Printer, container, and production method of beverage container

Abstract

To inhibit deterioration of the quality of an image formed in a diameter reduction part of a beverage container.SOLUTION: As indicated by a reference number 1A and a reference number 1C, the size of a dot image 102 formed in a large outer diameter portion 11X of a diameter reduction part 11 is larger than the size of a dot image 102 formed in a small outer diameter portion 11Y of the diameter reduction part 11. In other words, the diameter of the dot image 102 formed in the large outer diameter portion 11X of the diameter reduction part 11 is larger than the diameter of the dot image 102 formed in the small outer diameter portion 11Y of the diameter reduction part 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a printing device, a container, and a method for manufacturing a beverage container. [Background technology]

[0002] Patent Document 1 discloses a configuration in which a conical drinking cup is rotated by a mandrel that is pushed into the inside of the drinking cup during a printing process on the drinking cup. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2010-522651 Summary of the Invention [Problem to be solved by the invention]

[0004] A cylindrical beverage container may be provided with a tapered portion whose outer diameter decreases in the axial direction of the container. To form an image on the outer peripheral surface of the container, ink may be ejected from an inkjet head into the container to form a plurality of dot images on the surface of the container. Here, the circumferential length of the portion of the reduced diameter section with a larger outer diameter is different from the circumferential length of the portion of the reduced diameter section with a smaller outer diameter. In this case, when ink is ejected at a constant time interval, the spacing between dot images arranged in a row in the circumferential direction of the portion of the reduced diameter section with a larger outer diameter will differ from the spacing between dot images arranged in a row in the circumferential direction of the portion of the reduced diameter section with a smaller outer diameter. In this case, there may be variations in shading in the formed image, which may lead to a deterioration in the quality of the formed image. An object of the present invention is to prevent deterioration in the quality of an image formed on a narrowed portion of a beverage container. [Means for solving the problem]

[0005] The printing device to which the present invention is applicable comprises: a rotating means for rotating a cylindrically shaped beverage container in a circumferential direction, the container having a tapered portion whose outer diameter decreases as it progresses in the axial direction; and an inkjet head arranged along the axial direction of the container and facing the outer peripheral surface of the container, which ejects ink onto the outer peripheral surface of the rotating container to form a plurality of dot images on the outer peripheral surface, and which forms the dot images so that the size of the dot images formed in the large outer diameter portion of the tapered portion, which is the portion with a larger outer diameter, is larger than the size of the dot images formed in the small outer diameter portion of the tapered portion, which is the portion with a smaller outer diameter.

[0006] Here, the dot image formed by ink ejected from a portion of the inkjet head extending from one end to the other in the axial direction of the container that faces the large outer diameter portion may be larger than the dot image formed by ink ejected from a portion of the inkjet head that faces the small outer diameter portion. Furthermore, the ejection frequency of ink ejected from the portion of the inkjet head facing the large outer diameter portion may be greater than the ejection frequency of ink ejected from the portion of the inkjet head facing the small outer diameter portion. Furthermore, the rotation speed of the container when ink is ejected from the portion of the inkjet head facing the large outer diameter portion may be smaller than the rotation speed of the container when ink is ejected from the portion of the inkjet head facing the small outer diameter portion. Alternatively, the inkjet head may be provided as a large dot image inkjet head for forming large dot images and a small dot image inkjet head for forming small dot images, and the large dot image inkjet head may be used to eject ink onto the large outer diameter portion, while the small dot image inkjet head may be used to eject ink onto the small outer diameter portion. In addition, a container conveying means for conveying containers may be further provided, and a plurality of container stopping points may be provided that are located at different positions in the direction in which the container is conveyed by the container conveying means, and the inkjet head may be provided at each of the container stopping points, so that the container stopping point at which the inkjet head for large dot images is provided is different from the container stopping point at which the inkjet head for small dot images is provided. In addition, the frequency of ink ejection into the container at the container stopping location where the inkjet head for large dot images is provided may be greater than the frequency of ink ejection into the container at the container stopping location where the inkjet head for small dot images is provided. The rotation speed of the container at the container stopping location where the large dot image inkjet head is provided may be slower than the rotation speed of the container at the container stopping location where the small dot image inkjet head is provided. Furthermore, the frequency of ink ejection when a dot image is formed on the large outer diameter portion may be higher than the frequency of ink ejection when a dot image is formed on the small outer diameter portion. The rotation speed of the container when the dot image is formed on the large outer diameter portion may be slower than the rotation speed of the container when the dot image is formed on the small outer diameter portion. Furthermore, when the present invention is considered as a container, the container to which the present invention is applicable is a beverage container that is formed in a cylindrical shape and has a tapered portion whose outer diameter decreases as it progresses in the axial direction, and an image composed of a plurality of dot images is formed on the outer surface of the container, and the size of the dot images formed on the large outer diameter portion, which is the part of the tapered portion with a larger outer diameter, is larger than the size of the dot images formed on the small outer diameter portion, which is the part of the tapered portion with a smaller outer diameter. Here, the number of the dot images formed on the large outer diameter portion and arranged in the circumferential direction of the large outer diameter portion may be greater than the number of the dot images formed on the small outer diameter portion and arranged in the circumferential direction of the small outer diameter portion. Furthermore, when the present invention is considered as a manufacturing method of a beverage container, the manufacturing method of a beverage container to which the present invention is applicable is a manufacturing method of a beverage container that is formed in a cylindrical shape and has a tapered portion whose outer diameter decreases as it progresses in the axial direction, and has an image formed on its outer peripheral surface, the manufacturing method of a beverage container that rotates the container in a circumferential direction, and ejects ink onto the outer peripheral surface of the rotating container from an inkjet head arranged along the axial direction of the container and positioned opposite the outer peripheral surface of the container, to form multiple dot images on the outer peripheral surface, and when forming the multiple dot images on the outer peripheral surface, the dot images are formed so that the size of the dot images formed on the large outer diameter portion of the tapered portion, which is the part with a larger outer diameter, is larger than the size of the dot images formed on the small outer diameter portion of the tapered portion, which is the part with a smaller outer diameter. [Effects of the Invention]

[0007] According to the present invention, it is possible to prevent deterioration in the quality of an image formed on a reduced diameter portion of a beverage container. [Brief explanation of the drawings]

[0008] [Figure 1] 1(A) and 1(B) are diagrams illustrating a beverage can. [Figure 2] FIG. 1 is a diagram showing a printing device that prints on beverage cans. [Figure 3] FIG. 2 is a diagram illustrating an example of the hardware configuration of a control unit. [Figure 4] 4 is a view of the upstream printing unit and the downstream printing unit as viewed from the direction indicated by arrow IV in FIG. 2. [Figure 5] 10A and 10B are diagrams showing another example of an image formed on a reduced diameter portion of a beverage can. [Figure 6] FIG. 10 is a diagram showing another example of the configuration of the printing unit. [Figure 7] FIG. 10 is a diagram illustrating another example of the configuration of a printing device. [Figure 8] 10A and 10B are diagrams showing other configuration examples of beverage cans. [Figure 9]FIG. 1 is a perspective view of a beverage can as viewed from above. [Figure 10] FIG. 1 is a diagram illustrating a printing device having a configuration in which a support member is attached to a rotating member. [Figure 11] FIG. 1 is a diagram illustrating a printing device having a configuration in which a support member is attached to a rotating member. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Figures 1(A) and (B) are diagrams illustrating a beverage can 10 according to this embodiment. Figure 1(A) is a front view of the beverage can 10, and Figure 1(B) is a view of the beverage can 10 as viewed from the direction of arrow IB in Figure 1(A). This beverage can 10, which is an example of a container, is formed in a cylindrical shape. Furthermore, as shown in Figure 1(A), this beverage can 10 is provided with a reduced diameter portion 11 whose outer diameter decreases along the axial direction.

[0010] In this embodiment, a reduced diameter portion 11 is provided in the beverage can 10, and the beverage can 10 of this embodiment is a so-called tapered can. The beverage can 10 is provided with a can body 31, and in this embodiment, the entire can body 31 is tapered. As shown in FIG. 1(A), a beverage can 10 has one end 11A and another end 11B that are located at different axial positions. A circular opening 11E is provided at one end 11A of beverage can 10. A bottom 11F is provided at the other end 11B of beverage can 10. Can body 31 is located between opening 11E and bottom 11F.

[0011] In this embodiment, the outer diameter of one end 11A of the beverage can 10 is larger than the outer diameter of the other end 11B of the beverage can 10. The reduced diameter portion 11 is provided on the beverage can 10 from the one end 11A side to the other end 11B side. The reduced diameter portion 11 is provided so that the outer diameter gradually decreases as it progresses in the axial direction of the beverage can 10. More specifically, the reduced diameter portion 11 is provided so that the outer diameter gradually decreases as it progresses from one end 11A of the beverage can 10 to the other end 11B.

[0012] The reduced diameter portion 11 has a large outer diameter portion 11X, which is a portion with a large outer diameter, and a small outer diameter portion 11Y, which is a portion with a small outer diameter. In this embodiment, when comparing positions in the axial direction of the beverage can 10, the position of the large outer diameter portion 11X and the position of the small outer diameter portion 11Y are different. Furthermore, the reduced diameter portion 11 has an intermediate portion 11Z between the large outer diameter portion 11X and the small outer diameter portion 11Y. In this embodiment, when comparing the outer diameter of the large outer diameter portion 11X, the outer diameter of the intermediate portion 11Z, and the outer diameter of the small outer diameter portion 11Y, the relationship among the outer diameters is as follows. Relationship of outer diameter: outer diameter of large outer diameter part 11X > outer diameter of intermediate part 11Z > outer diameter of small outer diameter part 11Y

[0013] As shown in FIG. 1(A), an image 101 is formed on an outer peripheral surface 11M of a beverage can 10. This image 101 is made up of a plurality of dot images 102 formed by hardening ink ejected by an inkjet, which will be described later. The drawings indicated by reference numerals 1A, 1B, and 1C in FIG. 1 are enlarged views of a portion of an image 101 formed on an outer peripheral surface 11M of a beverage can 10. In this embodiment, as shown in the figures indicated by symbols 1A, 1B, and 1C, a dot image 102 is formed on the outer peripheral surface 11M of the reduced diameter portion 11, and an image 101 is formed by a plurality of these dot images 102.

[0014] The dot images 102 are arranged in the axial direction of the beverage can 10. The dot images 102 are also arranged in the circumferential direction of the beverage can 10. The drawings denoted by reference numerals 1A, 1B, and 1C show dot images 102 aligned in the axial direction of a beverage can 10, that is, one row of dot images 102 along this axial direction. In this embodiment, as shown in the figures indicated by symbols 1A and 1C, the size of the dot image 102 formed in the large outer diameter portion 11X of the narrowing portion 11 is larger than the size of the dot image 102 formed in the small outer diameter portion 11Y of the narrowing portion 11. In other words, in this embodiment, the diameter of the dot image 102 formed on the large outer diameter portion 11X of the reduced diameter portion 11 is larger than the diameter of the dot image 102 formed on the small outer diameter portion 11Y of the reduced diameter portion 11.

[0015] In the printing device of this embodiment (described later), when forming a dot image 102 using an inkjet head, the dot image 102 is formed so that the size of the dot image 102 formed in the large outer diameter portion 11X is larger than the size of the dot image 102 formed in the small outer diameter portion 11Y. In this embodiment, two types of dot images 102, large dot images 102 and small dot images 102, are formed.

[0016] In this embodiment, as shown in the figure indicated by the symbol 1B, the dot image 102 is formed so that a large dot image 102 is formed in the large outer diameter region 11J, which is an area located closer to the large outer diameter portion 11X than the intermediate portion 11Z, with the intermediate portion 11Z as the boundary. In this embodiment, the dot images 102 are formed so that small dot images 102 are formed in the small outer diameter region 11K, which is a region located closer to the small outer diameter portion 11Y than the intermediate portion 11Z.

[0017] In this embodiment, two types of dot images 102 are formed in this way: large dot images 102 and small dot images 102. However, the present invention is not limited to this, and the types of dot images 102 with different sizes may be three or more. When the dot images 102 are of a plurality of different sizes, the sizes of the dot images 102 are changed in order from the small outer diameter portion 11Y to the large outer diameter portion 11X, and the dot images 102 become larger each time the size changes. Alternatively, the dot images 102 may be formed so that they become gradually larger from the small outer diameter portion 11Y toward the large outer diameter portion 11X.

[0018] In this embodiment, the beverage content is filled into the beverage can 10 through an opening 11E located at one end 11A of the beverage can 10. A can lid (not shown) is then attached to the opening 11E to close the opening 11E. This completes the beverage can filled with the beverage. Examples of beverages that can be filled include alcoholic beverages such as beer, and non-alcoholic beverages such as soft drinks. In this embodiment, the beverage can 10 refers to an empty can body before being filled with a beverage. It should be noted that a can lid is not essential, and in some cases, after a beverage is poured into the beverage can 10, a can lid is not attached, and the beverage inside the beverage can 10 may be consumed by a user without the can lid. Furthermore, the dome shape of the bottom 11F (shown by the dotted line in FIG. 1(A)) may be omitted.

[0019] The beverage can 10 of this embodiment is an example of a container. More specifically, the beverage can 10 of this embodiment is an example of a beverage container. The beverage can 10 of this embodiment is made of metal and is formed from a metal material. Specifically, the beverage can 10 is formed from, for example, aluminum, an aluminum alloy, or the like. The beverage can 10 is formed, for example, by subjecting a flat plate material (substrate) to draw and ironing (DI) forming or stretch draw forming. The material of the beverage can 10 is not particularly limited, and the beverage can 10 may be made of a resin material or paper. In other words, a container having a reduced diameter portion 11, such as the beverage can 10 of this embodiment, may be made of a resin material or paper. Furthermore, the method for forming the container is not limited, and the container may be formed by a method other than the above-mentioned draw and ironing (DI) forming or stretch draw forming.

[0020] FIG. 2 is a diagram showing a printing device 100 that prints on a beverage can 10. In this embodiment, the printing device 100 shown in Figure 2 forms an image 101 on the reduced diameter portion 11 (see Figure 1(A)). In other words, in this embodiment, the printing device 100 forms an image 101 on the can body 31 of the beverage can 10. In other words, in this embodiment, the printing device 100 forms an image 101 on the outer peripheral surface 11M of the beverage can 10. The printing device 100 is provided with a control unit 60 that controls each unit of the printing device 100 .

[0021] 3 is a diagram showing an example of the hardware configuration of the control unit 60. The control unit 60 is realized by a computer. The control unit 60 has an arithmetic processing unit 21 that executes digital arithmetic processing according to a program, and a secondary storage unit 212 that stores information. The secondary storage unit 212 is realized by an existing information storage device such as an HDD (Hard Disk Drive), semiconductor memory, or magnetic tape.

[0022] The arithmetic processing unit 21 includes a CPU 21a as an example of a processor. The arithmetic processing unit 21 is also provided with a RAM 21b used as a working memory for the CPU 21a, and a ROM 21c in which programs executed by the CPU 21a are stored. The arithmetic processing unit 21 is also provided with a nonvolatile memory 21d that is rewritable and can retain data even if the power supply is interrupted.

[0023] The nonvolatile memory 21d is configured, for example, with a battery-backed SRAM, a flash memory, etc. The secondary storage unit 212 stores files and the like, as well as programs executed by the arithmetic processing unit 21. In this embodiment, the CPU 21a of the arithmetic processing unit 21 reads programs stored in the ROM 21c or the secondary storage unit 212, and thereby various processes performed by the printing device 100 are executed.

[0024] The program executed by the CPU 21a may be provided to the printing device 100 in a state where it is stored in a computer-readable recording medium such as a magnetic recording medium (such as a magnetic tape or a magnetic disk), an optical recording medium (such as an optical disk), a magneto-optical recording medium, or a semiconductor memory. The program executed by the CPU 21a may also be provided to the printing device 100 using a communication means such as the Internet.

[0025] The printing device 100 will be further described with reference to FIG. The printing apparatus 100 is provided with a supply unit 510 to which beverage cans 10 are supplied. In the supply section 510, beverage cans 10 are attached to support members 20 designated by the reference symbol 2A. The support members 20 designated by the reference symbol 2A move to the supply section 510. In the supply section 510, beverage cans 10 are attached to the support members 20. In the printing device 100, the beverage can 10 is supported by the support member 20.

[0026] The outer peripheral surface of the support member 20 is tapered. The support member 20 is provided with its axis aligned horizontally. In this embodiment, the support member 20 is inserted into the beverage can 10, and thereby the beverage can 10 is supported by the support member 20. Furthermore, the printing device 100 of this embodiment is provided with a plurality of moving units 550 as an example of a moving body that moves while supporting the beverage can 10.

[0027] In this embodiment, the support member 20 that supports the beverage can 10 is attached to the moving unit 550. The support member 20 and the beverage can 10 supported by the support member 20 move together with the moving unit 550. As indicated by the reference symbol 2A, each of the moving units 550 is provided with a rotation mechanism 550E as an example of a rotation means for rotating the support member 20 in the circumferential direction. The rotation mechanism 550E is provided with a drive motor (not shown).

[0028] In this embodiment, the control unit 60 controls the rotation of the drive motor, thereby making it possible to change the rotation speed of the beverage can 10. In this embodiment, a control signal is sent from the control unit 60 to the drive motor, thereby changing the rotation speed of the beverage can 10. In this embodiment, the control signal is sent from the control unit 60 to the moving unit 550 by wireless communication.

[0029] An upstream printing unit 700 is provided downstream of the supply unit 510 . The upstream printing unit 700 is provided with a plurality of inkjet heads 19. Each of the inkjet heads 19 is provided to extend in a direction perpendicular to the plane of the paper in Fig. 2. Each of the inkjet heads 19 is provided to extend along the horizontal direction. The upstream printing unit 700 uses an inkjet printing method to form an image 101 (see FIG. 1(A)) on a beverage can 10 that has been moved from the upstream side.

[0030] Forming an image by inkjet printing refers to printing onto the beverage can 10 by ejecting ink from the inkjet head 19. When ink is ejected from inkjet head 19 and adhered to beverage can 10, a plurality of dot images 102 are formed on outer peripheral surface 11M of beverage can 10 (see FIG. 1(A)). In this embodiment, the image 101 shown in FIG. 1(A) is formed by the plurality of dot images 102.

[0031] A plurality of ejection ports (not shown) for ejecting ink are provided on the bottom surface of the inkjet head 19, and in this embodiment, an image 101 is formed by ejecting ink from the plurality of ejection ports. When forming an image by inkjet printing, known methods can be used, such as a piezo method, a thermal (bubble) method, or a continuous method.

[0032] Furthermore, in this embodiment, a downstream printing unit 800 is provided downstream of the upstream printing unit 700 . The downstream printing unit 800 has the same configuration as the upstream printing unit 700 . The downstream printing unit 800 is also provided with a plurality of inkjet heads 19. The downstream printing unit 800 also uses an inkjet printing method to form an image 101 on a beverage can 10 that has been moved from the upstream side.

[0033] A light irradiation unit 751 as an example of a light irradiation means is provided downstream of the downstream printing unit 800. The light irradiating unit 751 has a light source and irradiates light onto the beverage cans 10 after image formation by the upstream printing unit 700 and image formation by the downstream printing unit 800 has been performed. This hardens the image 101 formed on the outer peripheral surface 11M of the beverage can 10. In other words, the dot image 102 formed on the outer peripheral surface 11M of the beverage can 10 hardens.

[0034] The upstream printing unit 700 and the downstream printing unit 800 form the image 101 using ultraviolet curable ink. In other words, the upstream printing unit 700 and the downstream printing unit 800 form the image 101 using actinic radiation curable ink. The light irradiating section 751 irradiates ultraviolet light onto the image 101 formed on the outer peripheral surface 11M of the beverage can 10. As a result, the image 101 hardens.

[0035] The ink used to form the image 101 is not limited to ultraviolet curable ink, and other types of ink such as heat curable ink may also be used. Image 101 can be formed using any existing ink that has been conventionally used, and there are no particular limitations on the ink used to form image 101. In other words, image 101 can be formed using any known ink that has been conventionally used for printing on beverage cans 10, and there are no particular limitations on the ink used to form image 101.

[0036] Furthermore, in the printing apparatus 100 of this embodiment, a protective layer forming unit 770 is provided downstream of the light irradiating unit 751 . The protective layer forming unit 770 applies paint onto the image 101 formed by the upstream printing unit 700 and the downstream printing unit 800, forming a transparent layer that covers the image 101. As a result, in this embodiment, a transparent protective layer (not shown) is formed on the outermost layer of the beverage can 10.

[0037] Downstream of the protective layer forming section 770, a removing section 780 is provided where the beverage cans 10 are removed from the support member 20. In this embodiment, the beverage can 10 is removed from the support member 20 at the removal unit 780. Then, in this embodiment, the beverage can 10 is ejected to the outside of the printing device 100. The beverage can 10 discharged outside the printing apparatus 100 is heated by a heating device (not shown), which hardens the protective layer formed on the outermost layer of the beverage can 10.

[0038] The printing device 100 is provided with a plurality of moving units 550 as an example of a moving body. In this embodiment, the moving units 550 support the beverage cans 10, and the beverage cans 10 move together with the moving units 550. Furthermore, in this embodiment, there is provided a moving mechanism 560 that functions as a moving means for moving the moving unit 550. The moving mechanism 560 is provided with an annular guide member 561 that guides the moving unit 550.

[0039] Each of the moving units 550 is guided by a guide member 561 and moves circularly along a predetermined circular moving path 850 . In this embodiment, a conveying mechanism 600, which is an example of a container conveying means, is configured by the moving unit 550 and the moving mechanism 560. In this embodiment, the conveying mechanism 600 conveys the beverage cans 10.

[0040] An electromagnet (not shown) is provided inside guide member 561. Furthermore, a permanent magnet (not shown) is provided in moving unit 550. In this embodiment, a linear mechanism is used to move moving unit 550. The conveying mechanism 600 of this embodiment conveys beverage cans 10 using the linear mechanism. The moving unit 550 is not limited to a linear mechanism and may be moved by other mechanisms. For example, the moving unit 550 may be provided with a motor so that the moving unit 550 moves autonomously.

[0041] The moving unit 550 moves along a predetermined circular moving path 850 . The movement path 850 is disposed so that its axis 800C is aligned with the horizontal direction. In other words, the movement path 850 is disposed around the axis 800C aligned with the horizontal direction. The axis 800C extends in a direction perpendicular to the plane of the paper in FIG. 2 . In this case, in this embodiment, the moving unit 550 moves around this axis center 800C that extends in a direction perpendicular to the paper surface in the drawing.

[0042] In this embodiment, an example has been described in which the annular movement path 850 is arranged around an axial center 800C along the horizontal direction, but this is not limiting, and the annular movement path 850 may also be arranged around an axial center along the vertical direction. Even when the annular movement path 850 is arranged around an axis center that is aligned in the vertical direction, it is preferable that the support member 20 and the inkjet head 19 are aligned in the horizontal direction.

[0043] 2, if the annular movement path 850 is arranged around a vertical axis, the support member 20 and the inkjet head 19 will be aligned vertically. This can easily lead to a decrease in the quality of the image 101 formed on the beverage can 10. Therefore, when the annular movement path 850 is arranged around an axial center along the vertical direction, it is preferable not to maintain the configuration of each part shown in FIG. 2 as it is. When the circular movement path 850 is arranged around an axial center along the vertical direction, it is preferable to change the arrangement angle of at least the support member 20 and the inkjet head 19 so that they are arranged along the horizontal direction.

[0044] The upstream printing unit 700 and the downstream printing unit 800 will now be described in detail. The upstream printing unit 700 and the downstream printing unit 800 have the same configuration. Each of the upstream printing unit 700 and the downstream printing unit 800 is provided with a plurality of inkjet heads 19 arranged side by side in the left-right direction in the figure. Each of the inkjet heads 19 is provided along the horizontal direction. Each of the upstream printing unit 700 and the downstream printing unit 800 is provided with a first inkjet head 19C that ejects cyan ink, a second inkjet head 19M that ejects magenta ink, a third inkjet head 19Y that ejects yellow ink, and a fourth inkjet head 19K that ejects black ink.

[0045] In this embodiment, each of the upstream printing unit 700 and the downstream printing unit 800 is provided with an inkjet head 19 that ejects ink of the same color, and in this embodiment, two inkjet heads 19 that eject ink of the same color are provided. In this embodiment, a plurality of inkjet heads 19 are provided for each color. Specifically, two inkjet heads 19 are provided for each color.

[0046] Four inkjet heads 19, namely, first inkjet head 19C to fourth inkjet head 19K, provided in each of the upstream printing unit 700 and the downstream printing unit 800, form images on the outer peripheral surface 11M of the beverage can 10 using ultraviolet curable ink. In this embodiment, the beverage can 10 moves with its axial direction horizontal, and a part of the outer circumferential surface 11M of the beverage can 10 faces upward in the vertical direction. In this embodiment, ink is ejected downward from above this outer peripheral surface 11M to form an image 101 (see FIG. 1(A)) on the outer peripheral surface 11M of the beverage can 10.

[0047] Furthermore, in this embodiment, the four inkjet heads 19 provided in each of the upstream printing unit 700 and the downstream printing unit 800 are arranged side by side in the conveyance direction of the beverage cans 10. Moreover, each of the four inkjet heads 19 is arranged along a direction perpendicular to (intersecting with) the conveyance direction of the beverage cans 10. In this embodiment, ink is ejected from above onto the outer peripheral surface 11M of the beverage can 10 as the beverage can 10 passes below four inkjet heads 19 provided in each of the upstream printing unit 700 and the downstream printing unit 800. In this way, an image 101 is formed on the outer peripheral surface 11M of the beverage can 10.

[0048] Each of the moving units 550 stops at the installation location of one of the multiple inkjet heads 19. Then, at the installation location of each inkjet head 19, ink is ejected onto the outer peripheral surface 11M of the beverage can 10, and an image 101 is formed on the outer peripheral surface 11M of the beverage can 10. When the inkjet heads 19 form the image 101, the drive motor provided in the rotation mechanism 550E is driven, and the beverage can 10 rotates in the circumferential direction.

[0049] The beverage can 10 supported by the moving unit 550 stops at the installation locations of the multiple inkjet heads 19. In this embodiment, the installation locations of the inkjet heads 19 are beverage can stopping locations 91, where the beverage can 10 stops. At each of these beverage can stopping points 91, which are examples of container stopping points, ink is ejected from the inkjet head 19 onto the outer surface 11M of the beverage can 10, forming an image 101 on this outer surface 11M. When the image 101 is formed on the outer peripheral surface 11M of the beverage can 10, the beverage can 10 is rotating, and ink is ejected from each inkjet head 19 onto the rotating beverage can 10.

[0050] Each of the moving units 550 also stops at the supplying section 510, the light irradiating section 751, the protective layer forming section 770, and the removing section 780, respectively. In addition, in the light irradiation section 751 and the protective layer forming section 770, the beverage can 10 supported by the moving unit 550 is rotated in the circumferential direction.

[0051] FIG. 4 is a diagram of the upstream printing unit 700 and the downstream printing unit 800 as viewed from the direction indicated by arrow IV in FIG. In this embodiment, as described above, the upstream printing unit 700 and the downstream printing unit 800 are each provided with four inkjet heads 19, the first inkjet head 19C to the fourth inkjet head 19K. In this embodiment, when the inkjet heads 19 form an image 101 on the beverage can 10, each of the inkjet heads 19 is arranged along the axial direction of the beverage can 10 and positioned opposite the outer peripheral surface 11M of the beverage can 10.

[0052] Furthermore, when the inkjet heads 19 form the image 101 on the beverage can 10, each of the inkjet heads 19 is provided from one end 11A to the other end 11B of the beverage can 10 in the axial direction. In this embodiment, the inkjet heads 19 include an inkjet head for large dot images 19L that forms large dot images 102, and an inkjet head for small dot images 19S that forms dot images 102 that are smaller than the dot images 102 formed by the inkjet head for large dot images 19L.

[0053] In this embodiment, each of the four inkjet heads 19 provided in the upstream printing section 700 is a large-dot image inkjet head 19L. In this embodiment, the large dot image inkjet head 19L ejects ink onto a large outer diameter region 11J (see FIG. 1A) including the large outer diameter portion 11X (see FIG. 1A). In this embodiment, each of the four inkjet heads 19 provided in the downstream printing section 800 is an inkjet head 19S for small dot images.

[0054] In this embodiment, the dot images 102 formed by the inkjet head 19S for small dot images are smaller than the dot images 102 formed by the inkjet head 19L for large dot images. In other words, in this embodiment, the amount of ink contained in the ink droplets ejected by the inkjet head 19S for small dot images is less than the amount of ink contained in the ink droplets ejected by the inkjet head 19L for large dot images. In other words, in this embodiment, the volume of ink ejected by the inkjet head 19S for small dot images, which is the volume per ink droplet, is smaller than the volume of ink ejected by the inkjet head 19L for large dot images, which is the volume per ink droplet.

[0055] In this embodiment, the small dot image inkjet head 19S ejects ink onto the small outer diameter region 11K (see FIG. 1A) including the small outer diameter portion 11Y (see FIG. 1A). As a result, in this embodiment, as shown in Figure 1(A), a large dot image 102 is formed in the large outer diameter region 11J including the large outer diameter portion 11X, and a small dot image 102 is formed in the small outer diameter region 11K including the small outer diameter portion 11Y.

[0056] Note that the dot image 102 shown in FIG. 1(A) and the dot image 102 described below each represent a dot image 102 formed by one of four sets of inkjet heads 19 provided for each color. More specifically, the dot image 102 shown in FIG. 1(A) and the dot images 102 described below are both dot images 102 formed by a set of inkjet heads 19 corresponding to one color, such as an inkjet head 19L for large dot images corresponding to black and an inkjet head 19S for small dot images corresponding to black. Of the four sets of inkjet heads 19, the remaining three sets of inkjet heads 19 each form a dot image 102 in the same manner as the dot image 102 formed by the one set of inkjet heads 19 described above.

[0057] Here, in the case where the beverage can 10 is provided with a reduced diameter section 11 as in this embodiment, if ink is ejected from the inkjet head 19 at regular time intervals, the formed image 101 may have variations in shade, which may result in a deterioration in the quality of the formed image 101. When a beverage can 10 is provided with a reduced diameter section 11, the spacing between the dot images 102 arranged in a circumferential direction of the part of the reduced diameter section 11 with a larger outer diameter differs from the spacing between the dot images 102 arranged in a circumferential direction of the part of the reduced diameter section 11 with a smaller outer diameter.

[0058] In this case, the formed image 101 may have uneven shading, which may result in a deterioration in the quality of the formed image 101. In contrast to this, in this embodiment, a large dot image 102 is formed on the side of the reduced diameter portion 11 where the large outer diameter portion 11X is located. Also, in this embodiment, a small dot image 102 is formed on the side of the reduced diameter portion 11 where the small outer diameter portion 11Y is located. In this case, the shading of the image 101 formed on the reduced diameter portion 11 becomes smaller.

[0059] In this embodiment, as shown in FIG. 4, a plurality of beverage can stopping points 91 are provided. The plurality of beverage can stopping points 91 are provided at mutually different positions in the direction in which the beverage cans 10 are conveyed by the conveying mechanism 600 (see FIG. 2). In this embodiment, an inkjet head 19 is provided at each of the beverage can stopping points 91 . Furthermore, in this embodiment, the beverage can stopping location 91 where the large dot image inkjet head 19L is provided is different from the beverage can stopping location 91 where the small dot image inkjet head 19S is provided.

[0060] Here, one beverage can stopping point 91 may be provided with inkjet head 19L for large dot images and inkjet head 19S for small dot images. However, it is more preferable that the beverage can stopping location 91 where the large dot image inkjet head 19L is provided is different from the beverage can stopping location 91 where the small dot image inkjet head 19S is provided. Here, it is assumed that a single beverage can stopping location 91 is provided with inkjet head 19L for large dot images and inkjet head 19S for small dot images.

[0061] In this case, in order to avoid interference between the inkjet heads 19, it may be necessary to position one or both of the inkjet head for large dot images 19L and the inkjet head for small dot images 19S at an angle, or it may be necessary to position one or both of them in a direction other than the vertical direction. In this case, the quality of the formed image 101 is more likely to deteriorate than when the height direction of the inkjet head 19 coincides with the vertical direction and the inkjet head 19 is arranged along the vertical direction.

[0062] In contrast to this, in this embodiment, the beverage can stopping location 91 where the large dot image inkjet head 19L is provided is different from the beverage can stopping location 91 where the small dot image inkjet head 19S is provided. In this case, the large dot image inkjet head 19L and the small dot image inkjet head 19S can be arranged vertically, which reduces the risk of problems such as a decrease in the quality of the formed image 101.

[0063] FIG. 5 is a diagram showing another example of an image 101 formed on the reduced diameter portion 11 of a beverage can 10. In FIG. In this example shown in Figure 5, the number of dot images 102 located in the large outer diameter region 11J and arranged in the circumferential direction of the beverage can 10 is greater than the number of dot images 102 located in the small outer diameter region 11K and arranged in the circumferential direction of the beverage can 10. Specifically, for example, the number of large dot images 102 arranged in a line around the circumference of the beverage can 10 located in the area indicated by reference symbol 5A in Figure 5 is greater than the number of small dot images 102 arranged in a line around the circumference of the beverage can 10 located in the area indicated by reference symbol 5B in Figure 5.

[0064] In this embodiment, multiple dot image rows 193A in which large dot images 102 are arranged in the circumferential direction of the beverage can 10 are present within the large outer diameter region 11J. In this embodiment, a plurality of dot image rows 193B in which small dot images 102 are arranged in the circumferential direction of the beverage can 10 are present within the small outer diameter region 11K. In this embodiment, the number of large dot images 102 included in each of the plurality of dot image rows 193A is different from the number of small dot images 102 included in each of the plurality of dot image rows 193B. In this embodiment, the number of large dot images 102 included in each of the plurality of dot image rows 193A is the same. In this embodiment, there are multiple dot image rows 193A (only one dot image row 193A is shown in Figure 5), but the number of large dot images 102 included in one of the multiple dot image rows 193A is the same as the number of large dot images 102 included in another of the multiple dot image rows 193A. In this embodiment, the number of small dot images 102 included in each of the plurality of dot image rows 193B is the same. In this embodiment, there are multiple dot image rows 193B (only one dot image row 193B is shown in Figure 5), but the number of small dot images 102 included in one dot image row 193B is the same as the number of small dot images 102 included in another dot image row 193B.

[0065] In the example shown in Figure 5, the number of large dot images 102 contained in each dot image row 193A located in the large outer diameter region 11J and extending along the circumferential direction of the beverage can 10 is greater than the number of small dot images 102 contained in each dot image row 193B located in the small outer diameter region 11K and extending along the circumferential direction of the beverage can 10. In this way, by making the number of large dot images 102 contained in each dot image row 193A greater than the number of small dot images 102 contained in each dot image row 193B, it is possible to make the shading of the image 101 even less pronounced than when the numbers of dot images 102 are the same.

[0066] When forming a dot image 102 in the form shown in Figure 5, for example, the frequency of ink ejection onto the beverage can 10 at the beverage can stopping point 91 where the large dot image inkjet head 19L (see Figure 4) is provided is made higher than the frequency of ink ejection onto the beverage can 10 at the beverage can stopping point 91 where the small dot image inkjet head 19S is provided. In other words, the ink ejection frequency of the large dot image inkjet head 19L that ejects ink onto the large outer diameter region 11J is set higher than the ink ejection frequency of the small dot image inkjet head 19S that ejects ink onto the small outer diameter region 11K.

[0067] In other words, the number of times that the large dot image inkjet head 19L ejects ink per unit time is set to be greater than the number of times that the small dot image inkjet head 19S ejects ink per unit time. As a result, in this embodiment, the number of large dot images 102 aligned in the circumferential direction of the beverage can 10 is greater than the number of small dot images 102 aligned in the circumferential direction of the beverage can 10.

[0068] Additionally, when forming a dot image 102 in the form shown in FIG. 5, the rotational speed of the beverage can 10 at the beverage can stopping point 91 where the large dot image inkjet head 19L (see FIG. 4) is provided may be set lower than the rotational speed of the beverage can 10 at the beverage can stopping point 91 where the small dot image inkjet head 19S is provided. In this case as well, the number of large dot images 102 aligned in the circumferential direction of the beverage can 10 is greater than the number of small dot images 102 aligned in the circumferential direction of the beverage can 10.

[0069] Alternatively, when forming dot image 102 in the form shown in FIG. 5, the ink ejection frequency of large dot image inkjet head 19L may be set higher than the ink ejection frequency of small dot image inkjet head 19S, and the rotation speed of beverage can 10 at beverage can stopping point 91 where large dot image inkjet head 19L is provided may be set lower than the rotation speed of beverage can 10 at beverage can stopping point 91 where small dot image inkjet head 19S is provided.

[0070] In other words, the ink ejection frequency of the inkjet head 19L for large dot images may be set to be greater than the ink ejection frequency of the inkjet head 19S for small dot images, and the rotation speed of the beverage can 10 when the large dot image 102 is formed by the inkjet head 19L for large dot images may be set to be less than the rotation speed of the beverage can 10 when the small dot image 102 is formed by the inkjet head 19S for small dot images.

[0071] Fig. 6 is a diagram showing another example of the configuration of the printing unit, showing the printing unit as viewed from above. In the above, the sizes of the dot images 102 are made different by providing two inkjet heads 19, an inkjet head 19L for large dot images and an inkjet head 19S for small dot images, but the manner in which the sizes of the dot images 102 are made different is not limited to this.

[0072] For example, as shown in FIG. 6, one common inkjet head 191 may be used to produce dot images 102 of different sizes. In the printing section 980 shown in FIG. 6, instead of two inkjet heads 19, an inkjet head 19L for large dot images and an inkjet head 19S for small dot images, one common inkjet head 191 is provided for each color. In this configuration example shown in FIG. 6, instead of providing two inkjet heads 19 for each color, one common inkjet head 191 is provided for each color, and the size of the dot image 102 is made different using this one common inkjet head 191.

[0073] In this configuration example, a common inkjet head 191 is provided with a large outer diameter facing portion 191A that faces the large outer diameter region 11J and a small outer diameter facing portion 191B that faces the small outer diameter region 11K. When using this common inkjet head 191, the dot image 102 (not shown in Figure 6) formed by the ink ejected from the large outer diameter opposing portion 191A is made larger than the dot image 102 formed by the ink ejected from the small outer diameter opposing portion 191B. In other words, in this case, the amount of ink contained in the ink droplets ejected from the large outer diameter facing portion 191A is made greater than the amount of ink contained in the ink droplets ejected from the small outer diameter facing portion 191B, thereby creating a difference in the amount of ink contained in the ink droplets. In other words, in this case, the volume of ink ejected from the large outer diameter opposing portion 191A, i.e., the volume per ink droplet, is made larger than the volume of ink ejected from the small outer diameter opposing portion 191B, i.e., the volume per ink droplet, thereby creating a difference in the volume per ink droplet.

[0074] Furthermore, when using this common inkjet head 191, in addition to differentiating the amount of ink contained in the ink droplets, the ejection frequency of the ink ejected from the large outer diameter opposing portion 191A may be made higher than the ejection frequency of the ink ejected from the small outer diameter opposing portion 191B. In this case, the number of large dot images 102 formed in the large outer diameter region 11J and arranged in the circumferential direction of the beverage can 10 is greater than the number of small dot images 102 formed in the small outer diameter region 11K and arranged in the circumferential direction of the beverage can 10.

[0075] Furthermore, when using this common inkjet head 191, in addition to differentiating the amount of ink contained in the ink droplets, the rotational speed of the beverage can 10 when ink is ejected from the large outer diameter opposing portion 191A may be made slower than the rotational speed of the beverage can 10 when ink is ejected from the small outer diameter opposing portion 191B. In other words, when using this common inkjet head 191, in addition to making a difference in the volume per ink droplet, the rotational speed of the beverage can 10 when ink is ejected from the large outer diameter opposing portion 191A may be made slower than the rotational speed of the beverage can 10 when ink is ejected from the small outer diameter opposing portion 191B. In this case too, the number of large dot images 102 formed in the large outer diameter region 11J and arranged in the circumferential direction of the beverage can 10 is greater than the number of small dot images 102 formed in the small outer diameter region 11K and arranged in the circumferential direction of the beverage can 10.

[0076] Furthermore, when a common inkjet head 191 is used, in addition to differentiating the amount of ink contained in the ink droplets, the ink ejection frequency of the large outer diameter opposing portion 191A may be made higher than the ink ejection frequency of the small outer diameter opposing portion 191B, and the rotation speed of the beverage can 10 when the large outer diameter opposing portion 191A forms the large dot image 102 may be made lower than the rotation speed of the beverage can 10 when the small outer diameter opposing portion 191B forms the small dot image 102. In other words, when a common inkjet head 191 is used, in addition to differentiating the volume per ink droplet, the ink ejection frequency of the large outer diameter opposing portion 191A may be made greater than the ink ejection frequency of the small outer diameter opposing portion 191B, and the rotation speed of the beverage can 10 when the large outer diameter opposing portion 191A forms a large dot image 102 may be made slower than the rotation speed of the beverage can 10 when the small outer diameter opposing portion 191B forms a small dot image 102.

[0077] When changing the rotation speed of the beverage can 10 while using a common inkjet head 191, ink is ejected to either the large outer diameter region 11J or the small outer diameter region 11K, and then the rotation speed of the beverage can 10 is changed. Then, after changing the rotation speed of the beverage can 10, ink is ejected to the other region. In other words, in this case, after ink is ejected to either the large outer diameter region 11J or the small outer diameter region 11K, the rotation speed of the beverage can 10 is changed and then ink is ejected to the other region.

[0078] Alternatively, the number of rotations of beverage can 10 from the start of formation of large dot image 102 in large outer diameter region 11J until the end of formation of this large dot image 102 may be set to be greater than the number of rotations of beverage can 10 from the start of formation of small dot image 102 in small outer diameter region 11K until the end of formation of this small dot image 102. In this case, too, the number of large dot images 102 formed in the large outer diameter region 11J and arranged in the circumferential direction of the beverage can 10 can be made greater than the number of small dot images 102 formed in the small outer diameter region 11K and arranged in the circumferential direction of the beverage can 10.

[0079] More specifically, in this case, for example, when forming a large dot image 102 in the large outer diameter region 11J, the beverage can 10 is first rotated once, and while the beverage can 10 is rotating once, the large dot image 102 is formed in this large outer diameter region 11J. Furthermore, during subsequent rotations of the beverage can 10, new large dot images 102 are formed between the large dot images 102 already formed in the large outer diameter region 11J. Furthermore, when forming the small dot image 102 in the small outer diameter region 11K, for example, the beverage can 10 is rotated once, and while the beverage can 10 is rotating once, the small dot image 102 is formed in this small outer diameter region 11K.

[0080] More specifically, when forming the large dot image 102 in the large outer diameter region 11J, for example, the beverage can 10 is first rotated once at the location where the large dot image inkjet head 19L (see FIG. 4) is installed. Then, while the beverage can 10 is rotating once, the large dot image 102 is formed in the large outer diameter region 11J. Furthermore, rotation continues at the location where large dot image inkjet head 19L is installed. Then, during rotation of beverage can 10 after this one rotation, new large dot images 102 are formed between the large dot images 102 already formed in large outer diameter region 11J.

[0081] Furthermore, when forming the dot image 102 in the small outer diameter region 11K, the beverage can 10 is rotated once at the location where the inkjet head 19S for small dot images (see FIG. 4) is installed. Then, while the beverage can 10 is rotating once, the small dot image 102 is formed in this small outer diameter region 11K. As a result, in this case, the number of large dot images 102 formed in the large outer diameter region 11J and arranged in the circumferential direction of the beverage can 10 is greater than the number of small dot images 102 formed in the small outer diameter region 11K and arranged in the circumferential direction of the beverage can 10.

[0082] Furthermore, when a process for changing the rotation speed of the beverage can 10 is performed and a common inkjet head 191 (see Figure 6) is used, for example, during the first rotation of the beverage can 10, both the large outer diameter opposing portion 191A and the small outer diameter opposing portion 191B are used to form dot images 102 in both the large outer diameter region 11J and the small outer diameter region 11K. Specifically, a large dot image 102 is formed in the large outer diameter region 11J, and a small dot image 102 is formed in the small outer diameter region 11K.

[0083] Furthermore, for example, during the second rotation of the beverage can 10, only the large outer diameter facing portion 191A is used to form the large dot image 102 in the large outer diameter region 11J. This also makes it possible to make the number of large dot images 102 aligned in the circumferential direction of the large outer diameter region 11J greater than the number of small dot images 102 aligned in the circumferential direction of the small outer diameter region 11K.

[0084] When forming a large dot image 102 in the large outer diameter region 11J, if a new large dot image 102 is to be formed between large dot images 102 that have already been formed, as described above, an encoder or the like is used to identify the phase in the rotational direction of the beverage can 10. Specifically, for example, the moving unit 550 (see FIG. 2) is provided with an encoder that identifies the phase in the rotational direction of the support member 20. This encoder is then used to identify the phase of the beverage can 10 when the large dot image 102 is formed during the first rotation of the beverage can 10 supported by the support member 20.

[0085] Then, when a new large dot image 102 is formed during the second rotation of the beverage can 10, the timing of forming the new large dot image 102 during this second rotation is determined based on this identified phase and information about the phase newly acquired during the second rotation of the beverage can 10. Specifically, the timing for forming the large dot image 102 during the second rotation is determined so that the new large dot image 102 is positioned between the large dot images 102 formed by the formation of the large dot images 102 during the first rotation of the beverage can 10.

[0086] FIG. 7 is a diagram showing another example of the configuration of the printing device 100. In FIG. In this configuration example shown in FIG. 7, an intermediate image forming section 750 is provided. In the conveying direction of the beverage cans 10, the intermediate image forming unit 750 is disposed downstream of the upstream printing unit 700 and upstream of the downstream printing unit 800. The intermediate image forming unit 750 has the same configuration as the upstream printing unit 700 and the downstream printing unit 800 .

[0087] 7, three inkjet heads 19 are provided for each color. In this configuration example as well, each of the locations where the inkjet heads 19 are installed serves as a beverage can stopping point 91. The plurality of inkjet heads 19 are provided at different beverage can stopping positions 91 . The inkjet heads 19 provided in the upstream printing unit 700, the intermediate image forming unit 750, and the downstream printing unit 800 eject ink at predetermined fixed time intervals.

[0088] In this configuration example, the number of inkjet heads 19L for large dot images that eject ink into the large outer diameter region 11J (see Figure 1(A)) is greater than the number of inkjet heads 19S for small dot images that eject ink into the small outer diameter region 11K. Specifically, in this configuration example, the upstream printing unit 700 and the intermediate image forming unit 750 are each provided with a large dot image inkjet head 19L, and two large dot image inkjet heads 19L are provided for each color. In contrast to this, the inkjet heads 19S for small dot images are provided only in the downstream printing section 800, and one inkjet head 19S for small dot images is provided for one color. In this configuration example, the number of large dot images 102 formed and aligned in the circumferential direction in the large outer diameter region 11J is also greater than the number of small dot images 102 formed and aligned in the circumferential direction in the small outer diameter region 11K.

[0089] In this configuration example shown in Figure 7, a large dot image inkjet head 19L provided in the upstream printing unit 700 forms multiple large dot images 102 aligned in the circumferential direction of the beverage can 10 in the large outer diameter region 11J. Thereafter, in this configuration example, a plurality of large dot images 102 arranged in the circumferential direction of the beverage can 10 are formed in the large outer diameter region 11J by the large dot image inkjet head 19L provided in the intermediate image forming unit 750.

[0090] In the intermediate image forming unit 750 , new large dot images 102 are formed between the large dot images 102 formed by the upstream printing unit 700 . More specifically, the new large dot image 102 formed by the intermediate image forming unit 750 is formed so that it is positioned between large dot images 102 formed by the upstream printing unit 700 that are adjacent to each other in the circumferential direction of the beverage can 10.

[0091] In this configuration example, similar to the above, when the large dot image 102 is formed in the upstream printing unit 700, an encoder or the like is used to identify the phase in the rotation direction of the beverage can 10. Then, when a new large dot image 102 is formed in the intermediate image forming section 750, the timing of forming this new large dot image 102 in the intermediate image forming section 750 is determined based on the identified phase and information about the phase newly acquired by the intermediate image forming section 750.

[0092] Specifically, the timing at which a new large dot image 102 formed by the intermediate image forming section 750 is positioned between large dot images 102 formed by the formation of large dot images 102 performed in the upstream printing section 700 is determined as the timing at which the new large dot image 102 is formed in the intermediate image forming section 750.

[0093] In this configuration example shown in FIG. 7, each of the inkjet heads 19 is provided at a different beverage can stopping position 91 from the others. As a result, the quality of the formed image 101 is improved compared to when a plurality of inkjet heads 19 are provided at one beverage can stopping point 91, as described above. Here, for example, with regard to the large dot image inkjet head 19L, two large dot image inkjet heads 19L may be provided at one beverage can stopping point 91, but in this case, the quality of the formed image 101 is likely to deteriorate.

[0094] In contrast to this, in this embodiment, the two large dot image inkjet heads 19L are installed at different beverage can stopping positions 91. In this case, the degradation of the quality of the image 101 caused by providing two large dot image inkjet heads 19L at one beverage can stopping location 91 is less likely to occur.

[0095] Note that, although the above describes processing that is based on the assumption that the sizes of the dot images 102 are varied, the above processing may also be performed without varying the sizes of the dot images 102, but with all the dot images 102 being the same size, and only the number of dot images 102 being varied. The above describes the process of making the number of large dot images 102 arranged in the circumferential direction in the large outer diameter region 11J greater than the number of small dot images 102 arranged in the circumferential direction in the small outer diameter region 11K. This process may be performed without changing the size of the dot images 102, but instead by keeping the size of the dot images 102 constant. Even if the size of the dot images 102 is not changed and only the number of dot images 102 is changed, the shading of the formed image 101 becomes smaller.

[0096] FIG. 8 is a diagram showing another example of the configuration of the beverage can 10. In this beverage can 10 shown in FIG. 8, as indicated by the reference symbol 8A, one end 11A of the beverage can 10 is provided with a tapered portion 11 whose outer diameter decreases toward the opening 11E. 8, there is no tapering in the can body 31. In this configuration example, the outer diameter of one end 31A of the can body 31 is approximately equal to the outer diameter of the other end 31B. The above describes the process of forming the dot image 102 on the reduced diameter portion 11 provided on the can body 31, but the above-described formation process may also be applied to a reduced diameter portion 11 provided other than on the can body 31 of the beverage can 10.

[0097] Specifically, the above-described forming process may be applied to forming an image 101 on the reduced diameter portion 11 of a beverage can 10 shown in FIG. In addition, the beverage can 10 shown in FIG. 8 is also provided at the other end 11B of the beverage can 10 with a tapered diameter portion 81, as indicated by reference numeral 8B, whose outer diameter decreases toward the bottom 11F. The formation process described above may be applied to the formation of the image 101 on the reduced diameter portion 81 located on the bottom portion 11F side. The reduced diameter portion to which the forming process described above is applied is not limited to a reduced diameter portion provided in the can body 31, but may also be a reduced diameter portion provided on the opening 11E side or bottom 11F side of the beverage can 10.

[0098] Furthermore, the process for forming the dot image 102 described above does not necessarily have to be applied to the entire area of ​​the reduced diameter portion 11, but may be applied to a partial area of ​​the reduced diameter portion 11, such as an area 89 described later. Specifically, for example, the process of forming the dot image 102 described above may be applied to a portion of the area that extends in the circumferential direction of the reduced diameter portion 11 and over the entire circumference of the reduced diameter portion 11. Furthermore, for example, the process of forming the dot image 102 described above may be applied to a part of the region that extends in the axial direction of the reduced diameter portion 11 and over the entire area in this axial direction.

[0099] In the example shown in Figure 5, the number of large dot images 102 located on the large outer diameter region 11J side and arranged circumferentially around the beverage can 10, which exist around the entire circumference of the beverage can 10, is greater than the number of small dot images 102 located on the small outer diameter region 11K side and arranged circumferentially around the beverage can 10, which exist around the entire circumference of the beverage can 10. In this embodiment, the relationship that the number of large dot images 102 is greater than the number of small dot images 102 also exists in some regions of the reduced diameter portion 11 .

[0100] Here, a rectangular area 89 is assumed as shown by reference numeral 5G in FIG. This rectangular area 89 has a first height direction side 71 and a second height direction side 72 that extend in the height direction of the beverage can 10. In addition, this rectangular area 89 has a first circumferential direction side 73 and a second circumferential direction side 74 that extend in the circumferential direction of the beverage can 10.

[0101] Here, as shown in FIG. 1(B) and FIG. 9, imaginary planes H1 to H4 are assumed. 9 (a perspective view of a beverage can when viewed from above), imaginary plane H1 is an imaginary plane extending along the axial direction of beverage can 10 and passing through axial center 10G of beverage can 10. In addition, imaginary plane H2 is also an imaginary plane extending along the axial direction of beverage can 10 and passing through axial center 10G of beverage can 10. Here, the imaginary plane H1 and the imaginary plane H2 are located at different positions in the circumferential direction of the beverage can 10. The imaginary planes H3 and H4 are imaginary planes that are perpendicular to the extension direction of the axial center 10G of the beverage can 10. The imaginary planes H3 and H4 are located at different positions in the axial direction of the beverage can 10. The first height direction side 71 shown in FIG. 5 is a side that passes through the point where an imaginary plane H1 (not shown in FIG. 5) and the outer peripheral surface 11M of the beverage can 10 intersect. The second height direction side 72 is a side that passes through the point where an imaginary plane H2 (not shown in FIG. 5) and the outer peripheral surface 11M of the beverage can 10 intersect.

[0102] The first circumferential side 73 (see FIG. 5) is a side that passes through the point where the imaginary plane H3 intersects with the outer peripheral surface 11M of the beverage can 10. The second circumferential side 74 is a side that passes through the point where the imaginary plane H4 intersects with the outer peripheral surface 11M of the beverage can 10. In this embodiment, even within this area 89, which is surrounded by the first height direction edge 71, the second height direction edge 72, the first circumferential direction edge 73, and the second circumferential direction edge 74 and forms part of the outer peripheral surface 11M of the beverage can 10, the number of large dot images 102 and the number of small dot images 102 differ.

[0103] Specifically, as described above, in this region 89, the number of large dot images 102 located in the large outer diameter portion 5X and arranged circumferentially around the beverage can 10 is greater than the number of small dot images 102 located in the small outer diameter portion 5Y and arranged circumferentially around the beverage can 10. The relationship that "the number of dot images arranged in the circumferential direction of the large outer diameter portion is greater than the number of dot images arranged in the circumferential direction of the small outer diameter portion" is not limited to the relationship between the magnitude of the number of dot images 102 existing around the entire circumference of the beverage can 10, but also applies to the relationship between the magnitude of the number of dot images 102 existing in a certain area of ​​the beverage can 10.

[0104] The "large outer diameter portion" is not limited to the large outer diameter portion 11X located at one end 11A of the beverage can 10 shown in Figure 1(A), but may also be a portion other than one end 11A of the beverage can 10, such as the large outer diameter portion 5X shown in Figure 5. The "large outer diameter portion" refers to a portion having a relatively larger outer diameter than the "small outer diameter portion," and does not refer to a specific portion such as one end 11A of beverage can 10 in the axial direction. If there are two portions with relatively different outer diameters, then a "large outer diameter portion" and a "small outer diameter portion" are provided.

[0105] In addition, in the above, the size of the dot images 102 and the number of dot images 102 are made different between the large outer diameter region 11J located closer to the large outer diameter portion 11X than the intermediate portion 11Z (see Figure 1(A)) and the small outer diameter region 11K located closer to the small outer diameter portion 11Y than the intermediate portion 11Z, but the manner in which the dot images 102 are formed is not limited to this. For example, the dot image 102 may be formed so that it gradually becomes larger from the small outer diameter portion 11Y of the reduced diameter portion 11 toward the large outer diameter portion 11X. Alternatively, the dot images 102 may be formed so that the number of dot images 102 contained in a row of dot images aligned circumferentially on the beverage can 10 gradually increases from the small outer diameter portion 11Y of the reduced diameter portion 11 toward the large outer diameter portion 11X.

[0106] In addition, in the above, an example has been described in which the size of one dot image 102 is changed by changing the amount of ink contained in one drop of ink ejected from the inkjet head 19, but the size of one dot image 102 may also be changed in other ways. In other words, the above describes an example in which the size of a single dot image 102 is changed by changing the volume of each ink droplet, but the size of a single dot image 102 may also be changed in other ways. To explain further, in the above, we have described a case where the size of a single dot image 102 is changed by increasing or decreasing the amount of ink ejected, thereby changing the amount of ink ejected, but the size of a single dot image 102 may also be changed in other ways. Another example of such an embodiment is to change the number of times ink is ejected when forming one dot image 102. By changing the number of times ink is ejected when forming one dot image 102, the size of one dot image 102 can also be changed.

[0107] For example, when forming one large dot image 102, the number of times ink is ejected from one ink ejection port corresponding to this one large dot image 102 may be increased to form this one large dot image. Furthermore, when forming one small dot image 102, the number of times ink is ejected from one ink ejection port corresponding to this one small dot image 102 may be reduced to form this one small dot image 102. When dot images 102 of different sizes are formed by increasing or decreasing the number of times ink is ejected from one ink ejection port, ink is ejected multiple times to form one dot image 102. Each ink droplet ejected by these multiple ink ejections lands on approximately the same landing point, and one dot image 102, such as one large dot image 102 or one small dot image 102, is formed on this landing point. In this case, the size of the dot image 102 formed at the impact point varies depending on the number of times ink is ejected from one ink ejection port.

[0108] Furthermore, in the printing device 100 described above, the beverage can 10 is moved using a so-called linear mechanism, but the manner in which the beverage can 10 is moved is not limited to this. For example, a rotating member may be provided, and the support member 20 may be attached to the rotating member, with the beverage can 10 being supported by the support member 20. In this case, the beverage can 10 moves due to the rotation of the rotating member, and the beverage can 10 stops due to the stopping of the rotation of the rotating member. An inkjet head 19 is provided at the stop position of the beverage can 10, and a dot image 102 is formed on the beverage can 10 at the stop position of the beverage can 10 in the same manner as described above.

[0109] 10 and 11 are diagrams showing a printing device 100 having a configuration in which a support member 20 is attached to a rotating member. 10 is a top view, and FIG. 11 is a cross-sectional view of the printing device 100 taken along line XI-XI in FIG. As shown in FIG. 10, the printing device 100 is provided with a rotary member 210 that is driven by a first motor M1 (see FIG. 11) and rotates intermittently in the direction indicated by an arrow 10A in the figure. The rotating member 210 is formed in a disk shape and rotates around a rotation center 1E shown in Fig. 10. This rotation center 1E extends in the vertical direction.

[0110] A rotation mechanism (not shown) is provided inside the housing 290 shown in FIG. This rotation mechanism is made up of known mechanisms such as gears and cams, and receives force from the first motor M1 to rotate the rotation member 210. In this embodiment, the rotation mechanism is provided around the rotation member 59 (details of which will be described later). 10, the printing device 100 is provided with a plurality of (16 in this embodiment) holding mechanisms 230 that hold beverage cans 10. Note that, although the number of holding mechanisms 230 is 16 in this embodiment, this may be designed as appropriate, and the number of holding mechanisms 230 may be other than 16. As indicated by the reference symbol 1X, each of the holding mechanisms 230 is provided with a shaft 230S that is rotatably supported by the rotation member 210. This shaft 230S is rotatable in the circumferential direction.

[0111] As indicated by the reference symbol 1X, each of the holding mechanisms 230 is provided with a support member 20. In this configuration example as well, the support member 20 supports the beverage can 10. The support member 20 is attached to one end of the shaft 230 S. The support member 20 is supported by the rotating member 210. Specifically, the support member 20 is supported by the rotating member 210 via a shaft 230S. The support member 20 is provided at a position away from the rotation center 1E of the rotating member 210.

[0112] A receiving gear 230G, which is an example of a receiving member that receives a rotational driving force, is provided at the other end of the shaft 230S. The receiving gear 230G is configured by a helical gear. The receiving gear 230G meshes with the transmission member 50 and receives a rotational driving force from the transmission member 50. In this embodiment, as shown in FIG. 11, a gear portion 50G is provided on the outer periphery of the transmission member 50 along the circumferential direction of the transmission member 50. The receiving gear 230G meshes with the gear portion 50G provided on the outer periphery of the transmission member 50, and receives the rotational driving force from the gear portion 50G.

[0113] A plurality of shafts 230S and support members 20 are provided, and the shafts 230S and support members 20 are arranged radially around an arrangement center 1M indicated by reference symbol 1M in FIG. In other words, the shaft 230S and the support member 20 are arranged radially around the rotation center 1E of the rotation member 210. The arrangement center 1M coincides with the rotation center 1E of the rotation member 210.

[0114] The support member 20 supports the beverage can 10 by inserting the support member 20 into the beverage can 10, as shown by arrow 1G in FIG. As shown in FIG. 11, in this embodiment, a disc-shaped transmission member 50 is provided above the receiving gear 230G. The transmission member 50 meshes with a receiving gear 230G provided on each of the holding mechanisms 230, and transmits a rotational driving force to the receiving gear 230G, causing the support member 20 to rotate. The transmission member 50 does not necessarily have to be disposed above the receiving gear 230G, but may be disposed below the receiving gear 230G.

[0115] The transmission member 50 is disposed coaxially with the rotation member 210. In this embodiment, the rotation center 1F of the transmission member 50 is located on an extension of the rotation center 1E of the rotation member 210 (see FIG. 10). The transmission member 50 is connected to the plurality of support members 20. More specifically, the transmission member 50 is connected to the plurality of support members 20 via a receiving gear 230G and a shaft 230S. The transmission member 50 rotates to transmit a rotational driving force to each of the plurality of support members 20 .

[0116] The transmission member 50 rotates upon receiving a rotational driving force from a cylindrical rotating member 59 (see Figure 11) extending downward from the rotation center (central part in the radial direction) of the transmission member 50, and transmits the rotational driving force to each of the multiple support members 20. In this embodiment, as shown in FIG. 11, a second motor M2 is provided to rotate the rotary member 59, and the rotary member 59 rotates by receiving a driving force from the second motor M2.

[0117] The transmission member 50 rotates in the direction indicated by the arrow 1D in FIG. This causes the receiving gear 230G to rotate, and the support member 20 (beverage can 10) to rotate in the direction indicated by the arrow 1N. In this embodiment, the transmission member 50 rotates in the direction opposite to the direction indicated by the arrow 10A, which is the rotation direction of the rotation member 210. The transmission member 50 rotates around a rotation center 1F located at the radial center of the transmission member 50, and in this embodiment, this rotation center 1F coincides with the arrangement center 1M of the radially arranged support members 20.

[0118] The printing device 100 shown in FIG. 10 also includes a supply unit 510 to which beverage cans 10 are supplied. In the supply section 510, the beverage can 10 is attached to the support member 20. This allows the support member 20 to start supporting the beverage can 10. A plurality of inkjet heads 19 are provided downstream of the supply unit 510 in the rotation direction of the rotary member 210. In this configuration example, six inkjet heads 19 are provided.

[0119] Specifically, the six inkjet heads 19 include a first inkjet head 19C, a second inkjet head 19M, a third inkjet head 19Y, a fourth inkjet head 19K, a fifth inkjet head 19W, and a sixth inkjet head 19T. In the above (see FIG. 6), an example has been described in which four inkjet heads 19 are provided as one set of inkjet heads: a first inkjet head 19C, a second inkjet head 19M, a third inkjet head 19Y, and a fourth inkjet head 19K. The number of inkjet heads 19 is not particularly limited, and as in the configuration example shown in FIG. 10, the number of inkjet heads 19 provided may be any number other than four. The fifth inkjet head 19W and the sixth inkjet head 19T eject ink of, for example, white or special color. The first inkjet head 19C to the sixth inkjet head 19T form images on the beverage can 10 supported by the support member 20.

[0120] As described above, each of the six inkjet heads 19 forms an image on a beverage can 10 supported by the support member 20. The six inkjet heads 19 are aligned in the direction in which the beverage can 10 moves. In other words, the six inkjet heads 19 are aligned along the rotation direction of the rotating member 210. Furthermore, the six inkjet heads 19 are arranged radially around the rotation center 1E of the rotating member 210. Furthermore, as shown in Fig. 11, the inkjet heads 19 are arranged above the beverage can 10 and eject ink toward the beverage can 10 located below.

[0121] In this configuration example shown in Figures 10 and 11, similar to the configuration example shown in Figure 6, the inkjet head 19 (see Figure 11) is provided with a large outer diameter facing portion 191A that faces the large outer diameter region 11J and a small outer diameter facing portion 191B that faces the small outer diameter region 11K. In this configuration example, as in the configuration example shown in Figure 6, a large dot image 102 (not shown in Figures 10 and 11) is formed in the large outer diameter region 11J of the beverage can 10, and a small dot image 102 is formed in the small outer diameter region 11K of the beverage can 10.

[0122] In addition to this configuration, as in the configuration example shown in FIG. 4, two inkjet heads 19, an inkjet head 19L for large dot images and an inkjet head 19S for small dot images, may be provided for each color. Also, as in the configuration example shown in FIG. 7, two inkjet heads 19L for large dot images and one inkjet head 19S for small dot images may be provided for each color.

[0123] As shown in FIG. 10, in this configuration example, a light irradiation unit 751 is provided downstream of the six inkjet heads 19 in the rotation direction of the rotating member 210 (the conveyance direction of the beverage can 10). In this configuration example, the light irradiation unit 751 also irradiates the outer peripheral surface 11M of the beverage can 10 with light. This hardens the image 101 (not shown in FIGS. 10 and 11) on the outer peripheral surface 11M of the beverage can 10. In other words, the dot image 102 (not shown in FIGS. 10 and 11) on the outer peripheral surface 11M of the beverage can 10 hardens.

[0124] As the rotating member 210 rotates, the support member 20 (beverage can 10) passes through each of the multiple inkjet heads 19. Furthermore, the rotating member 210 temporarily stops rotating every time it rotates. In this configuration example, a plurality of beverage can stopping points 91 are also provided, and the support member 20 (beverage can 10) stops at each of these beverage can stopping points 91. In this configuration example, the rotating member 210 is rotated intermittently to transport the beverage can 10 along a predetermined circular path, and the transport of the beverage can 10 is temporarily stopped each time the beverage can 10 reaches each of the beverage can stopping points 91. In other words, in this embodiment, the rotating member 210 is rotated intermittently to cause the beverage can 10 to revolve, and the beverage can 10 is stopped temporarily each time the beverage can 10 reaches each of the beverage can stopping points 91.

[0125] Furthermore, in this configuration example, an inspection mechanism 92 as an example of an inspection means for inspecting the beverage cans 10 is provided between the supply unit 510 and the six inkjet heads 19. In this embodiment, an inspection mechanism 92 is provided upstream of the six inkjet heads 19, and inspects the beverage can 10 before the six inkjet heads 19 form an image.

[0126] The inspection mechanism 92 inspects, for example, whether the beverage can 10 is deformed. In this embodiment, if the inspection mechanism 92 determines that the beverage can 10 does not satisfy predetermined conditions (for example, if it determines that the beverage can 10 is deformed), an ejection mechanism 93, which is an example of an ejection means, ejects the beverage can 10 outside the printing device 100.

[0127] A protective layer forming section 770 is provided downstream of the light irradiating section 751 . As described above, the protective layer forming unit 770 applies paint onto the image 101 formed by the inkjet head 19 to form a transparent layer that covers the image 101. As a result, a transparent protective layer (not shown) is formed on the outermost layer of the beverage can 10. A removing section 780 is provided downstream of the protective layer forming section 770. In this removing section 780, the beverage can 10 is removed from the support member 20. The removed beverage can 10 is discharged to the outside of the printing apparatus 100.

[0128] A series of operations of the printing device 100 will be described with reference to FIG. In the printing device 100, first, the transmission member 50 starts to rotate in the direction indicated by the arrow 1D, and the support member 20 starts to rotate in the direction indicated by the arrow 1N. Then, in the supply section 510, the beverage can 10 conveyed from the upstream side is attached to the support member 20. As a result, the support member 20 starts to support the beverage can 10.

[0129] After the support member 20 starts to support the beverage can 10, the rotating member 210, which had been in a stopped state, rotates in the direction indicated by the arrow 10A in the figure by a predetermined angle and then stops again. As a result, the beverage can 10 reaches the inspection mechanism 92. In other words, in this case, the beverage can 10 revolves and reaches the inspection mechanism 92. Thereafter, the rotating member 210 rotates again by a predetermined angle, causing the beverage can 10 to revolve and reach the discharge mechanism 93. Thereafter, the rotary member 210 rotates again by a predetermined angle, causing the beverage can 10 to revolve and reach below the first inkjet head 19, which is the first inkjet head 19C.

[0130] Then, ink is ejected from this first inkjet head 19C toward the beverage can 10 which is positioned below and rotating, and an image 101 is formed on the outer surface of the beverage can 10 using ink of the first color. Specifically, a large dot image 102 is formed in the large outer diameter region 11J (see Figure 11), and a small dot image 102 is formed in the small outer diameter region 11K, thereby forming an image 101 in the first color of ink on the outer surface of the beverage can 10. Next, the rotating member 210 rotates and stops again, and the beverage can 10 stops below the second inkjet head 19M. In other words, the beverage can 10 revolves and stops, and the beverage can 10 stops below the second inkjet head 19M. Then, an image is formed using the second color ink by the second inkjet head 19M. Note that, in this case, similar to the above, large dot images 102 are formed in the large outer diameter region 11J, and small dot images are formed in the small outer diameter region 11K.

[0131] Furthermore, the beverage can 10 is moved to the third inkjet head 19Y, an image is formed by the third inkjet head 19Y, the beverage can 10 is moved to the fourth inkjet head 19K, and an image is formed by the fourth inkjet head 19K. Furthermore, the beverage can 10 is moved to the fifth inkjet head 19W, an image is formed by the fifth inkjet head 19W, the beverage can 10 is moved to the sixth inkjet head 19T, and an image is formed by the sixth inkjet head 19T. When forming an image using each of the third inkjet head 19Y to sixth inkjet head 19T, a large dot image 102 is formed in the large outer diameter region 11J, and a small dot image is formed in the small outer diameter region 11K.

[0132] Thereafter, the beverage can 10 passes through the light irradiation section 751 and the protective layer forming section 770 in this order, and then reaches the removal section 780. In the light emitting section 751, the image 101 formed on the outer peripheral surface 11M of the beverage can 10 is irradiated with light. In the protective layer forming section 770, paint is applied onto the image 101 formed on the outer peripheral surface 11M of the beverage can 10, forming a transparent layer that covers the image 101. As a result, a transparent protective layer (not shown) is formed on the outermost layer of the beverage can 10. In the removing section 780, the beverage can 10 is removed from the support member 20. The removed beverage can 10 is ejected to the outside of the printing apparatus 100.

[0133] In the explanation of the processing performed by the printing device 100 shown in Figures 10 and 11, the processing when the size of the dot image 102 is varied is described as an example, but the processing by the printing device 100 shown in Figures 10 and 11 is not limited to this. As in the above, processing may be performed in which the sizes of the dot images 102 are made different and the number of large dot images 102 is greater than the number of small dot images 102. Alternatively, the above process may be performed without varying the size of the dot images 102, but with all the dot images 102 remaining the same size, and only the number of dot images 102 in the circumferential direction of the beverage can 10 may be changed. In other words, the above process may be performed without varying the size of the dot images 102, but with all the dot images 102 remaining the same size, such that the number of dot images 102 located in the large outer diameter region 11J and aligned in the circumferential direction of the beverage can 10 is greater than the number of dot images 102 located in the small outer diameter region 11K and aligned in the circumferential direction of the beverage can 10.

[0134] In addition, in the printing device 100 shown in Figures 10 and 11, a case has been described in which a rotational driving force is transmitted from a single common member, the transmission member 50, to multiple support members 20, causing each of the support members 20 to rotate. The manner in which each support member 20 rotates is not limited to this, and for example, a drive motor (not shown) may be provided for each support member 20, and the support member 20 may be rotated by this drive motor provided for each support member 20. [Explanation of symbols]

[0135] 10... beverage can, 11... reduced diameter portion, 11A... one end, 11B... other end, 11X... large outer diameter portion, 11Y... small outer diameter portion, 19... inkjet head, 19L... inkjet head for large dot images, 19S... inkjet head for small dot images, 91... beverage can stopping point, 100... printing device, 102... dot image, 550E... rotation mechanism, 600... conveying mechanism

Claims

1. a rotating means for rotating a cylindrical beverage container in a circumferential direction, the beverage container having a tapered portion whose outer diameter decreases along the axial direction; an inkjet head disposed along the axial direction of the container and facing the outer peripheral surface of the container, for ejecting ink onto the outer peripheral surface of the rotating container to form a plurality of dot images on the outer peripheral surface; Equipped with forming the dot image so that the size of the dot image formed on the large outer diameter portion, which is a portion of the reduced diameter section where the outer diameter is large, is larger than the size of the dot image formed on the small outer diameter portion, which is a portion of the reduced diameter section where the outer diameter is small; Printing device.

2. a dot image formed by ink ejected from a portion of the inkjet head extending from one end to the other end in the axial direction of the container, the portion facing the large outer diameter portion, is larger than a dot image formed by ink ejected from a portion of the inkjet head facing the small outer diameter portion; The printing device of claim 1 .

3. the ejection frequency of ink ejected from the portion of the inkjet head facing the large outer diameter portion is higher than the ejection frequency of ink ejected from the portion of the inkjet head facing the small outer diameter portion; The printing device according to claim 2 .

4. a rotation speed of the container when ink is ejected from the portion of the inkjet head facing the large outer diameter portion is lower than a rotation speed of the container when ink is ejected from the portion of the inkjet head facing the small outer diameter portion; The printing device according to claim 2 .

5. As the inkjet head, a large dot image inkjet head for forming large dot images and a small dot image inkjet head for forming small dot images are separately provided, the large dot image inkjet head ejects ink onto the large outer diameter portion, and the small dot image inkjet head ejects ink onto the small outer diameter portion; The printing device of claim 1 .

6. A container transport means for transporting the container is further provided, a plurality of container stopping points are provided, the positions of which are different from each other in the direction in which the container is transported by the container transport means; The inkjet head is provided at each of the container stop locations, the container stopping position where the inkjet head for large dot images is provided is different from the container stopping position where the inkjet head for small dot images is provided; The printing device according to claim 5 .

7. a frequency of ink ejection into the container at the container stopping location where the inkjet head for large dot images is provided is higher than a frequency of ink ejection into the container at the container stopping location where the inkjet head for small dot images is provided; The printing device according to claim 6.

8. a rotation speed of the container at the container stopping location where the inkjet head for large dot images is provided is slower than a rotation speed of the container at the container stopping location where the inkjet head for small dot images is provided; The printing device according to claim 6.

9. the frequency of ink ejection when a dot image is formed on the large outer diameter portion is higher than the frequency of ink ejection when a dot image is formed on the small outer diameter portion; The printing device of claim 1 .

10. the rotation speed of the container when the dot image is formed on the large outer diameter portion is lower than the rotation speed of the container when the dot image is formed on the small outer diameter portion; The printing device of claim 1 .

11. A beverage container having a cylindrical shape and a tapered portion whose outer diameter decreases along the axial direction, an image formed on the outer peripheral surface of the container, the image being composed of a plurality of dot images; a size of a dot image formed on a large outer diameter portion, which is a portion of the reduced diameter portion where the outer diameter is large, is larger than a size of a dot image formed on a small outer diameter portion, which is a portion of the reduced diameter portion where the outer diameter is small container.

12. the number of the dot images formed on the large outer diameter portion and aligned in the circumferential direction of the large outer diameter portion is greater than the number of the dot images formed on the small outer diameter portion and aligned in the circumferential direction of the small outer diameter portion; 12. The container of claim 11.

13. A method for manufacturing a beverage container having a cylindrical shape and a tapered portion whose outer diameter decreases along the axial direction, the beverage container having an image formed on its outer peripheral surface, Rotating the container in a circumferential direction; an ink jet head disposed along the axial direction of the container and facing the outer peripheral surface of the container ejects ink onto the outer peripheral surface of the rotating container, thereby forming a plurality of dot images on the outer peripheral surface; When forming the plurality of dot images on the outer peripheral surface, the dot images are formed so that the size of the dot images formed on a large outer diameter portion, which is a portion of the reduced diameter section where the outer diameter is large, is larger than the size of the dot images formed on a small outer diameter portion, which is a portion of the reduced diameter section where the outer diameter is small. A method for manufacturing beverage containers.

Images