Printer, printing method, and detection method

Abstract

To appropriately irradiate ultraviolet rays to a medium.SOLUTION: A printer 10 uses ultraviolet curable ink to perform printing of a three-dimensional medium 50 held by a holding tool 40 to be a holding member and includes an ink jet head 102, a sub-scanning driving part 18, and a control part 30. The holding tool 40 is provided with a rotating mechanism, an ultraviolet-light irradiator, and a cover. The control part 30 causes the ink jet head 102 to perform main scanning operation by causing the ink jet head to discharge ink to the ink jet head 102 while causing the rotating mechanism to rotate the medium 50, and causes the ink jet head to perform sub-scanning operation within a range that a position of the nozzle array in the sub-scanning direction is not put outside an opposite medium range when a range from one end to the other end of the medium 50 in a sub-scanning direction at a position opposite the nozzle array is defined as the opposite position medium range.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a printing device, a printing method, and a detection method. [Background technology]

[0002] Conventionally, there is known a printing device that performs printing on the outer surface of a cylindrical body by an inkjet method (see, for example, Patent Document 1). The printing device disclosed in Patent Document 1 mounts a cylindrical body that does not absorb ink on a mandrel that is rotatable about a central axis and is movable in the axial direction and in a direction perpendicular to the axial direction, and then sprays ultraviolet-curable ink of each color from each inkjet head of an inkjet head group composed of a plurality of nozzles that spray ink of each color onto the outer surface of the cylindrical body to perform a desired decorative print, irradiates the decorative print with ultraviolet light, and then irradiates the decorative print with ultraviolet light to cure it. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-143200 A Summary of the Invention [Problem to be solved by the invention]

[0004] When printing is performed by the inkjet method using ultraviolet curable ink, if ultraviolet light irradiated to harden the ink hits the inkjet head, the ink hardens at the nozzle position of the inkjet head, which may cause the nozzle to become clogged. In addition, when printing is performed while rotating a medium (media, work) to be printed, for example, it is considered that ultraviolet light is irradiated onto the side of the medium at a position (position where the medium has rotated) that is located in the rotation direction from the ink landing position. In this case, it is considered that, for example, ultraviolet light leaking from the periphery of the medium is likely to reach the inkjet head. Therefore, when printing is performed in such a configuration, it is desirable to more appropriately irradiate the medium with ultraviolet light. Therefore, an object of the present invention is to provide a printing device, a printing method, and a detection method that can solve the above problems. [Means for solving the problem]

[0005] The inventors of the present application have conducted extensive research into a configuration for printing a three-dimensional medium by an inkjet method while rotating the medium and irradiating the outer surface of the medium with ultraviolet light. They then came up with the idea of ​​installing a cover between an ultraviolet irradiator that irradiates ultraviolet light and an inkjet head to cover at least the ultraviolet irradiator. With this configuration, for example, it is possible to appropriately realize a configuration in which ultraviolet light is less likely to hit the inkjet head. When using such a cover, for example, a cover having an opening that matches the shape of the medium can be used. However, even in this case, for example, a gap may be generated between the end of the medium in the axial direction of rotation and the cover, and ultraviolet light may leak from the gap. When printing on the outer surface of the medium, for example, the inkjet head is made to perform a main scanning operation (scan) and a sub-scanning operation (feed) to cause the inkjet head to eject ink to each position on the outer surface. In this case, the sub-scanning operation can be considered to be, for example, an operation of moving relative to the medium in a predetermined sub-scanning direction. In this case, for example, when printing is performed over a wide area on the outer surface of the medium, it is considered that the inkjet head will pass through the position of the gap between the cover and the medium during one of the sub-scanning operations. As a result, ultraviolet light leaking through the gaps may hit the inkjet head, causing the ink to harden near the nozzles, resulting in clogging of the nozzles.

[0006] In response to this, the inventors of the present application came up with a configuration in which the relative movement of the inkjet head during at least some of the sub-scanning operations is made different from that of a general sub-scanning operation, so that the inkjet head does not pass through the gap between the cover and the medium. With this configuration, for example, it is possible to appropriately prevent ultraviolet rays from hitting the inkjet head at the gap between the cover and the medium. This also makes it possible, for example, to make it less likely for the nozzles in the inkjet head to become clogged.

[0007] Furthermore, the inventors of the present application have conducted further intensive research and have found the characteristics necessary to obtain such effects, which led to the present invention. In order to solve the above problems, the present invention provides a printing device that uses ultraviolet curable ink to print on a three-dimensional medium held by a holding member that holds a medium to be printed on, the printing device comprising: an inkjet head having a nozzle row in which a plurality of nozzles are arranged at different positions in a predetermined nozzle row direction; a sub-scanning drive unit that causes the inkjet head to perform a sub-scanning operation to move the inkjet head relatively to the medium in a sub-scanning direction parallel to the nozzle row direction; and a control unit that controls the operation of the inkjet head and the sub-scanning drive unit, the holding member comprising a rotation mechanism that rotates the medium while holding the medium at a position facing the nozzle row, an ultraviolet irradiator that irradiates ultraviolet rays onto an outer surface of the medium, and a cover that is a member that covers at least the ultraviolet irradiator from the side of an upper surface of the holding member that is the surface facing the inkjet head, the cover having an opening at a position facing the nozzle row and covering the upper surface of the holding member while opposing the nozzle row to the medium at the position of the opening, the rotation mechanism being configured to rotate the medium while holding the medium at a position facing the nozzle row, the control unit further controls a rotation operation of the rotation mechanism to rotate the medium, and causes the inkjet head to eject ink while rotating the medium, thereby causing the inkjet head to perform a main scanning operation of ejecting ink onto the rotating medium, and causes the inkjet head to perform the sub-scanning operation between at least some of the main scanning operations while performing the main scanning operation a plurality of times, thereby causing the inkjet head to eject ink onto a printing range that is wider in the sub-scanning direction than a nozzle array length, which is the length of the nozzle array in the sub-scanning direction, and when a range from one end to the other end of the medium in the sub-scanning direction at a position opposite the nozzle array is defined as an opposing position medium range, the control unit causes the inkjet head to perform the sub-scanning operation within a range that does not cause the position of the nozzle array in the sub-scanning direction to go outside the opposing position medium range.

[0008] In this configuration, for example, during the sub-scanning operation, the inkjet head can be appropriately prevented from passing through the gap between the cover and the medium. Therefore, with this configuration, for example, ultraviolet light can be appropriately prevented from hitting the inkjet head at the gap between the cover and the medium. This also makes it difficult for nozzles in the inkjet head to become clogged. In this configuration, for example, the control unit causes the inkjet head to perform all main scanning operations while the position of the nozzle row in the sub-scanning direction is within the opposing position medium range. In this case, the control unit also causes the inkjet head to perform sub-scanning operations between at least some of the main scanning operations, so that the inkjet head can print on the entire side surface of the medium at most.

[0009] In addition, in this configuration, the ultraviolet irradiator irradiates the medium with ultraviolet light from, for example, a position farther from the inkjet head than the position on the medium closest to the inkjet head (the top of the medium). With this configuration, for example, the ultraviolet irradiator can be easily and appropriately covered with a cover. More specifically, the ultraviolet irradiator irradiates ultraviolet light toward, for example, a position downstream in the rotation direction of the medium from the landing position where the ink lands on the medium, and at a rotation angle of 90 degrees to 180 degrees from the landing position in the rotation direction. With this configuration, for example, ultraviolet light can be appropriately irradiated onto the ink that has landed on the medium.

[0010] Also, in this configuration, the printing device performs printing in a multi-pass method in which the number of main scanning operations performed in a state where one position of the medium faces the nozzle row is multiple. In this case, the control unit causes the inkjet head to perform main scanning operations a number of times corresponding to a preset number of passes, for example, in a state where one end (front end) of the medium in the sub-scanning direction at a position facing the nozzle row is aligned with one end (front end) of the nozzle row in the sub-scanning direction. Then, the control unit causes the inkjet head to perform a sub-scanning operation in which the inkjet head moves in the sub-scanning direction relative to the medium by a distance corresponding to the number of passes, which is a moving distance corresponding to the distance obtained by dividing the length of the nozzle row by the number of passes, before causing the inkjet head to perform the next main scanning operation. With this configuration, for example, the main scanning operation for the number of passes performed first can be appropriately performed without performing a sub-scanning operation in which the inkjet head passes through the position of the gap between the cover and the medium on the side of one end of the medium. Also, this makes it possible to more appropriately prevent ultraviolet rays from hitting the inkjet head at the position of the gap between the cover and the medium, for example. Such an operation can be considered to be, for example, a configuration in which the first main scanning operation (main scanning operation for the first scan) is started in a state in which one end of the medium and one end of the inkjet head are aligned. Also, the pass number corresponding distance can be considered, for example, as a standard movement amount (feed amount) in a sub-scanning operation.

[0011] In this case, for example, it is also possible to perform a sub-scanning operation at a distance shorter than the distance corresponding to the number of passes while performing a main scanning operation for the first number of passes. More specifically, in the printing device, for example, it is possible to make the printing resolution in the sub-scanning direction higher than the resolution corresponding to the nozzle pitch in the nozzle row. In this case, the nozzle pitch can be considered to be, for example, the interval between the nozzles in the nozzle row in the sub-scanning direction. In this case, for example, by performing printing using a multi-pass method, it is possible to perform printing on the medium with the printing resolution in the sub-scanning direction higher than the resolution corresponding to the nozzle pitch. In this case, for example, during at least a part of the interval between the main scanning operations the number of times corresponding to the number of passes performed with one end of the medium and one end of the nozzle row aligned, the sub-scanning drive unit moves the inkjet head in the sub-scanning direction relative to the medium by a distance less than the nozzle pitch. With this configuration, for example, it is possible to appropriately prevent ultraviolet rays from hitting the inkjet head at the position of the gap between the cover and the medium, while appropriately printing at a high resolution.

[0012] In addition, in this configuration, the control unit causes the inkjet head to perform a main scan operation and a sub-scan operation so that the inkjet head does not pass through the position of the gap between the cover and the medium, even on the other end (rear end) side of the medium and the inkjet head. More specifically, in a sub-scan operation in which the position of the other end of the nozzle row exceeds the position of the other end of the medium in the sub-scanning direction at the position facing the nozzle row when the moving distance of the inkjet head relative to the medium is set to the pass number corresponding distance, the control unit causes the inkjet head to perform a sub-scan operation so that the inkjet head is moved relative to the medium by the moving distance until the other end of the nozzle row reaches the position of the other end of the medium. With this configuration, for example, it is possible to appropriately prevent the sub-scan operation from being performed beyond the edge of the medium on the other end side of the medium. Also, this makes it possible to more appropriately prevent the inkjet head from being exposed to ultraviolet light at the position of the gap between the cover and the medium, for example. In this case, the control unit, for example, causes the inkjet head to perform a sub-scanning operation in which the other end of the nozzle row reaches the position of the other end of the medium in the sub-scanning direction, and then causes the inkjet head to perform multiple main scanning operations while the other end of the medium and the other end of the nozzle row are aligned. With this configuration, for example, the required number of main scanning operations can be appropriately performed for a range including the other end of the medium. In this case, the control unit, for example, causes the inkjet head to perform main scanning operations for the number of passes while the other end of the medium and the other end of the nozzle row are aligned. The state in which the other end of the medium and the other end of the nozzle row are aligned may be, for example, a state in which the distance between the other end of the medium and the other end of the nozzle row is equal to or less than the nozzle pitch. In this case, the control unit, for example, may cause the inkjet head to perform a sub-scanning operation in which the inkjet head moves relatively a distance less than the nozzle pitch between multiple main scanning operations performed in this state.

[0013] In addition, in controlling the printing operation, it is also possible to treat the printing range (print target area) on the medium where printing is performed as the range of the medium. In this case, for example, one end (front end) of the medium can be considered as a position corresponding to one end of the printing range in the sub-scanning direction. Also, the other end (rear end) of the medium can be considered as a position corresponding to the other end of the printing range in the sub-scanning direction. In this case, the alignment of one end of the medium with one end of the nozzle row can be considered to correspond to, for example, the alignment of a position corresponding to one end of the print data in the sub-scanning direction with the position of one end of the nozzle row in the sub-scanning direction. Also, the alignment of the other end of the medium with the other end of the nozzle row can be considered to correspond to, for example, the alignment of a position corresponding to the other end of the print data in the sub-scanning direction with the position of the other end of the nozzle row in the sub-scanning direction.

[0014] In addition, in this configuration, for example, if a gap occurs between the cover and the medium due to misalignment of the cover, ultraviolet light may leak unintentionally and hit the inkjet head. For this reason, it is preferable to check whether the cover is properly covering the ultraviolet irradiator in a predetermined state. In this case, for example, a sensor may be used to detect the state of the gap. More specifically, in this case, the printing device further includes a sensor used to detect the position of the upper surface of the holding member, and a sensor moving means for moving the sensor relative to the holding member. In addition, the holding member further includes a cover moving means for moving the cover in a direction in which the distance between the inkjet head and the cover changes. Then, the control unit further controls, for example, the sensor and the sensor moving means, and detects the state of the gap between the cover and the medium based on the output of the sensor acquired while moving the sensor by the sensor moving means along a path passing through the edge of the opening of the cover. With this configuration, for example, the state of the gap between the cover and the medium can be detected. In addition, for example, it is possible to appropriately prevent unintentional leakage of ultraviolet light due to misalignment of the cover. In this case, the control unit moves the sensor along multiple paths in a direction intersecting the nozzle row direction, for example. The multiple paths include, for example, a one-end path that passes near one end of the medium at a position facing the nozzle row, an other-end path that passes near the other end of the medium at a position facing the nozzle row, and an intermediate position path that passes over the medium between the one-end path and the other-end path. With this configuration, for example, the state of the gap between the cover and the medium can be more appropriately detected.

[0015] As the sensor, for example, a photosensor that detects light can be suitably used. In this case, for example, a light-reflective member can be attached to at least a part of at least one of the medium and the cover. In this case, the control unit moves the sensor along a path along which the sensor detects reflected light from the position where the light-reflective member is attached on at least one of the medium and the cover. In addition, the control unit detects reflected light from the cover and the medium by the sensor. With this configuration, for example, the state of the gap between the cover and the medium can be more appropriately detected. For the light-reflective member, for example, a tape of a light-reflective color such as white can be suitably used. In addition, when a photosensor is used as the sensor, the sensor can also be used for the purpose of directly detecting ultraviolet light leaking from the gap. In this case, for example, in a state where ultraviolet light is irradiated onto the outer surface of the medium by an ultraviolet irradiator, the control unit further detects ultraviolet light leaking from the gap between the edge of the opening of the cover and the medium based on the output of the sensor. With this configuration, for example, when an unintended leakage of ultraviolet light occurs due to a positional deviation of the cover, etc., the leakage of ultraviolet light can be more appropriately detected. Furthermore, as a configuration of the present invention, for example, it is also possible to use a printing method or the like having the same characteristics as those described above. In this case, for example, the same effects as those described above can also be obtained.

[0016] The features of the present invention can also be considered by focusing on a configuration using such a sensor. In this case, the present invention is, for example, a printing device that uses ultraviolet curable ink to print on a three-dimensional medium held by a holding member that holds a medium to be printed, and includes an inkjet head having a nozzle row in which a plurality of nozzles are arranged at different positions in a predetermined nozzle row direction, a sensor used to detect the position of an upper surface of the holding member, which is the surface of the holding member that faces the inkjet head, a sensor moving means for moving the sensor relatively to the holding member, and a control unit for controlling the operations of the inkjet head, the sensor, and the sensor moving means, and the holding member moves the medium while holding the medium at a position facing the nozzle row. the inkjet head and the cover are provided with a rotation mechanism which rotates the inkjet head, an ultraviolet irradiator which irradiates ultraviolet light onto the outer surface of the medium, a cover which is a member covering at least the ultraviolet irradiator from the side of the top surface of the holding member, the cover having an opening facing the nozzle row and covering the top surface of the holding member while facing the nozzle row and the medium at the position of the opening, and a cover moving means which moves the cover in a direction which changes the distance between the inkjet head and the cover, and the control unit detects the state of the gap between the cover and the medium based on the output of the sensor obtained while moving the sensor by the sensor moving means along a path which passes through the edge of the opening of the cover.

[0017] When configured in this manner, for example, the state of the gap between the cover and the medium can be appropriately detected. This also makes it possible to appropriately prevent, for example, unintended leakage of ultraviolet light due to misalignment of the cover. Therefore, with this configuration, for example, ultraviolet light can be more appropriately irradiated onto the medium. It is also possible to use a detection method having the same characteristics as described above as a configuration of the present invention. In this case, for example, the same effects as described above can be obtained. Effect of the Invention

[0018] According to the present invention, for example, it is possible to more appropriately irradiate a medium with ultraviolet light. [Brief description of the drawings]

[0019] [Figure 1] 1A is a diagram illustrating a printing device 10 according to an embodiment of the present invention. Fig. 1A shows an example of the configuration of the main part of the printing device 10. Fig. 1B shows an example of the configuration of a head unit 12. [Diagram 2] 2A and 2B are a cross-sectional view and a top view showing an example of the configuration of the holding jig 40 in a simplified manner. [Diagram 3] 3A is a diagram showing an example of the configuration of the holding jig 40. Fig. 3(a) is a cross-sectional view showing an example of a more specific configuration of the holding jig 40. Fig. 3(b) is a perspective view showing an example of the configuration of the ultraviolet irradiator 208 in the holding jig 40. [Figure 4] 13 is a diagram illustrating a magnet sheet 224 in the holding jig 40. FIG. [Diagram 5] 1A to 1C are diagrams illustrating an example of a main scanning operation and a sub-scanning operation that are the same as or similar to a conventional method. [Figure 6] 5A to 5C are diagrams illustrating an example of a main scanning operation and a sub-scanning operation in this example. [Figure 7] 7A and 7B are diagrams showing other examples of main scanning and sub-scanning operations in this example. Fig. 7A shows an example of the position of the inkjet head 102 during the Nth and (N+1)th main scanning operations performed on a medium 50 of a predetermined size. Fig. 7B shows an example of the position of the inkjet head 102 during the (N-1)th and Nth main scanning operations performed on a medium 50 of a predetermined size different from that shown in Fig. 7A. [Figure 8] 11A to 11C are diagrams illustrating an example of an operation for detecting the state of a gap using the sensor 20. [Figure 9] 10 is a flowchart showing an example of an operation for detecting a gap state in the printing device 10. [Figure 10]10A and 10B are diagrams illustrating a method of printing on the side surfaces of a medium 50. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a diagram illustrating a printing device 10 according to an embodiment of the present invention. Fig. 1(a) shows an example of the configuration of the main parts of the printing device 10. Except for the points described below, the printing device 10 and each part of the printing device 10 may have the same or similar features as a known printing device and each part thereof.

[0021] In this example, the printing device 10 is an inkjet printer that performs printing on a three-dimensional medium 50 held by a holding jig 40 using ultraviolet curable ink (UV ink). The ultraviolet curable ink can be considered to be, for example, ink that is fixed to the medium 50 by being cured by irradiation with ultraviolet rays. The medium 50 can be considered to be, for example, a workpiece that is a target of printing processing in the printing device 10. In this example, the holding jig 40 is an example of a holding member that holds the medium 50, and holds the medium 50 rotatably around a predetermined rotation axis at a position facing the inkjet head 102, and rotates the medium 50 according to the control of the printing device 10. In this case, the position facing the inkjet head 102 can be considered to be, for example, a position facing the nozzle row of the inkjet head 102. Holding the medium 50 at a position facing the inkjet head 102 can be considered to be, for example, holding the medium 50 at a position facing the inkjet head 102 when ink is discharged from the inkjet head 102 to the medium 50. In this embodiment, the holding jig 40 is equipped with an ultraviolet irradiator and irradiates ultraviolet light onto the outer surface of the medium 50. The configuration of the holding jig 40 will be described in more detail later.

[0022] In this example, the printing device 10 includes a head unit 12, a base unit 14, a main scanning drive unit 16, a sub-scanning drive unit 18, a sensor 20, a sensor moving means 22, and a control unit 30. The head unit 12 has an inkjet head that ejects ink onto a medium 50. The configuration of the head unit 12 will be described in more detail later. The base unit 14 is a table-like member that holds a holding jig 40 at a position facing the head unit 12. In this example, the base unit 14 holds the holding jig 40 so that the medium 50 held by the holding jig 40 and the inkjet head in the head unit 12 face each other by placing the holding jig 40 on the upper surface. The main scanning drive unit 16 is a drive unit that causes the inkjet head in the head unit 12 to perform a main scanning operation. The main scanning operation can be considered to be, for example, an operation of ejecting ink while moving relatively to the medium 50 in a preset main scanning direction (Y direction in the figure). In this example, the main scanning driver 16 rotates the medium 50 on the holding jig 40 in response to control from the controller 30, thereby moving the inkjet head relative to a position on the medium 50 that faces the nozzle row. In this case, the inkjet head can be considered to move in the main scanning direction relative to a position on the medium 50 where ink is ejected, for example, as the medium 50 rotates. In this case, the main scanning operation in this example can also be considered to be, for example, an operation of ejecting ink onto the rotating medium. The main scanning operation can also be considered to be, for example, an operation of ejecting ink onto the medium 50 while fixing the position of the inkjet head relative to the medium 50 in the sub-scanning direction.

[0023] The sub-scanning driver 18 is a driver that causes the inkjet head in the head unit 12 to perform a sub-scanning operation. The sub-scanning operation can be considered, for example, as an operation of moving relatively to the medium 50 in a sub-scanning direction (X direction in the figure) perpendicular to the main scanning direction. The sub-scanning operation can also be considered, for example, as a feed operation that changes the range of the medium facing the inkjet head by relative movement in the sub-scanning direction. In this example, the main scanning direction is an example of a predetermined first direction. The sub-scanning direction is an example of a second direction perpendicular to the first direction. The main scanning operation is an example of a first scan that ejects ink while moving in the first direction relative to each position on the medium 50. The sub-scanning operation is an example of a second scan that moves relatively to the medium 50 in the second direction.

[0024] The sensor 20 is a detection means used to detect the state of the holding jig 40. In this example, the sensor 20 is a photosensor that detects light such as ultraviolet light, and detects, for example, ultraviolet light leaking from an opening of the holding jig 40. With this configuration, for example, it is possible to properly detect whether the medium 50 or the like is properly installed on the holding jig 40. More specifically, in this case, for example, it is possible to detect the misalignment of the cover or the medium 50 by detecting the leakage of ultraviolet light caused by the misalignment of the cover or the medium 50 in the holding jig 40 using the sensor 20. In addition, it is also possible to detect, for example, the state of the gap generated between the cover of the holding jig 40 and the medium 50 based on the detection result of the sensor 20. The sensor moving means 22 is a means for moving the sensor 20 relative to the holding jig 40, and moves the sensor 20 to match the location where the sensor 20 performs detection. The control unit 30 is a part including, for example, a CPU of the printing device 10, and controls the operation of each part of the printing device 10 in accordance with a program such as firmware (FW) of the printing device 10.

[0025] Next, the configuration of the head unit 12 will be described in more detail. FIG. 1(b) shows an example of the configuration of the head unit 12. In this example, the head unit 12 has a plurality of inkjet heads 102 that eject ultraviolet curable ink. More specifically, in this example, the head unit 12 has four inkjet heads 102, as shown in the figure with reference numerals 102a to d for distinction. Among them, the inkjet heads 102a to c are aligned in the main scanning direction with their positions in the sub-scanning direction being the same. In addition, the inkjet head 102d is arranged with its position in the sub-scanning direction shifted from the inkjet heads 102a to c. In this case, regarding the configuration of the head unit 12, for example, it can be considered that at least some of the inkjet heads 102 in the head unit 12 are aligned in the main scanning direction with their positions in the sub-scanning direction being the same. In addition, regarding the configuration of the head unit 12, for example, it can be considered that some of the inkjet heads 102 are arranged with their positions in the sub-scanning direction shifted from the other inkjet heads 102.

[0026] Also, in the present embodiment, the inkjet head 102 has a plurality of nozzle rows 112 (two nozzle rows 112), as shown by assigning the reference numerals 112a and 112b to the inkjet head 102 with the reference numeral 102a in the drawing to distinguish them from one another. In this case, the nozzle rows 112 can be considered as, for example, a row in which a plurality of nozzles are arranged at different positions in a predetermined nozzle row direction. In this embodiment, the nozzle row direction is parallel to the sub-scanning direction. The positions of the plurality of nozzle rows 112 in the main scanning direction are different from one another. The fact that the positions of the plurality of nozzle rows 112 in the main scanning direction are different from one another can be considered as, for example, that the positions of the plurality of nozzle rows 112 in the inkjet head 102 in the main scanning direction are different from one another when the inkjet head 102 is in a position at which ink is ejected onto the medium 50. Also, in this embodiment, the plurality of nozzle rows 112 in the same inkjet head 102 can be considered as, for example, a plurality of nozzle rows 112 in which the relative positions of one with respect to the other are known. The inkjet head 102 ejects, for example, ink of a plurality of colors from a plurality of nozzle rows 112. More specifically, in this case, the inkjet head 102 ejects, for example, ink of a first color from a first nozzle row 112, and ejects ink of a second color different from the first color from a second nozzle row 112 different from the first nozzle row 112. Furthermore, the inkjet head 102 may eject ink of the same color from a plurality of nozzle rows 112 depending on the desired printing content, etc.

[0027] Here, in this example, the printing device 10 performs printing by a multi-pass method. In this case, the multi-pass method can be considered as, for example, a method in which the number of main scanning operations performed in a state where one position of the medium 50 faces the nozzle row is multiple. Furthermore, when printing is performed in the printing device 10 of this example, the control unit 30 moves the head unit 12 relatively to the medium 50, so that the inkjet heads 102 in the head unit 12 are moved in sequence to directly above the rotating medium 50 and face the medium 50. In addition, as a result, the control unit 30 causes the multiple inkjet heads 102 to eject ink onto the medium 50 in sequence. More specifically, in this case, the control unit 30 causes, for example, a first inkjet head 102 to eject ink onto the entire printing range on the side of the medium 50 in a state where the first inkjet head 102 and the medium 50 face each other. Furthermore, after causing the first inkjet head 102 to eject ink onto the medium 50, the control unit 30 causes a second inkjet head 102 different from the first inkjet head 102 to face the medium 50, and in this state, causes the inkjet head 102 to eject ink onto the side surface of the medium 50 in the same manner as described above. By repeating similar operations thereafter, the control unit 30 causes the multiple inkjet heads 102 in the head unit 12 to eject ink onto the medium 50. According to this example, for example, printing onto the medium 50 can be performed appropriately.

[0028] Next, the configuration of the holding jig 40 used in the printing device 10 of this example will be described in more detail. FIG. 2 and FIG. 3 show an example of the configuration of the holding jig 40. FIG. 2(a) and FIG. 2(b) are a cross-sectional view and a top view showing a simplified example of the configuration of the holding jig 40. FIG. 3(a) is a cross-sectional view showing a more specific example of the configuration of the holding jig 40. FIG. 3(b) is a perspective view showing an example of the configuration of the ultraviolet irradiator 208 in the holding jig 40. As described above, in this example, the holding jig 40 holds the medium 50 rotatably. In addition, the holding jig 40 irradiates the outer surface of the medium 50 with ultraviolet rays. In order to perform these operations, in this example, the holding jig 40 has a housing unit 202, a cover 204, a rotation mechanism 206, an ultraviolet irradiator 208, a light source holding unit 210, and a cover moving means 212.

[0029] The housing part 202 is a housing part of the holding jig 40 that constitutes the bottom and side surfaces of the holding jig 40, and houses the rotating mechanism 206, the ultraviolet irradiator 208, the light source holding part 210, and the like between the housing part 202 and the cover 204. The cover 204 is a member that covers the upper surface of the holding jig 40. The upper surface of the holding jig 40 can be considered to be, for example, the surface of the holding jig 40 that faces the inkjet head 102 (see FIG. 1). The cover 204 can be considered to be, for example, a member that covers at least the ultraviolet irradiator 208 from the upper surface side of the holding jig 40. In this example, the cover 204 has an opening 220 at a position facing the nozzle row of the inkjet head 102, and covers the upper surface of the holding jig 40 while facing the nozzle row and the medium 50 at the position of the opening 220. In this case, the opening 220 at a position facing the nozzle row can be considered to be, for example, that the opening 220 is provided at a position facing the nozzle row of one of the inkjet heads 102 when the inkjet head 102 is opposed to the medium 50 during printing. The opening 220 can also be considered to be, for example, an opening on the upper surface of the holding jig 40 so that ink ejected from the nozzle row of the inkjet head 102 reaches the medium 50.

[0030] In this example, the cover 204 has a base portion 222 and a magnet sheet 224. The base portion 222 is a plate-like portion constituting the base portion of the cover 204, and holds the magnet sheet 224 at a position between the inkjet head 102 and the medium 50. The magnet sheet 224 is a removable portion of the cover 204, and is processed into a shape that matches the shape of the medium 50, for example. More specifically, as described above, in this example, the cover 204 has an opening 220. In this case, it is preferable that the opening 220 is shaped to match the shape of the medium 50 so that, for example, no unnecessary gap is generated between the opening 220 and the medium 50. Therefore, in this example, the opening 220 is formed in the magnet sheet 224, and the magnet sheet 224 is held by the base portion 222, so that the opening 220 of the cover 204 is shaped to match the shape of the medium 50. Also, in this case, as shown in the figure, for example, base portion 222 has an opening larger than opening 220 of cover 204, and holds magnet sheet 224 so as to cover a part of this larger opening. With this configuration, for example, opening 220 that matches the shape of medium 50 can be appropriately formed in cover 204. Also, in this case, magnet sheet 224 in cover 204 can be considered, for example, as a member or the like that matches the shape of medium 50. And base portion 222 can be considered, for example, as a part or the like that has a fixed shape that is independent of the shape of medium 50.

[0031] The rotation mechanism 206 is a mechanism that rotates the medium 50 while holding the medium 50 at a position facing the nozzle row of the inkjet head 102. In this example, the rotation mechanism 206 has a shaft portion 226 and a rotation drive portion 228. The shaft portion 226 is a portion that rotatably holds the medium 50, and for example, holds the medium 50 rotatably at one end side and the other end side of the axial direction of the rotation shaft of the medium 50. For example, a chuck or the like that is suited to the medium 50 can be suitably used as the shaft portion 226. The rotation drive portion 228 is a drive portion that rotates the shaft portion 226, and rotates the medium 50 together with the shaft portion 226 by rotating the shaft portion 226. With this configuration, the rotation mechanism 206 can appropriately hold and rotate the medium 50. As described above, in the printing device 10 (see FIG. 1) of this example, the inkjet head 102 is moved relative to the position of the medium 50 facing the nozzle row by rotating the medium 50 during the main scanning operation. In this case, the control unit 30 (see FIG. 1) in the printing device 10 controls the operation of the rotation drive unit 228, for example, to control the rotation operation of the rotation mechanism 206 to rotate the medium 50. The control unit 30 also controls the operation of the inkjet head 102 and the rotation mechanism 206 via the main scanning drive unit 16 (see FIG. 1), for example, to cause the rotation mechanism 206 to eject ink from the inkjet head 102 while rotating the medium 50. In addition, the control unit 30 causes the inkjet head 102 to perform the main scanning operation. In this example, the rotation mechanism 206 rotates the medium 50 so that the direction of movement of the outer surface of the medium 50 at the position facing the nozzle row of the inkjet head 102 is the main scanning direction. With this configuration, for example, it is possible to cause the inkjet head 102 to perform the main scanning operation appropriately.

[0032] The ultraviolet irradiator 208 is an ultraviolet light source (UV light source) that irradiates ultraviolet light onto the outer surface (side surface) of the medium 50, and is disposed in a position adjacent to the medium 50 in the housing part 202 of the holding jig 40, thereby irradiating ultraviolet light onto the outer surface of the rotating medium 50. In addition, the ultraviolet irradiator 208 thereby cures the ink (ultraviolet curable ink) attached to the medium 50. In this example, the ultraviolet irradiator 208 has a lighting part 242 and a canopy 244, as shown in FIG. 3B, for example. The lighting part 242 is a part that generates ultraviolet light in the ultraviolet irradiator 208, and has, for example, a plurality of UVLEDs. The UVLEDs can be considered to be, for example, light emitting diodes that emit ultraviolet light. The lighting part 242 is turned on, for example, according to the control of the control part 30. The canopy 244 is a light shielding member (light shielding part) for blocking a part of the ultraviolet light generated by the lighting part 242. In this example, the canopy 244 is disposed between the inkjet head 102 and the lighting unit 242, thereby blocking ultraviolet light traveling in a direction toward the inkjet head 102. By using such a canopy 244, for example, stray light traveling toward the inkjet head 102 can be appropriately reduced.

[0033] In this example, the ultraviolet irradiator 208 irradiates the medium 50 with ultraviolet rays from a position farther from the inkjet head 102 than the top of the medium 50. In this case, the top of the medium 50 can be considered to be, for example, the position on the medium 50 closest to the inkjet head 102. With this configuration, for example, the ultraviolet irradiator 208 can be easily and appropriately covered by the cover 204. This also makes it possible to more appropriately reduce stray light traveling from the ultraviolet irradiator 208 toward the inkjet head 102. More specifically, in this example, the ultraviolet irradiator 208 irradiates ultraviolet rays toward a position downstream in the rotation direction of the medium 50 from the landing position where the ink lands on the medium 50 and at a rotation angle of 90 degrees to 180 degrees from the landing position in the rotation direction. With this configuration, for example, the ink that has landed on the medium 50 can be appropriately irradiated with ultraviolet rays. Such an ultraviolet ray irradiation position can be considered to be, for example, a position rotated 1 / 4 to 1 / 2 revolution in the rotation direction from the ink landing position on the medium 50. Also, the ultraviolet ray irradiator 208 is preferably installed at a position where the reflected light from the medium 50 is directed away from the inkjet head 102 (for example, downward).

[0034] The light source holding unit 210 is a platform-like member that holds the ultraviolet irradiator 208. In this example, the light source holding unit 210 holds the ultraviolet irradiator 208 on its upper surface, thereby holding the ultraviolet irradiator 208 at a position where the ultraviolet irradiator 208 can be irradiated toward the outer surface of the medium 50. The cover moving means 212 is a means for moving the cover 204 in the vertical direction. In this case, the vertical direction can be considered to be, for example, a direction in which the distance between the inkjet head 102 and the cover 204 changes. In this example, the cover moving means 212 is a means for moving the cover 204 by manual operation by the user, and for example, moves the base part 222 in the cover 204 in the vertical direction in response to the rotation of a handle for manual operation, thereby moving the magnet sheet 224 together with the base part 222. In addition, the cover moving means 212 moves the cover 204 in the vertical direction in response to the user's operation. In this case, it is considered that the cover moving means 212 moves the cover 204 in the vertical direction in accordance with, for example, the size of the medium 50. More specifically, in order to appropriately reduce stray light traveling from the ultraviolet irradiator 208 toward the inkjet head 102, it is important, for example, not to create a large gap between the cover 204 and the medium 50. In order to prevent such a gap, it is preferable to bring the edge of the opening 220 of the cover 204 sufficiently close to the medium 50. In order to do so, it is preferable to move the cover 204 appropriately in the vertical direction according to the size of the medium 50, for example. Therefore, in this example, the cover 204 is moved by the cover moving means 212, so that, for example, the gap between the cover 204 and the medium 50 is made sufficiently small. In this case, making the gap between the cover 204 and the medium 50 sufficiently small can be considered, for example, to substantially eliminate the gap in the lateral direction of the medium 50. The gap in the lateral direction of the medium 50 can be considered, for example, to be a gap in a direction perpendicular to the rotation axis of the medium 50. Substantially eliminating the gap in the lateral direction can be considered, for example, to be a matter of reducing the gap to a degree that does not affect the rotation of the medium 50 and does not cause problematic stray light. According to this example, for example, the medium 50 can be appropriately held by the holding jig 40.Furthermore, the ink that has landed on the medium 50 can be properly cured by the ultraviolet irradiator 208 in the holding jig 40 .

[0035] Next, the countermeasure against stray light implemented in the printing device 10 of this example will be described in more detail. As described above, in this example, the cover 204 has a base portion 222 and a magnet sheet 224. The magnet sheet 224 is processed into a shape that matches the shape of the medium 50, for example. In this case, by using such a magnet sheet 224, the gap in the lateral direction of the medium 50 can be appropriately and sufficiently small, as shown in FIG. 4, for example. FIG. 4 is a diagram for explaining the magnet sheet 224 in the holding jig 40. In FIG. 4, the upper left diagram shows an example of a state in which the magnet sheet 224 is installed. Also, the lower right diagram shows an example of a state in which the magnet sheet 224 has been removed. As can be understood from the state shown in FIG. 4, in this example, by using the magnet sheet 224, the gap in the lateral direction of the medium 50 can be appropriately and sufficiently small, as described above.

[0036] However, even if the magnet sheet 224 is used in a shape that matches the shape of the medium 50, for example, if the position of the cover 204 in the vertical direction in which the cover 204 is moved by the cover moving means 212 (see FIG. 2) is inappropriate, an unintended gap may occur between the cover 204 and the medium 50, and problematic stray light may reach the inkjet head 102. Therefore, in the printing device 10 of this example, a sensor 20 (see FIG. 1) is used to detect the state of the gap that occurs between the cover 204 and the medium 50. In this case, the sensor 20 can be considered to be used, for example, to detect the position of the upper surface of the holding jig 40. In addition, in this example, a white tape 232 is attached to a predetermined position on the magnet sheet 224 to facilitate detection by the sensor 20. In this case, the tape 232 is an example of a light-reflective member that is attached to at least a part of at least one of the medium 50 and the cover 204. For example, a tape of a light-reflective color other than white may be used as the tape 232. In addition, a member other than the tape 232 may be used as the light-reflective member. In this example, the tape 232 can also be considered to indicate, for example, the location where detection is performed by the sensor 20. The operation of detecting the state of the gap using the sensor 20 will be described in more detail later.

[0037] As described above, in this example, the magnet sheet 224 is used and the position of the cover 204 in the up-down direction is adjusted, so that the gap in the lateral direction (main scanning direction, left-right direction) of the medium 50 can be appropriately and sufficiently small. In this case, the edge of the cover 204 and the medium 50 overlap in the up-down direction at the edge of the cover 204 in the lateral direction, so that stray light can be appropriately prevented. However, even in this case, if the gap is eliminated at one end side and the other end side (front side and back side) in the lateral direction and the front-rear direction (sub-scanning direction), the medium 50 will rotate with the cover 204 and the medium 50 in contact with each other, and scratches, etc., will easily occur on the medium 50. Therefore, at these positions, for example, gaps that are not blocked by either the cover 204 or the medium 50 are likely to occur. As a result, for example, if the inkjet head 102 is made to perform the main scanning operation and the sub-scanning operation by the conventional method, stray light leaking from the end in the front-rear direction will reach the inkjet head 102, and problems such as nozzle clogging will easily occur. In contrast, in this embodiment, the inkjet head 102 is caused to perform main scanning and sub-scanning operations so that the inkjet head 102 does not pass through the position of the gap between the cover 204 and the medium 50 in the front-to-rear direction, thereby making it difficult for the influence of such stray light to occur. Therefore, the main scanning and sub-scanning operations performed by the inkjet head 102 in this embodiment will be described in more detail below. Also, for the sake of convenience, first, an example of main scanning and sub-scanning operations that are the same as or similar to conventional methods will be described.

[0038] FIG. 5 is a diagram showing an example of main scanning and sub-scanning operations that are the same as or similar to conventional methods, and shows an example of main scanning and sub-scanning operations in which one inkjet head 102 ejects ink onto each position on the medium 50. The illustrated operation is an example of a two-pass operation in which two main scanning operations are performed onto each position on the medium 50. In addition, in FIG. 5, the regions indicated with letters A to D are regions whose width in the sub-scanning direction corresponds to the number of passes. These regions can also be considered, for example, as band regions corresponding to one pass. In the following, these regions are referred to as regions A to D. In addition, the operation will be described with the lower side of the figure as the front side and the upper side as the back side.

[0039] In the first main scanning operation (first scan) in the illustrated operation, the inkjet head 102 ejects ink in the first pass onto the region A. In this case, the inkjet head 102 is moved forward from the position corresponding to the front end of the print data, and ink is ejected onto the medium 50 using only a part (half) of the back side of the inkjet head 102. In addition, in the second main scanning operation (second scan), the inkjet head 102 ejects ink in the second pass onto the region A, and ejects ink in the first pass onto the region B. In this case, for example, as shown in the figure, the entire inkjet head 102 is used to eject ink onto the medium 50. When the second scan is completed, the image drawn by the inkjet head 102 onto the front end portion (front end portion) of the medium 50 corresponding to the region A is completed.

[0040] Thereafter, the inkjet head 102 ejects ink to each position on the medium 50 by performing the main scanning operation while performing the sub-scanning operation between the main scanning operations. More specifically, in the fourth main scanning operation (fourth scan) which is one before the last main scanning operation (final scan) in the illustrated operation, the inkjet head 102 ejects ink in the second pass onto the region C, and ejects ink in the first pass onto the region D. In this case, too, as shown in the figure, the entire inkjet head 102 is used to eject ink onto the medium 50. In contrast, in the fifth main scanning operation (fifth scan) which is the final scan, the inkjet head 102 is moved further to the back side by the sub-scanning operation, and the main scanning operation is performed in a state where the inkjet head 102 is ejected in the second pass onto the region D. Therefore, in this case, ink is ejected onto the medium 50 using only a portion (half) on the front side of the inkjet head 102. In this case, during some main scanning operations, such as the first scan and the fifth scan, the inkjet head 102 passes over a gap between the cover 204 and the medium 50 in the front-to-rear direction. This gap makes it easier for stray light to strike the inkjet head 102. As a result, problems such as nozzle clogging are more likely to occur in the inkjet head 102. In contrast, in this example, the inkjet head 102 is caused to perform main scanning operations and sub-scanning operations, for example, as shown in FIG. 6, thereby making such problems less likely to occur.

[0041] FIG. 6 is a diagram showing an example of the main scanning operation and the sub-scanning operation in this example, which shows an example of the main scanning operation and the sub-scanning operation in which one inkjet head 102 ejects ink to each position on the medium 50. As shown in the figure, in this example, for at least some of the main scanning operations and the sub-scanning operations, the way in which the inkjet head 102 is moved in the sub-scanning operation and the part of the inkjet head 102 to which ink is ejected in the main scanning operation are different from those shown in FIG. 5. This also eliminates the main scanning operation and the sub-scanning operation in which the inkjet head 102 passes over the gap between the cover 204 and the medium 50 in the front-rear direction. Such an operation can be considered, for example, as an operation in which the nozzle row of the inkjet head 102 is not extended outside the front and rear ends of the print data.

[0042] More specifically, the operation shown in FIG. 6 is an example of a two-pass operation, similar to the operation shown in FIG. 5. Moreover, the areas A to D are areas whose width in the sub-scanning direction corresponds to the number of passes. In this case, in the first scan in this example, for example, the inkjet head 102 is moved to a position where the front end of the medium 50 overlaps with the front end of the inkjet head 102, which is the end on the front side, in the sub-scanning direction, and the inkjet head 102 is made to perform a main scanning operation. In addition, in controlling the printing operation, it is also possible to treat the printing range (print target area) in which printing is performed on the medium 50 as the range of the medium 50. In this case, for example, the front end of the medium 50 can be considered to be a position corresponding to the front end of the printing range on the medium 50. In addition, the alignment of the front end of the medium 50 and the front end of the inkjet head 102 can be considered to be, for example, alignment of the position corresponding to the front end of the print data with the position of the front end of the inkjet head 102. In the first scan, as shown in the figure, only a portion (half) of the inkjet head 102 on the front side is used to eject ink onto the medium 50. As a result, in the first scan, the inkjet head 102 ejects ink for the first pass onto the area A.

[0043] After the first main scan, the second main scan is performed without substantially changing the position of the inkjet head 102 in the sub-scanning direction, as shown in the figure. In this case, the position of the inkjet head 102 in the sub-scanning direction is not substantially changed, which can be considered to mean, for example, that the position of the inkjet head 102 is not changed by a larger amount than a small distance movement amount for increasing the resolution in the sub-scanning direction. More specifically, in the printing device 10, by performing printing using a multi-pass method, for example, the print resolution in the sub-scanning direction can be made higher than the resolution corresponding to the nozzle pitch in the nozzle row. In this case, the nozzle pitch can be considered to be, for example, the interval between the nozzles in the nozzle row in the sub-scanning direction. In this case, for example, it can be considered that the inkjet head 102 is moved by a distance less than the nozzle pitch relative to the medium 50 between the first scan and the second scan. In this case, it can be considered that the position of the inkjet head 102 is not substantially changed in the sub-scanning direction, including the case where the inkjet head 102 is moved by such a short distance relative to the medium 50.

[0044] In the second scan, as shown in the figure, the entire inkjet head 102 is used to eject ink onto the medium 50. As a result, in the second scan, the inkjet head 102 ejects ink in a second pass onto region A, and ejects ink in a first pass onto region B. In this case as well, when the second scan is completed, the image drawn by the inkjet head 102 on the front end portion of the medium 50 corresponding to region A is completed.

[0045] Thereafter, until the rear end (rear end) of the inkjet head 102 reaches the rear end (rear end) of the medium 50, the inkjet head 102 ejects ink to each position on the medium 50 by performing the main scanning operation while performing the sub-scanning operation between the main scanning operations. In this case, the rear end of the inkjet head 102 reaching the rear end of the medium 50 can be considered to be, for example, that the rear end of the inkjet head 102 reaches the rear end of the medium 50 when a sub-scanning operation is performed with a standard movement amount (feed amount) in any one sub-scanning operation. The rear end of the inkjet head 102 reaching the rear end of the medium 50 in the sub-scanning operation can be considered to be, for example, that the rear end of the inkjet head 102 overlaps with the rear end of the medium 50 during or at the end of the sub-scanning operation. The standard movement amount in the sub-scanning operation can be considered to be, for example, a movement amount determined according to the number of passes. The movement amount determined according to the number of passes can be considered to be, for example, a movement amount corresponding to the distance obtained by dividing the nozzle row length by the number of passes. The nozzle row length can be considered to be, for example, the length of the nozzle row in the sub-scanning direction. In this example, the standard movement amount in the sub-scanning operation is a movement distance corresponding to the distance obtained by dividing the nozzle row length by the number of passes (distance corresponding to the number of passes). As described above, in controlling the printing operation, it is considered that the printing range is treated as the range of the medium 50. In this case, the rear end of the medium 50 can be considered to be, for example, a position corresponding to the other end of the printing range in the sub-scanning direction.

[0046] In the example shown in FIG. 6, in the sub-scanning operation performed immediately before the fourth scan, the rear end of the inkjet head 102 comes to the rear end of the medium 50. Therefore, in this case, after the main scanning operation of the second scan is performed, the sub-scanning operation is performed with a standard movement amount for each main scanning operation until the main scanning operation of the fourth scan is performed. In addition, in the main scanning operations of the second scan to the fourth scan, the entire inkjet head 102 is used to eject ink onto the medium 50. In this case, in the third scan, the inkjet head 102 ejects ink for the second pass onto the region B, and ejects ink for the first pass onto the region C. In addition, in the fourth scan, the inkjet head 102 ejects ink for the second pass onto the region C, and ejects ink for the first pass onto the region D.

[0047] However, if a sub-scanning operation is further performed with the standard movement amount after the main scanning operation for the fourth scan, the rear end of the inkjet head 102 will exceed the position of the rear end of the medium 50. Therefore, if such a sub-scanning operation is performed, the inkjet head 102 will pass over the gap between the cover 204 and the medium 50 in the front-rear direction during this sub-scanning operation and the next main scanning operation. In this case, stray light will hit the inkjet head 102 at the position of this gap, and problems such as nozzle clogging will easily occur. Therefore, in this example, the sub-scanning operation in which the rear end of the inkjet head 102 exceeds the position of the rear end of the medium 50 is not performed, and the subsequent main scanning operation is performed. More specifically, in this case, after the main scanning operation for the fourth scan, the main scanning operation for the fifth scan is performed without substantially changing the position of the inkjet head 102 in the sub-scanning direction. In addition, in this main scanning operation, as shown in the figure, for example, only a part (half) of the rear side of the inkjet head 102 is used to eject ink onto the medium 50. When configured in this manner, for example, during a sub-scanning operation, it is possible to appropriately prevent the inkjet head 102 from passing through the position of the gap (gap in the front-rear direction) between the cover 204 and the medium 50. This also makes it possible to appropriately perform a multi-pass printing operation on the medium 50, for example, without performing a main scanning operation in which the inkjet head 102 passes over the gap in the front-rear direction between the cover 204 and the medium 50. Therefore, according to this example, it is possible to appropriately prevent stray light (ultraviolet rays) from hitting the inkjet head 102 at the position of the gap between the cover 204 and the medium 50. This also makes it possible to make it difficult for nozzles in the inkjet head 102 to become clogged, for example.

[0048] As can be understood from the illustrated operations, in this example, it is considered that printing is performed on a printing range whose width in the sub-scanning direction is wider than the nozzle row length. Furthermore, when focusing on the control performed by the control unit 30 in the printing device 10 regarding such printing operations, it can be considered that the control unit 30 causes the inkjet head 102 to eject ink on a printing range whose width in the sub-scanning direction is wider than the nozzle row length by, for example, causing the inkjet head to perform a sub-scanning operation between at least some of the main scanning operations and causing the inkjet head to perform multiple main scanning operations.

[0049] 6, the printing operation described above can be considered as an operation in which the inkjet head 102 is always above the medium 50. The inkjet head 102 always above the medium 50 can be considered as an operation in which the inkjet head 102 does not pass above the gap between the cover 204 and the medium 50 at any timing of the main scanning operation and the sub-scanning operation performed with the ultraviolet irradiator 208 turned on during a series of printing operations. The function of the printing device 10 performing such printing operation can be considered as a function of completing printing without the inkjet head 102 protruding from the medium 50. In addition, if the range from one end to the other end of the medium 50 in the sub-scanning direction at a position facing the nozzle row of the inkjet head 102 is defined as the facing position medium range, the printing device 10 can be considered as causing the inkjet head 102 to perform the sub-scanning operation within a range in which the position of the nozzle row in the sub-scanning direction does not go outside the facing position medium range. Moreover, when focusing on the control of the control unit 30 with respect to such an operation, in this example, the control unit 30 causes the inkjet head 102 to perform all main scanning operations while the position of the nozzle row in the sub-scanning direction is within the opposing position medium range. In this case, the control unit 30 causes the inkjet head 102 to perform sub-scanning operations between at least some of the main scanning operations, for example, to cause the inkjet head 102 to perform printing on the entire side surface of the medium 50 at most. Printing on the entire side surface of the medium 50 by the inkjet head 102 can be considered to mean, for example, ejecting ink from the inkjet head 102 to a position on the entire side surface of the medium 50 where ink needs to be ejected by the inkjet head 102, depending on the image to be printed, etc. Also, printing on the entire side surface of the medium 50 can be considered to mean, for example, that the entire side surface of the medium 50 is a substantial printing range, etc. Regarding the entire side surface being the substantial printing range, it can be considered that the printing range is the range that an observer recognizes as the entirety, depending on, for example, the purpose of printing.

[0050] In this example, the printing range can be considered to be, for example, the printing range indicated by the print data. In addition, when focusing on the relationship between the print data and the printing operation, as can be understood from the above description, the printing operation shown in FIG. 5 corresponding to the conventional method can be considered to be, for example, an operation in which printing is started from the front side of the print data and printing is ended from the back side of the print data. In this case, for example, when printing is performed on the entire side of the medium 50 or a printing range close to it, there is a high risk that stray light will hit the inkjet head 102 at the position of the above-mentioned gap in the front-rear direction by using print data corresponding to a printing range approximately the same as the size of the medium 50. In contrast, in this example, even when print data corresponding to a printing range approximately the same as the size of the medium 50 is used, such a problem can be appropriately prevented from occurring.

[0051] As can be understood from the first and second scans in the operation shown in FIG. 6, in this example, the control unit 30 causes the inkjet head 102 to perform main scanning operations a number of times corresponding to the number of passes in a state in which one end (front end) of the medium 50 in the sub-scanning direction (front-rear direction) at a position facing the nozzle row is aligned with one end (front end) of the inkjet head 102 in the sub-scanning direction. In this case, the alignment of one end of the medium 50 with one end of the inkjet head 102 can be considered to be, for example, the alignment of one end of the medium 50 with one end of the nozzle row in the inkjet head 102. The number of main scanning operations corresponding to the number of passes can be considered to be, for example, the number of main scanning operations that need to be performed at that position depending on the number of passes. More specifically, in the case of the operation shown in FIG. 6, this number is two. In this embodiment, after the inkjet head 102 performs the main scanning operation a number of times corresponding to the number of passes in this state, the control unit 30 causes the inkjet head 102 to perform a sub-scanning operation at a standard movement amount (feed amount) before causing the inkjet head 102 to perform the next main scanning operation. With this configuration, for example, the inkjet head 102 can appropriately perform the main scanning operation for the number of passes to be performed first without performing a sub-scanning operation in which the inkjet head 102 passes through the position of the gap between the cover 204 and the medium 50 on one end side of the medium 50. This also makes it possible to appropriately prevent the inkjet head 102 from being exposed to ultraviolet light at the position of this gap during any of the sub-scanning operations or main scanning operations. Such an operation can also be considered as, for example, a configuration in which the first main scanning operation (the main scanning operation for the first scan) is started in a state in which one end of the medium 50 and one end of the inkjet head 102 are aligned.

[0052] As described above, for example, when the printing resolution in the sub-scanning direction is made higher than the resolution corresponding to the nozzle pitch, it is also possible to move the inkjet head 102 relative to the medium 50 by a distance less than the nozzle pitch between the first and second scans. In this case, for example, it is possible to perform a sub-scanning operation at a distance shorter than the standard movement amount in the sub-scanning direction while performing a main scanning operation for the first number of passes. More specifically, in this case, for example, during at least a part of the main scanning operations corresponding to the number of passes performed with one end of the medium 50 and one end of the inkjet head 102 aligned, the sub-scanning driver 18 (see FIG. 1) moves the inkjet head 102 in the sub-scanning direction relative to the medium 50 by a distance less than the nozzle pitch. As can be understood from the fourth and fifth scans in the operation shown in FIG. 6, in this example, the control unit 30 causes the inkjet head 102 to perform the main scanning operation and the sub-scanning operation so that the inkjet head 102 does not pass through the position of the gap between the cover 204 and the medium 50 even on the other end (rear end, inner end) of the medium 50 and the inkjet head 102. According to this example, for example, it is possible to more appropriately prevent the inkjet head 102 from being exposed to ultraviolet light at the position of the gap between the cover 204 and the medium 50, while appropriately printing at a high resolution. Also, in order to simplify the illustration and explanation, in FIG. 6, an example of the main scanning operation and the sub-scanning operation performed by the inkjet head 102 in the case where the width of the medium 50 in the sub-scanning direction is an integer multiple (four times) of the standard movement amount in the sub-scanning operation has been described. However, the size of the medium 50 may be different from that shown in FIG. 6, for example, as in the example shown in FIG. 7.

[0053] FIG. 7 is a diagram showing another example of the main scanning operation and the sub-scanning operation in this example, and shows an example in which a medium 50 larger in size in the sub-scanning direction than the case shown in FIG. 6 is used. FIG. 7(a) shows an example of the position of the inkjet head 102 during the Nth scan and the (N+1)th scan of the main scanning operation performed on a medium 50 of a predetermined size. FIG. 7(b) shows an example of the position of the inkjet head 102 during the (N-1)th scan and the Nth scan of the main scanning operation performed on a medium 50 of a predetermined size different from that shown in FIG. 7(a). More specifically, FIG. 7(a) shows an example in which the width of the medium 50 in the sub-scanning direction is larger by an integer multiple of the standard movement amount in the sub-scanning operation compared to the case shown in FIG. 6. In this case, in the sub-scanning operation performed immediately before the Nth (N is a predetermined integer) main scanning operation, the rear end (rear end) of the inkjet head 102 reaches the rear end position of the medium 50. Therefore, in this case, after the Nth main scanning operation is performed, the inkjet head 102 is caused to perform the necessary number of main scanning operations thereafter without substantially changing the position of the inkjet head 102 in the sub-scanning direction, as shown for example as the N+1th main scanning operation in the figure. Also, in this case, ink is ejected onto the medium 50 using only a portion (half) of the inkjet head 102 on the far side, as in the case shown for example as the 5th main scanning operation in Figure 6. Also in this case, for example, between multiple main scanning operations performed in this state, the inkjet head 102 is caused to perform a sub-scanning operation in which the inkjet head 102 moves relatively a distance less than the nozzle pitch, as necessary.

[0054] Also, FIG. 7(b) shows an example in which the width of the medium 50 in the sub-scanning direction is slightly smaller than that shown in FIG. 7(a). More specifically, in FIG. 7(b), the area F in the figure is smaller than that in FIG. 7(a). In this case, it can be considered that the width of the medium 50 in the sub-scanning direction shown in FIG. 7(b) is not an integer multiple of the standard movement amount in the sub-scanning operation, for example. In this case, if the inkjet head 102 is made to perform a sub-scanning operation with the standard movement amount after the main scanning operation of the (N-1)th scan shown in the figure, the rear end of the inkjet head 102 will exceed the position of the rear end of the medium 50. Therefore, in this case, in the sub-scanning operation after the main scanning operation of the (N-1)th scan, the inkjet head 102 is made to perform a sub-scanning operation with a movement amount smaller than the standard movement amount, so that the position of the rear end of the inkjet head 102 is aligned with the position of the rear end of the medium 50. With this configuration, for example, it is possible to appropriately prevent the inkjet head 102 from going out of the range facing the medium 50. In this case, in the main scanning operation performed after the Nth scan, only a part of the inkjet head 102 is used to eject ink onto the area to be ejected. With this configuration, for example, even if the width in the sub-scanning direction is not an integer multiple of the standard movement amount in the sub-scanning operation, it is possible to appropriately eject ink onto the medium 50 without the inkjet head 102 going out of the range facing the medium 50.

[0055] 6 and 7, the sub-scanning operation performed near the rear end of the medium 50 can be considered, for example, by focusing on the control of the control unit of the printing device 10. The end of the inkjet head 102 can be considered, for example, to correspond to the end of the nozzle row in the inkjet head 102. More specifically, in this case, in the sub-scanning operation performed in the sub-scanning operation in which the position of the rear end (other end) of the nozzle row in the inkjet head 102 exceeds the position of the rear end (other end) of the medium in the sub-scanning direction at the position facing the nozzle row when the movement distance of the inkjet head 102 relative to the medium 50 is set to the standard movement amount, the control unit 30 causes the inkjet head 102 to perform the sub-scanning operation so as to move the inkjet head 102 relative to the medium 50 by, for example, the movement distance until the rear end of the nozzle row reaches the position of the rear end of the medium 50. With this configuration, for example, it is possible to appropriately prevent the sub-scanning operation in which the end of the inkjet head 102 exceeds the end of the medium 50 on the rear side. This can more appropriately prevent ultraviolet rays from hitting the inkjet head 102 at the position of the gap between the cover 204 (see FIG. 2) of the holding jig 40 and the medium 50. In this case, as described above, the control unit 30 causes the inkjet head 102 to perform a sub-scanning operation in which the rear end of the nozzle row reaches the position of the rear end of the medium 50 in the sub-scanning direction, and then causes the inkjet head 102 to perform multiple main scanning operations as necessary in a state in which the rear end of the medium 50 and the rear end of the nozzle row are aligned. With this configuration, for example, the main scanning operation can be appropriately performed the required number of times for a range including the rear end of the medium 50. In this case, the state in which the rear end of the medium 50 and the rear end of the nozzle row are aligned may be, for example, a state in which the distance between the rear end of the medium and the rear end of the nozzle row is equal to or less than the nozzle pitch. The rear end of the medium 50 may be, for example, the rear end of the printing range.In this case, the alignment of the rear end of the medium 50 with the rear end of the nozzle row can be considered to correspond to, for example, the alignment of the end of the print data in the sub-scanning direction on the side corresponding to the rear side of the medium 50 with the end of the nozzle row on the rear side. In this state, the control unit 30 causes the inkjet head 102 to perform main scanning operations for the number of passes, for example. In addition, for convenience of illustration and explanation, the above description is mainly about the operation of printing in two passes. However, the number of passes of printing may be a number other than two. In this case, too, the ink can be appropriately ejected onto the medium 50 by performing an operation according to the number of passes in the same or similar manner as described above. In addition, in this case, for example, by appropriately changing the number of main scanning operations performed without substantially changing the position of the inkjet head 102 in the sub-scanning direction on the front side or rear side of the medium 50, the operation according to the number of passes can be appropriately executed even when the number of passes is greater than two.

[0056] As described above, in this example, the inkjet head 102 is caused to perform the main scanning operation and the sub-scanning operation at a position that matches the size of the medium 50, so that the stray light leaking from the holding jig 40 can be appropriately prevented from hitting the inkjet head 102. In this case, even if printing is performed to the full size of the medium 50, nozzle clogging due to the influence of stray light is unlikely to occur, so that printing using large-sized print data can be more appropriately performed. In addition, this makes it possible to more appropriately print, for example, the entire side surface of the medium 50. Furthermore, in this case, the influence of stray light can be appropriately reduced by controlling the main scanning operation and the sub-scanning operation by the control unit 30 without adding new parts to the printing device 10. In order to more appropriately reduce the influence of stray light, it is more preferable to make it difficult for stray light to leak outside the holding jig 40. In this case, as described above, it is important not to create a large gap between the cover 204 of the holding jig 40 and the medium 50. In contrast, as described above, in this example, the sensor 20 is used to detect the state of the gap between the cover 204 and the medium 50. Therefore, the operation of detecting the state of the gap using the sensor 20 will be described in more detail below.

[0057] FIG. 8 is a diagram showing an example of the operation of detecting the state of the gap using the sensor 20, and shows an example of the path along which the sensor 20 is moved when detecting the state. As described above, in the cover 204 of the holding jig 40 of this example, the white tape 232 is attached to a predetermined position on the magnet sheet 224. In this case, by using the tape 232, for example, the reflectance of light can be increased. This also makes it possible to perform detection using the sensor 20 more appropriately. Also, the tape 232 can be considered to indicate, for example, the location where detection is performed by the sensor 20. The tape 232 can be attached to the medium 50 as necessary. For example, when using a medium 50 with a color that does not easily reflect light, the tape 232 can be attached to the medium 50.

[0058] In this case, the control unit 30 (see FIG. 1) of the printing device 10 moves the sensor 20 along a path that allows the sensor 20 to detect reflected light from a position where the tape 232 is attached on at least one of the cover 204 and the medium 50. In this case, the control unit 30 controls the operation of the sensor moving means 22 (see FIG. 1) to move the sensor 20. More specifically, in this example, the control unit 30 moves the sensor 20 along multiple paths indicated by arrows in the figure. As the multiple paths, for example, paths on the front side, the back side, and the center of the medium 50 are used. In this case, the front side path is an example of a one-end side path that passes near one end of the medium 50 at a position facing the nozzle row of the inkjet head 102 (see FIG. 1) during printing. The back side path is an example of an other-end side path that passes near the other end of the medium 50 at a position facing the inkjet head 102 during printing. The central path is an example of an intermediate position path that passes over the medium 50 between the one end path and the other end path. These paths can be considered to be, for example, paths that intersect with the nozzle row direction. As can be understood from the illustrated configuration, these paths can also be considered to be, for example, paths that pass through the edge of the opening 220 of the cover 204. The multiple paths along which the sensor 20 is moved may further include paths other than these. In this example, the control unit 30 detects the state of the gap between the cover 204 and the medium 50 based on the output of the sensor 20 acquired while moving the sensor 20 along these paths. With this configuration, for example, the state of the gap between the cover 204 and the medium 50 can be detected. This also makes it possible to appropriately prevent, for example, unintended leakage of ultraviolet light due to misalignment of the cover 204.

[0059] Here, as described above, in this example, the control unit 30 detects the state of the gap between the cover 204 and the medium 50 based on the output of the sensor 20. In this case, the control unit 30 detects, for example, a change in the output of the sensor 20 that occurs at the position of the gap as the state of the gap. More specifically, as described above, in the cover 204 of this example, the magnet sheet 224 is used that is shaped to match the shape of the medium 50, so that the opening 220 is shaped so that an unnecessary gap is unlikely to occur between the cover 204 and the medium 50. However, even in this case, a certain degree of step will be generated at the edge of the opening 220. Therefore, when the sensor 20 is moved along a path that passes through the edge, a change in output corresponding to the step will occur at the edge. Therefore, the control unit 30 can detect the edge position of the opening 220 based on, for example, the output of the sensor 20. Also, in this case, if the gap at the edge position becomes large due to, for example, a shift in the height of the cover 204, the output of the sensor 20 will change depending on the size of the gap. In this case, the change in the output can be considered to reflect, for example, the state of the gap. Therefore, the control unit 30 can appropriately detect the state of the gap based on the output of the sensor 20 and the change in the output. In this example, the sensor 20 can be considered to detect, for example, reflected light from the cover 204 and the medium 50. In addition, the control unit 30 can be considered to detect the state of the gap based on the light detected by the sensor 20. In this case, the control unit 30 determines that the gap is enlarged when the reflectance at the edge of the opening 220 is smaller than a predetermined reference value. In this case, the reflectance detected by the sensor 20 can be considered to reflect, for example, the distance between the cover 204 and the medium 50. Therefore, the control unit 30 can be considered to detect, for example, such a distance. In this example, the sensor 20 is moved along the front side, the back side, and the center path as described above. With this configuration, for example, the state of the gap can be appropriately detected for a wide range of the medium 50.This also allows proper verification that, for example, media 50 and cover 204 are properly installed.

[0060] Also, it is considered that the ultraviolet irradiator 208 (see FIG. 2) in the holding jig 40 is turned off while the operation of detecting the state of the gap is performed using the sensor 20. With this configuration, for example, changes in reflectance occurring at the edge of the opening 220 can be more appropriately detected. In addition, in a modified example of the operation of detecting the state of the gap, for example, the detection by the sensor 20 can be performed with the ultraviolet irradiator 208 turned on. In addition, in order to more reliably prevent unintended leakage of ultraviolet light from the gap between the cover 204 and the medium 50, it is also considered to further directly detect the ultraviolet light that actually leaks. More specifically, in this case, for example, with the ultraviolet irradiator 208 irradiating ultraviolet light onto the outer surface of the medium 50, the control unit 30 further detects ultraviolet light leaking from the gap between the edge of the opening 220 of the cover 204 and the medium 50 based on the output of the sensor 20. With this configuration, for example, when unintended leakage of ultraviolet light occurs due to misalignment of the cover 204, leakage of ultraviolet light can be more appropriately detected. In this case, it is also possible to move sensor 20 along the same path as when detecting the state of the gap. When detecting the ultraviolet light that actually leaks, sensor 20 may be moved along a path different from that when detecting the state of the gap. Also, it is preferable to detect the ultraviolet light that actually leaks not only at a position corresponding to the gap between cover 204 and medium 50 in the lateral direction of medium 50, but also at a position corresponding to the gap in the front-rear direction.

[0061] Next, the operation of detecting the state of the gap occurring between the cover 204 and the medium 50 will be described in more detail. FIG. 9 is a flow chart showing an example of the operation of detecting the state of the gap in the printing device 10. The operation shown in FIG. 9 is an example of the operation of a detection method for detecting the state of the printing device 10. Detecting the state of the printing device 10 can be considered to be, for example, detecting the state of the printing device 10 or the holding jig 40 used in the printing device 10. The operation shown in FIG. 9 can also be considered to be, for example, an example of the operation of work set detection. Work set detection can be considered to be, for example, detecting whether the medium 50 is properly placed on the holding jig 40. Proper placement of the medium 50 on the holding jig 40 can be considered to be, for example, that the medium 50 is properly placed, and that the height of the cover 204 of the holding jig 40 and the magnet sheet 224 on the cover 204 are placed in accordance with the position (height, etc.) of the medium 50. In this example, the control unit 30 of the printing device 10 starts control related to the work set detection in response to a user's instruction. In this case, for example, a menu (for example, a work set detection execution selection screen) is displayed on the monitor of the printing device 10 or a computer (control PC) that controls the operation of the printing device 10 to accept user instructions.

[0062] In addition, in the control operation related to the work set detection, the control unit 30 accepts the designation of the detection position for detecting the state of the gap from the user (S102). In this case, the control unit 30 accepts the user's instruction by, for example, having the user operate an input means (for example, an LED pointer, an up / down key, etc.) for inputting information to the printing device 10. In addition, in this example, the control unit 30 accepts the designation of the detection position from the user, for example, the detection position corresponding to the front side, the back side, and the center path shown in FIG. 8. With this configuration, for example, even if the printing range changes depending on the chuck used as the shaft portion 226 in the rotation mechanism 206 of the holding jig 40 or the medium 50, a preferable detection position can be appropriately set. After accepting the designation of the detection position from the user, the control unit 30 controls the operation of the sensor moving means 22 to move the sensor 20 along the path corresponding to the detection position. In addition, the control unit 30 thereby executes the detection operation for acquiring the output (sensor value) of the sensor 20 (S104).

[0063] Furthermore, the control unit 30 detects the state of the gap between the cover 204 and the medium 50 based on the output of the sensor 20 detected in step S104, and judges whether or not there is a problem with the state of the gap (S106). As described above, in this example, the control unit 30 judges that the gap is large when, for example, the reflectance at the edge position of the opening 220 is smaller than a predetermined reference value. Therefore, in step S106, the control unit 30 judges that there is a problem with the state of the gap when, for example, the output of the sensor 20 is below a predetermined threshold value at any position. In addition, the control unit 30 thereby judges that there is a problem with the state of the gap when, for example, the size of the gap is too wide.

[0064] Then, if the output of the sensor 20 is not below the threshold value in all paths, the control unit 30 determines that there is no problem with the gap state (S106, Yes) and ends the work set detection operation. On the other hand, if the output of the sensor 20 is below the threshold value in any position in any path, the control unit 30 determines that there is a problem with the gap state (S106, No). In this case, the control unit 30 displays an error message on the monitor of the printing device 10 or the computer that controls the operation of the printing device 10 (S108). In this example, after the user confirms the error message, the control unit 30 displays a screen on the monitor or the like that prompts the user to install the cover 204 again (cover set) (S110), and ends the work set detection operation. According to this example, for example, the work set detection operation can be performed appropriately.

[0065] In this example, the detection operation in step S104 may be affected by errors. Therefore, if it is determined in step S106 that the output of sensor 20 is below the threshold at any position on any path, it may be possible to return to step S104 and obtain the output of sensor 20 again. In this case, in step S106, the control unit 30 determines that there is a problem with the state of the gap if the output of sensor 20 is below the threshold at any position even after performing a preset number of times (e.g., about three times). With this configuration, for example, the work set detection operation can be performed more appropriately.

[0066] Next, supplementary explanations regarding each of the components described above will be given. As described above, in this example, the printing device 10 prints on the medium 50 while rotating the medium 50. In this case, for example, a cylindrical (cylindrical) medium 50 can be suitably used as the medium 50. In this case, the cylindrical medium can be considered as an example of a medium having a shape of a rotating body whose cross section in a plane perpendicular to the rotation axis is a circle. In addition, it is also possible to use a medium 50 having a shape other than a cylindrical shape. For example, a medium 50 having a shape of a rotating body can be suitably used as the medium 50 having a shape other than a cylindrical shape. For example, a medium 50 having a shape of a cone or a truncated cone (a truncated cone shape) can be used as such a medium 50. In addition, when a medium 50 having a shape such as a cone or a truncated cone is used, the holding jig 40 holds the medium 50 so that the height of the medium 50 at the position facing the inkjet head 102 (the position where the ink lands) is constant. In this case, for example, it is possible to hold the medium 50 so that the generating line of the medium 50, which is cone-shaped or the like, at the position facing the inkjet head 102 is horizontal by appropriately tilting the rotation axis that rotates the medium 50 relative to the horizontal direction.

[0067] Furthermore, when printing is performed on the medium 50 while rotating the medium 50 as in this example, it is conceivable that a seam 302 of the image will occur on the side of the medium 50, as shown in Fig. 10 for example. Fig. 10 is a diagram explaining how to print on the side of the medium 50. Figs. 10(a) and (b) show an example of how to print on the side of the medium 50.

[0068] As can be understood from the seam 302 shown in FIG. 10, the seam 302 of the image on the side surface of the medium 50 can be considered to be, for example, a boundary portion between a position where ink is first discharged onto the side surface in the main scanning operation (drawing start position) and a position where ink is last discharged onto the side surface in the main scanning operation (drawing end position). The seam 302 is usually considered to be formed in a straight line, for example, as shown in FIG. 10(a). In this case, the straight seam 302 can be considered to be, for example, a seam 302 in which ink dots formed by ink discharged to the drawing start and drawing end positions in the main scanning operation are aligned in a straight line. With this configuration, for example, the printing operation can be easily and appropriately controlled. However, in this case, if it is attempted to prevent the background color of the medium 50 from being seen at the seam 302, for example, ink dots overlap at the seam 302, and a dark line corresponding to the seam 302 is drawn, making the seam 302 more noticeable. In order to make the seam 302 less noticeable, it is possible to form a non-linear seam 302 as shown in FIG. 10(b), for example. In this case, the non-linear seam 302 can be considered as a seam 302 in which ink dots formed by ink ejected at the drawing start and end positions in the main scanning operation are not aligned in a straight line. In this case, it is also possible to form a jagged seam 302 as shown in the figure, for example. With this configuration, it is possible to more appropriately prevent the position of the seam 302 from being noticeable, for example. This also makes it possible to appropriately perform printing on the side of the medium 50 with higher quality, for example. [Industrial Applicability]

[0069] The present invention can be suitably used in, for example, a printing device. [Explanation of symbols]

[0070] 10 printing device, 102 inkjet head, 112 nozzle row, 12 head section, 14 base section, 16 main scanning drive section, 18 sub-scanning drive section, 20 sensor, 202 housing section, 204 cover, 206 rotation mechanism, 208 ultraviolet irradiator, 210 light source holder, 212 cover moving means, 22 sensor moving means, 220 opening, 222 base section, 224 magnet sheet, 226 shaft section, 228 rotation drive section, 232 tape, 242 lighting section, 244 visor, 30 control section, 302 joint, 40 holding jig, 50 medium

Claims

1. an inkjet head having a plurality of nozzles for printing using ultraviolet curable ink; a holding member for holding the three-dimensional medium to be printed; a sub-scanning drive unit that moves the inkjet head relatively to the medium in a sub-scanning direction that is parallel to the row direction in which the plurality of nozzles are arranged; Equipped with The holding member is a rotation mechanism that rotates the medium; an ultraviolet irradiator for irradiating the medium with ultraviolet light; a cover for covering the ultraviolet irradiator from the upper surface side of the holding member; and a rotation mechanism for rotating the medium; a rotation mechanism for rotating the medium; a rotation mechanism for rotating the medium; a rotation mechanism for rotating the medium;

2. 2. The printing device according to claim 1, wherein the inkjet head is caused to perform a sub-scanning operation in which the inkjet head moves in the sub-scanning direction relative to the medium by a distance corresponding to the number of passes, which is a movement distance corresponding to the distance obtained by dividing the nozzle row length by the number of passes.

3. a control unit for controlling the operation of the inkjet head; The control unit After the inkjet head performs the sub-scanning operation in which the other end of the nozzle array reaches the position of the other end of the medium in the sub-scanning direction, 3. The printing device according to claim 2, wherein the inkjet head is caused to perform a plurality of main scanning operations while the other end of the medium is aligned with the other end of the nozzle row.

4. Further comprising a control unit that controls the sensor and the sensor moving means, The printing device described in claim 1, characterized in that the control unit detects the state of the gap between the cover and the medium based on the output of the sensor obtained while the sensor moving means moves the sensor along a path passing through the edge of the opening of the cover.

5. A printing device that uses ultraviolet curable ink to print on a three-dimensional medium held by a holding member that holds a medium to be printed, An inkjet head; Control unit and Equipped with The holding member is a rotation mechanism that rotates the medium while holding the medium at a position facing the nozzle row; an ultraviolet irradiator that irradiates ultraviolet light onto the outer surface of the medium; a cover that covers at least the ultraviolet irradiator from the upper surface side of the holding member, the cover having an opening at a position facing the nozzle row, and that covers the upper surface of the holding member while causing the nozzle row and the medium to face each other at the position of the opening; a cover moving means for moving the cover in a direction in which the distance between the inkjet head and the cover changes; Equipped with A printing device characterized in that the control unit detects the state of the gap between the cover and the medium based on the output of the sensor obtained while moving the sensor using a sensor moving means along a path passing through the edge of the opening in the cover.

6. the sensor is a photosensor that detects light, and detects reflected light from the cover and the medium in a state where a light-reflective member is attached to a portion of the medium and the cover; The printing device according to claim 5 , wherein the control unit moves the sensor along a path along which the sensor detects reflected light from the medium and the position where the light-reflective member of the cover is attached.

7. the sensor is a photosensor that detects light, The printing device described in claim 5, characterized in that, when ultraviolet light is irradiated onto the outer surface of the medium by the ultraviolet irradiator, the control unit further detects ultraviolet light leaking from the gap between the edge of the opening in the cover and the medium based on the output of the sensor.

8. A printing method for printing using ultraviolet curable ink, an inkjet head having a plurality of nozzles; a holding member for holding the three-dimensional medium to be printed; Using moving the inkjet head relative to the medium in a sub-scanning direction parallel to a column direction in which the plurality of nozzles are arranged; The holding member is a rotation mechanism that rotates the medium; an ultraviolet irradiator for irradiating the medium with ultraviolet light; a cover for covering the ultraviolet irradiator from the upper surface side of the holding member; and a rotating mechanism for rotating the medium; a printing method for printing the medium within a range from one end to the other end of the medium in the sub-scanning direction;

9. 1. A detection method for detecting a state of a printing device that prints on a three-dimensional medium held by a holding member that holds a medium to be printed using ultraviolet curable ink, the method comprising: The holding member is a rotation mechanism that rotates the medium while holding the medium at a position facing the nozzle row; an ultraviolet irradiator that irradiates ultraviolet light onto the outer surface of the medium; a cover that covers at least the ultraviolet irradiator from the upper surface side of the holding member, the cover having an opening at a position facing the nozzle row, and that covers the upper surface of the holding member while causing the nozzle row and the medium to face each other at the position of the opening; a cover moving means for moving the cover in a direction in which the distance between the inkjet head and the cover changes; Equipped with A detection method characterized by detecting the state of the gap between the cover and the medium based on the output of the sensor obtained while moving the sensor by a sensor moving means along a path passing through the edge of the opening in the cover.

Images