Printing apparatus and control method thereof

Abstract

To provide a printing apparatus capable of preventing excessive irradiation of the outer peripheral surface of a printed material with ultraviolet rays, even when the length in a sub-scanning direction of an ultraviolet irradiation section that irradiates with ultraviolet rays the outer peripheral surface of a printed material having a cylindrical, truncated cone or conical outer shape is longer than the length in the sub-scanning direction of a printed part, which is a part of the printed material where printing is performed, and the width in the sub-scanning direction of an inkjet head is narrower than the length in the sub-scanning direction of the printed part.SOLUTION: In the printing apparatus, an ultraviolet irradiation part 36 is constituted of a plurality of divided irradiation parts 37-48 divided in a sub-scanning direction, and the plurality of divided irradiation parts 37-48 can be individually turned on. A control part of the printing apparatus controls a lighting range of the ultraviolet irradiation part 36 in the sub-scanning direction on the basis of a detection result of a position detection mechanism for detecting a relative position of an inkjet head 3 in the sub-scanning direction with respect to a printing medium 2 when printing the printing medium 2.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a printing apparatus for printing on the outer peripheral surface of a printing medium having a cylindrical, truncated conical or conical outer shape, and also to a method for controlling the printing apparatus. [Background technology]

[0002] Conventionally, there has been known a printing device for printing using ultraviolet-curable ink on the outer peripheral surface of a printing medium having a cylindrical, truncated cone, or conical outer shape (see, for example, Patent Document 1). The printing device described in Patent Document 1 includes an inkjet head that ejects ink toward the outer peripheral surface of the printing medium, an ultraviolet irradiation device that cures the ink ejected onto the outer peripheral surface of the printing medium, a stage having a table on which the ultraviolet irradiation device is placed, a carriage on which the inkjet head is mounted, a carriage drive mechanism that moves the carriage in the main scanning direction, a stage drive mechanism that moves the stage in the sub-scanning direction, and a table lifting mechanism that raises and lowers the table.

[0003] In the printing device described in Patent Document 1, an inkjet head is formed with a large number of nozzles that eject ink. The lower surface of the inkjet head is an ink ejection surface on which a large number of nozzles are formed. On the ink ejection surface, a nozzle row is formed with multiple nozzles arranged in the sub-scanning direction. The ultraviolet irradiation device includes a rotation mechanism that holds the print medium and rotates the print medium around its axis, and an ultraviolet irradiator that irradiates ultraviolet rays toward the outer peripheral surface of the print medium to which ink is attached. The ultraviolet irradiator includes an LED substrate on which a large number of LED chips that emit ultraviolet rays are mounted.

[0004] In the printing device described in Patent Document 1, the ultraviolet irradiation device is mounted on a table so that the axis of the print medium coincides with the sub-scanning direction when viewed from above. The length of the print medium in the sub-scanning direction set on the rotation mechanism is longer than the width of the inkjet head in the sub-scanning direction. In this printing device, the stage is stopped at a fixed position, and the print medium is rotated by the rotation mechanism while ink is ejected from the inkjet head, which is stopped at a fixed position, to print a portion of the image on the outer surface of the print medium. The stage is then moved a predetermined distance in the sub-scanning direction and stopped. After that, the print medium is again rotated by the rotation mechanism while ink is ejected from the inkjet head, which is stopped at a fixed position, to print a portion of the image on the outer surface of the print medium.

[0005] The printing device described in Patent Document 1 repeats the above operations to print on the outer peripheral surface of the substrate. When printing on the substrate, an ultraviolet irradiator irradiates the outer peripheral surface of the substrate with ultraviolet light. In the printing device described in Patent Document 1, the length of the LED substrate in the sub-scanning direction is longer than the length of the portion of the substrate where printing is performed in the sub-scanning direction, so that the ink applied to the outer peripheral surface of the substrate can be cured. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2023-88834 Summary of the Invention [Problem to be solved by the invention]

[0007] According to the inventor's investigation, in the printing device described in Patent Document 1, if the entire LED substrate is lit during printing on a substrate, excessive ultraviolet light may be irradiated onto the outer periphery of the substrate, causing the temperature of the substrate to rise excessively. If the temperature of the substrate rises excessively, defects such as deformation of the substrate may occur. Furthermore, the inventor's investigation revealed that, depending on the type of ink, irradiation of excessive ultraviolet light onto the outer periphery of the substrate may cause the ink to over-cure, resulting in cracks in the ink after drying (i.e., cracks may occur in the image printed on the substrate).

[0008] Therefore, an object of the present invention is to provide a printing device for printing using ultraviolet-curable ink on the outer peripheral surface of a printing medium having a cylindrical, truncated conical or conical outer shape, which is capable of preventing excessive ultraviolet light from being irradiated onto the outer peripheral surface of the printing medium, even if the length in the sub-scanning direction of the ultraviolet irradiator that irradiates ultraviolet light toward the outer peripheral surface of the printing medium is longer than the length in the sub-scanning direction of the printing portion that is the portion of the printing medium where printing is performed, and the width in the sub-scanning direction of the inkjet head is narrower than the length in the sub-scanning direction of the printing portion.

[0009] Another object of the present invention is to provide a control method for a printing device that uses ultraviolet-curable ink to print on the outer peripheral surface of a printing medium having a cylindrical, truncated cone, or conical outer shape, and that can prevent excessive ultraviolet light from being irradiated onto the outer peripheral surface of the printing medium even when the length of the ultraviolet light irradiating section in the sub-scanning direction is longer than the length of the printing medium in the sub-scanning direction and the width of the inkjet head in the sub-scanning direction is narrower than the length of the printing medium in the sub-scanning direction. [Means for solving the problem]

[0010] In order to solve the above problems, the printing device of the present invention is a printing device for printing with ultraviolet-curable ink on the outer peripheral surface of a printing substrate having a cylindrical, truncated conical or conical outer shape, and includes a rotation mechanism that holds the printing substrate and rotates the printing substrate around the axis of the printing substrate as the center of rotation, an inkjet head that is arranged above the printing substrate and ejects ink toward the outer peripheral surface of the printing substrate, an ultraviolet irradiator that irradiates ultraviolet rays toward the outer peripheral surface of the printing substrate to which the ink has adhered, a movement mechanism that moves the inkjet head relative to the rotation mechanism and the ultraviolet irradiator in a sub-scanning direction that is orthogonal to the up-down direction and parallel to the axis of the printing substrate when viewed from the up-down direction, a position detection mechanism that detects the relative position of the inkjet head in the sub-scanning direction with respect to the rotation mechanism and the ultraviolet irradiator, and a control device that controls the printing device. a control unit, wherein the inkjet head is formed with a plurality of nozzles that eject ink, the underside of the inkjet head is an ink ejection surface on which the plurality of nozzles are formed, and a nozzle row is formed on the ink ejection surface by a plurality of nozzles arranged in the sub-scanning direction, the length in the sub-scanning direction of the ultraviolet irradiation unit that is the part of the ultraviolet irradiator that irradiates ultraviolet light is longer than the length in the sub-scanning direction of the printing part that is the part on the printing medium where printing is performed, the width in the sub-scanning direction of the inkjet head is narrower than the length in the sub-scanning direction of the printing part, the ultraviolet irradiation unit is made up of a plurality of divided irradiation units that are divided in the sub-scanning direction, and the plurality of divided irradiation units can be turned on individually, and the control unit controls the lighting range of the ultraviolet irradiation units in the sub-scanning direction based on the detection result of the position detection mechanism when printing on the printing medium.

[0011] In order to solve the above-mentioned problems, a method for controlling a printing device of the present invention provides a printing device for printing on the outer peripheral surface of a printing medium having a cylindrical, truncated conical or conical outer shape using ultraviolet-curable ink, the printing device comprising: a rotation mechanism for holding the printing medium and rotating the printing medium around the axis of the printing medium as a rotation center; an inkjet head disposed above the printing medium and ejecting ink toward the outer peripheral surface of the printing medium; an ultraviolet irradiator for irradiating ultraviolet rays toward the outer peripheral surface of the printing medium to which the ink has adhered; a movement mechanism for moving the inkjet head relative to the rotation mechanism and the ultraviolet irradiator in a sub-scanning direction that is orthogonal to the up-down direction and parallel to the axis of the printing medium when viewed from the up-down direction; and a position detection mechanism for detecting the relative position of the inkjet head in the sub-scanning direction with respect to the rotation mechanism and the ultraviolet irradiator. The inkjet head is formed with a plurality of nozzles that eject ink, and the underside of the inkjet head serves as an ink ejection surface on which the plurality of nozzles are formed, and on the ink ejection surface, a nozzle row is formed by a plurality of nozzles arranged in the sub-scanning direction, the length in the sub-scanning direction of the ultraviolet irradiation section of the ultraviolet irradiator that irradiates ultraviolet light is longer than the length in the sub-scanning direction of the printable portion that is the portion on the printable material where printing is performed, the width in the sub-scanning direction of the inkjet head is narrower than the length in the sub-scanning direction of the printable portion, the ultraviolet irradiation section is made up of a plurality of divided irradiation sections that are divided in the sub-scanning direction, and the plurality of divided irradiation sections can be turned on individually. This is a control method for a printing device characterized in that, when printing on the printable material, the lighting range of the ultraviolet irradiation section in the sub-scanning direction is controlled based on the detection result of the position detection mechanism.

[0012] In the present invention, the ultraviolet irradiation unit is composed of multiple divided irradiation units divided in the sub-scanning direction, and each divided irradiation unit can be turned on individually. Furthermore, in the present invention, when printing on a substrate, the lighting range of the ultraviolet irradiation unit in the sub-scanning direction is controlled based on the detection results of a position detection mechanism that detects the relative position of the inkjet head in the sub-scanning direction with respect to the rotation mechanism and the ultraviolet irradiator. Therefore, in the present invention, when printing on a substrate, it is possible to light only the portion of the ultraviolet irradiation unit necessary for curing the ink, without lighting the entire ultraviolet irradiation unit. Therefore, in the present invention, even if the length of the ultraviolet irradiation unit in the sub-scanning direction is longer than the length of the substrate in the sub-scanning direction and the width of the inkjet head in the sub-scanning direction is narrower than the length of the substrate in the sub-scanning direction, it is possible to prevent excessive ultraviolet light from being irradiated onto the outer peripheral surface of the substrate.

[0013] In the present invention, it is preferable that one end of the inkjet head in the sub-scanning direction is defined as a first head end, the other end of the inkjet head in the sub-scanning direction is defined as a second head end, and the range between the first head end and the second head end in the sub-scanning direction is defined as a head arrangement range, and the control unit turns on the divided irradiation units of the ultraviolet irradiation unit that have at least a portion included in the head arrangement range. With this configuration, all of the divided irradiation units of the ultraviolet irradiation unit that have at least a portion included in the head arrangement range are turned on, making it possible to irradiate ultraviolet rays onto the entire portion of the printed area immediately after ink ejected from the inkjet head lands. Therefore, it is possible to properly cure the entire ink attached to that portion of the printed area.

[0014] In the present invention, when the first head end is located at the same position as the boundary between two divided irradiation units in the sub-scanning direction, the control unit preferably also turns on the divided irradiation unit that is adjacent to the boundary and located outside the first head end in the sub-scanning direction, and when the second head end is located at the same position as the boundary between two divided irradiation units in the sub-scanning direction, the control unit also turns on the divided irradiation unit that is adjacent to the boundary and located outside the second head end in the sub-scanning direction. This configuration makes it possible to reliably irradiate ultraviolet rays to the edge of a portion of the printed area in the sub-scanning direction immediately after ink ejected from the inkjet head lands. Therefore, it is possible to properly cure ink adhering to the edge of a portion of the printed area in the sub-scanning direction.

[0015] In the present invention, it is preferable that the intensities of the ultraviolet rays emitted from the multiple divided irradiation units are individually adjustable. With this configuration, it is possible to adjust the finish of the image printed on the outer peripheral surface of the printing medium by adjusting the intensities of the ultraviolet rays emitted from the divided irradiation units.

[0016] In the present invention, the intensities of the ultraviolet rays irradiated from the plurality of divided irradiation units can be individually adjusted, and the control unit prints a first printing unit by ejecting ink from the inkjet head toward the outer circumferential surface of the print medium while stopping the inkjet head relative to the rotation mechanism and the ultraviolet irradiator in the sub-scanning direction, and then moves the inkjet head a predetermined amount relative to the rotation mechanism and the ultraviolet irradiator in the sub-scanning direction and stops it, and then ejects ink from the inkjet head toward the outer circumferential surface of the print medium to print a second printing unit, and is the first divided printable portion, and the portion of the printable portion where the second printable portion is to be printed is the second divided printable portion. When printing the first printable portion, it is preferable to irradiate the first divided printable portion with ultraviolet light of a first intensity that semi-cures the ink adhering to the printable portion from the ultraviolet irradiation unit, and when printing the second printable portion, to irradiate the second divided printable portion with ultraviolet light of the first intensity from the ultraviolet irradiation unit, and to irradiate the first divided printable portion with ultraviolet light of a second intensity higher than the first intensity from the ultraviolet irradiation unit, and after printing the second printable portion, to irradiate the second divided printable portion with ultraviolet light of the second intensity from the ultraviolet irradiation unit. With this configuration, by repeating the printing operation as described above, it is possible to perform glossy printing (gloss printing) on ​​the outer peripheral surface of the printable material. [Effects of the Invention]

[0017] As described above, in the present invention, in a printing device for printing using ultraviolet-curable ink on the outer peripheral surface of a substrate having a cylindrical, truncated cone-shaped or conical outer shape, even if the length in the sub-scanning direction of the ultraviolet irradiation section, which is the part of the ultraviolet irradiator that irradiates ultraviolet rays toward the outer peripheral surface of the substrate, is longer than the length in the sub-scanning direction of the printing section, which is the part of the substrate where printing is performed, and even if the width in the sub-scanning direction of the inkjet head is narrower than the length in the sub-scanning direction of the printing section, it is possible to prevent excessive ultraviolet rays from being irradiated onto the outer peripheral surface of the substrate. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a front view illustrating a configuration of a printing apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a block diagram illustrating the configuration of the printing apparatus shown in FIG. [Figure 3] FIG. 2A is a bottom view of the inkjet head and carriage shown in FIG. 1, and FIG. 2B is a bottom view for explaining the configuration of the inkjet head shown in FIG. [Figure 4] FIG. 2 is a front view for explaining the configuration of the ultraviolet irradiation device shown in FIG. [Figure 5] FIG. 5 is a side view for explaining the configuration of the rotation mechanism shown in FIG. [Figure 6] FIG. 5 is a side view for explaining the configuration of the rotation mechanism shown in FIG. [Figure 7] 5 is a diagram for explaining the configuration of an ultraviolet irradiation unit shown in FIG. 4. FIG. [Figure 8] 10A and 10B are diagrams for explaining a method of controlling the lighting of an ultraviolet irradiation unit according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] (Overall configuration of the printing device) Fig. 1 is a front view illustrating the configuration of a printing device 1 according to an embodiment of the present invention. Fig. 2 is a block diagram illustrating the configuration of the printing device 1 shown in Fig. 1. Fig. 3(A) is a bottom view of the inkjet head 3 and carriage 7 shown in Fig. 1, and Fig. 3(B) is a bottom view illustrating the configuration of the inkjet head 3 shown in Fig. 3(A).

[0021] The printing device 1 of this embodiment is a device for printing on the outer peripheral surface of a printing substrate 2 having a cylindrical, truncated conical, or conical outer shape, and is, for example, a commercial inkjet printer. The printing device 1 prints on the outer peripheral surface of the printing substrate 2 using ultraviolet-curable ink. The printing substrate 2 is formed, for example, in a cylindrical shape. That is, the printing substrate 2 is formed in a cylindrical, truncated conical, or conical cylindrical shape. The printing substrate 2 is also formed, for example, from resin. The printing device 1 is capable of printing on multiple types of printing substrates 2 with different outer diameters and lengths.

[0022] The printing device 1 is equipped with inkjet heads 3 (hereinafter referred to as "heads 3") that eject ultraviolet-curable ink toward the outer peripheral surface of the print medium 2. The printing device 1 of this embodiment is equipped with multiple heads 3. Specifically, the printing device 1 is equipped with four heads 3. The printing device 1 also includes an ultraviolet irradiation device 4 for curing the ink ejected onto the outer peripheral surface of the print medium 2, a stage 6 having a table 5 on which the ultraviolet irradiation device 4 is placed, a carriage 7 on which the multiple heads 3 are mounted, a Y-bar 8 that holds the carriage 7 so as to allow movement in a main scanning direction perpendicular to the up-down direction (vertical direction), and a main body frame 9 that holds the stage 6 so as to allow movement in a sub-scanning direction perpendicular to the up-down direction and the main scanning direction.

[0023] The printing device 1 also includes a carriage drive mechanism 11 that moves the carriage 7 in the main scanning direction relative to the Y bar 8, a stage drive mechanism 12 that moves the stage 6 in the sub-scanning direction relative to the main frame 9, a table lifting mechanism 13 that raises and lowers the table 5, a control unit 14 that controls the printing device 1, and a position detection mechanism 15 that detects the position of the stage 6 in the sub-scanning direction.

[0024] The carriage drive mechanism 11 includes, for example, a motor as a drive source and a power transmission mechanism such as a belt and pulleys that transmits the power of the motor to the carriage 7. The stage drive mechanism 12 includes, for example, a motor 16 as a drive source and a power transmission mechanism such as a belt and pulleys that transmits the power of the motor 16 to the stage 6. The stage drive mechanism 12 moves the table 5 together with the stage 6 in the sub-scanning direction. The table lifting mechanism 13 includes, for example, a motor as a drive source and a power transmission mechanism such as a ball screw that transmits the power of the motor to the table 5.

[0025] In the following description, the sub-scanning direction (X direction in Fig. 1, etc.) is the front-to-rear direction, and the main scanning direction (Y direction in Fig. 1, etc.) is the left-to-right direction. In the following description, the X1 direction side in Fig. 5, etc., which is one side of the front-to-rear direction, is the "front" side, the X2 direction side in Fig. 5, etc., which is the opposite side, is the "rear" side, the Y1 direction side in Fig. 4, etc., which is one side of the left-to-right direction, is the "right" side, and the Y2 direction side in Fig. 2, etc., which is the opposite side, is the "left" side.

[0026] The upper surface of the table 5 is a plane perpendicular to the vertical direction. The ultraviolet irradiation device 4 placed on the table 5 is arranged below the head 3. The print medium 2 is held by the ultraviolet irradiation device 4 and arranged below the head 3. In other words, the head 3 is arranged above the print medium 2. The head 3 ejects ink downward. The ink ejected by the head 3 lands on the outer peripheral surface of the print medium 2 at the upper end of the print medium 2.

[0027] The head 3 has a plurality of nozzles 3a formed therein that eject ink. Specifically, the large number of nozzles 3a are formed on the bottom surface of the head 3. The bottom surface of the head 3 is an ink ejection surface 3c on which the plurality of nozzles 3a (specifically, the large number of nozzles 3a) are formed. On the ink ejection surface 3c, a nozzle row 3b is formed from the large number of nozzles 3a that are arranged in the sub-scanning direction (front-back direction). On the ink ejection surface 3c, a plurality of nozzle rows 3b that are arranged in the main scanning direction (left-right direction) are formed. The head 3 has a plurality of piezoelectric elements (piezo elements) that cause ink to be ejected from each of the plurality of nozzles 3a.

[0028] As shown in Figure 3(A), for example, three of the four heads 3 mounted on the carriage 7 are arranged at the same position in the front-to-rear direction and are aligned in the left-to-right direction. The remaining head 3 is arranged at a position offset from the other three heads 3 in the front-to-rear direction. Three of the four heads 3 eject color inks, and the remaining head 3 ejects white ink. The viscosity of the white ink is higher than the viscosity of the color inks.

[0029] The position detection mechanism 15 is, for example, an encoder (rotary encoder) for detecting the rotational position and rotational speed of the motor 16. The position detection mechanism 15 detects the position of the stage 6 in the sub-scanning direction (front-rear direction) based on the amount of rotation of the motor 16. The position detection mechanism 15 and the motor 16 are electrically connected to the control unit 14. The control unit 14 is also electrically connected to a PC (personal computer) 18. The PC 18 generates print data for printing on the print substrate 2. When printing on the print substrate 2, the print data generated by the PC 18 is sent from the PC 18 to the control unit 14. That is, when printing on the print substrate 2, the print data sent from the PC 18 is input to the control unit 14.

[0030] (Configuration of ultraviolet irradiation device) Fig. 4 is a front view for explaining the configuration of the ultraviolet irradiation device 4 shown in Fig. 1. Figs. 5 and 6 are side views for explaining the configuration of the rotation mechanism 21 shown in Fig. 4. Fig. 7 is a diagram for explaining the configuration of the LED substrate 36 shown in Fig. 4, etc.

[0031] The ultraviolet irradiation device 4 includes a rotation mechanism 21 that holds the substrate 2 and rotates it around its axis; an ultraviolet irradiator 22 that irradiates ultraviolet light toward the outer peripheral surface of the substrate 2 to which ink is attached; and a cover 23 that covers the rotation mechanism 21 and the ultraviolet irradiator 22 from above. The cover 23 has an opening 23a through which the upper end of the substrate 2 is positioned. The ultraviolet irradiation device 4 is placed on the table 5 so that the axis of the substrate 2 coincides with the front-to-rear direction when viewed from above. That is, the axis of the substrate 2 coincides with the front-to-rear direction when viewed from above, and the sub-scanning direction is parallel to the axis of the substrate 2 when viewed from above. The nozzle array 3b, which ejects ink toward the substrate 2 during printing, is positioned directly above the substrate 2.

[0032] The rotation mechanism 21 rotates the print substrate 2 when printing on the print substrate 2. In this embodiment, printing is performed on the print substrate 2 while the print substrate 2 is rotated by the rotation mechanism 21 with the stage 6 and carriage 7 stopped at a fixed position. When printing on the print substrate 2, the rotation mechanism 21 rotates the print substrate 2, for example, in a counterclockwise direction when viewed from the front. The rotation mechanism 21 includes a motor 25 as a drive source and a power transmission mechanism 26 for transmitting the power of the motor 25 to the print substrate 2.

[0033] The rotation mechanism 21 also includes a first rotating part 27 that holds one end of the printing medium 2, a first holding part 28 that rotatably holds the first rotating part 27, a second rotating part 29 that holds the other end of the printing medium 2, a second holding part 30 that rotatably holds the second rotating part 29, a rotating frame 31 to which the first holding part 28 and the second holding part 30 are attached, and an encoder (rotary encoder) 32 that detects the rotational position and rotational speed of the printing medium 2. Note that the power transmission mechanism 26 and the like are not shown in Figure 4.

[0034] The first rotating unit 27 and the second rotating unit 29 rotate together with the substrate 2. The first rotating unit 27 holds the rear end of the substrate 2, and the second rotating unit 29 holds the front end of the substrate 2. The power transmission mechanism 26 connects the first rotating unit 27 to the motor 25. The power transmission mechanism 26 includes a gear train 33. The gear train 33 includes a drive gear fixed to the output shaft of the motor 25 and a driven gear fixed to the first rotating unit 27. The encoder 32 is connected to the rear end of the first rotating unit 27. The second holding unit 30 is movable in the direction of the axis of the substrate 2. In this embodiment, the positions of the second rotating unit 29 and the second holding unit 30 in the direction of the axis of the substrate 2 are adjusted depending on the length of the substrate 2. The power transmission mechanism 26 may also be configured using pulleys, belts, etc.

[0035] The rotating frame 31 is rotatable relative to a lower frame 34 that constitutes the bottom surface of the ultraviolet irradiation device 4, with the left-right direction as the axis of rotation. The rotating frame 31 is also rotatable relative to the lower frame 34, with the rear end of the rotating frame 31 as the rotation center. In this embodiment, by rotating the rotating frame 31 relative to the lower frame 34, it is possible to adjust the inclination of the rotation mechanism 21 relative to the horizontal direction when viewed from the left-right direction. In other words, by rotating the rotating frame 31 relative to the lower frame 34, it is possible to adjust the inclination of the axis of the printing medium 2 relative to the horizontal direction.

[0036] In this embodiment, when printing on a printing substrate 2 having a cylindrical outer shape, the direction of the axis of the printing substrate 2 coincides with the front-to-rear direction (see FIG. 5). On the other hand, when printing on a printing substrate 2 having a truncated cone or conical outer shape, the direction of the axis of the printing substrate 2 is inclined with respect to the front-to-rear direction (see FIG. 6). In other words, the inclination of the rotation mechanism 21 is adjusted when printing on the outer peripheral surface of a printing substrate 2 having a truncated cone or conical outer shape. Specifically, the inclination of the rotation mechanism 21 is adjusted so that the top end of the printing substrate 2 is parallel to the front-to-rear direction.

[0037] The ultraviolet irradiator 22 is equipped with an LED substrate 36 on which a number of light-emitting elements that emit ultraviolet rays (ultraviolet light) are mounted. The light-emitting elements are LED chips (UVLED chips). The ultraviolet irradiator 22 is disposed on the left side of the substrate 2. The ultraviolet irradiator 22 irradiates the substrate 2 with ultraviolet rays from the left side immediately after ink has landed thereon. In this embodiment, the vertical position of the ultraviolet irradiator 22 is adjustable. In addition, the horizontal position of the ultraviolet irradiator 22 and the inclination of the ultraviolet irradiator 22 with respect to the axis of the substrate 2 when viewed from the vertical direction are adjustable. In this embodiment, when printing on a substrate 2 that has a cylindrical outer shape, the ultraviolet irradiator 22 is installed so that the ultraviolet ray emission surface of the ultraviolet irradiator 22 (i.e., the ultraviolet ray emission surface of the LED substrate 36) is parallel to the front-to-rear direction. In addition, when printing on a substrate 2 having a truncated cone or conical outer shape, the inclination of the ultraviolet irradiator 22 is adjusted so that the ultraviolet light emission surface of the ultraviolet irradiator 22 is parallel to the left end of the substrate 2.

[0038] As described above, the stage driving mechanism 12 moves the table 5 on which the ultraviolet irradiation device 4 is placed together with the stage 6 in the front-to-rear direction. In this embodiment, the relative positions of the rotation mechanism 21 and the ultraviolet irradiator 22 in the front-to-rear direction do not change. That is, in this embodiment, the relative positions of the printing medium 2 held by the rotation mechanism 21 and the ultraviolet irradiator 22 in the front-to-rear direction do not change. The stage driving mechanism 12 in this embodiment is a moving mechanism that moves the head 3 in the sub-scanning direction relative to the rotation mechanism 21 and the ultraviolet irradiator 22. Also, as described above, the position detection mechanism 15 detects the position of the stage 6 in the front-to-rear direction based on the amount of rotation of the motor 16. That is, the position detection mechanism 15 in this embodiment is provided to detect the relative position of the head 3 in the sub-scanning direction relative to the rotation mechanism 21 and the ultraviolet irradiator 22.

[0039] The LED substrate 36 is formed in the shape of a long, narrow rectangular plate. The LED substrate 36 is arranged so that the thickness direction of the LED substrate 36 coincides with the left-right direction. When viewed from the left-right direction, the LED substrate 36 is arranged so that the direction of the short side of the rectangular LED substrate 36 coincides with the up-down direction and the direction of the long side of the LED substrate 36 coincides with the front-to-back direction. The ultraviolet light emission surface of the LED substrate 36 faces right. The LED substrate 36 in this embodiment serves as an ultraviolet light irradiation unit that irradiates ultraviolet light from the ultraviolet irradiator 22.

[0040] The front-to-rear length of the LED substrate 36 is longer than the front-to-rear length of the printing medium 2 when it is attached to the rotation mechanism 21. If the portion (range) of the printing medium 2 where printing is performed is defined as the printing portion 2a (see FIG. 7), the length of the printing portion 2a is equal to or shorter than the length of the printing medium 2. In other words, the front-to-rear length of the LED substrate 36 is longer than the front-to-rear length of the printing portion 2a when the printing medium 2 is attached to the rotation mechanism 21. Furthermore, the front-to-rear length of the LED substrate 36 is longer than the front-to-rear length of the longest printing medium 2 among the printing mediums 2 on which printing is performed by the printer 1.

[0041] The width of the head 3 in the front-to-rear direction is narrower than the length of the printing section 2a in the front-to-rear direction when the printing medium 2 is attached to the rotation mechanism 21. In other words, the length of the printing section 2a in the front-to-rear direction is wider than the width of the head 3 in the front-to-rear direction. Therefore, when printing on the printing medium 2, the printing medium 2 is moved in stages in the front-to-rear direction (sub-scanning direction) together with the table 5, rotation mechanism 21, etc., and printing is performed sequentially on the outer peripheral surface of the printing medium 2.

[0042] The LED substrate 36 is divided into a plurality of blocks in the front-rear direction and is composed of a plurality of divided irradiation sections 37 to 48 divided in the front-rear direction. In this embodiment, the LED substrate 36 is composed of 12 divided irradiation sections 37 to 48. The divided irradiation sections 37 to 48 are arranged in this order, for example, from the front to the rear. The divided irradiation sections 37 to 48 have the same width in the front-rear direction. The LED substrate 36 may be composed of 13 or more divided irradiation sections, or may be composed of fewer than 11 divided irradiation sections.

[0043] Each of the divided irradiation units 37 to 48 is electrically connected to the control unit 14. That is, the divided irradiation units 37 to 48 are individually connected to the control unit 14. The divided irradiation units 37 to 48 are current-controlled by the control unit 14. In this embodiment, the control unit 14 is capable of individually current-controlling the divided irradiation units 37 to 48. That is, the 12 divided irradiation units 37 to 48 can be individually turned on, and the control unit 14 turns each of the divided irradiation units 37 to 48 on or off individually. Furthermore, the intensity (illuminance) of the ultraviolet light emitted from the 12 divided irradiation units 37 to 48 can be individually adjusted.

[0044] (LED board control method) As described above, when printing on the substrate 2, print data transmitted from the PC 18 is input to the control unit 14. The control unit 14 prints on the substrate 2 based on the input print data. Also, as described above, when printing on the substrate 2, the substrate 2 is moved in stages in the front-to-rear direction together with the table 5, the rotation mechanism 21, etc., to sequentially print on the outer peripheral surface of the substrate 2. For example, the substrate 2 is moved in stages from the front to the rear, and printing is sequentially performed on the outer peripheral surface of the substrate 2 from the front to the rear of the substrate 2. That is, with the substrate 2 stopped at a fixed position in the front-to-rear direction, ink is ejected from the head 3, which is stopped at a fixed position, while the substrate 2 is rotated by the rotation mechanism 21, to first print on the front portion of the printing area 2a, as shown in FIG. 7(A).

[0045] Thereafter, the substrate 2 is moved forward a predetermined distance together with the stage 6 and table 5, etc., and stopped (i.e., the head 3 is moved backward relatively to the substrate 2 and stopped (see Figure 7(B))), and the substrate 2 is again rotated by the rotation mechanism 21, while ink is ejected from the head 3, which is stopped in a fixed position, to print on the middle part of the printing section 2a. Thereafter, in the same manner, the substrate 2 is moved forward a predetermined distance and stopped (i.e., the head 3 is moved backward relatively to the substrate 2 and stopped (see Figure 7(C))), and the substrate 2 is again rotated by the rotation mechanism 21, while ink is ejected from the head 3, which is stopped in a fixed position, to print on the rear part of the printing section 2a.

[0046] When printing on the substrate 2, the ultraviolet irradiator 22 irradiates the substrate 2 with ultraviolet light. Specifically, when printing on the substrate 2, the LED board 36 irradiates the substrate 2 with ultraviolet light. A method for controlling the LED board 36 when printing on the substrate 2 will be described below. In the following description, as an example, a method for controlling the LED board 36 will be described when the total front-to-back width of the three divided irradiation units 37 to 48 is equal to the front-to-back width of the head 3. In addition, in the following description, a method for controlling the LED board 36 will be described when the substrate 2 and the LED board 36 are moved forward in stages by a distance equal to the front-to-back width of the head 3 (i.e., when the head 3 is moved backward in stages relative to the substrate 2 and the LED board 36), as shown in FIG. 7.

[0047] The control unit 14 controls the lighting range of the LED substrate 36 in the front-to-rear direction based on the detection result of the position detection mechanism 15 when printing on the print medium 2. Specifically, the control unit 14 selects the divided irradiation units 37-48 to be lit from among the divided irradiation units 37-48 based on the relative position of the head 3 in the front-to-rear direction with respect to the rotation mechanism 21 and the ultraviolet irradiator 22 (i.e., the relative position of the head 3 in the front-to-rear direction with respect to the print medium 2 and the LED substrate 36) that is specified based on the detection result of the position detection mechanism 15 when printing on the print medium 2, and lights up the selected divided irradiation units 37-48.

[0048] In this embodiment, the front end of head 3, which is one end of head 3 in the sub-scanning direction, is defined as the first head end 3e, the rear end of head 3, which is the other end of head 3 in the sub-scanning direction, is defined as the second head end 3f, and the range between first head end 3e and second head end 3f in the sub-scanning direction is defined as head placement range S. Control unit 14 lights up divided irradiation units 37 to 48 of LED substrate 36, at least a portion of which is included within head placement range S.

[0049] For example, as shown in FIG. 7(A), when printing on the front portion of the printing target area 2a, the control unit 14 turns on the divided irradiation units 38 and 39 that are entirely included within the head arrangement range S, and the divided irradiation units 37 and 40 that are partially included within the head arrangement range S. That is, the control unit 14 turns on all of the divided irradiation units 37 to 40 that are at least partially included within the head arrangement range S (the divided irradiation units 37 to 40 that are hatched in FIG. 7(A)). At this time, the control unit 14 does not turn on the remaining divided irradiation units 41 to 48. That is, at this time, only the divided irradiation units 37 to 40 are turned on, and the remaining divided irradiation units 41 to 48 are turned off.

[0050] 7(B), the control unit 14 turns on divided irradiation units 41 and 42 that are entirely within the head arrangement range S and divided irradiation units 40 and 43 that are partially within the head arrangement range S (i.e., turns on all of the divided irradiation units 40 to 43 that are hatched in FIG. 7(B)), and does not turn on the remaining divided irradiation units 37 to 39 and 44 to 48. Furthermore, when printing on the rear portion of the printable unit 2a, the control unit 14 turns on divided irradiation units 44 and 45 that are entirely within the head arrangement range S and divided irradiation units 43 and 46 that are partially within the head arrangement range S (i.e., turns on all of the divided irradiation units 43 to 46 that are hatched in FIG. 7(C)), and does not turn on the remaining divided irradiation units 37 to 42, 47, and 48.

[0051] 7(D), for example, when first head end 3e is arranged at the same position as the boundary between divided irradiation units 37 and 38 in the front-to-rear direction, control unit 14 also lights up divided irradiation units 37 that are not included in head arrangement range S. That is, when first head end 3e is arranged at the same position as the boundary between two divided irradiation units 37, 38 in the sub-scanning direction, control unit 14 also lights up divided irradiation units 37 that are in contact with the boundary between divided irradiation units 37, 38 and are arranged outside (i.e., in front of) first head end 3e in the sub-scanning direction.

[0052] 7(D), for example, when second head end 3f is arranged at the same position as the boundary between divided irradiation unit 40 and divided irradiation unit 41 in the front-to-rear direction, control unit 14 also lights up divided irradiation units 41 that are not included in head arrangement range S. In other words, when second head end 3f is arranged at the same position as the boundary between two divided irradiation units 40, 41 in the sub-scanning direction, control unit 14 also lights up divided irradiation units 41 that are in contact with the boundary between divided irradiation units 40, 41 and are arranged outside (i.e., behind) second head end 3f in the sub-scanning direction.

[0053] (Main effect of this form) As described above, in this embodiment, the LED substrate 36 is composed of a plurality of divided irradiation units 37-48 that are divided in the front-rear direction, and the plurality of divided irradiation units 37-48 can be individually turned on. Also, in this embodiment, the control unit 14 controls the lighting range of the LED substrate 36 in the front-rear direction based on the detection result of the position detection mechanism 15 during printing on the printing medium 2. Specifically, as shown in Figures 7(A) to 7(C), the control unit 14 lights up the divided irradiation units 37-48 of the LED substrate 36 that are at least partially included within the head arrangement range S, and does not light up the remaining divided irradiation units 37-48.

[0054] Furthermore, as shown in FIG. 7(D), when the first head end 3e is positioned at the same position as the boundary between the two divided irradiation units 37-48 in the front-to-back direction, or when the second head end 3f is positioned at the same position as the boundary between the two divided irradiation units 37-48 in the front-to-back direction, the control unit 14 lights up not only the divided irradiation units 37-48 that are at least partially included within the head placement range S, but also the divided irradiation units 37-48 that are in contact with the boundary between the two divided irradiation units 37-48 and are positioned outside the first head end 3e and the second head end 3f in the front-to-back direction.

[0055] Therefore, in this embodiment, it is possible to light up only the portion of the LED substrate 36 that is necessary for curing the ink. Therefore, in this embodiment, even if the length of the LED substrate 36 in the front-rear direction is longer than the length of the printing area 2a in the front-rear direction and the width of the head 3 in the front-rear direction is narrower than the length of the printing area 2a in the sub-scanning direction, it is possible to prevent excessive ultraviolet light from being irradiated onto the outer circumferential surface of the printing object 2.

[0056] 7(A) to 7(C), the control unit 14 turns on the divided irradiation units 37 to 48 of the LED substrate 36, at least a part of which is included within the head arrangement range S, so that it is possible to irradiate ultraviolet light onto the entire part of the printing target 2a immediately after the ink ejected from the head 3 lands. Therefore, in this embodiment, it is possible to properly cure the entire ink that has adhered to that part of the printing target 2a.

[0057] Furthermore, in this embodiment, when the first head end 3e is positioned at the same position as the boundary between the two divided irradiation units 37-48 in the front-to-rear direction, or when the second head end 3f is positioned at the same position as the boundary between the two divided irradiation units 37-48 in the front-to-rear direction, the control unit 14 turns on not only the divided irradiation units 37-48 at least a portion of which is included in the head arrangement range S, but also the divided irradiation units 37-48 that are in contact with the boundary between the two divided irradiation units 37-48 and are positioned outside the first head end 3e or the second head end 3f in the front-to-rear direction, so that ultraviolet rays can be reliably irradiated onto the front-to-rear edges of a portion of the printing target 2a immediately after the ink ejected from the head 3 lands. Therefore, in this embodiment, it is possible to properly cure ink that has adhered to the front-to-rear edges of a portion of the printing target 2a.

[0058] In this embodiment, the intensity of the ultraviolet light emitted from the multiple divided irradiation units 37 to 48 can be adjusted individually. Therefore, in this embodiment, by adjusting the intensity of the ultraviolet light emitted from the divided irradiation units 37 to 48, it is possible to adjust the finish of the image printed on the outer peripheral surface of the printing medium 2.

[0059] (Example of changing the control method for the LED board) FIG. 8 is a diagram for explaining a method of controlling the lighting of an LED board 36 according to another embodiment of the present invention.

[0060] In the embodiment described above, when gloss printing (gloss printing) is performed on the outer peripheral surface of the print medium 2 using clear ink (transparent ink) ejected from the head 3, the control unit 14 controls the lighting range of the LED substrate 36 in the front-to-rear direction based on the detection result of the position detection mechanism 15 during printing on the print medium 2, for example, as follows: In the following explanation, a method for controlling the LED substrate 36 when the total front-to-rear width of the two divided irradiation units 37 to 48 is equal to the front-to-rear width of the head 3 is described.

[0061] In the following description, the control unit 14 prints the printing section P1 by ejecting ink from the head 3 toward the outer peripheral surface of the printing medium 2 while rotating the printing medium 2 using the rotation mechanism 21 with the printing medium 2 stopped at a fixed position in the front-to-back direction (i.e., with the head 3 stopped relative to the printing medium 2 in the sub-scanning direction) (see FIG. 8A). Then, the control unit 14 moves the printing medium 2 forward by the width of the head 3 in the front-to-back direction and stops it (i.e., after moving the head 3 a predetermined amount relative to the printing medium 2 in the sub-scanning direction and stopping it), and then, while rotating the printing medium 2 using the rotation mechanism 21, ejects ink from the head 3 toward the outer peripheral surface of the printing medium 2 to print the printing section P2 (see FIG. 8B). The control unit 14 then prints the printing sections P3 and P4 in the same manner (see FIGS. 8C and 8D). The front-to-back width of the printing sections P1 to P4 is, for example, equal to the front-to-back width of the head 3.

[0062] In the following description, the area of ​​the printed portion 2a where printing portion P1 is printed will be referred to as divided printed portion 2b, the area of ​​the printed portion 2a where printing portion P2 is printed will be referred to as divided printed portion 2c, the area of ​​the printed portion 2a where printing portion P3 is printed will be referred to as divided printed portion 2d, and the area of ​​the printed portion 2a where printing portion P4 is printed will be referred to as divided printed portion 2e.

[0063] In this embodiment, in the relationship between printing section P1 and printing section P2, printing section P1 is the first printing section, and printing section P2 is the second printing section. Also, in the relationship between printing section P2 and printing section P3, printing section P2 is the first printing section, and printing section P3 is the second printing section. Furthermore, in the relationship between printing section P3 and printing section P4, printing section P3 is the first printing section, and printing section P4 is the second printing section. Also, in this embodiment, in the relationship between divided printing section 2b and divided printing section 2c, divided printing section 2b is the first divided printing section, and divided printing section 2c is the second divided printing section. Also, in the relationship between divided printing section 2c and divided printing section 2d, divided printing section 2c is the first divided printing section, and divided printing section 2d is the second divided printing section. Furthermore, in the relationship between the divided printing portion 2d and the divided printing portion 2e, the divided printing portion 2d is a first divided printing portion, and the divided printing portion 2e is a second divided printing portion.

[0064] When gloss printing is performed on the outer peripheral surface of the printing substrate 2, the control unit 14 causes the LED substrate 36 to irradiate the divided printing portions 2b with ultraviolet light of a first intensity that partially cures the ink adhering to the printing portion 2a (i.e., a first intensity that does not completely cure the ink) during printing of the printing portion P1. Specifically, as shown in FIG. 8(A), the divided irradiation units 39 (divided irradiation units 39 hatched in FIG. 8(A)) that are arranged at the same position in the front-to-back direction as the rear portion of the divided printing portion 2b are turned on to irradiate the divided printing portions 2b with ultraviolet light of the first intensity. At this time, the control unit 14 does not turn on the remaining divided irradiation units 37, 38, 40 to 48. In other words, the remaining divided irradiation units 37, 38, 40 to 48 are turned off.

[0065] Furthermore, during printing of the printing section P2, the control section 14 causes the LED substrate 36 to irradiate the divided printing section 2c with ultraviolet light of a first intensity, and also causes the LED substrate 36 to irradiate the divided printing section 2b with ultraviolet light of a second intensity higher than the first intensity. Specifically, as shown in FIG. 8(B), a divided irradiation section 41 (divided irradiation section 41 hatched in FIG. 8(B)) located at the same position as the rear portion of the divided printing section 2c in the front-to-back direction irradiates the divided printing section 2c with ultraviolet light of the first intensity, and two divided irradiation sections 38 and 39 (divided irradiation sections 38 and 39 hatched in the opposite direction to the hatching of the divided irradiation section 41 in FIG. 8(B)) located at the same position as the divided printing section 2b in the front-to-back direction irradiate the divided printing section 2b with ultraviolet light of the second intensity. At this time, the control section 14 does not light up the remaining divided irradiation sections 37, 40, 42 to 48. The ultraviolet light of the second intensity is ultraviolet light that can completely cure the ink in the printing portion P1.

[0066] Similarly, when printing the printing section P3, the control section 14 causes the LED substrate 36 to irradiate the divided printing section 2d with ultraviolet light of a first intensity, and causes the LED substrate 36 to irradiate the divided printing section 2c with ultraviolet light of a second intensity. That is, after printing the printing section P2, the control section 14 causes the LED substrate 36 to irradiate the divided printing section 2c with ultraviolet light of the second intensity. Specifically, as shown in FIG. 8(C), a divided irradiation section 43 arranged at the same position as the rear portion of the divided printing section 2d in the front-to-back direction irradiates the divided printing section 2d with ultraviolet light of the first intensity, and two divided irradiation sections 40, 41 arranged at the same position as the divided printing section 2c in the front-to-back direction irradiate the divided printing section 2c with ultraviolet light of the second intensity.

[0067] Furthermore, during printing of the printing section P4, the control unit 14 causes the LED substrate 36 to irradiate the divided printing section 2e with ultraviolet light of a first intensity, and also causes the LED substrate 36 to irradiate the divided printing section 2d with ultraviolet light of a second intensity. That is, after printing the printing section P3, the control unit 14 causes the LED substrate 36 to irradiate the divided printing section 2d with ultraviolet light of the second intensity. Specifically, as shown in FIG. 8(D), the divided irradiation unit 45, which is located at the same position as the rear portion of the divided printing section 2e in the front-to-back direction, irradiates the divided printing section 2e with ultraviolet light of the first intensity, and two divided irradiation units 43 and 44, which are located at the same position as the divided printing section 2d in the front-to-back direction, irradiate the divided printing section 2d with ultraviolet light of the second intensity. After printing of the printing section P4, the control unit 14 causes the LED substrate 36 to irradiate the divided printing section 2e with ultraviolet light of the second intensity.

[0068] In this modified example, it is also possible to light up only the portion of the LED substrate 36 that is necessary for curing the ink. Therefore, in this modified example, as in the above-described embodiment, even if the length of the LED substrate 36 in the front-rear direction is longer than the length of the printing portion 2a in the front-rear direction and the width of the head 3 in the front-rear direction is narrower than the length of the printing portion 2a in the sub-scanning direction, it is possible to prevent excessive ultraviolet light from being irradiated onto the outer peripheral surface of the printing medium 2.

[0069] (Other embodiments) The above-described embodiment is one example of a preferred embodiment of the present invention, but the present invention is not limited to this embodiment and various modifications can be made without departing from the spirit of the present invention.

[0070] In the above-described embodiment, when the first head end 3e is positioned at the same position as the boundary between the two divided irradiation units 37-48 in the front-to-rear direction or when the second head end 3f is positioned at the same position as the boundary between the two divided irradiation units 37-48 in the front-to-rear direction during printing on the print medium 2, the control unit 14 may turn on only the divided irradiation units 37-48 that are at least partially included within the head arrangement range S, and may not turn on the divided irradiation units 37-48 that are in contact with the boundary between the two divided irradiation units 37-48 and are positioned outside the first head end 3e or the second head end 3f in the front-to-rear direction. Also, in the above-described embodiment, the control unit 14 may turn on only the divided irradiation units 37-48 that are entirely included within the head arrangement range S during printing on the print medium 2, and may not turn on the divided irradiation units 37-48 that are only partially included within the head arrangement range S.

[0071] In the above-described embodiment, the position detection mechanism 15 for detecting the relative position of the head 3 in the sub-scanning direction with respect to the rotation mechanism 21 and the ultraviolet irradiator 22 does not have to be a rotary encoder for detecting the rotation position and rotation speed of the motor 16. For example, the position detection mechanism 15 may be a linear encoder for directly detecting the position of the stage 6, or may be an image sensor such as a camera installed above the table 5. Also, in the above-described embodiment, the intensities of the ultraviolet rays irradiated from the divided irradiation units 37 to 48 do not have to be individually adjustable.

[0072] In the above-described embodiment, the printing apparatus 1 may include, instead of the stage drive mechanism 12, a Y-bar drive mechanism that moves the Y-bar 8 together with the head 3 and carriage 7 in the sub-scanning direction. In this case, the Y-bar drive mechanism serves as a movement mechanism that moves the head 3 in the sub-scanning direction relative to the rotation mechanism 21 and the ultraviolet irradiator 22. Also, in the above-described embodiment, the divided irradiation units 37-48 may include divided irradiation units 37-48 whose front-to-rear widths differ from those of the other divided irradiation units 37-48. Furthermore, in the above-described embodiment, the ultraviolet irradiation unit that irradiates ultraviolet light of the ultraviolet irradiator 22 may be something other than the LED substrate 36.

[0073] In the above-described embodiment, if only printing on a substrate 2 having a fixed outer diameter is performed by the printing device 1, the vertical position of the ultraviolet irradiator 22 does not have to be adjustable. Furthermore, in the above-described embodiment, if only printing on a substrate 2 having a cylindrical outer shape is performed by the printing device 1, the tilt of the rotation mechanism 21 relative to the horizontal when viewed from the left and right does not have to be adjustable, and the tilt of the ultraviolet irradiator 22 relative to the axis of the substrate 2 when viewed from the top and bottom does not have to be adjustable. Furthermore, in the above-described embodiment, the ultraviolet irradiator 22 may be disposed below the substrate 2 or to the right of the substrate 2. Furthermore, in the above-described embodiment, the printing device 1 may have only one head 3. [Explanation of symbols]

[0074] 1 Printing device 2 Printing material 2a Printed area 2b Divided printed section (1st divided printed section) 2c, 2d Divided printed parts (1st divided printed part, 2nd divided printed part) 2e Divided printed section (2nd divided printed section) 3 heads (inkjet heads) 3a nozzle 3b Nozzle row 3c Ink ejection surface 3e First head end 3f 2nd head end 12 Stage drive mechanism (movement mechanism) 14 Control Unit 15 Position detection mechanism 21 Rotation mechanism 22 Ultraviolet irradiator 36 LED board (ultraviolet light irradiation part) 37~48 divided irradiation area P1 Printing Department (1st printing department) P2, P3 printing department (1st printing department, 2nd printing department) P4 Printing Department (Second Printing Department) S Head placement range X sub-scanning direction

Claims

1. A printing device for printing with ultraviolet-curable ink on the outer peripheral surface of a printing object having a cylindrical, truncated conical, or conical outer shape, a rotation mechanism that holds the substrate and rotates it around an axis of the substrate; an inkjet head that is disposed above the substrate and ejects ink toward the outer peripheral surface of the substrate; an ultraviolet irradiator that irradiates ultraviolet rays toward the outer peripheral surface of the substrate to which the ink is attached; a movement mechanism that moves the inkjet head relative to the rotation mechanism and the ultraviolet irradiator in a sub-scanning direction that is perpendicular to the up-down direction and parallel to the axis of the substrate when viewed from the up-down direction; a position detection mechanism that detects the relative position of the inkjet head in the sub-scanning direction with respect to the rotation mechanism and the ultraviolet irradiator; and a control unit that controls the printing device, The inkjet head is formed with a plurality of nozzles for ejecting ink, a lower surface of the inkjet head serving as an ink ejection surface on which a plurality of the nozzles are formed; On the ink ejection surface, a nozzle row is formed by a plurality of the nozzles arranged in a sub-scanning direction, a length in the sub-scanning direction of an ultraviolet irradiation section of the ultraviolet irradiator, which is a section that irradiates ultraviolet light, is longer than a length in the sub-scanning direction of a printing section, which is a section where printing is performed on the printing medium; a width of the inkjet head in the sub-scanning direction is narrower than a length of the printing portion in the sub-scanning direction; the ultraviolet irradiation unit is configured by a plurality of divided irradiation units divided in the sub-scanning direction, The plurality of divided irradiation units can be individually turned on, The printing device is characterized in that the control unit controls the lighting range of the ultraviolet irradiation unit in the sub-scanning direction based on the detection result of the position detection mechanism when printing on the printing medium.

2. When one end of the inkjet head in the sub-scanning direction is defined as a first head end, the other end of the inkjet head in the sub-scanning direction is defined as a second head end, and the range between the first head end and the second head end in the sub-scanning direction is defined as a head arrangement range, 2. The printing apparatus according to claim 1, wherein the control unit turns on the divided irradiation units of the ultraviolet irradiation unit, at least a part of which is included in the head arrangement range.

3. 3. The printing device according to claim 2, wherein when the first head end is positioned at the same position as the boundary between two of the divided irradiation units in the sub-scanning direction, the control unit also lights up the divided irradiation unit that is in contact with the boundary and is positioned outside the first head end in the sub-scanning direction, and when the second head end is positioned at the same position as the boundary between two of the divided irradiation units in the sub-scanning direction, the control unit also lights up the divided irradiation unit that is in contact with the boundary and is positioned outside the second head end in the sub-scanning direction.

4. 4. The printing device according to claim 1, wherein the intensities of the ultraviolet rays emitted from the plurality of divided irradiation units are individually adjustable.

5. The intensity of the ultraviolet rays irradiated from the plurality of divided irradiation units can be adjusted individually. The control unit a first printing section is printed by ejecting ink from the inkjet head toward the outer circumferential surface of the medium to be printed while the inkjet head is stopped relative to the rotation mechanism and the ultraviolet irradiator in the sub-scanning direction, and then the inkjet head is moved a predetermined distance relative to the rotation mechanism and the ultraviolet irradiator in the sub-scanning direction and stopped, and then the ink is ejected from the inkjet head toward the outer circumferential surface of the medium to be printed, and When a portion of the printing portion where the first printing portion is printed is defined as a first divided printing portion, and a portion of the printing portion where the second printing portion is printed is defined as a second divided printing portion, The printing device described in claim 1, characterized in that, when printing the first printing section, the ultraviolet irradiation section is caused to irradiate the first divided printing section with ultraviolet light of a first intensity that semi-cures the ink adhering to the printing section, and when printing the second printing section, the ultraviolet irradiation section is caused to irradiate the second divided printing section with ultraviolet light of the first intensity and the ultraviolet irradiation section is caused to irradiate the first divided printing section with ultraviolet light of a second intensity higher than the first intensity, and after printing the second printing section, the ultraviolet irradiation section is caused to irradiate the second divided printing section with ultraviolet light of the second intensity.

6. A printing device for printing with ultraviolet curable ink on the outer peripheral surface of a printing medium having a cylindrical, truncated conical or conical outer shape, the printing device comprising: a rotation mechanism for holding the printing medium and rotating the printing medium around the axis of the printing medium; an inkjet head disposed above the printing medium and ejecting ink toward the outer peripheral surface of the printing medium; an ultraviolet irradiator for irradiating ultraviolet rays toward the outer peripheral surface of the printing medium to which the ink has adhered; a movement mechanism for moving the inkjet head relative to the rotation mechanism and the ultraviolet irradiator in a sub-scanning direction that is perpendicular to the up-down direction and parallel to the axis of the printing medium when viewed from the up-down direction; and a movement mechanism for detecting the relative position of the inkjet head in the sub-scanning direction with respect to the rotation mechanism and the ultraviolet irradiator. a position detection mechanism for detecting a position of the inkjet head when the ink is ejected, the inkjet head having a plurality of nozzles formed therein, a bottom surface of the inkjet head being an ink ejection surface on which the plurality of nozzles are formed, the ink ejection surface having a nozzle row formed by the plurality of nozzles arranged in a sub-scanning direction, the length in the sub-scanning direction of an ultraviolet irradiation section of the ultraviolet irradiator which is a section that irradiates ultraviolet light is longer than the length in the sub-scanning direction of a printing section which is a section on the printing medium where printing is performed, the width in the sub-scanning direction of the inkjet head being narrower than the length in the sub-scanning direction of the printing section, the ultraviolet irradiation section being composed of a plurality of divided irradiation sections which are divided in the sub-scanning direction, and the plurality of divided irradiation sections can be turned on individually, A control method for a printing device, comprising controlling a lighting range of the ultraviolet irradiation unit in a sub-scanning direction based on a detection result of the position detection mechanism during printing on the printing medium.

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