Droplet discharge device, recording method, and program

Abstract

To provide a droplet discharge device in which a difference in density between an overlapping region and a non-overlapping area of a head module can be made less noticeable, a recording method, and a program.SOLUTION: A droplet discharge device 100 which has a plurality of line heads 150 arranged so that adjacent two head modules 151 have an overlapping area ab where ends thereof in a first direction C are overlapped with each other, comprises: a recording part 2 which discharges droplets from nozzle openings 152 to a recording medium P on the basis of image data; and a control part 101 which controls on the basis of a nozzle changeover unit whether droplets are discharged from any one nozzle opening 152. The control part 101 sets the nozzle changeover unit according to a combination of resolutions in the first direction C and a second direction B of the image data.SELECTED DRAWING: Figure 7B

Description

Technical Field

[0001] The present invention relates to a droplet ejection device, a recording method, and a program.

Background Art

[0002] Conventionally, a droplet ejection device that ejects droplets onto a recording surface of a recording medium conveyed in a conveyance direction to record an image is known. The droplet ejection device ejects droplets from nozzles of a droplet ejection head at an appropriate timing based on image data.

[0003] Among droplet ejection devices, there is a so-called single-pass type in which head modules each including a plurality of droplet ejection heads are arranged in a staggered manner so as to have an overlapping region. In such a droplet ejection device, droplets ejected from different head modules in the overlapping region and having a difference in landing time may be connected to each other. Then, the dot shape differs between the overlapping region and the non-overlapping region, a gloss difference due to reflected light occurs, and the image quality deteriorates.

[0004] Therefore, for example, Patent Document 1 describes a droplet ejection device that switches a head module that ejects droplets when non-ejection of droplets continues for a predetermined number of times or more in an overlapping region. According to such a droplet ejection device, it becomes difficult for dots ejected from different head modules to be connected to each other, and deterioration of image quality can be suppressed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, as shown in FIGS. 10A and 10B, in such an image forming apparatus, if there is a misalignment in the conveyance direction D between the head modules H1 and H2, there will be a deviation in the ink coverage rate in the overlapping region. Specifically, FIG. 10B shows that as a result of the misalignment in the conveyance direction D between the head modules H1 and H2 compared to FIG. 10A, there is a deviation in the droplet landing position in the conveyance direction D, the gap G disappears, and the ink coverage rate increases. There was a problem that the deviation in the ink coverage rate directly became a conspicuous deviation in density from the non-overlapping region.

[0007] The present invention has been made in view of such circumstances. Its object is to provide a droplet discharge device, a recording method, and a program that can make the density deviation from the non-overlapping region less conspicuous in the overlapping region of the head module.

Means for Solving the Problems

[0008] In order to solve the above problems, the invention according to claim 1 is a droplet discharge device, a line head in which a plurality of head modules each having a nozzle row composed of a plurality of nozzle openings arranged in a row along a first direction are arranged in a plurality along the first direction, and the line heads are arranged so that adjacent two head modules have an overlapping region where the ends in the first direction overlap each other; a recording unit that discharges droplets from the nozzle openings to a recording medium based on image data; a moving unit that relatively moves the recording medium and the line head in a second direction intersecting the first direction so that the nozzle openings corresponding to the overlapping region of the two head modules can be moved to the same location on the recording medium; a control unit that controls which of the nozzle openings corresponding to the overlapping region discharges droplets based on a nozzle switching unit; and the control unit sets the nozzle switching unit according to the combination of the resolutions in the first direction and the second direction of the image data.

[0009] The invention according to claim 2 is the droplet discharge device according to claim 1, wherein the control unit sets different nozzle switching units according to the resolution of the image data in the second direction.

[0010] The invention according to claim 3 is the droplet discharge device according to claim 2, wherein the resolution of the image data in the second direction is less than or equal to the resolution in the first direction.

[0011] The invention according to claim 4 is the droplet discharge device according to claim 3, wherein the control unit sets the nozzle switching unit so that the lower the resolution of the image data in the second direction, the larger the nozzle switching unit.

[0012] The invention according to claim 5 is the droplet discharge device according to claim 4, wherein the control unit sets the nozzle switching unit so that the visual sensitivity is less than 50% in the human visual frequency characteristic (VTF).

[0013] The invention according to claim 6 is the droplet discharge device according to any one of claims 1 to 5, wherein the control unit controls so that the switching position of the head module is the same in the first direction in a plurality of the nozzle rows adjacent to each other in the second direction.

[0014] The invention according to claim 7 is the droplet discharge device according to claim 6, wherein the control unit sets the switching position of the head module in the second direction so that the visual sensitivity is less than 50% in the human visual frequency characteristic (VTF).

[0015] The invention according to claim 8 is the droplet discharge device according to any one of claims 1 to 5, wherein ink that thickens by a phase change after landing on the recording medium is discharged.

[0016] The invention according to claim 9 is A line head in which a plurality of head modules each having a nozzle row composed of a plurality of nozzle openings arranged in a row along a first direction are arranged in a plurality along the first direction, and the line head is arranged such that adjacent two head modules have an overlapping region where the ends in the first direction overlap each other. A recording method by a droplet ejection device having the line head, a recording step of ejecting droplets from the nozzle openings onto a recording medium based on image data; a moving step of relatively moving the recording medium and the line head in a second direction intersecting the first direction so that the nozzle openings corresponding to the overlapping region of the two head modules can be moved to the same position on the recording medium; a control step of controlling whether to eject droplets from any of the nozzle openings corresponding to the overlapping region based on a nozzle switching unit; and the control step sets the nozzle switching unit according to a combination of resolutions in the first direction and the second direction of the image data.

[0017] The invention according to claim 10 is a program, a line head in which a plurality of head modules each having a nozzle row composed of a plurality of nozzle openings arranged in a row along a first direction are arranged in a plurality along the first direction, and the line head is arranged such that adjacent two head modules have an overlapping region where the ends in the first direction overlap each other; a recording unit that ejects droplets from the nozzle openings onto a recording medium based on image data; a moving unit that relatively moves the recording medium and the line head in a second direction intersecting the first direction so that the nozzle openings corresponding to the overlapping region of the two head modules can be moved to the same position on the recording medium; and a computer of a droplet ejection device having the moving unit, functions as a control unit that controls which of the nozzle openings corresponding to the overlapping region ejects droplets based on a nozzle switching unit. The control unit sets the nozzle switching unit according to the combination of the resolutions in the first direction and the second direction of the image data.

Advantages of the Invention

[0018] According to the present invention, in the overlapping region of the head module, the density deviation from the non-overlapping region can be made less noticeable.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7A

Figure 7B

Figure 8

Figure 9

Figure 10A

Figure 10B

Embodiments for Carrying Out the Invention

[0020] Hereinafter, a droplet ejection device according to an embodiment of the present invention will be described with reference to the drawings. However, the scope of the present invention is not limited to the illustrated examples. Also, in the following description, those having the same function and configuration may be denoted by the same reference numerals, and the description thereof may be omitted.

[0021] [Overall Configuration of Droplet Ejection Device] FIG. 1 is a schematic diagram showing an inkjet recording apparatus 100 according to the present embodiment. The inkjet recording apparatus 100 is a droplet ejection device according to the present embodiment.

[0022] (Moving Unit) As shown in FIG. 1, the inkjet recording apparatus 100 has an endless belt-shaped conveyance belt 1. The conveyance belt 1 is stretched between rollers 81 and 82. In the inkjet recording apparatus 100, the conveyance belt 1 constitutes a moving unit that conveys the recording medium P.

[0023] (Recording Unit) The inkjet recording apparatus 100 also includes an inkjet head 2 that constitutes a recording unit. The inkjet head 2 ejects ink 7 based on image data to form an ink image on the surface of the recording medium P.

[0024] {Inkjet Head} The inkjet head 2 includes, for example, inkjet heads 2Y, 2M, 2C, and 2K that eject yellow, magenta, cyan, and black inks 7, respectively. Note that the number of inkjet heads 2 and the number of colors are not limited in any way.

[0025] The conveyance belt 1 is fed between the rollers 81, 82 and the tension roller 3 in the direction indicated by the arrow A in FIG. 1. The conveyance belt 1 relatively moves the recording medium P placed on its outer surface in the conveyance direction (second direction) indicated by the arrow B in FIG. 1 with respect to the inkjet head 2.

[0026] Further, on the inner surface of the conveyor belt 1, a suction plate 8 is disposed at a position facing the inkjet head 2. The suction plate 8 sucks and adheres the recording medium P and the conveyor belt 1. The recording medium P is adhered to the conveyor belt 1 and supported by the suction plate 8, and is thus moved relative to the inkjet head 2 while maintaining flatness. Note that the suction plate 8 may not be provided if it is not necessary to maintain the flatness of the recording medium P, or if the flatness of the recording medium P can be maintained by other means.

[0027] Also, in this embodiment, the recording medium P is relatively moved with respect to the inkjet head 2 by operating the conveyor belt 1, but the configuration of the moving unit is not limited to this. The moving unit may be configured to relatively move with respect to the recording medium P by moving the inkjet head 2.

[0028] In the inkjet recording apparatus 100, ink 7 is ejected from the inkjet head 2 based on image data, and an ink image composed of a plurality of dots is formed on the surface of the recording medium P. The inkjet head 2 can use a conventionally known method such as an on-demand method or a continuous method. Examples of the ejection method include electro-mechanical conversion methods such as single cavity type, double cavity type, vender type, piston type, shear mode type, or shared wall type. Alternatively, electro-thermal conversion methods such as thermal inkjet type or bubble jet (registered trademark) type, and electrostatic attraction methods such as spark jet type can be mentioned.

[0029] {ink} The ink 7 used in the inkjet recording apparatus 100 is obtained by dispersing a pigment in a liquid medium. Note that either an aqueous medium or an oily medium can be used as the liquid medium. Conventionally known additives such as surfactants and dispersants may be mixed in the ink 7 as necessary.

[0030] In addition, as the ink 7, phase change ink or UV (ultraviolet) curable ink is also preferably used. The phase change ink is an ink that undergoes a phase change and thickens according to the temperature of the recording medium P after landing on the recording medium P. Furthermore, a two-component reaction type ink that applies a pretreatment agent to the recording medium P and causes a phase change by reacting with the pretreatment agent can also be used.

[0031] As the pigment of the ink 7, in addition to coloring materials, microcapsules containing coloring materials may also be used. The particle size of the pigment is preferably in the range of, for example, 50 nm to 200 nm. The content of the pigment in the ink 7 is preferably in the range of, for example, 0.1 mass% to 15 mass%, and more preferably in the range of 0.5 mass% to 12 mass%.

[0032] (Head module) FIG. 2 is a schematic diagram showing a main part of the line head of the inkjet recording apparatus 100 of the present embodiment.

[0033] The inkjet heads 2Y to 2K are each a line head 150. As shown in FIG. 2, each line head 150 is configured by arranging a plurality of short head modules 151 in the width direction C (first direction) intersecting the conveyance direction B.

[0034] Each head module 151 has a plurality of nozzle openings 152 arranged along the width direction C intersecting the conveyance direction B on the surface facing the recording medium P. In addition, the head modules 151 are arranged so as to have an overlapping region ab where the ends in the width direction C overlap each other.

[0035] Note that the number of the head modules 151 is not limited at all. Also, a plurality of rows of the nozzle openings 152 may be arranged in the conveyance direction B. Each head module 151 is arranged over the entire width of the recording medium P in at least the number required to cover the entire width of the recording medium P in the width direction C. Then, each head module 151 discharges the ink 7 from each nozzle opening 152 toward the recording medium P.

[0036] In the following, as shown in FIG. 2, of the two adjacent head modules 151, the one on the upstream side in the conveyance direction B is referred to as the first head module 151A, and the one on the downstream side is referred to as the second head module 151B. Also, the region excluding the overlapping region ab of the first head module 151A is referred to as the non-overlapping region a, and the region excluding the overlapping region ab of the second head module 151B is referred to as the non-overlapping region b.

[0037] In the present embodiment, the two adjacent head modules 151 each have a plurality of nozzle openings 152 corresponding to the overlapping region ab. Also, the recording medium P and the line head 150 are relatively moved in the conveyance direction B by a moving unit. Then, the moving unit relatively moves the recording medium P so that the corresponding nozzle openings 152 of the adjacent head modules 151 pass over the same location of the recording medium P in the overlapping region ab.

[0038] (Overall control unit) FIG. 3 is a block diagram of the inkjet recording apparatus 100 according to the present embodiment.

[0039] In the inkjet recording apparatus 100, the rasterization processing unit 110, the halftone processing unit 120, and the sorting processing unit 130 are controlled by an overall control unit (control unit) 101. The overall control unit 101 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), and the like. Also, a storage unit 105 including a ROM (Read Only Memory) or the like in which an inkjet recording program and other information are stored is connected to the overall control unit 101. The recording operation of the inkjet recording apparatus 100 is performed by the CPU reading the program and data stored in the ROM and storing them in the RAM, and then executing the program.

[0040] When image data is input, the overall control unit 101 converts the image data into bitmap data in the rasterization processing unit 110 and sends it to the halftone processing unit 120. The halftone processing unit 120 generates dot data from the bitmap data and sends it to the distribution processing unit 130. The distribution processing unit 130 determines whether a pixel in the dot data is to be formed by one of the head modules 151 by distributing the pixels in the dot data to one of the head modules 151.

[0041] The pixels distributed by the distribution processing unit 130 are sent to either the driving unit 140A or the driving unit 140B corresponding to each of the first head module 151A and the second head module 151B. Then, the driving units 140A and 140B eject droplets from the nozzle openings 152 of the head module 151 based on the dot data. The above series of processes are performed for each color of ink ejected from each line head 150.

[0042] That is, the overall control unit 101 controls the ink ejection operations by the plurality of head modules 151 according to the image data. In particular, in the overlapping region ab, the overall control unit 101 controls whether to form a pixel in one of the corresponding nozzle openings 152 of two adjacent head modules 151, so as to perform the ink ejection operations complementarily.

[0043] (Recording operation) FIG. 4 is a flowchart showing the flow of the recording operation by the inkjet recording apparatus 100. As described above, when the overall control unit 101 starts the inkjet recording program, first, the rasterization processing unit 110 executes rasterization processing (step S101). After the execution of the rasterization processing, the overall control unit 101 executes halftone processing by the halftone processing unit 120 (step S102). After the execution of the halftone processing, the overall control unit 101 executes pixel distribution processing by the distribution processing unit 130 (step S103). After the execution of the distribution processing, the overall control unit 101 ejects ink from each line head 150 by the drive units 140A to 140B to record an image (step S104).

[0044] {Distribution Processing} FIG. 5 is a flowchart showing the schematic flow of the pixel distribution processing in step S103 by the inkjet recording apparatus 100 according to the present embodiment.

[0045] First, the distribution processing unit 130 acquires the resolution of the image data (step S1031). In the present embodiment, the resolution of the image data is anisotropic. Specifically, it is assumed that the width direction (main scanning direction) C is 1200 dpi and the conveyance direction (sub-scanning direction) B is 600 dpi.

[0046] The distribution processing unit 130 sets the nozzle switching unit based on the resolution of the image data acquired in step S1031 (step S1032). The nozzle switching unit is a unit that determines how many dots one head module 151 forms continuously in the overlapping region ab before switching to the other head module 151 to form dots. In the storage unit 105, a correspondence table between the resolution of the image data and the nozzle switching unit suitable for the resolution is stored in advance, and the distribution processing unit 130 sets the nozzle switching unit based on the correspondence table.

[0047] The distribution processing unit 130 distributes pixels based on the set nozzle switching unit (step S1033). For example, when the nozzle switching unit is 4, the distribution processing unit 130 distributes pixels so that when 4 dots are formed by the first head module 151A in the overlapping region ab, 4 dots are formed by the second head module 151B.

[0048] FIG. 6 shows a graph showing the relationship between the nozzle switching unit and the density of the overlapping region ab when the head modules 151A and 151B are displaced by 1 / 4 pixel in the transport direction B. In FIG. 6, the horizontal axis represents the nozzle switching unit. Also, in FIG. 6, the vertical axis represents the output value of the sensor in the overlapping region ab, that is, the density. It is assumed that the output values (i.e., normal values) in the non-overlapping regions a and b are 20.

[0049] Also, FIG. 7A shows an example of switching of image data when the nozzle switching unit is 1, and FIG. 7B shows an example of switching of image data when the nozzle switching unit is 4. When the nozzle switching unit is 1, as shown in FIG. 7A, the gap between dots increases, and as shown in FIG. 6, the output value becomes lower than that in the non-overlapping regions a and b. That is, when the nozzle switching unit is 1, when there is a displacement in the transport direction B between the head modules 151, a significant density shift occurs between the overlapping region ab and the non-overlapping regions a and b.

[0050] On the other hand, when the nozzle switching unit is increased, as shown in FIG. 7B, the gap between dots decreases, and as shown in FIG. 6, the output value approaches 20 in the non-overlapping regions a and b. That is, when the nozzle switching unit is increased, even if there is a displacement in the transport direction B between the head modules 151, the density shift between the overlapping region ab and the non-overlapping regions a and b decreases and becomes less noticeable.

[0051] However, it is not preferable to increase the nozzle switching unit too much. As shown in FIG. 6, even if the nozzle switching unit is increased beyond 4, the density difference does not decrease much, while the density shift becomes more visible.

[0052] Specifically, as the visual transfer function for brightness fluctuations (hereinafter referred to as VTF (Visual Transfer Function)), the following approximate formulas (1) and (2) of Dooly are known. In formula (1), l represents the observation distance (mm). In formula (2), f represents the spatial frequency (cycles / mm).

[0053] [Number]

[0054] Fig. 8 shows the VTF when l = 300. In Fig. 8, the vertical axis represents the visual sensitivity to brightness fluctuations, and the horizontal axis represents the spatial frequency (cycles / mm). Fig. 9 shows a table of the correspondence relationship between the nozzle switching unit, the switching period pixel number, and the spatial frequency when the resolution in the main scanning direction C is 1200 dpi. It can be seen from Fig. 9 that as the nozzle switching unit increases, the spatial frequency approaches 1.0. Also, it can be seen from Fig. 8 that as the spatial frequency approaches 1.0, the visual sensitivity becomes maximum. And when the visual sensitivity increases, the density deviation is more easily visually recognized.

[0055] Therefore, in the present embodiment, the distribution processing unit 130 sets the nozzle switching unit so that the visual sensitivity is less than 0.5 (50%). Specifically, as shown in Fig. 8, the visual sensitivity is less than 0.5 when the spatial frequency is 1.8 (cycles / mm) or more. And as shown in Fig. 9, the spatial frequency is 1.8 (cycles / mm) or more when the nozzle switching unit is 13 or less. Therefore, in the correspondence table between the resolution and the nozzle switching unit, the nozzle switching unit is set in the range of 2 to 13.

[0056] With the completion of the pixel distribution by the distribution processing unit 130, the overall control unit 101 completes the distribution process. Then, the overall control unit 101 transitions to step S104 to form an image.

[0057] [Effects of the Embodiment] Conventionally, when there is a positional deviation in the sub-scanning direction B between the head modules 151, as shown in FIGS. 10A and 10B, at the switching position of the head module 151 in the overlapping region ab, a difference in the presence or absence of gaps between dots occurs, and a density deviation occurs between the non-overlapping regions a and b.

[0058] However, the inkjet recording apparatus 100 according to the present embodiment sets a nozzle switching unit according to the combination of the resolutions in the main scanning direction C and the sub-scanning direction B of the image data. Then, based on the nozzle switching unit, the distribution processing unit 130 controls whether to eject the ink 7 from any one of the corresponding nozzle openings 152 in the overlapping region ab. Therefore, in the overlapping region ab, the frequency itself of the density deviation from the non-overlapping regions a and b can be reduced, and the density deviation from the non-overlapping regions a and b can be made less noticeable.

[0059] Also, the inkjet recording apparatus 100 forms circular dots on the recording medium P. Therefore, when forming an image with an anisotropic recording resolution where the resolution in the sub-scanning direction B is lower than the resolution in the main scanning direction C, a density deviation from the non-overlapping regions a and b particularly significantly occurs in the overlapping region ab, but according to the inkjet recording apparatus 100 according to the present embodiment, this can be solved.

[0060] Further, the inkjet recording apparatus 100 according to the present embodiment sets the nozzle switching unit so that the visual sensitivity is less than 50% in the human visual frequency characteristic (VTF). Therefore, even if a density deviation from the non-overlapping regions a and b occurs in the overlapping region ab, the deviation can be made difficult to visually recognize.

[0061] [Other configurations] As described above, specific explanations have been made based on the embodiments according to the present invention, but the present invention is not limited to the above-described embodiments. Of course, various modifications including the scope of the invention described in the claims and its equivalent scope are possible.

[0062] For example, when the nozzle switching unit is 4, the distribution processing unit 130 distributes the pixels so as to switch the head module 151 every 4 dots, but it is not limited to this. For example, when the nozzle switching unit is 4, the distribution processing unit 130 may distribute the image so as to switch the head module 151 on average every 4 dots.

[0063] In addition, although the case where the resolution of the image data is the main scanning direction C1200 dpi × the sub-scanning direction B600 dpi has been exemplified, it is of course not limited to this. For example, the resolution of the image data may be the main scanning direction C1200 dpi × the sub-scanning direction B900 dpi or the like.

[0064] Note that it is preferable to set the corresponding table so that the nozzle switching unit becomes larger as the resolution in the sub-scanning direction B becomes lower. When the resolution in the sub-scanning direction B of the image data is low and the recording operation can be performed at high speed, by increasing the nozzle switching unit, the density deviation between the non-overlapping regions a and b in the overlapping region ab can be made less conspicuous more effectively.

[0065] In addition, in the above, every time one head module 151 forms a plurality of dots continuously by the nozzle switching unit in the main scanning direction C, it is switched so that the other head module 151 forms dots, but it is not limited to this. That is, in the said structure, the switching position between one head module 151 and the other head module 151 may be made the same in a plurality (for example, 8 to 32) of nozzle rows adjacent in the sub-scanning direction B. By adopting such a configuration, the density deviation between the non-overlapping regions a and b at the boundary portion in the sub-scanning direction B of the overlapping region ab can also be made less conspicuous.

[0066] Note that the number of nozzle rows for aligning the switching positions of the head modules 151 in the sub-scanning direction B is also preferably set so that the visual sensitivity is less than 50% in the human visual frequency characteristic (VTF). By adopting such a configuration, the density deviation between the non-overlapping regions a and b at the boundary portion in the sub-scanning direction B of the overlapping region ab can be made even less conspicuous.

[0067] Also, although it has been described above that the droplet discharge device is the inkjet recording device 100, the liquid discharged from the droplet discharge device according to the present invention is not limited to ink.

[0068] However, when the inkjet recording device 100 discharges ink that undergoes a phase change after landing on the recording medium P, it is preferable to apply the present invention. Further, when the inkjet recording device 100 uses the recording medium P coated with the pretreatment agent for causing the phase change, it is particularly preferable to apply the present invention. This is because when dots made of phase change ink with different landing times are connected, the density deviation as described above is likely to occur.

[0069] Also, in the above, an example in which a hard disk, a semiconductor non-volatile memory, etc. are used as the computer-readable medium of the program according to the present invention has been disclosed, but it is not limited to this example. As other computer-readable media, portable recording media such as CD-ROM can be applied. Further, a carrier wave is also applied as a medium for providing the data of the program according to the present invention via a communication line.

Explanation of Signs

[0070] 1 Conveyor belt (moving part) 2 Inkjet head (recording part) 100 Inkjet recording device (droplet discharge device) 101 Overall control unit (control unit) 150 Line head 151 Head module 151A First head module 151B Second head module 152 Nozzle opening ab Overlap region B Conveying direction (sub-scanning direction, second direction) C Width direction (main scanning direction, first direction) P Recording medium

Claims

1. A line head in which a plurality of head modules each having a nozzle row composed of a plurality of nozzle openings arranged in a row along a first direction are arranged along the first direction, and the line head is arranged such that adjacent two head modules have an overlapping region where the ends in the first direction overlap each other, the line head having a recording unit that discharges droplets from the nozzle openings onto a recording medium based on image data, a moving unit that relatively moves the recording medium and the line head in a second direction intersecting the first direction so that the nozzle openings corresponding to the overlapping region of the two head modules can be moved to the same position on the recording medium, and a control unit that controls which of the nozzle openings corresponding to the overlapping region discharges droplets based on a nozzle switching unit. The control unit is a droplet discharge device that sets the nozzle switching unit according to a combination of resolutions in the first direction and the second direction of the image data.

2. The droplet discharge device according to claim 1, wherein the control unit sets different nozzle switching units according to the resolution in the second direction of the image data.

3. The droplet discharge device according to claim 2, wherein the image data has a resolution in the second direction that is less than or equal to the resolution in the first direction.

4. The droplet discharge device according to claim 3, wherein the control unit sets the nozzle switching unit such that the lower the resolution in the second direction of the image data, the larger the nozzle switching unit.

5. The droplet discharge device according to claim 4, wherein the control unit sets the nozzle switching unit such that the visual sensitivity is less than 50% in the human visual frequency characteristic (VTF).

6. The droplet discharge device according to any one of claims 1 to 5, wherein the control unit controls such that the switching positions of the head modules are the same in the first direction in a plurality of the nozzle rows adjacent in the second direction.

7. The droplet ejection device according to claim 6, wherein the control unit sets the switching position of the head module in the second direction so that the visual sensitivity is less than 50% in the human visual frequency characteristic (VTF).

8. The droplet ejection device according to any one of claims 1 to 5, which ejects ink that thickens by a phase change after landing on the recording medium.

9. A line head in which a plurality of head modules each having a nozzle row composed of a plurality of nozzle openings arranged in a row along a first direction are arranged in a plurality along the first direction, and the ends of two adjacent head modules in the first direction are arranged so as to have an overlapping region where the ends overlap each other. A recording method by a droplet ejection device having a line head, A recording step of ejecting droplets from the nozzle openings onto a recording medium based on image data; A moving step of relatively moving the recording medium and the line head in a second direction intersecting the first direction so that the nozzle openings corresponding to the overlapping regions of the two head modules can be moved to the same position on the recording medium; A control step of controlling, based on a nozzle switching unit, whether to eject droplets from any one of the nozzle openings corresponding to the overlapping regions; and The control step is a recording method for setting the nozzle switching unit according to a combination of the resolutions in the first direction and the second direction of the image data.

10. A line head in which a plurality of head modules each having a nozzle row composed of a plurality of nozzle openings arranged in a row along a first direction are arranged in a plurality along the first direction, and the ends of two adjacent head modules in the first direction are arranged so as to have an overlapping region where the ends overlap each other; and A recording unit that ejects droplets from the nozzle openings onto a recording medium based on image data; A computer of a droplet ejection device having a moving unit that relatively moves the recording medium and the line head in a second direction intersecting the first direction so that the nozzle openings corresponding to the overlapping regions of the two head modules can be moved to the same location on the recording medium. Function as a control unit that controls which of the nozzle openings corresponding to the overlapping regions discharges droplets based on a nozzle switching unit. The control unit is a program that sets the nozzle switching unit according to a combination of resolutions in the first direction and the second direction of the image data.

Images