Printing apparatus

Abstract

To make it easier to treat the inkjet heads used for printing on can bodies. [Solution] The control unit starts moving the multiple mandrels 230M in response to instructions from, for example, an instructor. Instructions from the instructor are received via a user interface (not shown). This user interface is configured, for example, as a touch panel. The control unit then stops moving the multiple mandrels 230M when a large gap 78 is positioned opposite the inkjet head 260. This ensures that a large gap 78 is positioned opposite the inkjet head 260.

Description

Technical Field

[0001] The present invention relates to a printing apparatus.

Background Art

[0002] Patent Document 1 discloses a configuration in which a cleaning function for the nozzle surface by spraying a cleaning liquid is added by using a cap for sucking bubbles inside the nozzle together with the ink.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a printing apparatus that performs printing on a can body, printing may be performed using an inkjet head. When using an inkjet head, treatments for the inkjet head, such as cleaning the inkjet head and inspecting the inkjet head, become necessary. An object of the present invention is to make it easier to perform treatments on an inkjet head used for printing on a can body.

Means for Solving the Problems

[0005] A printing apparatus to which the present invention is applied includes a plurality of can body support members that support a can body and perform circular movement, and an inkjet head that discharges ink onto the can body supported by the can body support members. The intervals between the arrangements of the plurality of can body support members are not constant, and the plurality of can body support members are provided in a form in which there are large gaps and small gaps.

[0006] The system may further include control means for stopping the plurality of can support members when the large gap is located opposite the inkjet head. Furthermore, the inkjet heads may be provided in multiple quantities and arranged in line with the direction of movement of the can support member, and the control means may stop the movement of the multiple can support members each time that the large gap is located at the opposing location of each of the multiple inkjet heads. Furthermore, the system may also include a cleaning device for cleaning the inkjet head when the large gap is located opposite the inkjet head. Furthermore, the cleaning device may be configured to move from outside the large gap into the large gap when the large gap is located opposite the inkjet head. Furthermore, multiple large gaps may be provided. Furthermore, the inkjet heads may be provided in multiple locations and arranged in line with the movement direction of the can support member, such that when one large gap is located at the opposing location of one inkjet head, another large gap is located at the opposing location of another inkjet head. Furthermore, some of the can body support members may be missing, and the large gap may be created as a result of the absence of some of the can body support members.

[0007] From another perspective, the printing apparatus to which the present invention is applied is a printing apparatus comprising: a plurality of can support members that support a can body and move in a circulating manner; an inkjet head that ejects ink onto the can body supported by the can support members; and a cleaning device that moves in a circulating manner and cleans the inkjet head.

[0008] In this case, a plurality of inkjet heads may be provided, and the cleaning device may clean each of the plurality of inkjet heads by sequentially passing through them. Furthermore, the cleaning device may be configured to circulate along a path that follows the path through which the plurality of can support members pass. Furthermore, the cleaning device may be provided in multiple locations, and the positions of the multiple can support members in the direction of movement may be offset from each other. Furthermore, the cleaning device may be provided between two adjacent can support members. Furthermore, the function of one cleaning device included in the multiple cleaning devices may be different from the functions of the other cleaning devices. Furthermore, the system may also include a mechanism to bring the cleaning device, which has stopped at a position opposite the inkjet head, closer to the inkjet head, and / or to bring the inkjet head closer to the cleaning device. Furthermore, the multiple can support members that perform circulating movement, and the cleaning device that performs circulating movement, may be supported by a common rotating member. [Effects of the Invention]

[0009] According to the present invention, it is possible to make it easier to treat the inkjet head used for printing on can bodies. [Brief explanation of the drawing]

[0010] [Figure 1] This is a diagram showing the printing machine viewed from above. [Figure 2] This is a cross-sectional view of the printing apparatus along line II-II in Figure 1. [Figure 3] This diagram shows the hardware configuration of the control unit. [Figure 4] This is a view of the inspection mechanism from the direction of arrow IV in Figure 1. [Figure 5] This diagram shows the state of the printing device when treatment is being performed on the inkjet head. [Figure 6] This diagram shows another example of a printing device configuration. [Figure 7]This is a diagram showing another configuration example of the printing apparatus. [Figure 8] This is a diagram showing another configuration example of the printing apparatus. [Figure 9] This is a diagram showing another configuration example of the printing apparatus. [Figure 10] This is a diagram when a part of the printing apparatus is viewed from the direction indicated by arrow X in FIG. 9. [Figure 11] This is a diagram showing another configuration example of the printing apparatus. [Figure 12] This is a diagram showing a printing apparatus in which a mandrel circulates and moves around a rotation center along a direction intersecting the vertical direction. [[ID=1)8]]

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram when the printing apparatus 100 according to this embodiment is viewed from above. FIG. 2 is a cross-sectional view of the printing apparatus 100 taken along line II-II in FIG. 1. In FIG. 1, the transmission member 50 shown in FIG. 2 is indicated by a broken line. The printing apparatus 100 forms an image on a can body 10 used for a beverage can or the like based on digital image information. Further, the printing apparatus 100 forms an image on the can body 10 using an inkjet printing method.

[0012] As shown in FIG. 2, the printing apparatus 100 is provided with a control unit 60. The control unit 60 controls each device and each mechanism unit provided in the printing apparatus 100. Also, as shown in FIG. 1, the printing apparatus 100 is provided with a rotating member 210. The rotating member 210 is driven by a first motor M1 shown in FIG. 2. The rotating member 210 rotates intermittently in the direction indicated by arrow 1A in the figure. The rotating member 210 is formed in a disk shape. The rotating member 210 rotates around the rotation center 1E shown in FIG. 1. This rotation center 1E extends in the vertical direction.

[0013] Inside the housing 290 shown in FIG. 2, a rotation mechanism (not shown) is provided. This rotating mechanism is composed of known mechanisms such as gears and cams. The rotating mechanism receives force from the first motor M1 to rotate the rotating member 210. In this embodiment, a rotation mechanism is provided around the rotating member 59.

[0014] Figure 3 shows the hardware configuration of the control unit 60. The control unit 60 is equipped with a processing unit 901 and an information storage device 902 for storing information. The processing unit 901 is comprised of a computer. The processing unit 901 has a CPU (=Central Processing Unit) 911 as an example of a processor. The processing unit 901 also has a ROM (=Read Only Memory) 912 in which the program is stored. Furthermore, the processing unit 901 has a RAM (=Random Access Memory) 913 used as a work area. The information storage device 902 is implemented using existing devices such as hard disk drives, semiconductor memory, and magnetic tape. The processing unit 901 and the information storage device 902 are connected via the bus 906 and signal lines (not shown).

[0015] The program executed by the CPU 911 can be provided to the control unit 60 via the recording medium. Examples of recording media include magnetic recording media such as magnetic tapes and magnetic disks. Other examples of recording media include optical recording media such as optical disks. Furthermore, magneto-optical recording media are another example. Finally, semiconductor memory is another example of a recording medium. Furthermore, the program executed by the CPU 911 may be provided to the control unit 60 using communication means such as the Internet. In this embodiment, the CPU 911 executes programs stored in the ROM 912 and the information storage device 902. This execution controls each device and mechanism provided in the printing device 100.

[0016] The printing apparatus 100 will be further described with reference to Figure 1. The printing device 100 is equipped with multiple holding mechanisms 230 for holding the can body 10. There are 15 holding mechanisms 230 in total. The holding mechanism 230 is not provided at the location indicated by reference numeral 1K. The holding mechanism 230 is missing at the location indicated by reference numeral 1K.

[0017] As indicated by reference numeral 1X, each of the holding mechanisms 230 is provided with a shaft 230S. The shaft 230S is supported by the rotating member 210 in a rotatable state. The shaft 230S is capable of rotation in the circumferential direction. Furthermore, as indicated by reference numeral 1X, each of the holding mechanisms 230 is provided with a mandrel 230M. This mandrel 230M, as an example of a can support member, supports the can 10. The mandrel 230M is attached to one end of the shaft 230S. The mandrel 230M is supported by the rotating member 210. Specifically, the mandrel 230M is supported by the rotating member 210 via the shaft 230S. The mandrel 230M is positioned away from the rotation center 1E of the rotating member 210.

[0018] The other end of the shaft 230S is provided with a receiving gear 230G, which serves as a receiving member to receive rotational driving force. The receiving gear 230G is composed of helical gears. The receiving gear 230G meshes with the transmission member 50 and receives rotational driving force from this transmission member 50. In this embodiment, as shown in Figure 2, a gear portion 50G is provided on the outer circumference of the transmission member 50. The gear portion 50G is provided along the circumferential direction of the transmission member 50. The receiving gear 230G meshes with the gear portion 50G provided on the outer circumference of the transmission member 50. The receiving gear 230G receives rotational driving force from the gear portion 50G.

[0019] Multiple shafts 230S and mandrels 230M are provided, as shown in Figure 1. Furthermore, the shafts 230S and mandrels 230M are arranged radially around the arrangement center 1C, indicated by reference numeral 1C in Figure 1. In other words, the shaft 230S and the mandrel 230M are arranged radially around the rotation center 1E of the rotating member 210. The center of arrangement 1C and the center of rotation 1E of the rotating member 210 coincide.

[0020] The can body 10 is formed in a cylindrical shape. Furthermore, one end of the can body 10 in the longitudinal direction is provided with a bottom. This end is closed. On the other hand, the other end of the can body 10 is not sealed but is open. An open section is provided at the other end of the can body 10. The can body 10 is supported by the mandrel 230M in the manner shown by arrow 1G in Figure 1. The can body 10 is supported by the mandrel 230M by inserting the mandrel 230M into the interior of the can body 10 through the open portion of the can body 10.

[0021] As shown in Figure 2, a disc-shaped transmission member 50 is provided above the receiving gear 230G. The transmission member 50 meshes with the receiving gears 230G provided on each of the holding mechanisms 230. The transmission member 50 transmits rotational driving force to the receiving gears 230G, causing the mandrel 230M to rotate. Furthermore, the transmission member 50 is not limited to being positioned above the receiving gear 230G. The transmission member 50 may also be positioned below the receiving gear 230G.

[0022] The transmission member 50 is arranged coaxially with the rotating member 210. The rotation center 1F of the transmission member 50 is located on the extension of the rotation center 1E of the rotating member 210 (see Figure 1). Furthermore, as shown in Figure 1, the transmission member 50 is connected to multiple mandrels 230M. The transmission member 50 is connected to a plurality of mandrels 230M via a receiving gear 230G and a shaft 230S. The transmission member 50 rotates to transmit rotational driving force to each of the multiple mandrels 230M.

[0023] A cylindrical rotating member 59 is provided below the transmission member 50 shown in Figure 2. The rotating member 59 is connected to the transmission member 50. The rotating member 59 extends downward from the center of rotation of the transmission member 50. In other words, the rotating member 59 extends downward from the radial center of the transmission member 50. In this embodiment, rotational driving force is transmitted from the rotating member 59 to the transmission member 50. This causes the transmission member 50 to rotate. Accordingly, rotational driving force is transmitted from the transmission member 50 to each of the multiple mandrels 230M. In this embodiment, as shown in Figure 2, a second motor M2 is provided to rotate the rotating member 59. The rotating member 59 rotates by receiving the driving force from this second motor M2.

[0024] The transmission member 50 rotates in the direction indicated by arrow 1D in Figure 1. In this embodiment, the receiving gear 230G meshes with the rotating transmission member 50. As a result, the receiving gear 230G rotates, causing the mandrel 230M to rotate in the direction indicated by arrow 1M. Consequently, the can body 10 also rotates in the direction indicated by arrow 1M. In this embodiment, the transmission member 50 rotates in the opposite direction to the direction indicated by arrow 1A, which is the rotation direction of the rotating member 210. Alternatively, the transmission member 50 may rotate in the same direction as the rotation direction of the rotating member 210. The transmission member 50 rotates with a rotation center 1F located in the radial center of the transmission member 50. In this embodiment, this rotation center 1F coincides with the arrangement center 1C of the radially arranged mandrels 230M.

[0025] As shown in Figure 1, when the printing device 100 is viewed from above, the rotation center 1F and the placement center 1C are located at the same location. Furthermore, the rotation center 1E of the rotating member 210 is located at the same location as the rotation center 1F and the placement center 1C. Furthermore, in this embodiment, the transmission member 50 is located closer to the center 1C than the radially arranged mandrels 230M.

[0026] Furthermore, as shown in Figure 1, the printing apparatus 100 is equipped with six inkjet heads 260 that function as image forming means. In addition, the printing apparatus 100 is equipped with support members that support the six inkjet heads 260. These support members are not shown in the illustration. Six inkjet heads 260 are provided, specifically the first inkjet head 261 to the sixth inkjet head 266. In this embodiment, an example of an image forming means is described in which an inkjet head 260 is used. However, the image forming means is not limited to this, and other methods of forming images may also be used.

[0027] Six inkjet heads 260 form images on the can body 10, which is supported by a mandrel 230M. The six inkjet heads 260 are arranged in the direction of movement on the can body 10. In other words, the six inkjet heads 260 are arranged in line with the direction of rotation of the rotating member 210. Furthermore, the six inkjet heads 260 are arranged radially around the rotation center 1E of the rotating member 210.

[0028] As shown in Figure 2, the inkjet head 260 is positioned above the ink tank 10. The inkjet head 260 ejects ink toward the ink tank 10 located below it. The inkjet head 260 has a facing surface 241 that faces the ink tank 10. This facing surface 241 is provided with a plurality of ink ejection ports for ejecting ink.

[0029] Each of the inkjet heads 260 ejects ultraviolet-curable ink to form an image on the outer surface of the inkjet can 10. Furthermore, the ink used is not limited to UV-curing ink. Other inks, such as thermosetting inks, may also be used. Furthermore, each of the 260 inkjet heads ejects different inks, such as yellow, magenta, cyan, black, white, and spot colors, into the ink cartridge 10.

[0030] As shown in Figure 1, a UV LED (Ultraviolet Light Emitting Diode) lamp 250 is also provided. Here, we assume the rotation direction of the rotating member 210. In this rotational direction, the UV LED lamp 250, which functions as a light irradiation means, is located downstream of the six inkjet heads 260. In the transport direction of the can body 10, the UV LED lamp 250 is located downstream of the six inkjet heads 260.

[0031] In this embodiment, ultraviolet light is irradiated onto the outer surface of the can body 10 by the UV LED lamp 250. As a result, the ultraviolet-curable ink that constitutes the image on the outer surface of the can body 10 hardens. Furthermore, in this embodiment, a lamp housing box 70 for housing the UV LED lamp 250 is provided. By providing this lamp housing box 70, the direction of ultraviolet light to areas other than the can body 10 is suppressed. The lamp housing box 70 is provided with an inlet 71 and an outlet 72. The can body 10, supported by the mandrel 230M, enters the lamp housing box 70 through the inlet 71. The can body 10, also supported by the mandrel 230M, then moves outside the lamp housing box 70 through the outlet 72.

[0032] The rotating member 210 moves the mandrel 230M by passing it through each of the multiple inkjet heads 260. Furthermore, the rotating member 210 stops rotating after each rotation by a predetermined angle. In this embodiment, a total of 16 mandrel stopping points 801 to 816 are provided. In this embodiment, the mandrel 230M stops at each of these mandrel stopping points 801 to 816. In other words, the can body 10 stops at each of these mandrel stopping points 801 to 816.

[0033] In this embodiment, the rotating member 210 is rotated intermittently to transport the can body 10 along a predetermined circular path. Furthermore, each time the can body 10 reaches one of the 16 mandrel stopping points 801 to 816, the can body 10 is temporarily stopped. In this embodiment, the rotating member 210 is rotated intermittently to cause the can body 10 to revolve. In addition, the can body 10 is temporarily stopped each time it reaches one of the 16 mandrel stopping points 801 to 816.

[0034] In this embodiment, inkjet heads 260 are provided at six mandrel stopping points 804 to 809. Furthermore, a UV LED lamp 250 is provided at one of the other mandrel stopping points 811. Hereinafter, in this specification, the mandrel stopping points 804 to 809 on which the inkjet head 260 is installed will be referred to as "image forming stopping points 804 to 809". Furthermore, the mandrel stopping point 811 where the UV LED lamp 250 is installed is referred to as the "light irradiation stopping point 811". In this embodiment, one additional mandrel stop location, indicated by reference numeral 810, is provided between the image-forming stop locations 804-809 and the light irradiation stop location 811.

[0035] In this embodiment, ultraviolet light is emitted from the UV LED lamp 250. In this case, ultraviolet light may reach the inkjet head 260 located upstream. In this case, the ink may harden at the inkjet head 260. In this case, ink clogging may occur, or the quality of the resulting image may deteriorate. Therefore, in this embodiment, as described above, one mandrel stop location 810 is provided between the image forming stop locations 804 to 809 and the light irradiation stop location 811.

[0036] This increases the distance between the UV LED lamp 250 and the inkjet head 260. In this case, the amount of ultraviolet light reaching the inkjet head 260 is reduced. Furthermore, the mandrel stopping point 810 is not limited to one; two or more mandrel stopping points 810 may be provided.

[0037] Furthermore, the printing apparatus 100 of this embodiment is provided with a can loading section 91, as shown in Figure 1. The can loading section 91 is located upstream of the multiple inkjet heads 260. In the can body insertion section 91, the inside of the cylindrically formed mandrel 230M is subjected to negative pressure. As a result, the mandrel 230M is drawn in by the can body 10, and the mandrel 230M enters the interior of the can body 10. This initiates the support of the can body 10 by the mandrel 230M.

[0038] An inspection mechanism 92 is provided between the can input section 91 and the inkjet head 260. This inspection mechanism 92, as an example of an inspection means, inspects the inserted can 10. In this embodiment, the inspection mechanism 92 is provided upstream of the inkjet head 260. In this embodiment, the can body 10 is inspected before image formation is performed by the inkjet head 260.

[0039] Figure 4 shows the inspection mechanism 92 as viewed from the direction of arrow IV in Figure 1. The inspection mechanism 92 inspects whether the can body 10 is deformed or not. As shown in Figure 4, the inspection mechanism 92 is equipped with a light source 92A that emits laser light. The light source 92A is located on one end of the can body 10. The laser light emitted from the light source 92A travels along the outer surface of the can body 10 and along the axial direction of the can body 10. Furthermore, a light-receiving unit 92B is provided at the other end of the can body 10 to receive laser light from the light source 92A.

[0040] If a part of the can body 10 is deformed as shown by reference numeral 3A, the laser light will be blocked. In this case, the light receiving unit 92B will not receive the laser light. This allows the deformation of the can body 10 to be detected. Furthermore, in this embodiment, as shown in Figure 1, a discharge mechanism 93 is provided as an example of a discharge means. The discharge mechanism 93 discharges the can body 10, which has been detected to be deformed, to the outside of the printing device 100. In this embodiment, if the inspection mechanism 92 determines that the can body 10 does not meet predetermined conditions, the discharge mechanism 93 discharges the can body 10. More specifically, if the inspection mechanism 92 determines that the can body 10 is deformed, the discharge mechanism 93 discharges the can body 10.

[0041] As shown in Figure 1, the ejection mechanism 93 is located between the inspection mechanism 92 and the inkjet head 260. The ejection mechanism 93 is located upstream of the inkjet head 260. Therefore, in this embodiment, the can body 10 is ejected before image formation is performed by the inkjet head 260.

[0042] In the discharge mechanism 93, compressed air is supplied to the inside of the mandrel 230M. This causes the can body 10 to move in the direction indicated by arrow 1H in the figure. Furthermore, the bottom of the can body 10 is sucked by a suction member (not shown). In other words, the closed end of the can body 10 is sucked by a suction member (not shown). Then, the suction member transports the can 10 to the outside of the printing device 100. As a result, the can 10 is discharged to the outside of the printing device 100.

[0043] The printing apparatus 100 will be further described with reference to Figure 1. A paint application device 94 is provided downstream of the UV LED lamp 250. In other words, a paint application device 94 is provided downstream of the mandrel stopping point 811. The paint application device 94 has a rotating body (not shown). In the paint application device 94, paint is first supplied to the outer surface of this rotating body. Then, the paint application device 94 brings the outer surface of the rotating body into contact with the outer surface of the can body 10. As a result, paint adheres to the outer surface of the can body 10. When paint adheres to the outer surface of the can body 10, a protective layer is formed on the outer surface of the can body 10.

[0044] Subsequently, in this embodiment, the can body 10 is discharged at the can body discharge section 95 downstream of the paint application device 94. In other words, the can body 10 is discharged at the mandrel stopping point 815. At the can body discharge section 95, compressed air is supplied to the inside of the mandrel 230M. This removes the can body 10 from the mandrel 230M. Furthermore, the can body 10 is transported to the outside of the printing device 100 by a transport mechanism (not shown). The can body 10, once transported outside the printing device 100, is then transported to a baking process (not shown). In this baking process, the can body 10 undergoes a heat treatment.

[0045] Referring to Figure 1, a series of operations of the printing device 100 will be explained. When printing is performed by the printing device 100, the transmission member 50 first starts rotating in the direction indicated by arrow 1D. This causes the mandrel 230M to start rotating in the direction indicated by arrow 1M. At the boiler input section 91, the boiler 10, which has been transported from the upstream side, is attached to the mandrel 230M. In this embodiment, the can 10 is transported from the upstream side to the can input section 91. At this time, an empty mandrel 230M is waiting in the can input section 91.

[0046] Furthermore, the inside of this empty mandrel 230M is subjected to negative pressure, and the can 10 is drawn in by this empty mandrel 230M. As a result, the mandrel 230M enters the inside of the can body 10. In this embodiment, the mandrel 230M enters the inside of the can body 10, thereby initiating support of the can body 10 by the mandrel 230M.

[0047] After the mandrel 230M begins supporting the can body 10, the rotating member 210, which was in a stationary state, starts to rotate. The rotating member 210 rotates by a predetermined angle in the direction indicated by arrow 1A in the figure and then stops again. This allows the can body 10 to reach the inspection mechanism 92. In other words, in this case, the can body 10 revolves and reaches the inspection mechanism 92. Subsequently, the rotating member 210 rotates again by a predetermined angle. This causes the can body 10 to revolve and reach the discharge mechanism 93. Subsequently, the rotating member 210 rotates again by a predetermined angle. As a result, the can body 10 revolves and reaches below the first inkjet head 261. The can body 10 then temporarily stops below the first inkjet head 261.

[0048] Then, ink is ejected from this first inkjet head 261 toward the rotating ink tank 10 located below it. In other words, ink is ejected from the first inkjet head 261 toward the rotating ink tank 10. As a result, an image is formed on the outer surface of the can body 10 using the first color of ink.

[0049] Subsequently, in this embodiment, the rotating member 210 is rotated and stopped again. As a result, the can body 10 stops below the second inkjet head 262, which is the second inkjet head 260. In other words, the can body 10 revolves and stops, and the can body 10 stops below the second inkjet head 262. Then, this second inkjet head 262 forms the image using the second color of ink.

[0050] Subsequently, in this embodiment, the ink cartridge 10 is moved to the third inkjet head 263. Then, the third inkjet head 263 forms an image. Subsequently, the ink cartridge 10 is moved to the fourth inkjet head 264. Then, the fourth inkjet head 264 forms an image. Furthermore, images are similarly formed on the fifth inkjet head 265 and the sixth inkjet head 266.

[0051] In the above explanation, we described the case where all six inkjet heads 260 are used to form an image as an example. The manner in which the image is formed is not limited thereto. The image may be formed using some of the six inkjet heads 260.

[0052] In this embodiment, the transmission member 50 rotates when the inkjet head 10 moves between the inkjet heads 260. In other words, in this embodiment, the transmission member 50 rotates when the inkjet head 10 revolves. This causes the can body 10 to rotate. When the can body 10 rotates, uneven ink application becomes less likely.

[0053] Let's consider the case where the can body 10 is moved while its rotation is stopped. In other words, let's consider the case where the can body 10 revolves around an orbit while it is not rotating on its own axis. In this case, the ink adhering to the can body 10 may move downward due to gravity, potentially causing uneven ink distribution. In contrast, in a configuration where the can body 10 rotates as it moves, uneven ink adhesion is less likely to occur.

[0054] After passing through the inkjet head 260, the ink can 10 moves to below the UV LED lamp 250. This causes ultraviolet light to be irradiated onto the outer surface of the ink can 10. As a result, the ink on the outer surface of the ink can 10 hardens. Subsequently, the paint is applied to the outer surface of the can body 10 by the paint application device 94.

[0055] Next, compressed air is supplied to the inside of the mandrel 230M at the can body discharge section 95. As a result, the inner surface of the can body 10 attached to the mandrel 230M is pressed by this compressed air. Consequently, the can body 10 is removed from the mandrel 230M. The can body 10, removed from the mandrel 230M, is transported to a baking process (not shown). In this baking process, heat treatment is performed, which hardens the paint applied to the can body 10.

[0056] Here, we will explain the arrangement of the mandrel 230M, which is a can support member. In this embodiment, multiple mandrels 230M are provided. These multiple mandrels 230M move around the rotation center 1E of the rotating member 210. The multiple mandrels 230M perform circulating movement. In this embodiment, the spacing between the multiple mandrels 230M is not constant. In this embodiment, the multiple mandrels 230M are provided with a large gap 78 and a small gap 79. Here, "interval" refers to the distance between two mandrels 230M that are adjacent to each other in the rotational direction of the rotating member 210.

[0057] The mandrel 230M is not present at the location indicated by the symbol 1K in Figure 1. The mandrel 230M is missing at the location indicated by the symbol 1K in Figure 1. In this embodiment, this defect results in a large gap 78 at the location indicated by reference numeral 1K. A gap exists between two adjacent mandrels 230M. In this embodiment, this gap is large at the location indicated by reference numeral 1K. A large gap 78 exists at the location indicated by reference numeral 1K.

[0058] In contrast, the gap between the two mandrels 230M is small in all locations except those indicated by symbol 1K. Small gaps 79 exist in other locations, such as those indicated by symbol 1M. In this embodiment, a large gap 78 is provided by the defect of a portion of the mandrel 230M.

[0059] A through-hole 210K is provided in the rotating member 210 at the location indicated by reference numeral 1K, through which a shaft 230S provided in the holding mechanism 230 passes. However, the holding mechanism 230 is not provided at the location indicated by reference numeral 1K. The location indicated by the symbol 1K is where the holding mechanism 230 can be installed. In other words, the location indicated by the symbol 1K is where the mandrel 230M can be installed.

[0060] In this embodiment, the mandrel 230M is intentionally omitted at the location indicated by reference numeral 1K. The location indicated by reference numeral 1K is missing the mandrel 230M. "Missing" can be described as a situation where the structure for installing the Mandrel 230M exists, but the Mandrel 230M is not actually installed.

[0061] Figure 5 shows the state of the printing apparatus 100 when treatment is being performed on the inkjet head 260. In Figure 5, the movement of the mandrel 230M has stopped. In this embodiment, the mandrel 230M is controlled when processing is performed on the inkjet head 260. The control of the mandrel 230M is performed by a control unit 60, which is an example of a control means. Specifically, the control unit 60 controls the position of the multiple mandrels 230M. In other words, the control unit 60 controls the stopping of the multiple moving mandrels 230M.

[0062] As shown in Figure 5, the control unit 60 stops the multiple mandrels 230M when a large gap 78 is located opposite the inkjet head 260. More specifically, the control unit 60 stops the multiple mandrels 230M when a large gap 78 is located opposite the first inkjet head 261. In this embodiment, when processing is performed on the inkjet head 260, the rotation of the transmission member 50 is also stopped.

[0063] The control unit 60 starts moving the multiple mandrels 230M in response to instructions from the user, for example. Instructions from the user are received via a user interface (not shown). This user interface is configured, for example, as a touch panel. Then, when the control unit 60 determines that a large gap 78 is located opposite the inkjet head 260, it stops the movement of the multiple mandrels 230M. As a result, as shown in Figure 5, a large gap 78 is positioned opposite the inkjet head 260. More specifically, in this example, the large gap 78 is positioned opposite the first inkjet head 261.

[0064] The movement of the mandrel 230M is controlled using a rotary encoder (not shown). This rotary encoder rotates in conjunction with the rotating member 210. The control unit 60 determines the rotation angle of the rotating member 210 based on the output from the rotary encoder. The control unit 60 controls the first motor M1 (see Figure 2) based on the specified rotation angle. The control unit 60 also controls the rotation of the rotating member 210 based on the specified rotation angle.

[0065] In this embodiment, the rotation angle of the rotating member 210 is registered in the information storage device 902 shown in Figure 3. The information storage device 902 registers the rotation angle when the large gap 78 is located directly below the first inkjet head 261. The control unit 60 controls the first motor M1 so that the angle determined based on the output from the rotary encoder matches the registered rotation angle.

[0066] As a result, the mandrel 230M stops with a large gap 78 located below the first inkjet head 261. The mandrel 230M stops when it is not positioned directly beneath the first inkjet head 261. When the mandrel 230M stops, the mandrel 230M will be positioned directly beneath each of the second inkjet heads 262 through the sixth inkjet heads 266.

[0067] Subsequently, in this embodiment, the operator performs treatment on the first inkjet head 261. Examples of such treatment include inspection and cleaning. The operator performs the procedure on the first inkjet head 261, which is located above the large gap 78. Here, the operator performs, for example, cleaning the first inkjet head 261. Furthermore, the treatment of the first inkjet head 261 may be performed using a device for treatment, such as a cleaning device described later. In this case, the device is installed in the large gap 78. Then, the treatment of the first inkjet head 261 is performed by this device.

[0068] The control unit 60 further performs control so that a large gap 78 is located at each of the opposing locations of the inkjet heads 260 other than the first inkjet head 261. The control unit 60 stops the movement of the multiple mandrels 230M whenever a large gap 78 is located between each of the opposing points of the second inkjet head 262 to the sixth inkjet head 266.

[0069] In performing control, the control unit 60 first stops the mandrel 230M so that a large gap 78 is located directly below the first inkjet head 261, as described above. Subsequently, the control unit 60 resumes moving the mandrel 230M. Next, the control unit 60 stops the mandrel 230M so that a large gap 78 is located directly below the second inkjet head 262.

[0070] Subsequently, the control unit 60 restarts the movement of the mandrel 230M and stops the movement of the mandrel 230M four more times. As a result, the mandrel 230M stops with a large gap 78 located directly below each of the third inkjet heads 263 to the sixth inkjet head 266. In this embodiment, the second inkjet head 262 to the sixth inkjet head 266 are also cleaned by a technician or equipment.

[0071] In this embodiment, multiple inkjet heads 260 are provided and are arranged in the direction of movement of the mandrel 230M. The control unit 60 stops the movement of the multiple mandrels 230M whenever a large gap 78 is positioned between each of the multiple inkjet heads 260. This makes it easier to clean each of the multiple inkjet heads 260.

[0072] Figure 6 shows another example configuration of the printing apparatus 100. Figure 6 shows the state when the first inkjet head 261 is viewed from the direction indicated by arrow VI in Figure 5. In Figure 6, a large gap 78 is located directly below the first inkjet head 261. In this state, the mandrel 230M is not located directly beneath the first inkjet head 261.

[0073] In this configuration example, a cleaning device 510 is provided for cleaning the inkjet head 260. The cleaning device 510 moves from outside the large gap 78 into the large gap 78, as indicated by arrow 6A. When a large gap 78 is located opposite the first inkjet head 261, the cleaning device 510 moves from outside the large gap 78 into the large gap 78.

[0074] In this embodiment, a moving mechanism 520 is provided for moving the cleaning device 510. This moving mechanism 520 causes the cleaning device 510 to move up and down. As a result, the cleaning device 510 moves from outside the large gap 78 into the large gap 78. In other words, the cleaning device 510 moves toward the first inkjet head 261. The moving mechanism 520 is equipped with a drive source such as a motor. The moving mechanism 520 may use any known mechanism and is not particularly limited.

[0075] The cleaning device 510 and the moving mechanism 520 are supported from below by a support portion 530. The support portion 530 is fixed to a device frame (not shown). The cleaning device 510 and the moving mechanism 520 are provided in a manner that corresponds to the first inkjet head 261. In addition, cleaning devices 510 and moving mechanisms 520 are provided, corresponding to each of the second to sixth inkjet heads 262 to 266. In this embodiment, six cleaning devices 510 and moving mechanisms 520 are provided.

[0076] After the cleaning device 510 moves from outside the large gap 78 to inside the large gap 78, the cleaning device 510 cleans the first inkjet head 261. The cleaning device 510 cleans the first inkjet head 261 when a large gap 78 is located opposite the first inkjet head 261. In other words, the cleaning device 510 cleans the first inkjet head 261 when a large gap 78 is located directly beneath the first inkjet head 261.

[0077] Once cleaning by the cleaning device 510 is complete, the cleaning device 510 descends. In other words, the cleaning device 510 retracts from the first inkjet head 261. Once cleaning by the cleaning device 510 is complete, the cleaning device 510 moves to a location off the movement path 540 of the mandrel 230M. This prevents interference between the cleaning device 510 and the mandrel 230M.

[0078] In Figure 6, the black circle indicated by the symbol 6B represents the movement path 540 of the mandrel 230M. This movement path 540 extends in a direction perpendicular to the plane of Figure 6. When the mandrel 230M is being circulated, the cleaning device 510 is located outside of this movement path 540. When cleaning is performed, the cleaning device 510 is positioned on this movement path 540.

[0079] The same process is also performed on the second inkjet head 262 to the sixth inkjet head 266. Whenever a large gap 78 is positioned directly beneath each inkjet head 260, the cleaning device 510 moves forward toward the inkjet head 260. Next, cleaning is performed by the cleaning device 510. After that, the cleaning device 510 is retracted.

[0080] In this embodiment, the cleaning device 510 is moved by control from the control unit 60. Furthermore, cleaning by the cleaning device 510 is initiated by control from the control unit 60. The cleaning of the inkjet head 260 by the cleaning device 510 is not particularly limited. The cleaning of the inkjet head 260 by the cleaning device 510 includes spraying cleaning solution onto the inkjet head 260.

[0081] Furthermore, the cleaning of the inkjet head 260 by the cleaning device 510 includes the spraying of gas. More specifically, it involves spraying gas onto the inkjet head 260. Blowing gas onto the inkjet head 260 accelerates the evaporation of the cleaning solution adhering to the inkjet head 260.

[0082] Figure 7 shows another example configuration of the printing device 100. Figure 7 shows the printing device 100 as viewed from above. In this configuration example, multiple large gaps 78 are provided. In this configuration example, when one large gap 78 is located opposite one inkjet head 260, another large gap 78 is located opposite the other inkjet head 260.

[0083] In Figure 7, one large gap 78 is located opposite the first inkjet head 261. Another large gap 78 is located opposite the third inkjet head 263. In the state shown in Figure 7, the first inkjet head 261 and the third inkjet head 263 are treated. Here, the first inkjet and third inkjet heads 263 are cleaned. This cleaning may be performed by a practitioner or by the cleaning device 510.

[0084] Subsequently, the large gap 78 moves, as described above. As a result, although not shown in the diagram, one large gap 78 is located opposite the second inkjet head 262. Additionally, another large gap 78 is located opposite the fourth inkjet head 264. Then, the second inkjet head 262 and the fourth inkjet head 264 are cleaned.

[0085] Subsequently, the large gap 78 moves further. As a result, in this configuration example, one large gap 78 is located opposite the third inkjet head 263. Additionally, another large gap 78 is located opposite the fifth inkjet head 265. Next, the fifth inkjet head 265 is cleaned. Subsequently, the large gap 78 moves further. As a result, in this configuration example, one large gap 78 is located opposite the fourth inkjet head 264. Additionally, another large gap 78 is located opposite the sixth inkjet head 266. Next, the sixth inkjet head 266 is cleaned.

[0086] In a configuration with multiple large gaps 78, multiple inkjet heads 260 can be cleaned simultaneously. For example, if there are multiple operators or multiple cleaning devices 510, multiple inkjet heads 260 can be cleaned simultaneously. In this case, cleaning the inkjet head 260 can be done in a shorter amount of time.

[0087] Although not shown in the diagram, three additional large gaps 78 may be provided. In this case, for example, a large gap 78 can be located at the opposing points of the first inkjet head 261, the third inkjet head 263, and the fifth inkjet head 265. Furthermore, in this case, a large gap 78 can be positioned at the opposing locations of the second inkjet head 262, the fourth inkjet head 264, and the sixth inkjet head 266.

[0088] Figure 8 shows another example of the configuration of the printing apparatus 100. In this configuration example, there are multiple missing mandrels (230M). In this configuration example, the multiple missing locations are adjacent to each other. In this configuration example, the mandrel 230M is not located between adjacent defective areas. In this configuration example, multiple defective areas are arranged consecutively in the rotational direction of the rotating member 210. In this configuration example, the gap 78 is larger than in the configuration shown in Figure 5.

[0089] In this configuration example shown in Figure 8, as in the configuration example shown in Figure 5, there is one large gap 78. The large gap 78 shown in Figure 8 is larger than the large gap 78 shown in Figure 5. In this configuration example shown in Figure 8, cleaning of multiple inkjet heads 260 can be performed simultaneously. Furthermore, in this case, the work efficiency when a technician cleans the inkjet head 260 is easily improved. A larger gap 78 provides more workspace. In this case, the work efficiency when a technician cleans the head is easily improved.

[0090] Figure 9 shows another example of the configuration of the printing device 100. Figure 10 shows a view of a part of the printing device 100 from the direction indicated by arrow X in Figure 9. Figure 9 shows the printing device 100 as viewed from above. In this configuration example, as shown in Figure 9, a cleaning device 510 for cleaning the inkjet head 260 is provided. The cleaning device 510 is supported by the rotating member 210. The cleaning device 510 also moves around the rotation center 1E of the rotating member 210. The cleaning device 510 also performs circulating movement. The cleaning device 510 is installed in a manner that corresponds to the location where the mandrel 230M is missing.

[0091] Multiple mandrels 230M that move in a circular motion, and a cleaning device 510 that also moves in a circular motion, are supported by a common rotating member 210. As a result, the cleaning device 510 moves along an annular path R2 that follows an annular path R1 through which multiple mandrels 230M pass.

[0092] The cleaning device 510 is installed between two mandrels 230M that are adjacent to each other. Furthermore, as shown in Figure 10, a moving mechanism 520 is provided for moving the cleaning device 510. The moving mechanism 520 moves the cleaning device 510, which has stopped at a position opposite the inkjet head 260, closer to the inkjet head 260. The cleaning device 510 and the moving mechanism 520 are supported from below by a support portion 530 fixed to the rotating member 210.

[0093] In this embodiment, the cleaning device 510 is stopped at the location opposite the inkjet head 260 that is to be cleaned. When the cleaning device 510 stops at this opposing point, the moving mechanism 520 is activated in response to an instruction from the control unit 60. In response, the cleaning device 510 moves closer to the inkjet head 260.

[0094] Subsequently, the cleaning device 510 cleans the inkjet head 260. Once the cleaning of the inkjet head 260 by the cleaning device 510 is complete, the cleaning device 510 moves away from the inkjet head 260. In addition, the inkjet head 260 may be configured to move closer to the stopped cleaning device 510. Alternatively, the cleaning device 510 may be positioned closer to the inkjet head 260, and the inkjet head 260 may be positioned closer to the cleaning device 510.

[0095] The cleaning device 510 shown in Figure 9 passes through each of the multiple inkjet heads 260 in sequence. The cleaning device 510 stops sequentially at each of the opposing locations of the multiple inkjet heads 260. The cleaning device 510 stops sequentially at each of the installation locations of the multiple inkjet heads 260. The cleaning device 510, having stopped in front of the inkjet head 260, approaches the inkjet head 260. Next, the cleaning device 510 cleans the inkjet head 260. After that, the cleaning device 510 moves away from the inkjet head 260.

[0096] Note that the moving mechanism 520 shown in Figure 10 is not essential. The cleaning device 510 may simply be configured to move in a circular motion. Furthermore, stopping the cleaning device 510 is not mandatory. The cleaning device 510 may be configured to clean the inkjet head 260 while moving.

[0097] Figure 11 shows another example of the configuration of the printing apparatus 100. In this configuration example, multiple cleaning devices 510 are provided. As described above, each of these multiple cleaning devices 510 is supported by a rotating member 210. These multiple cleaning devices 510 are installed such that the positions of the multiple mandrels 230M are offset from each other in the direction of movement.

[0098] In this configuration example, two cleaning devices 510 are installed adjacent to each other. The mandrel 230M is not located between the two cleaning devices 510. The number of cleaning devices 510 may be three or more. Furthermore, the mandrel 230M may be positioned between the cleaning devices 510. Furthermore, a moving mechanism 520, as shown in Figure 10, may be provided in conjunction with the cleaning device 510. Alternatively, the configuration may be made without this moving mechanism 520.

[0099] In this configuration example shown in Figure 11, the function of one cleaning device 510 included in the multiple cleaning devices 510 differs from the function of the other cleaning devices 510. One cleaning device 510 is provided, which is a downstream cleaning device 511 located on the downstream side in the rotational direction of the rotating member 210. Another cleaning device 510 is provided, which is an upstream cleaning device 512 located on the upstream side in the rotational direction of the rotating member 210. The downstream cleaning device 511 sprays cleaning solution onto the inkjet head 260. The upstream cleaning device 512 sprays a gas such as air onto the inkjet head 260.

[0100] In this configuration example, first, a cleaning solution is sprayed onto the first inkjet head 261 by the downstream cleaning device 511. Next, a gas is sprayed onto the first inkjet head 261 by the upstream cleaning device 512. Subsequently, in this embodiment, the downstream cleaning device 511 and the upstream cleaning device 512 pass sequentially below each of the second inkjet heads 262 to the sixth inkjet heads 266. As a result, cleaning solution is also sprayed onto the second inkjet head 262 to the sixth inkjet head 266. In addition, gas is also sprayed onto the second inkjet head 262 to the sixth inkjet head 266.

[0101] 〔others〕 In the above, we described configurations in which the mandrel 230M circulates around a rotation center along the vertical direction, and in which a large gap 78 is provided or a cleaning device 510 is installed. The embodiments described above may also be applied to a printing apparatus in which the mandrel 230M circulates around a center of rotation along a direction intersecting the vertical direction. More specifically, the embodiments described above may be applied, for example, to a printing apparatus in which the mandrel 230M circulates around a rotation center along the horizontal direction.

[0102] Figure 12 shows a printing apparatus 100 in which the mandrel 230M circulates around a center of rotation along a direction intersecting the vertical direction. Note that the can body 10 is not shown in Figure 12. In this printing apparatus 100, the mandrel 230M and the can body 10 are arranged, for example, along the horizontal direction. Furthermore, in this printing apparatus 100, the mandrel 230M and the can body 10 are arranged along a direction perpendicular to the direction of movement of the mandrel 230M and the can body 10.

[0103] Furthermore, in this printing apparatus 100, the inkjet head 260 is positioned above the circulation path R100 on which the can body 10 moves. Furthermore, the inkjet head 260 is positioned along a direction perpendicular to the direction of movement of the mandrel 230M and the can body 10. In a printing apparatus 100 with such a configuration, the same configuration as described above may also be adopted. In other words, a configuration that includes providing a large gap 78 or installing a cleaning device 510 may be adopted.

[0104] Here, in the configuration examples shown in Figures 1 to 8 above, as an example of processing, we have explained the case in which the control unit 60 shown in Figure 2 positions a large gap 78 at each opposing point on the inkjet head 260. Then, in the configuration examples shown in Figures 1 to 8, as described above, this large gap 78 is used to perform processing on the inkjet head 260. Modes used when processing the inkjet head 260 include image formation mode and processing mode. In this embodiment, the mode is switched based on instructions from the operator.

[0105] In the treatment mode, which is a dedicated mode for treating the inkjet head 260, it is preferable to make the stop time of the mandrel 230M longer than the stop time in the image formation mode, which is the mode for forming an image on the can body 10. Specifically, when a large gap 78 is positioned opposite the inkjet head 260, it is preferable to make the stop time of the mandrel 230M longer than the stop time during image formation mode. When cleaning or other procedures are performed by an operator or the cleaning device 510 shown in Figure 6, if the downtime of the mandrel 230M is short, it becomes difficult to secure enough time for the procedures. In contrast, a longer stopping time for the Mandrel 230M makes it easier to secure time for treatment.

[0106] However, this does not preclude the possibility of performing an action on the inkjet head 260 during image formation mode. Even during image formation mode, the large gap 78 located at each opposing position of the inkjet head 260 may be used to perform an action on the inkjet head 260. If the processing time is short, it may be possible to perform processing on the inkjet head 260 even in image formation mode. Furthermore, even in image formation mode, if the stopping time of the mandrel 230M is inherently long, it may be possible to perform actions on the inkjet head 260.

[0107] Furthermore, two treatment modes may be provided: an automatic treatment mode in which multiple mandrels 230M move automatically, and a manual treatment mode in which multiple mandrels 230M move in response to instructions from the operator. In automatic processing mode, for example, at predetermined intervals, multiple mandrels 230M are moved automatically so that the larger gaps 78 move below each of the inkjet heads 260.

[0108] On the other hand, in manual treatment mode, the practitioner inputs information about the treatment via a user interface, such as a touch panel. Specifically, in this case, the operator inputs information about the inkjet head 260 that they wish to treat, among the multiple inkjet heads 260 provided. In response, the control unit 60 moves the mandrel 230M to position a large gap 78 below the inkjet head 260 that the operator wishes to treat.

[0109] Alternatively, in manual operation mode, the operator presses and holds a button on the user interface, causing the mandrel 230M to move while the button is being held down. In this case, the operator releases the button when a large gap 78 is positioned below the inkjet head 260 as desired by the operator. Subsequently, in this case, the operator performs treatment on the inkjet head 260 located above the large gap 78, either by themselves or by instructing the cleaning device 510 shown in Figure 6. Subsequently, if the operator wishes to perform further operations on other inkjet heads 260, the operator performs further operations on the user interface. This results in a larger gap 78 being positioned below these other inkjet heads 260.

[0110] Even in manual operation mode, depending on the information entered by the operator, the large gap 78 will be positioned sequentially below each of the first inkjet heads 261 to the sixth inkjet heads 266. Furthermore, in manual treatment mode, it is conceivable that, for example, the operator may wish to treat only some of the inkjet heads 260. In this case, depending on the operator's actions, the mandrel 230M will not stop even if a large gap 78 is located below the other inkjet heads 260. In this case, the mandrel 230M stops when a large gap 78 is located below some of the inkjet heads 260 that the operator wishes to treat.

[0111] Furthermore, in the automatic processing mode, one of the processing modes, for example, the large gap 78 is positioned sequentially below each of the first inkjet heads 261 to the sixth inkjet heads 266. Incidentally, this is not the only option; in automatic processing mode, the larger gaps 78 may be positioned below each of the multiple inkjet heads 260 in a different order than this one.

[0112] Furthermore, even if the mandrel 230M stops while the large gap 78 is located below the inkjet head 260, it does not necessarily mean that the inkjet head 260 will be treated. Regardless of whether it is image formation mode, automatic processing mode, or manual processing mode, processing is not guaranteed to be performed on the inkjet head 260 located above the large gap 78. It is conceivable that the operator may not want treatment to be performed on the inkjet head 260, which is located above the large gap 78. In this case, no treatment will be performed on the inkjet head 260. Treatment of the inkjet head 260 will be performed as needed.

[0113] Figures 9-11 illustrate the case where the cleaning device 510 passes through each of the first to sixth inkjet heads 261 in order. In the configuration examples shown in Figures 9-11, at least three modes may be provided: an image formation mode, an automatic treatment mode, and a manual treatment mode.

[0114] In the image formation mode, only image formation by the inkjet head 260 may be performed. Alternatively, in the image formation mode, image formation by the inkjet head 260 may be performed, and the inkjet head 260 may also be cleaned by the cleaning device 510. In addition, in automatic treatment mode, for example, the cleaning device 510 sequentially passes through each of the first inkjet heads 261 to the sixth inkjet heads 266, and each of the inkjet heads 260 is cleaned. In addition, in automatic treatment mode, the cleaning device 510 may pass through each of the multiple inkjet heads 260 in a different order than the one described above. In automatic processing mode, image formation by the inkjet head 260 does not occur.

[0115] In manual treatment mode, the operator inputs information about the inkjet head 260 to be cleaned via the user interface. In this case, the control unit 60 controls the movement of the cleaning device 510 to position it below the inkjet head 260 desired by the operator. Alternatively, in manual operation mode, the operator presses and holds a button on the user interface, causing the cleaning device 510 to move while the button is being held down. In this case, the operator releases the button when the cleaning device 510 is positioned below the desired inkjet head 260. As a result, in this case as well, the cleaning device 510 will be positioned below the inkjet head 260 as desired by the operator.

[0116] Even in the configuration examples shown in Figures 9-11, it is not guaranteed that cleaning will be performed on all inkjet heads 260 of the first inkjet head 261 to the sixth inkjet head 266. If the operator does not wish to clean all inkjet heads 260, a situation may arise where some inkjet heads 260 are cleaned while others are not. In the configuration examples shown in Figures 9-11, it is also possible to receive information about the inkjet head 260 that the operator wishes to clean. In this case, the inkjet heads 260 that the operator requests to be cleaned will be cleaned, but the inkjet heads 260 that the operator does not request to be cleaned will not be cleaned. [Explanation of symbols]

[0117] 10...Can body, 60...Control unit, 78...Large gap, 79...Small gap, 100...Printing device, 210...Rotating member, 230M...Mandrel, 260...Inkjet head, 510...Cleaning device, 520...Moving mechanism, R1...Path, R2...Path

Claims

1. Multiple can support members that support the can body and allow it to circulate, An inkjet head that ejects ink onto a can supported by the can support member, Equipped with, A printing apparatus in which the plurality of can body support members are arranged such that the spacing between them is not constant, and large gaps and small gaps exist.

2. The printing apparatus according to claim 1, further comprising control means for stopping the plurality of can support members when the large gap is located opposite the inkjet head.

3. Multiple inkjet heads are provided and arranged in line with the direction of movement of the can support member. The printing apparatus according to claim 2, wherein the control means stops the movement of the plurality of can support members each time the large gap is positioned at the opposing location of each of the plurality of inkjet heads.

4. The printing apparatus according to claim 1, further comprising a cleaning device for cleaning the inkjet head when the large gap is located opposite the inkjet head.

5. The printing apparatus according to claim 4, wherein the cleaning device moves from outside the large gap into the large gap when the large gap is located opposite the inkjet head.

6. The printing apparatus according to claim 1, wherein a plurality of the aforementioned large gaps are provided.

7. Multiple inkjet heads are provided and arranged in line with the direction of movement of the can support member. The printing apparatus according to claim 6, wherein when one large gap is located at the opposing location of one of the inkjet heads, another large gap is located at the opposing location of the other inkjet head.

8. Some of the aforementioned can body support members are missing, The printing apparatus according to claim 1, wherein the large gap is provided due to the absence of some of the can body support members.

9. Multiple can support members that support the can body and allow it to circulate, An inkjet head that ejects ink onto a can supported by the can support member, A cleaning device that performs a circulating movement to clean the inkjet head, A printing device equipped with the following features.

10. Multiple inkjet heads are provided, The printing apparatus according to claim 9, wherein the cleaning device cleans each of the multiple inkjet heads in sequence.

11. The printing apparatus according to claim 9, wherein the cleaning device circulates along a path that is in line with the path through which the plurality of can support members pass.

12. The printing apparatus according to claim 11, wherein the cleaning device is provided in multiple locations, and the positions of the multiple can support members in the direction of movement are offset from each other.

13. The printing apparatus according to claim 9, wherein the cleaning device is provided between two adjacent can support members.

14. The printing apparatus according to claim 12, wherein the function of one cleaning device included in the multiple cleaning devices is different from the function of the other cleaning devices.

15. The printing apparatus according to claim 9, further comprising a mechanism for bringing the cleaning device, which has stopped at a position opposite the inkjet head, closer to the inkjet head, and / or bringing the inkjet head closer to the cleaning device.

16. The printing apparatus according to claim 9, wherein the plurality of can support members that perform circulating movement and the cleaning device that performs circulating movement are supported by a common rotating member.

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