JP2020026055A - Ink jet printer and printing method - Google Patents

Abstract

To provide an ink jet printer capable of suppressing generation of stripe mottles, and to provide a printing method.SOLUTION: Printing means of an ink jet printer forms ink dots on a medium 90 at a position on a grid point group 51 as a group of grid points 51a of a square grid which is formed by a plurality of squares defined with a pair of sides of 1/600 inch in length extending in the direction indicated by an arrow 10b and a pair of sides of 1/600 inch in length extending in the direction indicated by an arrow 10c, and at a position on one of a group of grid points 52a of a square grid which is formed by a plurality of squares defined with a pair of sides of 1/600 inch in length extending in the direction indicated by an arrow 10b and a pair of sides of 1/600 inch in length extending in the direction indicated by an arrow 10c, but the grid point group 52 is shifted from the grid point group 51 just for 1/1200 inch in length in the direction indicated by the arrow 10b and in the direction indicated by the arrow 10c.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an ink jet printer and a printing method that execute printing by ejecting ink toward a medium and forming dots of the ink on the medium.

  As a conventional inkjet printer, a platen that supports the medium from below in the vertical direction, a guide rail that is disposed on the upper side in the vertical direction with respect to the platen and extends in the left-right direction perpendicular to the vertical direction, and a guide A carriage that guides the movement in the left-right direction by the rail, a plurality of inkjet heads mounted on the carriage to eject ink toward the medium, and a medium that conveys the medium in the front-rear direction orthogonal to both the vertical direction and the left-right direction A device including a transport device is known (for example, see Patent Document 1). 2. Description of the Related Art In a conventional inkjet printer, nozzles for ejecting ink are arranged in the inkjet head in the front-rear direction.

  As shown in FIG. 14, a conventional inkjet printer has a pair of opposite sides 911b extending in the left-right direction, that is, the main scanning direction indicated by an arrow 900a and each having a length 911a, and a front-rear direction, that is, an arrow 900b. The ink is positioned at a grid point group 910 which is a group of grid points 910a of a square grid formed by a square 911 formed by a pair of opposite sides 911c each extending in the sub-scanning direction and having a length 911a. Are formed on the medium 900.

JP 2018-034316 A

  However, in the conventional inkjet printer, a streak 931 (see FIG. 15A) in which the height of the ink is higher than the surroundings, a streak 932 in which the height of the ink is lower than the surroundings (see FIG. 15B), and the like. Is caused in the main scanning direction indicated by arrow 900a and the sub-scanning direction indicated by arrow 900b.

  Therefore, an object of the present invention is to provide an inkjet printer and a printing method that can suppress the occurrence of streaks.

  The inkjet printer of the present invention includes a printing unit that performs printing on the medium by ejecting ink toward the medium, and the printing unit extends in a first direction and has a first length. A grid formed by a plurality of rectangles each including a set of opposite sides and a set of opposite sides each extending in a second direction orthogonal to the first direction and each having a second length. A first lattice point group, which is a group of lattice points, a pair of opposite sides each extending in the first direction and having the first length, and each extending in the second direction; A group of grid points of a grid formed of a plurality of rectangles each including a pair of opposite sides having the second length, wherein the grid points are formed in each of the first direction and the second direction. An ink dot is placed on the medium at a position shifted from the first grid point group to the second grid point group. Formed, characterized in that.

  With this configuration, the ink jet printer according to the present invention has a structure in which the first grid point group and the second grid point group are displaced in the first direction and the second direction, respectively. The occurrence of streaks such as streaks that are higher and streaks whose ink height is lower than the surroundings can be suppressed in the first direction and the second direction.

  In the inkjet printer according to the aspect of the invention, the first grid point group and the second grid point group are displaced from each other by a half of the first length in the first direction, In the second direction, they may be shifted from each other by a half of the second length.

  With this configuration, in the ink jet printer of the present invention, since the first lattice point group and the second lattice point group are well-balanced in both the first direction and the second direction, the height of the ink It is possible to suppress the occurrence of streaks such as streaks that are higher than the surroundings and streaks whose ink height is lower than the surroundings in the first direction and the second direction.

  In the inkjet printer according to the aspect of the invention, the first length and the second length may be equal to each other.

  With this configuration, in the ink jet printer of the present invention, since both the first grid point group and the second grid point group are square grid point groups, the height of the ink is higher than the surroundings, Can be suppressed from occurring in the first direction and the second direction.

  In the inkjet printer according to the aspect of the invention, the printing unit may form the dot having the first length in diameter on the medium.

  With this configuration, the ink jet printer according to the present invention has a structure in which the diameter of the dot is the first length. The amount of height change is small, and the occurrence of muscle spots can be effectively suppressed.

  In the ink jet printer of the present invention, the ink is at least one of a UV-curable ink, a latex ink, a UV flash drying ink, an ink that coagulates with a coagulant, and an ink that thickens and gels due to a thixotropic phenomenon. May be one.

  With this configuration, the ink jet printer according to the present invention has a first grid point group and a second grid point group, because the ink after landing swiftly thickens, so that it is difficult to move from the landing position and hard to smooth. Is shifted in each of the first direction and the second direction, and the advantage of suppressing the occurrence of muscle spots is great.

  The printing method of the present invention includes a printing step of performing printing on the medium by discharging ink toward the medium, wherein the printing step extends in a first direction and has a first length. A grid formed by a plurality of rectangles each including a set of opposite sides and a set of opposite sides each extending in a second direction orthogonal to the first direction and each having a second length. A first lattice point group, which is a group of lattice points, a pair of opposite sides each extending in the first direction and having the first length, and each extending in the second direction; A group of grid points of a grid formed of a plurality of rectangles each including a pair of opposite sides having the second length, wherein the grid points are formed in each of the first direction and the second direction. Ink dots are formed on the medium at positions deviated from the first lattice point group and the second lattice point group. Characterized in that it is a step.

  With this configuration, according to the printing method of the present invention, since the first grid point group and the second grid point group are displaced in the first direction and the second direction, the height of the ink is The occurrence of streaks such as streaks that are higher and streaks whose ink height is lower than the surroundings can be suppressed in the first direction and the second direction.

  ADVANTAGE OF THE INVENTION The inkjet printer and printing method of this invention can suppress generation | occurrence | production of a streak.

FIG. 1 is an external perspective view of an inkjet printer according to an embodiment of the present invention. FIG. 2 is a top view of a carriage on which the inkjet head unit shown in FIG. 1 is mounted. FIG. 2 is a bottom view of the inkjet head unit shown in FIG. 1. FIG. 2 is a block diagram of the ink jet printer shown in FIG. 1. FIG. 4A is a diagram illustrating an example of an arrangement of dots printed on a medium by one inkjet head of the inkjet head unit illustrated in FIG. 3. FIG. 5B is a diagram illustrating an example of an arrangement of dots printed on a medium by one inkjet head of the inkjet head unit illustrated in FIG. 3, which is different from FIG. 5A is a diagram illustrating an example of an arrangement of dots printed on a medium by one inkjet head of the inkjet head unit illustrated in FIG. 3, which is different from FIGS. 5A and 5B. FIG. FIG. 5B is a diagram illustrating an example of an arrangement of dots printed on a medium by one inkjet head of the inkjet head unit illustrated in FIG. 3, which is different from FIGS. 5A, 5B, and 6A. It is. FIG. 4 is a diagram illustrating an example of an arrangement of dots printed on a medium by the inkjet head unit illustrated in FIG. 3. 8A is a diagram showing a grid point group serving as a reference for a part of the dots shown in FIG. 8B is a diagram showing a grid point group different from the grid point group shown in FIG. 8A, which is a reference for a part of the dots shown in FIG. FIG. 9A is a diagram showing ink dots corresponding to the lattice point group shown in FIG. FIG. 9B is a diagram illustrating ink dots corresponding to the lattice point group illustrated in FIG. FIG. 2A is a diagram illustrating an example of an image having a straight edge formed by the inkjet printer illustrated in FIG. 1 in one pass. 11B is a diagram illustrating an example of a case where the image illustrated in FIG. 10A is formed by each of a plurality of passes. FIG. 2A is a diagram illustrating an example of an image in which the shape of the edge is jagged, which is formed by the inkjet printer illustrated in FIG. 1 in one pass. FIG. 12B is a diagram illustrating an example of a case where the image illustrated in FIG. 11A is formed by each of a plurality of passes. FIG. 8 is a diagram illustrating an example of a dot arrangement illustrated in FIG. 7 when a dot size is smaller than a standard size. FIG. 8 is a diagram illustrating an example of a dot arrangement illustrated in FIG. 7 when a printing position of a dot is shifted from a standard position. FIG. 11 is a diagram illustrating an example of an arrangement of dots printed on a medium by a conventional inkjet printer. FIG. 15A is a diagram illustrating a streak in which the height of ink is higher than the surroundings in the dot arrangement shown in FIG. FIG. 15 (b) is a view showing a stripe in which the height of the ink is lower than the surroundings in the dot arrangement shown in FIG. FIG. 15A is a diagram illustrating an example of the dot arrangement illustrated in FIG. 14 when the dot size is smaller than a standard size. FIG. 17 (b) is a view showing a stripe in which the height of the ink is lower than the surroundings in the dot arrangement shown in FIG. 16 (a). FIG. 15A is a diagram illustrating an example of the dot arrangement illustrated in FIG. 14 when the printing position of a dot is shifted from a standard position. FIG. 18 (b) is a view showing a stripe in which the height of the ink is lower than the surroundings in the dot arrangement shown in FIG.

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

  First, the configuration of the ink jet printer according to the present embodiment will be described.

  FIG. 1 is an external perspective view of an inkjet printer 10 according to the present embodiment.

  As shown in FIG. 1, the inkjet printer 10 includes a platen 11 that supports the medium 90 from below in a vertical direction indicated by an arrow 10a, and is disposed above the platen 11 in a vertical direction and is orthogonal to the vertical direction. A guide rail 12 extending in the left-right direction indicated by the arrow 10b, a carriage 13 guided by the guide rail 12 to move in the direction indicated by the arrow 10b, and ejecting ink toward the medium 90 mounted on the carriage 13 And a plurality of inkjet head units 21 to 27.

  Various inks can be used as the ink used in the inkjet printer 10. In particular, as the ink used in the ink jet printer 10, an ink having a height, that is, a thickness that is easy to come out is most suitable. For example, as the ink used in the inkjet printer 10, a UV curable ink that cures when irradiated with ultraviolet light, a solvent UV ink, a water-based UV curable ink, is heated by being irradiated with ultraviolet light, and the solvent is heated by the heat. It is preferable to use an ink that solidifies instantaneously, such as an instant dry ink that is vaporized, dried, and fixed.

  FIG. 2 is a top view of the carriage 13 on which the inkjet head units 21 to 27 are mounted.

  As shown in FIG. 2, the carriage 13 includes an inkjet head unit 21 that ejects black ink, an inkjet head unit 22 that ejects yellow ink, an inkjet head unit 23 that ejects magenta ink, and a cyan ink. , An inkjet head unit 25 that ejects red ink, an inkjet head unit 26 that ejects green ink, and an inkjet head unit 27 that ejects blue ink.

  The inkjet head units 22 to 24 are arranged side by side in the direction indicated by the arrow 10b. The inkjet head units 25 to 27 are arranged side by side in the direction indicated by the arrow 10b. The inkjet head unit 21, the inkjet head units 22 to 24, and the inkjet head units 25 to 27 are displaced in a direction indicated by an arrow 10c orthogonal to both a direction indicated by an arrow 10a and a direction indicated by an arrow 10b. Have been.

  FIG. 3 is a bottom view of the inkjet head unit 21.

  As shown in FIG. 3, the inkjet head unit 21 includes four inkjet heads 21a to 21d that eject black ink toward the medium 90 (see FIG. 1). In each of the inkjet heads 21a to 21d, a plurality of nozzles 21e for discharging black ink are arranged side by side in a direction indicated by an arrow 10c.

  In the inkjet head 21a, the plurality of nozzles 21e are arranged so that the distance between the centers of the adjacent nozzles 21e is 4/1200 inches, that is, 300 dpi in the direction indicated by the arrow 10c. I have. Although the inkjet head 21a has been described, the same applies to the inkjet heads 21b to 21d.

  The ink jet head 21b is arranged to be shifted from the ink jet head 21a by 1/1200 inch in the direction shown by the arrow 10c. The ink jet head 21c is displaced from the ink jet head 21a and the ink jet head 21b in directions indicated by arrows 10c by 2/1200 inches and 1/1200 inches, respectively. The inkjet head 21d is arranged to be shifted from the inkjet head 21a, the inkjet head 21b, and the inkjet head 21c in directions indicated by arrows 10c by 3/1200 inches, 2/1200 inches, and 1/1200 inches, respectively.

  Although the inkjet head unit 21 has been described above, the same applies to the inkjet head units 22 to 27.

  FIG. 4 is a block diagram of the inkjet printer 10.

  As shown in FIG. 4, the inkjet printer 10 includes inkjet head units 21 to 27, a medium transport device 31 that transports the medium 90 (see FIG. 1) in a direction indicated by an arrow 10c (see FIG. 1), and a guide. A carriage driving device 32 that moves the carriage 13 (see FIG. 1) in the direction indicated by the arrow 10b (see FIG. 1) along the rail 12 (see FIG. 1), and buttons for inputting various operations, for example. Operating unit 33 as an input device, a display unit 34 as a display device such as an LCD (Liquid Crystal Display) for displaying various information, and directly via a network or without a network by wire or wireless. , A communication unit 35 that is a communication device that communicates with an external device, and a semiconductor memo that stores various information. A storage unit 36 which is a nonvolatile storage device such as a hard disk drive (HDD) or a hard disk drive (HDD), and a control unit 37 for controlling the entire inkjet printer 10.

  The control unit 37 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory) storing programs and various data, and a RAM (Random Access Memory) used as a work area of the CPU. I have. The CPU executes a program stored in the ROM or the storage unit 36.

  The control unit 37 functions as a printing unit 37 a that executes printing on the medium 90 by executing a program stored in the ROM or the storage unit 36.

  Next, the operation of the inkjet printer 10 will be described.

  Upon receiving the print data via the communication unit 35, the printing unit 37a executes printing on the medium 90 based on the print data received via the communication unit 35. That is, the printing unit 37a moves the carriage 13 in the direction indicated by the arrow 10b by the carriage driving device 32, and ejects ink toward the medium 90 by the inkjet head units 21 to 27, thereby forming the medium in the direction indicated by the arrow 10b. 90 is executed. When printing on the medium 90 in the direction indicated by the arrow 10b is performed, the printing unit 37a conveys the medium 90 in the direction indicated by the arrow 10c by the medium conveyance device 31 as necessary, thereby changing the direction indicated by the arrow 10c. Change the print position on the medium 90 at

  5 to 7 are diagrams illustrating an example of an arrangement of dots printed on the medium 90 by the inkjet head unit 21. FIG.

  In the drawings after FIG. 5, the position 41 indicates the same position on the medium 90.

  The printing unit 37a ejects ink toward the medium 90 by the inkjet head 21a while the carriage 13 is moved once in the direction indicated by the arrow 10b by the carriage driving device 32, thereby causing the printing medium 37a to move toward the medium 90 as shown in FIG. A dot 42 of the ink shown in a) is formed. The diameter of the dot 42 is 2/1200 inches. The distance between the centers of the adjacent dots 42 in the direction indicated by the arrow 10b is 2/1200 inches. The distance between the centers of the adjacent dots 42 in the direction indicated by the arrow 10c is 4/1200 inches. In FIG. 5A, each of the dots 42 arranged in the direction indicated by the arrow 10c is ejected at the same time from each of the nozzles 21e of the inkjet head 21a.

  The printing unit 37a ejects ink toward the medium 90 by the inkjet head 21b while the carriage 13 is moved once in the direction indicated by the arrow 10b by the carriage driving device 32, thereby causing the ink to be discharged onto the medium 90 as shown in FIG. The ink dots 42 shown in b) are formed. The diameter of the dot 42 is 2/1200 inches. The distance between the centers of the adjacent dots 42 in the direction indicated by the arrow 10b is 2/1200 inches. The distance between the centers of the adjacent dots 42 in the direction indicated by the arrow 10c is 4/1200 inches. In FIG. 5B, each of the dots 42 arranged in the direction indicated by the arrow 10c is ejected at the same time from each of the nozzles 21e of the inkjet head 21b.

  The printing unit 37a ejects ink toward the medium 90 by the inkjet head 21c while the carriage 13 is moved once in the direction indicated by the arrow 10b by the carriage driving device 32, thereby causing the ink to be discharged onto the medium 90 as shown in FIG. A dot 42 of the ink shown in a) is formed. The diameter of the dot 42 is 2/1200 inches. The distance between the centers of the adjacent dots 42 in the direction indicated by the arrow 10b is 2/1200 inches. The distance between the centers of the adjacent dots 42 in the direction indicated by the arrow 10c is 4/1200 inches. In FIG. 6A, each of the dots 42 arranged in the direction indicated by the arrow 10c is ejected at the same time from each of the nozzles 21e of the inkjet head 21c.

  The printing unit 37a ejects ink toward the medium 90 by the inkjet head 21d while the carriage 13 is moved once in the direction indicated by the arrow 10b by the carriage driving device 32, thereby causing the ink to be ejected toward the medium 90 as shown in FIG. The ink dots 42 shown in b) are formed. The diameter of the dot 42 is 2/1200 inches. The distance between the centers of the adjacent dots 42 in the direction indicated by the arrow 10b is 2/1200 inches. The distance between the centers of the adjacent dots 42 in the direction indicated by the arrow 10c is 4/1200 inches. In FIG. 6B, each of the dots 42 arranged in the direction indicated by the arrow 10c is ejected at the same time from each of the nozzles 21e of the inkjet head 21d.

  In the above, the dots 42 shown in FIGS. 5A to 6B are separately described for easy understanding. However, the printing unit 37a moves the carriage 13 once in the direction indicated by the arrow 10b by the carriage driving device 32, while the inkjet heads 21a to 21d move the printing medium 37a with respect to the medium 90 in FIGS. 5A to 6B. Are formed as shown in FIG. That is, the printing unit 37a forms the ink dots 42 shown in FIG. 7 on the medium 90 while the carriage driving device 32 moves the carriage 13 once in the direction indicated by the arrow 10b.

  FIG. 8A is a diagram illustrating a grid point group 51 serving as a reference for a part of the dots 42 illustrated in FIG. FIG. 8B is a diagram showing a grid point group 52 serving as a reference for a part of the dots 42 shown in FIG.

  The arrangement of the dots 42 shown in FIG. 7 is an arrangement in which the ink dots 42 are formed at the positions of the lattice point group 51 shown in FIG. 8A and the lattice point group 52 shown in FIG. 8B.

  The grid point group 51 shown in FIG. 8A extends in the direction shown by the arrow 10b and has a pair of opposite sides each having a length of 2/1200 inches, and extends in the direction shown by the arrow 10c. This is a group of grid points 51a of a square grid formed by a plurality of squares each including a pair of opposite sides having a length of 2/1200 inches, that is, a square grid point group.

  The grid point group 52 shown in FIG. 8B extends in the direction shown by the arrow 10b and has a pair of opposite sides each having a length of 2/1200 inches, and extends in the direction shown by the arrow 10c. It is a group of grid points 52a of a square grid formed by a plurality of squares each having a pair of opposite sides having a length of 2/1200 inches, that is, a square grid point group. The lattice point group 52 is shifted from the lattice point group 51 by half the length of 2/1200 inch, that is, 1/1200 inch in the direction indicated by the arrow 10b and the direction indicated by the arrow 10c.

  FIG. 9A is a diagram showing the ink dots 42 corresponding to the grid point group 51 shown in FIG. 8A. FIG. 9B is a diagram showing the ink dots 42 corresponding to the grid point group 52 shown in FIG. 8B.

  While the carriage driving device 32 moves the carriage 13 once in the direction indicated by the arrow 10b, the printing unit 37a moves the grid point group 51 (see FIG. 8A) with respect to the medium 90 by the inkjet heads 21a and 21c. The dot 42 of the ink shown in FIG. While the carriage driving device 32 moves the carriage 13 once in the direction indicated by the arrow 10b, the printing unit 37a moves the grid point group 52 (see FIG. 8B) with respect to the medium 90 by the inkjet heads 21b and 21d. 9), the ink dots 42 shown in FIG. 9B are formed. That is, the printing unit 37a forms the ink dots 42 shown in FIG. 7 on the medium 90 by the inkjet heads 21a to 21d while the carriage driving device 32 moves the carriage 13 once in the direction indicated by the arrow 10b. .

  As shown in FIG. 10A, the printing unit 37a performs one-time printing in the direction indicated by the arrow 10b, that is, the shape of the ends 61a and 61b of the image 61 formed in one pass in the direction indicated by the arrow 10c. You may make it straight in the direction shown by arrow 10b. However, when the shape of the ends 61a and 61b in the direction indicated by the arrow 10c of the image 61 formed in one pass is straightened in the direction indicated by the arrow 10b, the printing unit 37a uses the arrow 10c by the medium transport device 31 between the passes. When the conveyance of the medium 90 in the direction shown in FIG. 10 is deviated from the expected, as shown in FIG. A streak, such as a streak 61d, is generated in the direction indicated by the arrow 10b.

  Therefore, as shown in FIG. 11A, the printing unit 37a does not straighten the shapes of the ends 62a and 62b in the direction indicated by the arrow 10c of the image 62 formed in one pass in the direction indicated by the arrow 10b. The jaggedness is preferred. The printing unit 37a conveys the medium 90 in the direction indicated by the arrow 10c by the medium conveying device 31 between the passes when the shapes of the edges 62a and 62b in the direction indicated by the arrow 10c of the image 62 formed in one pass are jagged. 11B, even if the height of the ink is lower than expected, as shown in FIG. 11B, between the images 62 for each pass, a jagged area 62c where the height of the ink is higher than the surroundings, or a jagged area where the height of the ink is lower than the surroundings. Although the region 62d is generated, it is possible to suppress the occurrence of muscle spots in the direction indicated by the arrow 10b.

  The arrangement of the dots 42 when printing with one color of black ink has been described above. However, the same applies to the arrangement of the dots 42 when printing with one color of ink other than black or when printing with two or more colors of ink.

  As described above, in the inkjet printer 10, since the grid point group 51 and the grid point group 52 are displaced in the direction indicated by the arrow 10b and the direction indicated by the arrow 10c, the height of the ink is higher than that of the surroundings. The occurrence of streaks such as streaks or streaks whose ink height is lower than the surroundings can be suppressed in the directions indicated by arrows 10b and 10c.

  The ink jet printer 10 has a grid point group 51 and a grid point group 52 in the direction indicated by the arrow 10b and the direction indicated by the arrow 10c, respectively, in one direction of the smallest square constituting the grid point group 51 and the grid point group 52. Is a half of the length of 2/1200 inches, that is, shifted by a length of 1/1200 inches, that is, the direction and the arrow indicated by the arrow 10b are the grid point group 51 and the grid point group 52. 10C, the streaks such as streaks where the height of the ink is higher than the surroundings and streaks where the height of the ink is lower than the surroundings are indicated by the arrow 10b and the direction indicated by the arrow 10c. Can be suppressed. In the inkjet printer 10, the lattice point group 51 and the lattice point group 52 are shifted in at least one of the direction indicated by the arrow 10b and the direction indicated by the arrow 10c except for a length of 1/1200 inch. May be.

  In the ink jet printer 10, the smallest rectangle forming the lattice point group 51 and the lattice point group 52 is a square in which the length of one side of one set is equal to the length of one side of the other set. is there. That is, in the inkjet printer 10, both the grid point group 51 and the grid point group 52 are square grid point groups. Accordingly, the inkjet printer 10 suppresses the occurrence of streaks such as streaks having a height of ink higher than the surroundings and streaks having a height of ink lower than the surroundings in the directions indicated by the arrows 10b and 10c. Can be. Note that, in the inkjet printer 10, the minimum rectangle forming the lattice point group 51 and the lattice point group 52 does not have to be a square. That is, in the inkjet printer 10, the grid point group 51 is a rectangular grid point group other than the square grid point group, and the grid point group 52 has the same shape and the same size as the grid point group 51. The grid point group may be shifted from the group 51 in the direction indicated by the arrow 10b and the direction indicated by the arrow 10c.

  The arrangement of the dots 42 according to the present embodiment can also suppress the occurrence of streaks due to a shift in the size of the dots 42. For example, as shown in FIG. 16A, the arrangement of the conventional dots 920 shown in FIG. 14 is such that when the size of the dots 920 is smaller than the standard size shown in FIG. As shown in the drawing, a streak 932 in which the height of the ink is lower than the surroundings is remarkably generated in the main scanning direction indicated by an arrow 900a and the sub-scanning direction indicated by an arrow 900b. However, as shown in FIG. 12, the arrangement of the dots 42 according to the present embodiment is such that even when the size of the dots 42 is smaller than the standard size shown in FIG. It is difficult for streaks lower than the surroundings to occur in the directions indicated by arrows 10b and 10c.

  The arrangement of the dots 42 according to the present embodiment can also suppress the occurrence of streaks due to a shift in the printing position of the dots 42. For example, in the conventional arrangement of the dots 920 shown in FIG. 14, as shown in FIG. 17A, the printing position of the dots 920 is shifted from the standard position shown in FIG. 14 by the distance 940 in the direction shown by the arrow 900b. In this case, as shown in FIG. 17B, a streak 932 in which the height of the ink is lower than the surroundings is remarkably generated in the main scanning direction indicated by an arrow 900a at a position where the printing position of the dot 920 is shifted. However, the arrangement of the dots 42 according to the present embodiment is, as shown in FIG. 13, a case where the printing position of the dots 42 is shifted from the standard position shown in FIG. 7 by the distance 43 in the direction shown by the arrow 10c. Even if there is, a streak having zero ink height is unlikely to occur in the direction indicated by the arrow 10b.

  In the arrangement of the dots 42 according to the present embodiment, since the amount of change in the height of the ink depending on the location is small, the dots 42 are less likely to spread around as compared with the conventional arrangement of the dots 920 shown in FIG. , The bleeding of the ink can be greatly reduced in the image printed.

  The ink-jet printer 10 has a grid point when the ink thickness after landing is thick, or when “the ink that is hard to move from the landing position and is hard to smoothen because the ink after landing rapidly thickens” is adopted. Since the group 51 and the lattice point group 52 are shifted by a length of 1/1200 inch in the direction indicated by the arrow 10b and the direction indicated by the arrow 10c, the effect of suppressing the occurrence of muscle spots is great. Examples of “the ink that is hard to move from the landing position and hard to smoothen because the ink after landing rapidly thickens” include, for example, a UV curable ink, a latex ink, a UV flash drying ink, and a high-speed flocculant. At least one of an ink that coagulates into an ink and an ink that thickens and gels due to a thixotropy phenomenon may be employed.

  Since the diameter of the dot 42 is 2/1200 inches, the ink jet printer 10 has both the direction indicated by the arrow 10b and the direction indicated by the arrow 10c as compared with the case where the diameter of the dot 42 is less than 2/1200 inch. The amount of change in the height of the ink depending on the location is small, and the occurrence of streaks can be effectively suppressed.

  In the inkjet printer 10, the diameter of the dots 42 may be more than 2/1200 inches or less than 2/1200 inches.

  In the present embodiment, the inkjet printer 10 realizes the arrangement of the dots 42 shown in FIG. 7 in one printing in the direction indicated by the arrow 10b, that is, in one pass. However, the ink jet printer 10 may realize the arrangement of the dots 42 shown in FIG. 7 with the number of passes other than one pass. For example, the inkjet printer 10 may realize the arrangement of the dots 42 shown in FIG. 7 in four printings in the direction indicated by the arrow 10b, that is, in four passes. For example, the ink jet printer 10 may be configured to arrange the dots 42 shown in FIG. 5A, the dots 42 shown in FIG. 5B, the dots 42 shown in FIG. 7) may be realized by separate passes, that is, the dot 42 shown in FIG. 7 may be realized by a total of four passes. In general, an ink jet printer suppresses the occurrence of streaks by printing with a large number of passes such as 16 passes. However, by realizing the arrangement of the dots 42 shown in FIG. 7, the inkjet printer 10 can suppress the occurrence of stripe spots even when printing is performed with four or less passes.

  An example of a method for realizing the arrangement of the dots 42 shown in FIG. 7 in four passes will be described. First, the inkjet printer 10 realizes the arrangement of the dots 42 shown in FIG. 5A in one printing in the direction indicated by the arrow 10b, that is, in one pass. Next, the inkjet printer 10 transports the medium 90 by 1/1200 inch in the direction shown by the arrow 10c by the medium transport device 31, and then performs one printing in the direction shown by the arrow 10b, that is, one pass, as shown in FIG. The arrangement of the dots 42 shown in b) is realized. Next, the inkjet printer 10 conveys the medium 90 by 1/1200 inch in the direction shown by the arrow 10c by the medium conveying device 31, and then performs one printing in the direction shown by the arrow 10b, that is, one pass, as shown in FIG. The arrangement of the dots 42 shown in a) is realized. Next, the inkjet printer 10 conveys the medium 90 by 1/1200 inch in the direction shown by the arrow 10c by the medium conveying device 31, and then performs one printing in the direction shown by the arrow 10b, that is, one pass, as shown in FIG. The arrangement of the dots 42 shown in b) is realized. Through the above steps, the inkjet printer 10 can realize the arrangement of the dots 42 shown in FIG. 7 in four passes. When the arrangement of the dots 42 shown in FIG. 7 is realized by the above method, the inkjet head unit may be provided with only one inkjet head.

  The arrangement of the dots 42 shown in FIG. 7 is an arrangement of the dots 42 having a resolution of 1200 dpi. However, the ink jet printer 10 may realize the dot arrangement of the present invention at a resolution other than 1200 dpi. For example, the ink jet printer 10 may realize the dot arrangement of the present invention at any resolution of 600 dpi or more. In particular, it is preferable that the ink jet printer 10 realizes the dot arrangement of the present invention at a high resolution exceeding 1200 dpi. The ink jet printer 10 may realize the dot arrangement of the present invention with a high resolution in which the diameter of the dots 42 becomes short, such as 60 μm, and the height in which the diameter of the dots 42 becomes very short, such as 30 μm. It is preferable to realize the dot arrangement of the present invention at a resolution.

  When printing an image in which dots do not contact each other, such as printing of light-colored characters and low-resolution printing, the inkjet printer 10 may apply the conventional dot arrangement instead of the dot arrangement of the present invention. .

  In the present embodiment, the inkjet printer 10 includes a black inkjet head 21, yellow, magenta, and cyan inkjet head units 22 to 24 as primary colors, and red, green, and blue inkjet heads as secondary colors. Units 25 to 27 are provided. However, the inkjet printer 10 does not have to include the inkjet head units 25 to 27 for the secondary colors red, green, and blue.

  In the present embodiment, the inkjet printer 10 uses the arrowheads to indicate the primary color yellow, magenta, and cyan inkjet head units 22 to 24 and the secondary color red, green, and blue inkjet head units 25 to 27. They are displaced in the direction shown by 10c. The inkjet printer 10 may be mounted on the carriage 13 with the tertiary color inkjet head unit shifted from the inkjet head units 21 to 27 in the direction indicated by the arrow 10c. In addition, the inkjet printer 10 may arrange the inkjet head units without shifting in the direction indicated by the arrow 10c.

  In the present embodiment, the ink jet printer 10 moves the medium 90 in the direction indicated by the arrow 10c with respect to the ink jet head units 21 to 27 by transporting the medium 90 with respect to the platen 11 in the direction indicated by the arrow 10c. ing. However, the inkjet printer 10 extends the platen 11 in the sub-scanning direction from that shown in FIG. 1 and moves the carriage 13 with respect to the platen 11 in the direction indicated by the arrow 10c. You may move 21-27 in the direction shown by arrow 10c.

  In the present embodiment, the inkjet printer 10 is a serial inkjet printer. However, the dot arrangement of the present invention can be applied to an inkjet printer of a system other than the serial system. For example, the dot arrangement of the present invention may be applied to a line head type inkjet printer.

  The dot arrangement of the present invention is applicable to various printings. For example, the dot arrangement of the present invention can be applied to digital printing such as flexo, gravure, and offset, textile printing, and 3D printing. The arrangement of the dots of the present invention is less likely to cause streaking, and therefore is less likely to cause moire when applied to textile printing.

10 Inkjet printer 10b Arrow (arrow indicating first direction or second direction)
10c arrow (arrow indicating first direction or second direction)
37a printing means 42 dots 51 grid point group 51a grid point 52 grid point group 52a grid point 90 medium

Claims (6)

A printing unit that executes printing on the medium by discharging ink toward the medium,
The printing means,
A pair of opposite sides extending in a first direction and each having a first length, and a pair of opposite sides extending in a second direction orthogonal to the first direction and each having a second length A first grid point group, which is a group of grid points of a grid formed by a plurality of rectangles formed by the opposite sides of
A pair of opposite sides extending in the first direction and each having the first length, and a pair of opposite sides extending in the second direction and each having the second length. A group of grid points of a grid formed by a plurality of rectangles, wherein the grid points are shifted from the first grid point group in each of the first direction and the second direction. An ink jet printer, wherein ink dots are formed on the medium at the positions of and.   The first lattice point group and the second lattice point group are shifted from each other by a half of the first length in the first direction, and the second lattice point group is shifted in the second direction. The ink jet printer according to claim 1, wherein the ink jet printers are shifted from each other by a half of the second length.   The inkjet printer according to claim 1, wherein the first length and the second length are equal to each other.   The inkjet printer according to claim 1, wherein the printing unit forms the dot having a diameter equal to the first length on the medium. The ink is
UV curable ink,
Latex ink,
UV instant drying ink,
An ink that solidifies with a flocculant,
The ink jet printer according to any one of claims 1 to 4, wherein the ink is at least one of an ink which is thickened and gelled by a thixotropy phenomenon. A printing step of performing printing on the medium by ejecting ink toward the medium,
The printing step includes:
A pair of opposite sides extending in a first direction and each having a first length, and a pair of opposite sides extending in a second direction orthogonal to the first direction and each having a second length A first grid point group, which is a group of grid points of a grid formed by a plurality of rectangles formed by the opposite sides of
A pair of opposite sides extending in the first direction and each having the first length, and a pair of opposite sides extending in the second direction and each having the second length. A group of grid points of a grid formed by a plurality of rectangles, wherein the grid points are shifted from the first grid point group in each of the first direction and the second direction. Forming a dot of ink on the medium at the positions of and.

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