Printing apparatus and printing method

Abstract

In printing devices that use liquid ejection heads, image inconsistencies may occur due to differences in the time it takes for liquid droplets to land on the recording medium. [Solution] The printing apparatus comprises a print head having a first nozzle row including a first nozzle that ejects a liquid of a predetermined color, a second nozzle row including a second nozzle, and a third nozzle row including a third nozzle, wherein the first nozzle, the second nozzle, and the third nozzle each form a first raster line, a second raster line, and a third raster line, respectively, and the first distance between the first nozzle and the third nozzle along the transport direction is 1.5 or less when the second distance between the first nozzle and the second nozzle along the transport direction is set to 1, and the print dot diameter d of the impact dots formed by ejecting the liquid from the first nozzle has the relationship d ≥ 1.5 × L.

Description

[Technical Field]

[0001] This disclosure relates to a printing apparatus and a printing method. [Background technology]

[0002] A liquid ejection head having multiple nozzles for ejecting droplets is known. The liquid ejection head described in Patent Document 1 is composed of multiple head modules. Each head module is provided with multiple nozzle rows. Each nozzle row includes multiple nozzles arranged along a direction that is obliquely inclined with respect to the direction of movement of the recording medium. The multiple nozzle rows are arranged in a direction that intersects the direction of movement. Adjacent dots are formed by a nozzle included in one nozzle row within the multiple nozzle rows and a nozzle included in a nozzle row adjacent to that nozzle row. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2012-139987 [Overview of the project] [Problems that the invention aims to solve]

[0004] In a printing apparatus that uses a liquid ejection head consisting of a nozzle row including multiple nozzles arranged in a direction that is oblique to the direction of movement of the recording medium, image unevenness may occur due to differences in the time it takes for the liquid droplets to land on the recording medium. [Means for solving the problem]

[0005] The printing apparatus of the present disclosure comprises a print head having a first nozzle row in which a plurality of nozzles, including a first nozzle for discharging a liquid of a predetermined color, are arranged along an inclined direction that is inclined with respect to the transport direction of the printing medium; a second nozzle row in which a plurality of the nozzles, including a second nozzle for discharging the liquid of the predetermined color, are arranged along the inclined direction and are provided in an orthogonal direction perpendicular to the transport direction with respect to the first nozzle row; and a third nozzle row in which a plurality of the nozzles, including a third nozzle for discharging the liquid of the predetermined color, are arranged along the inclined direction and are provided in the opposite direction to the orthogonal direction with respect to the first nozzle row. The first nozzle forms a first raster line, the second nozzle forms a second raster line adjacent to the first raster line, and the third nozzle forms a third raster line adjacent to the first raster line. The first distance between the first nozzle and the third nozzle along the transport direction is 1.5 or less, when the second distance between the first nozzle and the second nozzle along the transport direction is 1. The print dot diameter d of the impact dots formed by discharging the liquid from the first nozzle has the following relationship. d≧1.5×L Here, L is the diagonal length of the recording resolution grid.

[0006] The printing method of this disclosure comprises a print head having a first nozzle row in which a plurality of nozzles, including a first nozzle for discharging a liquid of a predetermined color, are arranged along an inclined direction that is inclined with respect to the transport direction of the printing medium; a second nozzle row in which a plurality of nozzles, including a second nozzle for discharging the liquid of the predetermined color, are arranged along the inclined direction and are provided on one of the orthogonal directions perpendicular to the transport direction relative to the first nozzle row; and a third nozzle row in which a plurality of nozzles, including a third nozzle for discharging the liquid of the predetermined color, are arranged along the inclined direction and are provided on the other orthogonal direction relative to the first nozzle row. A printing method for a printing apparatus comprising: a first nozzle forming a first raster line; a second nozzle forming a second raster line adjacent to the first raster line; a third nozzle forming a third raster line adjacent to the first raster line; a first distance between the first nozzle and the third nozzle along the transport direction being 1.5 or less when the second distance between the first nozzle and the second nozzle along the transport direction is set to 1; and by discharging the liquid from the first nozzle, impact dots with the following relationship are formed. d≧1.5×L Here, L is the diagonal length of the recording resolution grid. [Brief explanation of the drawing]

[0007] [Figure 1] A diagram showing the external configuration of a liquid dispensing device. [Figure 2] A diagram showing the schematic configuration of a liquid dispensing device. [Figure 3] A diagram showing the schematic configuration of a liquid dispensing head. [Figure 4] A diagram showing the schematic configuration of the head chip. [Figure 5] A diagram showing the relationship between the raster line and the discharge nozzle. [Figure 6] A diagram showing the relationship between the raster line and the discharge nozzle. [Figure 7] A diagram showing the relationship between the raster line and the head tip. [Figure 8] A schematic diagram illustrating the relationship between print dots and resolution pitch. [Figure 9] A diagram showing the relationship between the grid diagonal and the print dot diameter. [Figure 10] A diagram showing the relationship between print duty cycle and brightness difference. [Figure 11] A diagram showing the schematic configuration of a liquid dispensing head. [Figure 12] A diagram showing the schematic configuration of the head chip. [Figure 13] A diagram showing the relationship between the raster line and the discharge nozzle. [Figure 14] A diagram showing the relationship between the raster line and the discharge nozzle. [Modes for carrying out the invention]

[0008] Figure 1 shows the external configuration of the liquid ejection device 11. The liquid ejection device 11 has a reading function for reading originals, a copying function for copying originals, and a printing function for printing print data. The liquid ejection device 11 is an inkjet printer that prints images by ejecting ink onto a medium M. Ink corresponds to an example of a liquid. The liquid ejection device 11 has a housing 12. The housing 12 houses the various operating parts of the liquid ejection device 11. The liquid ejection device 11 includes an image reading unit 13, an automatic feeding unit 14, an operation unit 15, a printing unit 16, and a medium storage unit 18. The liquid ejection device 11 corresponds to an example of a printing device.

[0009] Several figures, including Figure 1, show a three-dimensional coordinate system. The Z-axis is perpendicular to the installation surface of the liquid dispensing device 11. The Y-axis is perpendicular to the X-axis and Z-axis. The Y-axis is along the transport direction T in which the medium M is transported at a position opposite the liquid dispensing head 22, which will be described later. The X-axis is perpendicular to the Y-axis and Z-axis. The X-axis is along the orthogonal direction C, which is perpendicular to the transport direction T.

[0010] The image reading unit 13 is mounted on top of the printing unit 16. The image reading unit 13 is configured to read images such as characters and photographs recorded on the original document. The image reading unit 13 reads the original document and generates reading data.

[0011] The automatic document feeding unit 14 is configured to feed documents toward the image reading unit 13. The automatic document feeding unit 14 is positioned above the image reading unit 13. One or more documents are placed on the automatic document feeding unit 14. The automatic document feeding unit 14 feeds the placed documents toward the image reading unit 13 one by one.

[0012] The control unit 15 receives various input operations performed when the user gives instructions to the liquid dispensing device 11. The control unit 15 includes a display panel, operation buttons, etc. The display panel is composed of a liquid crystal display, an organic EL (Electro Luminescence) display, etc. The display panel may also have a touch input function.

[0013] The printing unit 16 prints an image onto a medium M. Medium M corresponds to an example of a printing medium. The printing unit 16 is located below the image reading unit 13. The printing unit 16 copies the original based on the reading data generated by the image reading unit 13. The printing unit 16 prints an image onto the medium M based on print data received from an external device or the like. The printing unit 16 has a mounting section 17.

[0014] The mounting section 17 places the medium M printed by the printing section 16 on it. The mounting section 17 has a mounting surface 17A. The mounting surface 17A is provided on the upper surface of the printing section 16.

[0015] The media storage section 18 houses the media M to be printed by the printing section 16. The media storage section 18 is located below the printing section 16. The media storage section 18 is configured to be retractable from the housing 12. The liquid dispensing device 11 includes one or more media storage sections 18. The liquid dispensing device 11 shown in Figure 1 includes four media storage sections 18. The four media storage sections 18 are located below the printing section 16 along the Z-axis.

[0016] Figure 2 shows the schematic configuration of the liquid dispensing device 11. Figure 2 shows the schematic configuration of the printing unit 16 and one media storage unit 18 of the liquid dispensing device 11. Figure 2 shows the control unit 100 provided in the liquid dispensing device 11. Figure 2 shows the liquid dispensing device 11 with the image reading unit 13 omitted. Figure 2 shows the configuration inside the housing 12 of the liquid dispensing device 11. The printing unit 16 includes a head unit 20, a transport unit 30, a maintenance unit 40, and a waste liquid container 50. The media storage unit 18 includes an edge guide 18A and a size sensor 18B.

[0017] The head unit 20 ejects one or more colors of ink onto the medium M. The head unit 20 includes a support section 21 and a liquid ejection head 22.

[0018] The support section 21 supports the liquid discharge head 22 at a position above the liquid discharge head 22. The support section 21 also supports the liquid discharge head 22 at a position facing the conveyed medium M.

[0019] The liquid ejection head 22 ejects ink facing the medium M. The liquid ejection head 22 corresponds to an example of a print head. The liquid ejection head 22 extends in a direction C perpendicular to the facing medium M. The direction C is perpendicular or approximately perpendicular to the transport direction T in which the facing medium M is transported. The liquid ejection head 22 has a plurality of ejection nozzles 23 on the ejection surface 22s facing the medium M. The liquid ejection head 22 is a line head having a number of ejection nozzles 23 capable of simultaneously ejecting ink over the entire width of the medium M in the direction C perpendicular to the medium M. The liquid ejection device 11 performs line printing by ejecting ink from a plurality of ejection nozzles 23 located facing the entire width of the medium M toward the transported medium M. The liquid ejection head 22 is connected to the supply path 27.

[0020] The ejection nozzle 23 is an opening provided on the ejection surface 22s of the liquid ejection head 22 that faces the medium M. The ejection nozzle 23 corresponds to an example of a nozzle. The ejection nozzle 23 ejects ink into the medium M in droplet form. The arrangement of multiple ejection nozzles 23 will be described later.

[0021] The supply path 27 is an ink channel that supplies ink to the liquid ejection head 22. The liquid ejection head 22 is connected to one or more supply paths 27. When the liquid ejection head 22 is connected to multiple supply paths 27, each supply path 27 supplies ink of a different color to the liquid ejection head 22. The supply paths 27 are connected to the liquid container 28.

[0022] The liquid container 28 holds ink. The liquid container 28 is, for example, an ink cartridge. The liquid container 28 may also be a liquid tank into which ink is injected from a liquid container such as a bottle. The liquid ejection device 11 comprises one or more liquid containers 28. When the liquid ejection device 11 comprises multiple liquid containers 28, each liquid container 28 may, for example, hold ink of a different color. The liquid ejection device 11 shown in Figure 2 comprises four liquid containers 28. The four liquid containers 28 each hold black ink, yellow ink, cyan ink, and magenta ink, respectively. The number of liquid containers 28 can be set as appropriate. The ink contained in the liquid containers 28 is supplied to the liquid ejection head 22 via a supply path 27. The liquid containers 28 are held in a holder 29.

[0023] The holder 29 holds one or more liquid containers 28. When the liquid container 28 is, for example, an ink cartridge, the holder 29 holds the ink cartridge in a removable manner. When the liquid container 28 is installed in the holder 29, the liquid container 28 connects to the supply path 27.

[0024] The transport unit 30 transports the medium M within the transport path TR. The transport unit 30 transports the medium M from the medium storage unit 18 towards the mounting unit 17. The transport unit 30 includes a feeding roller 31, a separation roller 32, a transport roller 33, and a transport belt 34.

[0025] The feeding roller 31 picks up the topmost medium M from among the multiple mediums M stacked in the medium storage section 18 and feeds it into the transport path TR. The feeding roller 31 is positioned above the medium storage section 18.

[0026] The separation roller 32 separates the media M being transported into the transport path TR into individual sheets. When the feeding roller 31 feeds multiple media M into the transport path TR, the separation roller 32 separates the media M being transported into the transport path TR into a single sheet.

[0027] The conveyor rollers 33 transmit driving force to the medium M in the conveyor path TR and convey the medium M. Multiple conveyor rollers 33 are provided in the conveyor path TR. Multiple conveyor rollers 33 are arranged along the conveyor path TR.

[0028] The conveyor belt 34 is positioned at a support location opposite the liquid discharge head 22. The conveyor belt 34 supports the medium M at the support location and conveys the medium M in the conveying direction T. The conveyor belt 34 is wrapped around the first roller 35 and the second roller 36. The conveyor belt 34 is rotated by the belt movement mechanism 37.

[0029] The first roller 35 and the second roller 36 rotatably support the conveyor belt 34. Either the first roller 35 or the second roller 36 transmits rotational driving force to the conveyor belt 34, causing it to rotate. The first roller 35 and the second roller 36 apply tension to the conveyor belt 34.

[0030] The belt movement mechanism 37 rotates the conveyor belt 34 using the first roller 35 as a pivot point. The belt movement mechanism 37 moves the conveyor belt 34 to a support position shown by a solid line in Figure 2 and to a retracted position shown by a dashed line in Figure 2. The support position is the position where the conveyor belt 34 faces the liquid discharge head 22. In the support position, the conveyor belt 34 is supported at a position that creates a predetermined gap with respect to the liquid discharge head 22. The retracted position is the position where the conveyor belt 34 does not face the liquid discharge head 22.

[0031] The maintenance unit 40 performs maintenance operations on the liquid discharge head 22. The maintenance operations reduce discharge failures caused by clogging of the discharge nozzle 23 or adhesion of foreign matter. Maintenance operations include dry discharge, capping, and suction cleaning. The maintenance unit 40 includes a plurality of caps 41, a discharge mechanism 44, and a cap moving mechanism 45.

[0032] The cap 41 contacts the discharge surface 22s and covers the multiple discharge nozzles 23. The cap 41 moves by the cap movement mechanism 45 between a separated position shown by a solid line in Figure 2 and a capping position shown by a dashed line in Figure 2. The separated position is the position where the cap 41 and the discharge surface 22s do not come into contact. The capping position is the position where the cap 41 and the discharge surface 22s come into contact.

[0033] The discharge mechanism 44 discharges the ink in the cap 41 into the waste liquid container 50. For example, when the liquid discharge head 22 performs an empty discharge, the discharge mechanism 44 discharges the ink discharged to the cap 41 as waste liquid into the waste liquid container 50. The discharge mechanism 44 has a waste liquid flow path 42 and a pressure reducing unit 43.

[0034] The waste liquid channel 42 allows the ink inside the cap 41 to flow into the waste liquid container 50. The waste liquid channel 42 is a channel that connects the cap 41 and the waste liquid container 50.

[0035] The pressure reducing unit 43 reduces the pressure in the waste liquid passage 42. The pressure reducing unit 43 is installed in the middle of the waste liquid passage 42. The pressure reducing unit 43 operates, for example, when the maintenance unit 40 performs suction cleaning. The pressure reducing unit 43 operates when the discharge surface 22s and the cap 41 are in contact, thereby sucking the ink out of the discharge nozzle 23.

[0036] The cap moving mechanism 45 moves the cap 41 between a separated position and a capping position. The cap moving mechanism 45 is driven in conjunction with the belt moving mechanism 37. When the conveyor belt 34 moves to the retracted position, the cap moving mechanism 45 moves the cap 41 to the capping position. When the conveyor belt 34 moves to the support position, the cap moving mechanism 45 moves the cap 41 to the separated position.

[0037] The waste liquid container 50 contains the ink discharged from the cap 41. The waste liquid container 50 contains the ink that has flowed through the waste liquid channel 42 and the pressure reduction unit 43 as waste liquid. The waste liquid container 50 is positioned to the side of the media storage section 18, for example. The waste liquid container 50 is held in the waste liquid container holder 51.

[0038] The waste liquid container holder 51 detachably holds the waste liquid container 50. When the waste liquid container 50 is attached to the waste liquid container holder 51, it is connected to the waste liquid flow path 42. The waste liquid container 50 becomes capable of containing waste liquid.

[0039] The edge guide 18A provided in the media storage section 18 positions the side surface of the media M to be stored in the media storage section 18. The edge guide 18A is operated by the user when setting the media M in the media storage section 18.

[0040] The size sensor 18B detects the size of the medium M set in the medium storage section 18. For example, the size sensor 18B detects the size of the medium M based on the position of the edge guide 18A. The size sensor 18B is not limited to a configuration that detects the size of the medium M based on the position of the edge guide 18A. The size sensor 18B may be a contact sensor or a non-contact sensor.

[0041] The control unit 100 is a controller that controls the operation of the liquid dispensing device 11. The control unit 100 is, for example, a processor having a CPU (Central Processing Unit). The control unit 100 is composed of one or more processors. The control unit 100 operates as various functional units by executing a control program. The control unit 100 controls the image reading unit 13 to generate read data. The control unit 100 controls the printing unit 16 to print various images on the medium M based on the read data and print data. The control unit 100 may have a storage unit such as ROM (Read Only Memory) or RAM (Random Access Memory).

[0042] Figure 3 shows a schematic configuration of the liquid discharge head 22. Figure 3 shows a magnified view of a portion of the first liquid discharge head 22a, which is an example of the liquid discharge head 22. Figure 3 shows the first liquid discharge head 22a in a plan view from above along the Z axis. Figure 3 virtually shows the discharge nozzle row 123. The first liquid discharge head 22a has a plurality of head tips 24.

[0043] The head chip 24 has multiple ejection nozzles 23. The head chip 24 corresponds to an example of a head module. The multiple head chips 24 are arranged such that the multiple ejection nozzles 23 are positioned across the entire area of ​​the medium width along the orthogonal direction C of the medium M. The first liquid ejection head 22a shown in Figure 3 shows six head chips 24. The number of head chips 24 is set appropriately according to the print resolution.

[0044] Multiple ejection nozzles 23 provided on the head tip 24 are arranged in one or more ejection nozzle rows 123. The multiple ejection nozzles 23 included in the ejection nozzle row 123 are arranged along the nozzle arrangement direction ND. The nozzle arrangement direction ND is a direction inclined with respect to the transport direction T and the orthogonal direction C. The nozzle arrangement direction ND corresponds to an example of an inclined direction. The head tip 24 shown in Figure 3 has multiple ejection nozzles 23 arranged in the ejection nozzle row 123. The ejection nozzle row 123 is, for example, a black ink ejection nozzle row 123K.

[0045] Multiple black ink ejection nozzles 23K are arranged in the nozzle arrangement direction ND within the black ink ejection nozzle row 123K. Each of the multiple black ink ejection nozzles 23K ejects black ink onto the medium M.

[0046] The first liquid ejection head 22a shown in Figure 3 has, but is not limited to, a row of black ink ejection nozzles 123K. The first liquid ejection head 22a may also include a row of cyan ink ejection nozzles 123C, a row of magenta ink ejection nozzles 123M, and a row of yellow ink ejection nozzles 123Y. The row of cyan ink ejection nozzles 123C has a plurality of cyan ink ejection nozzles 23C that eject cyan ink. The row of magenta ink ejection nozzles 123M has a plurality of magenta ink ejection nozzles 23M that eject magenta ink. The row of yellow ink ejection nozzles 123Y has a plurality of yellow ink ejection nozzles 23Y that eject yellow ink. The first liquid ejection head 22a has at least one of the following: a row of black ink ejection nozzles 123K, a row of cyan ink ejection nozzles 123C, a row of magenta ink ejection nozzles 123M, and a row of yellow ink ejection nozzles 123Y.

[0047] Figure 4 shows a schematic configuration of the head tip 24. Figure 4 shows a magnified view of the head tip 24 included in the ejection surface 22s of the first liquid ejection head 22a shown in Figure 3. Figure 4 shows the black ink ejection nozzle row 123K included in the first liquid ejection head 22a shown in Figure 3. The black ink ejection nozzle row 123K has multiple black ink ejection nozzles 23K arranged along the nozzle arrangement direction ND. Figure 4 schematically shows the number and size of the black ink ejection nozzles 23K.

[0048] The black ink ejection nozzles 23K, which form the row of black ink ejection nozzles 123K, each eject black ink onto the medium M. Each of the multiple black ink ejection nozzles 23K ejects ink to an ejection position along the X-axis. The multiple black ink ejection nozzles 23K form a raster line RL at their respective ejection positions along the X-axis. The raster line RL is a printed image in which dots are arranged along the transport direction T.

[0049] Figure 5 shows the relationship between the raster line RL and the ejection nozzle 23. Figure 5 shows a portion of the raster line RL printable on the medium M and a portion of the ejection nozzle 23. The ejection nozzle 23 ejects black ink as an example. Black corresponds to an example of a predetermined color. Figure 5 shows the raster line RL and the ejection nozzle 23 in a plan view from above along the Z axis. Figure 5 virtually shows multiple rows of ejection nozzles 123. The arrangement and number of ejection nozzles 23 shown in Figure 5 are examples and are not limited to the configuration shown in Figure 5.

[0050] A raster line RL is a printed image that extends along the transport direction T. Multiple raster lines RL are formed adjacent to each other in the orthogonal direction C. Each of the multiple raster lines RL is formed by one ejection nozzle 23. Each of the multiple raster lines RL is formed with a raster line width RW. The number of multiple raster lines RL along the orthogonal direction C and the raster line width RW correspond to the resolution of the printed image printed on the medium M.

[0051] The discharge nozzle row 123 includes a plurality of discharge nozzles 23 arranged in the nozzle arrangement direction ND. The discharge nozzle row 123 extends along the nozzle arrangement direction ND. Figure 5 shows the nth discharge nozzle row 123 as a plurality of discharge nozzle rows 123. n , the (n-1) discharge nozzle row 123 n-1 , the (n+1)th discharge nozzle row 123 n+1 This demonstrates that n is any integer greater than or equal to 3.

[0052] nth discharge nozzle row 123 n The p discharge nozzle 23 p, the (p + 2)-th ejection nozzle 23 p+2 , the (p + 4)-th ejection nozzle 23 p+4 , and the (p - 2)-th ejection nozzle 23 p-2 are included. p is an arbitrary integer of 13 or more. The p-th ejection nozzle 23 p , the (p + 2)-th ejection nozzle 23 p+2 , the (p + 4)-th ejection nozzle 23 p+4 , and the (p - 2)-th ejection nozzle 23 p-2 are an example of the ejection nozzle 23. The n-th ejection nozzle row 123 n corresponds to an example of the first nozzle row.

[0053] The p-th ejection nozzle 23 p forms the p-th raster line RL by continuously ejecting ink onto the medium M p . The p-th ejection nozzle 23 p corresponds to an example of the first nozzle. The p-th raster line RL p corresponds to an example of the first raster line.

[0054] The (p + 2)-th ejection nozzle 23 p+2 is arranged at a position adjacent to the p-th ejection nozzle 23 p in the orthogonal direction C to the p-th ejection nozzle 23 p . The (p + 2)-th ejection nozzle 23 p+2 forms the (p + 2)-th raster line RL by continuously ejecting ink onto the medium M p+2 . The (p +​​​​​​​​​​​​​​​​​​​​​It is formed at a position C perpendicular to the direction.

[0056] No. p-2 discharge nozzle 23 p-2 The p discharge nozzle 23 p In the opposite direction to the orthogonal direction C, the p discharge nozzle 23 p It is positioned adjacent to the p-2 discharge nozzle 23. p-2 This involves continuously ejecting ink onto the medium M, thereby creating the p-2 raster line RL p-2 Forms the p-2 raster line RL. p-2 This is the p-th raster line RL p It is formed in the opposite direction to the orthogonal direction C.

[0057] Discharge nozzle row 123 (the (n+1)th) n+1 This is the nth discharge nozzle row 123 n It is provided in the direction C orthogonal to the direction. The (n+1)th discharge nozzle row 123 n+1 This corresponds to an example of the second nozzle row. The (n+1)th discharge nozzle row 123 n+1 This is the p+1 discharge nozzle 23 p+1 , p+3 discharge nozzle 23 p+3 , and p+5 discharge nozzle 23 p+5 Includes the p+1 discharge nozzle 23. p+1 , p+3 discharge nozzle 23 p+3 , and p+5 discharge nozzle 23 p+5 This is an example of a discharge nozzle 23.

[0058] No. p+1 Discharge Nozzle 23 p+1 The p discharge nozzle 23 p It is provided in the direction C perpendicular to the direction. The p+1 discharge nozzle 23 p+1 This involves continuously ejecting ink onto the medium M, thereby creating the p+1 raster line RL. p+1 Forms the p+1 discharge nozzle 23. p+1 This corresponds to an example of the second nozzle. The p+1 raster line RL p+1 This corresponds to an example of the second raster line. The p+1th raster line RL p+1 This is the p-th raster line RL p In the direction C perpendicular to this, the p-th raster line RLp It is formed in a location adjacent to it.

[0059] No. p+3 discharge nozzle 23 p+3 This is the p+1 discharge nozzle 23 p+1 In the orthogonal direction C, the p+1 discharge nozzle 23 p+1 It is positioned adjacent to the p+3 discharge nozzle 23. p+3 This is achieved by continuously ejecting ink onto the medium M, thereby creating the p+3 raster line RL. p+3 Forms the p+3 raster line RL. p+3 This is the p+2 raster line RL p+2 In the orthogonal direction C, the p+2 raster line RL p+2 It is formed in a location adjacent to it.

[0060] No. p+5 discharge nozzle 23 p+5 This is the p+3 discharge nozzle 23 p+3 In the orthogonal direction C, the p+3 discharge nozzle 23 p+3 It is positioned adjacent to the p+5 discharge nozzle 23. p+5 This is achieved by continuously ejecting ink onto the medium M, thereby creating the p+5 raster line RL. p+5 Forms the p+5th raster line RL. p+5 This is the p+4th raster line RL p+4 In the orthogonal direction C, the p+4th raster line RL p+4 It is formed in a location adjacent to it.

[0061] Discharge nozzle row 123 (n-1) n-1 This is the nth discharge nozzle row 123 n It is provided in the opposite direction to the orthogonal direction C. n-1st discharge nozzle row 123 n-1 This corresponds to an example of the third nozzle row. The (n-1) discharge nozzle row 123 n-1 This is the p-1 discharge nozzle 23 p-1 , and p-3 discharge nozzle 23 p-3 Includes the p-1 discharge nozzle 23. p-1 , and p-3 discharge nozzle 23 p-3 This is an example of a discharge nozzle 23.

[0062] The (p - 1)-th ejection nozzle 23 p-1 is provided in the reverse direction of the orthogonal direction C with respect to the p-th ejection nozzle 23 p . The (p - 1)-th ejection nozzle 23 p-1 forms the (p - 1)-th raster line RL p-1 by continuously ejecting ink onto the medium M. The (p - 1)-th ejection nozzle 23 p-1 corresponds to an example of the third nozzle. The (p - 1)-th raster line RL p-1 corresponds to an example of the third raster line. The (p - 1)-th raster line RL p-1 is formed at a position adjacent to the p-th raster line RL p in the reverse direction of the orthogonal direction C with respect to the p-th raster line RL p .

[0063] The (p - 3)-th ejection nozzle 23 p-3 is arranged at a position adjacent to the (p - 1)-th ejection nozzle 23 p-1 in the reverse direction of the orthogonal direction C with respect to the (p - 1)-th ejection nozzle 23 p-1 . The (p - 3)-th ejection nozzle 23 p-3 forms the (p - 3)-th raster line RL p-3 by continuously ejecting ink onto the medium M. The (p - 3)-th raster line RL p-3 is formed at a position adjacent to the (p - 2)-th raster line RL p-2 in the reverse direction of the orthogonal direction C with respect to the (p - 2)-th raster line RL p-2 .

[0064] The n-th ejection nozzle row 123 n includes the p-th ejection nozzle 23 p+1 that forms the p-th raster line RL p+1 formed by the (p + 1)-th ejection nozzle 23 p-1 and the (p - 1)-th raster line RL p-1 formed by the (p - 1)-th ejection nozzle 23 p and adjacent to the p-th raster line RL p . The (p + 1)-th ejection nozzle 23 p+1 is included in the (n + 1)-th ejection nozzle row 123 n+1 . The (p - 1)-th ejection nozzle 23p-1 This is the (n-1) discharge nozzle row 123 n-1 It is included in.

[0065] nth discharge nozzle row 123 n This is the p+1 discharge nozzle 23 p+1 The p+1 raster line RL is formed by this. p+1 , and p+3 discharge nozzle 23 p+3 The p+3 raster line RL is formed by this. p+3 and the adjacent p+2 raster line RL p+2 The p+2 discharge nozzle 23 forms p+2 Includes the p+1 discharge nozzle 23. p+1 and p+3 discharge nozzle 23 p+3 This is the (n+1)th discharge nozzle row 123 n+1 It is included in the nth discharge nozzle row 123. n Some of the multiple discharge nozzles 23 included are in the (n+1)th discharge nozzle row 123 n+1 The two discharge nozzles 23 included in form a raster line RL and an adjacent raster line RL.

[0066] nth discharge nozzle row 123 n This is the p-1 discharge nozzle 23 p-1 The p-1 raster line RL is formed by p-1 , and p-3 discharge nozzle 23 p-3 The p-3 raster line RL is formed by p-3 adjacent to the p-2 raster line RL p-2 The p-2 discharge nozzle 23 forms p-2 Includes the p-1 discharge nozzle 23. p-1 and p-3 discharge nozzle 23 p-3 This is the (n-1) discharge nozzle row 123 n-1 It is included in the nth discharge nozzle row 123 n Some of the multiple discharge nozzles 23 included are in the (n-1) discharge nozzle row 123 n-1 The two discharge nozzles 23 included in form a raster line RL and an adjacent raster line RL.

[0067] The first liquid discharge head 22a forms adjacent raster lines RL using discharge nozzles 23 included in adjacent discharge nozzle rows 123. When the first liquid discharge head 22a forms adjacent raster lines RL using discharge nozzles 23 included in adjacent discharge nozzle rows 123, the first liquid discharge head 22a can be miniaturized.

[0068] Each nozzle row 123 shown in Figure 5 includes a blank nozzle 23b. The blank nozzle 23b is an example of a nozzle 23. The blank nozzle 23b does not eject ink. (n+1) nozzle row 123 n+1 The blank discharge nozzle 23b included is for the p-1 raster line RL p-1 It is positioned in a location where it can form. The p-1 raster line RL p-1 This is the (n-1) discharge nozzle row 123 n-1 The p-1 discharge nozzle 23 included p-1 Formed by the (n+1)th discharge nozzle row 123 n+1 The blank discharge nozzle 23b included in the assembly corresponds to an example of a surplus nozzle. The blank discharge nozzle 23b is positioned to form a raster line RL at a location that coincides with or approximately coincides with the raster line RL formed by the other discharge nozzles 23. In the event that a manufacturing error occurs during the production of the liquid discharge head 22, such as a deviation in the orthogonal direction C or the opposite direction of orthogonal direction C, the liquid may not be able to be discharged, resulting in white streaky concentration unevenness. In such cases, using a blank discharge nozzle can suppress white streaky concentration unevenness.

[0069] In Figure 5, the p discharge nozzle 23 p The ejection nozzle 23 that ejects ink in the opposite direction to the perpendicular direction C is the p-1 ejection nozzle 23 p-1 This is the p discharge nozzle 23. p and the p-1 discharge nozzle 23 p-1 The distance along the transport direction T between the first p discharge nozzle 23 p and the (n+1)th discharge nozzle row 123 n+1The distance between the blank discharge nozzle 23b and the p discharge nozzle 23 is shorter than the distance along the transport direction T. p and the p-1 discharge nozzle 23 p-1 The ink ejection time interval between the first p ejection nozzle 23 p and the (n+1)th discharge nozzle row 123 n+1 This is shorter than the ink ejection time interval between the blank ejection nozzle 23b included in the system. This suppresses the degradation of image quality caused by a longer ejection time interval.

[0070] (n+1) Discharge nozzle row 123 n+1 This is the p-1 raster line RL p-1 It is preferable to have a blank discharge nozzle 23b capable of forming a blank. Image quality degradation due to ink ejection time intervals is suppressed.

[0071] Figure 6 shows the relationship between the raster line RL and the discharge nozzle 23. Figure 6 shows the p-th discharge nozzle 23 shown in Figure 5. p The vicinity of is shown in magnified view. Figure 6 shows the distance between the first discharge nozzle NL1 and the distance between the second discharge nozzle NL2.

[0072] The distance NL1 between the first discharge nozzles is along the transport direction T of the p discharge nozzle 23 p and the p+1 discharge nozzle 23 p+1 This is the distance between the first discharge nozzles. The distance NL1 between the first discharge nozzles is the distance between the first p discharge nozzles 23 when printing a line image along the orthogonal direction C. p Printed dots 200 and the p+1 ejection nozzle 23 are ejected by p+1 This corresponds to the ejection time difference of the 200 print dots ejected. The ejection time difference corresponds to the ink impact time difference. The first ejection nozzle distance NL1 corresponds to an example of the second distance.

[0073] The distance NL2 between the second discharge nozzles is along the transport direction T of the p discharge nozzle 23 p and the p-1 discharge nozzle 23 p-1 This is the distance between the two nozzles. The distance NL2 between the second discharge nozzles is the distance between the p discharge nozzles 23 when printing a line image along the orthogonal direction C.p Printed dots 200 and the p-1 ejection nozzle 23 are ejected by p-1 This corresponds to the ejection time difference of the 200 print dots ejected by the nozzle. The distance between the second ejection nozzles NL2 corresponds to an example of the first distance.

[0074] The distance between the first discharge nozzles NL1 and the distance between the second discharge nozzles NL2 are adjusted by the distance between adjacent discharge nozzles 23 in the nozzle arrangement direction ND, the inclination angle of the nozzle arrangement direction ND with respect to the transport direction T, etc. (p discharge nozzle 23) p and the p-1 discharge nozzle 23 p-1 When the two nozzles are provided on different head tips 24, the distance NL2 between the second discharge nozzles varies depending on the position of the two head tips 24.

[0075] The distance between the second discharge nozzles NL2 is adjusted to 1.5 or less, with the distance between the first discharge nozzles NL1 being set to 1. By adjusting the distance between the second discharge nozzles NL2 to 1.5 times or less of the distance between the first discharge nozzles NL1, the p-1 discharge nozzle 23 p-1 and the p+1 discharge nozzle 23 p+1 Image degradation due to the difference in ejection time between the two points is reduced. "Image quality degradation due to the difference in ejection time" refers to the fact that, for example, the amount of ink dot bleeding or the degree of penetration into the medium differs depending on the time elapsed after impact, which can lead to differences in color and cause image quality degradation such as uneven density.

[0076] Figure 7 shows the relationship between the raster line RL and the head tip 24. Figure 7 shows a portion of the raster line RL printable on the medium M and a portion of the head tip 24. Figure 7 shows the raster line RL and the head tip 24 in a plan view from above along the Z axis. Figure 7 shows a virtual center line Vc, a first virtual line VL1, and a second virtual line VL2. Figure 7 virtually shows multiple ejection nozzle rows 123, in which multiple ejection nozzles 23 are arranged along the nozzle arrangement direction ND. The ejection nozzles 23 eject black ink as an example. The arrangement and number of ejection nozzles 23 shown in Figure 7 are examples and are not limited to the configuration shown in Figure 7.

[0077] The first liquid dispensing head 22a includes a plurality of head tips 24 arranged along the orthogonal direction C. Figure 7 shows the q-th head tip 24 included in the plurality of head tips 24. q , and q-1 head tip 24 q-1 This shows that q is any integer greater than or equal to 2.

[0078] Q Head Tip 24 q This is the nth discharge nozzle row 123 n , and n discharge nozzle row 123 n The (n+1)th discharge nozzle row 123 is arranged in the orthogonal direction C. n+1 It has the q head tip 24. q This corresponds to an example of the first head module.

[0079] Head tip #24 (Q-1) q-1 This is the q head tip 24 q It is positioned in the opposite direction to the orthogonal direction C. q-1 head tip 24 q-1 This is the (n-1) discharge nozzle row 123 n-1 , and n-1 discharge nozzle row 123 n-1 The (n-2) discharge nozzle row 123 is arranged in the opposite direction to the orthogonal direction C. n-2 It has the n-2nd discharge nozzle row 123 n-2 This includes the p-12 discharge nozzle 23 p-12 Multiple discharge nozzles 23, including the p-12 discharge nozzle 23, are arranged along the nozzle arrangement direction ND. p-12 This corresponds to an example of the fourth nozzle. n-2nd discharge nozzle row 123 n-2 This corresponds to an example of the fourth nozzle row. The q-1 head tip 24 ejects black ink. q-1 This corresponds to an example of a second head module.

[0080] Figure 7 shows the central point CP. The central point CP is located in the nth discharge nozzle row 123. nThis shows the centers of multiple discharge nozzles 23 along the nozzle arrangement direction ND. The center point CP corresponds to an example of the central position. The virtual center line Vc shown in Figure 7 is a virtual line along the transport direction T passing through the center point CP.

[0081] The first virtual line VL1 is in a direction C orthogonal to the virtual center line Vc, and the nth discharge nozzle row 123 is furthest from the virtual center line Vc. n This is a virtual line along the transport direction T passing through the discharge nozzle 23 included in the structure. Between the virtual center line Vc and the first virtual line VL1 is the nth discharge nozzle row 123. n The first nozzle row NG1 is included.

[0082] The first nozzle row NG1 is the nth discharge nozzle row 123 n This region includes a discharge nozzle 23 among a plurality of discharge nozzles 23 located in a direction C orthogonal to the center point CP. The first nozzle row NG1 corresponds to an example of the first part. The first nozzle row NG1, in a plan view from the transport direction T, is the (n+1)th discharge nozzle row 123 n+1 It overlaps with that.

[0083] The second virtual line VL2 is the nth discharge nozzle row 123, which is furthest from the virtual center line Vc, in the opposite direction to the orthogonal direction C, which is the other direction relative to the center point CP. n This is a virtual line along the transport direction T passing through the discharge nozzle 23 included in the structure. Between the virtual center line Vc and the second virtual line VL2 is the nth discharge nozzle row 123 n This includes the second nozzle row NG2.

[0084] The second nozzle row section NG2 is the nth discharge nozzle row 123 n This region includes a discharge nozzle 23 among the multiple discharge nozzles 23 contained therein, which is positioned in the opposite direction to the direction C orthogonal to the center point CP. The second nozzle row NG2 corresponds to an example of the second part. The second nozzle row NG2, in a plan view from the transport direction T, is the (n-1) discharge nozzle row 123 n-1 It overlaps with that.

[0085] nth discharge nozzle row 123 nHalf of this is a plan view from the transport direction T, and the (n+1)th discharge nozzle row 123 n+1 This overlaps with the nth discharge nozzle row 123 n Half of this is a plan view from the transport direction T, and the (n-1) discharge nozzle row 123 n-1 This overlaps with the other. By using this configuration, the head length of the first liquid discharge head 22a along the transport direction T can be kept short. This reduces the effects of transport errors and the risk of head friction due to the medium M.

[0086] (n+1) Discharge nozzle row 123 n+1 This is the nth discharge nozzle row 123 n The nth discharge nozzle row 123 is in a direction perpendicular to the direction C with respect to the center point CP along the nozzle arrangement direction ND. n The first nozzle row NG1 and the (n-1) discharge nozzle row 123 overlap in a plan view from the transport direction T. n-1 This is the nth discharge nozzle row 123, which is in the opposite direction to the direction C perpendicular to the center point CP. n It is preferable that the second nozzle row NG2 overlaps with the conveying direction T in a plan view. The head length of the first liquid discharge head 22a along the transport direction T is kept short. This reduces the effects of transport errors and the risk of head friction due to the medium M.

[0087] Figure 8 schematically shows the relationship between the print dot 200 and the resolution pitch. Figure 8 shows the resolution pitch at a given print resolution using grid lines GL. The grid line width GW between two grid lines GL corresponds to the raster line width RW. Figure 8 shows the grid lines GL, the print dot 200, the print dot diameter d, and the grid diagonal length L.

[0088] The grid diagonal L is the length of the diagonal of the grid G ​​enclosed by grid lines GL arranged along the transport direction T and grid lines GL arranged along the orthogonal direction C. The grid G ​​is determined by the print resolution. Grid G ​​corresponds to an example of a recording resolution grid. The grid diagonal L corresponds to an example of a diagonal length.

[0089] The printed dots 200 are dot images formed on the medium M when the ejection nozzle 23 ejects droplets of ink onto the medium M. The printed dots 200 correspond to an example of an impact dot. Figure 8 shows printed dots 200 with a printed dot diameter d. The printed dot diameter d represents the maximum dot diameter of the printed dots 200 when the ink ejection amount to a predetermined area is 20% or more, with the ink ejection amount when printing a solid image being 100%. Figure 8 shows the first printed dot 200a, the second printed dot 200b, the third printed dot 200c, and the fourth printed dot 200d as printed dots 200.

[0090] The first print dot 200a and the second print dot 200b are formed along the transport direction T. The first print dot 200a and the second print dot 200b are formed by ejecting ink from the same ejection nozzle 23. The first print dot 200a and the second print dot 200b are formed on a single raster line.

[0091] The third print dot 200c and the fourth print dot 200d are formed along the transport direction T. The third print dot 200c and the fourth print dot 200d are formed by ejecting ink from the same ejection nozzle 23. The third print dot 200c and the fourth print dot 200d are formed on a single raster line RL.

[0092] The ejection nozzle 23 that ejects the first print dot 200a forms a raster line RL adjacent to the raster line RL that can be formed by the ejection nozzle 23 that ejects the third print dot 200c. The first print dot 200a is, for example, formed by the p ejection nozzle 23 p When ejected, the third print dot 200c is ejected by the p+1 ejection nozzle 23 p+1 It is discharged.

[0093] The ratio of the print dot diameter d of the print dot 200 to the grid diagonal L affects the uniformity of the print image density printed on the medium M. By adjusting the ratio of the print dot diameter d of the print dot 200 to the grid diagonal L, density unevenness due to manufacturing errors in the first liquid discharge head 22a can be reduced.

[0094] Figure 9 shows the relationship between the grid diagonal L and the print dot diameter d. Figure 9 shows the reduction in error effect density when the print dot diameter d is changed while a constant inter-column error is present. Figure 9 shows the size of the grid diagonal L, the size and ratio of the print dot diameter d, and the evaluation results of the reduction in error effect density. The grid diagonal L is the length of the diagonal when the print resolution is 1200 × 1200 dpi. dpi is an abbreviation for dots per inch. The ratio is the value obtained by dividing the print dot diameter d by the grid diagonal L.

[0095] The error effect density reduction is an indicator of the degree of image density unevenness due to manufacturing errors in the first liquid ejection head 22a. Figure 9 shows an evaluation of the error effect density reduction based on the results in Figure 10. Manufacturing errors in the first liquid ejection head 22a are caused by manufacturing errors in the ejection nozzles 23 within the head tip 24, mounting position errors of the head tip 24, etc. When the manufacturing error of the first liquid ejection head 22a increases, the overlap ratio of printed dots increases, and the proportion of dots covering the medium decreases, so the density decreases in the areas where the overlap ratio increases. As a result, image density unevenness increases in the formed image. When image density unevenness increases, the error effect density reduction becomes larger. The error effect density reduction can be determined by measuring the image density unevenness when printing multiple adjacent raster lines RL with the printed dot diameter d shown in Figure 9 using multiple liquid ejection devices 11.

[0096] The error-affecting density reduction evaluation result "A" shown in Figure 9 indicates that, when the image density unevenness of each printed image printed by multiple liquid dispensing devices 11 was visually observed, no image density unevenness was observed in 90% or more of the printed images. The error-affecting density reduction evaluation result "B" indicates that image density unevenness was observed in less than 50% of the multiple printed images. The error-affecting density reduction evaluation result "C" indicates that image density unevenness was observed in 50% or more of the multiple printed images.

[0097] As shown in Figure 9, when the ratio of the printed dot diameter d to the grid diagonal L is 1.5 or greater, the reduction in density due to errors is hardly visible, and a printed image with little uniformity in image density is obtained. When the relationship between the grid diagonal L and the printed dot diameter d is given by equation (1), a printed image with little uniformity in image density is obtained. d≧1.5×L (1)

[0098] Figure 10 shows the relationship between print duty cycle and brightness difference. Figure 10 shows the brightness difference within a printed image when a print image is printed using a first liquid ejection head 22a with an inter-column error of 20 μm in the orthogonal direction C of the ejection nozzle 23. In this embodiment, brightness difference is used as a value that indicates the amount of decrease in density when an inter-column error occurs, compared to an ideal state where there is no inter-column error. Figure 10 shows the brightness difference for each output duty cycle. The print resolution of the printed image is 1200 × 1200 dpi, and the grid diagonal L is 30 μm. Figure 10 shows the results when the print dot diameter d is changed from 30 μm to 80 μm. Brightness difference is an example of an indicator of image density unevenness. The larger the brightness difference, the greater the image density unevenness.

[0099] As shown in Figure 10, the larger the print dot diameter d, the less uneven the image density becomes. When the print dot diameter d is 50 μm or larger, the brightness difference in each print duty cycle becomes 5% or less, and the unevenness of the image density becomes small. A printed image with less unevenness in image density can be obtained in the region where the grid diagonal L and the print dot diameter d have the relationship given by equation (1).

[0100] The liquid dispensing device 11 has a p dispensing nozzle 23 that dispenses black ink. p Multiple discharge nozzles 23, including the nth discharge nozzle row 123, are arranged along the nozzle arrangement direction ND, which is inclined with respect to the transport direction T of the medium M. n , nth discharge nozzle row 123 n The p+1 discharge nozzle 23 is located in a direction C perpendicular to the transport direction T and discharges black ink. p+1 Multiple discharge nozzles 23, including the n+1 discharge nozzle row 123, are arranged along the nozzle arrangement direction ND. n+1 , and n discharge nozzle row 123 n The p-1 discharge nozzle 23 is provided in the opposite direction to the orthogonal direction C and discharges black ink. p-1 Multiple discharge nozzles 23, including the (n-1) discharge nozzle row 123, are arranged along the nozzle arrangement direction ND. n-1 It comprises a first liquid discharge head 22a having a p discharge nozzle 23 p This is the p-th raster line RL p Forms the p+1 discharge nozzle 23. p+1 This is the p-th raster line RL p and the adjacent p+1 raster line RL p+1 Forms the p-1 discharge nozzle 23. p-1 This is the p-th raster line RL p adjacent to the p-1 raster line RL p-1 Forms the p-th discharge nozzle 23 along the transport direction T. p and the p-1 discharge nozzle 23 p-1 The distance NL2 between the second discharge nozzle and the second discharge nozzle 23 is along the transport direction T. p and the p+1 discharge nozzle 23 p+1 When the distance NL1 between the first discharge nozzles is set to 1, it is 1.5 or less. (P discharge nozzle 23) p The print dot diameter d of the print dot 200 formed by ejecting ink has the following relationship: d≧1.5×L (1) Here, L is the length of the diagonal of the grid G. This configuration suppresses differences in ink ejection time and image density unevenness caused by manufacturing errors in the first liquid ejection head 22a.

[0101] The first liquid discharge head 22a is connected to the nth discharge nozzle row 123 n , and n+1 discharge nozzle row 123 n+1 The q head tip 24 q and the (n-1) discharge nozzle row 123 n-1 The q-1 head tip 24 q-1 It is preferable that it includes the following. Q Head Tip 24 q and the q-1 head tip 24 q-1 Due to the arrangement, the nth discharge nozzle row 123 n and the (n-1) discharge nozzle row 123 n-1 The placement error between them may become large. The print dot diameter d has the relationship given by equation (1), so the q head tip 24 q and the q-1 head tip 24 q-1 Image density variations caused by the arrangement of elements are suppressed.

[0102] Head tip #24 (Q-1) q-1 This is the p-12 ejection nozzle 23 that ejects black ink. p-12 Multiple discharge nozzles 23, including the (n-2) discharge nozzle row 123, are arranged along the nozzle arrangement direction ND. n-2 It is preferable that it has Since the head tip 24 is composed of two discharge nozzle rows 123, manufacturing errors between the two discharge nozzle rows 123 are reduced, and image density unevenness is suppressed.

[0103] The liquid dispensing device 11 has a p dispensing nozzle 23 that dispenses black ink. p Multiple discharge nozzles 23, including the nth discharge nozzle row 123, are arranged along the nozzle arrangement direction ND, which is inclined with respect to the transport direction T of the medium M. n , nth discharge nozzle row 123 n The p+1 discharge nozzle 23 is provided on one of the orthogonal directions C perpendicular to the transport direction T and discharges black ink. p+1Multiple discharge nozzles 23, including the n+1 discharge nozzle row 123, are arranged along the nozzle arrangement direction ND. n+1 , and n discharge nozzle row 123 n The p-1 discharge nozzle 23 is located on the other side in the direction C perpendicular to the other side and discharges black ink. p-1 Multiple discharge nozzles 23, including the (n-1) discharge nozzle row 123, are arranged along the nozzle arrangement direction ND. n-1 The liquid dispensing device 11 is equipped with a first liquid dispensing head 22a having a p dispensing nozzle 23 p This is the p-th raster line RL p Forms the p+1 discharge nozzle 23 p+1 This is the p-th raster line RL p and the adjacent p+1 raster line RL p+1 Forms the p-1 discharge nozzle 23 p-1 This is the p-th raster line RL p adjacent to the p-1 raster line RL p-1 Forms the p-th discharge nozzle 23 along the transport direction T. p and the p-1 discharge nozzle 23 p-1 The distance NL2 between the second discharge nozzle and the second discharge nozzle 23 is along the transport direction T. p and the p+1 discharge nozzle 23 p+1 When the distance NL1 between the first discharge nozzles is set to 1, it is 1.5 or less. (P discharge nozzle 23) p By ejecting ink from the device, a print dot 200 with a print dot diameter d having the following relationship is formed. d≧1.5×L (1) Here, L is the length of the diagonal of the grid G. Printing images using this method suppresses variations in ink ejection time and image density unevenness caused by manufacturing errors in the first liquid ejection head 22a.

[0104] Figure 11 shows a schematic configuration of the liquid discharge head 22. Figure 11 shows a magnified view of a portion of the second liquid discharge head 22b, which is an example of the liquid discharge head 22. Figure 11 shows the second liquid discharge head 22b in a plan view from above along the Z axis. Figure 11 virtually shows the discharge nozzle row 123. The second liquid discharge head 22b has a plurality of head tips 24.

[0105] The head tip 24 shown in Figure 11 has multiple ejection nozzles 23 arranged in two ejection nozzle rows 123. The two ejection nozzle rows 123 are the black ink ejection nozzle row 123K and the yellow ink ejection nozzle row 123Y.

[0106] The black ink discharge nozzle row 123K has multiple black ink discharge nozzles 23K arranged in the nozzle arrangement direction ND. The black ink discharge nozzles 23K are part of a group of discharge nozzles 23. Each of the multiple black ink discharge nozzles 23K discharges black ink onto the medium M. The black ink discharge nozzle row 123K is positioned downstream of the yellow ink discharge nozzle row 123Y in the transport direction T.

[0107] Multiple yellow ink ejection nozzles 23Y are arranged in the nozzle arrangement direction ND in the yellow ink ejection nozzle row 123Y. Each of the multiple yellow ink ejection nozzles 23Y is part of a group of ejection nozzles 23. Each of the multiple yellow ink ejection nozzles 23Y ejects yellow ink onto the medium M.

[0108] In the second liquid ejection head 22b shown in Figure 11, the yellow ink ejection nozzle row 123Y is arranged in a direction C perpendicular to the black ink ejection nozzle row 123K. The arrangement of the yellow ink ejection nozzle row 123Y and the black ink ejection nozzle row 123K is not limited to the arrangement shown in Figure 11, but can be set as appropriate. Furthermore, the nozzle rows included in the second liquid ejection head 22b are not limited to the black ink ejection nozzle row 123K and the yellow ink ejection nozzle row 123Y, but may also include cyan ink 123C and magenta ink 123M.

[0109] In Figure 11, the second liquid ejection head 22b has two sets of ejection nozzles 123 of two different colors arranged in the orthogonal direction C, but it is not limited to this configuration. For example, the second liquid ejection head 22b may have a configuration in which four colors are arranged along the orthogonal direction C: a row of black ink ejection nozzles 123K, a row of yellow ink ejection nozzles 123Y, a row of cyan ink 123C, and a row of magenta ink 123M.

[0110] Figure 12 shows a schematic configuration of the head tip 24. Figure 12 shows a magnified view of the head tip 24 included in the ejection surface 22s of the second liquid ejection head 22b shown in Figure 11. Figure 12 shows the black ink ejection nozzle row 123K and the yellow ink ejection nozzle row 123Y included in the second liquid ejection head 22b shown in Figure 11. The black ink ejection nozzle row 123K has multiple black ink ejection nozzles 23K arranged along the nozzle arrangement direction ND. The yellow ink ejection nozzle row 123Y has multiple yellow ink ejection nozzles 23Y arranged along the nozzle arrangement direction ND. Figure 12 schematically shows the number and size of the black ink ejection nozzles 23K, etc.

[0111] The black ink ejection nozzles 23K, which form the row of black ink ejection nozzles 123K, each eject black ink onto the medium M. Each of the multiple black ink ejection nozzles 23K ejects ink to an ejection position along the X-axis. The multiple black ink ejection nozzles 23K form a raster line RL at each ejection position along the X-axis.

[0112] The yellow ink ejection nozzles 23Y, which form the row of yellow ink ejection nozzles 123Y, each eject yellow ink onto the medium M. Each of the multiple yellow ink ejection nozzles 23Y ejects ink to an ejection position along the X-axis. The multiple yellow ink ejection nozzles 23Y form a raster line RL at each ejection position along the X-axis.

[0113] Figure 13 shows the relationship between the raster line RL and the ejection nozzle 23. Figure 13 shows a portion of the raster line RL printable on the medium M and a portion of the ejection nozzle 23. Figure 13 shows the raster line RL and the ejection nozzle 23 in a plan view from above along the Z axis. Figure 13 virtually shows multiple ejection nozzle rows 123 and multiple head tips 24. The arrangement and number of ejection nozzles 23 shown in Figure 13 are examples and are not limited to the configuration shown in Figure 13.

[0114] Figure 13 shows the v-th head tip 24 v , and v+1 head tip 24 v+1 This indicates that v is any integer greater than or equal to 1. The v-th head tip 24 v , and v+1 head tip 24 v+1 This is an example of a head tip 24. Head tip 24 v The r discharge nozzle row 123 r and discharge nozzle row 123 s The v+1 head tip 24 is formed. v+1 This includes the r+1 discharge nozzle row 123 r+1 and s+1 discharge nozzle row 123 s+1 A formation is created.

[0115] r-th discharge nozzle row 123 r This is a black ink ejection nozzle row 123K, which includes a black ink ejection nozzle 23K that ejects black ink. Black corresponds to an example of a predetermined color. The r-th ejection nozzle row 123 r It includes a plurality of ejection nozzles 23 arranged in the nozzle arrangement direction ND. The plurality of ejection nozzles 23 include the first ejection nozzle 23, which is a black ink ejection nozzle 23K. t This includes t, where t is any integer greater than or equal to 1. The r-th discharge nozzle row 123 r It extends along the nozzle arrangement direction ND. The r-th discharge nozzle row 123 r This corresponds to an example of the first nozzle row.

[0116] No. t discharge nozzle 23 t This is achieved by ejecting ink onto the medium M, thereby creating the raster line RL.t Forms the t-discharge nozzle 23 t This corresponds to an example of the first nozzle. The raster line RL t This corresponds to an example of the first raster line.

[0117] S-discharge nozzle row 123 s This is a yellow ink discharge nozzle row 123Y, which includes a yellow ink discharge nozzle 23Y that discharges yellow ink. The yellow color corresponds to an example of a color different from a predetermined color. The yellow ink corresponds to an example of a second liquid. The second discharge nozzle row 123 s It includes a plurality of ejection nozzles 23 arranged in the nozzle arrangement direction ND. The plurality of ejection nozzles 23 include the first ejection nozzle 23 which is a yellow ink ejection nozzle 23Y. u This includes u, where u is any integer greater than or equal to 1. The sth discharge nozzle row 123 s It extends along the nozzle arrangement direction ND. The s-th discharge nozzle row 123 s This is the r-th discharge nozzle row 123 r It is provided in the orthogonal direction C. The sth discharge nozzle row 123 s This corresponds to an example of a second liquid discharge nozzle array.

[0118] No. u discharge nozzle 23 u This is achieved by ejecting ink onto the medium M, thereby creating the first u raster line RL u Forms the first raster line RL. u This is the t-th raster line RL t It is formed in the same or approximately the same position as the u-raster line RL. u and the t-th raster line RL t These are formed in positions that overlap each other. (U-discharge nozzle 23) u This corresponds to an example of a second liquid dispensing nozzle.

[0119] V Head Tip 24 v This is the black ink ejection nozzle 23K, which is the first ejection nozzle 23 t The r discharge nozzle row 123 includes r And the yellow ink ejection nozzle 23Y is the s ejection nozzle row 123s It has the following: The black ink ejection nozzle 23K and the yellow ink ejection nozzle 23Y form a raster line RL at the same or substantially the same position. The v head tip 24 v By having a black ink ejection nozzle 23K and a yellow ink ejection nozzle 23Y, the head length of the second liquid ejection head 22b along the transport direction T can be kept shorter than in a configuration where one color nozzle row is arranged on a single head chip, while suppressing image quality degradation due to differences in ink ejection times.

[0120] Discharge nozzle row r+1 123 r+1 This is a row of black ink ejection nozzles 123K, which includes a black ink ejection nozzle 23K that ejects black ink. The r+1 ejection nozzle row 123 r+1 It includes a plurality of ejection nozzles 23 arranged in the nozzle arrangement direction ND. The plurality of ejection nozzles 23 include the t+1 ejection nozzle 23, which is the black ink ejection nozzle 23K. t+1 Includes the r+1 discharge nozzle row 123. r+1 It extends along the nozzle arrangement direction ND.

[0121] Discharge nozzle 23 (t+1) t+1 This is achieved by ejecting ink onto the medium M, thereby creating the t+1 raster line RL. t+1 Forms the t+1th raster line RL. t+1 This is the t-th raster line RL t It is adjacent to the t+1 discharge nozzle 23. t+1 The t-discharge nozzle 23 t The third raster line RL is formed by t and the adjacent t+1 raster line RL t+1 It forms.

[0122] Discharge nozzle row 123 (s+1) s+1 This is a yellow ink ejection nozzle row 123Y which includes a yellow ink ejection nozzle 23Y that ejects yellow ink. The s+1st ejection nozzle row 123 s+1It includes a plurality of ejection nozzles 23 arranged in the nozzle arrangement direction ND. The plurality of ejection nozzles 23 include the u+1 ejection nozzle 23 which is the yellow ink ejection nozzle 23Y. u+1 Includes the s+1 discharge nozzle row 123. s+1 It extends along the nozzle arrangement direction ND. The s+1st discharge nozzle row 123 s+1 This is the r+1 discharge nozzle row 123 r+1 It is provided in the direction C perpendicular to the direction.

[0123] Discharge nozzle u+1 23 u+1 This is achieved by ejecting ink onto the medium M, thereby creating the u+1 raster line RL. u+1 Forms the u+1 raster line RL. u+1 This is the t+1th raster line RL t+1 It is formed in the same or approximately the same position as the raster line RL (the +1 raster line). u+1 and the t+1 raster line RL t+1 These are formed at positions where they overlap. The u+1 raster line RL u+1 This is the first u-raster line RL u Adjacent to it. 1st discharge nozzle 23 u+1 The u discharge nozzle 23 u The first u-raster line RL is formed by u and the adjacent u+1 raster line RL u+1 It forms.

[0124] Head tip #24 (v+1) v+1 This is the black ink ejection nozzle 23K, which is the t+1 ejection nozzle 23 t+1 Includes the r+1 discharge nozzle row 123 r+1 and the yellow ink ejection nozzle 23Y is the s+1 ejection nozzle row 123 s+1 It has the following: The black ink ejection nozzle 23K and the yellow ink ejection nozzle 23Y form a raster line RL at the same or approximately the same position. The v+1 head tip 24 v+1 This is the v head tip 24 v It is positioned in the orthogonal direction C.

[0125] Figure 14 shows the relationship between the raster line RL and the discharge nozzle 23. Figure 14 shows the t-th discharge nozzle 23 shown in Figure 13. t and discharge nozzle 23 u The vicinity of is shown in magnified view. Figure 14 shows the t-th discharge nozzle 23 t , the t+1 discharge nozzle 23 t+1 , t-1 discharge nozzle 23 t-1 , the u discharge nozzle 23 u , the u+1 discharge nozzle 23 u+1 , and u-1 discharge nozzle 23 u-1 This indicates that.

[0126] Discharge nozzle 23 (t-1) t-1 This is the r+1 discharge nozzle row 123 r+1 This is the black ink ejection nozzle 23K included. The t-1 ejection nozzle 23 t-1 This is achieved by ejecting ink onto the medium M, thereby creating the t-1 raster line RL. t-1 Forms the t-1 raster line RL. t-1 This is the t-th raster line RL t It is formed in the opposite direction to the orthogonal direction C. The t-1 raster line RL t-1 This is the t-th raster line RL t Adjacent to it. Discharge nozzle t-1 23 t-1 The t-discharge nozzle 23 t The third raster line RL is formed by t and adjacent to the t-1 raster line RL t-1 It forms.

[0127] Discharge nozzle u-1 23 u-1 This is the s+1 discharge nozzle row 123 s+1 This is the yellow ink ejection nozzle 23Y included. The u-1 ejection nozzle 23 u-1 This is achieved by ejecting ink onto the medium M, thereby creating the u-1 raster line RL. u-1 Forms the u-1 raster line RL. u-1 This is the t-1 raster line RL t-1 It is formed in the same or approximately the same position as the u-1 raster line RL. u-1and the t-1 raster line RL t-1 These are formed at positions where they overlap. The u-1st raster line RL u-1 This is the first u-raster line RL u It is formed in the opposite direction to the orthogonal direction C. The u-1 raster line RL u-1 This is the first u-raster line RL u Adjacent to it. Discharge nozzle u-1 23 u-1 The u discharge nozzle 23 u The first u-raster line RL is formed by u and the adjacent u-1 raster line RL u-1 It forms.

[0128] The liquid dispensing device 11 has a row of r dispensing nozzles 123 r Discharge nozzle 23 and r+1 discharge nozzle row 123 included r+1 The discharge nozzles 23 included in the liquid discharge device 11 enable the printing of a continuous black print image in the orthogonal direction C. s Discharge nozzle 23 and s+1 discharge nozzle row 123 included s+1 The included discharge nozzle 23 enables the printing of a continuous yellow print image in the orthogonal direction C.

[0129] The second liquid discharge head 22b is connected to the r discharge nozzle row 123 r A second u-discharge nozzle 23 is provided in the orthogonal direction C and discharges yellow ink of yellow color. u The sth discharge nozzle row 123 s It is preferable that it has The second liquid discharge head 22b is connected to the s discharge nozzle row 123 s By having this feature, it becomes possible to form a two-color raster line RL.

[0130] The second liquid discharge head 22b is connected to the r discharge nozzle row 123 r and the s-th discharge nozzle row 123 s The v head tip 24 v Preferably, it is composed of the following: The relative positional accuracy between the yellow raster line RL and the black raster line RL is improved. [Explanation of symbols]

[0131] 11...Liquid ejection device, 12...Housing, 13...Image reading unit, 14...Automatic feeding unit, 15...Operation unit, 16...Printing unit, 17...Placement unit, 17A...Placement surface, 18...Media storage unit, 18A...Edge guide, 18B...Size sensor, 20...Head unit, 21...Support unit, 22...Liquid ejection head, 22a...First liquid ejection head, 22b...Second liquid ejection head, 22s...Ejection surface, 23...Ejection nozzle, 23b...Blank ejection nozzle, 23C...Cyan ink ejection nozzle, 23K...Black ink ejection nozzle, 23M...Magenta ink ejection nozzle, 23 p-1 ...Discharge nozzle p-1, 23 p-2 ...P-2 discharge nozzle, 23 p-3 ...P-3 discharge nozzle, 23 p-12 ...P-12 discharge nozzle, 23 p ...P discharge nozzle, 23 p+1 ...Discharge nozzle p+1, 23 p+2 ...p+2 discharge nozzle, 23 p+3 ...P+3 discharge nozzle, 23 p+4 ...Discharge nozzle p+4, 23 p+5 ...Discharge nozzle p+5, 23 t-1 ...Discharge nozzle t-1, 23 t ...Discharge nozzle, 23 t+1 ...Discharge nozzle t+1, 23 u-1 ...U-1 discharge nozzle, 23 u ...Discharge nozzle, 23 u+1 ...1st ejection nozzle, 23Y...Yellow ink ejection nozzle, 24...Head tip, 24 q-1 ...Q-1 head tip, 24 q ...Q head tip, 24 v ...v head tip, 24 v+1…v+1 head tip, 27…supply path, 28…liquid container, 29…holder, 30…conveying section, 31…feeding roller, 32…separation roller, 33…conveying roller, 34…conveying belt, 35…first roller, 36…second roller, 37…belt movement mechanism, 40…maintenance section, 41…cap, 42…waste liquid flow path, 43…pressure reduction unit, 44…discharge mechanism, 45…cap movement mechanism, 50…waste liquid container, 51…waste liquid container holder, 100…control section, 123…discharge nozzle row, 123C…cyan ink discharge nozzle row, 123K…black ink discharge nozzle row, 123M…magenta ink discharge nozzle row, 123Y…yellow ink discharge nozzle row, 123 n-1 ...the (n-1) discharge nozzle row, 123 n-2 ...n-2nd discharge nozzle row, 123 n ...nth discharge nozzle row, 123 n+1 ...the (n+1)th discharge nozzle row, 123 r ...Rth discharge nozzle row, 123 r+1 ...row r+1 discharge nozzles, 123 s ...sth discharge nozzle row, 123 s+1 ...s+1st nozzle row, 200...printed dot, 200a...1st printed dot, 200b...2nd printed dot, 200c...3rd printed dot, 200d...4th printed dot, C...orthogonal direction, CP...center point, d...printed dot diameter, G...grid, GL...grid line, GW...grid line width, L...grid diagonal, M...medium, ND...nozzle arrangement direction, NG1...1st nozzle row section, NG2...2nd nozzle row section, NL1...distance between 1st nozzles, NL2...distance between 2nd nozzles, RL...raster line, RL p-1 ...Raster line p-1, RL p-2 ...P-2 raster line, RL p-3 ...P-3 raster line, RL p ...the p-th raster line, RL p+1 ...the p+1 raster line, RL p+2 ...the p+2 raster line, RL p+3 ...the p+3 raster line, RL p+4 ...p+4 raster line, RL p+5 ...p+5 raster line, RL t-1 ...Raster line t-1, RL t...the t-th raster line, RL t+1 ...the t+1th raster line, RL u-1 ...Raster line u-1, RL u ...the u-raster line, RL u+1 ...1st raster line, T...conveying direction, TR...conveying path, RW...raster line width, Vc...virtual centerline, VL1...1st virtual line, VL2...2nd virtual line.

Claims

1. A print head comprising: a first nozzle row in which a plurality of nozzles, including a first nozzle for discharging a liquid of a predetermined color, are arranged along an inclined direction that is inclined with respect to the transport direction of the printing medium; a second nozzle row in which a plurality of nozzles, including a second nozzle for discharging the liquid of the predetermined color, are arranged along the inclined direction and are provided in a direction perpendicular to the transport direction relative to the first nozzle row; and a third nozzle row in which a plurality of nozzles, including a third nozzle for discharging the liquid of the predetermined color, are arranged along the inclined direction and are provided in the opposite direction to the perpendicular direction relative to the first nozzle row, The first nozzle forms a first raster line. The second nozzle forms a second raster line adjacent to the first raster line. The third nozzle forms a third raster line adjacent to the first raster line. The first distance between the first nozzle and the third nozzle along the conveying direction is 1.5 or less, when the second distance between the first nozzle and the second nozzle along the conveying direction is set to 1. The printed dot diameter d of the impact dot formed by discharging the liquid from the first nozzle has the following relationship: Printing device. d ≥ 1.5 × L Here, L is the diagonal length of the recording resolution grid.

2. The aforementioned print head is A first head module having the first nozzle row and the second nozzle row, A second head module having the third nozzle row, The printing apparatus according to claim 1.

3. The second head module has a fourth nozzle row in which a plurality of nozzles, including a fourth nozzle for discharging the liquid of a predetermined color, are arranged along the inclined direction. The printing apparatus according to claim 2.

4. The second nozzle row overlaps with the first portion of one of the first nozzle rows in a plan view from the transport direction with respect to the central position of the first nozzle row along the inclination direction, The third nozzle row overlaps with the second portion of the other first nozzle row with respect to the central position in a plan view from the transport direction. The printing apparatus according to claim 1.

5. The second liquid discharge nozzle row is provided in the direction orthogonal to the first nozzle row and includes a second liquid discharge nozzle that discharges a second liquid of a different color from the predetermined color, The printing apparatus according to claim 1.

6. The print head is composed of a head module including the first nozzle row and the second liquid ejection nozzle row. The printing apparatus according to claim 5.

7. The second nozzle row has surplus nozzles capable of forming the third raster line. The printing apparatus according to claim 1.

8. A printing method for a printing apparatus comprising a print head having a first nozzle row in which a plurality of nozzles, including a first nozzle for discharging a liquid of a predetermined color, are arranged along an inclined direction that is inclined with respect to the transport direction of the printing medium; a second nozzle row in which a plurality of nozzles, including a second nozzle for discharging the liquid of the predetermined color, are arranged along the inclined direction and are provided on one of the orthogonal directions perpendicular to the transport direction relative to the first nozzle row; and a third nozzle row in which a plurality of nozzles, including a third nozzle for discharging the liquid of the predetermined color, are arranged along the inclined direction and are provided on the other orthogonal direction relative to the first nozzle row, are arranged along the inclined direction, wherein The first nozzle forms a first raster line. The second nozzle forms a second raster line adjacent to the first raster line. The third nozzle forms a third raster line adjacent to the first raster line. The first distance between the first nozzle and the third nozzle along the conveying direction is 1.5 or less, when the second distance between the first nozzle and the second nozzle along the conveying direction is set to 1. By discharging the liquid from the first nozzle, impact dots with a print dot diameter d having the following relationship are formed: Printing method. d ≥ 1.5 × L Here, L is the diagonal length of the recording resolution grid.

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