Image forming device

Abstract

To vary an irradiation amount of light emitted to an image for each of the images formed by image formation means.SOLUTION: In an image formation device, an irradiation amount of ultraviolet light from a light source 13 provided while corresponding to an ink jet head 11M for magenta and an ink jet head 11K for black is larger than an irradiation amount of ultraviolet light from a light source 13 provided while corresponding to an ink jet head 11C for cyan and an ink jet head 11Y for yellow.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] Patent Document 1 discloses a process in which a white layer is formed on the surface of a can body using a white inkjet head, and then ultraviolet light is irradiated using an irradiation lamp. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-83480 Summary of the Invention [Problem to be solved by the invention]

[0004] When forming an image on a can body, one possible mode is to provide a curing means for each image forming means, and each time an image is formed on the can body, light such as ultraviolet light is irradiated onto the can body to harden the image. Here, if the amount of light irradiated by each curing means is the same, it may happen that the amount of light irradiated is too much for the image that you do not want to cure, or conversely, the amount of light irradiated is insufficient for the image that you do want to cure. An object of the present invention is to make it possible to vary the amount of light irradiated onto an image for each image formed by an image forming means. [Means for solving the problem]

[0005] The image forming device to which the present invention is applicable comprises a plurality of image forming means for forming an image on a can body, and a curing means provided to correspond to each of the plurality of image forming means for irradiating light onto the can body on which an image has been formed by the image forming means to harden the image, wherein the amount of light irradiated onto the can body by one curing means included in the plurality of curing means is different from the amount of light irradiated onto the can body by another curing means included in the plurality of curing means.

[0006] Here, the irradiation time during which the one hardening means irradiates the can body with light may be different from the irradiation time during which the other hardening means irradiates the can body with light, so that the amount of light irradiated by the one hardening means to the can body may be different from the amount of light irradiated by the other hardening means to the can body. In addition, the output when the one curing means irradiates light onto the can body may be different from the output when the other curing means irradiates light onto the can body, so that the amount of light irradiated onto the can body by the one curing means is different from the amount of light irradiated onto the can body by the other curing means. The plurality of image forming means may include an image forming means that forms an image including a character image on the can body, and an image forming means that forms an image not including a character image on the can body, and the amount of light irradiated by the curing means provided corresponding to the image forming means that forms the image including the character image may be greater than the amount of light irradiated by the curing means provided corresponding to the image forming means that forms the image not including the character image. In addition, the irradiation of light onto the can body by the curing means provided corresponding to the image forming means that forms an image including the character image may be performed before the irradiation of light onto the can body by the curing means provided corresponding to the image forming means that forms an image that does not include the character image. In addition, the image forming means and the curing means corresponding to the image forming means may be provided in multiple sets, and processing by each set may be performed in sequence. Of the sequential irradiation of light onto the can body, the irradiation of light by the curing means corresponding to the image forming means that forms an image including the character image may be performed first. In addition, the amount of light irradiated onto the can body by the curing means provided corresponding to the image forming means that forms a black image on the can body may be greater than the amount of light irradiated onto the can body by the curing means provided corresponding to the image forming means that forms an image of a color other than black on the can body.

[0007] In addition, the irradiation of light onto the can body by the curing means provided corresponding to the image forming means that forms the black image may be performed before the irradiation of light onto the can body by the curing means provided corresponding to the image forming means that forms the image of a color other than black. In addition, the image forming means and the curing means corresponding to the image forming means may be provided in multiple sets, and processing by each set may be performed in sequence.Of the sequential irradiation of light onto the can body, the irradiation of light by the curing means corresponding to the image forming means that forms the black image may be performed first. The device may further include a blocking section that is positioned at a position opposite the curing means when the can body is not positioned at the position opposite the curing means and blocks light from the curing means. In addition, the blocking portion may be configured to move in conjunction with the moving can body, and may be positioned at the opposing position when the can body is not positioned at the opposing position, and may be positioned at a location away from the opposing position when the can body is positioned at the opposing position. The curing means may be arranged on the opposite side to the image forming means, with the can body arranged in a position facing the image forming means therebetween. In addition, when the can body is not positioned opposite the image forming means, a blocking section may be provided that is positioned between the image forming means and the curing means and blocks light from traveling from the curing means to the image forming means. [Effects of the Invention]

[0008] According to the present invention, the amount of light irradiated onto an image can be made different for each image formed by the image forming means. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a top view of the image forming apparatus. [Figure 2] 2 is a view of the image forming unit as viewed from the direction indicated by the arrow II in FIG. 1. [Figure 3] FIG. 3 is a diagram showing a state in which the can body has moved from the state shown in FIG. 2 and is positioned between the stopping points. [Figure 4] 3A and 3B are diagrams showing an example of an image formed by an image forming unit. [Figure 5] FIG. 10 is a diagram showing another example of the configuration of the image forming unit. [Figure 6] FIG. 10 is a diagram showing another example of the configuration of the image forming unit. [Figure 7] FIG. 10 is a diagram showing another example of an image formed on a can body. [Figure 8] 10(A) to 10(D) are diagrams showing other examples of images formed on a can body. [Figure 9] FIG. 10 is a diagram showing another example of an image formed on a can body. [Figure 10] 10(A) to 10(D) are diagrams showing other examples of images formed on a can body. [Figure 11] FIG. 10 is a diagram showing another example of an image formed on a can body. [Figure 12] 10(A) to 10(D) are diagrams showing other examples of images formed on a can body. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a top view of an image forming apparatus 1 according to this embodiment. The image forming apparatus 1 of this embodiment is provided with a can body supply section 510 to which can bodies 10 are supplied. In this can body supply section 510, the can bodies 10 are attached (supplied) to a support member 20 that supports the can bodies 10. The support member 20 is formed in a cylindrical shape, and the support member 20 is inserted into the cylindrical can body 10, and the can body 10 is attached to the support member 20.

[0011] The image forming apparatus 1 is also provided with a can body discharge section 520 where the can body 10 is discharged after the image has been formed. In the can body discharge section 520, the can body 10 is removed from the support member 20 and discharged to the outside of the image forming apparatus 1. In this embodiment, a can body moving mechanism 100 is provided as an example of a can body moving means for moving the can body 10.

[0012] The can body moving mechanism 100 moves the can body 10 so that the can body 10 moves around a predetermined center 30. Furthermore, the can body moving mechanism 100 stops the can body 10 at each of the plurality of stopping points 40. More specifically, the can body 10 stops below each of the plurality of inkjet heads 11 (details will be described later).

[0013] In this embodiment, the can body moving mechanism 100 is provided with a disk-shaped rotating member 110 that rotates around a center 30 as the center of rotation. In this embodiment, the rotating member 110 supports a plurality of support members 20 (can bodies 10). More specifically, in this embodiment, a connecting member 117 is provided to connect the rotating member 110 and the supporting member 20 , and the supporting member 20 is supported by the rotating member 110 via this connecting member 117 . Each of the connection members 117 protrudes outward in the radial direction of the rotation member 110 from the outer circumferential surface 110A of the rotation member 110. The connection members 117 are also arranged radially around the center 30.

[0014] In this embodiment, a support member 20 is attached to the tip of each of the connecting members 117, and further, in this embodiment, the can body 10 is supported by the support member 20. 1, the multiple support members 20 (can bodies 10) are arranged side by side in the circumferential direction of the rotating member 110. The multiple support members 20 (can bodies 10) are also arranged radially around the center 30.

[0015] The can body moving mechanism 100 is provided with a first motor M1 that rotates the rotating member 110. Furthermore, in this embodiment, a second motor (not shown) is provided corresponding to each support member 20 and rotates the support member 20 (can body 10) in the circumferential direction. This second motor is housed, for example, inside the connecting member 117. Note that the second motor may also be provided, for example, inside the rotating member 110. When the second motor is provided inside the rotating member 110, a rotational driving force is transmitted from this second motor provided inside the rotating member 110 to the support member 20 via a driving force transmission member such as a gear.

[0016] In this embodiment, a control device 60 that controls each part of the image forming apparatus 1 is also provided. The control device 60 controls the rotation of the first motor M1, causing the rotating member 110 to intermittently rotate. In this embodiment, the intermittent rotation of the rotating member 110 causes the can body 10 to move and stop at the stopping point 40 repeatedly. As a result, in this embodiment, the can body 10 stops below each of the inkjet heads 11, which will be described later.

[0017] In this embodiment, the second motor is driven, and when the can body 10 is positioned at least below the inkjet head 11, the support member 20 is rotated. As a result, when an image is formed by the inkjet head 11, the can body 10 rotates in the circumferential direction, and an image is formed all around the can body 10.

[0018] In this embodiment, the can body 10 (support member 20) moves along a predetermined circular path R1 (hereinafter referred to as "can body movement path R1") as a result of the rotation of the rotating member 110. In other words, in this embodiment, the can body 10 moves around the center 30 as a result of the rotation of the rotating member 110. Here, in this embodiment, "the can body 10 moves along a circular path" does not mean that the can body 10 moves around the entire circumference of the circular path, but rather that the can body 10 moves along at least a portion of the circular path.

[0019] An image forming section 120 is provided downstream of the can body supply section 510 in the direction of movement of the can bodies 10. In the image forming section 120, images are formed on the can bodies 10. The image forming unit 120 is provided with a plurality of inkjet heads 11. The inkjet heads 11, which are an example of an image forming means, are provided corresponding to each of the stopping points 40, and form images on the can bodies 10 located at the stopping points 40. As a result, in this embodiment, an image is formed on the outer peripheral surface 10A of the can body 10.

[0020] In this embodiment, ink is ejected from the inkjet head 11 onto the can body 10 located below, thereby forming an image on the can body 10. In this embodiment, a so-called inkjet printing method is used to form an image on the can body 10 that is positioned at the stopping point 40 and rotating in the circumferential direction.

[0021] In this embodiment, inkjet heads 11 for four colors are provided as the inkjet heads 11. Specifically, an inkjet head 11C that ejects cyan ink, an inkjet head 11M that ejects magenta ink, an inkjet head 11Y that ejects yellow ink, and an inkjet head 11K that ejects black ink are provided.

[0022] It should be noted that other inkjet heads 11 that eject ink of colors other than the above four colors, such as an inkjet head 11 that ejects white ink or an inkjet head 11 that ejects transparent ink, may also be provided. In addition, in this embodiment, an example in which four inkjet heads 11 are provided will be described, but the number of inkjet heads 11 to be installed is not particularly limited, and a number other than four inkjet heads 11 may be provided.

[0023] The four inkjet heads 11, inkjet heads 11C to 11K, form images on the can body 10 using ultraviolet curable ink. In other words, the four inkjet heads 11 form images on the can body 10 using photocurable ink that hardens when irradiated with light such as ultraviolet light. Here, image formation by inkjet printing refers to image formation performed by ejecting ink from inkjet head 11 and depositing the ink on can body 10. For image formation by inkjet printing, known methods can be used, such as a piezo method, a thermal (bubble) method, or a continuous method.

[0024] Fig. 2 is a diagram of the image forming unit 120 as viewed from the direction indicated by arrow II in Fig. 1. In other words, Fig. 2 is a diagram of the image forming unit 120 as viewed from the side of the image forming apparatus 1. When the image forming unit 120 is viewed from the direction indicated by the arrow II in FIG. 1, the side of each of the inkjet heads 11 and the like shown in FIG. 1 can also be seen, but FIG. 2 shows the inkjet head 11, the can body 10, and the light source 13 as viewed from the axial direction.

[0025] In this embodiment, as shown in Fig. 2, a plurality of light sources 13 are provided as an example of a curing means. The light sources 13 are provided corresponding to each of the plurality of stopping points 40. In other words, the light sources 13 are provided corresponding to each of the plurality of inkjet heads 11. The light source 13 is configured by, for example, an LED (Light Emitting Diode), but the light source 13 may be configured by a material other than an LED.

[0026] The light source 13 irradiates the can body 10, on which an image has been formed by the inkjet head 11, with ultraviolet light (light with a wavelength in the ultraviolet range) (hereinafter referred to as "ultraviolet light"), which is an example of light, thereby hardening the image formed on the can body 10. In this embodiment, the optical path of the ultraviolet light traveling from the light source 13 toward the can body 10 is linear. As a result, in this embodiment, energy consumption can be reduced compared to when the ultraviolet light is diffused, and the ultraviolet light can be prevented from traveling toward any destination other than the can body 10.

[0027] The light source 13 is provided on the opposite side of the can body movement path R1, which is the path along which the can body 10 moves, from the side on which the inkjet head 11 is installed. In other words, the light source 13 is disposed on the opposite side of the can body 10 from the side on which the inkjet head 11 is installed, with the can body 10 disposed in a position facing the inkjet head 11 therebetween. Light source 13 irradiates can body 10, which is stopped at stopping point 40 and rotating in the circumferential direction, from below with ultraviolet light, for example. This causes the image formed on outer peripheral surface 10A of can body 10 to harden.

[0028] In this embodiment, as shown in FIG. 2, a blocking portion 14 that blocks ultraviolet light from the light source 13 is provided. 1, the blocking portion 14 is disposed between adjacent can bodies 10. In other words, the blocking portion 14 is disposed between adjacent support members 20. The blocking portion 14 is fixed to the rotating member 110 by a connecting member 118 (see FIG. 1). Therefore, in this embodiment, when the can body 10 moves due to the rotation of the rotating member 110, the blocking portion 14 also moves. In other words, in this embodiment, the blocking portion 14 moves in conjunction with the can body 10.

[0029] FIG. 3 is a diagram showing a state in which the can body 10 has moved from the state shown in FIG. 2 and is now positioned between the stopping points 40. In FIG. 3, the blocking portion 14 of this embodiment is located at a position facing the light source 13 when the can body 10 is not located at this position. As a result, the light from the light source 13 is blocked by the blocking portion 14. More specifically, when the can body 10 is not positioned opposite the inkjet head 11, the blocking portion 14 is positioned between the inkjet head 11 and the light source 13, and blocks the light from the light source 13 toward the inkjet head 11.

[0030] In this embodiment, when the can body 10 is not located at the stopping point 40, the blocking portion 14 is located on the path R2 along which the ultraviolet light travels from the light source 13 toward the inkjet head 11 located opposite the light source 13. This prevents ultraviolet light from the light source 13 from reaching the inkjet head 11, making it less likely that problems such as ink curing will occur in the inkjet head 11.

[0031] In this embodiment, the blocking portion 14 is made up of a plate-like member arranged along the horizontal direction. As described above, the blocking portion 14 moves in conjunction with the moving can body 10. Specifically, as described above, the blocking portion 14 is fixed to the rotating member 110 (see FIG. 1 ) to which the can body 10 is fixed, and as a result, the blocking portion 14 moves in conjunction with the can body 10.

[0032] As described above, when the can body 10 is not positioned opposite the inkjet head 11 , the blocking portion 14 is positioned at this opposite position and blocks the ultraviolet light emitted from the light source 13 toward the inkjet head 11 . On the other hand, as shown in Figure 2, when the can body 10 is positioned opposite the inkjet head 11, the blocking portion 14 is positioned at a location away from this opposite position. This allows the light source 13 to irradiate the can body 10 with ultraviolet light. In this embodiment, as shown in FIG. 3, a plurality of blocking portions 14 are provided, each corresponding to one of the plurality of inkjet heads 11.

[0033] The light source 13 will be further described with reference to FIG. In this embodiment, a plurality of light sources 13 are provided. In this embodiment, the amount of ultraviolet light irradiated onto the can body 10 from each light source 13 is not the same, and the amount of ultraviolet light irradiated onto the can body 10 by one light source 13 included in the multiple light sources 13 is different from the amount of ultraviolet light irradiated onto the can body 10 by another light source 13 included in the multiple light sources 13.

[0034] Here, an image that should not be blurred, such as a character image or a code image such as a barcode, may be formed on the can body 10. Furthermore, in order to widely cover the surface of the can body 10 with an image, the background image or the like may be intentionally formed on the can body 10 with some blurring.

[0035] In this case, it is preferable to make the amount of ultraviolet light irradiated by the light source 13 provided corresponding to the inkjet head 11 that forms an image on the can body 10 that you do not want to bleed (hereinafter referred to as the "first irradiation amount") greater than the amount of ultraviolet light irradiated by the light source 13 provided corresponding to the inkjet head 11 that forms an image on the can body 10 that you do want to bleed (hereinafter referred to as the "second irradiation amount").

[0036] As described above, when the amount of ultraviolet light irradiated onto the can body 10 by one light source 13 is made different from the amount of ultraviolet light irradiated onto the can body 10 by another light source 13, the first irradiation amount can be made greater than the second irradiation amount. By making the first dose greater than the second dose, bleeding can be suppressed for images such as character images and code images where bleeding is not desired, and the spread of the dot images that make up an image can be ensured for images such as background images where bleeding and spreading are intentionally desired.

[0037] In the example shown in FIG. 2, the amount of ultraviolet light emitted by the light sources 13 provided corresponding to the magenta inkjet head 11M and the black inkjet head 11K is greater than the amount of ultraviolet light emitted by the light sources 13 provided corresponding to the cyan inkjet head 11C and the yellow inkjet head 11Y. In this case, bleeding of images formed by the magenta inkjet head 11M and the black inkjet head 11K can be suppressed. Furthermore, the dot images that make up the image formed by the cyan inkjet head 11C and the yellow inkjet head 11Y spread and bleed.

[0038] In order to make the amount of ultraviolet light irradiated onto the can body 10 by one light source 13 different from the amount of ultraviolet light irradiated onto the can body 10 by another light source 13, as in this embodiment, for example, multiple light sources 13 with the same output are prepared, and the irradiation time for which one light source 13 irradiates the can body 10 with ultraviolet light is made different from the irradiation time for which the other light sources 13 irradiate the can body 10 with ultraviolet light. Specifically, for example, by controlling the on / off of the light source 13 and making the lighting time of one light source 13 different from the lighting time of another light source 13, the amount of ultraviolet light irradiated onto the can body 10 by one light source 13 is made different from the amount of ultraviolet light irradiated onto the can body 10 by the other light source 13. In this way, when the light source 13 is controlled to be turned on and off, energy consumption is reduced compared to when the light source 13 is left on all the time.

[0039] Furthermore, for example, by providing a retractable shutter member and moving this shutter member back and forth along the optical path of the ultraviolet light, the amount of ultraviolet light irradiated onto the can body 10 by one light source 13 can be made different from the amount of ultraviolet light irradiated onto the can body 10 by another light source 13. Also, for example, a slit may be provided to allow ultraviolet light to pass through, and the width of this slit may be widened or narrowed to make the amount of ultraviolet light irradiated onto the can body 10 by one light source 13 different from the amount of ultraviolet light irradiated onto the can body 10 by another light source 13. In addition, for example, the distance between the can body movement path R1 and the light source 13 may be made different for each light source 13, thereby making the amount of ultraviolet light irradiated onto the can body 10 by one light source 13 different from the amount of ultraviolet light irradiated onto the can body 10 by another light source 13.

[0040] Also, for example, in an image forming device 1 in which each can body 10 moves individually, the amount of ultraviolet light irradiated onto the can body 10 by one light source 13 may be made different from the amount of ultraviolet light irradiated onto the can body 10 by another light source 13 by varying the stopping time of the can body 10 at the stopping point 40. More specifically, for example, image forming apparatus 1 may be provided with a plurality of moving bodies each having a drive source and capable of moving individually, and each can body 10 may be moved by these moving bodies. In this case, by varying the stopping time of the moving body at each stopping point 40, the amount of ultraviolet light irradiated onto the can body 10 by one light source 13 can be made different from the amount of ultraviolet light irradiated onto the can body 10 by another light source 13.

[0041] Furthermore, when the amount of ultraviolet light irradiated onto the can body 10 by one light source 13 is made different from the amount of ultraviolet light irradiated onto the can body 10 by another light source 13, for example, the output when one light source 13 irradiates ultraviolet light onto the can body 10 may be made different from the output when another light source 13 irradiates ultraviolet light onto the can body 10. If the output of one light source 13 when irradiating the can body 10 with ultraviolet light is to be different from the output of another light source 13 when irradiating the can body 10 with ultraviolet light, for example, multiple types of light sources 13 with different outputs are prepared. A light source 13 with a high output is installed at a stopping point 40 where it is desired to increase the amount of ultraviolet light irradiated onto the can body 10, and a light source 13 with a low output is installed at a stopping point 40 where it is desired to decrease the amount of ultraviolet light irradiated onto the can body 10.

[0042] Alternatively, for example, the amount of power supplied to each light source 13 may be varied for each light source 13, thereby making the amount of ultraviolet light irradiated onto the can body 10 by one light source 13 different from the amount of ultraviolet light irradiated onto the can body 10 by another light source 13. In addition, when the amount of ultraviolet light irradiated onto the can body 10 by one light source 13 is made different from the amount of ultraviolet light irradiated onto the can body 10 by another light source 13, both the irradiation time and output may be made different. Specifically, for example, the irradiation time and output when one light source 13 irradiates ultraviolet light onto the can body 10 may be different from the irradiation time and output when another light source 13 irradiates ultraviolet light onto the can body 10.

[0043] The "irradiation amount" can be calculated by multiplying the irradiation time by the output of the light source 13, and when the irradiation amount of ultraviolet light irradiated onto the can body 10 by one light source 13 is different from the irradiation amount of ultraviolet light irradiated onto the can body 10 by another light source 13, it can be said that these products are different from each other. Furthermore, the concept of "irradiance amount" includes the possibility of zero. Even if the output or irradiation time of one of the first and second light sources 13 is zero and the output or irradiation time of the other light source 13 is not zero, it can be said that the irradiation amount of ultraviolet light irradiated onto the can body 10 by the first light source 13 is different from the irradiation amount of ultraviolet light irradiated onto the can body 10 by the other light source 13.

[0044] In addition, in this embodiment, as shown in Figure 2, a downstream light source 19 is provided downstream of the image forming unit 120 in the movement direction of the can body 10, which irradiates ultraviolet light onto the can body 10 after the image has been formed by the image forming unit 120. This downstream light source 19 is a light source for finishing, and in this embodiment, the amount of ultraviolet light emitted by this downstream light source 19 is greater than the amount of ultraviolet light emitted by each of the light sources 13. More specifically, in this embodiment, the output of the downstream light source 19 is greater than the output of each of the light sources 13, and as a result, the amount of ultraviolet light irradiated by the downstream light source 19 is greater than the amount of ultraviolet light irradiated by each of the light sources 13.

[0045] In this embodiment, as indicated by the reference symbol 2X in FIG. 2, a stop position 40 where no light source 13 is installed is provided between the image forming unit 120 and the downstream light source 19. In other words, between the image forming unit 120 and the downstream light source 19, there is provided a stop portion 40 where no ultraviolet light is irradiated. In this embodiment, the number of stopping points 40 where no light source 13 is installed is one, but it may be two or more.

[0046] Between the time when the image is formed by the image forming unit 120 and the time when the can body 10 reaches the downstream light source 19, it may be desired to intentionally blur the dot image that constitutes the image on the can body 10 and expand the dot image. In this case, if there are no stopping points 40 where no light source 13 is installed and ultraviolet light is irradiated by the downstream light source 19 immediately after the image is formed, the extent of the dot image spreading becomes small. In contrast to this, if there is one or more stop points 40 where no light source 13 is installed, as in this embodiment, time is ensured for the dot image to spread, and the dot image spreads further.

[0047] When irradiation of ultraviolet light by the downstream light source 19 is completed, the can body 10 moves to the can body discharge section 520 (see FIG. 1). In this embodiment, the can body 10 is removed from the support member 20 at the can body discharge section 520, and the can body 10 is discharged to the outside of the image forming apparatus 1. The can body 10 discharged outside the image forming apparatus 1 is sequentially transported to, for example, a coating process in which a transparent paint is applied to the outer peripheral surface 10A of the can body 10, and a heating process in which the can body 10 coated with the transparent paint is heated. When the transparent coating is applied to the outer peripheral surface 10A of the can body 10, a protective layer is formed on the outermost layer of the can body 10. Furthermore, this protective layer is hardened by heating the can body 10 in the heating step.

[0048] FIG. 4 is a diagram showing an example of an image formed by the image forming unit 120. As shown in FIG. In this embodiment, an image 70 shown in Fig. 4 is formed over the entire outer peripheral surface 10A of the can body 10. Specifically, the image 70 is formed so that a long side 71 of the image 70 shown in Fig. 4 is aligned along the circumferential direction of the can body 10, and a short side 72 of the image 70 shown in Fig. 4 is aligned along the axial direction of the can body 10. The image 70 includes a background image 91 covering the surface of the can body 10, a character image 92, and a code image 93 configured by a barcode or the like. In this embodiment, the character images 92 include a vertical character image 92A in which characters are arranged along the axial direction of the can body 10, a horizontal character image 92B in which characters are arranged along the circumferential direction of the can body 10, and a numeric character image 92C in which characters representing numbers are arranged.

[0049] In this embodiment, the background image 91 is made up of cyan ink and yellow ink, as indicated by reference symbol 4B in Fig. 4. The inks forming the background image 91 are mixed in a ratio of 50% cyan and 50% yellow. Furthermore, the vertical character image 92A and the horizontal character image 92B included in the character image 92 are made of black ink. The ink composition ratio forming the vertical character image 92A and the horizontal character image 92B is 100% black.

[0050] In this embodiment, the code image 93 is also made of black ink, and the ink blend ratio for forming the code image 93 is 100% black. Furthermore, in this embodiment, the numeric character image 92C included in the character image 92 is composed of magenta ink, cyan ink, and black ink. The ink composition ratio of the inks forming this numeric character image 92C is 80% magenta, 10% cyan, and 10% black.

[0051] In this case, in this embodiment, the irradiation amount of ultraviolet light at the stopping points 40 where the cyan inkjet head 11C, the magenta inkjet head 11M, the yellow inkjet head 11Y, and the black inkjet head 11K are installed is set to 75%, 100%, 25%, and 100%, respectively, as shown by the symbol 4D. Here, each of these irradiation amounts is the irradiation amount when the irradiation amount of ultraviolet light from the light source 13 corresponding to the black ink, which has the greatest irradiation amount, is set to 100%.

[0052] As described above, in this embodiment, there is a desire to reduce the amount of ultraviolet light applied to the background image 91 to intentionally cause the ink to bleed. For this reason, in this embodiment, the amount of ultraviolet light irradiation is reduced to 25% for the yellow ink that forms the background image 91, as shown by the reference symbol 4D.

[0053] Furthermore, for cyan that constitutes the background image 91, the irradiation amount of ultraviolet light is not set to 100%, but is set to 75%, which is less than 100%. Since cyan ink is also used to form the numeric character image 92C, bleeding is not tolerated to a large extent. For this reason, the exposure dose for cyan ink is not set to a small value like 25%, which is the exposure dose for yellow, but is set to 75%, which is lower than 100%.

[0054] Furthermore, in this embodiment, since magenta and black inks are used to form vertical character image 92A, horizontal character image 92B, and numeric character image 92C, which are examples of character image 92, the amount of ultraviolet light irradiation is increased to 100%. Furthermore, for magenta and black, since they are not used in forming the background image 91, the amount of ultraviolet light irradiation is increased to 100%. In this embodiment, black is also used to form the code image 93. To prevent bleeding of the code image 93, the amount of ultraviolet light applied to black is set to 100%.

[0055] In this embodiment, the multiple inkjet heads 11 (see Figure 2) include an inkjet head 11 that forms an image including a character image 92 on the can body 10, and an inkjet head 11 that forms an image not including a character image 92 on the can body 10. Specifically, magenta, black and cyan inkjet heads 11M, 11K and 11C are provided as inkjet heads 11 for forming an image including the character image 92 on the can body 10. In addition, as the inkjet head 11 that forms an image that does not include the character image 92 on the can body 10, a yellow inkjet head 11Y is provided.

[0056] In this embodiment, the amount of ultraviolet light emitted by the light source 13 provided corresponding to each of the magenta, black, and cyan inkjet heads 11M, 11K, and 11C, which form images including the character image 92, is set to be greater than the amount of ultraviolet light emitted by the light source 13 provided corresponding to the yellow inkjet head 11Y, which forms images not including the character image 92. Specifically, the irradiation amount of ultraviolet light from the light sources 13 provided corresponding to each of the magenta, black, and cyan inkjet heads 11M, 11K, and 11C that form images including the character image 92 is 100%, 100%, and 75%, respectively, as shown by symbol 4D in Figure 4. In contrast to this, the amount of ultraviolet light emitted by the light source 13 provided in correspondence with the yellow inkjet head 11Y that forms an image that does not include the character image 92 is 25%.

[0057] In this embodiment, a black inkjet head 11K is provided as the inkjet head 11 that forms an image including the code image 93 on the can body 10. In this processing example, inkjet heads 11C, 11M, and 11Y for cyan, magenta, and yellow are provided as inkjet heads 11 for forming an image not including a code on the can body 10.

[0058] In this embodiment, the amount of ultraviolet light emitted by the light source 13 provided corresponding to the black inkjet head 11K, which forms an image including the code image 93, is 100%, and the amount of ultraviolet light emitted by the light source 13 provided corresponding to the cyan and yellow inkjet heads 11C and 11Y, which form images not including the code image 93, is 75% and 25%, respectively. That is, the amount of ultraviolet light emitted by the light source 13 provided corresponding to the black inkjet head 11K, which forms an image including the code image 93, is greater than the amount of ultraviolet light emitted by the light source 13 provided corresponding to the cyan and yellow inkjet heads 11C and 11Y, which form images not including the code image 93.

[0059] Furthermore, in this embodiment, the amount of ultraviolet light irradiated onto the can body 10 by the light source 13 provided corresponding to the inkjet head 11K that forms a black image is greater than the amount of ultraviolet light irradiated onto the can body 10 by the light source 13 provided corresponding to the inkjet heads 11C and 11Y that form images of colors other than black, cyan and yellow, on the can body 10. Specifically, the irradiation amount of ultraviolet light irradiated onto the can body 10 by the light source 13 provided corresponding to the inkjet head 11K that forms a black image is 100%. In contrast, the irradiation amounts of ultraviolet light irradiated onto the can body 10 by the light source 13 provided corresponding to the inkjet heads 11C and 11Y that form cyan and yellow images on the can body 10 are 75% and 25%, respectively.

[0060] In forming the character image 92 and the code image 93, at least black ink is often used. Therefore, by increasing the amount of ultraviolet light emitted by the light source 13 provided corresponding to the inkjet head 11K that forms a black image on the can body 10 compared to the amount of ultraviolet light emitted by the light source 13 provided corresponding to the inkjet head 11 that forms an image of a color other than black on the can body 10, bleeding of the character image 92 and the code image 93 can be suppressed.

[0061] FIG. 5 is a diagram showing another example of the configuration of the image forming unit 120. In FIG. In this configuration example, in the direction of movement of the can body 10, the black inkjet head 11K is arranged second from the downstream side, and the yellow inkjet head 11Y is arranged on the most downstream side. In this configuration example, the light source 13 corresponding to the black inkjet head 11K, which forms an image including the character image 92 and the code image 93, irradiates the can body 10 with ultraviolet light before the light source 13 corresponding to the yellow inkjet head 11Y, which forms an image not including the character image 92 and the code image 93, irradiates the can body 10 with ultraviolet light.

[0062] In the above example, since yellow is used to form the background image 91, it is preferable to reduce the amount of ultraviolet light irradiated onto the image formed with this yellow ink. In this case, if the yellow inkjet head 11Y is positioned upstream of the black inkjet head 11K as shown in FIG. 2, when the formed yellow image reaches the black inkjet head 11K, the amount of ultraviolet light irradiated onto the yellow image increases, accelerating the curing of the yellow image.

[0063] More specifically, when it is desired to spread the dot images constituting the yellow image over a longer period of time, if a light source 13 with a large irradiation amount corresponding to the black inkjet head 11K is provided immediately downstream of the yellow inkjet head 11Y as shown in FIG. 2, the light source 13 will accelerate the hardening of the dot images constituting the yellow image. In contrast, as shown in FIG. 5, if the black inkjet head 11K is located upstream of the yellow inkjet head 11Y, the yellow image will not be affected by the light source 13 provided corresponding to the black inkjet head 11K.

[0064] In other words, in the configuration example shown in Figure 5, the light source 13 provided corresponding to the inkjet head 11K that forms a black image irradiates the can body 10 with ultraviolet light before the light source 13 provided corresponding to the inkjet head 11Y that forms an image of yellow, which is an example of a color other than black, irradiates the can body 10 with ultraviolet light. This suppresses irradiation of the yellow image with ultraviolet light, making it easier to ensure the spread of the dot images that make up the yellow image.

[0065] FIG. 6 is a diagram showing another example of the configuration of the image forming unit 120. In FIG. In this configuration example, the black inkjet head 11K is located on the most upstream side. In this embodiment, a plurality of pairs of inkjet heads 11 and light sources 13 corresponding to the inkjet heads 11 are provided, and processing by each pair is carried out in sequence. In this configuration example shown in FIG. 6, among the sequential irradiation of ultraviolet light onto the can body 10, irradiation of ultraviolet light by the light source 13 provided corresponding to the inkjet head 11K that forms a black image is performed first.

[0066] In other words, in this configuration example shown in Figure 6, among the sequential irradiation of ultraviolet light onto the can body 10, the irradiation of ultraviolet light by the light source 13 provided corresponding to the black inkjet head 11K, which forms an image including the character image 92, is performed first. In the embodiment described with reference to FIG. 4, the amount of ultraviolet light emitted by the light source 13 provided corresponding to the black inkjet head 11K is the greatest.

[0067] In the configuration example shown in FIG. 6, the light source 13 with the greatest irradiation amount is arranged on the most upstream side in the direction of movement of the can body 10, and irradiation of ultraviolet light by this light source 13 is carried out first. This prevents images that require less irradiation of ultraviolet light than black images, such as yellow images and cyan images, from being affected by the light source 13 provided corresponding to the black inkjet head 11K.

[0068] In the configuration example shown in FIG. 6, the inkjet head 11 and the light source 13 are arranged in descending order of the amount of ultraviolet light emitted by the light source 13. In the embodiment shown in FIG. 4, as indicated by the reference symbol 4D, the irradiation amounts of ultraviolet light are in the order of black, magenta, cyan, and yellow, or magenta, black, cyan, and yellow.

[0069] In this case, for example, as shown in FIG. 6, it is preferable that the inkjet head 11 and the light source 13 provided corresponding to this inkjet head 11 are arranged in the order of black, magenta, cyan, and yellow from the upstream side to the downstream side in the movement direction of the can body 10. Alternatively, although not shown, it is preferable that the inkjet heads 11 and the light sources 13 provided corresponding to these inkjet heads 11 are provided in the order of magenta, black, cyan, and yellow. In this case, when two light sources 13 adjacent to each other in the movement direction of the can body 10 are compared, the amount of irradiation by the light source 13 that irradiates first will be greater than the amount of irradiation by the light source 13 that irradiates later. Alternatively, the amount of irradiation by the light source 13 that irradiates first will be equal to the amount of irradiation by the light source 13 that irradiates later.

[0070] 7 and 8(A) to (D) are diagrams showing other examples of images formed on the can body 10. In FIG. 7 shows the state of image 70 after image formation on can body 10 by image forming unit 120. In other words, FIG. 7 shows the state of image 70 after four color inks have been applied to can body 10. The image 70 shown in FIG. 7 is an image in which the contours of each component that makes up the image are clearly defined.

[0071] Figures 8(A) to (D) respectively show an image formed by cyan inkjet head 11C, an image formed by black inkjet head 11K, an image formed by magenta inkjet head 11M, and an image formed by yellow inkjet head 11Y. In other words, the images shown in each of Figures 8(A) to (D) show images formed based on image data of each color obtained by color separation processing of the image data that is the basis of the image shown in Figure 7.

[0072] In each of the drawings in FIG. 7 and FIGS. 8(A) to 8(D), the darker shaded areas are areas where the image density is high and where more ink is applied. In this processing example, as indicated by reference numeral 8X in FIG. 8, the amounts of ultraviolet light emitted by the light source 13 are set to 75%, 100%, 75%, and 50% for cyan, black, magenta, and yellow, respectively.

[0073] In this processing example, the character image 92 located in the portion indicated by reference numeral 7A in Fig. 7 is formed mainly in black ink, as shown in Fig. 8(B). Furthermore, this character image 92 located in the portion indicated by reference numeral 7A in Fig. 7 is small and detailed. For this reason, in this processing example, the amount of ultraviolet light emitted by the light source 13 corresponding to black is set to 100%, as indicated by the reference symbol 8X in FIG.

[0074] In this processing example, a character image 92 reading "KOBE BAYSIDE" is formed as shown in Fig. 7. In this processing example, as shown in Fig. 8(A) and (C), this character image 92 is formed mainly with cyan ink and magenta ink. As shown in FIGS. 8A and 8C, the cyan ink and the magenta ink are also used to form a background image 91 (see FIG. 7).

[0075] For this reason, in this processing example, the amount of ultraviolet light emitted by the light source 13 corresponding to cyan and magenta is set to 75%, as indicated by the symbol 8X in FIG. On the other hand, as shown in Fig. 8(D), yellow ink is not often used to form the character image 92. For this reason, the amount of ultraviolet light emitted by the light source 13 corresponding to yellow is set to 50%, as shown by the symbol 8X in Fig. 8.

[0076] 9 and 10(A) to (D) are diagrams showing other examples of images formed on the can body 10. In FIG. 9, similarly to the above, shows the state of image 70 after image formation by image forming unit 120. In other words, FIG. 9 shows the state of image 70 after four colors of ink have been applied to can body 10. In this image 70 shown in FIG. 9, a background image 91 exists on the upper side, a sharp image such as an image of a building exists on the lower side, and a character image 92 exists on the left side.

[0077] As above, Figures 10(A) to (D) respectively show an image formed by the cyan inkjet head 11C, an image formed by the black inkjet head 11K, an image formed by the magenta inkjet head 11M, and an image formed by the yellow inkjet head 11Y. In other words, FIGS. 10(A) to 10(D) show images formed based on image data obtained by color separation, similar to the above.

[0078] In this processing example, as indicated by reference numeral 10X in FIG. 10, the amount of ultraviolet light emitted by the light source 13 is set to 25%, 100%, 75%, and 50% for cyan, black, magenta, and yellow, respectively. In this processing example, as shown in Fig. 10(B), black ink is used to form the character image 92 located in the portion indicated by reference numeral 9A in Fig. 9. The portion indicated by reference numeral 10B in Fig. 10(B) has a lighter shade, and this black ink is not used much to form the background image 91 (see Fig. 9). For this reason, in this example, the amount of ultraviolet light emitted by the light source 13 corresponding to black is set to 100%, as indicated by the reference symbol 10X in FIG.

[0079] In this processing example, cyan and magenta inks are also used to form the character image 92 (see reference numeral 9A in FIG. 9), as indicated by reference numeral 10E in FIGS. 10(A) and 10(C). These cyan and magenta inks are also used to form the background image 91 (see FIG. 9). Therefore, in this processing example, as shown by the symbol 10X in Figure 10, the amount of ultraviolet light emitted by the light source 13 corresponding to cyan is set to 25%, and the amount of ultraviolet light emitted by the light source 13 corresponding to magenta is set to 75%.

[0080] The amount of ultraviolet light emitted by the light source 13 corresponding to magenta is set to 75% instead of 25% in order to promote curing of the magenta image. In this processing example, as shown in Fig. 10(C), a large amount of magenta ink is used in the lower part of the formed image, so in order to promote the hardening of this ink, the amount of ultraviolet light emitted by the light source 13 corresponding to magenta is set to 75%.

[0081] On the other hand, as shown in Figure 10(D), the amount of yellow ink used to form the character image 92 (see reference numeral 9A in Figure 9) is smaller than that of black ink. Therefore, as in the above, the amount of ultraviolet light irradiated on yellow is reduced. In this processing example, yellow ink is used in large amounts in the lower part of the image shown in Fig. 10(D). Therefore, in this processing example, the amount of ultraviolet light emitted by the light source 13 corresponding to yellow is set to 50% in order to promote curing of this lower part.

[0082] 11 and 12(A) to 12(D) are diagrams showing other examples of images formed on the can body 10. In FIG. As described above, Fig. 11 shows the state of image 70 after image formation by image forming unit 120. In other words, Fig. 11 shows the state of image 70 after four colors of ink have been applied to can body 10. The image 70 shown in FIG. 11 is a halftone image, and in the image 70 shown in FIG. 11, the color of the character image 92 is black.

[0083] 12(A) to 12(D), similar to the above, respectively show an image formed by the cyan inkjet head 11C, an image formed by the black inkjet head 11K, an image formed by the magenta inkjet head 11M, and an image formed by the yellow inkjet head 11Y. In other words, FIGS. 12(A) to 12(D) show each of the images formed based on image data obtained by color separation. In this processing example, as indicated by reference numeral 12X in FIG. 12, the irradiation amounts of ultraviolet light from the light source 13 are 25%, 100%, 25%, and 25% for cyan, black, magenta, and yellow, respectively.

[0084] In this processing example, as shown in Fig. 12(B), black ink is used predominantly to form the character image 92 such as "Cocktail" shown in Fig. 11. Furthermore, compared to yellow ink, black ink is used less frequently to form the background image 91. For this reason, in this processing example, the amount of ultraviolet light emitted by the light source 13 corresponding to black is set to 100%, as indicated by reference numeral 12X in FIG.

[0085] In this processing example, the final image 70 (image 70 shown in FIG. 11) is a halftone image, which is a light image overall. In this case, the density of the image formed by ink of each color is low. In this case, the amount of ink used to form image 70 is reduced, and accordingly, in this processing example, the amount of ultraviolet light irradiated on inks of colors other than black is set to 25%, as shown by symbol 12X in Figure 12.

[0086] (others) In the above, an example of a curing means has been described in which a light source 13 that emits light with a wavelength in the ultraviolet region is provided, but the curing means may also be a light source 13 that emits light with a wavelength other than the ultraviolet region. If the ink used by the inkjet head 11 when forming an image is an ink that is cured by light of a wavelength other than the ultraviolet region, a light source 13 that emits light of a wavelength other than the ultraviolet region will be provided as a curing means.

[0087] Furthermore, although the above describes a case in which the can body 10 moves along a can body movement path R1 having a curve, the can body movement path R1 along which the can body 10 moves may be linear, and the can body 10 may move along the linear can body movement path R1. In addition, in the above, an example was described in which the light source 13 is located on the opposite side of the can body movement path R1 from the inkjet head 11, but the location where the light source 13 is installed is not particularly limited, and the light source 13 may be located on the side where the inkjet head 11 is installed. [Explanation of symbols]

[0088] 1...image forming apparatus, 10...can body, 11...inkjet head, 13...light source, 14...blocking portion, 92...character image

Claims

1. a plurality of image forming means for forming images on the can body; a curing unit provided corresponding to each of the plurality of image forming units, for irradiating light onto the can body on which an image has been formed by the image forming unit to cure the image; Equipped with the plurality of image forming means include an image forming means for forming an image including a character image on the can body, and an image forming means for forming an image not including a character image on the can body; the amount of light irradiation by the curing means provided corresponding to the image forming means that forms an image including the character image is greater than the amount of light irradiation by the curing means provided corresponding to the image forming means that forms an image that does not include the character image; The irradiation of light onto the can body by the curing means provided corresponding to the image forming means that forms the image including the character image is performed prior to the irradiation of light onto the can body by the curing means provided corresponding to the image forming means that forms the image that does not include the character image. Image forming device.

2. a plurality of image forming means for forming images on the can body; a curing unit provided corresponding to each of the plurality of image forming units, for irradiating light onto the can body on which an image has been formed by the image forming unit to cure the image; Equipped with the plurality of image forming means include an image forming means for forming an image including a character image on the can body, and an image forming means for forming an image not including a character image on the can body; the amount of light irradiation by the curing means provided corresponding to the image forming means that forms an image including the character image is greater than the amount of light irradiation by the curing means provided corresponding to the image forming means that forms an image that does not include the character image; a plurality of sets of the image forming means and the curing means provided corresponding to the image forming means are provided, and processing by each set is performed in sequence; Among the sequential irradiations of light onto the can body, the irradiation of light by the curing means provided corresponding to the image forming means for forming an image including the character image is performed first. Image forming device.

3. a plurality of image forming means for forming images on the can body; a curing unit provided corresponding to each of the plurality of image forming units, for irradiating light onto the can body on which an image has been formed by the image forming unit to cure the image; Equipped with the amount of light irradiated onto the can body by the curing means provided corresponding to the image forming means that forms a black image on the can body is greater than the amount of light irradiated onto the can body by the curing means provided corresponding to the image forming means that forms an image of a color other than black on the can body; The irradiation of light onto the can body by the curing means provided corresponding to the image forming means that forms the black image is performed before the irradiation of light onto the can body by the curing means provided corresponding to the image forming means that forms the image of a color other than black. Image forming device.

4. a plurality of image forming means for forming images on the can body; a curing unit provided corresponding to each of the plurality of image forming units, for irradiating light onto the can body on which an image has been formed by the image forming unit to cure the image; Equipped with the amount of light irradiated onto the can body by the curing means provided corresponding to the image forming means that forms a black image on the can body is greater than the amount of light irradiated onto the can body by the curing means provided corresponding to the image forming means that forms an image of a color other than black on the can body; a plurality of sets of the image forming means and the curing means provided corresponding to the image forming means are provided, and processing by each set is performed in sequence; Among the sequential irradiations of light onto the can body, the irradiation of light by the curing means provided corresponding to the image forming means for forming the black image is performed first. Image forming device.

5. a plurality of image forming means for forming images on the can body; a curing unit provided corresponding to each of the plurality of image forming units, for irradiating light onto the can body on which an image has been formed by the image forming unit to cure the image; Equipped with The amount of light irradiated onto the can body by one curing means included in the plurality of curing means is different from the amount of light irradiated onto the can body by another curing means included in the plurality of curing means, a blocking portion that is positioned at a position opposite the curing means when the can body is not positioned at the position opposite the curing means and blocks light from the curing means; Image forming device.

6. The image forming apparatus described in claim 5, wherein the blocking portion is configured to move in conjunction with the moving can body, and is located at the opposing position when the can body is not located at the opposing position, and is located at a location away from the opposing position when the can body is located at the opposing position.

7. a plurality of image forming means for forming images on the can body; a curing unit provided corresponding to each of the plurality of image forming units, for irradiating light onto the can body on which an image has been formed by the image forming unit to cure the image; Equipped with The amount of light irradiated onto the can body by one curing means included in the plurality of curing means is different from the amount of light irradiated onto the can body by another curing means included in the plurality of curing means, the curing unit is disposed on the opposite side to the image forming unit, with the can body disposed in a position facing the image forming unit therebetween; Image forming device.

8. The image forming apparatus according to claim 7, further comprising a blocking section that is positioned between the image forming means and the curing means when the can body is not positioned opposite the image forming means and that blocks light from the curing means toward the image forming means.

Images