozzle row according to another embodiment of the present invention. [Figure 12] FIG. 10 is a schematic diagram for explaining the configuration of a nozzle row according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] (Outline of inkjet printer configuration) Fig. 1 is a schematic diagram illustrating the configuration of an inkjet printer 1 according to an embodiment of the present invention, Fig. 2 is a schematic diagram illustrating the configuration of inkjet heads 3 to 6 shown in Fig. 1.

[0019] The inkjet printer 1 (hereinafter referred to as "printer 1") of this embodiment is, for example, a commercial inkjet printer, and prints on a print medium 2. The print medium 2 is, for example, printing paper, fabric, or resin film. The printer 1 is equipped with inkjet heads 3 to 6 (hereinafter referred to as "heads 3 to 6") that eject ink. The printer 1 of this embodiment is equipped with multiple heads 3 to 6. Specifically, the printer 1 is equipped with four heads 3 to 6. The heads 3 to 6 eject ultraviolet-curable ink (UV ink).

[0020] The printer 1 also includes an ultraviolet irradiator 7 that irradiates ultraviolet light on the ink ejected from the heads 3-6 to cure the ink, a carriage 8 on which the four heads 3-6 and the ultraviolet irradiator 7 are mounted, a carriage drive mechanism 9 that moves the carriage 8 in the main scanning direction (the Y direction in FIG. 1, etc.), a guide rail 10 that guides the carriage 8 in the main scanning direction, a platen 11 on which the print medium 2 is placed during printing, and a medium feed mechanism 12 that feeds the print medium 2 in the vertical direction (the Z direction in FIG. 1, etc.) and in a sub-scanning direction (the X direction in FIG. 1, etc.) that is perpendicular to the main scanning direction. The medium feed mechanism 12 in this embodiment is a feed mechanism that feeds the print medium 2 relatively to the carriage 8 in the sub-scanning direction.

[0021] The printer 1 may be provided with a guide shaft instead of the guide rail 10. The printer 1 may be provided with a table on which the print medium 2 is placed and a table feed mechanism that feeds the table in the sub-scanning direction instead of the platen 11 and the medium feed mechanism 12. In this case, the table feed mechanism is a feed mechanism that feeds the print medium 2 relatively to the carriage 8 in the sub-scanning direction. The printer 1 may be provided with a table on which the print medium 2 is placed and a carriage feed mechanism that feeds the carriage 8 together with the guide rail 10 in the sub-scanning direction instead of the platen 11 and the medium feed mechanism 12. In this case, the carriage feed mechanism is a feed mechanism that feeds the print medium 2 relatively to the carriage 8 in the sub-scanning direction.

[0022] The printer 1 of this embodiment alternately moves the carriage 8 in the main scanning direction and feeds the print medium 2 in the sub-scanning direction multiple times to print on the print medium 2 using a multi-pass method. Specifically, the printer 1 prints on the print medium 2 using a multi-pass method by repeatedly moving the carriage 8 to one side in the main scanning direction, feeding the print medium 2 in the sub-scanning direction, moving the carriage 8 to the other side in the main scanning direction, and feeding the print medium 2 in the sub-scanning direction. In other words, the heads 3 to 6 eject ink both when the carriage 8 moves to one side in the main scanning direction and when the carriage 8 moves to the other side in the main scanning direction, and the printer 1 performs bidirectional printing on the print medium 2.

[0023] In the following description, the main scanning direction (Y direction) is referred to as the "left-right direction," and the sub-scanning direction (X direction) is referred to as the "front-rear direction." Furthermore, the X1 direction side in FIG. 1, etc., which is one side of the front-rear direction, is referred to as the "front" side, and the X2 direction side in FIG. 1, etc., which is the opposite side, is referred to as the "rear" side. In this embodiment, the printing medium 2 is fed to the front side when printing on the printing medium 2. In other words, the front side (X1 direction side) in this embodiment is the first direction side, which is the side in the direction of relative movement of the printing medium 2 with respect to the carriage 8.

[0024] The carriage drive mechanism 9 includes, for example, two pulleys, a belt that is stretched over the two pulleys and is partially fixed to the carriage 8, and a motor that rotates the pulleys. The carriage 8 is disposed above the platen 11. As described above, the carriage 8 is equipped with four heads 3 to 6. The four heads 3 to 6 are mounted on the carriage 8 so as to be adjacent to each other in the left-right direction. In other words, the four heads 3 to 6 are arranged in the left-right direction. The four heads 3 to 6 are arranged in this order from one side to the other in the left-right direction. Furthermore, the four heads 3 to 6 are arranged in the same position in the front-to-rear direction.

[0025] The ultraviolet irradiators 7 are mounted on the carriage 8 on both sides of the heads 3 to 6 in the left-right direction. That is, two ultraviolet irradiators 7 are mounted on the carriage 8. The ultraviolet irradiators 7 include, for example, a plurality of light-emitting elements and a substrate on which the plurality of light-emitting elements are mounted. The light-emitting elements are, for example, UV LED chips that emit ultraviolet light. The number of ultraviolet irradiators 7 mounted on the carriage 8 may be one. Furthermore, the ink ejected by the heads 3 to 6 may be ink other than ultraviolet-curable ink. In this case, the ultraviolet irradiators 7 are not necessary.

[0026] The heads 3 to 6 mounted on the carriage 8 eject ink toward the upper surface of the print medium 2 placed on the platen 11. In other words, the heads 3 to 6 eject ink downward. A plurality of nozzles capable of ejecting ink toward the print medium 2 are formed on the lower surfaces of the heads 3 to 6. The heads 3 to 6 are equipped with a plurality of piezoelectric elements (piezo elements) for ejecting ink from each of the plurality of nozzles. The piezoelectric elements are controlled by a head control unit that controls the heads 3 to 6. Furthermore, the piezoelectric elements are controlled, for example, by PWM (Pulse Width Modulation).

[0027] The nozzles formed in the heads 3 to 6 are arranged in the front-to-back direction, and the nozzles form nozzle rows 13 to 16. That is, the heads 3 to 6 are formed with nozzle rows 13 to 16, each consisting of a plurality of nozzles arranged in the sub-scanning direction. Specifically, one nozzle row 13 is formed in the head 3, one nozzle row 14 is formed in the head 4, one nozzle row 15 is formed in the head 5, and one nozzle row 16 is formed in the head 6. That is, a total of four nozzle rows 13 to 16 are formed in the four heads 3 to 6 mounted on the carriage 8. The nozzle rows 13 to 16 are each composed of, for example, 320 nozzles. The lengths of the nozzle rows 13 to 16 in the front-to-back direction are equal to each other. The four nozzle rows 13 to 16 are arranged in the left-to-right direction. Furthermore, the four nozzle rows 13 to 16 are arranged at the same position in the front-to-back direction.

[0028] The nozzle rows 13 to 16 eject color inks (colored inks) of different colors. That is, the four heads 3 to 6 are formed with four nozzle rows 13 to 16 that eject color inks of different colors. In this embodiment, the color of ink ejected by the nozzle row 13 is cyan (C), the color of ink ejected by the nozzle row 14 is magenta (M), the color of ink ejected by the nozzle row 15 is yellow (Y), and the color of ink ejected by the nozzle row 16 is black (K).

[0029] As described above, the printer 1 uses a multi-pass method to print on the print medium 2. For example, the printer 1 may print on the print medium 2 in 8 passes, 16 passes, or 32 passes, but the following describes the configuration of the nozzle rows 13 to 16 when the printer 1 prints on the print medium 2 in 8 passes.

[0030] The nozzle array 13 is made up of multiple path arrays 13a-13h that are separated by a fixed bandwidth BW in the front-to-back direction (sub-scanning direction). Because the printer 1 prints on the print medium 2 in eight passes, the nozzle array 13 is separated into eight path arrays 13a-13h. That is, the nozzle array 13 is made up of the eight path arrays 13a-13h. Similarly, the nozzle array 14 is made up of eight path arrays 14a-14h that are separated by the bandwidth BW in the front-to-back direction, the nozzle array 15 is made up of eight path arrays 15a-15h that are separated by the bandwidth BW in the front-to-back direction, and the nozzle array 16 is made up of eight path arrays 16a-16h that are separated by the bandwidth BW in the front-to-back direction. A more specific configuration of the nozzle arrays 13-16 will be described later.

[0031] The medium feed mechanism 12 includes, for example, a drive roller that contacts one side of the print medium 2, a driven roller that is disposed opposite the drive roller and that contacts the other side of the print medium 2, and a motor that rotates the drive roller. The medium feed mechanism 12 feeds the print medium 2 in the sub-scanning direction by an amount equal to the bandwidth BW when printing on the print medium 2. Specifically, the medium feed mechanism 12 feeds the print medium 2 forward by an amount equal to the bandwidth BW when printing on the print medium 2.

[0032] (Nozzle array configuration) FIG. 3 is a schematic diagram for explaining the configuration of the nozzle rows 13 to 16 shown in FIG.

[0033] As described above, nozzle row 13 is composed of eight path rows 13a to 13h, nozzle row 14 is composed of eight path rows 14a to 14h, nozzle row 15 is composed of eight path rows 15a to 15h, and nozzle row 16 is composed of eight path rows 16a to 16h. Each of path rows 13a to 13h, 14a to 14h, 15a to 15h, and 16a to 16h is composed of a plurality of nozzles.

[0034] Path arrays 13a to 13h are arranged in this order from rear to front, with path array 13a constituting the rear end of nozzle array 13 and path array 13h constituting the front end of nozzle array 13. Similarly, path arrays 14a to 14h, 15a to 15h, and 16a to 16h are arranged in this order from rear to front, with path arrays 14a, 15a, and 16a constituting the rear end of nozzle arrays 14 to 16 and path arrays 14h, 15h, and 16h constituting the front end of nozzle arrays 14 to 16.

[0035] Path arrays 13a to 13e, 14b to 14f, 15c to 15g, and 16d to 16h eject ink when printing on the print medium 2 in a predetermined print mode. On the other hand, path arrays 13f to 13h, 14a, 14g, 14h, 15a, 15b, 15h, and 16a to 16c do not eject ink when printing on the print medium 2 in a predetermined print mode. In other words, when printing on the print medium 2 in a predetermined print mode, the nozzles that make up path arrays 13f to 13h, 14a, 14g, 14h, 15a, 15b, 15h, and 16a to 16c are masked, and no voltage is applied to the piezoelectric elements that correspond to the nozzles that make up path arrays 13f to 13h, 14a, 14g, 14h, 15a, 15b, 15h, and 16a to 16c.

[0036] In this embodiment, path arrays 13a to 13e, 14b to 14f, 15c to 15g, and 16d to 16h are ink ejection path arrays that eject ink when printing on the print medium 2, while path arrays 13f to 13h, 14a, 14g, 14h, 15a, 15b, 15h, and 16a to 16c are non-ink ejection path arrays that do not eject ink when printing on the print medium 2. Each of the nozzle arrays 13 to 16 has five ink ejection path arrays. In other words, each of the four nozzle arrays 13 to 16 has the same number of ink ejection path arrays.

[0037] Nozzle row 13 is composed of path rows 13a to 13e that are ink ejection path rows and path rows 13f to 13h that are ink non-ejection path rows. Nozzle row 14 is composed of path rows 14b to 14f that are ink ejection path rows and path rows 14a, 14g, and 14h that are ink non-ejection path rows. Nozzle row 15 is composed of path rows 15c to 15g that are ink ejection path rows and path rows 15a, 15b, and 15h that are ink non-ejection path rows. Nozzle row 16 is composed of path rows 16d to 16h that are ink ejection path rows and path rows 16a to 16c that are ink non-ejection path rows.

[0038] In the nozzle array 13, the path arrays 13a to 13e, which are ink ejection path arrays, are arranged in a line in the front-to-back direction (i.e., they are arranged continuously in the front-to-back direction), and no non-ink ejection path arrays are located between the path arrays 13a to 13e, which are ink ejection path arrays. Similarly, in the nozzle array 14, the path arrays 14b to 14f, which are ink ejection path arrays, are arranged in a line in the front-to-back direction, in the nozzle array 15, the path arrays 15c to 15g, which are ink ejection path arrays, are arranged in a line in the front-to-back direction, and in the nozzle array 16, the path arrays 16d to 16h, which are ink ejection path arrays, are arranged in a line in the front-to-back direction. That is, in each of the four nozzle arrays 13 to 16, all of the ink ejection path arrays are arranged in a line in the front-to-back direction.

[0039] In nozzle array 13 (i.e., in head 3), the amount of ink ejected by path array 13c is greater than the amount of ink ejected by path arrays 13a, 13b, 13d, and 13e. Furthermore, the amount of ink ejected by path arrays 13a to 13c gradually increases from path array 13a toward path array 13c, and the amount of ink ejected by path arrays 13c to 13e gradually decreases from path array 13c toward path array 13e. In this embodiment, for example, the amount of ink ejected by path array 13a is equal to the amount of ink ejected by path array 13e, and the amount of ink ejected by path array 13b is equal to the amount of ink ejected by path array 13d.

[0040] In nozzle array 14 (i.e., in head 4), the amount of ink ejected by path array 14d is greater than the amount of ink ejected by path arrays 14b, 14c, 14e, and 14f. Furthermore, the amount of ink ejected by path arrays 14b to 14d gradually increases from path array 14b toward path array 14d, and the amount of ink ejected by path arrays 14d to 14f gradually decreases from path array 14d toward path array 14f. In this embodiment, for example, the amount of ink ejected by path array 14b is equal to the amount of ink ejected by path array 14f, and the amount of ink ejected by path array 14c is equal to the amount of ink ejected by path array 14e.

[0041] In nozzle array 15 (i.e., in head 5), the amount of ink ejected by path array 15e is greater than the amount of ink ejected by path arrays 15c, 15d, 15f, and 15g. Furthermore, the amount of ink ejected by path arrays 15c to 15e gradually increases from path array 15c toward path array 15e, and the amount of ink ejected by path arrays 15e to 15g gradually decreases from path array 15e toward path array 15g. In this embodiment, for example, the amount of ink ejected by path array 15c is equal to the amount of ink ejected by path array 15g, and the amount of ink ejected by path array 15d is equal to the amount of ink ejected by path array 15f.

[0042] In nozzle array 16 (i.e., in head 6), the amount of ink ejected by path array 16f is greater than the amount of ink ejected by path arrays 16d, 16e, 16g, and 16h. Furthermore, the amount of ink ejected by path arrays 16d to 16f gradually increases from path array 16d toward path array 16f, and the amount of ink ejected by path arrays 16f to 16h gradually decreases from path array 16f toward path array 16h. In this embodiment, for example, the amount of ink ejected by path array 16d is equal to the amount of ink ejected by path array 16h, and the amount of ink ejected by path array 16e is equal to the amount of ink ejected by path array 16g.

[0043] Furthermore, for example, the amount of ink ejected by path array 13c is equal to the amount of ink ejected by path array 14d, the amount of ink ejected by path array 15e, and the amount of ink ejected by path array 16f; the amount of ink ejected by path array 13a is equal to the amount of ink ejected by path array 14b, the amount of ink ejected by path array 15c, and the amount of ink ejected by path array 16d; and the amount of ink ejected by path array 13b is equal to the amount of ink ejected by path array 14c, the amount of ink ejected by path array 15d, and the amount of ink ejected by path array 16e.

[0044] The amount of ink ejected by each of path arrays 13a to 13e is adjusted by adjusting the ratio of on / off time (duty ratio) of voltage applied to the piezoelectric elements corresponding to the nozzles constituting path arrays 13a to 13e, and by adjusting the number of nozzles ejecting ink among the nozzles constituting path arrays 13a to 13e. The amount of ink ejected by each of path arrays 14b to 14f, the amount of ink ejected by each of path arrays 15c to 15g, and the amount of ink ejected by each of path arrays 16d to 16h are also adjusted in a similar manner.

[0045] In each of the four nozzle arrays 13 to 16, the ink ejection path array that is located closest to one side in the sub-scanning direction (specifically, located at the rear) is defined as the one-end path array, and the ink ejection path array that is located closest to the other side in the sub-scanning direction (specifically, located at the front) is defined as the other-end path array. In nozzle array 13, path array 13a is the one-end path array, and path array 13e is the other-end path array. In nozzle array 14, path array 14b is the one-end path array, and path array 14f is the other-end path array. In nozzle array 15, path array 15c is the one-end path array, and path array 15g is the other-end path array. In nozzle array 16, path array 16d is the one-end path array, and path array 16h is the other-end path array.

[0046] Furthermore, in each of the four nozzle rows 13 to 16, if a predetermined ink ejection path row located between one end path row and the other end path row in the sub-scanning direction is defined as a specific path row, then in nozzle row 13, path row 13c is the specific path row, in nozzle row 14, path row 14d is the specific path row, in nozzle row 15, path row 15e is the specific path row, and in nozzle row 16, path row 16f is the specific path row.

[0047] In the nozzle array 13, the amount of ink ejected by the path array 13c, which is the specific path array, is greater than the amount of ink ejected by the path arrays 13a, 13b, 13d, and 13e, which are ink ejection path arrays excluding the path array 13c. Furthermore, in nozzle row 14, the amount of ink ejected by path row 14d, which is a specific path row, is greater than the amount of ink ejected by path rows 14b, 14c, 14e, and 14f, which are ink ejection path rows excluding path row 14d; in nozzle row 15, the amount of ink ejected by path row 15e, which is a specific path row, is greater than the amount of ink ejected by path rows 15c, 15d, 15f, and 15g, which are ink ejection path rows excluding path row 15e; and in nozzle row 16, the amount of ink ejected by path row 16f, which is a specific path row, is greater than the amount of ink ejected by path rows 16d, 16e, 16g, and 16h, which are ink ejection path rows excluding path row 16f.

[0048] In this embodiment, path row 13a, which is the path row at one end of nozzle row 13, path row 14b, which is the path row at one end of nozzle row 14, path row 15c, which is the path row at one end of nozzle row 15, and path row 16d, which is the path row at one end of nozzle row 16, are arranged at positions offset from each other in the front-to-back direction. That is, the path rows at one end of each of the four nozzle rows 13 to 16 are arranged at positions offset from each other in the sub-scanning direction. Specifically, path rows 13a, 14b, 15c, and 16d are arranged in this order from rear to front in the front-to-back direction. Furthermore, the path rows at the other end of each of the four nozzle rows 13 to 16 are also arranged at positions offset from each other in the sub-scanning direction.

[0049] In this embodiment, path row 13c, which is a specific path row of nozzle row 13, path row 14d, which is a specific path row of nozzle row 14, path row 15e, which is a specific path row of nozzle row 15, and path row 16f, which is a specific path row of nozzle row 16, are arranged at positions offset from each other in the front-to-back direction. That is, the specific path rows of each of the four nozzle rows 13 to 16 are arranged at positions offset from each other in the sub-scanning direction. Specifically, path rows 13c, 14d, 15e, and 16f are arranged in this order from the rear to the front in the front-to-back direction. That is, the specific path rows of each of the four nozzle rows 13 to 16 are offset in the sub-scanning direction in the same order as the path rows at one end of each of the four nozzle rows 13 to 16.

[0050] (Printing method for print media) Figures 4 to 7 are diagrams for explaining the printing operation of the printer 1 shown in Figure 1. Figure 8(A) is a diagram for explaining the landing order of ink droplets at specific locations in the divided print areas PA1 and PA2 shown in Figures 4 to 7.

[0051] The printing area of ​​the printing medium 2, where printing is performed, is made up of multiple divided printing areas PA, which are separated in the front-to-back direction by a band width BW. Below, when each of the 10 divided printing areas PA (10 divided printing areas PA connected in the front-to-back direction) shown in Figures 4 to 7 is individually shown, the 10 divided areas PA will be referred to as divided printing areas PA1 to PA10. Divided printing areas PA1 to PA10 are arranged in this order from front to back. Also, below, the ink ejected by nozzle row 13 will be referred to as "C," the ink ejected by nozzle row 14 as "M," the ink ejected by nozzle row 15 as "Y," and the ink ejected by nozzle row 16 as "K."

[0052] When printing on the print medium 2, for example, first, the print medium 2 is advanced in the front-to-rear direction until the divided print area PA1 is positioned at the same position as the path arrays 13a, 14a, 15a, and 16a (see FIG. 4A). Then, while the carriage 8 is moved to one side in the left-to-right direction, ink is ejected from the path array 13a onto all or part of the divided print area PA1.

[0053] The print medium 2 is then advanced in the front-to-back direction until the divided print area PA2 is positioned at the same position as the path arrays 13a, 14a, 15a, and 16a (see FIG. 4B). That is, the print medium 2 is advanced forward by an amount equal to the bandwidth BW until the divided print area PA1 is positioned at the same position as the path arrays 13b, 14b, 15b, and 16b. Then, while the carriage 8 is moved to the other side in the left-to-right direction, ink is ejected from the path array 13a onto all or part of the divided print area PA2, and ink is ejected from the path arrays 13b and 14b onto all or part of the divided print area PA1. At this time, ink lands in the order C·M at specific locations in the divided print area PA1.

[0054] The print medium 2 is then fed forward in the front-to-rear direction by an amount equal to the bandwidth BW until the divided printing area PA3 is positioned at the same position as the path arrays 13a, 14a, 15a, and 16a (see Figure 4(C)). Then, while the carriage 8 is moved to one side in the left-to-right direction, ink is ejected from path array 13a onto all or part of the divided printing area PA3, ink is ejected from path arrays 13b and 14b onto all or part of the divided printing area PA2, and ink is ejected from path arrays 13c, 14c, and 15c onto all or part of the divided printing area PA1. At this time, ink lands in a specific location in divided printing area PA1 in the order Y, M, C, and ink lands in a specific location in divided printing area PA2 in the order M, C.

[0055] The print medium 2 is then advanced in the front-to-rear direction until the divided printing area PA4 is positioned at the same position as the path arrays 13a, 14a, 15a, and 16a (see FIG. 5A). Then, while the carriage 8 is moved to the other side in the left-to-right direction, ink is ejected from path array 13a onto all or part of the divided printing area PA4, ink is ejected from path arrays 13b and 14b onto all or part of the divided printing area PA3, ink is ejected from path arrays 13c, 14c, and 15c onto all or part of the divided printing area PA2, and ink is ejected from path arrays 13d, 14d, 15d, and 16d onto all or part of the divided printing area PA1. At this time, ink lands in a specific location in the divided printing area PA1 in the order C, M, Y, and K, ink lands in a specific location in the divided printing area PA2 in the order C, M, and Y, and ink lands in a specific location in the divided printing area PA3 in the order C, M, and Y.

[0056] Thereafter, the print medium 2 is advanced in the front-to-rear direction until divided printing area PA5 is positioned at the same position as path rows 13a, 14a, 15a, and 16a (see FIG. 5B). Then, while moving carriage 8 to one side in the left-to-right direction, ink is ejected from path row 13a onto all or part of divided printing area PA5, ink is ejected from path rows 13b and 14b onto all or part of divided printing area PA4, ink is ejected from path rows 13c, 14c, and 15c onto all or part of divided printing area PA3, ink is ejected from path rows 13d, 14d, 15d, and 16d onto all or part of divided printing area PA2, and ink is ejected from path rows 13e, 14e, 15e, and 16e onto all or part of divided printing area PA1. At this time, ink lands in the order of K, Y, M, C at specific locations in divided printing area PA1 and specific locations in divided printing area PA2, ink lands in the order of Y, M, C at specific locations in divided printing area PA3, and ink lands in the order of M, C at specific locations in divided printing area PA4.

[0057] Then, the print medium 2 is advanced in the front-to-rear direction until divided printing area PA6 is positioned at the same position as path rows 13a, 14a, 15a, and 16a (see FIG. 6A). Then, while moving carriage 8 to the other side in the left-to-right direction, ink is ejected from path row 13a onto all or part of divided printing area PA6, ink is ejected from path rows 13b and 14b onto all or part of divided printing area PA5, ink is ejected from path rows 13c, 14c, and 15c onto all or part of divided printing area PA4, ink is ejected from path rows 13d, 14d, 15d, and 16d onto all or part of divided printing area PA3, ink is ejected from path rows 13e, 14e, 15e, and 16e onto all or part of divided printing area PA2, and ink is ejected from path rows 14f, 15f, and 16f onto all or part of divided printing area PA1.

[0058] At this time, ink lands in specific locations in divided printing area PA1 in the order M, Y, K, ink lands in specific locations in divided printing area PA2 and divided printing area PA3 in the order C, M, Y, K, ink lands in specific locations in divided printing area PA4 in the order C, M, Y, and ink lands in specific locations in divided printing area PA5 in the order C, M.

[0059] Thereafter, the printing medium 2 is fed in the front-to-rear direction until the divided printing area PA7 is positioned at the same position as the pass arrays 13a, 14a, 15a, and 16a (see FIG. 6B). Then, while moving the carriage 8 to one side in the left-right direction, ink is ejected from path array 13a onto all or part of divided printing area PA7, ink is ejected from path arrays 13b and 14b onto all or part of divided printing area PA6, ink is ejected from path arrays 13c, 14c, and 15c onto all or part of divided printing area PA5, ink is ejected from path arrays 13d, 14d, 15d, and 16d onto all or part of divided printing area PA4, ink is ejected from path arrays 13e, 14e, 15e, and 16e onto all or part of divided printing area PA3, ink is ejected from path arrays 14f, 15f, and 16f onto all or part of divided printing area PA2, and ink is ejected from path arrays 15g and 16g onto all or part of divided printing area PA1.

[0060] At this time, at specific locations in divided printing area PA1, ink lands in the order of K·Y, at specific locations in divided printing area PA2, ink lands in the order of K·Y·M, at specific locations in divided printing area PA3 and divided printing area PA4, ink lands in the order of K·Y·M·C, at specific locations in divided printing area PA5, ink lands in the order of Y·M·C, and at specific locations in divided printing area PA6, ink lands in the order of M·C.

[0061] Thereafter, the printing medium 2 is fed in the front-to-rear direction until the divided printing area PA8 is positioned at the same position as the pass arrays 13a, 14a, 15a, and 16a (see FIG. 7(A)). Then, while moving the carriage 8 to the other side in the left-right direction, ink is ejected from path array 13a onto all or part of divided printing area PA8, ink is ejected from path arrays 13b and 14b onto all or part of divided printing area PA7, ink is ejected from path arrays 13c, 14c, and 15c onto all or part of divided printing area PA6, ink is ejected from path arrays 13d, 14d, 15d, and 16d onto all or part of divided printing area PA5, ink is ejected from path arrays 13e, 14e, 15e, and 16e onto all or part of divided printing area PA4, ink is ejected from path arrays 14f, 15f, and 16f onto all or part of divided printing area PA3, ink is ejected from path arrays 15g and 16g onto all or part of divided printing area PA2, and ink is ejected from path array 16f onto all or part of divided printing area PA1.

[0062] At this time, ink lands in a specific location in divided printing area PA2 in the order Y, K, ink lands in a specific location in divided printing area PA3 in the order M, Y, K, ink lands in a specific location in divided printing area PA4 and divided printing area PA5 in the order C, M, Y, K, ink lands in a specific location in divided printing area PA6 in the order C, M, Y, and ink lands in a specific location in divided printing area PA7 in the order C, M. Furthermore, when ink is ejected from pass array 16f onto divided printing area PA1, printing on divided printing area PA1 is completed.

[0063] Thereafter, the printing medium 2 is fed in the front-to-rear direction until the divided printing area PA9 is positioned at the same position as the pass arrays 13a, 14a, 15a, and 16a (see FIG. 7B). Then, while moving carriage 8 to one side in the left-right direction, ink is ejected from path array 13a onto all or part of divided printing area PA9, ink is ejected from path arrays 13b and 14b onto all or part of divided printing area PA8, ink is ejected from path arrays 13c, 14c, and 15c onto all or part of divided printing area PA7, ink is ejected from path arrays 13d, 14d, 15d, and 16d onto all or part of divided printing area PA6, ink is ejected from path arrays 13e, 14e, 15e, and 16e onto all or part of divided printing area PA5, ink is ejected from path arrays 14f, 15f, and 16f onto all or part of divided printing area PA4, ink is ejected from path arrays 15g and 16g onto all or part of divided printing area PA3, and ink is ejected from path array 16f onto all or part of divided printing area PA2.

[0064] At this time, ink lands in a specific location in divided printing area PA3 in the order K, Y, ink lands in a specific location in divided printing area PA4 in the order K, Y, M, ink lands in a specific location in divided printing area PA5 and divided printing area PA6 in the order K, Y, M, C, ink lands in a specific location in divided printing area PA7 in the order Y, M, C, and ink lands in a specific location in divided printing area PA8 in the order M, C. Furthermore, when ink is ejected from path array 16f onto divided printing area PA2, printing on divided printing area PA2 ends.

[0065] The above operation is repeated thereafter to print on the print medium 2. Note that, at a specific location in divided print area PA1 and a specific location in divided print area PA2 that is located in the same position in the left-right direction as the specific location in divided print area PA1 (i.e., a specific location in divided print area PA2 that is adjacent in the front-to-back direction to the specific location in divided print area PA1), ink lands in the order shown in FIG.

[0066] (Main effect of this form) As described above, in this embodiment, each of the nozzle rows 13 to 16 is composed of an ink ejection path row and an ink non-ejection path row, and each of the four nozzle rows 13 to 16 has the same number of ink ejection path rows. Furthermore, in this embodiment, the path rows at one end of each of the four nozzle rows 13 to 16, path row 13a, path row 14b, path row 15c, and path row 16d, are positioned at offset positions relative to each other in the front-to-back direction. Therefore, in this embodiment, as described above, ink lands at a specific location in divided print area PA1 and a specific location in divided print area PA2 that is positioned at the same position in the left-to-right direction as the specific location in divided print area PA1, for example, in the order shown in FIG. 8A.

[0067] In other words, in this embodiment, although the order in which ink lands in divided printing area PA1 after printing using the multi-pass method is completed does not completely match the order in which ink lands in divided printing area PA2, when divided printing area PA1 and divided printing area PA2 are viewed as a whole after printing using the multi-pass method is completed, it is possible to make the order in which ink lands in divided printing area PA1 closer to the order in which ink lands in divided printing area PA2, as shown in Figure 8(A).

[0068] Therefore, in this embodiment, it is possible to reduce the difference in color between the divided print area PA1 and the divided print area PA2 after printing is complete. In other words, in this embodiment, it is possible to reduce the difference in color between two divided print areas PA that are adjacent in the front-to-back direction after printing is complete. Therefore, in this embodiment, it is possible to reduce the occurrence of color shift, which causes a difference in color between divided print areas that are adjacent in the front-to-back direction, and as a result, it is possible to ensure the print quality of the printer 1.

[0069] In particular, in this embodiment, path arrays 13c, 14d, 15e, and 16f, which are the specific path arrays that eject the largest amounts of ink, are arranged at positions offset from one another in the front-to-rear direction. Also, in this embodiment, path arrays 13c, 14d, 15e, and 16f are arranged in this order from the rear to the front in the front-to-rear direction, and are offset in the same order as path arrays 13a, 14b, 15c, and 16d.

[0070] Therefore, in this embodiment, when viewing divided print area PA1 and divided print area PA2 as a whole after multi-pass printing is complete, it is possible to more closely align the ink landing order in divided print area PA1 with the ink landing order in divided print area PA2. Therefore, in this embodiment, it is possible to further reduce the difference in color tone between divided print area PA1 and divided print area PA2 after printing is complete. Therefore, in this embodiment, it is possible to further reduce the occurrence of color shift, which causes a difference in color tone between adjacent divided print areas PA in the front-to-back direction, and as a result, it is possible to improve the print quality of the printer 1.

[0071] In addition, when all path arrays 13a to 13h, 14a to 14h, 15a to 15h, and 16a to 16h are ink ejection path arrays, ink lands at specific locations in divided printing area PA1 and specific locations in divided printing area PA2 that are positioned in the same position in the left-right direction as the specific locations in divided printing area PA1, for example, in the order shown in Figure 8(B). Therefore, in this case, for example, if path arrays 13a to 16a arranged at the same position in the front-to-back direction eject the same amount of ink, path arrays 13b to 16b eject the same amount of ink, path arrays 13c to 16c eject the same amount of ink, path arrays 13d to 16d eject the same amount of ink, path arrays 13e to 16e eject the same amount of ink, path arrays 13f to 16f eject the same amount of ink, path arrays 13g to 16g eject the same amount of ink, and path arrays 13h to 16h eject the same amount of ink, there is a risk of a difference in the color tone of divided printing area PA1 after printing is completed and the color tone of divided printing area PA2 after printing is completed.

[0072] In this embodiment, path array 13a, path array 14b, path array 15c, and path array 16d are positioned at positions offset from one another in the front-to-back direction. Therefore, the number of nozzle arrays 13-16 that eject ink is reduced during the first to third and sixth to eighth passes of the eight-pass printing performed on each divided print area PA. Therefore, in this embodiment, it is possible to suppress color mixing during the first to third and sixth to eighth passes. Furthermore, in this embodiment, path array 13c, path array 14d, path array 15e, and path array 16f, which eject the largest amounts of ink, are positioned at positions offset from one another in the front-to-back direction. This suppresses color mixing during the fourth and fifth passes, and further suppresses color mixing during the first to third and sixth to eighth passes.

[0073] It should be noted that by arranging the nozzle rows 13-16 with a shift in the front-to-rear direction (i.e., by arranging the heads 3-6 with a shift in the front-to-rear direction), it is possible to completely match the ink landing order in the divided print area PA1 and the ink landing order in the divided print area PA2 after multi-pass printing is completed. However, in this case, the carriage 8 becomes larger in the front-to-rear direction. Also, in this case, it takes a long time to print on the print medium 2. In contrast, in this embodiment, the nozzle rows 13-16 are arranged in the same position in the front-to-rear direction, so this problem does not occur.

[0074] (Example of changing the inkjet head arrangement) In the embodiment described above, the four heads 3 to 6 are arranged in this order from one side to the other in the left-right direction, but the four heads 3 to 6 may be arranged in any order from one side to the other in the left-right direction. That is, the four nozzle rows 13 to 16 may be arranged in any order from one side to the other in the left-right direction. Furthermore, in the modified example described below, the four nozzle rows 13 to 16 may be arranged in any order from one side to the other in the left-right direction.

[0075] (Example 1 of changing the ink color ejected by the inkjet head) In the above-described embodiment, the color of ink ejected by nozzle row 13 may be yellow (Y), the color of ink ejected by nozzle row 14 may be cyan (C), the color of ink ejected by nozzle row 15 may be magenta (M), and the color of ink ejected by nozzle row 16 may be black (K). In this case, it becomes possible to arrange a larger amount of the relatively dark black ink closer to the surface of the image after printing than the relatively light yellow ink. This makes it possible to print an image with clear contours (sharp edges) on the print medium 2.

[0076] In this case, nozzle row 16 is a dark ink nozzle row that ejects relatively dark color ink, and nozzle row 13 is a light ink nozzle row that ejects relatively light color ink. That is, dark ink nozzle rows and light ink nozzle rows are formed in the four heads 3 to 6. Furthermore, the path row on one end of nozzle row 16, which is a dark ink nozzle row, (path row 16d) is arranged forward of the path row on one end of nozzle row 13, which is a light ink nozzle row (path row 13a).

[0077] Furthermore, in the above-described embodiment, the color of ink ejected by nozzle row 13 may be light cyan (Lc), the color of ink ejected by nozzle row 14 may be light magenta (Lm), the color of ink ejected by nozzle row 15 may be cyan (C), and the color of ink ejected by nozzle row 16 may be magenta (M). Even in this case, it is possible to arrange a larger amount of cyan and magenta ink, which are relatively darker than the relatively light cyan and light magenta inks, closer to the surface of the image after printing is complete, making it possible to print an image with clear contours, etc., on the print medium 2.

[0078] In this case, nozzle rows 15 and 16 are dark ink nozzle rows that eject relatively dark color ink, and nozzle rows 13 and 14 are light ink nozzle rows that eject relatively light color ink. That is, dark ink nozzle rows and light ink nozzle rows are formed in the four heads 3 to 6. Also, the path rows on one end of nozzle rows 15 and 16, which are dark ink nozzle rows, (path rows 15c and 16d) are arranged forward of the path rows on one end of nozzle rows 13 and 14, which are light ink nozzle row heads (path rows 13a and 14b).

[0079] In addition, when the color of ink ejected by nozzle row 13 is light cyan (Lc), the color of ink ejected by nozzle row 14 is light magenta (Lm), the color of ink ejected by nozzle row 15 is cyan (C), and the color of ink ejected by nozzle row 16 is magenta (M), for example, as shown in Figure 9, path rows 13a to 13e, 14a to 14e, 15d to 15h, and 16d to 16h are ink ejection path rows, path rows 13f to 13h, 14f to 14h, 15a to 15c, and 16a to 16c are non-ink ejection path rows, and path rows 13c, 14c, 15f, and 16f are the specific path rows that eject the most ink.However, since it is possible to arrange more of the relatively dark cyan and magenta ink closer to the surface of the image after printing than the relatively light light cyan and light magenta ink, it is possible to print an image with clear contours, etc. on the print medium 2.

[0080] (Example 2: Changing the ink color ejected by the inkjet head) In the above-described embodiment, the color of ink ejected by nozzle row 13 may be black (K), the color of ink ejected by nozzle row 14 may be magenta (M), the color of ink ejected by nozzle row 15 may be cyan (C), and the color of ink ejected by nozzle row 16 may be yellow (Y). In this case, it is possible to arrange a larger amount of the relatively light yellow ink closer to the surface of the image after printing than the relatively dark black ink. This makes it possible to print a fuzzy image on the print medium 2 with reduced ink graininess.

[0081] In this case, nozzle row 13 is a dark ink nozzle row that ejects relatively dark color ink, and nozzle row 16 is a light ink nozzle row that ejects relatively light color ink. Also, the path row on one end of nozzle row 16, which is a light ink nozzle row, (path row 16d) is located forward of the path row on one end of nozzle row 13, which is a dark ink nozzle row head (path row 13a).

[0082] Furthermore, in the above-described embodiment, the color of ink ejected by nozzle row 13 may be magenta (M), the color of ink ejected by nozzle row 14 may be cyan (C), the color of ink ejected by nozzle row 15 may be light magenta (Lm), and the color of ink ejected by nozzle row 16 may be light cyan (Lc). Even in this case, it is possible to arrange a larger amount of light magenta and light cyan ink, which are relatively lighter than the relatively dark magenta and cyan inks, closer to the surface of the image after printing is completed, making it possible to print a fuzzy image on the print medium 2 with reduced ink graininess.

[0083] In this case, nozzle rows 13 and 14 are dark ink nozzle rows that eject relatively dark color ink, and nozzle rows 15 and 16 are light ink nozzle rows that eject relatively light color ink. Also, the path rows on one end of nozzle rows 15 and 16, which are light ink nozzle rows, (path rows 15c and 16d) are arranged forward of the path rows on one end of nozzle rows 13 and 14, which are dark ink nozzle rows (path rows 13a and 14b).

[0084] In addition, if the color of ink ejected by nozzle row 13 is magenta (M), the color of ink ejected by nozzle row 14 is cyan (C), the color of ink ejected by nozzle row 15 is light magenta (Lm), and the color of ink ejected by nozzle row 16 is light cyan (Lc), then, for example, as shown in FIG. 9, path rows 13a to 13e, 14a to 14e, 15d to 15h, and 16d to 16h are ink ejection path rows, and path rows 13f to 13h, 14f to 14h are ink ejection path rows. Even if 4h, 15a to 15c, and 16a to 16c are non-ink-ejecting path arrays and path arrays 13c, 14c, 15f, and 16f are specific path arrays that eject the most ink, it is possible to arrange a larger amount of light magenta and light cyan ink, which are relatively lighter than the relatively dark magenta and cyan inks, closer to the surface of the image after printing is complete, making it possible to print a fuzzy image on printing medium 2 with reduced ink graininess.

[0085] (Nozzle row change example 1) In the above-described embodiment, the amount of ink ejected by each of the path arrays 13a to 13e may be equal to each other, the amount of ink ejected by each of the path arrays 14b to 14f may be equal to each other, the amount of ink ejected by each of the path arrays 15c to 15g may be equal to each other, and the amount of ink ejected by each of the path arrays 16d to 16g may be equal to each other.

[0086] (Nozzle row change example 2) FIG. 10 is a schematic diagram for explaining the configuration of nozzle rows 13 to 16 according to another embodiment of the present invention.

[0087] In the above-described embodiment, all of the path arrays 13a to 13h, 14a to 14h, 15a to 15h, and 16a to 16h may be ink ejection path arrays, as shown in Fig. 10. In this case, for example, similar to the above-described embodiment, path arrays 13c, 14d, 15e, and 16f are designated as specific path arrays that eject the most ink, and the specific path arrays of the four nozzle arrays 13 to 16 are arranged at positions offset from each other in the front-to-rear direction.

[0088] In this modified example, the specific pass rows of the four nozzle rows 13-16 are positioned at offset positions relative to each other in the front-to-back direction. Therefore, when the divided print areas PA1 and PA2 are viewed as a whole after multi-pass printing is completed, the ink landing order in the divided print area PA1 and the ink landing order in the divided print area PA2 can be made closer. This makes it possible to reduce the difference in color tone between the divided print area PA1 and the divided print area PA2 after printing is completed. In other words, it makes it possible to reduce the difference in color tone between two adjacent divided print areas PA after printing is completed. This makes it possible to reduce color shifts, which are differences in color tone between adjacent divided print areas PA, thereby ensuring the print quality of the printer 1.

[0089] In addition, in this modified example, the specific path rows of the four nozzle rows 13 to 16 that eject the largest amount of ink are positioned at positions offset from each other in the front-to-back direction, making it possible to suppress the occurrence of color mixing when the specific path rows eject ink.

[0090] (Nozzle row change example 3) FIG. 11 is a schematic diagram for explaining the configuration of nozzle rows 13 to 16 according to another embodiment of the present invention.

[0091] In the above-described embodiment, for example, as shown in FIG. 11, path rows 13a to 13g, 14a to 14g, 15b to 15h, and 16b to 16h may be ink ejection path rows, and path rows 13h, 14h, 15a, and 16a may be non-ink ejection path rows, with path row 13a, which is the path row on one end of nozzle row 13, and path row 14a, which is the path row on one end of nozzle row 14, being arranged at the same position in the front-to-back direction, and path row 15b, which is the path row on one end of nozzle row 15, and path row 16b, which is the path row on one end of nozzle row 16, being arranged at the same position in the front-to-back direction.

[0092] In this case, for example, similar to the embodiment described above, path arrays 13c, 14d, 15e, and 16f are designated as specific path arrays that eject the most ink. Even in this case, because the specific path arrays of the four nozzle arrays 13 to 16 are positioned at positions offset from each other in the front-to-back direction, when viewing divided print area PA1 and divided print area PA2 as a whole after multi-pass printing is completed, it is possible to make the ink landing order in divided print area PA1 and the ink landing order in divided print area PA2 closer together. This makes it possible to reduce the difference between the color tone of divided print area PA1 and the color tone of divided print area PA2 after printing is completed.

[0093] (Nozzle row change example 4) FIG. 12 is a schematic diagram for explaining the configuration of nozzle rows 13 to 16 according to another embodiment of the present invention.

[0094] In the embodiment described above, the printer 1 may print on the print medium 2 using multiple passes other than 8 passes. For example, the printer 1 may print on the print medium 2 using 11 passes. In this case, as shown in FIG. 12, for example, the nozzle row 13 is made up of 11 pass rows 13a to 13k, the nozzle row 14 is made up of 11 pass rows 14a to 14k, the nozzle row 15 is made up of 11 pass rows 15a to 15k, and the nozzle row 16 is made up of 11 pass rows 16a to 16k.

[0095] 12, path arrays 13a-13h, 14b-14i, 15c-15j, and 16d-16k are ink ejection path arrays, while path arrays 13i-13k, 14a, 14j, 14k, 15a, 15b, 15k, and 16a-16c are non-ink ejection path arrays. That is, each of nozzle arrays 13-16 has eight ink ejection path arrays. In this case, it is possible to achieve the same resolution of an image printed on the print medium 2 as that of an image printed on the print medium 2 using a conventional eight-pass method.

[0096] 12, for example, path arrays 13d, 13e, 14e, 14f, 15f, 15g, 16g, and 16h are designated as specific path arrays that eject the most ink, and the specific path arrays of the four nozzle arrays 13 to 16 are arranged at positions offset from one another in the front-to-rear direction. Furthermore, the printer 1 may print on the print medium 2 in 16 passes, for example, or may print on the print medium 2 in 32 passes. When the printer 1 prints on the print medium 2 in 16 passes, the nozzle arrays 13 to 16 include, for example, 16 path arrays. When the printer 1 prints on the print medium 2 in 32 passes, the nozzle arrays 13 to 16 include, for example, 32 path arrays.

[0097] (Other embodiments) The above-described embodiment and modified examples are examples of preferred embodiments of the present invention, but the present invention is not limited to these and various modifications can be made within the scope of the present invention.

[0098] In the above-described embodiments and modifications, when the nozzle arrays 13 to 16 have a specific path array, the number of ink ejection path arrays that the nozzle arrays 13 to 16 have may be three or more. Furthermore, in the above-described embodiments and modifications, the nozzle arrays 13 to 16 mainly have one specific path array, but the nozzle arrays 13 to 16 may also have two or more specific path arrays. For example, as in the modification shown in FIG. 12, the nozzle arrays 13 to 16 may also have two specific path arrays. Furthermore, in the above-described embodiments, when the nozzle arrays 13 to 16 are composed of nine or more path arrays, the specific path arrays of the nozzle arrays 13 to 16 may be arranged at the same position in the front-to-back direction.

[0099] In the above-described embodiments and modifications, the number of heads mounted on the carriage 8 may be one. In this case, four nozzle rows 13 to 16 are formed in one head. The number of heads mounted on the carriage 8 may also be two or three. When the number of heads mounted on the carriage 8 is two, for example, one of the two heads has two nozzle rows 13 and 14 formed therein, and the other head has two nozzle rows 15 and 16 formed therein.

[0100] Furthermore, in the above-described embodiments and modifications, the number of heads mounted on the carriage 8 may be five or more. That is, the printer 1 may have any number of heads, M, which is one or more. In this case, M heads are mounted on the carriage 8. In addition, in this case, it is sufficient that a total of N nozzle arrays, which are two or more, are formed on the M heads mounted on the carriage 8. In the case where a total of N nozzle arrays, which are two or more, are formed on the M heads mounted on the carriage 8, and the nozzle arrays include specific path arrays, it is sufficient that the nozzle arrays are composed of N+2 or more path arrays. With this configuration, it is possible to arrange the specific path arrays of the N nozzle arrays at positions offset from each other in the front-to-rear direction.

[0101] Furthermore, when a total of two or more N nozzle arrays are formed on the M heads mounted on the carriage 8, and the nozzle arrays do not have a specific path array (i.e., when the ink ejection path arrays eject the same amount of ink in each of the N nozzle arrays), the nozzle arrays only need to be composed of N or more path arrays. This configuration makes it possible to arrange the path arrays on one end of each of the N nozzle arrays at positions offset from each other in the front-to-rear direction. Note that when a total of two or more N nozzle arrays are formed on the M heads mounted on the carriage 8, and the nozzle arrays do not have a specific path array, if the nozzle arrays are composed of N path arrays, the number of ink ejection path arrays that the N nozzle arrays have is one. [Explanation of symbols]

[0102] 1. Printer (inkjet printer) 2 Print media 3 to 6 heads (inkjet head, dark ink head, light ink head) 8 Carriage 9 Carriage drive mechanism 12 Media feed mechanism (feed mechanism) 13~16 nozzle rows 13a, 14b, 15d, 16e: Path arrays (ink ejection path arrays, one end path arrays) 13b, 13d, 14c, 14e, 15d, 15f, 16e, 16g: Path array (ink ejection path array) 13c, 14d, 15e, 16f Path arrays (ink ejection path arrays, specific path arrays) 13e, 14f, 15g, 16h Path array (ink ejection path array, other end path array) 13f to 13h, 14a, 14g, 14h, 15a, 15b, 15h, 16a to 16c: Path arrays (path arrays with no ink ejection) BW Bandwidth X sub-scanning direction X1 1st direction Y main scanning direction Z vertical direction

Claims

1. an inkjet printer comprising one or more M inkjet heads each having a plurality of nozzles capable of ejecting ink toward a print medium, a carriage on which the M inkjet heads are mounted, a carriage drive mechanism for moving the carriage in a main scanning direction, and a feed mechanism for feeding the print medium relative to the carriage in a sub-scanning direction perpendicular to the up-and-down direction and the main scanning direction, wherein the inkjet printer performs printing on the print medium by a multi-pass method by repeatedly moving the carriage to one side in the main scanning direction, feeding the print medium relative to the carriage in the sub-scanning direction, moving the carriage to the other side in the main scanning direction, and feeding the print medium relative to the carriage in the sub-scanning direction, The inkjet head has a nozzle row formed thereon, the nozzle row being made up of a plurality of nozzles arranged in a sub-scanning direction, The M inkjet heads mounted on the carriage are formed with N nozzle rows, two or more in total, which are arranged in a main scanning direction and eject a plurality of color inks, the nozzle array is configured by N or more path arrays separated by a fixed band width in the sub-scanning direction, the feed mechanism feeds the printing medium relative to the carriage in a sub-scanning direction by an amount equal to the bandwidth when printing on the printing medium; an inkjet printer, characterized in that the path arrays eject ink in different amounts in at least two different nozzle arrays, and the path array ejecting the largest amount of ink is shifted for each nozzle array.

2. the nozzle array is configured by an ink ejection path array, which is the path array that ejects ink when printing on the print medium, and an ink non-ejection path array, which is the path array that does not eject ink; the number of ink ejection path arrays included in each of the N nozzle arrays is equal, When each of the N nozzle arrays has a plurality of the ink ejection path arrays, all of the ink ejection path arrays are arranged in series in the sub-scanning direction in each of the N nozzle arrays, In each of the N nozzle arrays, the ink ejection path array that is arranged closest to one side in the sub-scanning direction is defined as a one-end path array.

2. The inkjet printer according to claim 1, wherein the one end path arrays of the N nozzle arrays are arranged at positions shifted from each other in the sub-scanning direction.

3. the nozzle array is configured by N+2 or more path arrays, each of the N nozzle arrays includes three or more ink ejection path arrays; In each of the N nozzle arrays, the ink ejection path array that is arranged furthest to the other side in the sub-scanning direction among the plurality of ink ejection path arrays is defined as an other end side path array, and a predetermined ink ejection path array that is arranged between the one end side path array and the other end side path array in the sub-scanning direction is defined as a specific path array, In each of the N nozzle arrays, the amount of ink ejected by the specific path array is greater than the amount of ink ejected by the other ink ejection path arrays excluding the specific path array, and the amount of ink ejected by the ink ejection path array gradually increases from the one end path array toward the specific path array, and the amount of ink ejected by the ink ejection path array gradually decreases from the specific path array toward the other end path array, 3. The inkjet printer according to claim 2, wherein the specific path arrays of the N nozzle arrays are arranged at positions offset from one another in the sub-scanning direction, and are offset in the sub-scanning direction in the same order as the one-end path arrays of the N nozzle arrays are offset.

4. When the direction of relative movement of the print medium with respect to the carriage is defined as a first direction, The M inkjet heads are each formed with a dark ink nozzle row that ejects a relatively dark color ink and a light ink nozzle row that ejects a relatively light color ink, 4. The inkjet printer according to claim 1, wherein the one end path row of the dark ink nozzle row is disposed on the first direction side of the one end path row of the light ink nozzle row.

5. When the direction of relative movement of the print medium with respect to the carriage is defined as a first direction, The M inkjet heads are each formed with a dark ink nozzle row that ejects a relatively dark color ink and a light ink nozzle row that ejects a relatively light color ink, 4. The inkjet printer according to claim 1, wherein the path row on one end of the light ink nozzle row is disposed on the first direction side of the path row on one end of the dark ink nozzle row.

6. 6. The inkjet printer according to claim 1, wherein a total of four nozzle rows are formed in the M inkjet heads mounted on the carriage, each nozzle row ejecting a different color ink.

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