Printing device and printing method

Abstract

To suppress density unevenness caused by a difference in distance in a conveying direction between nozzles that are used for forming adjacent raster lines.SOLUTION: In a printing process of forming a plurality of raster lines in parallel on a medium in a width direction, a control part makes second nozzles of a second nozzle row form a raster line at a first area side of raster lines arranged adjacently at a boundary between the first area and a second area in the width direction and makes first nozzle of a first nozzle row form a raster line at the second area side of the raster lines arranged adjacently at the boundary, where an area in which the first nozzle row and the second nozzle row can form the raster lines is defined as the first area and an area in which the third nozzle row and a fourth nozzle row can form the raster lines is defined as the second area, of an image expressed by print data.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a printing apparatus and a printing method. [Background technology]

[0002] 2. Description of the Related Art Inkjet printers are known that perform printing using a print head that has a plurality of nozzles capable of ejecting dots of liquid onto a medium.

[0003] Also, a full line printer has been disclosed in which nozzles are arranged in a staggered pattern alternately on the upstream and downstream sides of the transport direction of the medium, forming a long head by connecting multiple nozzle groups consisting of an upstream nozzle row and a downstream nozzle row in a direction perpendicular to the transport direction (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-29146 A Summary of the Invention [Problem to be solved by the invention]

[0005] According to the above-mentioned document 1, the nozzle positions of the two nozzle rows in a nozzle group are shifted from each other in a direction perpendicular to the transport direction, i.e., in the longitudinal direction of the long head, so that one nozzle group can essentially be regarded as one nozzle row.

[0006] On the other hand, a print head configuration is also known that has nozzle rows on both the upstream and downstream sides of the transport direction, and can form long raster lines at the same position along the transport direction using either of these nozzle rows. With this configuration, in terms of print resolution, it is sufficient to use either the upstream or downstream nozzle row. However, when either one of the nozzle rows is used, the distance in the transport direction between the nozzles used to form adjacent raster lines may differ greatly between the joint between the nozzle rows in the longitudinal direction of the head and the other part. Such variation in the distance between the nozzles used to form adjacent raster lines creates a time difference in the formation timing of each raster line, which causes striped density unevenness. Therefore, improvements are required to suppress such density unevenness. [Means for solving the problem]

[0007] The printing device includes a first nozzle row and a third nozzle row in which a plurality of first nozzles capable of ejecting dots of liquid onto a medium are arranged in a predetermined first direction, and a second nozzle row and a fourth nozzle row in which a plurality of second nozzles capable of ejecting dots of liquid onto a medium are arranged in the first direction, the first nozzles and the second nozzles overlapping when viewed from a second direction intersecting the first direction, a print head in which the first nozzles and the second nozzles overlap when viewed from a second direction intersecting the first direction, a transport unit that performs relative movement between the medium and the print head in the second direction, and a control unit that controls the ejection of the dots by the nozzles in accordance with print data to perform the relative movement of the medium and the print head in the second direction. a control unit capable of forming a raster line in which dots are arranged on the medium, wherein the first nozzle row and the second nozzle row are adjacent to each other in the second direction in the order of the first nozzle row and the second nozzle row, the third nozzle row and the fourth nozzle row are adjacent to each other in the second direction in the order of the third nozzle row and the fourth nozzle row, the first nozzle row and the second nozzle row, and the third nozzle row and the fourth nozzle row are adjacent to each other in a third direction intersecting with the second direction, a distance in the second direction between the second nozzles on the side of a fourth nozzle row and the first nozzles on the side of the first nozzle row and the second nozzle row in the third nozzle row is shorter than a distance in the second direction between the first nozzles on the side of the third nozzle row and the fourth nozzle row in the first nozzle row and the first nozzles on the side of the first nozzle row and the second nozzle row in the third nozzle row, and when an area in an image represented by the print data in which the first nozzle row and the second nozzle row can form the raster lines is defined as a first area and an area in which the third nozzle row and the fourth nozzle row can form the raster lines is defined as a second area, the control unit, in a printing process in which a plurality of the raster lines are arranged in the third direction and formed on the medium, forms the raster line on the first area side of the raster lines adjacent to each other at the boundary between the first area and the second area in the third direction by the second nozzles of the second nozzle row, and forms the raster line on the second area side of the raster lines adjacent to each other at the boundary by the first nozzles of the third nozzle row.

[0008] According to a printing method for performing printing using a print head having a plurality of nozzles capable of ejecting dots of liquid onto a medium, the print head has a first nozzle row and a third nozzle row in which a plurality of first nozzles, which are the nozzles, are aligned in a predetermined first direction, and a second nozzle row and a fourth nozzle row in which a plurality of second nozzles, which are the nozzles, are aligned in the first direction, the first nozzles and the second nozzles overlap when viewed from a second direction intersecting the first direction, and the first nozzle row and the second nozzle row are arranged in the second direction in the order of the first nozzle row and the second nozzle row. the third nozzle row and the fourth nozzle row are adjacent to each other in the second direction in the order of the third nozzle row and the fourth nozzle row, the first nozzle row and the second nozzle row, and the third nozzle row and the fourth nozzle row are adjacent to each other in a third direction intersecting the second direction, and a distance in the second direction between the second nozzles on the side of the third nozzle row and the fourth nozzle row in the second nozzle row and the first nozzles on the side of the first nozzle row and the second nozzle row in the third nozzle row is the distance in the second direction is shorter than a distance in the second direction between the first nozzles on the side of the third nozzle row and the fourth nozzle row in the print head and the first nozzles on the side of the first nozzle row and the second nozzle row in the third nozzle row, and by relative movement between the medium and the print head in the second direction and control of the ejection of the dots by the nozzles in accordance with print data, wherein when an area in an image represented by the print data in which the first nozzle row and the second nozzle row can form the raster lines is defined as a first area and an area in which the third nozzle row and the fourth nozzle row can form the raster lines is defined as a second area, in the printing step, of the raster lines adjacent to each other at the boundary between the first area and the second area in the third direction, the raster line on the first area side is formed by the second nozzles of the second nozzle row, and of the raster lines adjacent to each other at the boundary, the raster line on the second area side is formed by the first nozzles of the third nozzle row. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a simplified device configuration. [Diagram 2] FIG. 13 is a simplified diagram showing the relationship between a print head whose nozzle arrangement direction is tilted and a medium, viewed from above. [Diagram 3] FIG. 13 is a simplified diagram showing the relationship between a print head whose nozzle arrangement direction is not tilted and a medium, viewed from above. [Figure 4] 4 is a flowchart showing a printing process according to the embodiment. [Diagram 5] FIG. 11 is a diagram showing the print result in step S120 after step S110, which is the print result in the first embodiment. [Figure 6] FIG. 13 is a diagram showing a conventional printing result. [Figure 7] FIG. 11 is a diagram showing a printing result in step S120 after step S110, which is a printing result in the second embodiment. [Figure 8] FIG. 13 is a diagram showing a printing result in step S120 after step S110, which is a printing result in the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that each drawing is merely an example for explaining the present embodiment. Since each drawing is an example, the ratio, shape, and shading may not be accurate, may not match each other, and some parts may be omitted.

[0011] 1.Outline of the device: 1 shows a simplified configuration of a printing device 10 according to this embodiment. The printing method of this embodiment is executed by the printing device 10. The printing device 10 includes a control unit 11, a display unit 13, an operation reception unit 14, a communication IF 15, a storage unit 16, a transport unit 17, a print head 18, and the like. IF stands for interface. The control unit 11 includes one or more ICs having a CPU 11a as a processor, a ROM 11b, a RAM 11c, and the like, and other non-volatile memories, and the like.

[0012] In the control unit 11, a processor, i.e., a CPU 11a, executes arithmetic processing according to a program 12 stored in a ROM 11b or other memory, using a RAM 11c or the like as a work area. The processor is not limited to a single CPU, and may be configured to perform processing using multiple CPUs or a hardware circuit such as an ASIC, or may be configured to perform processing in cooperation with a CPU and a hardware circuit.

[0013] The display unit 13 is a means for displaying visual information, and is configured, for example, by a liquid crystal display, an organic electroluminescence display, or the like. The 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 operations by a user, and is realized, for example, by a physical button, a touch panel, a mouse, a keyboard, or the like. Of course, 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. The display unit 13 and the operation reception unit 14 may be part of the configuration of the printing device 10, or may be peripheral devices externally attached to the printing device 10.

[0014] The communication IF 15 is a general term for one or more IFs that allow the printing device 10 to communicate with an external device (not shown) via wired or wireless communication in accordance with a predetermined communication protocol including a known communication standard. Examples of the external device include a personal computer, a server, a smartphone, a tablet terminal, a scanner, etc.

[0015] The storage unit 16 is, for example, a hard disk drive, a solid state drive, or other memory-based storage means. A part of the memory of the control unit 11 may be regarded as the storage unit 16. The storage unit 16 may be regarded as a part of the control unit 11.

[0016] In a so-called line printer, the transport unit 17 is a means for transporting the medium in a predetermined "transport direction" under the control of the control unit 11, and includes, for example, rollers (not shown) that rotate to transport the medium and a motor for driving the rollers. In a serial printer, the transport unit 17 is a means for relatively moving the medium and the print head 18 in the "transport direction" under the control of the control unit 11, and includes, for example, rails (not shown) for moving the print head 18 and a motor for moving the print head along the rails. The medium is typically paper, but may be a medium made of a material other than paper as long as it is a medium that can be printed with liquid. The transport direction corresponds to the "second direction" as described below, and the transport unit 17 executes the relative movement between the medium and the print head 18 in the second direction.

[0017] The print head 18 is a mechanism that ejects liquid such as ink by a so-called inkjet method to print on a medium. The print head 18 has a plurality of nozzles 19 capable of ejecting dots of liquid, and ejects dots from each nozzle 19 onto a medium transported by a transport unit 17 under the control of the control unit 11. Alternatively, the transport unit 17 ejects dots from each nozzle 19 under the control of the control unit 11 while moving the print head 18 relative to the medium in the transport direction D2. The print head 18 may be called a liquid ejection head, a recording head, a print head, an inkjet head, or the like.

[0018] Printing device 10 may be a single inkjet printer, but may also be a printing system consisting of multiple devices connected to each other so that they can communicate with each other. For example, the printing system may include an information processing device that corresponds to control unit 11, and a printer that has transport unit 17 and print head 18 and is controlled by the information processing device.

[0019] 2 and 3 each show a simplified view of the relationship between the print head 18 and the medium 30 from an above perspective. In FIG. 2 etc., each nozzle 19 is represented by a white circle, and the predetermined "first direction" in which the multiple nozzles 19 are aligned is indicated by the symbol D1. In this specification, the first direction D1 is also referred to as the "nozzle alignment direction D1." Furthermore, the symbol D2 indicates the second direction D2 that intersects with the nozzle alignment direction D1, that is, the transport direction D2. A "nozzle row" is formed by lining up the multiple nozzles 19 along the nozzle alignment direction D1.

[0020] In FIG. 2 and the like, the reference symbol D3 indicates a "third direction D3" that intersects with the transport direction D2. In this specification, the third direction D3 is also referred to as a "width direction D3". According to FIGS. 2 and 3, the transport direction D2 and the width direction D3 are perpendicular to each other. The width direction D3 can be interpreted as the longitudinal direction of the print head 18. The length in the width direction D3 is simply referred to as the width. The nozzle row of the print head 18 has a width equal to or greater than the width of the medium 30 as a whole. A printing device 10 having such a print head 18 corresponds to a so-called line printer. In the example of FIG. 2, the nozzle arrangement direction D1 is inclined obliquely with respect to the width direction D3. On the other hand, in the example of FIG. 3, the nozzle arrangement direction D1 is parallel to the width direction D3. The only difference between FIG. 2 and FIG. 3 is whether the nozzle arrangement direction D1 is inclined with respect to the width direction D3. In this embodiment, either the configuration of FIG. 2 or FIG. 3 may be adopted. The distance between the nozzles 19 in the nozzle arrangement direction D1 is referred to as the nozzle pitch. In other words, a nozzle row is a row in which a plurality of nozzles 19 are arranged at a constant nozzle pitch.

[0021] The print head 18 has a "first nozzle row 20a" and a "third nozzle row 20c" which are nozzle rows in which a plurality of "first nozzles 19a" which are nozzles 19 are arranged. Furthermore, the print head 18 has a "second nozzle row 20b" and a "fourth nozzle row 20d" which are nozzle rows in which a plurality of "second nozzles 19b" which are nozzles 19 are arranged. The first nozzle row 20a and the second nozzle row 20b are adjacent to each other in the transport direction D2 in the order of the first nozzle row 20a and the second nozzle row 20b. Similarly, the third nozzle row 20c and the fourth nozzle row 20d are adjacent to each other in the transport direction D2 in the order of the third nozzle row 20c and the fourth nozzle row 20d. The first nozzle row 20a and the second nozzle row 20b are adjacent to the third nozzle row 20c and the fourth nozzle row 20d in the width direction D3.

[0022] The positions of the first nozzle row 20a and the second nozzle row 20b in the width direction D3 are the same or almost the same. Similarly, the positions of the third nozzle row 20c and the fourth nozzle row 20d in the width direction D3 are the same or almost the same. In other words, the first nozzles 19a and the second nozzles 19b overlap when viewed from the transport direction D2. The first nozzles 19a and the second nozzles 19b are nozzles 19 that eject ink of the same color, for example, black (K) ink. Therefore, there is no substantial difference between the first nozzles 19a and the second nozzles 19b, but for convenience, they are called different names.

[0023] The first nozzle row 20a and the second nozzle row 20b may be understood to constitute one nozzle chip, and the third nozzle row 20c and the fourth nozzle row 20d may be understood to constitute another nozzle chip. The print head 18 is configured by connecting a plurality of such nozzle chips in the width direction D3. Although only two nozzle chips are shown in Figs. 2 and 3 and the figures described below, it may be understood that more nozzle chips are repeatedly connected in the width direction D3 to configure the print head 18. Therefore, the relationship between the first nozzle row and the second nozzle row and the third nozzle row and the fourth nozzle row can be understood in the same way when focusing on two nozzle chips adjacent to each other in the nozzle arrangement direction D1 or the width direction D3. In other words, from the perspective of Figures 2 and 3, if the third nozzle row 20c and the fourth nozzle row 20d are considered to be the first nozzle row and the second nozzle row, then the two nozzle rows of a nozzle chip (not shown) that is located on the opposite side of the nozzle chip having the third nozzle row 20c and the fourth nozzle row 20d from the first nozzle row 20a and the second nozzle row 20b in the width direction D3 are considered to be the third nozzle row and the fourth nozzle row.

[0024] The control unit 11 can form a "raster line" on the medium 30 in which dots are arranged in the transport direction D2 by controlling the ejection of dots by each nozzle 19 according to the print data. That is, the control unit 11 prints the image on the medium 30 by making each nozzle 19 eject or not eject dots based on the print data expressing the image to be printed. Note that the term "raster line" does not only refer to the result formed on the medium 30, but is also used in the state of the print data. In the state of the print data, the raster line is a pixel row in which a plurality of pixels are arranged corresponding to the transport direction D2. A certain first nozzle 19a belonging to the first nozzle row 20a and a second nozzle 19b of the second nozzle row 20b, whose position in the width direction D3 coincides or almost coincides with that of the first nozzle 19a, can form a raster line at the same position. That is, one raster line 31 illustrated in FIGS. 2 and 3 can be formed by one first nozzle 19a, and can also be formed by one second nozzle 19b. Similarly, a first nozzle 19a belonging to the third nozzle row 20c and a second nozzle 19b of the fourth nozzle row 20d, whose position in the width direction D3 coincides or nearly coincides with that of the first nozzle 19a, can form a raster line at the same position.

[0025] In the example of Fig. 2, the nozzle arrangement direction D1 is inclined with respect to the width direction D3. It is known that the printing resolution of the print head 18 in the width direction D3 can be increased by inclining the nozzle arrangement direction D1 with respect to the width direction D3. Even if the nozzle arrangement direction D1 is inclined with respect to the width direction D3, the nozzle arrangement direction D1 and the transport direction D2 intersect. Furthermore, the raster lines formed by the nozzles 19 of the nozzle row are naturally aligned in the width direction D3. When the nozzle arrangement direction D1 is parallel to the width direction D3 as in Fig. 3, the first direction D1 and the third direction D3 are naturally interpreted as being the same direction.

[0026] According to Figures 2 and 3, the distance W1 in the transport direction D2 between the second nozzle 19b on the side of the third nozzle row 20c and the fourth nozzle row 20d in the second nozzle row 20b and the first nozzle 19a on the side of the first nozzle row 20a and the second nozzle row 20b in the third nozzle row 20c is shorter than the distance W2 in the transport direction D2 between the first nozzle 19a on the side of the third nozzle row 20c and the fourth nozzle row 20d in the first nozzle row 20a and the first nozzle 19a on the side of the first nozzle row 20a and the second nozzle row 20b in the third nozzle row 20c. That is, at least in the vicinity of the boundary between the first nozzle row 20a and the second nozzle row 20b and the third nozzle row 20c and the fourth nozzle row 20d in the width direction D3, the nozzles 19 of each nozzle row are arranged in the transport direction D2 in the following order: the first nozzle 19a of the first nozzle row 20a, the second nozzle 19b of the second nozzle row 20b, the first nozzle 19a of the third nozzle row 20c, and the second nozzle 19b of the fourth nozzle row 20d. Similarly, the distance in the transport direction D2 between the second nozzle 19b on the side of the third nozzle row 20c and the fourth nozzle row 20d in the second nozzle row 20b and the second nozzle 19b on the side of the first nozzle row 20a and the second nozzle row 20b in the fourth nozzle row 20d may also be interpreted as the distance W2.

[0027] Needless to say, the print head 18 can eject ink of other colors such as cyan (C), magenta (M), and yellow (Y) in addition to K ink. The print head 18 may also be a product capable of ejecting liquids of other colors than ink. Although omitted in Figures 2 and 3 due to space limitations, the print head 18 has first to fourth nozzle rows for ejecting liquids of colors and types other than K ink in the same manner as the first to fourth nozzle rows 20a, 20b, 20c, and 20d.

[0028] 2 and 3, the print head 18 is stationary on the transport path of the medium 30, and the print head 18 ejects liquid onto the medium 30 transported by the transport unit 17 from upstream to downstream in the transport direction D2. However, the relative movement between the medium 30 and the print head 18 may at least include the movement of the print head 18. In other words, a mechanism may be adopted in which the print head 18 ejects liquid onto the medium 30 while moving from downstream to upstream in the transport direction D2 by a carriage (not shown), thereby forming a raster line on the medium 30 and achieving printing. In this case, the carriage corresponds to at least a part of the transport unit that executes the relative movement between the medium 30 and the print head 18.

[0029] 2.Printing method: 4 is a flowchart showing the printing process executed by the control unit 11 in accordance with the program 12. As the printing process, the control unit 11 forms a plurality of raster lines aligned in the width direction D3 on the medium 30. The description of this flowchart will serve as the description of the printing method of this embodiment. In step S100, the control unit 11 generates print data. First, the control unit 11 acquires image data expressing an image to be printed, which is the source of the print data. The image data is transmitted, for example, from an external device, and the control unit 11 acquires the image data from the external device via the communication IF 15. Alternatively, the image data is selected by a user's operation via the operation acceptance unit 14. The control unit 11 acquires the image data selected by the user from a storage location for the image data, for example, the storage unit 16.

[0030] The control unit 11 generates print data from image data. The control unit 11 generates print data by performing various image processing such as resolution conversion processing, color conversion processing, halftone processing, etc. on the image data. The print data is data that specifies the ejection or non-ejection of dots for each pixel and for each type of liquid. The type of liquid may be interpreted as the color of ink. The ejection of dots is also called dot-on, and the non-ejection of dots is also called dot-off.

[0031] In step S110, the control unit 11 assigns each raster line constituting the print data to each nozzle 19 of the print head 18 according to its position in the width direction D3. When the area in the image represented by the print data where the first nozzle row 20a and the second nozzle row 20b can form raster lines is defined as the "first area" and the area where the third nozzle row 20c and the fourth nozzle row 20d can form raster lines is defined as the "second area," the control unit 11 assigns the raster line on the first area side of adjacent raster lines at the boundary between the first area and the second area in the width direction D3 to the second nozzle 19b of the second nozzle row 20b, and assigns the raster line on the second area side of adjacent raster lines at the boundary to the first nozzle 19a of the third nozzle row 20c.

[0032] In step S120, the control unit 11 outputs data for each pixel constituting each raster line of the print data to each nozzle 19 of the print head 18 according to the allocation in step S110, and causes the print head 18 to execute printing based on the print data. Step S120 corresponds to a "printing step" in which a plurality of raster lines are formed on the medium 30 in the width direction D3 by relative movement between the medium 30 and the print head 18 in the transport direction D2 and control of the ejection of dots by the nozzles 19 according to the print data. According to step S120, of the raster lines adjacent to each other at the boundary, the raster line on the first region side is formed by the second nozzle 19b of the second nozzle row 20b, and of the raster lines adjacent to each other at the boundary, the raster line on the second region side is formed by the first nozzle 19a of the third nozzle row 20c.

[0033] First Example: FIG. 5 is a diagram illustrating a printing result in step S120 after step S110, and shows the print head 18 and a part of the medium 30. The explanation based on FIG. 5 is also referred to as the "first embodiment." The way to view FIG. 5 is almost the same as the way to view FIGS. 2 and 3. In FIG. 5, an example is adopted in which the nozzle arrangement direction D1 is inclined with respect to the width direction D3, as in FIG. 2, as the structure of the print head 18. In the explanation of FIG. 5, the distances W1 and W2 explained in FIG. 2 are also used as appropriate. The way to view FIGS. 6, 7, and 8 described below is also the same as the way to view FIG. 5.

[0034] In Fig. 5, each long region along the transport direction D2 shown in the medium 30 simply represents each raster line. A two-dimensional image is expressed by a series of multiple raster lines, and in such an image, a region where raster lines that can be formed by the first nozzle row 20a and the second nozzle row 20b are continuous is a first region 32, and a region where raster lines that can be formed by the third nozzle row 20c and the fourth nozzle row 20d are continuous is a second region 33. In Fig. 5, the regions of the image printed on the medium 30 are shown as the first region 32 and the second region 33, but these regions 32 and 33 can also be interpreted as respective regions of the print data that express the image.

[0035] In FIG. 5, the boundary A between the first region 32 and the second region 33 is indicated by a two-dot chain line for easy understanding. Of the raster lines adjacent to each other at the boundary A, the raster line on the first region 32 side is hereinafter referred to as the first adjacent raster line 31a, and the raster line on the second region 33 side is hereinafter referred to as the second adjacent raster line 31b. In FIG. 5, of the raster lines, the raster lines formed by the dot ejection from the first nozzle 19a are indicated in white, and the raster lines formed by the dot ejection from the second nozzle 19b are indicated in gray. Of course, these white and gray colors are merely expressions for convenience in distinguishing the raster lines, and are unrelated to the color of the actual image represented by the print data. In addition, since the actual image is represented by the dot-on and dot-off of each pixel in the print data, even if it is called one raster line, the dots are not necessarily completely connected along the transport direction D2, and naturally, the dots may be interrupted along the way.

[0036] 5, all of the raster lines in the first region 32, including the first adjacent raster line 31a, are formed by the second nozzles 19b, and all of the raster lines in the second region 33, including the second adjacent raster line 31b, are formed by the first nozzles 19a. That is, in the first embodiment, the control unit 11 forms the raster lines in the first region 32 using only the second nozzles 19b of the second nozzle row 20b, and forms the raster lines in the second region 33 using only the first nozzles 19a of the third nozzle row 20c.

[0037] Fig. 6 is a comparative example of Fig. 5, and shows a print result by a conventional printing process. The first nozzles 19a of the first nozzle row 20a and the third nozzle row 20c and the second nozzles 19b of the second nozzle row 20b and the fourth nozzle row 20d have the same print resolution in the width direction D3, so in the past, only one of the first nozzles 19a and the second nozzles 19b was used to print one image. In the example of Fig. 6, all of the raster lines of the print data are formed using only the second nozzles 19b, that is, the second nozzle row 20b and the fourth nozzle row 20d.

[0038] 5 and 6, in the first region 32 and the second region 33, each raster line is formed using nozzles 19 belonging to the same nozzle row. Therefore, the distance in the transport direction D2 between the nozzles 19 that form adjacent raster lines in the first region 32 and the distance in the transport direction D2 between the nozzles 19 that form adjacent raster lines in the second region 33 is a very short distance such as the distance W3 shown in Fig. 5, or is zero in the configuration of Fig. 3. On the other hand, the distance in the transport direction D2 between the nozzles 19 that form adjacent raster lines across the boundary A is the distance W2 as described in Fig. 2 in the comparative example shown in Fig. 6, and is the distance W1 as described in Fig. 2 in the first embodiment shown in Fig. 5.

[0039] As described above, when the distance between the nozzles 19 used to form adjacent raster lines in the transport direction D2 changes, a time difference occurs in the timing of forming the adjacent raster lines, which makes it easy for striped density unevenness to occur. In other words, density unevenness is likely to occur in the print result at the boundary A between the first adjacent raster line 31a and the second adjacent raster line 31b. According to this embodiment, the distance between the nozzle 19 used to form the first adjacent raster line 31a and the nozzle 19 used to form the second adjacent raster line 31b in the transport direction D2 is reduced from the conventional distance W2 to distance W1. As a result, the distance between the nozzle 19 used to form the first adjacent raster line 31a and the nozzle 19 used to form the second adjacent raster line 31b in the transport direction D2 approaches the distance W3 between the nozzles 19 that form other adjacent raster lines, and as a result, density unevenness occurring at the boundary A can be suppressed more than before.

[0040] Example 2: FIG. 7 shows a printing result by step S120 after step S110, and shows an example different from FIG. 5. The description based on FIG. 7 is also referred to as "second embodiment". According to FIG. 7, the first region 32 is formed by alternately allocating each raster line including the first adjacent raster line 31a to the first nozzle 19a of the first nozzle row 20a and the second nozzle 19b of the second nozzle row 20b in the width direction D3 while the first adjacent raster line 31a is formed by the second nozzle 19b of the second nozzle row 20b. Also, the second region 33 is formed by alternately allocating each raster line including the second adjacent raster line 31b to the first nozzle 19a of the third nozzle row 20c and the second nozzle 19b of the fourth nozzle row 20d in the width direction D3 while the second adjacent raster line 31b is formed by the first nozzle 19a of the third nozzle row 20c.

[0041] That is, in the second embodiment, the control unit 11 forms the raster lines of at least one of the first region 32 and the second region 33 by alternately using the first nozzle 19a and the second nozzle 19b in the width direction D3. In the second embodiment, the distance in the transport direction D2 between the nozzle 19 used to form the first adjacent raster line 31a and the nozzle 19 used to form the second adjacent raster line 31b is also reduced from the conventional distance W2 to distance W1. As a result, the distance in the transport direction D2 between the nozzle 19 used to form the first adjacent raster line 31a and the nozzle 19 used to form the second adjacent raster line 31b approaches the distance W4 between the nozzles 19 forming the other adjacent raster lines, so that the same effect as in the first embodiment is achieved. Note that at least one of the first region 32 and the second region 33 is formed, so in the second embodiment, either the first region 32 or the second region 33 may be printed as in the first embodiment.

[0042] Example 3: Print head 18 may have overlapping portions where the ends of the nozzle rows overlap. FIG. 8 illustrates a printing result in step S120 after step S110, assuming a configuration having such an overlapping portion. The description based on FIG. 8 is also referred to as the "third embodiment." According to FIG. 8, the print head 18 has an overlapping portion 21 formed in which the ends of the first nozzle row 20a and the second nozzle row 20b on the side of the third nozzle row 20c and the fourth nozzle row 20d overlap with the ends of the third nozzle row 20c and the fourth nozzle row 20d on the side of the first nozzle row 20a and the second nozzle row 20b, as viewed from the transport direction D2. The range of the nozzles 19 in the print head 18 other than the overlapping portion 21 is also referred to as a normal portion.

[0043] In the third embodiment, the control unit 11 associates the boundary between the first region 32 and the second region 33 with any of the following: a boundary between the overlapping portion 21 and a normal portion other than the overlapping portion 21 in the first nozzle row 20a and the second nozzle row 20b, inside the overlapping portion 21, and a boundary between the overlapping portion 21 and a normal portion other than the overlapping portion 21 in the third nozzle row 20c and the fourth nozzle row 20d. In FIG. 8, two-dot chain lines are drawn at positions in the image corresponding to these, that is, positions A1, A2, and A3 that can be candidates for the boundary, for easy understanding. The control unit 11 may set any one of these positions A1, A2, and A3 as the boundary between the first region 32 and the second region 33. In the example of FIG. 8, the position A3 is set as the boundary A3. Therefore, in the example of FIG. 8, of the raster lines adjacent to each other at the boundary A3, the raster line on the first region 32 side will be called the first adjacent raster line 31d, and the raster line on the second region 33 side will be called the second adjacent raster line 31e.

[0044] In the third embodiment, the control unit 11 naturally forms the first adjacent raster line 31d by the second nozzle 19b of the second nozzle row 20b, and forms the second adjacent raster line 31e by the first nozzle 19a of the third nozzle row 20c. Also, like the second embodiment, each raster line including the first adjacent raster line 31d and the second adjacent raster line 31e is alternately assigned to the first nozzle 19a and the second nozzle 19b in the width direction D3. The control unit 11 forms the same raster line by either the first nozzle 19a or the second nozzle 19b for the raster lines formed by the nozzles 19 in the overlapping portion 21, and forms the raster lines by alternately using the first nozzle 19a and the second nozzle 19b in the width direction D3.

[0045] In the example of FIG. 8, the first adjacent raster line 31d and the raster line 31c adjacent to the first adjacent raster line 31d on the opposite side of the boundary A3 correspond to the raster lines formed by the nozzles 19 of the overlapping portion 21. Therefore, the control unit 11 forms the first adjacent raster line 31d using the second nozzle 19b of the second nozzle row 20b and the second nozzle 19b of the fourth nozzle row 20d, and forms the raster line 31c using the first nozzle 19a of the first nozzle row 20a and the first nozzle 19a of the third nozzle row 20c. The method of printing a common raster line using two or more nozzles 19 may be understood as so-called overlap printing. Each raster line that does not correspond to the raster line formed by the nozzles 19 of the overlapping portion 21 is basically formed by one nozzle 19 each. In this way, in the third embodiment as well, the distance in the transport direction D2 between the nozzle 19 used to form the first adjacent raster line 31d and the nozzle 19 used to form the second adjacent raster line 31e is reduced from the conventional distance W2 to distance W1. As a result, the distance in the transport direction D2 between the nozzle 19 used to form the first adjacent raster line 31d and the nozzle 19 used to form the second adjacent raster line 31e approaches the distance W4 between the nozzles 19 that form the other adjacent raster lines, thereby achieving the same effect as the first and second embodiments.

[0046] 3. Summary: Thus, according to this embodiment, the printing device 10 has a first nozzle row 20a and a third nozzle row 20c in which a plurality of first nozzles 19a, which are nozzles 19 capable of ejecting dots of liquid onto a medium 30, are arranged in a predetermined first direction D1, and a second nozzle row 20b and a fourth nozzle row 20d in which a plurality of second nozzles 19b, which are nozzles 19, are arranged in the first direction D1, a print head 18 in which the first nozzles 19a and the second nozzles 19b overlap when viewed from a second direction D2 that intersects the first direction D1, a transport unit 17 that performs relative movement between the medium 30 and the print head 18 in the second direction D2, and a control unit 11 that is capable of forming raster lines on the medium 30 in which dots are arranged in the second direction D2 by controlling the ejection of dots by the nozzles 19 in accordance with print data. The first nozzle row 20a and the second nozzle row 20b are adjacent to each other in the second direction D2 in the order of first nozzle row 20a and second nozzle row 20b, the third nozzle row 20c and the fourth nozzle row 20d are adjacent to each other in the second direction D2 in the order of third nozzle row 20c and fourth nozzle row 20d, and the first nozzle row 20a and the second nozzle row 20b, and the third nozzle row 20c and the fourth nozzle row 20d are adjacent to each other in a third direction D3 that intersects with the second direction D2. The distance W1 in the second direction D2 between the second nozzle 19b on the side of the third nozzle row 20c and the fourth nozzle row 20d in the second nozzle row 20b and the first nozzle 19a on the side of the first nozzle row 20a and the second nozzle row 20b in the third nozzle row 20c is shorter than the distance W2 in the second direction D2 between the first nozzle 19a on the side of the third nozzle row 20c and the fourth nozzle row 20d in the first nozzle row 20a and the first nozzle 19a on the side of the first nozzle row 20a and the second nozzle row 20b in the third nozzle row 20c.When the area of ​​the image represented by the printing data where the first nozzle row 20a and the second nozzle row 20b can form raster lines is defined as the first area 32, and the area where the third nozzle row 20c and the fourth nozzle row 20d can form raster lines is defined as the second area 33, in the printing process in which multiple raster lines are arranged in the third direction D3 and formed on the medium 30, the control unit 11 forms the raster line on the first area 32 side of adjacent raster lines at the boundary between the first area 32 and the second area 33 in the third direction D3 by the second nozzle 19b of the second nozzle row 20b, and forms the raster line on the second area 33 side of adjacent raster lines at the boundary by the first nozzle 19a of the third nozzle row 20c.

[0047] According to the above configuration, the control unit 11 shortens the distance in the second direction D2 between the nozzles 19 used to form a first adjacent raster line on the first region 32 side and a second adjacent raster line on the second region 33 side that are adjacent to each other at the boundary, and makes it closer to the distance in the second direction D2 between the nozzles 19 used to form other adjacent raster lines. This makes it possible to improve print quality by suppressing streaky density unevenness that can occur at the boundary more than before.

[0048] According to the first embodiment, the control unit 11 forms the raster lines in the first region 32 using only the second nozzles 19b of the second nozzle row 20b, and forms the raster lines in the second region 33 using only the first nozzles 19a of the third nozzle row 20c. According to the above-described configuration, in addition to the effects of this embodiment described above, various effects can be obtained, such as simplifying the liquid supply path to the nozzles 19 and reducing the burden of maintenance such as cleaning of the nozzle rows, by clearly defining which nozzle rows are in use and which are not in use.

[0049] According to the second embodiment, the control unit 11 forms raster lines in at least one of the first region 32 and the second region 33 by alternately using the first nozzles 19a and the second nozzles 19b in the third direction D3. According to this configuration, the distance in the second direction D2 between the nozzles 19 used to form adjacent raster lines other than the first adjacent raster line and the second adjacent raster line adjacent to each other across the boundary can be set to a distance W4 that is greater than the distance W3. This makes it possible to reduce the difference in the distance in the second direction D2 between the nozzles 19 used to form the first adjacent raster line and the second adjacent raster line and the distance in the second direction D2 between the nozzles 19 used to form the other adjacent raster lines, thereby achieving print quality in which density unevenness is less noticeable.

[0050] According to the third embodiment, when the ends of the first nozzle row 20a and the second nozzle row 20b on the side of the third nozzle row 20c and the fourth nozzle row 20d and the ends of the third nozzle row 20c and the fourth nozzle row 20d on the side of the first nozzle row 20a and the second nozzle row 20b form an overlapping portion 21 that overlaps when viewed from the second direction D2, the control unit 11 sets the boundary between the first region 32 and the second region 33 as a normal portion of the first nozzle row 20a and the second nozzle row 20b other than the overlapping portion 21. The raster lines formed by the nozzles 19 in the overlapping portion 21 correspond to either the boundary with the overlapping portion 21, within the overlapping portion 21, or the boundary between the overlapping portion 21 and the normal portions of the third nozzle row 20c and the fourth nozzle row 20d other than the overlapping portion 21, and the same raster line is formed by either the first nozzle 19a or the second nozzle 19b, and the first nozzle 19a and the second nozzle 19b are alternately used to form the raster lines in the third direction D3. According to the above configuration, for the raster lines formed by the nozzles 19 in the overlapping portion 21, the same raster line can be formed by the first nozzles 19a in the first nozzle row 20a and the first nozzles 19a in the third nozzle row 20c, or another identical raster line can be formed by the second nozzles 19b in the second nozzle row 20b and the second nozzles 19d in the fourth nozzle row 20d. As a result, even if an error occurs in the positional relationship in the second direction D2 between the nozzle chip having the first nozzle row 20a and the second nozzle row 20b and the nozzle chip having the third nozzle row 20c and the fourth nozzle row 20d, it is possible to prevent all of the distances in the second direction D2 between the two nozzles 19 used to form one raster line corresponding to the overlapping portion 21 and the nozzles 19 used to form a raster line on the normal portion side adjacent to the raster line from being significantly different from the above-mentioned distances W3 and W4, leading to improved print quality.

[0051] Although only some of the combinations of claims are described in the claims, this embodiment naturally includes within its scope not only one-to-one combinations of independent claims and dependent claims, but also various combinations of multiple dependent claims. In addition to the printing device 10, the present embodiment also discloses a method and a program 12 for implementing the method in cooperation with a processor.

[0052] According to a printing method for performing printing using a print head 18 having a plurality of nozzles 19 capable of ejecting dots of liquid onto a medium 30, the print head 18 has a first nozzle row 20a and a third nozzle row 20c in which a plurality of first nozzles 19a, which are nozzles 19, are aligned in a predetermined first direction D1, and a second nozzle row 20b and a fourth nozzle row 20d in which a plurality of second nozzles 19b, which are nozzles 19, are aligned in the first direction D1, and the first nozzles 19a and the second nozzles 19b are aligned in a second direction D1 that intersects the first direction D1. 2, the first nozzle row 20a and the second nozzle row 20b are adjacent to each other in the second direction D2 in the order of the first nozzle row 20a and the second nozzle row 20b, the third nozzle row 20c and the fourth nozzle row 20d are adjacent to each other in the second direction D2 in the order of the third nozzle row 20c and the fourth nozzle row 20d, and the first nozzle row 20a and the second nozzle row 20b, and the third nozzle row 20c and the fourth nozzle row 20d are adjacent to each other in a third direction D3 that intersects with the second direction D2. The distance W1 in the second direction D2 between the second nozzle 19b on the side of the third nozzle row 20c and the fourth nozzle row 20d in the second nozzle row 20b and the first nozzle 19a on the side of the first nozzle row 20a and the second nozzle row 20b in the third nozzle row 20c is shorter than the distance W2 in the second direction D2 between the first nozzle 19a on the side of the third nozzle row 20c and the fourth nozzle row 20d in the first nozzle row 20a and the first nozzle 19a on the side of the first nozzle row 20a and the second nozzle row 20b in the third nozzle row 20c.According to the printing method, there is provided a printing step in which raster lines, each of which has dots lined up in the second direction D2, are formed on the medium 30 in a third direction D3 by relative movement between the medium 30 and the print head 18 in the second direction D2 and control of the ejection of dots by the nozzles 19 in accordance with the print data. When an area in an image represented by the print data in which the first nozzle row 20a and the second nozzle row 20b can form raster lines is defined as a first area 32, and an area in which the third nozzle row 20c and the fourth nozzle row 20d can form raster lines is defined as a second area 33, in the printing step, of the raster lines adjacent to each other at the boundary between the first area 32 and the second area 33 in the third direction D3, the raster line on the first area 32 side is formed by the second nozzles 19b of the second nozzle row 20b, and of the raster lines adjacent to each other at the boundary, the raster line on the second area 33 side is formed by the first nozzles 19a of the third nozzle row 20c.

[0053] The liquid ejected by the first nozzles 19a of the first nozzle row 20a and the third nozzle row 20c and the liquid ejected by the second nozzles 19b of the second nozzle row 20b and the fourth nozzle row 20d may be inks of different colors. In other words, nozzle rows that are separated in the transport direction D2 and have a relationship of ejecting inks of different colors can be considered as the first nozzle row and the third nozzle row, and the second nozzle row and the fourth nozzle row. [Explanation of symbols]

[0054] 10...printing device, 11...control unit, 12...program, 13...display unit, 14...operation reception unit, 15...communication IF, 16...memory unit, 17...transport unit, 18...print head, 19...nozzle, 19a...first nozzle, 19b...second nozzle, 20a...first nozzle row, 20b...second nozzle row, 20c...third nozzle row, 20d...fourth nozzle row, 30...medium, 31a, 31d...first adjacent raster line, 31b, 31e...second adjacent raster line, 32...first region, 33...second region

Claims

1. a print head having a first nozzle row and a third nozzle row in which a plurality of first nozzles capable of ejecting dots of liquid onto a medium are arranged in a predetermined first direction, and a second nozzle row and a fourth nozzle row in which a plurality of second nozzles capable of ejecting dots of liquid onto a medium are arranged in the first direction, the first nozzles and the second nozzles overlapping when viewed from a second direction intersecting the first direction; a transport unit that performs relative movement between the medium and the print head in the second direction; a control unit capable of forming a raster line in which the dots are aligned in the second direction on the medium by controlling the ejection of the dots from the nozzles in accordance with print data; the first nozzle row and the second nozzle row are adjacent to each other in the second direction in the order of the first nozzle row and the second nozzle row, the third nozzle row and the fourth nozzle row are adjacent to each other in the second direction in the order of the third nozzle row and the fourth nozzle row, the first nozzle row and the second nozzle row, and the third nozzle row and the fourth nozzle row are adjacent to each other in a third direction intersecting the second direction, a distance in the second direction between the second nozzles in the second nozzle row on the side of the third nozzle row and the fourth nozzle row and the first nozzles in the third nozzle row on the side of the first nozzle row and the second nozzle row is shorter than a distance in the second direction between the first nozzles in the first nozzle row on the side of the third nozzle row and the fourth nozzle row and the first nozzles in the third nozzle row on the side of the first nozzle row and the second nozzle row, When an area of ​​an image represented by the print data in which the first nozzle row and the second nozzle row can form the raster lines is defined as a first area, and an area in which the third nozzle row and the fourth nozzle row can form the raster lines is defined as a second area, The control unit, in a printing process in which a plurality of the raster lines are arranged in the third direction and formed on the medium, forms the raster line on the first region side of the raster lines adjacent to each other at the boundary between the first region and the second region in the third direction using the second nozzles of the second nozzle row, and forms the raster line on the second region side of the raster lines adjacent to each other at the boundary using the first nozzles of the third nozzle row.

2. 2. The printing device according to claim 1, wherein the control unit forms the raster lines in the first region using only the second nozzles of the second nozzle row, and forms the raster lines in the second region using only the first nozzles of the third nozzle row.

3. 2. The printing device according to claim 1, wherein the control unit forms the raster lines in at least one of the first region and the second region by alternately using the first nozzles and the second nozzles in the third direction.

4. when ends of the first nozzle row and the second nozzle row on the side of the third nozzle row and the fourth nozzle row and ends of the third nozzle row and the fourth nozzle row on the side of the first nozzle row and the second nozzle row form an overlapping portion when viewed from the second direction, The control unit is a boundary between the first region and the second region is associated with any one of a boundary between a normal portion other than the overlapping portion of the first nozzle row and the second nozzle row and the overlapping portion, an area within the overlapping portion, and a boundary between a normal portion other than the overlapping portion of the third nozzle row and the fourth nozzle row and the overlapping portion; 2. The printing device according to claim 1, wherein, for the raster lines formed by the nozzles in the overlapping portion, the same raster line is formed by either the first nozzles or the second nozzles, and the raster lines are formed by alternately using the first nozzles and the second nozzles in the third direction.

5. A printing method for performing printing using a print head having a plurality of nozzles capable of ejecting dots of liquid onto a medium, comprising: the print head has a first nozzle row and a third nozzle row in which a plurality of first nozzles, which are the nozzles, are aligned in a predetermined first direction, and a second nozzle row and a fourth nozzle row in which a plurality of second nozzles, which are the nozzles, are aligned in the first direction, the first nozzles and the second nozzles overlap when viewed from a second direction intersecting the first direction, the first nozzle row and the second nozzle row are adjacent to each other in the second direction in the order of the first nozzle row and the second nozzle row, the third nozzle row and the fourth nozzle row are adjacent to each other in the second direction in the order of the third nozzle row and the fourth nozzle row, the first nozzle row and the second nozzle row, and the third nozzle row and the fourth nozzle row are adjacent to each other in a third direction intersecting the second direction, a distance in the second direction between the second nozzles in the second nozzle row on the side of the third nozzle row and the fourth nozzle row and the first nozzles in the third nozzle row on the side of the first nozzle row and the second nozzle row is shorter than a distance in the second direction between the first nozzles in the first nozzle row on the side of the third nozzle row and the fourth nozzle row and the first nozzles in the third nozzle row on the side of the first nozzle row and the second nozzle row, a printing step of forming, on the medium, a plurality of raster lines in which the dots are arranged in the second direction, in the third direction, by controlling the relative movement between the medium and the print head in the second direction and the ejection of the dots by the nozzles in accordance with print data; When an area of ​​an image represented by the print data in which the first nozzle row and the second nozzle row can form the raster lines is defined as a first area, and an area in which the third nozzle row and the fourth nozzle row can form the raster lines is defined as a second area, a printing method characterized in that, in the printing process, of the raster lines adjacent to each other at the boundary between the first region and the second region in the third direction, the raster line on the first region side is formed by the second nozzles of the second nozzle row, and of the raster lines adjacent to each other at the boundary, the raster line on the second region side is formed by the first nozzles of the third nozzle row.

Images