inkjet printer

Abstract

To achieve simplification of communication path configuration of a light irradiation device and stabilization of printed matter quality in an ink jet printer comprising a plurality of light irradiation devices.SOLUTION: An ink jet printer 10 comprises: an ink head 40 which discharges a photocurable ink onto a recording medium 11; a first light irradiation device 61 and a second light irradiation device 62 that irradiate the photocurable ink with light; a controller 80 which controls the ink head 40, the first light irradiation device 61 and the second light irradiation device 62; and a transmission path 60 which connects the controller 80, the first light irradiation device 61 and the second light irradiation device 62 in series. When the controller 80 determines that timing at which an operation state of the first light irradiation device 61 is changed and timing at which an operation state of the second light irradiation device 62 is changed are coincident, the controller performs adjustment for shifting any one with respect to the other.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an inkjet printer.

Background Art

[0002] Conventionally, an inkjet printer is known that includes a nozzle for ejecting a photocurable ink onto a recording medium, a light irradiation device for irradiating light to cure the photocurable ink, and a control device for controlling the light irradiation device, and performs printing on the recording medium by an inkjet method. In such an inkjet printer, the light irradiated from the light irradiation device may be reflected and cure the photocurable ink adhering to the nozzle. When the photocurable ink adhering to the nozzle cures, there is a risk of causing clogging of the nozzle. In order to avoid clogging of the nozzle, the light irradiation device is controlled by the control device so that light is irradiated only to the area where irradiation is required.

[0003] For example, Patent Document 1 discloses an inkjet printer that controls the lighting and extinguishing of a light irradiation device based on the position of an ink head on which a nozzle is mounted. In this inkjet printer, furthermore, the intensity of the irradiated light is controlled according to the moving speed of the ink head and the height from the recording medium to the nozzle.

[0004] The above inkjet printer includes a light irradiation device arranged on the left side of the ink head and a light irradiation device arranged on the right side. The control device controls the two light irradiation devices. According to the above inkjet printer, when the ink head moves to the left while ejecting ink, the ink after ejection can be immediately cured by the light irradiation device on the right side. When the ink head moves to the right while ejecting ink, the ink after ejection can be immediately cured by the light irradiation device on the left side.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2011-148126 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Incidentally, when the number of light irradiation devices increases, the number of signal lines connecting the control device and the light irradiation devices also increases, making the communication path more complex. One example of a connection method between a control device and a light irradiation device is connection using I / O ports. In the case of connection using I / O ports, multiple light irradiation devices can be controlled by a single control device. However, since the connection method using I / O ports transmits signals in parallel using multiple signal lines, the number of signal lines connecting the control device and the light irradiation devices increases. Also, in the case of connection using I / O ports, since signals are transmitted in parallel using multiple signal lines, control is performed to synchronize the timing of transmission between terminals. Therefore, in the case of complex control, such as controlling multiple light irradiation devices simultaneously, electromagnetic interference between signal lines is a concern.

[0007] Alternatively, the control device and the light irradiation device can be connected using serial communication. This method transmits signals one bit at a time over a single signal line, thus avoiding electromagnetic interference. However, if multiple control devices are installed and multiple light irradiation devices are connected to each control device using serial communication, a separate control device and signal line are required for each light irradiation device, complicating the communication path.

[0008] Therefore, it is thought that the number of control devices and signal lines can be reduced by connecting a control device and two or more light irradiation devices in series using serial communication, for example. However, if the timing of sending a signal from the control device to one light irradiation device and the timing of sending a signal to another light irradiation device overlap, those signals may interfere with each other. In other words, a signal collision may occur. When a signal collision occurs, the intended signal may not be sent to the light irradiation device, and the light irradiation device may not be able to perform the desired irradiation. For example, light may not be irradiated in the area where it should be irradiated, resulting in insufficient irradiation. This can lead to poor curing of photocurable ink and cause ink bleeding in printed materials. Therefore, a signal collision leads to a decrease in the quality of printed materials.

[0009] The present invention has been made in view of the above, and its purpose is to simplify the equipment configuration of the communication path of the light irradiation devices and to stabilize the quality of the printed material in an inkjet printer equipped with multiple light irradiation devices. [Means for solving the problem]

[0010] The inkjet printer according to the present invention comprises: a platen on which a recording medium is placed; an ink head positioned above the platen and ejecting photocurable ink; a moving mechanism that reciprocates the ink head relative to the recording medium placed on the platen in the main scanning direction; a first light irradiation device and a second light irradiation device that irradiate light toward the photocurable ink ejected onto the recording medium; a control device that controls the ink head, the first light irradiation device and the second light irradiation device; and a transmission path that connects the control device at a single point and connects the control device, the first light irradiation device and the second light irradiation device in series or parallel. The control device includes: an irradiation control unit for changing the operating state of the first light irradiation device and the second light irradiation device; a first acquisition unit for acquiring a first timing which is the timing for changing the operating state of the first light irradiation device; a second acquisition unit for acquiring a second timing which is the timing for changing the operating state of the second light irradiation device; and an adjustment unit for determining whether the first timing and the second timing coincide, and if it is determined that the first timing and the second timing coincide, shifting one of the first timing and the second timing relative to the other.

[0011] In the inkjet printer of the present invention, the control device is connected to the first light irradiation device and the second light irradiation device at a single point. Therefore, the equipment configuration of the communication path is simplified. Furthermore, the adjustment unit determines whether there is a case where the timing for changing the operating state of the first light irradiation device (first timing) and the timing for changing the operating state of the second light irradiation device (second timing) coincide. If there is a case where the first timing and the second timing coincide, it is possible to avoid collisions between the signal transmitted from the control device to the first light irradiation device and the signal transmitted from the control device to the second light irradiation device by shifting either the first timing or the second timing. Therefore, irradiation defects caused by signal collisions can be avoided, and a deterioration in the quality of printed materials can be prevented. [Effects of the Invention]

[0012] According to the present invention, in an inkjet printer equipped with multiple light irradiation devices, the equipment configuration of the communication path of the light irradiation devices can be simplified, and the quality of the printed material can be stabilized. [Brief explanation of the drawing]

[0013] [Figure 1] This is a perspective view of a printer according to one embodiment. [Figure 2] This is a front view of a printer according to one embodiment. [Figure 3] This is a schematic diagram showing the configuration of the bottom surface of an ink head and light irradiation device according to one embodiment. [Figure 4] This is a block diagram of a printer control device according to one embodiment. [Figure 5A] This diagram shows the first light illuminator lit up while moving in the forward direction. [Figure 5B] This diagram shows the second light illuminator lit up while moving in the forward direction. [Figure 5C] This diagram shows the first light irradiation device turning off while moving in the forward direction. [Figure 5D] This diagram shows the second light irradiation device turning off while moving in the forward direction. [Figure 5E] This diagram shows the timing of switching off the first light irradiation device. [Figure 6] This is a flowchart showing the printing procedure for an image according to one embodiment. [Figure 7] This is an explanatory diagram of an ink head and light irradiation device according to another embodiment. [Figure 8] This graph shows the change in the irradiation dose of a light irradiation device over a certain period of time. [Figure 9] This is a schematic diagram showing the configuration of the bottom surface of the ink head and light irradiation device according to another embodiment. [Modes for carrying out the invention]

[0014] Hereinafter, an inkjet printer (hereinafter referred to as "printer") according to an embodiment of the present invention will be described with reference to the drawings. Note that the embodiments described herein are not intended to particularly limit the present invention. In addition, members and parts having the same function are denoted by the same reference numerals, and redundant descriptions are omitted or simplified as appropriate.

[0015] FIG. 1 is a perspective view of a printer 10 according to the present embodiment. The printer 10 is a so-called Roll-to-Roll type inkjet printer. The printer 10 performs printing on a recording medium 11. In the following description, for convenience, the directions of the printer 10 are defined as follows. When the printer 10 is viewed from the front, the direction away from the printer 10 is the front, and the direction approaching the printer 10 is the rear. Left, right, up, and down respectively mean left, right, up, and down when the printer 10 is viewed from the front. The reference signs F, Rr, L, R, U, and D in the drawings respectively mean front, rear, left, right, up, and down. The reference sign Y in the drawings indicates the main scanning direction. Here, the main scanning direction Y is the left-right direction. The reference sign X indicates the sub-scanning direction. Here, the sub-scanning direction X is the front-rear direction and is orthogonal to the main scanning direction Y in a plan view. The reference sign Z indicates the up-down direction. The up-down direction Z is orthogonal to the main scanning direction Y in a front view. However, the above directions are merely defined for convenience of explanation and do not limit the installation mode of the printer 10 in any way, nor do they limit the present invention in any way.

[0016] As shown in FIG. 1, the printer 10 performs printing on a recording medium 11. The recording medium 11 is, for example, formed in a long strip and used by being wound in a roll shape. Note that the recording medium 11 may be a sheet-like material obtained by cutting a roll-shaped one into a predetermined length. The recording medium 11 is, for example, recording paper. However, the recording medium 11 is not limited to recording paper. For example, the recording medium 11 includes sheets formed from resin materials such as polyvinyl chloride (PVC) and polyester, and sealing materials composed of a base paper and a release paper laminated on the base paper and coated with an adhesive.

[0017] As shown in Figures 1 and 2, the printer 10 comprises a platen 12, a carriage movement mechanism 20, a carriage 30, a main body case 70, legs 72, and a control device 80.

[0018] The platen 12 is a component that supports the recording medium 11 during printing. The platen 12 extends in the main scanning direction Y. The recording medium 11 is placed on the platen 12. The platen 12 is provided in the main body case 70.

[0019] As shown in Figure 2, the carriage movement mechanism 20 is a mechanism for moving the carriage 30 in the main scanning direction Y. The carriage movement mechanism 20 comprises a guide rail 21, a pulley 22, a pulley 23, an endless belt 24, and a carriage motor 25. The guide rail 21 guides the movement of the carriage 30 in the main scanning direction Y. The guide rail 21 is located above the platen 12. The guide rail 21 is provided on the main case 70. The guide rail 21 extends in the main scanning direction Y. The pulley 22 is provided to the left of the left end of the guide rail 21. The pulley 23 is provided to the right of the right end of the guide rail 21. The belt 24 is wrapped around the pulleys 22 and 23. The carriage motor 25 is connected to the right pulley 23. However, the carriage motor 25 may also be connected to the left pulley 22. The carriage motor 25 is driven, causing the pulley 23 to rotate, which in turn causes the belt 24 to travel between the pulley 22 and the pulley 23.

[0020] As shown in Figure 2, the carriage 30 is attached to the belt 24. The carriage 30 is engaged with the guide rail 21 and is slidably mounted on the guide rail 21. The carriage 30 is equipped with a plurality of ink heads 40, a first light irradiation device 61, and a second light irradiation device 62. Photocurable ink (photocurable ink) is ejected from the ink heads 40 onto the recording medium 11 placed on the platen 12. The photocurable ink ejected onto the recording medium 11 is cured when light is irradiated from the first light irradiation device 61 and the second light irradiation device 62. Driven by the carriage motor 25, the belt 24 moves, causing the carriage 30 to move in the main scanning direction Y. Consequently, the plurality of ink heads 40 mounted on the carriage 30, the first light irradiation device 61, and the second light irradiation device 62 move in the main scanning direction Y.

[0021] As shown in Figure 2, the carriage 30 is equipped with multiple ink heads 40. As shown in Figure 3, the ink heads 40 are formed in such a shape that the length in the sub-scanning direction X is longer than the length in the main scanning direction Y. The multiple ink heads 40 are formed to have the same shape and size. The ink head 40 is equipped with multiple first nozzles 41 arranged in the sub-scanning direction X, multiple second nozzles 42 arranged in the sub-scanning direction X, and a nozzle surface 43 on which the first nozzles 41 and second nozzles 42 are formed. Since the first nozzles 41 and second nozzles 42 are minute, they are represented by straight lines in Figure 3. The first nozzles 41 and second nozzles 42 of the ink head 40 eject photocurable ink onto the recording medium 11. In this embodiment, the printer 10 is equipped with three ink heads 40, but the number of ink heads 40 is not limited to three. Furthermore, although the ink head 40 is equipped with two rows of nozzles, a first nozzle 31 and a second nozzle 32, it may also be equipped with one row of nozzles or three or more rows of nozzles.

[0022] Photocurable inks have the property of hardening when irradiated with light (e.g., ultraviolet or infrared light). Photocurable inks (e.g., ultraviolet-curable inks and infrared-curable inks) contain a coloring agent such as a pigment, a photopolymerizable monomer, and a photopolymerization initiator, and may optionally contain other various additives such as photosensitizers, polymerization inhibitors, scavengers, antioxidants, ultraviolet absorbers, plasticizers, surfactants, leveling agents, thickeners, dispersants, defoamers, preservatives, solvents, etc. Photocurable inks are colored inks. Photocurable inks include, for example, process color inks and white inks. For example, process color inks include cyan ink, magenta ink, yellow ink, black ink, light cyan ink, and light magenta ink. Note that photocurable inks may also be colorless inks. For example, ultraviolet-curable inks are a type of photocurable ink.

[0023] As shown in Figure 2, the carriage 30 includes a first light irradiator 61 and a second light irradiator 62. The first light irradiator 61 and the second light irradiator 62 irradiate light (typically ultraviolet light) toward the photocurable ink ejected onto the recording medium 11. This forms an ink layer on the recording medium 11. Here, as shown in Figure 3, the first light irradiator 61 and the second light irradiator 62 each include a plurality of ultraviolet irradiation LEDs 63. The plurality of ultraviolet irradiation LEDs 63 are arranged in the main scanning direction Y and the sub-scanning direction X. However, the arrangement of the ultraviolet irradiation LEDs 63 is not limited to this. The ultraviolet irradiation LEDs 63 may be arranged in only one direction, either the main scanning direction Y or the sub-scanning direction X, or only one ultraviolet irradiation LED 63 may be arranged. The first light irradiator 61 and the second light irradiator 62 are installed above the platen 12. The first light irradiator 61 is located to the left of the ink head 40. The second light irradiator 42 is located to the right of the ink head 40. The first light irradiator 61, the second light irradiator 62, and the ink head 40 are positioned in a aligned position with respect to the sub-scanning direction X. In this embodiment, the first light irradiator 61 and the second light irradiator 62 are positioned to the left and right of the ink head 40, respectively, but this arrangement is not limited. For example, the first light irradiator 61 and the second light irradiator 62 may be positioned to the left of the ink head 40. Also, in this embodiment, the first light irradiator 61, the second light irradiator 62, and the ink head 40 are positioned in a aligned position with respect to the sub-scanning direction X, but the positions of the first light irradiator 61, the second light irradiator 62, and the ink head 40 in the sub-scanning direction X are not limited to this. For example, the first light irradiator 61 or the second light irradiator 62 may be positioned so as not to overlap with part or all of the ink head 40 in the sub-scanning direction X. In addition, the carriage 30 is equipped with two light irradiators, but it may be equipped with three or more light irradiators. Furthermore, in this embodiment, the first light irradiation device 61 and the second light irradiation device 62 are provided on the carriage 30, but they may also be installed in the printer 10 in a position where they can irradiate light onto the recording medium 11 placed on the platen 12.

[0024] As shown in Figure 2, the printer 10 is equipped with a media transport mechanism 50. The media transport mechanism 50 is a mechanism that moves the recording medium 11 placed on the platen 12 in the sub-scanning direction X. The media transport mechanism 50 includes a grid roller 51, a pinch roller 52, and a feed motor 53 (see Figure 4). The grid roller 51 is provided on the platen 12. Here, a part of the grid roller 51 is embedded in the platen 12. The pinch roller 52 is positioned above the grid roller 51 so as to face it in the vertical direction. The pinch roller 52 is a member that presses down on the recording medium 11 from above. The pinch roller 52 may be configured to move vertically according to the thickness of the recording medium 11. Note that the position and number of the grid roller 51 and pinch roller 52 are not particularly limited. The feed motor 53 is connected to the grid roller 51. With the recording medium 11 sandwiched between the grid roller 51 and the pinch roller 52, when the feed motor 53 is driven and the grid roller 51 rotates, the recording medium 11 is transported in the sub-scanning direction X.

[0025] As shown in Figure 1, an operation panel 13 is provided in front of the right front cover 71R of the main case 70. As shown in Figure 2, the operation panel 13 has a display unit that shows the status of the printer and input keys that are operated by the user. The operation panel 13 is connected to a control device 80 (see Figure 4) that controls various operations of the printer 10.

[0026] As shown in Figure 4, the control device 80 is a device that controls printing to the recording medium 11. The configuration of the control device 80 is not particularly limited. The control device 80 is, for example, a microcomputer. The hardware configuration of the microcomputer is not particularly limited, but for example, it includes an interface (I / F) for receiving print data from external devices such as a host computer, a central processing unit (CPU) for executing instructions of the control program, a read-only memory (ROM) for storing the program executed by the CPU, a random access memory (RAM) used as a working area for expanding the program, and a storage device such as memory for storing the program and various data. As shown in Figure 2, the control device 80 is located inside the right front cover 71R. However, the control device 80 does not have to be located inside the right front cover 71R. For example, the control device 80 may be a computer installed outside the right front cover 71R. In this case, the control device 80 is connected to the printer 10 so as to be able to communicate via wired or wireless connection.

[0027] As shown in Figure 4, the control device 80 is communicatively connected to the operation panel 13, the carriage motor 25 of the carriage movement mechanism 20, the ink head 40, the first light irradiation device 61, the second light irradiation device 62, and the feed motor 53 of the medium transport mechanism 50. The control device 80 controls the operation panel 13, the ink head 40, the first light irradiation device 61, the second light irradiation device 62, the carriage motor 25, and the feed motor 53. The control device 80, the first light irradiation device 61, and the second light irradiation device are connected in series using serial communication. The control device 80, the first light irradiation device 61, and the second light irradiation device are connected in series by a transmission line 60. The first light irradiation device 61 and the second light irradiation device 62 may also be connected in parallel to the control device 80. That is, the transmission line 60, which connects to the control device 80 at one point, may branch off and connect to the first light irradiation device 61 and the second light irradiation device 62, respectively.

[0028] The control device 80 controls the timing of the ink head 40 ejecting the photocurable ink, the amount of ink ejected, and other parameters. The control device 80 controls the movement of the carriage 30 in the main scanning direction Y by controlling the carriage motor 25. The control device 80 controls the movement of the recording medium 11 in the sub-scanning direction X by controlling the feed motor 53. The control device 80 controls the first light irradiation device 61 and the second light irradiation device 62. The control device 80 changes the operating state of the first light irradiation device 61 and the second light irradiation device 62 by transmitting signals to them. The change in operating state includes turning them on, turning them off, and changing the irradiation amount while they are on. In this embodiment, the irradiation amounts of the first light irradiation device 61 and the second light irradiation device 62 are kept constant. The control device 80 switches the first light irradiation device 61 on and off by transmitting a signal to the first light irradiation device 61. The control device 80 switches the second light irradiator 62 on and off by transmitting a signal to the second light irradiator 62.

[0029] As shown in Figure 4, the control device 80 includes a receiving unit 81 that receives print instructions and print data, a first acquisition unit 82 that acquires the timing for changing the operating state of the first light irradiation device 61 (hereinafter referred to as the first timing), a second acquisition unit 83 that acquires the timing for changing the operating state of the second light irradiation device 62 (hereinafter referred to as the second timing), an irradiation control unit 84 that changes the operating states of the first light irradiation device 61 and the second light irradiation device 62, and an adjustment unit 85 that adjusts the first timing or the second timing. Each of these units is implemented by a program. This program is read from a recording medium such as a CD or DVD. This program may also be downloaded via the Internet. Furthermore, each of these units may be implemented by a processor and / or circuits.

[0030] As described above, the first acquisition unit 82 acquires the timing for changing the operating state of the first light irradiation device 61. In this embodiment, the first acquisition unit 82 acquires the timing for turning the first light irradiation device 61 from OFF to ON, and the timing for turning it from ON to OFF. The timing for changing the operating state of the first light irradiation device 61 is a predetermined timing within one reciprocating movement (pass) of the carriage 30 in the main scanning direction Y. The timing for changing the operating state of the first light irradiation device 61 is indicated, for example, by the coordinate of the carriage 30 in the main scanning direction Y. The timing for changing the operating state of the first light irradiation device 61 is determined based on the print data acquired by the receiving unit 81. When the carriage 30 is at the data acquisition position during printing, the first acquisition unit 82 acquires the timing for changing the operating state of the first light irradiation device 61 in the next pass. Here, the data acquisition position is the position where the carriage 30 is located before the start of the next pass. For example, the data acquisition position is a position to the right of the platen 12.

[0031] The second acquisition unit 83 acquires the timing of changes in the operating state of the second light irradiation device 62, in the same manner as the first acquisition unit. In this embodiment, the second acquisition unit 83 acquires the timing of switching the second light irradiation device 62 from OFF to ON, and the timing of switching it from ON to OFF.

[0032] The irradiation control unit 84 controls the operating state of the first light irradiation device 61 and the second light irradiation device 62 based on the change timing acquired by the first acquisition unit 82 and the second acquisition unit 83. The irradiation control unit 84 transmits a signal (hereinafter referred to as the first signal) to the first light irradiation device 61 at the change timing acquired by the first acquisition unit 82. The irradiation control unit 84 transmits a signal (hereinafter referred to as the second signal) to the second light irradiation device 62 at the change timing acquired by the second acquisition unit 83. The first light irradiation device 61 is switched ON / OFF upon receiving the first signal. The second light irradiation device 62 is switched ON / OFF upon receiving the second signal. The irradiation control unit 84 executes control at the timing acquired by the first acquisition unit 82 and the second acquisition unit 83 so that the first light irradiation device 61 and the second light irradiation device 62 operate as desired.

[0033] The operation state of the first light irradiation device 61 and the second light irradiation device 62 may be changed by changing the ON / OFF state of all of the multiple ultraviolet irradiation LEDs 63, or by changing the ON / OFF state of some of the multiple ultraviolet irradiation LEDs 63. For example, as shown in Figure 3, suppose the first light irradiation device 61 is divided into four equal parts in the sub-scanning direction X, and light irradiation devices 61a, 61b, 61c, and 61d are lined up from the front. Each of the light irradiation devices 61a to 61d contains multiple ultraviolet irradiation LEDs 63. The irradiation control unit 84 may change the operation state for each of the light irradiation devices 61a to 61d. However, the number of divisions of the first light irradiation device 61 and the second light irradiation device 62 is not limited to four. Also, the first light irradiation device 61 and the second light irradiation device 62 may be divided in the main scanning direction Y. Furthermore, the irradiation control unit 84 may change the operation state of the ultraviolet irradiation LEDs 63 arranged in the first light irradiation device 61 and the second light irradiation device 62 on a per-ultraviolet irradiation LED basis.

[0034] The adjustment unit 85 determines whether the timing for changing the operating state of the first light irradiation device 61 (first timing) and the timing for changing the operating state of the second light irradiation device 62 (second timing) coincide. If the adjustment unit 85 determines that the first timing and the second timing coincide, it adjusts one of the first timings to shift the other. If this adjustment is made, the irradiation control unit 84 changes the operating states of the first light irradiation device 61 and the second light irradiation device 62 at the timing adjusted by the adjustment unit 85. If there is no case in which the first timing and the second timing coincide, the adjustment unit 85 does not perform any adjustment.

[0035] The configuration of printer 10 has been explained above. Next, we will explain the printing operation of printer 10.

[0036] Figures 5A to 5E are explanatory diagrams showing the movement of the carriage 30 in the forward direction (for example, to the left). In Figures 5A to 5E, the first light irradiator 61 and the second light irradiator 62 switch from an off state to an on state at the on position R1. Also, the first light irradiator 61 and the second light irradiator 62 switch from an on state to an off state at the off position R2. For example, the on position R1 and the off position R2 are indicated by coordinates in the main scanning direction Y. The on position R1 and the off position R2 are determined by the print data received by the receiving unit 81. For example, the on position R1 and the off position R2 are determined as the positions of both ends of the print data in the main scanning direction Y. Also, if the print data contains multiple images, the on position R1 and the off position R2 may be determined for each image as the positions of both ends of the image in the main scanning direction Y. The area between the illuminated position R1 and the unlit position R2 is the area where light illumination is required. Note that the illuminated position R1 and the unlit position R2 may be the positions at both ends of the platen 12 in the main scanning direction Y.

[0037] Figure 5A shows the timing when the first light irradiator 61 turns on. Figure 5B shows the timing when the second light irradiator 62 turns on. Figure 5C shows the timing when the first light irradiator 61 turns off. Figure 5D shows the timing when the second light irradiator 62 turns off. In the examples shown in Figures 5A to 5D, the timing when the operating state of the first light irradiator 61 changes does not coincide with the timing when the operating state of the second light irradiator 62 changes. The timing when the control device 80 transmits the first signal to the first light irradiator 61 does not coincide with the timing when it transmits the second signal to the second light irradiator 62. Therefore, the first signal and the second signal do not collide in the transmission line 60 (see Figure 4) that connects the control device 80, the first light irradiator 61 and the second light irradiator 62 in series. In other words, no signal collision occurs in the transmission line 60.

[0038] On the other hand, in the example shown in Figure 5E, the timing at which the first light irradiator 61 turns off coincides with the timing at which the second light irradiator 62 turns on. Figure 5E is an explanatory diagram of the case when the first timing and the second timing coincide. In the example shown in Figure 5E, the control device 80 transmits the first signal and the second signal simultaneously. Therefore, the first signal and the second signal collide in the transmission line 60. That is, a signal collision occurs in the transmission line 60. When a signal collision occurs, there is a risk that the operating states of the first light irradiator 61 and the second light irradiator 62 will not be changed properly. Therefore, if the timing at which the operating state of the first light irradiator 61 is changed and the timing at which the operating state of the second light irradiator 62 is changed coincides, the adjustment unit 85 adjusts one of them to shift the other.

[0039] Even if the timing of turning off the first light irradiator 61 and the second light irradiator 62 is delayed, the ink will cure normally and the print quality will not deteriorate. Similarly, even if the timing of turning on the first light irradiator 61 and the second light irradiator 62 is advanced, the ink will cure normally and the print quality will not deteriorate. Therefore, when adjusting the timing, it is preferable to delay the timing of turning off the lights or to advance the timing of turning them on. In the example shown in Figure 5E, the timing of turning off the first light irradiator 61 and the timing of turning on the second light irradiator 62 coincide, so the adjustment unit 85 delays the timing of turning off the first light irradiator 61. It is preferable to delay the timing to prevent signal collisions.

[0040] Figure 6 is a flowchart showing the printing procedure of the printer 10 according to this embodiment. As shown in Figure 6, the control device 80 determines whether adjustment is necessary for each pass, and if necessary, the adjustment unit 85 performs the adjustment operation.

[0041] In step S10, the user, for example, operates an operating terminal connected to the printer 10 to decide whether to print a predetermined image. As a result, a print instruction signal and print data are transmitted from the operating terminal to the receiving unit 81, and the receiving unit 81 receives the print instruction signal and print data.

[0042] In step S20, the control device 80 starts preparing to print an image onto the recording medium 11 based on the print signal and print data received by the receiving unit 81.

[0043] In step S30, the first acquisition unit 82 and the second acquisition unit 83 each acquire the timing for changing the operating state of the first light irradiation device 61 (first timing) and the timing for changing the operating state of the second light irradiation device 62 (second timing), respectively, based on the data acquired by the receiving unit 81. At this time, the control device 80 also determines the positions of the illuminated position R1 and the unilluminated position R2 of the path to be executed, as well as the amount of photocurable ink ejected by the ink head 40.

[0044] In step S40, the control device 80 compares the data acquired by the first acquisition unit 82 with the data acquired by the second acquisition unit 83 and determines whether there is a case in the pass where the operating states of the first light irradiation device 61 and the second light irradiation device 62 are changed simultaneously. If there is a case where the operating states of the first light irradiation device 61 and the second light irradiation device 62 are changed simultaneously, the process proceeds to step S50. On the other hand, if there is no case where the operating states of the first light irradiation device 61 and the second light irradiation device 62 are changed simultaneously, the process proceeds to step S60.

[0045] When the operating states of the first light irradiator 61 and the second light irradiator 62 are to be changed simultaneously, the adjustment unit 85 performs an adjustment operation in step S50. The adjustment operation is, for example, when the state is as shown in Figure 5E, an operation to delay the turning off of the first light irradiator 61 by a predetermined timing. The predetermined timing may be predetermined or may be set as appropriate by the user. The predetermined timing may be, for example, equal to the time lag from when the control device 80 sends a signal to the first light irradiator 61 until the first light irradiator 61 actually turns off. Alternatively, the predetermined timing may be set by distance, not just time. For example, the predetermined timing may be set by the distance obtained by the product of the time from when the control device 80 sends a signal to the first light irradiator 61 until the first light irradiator 61 turns off, and the speed at which the carriage 30 moves in the main scanning direction Y. That is, the turning-off position R2 of the first light irradiator 61 may be shifted to the left by the above distance.

[0046] In step S60, the control device 80 executes a pass while controlling the ink head 40, the first light irradiation device 61, and the second light irradiation device 62 based on the adjusted timing. The ink head 40 ejects photocurable ink, and the first light irradiation device 61 and the second light irradiation device 62 irradiate light based on the adjusted timing.

[0047] In step S70, the control device 80 determines whether the image printing is complete based on the print data acquired by the receiving unit 81. If it determines that the image printing is complete, it terminates printing. If it determines that the image printing is not complete, it returns to step S30 to determine the control for the next pass.

[0048] As described above, with the printer 10 of this embodiment, when the operating states of the first light irradiator 61 and the second light irradiator 62 are to be changed simultaneously, the adjustment unit 85 can delay the turning off of the first light irradiator 61 by a predetermined timing, thereby avoiding a collision between the first signal and the second signal. This prevents malfunctions of the first light irradiator 61 and the second light irradiator 62, and thus prevents a decrease in the quality of printed materials.

[0049] According to this embodiment, the printer 10 has a first light irradiation device 61 to the left of the ink head 40 and a second light irradiation device 62 to the right of the ink head 40. After the ink head 40 ejects the photocurable ink, the ejected photocurable ink is cured by irradiating it with light from the first light irradiation device 61 and the second light irradiation device 62. When the ink head 40 ejects the photocurable ink while moving to the left, the photocurable ink can be immediately cured by the second light irradiation device 62 on the right. Also, when the ink head 40 ejects the photocurable ink while moving to the right, the photocurable ink can be immediately cured by the first light irradiation device 61 on the left. The printer 10 can immediately cure the photocurable ink in both the forward and return strokes. Furthermore, when the ink head 40 moves to the left or to the right, the amount of irradiation to the photocurable ink can be increased by irradiating it with light from both the first light irradiation device 61 and the second light irradiation device 62. This allows printer 10 to perform printing efficiently.

[0050] In this embodiment, the first light irradiation device 61 and the second light irradiation device 62 turn on when they reach the on position R1 and turn off when they reach the off position R2. When the light irradiated from the first light irradiation device 61 and the second light irradiation device 62 is reflected off the recording medium 11, the reflected light is irradiated onto the ink head 40. This can cause the photocurable ink adhering to the nozzles 41 and 42 to harden, potentially leading to clogging of the nozzles 41 and 42. Therefore, it is desirable that the time for which the first light irradiation device 61 and the second light irradiation device 62 irradiate light is as short as possible. By setting the on position R1 and the off position R2 as the ends of the range where light irradiation is required, the on time of the first light irradiation device 61 and the second light irradiation device 62 can be shortened. This makes it possible to suppress the hardening of the photocurable ink adhering to the nozzles 41 and 42.

[0051] If the ink is not cured sufficiently, the quality of the printed material will deteriorate. In areas where light irradiation is required, the first light irradiation device 61 and the second light irradiation device 62 must be turned on. If the turning on is delayed, the first light irradiation device 61 and the second light irradiation device 62 will not be able to irradiate the required area with the required amount of light. On the other hand, even if the turning off is slightly delayed, it is still possible to irradiate the required area with the required amount of light. According to this embodiment, if the adjustment unit 85 determines that the timing of the first light irradiation device 61 turning off and the timing of the second light irradiation device 62 turning on coincide, it delays the timing of turning off the first light irradiation device 61 by a predetermined time. Therefore, it is possible to avoid signal collisions without reducing the amount of light irradiated to the area that needs irradiation, and to prevent malfunctions of the first light irradiation device 61 and the second light irradiation device 62. Thus, a deterioration in the quality of the printed material can be avoided.

[0052] According to this embodiment, the adjustment unit 85 delays the timing of the first light irradiation device 61 turning off by shifting the off position of the first light irradiation device 61 by a predetermined distance. The predetermined distance is determined by the product of the time from when the control device 80 issues a signal to the first light irradiation device 61 to turn off until the first light irradiation device 61 turns off, and the speed at which the carriage 30 moves in the main scanning direction Y. According to this embodiment, the delay in turning off the first light irradiation device 61 can be minimized. The occurrence of clogging of the nozzles 41 and 42 due to adjustment operations can be minimized.

[0053] A preferred embodiment of the present invention has been described above. However, the above-described embodiment is merely illustrative, and the present invention can be implemented in various other forms.

[0054] In this embodiment, the printer 10 has a first light irradiator 61 and a second light irradiator 62, one on each side of the ink head 40, but is not limited to this. For example, two light irradiators may be located on either the left or right side of the ink head 40. Also, the number of light irradiators is not limited to two. The printer 10 may have three or more light irradiators.

[0055] In this embodiment, the printer 10 delays the off-time of the first light irradiator 61 when the off-time of the first light irradiator 61 coincides with the on-time of the second light irradiator 62, but is not limited to this. As shown in Figure 7, the on-time of the second light irradiator 62 may be advanced when the off-time of the first light irradiator 61 coincides with the on-time of the second light irradiator 62. In this case as well, signal collisions can be avoided and the same effects as in the above embodiment can be obtained. In this case, by setting the predetermined timing adjusted by the adjustment unit 85 to the product of the time from when the control device 80 issues a signal to the second light irradiator 62 to turn on until the second light irradiator 62 turns on, and the movement speed when the carriage 30 moves in the main scanning direction Y, the amount of deviation in the illuminated position of the second light irradiator 62 is minimized. By minimizing the amount of deviation in the illuminated position, the time during which the second light irradiator 62 is illuminated can be shortened, and the occurrence of clogging of the nozzles 41 and 42 due to adjustment operations can be minimized.

[0056] In this embodiment, the printer 10 determines the timing for changing the operating state of the first light irradiator 61 and the second light irradiator 62 based on the coordinate of the main scanning direction Y, but is not limited to this. For example, the timing for changing the operating state can also be determined based on the elapsed time since the start of the pass. In this case, the adjustment unit 85 can shift the timing by, for example, the amount of time from when the control device 80 sends a signal to the first light irradiator 61 and the second light irradiator 62 until the first light irradiator 61 and the second light irradiator 62 turn off or turn on, thereby shifting the timing by the minimum amount of time within the range where signal collisions do not occur. By minimizing the shift time by the adjustment unit 85, the time that the first light irradiator 61 and the second light irradiator 62 are lit is shortened, and the occurrence of nozzle clogging due to adjustment operations can be minimized.

[0057] The operating states of the first light irradiator 61 and the second light irradiator 62 of the printer 10 in this embodiment are limited to two states: on and off. The operating states of the first light irradiator 61 and the second light irradiator 62 may, for example, be the amount of light emitted by the first light irradiator 61 and the second light irradiator 62, as shown in Figure 8. Figures 8(a) and (b) are graphs in which the horizontal axis represents time [ms] from the start of the pass and the vertical axis represents the amount of light emitted by the light irradiator [%], and are examples of control by the control device 80. Figure 8(a) shows the relationship between time and the amount of light emitted in the first light irradiator 61, and Figure 8(b) shows the relationship between time and the amount of light emitted in the second light irradiator 62. Assume that at time t [ms], it is necessary to reduce the amount of light emitted by the first light irradiator 61 from L1 [%] to L2 [%]. Furthermore, let's assume that at time t [ms], it is necessary to increase the irradiation amount of the second light irradiation device 62 from L2 [%] to L1 [%]. At this time, the irradiation amounts of the first light irradiation device 61 and the second light irradiation device 62 will be changed simultaneously. Therefore, as shown in Figure 8(a), the adjustment unit 85 performs an operation to shift the time at which the irradiation amount of the first light irradiation device 61 is changed by Δt. As a result, no signal collision occurs in the transmission line 60. Note that when changing the irradiation amount of light of the first light irradiation device 61 and the second light irradiation device 62, for example, the irradiation amount of light may be changed for each light irradiation device 61a to 61d as shown in Figure 3.

[0058] Furthermore, it is conceivable that the first light irradiator 61 and the second light irradiator 62 may be turned on or have their irradiation levels increased simultaneously, or that the first light irradiator 61 and the second light irradiator 62 may be turned off or have their irradiation levels decreased simultaneously. When the first light irradiator 61 and the second light irradiator 62 are turned on or have their irradiation levels increased simultaneously, the adjustment can be performed without reducing the amount of irradiation to the area that needs to be irradiated by performing an adjustment operation to advance the timing of turning on or increasing the irradiation level of either the first light irradiator 61 or the second light irradiator 62. When the first light irradiator 61 and the second light irradiator 62 are turned off or have their irradiation levels decreased simultaneously, the adjustment can be performed without reducing the amount of irradiation to the area that needs to be irradiated by performing an adjustment operation to delay the timing of turning off or reducing the irradiation level of either the first light irradiator 61 or the second light irradiator 62.

[0059] In this embodiment, the first light irradiation device 61 and the second light irradiation device 62 are arranged on the left and right sides of the carriage 30, respectively. However, the arrangement of the first light irradiation device 61 and the second light irradiation device 62 is not limited to this. For example, as shown in Figure 9, a third light irradiation device 64 equipped with multiple ultraviolet irradiation LEDs 63 is provided on the right side of the carriage 30. The third light irradiation device 64 is divided into a front region and a rear region. Of the two divided regions, the front region may be designated as the first light irradiation device 61 and the rear region as the second light irradiation device 62.

[0060] The technology disclosed herein can be applied to various types of printers. In addition to the Roll-to-Roll type printer 10 shown in the embodiments described above, it can also be applied to a so-called flatbed type printer 10, for example, in which a recording medium is placed on a table and the table is transported in the sub-scanning direction X to print. Furthermore, it can also be applied to a so-called gantry type printer 10, in which a recording medium is placed on a table and a carriage 30 is moved relative to the table in the main scanning direction Y and the sub-scanning direction X to print. [Explanation of Symbols]

[0061] 10 Printers 11 Recording media 12 Platen 20. Carriage movement mechanism 40 Inkheads 60 transmission lines 61 First light irradiation device 62 Second light irradiation device 80 Control device 82 First acquisition part 83 Second acquisition part 84 Irradiation control unit 85 Adjustment part

Claims

1. A platen on which the recording medium is placed, The recording medium placed on the platen is provided with an ink head that ejects photocurable ink, A moving mechanism that moves the ink head back and forth in the main scanning direction relative to the recording medium placed on the platen, A first light irradiation device and a second light irradiation device that irradiate light toward the photocurable ink ejected onto the recording medium, A control device that controls the ink head, the first light irradiation device, and the second light irradiation device, The system comprises a transmission path that connects to the control device at a single point and connects the control device, the first light irradiation device, and the second light irradiation device in series or in parallel, The control device is An irradiation control unit that changes the operating state of the first light irradiation device and the second light irradiation device, A first acquisition unit acquires a first timing which is the timing at which the operating state of the first light irradiation device is changed, A second acquisition unit acquires a second timing, which is the timing at which the operating state of the second light irradiation device is changed. An inkjet printer having an adjustment unit that determines whether the first timing and the second timing coincide, and if it is determined that the first timing and the second timing coincide, shifts either the first timing or the second timing relative to the other.

2. Changing the operating state of the first light irradiation device is done by turning the first light irradiation device on or off. The inkjet printer according to claim 1, wherein changing the operating state of the second light irradiation device is to turn on or turn off the second light irradiation device.

3. The first timing is the timing at which the first light irradiation device is turned off. The second timing is the timing for turning on the second light irradiation device. The inkjet printer according to claim 2, wherein the adjustment unit delays the first timing by a predetermined time when it determines that the first timing and the second timing coincide.

4. The first timing is the timing at which the first light irradiation device is turned off. The second timing is the timing for turning on the second light irradiation device. The inkjet printer according to claim 2, wherein the adjustment unit advances the second timing by a predetermined time when it determines that the first timing and the second timing coincide.

5. The first light irradiation device is positioned on one side of the main scanning direction relative to the ink head, The second light irradiation device is positioned on the other side of the main scanning direction relative to the ink head, The inkjet printer according to claim 1, wherein the moving mechanism moves the ink head, the first light irradiation device, and the second light irradiation device back and forth relative to the recording medium placed on the platen in the main scanning direction.

6. The control device is configured such that, when the first light irradiator and the second light irradiator move in one of the main scanning directions, the first light irradiator is turned off when it reaches a predetermined off position, and the second light irradiator is turned on when it reaches a predetermined on position. The inkjet printer according to claim 5, wherein the adjustment unit delays the first timing by shifting the off position of the first light irradiation device by a predetermined distance to one side of the main scanning direction when it determines that the first timing and the second timing coincide.

7. The control device is configured such that, when the first light irradiator and the second light irradiator move in one of the main scanning directions, the first light irradiator is turned off when it reaches a predetermined off position, and the second light irradiator is turned on when it reaches a predetermined on position. The inkjet printer according to claim 5, wherein the adjustment unit advances the second timing by shifting the illumination position of the second light irradiation device by a predetermined distance to the other side of the main scanning direction when it determines that the first timing and the second timing coincide.

8. The inkjet printer according to claim 3, wherein the predetermined time is the time from when the control device issues a signal to turn off the first light irradiator until the first light irradiator turns off.

9. The inkjet printer according to claim 4, wherein the predetermined time is the time from when the control device issues a signal to light up the second light irradiating device until the second light irradiating device is lit.

10. The inkjet printer according to claim 6, wherein the predetermined distance is the product of the time from when the control device issues a signal to turn off the first light irradiator until the first light irradiator turns off, and the speed at which the first light irradiator moves in the main scanning direction.

11. The inkjet printer according to claim 7, wherein the predetermined distance is the product of the time from when the control device issues a signal to light up the second light irradiator until the second light irradiator lights up, and the speed at which the second light irradiator moves in the main scanning direction.

12. Changing the operating state of the first light irradiation device involves increasing or decreasing the irradiation dose of the first light irradiation device. The inkjet printer according to claim 1, wherein changing the operating state of the second light irradiation device is to increase or decrease the irradiation amount of the second light irradiation device.

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