Printer

Abstract

To reduce oscillation of a can body support member that supports a can body.SOLUTION: In a state shown in (A), a transmission member 50 rotates at a rotational speed T. In the state shown in (B), a state at the time when the rotation of a rotating member is performed is illustrated. When the rotation of the rotating member is performed, a control unit changes the rotational speed of the transmission member 50. The control unit controls a second motor to change the rotational speed of the transmission member 50. More specifically, when the rotating member rotates and a mandrel 230M moves, the control unit reduces the rotational speed of the transmission member 50 to set the rotational speed of the transmission member 50 to a rotational speed S which is lower than the rotational speed T.SELECTED DRAWING: Figure 6

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a printing apparatus having a mandrel wheel, a plurality of rotatable mandrels provided on the mandrel wheel, and an inkjet printing station that forms a printed image on at least the body portion of the outer surface of a cylindrical container attached to the mandrel by inkjet printing.

Prior Art Documents

Patent Documents

[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, image formation on the can body may be performed while the can body is supported by a rotating can body support member. Here, when the rotational speed of the can body support member fluctuates, the can body support member is likely to sway, which easily leads to a deterioration in the quality of the formed image. Also, if image formation on the can body is performed after waiting for this sway to subside, the efficiency of image formation on the can body decreases. An object of the present invention is to reduce the sway of a can body support member that supports a can body.

Means for Solving the Problems

[0005] The printing apparatus to which the present invention is applied includes a rotating member that rotates, a plurality of can body support members that are supported by the rotating member and are provided at a location deviated from the rotation center of the rotating member and support the can body, a plurality of image forming means for forming an image on the can body supported by the can body support members, a transmission member that is arranged coaxially with the rotating member and is connected to the plurality of can body support members, rotates, and transmits a rotational driving force to each of the plurality of can body support members, and rotation control means for controlling the rotation of the transmission member, the rotation control means being configured to change the rotation speed of the transmission member when the rotating member rotates.

[0006] Here, the rotation control means may change the rotation speed of the transmission member when the can body support member moves from one image forming means to another image forming means as the rotating member rotates. Further, when the can body support member moves with the rotation of the rotating member in a state where the rotation speed of the transmission member does not change, the relative movement amount of the can body support member that relatively moves with respect to the transmission member increases, the rotation speed of the can body support member increases, and the rotation control means changes the rotation speed of the transmission member so that the increase in the rotation speed of the can body support member is suppressed as compared with the case where the rotation speed of the transmission member does not change. Further, when the can body support member moves with the rotation of the rotating member in a state where the rotation speed of the transmission member does not change, the relative movement amount of the can body support member that relatively moves with respect to the transmission member decreases, the rotation speed of the can body support member decreases, and the rotation control means changes the rotation speed of the transmission member so that the decrease in the rotation speed of the can body support member is suppressed as compared with the case where the rotation speed of the transmission member does not change. Further, the rotation control means may change the rotation speed of the transmission member so that the rotation speed of the can body support member when the rotating member is not rotating substantially coincides with the rotation speed of the can body support member when the rotating member is rotating. Further, the transmission member may rotate in a direction opposite to the rotation direction of the rotating member, and the rotation control means may reduce the rotation speed of the transmission member when the rotating member rotates. Further, the transmission member may rotate in the same direction as the rotation direction of the rotating member, and the rotation control means may increase the rotation speed of the transmission member when the rotating member rotates. Further, the plurality of can body support members may be arranged radially around the rotation center of the rotating member, and the plurality of image forming means may be arranged radially around the rotation center of the rotating member.

Advantages of the Invention

[0007] According to the present invention, it is possible to reduce the shaking of the can body support member that supports the can body.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a view of the printing apparatus 100 according to the present embodiment as viewed from above. FIG. 2 is a cross-sectional view of the printing apparatus 100 taken along line II-II of FIG. 1. In FIG. 1, the transmission member 50 shown in FIG. 2 is indicated by a broken line. The printing apparatus 100 of the present embodiment 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.

[0010] As shown in FIG. 2, the printing apparatus 100 is provided with a control unit 60 that controls each device and each mechanism provided in the printing apparatus 100. Further, as shown in FIG. 1, the printing apparatus 100 is provided with a rotating member 210 that is driven by a first motor M1 (see FIG. 2) and rotates intermittently in the direction indicated by arrow 1A in the figure. The rotating member 210 is formed in a disk shape and rotates about the rotation center 1E shown in FIG. 1. This rotation center 1E extends in the vertical direction.

[0011] Inside the housing 290 shown in FIG. 2, a rotation mechanism (not shown) is provided. This rotation mechanism is configured by a known mechanism such as a gear or a cam, and rotates the rotating member 210 by receiving the force from the first motor M1. In this embodiment, a rotation mechanism is provided around a rotating member 59 (details will be described later).

[0012] FIG. 3 is a diagram showing the hardware configuration of the control unit 60. The control unit 60 is provided with a processing unit 901 and an information storage device 902 that stores information. The processing unit 901 is constituted by a computer. The processing unit 901 has a CPU (= Central Processing Unit) 911 as an example of a processor. Further, the processing unit 901 has a ROM (= Read Only Memory) 912 in which a program is stored and a RAM (= Random Access Memory) 913 used as a work area. The information storage device 902 is realized by an existing device such as a hard disk drive, a semiconductor memory, or a magnetic tape. The processing unit 901 and the information storage device 902 are connected through a bus 906 and signal lines (not shown).

[0013] The program executed by the CPU 911 can be provided to the control unit 60 in a state of being stored in a computer-readable recording medium such as a magnetic recording medium (magnetic tape, magnetic disk, etc.), an optical recording medium (optical disk, etc.), a magneto-optical recording medium, or a semiconductor memory. Further, 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 the programs stored in the ROM 912 and the information storage device 902, thereby controlling each device and each mechanism provided in the printing apparatus 100.

[0014] With reference to FIG. 1, the printing apparatus 100 will be further described. The printing apparatus 100 is provided with a plurality (16 in this embodiment) of holding mechanisms 230 that hold the can body 10. In this embodiment, the number of the holding mechanisms 230 is 16, but it may be appropriately designed, and the number of the holding mechanisms 230 may be other than 16. As shown by reference numeral 1X, each of the holding mechanisms 230 is provided with a shaft 230S that is rotatably supported by a rotating member 210. This shaft 230S is capable of rotating in the circumferential direction.

[0015] Also, as shown by reference numeral 1X, each of the holding mechanisms 230 is provided with a mandrel 230M as an example of a can body support member that supports the can body 10. This 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. Also, the mandrel 230M is provided at a location offset from the rotation center 1E of the rotating member 210.

[0016] At the other end of the shaft 230S, a receiving gear 230G is provided as an example of a receiving member that receives a rotational driving force. The receiving gear 230G is constituted by a helical gear. The receiving gear 230G meshes with the transmission member 50 and receives a rotational driving force from this transmission member 50. In the present embodiment, as shown in FIG. 2, a gear portion 50G provided along the circumferential direction of the transmission member 50 is provided on the outer peripheral portion of the transmission member 50. The receiving gear 230G meshes with this gear portion 50G provided on the outer peripheral portion of the transmission member 50 and receives a rotational driving force from this gear portion 50G.

[0017] A plurality of shafts 230S and mandrels 230M are provided, and these shafts 230S and mandrels 230M are radially arranged around the arrangement center 1C indicated by reference numeral 1C in FIG. 1. In other words, the shafts 230S and mandrels 230M are radially arranged around the rotation center 1E of the rotating member 210. The arrangement center 1C coincides with the rotation center 1E of the rotating member 210.

[0018] The can body 10 is formed in a cylindrical shape. Also, the can body 10 has a bottom formed at one end in the longitudinal direction, and this one end is closed. On the other hand, the other end of the can body 10 is not closed and is open. Support of the can body 10 by the mandrel 230M is performed by inserting the mandrel 230M into the inside of the can body 10 from this open side, as shown by the arrow 1G in FIG. 1.

[0019] As shown in FIG. 2, in the present embodiment, a disk-shaped transmission member 50 is provided above the receiving gear 230G. As described above, the transmission member 50 meshes with the receiving gears 230G provided in each of the holding mechanisms 230, transmits a rotational driving force to the receiving gears 230G, and rotates the mandrel 230M. Note that the transmission member 50 is not limited to being disposed above the receiving gear 230G, and may be disposed below the receiving gear 230G.

[0020] The transmission member 50 is disposed coaxially with the rotating member 210. In other words, in the present embodiment, the rotation center 1F of the transmission member 50 is located on the extension line of the rotation center 1E (see FIG. 1) of the rotating member 210. Also, the transmission member 50 is connected to a plurality of mandrels 230M. More specifically, the transmission member 50 is connected to a plurality of mandrels 230M via the receiving gears 230G and the shafts 230S. The transmission member 50 rotates and transmits a rotational driving force to each of the plurality of mandrels 230M.

[0021] The transmission member 50 receives a rotational driving force from a columnar rotating member 59 (see FIG. 2) extending downward from the rotation center (central portion in the radial direction) of the transmission member 50, rotates, and transmits a rotational driving force to each of the plurality of mandrels 230M. In the present embodiment, as shown in FIG. 2, a second motor M2 for rotating the rotating member 59 is provided, and the rotating member 59 rotates by receiving a driving force from this second motor M2.

[0022] The transmission member 50 rotates in the direction indicated by the arrow 1D in FIG. 1. And in this embodiment, the receiving gear 230G is engaged with the rotating transmission member 50, whereby the receiving gear 230G rotates and the mandrel 230M (cylinder body 10) rotates in the direction indicated by the arrow 1M. In this embodiment, the transmission member 50 rotates in a direction opposite to the direction indicated by the arrow 1A which is the rotation direction of the rotating member 210. The transmission member 50 rotates about a rotation center 1F located at the central portion in the radial direction of the transmission member 50. In this embodiment, the rotation center 1F coincides with the arrangement center 1C of the radially arranged mandrels 230M.

[0023] In this embodiment, as shown in FIG. 1, when the printing apparatus 100 is viewed from above, the rotation center 1F and the arrangement center 1C are located at the same position. Further, the rotation center 1E of the rotating member 210 is also located at the position where the rotation center 1F and the arrangement center 1C are located. Furthermore, in this embodiment, the transmission member 50 is located closer to the arrangement center 1C side than the radially arranged mandrels 230M.

[0024] Also, as shown in FIG. 1, the printing apparatus 100 is provided with six inkjet heads 260 that function as image forming means. Specifically, in this embodiment, six inkjet heads 260, namely, the first inkjet head 261 to the sixth inkjet head 266, are provided. Note that in this embodiment, a case where an inkjet head is used as an example of the image forming means will be described, but the image forming means is not limited to an inkjet head, and other means for forming an image using other methods may be used.

[0025] The six inkjet heads 260 form an image on the cylinder body 10 supported by the mandrel 230M. The six inkjet heads 260 are arranged side by side in the moving direction on the cylinder body 10. In other words, the six inkjet heads 260 are arranged side by side along the rotation direction of the rotating member 210. Furthermore, the six inkjet heads 260 are radially arranged around the rotation center 1E of the rotating member 210. Also, as shown in FIG. 2, the inkjet heads 260 are arranged above the can body 10 and eject ink toward the can body 10 located below. The inkjet head 260 has a lower surface 241 facing the can body 10, and a plurality of ink ejection ports (not shown) for ejecting ink are provided on this lower surface 241.

[0026] Each of the inkjet heads 260 ejects an ultraviolet-curable ink to form an image on the outer peripheral surface of the can body 10. In this embodiment, the ultraviolet-curable ink is used in this way, but not limited to using the ultraviolet-curable ink, and a heat-curable ink may also be used. Also, each of the inkjet heads 260 ejects different inks such as yellow, magenta, cyan, black, white, and special colors to the can body 10.

[0027] Also, as shown in FIG. 1, in this embodiment, in the rotation direction of the rotating member 210 (the conveyance direction of the can body 10), a UVLED (Ultraviolet Light Emitting Diode) lamp 250 that functions as a light irradiation means is provided on the downstream side of the six inkjet heads 260. In this embodiment, ultraviolet rays are irradiated from the UVLED lamp 250 to the outer peripheral surface of the can body 10. Thereby, the ultraviolet-curable ink constituting the image on the outer peripheral surface of the can body 10 is cured.

[0028] Furthermore, in this embodiment, a lamp housing box 70 for housing the UVLED lamp 250 is provided. By providing this lamp housing box 70, the irradiation of ultraviolet rays to other than the can body 10 is suppressed. The lamp housing box 70 is provided with an inlet portion 71 through which the mandrel 230M (can body 10) passes when entering the lamp housing box 70, and an outlet portion 72 through which the mandrel 230M passes when exiting the lamp housing box 70.

[0029] The rotating member 210 moves the mandrel 230M (cylinder body 10) via each of a plurality of provided inkjet heads 260. Further, each time the rotating member 210 rotates, the rotation is once stopped. In the present embodiment, a total of 16 mandrel stop positions (cylinder body stop positions) 801 to 816 are provided, and at each of these mandrel stop positions 801 to 816, the mandrel 230M (cylinder body 10) stops. In the present embodiment, the rotating member 210 is intermittently rotated to convey the cylinder body 10 along a predetermined circumferential path, and each time the cylinder body 10 reaches each of the 16 mandrel stop positions, the cylinder body 10 is once stopped. In other words, in the present embodiment, the rotating member 210 is intermittently rotated to revolve the cylinder body 10, and each time the cylinder body 10 reaches each of the 16 mandrel stop positions, the cylinder body 10 is once stopped.

[0030] In the present embodiment, inkjet heads 260 are provided at six mandrel stop positions 804 to 809 out of the 16 mandrel stop positions 801 to 816, and further, a UVLED lamp 250 is provided at another mandrel stop position 811. Further, in the present embodiment, between the mandrel stop positions 804 to 809 where the inkjet heads 260 are installed (hereinafter sometimes referred to as "image formation stop positions 804 to 809") and the mandrel stop position 811 where the UVLED lamp 250 is installed (hereinafter sometimes referred to as "light irradiation stop position 811"), another mandrel stop position (the mandrel stop position indicated by reference numeral 810) is provided.

[0031] In the present embodiment, ultraviolet rays are emitted from the UVLED lamp 250, but if this ultraviolet ray reaches the inkjet head 260 located on the upstream side, the ink may harden at the inkjet head 260, and there is a risk of ink clogging or a decrease in the quality of the formed image. Therefore, in the present embodiment, as described above, one mandrel stop position 810 is provided between the image formation stop positions 804 to 809 and the light irradiation stop position 811, increasing the separation distance between the UVLED lamp 250 and the inkjet head 260. As a result, the ultraviolet rays reaching the inkjet head 260 are reduced. In the present embodiment, one mandrel stop position 810 is provided between the image formation stop positions 804 to 809 and the light irradiation stop position 811, but two or more mandrel stop positions may be provided.

[0032] Furthermore, in the printing apparatus 100 of the present embodiment, as shown in FIG. 1, a can body input section 91 is provided upstream of the plurality of inkjet heads 260. In the can body input section 91, the inside of the mandrel 230M formed in a cylindrical shape is set to a negative pressure, and the mandrel 230M sucks the can body 10, causing the mandrel 230M to enter the inside of the can body 10. As a result, the support of the can body 10 by the mandrel 230M is started.

[0033] An inspection mechanism 92, which is an example of inspection means for inspecting the input can body 10, is provided between the can body input section 91 and the inkjet head 260. In the present embodiment, the inspection mechanism 92 is provided upstream of the inkjet head 260, and the can body 10 is inspected before image formation by the inkjet head 260.

[0034] Specifically, the inspection mechanism 92 inspects whether the can body 10 is deformed or not. More specifically, as shown in FIG. 4 (a view of the inspection mechanism 92 as seen from the direction of arrow IV in FIG. 1), the inspection mechanism 92 is provided with a light source 92A that emits a laser beam traveling along the outer peripheral surface of the can body 10 and along the axial direction of the can body 10 on one end side of the can body 10. Furthermore, a light receiving portion 92B for receiving the laser beam from the light source 92A is provided on the other end side of the can body 10.

[0035] When a part of the can body 10 is deformed as shown by reference numeral 3A, the laser light is blocked, and the light-receiving unit 92B will not receive the laser light. Thus, the deformation of the can body 10 is detected. In this embodiment, when the inspection mechanism 92 determines that the can body 10 does not meet the predetermined conditions (when it is determined that the can body 10 is deformed), a discharge mechanism 93 (see FIG. 1), which is an example of the discharge means, discharges this can body 10 to the outside of the printing apparatus 100.

[0036] As shown in FIG. 1, the discharge mechanism 93 is disposed between the inspection mechanism 92 and the inkjet head 260 (it is disposed upstream of the inkjet head 260). Therefore, in this embodiment, the can body 10 is discharged before the image formation by the inkjet head 260. In the discharge mechanism 93, compressed air is supplied into the mandrel 230M, and the can body 10 moves in the direction indicated by the arrow 1H in the figure. Further, the bottom portion (the end on the closed side) of the can body 10 is sucked by a suction member (not shown). Then, the can body 10 is conveyed to the outside of the printing apparatus 100 by this suction member, and the can body 10 is discharged to the outside of the printing apparatus 100.

[0037] Referring to FIG. 1, the printing apparatus 100 will be further described. A paint application device 94 is provided downstream of the UVLED lamp 250 (at the mandrel stop position 813). The paint application device 94 has a rotating body (not shown) on whose outer peripheral surface the paint is placed, and the outer peripheral surface of this rotating body is brought into contact with the outer peripheral surface of the can body 10 to apply the paint to the outer periphery of the can body 10. By applying the paint, a protective layer is formed on the outer peripheral surface of the can body 10.

[0038] Thereafter, in this embodiment, the can body 10 is discharged at the can body discharge portion 95 downstream of the paint application device 94 (at the mandrel stop position 815). Specifically, by supplying compressed air into the mandrel 230M, the can body 10 is removed from the mandrel 230M, and further, the can body 10 is conveyed to the outside of the printing device 100 by a conveying mechanism (not shown). The can body 10 conveyed to the outside of the printing device 100 is conveyed to a baking process (not shown) and is subjected to heat treatment.

[0039] Referring to FIG. 1, a series of operations of the printing device 100 will be described. When printing with the printing device 100, first, the rotation of the transmission member 50 in the direction indicated by the arrow 1D is started, and the rotation of the mandrel 230M in the direction indicated by the arrow 1M is started. In the present embodiment, the transmission member 50 rotates constantly. Also, in the present embodiment, as will be described later, when the rotating member 210 rotates, the rotation speed of the transmission member 50 changes.

[0040] In the present embodiment, at the can body loading section 91, the can body 10 conveyed from the upstream side is attached to the mandrel 230M. Specifically, in the present embodiment, the can body 10 is conveyed to the can body loading section 91 from the upstream side. At this time, an empty mandrel 230M is waiting at the can body loading section 91. Further, the inside of the mandrel 230M is set to negative pressure, and the can body 10 is sucked by the mandrel 230M. Thereby, the mandrel 230M enters the inside of the can body 10, and the support of the can body 10 by the mandrel 230M is started.

[0041] After the support of the can body 10 by the mandrel 230M is started, the rotating member 210 that was in a stopped state rotates by a predetermined angle in the direction indicated by the arrow 1A in the figure and stops again. Thereby, the can body 10 reaches the inspection mechanism 92. In other words, in this case, the can body 10 revolves and the can body 10 reaches the inspection mechanism 92. Thereafter, the rotating member 210 rotates again by a predetermined angle. As a result, the can body 10 revolves, and the can body 10 reaches the discharging mechanism 93. Thereafter, the rotating member 210 rotates again by a predetermined angle. As a result, the can body 10 revolves, and the can body 10 reaches below the first inkjet head 261 which is the first one of the inkjet heads 260.

[0042] Then, ink is ejected from this first first inkjet head 261 toward the can body 10 which is positioned below and rotating, and an image with the first color ink is formed on the outer peripheral surface of the can body 10. In other words, ink is ejected from the first inkjet head 261 toward the rotating can body 10, and an image with the first color ink is formed on the outer peripheral surface of the can body 10. Thereafter, in the present embodiment, the rotation and stop of the rotating member 210 are performed again, and the can body 10 stops below the second inkjet head 262 which is the second one of the inkjet heads 260. In other words, the revolution and stop of the can body 10 are performed, and the can body 10 stops below the second inkjet head 262 which is the second inkjet head 260. And an image with the second color ink is formed by this second inkjet head 262.

[0043] Thereafter, in the present embodiment, the movement of the can body 10 to the third inkjet head 263, the formation of an image by the third inkjet head 263, the movement of the can body 10 to the fourth inkjet head 264, and the formation of an image by the fourth inkjet head 264 are performed. Further, images are similarly formed by the fifth inkjet head 265 and the sixth inkjet head 266. In addition, in the present embodiment, the case where images are formed using all six inkjet heads 260 has been described as an example, but images may be formed using some of the six inkjet heads 260.

[0044] In this embodiment, when the can body 10 moves between the inkjet heads 260, the transmission member 50 rotates, and thereby, the can body 10 rotates. When the can body 10 rotates, uneven adhesion of the ink is less likely to occur. In other words, in this embodiment, when the can body 10 revolves, the transmission member 50 rotates, and thereby, the can body 10 rotates on its own axis. When the can body 10 rotates on its own axis, uneven adhesion of the ink is less likely to occur. When the can body 10 is moved in a state where the rotation of the can body 10 is stopped, the ink adhering to the can body 10 may move downward due to gravity, and uneven adhesion of the ink may occur. In other words, when the can body 10 is revolved in a state where the can body 10 does not rotate on its own axis, the ink adhering to the can body 10 may move downward due to gravity, and uneven adhesion of the ink may occur.

[0045] The can body 10 that has passed through the inkjet head 260 moves below the UVLED lamp 250, and ultraviolet rays are irradiated onto the outer peripheral surface of the can body 10. Thereby, the ink on the outer peripheral surface of the can body 10 is cured. Then, paint is applied to the outer peripheral surface of the can body 10 by the paint application device 94. Next, at the can discharging section 95, compressed air is supplied into the mandrel 230M, and the inner surface of the can body 10 mounted on the mandrel 230M is pressed by this compressed air. Thereby, the can body 10 is removed from the mandrel 230M. The can body 10 removed from the mandrel 230M is conveyed to a baking process (not shown), and heat treatment is performed. Thereby, the paint applied to the can body 10 is cured.

[0046] FIG. 5 is a view when the first inkjet head 261, the second inkjet head 262, etc. are viewed from the direction indicated by the arrow V in FIG. 1. Note that in FIG. 5, the display is in a simplified form. When viewing the first inkjet head 261, the second inkjet head 262, etc. from the direction indicated by the arrow V in FIG. 1, as going in the depth direction of the paper surface of FIG. 5, the first inkjet head 261, the second inkjet head 262, etc. move away from each other. However, in FIG. 5, the display is in a simplified form, and the first inkjet head 261 and the second inkjet head 262 are shown in a parallel form.

[0047] Also, in FIG. 5, the state is shown when the rotating member 210 (not shown in FIG. 5) is not rotating and the mandrel 230M is not moving. Also, in FIG. 5, the illustration of the mandrel 230M located below the second inkjet head 262 and the receiving gear 230G interlocked with this mandrel 230M is omitted.

[0048] In the present embodiment, as described above, the transmission member 50 rotates in the counterclockwise direction as indicated by the arrow 1D in FIG. 1. In this case, at the location where the first inkjet head 261 is provided, as shown in FIG. 5, the transmission member 50 moves in the direction indicated by the arrow 5A. Thereby, in the present embodiment, the receiving gear 230G rotates in the counterclockwise direction. Also, in the present embodiment, when the rotating member 210 is not rotating, the rotation speed of the transmission member 50 is the rotation speed T. In FIG. 5, the rotation direction of the rotating member 210 (not shown in FIG. 5) is the direction indicated by the arrow 5B, and the rotating member 210 rotates in the direction opposite to the rotation direction of the transmission member 50.

[0049] FIGS. 6(A) to (C) are diagrams showing the states of respective parts when the rotating member 210 (not shown in FIG. 6) rotates and the mandrel 230M moves from the first inkjet head 261, which is an example of one image forming means, to the second inkjet head 262, which is an example of the other image forming means. In other words, FIGS. 6(A) to 6(C) are diagrams showing the states of respective parts when the rotating member 210 rotates and the mandrel 230M moves from the first inkjet head 261 to the second inkjet head 262 located on the downstream side of the first inkjet head 261 by one position.

[0050] The state shown in FIG. 6(A) is the same as the state shown in FIG. 5, the rotation of the rotating member 210 is not performed, and the transmission member 50 is rotating at the rotation speed T. FIG. 6(B) shows the state when the rotating member 210 rotates. In the present embodiment, when the rotating member 210 rotates, the control unit 60 (see FIG. 2), which is an example of the rotation control means, changes the rotation speed of the transmission member 50. Specifically, the control unit 60 controls the second motor M2 (see FIG. 2) to change the rotation speed of the transmission member 50.

[0051] The control unit 60 changes the rotation speed of the transmission member 50 when the rotating member 210 rotates and the mandrel 230M moves from the first inkjet head 261 to the second inkjet head 262. Specifically, as shown in FIG. 6(B), when the rotating member 210 rotates and the mandrel 230M moves, the control unit 60 decreases the rotation speed of the transmission member 50 to a rotation speed S that is smaller than the above rotation speed T.

[0052] Thereby, in the present embodiment, an increase in the rotation speed of the mandrel 230M can be suppressed as compared with the case where the rotation speed of the transmission member 50 is not decreased. Here, the process when the mandrel 230M moves from the first inkjet head 261 to the second inkjet head 262 is described. However, the same process is also performed when the mandrel 230M moves from another inkjet head to an inkjet head located on the downstream side of the other inkjet head by one position.

[0053] Here, as shown in FIG. 7 (a diagram for explaining the rotation speed of the mandrel 230M), assume a case where the mandrel 230M moves as the rotating member 210 rotates without a change in the rotation speed of the transmission member 50. In other words, assume a case where the rotation speed of the transmission member 50 remains at the rotation speed T and the mandrel 230M moves. In this case, the relative movement amount of the mandrel 230M that relatively moves with respect to the transmission member 50 increases, and the rotation speed of the mandrel 230M increases.

[0054] In the present embodiment, in a state where the rotating member 210 does not rotate and only the transmission member 50 rotates, the mandrel 230M is configured to relatively move with respect to the rotating transmission member 50. As shown in FIG. 7, when the mandrel 230M moves as the rotating member 210 rotates without a change in the rotation speed of the transmission member 50, the relative movement amount of the mandrel 230M with respect to the transmission member 50 increases. In this case, the rotation speed of the mandrel 230M increases compared to before the rotating member 210 rotates.

[0055] On the other hand, as shown in FIG. 6(B), if the rotation speed of the transmission member 50 is set to a rotation speed S smaller than the rotation speed T and made smaller than the rotation speed T before the rotation of the rotating member 210, an increase in the rotation speed of the mandrel 230M can be suppressed. In the present embodiment, when the rotating member 210 rotates, the control unit 60 performs a process of changing the rotation speed of the transmission member 50 so that an increase in the rotation speed of the mandrel 230M is suppressed compared to the case where no change occurs in the rotation speed of the transmission member 50.

[0056] It is more preferable to change the rotation speed of the transmission member 50 so that the rotation speed of the mandrel 230M when the rotating member 210 is not rotating and the rotation speed of the mandrel 230M when the rotating member 210 is rotating are substantially the same. In this case, the control unit 60 changes the rotational speed of the transmission member 50 so that the rotational speed of the mandrel 230M when the rotating member 210 is not rotating substantially coincides with the rotational speed of the mandrel 230M when the rotating member 210 is rotating.

[0057] FIG. 8 is a diagram showing the rotational speed of the transmission member 50 when changing the rotational speed of the transmission member 50 so that the rotational speed of the mandrel 230M when the rotating member 210 is not rotating substantially coincides with the rotational speed of the mandrel 230M when the rotating member 210 is rotating. In this example shown in FIG. 8, the rotational speed of the transmission member 50 gradually decreases as the rotational speed (peripheral speed) of the rotating member 210 increases. Then, at the timing indicated by reference sign 8A when the rotational speed of the rotating member 210 is the highest, the rotational speed of the transmission member 50 becomes the lowest.

[0058] Thereafter, the rotational speed of the transmission member 50 gradually increases as the rotational speed (peripheral speed) of the rotating member 210 decreases, and when the rotational speed of the rotating member 210 becomes zero, it becomes the rotational speed T which is the initial rotational speed. In this case, the mandrel 230M that rotates at a constant rotational speed in a stationary state moves while maintaining this constant rotational speed so as to reach the downstream second inkjet head 262.

[0059] When changing the rotational speed of the transmission member 50 as in the present embodiment, fluctuations in the rotational speed of the mandrel 230M are suppressed, and the mandrel 230M is less likely to shake. Here, when the rotational speed of the transmission member 50 does not change, when the rotating member 210 rotates and the mandrel 230M moves, as shown in FIG. 7, the rotational speed of the mandrel 230M increases. And in this case, when the rotation of the rotating member 210 stops and the mandrel 230M reaches the second inkjet head 262 shown in FIG. 7, the rotational speed of the mandrel 230M rapidly decreases and returns to the original rotational speed. At this time, the mandrel 230M is likely to shake.

[0060] In this case, with the second inkjet head 262, a situation may occur where image formation starts while the mandrel 230M is vibrating, which easily leads to a deterioration in the quality of the formed image. Also, if image formation on the can body 10 is performed after waiting for this vibration to subside, the efficiency of image formation on the can body 10 decreases. On the other hand, as in this embodiment, when the rotation speed of the transmission member 50 is decreased, the degree of decrease in the rotation speed of the mandrel 230M when the mandrel 230M reaches the second inkjet head 262 becomes smaller.

[0061] In this case, the vibration of the mandrel 230M when the mandrel 230M reaches the second inkjet head 262 becomes smaller. And in this case, a decrease in the quality of the formed image is less likely to occur, and a decrease in the efficiency of image formation can be suppressed. Here, as described above, when changing the rotation speed of the transmission member 50 so that the rotation speed of the mandrel 230M when the rotating member 210 is not rotating and the rotation speed of the mandrel 230M when the rotating member 210 is rotating are substantially the same, the vibration of the mandrel 230M becomes even smaller.

[0062] In the processing example shown in FIG. 8, as described above, the rotation speed of the transmission member 50 gradually decreases, and then the rotation speed of the transmission member 50 gradually increases. The mode of decrease in the rotation speed of the transmission member 50 is not limited to this, and the rotation speed after the decrease may be a constant value like the above rotation speed S. Also in this case, compared with the case where the rotation speed of the transmission member 50 remains at the rotation speed T without changing, the vibration of the mandrel 230M can be reduced.

[0063] FIG. 9 is a diagram showing another configuration example of the printing apparatus 100. Also in FIG. 9, as in FIG. 5, it shows the state when viewing the first inkjet head 261, the second inkjet head 262, etc. from the direction indicated by the arrow V in FIG. 1. In this configuration example, the transmission member 50 is configured to rotate in the same direction as the rotation direction of the rotating member 210. In this case, when the mandrel 230M moves as the rotating member 210 rotates without a change in the rotational speed of the transmission member 50, the relative movement amount of the mandrel 230M that relatively moves with respect to the transmission member 50 decreases, and the rotational speed of the mandrel 230M decreases.

[0064] On the other hand, in the present embodiment, as shown in FIG. 10 (a diagram showing the rotational speed of the transmission member when the rotating member rotates), when the rotating member 210 rotates, the control unit 60 increases the rotational speed of the transmission member 50 to a rotational speed R that is greater than the rotational speed T. As a result, in this case, compared with the case where no change occurs in the rotational speed of the transmission member 50, a decrease in the rotational speed of the mandrel 230M is suppressed. In this case, the control unit 60 performs a process of changing the rotational speed of the transmission member 50 so that a decrease in the rotational speed of the mandrel 230M is suppressed compared with the case where no change occurs in the rotational speed of the transmission member 50.

[0065] Also in this case, similar to the above, the sway of the mandrel 230M when the rotation of the rotating member 210 stops becomes small. And in this case, similar to the above, a decrease in the quality of the image is suppressed, and a decrease in the efficiency of image formation is also suppressed. Note that, similar to the above, also in the configuration examples shown in FIGS. 9 and 10, the rotational speed of the transmission member 50 may be changed so that the rotational speed of the mandrel 230M when the rotating member 210 is not rotating substantially matches the rotational speed of the mandrel 230M when the rotating member 210 is rotating. In this case, similar to the above, the mandrel 230M that rotates at a constant rotational speed in a stationary state moves while maintaining this constant rotational speed and reaches the second inkjet head 262, which is the downstream inkjet head.

[0066] In the present embodiment, as described above, in the configuration in which the transmission member 50 rotates in the direction opposite to the rotation direction of the rotating member 210, the first aspect in which the rotational speed of the transmission member 50 is decreased when the rotating member 210 rotates has been described. In addition, in the present embodiment, as described above, a second aspect has been described in which when the rotating member 210 rotates, the number of rotations of the transmission member 50 is increased in a configuration where the transmission member 50 rotates in the same direction as the rotation direction of the rotating member 210. Here, in the second aspect, it is necessary to increase the number of rotations of the transmission member 50. In this case, a larger second motor M2 (see FIG. 2) may be required, which tends to increase the cost. On the other hand, in the first aspect, since it is not necessary to increase the number of rotations of the transmission member 50, it is easier to suppress an increase in cost compared to the second aspect.

Explanation of Reference Numerals

[0067] 1E…Rotation center, 10…Can body, 50…Transmission member, 60…Control unit, 100…Printing device, 210…Rotating member, 230M…Mandrel, 260…Inkjet head, 261…First inkjet head, 262…Second inkjet head

Claims

1. A rotating member that rotates; A plurality of can body support members that are supported by the rotating member and are provided at a position offset from the rotation center of the rotating member and support the can body; A plurality of image forming means for forming an image on the can body supported by the can body support member; A transmission member that is arranged coaxially with the rotating member and is connected to the plurality of can body support members, rotates, and transmits a rotational driving force to each of the plurality of can body support members; Rotation control means for controlling the rotation of the transmission member, the rotation control means for changing the rotation speed of the transmission member when the rotating member rotates; A printing apparatus comprising the same.

2. The rotation control means is: When the rotating member rotates and the can body support member moves from one image forming means to another image forming means, the rotation speed of the transmission member is changed. The printing apparatus according to claim 1.

3. When the can body support member moves with the rotation of the rotating member in a state where no change in the rotation speed of the transmission member occurs, the relative movement amount of the can body support member that relatively moves with respect to the transmission member increases, and the rotation speed of the can body support member increases. The rotation control means is: The rotation speed of the transmission member is changed so that an increase in the rotation speed of the can body support member is suppressed as compared with the case where no change in the rotation speed of the transmission member occurs. The printing apparatus according to claim 1.

4. When the can body support member moves with the rotation of the rotating member in a state where no change in the rotation speed of the transmission member occurs, the relative movement amount of the can body support member that relatively moves with respect to the transmission member decreases, and the rotation speed of the can body support member decreases. The rotation control means is: Changing the rotational speed of the transmission member so that a decrease in the rotational speed of the can body support member is suppressed as compared to the case where no change in the rotational speed of the transmission member occurs. The printing apparatus according to claim 1.

5. The rotation control means Changing the rotational speed of the transmission member so that the rotational speed of the can body support member when the rotating member is not rotating substantially coincides with the rotational speed of the can body support member when the rotating member is rotating. The printing apparatus according to claim 1.

6. The transmission member rotates in a direction opposite to the rotational direction of the rotating member. The rotation control means When the rotation of the rotating member is performed, decreasing the rotational speed of the transmission member. The printing apparatus according to claim 1.

7. The transmission member rotates in the same direction as the rotational direction of the rotating member. The rotation control means When the rotation of the rotating member is performed, increasing the rotational speed of the transmission member. The printing apparatus according to claim 1.

8. The plurality of can body support members are arranged radially around the rotation center of the rotating member, and the plurality of image forming means are arranged radially around the rotation center of the rotating member. The printing apparatus according to claim 1.

Images