Inspection device and inkjet printing apparatus equipped therewith

Abstract

To enable accurate inspection by suppressing noise caused by reflection light by a conveyance roller.SOLUTION: An inspection part 43 is configured so that a black tape for absorbing light from an upper reflection light source 51b, a lower reflection light source 51c and a transmission light source 53 is wound around an outer peripheral surface of conveyance rollers 45 and 47. Accordingly, reflection of the emitted light by a lower side outer peripheral surface of the conveyance roller 45 and an upper side outer peripheral surface of the conveyance roller 47 is suppressed. As a result, noise in a photographing part 51 caused by reflection light by the conveyance rollers 45 and 47 can be suppressed. Therefore, accurate inspection in the inspection part 43 can be performed. Cost can be reduced by configuration of the black tape. The configuration that only the black tape is wound can be also easily applied to an existing device.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an inspection apparatus that reads an image of a transparent printing medium being conveyed by a conveyance roller to inspect a printing state, and an inkjet printing apparatus including the same.

Background Art

[0002] In an inkjet printing apparatus that ejects ink droplets to print an image on a printing medium, defects caused by ejection such as nozzle clogging, lateral flight of ink droplets, ejection of ink at times other than the specified timing (so-called dripping), defects caused by conveyance such as skew or meandering of the printing medium, wrinkles, ink flow defects caused by poor drying of ink droplets, and contamination caused by reattachment due to contamination of rollers accompanying ink flow may occur. Therefore, an inspection apparatus that inspects the printed image is used.

[0003] Conventionally, some devices of this type include a light source and a reading sensor (see, for example, Patent Document 1). The light source and the reading sensor are arranged on the same surface of the printing medium. The light irradiated from the light source is reflected by the printing medium and enters the reading sensor.

[0004] In such a configuration, when the printing medium is transparent, the reflected light passes through the transparent portion. Therefore, it becomes difficult to distinguish between the image portion printed with black ink and the transparent portion. As a result, when the printing medium is transparent, there is a problem that accurate inspection cannot be performed.

[0005] Therefore, some devices include a photographing unit, a first irradiation unit, and a second irradiation unit (see, for example, Patent Document 2). The first irradiation unit is arranged opposite to the photographing unit with the printing medium interposed therebetween. The second irradiation unit is arranged on the same side as the photographing unit. Thereby, transmitted light enters the photographing unit from the first irradiation unit. Reflected light enters the photographing unit from the second irradiation unit. Therefore, even when the printing medium is transparent, accurate inspection is possible.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 6010980 (Figure 1) [Patent Document 2] Japanese Patent Publication No. 2019-142007 (Figure 5) [Overview of the project] [Problems that the invention aims to solve]

[0007] However, conventional examples with such a configuration have the following problems. In other words, conventional devices have transport rollers positioned upstream and downstream of the imaging unit. Therefore, especially when the outer surface of the transport rollers is silver, strong reflection occurs from the transport rollers. Consequently, noise caused by reflected light from the transport rollers occurs in the imaging unit, which can hinder accurate inspection. This problem can also occur in configurations that do not have a second irradiation unit, which is the source of the reflected light.

[0008] The present invention has been made in view of these circumstances, and aims to provide an inspection device and an inkjet printing device equipped therewith that can perform accurate inspections by suppressing noise caused by reflected light from a transport roller. [Means for solving the problem]

[0009] To achieve this objective, the present invention has the following configuration. In other words, the present invention relates to an inspection device for reading a printed image printed on a transparent printing medium and inspecting the printing condition, comprising: a first transport roller for transporting the transparent printing medium; a second transport roller positioned downstream in the transport direction, spaced apart from the first transport roller, for transporting the transparent printing medium; an imaging unit positioned between the first transport roller and the second transport roller, positioned on one side of the transparent printing medium, for capturing a printed image located in an inspection area set between the first transport roller and the second transport roller; and a light irradiation unit for irradiating light to capture the printed image located in the inspection area by the imaging unit, wherein the first transport roller and the second transport roller are characterized in that their outer surfaces are made of light-absorbing members that absorb light from the light irradiation unit.

[0010] [Effects] According to the present invention, the first and second conveying rollers are made of light-absorbing members whose outer surfaces absorb light from the light-emitting section. Therefore, reflection of light emitted from the light-emitting section by the first and second conveying rollers is suppressed. As a result, noise caused by reflected light from the first and second conveying rollers can be suppressed. Thus, accurate inspection can be performed.

[0011] Furthermore, in the present invention, it is preferable that the light-absorbing member is a black tape that has been treated with an anti-reflective coating.

[0012] The outer surfaces of the first and second conveyor rollers are made of black tape that has been treated with an anti-reflective coating (e.g., a matte finish). Therefore, costs can be reduced. Also, since it only involves wrapping black tape, it can be easily applied to existing equipment.

[0013] Furthermore, in the present invention, it is preferable that the light-absorbing member has a needle-like structure with numerous recesses and numerous protrusions, and is coated with a black film.

[0014] The needle-like structure has numerous recesses and protrusions, and the outer surfaces of the first and second conveyor rollers are coated with a black film. Therefore, durability can be improved, and the effect can be maintained over a long period of time.

[0015] Furthermore, the present invention relates to an inspection device for reading a printed image printed on a transparent printing medium and inspecting the printing condition, characterized in that it comprises: a first transport roller for transporting the transparent printing medium; a second transport roller positioned downstream in the transport direction, spaced apart from the first transport roller, and transporting the transparent printing medium; an imaging unit positioned between the first transport roller and the second transport roller, positioned on one side of the transparent printing medium, and for capturing a printed image located in an inspection area set between the first transport roller and the second transport roller; a light irradiation unit that irradiates light for capturing the printed image located in the inspection area by the imaging unit; and a light irradiation restricting unit that restricts the irradiation of light from the light irradiation unit to the first transport roller and the second transport roller.

[0016] [Function and Effects] According to the present invention, the light irradiation restricting unit restricts the irradiation of light from the light irradiation unit to the first and second conveyor rollers. Therefore, noise caused by reflected light from the first and second conveyor rollers can be prevented. Thus, accurate inspection can be performed.

[0017] Furthermore, in the present invention, it is preferable that the light irradiation regulating unit is composed of a light irradiation unit that irradiates light onto a range including the inspection area excluding the first transport roller and the second transport roller.

[0018] The light irradiation unit is a light irradiation regulating unit, and it irradiates light into an area including the inspection area, excluding the first and second transport rollers. This makes it possible to solve problems caused by reflected light from the first and second transport rollers by modifying only the light irradiation unit.

[0019] In the present invention, it is preferable that the light irradiation restricting unit includes a hood that prevents the light from the light irradiation unit from irradiating the first conveyance roller and the second conveyance roller.

[0020] The light irradiation restricting unit includes a hood that prevents the light from the light irradiation unit from irradiating the first conveyance roller and the second conveyance roller. Thereby, just by providing a hood for the light irradiation unit, the problems caused by the reflected light on the first conveyance roller and the second conveyance roller can be solved. Therefore, it can be easily applied to existing devices.

[0021] In the present invention, it is preferable that the light irradiation restricting unit is configured such that the distance in the conveyance direction between the first conveyance roller and the second conveyance roller is set outside the light irradiation range by the light irradiation unit.

[0022] The light irradiation restricting unit is configured such that the distance in the conveyance direction between the first conveyance roller and the second conveyance roller is set outside the light irradiation range by the light irradiation unit. Therefore, the problems caused by the reflected light on the first conveyance roller and the second conveyance roller can be solved without adding a new configuration.

[0023] In the present invention, it is preferable that the light irradiation restricting unit is configured to be disposed at a position on the side where the first conveyance roller and the second conveyance roller are disposed and between the first conveyance roller and the second conveyance roller, with respect to the transparent printing medium conveyed between the first conveyance roller and the second conveyance roller by the imaging unit.

[0024] Based on the transparent printing medium conveyed between the first conveying roller and the second conveying roller, at a position on the side where the first conveying roller and the second conveying roller are arranged, and at a position between the first conveying roller and the second conveying roller, a photographing unit is arranged, and a light irradiation restricting unit is configured. Therefore, it is possible to suppress the light reflected from the outer peripheral surface between the first conveying roller and the second conveying roller from entering the photographing unit. Thus, by simply changing the position of the photographing unit, the problems caused by the reflected light on the first conveying roller and the second conveying roller can be solved.

[0025] Further, the invention according to claim 1 is an inspection apparatus that reads a printed image printed on a transparent printing medium and inspects the printing state, including a first conveying roller that conveys the transparent printing medium, a second conveying roller that is arranged downstream in the conveying direction at a distance from the first conveying roller and conveys the transparent printing medium, a photographing unit that is arranged between the first conveying roller and the second conveying roller, is arranged on one surface side of the transparent printing medium, and photographs a printed image located in an inspection area set between the first conveying roller and the second conveying roller, and a light irradiation unit that irradiates light for photographing the printed image located in the inspection area by the photographing unit. The photographing unit is characterized in that it has a moving mechanism whose position with respect to the inspection area is fixed during operation and can move away from the inspection area and away from the surface of the transparent printing medium during maintenance.

[0026] During maintenance, the photographing unit can be moved away from the surface of the transparent printing medium by the moving mechanism. Therefore, powders and the like detached from the transparent printing medium can be easily removed from the photographing unit. Thus, accurate inspection can be performed over a long period.

[0027] Furthermore, in the present invention, it is preferable that the device frame to which the first transport roller and the second transport roller are rotatably mounted comprises a moving mechanism having a long axis in the width direction of the transparent printing medium and an imaging unit frame mounted on the device frame with the imaging unit attached, and a pivot shaft provided on one end of the imaging unit frame, with its axis parallel to the surface of the transparent printing medium (Claim 2).

[0028] The imaging unit frame has a pivot axis at one end. The pivot axis is positioned so that its axis is parallel to the surface of the transparent printing medium. Therefore, the imaging unit frame can pivot around one end relative to the surface of the transparent printing medium at the other end. Thus, maintenance can be performed simply by pivoting the imaging unit frame away from the surface of the transparent printing medium.

[0029] Furthermore, in the present invention, it is preferable that the apparatus frame is provided with a frame positioning pin that restricts the position of the other end of the imaging unit frame so that the imaging unit is in a focus position with respect to the printed image on the transparent printing medium (Claim 3).

[0030] The frame positioning pins restrict the position of the other end of the imaging unit frame so that the imaging unit is in focus. Therefore, even after the imaging unit frame has been swung and then returned to its original position, the imaging unit can still take pictures properly.

[0031] Furthermore, in the present invention, it is preferable that the imaging unit frame comprises rails arranged on both ends of the imaging unit in the width direction of the transparent printing medium, the imaging unit being configured to be movable relative to the transparent printing medium at both ends, and imaging unit positioning pins that restrict the position of the imaging unit on the rails so that the imaging unit is in a focus position where it is in focus with respect to the printed image on the transparent printing medium (Claim 4).

[0032] The imaging unit frame is equipped with rails and imaging unit positioning pins. Therefore, the imaging unit can move along the rails relative to the transparent printing medium, but can be easily fixed in the focused position by the imaging unit positioning pins. Thus, even if the imaging unit is moved during maintenance, it can be easily set to the focused position.

[0033] Furthermore, in the present invention, it is preferable to further include the above-described inspection device and a print head upstream of the inspection device that ejects ink droplets onto the transparent printing medium to print the print image, and to inspect the print image printed by the print head with the inspection device.

[0034] The printed image on a transparent printing medium printed by the print head is inspected by an inspection device. In the inspection device, reflection of light emitted from the light irradiation unit by the first and second transport rollers is suppressed. As a result, noise caused by reflected light from the first and second transport rollers can be suppressed. Accurate inspection of printed images produced by an inkjet printing device can be performed.

[0035] Furthermore, this specification also discloses inventions relating to the following inspection devices.

[0036] In conventional devices, when the printing medium is film and the image-forming ink is water-based, a primer layer (also called a pre-treatment layer or ink-penetrating layer) is generally formed before printing to ensure the water-based ink adheres properly. As a result, powder from the primer layer can adhere to the imaging unit, potentially hindering accurate inspection. Similarly, when the printing medium is paper, paper dust can adhere to the imaging unit, potentially causing the same problem. Therefore, it is necessary to periodically clean the light-transmitting surface of the imaging unit. However, when the image sensor in the imaging unit is a CIS (contact image sensor), the depth of field is shallow. Consequently, the distance between the light-transmitting surface of the imaging unit and the printing medium is reduced. This presents a problem in that maintenance of the imaging unit is difficult.

[0037] (1) In an inspection device that reads a printed image printed on a printing medium and inspects the printing condition, A first transport roller for transporting the printing medium, A second conveyor roller is positioned downstream in the conveying direction, spaced apart from the first conveyor roller, and conveys the printing medium. A photographing unit is positioned between the first transport roller and the second transport roller, on one side of the printing medium, and captures a printed image located in an inspection area set between the first transport roller and the second transport roller. The aforementioned imaging unit emits light to capture a printed image located in the inspection area, and the light irradiation unit emits light to capture the printed image located in the inspection area. Equipped with, The inspection apparatus is characterized in that the imaging unit has a fixed position relative to the inspection area during operation, and a moving mechanism that allows it to move away from the inspection area and away from the surface of the printing medium during maintenance.

[0038] According to the invention described in (1) above, the imaging unit can be moved away from the surface of the printing medium by the moving mechanism during maintenance. Therefore, powder and other particles that have separated from the printing medium can be easily removed from the imaging unit. Thus, accurate inspections can be performed over a long period of time.

[0039] (2) In the inspection apparatus described in (1) above, The device comprises a frame on which the first and second conveying rollers are rotatably mounted, The moving mechanism has a long axis in the width direction of the printing medium, and with the imaging unit attached, the imaging unit frame is attached to the device frame, The pivot shaft is positioned so as to be parallel to the surface of the printing medium, and is provided on one end of the frame of the photographic unit, An inspection device characterized by having the following features.

[0040] According to the invention described in (2) above, the imaging unit frame is equipped with a pivot shaft at one end. The pivot shaft is positioned so that its axis is parallel to the surface of the printing medium. Therefore, the imaging unit frame can pivot at one end relative to the surface of the printing medium. Thus, maintenance can be performed simply by pivoting the imaging unit frame away from the surface of the printing medium.

[0041] (3) In the inspection apparatus described in (1) above, The inspection apparatus is characterized in that the apparatus frame is provided with a frame positioning pin that restricts the position of the other end of the imaging unit frame so that the imaging unit is in focus with respect to the printed image on the transparent printing medium.

[0042] According to the invention described in (3) above, the frame positioning pin restricts the position of the other end of the imaging unit frame so that the imaging unit is in the focus position. Therefore, even after the imaging unit frame has been swung and then returned to its original position, imaging by the imaging unit can be performed appropriately.

[0043] (4) In the inspection apparatus described in (1) above, The inspection apparatus is characterized in that the imaging unit frame is arranged on both ends of the imaging unit in the width direction of the transparent printing medium, and the imaging unit is configured to be movable relative to the transparent printing medium at both ends of the rail, and the imaging unit positioning pins restrict the position of the imaging unit on the rail so that the imaging unit is in a focus position where it is in focus with respect to the printed image on the transparent printing medium.

[0044] According to the invention described in (4) above, the imaging unit frame includes a rail and an imaging unit positioning pin. Therefore, the imaging unit is movable along the rail relative to the printing medium, but can be easily fixed in the focused position by the imaging unit positioning pin. Thus, even if the imaging unit is moved during maintenance, imaging can be performed properly by the imaging unit.

[0045] (5) In the inspection apparatus described in (1) to (4) above, Upstream of the inspection device, a print head ejects ink droplets onto the printing medium to print the print image, Equipped with, An inkjet printing apparatus characterized by inspecting the printed image printed by the print head with the inspection device.

[0046] According to the invention described in (5) above, the printed image of the printing medium printed by the print head is inspected by an inspection device. In the inspection device, the reflection of light emitted from the light irradiation unit by the first transport roller and the second transport roller is suppressed. As a result, noise caused by reflected light from the first transport roller and the second transport roller can be suppressed. Accurate inspection of the printed image printed in the inkjet printing device can be performed. [Effects of the Invention]

[0047] According to the inspection apparatus of the present invention, the first and second transport rollers are made of light-absorbing members whose outer surfaces absorb light from the light-emitting section. Therefore, reflection of light emitted from the light-emitting section by the first and second transport rollers is suppressed. As a result, noise caused by reflected light from the first and second transport rollers can be suppressed. Thus, accurate inspection can be performed. [Brief explanation of the drawing]

[0048] [Figure 1] This is a schematic diagram showing the overall configuration of the inkjet printing apparatus according to the embodiment. [Figure 2] This is a side view showing the main components of the inspection section. [Figure 3] This is a perspective view showing the configuration of the conveyor roller in Example 1. [Figure 4] This shows the configuration of the conveyor roller in a modified example, and is a magnified longitudinal cross-sectional view of a part of it. [Figure 5] This is a side view showing the main parts of the inspection unit in Example 2. [Figure 6] This is a side view showing the main parts of the inspection unit in Example 3. [Figure 7] This is a side view showing the main parts of the inspection unit in Example 4. [Figure 8] This is a side view showing the main parts of the inspection unit in Example 5. [Figure 9] This is a side view of the moving mechanism in the inspection department. [Figure 10] This is a plan view of the moving mechanism in the inspection department. [Figure 11] This is a front view of the imaging unit movement mechanism in the inspection unit. [Figure 12] This is a plan view of the imaging unit movement mechanism in the inspection unit. [Modes for carrying out the invention]

[0049] Various embodiments of an inkjet printing apparatus equipped with the inspection device according to the present invention are described below. [Examples]

[0050] Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings. Figure 1 is a schematic diagram showing the overall configuration of an inkjet printing apparatus according to an embodiment.

[0051] The inkjet printing apparatus 1 comprises a paper feeding unit 3, a coating unit 5, a printing unit 7, a main drying unit 9, and a paper discharge unit 11. In Figure 1, the left-right direction is defined as the transport direction X. The left direction in the transport direction X is defined as the downstream side, and the right direction as the upstream side. In some cases, the left direction is denoted as the +X direction and the right direction as the -X direction, with a reference point. In Figure 1, the direction from back to front of the paper is defined as the width direction Y. The up-down direction in Figure 1 is defined as the height direction Z. The paper feeding unit 3, coating unit 5, printing unit 7, main drying unit 9, and paper discharge unit 11 are arranged in that order toward the downstream side in the transport direction X.

[0052] The paper feeding unit 3 supplies the flexible packaging film WF, which is to be printed, to the coating unit 5. In this embodiment, the flexible packaging film WF is, for example, a transparent film. The paper feeding unit 3 holds the rolled flexible packaging film WF so that it can rotate around a horizontal axis. The paper feeding unit 3 unwinds the flexible packaging film WF with the printing surface facing upwards relative to the coating unit 5. The material of the flexible packaging film WF is, for example, a hydrophobic substrate with low absorption of water-based ink. Examples of flexible packaging film WF include plastic films such as polypropylene resin, vinyl chloride resin, and polyimide resin.

[0053] The flexible packaging film WF mentioned above corresponds to the "transparent printing medium" in this invention.

[0054] The coating unit 5 applies a primer to the flexible packaging film WF to form a primer layer. The primer layer is also called a pretreatment layer, ink penetration layer, or ink receiving layer. The primer is a coating liquid, also called an undercoat liquid or base preparation liquid. Specifically, the coating unit 5 comprises a pan 13, a gravure roller 15, and a transport unit 17. The pan 13 stores the primer. The lower part of the gravure roller 15 is partially immersed in the primer stored in the pan 13, and as it rotates, its upper part supplies the primer to the printed surface of the flexible packaging film WF. The transport unit 17 unwinds the flexible packaging film WF from the paper feeding unit 3 and transports the flexible packaging film WF to the gravure roller 15. In the area where the primer is supplied by the gravure roller 15, the transport direction of the flexible packaging film WF and the rotation direction of the circumferential surface of the gravure roller 15 are opposite. The primer is applied to the flexible packaging film WF using a so-called reverse kiss method. The transport unit 17 transports the flexible packaging film WF, which has been coated with primer, from the coating unit 5 to the printing unit 7 with the printed surface of the film facing upwards.

[0055] Examples of primers include those containing resins, polyvalent metal salts, alcohols, surface tension modifiers, and pure water. Examples of resins include shellac, examples of polyvalent metal salts include calcium lactate, examples of alcohols include ethanol, and examples of surface tension modifiers include SY Glyster.

[0056] The printing unit 7 comprises a color printing unit 19, a pre-drying unit 21, a white printing unit 25, an upper drying unit 27, and a transport unit 29. The color printing unit 19 prints a color image on the printed surface of the flexible packaging film WF coated with a primer layer by, for example, dispensing multi-colored inks. The pre-drying unit 21 pre-dries the printed surface of the flexible packaging film WF after color printing. The white printing unit 25 prints a white image on the printed surface of the flexible packaging film WF by dispensing white ink. The upper drying unit 27 dries the printed surface of the flexible packaging film WF with the white image printed on it. The transport unit 29 transports the flexible packaging film WF from the color printing unit 19 to the upper drying unit 27.

[0057] The main drying unit 9 dries both the printed side and the opposite side of the flexible packaging film WF printed in the printing unit 7. Specifically, the main drying unit 9 comprises a first drying unit 31, a second drying unit 33, a third drying unit 35, a first conveying unit 37, a second conveying unit 39, and a third conveying unit 41. The first drying unit 31 dries the printed side of the flexible packaging film WF that is conveyed downstream in the conveying direction X by the first conveying unit 37. The second drying unit 33 dries both sides of the flexible packaging film WF that is conveyed upstream in the conveying direction X by the second conveying unit 39. The third drying unit 35 dries both sides of the flexible packaging film WF that is conveyed downstream in the conveying direction X by the third conveying unit 41. The first drying section 31, the second drying section 33, and the third drying section 35 discharge gas heated to a predetermined temperature onto the flexible packaging film WF. This dries the image printed on the printed surface of the flexible packaging film WF. The main drying section 9 discharges gas at, for example, 80-90°C at a wind speed of 27-30 m / s.

[0058] In this embodiment, an inspection unit 43 is provided at the downstream end of the main drying unit 9. The detailed configuration of this inspection unit 43 will be described later. Note that the inspection unit 43 corresponds to the "inspection device" in this invention.

[0059] The paper discharge section 11 winds the flexible packaging film WF, which has been dried by the main drying section 9, around a horizontal axis.

[0060] The inspection unit 43 will now be described with reference to Figures 2 and 3. Figure 2 is a side view showing the main parts of the inspection unit. Figure 3 is a perspective view showing the configuration of the conveyor roller in Example 1.

[0061] The inspection unit 43 includes a transport roller 45, a transport roller 47, a frame 49, an imaging unit 51, and a transmitted light source unit 53.

[0062] The conveyor rollers 45 and 47 convey the flexible packaging film WF. Specifically, the conveyor roller 45 feeds the film from the left in the conveying direction X, changes its orientation downwards in the height direction Z, and feeds it out. The conveyor roller 47 is positioned below the conveyor roller 45 in the height direction Z. The center of rotation of the conveyor roller 47 is spaced at a distance L1 from the center of rotation of the conveyor roller 45. The distance L1 is, for example, 100 mm. The conveyor roller 47 feeds the flexible packaging film WF from above, changing its orientation to the left in the conveying direction X.

[0063] The frame 49 is positioned between the conveyor rollers 45 and 47 in the height direction Z, and is located on the opposite side (-X direction) from the conveyor rollers 45 and 47, with the flexible packaging film WF in between. More specifically, the frame 49 is located to the right of the conveyor roller 47 in the conveying direction X. The frame 49 is attached to a device frame (not shown) that rotatably holds the conveyor rollers 45 and 47, etc. The frame 49 is made of, for example, a cylindrical member. The frame 49 is formed to be long in the width direction Y. An imaging unit 51 is attached to the upper surface of the frame 49. The imaging unit 51 is formed to be long in the width direction Y, similar to the frame 49.

[0064] The imaging unit 51 is equipped with an image sensor 51a in its central part. The imaging unit 51 is equipped with an upper reflective light source 51b above the image sensor 51a in the height direction Z. The imaging unit 51 is equipped with a lower reflective light source 51c below the image sensor 51 in the height direction Z. The image sensor 51a is, for example, a CIS (contact image sensor). The upper reflective light source 51b and the lower reflective light source 51c irradiate light from the imaging unit 51 side toward the left in the transport direction X, that is, toward the opposite side toward the printed surface on the flexible packaging film WF side that is transported by the transport rollers 45, 47. The upper reflective light source 51b and the lower reflective light source 51c are, for example, made of light-emitting diodes. The transmitted light source 53 is located on the opposite side of the imaging unit 51 in the transport direction X, with the flexible packaging film WF in between. The transmitted light source 53 is, for example, made of light-emitting diodes. The upper reflective light source 51b, the lower reflective light source 51c, and the transmitted light source 53 described above primarily irradiate the flexible packaging film WF with light. However, the light from the upper reflective light source 51b and the transmitted light source 53 also irradiates the lower outer surface of the conveying roller 45. In addition, the light from the lower reflective light source 51b and the transmitted light source 53 also irradiates the upper outer surface of the conveying roller 47.

[0065] The aforementioned imaging unit 51 photographs the area between the transport rollers 45 and 47. Specifically, the imaging unit 51 photographs the inspection area IA. The inspection area IA is located between the transport rollers 45 and 47 and is set approximately in the center of the distance L1. The imaging unit 51 reads the printed image printed on the printed surface of the flexible packaging film WF by detecting the reflected and transmitted light from the inspection area IA with the image sensor 51a.

[0066] The aforementioned conveyor rollers 45 and 47 are made of metal, as has been done in the past. For example, the outer surfaces of the conveyor rollers 45 and 47 are silver in color. In this embodiment, the outer surfaces of these conveyor rollers 45 and 47 are treated.

[0067] Specifically, it is as shown in Figure 3.

[0068] The conveyor rollers 45 and 47 have a narrow black tape 55 wrapped spirally around their outer circumference, centered on the long axis of the conveyor rollers 45 and 47. The black tape has an anti-reflective treatment applied to its surface. For example, the anti-reflective treatment may be a matte finish achieved by applying a textured surface treatment. Alternatively, an anti-reflective film may be applied to the surface of the black tape. Furthermore, the black tape 55 may be wrapped only once around the outer circumference, with a width matching the length Y in the width direction of the conveyor rollers 45 and 47.

[0069] The transport roller 45 described above corresponds to the "first transport roller" in this invention, and the transport roller 47 corresponds to the "second transport roller" in this invention. The upper reflective light source 51b, the lower reflective light source 51c, and the transmitted light source 53 correspond to the "light irradiation section" in this invention. The black tape 55 corresponds to the "light absorbing member" in this invention.

[0070] In this embodiment, the inspection unit 43 is constructed by wrapping black tape 55, which absorbs light from the upper reflective light source 51b, the lower reflective light source 51c, and the transmitted light source 53, around the outer circumferential surfaces of the transport rollers 45 and 47. Therefore, reflection of the irradiated light from the lower outer circumferential surface of the transport roller 45 and the upper outer circumferential surface of the transport roller 57 is suppressed. As a result, noise in the imaging unit 51 caused by reflected light from the transport rollers 45 and 47 can be suppressed. Thus, accurate inspection can be performed in the inspection unit 43. Furthermore, since it is constructed using black tape 55, costs can be reduced. Also, since it only requires wrapping black tape 55, it can be easily applied to existing equipment.

[0071] The present invention is not limited to the above embodiments and can be modified and implemented as described below. Refer to Figure 4. Figure 4 shows the configuration of the conveying roller in a modified example, and is an enlarged longitudinal cross-sectional view of a part thereof.

[0072] In this modified example, the outer surfaces of the conveyor rollers 45 and 47 are composed of a needle-like structure 57. Specifically, the needle-like structure 57 has a number of recesses 57a and a number of protrusions 57b. Its surface is also composed of a black coating. This configuration ensures that the outer surfaces of the conveyor rollers 45 and 57 are composed of a light-absorbing material. Specifically, it is preferable that the aspect ratio of the recesses 57a and protrusions 57b in the needle-like structure 57 on the outer surfaces of the conveyor rollers 45 and 57 is between 2 and 30. With this structure, light irradiated onto the needle-like structure 57 is absorbed by the needle-like structure, thus suppressing reflection. Furthermore, it is preferable that the black coating be made of a conductive metal. By using a conductive metal, it is possible to improve the ability of powder to enter the conveyor rollers 45 and 47 due to static electricity. Therefore, it is possible to prevent powder from entering the recesses and reducing the light absorption performance. As a result, the performance can be maintained over a long period of time.

[0073] As described above, the outer surfaces of the conveyor rollers 45 and 47 are made of a needle-like structure 57 with numerous recesses 57a and numerous protrusions 57b, and are coated with a black film. Therefore, durability can be improved, and the effect can be maintained over a long period of time. [Examples]

[0074] Next, Embodiment 2 of the present invention will be described with reference to the drawings. Figure 5 is a side view showing the main part of the inspection unit in Embodiment 2.

[0075] The inspection unit 43A in Example 2 is configured as follows.

[0076] The inspection unit 43A differs from the inspection unit 43 in its configuration, specifically in its upper reflective light source 51b1, lower reflective light source 51c1, and transmissive light source 53a. Specifically, the upper reflective light source 51b1 and lower reflective light source 51c1 irradiate the flexible packaging film WF from the right in the transport direction X. However, the direction of light irradiation is narrowed for the upper reflective light source 51b1 and lower reflective light source 51c1. In other words, the upper reflective light source 51b1 and lower reflective light source 51c1 have directionality. This directionality restricts the irradiation of light to the lower outer surface of the transport roller 45 and to the upper outer surface of the transport roller 47 in the height direction Z. However, this directionality does not restrict the irradiation of light to the inspection area IA. The transmissive light source 53a also has similar directionality. Such directionality can be achieved, for example, by devising the lens shape of the light source.

[0077] The upper reflective light source 51b1, the lower reflective light source 51c1, and the transmitted light source 53a described above correspond to the "light irradiation regulating unit" in this invention.

[0078] According to this embodiment, the problem caused by reflected light from the conveyor rollers 45 and 47 can be solved simply by modifying the configuration for light irradiation. [Examples]

[0079] Next, Embodiment 3 of the present invention will be described with reference to the drawings. Figure 6 is a side view showing the main part of the inspection unit in Embodiment 3.

[0080] The inspection unit 43B in Example 3 is configured as follows.

[0081] The inspection unit 43B has a hood 55 on the imaging unit 51 and a hood 57 on the transmitted light source unit 53. Specifically, the hood 55 is attached to the top of the upper reflective light source 51b and the bottom of the lower reflective light source 51c. The hood 57 is attached to the top and bottom of the transmitted light source 53. The hoods 55 and 57 allow illumination of the inspection area IA. On the other hand, the hoods 55 and 57 restrict the illumination of light to the lower outer circumferential surface of the transport roller 45 and the upper outer circumferential surface of the transport roller 47 in the height direction Z.

[0082] The hoods 55 and 57 mentioned above correspond to the "light irradiation restricting section" in this invention.

[0083] According to this embodiment, hoods 55 and 57 are provided to prevent light from irradiating the transport rollers 45 and 47. This allows problems caused by reflected light on the transport rollers 45 and 47 to be solved simply by providing hoods 55 on the upper reflective light source 51b and the lower reflective light source 51c, and hood 57 on the transmitted light source 53. Therefore, it can be easily applied to existing equipment.

[0084] It should be noted that the present invention is not limited to the embodiment in which the hood 55 is attached to the imaging unit 51 and the hood 57 is attached to the light source 53, as described above. In other words, it is sufficient that the shielding members are positioned so that the light from the light source does not reach the outer circumferential surfaces of the transport rollers 45 and 47, and the positions of the hoods 55 and 57 are not limited to the positions described above. [Examples]

[0085] Next, Embodiment 4 of the present invention will be described with reference to the drawings. Figure 7 is a side view showing the main part of the inspection unit in Embodiment 4.

[0086] The inspection unit 43C in Example 4 is configured as follows.

[0087] In the inspection unit 43C, the transport rollers 45 and 47 are positioned with a distance L2 between them in the height direction Z. This distance L2 is longer than the distance L1 of the inspection unit 43 in Embodiment 1. Distance L2 is the length over which the lower outer surface of the transport roller 45 and the upper outer surface of the transport roller 47 are not illuminated by light from the upper reflective light source 51b, the lower reflective light source 51c, and the transmissive light source 53. In other words, the transport rollers 45 and 47 are positioned such that the lower outer surface of the transport roller 45 and the upper outer surface of the transport roller 47 are outside the illumination range of the light from the upper reflective light source 51b, the lower reflective light source 51c, and the transmissive light source 53.

[0088] Furthermore, the transport rollers 45 and 47, which are arranged in the height direction Z at the aforementioned distance L2 interval, correspond to the "light irradiation regulating section" in this invention.

[0089] In this embodiment, the distance L2 between the transport roller 45 and the transport roller 47, which are straddling the inspection area IA on which the flexible packaging film WF is being transported, is set to be outside the illumination range of the upper reflective light source 51b, the lower reflective light source 51c, and the transmitted light source 53. Therefore, problems caused by reflected light from the transport rollers 45 and 47 can be solved without adding any new configurations. [Examples]

[0090] Next, Embodiment 2 of the present invention will be described with reference to the drawings. Figure 8 is a side view showing the main part of the inspection unit in Embodiment 5.

[0091] The inspection unit 43D in Example 5 is configured as follows. The inspection unit 43D has the same configuration as the inspection unit 43 in Example 1 described above. However, its position relative to the transport rollers 45 and 57 is different.

[0092] First, the configuration of this embodiment is the same as that of the inspection unit 43 in Embodiment 1, but with the imaging unit 51 and equivalent plateau 53 positioned in the opposite direction to the flexible packaging film WF being transported by the transport rollers 45 and 47. Specifically, in the inspection unit 43D, the imaging unit 51 is positioned on the left side in the transport direction X with the flexible packaging film WF in the middle. In the inspection unit 43D, the transmitted light source 53 is positioned on the right side in the transport direction X with the flexible packaging film WF in the middle.

[0093] Furthermore, the imaging unit 51 differs from the inspection unit 43 in Embodiment 1 in its position in the transport direction X. In this embodiment, the imaging unit 51 is positioned on the side where the transport rollers 45 and 47 are located (towards the X direction from the flexible packaging film WF) that is transported between the transport rollers 45 and 47, and is positioned between the transport rollers 45 and 47. More preferably, the light-receiving surface of the image sensor 51a is positioned on the side of the center line CL connecting the rotation centers of the transport rollers 45 and 47, rather than the tangent to the left outer peripheral surfaces of both the transport rollers 45 and 47.

[0094] As a result, the imaging unit 51 is positioned between the transport rollers 45 and 57. Therefore, it is possible to suppress light reflected from the outer surface between the transport rollers 45 and 57 from entering the imaging unit 51. Thus, simply by changing the position of the imaging unit 51, problems caused by reflected light from the transport rollers 45 and 47 can be solved.

[0095] <Movement mechanism> Now, refer to Figures 9 and 10. Figure 9 is a side view of the moving mechanism in the inspection unit. Figure 10 is a top view of the moving mechanism in the inspection unit.

[0096] In each of the above-described embodiments 1 to 5, a primer layer is formed in the coating unit 5 before printing so that the ink ejected from the printing unit 7 can be fixed. As a result, powder from the primer layer may adhere to the imaging unit 51 (especially the light-receiving surface), which can hinder accurate inspection. Also, if the printing medium is paper instead of flexible packaging film WF, paper dust may adhere to the imaging unit 51, potentially causing a similar problem. Therefore, it is necessary to periodically clean the side of the imaging unit 51 on which the printing medium is transported. However, if the image sensor 51a of the imaging unit 51 is a CIS (contact image sensor), the depth of field is shallow. As a result, the distance between the light-transmitting surface of the imaging unit 51 and the printing medium is narrow. Consequently, there is a problem in that maintenance of the imaging unit 51 is difficult. It is preferable to have the following moving mechanism 61.

[0097] The moving mechanism 61 fixes the position of the imaging unit 51 relative to the inspection area IA when the inkjet printing device 1 is in operation. On the other hand, during maintenance, the imaging unit 51 is moved away from the inspection area IA and made movable in a direction away from the surface of the flexible packaging film WF.

[0098] Specifically, the moving mechanism 61 comprises a device frame 63 and a pivot pin 65. The transport rollers 45 and 47 are rotatably mounted to the device frame 63. More specifically, the transport rollers 45 and 47 are rotatably mounted to the device frame 63 at both ends with their axis of rotation facing the width direction Y. The pivot pin 65 is inserted through one end of the frame 49 on which the imaging unit 51 is mounted. The pivot pin 65 is positioned so that its axis is parallel to the surface of the flexible packaging film WF. A support plate 67 is erected on the device frame 63, which is at one end of the frame 49. A pinning plate 69 is attached to the upper part of the support plate 67. The pivot pin 65, which protrudes downward from the frame 49, has its lower part inserted through the pinning plate 69. As a result, as shown by the dashed line in Figure 10, the frame 49 can swing along the upper surface of the support plate 67 along a plane consisting of the transport direction X and the width direction Y, with the pivot axis P1 of the pivot pin 65 as the pivot axis. In other words, the imaging unit 51 can swing together with the frame 49 along a plane consisting of the transport direction X and the width direction Y.

[0099] The frame 49 described above corresponds to the "imaging unit frame" in this invention.

[0100] The device frame 63 is equipped with a frame positioning pin 71 that regulates the position of the other end of the frame 49 so that the imaging unit 51 is in focus with the flexible packaging film WF. Specifically, the device frame 63 has a support plate 67 attached to the opposite side of the pivot pin 65 in the width direction Y. The frame positioning pin 71 is attached to the upper part of the support plate 67. The lower part of the frame positioning pin 71 is embedded in the support plate 67, and the upper part protrudes from the upper surface of the support plate 67 in the height direction Z. In addition, an L-shaped plate 73 is attached to the side of the other end of the frame 49. As shown in Figure 10, the L-shaped plate 73 has the shape of the letter L in a plan view. The horizontal portion of the L-shaped plate 73 in the width direction Y abuts against the frame positioning pin 71. With the L-shaped plate 73 in contact with the frame positioning pin 71, the L-shaped plate 73 is fixed to the support plate 67 by a screw 75, and the position of the frame 49 is fixed.

[0101] The inclusion of the moving mechanism 61 allows the imaging unit 51 to be moved away from the surface of the flexible packaging film WF during maintenance. Therefore, powder and other debris that have detached from the flexible packaging film WF can be easily removed from the imaging unit 51. Thus, accurate inspections can be performed over a long period of time. Furthermore, the frame positioning pin 71 restricts the position of the other end of the frame 49 so that the imaging unit 51 is in focus. Therefore, even after the frame 49 has been swung for maintenance of the imaging unit 51 and then returned to its original position, imaging by the imaging unit 51 can be performed appropriately.

[0102] Furthermore, it is preferable that the frame 49 is configured as shown in Figures 10 to 12. Figure 10 is a plan view of the moving mechanism in the inspection unit. Figure 11 is a front view of the imaging unit moving mechanism in the inspection unit. Figure 12 is a plan view of the imaging unit moving mechanism in the inspection unit.

[0103] In other words, it is preferable that the frame 49 is equipped with an imaging unit moving mechanism 81 that allows the imaging unit 51 to move in the transport direction X relative to the inspection area IA.

[0104] The imaging unit movement mechanism 81 includes a mounting plate 83, a rail 85, an imaging unit positioning pin 87, a regulating piece 89, and a screw 91.

[0105] Mounting plates 83 are attached to both ends of the imaging unit 51 in the width direction Y. Mounting plates 83 are L-shaped. Rails 85 are attached to the frame 49 below the mounting plates 83. When viewed from the transport direction X, the rails 85 have a groove in the center. The groove of the rails 85 is formed along the transport direction X. The imaging unit positioning pins 87 are mounted protruding downward from the lower surface of the mounting plates 83. A restricting piece 89 is fixed to the groove of the rail 85. The restricting piece 89 is fixed to the flexible packaging film WF side in the transport direction X. When the imaging unit 51 is moved along the transport direction X with the imaging unit positioning pins 87 inserted into the groove of the rail 85, the imaging unit positioning pins 87 come into contact with the restricting piece 89 and restrict movement. This position is set to be the focus position where the imaging unit 51 is in focus with the printed image in the inspection area IA of the flexible packaging film WF. With the imaging unit positioning pin 87 in contact with the restricting piece 89 and its movement restricted, the screw 91 is attached. This fixes the imaging unit 51 to the frame 49 in the focused position.

[0106] By providing the imaging unit movement mechanism 81 in this way, the imaging unit 51 can be easily set to the focused position even when it is moved during maintenance.

[0107] The present invention is not limited to the embodiments described above, and can be modified and implemented as follows.

[0108] (1) In the embodiments described above, a transparent film, WF, used as the printing medium was explained as an example. However, the present invention is not limited to such a printing medium. For example, the present invention can also be applied to translucent films or translucent paper media.

[0109] (2) In each of the embodiments described above, the inkjet printing apparatus 1 is equipped with a coating unit 5 to form a primer layer. However, if the printing unit 7 ejects oil-based ink, it is not necessary to have a coating unit 5.

[0110] (3) In each of the embodiments described above, the inspection units 43, 43A to 43D are equipped with an upper reflective light source 51 (51b1) and a lower reflective light source 51c (51c1). However, the present invention does not necessarily require the provision of two reflective light sources.

[0111] (4) In each of the embodiments described above, the inspection units 43, 43A to 43D are equipped with a transmitted light source 53. However, the present invention does not require a transmitted light source 53. In other words, even if only a reflected light source is provided, such as the upper reflected light source 51b and the lower reflected light source 51c, the present invention can be applied because it can suppress the adverse effects of reflection from the conveying rollers 45 and 57 caused by the reflected light source. Furthermore, the present invention can also be applied even if only a transmitted light source 53 is provided. [Industrial applicability]

[0112] As described above, the present invention is suitable for an inspection device that reads an image on a transparent printing medium and inspects the printing condition, and for an inkjet printing device equipped therewith. [Explanation of Symbols]

[0113] 1. Inkjet printing device 3 … Paper feed section 5. Coating area 7 … Printing department 9… Main drying section 11 ... Paper output section WF… Flexible packaging film 19… Color Printing Department 25 … White printing section 43 (43A~43D) ... Inspection Department 45, 47 ... Conveyor rollers 49… Frame 51… Photography Department 51a ... Image sensor 51b, 51b1 … Upper reflective light source 51c, 51c1 … Bottom reflective light source 53, 53a... Transmitted light source L1,L2 … distance IA… Inspection area 55... Black tape 57 … needle-like structure 55, 57 ... Food CL … Center line 61 … Movement mechanism 63 ... Device frame 65 ... Oscillating pin P1 ... Oscillating axis 81... Camera unit movement mechanism 85... Rail 87… Imaging unit positioning pin

Claims

1. In an inspection device that reads a printed image printed on a transparent printing medium and inspects the printing condition, A first transport roller for transporting the transparent printing medium, A second conveyor roller is positioned downstream in the conveying direction, spaced apart from the first conveyor roller, and conveys the transparent printing medium. A photographing unit is positioned between the first transport roller and the second transport roller, on one side of the transparent printing medium, and photographs a printed image located in an inspection area set between the first transport roller and the second transport roller. The aforementioned imaging unit emits light to capture a printed image located in the inspection area, and the light irradiation unit emits light to capture the printed image located in the inspection area. The device comprises a frame on which the first and second conveying rollers are rotatably mounted, The imaging unit is equipped with a movement mechanism that, during operation, has a fixed position relative to the inspection area, and during maintenance, can move away from the inspection area and away from the surface of the transparent printing medium. The moving mechanism has a long axis in the width direction of the transparent printing medium, and with the imaging unit attached, the imaging unit frame is attached to the device frame, The pivot shaft is positioned so as to be parallel to the surface of the transparent printing medium, and is provided on one end of the imaging unit frame, An inspection device characterized by having the following features.

2. In the inspection apparatus according to Claim 1, The inspection apparatus is characterized in that the apparatus frame is provided with a frame positioning pin that restricts the position of the other end of the imaging unit frame so that the imaging unit is in focus with respect to the printed image on the transparent printing medium.

3. In the inspection apparatus according to claim 1 or 2, The inspection apparatus is characterized in that the imaging unit frame is arranged on both ends of the imaging unit in the width direction of the transparent printing medium, and the imaging unit is configured to be movable relative to the transparent printing medium at both ends of the rail, and the imaging unit positioning pins restrict the position of the imaging unit on the rail so that the imaging unit is in a focus position where it is in focus with respect to the printed image on the transparent printing medium.

Images