Printer and printing method

Abstract

To suppress generation of a light-colored streak along a relative movement direction of a medium in between nozzle arrays due to flow of a dot on the medium.SOLUTION: A transfer part relatively moves a medium in a relative movement direction crossing with a nozzle array direction with reference to a printing head. In an overlapping part of the printing head, a first nozzle array is located on an upstream side in the relative movement direction from a second nozzle array. In the nozzle array direction, a boundary between a first printing region by the first nozzle array and a second printing region by the second nozzle array is within a range of the overlapping part. A plurality of first nozzles includes a normal nozzle existing in the first printing region and a flow prevention dot formation nozzle existing in an end portion on the first printing region side in the second printing region. A control part causes the printing head to form a plurality of flow prevention dots not adjacent to each other in the relative movement direction by first liquid discharged from the flow prevention dot formation nozzle to the medium at the time of printing.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a printing apparatus having an overlapping portion where nozzle rows partially overlap each other, and a printing method. [Background technology]

[0002] Patent Document 1 discloses a printer that performs printing using a printing unit in which a first nozzle array group and a second nozzle array group are aligned in a direction intersecting a predetermined direction. In the first nozzle array group, first nozzle arrays in which first nozzles that eject a first liquid are aligned in the predetermined direction are aligned in the predetermined direction, and ends of adjacent first nozzle arrays overlap. In the second nozzle array group, second nozzle arrays in which second nozzles that eject a second liquid are aligned in the predetermined direction are aligned in the predetermined direction, and ends of adjacent second nozzle arrays overlap.

[0003] In the printer, there is an error in the installation position in the predetermined direction between nozzle array groups that eject different liquids, and there is an error in the installation position in the predetermined direction between nozzle arrays that eject the same liquid. The error between nozzle arrays that eject the same liquid causes density unevenness such as black streaks or white streaks in the print result due to overlapping portions of nozzle arrays that eject the same liquid. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-195897 Summary of the Invention [Problem to be solved by the invention]

[0005] Even if the range of use of the first and second nozzles in the overlapping area is determined so that the print area by the first nozzle row and the print area by the second nozzle row are continuous in a first nozzle row and a second nozzle row that eject the same liquid, faint streaks, such as white streaks, which are the background color components of the medium, may appear. Therefore, improvements are needed to eliminate faint streaks that occur in the overlapping area between nozzle rows that eject the same liquid. [Means for solving the problem]

[0006] The printing device of the present invention comprises: a print head having a first nozzle row in which a plurality of first nozzles capable of ejecting a first liquid onto a medium are aligned in a predetermined nozzle alignment direction, and a second nozzle row in which a plurality of second nozzles capable of ejecting the first liquid onto the medium are aligned in the nozzle alignment direction; a transport unit that moves the medium relative to the print head in a relative movement direction that intersects with the nozzle arrangement direction; a control unit that controls the ejection of a liquid including the first liquid by the print head, the print head has an overlapping portion where a portion of the first nozzle row and a portion of the second nozzle row overlap when viewed in the direction of relative movement, In the overlapping portion, the first nozzle row is located upstream of the second nozzle row in the relative movement direction, a boundary between a first printing area printed by the first nozzle row and a second printing area printed by the second nozzle row is within the overlapping area in the nozzle arrangement direction; the plurality of first nozzles include normal nozzles in the first printing region and flow prevention dot forming nozzles in the second printing region at an end of the second printing region on the first printing region side, The control unit has an aspect in which, during printing, the control unit causes the print head to form a plurality of flow prevention dots that are not adjacent to each other in the direction of relative movement by using the first liquid ejected from the flow prevention dot formation nozzles onto the medium.

[0007] A printing method of the present invention includes moving a medium relative to a print head in a relative movement direction that intersects with a predetermined nozzle arrangement direction, and ejecting a liquid including a first liquid from the print head onto the medium, the print head has a first nozzle row in which a plurality of first nozzles capable of ejecting the first liquid onto the medium are aligned in the nozzle alignment direction, and a second nozzle row in which a plurality of second nozzles capable of ejecting the first liquid onto the medium are aligned in the nozzle alignment direction, the print head has an overlapping portion where a portion of the first nozzle row and a portion of the second nozzle row overlap when viewed in the direction of relative movement, In the overlapping portion, the first nozzle row is located upstream of the second nozzle row in the relative movement direction, a boundary between a first printing area printed by the first nozzle row and a second printing area printed by the second nozzle row is within the overlapping area in the nozzle arrangement direction; the plurality of first nozzles include normal nozzles in the first printing region and flow prevention dot forming nozzles in the second printing region at an end of the second printing region on the first printing region side, In a printing method in which streaks occur between the first printing area and the second printing area due to the flow of the first liquid during printing without using the flow prevention dot forming nozzle, the first liquid is ejected from the flow prevention dot forming nozzle onto the medium to form multiple flow prevention dots that are not adjacent to each other in the relative movement direction.

[0008] Furthermore, the present invention provides a printing method in which a medium is moved relatively to a print head in a relative movement direction that intersects with a predetermined nozzle arrangement direction, and a liquid including a first liquid is ejected from the print head onto the medium, the print head has a first nozzle row in which a plurality of first nozzles capable of ejecting the first liquid onto the medium are aligned in the nozzle alignment direction, and a second nozzle row in which a plurality of second nozzles capable of ejecting the first liquid onto the medium are aligned in the nozzle alignment direction, the print head has an overlapping portion where a portion of the first nozzle row and a portion of the second nozzle row overlap when viewed in the direction of relative movement, In the overlapping portion, the first nozzle row is located upstream of the second nozzle row in the relative movement direction, where n is an integer of 2 or greater, and a pair of the first nozzle and the second nozzle, whose position in the first nozzle row and whose position in the second nozzle row correspond to each other in the overlapping portion, is defined as a nozzle pair, the overlapping portion has n sets of nozzle pairs aligned in the nozzle alignment direction, The printing method includes: a first test pattern printing step of printing a first test pattern on the medium to determine a usage range of the first nozzles and the second nozzles in the overlapping portion, the first test pattern being printed using m specific nozzle pairs, where m is an integer greater than or equal to 0 and less than n, in which the first nozzles and the second nozzles are used to eject the first liquid; a use range determination step of determining the use range based on the density of a specific area from the first printing position to the second printing position, the first printing position is a printing position of the first nozzle that is closest to a second printing area by the second nozzle row in a first printing area by the first nozzle row in the first test pattern printed on the medium, the second printing position is a printing position of the second nozzle that is closest to the first printing area among the second printing positions in the first test pattern printed on the medium, the plurality of first nozzles include normal nozzles in the first printing region and flow prevention dot forming nozzles in the second printing region at an end of the second printing region on the first printing region side, The printing method includes: The present invention has an aspect in which, when streaks occur between the first printing area and the second printing area due to the flow of the first liquid during printing based on the range of use, the method further includes a flow prevention dot formation process in which multiple flow prevention dots that are not adjacent to each other in the relative movement direction are formed using the first liquid ejected from the flow prevention dot formation nozzle onto the medium. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram illustrating a configuration example of a printing apparatus. [Figure 2] 3A and 3B are diagrams illustrating an example of the positional relationship between a print head and a medium. [Figure 3] Figure 3A is a diagram showing a schematic representation of a portion of the first nozzle row and the second nozzle row as an example of an ideal state, Figure 3B is a diagram showing a schematic representation of a portion of the first nozzle row and the second nozzle row as a first example of a non-ideal state, and Figure 3C is a diagram showing a schematic representation of a portion of the first nozzle row and the second nozzle row as a second example of a non-ideal state. [Figure 4] 10 is a flow chart showing an example of a nozzle use range determination process; [Figure 5] Figure 5A is a diagram illustrating the overlapping portion and the first test pattern when the adjustment value is 0, Figure 5B is a diagram illustrating the overlapping portion and the first test pattern when the adjustment value is +1, and Figure 5C is a diagram illustrating the overlapping portion and the first test pattern when the adjustment value is -1. [Figure 6] FIG. 2 is a diagram illustrating a print head and a main part of a printed image. [Figure 7] 10A and 10B are diagrams schematically showing examples of intervals between flow-preventing dots. [Figure 8] FIG. 10 is a diagram schematically showing an example of the size of the flow prevention dot. [Figure 9] FIG. 10 is a diagram schematically showing an example of the number of flow prevention dot forming nozzles. [Figure 10] 10 is a flowchart illustrating an example of an adjustment process. [Figure 11] FIG. 4 is a diagram illustrating a print head and a main part of a second test pattern. [Figure 12] 10 is a flowchart illustrating an example of a print control process. [Figure 13] 10 is a flowchart schematically illustrating another example of the print control process. [Figure 14] 5A and 5B are diagrams schematically showing an example of the behavior of the first liquid on the medium when the wettability of the liquid with respect to the medium is low. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes embodiments of the present invention. Of course, the following embodiments are merely examples of the present invention, and not all of the features shown in the embodiments are necessarily essential to the solution of the invention.

[0011] (1) Summary of the aspects included in the present invention: First, an overview of the embodiments included in the present invention will be described with reference to the examples shown in Figures 1 to 14. The figures in this application are diagrams showing examples in a schematic manner, and the ratios, shapes, and shadings shown in these figures may not be accurate, and the figures may not be consistent with each other, and some parts may be omitted. Of course, each element of the present embodiment is not limited to the specific example indicated by a symbol. In the "Outline of the embodiments included in the present invention," the words in parentheses indicate supplementary explanations for the immediately preceding words.

[0012] [Aspect 1] As illustrated in FIG. 1 and other figures, a printing device 10 according to one embodiment includes a print head 19, a transport unit 17, and a control unit 11. As illustrated in FIG. 6 and other figures, the print head 19 includes a first nozzle row 201 in which a plurality of first nozzles 211 capable of ejecting a first liquid LQ1 onto a medium 30 are aligned in a predetermined nozzle alignment direction D3, and a second nozzle row 202 in which a plurality of second nozzles 212 capable of ejecting the first liquid LQ1 onto the medium 30 are aligned in the nozzle alignment direction D3. The transport unit 17 moves the medium 30 relative to the print head 19 in a relative movement direction D1 that intersects with the nozzle alignment direction D3. The control unit 11 controls the ejection of the liquid LQ0 containing the first liquid LQ1 by the print head 19. The print head 19 includes an overlapping portion 22 in which a portion of the first nozzle row 201 and a portion of the second nozzle row 202 overlap when viewed from the relative movement direction D1. In the overlapping portion 22, the first nozzle row 201 is located upstream S1 of the second nozzle row 202 in the relative movement direction D1. In the nozzle alignment direction D3, a boundary B1 between a first print region AR1 printed by the first nozzle row 201 and a second print region AR2 printed by the second nozzle row 202 is within the overlapping portion 22. The multiple first nozzles 211 include a normal nozzle NZ1 in the first print region AR1 and a flow prevention dot forming nozzle NZ2 at the end of the second print region AR2 on the first print region AR1 side. The control unit 11 causes the print head 19 to form multiple flow prevention dots DT1 that are not adjacent to each other in the relative movement direction D1 using the first liquid LQ1 ejected from the flow prevention dot forming nozzle NZ2 onto the medium 30 during printing.

[0013] Testing revealed that when the wettability of the liquid LQ0 to the medium 30 is low, the first liquid LQ1 ejected first from the first nozzle row 201 flows and gathers on the medium 30, resulting in the formation of faint streaks along the direction D1 of relative movement of the medium 30 between the nozzle rows. The faint streaks represent streaks that reveal the background color components of the medium 30. In the above-described embodiment, multiple flow prevention dots DT1 that are not adjacent to each other in the direction D1 of relative movement are formed at the end of the second printing region AR2 on the first printing region AR1 side. This allows the first liquid LQ1 in the first printing region AR1 and the first liquid LQ1 in the second printing region AR2 to be appropriately connected. This prevents faint streaks along the direction D1 of relative movement between the nozzle rows ejecting the first liquid LQ1. Therefore, the above-described embodiment can provide a printing device that can prevent faint streaks along the direction D1 of relative movement of the medium between the nozzle rows due to the flow of dots on the medium.

[0014] There are various examples of the above-described aspects. The transport unit may move the medium in the relative movement direction without moving the print head, may move the print head in the direction opposite to the relative movement direction without moving the medium, or may move both the medium and the print head. The upstream side in the relative movement direction does not mean the side to which the medium moves relatively, but the side to which the medium moves relatively. Therefore, at a certain position in the relative movement direction, the first liquid ejected from the first nozzle row lands and then the first liquid ejected from the second nozzle row lands. When the relative movement direction is the medium transport direction, the medium is transported from the upstream side to the downstream side. The number of flow prevention dot forming nozzles may be one nozzle, or two or more nozzles. The fact that multiple flow prevention dots are not adjacent to each other in the relative movement direction means that multiple flow prevention dots are formed at a recording rate of 50% or less in pixel units in the relative movement direction. In this application, the terms "first", "second", etc. are terms for distinguishing between elements among a plurality of elements having similarities, and do not imply any order. Of course, the above remarks also apply to the following aspects.

[0015] [Aspect 2] 1 and 13, the printing device 10 may further include an operation receiving unit 14 that receives an operation to change from the flow prevention dot forming nozzles NZ2 to the normal nozzles NZ1. When the change operation is received, the control unit 11 may change the flow prevention dot forming nozzles NZ2 to the normal nozzles NZ1 and control the ejection of the liquid LQ0 by the print head 19. When the flow prevention dot forming nozzles NZ2 are changed to normal nozzles NZ1, the amount of first liquid LQ1 ejected from the first nozzle row 201 toward the end of the second printing region AR2 on the side of the first printing region AR1 increases. If light streaks are still visible when the flow prevention dots DT1 are formed, changing the flow prevention dot forming nozzles NZ2 to normal nozzles NZ1 will reduce the light streaks. Therefore, the above aspect can more appropriately suppress streaks along the direction of relative movement between the nozzle rows depending on the type of medium and liquid.

[0016] [Aspect 3] 1, 8, and 10, the printing device 10 may further include an operation receiving unit 14 that receives a setting operation for the size of the flow prevention dots DT1. When the setting operation is received, the control unit 11 may cause the print head 19 to form the plurality of flow prevention dots DT1 at the size. As the size of the flow prevention dots DT1 increases, the amount of first liquid LQ1 ejected from the first nozzle row 201 toward the end of the second printing region AR2 on the side of the first printing region AR1 increases. If faint streaks are visible even when relatively small flow prevention dots DT1 are formed, the faint streaks are reduced by increasing the size of the flow prevention dots DT1. Therefore, the above aspect can more appropriately suppress streaks along the direction of relative movement between the nozzle rows.

[0017] [Aspect 4] Incidentally, a printing method according to one embodiment is a printing method in which a medium 30 is moved relative to a print head 19 in a relative movement direction D1 that intersects with a predetermined nozzle alignment direction D3, and a liquid LQ0 containing a first liquid LQ1 is ejected from the print head 19 onto the medium 30. The print head 19 has a first nozzle row 201 in which a plurality of first nozzles 211 capable of ejecting the first liquid LQ1 onto the medium 30 are aligned in the nozzle alignment direction D3, and a second nozzle row 202 in which a plurality of second nozzles 212 capable of ejecting the first liquid LQ1 onto the medium 30 are aligned in the nozzle alignment direction D3. The print head 19 has an overlapping portion 22 in which a portion of the first nozzle row 201 and a portion of the second nozzle row 202 overlap as viewed from the relative movement direction D1. In the overlapping portion 22, the first nozzle row 201 is located upstream S1 of the second nozzle row 202 in the relative movement direction D1. In the nozzle alignment direction D3, a boundary B1 between the first print region AR1 printed by the first nozzle row 201 and the second print region AR2 printed by the second nozzle row 202 is within the range of the overlapping portion 22. The multiple first nozzles 211 include a normal nozzle NZ1 located in the first print region AR1 and a flow prevention dot forming nozzle NZ2 located at the end of the second print region AR2 on the first print region AR1 side. In this printing method, when streaks 50 caused by the flow of the first liquid LQ1 occur between the first print region AR1 and the second print region AR2 during printing without using the flow prevention dot forming nozzle NZ2, as illustrated in FIG. 14 , multiple flow prevention dots DT1 that are not adjacent to each other in the relative movement direction D1 are formed by the first liquid LQ1 ejected onto the medium 30 from the flow prevention dot forming nozzle NZ2.

[0018] The above aspect can provide a printing method that can prevent the generation of faint streaks between nozzle rows along the direction of relative movement of the medium due to the flow of dots on the medium.

[0019] [Aspect 5] Here, n is an integer equal to or greater than 2, and a pair of the first nozzle 211 and the second nozzle 212, in which the position of the first nozzle row 201 within the overlapping portion 22 corresponds to the position of the second nozzle row 202 within the overlapping portion 22, is defined as a nozzle pair. In a printing method according to another aspect, the overlapping portion 22 has n sets of nozzle pairs aligned in the nozzle alignment direction D3. This printing method includes the following steps, as exemplified in FIG. 4. (a1) When printing a first test pattern 31 on the medium 30 to determine the range of use of the first nozzle 211 and the second nozzle 212 in the overlapping portion 22, a first test pattern printing process ST1 is performed in which the number of specific nozzle pairs that use the first nozzle 211 and the second nozzle 212 to eject the first liquid LQ1 is set to m, where m is an integer greater than or equal to 0 and less than n, and the first test pattern 31 is printed. (a2) A use range determination step ST2 in which the use range is determined based on the density of the specific region 32 from the first printing position to the second printing position. The first printing position is a printing position of the first nozzle 211, in the first print region AR1 printed by the first nozzle row 201, that is closest to the second print region AR2 printed by the second nozzle row 202, in the first test pattern 31 printed on the medium 30. The second printing position is a printing position of the second nozzle 212, in the second print region AR2 that is closest to the first print region AR1, in the first test pattern 31 printed on the medium 30. The multiple first nozzles 211 include a normal nozzle NZ1 in the first print region AR1 and a flow prevention dot forming nozzle NZ2 at the end of the second print region AR2 on the first print region AR1 side. As exemplified in FIGS. 10 and 12 , this printing method further includes the following steps. (a3) A flow prevention dot formation process ST3 in which, when streaks 50 (see Figure 14) caused by the flow of the first liquid LQ1 occur between the first printing area AR1 and the second printing area AR2 during printing based on the usage range, multiple flow prevention dots DT1 that are not adjacent to each other in the relative movement direction D1 are formed using the first liquid LQ1 ejected from the flow prevention dot formation nozzle NZ2 onto the medium 30.

[0020] Testing revealed that even when the usage ranges of the first nozzles 211 and the second nozzles 212 are determined based on the density of the specific region 32 of the first test pattern 31, if the wettability of the liquid LQ0 with respect to the medium 30 is low, faint streaks appear between the nozzle rows along the direction D1 of relative movement of the medium 30. This is because the first liquid LQ1 ejected first from the first nozzle row 201 flows and gathers on the medium 30. In the above embodiment, if streaks 50 due to the flow of the first liquid LQ1 appear between the first print region AR1 and the second print region AR2 during printing based on the determined usage ranges, multiple flow prevention dots DT1 that are not adjacent to each other in the direction D1 of relative movement are formed at the end of the second print region AR2 on the first print region AR1 side. This allows the first liquid LQ1 in the first print region AR1 and the first liquid LQ1 in the second print region AR2 to be appropriately connected, suppressing faint streaks along the direction D1 of relative movement between the nozzle rows ejecting the first liquid LQ1. Therefore, the above aspect can provide a printing method that can prevent the generation of faint streaks between nozzle rows along the direction of relative movement of the medium due to the flow of dots on the medium.

[0021] [Aspect 6] As illustrated in FIGS. 8 and 10, the printing method may further include the following steps. (a4) A size setting reception step ST4 for receiving a setting of the size of the flow-preventing dots DT1. In the flow prevention dot forming step ST3, the plurality of flow prevention dots DT1 may be formed to the above size.

[0022] As the size of the flow prevention dots DT1 increases, the amount of first liquid LQ1 ejected from the first nozzle row 201 toward the end of the second printing region AR2 on the side of the first printing region AR1 increases. If faint streaks are visible even when relatively small flow prevention dots DT1 are formed, the faint streaks are reduced by increasing the size of the flow prevention dots DT1. Therefore, the above aspect can more appropriately suppress streaks along the direction of relative movement between the nozzle rows.

[0023] [Aspect 7] As illustrated in FIGS. 7, 10 and 11, the printing method may further include the following steps. (a5) A second test pattern printing process ST5 in which a second test pattern 35 including the flow prevention dots DT1 is formed by the first liquid LQ1 ejected onto the medium 30 from the first nozzle row 201 and the second nozzle row 202, the second test pattern 35 including a plurality of individual patterns 36 in which the spacing between the flow prevention dots DT1 in the relative movement direction D1 is changed. (a6) A spacing determination step ST6 for determining the spacing between the flow prevention dots DT1 to be applied to the flow prevention dot forming step ST3 based on the second test pattern 35.

[0024] As the spacing between the flow prevention dots DT1 narrows, the amount of first liquid LQ1 ejected from the first nozzle row 201 toward the end of the second printing region AR2 on the side of the first printing region AR1 increases. If faint streaks are visible even when flow prevention dots DT1 are formed at relatively wide spacing, narrowing the spacing between the flow prevention dots DT1 will reduce the faint streaks. Therefore, the above aspect can more appropriately suppress streaks along the direction of relative movement between the nozzle rows.

[0025] [Aspect 8] In the second test pattern printing step ST5, the second test pattern 35 may be formed when at least one of the type of the medium 30 and the type of the first liquid LQ1 is changed. The degree to which the dots on the medium 30 flow varies depending on the combination of the type of medium 30 and the type of liquid LQ0. By forming the second test pattern 35 by changing at least one of the type of medium 30 and the type of first liquid LQ1, it is possible to effectively prevent the flow of dots on the medium from causing faint streaks along the direction of relative movement of the medium between the nozzle rows.

[0026] Furthermore, the above-described aspects are applicable to a multifunction peripheral including the above-described printing device, a control method for the above-described printing device, a control program for the above-described printing device, a control program for the above-described multifunction device, a computer-readable non-transitory medium on which any of the above programs is recorded, etc. Any of the above-described devices may be composed of multiple distributed parts.

[0027] (2) Examples of printing devices: Fig. 1 shows a schematic example of the configuration of a printing device 10. A printing method is performed in the printing device 10. Fig. 2 is a plan view showing a simplified example of the positional relationship between a print head 19 and a medium 30 as viewed from above. Figs. 3A to 3C show a schematic example of a portion of a first nozzle row and a second nozzle row. 1 includes a control unit 11, a display unit 13, an operation reception unit 14, a memory unit 15, a communication I / F (interface) 16, a transport unit 17, a print head 19, etc. The control unit 11 includes a CPU (Central Processing Unit) 11a as a processor, a ROM (Read Only Memory) 11b, a RAM (Random Access Memory) 11c, etc. The control unit 11 may also include a non-volatile memory, etc. The control unit 11 including the CPU 11a may be configured with one or more ICs (Integrated Circuits).

[0028] The CPU 11a controls the printing device 10 by using RAM 11c and the like as a work area and executing arithmetic processing in accordance with the program 12 recorded in ROM 11b or other memory. The processor is not limited to a single CPU, but may be multiple CPUs or a hardware circuit such as an ASIC (Application Specific Integrated Circuit). Furthermore, the CPU and the hardware circuit may work together to perform processing.

[0029] Display unit 13 is a means for displaying visual information, and may be a liquid crystal display, an organic EL (electroluminescence) display, etc. Display unit 13 may be configured to include a display and a drive circuit for driving the display. The operation reception unit 14 is a means for receiving input from a user, and may be a physical button, a touch panel, a mouse, a keyboard, or the like. The touch panel may be realized as one function of the display unit 13. The display unit 13 and the operation reception unit 14 may be collectively referred to as the operation panel of the printing device 10.

[0030] The storage unit 15 may be a solid state drive, a hard disk drive, other memory, etc. A part of the memory of the control unit 11 may be regarded as the storage unit 15. The storage unit 15 may be regarded as a part of the control unit 11. The display unit 13, the operation reception unit 14, and the storage unit 15 may be peripheral devices externally attached to the printing device 10. The communication I / F 16 is a general term for one or more I / Fs that allow the printing device 10 to communicate with an external device via wired or wireless communication in accordance with a predetermined communication protocol, including a known communication standard. The external device may be a communication device such as a personal computer, a server, a smartphone, or a tablet terminal.

[0031] As shown in FIG. 2, the transport unit 17 moves the medium 30 in a relative movement direction D1 that intersects with a predetermined nozzle arrangement direction D3. When the printing device 10 is a line-type inkjet printer such as a line printer, the medium 30 is continuous in the relative movement direction D1, and the transport unit 17 continuously transports the medium 30 in the relative movement direction D1 during printing. Therefore, the relative movement direction D1 in a line-type printing device can also be referred to as the transport direction. The transport unit 17 can be referred to as moving the medium 30 relative to the print head 19 in a predetermined transport direction (relative movement direction D1). The transport unit 17 includes, for example, rollers that rotate to transport the medium 30 and a motor as a power source for rotation. The transport unit 17 may also be a mechanism that transports the medium 30 by placing the medium 30 on a pallet, belt, drum, or the like. The medium 30 is, for example, paper, but any medium that can be printed with the liquid LQ0 may be used, including materials other than paper, such as fabric or film.

[0032] The print head 19 is a means for printing by ejecting the liquid LQ0 onto the medium 30 using an inkjet method under the control of the control unit 11. The liquid LQ0 is mainly ink, but the print head 19 can also eject liquid LQ0 other than ink. The print head 19 can eject ink of multiple colors, such as C (cyan), M (magenta), Y (yellow), and K (black). Of course, the ink ejected by the print head 19 is not limited to CMYK inks.

[0033] Printing device 10 may be realized by a single printer, or may be realized by multiple devices or equipment connected to each other so that they can communicate with each other. When printing device 10 is a system made up of multiple devices, it may include, for example, an information processing device that plays the role of control unit 11, and a printer that includes transport unit 17 and print head 19 and performs printing under the control of the information processing device. In this case, the information processing device can be understood as a print control device, image processing device, etc.

[0034] FIG. 2 shows print heads 19C, 19M, 19Y, and 19K as print heads 19 of a line-type printing device. The line-type print heads 19C, 19M, 19Y, and 19K are arranged in order in the relative movement direction D1 and fixed on the transport path of the medium 30. The width direction D2 of the medium 30 intersects with the relative movement direction D1. In FIG. 2, the intersection of the relative movement direction D1 and the width direction D2 may be interpreted as being perpendicular or nearly perpendicular. The nozzle arrangement direction D3 shown in FIG. 2 is aligned with the width direction D2. The transport unit 17 transports the medium 30 from upstream to downstream in the relative movement direction D1. Hereinafter, the upstream side of the relative movement direction D1 may be simply referred to as the upstream side, and the downstream side of the relative movement direction D1 may be simply referred to as the downstream side. Because the relative movement direction D1 shown in FIG. 2 is an upward direction, the lower side in FIG. 2 is the upstream side, and the upper side is the downstream side. In FIG. 6 and other figures described later, the left side is the upstream side S1 and the right side is the downstream side S2.

[0035] Each of the print heads 19C, 19M, 19Y, and 19K has multiple nozzle rows. The print head 19C has multiple nozzle rows 20C capable of ejecting C ink. The multiple nozzle rows 20C include nozzle rows 20C1, 20C2, 20C3, 20C4, and 20C5. The print head 19M has multiple nozzle rows 20M capable of ejecting M ink. The multiple nozzle rows 20M include nozzle rows 20M1, 20M2, 20M3, 20M4, and 20M5. The print head 19Y has multiple nozzle rows 20Y capable of ejecting Y ink. The multiple nozzle rows 20Y include nozzle rows 20Y1, 20Y2, 20Y3, 20Y4, and 20Y5. The print head 19K has multiple nozzle rows 20K capable of ejecting K ink. The multiple nozzle rows 20K include nozzle rows 20K1, 20K2, 20K3, 20K4, and 20K5. Of course, the number of nozzle rows that make up the print head 19 corresponding to one type of liquid LQ0 does not have to be five.

[0036] Print heads 19C, 19M, 19Y, and 19K all have a length in the width direction D2 sufficient to cover the medium width, which is the length of the medium 30 in the width direction D2. Print heads 19C, 19M, 19Y, and 19K are basically the same except for the color of the ink they eject, so print head 19C will be described here as a representative. Nozzle rows 20C1, 20C2, 20C3, 20C4, and 20C5 that make up print head 19C all have multiple nozzles 21 arranged in the nozzle arrangement direction D3 that are capable of ejecting the same liquid LQ0, i.e., C ink, which serves as the first liquid LQ1 (see FIG. 1). When focusing on print head 19M, M ink corresponds to the first liquid LQ1. When focusing on a certain print head 19 and referring to the liquid LQ0 ejected by that print head 19 as the first liquid LQ1, the liquid LQ0 ejected by another print head 19 may be referred to as the second liquid.

[0037] In FIG. 2, chips having each nozzle row are simply represented by rectangles, and the individual nozzles 21 in each nozzle row are omitted. As shown in FIG. 2, the print head 19 includes multiple chips arranged in a staggered pattern in the width direction D3, each chip having a nozzle row. For example, print head 19C includes a chip having nozzle row 20C1, a chip having nozzle row 20C2, a chip having nozzle row 20C3, a chip having nozzle row 20C4, and a chip having nozzle row 20C5. Each chip may have multiple nozzle rows for CMYK. Incorporating multiple chips into the print head 19 can result in installation errors between the chips. In FIG. 3A and other figures, individual nozzles 21 are represented by circles. The multiple nozzles 21 in a nozzle row may be arranged in a single row or in a staggered pattern, i.e., two rows. Here, the nozzle arrangement direction D3 of the multiple nozzles 21 arranged in a staggered pattern is the direction of arrangement of the nozzles 21 in each of the two rows. The spacing between adjacent nozzles 21 in the nozzle row, i.e., the distance between the nozzles 21 in the nozzle arrangement direction D3, is referred to as the nozzle pitch. The nozzle pitch is constant by design. The nozzle arrangement direction D3 may be parallel to the width direction D2 or may be inclined obliquely relative to the width direction D2. In either case, the nozzle arrangement direction D3 intersects with the relative movement direction D1. The spacing between the nozzles 21 in the width direction D2 may also be considered to be the nozzle pitch.

[0038] In this specific example, of the two nozzle rows adjacent to each other in the relative movement direction D1 within one print head 19, the upstream nozzle row is referred to as the "first nozzle row" and the downstream nozzle row is referred to as the "second nozzle row" to distinguish them. The "first nozzle row" has a plurality of "first nozzles" capable of ejecting the first liquid LQ1 onto the medium 30, aligned in the nozzle alignment direction D3. The "second nozzle row" has a plurality of "second nozzles" capable of ejecting the first liquid LQ1 onto the medium 30, aligned in the nozzle alignment direction D3. The terms "first nozzle row" and "second nozzle row" are merely used for the convenience of distinguishing between two nozzle rows. For example, if we focus on nozzle rows 20C1 and 20C2 within print head 19C, and the upstream nozzle row 20C2 corresponds to the first nozzle row, then the downstream nozzle row 20C1 corresponds to the second nozzle row. In this case, the nozzle row 20C2 can be said to have a plurality of first nozzles that eject C ink lined up in the nozzle alignment direction D3, and the nozzle row 20C1 can be said to have a plurality of second nozzles that eject C ink lined up in the nozzle alignment direction D3. Similarly, focusing on the nozzle rows 20C4 and 20C5, if the upstream nozzle row 20C4 is considered to be the first nozzle row, the downstream nozzle row 20C5 can be considered to be the second nozzle row. In this case, the nozzle row 20C4 can be said to have a plurality of first nozzles that eject C ink lined up in the nozzle alignment direction D3, and the nozzle row 20C5 can be said to have a plurality of second nozzles that eject C ink lined up in the nozzle alignment direction D3. The control unit 11 controls the ejection of the liquid LQ0 containing the first liquid LQ1 by this print head 19.

[0039] In this specific example, the ends of adjacent nozzle rows in the multiple nozzle rows that make up one print head 19 overlap in the nozzle alignment direction D3. Therefore, the print head 19 can be said to have an "overlapping portion 22" where a portion of the first nozzle row and a portion of the second nozzle row overlap when viewed in the relative movement direction D1. Figure 2 shows the range of each overlapping portion 22 in print head 19C. In the overlapping portion 22, the first nozzle row is located upstream of the second nozzle row in the relative movement direction D3. Note that the range of the nozzles 21 aligned in the print head 19 that does not fall under the overlapping portion 22 will be referred to as the "normal portion."

[0040] In this specific example, a pair of a first nozzle and a second nozzle whose position in the overlapping portion 22 of the first nozzle row corresponds to that in the overlapping portion 22 of the second nozzle row is referred to as a "nozzle pair." One overlapping portion 22 has n nozzle pairs aligned in the nozzle alignment direction D3. n is an integer greater than or equal to 2, e.g., n=64. Here, the right and left as viewed from upstream to downstream are simply referred to as the right and left, respectively. The first nozzle and the second nozzle whose position in the overlapping portion 22 of the first nozzle row corresponds to that in the overlapping portion 22 of the second nozzle row refer to the first nozzle and the second nozzle whose order in the left-right direction within the overlapping portion 22 is the same. For example, within the overlapping portion 22 of the nozzle row 20C4 and the nozzle row 20C5, the leftmost nozzle 21 in the nozzle row 20C4 and the leftmost nozzle 21 in the nozzle row 20C5 form one nozzle pair. Similarly, in the overlapping portion 22 between the nozzle rows 20C4 and 20C5, the second nozzle 21 from the left in the nozzle row 20C4 and the second nozzle 21 from the left in the nozzle row 20C5 form one nozzle pair.

[0041] The control unit 11 causes the print head 19 to eject droplets of the liquid LQ0 onto the medium 30 based on print data that represents an image. As is known, the print head 19 is provided with a drive element for each nozzle 21, and the application of a drive signal to the drive element of each nozzle 21 is controlled according to the print data, causing each nozzle 21 to eject or not eject droplets. When droplets from the nozzles 21 land on the medium 30, dots are formed on the medium 30. In this way, the image represented by the print data is printed on the medium 30 as a dot pattern. Here, the print data is assumed to be data that represents the droplet ejection state for each pixel and for each CMYK color, for example, whether or not to eject the droplets. In this case, the print data can also be considered image data that represents the dot formation state for each pixel and for each CMYK color, for example, whether or not to form the dots. The ejection of droplets can be referred to as dot-on, and the non-ejection of droplets can be referred to as dot-off. The control unit 11 controls the transport unit 17 and the print head 19 to form a printed image on the medium 30 by ejecting liquid droplets such as ink droplets onto the medium 30 passing under the print heads 19C, 19M, 19Y, and 19K.

[0042] Figure 3A shows an enlarged schematic of the overlapping portion 22 and its vicinity as an example of an ideal state. The ideal state refers to a state in which there is little or no error in the positional relationship in the nozzle alignment direction D3 between the first nozzle row and the second nozzle row, which share the overlapping portion 22. Note that in Figures 3A to 3C, the nozzle alignment direction D3 and the width direction D2 are parallel. Here, nozzle row 20C4 of print head 19C is referred to as the first nozzle row, and nozzle row 20C5 is referred to as the second nozzle row.

[0043] For convenience, in FIGS. 3A to 3C, nozzle numbers are assigned to the nozzles 21 constituting one nozzle row in order from left to right along the nozzle arrangement direction D3. Note that a nozzle 21 with a nozzle number # (number) will also be referred to simply as nozzle # (number). In the example shown in FIG. 3A, each nozzle row is composed of 50 nozzles 21, and a range of six consecutive nozzles #45 to #50 in nozzle row 20C4 and a range of six consecutive nozzles #1 to #6 in nozzle row 20C5 form an overlapping portion 22. That is, in the example of FIG. 3A, n=6. According to the example of FIG. 3A, a range of 38 consecutive nozzles #7 to #44 in each nozzle row corresponds to the normal portion. In FIG. 3A, the nozzle 21 with nozzle number #46 in nozzle row 20C4 and the nozzle 21 with nozzle number #2 in nozzle row 20C5 are surrounded by a dashed line to indicate that they are a nozzle pair in the overlapping portion 22.

[0044] 3A, the first and second nozzles forming a nozzle pair, for example, the nozzle 21 with nozzle number #46 in nozzle row 20C4 and the nozzle 21 with nozzle number #2 in nozzle row 20C5, are positioned in the same position in the width direction D2. Therefore, in an ideal state, the first and second nozzles forming a nozzle pair would be able to eject droplets of the same color at the same position on the medium 30. However, there are individual differences in actual products, and such an ideal state is not always realized.

[0045] 3B and 3C show enlarged schematic views of the overlapping portion 22 and its vicinity as examples of non-ideal conditions. The same explanations as for FIG. 3A will be omitted for FIGS. 3B and 3C. In the example shown in FIG. 3B, the nozzle rows 20C4 and 20C5 are closer to each other in the nozzle alignment direction D3 than in the ideal state of FIG. 3A. In the example shown in FIG. 3C, the nozzle rows 20C4 and 20C5 are farther from each other in the nozzle alignment direction D3 than in the ideal state of FIG. 3A. Therefore, in FIGS. 3B and 3C, the nozzle #46 of the nozzle row 20C4 and the nozzle #2 of the nozzle row 20C5, which form a nozzle pair, are misaligned when viewed from the relative movement direction D1.

[0046] When a print head 19 having alternating normal portions and overlapping portions 22 is used for printing, one color of ink in one raster line is printed by one nozzle 21 in the normal portion, and one color of ink in one raster line is printed by one nozzle pair in the overlapping portion 22. A raster line is a linear image whose longitudinal direction is oriented in the relative movement direction D1, and in the print data, it is a pixel row in which pixels are aligned along the relative movement direction D1. Printing one color of ink in one raster line with one nozzle pair is also called OL (overlap) printing. In OL printing, the two nozzles 21 that form one nozzle pair are used, for example, at a usage ratio of 50% each.

[0047] In the print result reproduced on the medium 30, density differences are likely to occur between the area formed by each raster line printed in the normal portion and the area formed by each raster line printed in OL by each nozzle pair in the overlapping portion 22. This is because the number of nozzles used to print each raster line differs between each raster line printed in the normal portion and each raster line printed in OL by the overlapping portion 22, and these differences affect various factors such as ink bleeding, drying, and line thickness, ultimately resulting in density differences. These density differences are perceived by the user as density unevenness.

[0048] In the nozzle alignment direction D3, the boundary B1 (see FIG. 6) between the first print area AR1 printed by the first nozzle row and the second print area AR2 printed by the second nozzle row is within the overlapping area 22. In this example, to minimize the density difference between the print results in the normal area and the overlapping area 22, OL printing is avoided as much as possible in the overlapping area 22. This can be said to avoid using all n nozzle pairs for OL printing. However, it is necessary to avoid the occurrence of gaps in the width direction D2 between the first print area AR1 printed by the first nozzle row and the second print area AR2 printed by the second nozzle row due to OL printing not being performed. Therefore, the range of use of the first and second nozzles is first determined based on a first test pattern without flow prevention dots. Hereinafter, the test pattern may be abbreviated as TP, and the first test pattern may be abbreviated as first TP.

[0049] 4 is a flowchart showing a schematic example of the nozzle use range determination process that the control unit 11 performs in accordance with the program 12. Here, steps S100 to S110 correspond to the first test pattern printing step ST1, and steps S120 to S130 correspond to the use range determination step ST2. Hereinafter, the word "step" may be omitted, and the step number shown in parentheses. The nozzle use range determination process begins when the control unit 110 receives an instruction to start the nozzle use range determination process via the operation reception unit 14. When the nozzle usage range determination process begins, the control unit 11 acquires first TP print data, which is print data representing the first TP (S100). If the first TP print data is stored in a storage location such as the storage unit 15 or a memory inside or outside the printing device 10, the control unit 11 can acquire the first TP print data from that storage location. The control unit 11 may also acquire the first TP print data by receiving it from an external device via the communication I / F 16. Of course, the control unit 11 may also generate the first TP print data by acquiring image data of the first TP from a storage location or an external device and performing image processing such as resolution conversion, color conversion, and halftone processing on the image data. The process of generating the first TP print data in this way is also included in the acquisition of the first TP print data.

[0050] In this specific example, it is assumed that the print data provided by the control unit 11 to the print head 19 is provided after applying color shift correction, whether it is TP print data or print data representing a user-specified image. Here, we will briefly explain color shift correction. For example, the print heads 19C, 19M, 19Y, and 19K shown in FIG. 2 may have errors in their installation positions in the width direction D2. In this case, using the K ink image printed by print head 19K as a reference, the amount of misalignment in the width direction D2 between the C ink image, M ink image, and Y ink image printed by print heads 19C, 19M, and 19Y is obtained. Then, shift correction is applied to the print data provided to each of the print heads 19C, 19M, and 19Y to eliminate the amount of misalignment of each of the C, M, and Y inks relative to K in the width direction D2, resulting in a print result on the medium 30 in which the misalignment between the C, M, and K colors is compensated for. In the print data to which the shift correction between colors has been applied, it is determined which nozzle 21 in which nozzle row of which print head 19 each raster line of each CMYK color is assigned.

[0051] After acquiring the first TP print data, the control unit 11 causes the transport unit 17 to start transporting the medium 30, and controls the print head 19 based on the first TP print data to print a first TP on the medium 30 for determining the range of use of the first and second nozzles in the overlapping portion 22 (S110). At this time, the control unit 11 causes the TP to be printed with m "specific nozzle pairs" that use the first and second nozzles of the nozzle pairs in the overlapping portion 22 to eject the first liquid LQ1, where 0≦m <nである。

[0052] 5A to 5C schematically illustrate a portion of the first nozzle row and second nozzle row in an ideal state in the print head 19C, and the first TP31 printed in S110. First, a description common to FIGS. 5A to 5C will be provided. The printed result, the first TP31, is a plain image printed with one color of ink; in FIGS. 5A to 5C, it is printed using C ink. The first TP31 shown in FIGS. 5A to 5C is printed not with the normal portion but with the overlapping portion 22. However, the first TP31 may include an area printed with the normal portion in addition to the area printed with the overlapping portion 22. In FIGS. 5A to 5C, the numbers 0, +1, −1, etc. written in parentheses next to the reference numeral 31 represent the adjustment values ​​for the ranges of use of the first and second nozzles adopted by the control unit 11 when printing the first TP31. Also, in FIGS. 5A to 5C, among the nozzles 21 in the overlapping portion 22, the “used nozzles” that ejected ink to print the first TP31 are simply indicated by circles, while the “unused nozzles” that did not eject ink to print the first TP31 are indicated by an “X” in a circle.

[0053] As shown in FIG. 5A, the first TP31(0) corresponding to adjustment value = 0 prints in the overlapping portion 22 with nozzle numbers #45 to #47 of nozzle row 20C4 as active nozzles, nozzle numbers #48 to #50 as inactive nozzles, and nozzle numbers #1 to #3 of nozzle row 20C5 as inactive nozzles and nozzle numbers #4 to #6 as active nozzles. When printing the first TP31(0), there are 0 specific nozzle pairs, i.e., m = 0. Therefore, the first TP31(0) does not include raster lines printed in OL. Thus, when adjustment value = 0, under the ideal conditions shown in FIG. 5A, printing in the overlapping portion 22 can be said to be substantially the same as printing in the normal portion.

[0054] As shown in FIG. 5B, the first TP31(+1), which corresponds to an adjustment value of +1, is printed in the overlapping portion 22 with nozzle numbers #45 to #48 of nozzle row 20C4 as the used nozzles, nozzle numbers #49 and #50 as the unused nozzles, and nozzle numbers #1 to #3 of nozzle row 20C5 as the unused nozzles, and nozzle numbers #4 to #6 as the used nozzles. When printing the first TP31(+1), there is one specific nozzle pair, i.e., m=1. According to FIG. 5B, nozzle #48 of nozzle row 20C4 and nozzle #4 of nozzle row 20C5 correspond to the specific nozzle pair, and the first TP31(+1) includes a raster line printed in OL by this specific nozzle pair.

[0055] In general, OL printing is performed by allocating approximately 50% of the data for the multiple pixels that make up one raster line to be printed by each of the two nozzles that make up a nozzle pair to each of the two nozzles that make up that nozzle pair. In contrast, in TP printing in step S110, the control unit 11 allocates 100% of the data for the multiple pixels that make up one raster line to each of the first and second nozzles that make up a specific nozzle pair. Therefore, in the example of FIG. 5B, the same raster line is printed overlappingly by nozzle #48 of nozzle row 20C4 and nozzle #4 of nozzle row 20C5.

[0056] As shown in FIG. 5C, the first TP31(-1) corresponding to an adjustment value of -1 prints in the overlapping portion 22 with nozzle numbers #45 and #46 of nozzle row 20C4 as active nozzles, nozzle numbers #47 to #50 as inactive nozzles, nozzle numbers #1 to #3 of nozzle row 20C5 as inactive nozzles, and nozzle numbers #4 to #6 as active nozzles. When printing the first TP31(-1), m=0, just like the first TP31(0), and the first TP31(-1) does not include OL-printed raster lines. Furthermore, a negative adjustment value indicates the existence of a "non-active nozzle pair" in which both the first and second nozzles are non-active nozzles. When the adjustment value is -1, there is only one non-active nozzle pair. According to FIG. 5C, nozzle #47 of nozzle row 20C4 and nozzle #3 of nozzle row 20C5 correspond to the non-active nozzle pair. If there is an unused nozzle pair, the raster lines of the print data that correspond to the positions of the unused nozzle pair are not printed.

[0057] In S110, the control unit 11 controls the print head 19 to print multiple first TPs 31 with different adjustment values, such as a first TP31(0), a first TP31(+1), and a first TP31(-1), onto the medium 30. Although not shown, the control unit 11 may also control the print head 19 to print a first TP31(+2) with an adjustment value of +2 or a first TP31(-2) with an adjustment value of -2. When the adjustment value is +2, m=2, and in addition to the nozzle pair of nozzle #48 of nozzle row 20C4 and nozzle #4 of nozzle row 20C5, the nozzle pair of nozzle #49 of nozzle row 20C4 and nozzle #5 of nozzle row 20C5 also becomes a specific nozzle pair. On the other hand, when the adjustment value is -2, m is 0, and in addition to the nozzle pair between nozzle #47 of nozzle row 20C4 and nozzle #3 of nozzle row 20C5, the nozzle pair between nozzle #46 of nozzle row 20C4 and nozzle #2 of nozzle row 20C5 also becomes an unused nozzle pair. When generating two or more specific nozzle pairs within the overlapping portion 22, the control unit 11 generates these multiple specific nozzle pairs so that they are consecutive in the nozzle alignment direction D3. Similarly, when generating two or more non-used nozzle pairs within the overlapping portion 22, the control unit 11 generates these multiple non-used nozzle pairs so that they are consecutive in the nozzle alignment direction D3.

[0058] After printing the first TP, the control unit 11 acquires the read result of the first TP 31 on the medium 30 (S120). If the user visually evaluates the first TP 31, the control unit 11 may acquire the read result selected from among first TP 31(0), first TP 31(+1), first TP 31(-1), etc. via the operation reception unit 14. Here, the area printed by the first nozzle row in the first TP 31 will be referred to as the first print area AR1, and the area printed by the second nozzle row will be referred to as the second print area AR2. In the first TP 31, the user evaluates the density of a "specific area 32" from the "first print position" of the first print area AR1, which is the print position of the first nozzle closest to the second print area AR2, to the "second print position" of the second nozzle closest to the first print area AR1, which is the print position of the second nozzle closest to the first print area AR2. In Figures 5A to 5C, the specific area 32 of the first TP 31 is shown surrounded by a dashed line. A mark such as a broken line that clearly indicates the specific area 32 may or may not be printed together with the first TP 31 in S110.

[0059] For the first TP31(0), in the first print region AR1 printed by the nozzle row 20C4, the print position printed by nozzle #47 is closest to the second print region AR2 printed by the nozzle row 20C5. Therefore, the print position printed by nozzle #47 corresponds to the first print position. Also, in the second print region AR2 printed by the nozzle row 20C5, the print position printed by nozzle #4 is closest to the first print region AR1 printed by the nozzle row 20C4. Therefore, the print position printed by nozzle #4 corresponds to the second print position. Therefore, in the first TP31(0), the area in the width direction D2 from the first print position printed by nozzle #47 of the nozzle row 20C4 to the second print position printed by nozzle #4 of the nozzle row 20C5 corresponds to the specific region 32.

[0060] For the first TP31(+1), the printing position on the medium 30 by nozzle #48 of nozzle row 20C4 corresponds to the first printing position, and the printing position on the medium 30 by nozzle #4 of nozzle row 20C5 corresponds to the second printing position. Therefore, within the first TP31(+1), the area in the width direction D2 from the first printing position by nozzle #48 of nozzle row 20C4 to the second printing position by nozzle #4 of nozzle row 20C5 corresponds to the specific area 32. As shown in FIG. 5B, in an ideal situation, the first printing position and the second printing position are the same, so the specific area 32 is an area equivalent to one raster line.

[0061] For the first TP31(-1), the printing position on the medium 30 by nozzle #46 of nozzle row 20C4 corresponds to the first printing position, and the printing position on the medium 30 by nozzle #4 of nozzle row 20C5 corresponds to the second printing position. Therefore, within the first TP31(-1), the area in the width direction D2 from the first printing position by nozzle #46 of nozzle row 20C4 to the second printing position by nozzle #4 of nozzle row 20C5 corresponds to the specific area 32.

[0062] When the adjustment value described above is increased, raster lines printed by specific nozzle pairs in OL appear in the first TP 31, making it more likely that "black streaks" as illustrated in FIG. 5B will appear in the specific region 32. Black streaks refer to "dark streaks" that are denser than neighboring colors in the first TP 31, i.e., streaky irregularities of a dark color, and are not necessarily black. Conversely, when the adjustment value is decreased, the first TP 31 is printed by the overlapping portion 22 including unused nozzle pairs, making it more likely that "white streaks" as illustrated in FIG. 5C will appear in the specific region 32. White streaks refer to "light streaks" that are denser than neighboring colors in the first TP 31, i.e., streaky irregularities of a light color, and are not necessarily white. White streaks refer to light streaks that reveal the background color components of the medium 30. However, the adjustment value that does not produce streaks, the adjustment value that produces black streaks, and the adjustment value that produces white streaks vary depending on factors such as the positional error between nozzle rows in the width direction D2. Therefore, the control unit 11 performs a process to acquire the reading results via the operation reception unit 14. At this time, the user visually evaluates the multiple first TPs 31 on the medium 30, selects the first TP 31 with the best image quality, and can notify the control unit 11 of the selection result by operating the operation reception unit 14. Good image quality means that white or black streaks are not noticeable. Even if the user does not clearly recognize the specific area 32 within the first TP 31, the first TP 31 with strong black or white streaks in the specific area 32 will not be selected, and a first TP 31 with no or barely noticeable black or white streaks in the specific area 32 will be selected. This can be interpreted as the user reading the specific area 32.

[0063] To make it easier for the user to select a first TP 31, each first TP 31 with a different adjustment value may be printed with identification information such as a number, name, or adjustment value. The user may input the identification information of the selected first TP 31 through the operation reception unit 14 and notify the control unit 11. The process of obtaining the selection result of the first TP 31 from the user corresponds to obtaining the read result of the first TP 31 in S120. Furthermore, the first TP 31 may not be read visually by the user, but may be read by a reading device (not shown), such as a scanner or colorimeter, and the read image data and colorimetric values ​​as the read result may be transmitted from the reading device to the printing device 10 via the communication I / F 16. In other words, in S120, the control unit 11 may obtain the read result of the first TP 31 from the reading device.

[0064] After obtaining the reading results, the control unit 11 determines the range of use of the first nozzles and the range of use of the second nozzles in accordance with the reading results (S130). When the control unit 11 obtains the selection result of the first TP31 from the user, the control unit 11 determines the range of use of the first nozzles and the range of use of the second nozzles employed when printing the first TP31 selected by the user. For example, if the user selects the first TP31(+1), as shown in FIG. 5B, the control unit 11 determines the range of nozzle numbers #45 to #48 of the nozzle row 20C4 in the overlapping portion 22 as the range of use of the first nozzles in the overlapping portion 22, and determines the range of nozzle numbers #4 to #6 of the nozzle row 20C5 in the overlapping portion 22 as the range of use of the second nozzles in the overlapping portion 22. In this case, there is one specific nozzle pair used for OL printing within the overlapping portion 22. When the control unit 11 acquires the scanned image data and colorimetric values ​​as the scanning results of the first TP 31 from the scanning device, it analyzes the scanning results for each first TP 31, evaluates the presence and degree of black and white streaks in the specific area 32 based on predetermined evaluation criteria, and selects the first TP 31 with the best image quality. In other words, the control unit 11 executes the selection of the first TP 31 made by the user as described above in accordance with the program 12. Then, the control unit 11 determines the usage range of the first nozzle and the usage range of the second nozzle for the overlapping area 22 to be the usage ranges adopted when printing the selected first TP 31. In this way, in S120 and S130, the control unit 11 determines the usage range of the first nozzle and the usage range of the second nozzle based on the density of the specific area 32 of the first TP 31 printed on the medium 30.

[0065] In the example of FIGS. 5A to 5C, the use range of the nozzles 21 in the nozzle row 20C5 serving as the second nozzle row is fixed regardless of the adjustment value, while the use range of the nozzles 21 in the nozzle row 20C4 serving as the first nozzle row is changed in accordance with the adjustment value within the overlapping portion 22. Of course, when printing the first TP31, the control unit 11 may fix the use range of the nozzles 21 in the first nozzle row and change the use range of the nozzles 21 in the second nozzle row in accordance with the adjustment value. In this way, when changing the use range of the nozzles 21 in only one of the first and second nozzle rows in the overlapping portion 22, the use ranges of the first and second nozzles are determined by determining the use range of the nozzles 21 in the nozzle row whose use range is variable. Of course, the control unit 11 may change the use range of the nozzles 21 in the first nozzle row and the use range of the nozzles 21 in the second nozzle row in accordance with the adjustment value when printing the first TP31.

[0066] Once the control unit 11 has determined the ranges of use for the first and second nozzles, it saves the determination and ends the nozzle use range determination process shown in Figure 4. Determining the ranges of use also determines the ranges of non-use for the nozzles 21. For the normal portion, all nozzles 21 are in the range of use, so there is no need to determine the ranges of use and non-use again. The control unit 11 performs the nozzle use range determination process shown in Figure 4 for all overlapping portions 22 of print heads 19C, 19M, 19Y, and 19K, and determines the ranges of use for the first and second nozzles for each overlapping portion 22. Thereafter, when the control unit 11 executes printing in response to a user instruction, it performs printing by adopting the range determined as described above as the range of use of the first nozzles and the second nozzles in the overlapping portion 22.

[0067] As a result, for a combination of the medium 30 used for printing and the liquid LQ0, it is possible to minimize the number of specific nozzle pairs that perform OL printing within the overlapping portion 22, and to prevent degradation of image quality due to uneven density such as black streaks or white streaks in the print results from the overlapping portion 22. As a result, the problem of noticeable density differences between the area printed by the normal portion and the area printed by the OL printing by the overlapping portion 22 is also solved.

[0068] However, it was found that when the combination of the medium 30 and the liquid LQ0 is changed, faint streaks appear between the nozzle rows along the relative movement direction D3 of the medium 30, even if the range of use of the first and second nozzles is determined based on the density of the specific region 32 of the first TP 31. In particular, when the wettability of the liquid LQ0 to the medium 30 is low, such as when UV (ultraviolet) ink or resin ink is ejected onto the medium 30, or when ink is ejected onto a resin medium, faint streaks 50 are likely to appear, as illustrated in FIG. 14 . The wettability of the liquid LQ0 to the medium 30 can be quantified by the contact angle of a droplet placed on the medium. A larger contact angle indicates lower wettability, and a smaller contact angle indicates higher wettability. The lower the wettability, the stronger the medium 30's tendency to repel the liquid LQ0, and the higher the wettability, the weaker the medium 30's tendency to repel the liquid LQ0.

[0069] FIG. 14 schematically illustrates the behavior of the first liquid LQ1 on the medium 30 when the wettability of the liquid LQ0 with respect to the medium 30 is low. FIG. 14 also schematically illustrates a main portion of a print head 19 having a first nozzle row 201 on the upstream side S1 and a second nozzle row 202 on the downstream side S2, as well as a main portion of a printed image 45 that does not have flow prevention dots DT1 compared to the example in FIG. 6. The bottom of FIG. 14 schematically illustrates print data 40 for causing the print head 19 to eject the first liquid LQ1. For convenience of illustration, FIG. 14 shows the nozzle rows (201, 202) in an ideal state, but if the nozzle rows (201, 202) are not in an ideal state, the first liquid LQ1 will be ejected according to the usage range determined in the nozzle usage range determination process of FIG. 4. As described above, the first nozzles 211 are aligned in the nozzle alignment direction D3 in the first nozzle row 201, and the second nozzles 212 are aligned in the nozzle alignment direction D3 in the second nozzle row 202. The range of use of both nozzles (211, 212) in the overlapping portion 22 is determined according to the first TP31. In the nozzle alignment direction D3, the boundary B1 between the first print region AR1 formed by the first nozzle row 201 and the second print region AR2 formed by the second nozzle row 202 is within the range of the overlapping portion 22.

[0070] Here, as shown in the lower part of FIG. 14, it is assumed that the print data 40 indicates that the first liquid LQ1 is to be ejected seamlessly from the first print region AR1 to the second print region AR2. When the control unit 11 controls the driving of the print head 19 in accordance with the print data 40, the first liquid LQ1 ejected from the first nozzle row 201 on the upstream side S1 lands on the medium 30 first, and after a predetermined period, the first liquid LQ1 ejected from the second nozzle row 202 on the downstream side S2 lands on the medium 30. If the wettability of the liquid LQ1 with respect to the medium 30 is low, the first liquid LQ1 on the first print region AR1 will land before the first liquid LQ1 on the second print region AR2, and as a result, the first liquid LQ1 will flow and gather in the first print region AR1. In FIG. 14, the impact range of the first liquid LQ1 outside the first print region AR1 is indicated by a two-dot chain line. As indicated by the arrow within the two-dot chain line, it can be seen that the first liquid LQ1 on the first printing region AR1 flows away from the boundary B1. As a result, the first liquid LQ1 that later lands in the second printing region AR2 does not connect with the first liquid LQ1 on the first printing region AR1, and a faint streak 50 appears between the nozzle rows along the direction D1 of relative movement of the medium 30.

[0071] 6, the control unit 11 controls the first nozzle 211 included in the first nozzle row 201 on the upstream side S1 as the flow prevention dot forming nozzle NZ2 to form the flow prevention dots DT1 in the second printing area AR2. This makes it possible to suppress the above-mentioned faint streaks 50.

[0072] FIG. 6 schematically illustrates the main parts of the print head 19 and the main parts of the printed image 45. The lower part of FIG. 6 schematically illustrates print data 41 for causing the first nozzle row 201 to eject the first liquid LQ1, and print data 42 for causing the second nozzle row 202 to eject the first liquid LQ1. For convenience of illustration, FIG. 14 shows the nozzle rows (201, 202) in an ideal state, but if the nozzle rows (201, 202) are not in an ideal state, the usage range determined in the nozzle usage range determination process of FIG. 4 will be followed. FIG. 7 schematically illustrates the spacing between flow prevention dots DT1 in the relative movement direction D1. Nozzle #48 of the first nozzle row 201 shown in FIG. 6 is located in the second print region AR2 and is located at the end of the second print region AR2 on the first print region AR1 side in the nozzle alignment direction D3. FIG. 6 shows that nozzle #48 of the first nozzle row 201 is not an unused nozzle, but is used as a flow prevention dot forming nozzle NZ2 to form flow prevention dots DT1. Of the multiple first nozzles 211, nozzles #42 to #47 (#42 to #47 in FIG. 6) located in the first print region AR1 will be referred to as normal nozzles NZ1. The multiple first nozzles 211 shown in FIG. 6 include multiple normal nozzles NZ1 located in the first print region AR1 and a flow prevention dot forming nozzle NZ2 located at the end of the second print region AR2 on the first print region AR1 side. The control unit 11 can accept a setting for whether or not to form flow prevention dots DT1 via the operation accepting unit 14. Here, it is assumed that the setting indicates the formation of flow prevention dots DT1. In this case, the control unit 11 causes the print head 19 to form a plurality of flow preventing dots DT1 that are not adjacent to each other in the relative movement direction D1 using the first liquid LQ1 ejected onto the medium 30 from the flow preventing dot formation nozzles NZ2 during printing.

[0073] As shown in FIG. 7, the print data 40 defines pixels PX1 as units in which dots, including flow prevention dots DT1, are arranged. A pixel is the smallest element of an image, to which a color can be independently assigned. A pixel PX1 represents a unit area that defines the formation position of each dot for a certain color, such as C. It can also be said that for a certain color, each pixel PX1 is assigned the ability to place a single dot. When multiple flow prevention dots DT1 are not adjacent to each other in the relative movement direction D1, this means that no flow prevention dots DT1 are arranged in adjacent pixels PX1 in the relative movement direction D1. If the ratio of the number of dots to the number of pixels is called the recording rate, when multiple flow prevention dots DT1 are not adjacent to each other in the relative movement direction D1, the recording rate of the flow prevention dots DT1 in the relative movement direction D1 is greater than 0% but less than 50%.

[0074] As shown in FIG. 7, the spacing between the flow prevention dots DT1 in the relative movement direction D1 may be set to various values, such as two dots for a maximum recording rate of 50%, three dots for a maximum recording rate of 33%, or four dots for a maximum recording rate of 25%. If the spacing between the flow prevention dots DT1 in a print image with a recording rate of 100% is two dots, the flow prevention dots DT1 are formed every other dot, i.e., every other pixel, in the relative movement direction D1. If the recording rate of the print image is less than 100%, the flow prevention dots DT1 are formed at positions where normal dots would be formed in the print image, but are not formed at positions where no dots would be formed in the print image. Therefore, the recording rate of the flow prevention dots DT1 decreases depending on the recording rate of the print image. The spacing between the multiple flow prevention dots DT1 is preferably approximately equal. FIG. 7 shows that the spacing between the flow prevention dots DT1 is equal. Because the flow prevention dots DT1 may be arranged in pixel PX1 units, variations of one dot may occur depending on the recording rate of the flow prevention dots DT1. "Approximately equal spacing" means that the spacing between the flow prevention dots DT1 varies by one dot or less. For example, if the recording rate of the flow prevention dots DT1 is 40%, the spacing between the flow prevention dots DT1 that are approximately equal will be two or three dots. If the recording rate of the flow prevention dots DT1 is 30%, the spacing between the flow prevention dots DT1 that are approximately equal will be three or four dots. The reason why the spacing between the flow prevention dots DT1 is preferably approximately equal is that variations in the spacing between the multiple flow prevention dots DT1 that exceed approximately equal spacing may degrade the image quality of the printed image 45. Where the gap is narrow, the first liquid LQ1 in the first printing region AR1 and the first liquid LQ1 in the second printing region AR2 may join together, whereas where the gap is wide, the first liquid LQ1 in the first printing region AR1 and the first liquid LQ1 in the second printing region AR2 may not join together. In this case, the printed image 45 is disturbed at the boundary B1 between the first printing region AR1 and the second printing region AR2, resulting in a decrease in the image quality of the printed image 45.

[0075] In the lower part of FIG. 6, the print data 40 is shown as having a dot recording rate of 100%. The control unit 11 assigns dot data for forming dots on the medium 30 to each nozzle 21 based on the print data 40, and in addition to this dot data, assigns flow prevention dot data to the flow prevention dot forming nozzle NZ2. The dot data is multi-valued data that represents the dot formation state, such as binary data representing whether or not a dot is formed. Binary dot data can be, for example, data representing "1" indicating dot formation or "0" indicating dot absence. Multi-valued dot data can be, for example, quaternary data representing "3" indicating large dot formation, "2" indicating medium dot formation, "1" indicating small dot formation, or "0" indicating dot absence. The flow prevention dot data is dot data for forming flow prevention dots DT1 at the end of the second printing area AR2 on the medium 30 on the side of the first printing area AR1.

[0076] The print data 42 shown in FIG. 6 is dot data assigned to nozzles #4 through #9 of the second nozzle row 202 to form dots in the second print region AR2. The print data 41 shown in FIG. 6 is dot data that adds flow prevention dot data to the dot data assigned to nozzles #4 through #47 of the first nozzle row 201 to form dots in the first print region AR1 (nozzles #42 through #47 in FIG. 6). The flow prevention dot data is assigned to nozzle #48 of the first nozzle row 201 to form flow prevention dots DT1 in the second print region AR2, not in the first print region AR1. Therefore, the print data 41 is dot data that combines dot data assigned to the normal nozzle NZ1 in the first print region AR1 and flow prevention dot data assigned to the flow prevention dot forming nozzle NZ2 in the second print region AR2. Therefore, according to the data, at the end of the second printing area AR2 on the first printing area AR1 side, the first liquid LQ1 ejected from the flow prevention dot forming nozzle NZ2 will be superimposed on the first liquid LQ1 ejected from nozzle #4 of the first nozzle row 201.

[0077] If the liquid LQ0 has low wettability with respect to the medium 30 and there are no flow prevention dots DT1, the first liquid LQ1 that lands in the first printing region AR1 before the second printing region AR2 will flow and gather on the medium 30, resulting in light streaks 50, as shown in Figure 14. Here, if the first liquid LQ1 is ejected from the flow prevention dot formation nozzle NZ2 in the second printing region AR2 of the first nozzle row 201 so as to form continuous dots in the relative movement direction D1, dark streaks such as black streaks will appear. Because the multiple flow prevention dots DT1 are not adjacent to one another in the relative movement direction D1, the first liquid LQ1 in the first printing region AR1 and the first liquid LQ1 in the second printing region AR2 are appropriately connected, and the light streaks 50 are suppressed. Due to the above-described effects, this specific example can prevent the generation of faint streaks between nozzle rows along the relative movement direction D1 of the medium 30 due to the flow of dots on the medium 30.

[0078] As shown in Fig. 8, the size of the flow prevention dot DT1 may be set to various sizes such as large dots, medium dots, small dots, etc. Fig. 8 shows a schematic example of the size of the flow prevention dot DT1. As shown in FIG. 9, the number of flow prevention dot forming nozzles NZ2 may be set to various numbers, such as one nozzle, two nozzles, or three nozzles. FIG. 9 schematically illustrates the number of flow prevention dot forming nozzles NZ2. The flow prevention dot forming nozzle NZ2 is set at a position adjacent to the normal nozzles NZ1 in the first nozzle row 201. When there is one flow prevention dot forming nozzle NZ2, the flow prevention dot forming nozzle NZ2 is adjacent to the normal nozzle NZ1 in the width direction D2. When there are two flow prevention dot forming nozzles NZ2, the flow prevention dot forming nozzle NZ2 is a combination of a nozzle adjacent to the normal nozzle NZ1 and a nozzle adjacent to that nozzle (other than the normal nozzle NZ1) in the width direction D2.

[0079] FIG. 10 is a flowchart illustrating the adjustment process performed by the control unit 11 in accordance with the program 12. The adjustment process is performed on the assumption that the nozzle usage range determination process shown in FIG. 4 has been performed. Here, S204 corresponds to the size setting reception process ST4. S206 corresponds to the second test pattern printing process ST5 and the flow prevention dot formation process ST3. This is because the second TP35 including flow prevention dots DT1 is formed when streaks 50 caused by the flow of the first liquid LQ1 occur between the printing areas (AR1, AR2) during printing of the first TP31 without using the flow prevention dot formation nozzle NZ2. S208 to S210 correspond to the spacing determination process ST6. FIG. 11 illustrates a schematic example of the print head 19 and the main components of the second test pattern 35. Hereinafter, the second test pattern may be abbreviated as second TP. The following describes the process for determining the formation conditions for flow prevention dots DT1 for a certain overlapping portion 22 included in print head 19C. Of course, the nozzle usage range determination process may be performed for each of the multiple overlapping portions 22 included in print head 19C, or may be performed for print heads 19M, 19Y, and 19K.

[0080] The adjustment process may be started when the control unit 110 receives an instruction to start the adjustment process via the operation reception unit 14. Alternatively, the start of the adjustment process may be triggered by the control unit 11 detecting that at least one of the type of medium 30 and the type of first liquid LQ1 has been changed. By performing the second TP formation process of S208, the printing device 10 will form the second TP 35 when at least one of the type of medium 30 and the type of first liquid LQ1 has been changed. The wettability of the liquid LQ0 with respect to the medium 30 depends on the combination of the type of medium 30 and the type of the liquid LQ0. Therefore, changing at least one of the type of medium 30 and the type of the first liquid LQ1 can change the degree to which the dots on the medium 30 flow. When the second TP35 is formed by changing at least one of the type of medium 30 and the type of the first liquid LQ1, the faint streaks 50 caused by the flow of the dots on the medium 30 can be suppressed in accordance with the second TP35.

[0081] When the adjustment process starts, the control unit 11 displays a user interface screen (not shown) on the display unit 13 and accepts a selection of whether or not to form flow-preventing dots DT1 via the operation reception unit 14 (S202). For example, if a light streak 50 appears in the printed image 45 (including the first TP31) formed on the medium 30 according to the determined usage range, the user can operate the operation reception unit 14 to form flow-preventing dots DT1. If a light streak 50 does not appear in the printed image 45 or if its presence is not a problem, the user can operate the operation reception unit 14 to not form flow-preventing dots DT1. If the selection of not forming flow-preventing dots DT1 is made, the control unit 11 ends the adjustment process.

[0082] If forming flow prevention dots DT1 is selected, the control unit 11 accepts settings such as the size of the flow prevention dots DT1 via the operation acceptance unit 14 (S204). The control unit 11 then acquires original print data representing the second TP35, generates print data 40 from the original print data according to the settings such as the size of the flow prevention dots DT1, and forms the second TP35 including the flow prevention dots DT1 on the medium 30 (S206). If the original print data is stored in a storage location such as the storage unit 15 or a memory inside or outside the printing device 10, the control unit 11 can acquire the original print data from that storage location. The control unit 11 may also acquire the original print data by receiving it from an external device via the communication I / F 16. Of course, the control unit 11 may also generate the original print data by acquiring image data of the second TP from a storage location or an external device and performing image processing such as resolution conversion, color conversion, and halftone processing on the image data. The process of generating the original print data in this manner is also included in acquiring the original print data.

[0083] As shown in FIG. 11, the second TP35 is formed including flow prevention dots DT1 by the first liquid LQ1 ejected onto the medium 30 from the first nozzle array 201 and the second nozzle array 202. The second TP35 shown in FIG. 11 includes multiple individual patterns 36 in which the spacing between the flow prevention dots DT1 in the relative movement direction D1 is varied. For example, individual pattern 36a includes multiple flow prevention dots DT1 spaced at a dot spacing of two dots as shown in FIG. 7. Individual pattern 36b includes multiple flow prevention dots DT1 spaced at a dot spacing of three dots as shown in FIG. 7. Individual pattern 36c includes multiple flow prevention dots DT1 spaced at a dot spacing of four dots as shown in FIG. 7. FIG. 11 shows that the dot recording rate of individual pattern 36a (50%), the dot recording rate of individual pattern 36b (33%), and the dot recording rate of individual pattern 36a (25%) are also formed on the medium 30.

[0084] For example, as shown in FIG. 8 , when dot sizes include large dots, medium dots, and small dots, the user can set the size of the flow prevention dots DT1 to large dots, medium dots, or small dots via the operation reception unit 14. When the large dot setting operation is received, the control unit 11 causes the print head 19 to form multiple large flow prevention dots DT1 in the second TP35 shown in FIG. 11 . When the small dot setting operation is received, the control unit 11 causes the print head 19 to form multiple small flow prevention dots DT1 in the second TP35. For example, if faint streaks 50 are observed even when multiple flow prevention dots DT1 are formed as small dots, the size of the flow prevention dots DT1 can be increased. Increasing the size of the flow prevention dots DT1 increases the amount of first liquid LQ1 ejected from the first nozzle row 201 toward the end of the second printing region AR2 on the first printing region AR1 side, thereby reducing the faint streaks 50. Therefore, streaks along the relative movement direction D1 between the nozzle rows are more appropriately suppressed. In this way, when streaks 50 occur between the printing areas (AR1, AR2) due to the flow of the first liquid LQ1 during printing based on the usage range in accordance with the first TP31, the control unit 11 forms multiple flow prevention dots DT1 that are not adjacent to each other in the relative movement direction D1 using the first liquid LQ1 ejected onto the medium 30 from the flow prevention dot formation nozzle NZ2.

[0085] In S204, the control unit 11 may accept a setting operation for the spacing between the flow prevention dots DT1 in the relative movement direction D1 via the operation reception unit 14. When a setting operation for two dots as shown in FIG. 7 is accepted, the control unit 11 may cause the print head 19 to form a second TP35 having at least the individual pattern 36a as shown in FIG. 11. When a setting operation for four dots as shown in FIG. 7 is accepted, the control unit 11 may cause the print head 19 to form a second TP35 having at least the individual pattern 36c as shown in FIG. 11. For example, if light streaks 50 are observed even when multiple flow prevention dots DT1 are formed at intervals of four dots, the spacing between the flow prevention dots DT1 may be narrowed. Narrowing the spacing between the flow prevention dots DT1 increases the amount of first liquid LQ1 ejected from the first nozzle row 201 toward the end of the second printing region AR2 on the first printing region AR1 side, thereby reducing the light streaks 50. Therefore, streaks along the relative movement direction D1 between the nozzle rows are more appropriately suppressed.

[0086] In S204, the control unit 11 may accept an operation to set the number of flow prevention dot forming nozzles NZ2 via the operation reception unit 14. When the operation to set one nozzle, as shown in FIG. 9, is accepted, the control unit 11 causes the print head 19 to form the multiple flow prevention dots DT1 of the second TP35 so that each dot is arranged in the width direction D2. When the operation to set three nozzles, as shown in FIG. 9, is accepted, the control unit 11 causes the print head 19 to form the multiple flow prevention dots DT1 of the second TP35 so that each dot is arranged in the width direction D2. For example, if faint streaks 50 are observed even when a single flow prevention dot forming nozzle NZ2 is used, the number of flow prevention dot forming nozzles NZ2 can be increased. Increasing the number of flow prevention dot forming nozzles NZ2 increases the amount of first liquid LQ1 ejected from the first nozzle row 201 toward the end of the second printing region AR2 on the first printing region AR1 side, thereby reducing the faint streaks 50. Therefore, streaks along the relative movement direction D1 between the nozzle rows are more appropriately suppressed.

[0087] After printing the second TP 35, the control unit 11 acquires the read result of the second TP 35 on the medium 30 (S208). If the user visually evaluates the second TP 35, the control unit 11 may acquire the read result by selecting from the individual patterns 36a-36c via the operation reception unit 14. The individual pattern 36a shown in FIG. 11 has darker stripes along the relative movement direction D1 due to multiple flow prevention dots DT1 spaced two dots apart. The individual pattern 36c shown in FIG. 11 has lighter stripes along the relative movement direction D1 due to multiple flow prevention dots DT1 spaced four dots apart. The individual pattern 36b shown in FIG. 11 has no stripes of varying shades along the relative movement direction D1 due to multiple flow prevention dots DT1 spaced three dots apart. Therefore, the user can select the individual pattern 36b with the best image quality (33%) and notify the control unit 11 of the selection result by operating the operation reception unit 14. The process of acquiring the selection result of the second TP 35 from the user corresponds to acquiring the reading result of the second TP 35 in S208. Furthermore, the second TP 35 may not be read visually by the user but may be read by a reading device (not shown) such as a scanner or a colorimeter, and the read image data and colorimetric values ​​as the reading results may be transmitted from the reading device to the printing device 10 via the communication I / F 16. In other words, in S208, the control unit 11 may acquire the reading result of the second TP 35 from the reading device.

[0088] After acquiring the read results, the control unit 11 determines the formation conditions of the flow prevention dots DT1 based on the read results and saves the determined results (S210). If the control unit 11 acquires the selection result of the second TP35 from the user, it determines the spacing between the flow prevention dots DT1 to be applied to the formation of the print image 45 to be the spacing corresponding to the selection result. Since the print control process illustrated in FIG. 13 is then performed, the control unit 11 determines the spacing between the flow prevention dots DT1 to be applied to the flow prevention dot formation process ST3 based on the second TP35. For example, if the user selects the individual pattern 36b, the control unit 11 determines the spacing between the flow prevention dots DT1 to be applied to the formation of the print image 45 to be three dots. The control unit 11 may perform the adjustment process illustrated in FIG. 10 for all overlapping portions 22 of the print heads 19C, 19M, 19Y, and 19K, and determine the formation conditions of the flow prevention dots DT1 for each overlapping portion 22. Thereafter, when printing is performed in response to a user instruction or the like, the control unit 11 forms the flow preventing dots DT1 under the above-described formation conditions in accordance with the print control process exemplified in FIG. 11, as the spacing between the flow prevention dots DT1 narrows, the amount of first liquid LQ1 ejected from the first nozzle row 201 toward the end of the second printing region AR2 on the side of the first printing region AR1 increases. When faint streaks are visible, as in individual pattern 36c, narrowing the spacing between the flow prevention dots DT1, as in individual pattern 36b, reduces the faint streaks. Therefore, streaks along the direction D1 of relative movement between the nozzle rows are more appropriately suppressed.

[0089] 12 is a flowchart showing a typical example of the print control process performed by the control unit 11 in accordance with the program 12. The print control process is performed on the premise that the adjustment process shown in FIG. 10 has been performed. Here, steps S306 to S308 correspond to the flow prevention dot formation process ST3. The print control process starts when the control unit 110 receives an instruction to start the print control process via the operation reception unit 14. When the print control process starts, the control unit 11 acquires print data 40 representing an image (S302). This print data 40 is not limited to data with a dot recording rate of 100%, but refers to data representing various images with a dot recording rate of less than 100%, such as natural images or photographic images that users may display in their rooms or sell, or document images to be shown to others, such as line drawings for presentations.

[0090] After acquiring the print data 40, the control unit 11 assigns dot data to each nozzle 21 to be used for printing based on the print data 40 (S304). For example, as shown in Fig. 6, the control unit 11 assigns dot data for the first print region AR1 to nozzles #4 through #47 of the first nozzle row 201, and assigns dot data for the second print region AR2, i.e., print data 42, to nozzles #4 through #4 of the second nozzle row 202. At this point, the print data 42 for the second nozzle row 202 is generated. Furthermore, the control unit 11 assigns flow prevention dot data to the flow prevention dot forming nozzle NZ2 based on the print data 40 (S306). For example, if the position where normal dots are assigned at the end of the second print area AR2 on the first print area AR1 side in the print data 42 is the assigned position for flow prevention dots DT1, the control unit 11 assigns this position. In this way, the print data 41 for the first nozzle row 201 is generated.

[0091] Finally, the control unit 11 causes the print head 19 to eject droplets LQ0 in accordance with the print data 40, thereby forming a print image 45 on the medium 30 (S308). Focusing on the print head 19C, the control unit 11 causes the first nozzle row 201 to eject the first liquid LQ1 of C in accordance with the print data 41, and also causes the second nozzle row 202 to eject the first liquid LQ1 of C in accordance with the print data 42. At this time, at the end of the second printing region AR2 on the first printing region AR1 side, a plurality of flow prevention dots DT1 that are not adjacent to each other in the relative movement direction D1 are formed by the first liquid LQ1 of C ejected from the flow prevention dot formation nozzles NZ2 onto the medium 30. In this way, when streaks 50 due to the flow of the first liquid LQ1 occur between the printing areas (AR1, AR2) during printing based on the usage range in accordance with the first TP31, the control unit 11 forms the above-mentioned multiple flow prevention dots DT1.

[0092] As described above, the flow prevention dots DT1 are formed by the first liquid LQ1 ejected from the flow prevention dot forming nozzles NZ2 of the first nozzle row 201 directed toward the first printing region AR1 into the second printing region AR2, thereby suppressing the formation of faint streaks 50 as shown in FIG. 14. Because the multiple flow prevention dots DT1 are not adjacent to one another in the direction of relative movement D1, the first liquid LQ1 in the first printing region AR1 and the first liquid LQ1 in the second printing region AR2 are appropriately connected, suppressing the formation of dark streaks. Therefore, this specific example can suppress the formation of faint streaks along the direction D1 of relative movement of the medium 30 between the nozzle rows due to the flow of dots on the medium 30.

[0093] (3) Variation: The present invention can be embodied in various modifications. The printing device 10 is not limited to a line-type printing device, but may also be a serial-type printing device. For example, if the print head 19 is mounted on a carriage that is movable along the main scanning direction, the print head 19 may have a first nozzle row 201 and a second nozzle row 202. In this case, the relative movement direction D1 is a direction along the main scanning direction, and the transport unit 17 moves the print head 19 in the direction opposite to the relative movement direction D1 without moving the medium 30. Therefore, the transport unit 17 moves the medium 30 relative to the print head 19 in the relative movement direction D1 that intersects with the nozzle arrangement direction D3. 11 includes multiple individual patterns 36 in which the spacing between the flow prevention dots DT1 in the relative movement direction D1 is varied, but the second TP is not limited to the example of FIG. 11. For example, if the second TP includes multiple individual patterns in which the size of the flow prevention dots DT1 is varied, the control unit 11 can determine the size of the flow prevention dots DT1 to be used in the flow prevention dot forming process ST3. If the second TP includes multiple individual patterns in which the number of flow prevention dot forming nozzles NZ2 is varied, the control unit 11 can determine the number of flow prevention dot forming nozzles NZ2 to be used in the flow prevention dot forming process ST3.

[0094] 13, the control unit 11 may perform control to change the flow prevention dot forming nozzle NZ2 to the normal nozzle NZ1. This is because the appropriate range of use of the first nozzle 211 and the second nozzle 212 may change due to changes in the state of the nozzle 21, the environment, etc. 13 is a flowchart schematically illustrating another example of print control processing performed by the control unit 11 in accordance with the program 12. This print control processing also starts when the control unit 110 receives an instruction to start the print control processing via the operation reception unit 14. The flow in FIG. 13 also shows a UI (user interface) screen 500 and the role of the nozzles 21 during printing.

[0095] When the print control process starts, the control unit 11 displays a UI screen 500 on the display unit 13 (S402). The UI screen 500 includes a selection item 501 for forming flow prevention dots DT1 using the flow prevention dot forming nozzle NZ2, a selection item 502 for changing the flow prevention dot forming nozzle NZ2 to the normal nozzle NZ1, an OK button (not shown), and the like. The operation reception unit 14 can accept an operation for either of the selection items 501 or 502. The user can select either of the selection items 501 or 502 by operating either of the selection items 501 or 502 and then operating the OK button. When the selection item 502 is selected, the operation reception unit 14 accepts an operation for changing from the flow prevention dot forming nozzle NZ2 to the normal nozzle NZ1. The control unit 11 accepts a selection operation for either of the selection items 501 or 502 via the operation reception unit 14.

[0096] When the OK button is operated, the control unit 11 branches the process depending on the selection operation for the selection items 501 and 502 (S404). When the control unit 11 accepts the selection operation for the selection item 501, it causes the print head 19 to form a plurality of flow prevention dots DT1 that are not adjacent to each other in the relative movement direction D1 using the flow prevention dot formation nozzle NZ2 during printing (S406), as shown in the flow. On the other hand, when the control unit 11 accepts the selection operation for the selection item 502, it changes the flow prevention dot formation nozzle NZ2 to the normal nozzle NZ1 and causes the print head 19 to form normal dots (S408), as shown in the flow. Therefore, when the operation to change from the flow prevention dot formation nozzle NZ2 to the normal nozzle NZ1 is accepted, the control unit 11 changes the flow prevention dot formation nozzle NZ2 to the normal nozzle NZ1 and controls the ejection of the liquid LQ0 by the print head 19. When the flow prevention dot forming nozzles NZ2 are changed to normal nozzles NZ1, the amount of first liquid LQ1 ejected from the first nozzle row 201 toward the end of the second printing region AR2 on the side of the first printing region AR1 increases. This makes it possible to reduce faint streaks that may be observed even when the flow prevention dots DT1 are formed.

[0097] (4) Conclusion: As explained above, according to the present invention, it is possible to provide, through various aspects, configurations that can prevent the generation of faint streaks between nozzle rows along the direction of relative movement of the medium due to the flow of dots on the medium. Of course, even in an aspect that consists only of the constituent elements of the independent claims, the basic actions and effects described above can be obtained. Furthermore, it is possible to implement configurations in which the components disclosed in the above examples are substituted with each other or the combination is changed, or configurations in which the components disclosed in the publicly known techniques and the above examples are substituted with each other or the combination is changed, etc. The present invention also includes these configurations. [Explanation of symbols]

[0098] 10...printing device, 11...control unit, 12...program, 13...display unit, 14...operation reception unit, 15...memory unit, 16...communication I / F, 17...transport unit, 19...print head, 20C, 20C1, 20C2, 20C3, 20C4, 20C5, 20M, 20Y, 20K...nozzle array, 21...nozzle, 22...overlapping portion, 30...medium, 31...first test pattern, 32...specific area, 35...second test pattern, 36, 36a to 36c...individual patterns, 40, 41, 42...print data, 45...printed image, 50...streak, 201...first nozzle array, 202...second nozzle array, 211...first nozzle 212...second nozzle, 500...user interface screen, AR1...first printing area, AR2...second printing area, B1...boundary, D1...relative movement direction, D2...width direction, D3...nozzle arrangement direction, DT1...flow prevention dot, LQ0...liquid, LQ1...first liquid, NZ1...normal nozzle, NZ2...flow prevention dot forming nozzle, PX1...pixel, S1...upstream side, S2...downstream side, ST1...first test pattern printing process, ST2...usage range determination process, ST3...flow prevention dot forming process, ST4...size setting reception process, ST5...second test pattern printing process, ST6...spacing determination process.

Claims

1. a print head having a first nozzle row in which a plurality of first nozzles capable of ejecting a first liquid onto a medium are aligned in a predetermined nozzle alignment direction, and a second nozzle row in which a plurality of second nozzles capable of ejecting the first liquid onto the medium are aligned in the nozzle alignment direction; a transport unit that moves the medium relative to the print head in a relative movement direction that intersects with the nozzle arrangement direction; a control unit that controls the ejection of a liquid including the first liquid by the print head, the print head has an overlapping portion where a portion of the first nozzle row and a portion of the second nozzle row overlap when viewed from the direction of relative movement, In the overlapping portion, the first nozzle row is located upstream of the second nozzle row in the relative movement direction, a boundary between a first printing area printed by the first nozzle row and a second printing area printed by the second nozzle row is within the overlapping area in the nozzle arrangement direction; the plurality of first nozzles include normal nozzles in the first printing region and flow prevention dot forming nozzles in the second printing region at an end of the second printing region on the first printing region side, The control unit causes the print head to form a plurality of flow prevention dots that are not adjacent to each other in the direction of relative movement using the first liquid ejected from the flow prevention dot formation nozzles onto the medium during printing.

2. an operation receiving unit that receives an operation to change the flow prevention dot forming nozzles to the normal nozzles, The printing device according to claim 1 , wherein, when the change operation is accepted, the control unit changes the flow prevention dot forming nozzles to the normal nozzles and controls the ejection of the liquid by the print head.

3. an operation receiving unit that receives an operation for setting the size of the flow-preventing dots; The printing device according to claim 1 , wherein the control unit, when the setting operation is accepted, causes the print head to form the plurality of flow prevention dots in the size.

4. A printing method in which a medium is moved relative to a print head in a relative movement direction that intersects with a predetermined nozzle arrangement direction, and a liquid including a first liquid is ejected from the print head onto the medium, the print head has a first nozzle row in which a plurality of first nozzles capable of ejecting the first liquid onto the medium are aligned in the nozzle alignment direction, and a second nozzle row in which a plurality of second nozzles capable of ejecting the first liquid onto the medium are aligned in the nozzle alignment direction, the print head has an overlapping portion where a portion of the first nozzle row and a portion of the second nozzle row overlap when viewed from the direction of relative movement, In the overlapping portion, the first nozzle row is located upstream of the second nozzle row in the relative movement direction, a boundary between a first printing area printed by the first nozzle row and a second printing area printed by the second nozzle row is within the overlapping area in the nozzle arrangement direction; the plurality of first nozzles include normal nozzles in the first printing region and flow prevention dot forming nozzles in the second printing region at an end of the second printing region on the first printing region side, A printing method in which, when streaks occur between the first printing area and the second printing area due to the flow of the first liquid during printing without using the flow prevention dot forming nozzle, the first liquid is ejected from the flow prevention dot forming nozzle onto the medium to form multiple flow prevention dots that are not adjacent to each other in the relative movement direction.

5. A printing method in which a medium is moved relative to a print head in a relative movement direction that intersects with a predetermined nozzle arrangement direction, and a liquid including a first liquid is ejected from the print head onto the medium, the print head has a first nozzle row in which a plurality of first nozzles capable of ejecting the first liquid onto the medium are aligned in the nozzle alignment direction, and a second nozzle row in which a plurality of second nozzles capable of ejecting the first liquid onto the medium are aligned in the nozzle alignment direction, the print head has an overlapping portion where a portion of the first nozzle row and a portion of the second nozzle row overlap when viewed from the direction of relative movement, In the overlapping portion, the first nozzle row is located upstream of the second nozzle row in the relative movement direction, where n is an integer of 2 or greater, and a pair of the first nozzle and the second nozzle, whose position in the overlapping portion of the first nozzle row corresponds to a position in the overlapping portion of the second nozzle row, is defined as a nozzle pair, the overlapping portion has n sets of the nozzle pairs aligned in the nozzle alignment direction, The printing method includes: a first test pattern printing step of printing a first test pattern on the medium to determine a usage range of the first nozzles and the second nozzles in the overlapping portion, the first test pattern being printed using m specific nozzle pairs, where m is an integer greater than or equal to 0 and less than n, in which the first nozzles and the second nozzles are used to eject the first liquid; a use range determination step of determining the use range based on the density of a specific area from the first printing position to the second printing position, the first printing position is a printing position of the first nozzle that is closest to a second printing area by the second nozzle row in a first printing area by the first nozzle row in the first test pattern printed on the medium, the second printing position is a printing position of the second nozzle that is closest to the first printing area in the second printing area in the first test pattern printed on the medium, the plurality of first nozzles include normal nozzles in the first printing region and flow prevention dot forming nozzles in the second printing region at an end of the second printing region on the first printing region side, The printing method includes: A printing method further including a flow prevention dot formation process for forming a plurality of flow prevention dots that are not adjacent to each other in the relative movement direction using the first liquid ejected from the flow prevention dot formation nozzle onto the medium when streaks occur between the first printing area and the second printing area due to the flow of the first liquid during printing based on the usage range.

6. a size setting receiving step of receiving a setting of the size of the flow-preventing dot; The printing method according to claim 5 , wherein the flow prevention dot forming step forms the plurality of flow prevention dots in the size.

7. a second test pattern printing process for forming a second test pattern including the flow prevention dots by the first liquid ejected onto the medium from the first nozzle row and the second nozzle row, the second test pattern including a plurality of individual patterns in which the spacing between the flow prevention dots in the relative movement direction is changed; 7. The printing method according to claim 5, further comprising a spacing determination step of determining the spacing between the flow prevention dots to be applied to the flow prevention dot forming step based on the second test pattern.

8. The printing method according to claim 7 , wherein in the second test pattern printing step, the second test pattern is formed when at least one of the type of the medium and the type of the first liquid is changed.

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