Inkjet printer

Abstract

An inkjet printer (1) comprises: a recording head (20) having a first nozzle row (21R) and a second nozzle row (22R); a light irradiation device (30) having a plurality of irradiation units (36A-36C) in each of which amount of light can be adjusted; and a control device (60). The control device (60) has: an acquisition unit (61) that acquires print data; a print pattern determination unit (62) that determines a print pattern indicating a combination of the presence / absence of discharge of ink from the first nozzle row (21R) and the presence / absence of discharge of ink from the second nozzle row (22R); and an irradiation control unit (63) that adjusts the amount of light of each of the irradiation units (36A-36C) on the basis of the print pattern.

Description

Inkjet printer

[0001] The present invention relates to an inkjet printer that performs printing using photocurable ink.

[0002] Conventionally, inkjet printers have been known that include a recording head that ejects photocurable ink onto a recording medium, a light irradiation device that irradiates the photocurable ink on the recording medium with light, a scanning mechanism that moves the recording head and the light irradiation device in a main scanning direction, and a feed mechanism that moves the recording medium in a sub-scanning direction relative to the recording head and the light irradiation device (see, for example, JP 2019-123217 A). Note that the sub-scanning direction is perpendicular to the main scanning direction. In such inkjet printers, an image is formed on the recording medium by sequentially repeating the movement of the recording head and the light irradiation device in the main scanning direction and the relative movement of the recording medium in the sub-scanning direction.

[0003] Light emitted from the light irradiation device may be reflected inside the printer and incident on the nozzle surface of the recording head. If the reflected light is incident on the nozzle surface of the recording head, the ink in the nozzles may harden, causing the nozzles to clog. If the amount of light emitted from the light irradiation device (hereinafter referred to as light amount) is large, the amount of reflected light increases, making the nozzles more likely to clog. On the other hand, if the light amount of the light irradiation device is small, the ink on the recording medium will not be cured properly. Therefore, it is desirable for the light irradiation device to irradiate light in the right amount.

[0004] Japanese Patent Application Laid-Open Publication No. 2019-123217 describes a control in which a light irradiation device includes multiple light-emitting elements, and during printing, those of the multiple light-emitting elements that do not face the table are turned off. Japanese Patent Application Laid-Open Publication No. 2019-123217 also describes a control in which those of the multiple light-emitting elements that face an image data area (an area where ink is ejected) of a recording medium are turned on, and those that do not face the image data area are turned off. Japanese Patent Application Laid-Open Publication No. 2019-123217 also describes that the above control of turning the light-emitting elements on and off suppresses reflected light from entering the recording head.

[0005] Japanese Patent Application Laid-Open No. 2019-123217

[0006] An object of the present invention is to suppress reflected light from entering the recording head and improve print quality in an inkjet printer equipped with a recording head that ejects photocurable ink and a light irradiation device.

[0007] The inkjet printer disclosed herein includes a recording head having a first nozzle row including a plurality of nozzles arranged in a sub-scanning direction for ejecting a first photo-curable ink toward a recording medium, and a second nozzle row arranged on one side of a main scanning direction perpendicular to the sub-scanning direction with respect to the first nozzle row, the second nozzle row including a plurality of nozzles arranged in the sub-scanning direction for ejecting a second photo-curable ink toward the recording medium. The inkjet printer also includes a scanning mechanism that moves the recording head in the main scanning direction, a feed mechanism that moves the recording head and the recording medium relatively in the sub-scanning direction, a light irradiation device that irradiates light toward the ink ejected from the recording head, and a control device that controls the recording head, the scanning mechanism, the feed mechanism, and the light irradiation device. The light irradiation device has a plurality of irradiation units positioned at different positions in the sub-scanning direction, each of which has an adjustable light intensity. The control device has an acquisition unit that acquires print data including data regarding the ejection operation of the first nozzle row and the second nozzle row, a print pattern determination unit that determines a print pattern that indicates a combination of whether or not ink is ejected from the first nozzle row and whether or not ink is ejected from the second nozzle row based on the print data, and an irradiation control unit that adjusts the light intensity of each irradiation unit of the light irradiation device based on the print pattern.

[0008] According to the inkjet printer, the light irradiation device has multiple irradiation units positioned at different positions in the sub-scanning direction, and each of these irradiation units has an adjustable light intensity. The light intensity of each irradiation unit is adjusted based on a printing pattern indicating a combination of the presence or absence of ink ejection from the first nozzle row and the presence or absence of ink ejection from the second nozzle row. The light intensity of each irradiation unit can be adjusted in accordance with the presence or absence of ink ejection from the first nozzle row and the second nozzle row. By adjusting the light intensity of each irradiation unit, excessive light irradiation from the light irradiation device can be suppressed, thereby effectively suppressing reflected light. This can prevent reflected light from entering the recording head. Furthermore, by adjusting the light intensity of each irradiation unit, sufficient light can be irradiated onto the ink on the recording medium, thereby improving print quality.

[0009] According to the present invention, in an inkjet printer equipped with a recording head that ejects photocurable ink and a light irradiation device, it is possible to suppress reflected light from entering the recording head and improve print quality.

[0010] FIG. 1 is a perspective view of an inkjet printer according to an embodiment. FIG. 2 is a front view of the inkjet printer with the cover open. FIG. 3 is a plan view of a portion of the inkjet printer. FIG. 4 is a diagram showing the arrangement of the recording head and the light irradiation device. FIG. 5 is a block diagram of the control system of the inkjet printer. FIG. 6 is a diagram showing whether or not each ink head ejects ink and the light intensity of each irradiation unit in a first printing pattern. FIG. 7 is a diagram showing whether or not each ink head ejects ink and the light intensity of each irradiation unit in a second printing pattern. FIG. 8 is a diagram showing whether or not each ink head ejects ink and the light intensity of each irradiation unit in a third printing pattern.

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an inkjet printer (hereinafter referred to as a printer) according to the present invention will be described below with reference to the drawings.

[0012] FIG. 1 is a perspective view of a printer 1 according to this embodiment. The symbols F, Rr, L, and R in the figure represent front, rear, left, and right, respectively. The symbol Y represents the main scanning direction, and the symbol X represents the sub-scanning direction. Here, the main scanning direction coincides with the left-right direction. The sub-scanning direction is a direction perpendicular to the main scanning direction, and here coincides with the front-rear direction.

[0013] As shown in Fig. 1, the printer 1 includes a case 10, a front cover 12, and an operation panel 14. Although not shown, a hinge is provided at the rear of the front cover 12. The front cover 12 is rotatably attached to the case 10 by the hinge. The front cover 12 can be opened and closed. Fig. 2 is a front view of the printer 1 with the front cover 12 open.

[0014] As shown in FIG. 2, the printer 1 includes a table 16 that supports the recording medium 5, a recording head 20 that ejects ink toward the recording medium 5, a scanning mechanism 40 that moves the recording head 20 in the main scanning direction, a feed mechanism 50 that moves the recording head 20 and the recording medium 5 relative to each other in the sub-scanning direction, a light irradiation device 30, and a control device 60.

[0015] The printer 1 is a device that forms an image on a recording medium 5 using ink that hardens when irradiated with light (i.e., photocurable ink). The term "image" as used herein includes pictures, patterns, letters, symbols, and the like. The image may be a thin, two-dimensional image or a thick, three-dimensional image. The type of photocurable ink is not particularly limited. In this embodiment, the photocurable ink is an ultraviolet-curable ink that hardens when irradiated with ultraviolet light. The shape of the recording medium 5 is not particularly limited. The recording medium 5 may be a sheet-like member such as recording paper, or a three-dimensional object such as a mobile phone case. The material of the recording medium 5 is also not particularly limited, as long as an image can be formed using ink.

[0016] In this embodiment, the light irradiation device 30 is composed of two ultraviolet lamps 32 arranged on the left and right sides of the recording head 20. However, it is possible to omit one of the ultraviolet lamps 32 on the left or right side. The ultraviolet lamps 32 are fixed to the recording head 20. The ultraviolet lamps 32 are configured to move in the main scanning direction together with the recording head 20. The recording head 20 and the ultraviolet lamps 32 are attached to a carriage 42.

[0017] The scan mechanism 40 includes a guide rail 43 extending in the main scanning direction, an endless belt 44 to which a carriage 42 is fixed, a left pulley 45L and a right pulley 45R around which the belt 44 is wound, and a carriage motor 46 that drives the pulley 45L. The carriage 42 is slidably engaged with the guide rail 43. When the carriage motor 46 is driven, the belt 44 runs and the carriage 42 moves in the main scanning direction. This causes the recording head 20 and the light irradiation device 30 to move in the main scanning direction.

[0018] The feed mechanism 50 is configured to drive the table 16 in the sub-scanning direction to move the recording medium 5 relative to the recording head 20 in the sub-scanning direction. As shown in FIG. 3 , the feed mechanism 50 includes a left slide rail 51L and a right slide rail 51R extending in the sub-scanning direction, a ball screw (not shown) extending in the sub-scanning direction, a slider 52 supporting the table 16, and a feed motor 56 (see FIG. 5 ) for rotating the ball screw. The slider 52 is slidably engaged with the slide rails 51L and 51R. A threaded hole (not shown) that engages with the ball screw is formed in the slider 52. When the feed motor 56 is driven, the ball screw rotates and the slider 52 moves in the sub-scanning direction. This moves the table 16 in the sub-scanning direction, and the recording medium 5 placed on the table 16 moves in the sub-scanning direction.

[0019] 4 is a diagram showing the arrangement of the recording head 20 and the light irradiation device 30. The recording head 20 includes a first head unit 21U and a second head unit 22U.

[0020] The first head unit 21U has an ink head 21K that ejects black ink, an ink head 21Y that ejects yellow ink, an ink head 21M that ejects magenta ink, and an ink head 21C that ejects cyan ink. The black ink, yellow ink, magenta ink, and cyan ink are examples of process color inks. The black ink, yellow ink, magenta ink, and cyan ink have the property of curing when exposed to ultraviolet light, and are examples of "first photocurable inks." The ink heads 21K, 21Y, 21M, and 21C are examples of "first ink heads." In the following description, the ink heads 21K, 21Y, 21M, and 21C will be collectively referred to as the first ink heads 21, as appropriate.

[0021] The second head unit 22U has two ink heads 22W that eject white ink, an ink head 22Pr that ejects primer ink, and an ink head 22Gl that ejects gloss ink. The white ink, primer ink, and gloss ink are examples of spot color inks. The spot color ink may be metallic ink containing metal particles. The spot color ink is an ink that imparts special effects to images formed with process color inks. The white ink forms the base of the image, the primer ink improves the adhesion of the image, and the gloss ink and metallic ink improve the glossiness of the image. The white ink, primer ink, and gloss ink have the property of curing when exposed to ultraviolet light and are examples of "second photocurable inks." The ink heads 22W, 22Pr, and 22Gl are examples of "second ink heads." In the following description, the ink heads 22W, 22Pr, and 22Gl will be collectively referred to as the second ink heads 22.

[0022] Each of the first ink head 21 and the second ink head 22 has a plurality of nozzles 23 aligned in the sub-scanning direction. The nozzles 23 open downward. The nozzles 23 aligned in the sub-scanning direction of the first ink head 21 form a first nozzle row 21R. The nozzles 23 aligned in the sub-scanning direction of the second ink head 22 form a second nozzle row 22R. In this embodiment, the second head unit 22U is disposed to the left and in front of the first head unit 21U. The positions of the first head unit 21U and the second head unit 22U in the sub-scanning direction are different from each other. At least some of the nozzles 23 of the second nozzle row 22R are disposed forward of the first nozzle row 21R. Here, the entire second nozzle row 22R is disposed forward of the first nozzle row 21R.

[0023] As described above, the light irradiation device 30 includes ultraviolet lamps 32 arranged to the left and right of the recording head 20. The ultraviolet lamps 32 have multiple light-emitting elements 34 aligned in the sub-scanning direction. In this embodiment, the control device 60 divides the ultraviolet lamp 32 into three irradiation sections 36A, 36B, and 36C and adjusts the light intensity for each of the irradiation sections 36A, 36B, and 36C. The light intensity of each of the irradiation sections 36A, 36B, and 36C can be adjusted independently. Adjusting the light intensity includes setting the output to 0% (in other words, turning it off), 100%, and setting it to a value greater than 0% but less than 100%.

[0024] The irradiation units 36A, 36B, and 36C are aligned in the sub-scanning direction. The irradiation units 36A, 36B, and 36C are aligned in order from rear to front. In terms of the sub-scanning direction, the irradiation unit 36A is disposed in the same position as the first nozzle row 21R, and the irradiation unit 36B is disposed in the same position as the second nozzle row 22R. The irradiation unit 35C is disposed forward of the first nozzle row 21R and the second nozzle row 22R. The position of the irradiation unit 35C in the sub-scanning direction is different from the positions of the first nozzle row 21R and the second nozzle row 22R in the sub-scanning direction.

[0025] The control device 60 controls the recording head 20, the light irradiation device 30, the scanning mechanism 40, and the feed mechanism 50 based on the print data. Although not shown, the control device 60 is made up of a microcomputer and includes an interface (I / F) for receiving print data and the like from an external device such as a host computer, a central processing unit (CPU) for executing instructions from a control program, a ROM for storing the program executed by the CPU, a RAM used as a working area for expanding the program, and a storage device such as a memory for storing the program and various data. In this embodiment, the control device 60 is located inside the case 10 and is a computer dedicated to the printer 1. However, the control device 60 may also be located outside the case 10 or may be a general-purpose computer such as a personal computer. 5 , the CPU of the control device 60 executes a computer program to function as an acquisition unit 61 that acquires print data including data regarding the ejection operations of the first nozzle row 21R and the second nozzle row 22R, a print pattern determination unit 62 that determines a print pattern indicating a combination of the presence or absence of ink ejection from the first nozzle row 21R and the presence or absence of ink ejection from the second nozzle row 22R based on the print data, and an irradiation control unit 63 that adjusts the light intensity of each irradiation unit 36A, 36B, 36C of the light irradiation device 30 based on the print pattern. Note that the ejection operation of the first nozzle row 21R refers to the ejection operation of each nozzle 23 that constitutes the first nozzle row 21R, and the ejection operation of the second nozzle row 22R refers to the ejection operation of each nozzle 23 that constitutes the second nozzle row 22R. The control device 60 has the acquisition unit 61, the print pattern determination unit 62, and the irradiation control unit 63. The control device 60 is communicably connected to the first ink head 21, the second ink head 22, the left and right ultraviolet lamps 32, the carriage motor 46, and the feed motor 56.

[0026] The printer 1 alternately repeats a pass operation in which ink is ejected from the print head 20 while moving the carriage 42 in the main scanning direction, and a feed operation in which the print medium 5 is moved forward. In this embodiment, the forward direction corresponds to the "feed direction." In this embodiment, the printer 1 performs so-called bidirectional printing. The print head 20 ejects ink when the carriage 42 moves left and when it moves right. However, the printer 1 may also be configured to perform unidirectional printing. The print head 20 may eject ink only when the carriage 42 moves left or only when it moves right.

[0027] In this embodiment, a pass operation and a feed operation are repeated four times in an area of ​​the recording medium 5 facing the first nozzle row 21R, in other words, in the area between the front and rear ends of the first nozzle row 21R, to form an image using process color inks. That is, the number of passes is set to four. However, the number of passes is not limited to four. The number of passes may be two or more, or even one. Similarly, a pass operation and a feed operation are repeated four times in an area of ​​the recording medium 5 facing the second nozzle row 22R, in other words, in the area between the front and rear ends of the second nozzle row 22R, to form an image using spot color inks. The print data includes data related to the ejection operations of the first nozzle row 21R and the second nozzle row 22R for each pass operation. Hereinafter, this data will be referred to as pass data. The print data includes multiple pass data. The irradiation control unit 63 is configured to adjust the light intensity of each of the irradiation units 36A, 36B, and 36C based on the pass data.

[0028] The printer 1 can execute a printing pattern in which ink is ejected from the first nozzle row 21R but not from the second nozzle row 22R (hereinafter referred to as the first printing pattern), a printing pattern in which ink is ejected from both the first nozzle row 21R and the second nozzle row 22R (hereinafter referred to as the second printing pattern), and a printing pattern in which ink is ejected from the second nozzle row 22R but not from the first nozzle row 21R (hereinafter referred to as the third printing pattern). Note that ejecting ink from the first nozzle row 21R means ejecting ink from at least one nozzle 23 in the first nozzle row 21R of the ink heads 21K, 21Y, 21M, and 21C, and not ejecting ink from the first nozzle row 21R means not ejecting ink from any nozzle 23 in the first nozzle row 21R of the ink heads 21K, 21Y, 21M, and 21C. "Ejecting ink from the second nozzle row 22R" means that ink is ejected from at least one nozzle 23 of the second nozzle row 22R of the ink heads 22W, 22Pr, 22Gl, and "not ejecting ink from the second nozzle row 22R" means that ink is not ejected from any nozzle 23 of the second nozzle row 22R of the ink heads 22W, 22Pr, 22Gl. Next, the control of the light irradiation device 30 for each print pattern will be described.

[0029] For the first printing pattern, the irradiation control unit 63 of the control device 60 adjusts the light intensity of the irradiation units 36A-36C of the ultraviolet lamp 32 as shown in FIG. 6 . That is, the irradiation control unit 63 turns on the irradiation units 36A-36B and turns off the irradiation unit 36C. The irradiation control unit 63 turns off the irradiation unit 36C, which is the farthest from the first nozzle row 21R in the sub-scanning direction among the irradiation units 36A-36C. Since ink is not ejected from the second nozzle row 22R for the first printing pattern, insufficient ink curing does not occur even if the irradiation unit 36C is turned off. This prevents excessive irradiation from the ultraviolet lamp 32. Furthermore, the irradiation control unit 63 controls the light intensity of the irradiation units 36A-36B so that it increases toward the front. The light intensity of the irradiation unit 36B is greater than that of the irradiation unit 36A. Here, the irradiation control unit 63 sets the output of the irradiation units 36A, 36B, and 36C to 50%, 100%, and 0%, respectively. As a result, the ink ejected from the first nozzle row 21R does not harden immediately after landing on the recording medium 5, but hardens after it has sufficiently spread and wetted. This makes it possible to obtain an image with good color development. It is preferable that the total light amount of the irradiation units 36A to 36B is set so that the integrated light amount received by the ink matches the critical exposure amount of the ink (the amount of light at which the ink completely hardens). This allows the ink to be irradiated with just the right amount of light.

[0030] For the second printing pattern, the irradiation control unit 63 of the control device 60 adjusts the light intensity of the irradiation units 36A-36C of the ultraviolet lamp 32 as shown in FIG. 7 . That is, the irradiation control unit 63 turns on all of the irradiation units 36A-36C. The irradiation control unit 63 controls the irradiation units 36A-36C so that the light intensity of the frontmost irradiation unit 36C is greater than the light intensity of each of the other irradiation units 36A-36B. Here, the irradiation control unit 63 sets the outputs of the irradiation units 36A, 36B, and 36C to 50%, 50%, and 100%, respectively. Note that, for the second printing pattern as well, it is preferable that the total light intensity of the irradiation units 36A-36C be set so that the integrated light amount received by the ink matches the critical exposure amount of the ink.

[0031] For the third printing pattern, the irradiation control unit 63 of the control device 60 adjusts the light intensity of the irradiation units 36A-36C of the ultraviolet lamp 32 as shown in FIG. 8 . That is, the irradiation control unit 63 turns off the irradiation unit 36A and turns on the irradiation units 36B-36C. Of the irradiation units 36A-36C, the irradiation control unit 63 turns off the irradiation unit 36A, which is upstream of the second nozzle row 22R in the sub-scanning direction. Since ink is not ejected from the first nozzle row 21R for the third printing pattern, insufficient ink curing does not occur even if the irradiation unit 36A is turned off. This prevents excessive irradiation from the ultraviolet lamp 32. Furthermore, the irradiation control unit 63 controls the irradiation units 36B-36C so that the light intensity increases toward the front. The light intensity of the irradiation unit 36C is greater than that of the irradiation unit 36B. Here, the irradiation control unit 63 sets the output of the irradiation units 36A, 36B, and 36C to 0%, 50%, and 100%, respectively. As a result, the ink ejected from the second nozzle row 22R does not harden immediately after landing on the recording medium 5, but hardens after it has sufficiently spread out. In the third printing pattern as well, it is preferable that the total light amount of the irradiation units 36B to 36C is set so that the integrated light amount received by the ink matches the critical exposure amount of the ink.

[0032] The print pattern determination unit 62 of the control device 60 determines which of the first print pattern, the second print pattern, or the third print pattern to execute for each pass operation based on the print data acquired by the acquisition unit 61. The illumination control unit 63 adjusts the light intensity of the illumination units 36A to 36C according to the print pattern for each pass operation. The illumination control unit 63 adjusts the light intensity of the illumination units 36A to 36C for each pass data.

[0033] Next, various effects brought about by the printer 1 according to this embodiment will be described.

[0034] According to the printer 1 of this embodiment, the light irradiation device 30 has multiple irradiation sections 36A-36C aligned in the sub-scanning direction, and each of these irradiation sections 36A-36C has adjustable light intensity. The light intensity of each of the irradiation sections 36A-36C is adjusted based on the print pattern. Excessive light irradiation from the light irradiation device 30 can be prevented, effectively suppressing reflected light. This prevents reflected light from reaching the recording head 20, effectively preventing clogging of the nozzles 23 of the recording head 20. This eliminates the need for frequent cleaning of the recording head 20 and avoids the consumption of large amounts of ink for cleaning. Furthermore, sufficient light irradiation of the ink on the recording medium 5 can improve print quality.

[0035] In this embodiment, the output of at least one of the irradiation units 36A to 36C is set to be greater than 0% and less than 100%. This embodiment makes it easier to irradiate the ink on the recording medium 5 with just the right amount of light, compared to control that simply switches the irradiation units 36A to 36C ON / OFF (in other words, control that simply switches the output of the irradiation units 36A to 36C between 100% and 0%).

[0036] The irradiation control unit 63 is configured to adjust the light intensity of the irradiation units 36A to 36C based on the print pattern for each pass operation. The print data includes pass data, which is data related to the ejection operation of the first nozzle row 21R and the second nozzle row 22R for each pass operation, and the irradiation control unit 63 is configured to adjust the light intensity of the irradiation units 36A to 36C based on the pass data. This makes it possible to eliminate any excess or deficiency in the light intensity of the irradiation units 36A to 36C for each pass operation.

[0037] The positions of the first nozzle row 21R and the second nozzle row 22R in the sub-scanning direction may be partially the same, but in this embodiment, they are different. The second nozzle row 22R is disposed forward of the first nozzle row 21R. The nozzles 23 of the second nozzle row 22R are disposed forward of the first nozzle row 21R. This more effectively utilizes the aforementioned control of adjusting the light intensity of the irradiation units 36A to 36C arranged in the front-to-rear direction. For example, by turning off the irradiation unit 36C for the first print pattern and turning off the irradiation unit 36A for the third print pattern, it is possible to effectively prevent reflected light from entering the recording head 20.

[0038] As shown in FIG. 6 , the light irradiation device 30 includes an irradiation unit 36A arranged on one side of the first nozzle row 21R in the main scanning direction, an irradiation unit 36B arranged on one side of the second nozzle row 22R in the main scanning direction and in front of the irradiation unit 36A, and an irradiation unit 36C arranged in front of the irradiation unit 36B. For the first print pattern, the first nozzle row 21R ejects ink, while the second nozzle row 22R does not eject ink. The irradiation control unit 63 turns on the irradiation unit 36A, turns on the irradiation unit 36B, and turns off the irradiation unit 36C. This allows the ink ejected from the first nozzle row 21R to be sufficiently cured, and by eliminating irradiation from the irradiation unit 36C, excessive irradiation from the light irradiation device 30 can be prevented. Reflected light toward the recording head 20 can be effectively suppressed.

[0039] Furthermore, according to this embodiment, when printing the first pattern, the light intensity of the irradiation unit 36B is greater than the light intensity of the irradiation unit 36A, making it possible to obtain a high-quality image while suppressing reflected light.

[0040] 7, the light irradiation device 30 has an irradiation unit 36A arranged on one side of the first nozzle row 21R in the main scanning direction, an irradiation unit 36B arranged on one side of the second nozzle row 22R in the main scanning direction and in front of the irradiation unit 36A, and an irradiation unit 36C arranged in front of the irradiation unit 36B. For the second printing pattern, the first nozzle row 21R ejects ink, and the second nozzle row 22R ejects ink. The irradiation control unit 63 turns on the irradiation unit 36A, turns on the irradiation unit 36B, and turns on the irradiation unit 36C. This allows the ink ejected from the first nozzle row 21R and the second nozzle row 22R to be sufficiently cured.

[0041] Furthermore, according to this embodiment, when printing the second pattern, the light intensity of the irradiation unit 36C is greater than the light intensity of the irradiation unit 36B, making it possible to obtain a high-quality image while suppressing reflected light.

[0042] As shown in FIG. 8 , the light irradiation device 30 includes an irradiation unit 36A arranged on one side of the first nozzle row 21R in the main scanning direction, an irradiation unit 36B arranged on one side of the second nozzle row 22R in the main scanning direction and in front of the irradiation unit 36A, and an irradiation unit 36C arranged in front of the irradiation unit 36B. For the third print pattern, the first nozzle row 21R does not eject ink, and the second nozzle row 22R ejects ink. The irradiation control unit 63 turns off the irradiation unit 36A, turns on the irradiation unit 36B, and turns on the irradiation unit 36C. This allows the ink ejected from the second nozzle row 22R to be sufficiently cured, and by eliminating irradiation from the irradiation unit 36A, excessive irradiation from the light irradiation device 30 can be prevented. Reflected light toward the recording head 20 can be effectively suppressed.

[0043] Furthermore, according to this embodiment, when printing the third pattern, the light intensity of the irradiation unit 36C is greater than the light intensity of the irradiation unit 36B, making it possible to obtain a high-quality image while suppressing reflected light.

[0044] Although one embodiment of the present invention has been described above, the embodiment is merely an example, and various other embodiments are possible.

[0045] In the above embodiment, the number of first ink heads 21 and second ink heads 22 is four, but there is no limitation on the number of ink heads 21 and second ink heads 22. Furthermore, the recording head 20 may include one or more other ink heads in addition to the first ink head 21 and second ink head 22.

[0046] The scan mechanism is not limited to the scan mechanism 40 of the above embodiment as long as it can move the recording head 20 in the main scanning direction. The feed mechanism is not limited to the feed mechanism 50 of the above embodiment as long as it can move the recording medium 5 relatively to the recording head 20 in the sub-scanning direction. The feed mechanism may include a feed roller that transports the recording medium 5 forward. The feed mechanism may also be a mechanism that moves the recording head 20 in the sub-scanning direction while keeping the recording medium 5 stationary. The printer is not limited to a flatbed printer, and may also be a roll-to-roll printer.

[0047] The photo-curable ink (first photo-curable ink) ejected by the first nozzle row 21R is not limited to a process color, and the photo-curable ink (second photo-curable ink) ejected by the second nozzle row 22R is not limited to a spot color.

[0048] In the above embodiment, the entire second nozzle row 22R of the second ink head 22 is disposed forward of the first nozzle row 21R of the first ink head 21, but only some of the nozzles 23 of the second nozzle row 22R may be disposed forward of the first nozzle row 21R. Some of the nozzles 23 of the first nozzle row 21R and some of the nozzles 23 of the second nozzle row 22R may be disposed at the same position in the sub-scanning direction.

[0049] In the above embodiment, the ultraviolet lamp 32 is divided into three irradiation sections 36A to 36C, but the number of irradiation sections is not limited to three. The number of irradiation sections may be two, or may be four or more.

[0050] In the first printing pattern, the outputs of the irradiation units 36A and 36B are not limited to 50% and 100%, respectively. The outputs of the irradiation units 36A and 36B may be equal to each other. The light intensity of the irradiation unit 36B may be less than the light intensity of the irradiation unit 36A. In the third printing pattern, the outputs of the irradiation units 36B and 36C are not limited to 50% and 100%, respectively. The outputs of the irradiation units 36B and 36C may be equal to each other. The light intensity of the irradiation unit 36C may be less than the light intensity of the irradiation unit 36B. In the second printing pattern, the outputs of the irradiation units 36A, 36B, and 36C are not limited to 50%, 50%, and 100%, respectively. The outputs of two or three of the irradiation units 36A, 36B, and 36C may be equal to each other. The light intensity of the irradiation unit 36C may be less than the light intensity of the irradiation unit 36A or 36B.

[0051] In the above embodiment, the position of the irradiation unit 35A in the sub-scanning direction is generally equal to the position of the first nozzle row 21R in the sub-scanning direction, but it may be partially equal to that. Similarly, the position of the irradiation unit 35B in the sub-scanning direction may be generally equal to the position of the second nozzle row 22R in the sub-scanning direction, or it may be partially equal to that.

[0052] REFERENCE SIGNS LIST 1 Inkjet printer 5 Recording medium 20 Recording head 21 First ink head 21R First nozzle row 22 Second ink head 22R Second nozzle row 30 Light irradiation device 32 Ultraviolet lamp 36A Irradiation section (first irradiation section) 36B Irradiation section (second irradiation section) 36C Irradiation section (third irradiation section) 40 Scanning mechanism 50 Feed mechanism 60 Control device 61 Acquisition section 62 Print pattern determination section 63 Irradiation control section

Claims

1. A recording head having: a first nozzle row in which a plurality of nozzles for ejecting a first photocurable ink toward a recording medium are arranged in the sub-scanning direction; and a second nozzle row arranged in the main scanning direction perpendicular to the sub-scanning direction relative to the first nozzle row, and in which a plurality of nozzles for ejecting a second photocurable ink toward the recording medium are arranged in the sub-scanning direction; A scanning mechanism that moves the recording head in the main scanning direction, A feed mechanism that moves the recording head and the recording medium relative to each other in the sub-scanning direction, A light irradiation device that irradiates light onto the ink ejected from the recording head, The device comprises the recording head, the scanning mechanism, the feed mechanism, and a control device for controlling the light irradiation device, The light irradiation device has a plurality of irradiation units whose positions in the sub-scanning direction are different from each other and whose light intensity can be adjusted. The control device is An acquisition unit that acquires print data including data relating to the ejection operation of the first nozzle row and the second nozzle row, A print pattern determination unit determines a print pattern that indicates a combination of whether or not ink is ejected from the first nozzle row and whether or not ink is ejected from the second nozzle row, based on the print data. An inkjet printer having an irradiation control unit that adjusts the amount of light in each irradiation unit of the light irradiation device based on the printing pattern.

2. The control device is configured to alternately repeat a path operation, which ejects ink while moving the recording head in the main scanning direction, and a feed operation, which moves the recording head and the recording medium relative to each other in the sub-scanning direction. The inkjet printer according to claim 1, wherein the irradiation control unit is configured to adjust the light intensity of each irradiation unit based on the print pattern for each pass operation.

3. The control device is configured to alternately repeat a path operation, which ejects ink while moving the recording head in the main scanning direction, and a feed operation, which moves the recording head and the recording medium relative to each other in the sub-scanning direction. The print data includes path data, which is data relating to the ejection operation of the first nozzle row and the second nozzle row for each pass operation. The inkjet printer according to claim 1, wherein the print pattern determination unit determines the print pattern based on the path data.

4. The first photocurable ink is a process color ink, The inkjet printer according to claim 1, wherein the second photocurable ink is a special color ink.

5. In the relative movement of the recording medium and the recording head in the sub-scanning direction by the feed mechanism, when the direction of movement of the recording medium relative to the recording head is defined as the feed direction, The inkjet printer according to claim 1, wherein at least some of the nozzles of the second nozzle row are arranged on the feed direction side of the first nozzle row.

6. The aforementioned light irradiation device is A first irradiation unit is positioned in one of the main scanning directions of the first nozzle row, and its position in the sub-scanning direction is partially or entirely equal to the position of the first nozzle row in the sub-scanning direction. A second irradiation unit is positioned on one of the main scanning directions of the second nozzle row and on the feed direction side of the first irradiation unit, and its position in the sub-scanning direction is partially or entirely equal to the position of the second nozzle row in the sub-scanning direction, The system includes a third irradiation unit, which is positioned on the feed direction side of the second irradiation unit and whose position in the sub-scanning direction is different from the position of the second nozzle row in the sub-scanning direction. The inkjet printer according to claim 5, wherein the irradiation control unit is configured to light up the first irradiation unit, light up the second irradiation unit, and turn off the third irradiation unit when the first nozzle row ejects the first photocurable ink and the second nozzle row does not eject the second photocurable ink.

7. The inkjet printer according to claim 6, wherein the irradiation control unit is configured to make the light intensity of the second irradiation unit greater than the light intensity of the first irradiation unit when the first nozzle row ejects the first photocurable ink and the second nozzle row does not eject the second photocurable ink.

8. The aforementioned light irradiation device is A first irradiation unit is positioned in one of the main scanning directions of the first nozzle row, and its position in the sub-scanning direction is partially or entirely equal to the position of the first nozzle row in the sub-scanning direction. A second irradiation unit is positioned on one of the main scanning directions of the second nozzle row and on the feed direction side of the first irradiation unit, and its position in the sub-scanning direction is partially or entirely equal to the position of the second nozzle row in the sub-scanning direction, The system includes a third irradiation unit, which is positioned on the feed direction side of the second irradiation unit and whose position in the sub-scanning direction is different from the position of the second nozzle row in the sub-scanning direction. The inkjet printer according to claim 5, wherein the irradiation control unit is configured to turn off the first irradiation unit, turn on the second irradiation unit, and turn on the third irradiation unit when the first nozzle row does not eject the first photocurable ink and the second nozzle row ejects the second photocurable ink.

9. The inkjet printer according to claim 8, wherein the irradiation control unit is configured to make the light intensity of the third irradiation unit greater than the light intensity of the second irradiation unit when the first nozzle row does not eject the first photocurable ink and the second nozzle row ejects the second photocurable ink.

10. The inkjet printer according to any one of claims 6 to 9, wherein the irradiation control unit is configured to light up the first irradiation unit, the second irradiation unit, and the third irradiation unit when the first nozzle row ejects the first photocurable ink and the second nozzle row ejects the second photocurable ink.

11. The inkjet printer according to claim 10, wherein the irradiation control unit is configured to make the light intensity of the third irradiation unit greater than the light intensity of the second irradiation unit when the first nozzle row ejects the first photocurable ink and the second nozzle row ejects the second photocurable ink.