Inspection device and inspection method

Abstract

To eliminate an influence of an image of a holding surface holding an inspection medium.SOLUTION: An inspection device includes: a paper suction part that suctions an inspection medium on which an image is formed on a medium; a reading part that reads the image of the inspection medium; and an inspection part that inspects the inspection medium by comparing an inspection image 35a obtained by performing an image processing on an inspection read image 34a read by the reading part with a reference image 33a. A suction surface of the paper suction part is a non-plain surface having a plurality of suction holes 7a, and the inspection part changes one or both of the inspection image and the reference image based on a transmittance of the medium. The reference image 33a is a difference image between the reference medium on which the image is formed on a transparent medium held by the paper suction unit and a background image 32a obtained by imaging the transparent medium held by the paper suction unit, and the inspection image 35a is a difference image between the image obtained by reading the inspection medium by the reading part and the background image 32b.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an inspection device and an inspection method, and more particularly to an inspection device that inspects the quality of a light-transmitting medium on which an image is formed by adsorbing it onto a cylindrical drum. [Background technology]

[0002] The inspection device inspects for defects such as defects in images formed on media and dirt adhering to the media on which the image is formed. Patent Document 1 discloses a technique for inspecting the surface of a liquid crystal display, in which a difference between an image of the area to be inspected and a background image is taken to remove streaks other than those being inspected. This background image is created by capturing multiple images of a sample with as few defects as possible, creating an average image of these, and then extracting only the screen portion of the area to be inspected from that image. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-219072 A (paragraph 0030, Figure 3(a)(b)) Summary of the Invention [Problem to be solved by the invention]

[0004] When an image is formed by adsorbing and holding a medium on a cylindrical drum, the medium may be a light-transmitting medium, such as a transparent medium or a semi-transmitting medium. The drum may also have multiple holes for adsorption. Therefore, when an inspection device inspects an image formed on the light-transmitting medium, the multiple holes are visible through the medium. To remove the image of the adsorption surface (holding surface) that adsorbs (holds) the inspection medium on the drum, the inspection device may apply the technology described in Patent Document 1. However, the background image described in Patent Document 1 is based on an average image of multiple images of a defect-free sample. In other words, the technology described in Patent Document 1 detects defects in the medium itself. Therefore, the technology described in Patent Document 1 cannot be applied to an invention that addresses the problem of background image transmission through a light-transmitting medium.

[0005] The present invention has been made in consideration of the above problems, and aims to provide an inspection device and an inspection method that can eliminate the influence of an image on a holding surface that holds an inspection medium. [Means for solving the problem]

[0006] The above-mentioned problems of the present invention can be solved by the following means.

[0007] (1) An inspection device comprising a holding unit (adsorption unit) that holds (adsorbs) an inspection medium (image-forming medium) on which an image is formed, a reading unit that reads the image on the inspection medium, and an inspection unit that inspects the inspection medium by comparing the inspection image obtained by image processing the read image read by the reading unit with a reference image (comparison image), wherein the holding surface of the holding unit is a non-plain surface (e.g., a surface having multiple adsorption holes), and the inspection unit changes either or both of the inspection image and the reference image based on the translucency of the medium.

[0008] (2) The medium is a transparent medium (translucent plain medium), and the inspection device described in (1) is further provided with a background image generation unit that generates a background image obtained by capturing an image of the holding surface without a medium or a background image obtained by capturing an image of the transparent medium held in the holding unit, and the reference image is a differential image between the image-formed transparent medium on which the image is formed on the transparent medium held in the holding unit and the background image, and the inspection image is a differential image between an image of the inspection medium read by the reading unit and the background image.

[0009] (3) The medium is a transparent medium, and the inspection device described in (1) further includes a background image generation unit that generates a background image obtained by capturing an image of the holding surface when no medium is present or a background image obtained by capturing an image of the transparent medium held in the holding unit, the reference image is a composite image obtained by combining an image formed on the medium with the background image, and the inspection image is an image obtained by reading the inspection medium with the reading unit.

[0010] (4) The medium is a translucent medium, and the inspection device described in (1) further includes a background image generation unit that generates a background image by capturing an image of the translucent medium held in the holding unit, the reference image is a differential image between an image-forming medium on which the image is formed on the translucent medium held in the holding unit and the background image, and the inspection image is a differential image between an image of the inspection medium read by the reading unit and the background image.

[0011] (5) The medium is a translucent medium, and the inspection device described in (1) further includes a background image generation unit that generates a background image by capturing an image of the translucent medium held in the holding unit, the reference image is a composite image that combines an image when an image is formed on the medium with the background image, and the inspection image is an image read from the inspection medium by the reading unit.

[0012] (6) The inspection device according to any one of (2) to (5), wherein the reference image is only a print area.

[0013] (7) An inspection device described in any of (2) to (5), wherein the translucency of the medium is the transmittance of the medium, and the inspection unit performs an inspection operation when the transmittance of the medium is higher than a reference value.

[0014] (8) The inspection device according to any one of (2) to (5) above, wherein the density of the background image is changed depending on the transmittance of the medium.

[0015] (9) The inspection device according to (7), further comprising an input unit that enables the transmittance to be specified.

[0016] (10) The inspection device according to (7), further comprising a medium measuring unit that measures the transmittance of the medium.

[0017] (11) The inspection device according to any one of (2) to (5) above, which adjusts the color of the background image depending on the color of the medium.

[0018] (12) The inspection device according to (11) above, further comprising a medium measurement unit that measures the color of the medium.

[0019] (13) An inspection device according to any one of (2) to (5), wherein the holding unit is a rotating body, the holding surface is a cylindrical surface divided into multiple parts in the direction of rotation, multiple background images are stored for each divided surface, and the inspection unit compares images while recognizing the images of the individual divided surfaces.

[0020] (14) The inspection medium is a medium on which different images are formed, and the reference image is stored in a memory unit across multiple pages from the first page to correspond to the inspection medium, and the inspection unit feeds the rotating body empty until the suction surface on which the medium is adsorbed to the rotating body coincides with the suction surface of the first page of the reference image, and performs image formation and inspection from the point of agreement.

[0021] (15) The inspection medium is a medium on which different images are formed, and the reference image is stored in a memory unit across multiple pages from the first page to correspond to the inspection medium, and the inspection unit transports the medium until the suction surface on which the medium is adsorbed to the rotating body coincides with the suction surface of the first page of the reference image, and performs image formation and inspection from the point of agreement.

[0022] (16) The inspection device described in (13) above, wherein the inspection unit recognizes the adsorption position of the medium by comparing an image of the adsorption surface where the medium is adsorbed to the rotating body with images of each division surface stored in the memory unit.

[0023] (17) The inspection device described in (13) further includes a drive unit that rotates the rotating body, and the inspection unit recognizes the suction position of the medium using rotation angle information of the rotating body detected by a sensor.

[0024] (18) An inspection device as described in (13) above, in which the divided surfaces of the cylindrical surface are assigned codes that identify the divided surfaces, and the inspection unit uses the codes to recognize the suction position of the medium.

[0025] (19) An inspection device that can select between the inspection device described in (3) or (5) above and the inspection device described in (2) or (4) above.

[0026] (20) The inspection device according to (1) above, which suspends image formation and inspection when it is determined that the inspection operation is not to be performed during inspection.

[0027] (21) The inspection device according to (1) above, wherein if it is determined that the inspection operation will not be performed during inspection, subsequent inspection media are discharged to a sorter different from that for the media for which inspection has been completed.

[0028] (22) The inspection device according to (1) above, which, if it is determined during inspection that the inspection operation will not be performed, marks the edges of the subsequent printed sheets to indicate that they have not yet been inspected.

[0029] (23) An inspection method performed by an inspection device that includes a holding unit that holds an inspection medium on which an image is formed and has a non-plain holding surface, a reading unit that reads the image on the inspection medium, and an inspection unit that inspects the inspection medium by comparing an inspection image obtained by image processing the read image read by the reading unit with a reference image, wherein the inspection unit changes either or both of the inspection image and the reference image based on the translucency of the medium. [Effects of the Invention]

[0030] According to the present invention, it is possible to eliminate the influence of an image on the holding surface that holds the inspection medium. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a configuration diagram of an inspection device according to each embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing a configuration of the periphery of an image forming unit of the inspection device. [Figure 3A] FIG. 1 is a diagram showing the structure of a holding unit that holds an inspection medium. [Figure 3B] FIG. 2 is a diagram showing the structure of the holding unit that holds the inspection medium. [Figure 3C] FIG. 3 is a diagram showing the structure of the holding unit that holds the inspection medium. [Figure 4] 1A and 1B are diagrams illustrating an inspection method according to a first embodiment of the present invention, in which an inspection image obtained by subtracting a background image from a scanned image of an inspection medium is compared with a reference image for inspection. [Figure 5] 5 is a flowchart illustrating a method for generating a reference image in the inspection method according to the first embodiment of the present invention. [Figure 6] 10A and 10B are diagrams for explaining a method for a reading unit to read a background image. [Figure 7] 10A and 10B are diagrams for explaining a method of reading a reference read image or an inspection read image. [Figure 8]5 is a flowchart illustrating a method of generating an inspection image and comparing it with a reference image in the inspection method according to the first embodiment of the present invention. [Figure 9] 10A and 10B are diagrams illustrating an inspection method according to a second embodiment of the present invention, in which an inspection image obtained by combining a scanned image of an inspection medium with a background image is compared with a reference image for inspection. [Figure 10] 10 is a flowchart illustrating a method of generating an inspection image and comparing it with a reference image in an inspection method according to a second embodiment of the present invention. [Figure 11] 10A and 10B are diagrams illustrating an inspection method according to a third embodiment of the present invention, in which an inspection image obtained by subtracting a background image from a scanned image of an inspection medium is compared with a reference image for inspection. [Figure 12] 10A and 10B are diagrams illustrating an inspection method according to a fourth embodiment of the present invention, in which an inspection image obtained by combining a scanned image of an inspection medium with a background image is compared with a reference image for inspection. [Figure 13] FIG. 13 is a diagram showing an example of an operation setting screen in the fifth embodiment of the present invention. [Figure 14] 10A and 10B are diagrams illustrating an example of a medium on which a mark indicating that inspection has been stopped when the inspection device has stopped the inspection operation. [Figure 15] 13 is a flowchart illustrating an inspection interruption process executed in an inspection method according to a fifth embodiment of the present invention. [Figure 16] FIG. 10 is a diagram showing an example of a designation screen for designating an action to be taken when inspection is interrupted. [Figure 17] 10 is a flowchart illustrating an inspection method according to a sixth embodiment of the present invention. [Figure 18] 13 is a flowchart illustrating a method of generating an inspection image and comparing it with a reference image in an inspection method according to a sixth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] In the following embodiments, the present invention will be described in detail with reference to the drawings. Note that each drawing is merely a schematic illustration to allow a sufficient understanding of the present invention. Therefore, the present invention is not limited to the illustrated examples. In addition, in each drawing, common or similar components are given the same reference numerals, and redundant explanations thereof will be omitted.

[0033] The inspection device 100 of an embodiment of the present invention comprises a holding unit (e.g., drum 6) that holds (adsorbs) an inspection medium (image-forming medium) on which an image is formed on a medium P, a reading unit (1) that reads the image on the inspection medium, and an inspection unit (25) that inspects the inspection medium by comparing an inspection image obtained by image-processing the read image read by the reading unit with a reference image (comparison image), and the holding surface (adsorption surface 6d) of the holding unit is a non-plain surface (e.g., a surface having multiple adsorption holes), and the inspection unit changes either or both of the inspection image and the reference image based on the translucency (e.g., transmittance) of the medium.

[0034] (First embodiment) FIG. 1 is a configuration diagram of an inspection device according to a first embodiment of the present invention. The inspection device 100 inspects an inspection medium (particularly a light-transmitting medium such as a transparent medium or a semi-transmitting medium) on which an image is formed. The inspection device 100 comprises an image forming unit 10, a display operation unit 9, a control unit 20, and a memory unit 30. The image forming unit 10 forms an image on a medium P (FIG. 2) that is adsorbed to a cylindrical drum 6 (FIG. 2). The image forming unit 10 comprises a reading unit 1, a medium measuring unit 2, a printing unit 3, and a drive unit 4. The display operation unit 9 is a touch panel that functions as an input unit and a display unit.

[0035] FIG. 2 is a schematic diagram showing the structure of the image forming unit and its surroundings in the inspection device. Image forming unit 10 includes drum 6, reading unit 1, medium measurement unit 2, printing unit 3, and rollers 8a and 8b. Drum 6 is a cylindrical rotating body with three paper suction units 6a, 6b, and 6c arranged on its surface in the direction of rotation (see white arrows). In other words, drum 6 is a rotating body with a cylindrical surface divided into multiple sections in the direction of rotation.

[0036] The reading unit 1 is a line sensor that reads an image formed on the medium P being transported. The medium measurement unit 2 is a media sensor that detects the light transmittance and color (hue, saturation, brightness, etc.) of the medium (paper sheet). The printing unit 3 prints with ink or toner on the medium P that is adsorbed to and transported on the surface of the drum 6. The roller 8a feeds the medium P onto the drum 6. The roller 8b ejects the medium P from the drum 6.

[0037] 3A, 3B, and 3C are diagrams showing the structure of a paper suction section serving as a holding section that holds a medium. The paper suction sections 6a, 6b, and 6c are provided on the surface of the drum 6. A PFA (Perfluoroalkoxy Alkane) sheet 7c is attached to the top surface of a rectangular SUS (Steel Special Use Stainless Steel) sheet 7b. The SUS sheet 7b and the PFA sheet 7c have multiple suction holes 7a. In other words, the surfaces of the paper suction sections 6a, 6b, and 6c are not plain and function as suction surfaces 6d (Figure 2) that suction (hold) media.

[0038] A claw 7d is provided on one side of the paper suction units 6a, 6b, and 6c to prevent mechanical misalignment in the transport direction. A code (for example, the number "1") is printed on the claw 7d of the paper suction unit 6a to distinguish it from the paper suction units 6b and 6c. The number "2" is printed on the claw 7d of the paper suction unit 6b, and the number "3" is printed on the claw 7d of the paper suction unit 6c.

[0039] Returning to the explanation of FIG. 1, the drive unit 4 rotates a transport mechanism such as rollers 8a and 8b (FIG. 2) that transport the medium, and the drum 6 (FIG. 2). The drive unit 4 has a sensor (e.g., a rotary encoder) that detects rotation angle information of the drum 6. The storage unit 30 is a volatile storage unit such as a RAM (Random Access Memory) or a non-volatile storage unit such as an HDD (Hard Disk Drive) or SSD (Solid State Drive). The storage unit 30 has areas for storing a reference scanned image 31, a background image 32, a reference image 33, an inspection scanned image 34, and an inspection image 35.

[0040] The control unit 20 is a CPU (Central Processing Unit) that executes programs to realize functions such as image formation and inspection. The control unit 20 realizes the following functional units: an inspection unit 25, a background image generation unit 21, a reading control unit 22, a drive control unit 23, and a display operation control unit 24. The inspection unit 25 generates an inspection image 35 (35a (FIG. 4), 35b (FIG. 9), 35c (FIG. 11), 35d (FIG. 12)). This inspection image 35 is based on an inspection read image 34 (34a (FIG. 4), 34b (FIG. 11)) obtained by reading, by the reading unit 1, the surface of an inspection medium on which an image is formed, such as a transparent medium or a semi-transparent medium, and which is a light-transmitting medium. Furthermore, the inspection unit 25 inspects the generated inspection images 35 (35a, 35b, 35c, 35d) by comparing them with the reference images 33 (33a (FIG. 4), 33b (FIG. 9), 33c (FIG. 11), 33d (FIG. 12)). In other words, the reference images 33 can be said to be comparison images to be compared with the inspection images 35.

[0041] The background image generation unit 21 generates background images 32 (32a (Fig. 4), 32b (Fig. 4), 32c (Fig. 9), 32d (Fig. 11), 32e (Fig. 11), 32f (Fig. 12)). This background image 32 is what the reading unit 1 sees on the surfaces of the paper suction units 6a, 6b, 6c through a light-transmitting medium such as a transparent medium or a semi-light-transmitting medium. The reading control unit 22 controls the reading unit 1. The drive control unit 23 controls the drive unit 4. The display operation control unit 24 controls the display operation unit 9.

[0042] The inspection unit 25 changes either or both of the inspection image 35 and the reference image 33 based on the light transmittance (transmittance) of the medium. That is, the inspection image 35 and the reference image 33 are changed not only in this embodiment but also in the second, third, and fourth embodiments described later. In this embodiment, the inspection image 35 and the reference image 33 are obtained by subtracting the background image 32 from the scanned image (the reference scanned image 31 or the inspection scanned image 34) (see FIG. 4).

[0043] The inspection image 35, the reference image 33, and the background image 32 are generated for each of the divided surfaces obtained by dividing the cylindrical surface of the drum 6 into a plurality of parts, and each image is stored in the storage unit 30. The inspection unit 25 performs inspection by comparing the inspection image 35 with the reference image 33 while recognizing the image of each divided surface.

[0044] The inspection unit 25 includes a reference image generation unit 11, an inspection image generation unit 12, a comparison / determination unit 13, an image subtraction unit 14, an image synthesis unit 15, and a RIP (Raster Image Processor) unit 16. The reference image generation unit 11 generates a reference image 33 (33a (FIG. 4), 33b (FIG. 9), 33c (FIG. 11), 33d (FIG. 12)). This reference image 33 is based on an image of a reference medium (reference scanned image 31 (31a (FIG. 4), 31b (FIG. 11))) that is ideally formed on a light-transmitting medium that is free of scratches and defects. The inspection image generation unit 12 generates inspection images 35 (35a (FIG. 4), 35b (FIG. 9), 35c (FIG. 11), 35d (FIG. 12)) based on images of the inspection medium that are formed on multiple sheets of light-transmitting medium.

[0045] The comparison and determination unit 13 compares the inspection image 35 with the reference image 33 to inspect the inspection medium. The image subtraction unit 14 subtracts the background image 32 from the scanned image (reference scanned image 31 or inspection scanned image 34) when obtaining the inspection image 35 or the reference image 33 (see FIGS. 4 and 11). The image synthesis unit 15 synthesizes the scanned image and the background image 32 (see FIGS. 9 and 12). The RIP unit 16 converts input image, font, and other data into halftone dot data, and converts colors into YMCK four-color halftone dot data. The RIP unit 16 also generates a RIP image 36a (FIG. 9) including the material image 37 (FIG. 4).

[0046] 4 is a diagram illustrating an inspection method according to a first embodiment of the present invention. In this embodiment, an inspection image obtained by subtracting a background image from a scanned image of the surface of an inspection medium formed with an image on a transparent medium is compared with a reference image. The reference scanned image 31a is an image obtained by the reading unit 1 reading the suction surface 6d (FIG. 2) of the drum 6 when a reference medium (image-formed transparent medium) having a material image 37 formed on a transparent medium (light-transmitting plain medium) is adsorbed to the suction surface 6d. Here, the material image 37 is, for example, an image of a spade mark. Images of the paper adsorption sections 6a, 6b, and 6c (FIGS. 3A, 3B, and 3C) (particularly, images of the multiple suction holes 7a) appear outside the material image 37 in the reference scanned image 31a. The background image 32a is an image of the suction surface 6d (FIG. 2) when a transparent medium is adsorbed to the suction surface 6d. This background image 32a may be an image obtained by the reading unit 1 reading the image of the suction surface 6d without a medium. The background image 32a can be called a holding surface image because it is an image of the suction surface 6d as a holding surface.

[0047] The reference image 33a is an image obtained by subtracting the background image 32a from the reference scanned image 31a. In the reference image 33a, the images of the multiple suction holes 7a (FIGS. 3A, 3B, and 3C) that were visible outside the material image 37 have been deleted. However, the shapes of the multiple suction holes 7a are visible inside the material image 37a. In other words, the subtraction causes the color of the suction holes 7a or the color around the suction holes 7a to change inside the material image 37a.

[0048] The inspection read image 34a is an image obtained by reading the surface of an inspection medium, on which an inspection image 38 is formed, by the reading unit 1. The inspection image 38 is the same image as the material image 37. In this case, the inspection read image 34a includes not only the inspection image 38 and an image of the suction surface 6d (FIG. 2) of the paper suction units 6a, 6b, and 6c (FIGS. 3A, 3B, and 3C) (particularly, images of the multiple suction holes 7a), but also a defective print image 39. The background image 32b is the same image as the background image 32a described above. The inspection image 35a is an image obtained by subtracting the background image 32b from the inspection read image 34a. The defective print image 39 remains in the inspection image 35a. In addition, as with the reference image 33a, images of the multiple suction holes 7a that were visible outside the inspection image 38 have been deleted from the inspection image 35a. Furthermore, the shapes of the plurality of suction holes 7a are reflected inside the inspection image 38a.

[0049] The comparison / determination unit 13 (FIG. 1) compares the inspection image 35a with the reference image 33a. Both the inspection image 35a and the reference image 33a contain images of multiple suction holes 7a reflected within the material image 37 and the inspection image 38. Therefore, the only difference between the inspection image 35a and the reference image 33a is the defective print image 39. Note that the read display image 33e and the inspection display image 35e are shown on the right side of FIG. 4. The read display image 33e and the inspection display image 35e are displayed by the display operation unit 9 in place of the reference image 33a and the inspection image 35a, as necessary. The read display image 33e contains only the material image 37, while the inspection display image 35e contains the inspection image 38 and the defective print image 39.

[0050] FIG. 5 is a flowchart for explaining a method for generating a reference image in the inspection method according to the first embodiment of the present invention. In this embodiment, it is assumed that multiple (three) background images 32 (images of the suction surfaces 6d (FIG. 2) of the paper suction units 6a, 6b, and 6c) are stored in advance in the memory unit 30. That is, as shown in FIG. 6, it is assumed that the drum 6 (FIG. 2) is holding a transparent medium, and the reading unit 1 is capturing an image of the surface of the paper suction units 6a, 6b, and 6c. Here, it is assumed that the rotation of the drum 6 is stopped and medium transport (empty feeding) is performed so that the alignment of the medium (paper) with the paper suction units 6a, 6b, and 6c is completed. Note that FIG. 6 shows the area of ​​the transparent medium 40, the print area 41, and the outside of the print area 42.

[0051] When the flow starts, the inspection unit 25 uses the medium measurement unit 2 to measure the medium transmittance (in this embodiment, the transmittance is 100% since the medium is transparent) (step S1). After processing step S1, the reference image generation unit 11 prints the material image 37 (FIG. 4) on the medium, as shown in FIG. 7 (step S2). Note that reference numeral 43 in FIG. 7 denotes the image formation medium on which the image is formed. After processing step S2, the reading control unit 22 causes the reading unit 1 to scan the medium (in this embodiment, a transparent medium) on which the material image 37 is formed (step S3).

[0052] After the process of step S3, the reference image generating unit 11 identifies a background image 32a using the reference scanned image 31a scanned in step S3 (step S4). Specifically, the reference image generating unit 11 uses the reference scanned image 31a to identify a background image from multiple (three) background images (images (holding surface images) of the suction surfaces 6d of the paper suction units 6a, 6b, and 6c) stored in the storage unit 30. After the process of step S4, the reference image generating unit 11 corrects the density of the background image 32a (FIG. 4) identified in step S3 using the transmittance of the medium measured in step S1 (step S5). Note that in this embodiment, the transmittance is 100%, so density correction of the background image 32a is not actually performed. After the process of step S5, the image subtracting unit 14 subtracts the background image 32a from the reference scanned image 31a to generate a difference image (reference image 33a) (step S6). After processing step S6, the reference image generation unit 11 determines the print area 41 ( FIG. 6 ) from the difference image (reference image 33a) (step S7). The print area 41 refers to an area where no change occurs when, for example, the outer edges of the reference image 33a and the reference scanned image 31a are compared. After processing step S7, the reference image generation unit 11 extracts the print area 41 determined in step S7 from the reference scanned image 31a ( FIG. 4 ) scanned in step S3 (step S8). After processing step S8, the reference image generation unit 11 stores the image extracted in step S8 in the storage unit 30 as a reference image (step S9). After processing step S9, the reference image generation unit 11 determines whether the printing, scanning, etc. of the material image 37 is the final page (step S10). If it is not the final page (No in step S10), the process returns to step S1, and the reference image generation unit 11 prints the material image of the next page on a medium. On the other hand, if it is the last page (Yes in step S10), the processing in FIG. 5 ends.

[0053] FIG. 8 is a flowchart for explaining a method of generating an inspection image and comparing it with a reference image in the inspection method according to the first embodiment of the present invention. The inspection image generating unit 12 measures the medium transmittance using the medium measuring unit 2 (step S11). After processing step S11, the inspection image generating unit 12 prints the inspection image 38 (FIG. 4) on a medium (transparent medium in this embodiment) as shown in FIG. 7 (step S12). After processing step S12, the reading control unit 22 causes the reading unit 1 to scan the medium (transparent medium) on which the inspection image 38 is formed (step S13).

[0054] After the process of step S13, the inspection image generation unit 12 identifies the background image 32b using the inspection read image 34a (FIG. 4) scanned in step S13 (step S14). After the process of step S14, the inspection image generation unit 12 corrects the density of the background image 32b (FIG. 4) identified in step S14 using the transmittance of the medium measured in step S11 (100% in this embodiment) (step S15). Note that in this embodiment, since the transmittance is 100%, density correction of the background image 32b is not substantially performed. After the process of step S15, the image subtraction unit 14 subtracts the background image 32b from the inspection read image 34a to generate a difference image (inspection image 35a) (step S16). After the process of step S16, the inspection image generation unit 12 determines the print area 41 (FIG. 6) from the difference image (inspection image 35a) (step S17). The print area 41 refers to an area where there is no change when comparing the outer edges of the inspection image 35a and the inspection read image 34a, for example. If the area determined in step S7 (FIG. 5) is larger, the larger area is used as the print area 41. After processing in step S17, the inspection image generation unit 12 extracts the print area 41 determined in step S17 from the inspection read image 34a (FIG. 4) scanned in step S13 (step S18).

[0055] After processing step S18, the comparison and judgment unit 13 (FIG. 1) compares the image extracted in step S18 with the reference image stored in the memory unit 30 in step S9 (FIG. 5) (step S19) and inspects it. After processing step S19, the comparison and judgment unit 13 determines whether the inspection result is OK (step S20). If the inspection result is OK (Yes in step S20), the drive control unit 23 (FIG. 1) controls the image to be sent to a sorter for OK images (step S21). On the other hand, if the inspection result is NG (No in step S20), the drive control unit 23 controls the image to be sent to a sorter for NG images (step S22). After processing step S21 or S22, the control unit 20 determines whether the printing, scanning, etc. of the inspection image 38 is the final page (step S23). If it is not the last page (No in step S23), the process returns to step S11, and the inspection image generation unit 12 controls to print the inspection image of the next page on the medium. On the other hand, if it is the last page (Yes in step S23), the process in Fig. 8 ends. In other words, the reference images are stored in the memory unit 30 for multiple pages starting from the first page so as to correspond to each page of the inspection medium.

[0056] As described above, according to the inspection device 100 of this embodiment, the reference image 33a is obtained by subtracting the background image 32a from the reference scanned image 31a (FIG. 4) printed on a transparent medium. Furthermore, the inspection image 35a is obtained by subtracting the background image 32b from the inspection scanned image 34a printed on a transparent medium. The inspection device 100 then compares the reference image 33a with the inspection image 35a to inspect the inspection medium.

[0057] If the inspection result is OK, the inspection device 100 sends the inspection medium to a sorter for OK items, and if the inspection result is NG, the inspection device 100 sends the inspection medium to a sorter for NG items.

[0058] (Second embodiment) In the first embodiment, the inspection unit 25 subtracted the background image 32a from the reference scanned image 31a (FIG. 4) printed on a transparent medium to obtain a reference image 33a, and subtracted the background image 32b from the inspection scanned image 34a printed on a transparent medium to obtain an inspection image 35a. The inspection unit 25 then compared the reference image 33a with the inspection image 35a. In this embodiment, the inspection unit 25 sets the reference image 33b as a composite image obtained by combining the RIP image 36a (FIG. 9) when printing the material image with the background image 32c, and compares the reference image 33b with the inspection image 35b printed on a transparent medium.

[0059] 9 is a diagram illustrating an inspection method according to a second embodiment of the present invention, in which an inspection image obtained by combining a scanned image of an inspection medium with a background image is compared with a reference image. The inspection medium is a transparent medium on which an inspection image 38 is formed.

[0060] The RIP image 36a is an image of electronic data when the material image 37 is image-formed on a transparent medium. In the RIP image 36a, the outside (background) of the material image 37 is transparent or translucent. The background image 32c is the same as the background image 32a (FIG. 4) in the above embodiment. In other words, the background image 32c is an image of the suction surface read by the reading unit 1 when the transparent medium is suctioned to the suction surface 6d (FIG. 2) of the drum 6.

[0061] Reference image 33b is a composite image obtained by combining RIP image 36a and background image 32c. In reference image 33b, the outside of material image 37 is replaced with background image 32c, and the inside of material image 37 is material image 37 itself. In other words, unlike reference image 33a (FIG. 4), the shapes of the multiple suction holes 7a (FIGS. 3A, 3B, and 3C) are not reflected inside material image 37. In other words, the inside of material image 37 is not affected by background image 32c. Note that an image (not shown) in which the shapes of the multiple suction holes 7a are reflected is an added image and is distinguished from a composite image.

[0062] Inspection image 35b is a read image obtained by reading an image-formed medium, on which an inspection image 38 is formed, by reading unit 1. Inspection image 35b has a defective print image 39 added thereto. Comparison / determination unit 13 (FIG. 1) performs inspection by comparing reference image 33b with inspection image 35b.

[0063] FIG. 10 is a flowchart for explaining a method of generating an inspection image and comparing it with a reference image in the inspection method according to the second embodiment of the present invention. When the flow starts, the inspection image generation unit 12 measures the medium transmittance using the medium measurement unit 2 (step S31). After processing step S31, the inspection image generation unit 12 prints the inspection image 38 (FIG. 9) on the medium (transparent medium) as shown in FIG. 7 (step S32). After processing step S32, the reading control unit 22 causes the reading unit 1 to scan the medium (transparent medium) on which the inspection image 38 is formed (step S33).

[0064] After the processing of step S33, the inspection image generation unit 12 identifies a background image 32c (FIG. 9) using the inspection read image (not shown) scanned in step S33 (step S34). After the processing of step S34, the inspection image generation unit 12 corrects the density of the background image 32c identified in step S33 and the background portion of the inspection image 35b using the transmittance of the medium measured in step S31 (100% in this embodiment) (step S35). Note that in this embodiment, since the transmittance = 100%, density correction of the background image 32a is not actually performed. The inspection image is generated after the processing of step 35.

[0065] After processing step S35, the comparison and judgment unit 13 (FIG. 1) generates a reference image 33b (FIG. 9) by combining the background image 32c identified in step S34 with the RIP image 36a (FIG. 9) of the page to be inspected (step S39). The comparison and judgment unit 13 compares the inspection image 35b generated in step S39 with the reference image 33b (step S40) and inspects it. After processing step S40, the comparison and judgment unit 13 determines whether the inspection result is OK (step S41). If the inspection result is OK (Yes in step S41), the drive control unit 23 (FIG. 1) controls the sheet to be transported to a sorter for OK sheets (step S42). On the other hand, if the inspection result is NG (No in step S41), the drive control unit 23 controls the sheet to be transported to a sorter for NG sheets (step S43). After processing step S42 or S43, the control unit 20 determines whether the printing, scanning, etc. of the inspection image (not shown) is the final page (step S44). If it is not the final page (No in step S44), the process returns to step S31, and the inspection image generation unit 12 controls to print the inspection image 38 ( FIG. 9 ) of the next page on the medium. On the other hand, if it is the final page (Yes in step S44), the process of FIG. 10 ends.

[0066] As described above, the inspection device 100 of this embodiment obtains the reference image 33b as a composite image obtained by combining the RIP image 36a (FIG. 9) when printing the material image with the background image 32c. The inspection device 100 compares the reference image 33b with the inspection image 35b printed on the transparent medium to inspect the inspection medium.

[0067] (Third embodiment) In the first embodiment, an image is formed on a transparent medium, but it is also possible to form an image on a semi-transparent medium.

[0068] 11 is a diagram illustrating an inspection method according to a third embodiment of the present invention. In this embodiment, an inspection image obtained by subtracting a background image from a scanned image of the surface of an inspection medium formed on a semi-translucent medium is compared with a reference image.

[0069] The reference scanned image 31b is a scanned image obtained by the reading unit 1 reading the adsorption surface 6d (FIG. 2) when a reference medium (image-formed medium) on which a material image 37 is formed is adsorbed to the drum 6. The background image 32d is an image of the adsorption surface read by the reading unit 1 when the semi-transparent medium is adsorbed to the adsorption surface 6d (FIG. 2). The background image 32d has a different density from the background image 32a (FIG. 4). If the semi-transparent medium is colored and transparent, the background image 32d will also have a different color from the background image 32a (FIG. 4).

[0070] The reference image 33c is an image obtained by subtracting the background image 32d from the reference scanned image 31b. In the reference image 33c, similar to FIG. 4, the images of the suction holes 7a that were reflected outside the material image 37 are deleted. However, the shapes of the suction holes 7a (FIGS. 3A, 3B, and 3C) are reflected inside the material image 37.

[0071] The inspection scan image 34b is a scan image obtained by reading the surface of an inspection medium, which has an inspection image 38 formed on a semi-translucent medium, using the reading unit 1. A defective print image 39 is added to the inspection scan image 34b. The background image 32e is the same image as the background image 32d described above. The inspection image 35c is an image obtained by subtracting the background image 32e from the inspection scan image 34b. The defective print image 39 remains in the inspection image 35c. Furthermore, the shapes of the multiple suction holes 7a are reflected inside the spade mark figure corresponding to the inspection image 38.

[0072] The comparison / determination unit 13 (FIG. 1) compares the inspection image 35c with the reference image 33c. Both the inspection image 35c and the reference image 33c contain images of multiple suction holes 7a that are reflected within the material image 37 and the inspection image 38. Therefore, the only difference between the inspection image 35a and the reference image 33a is the defective print image 39. Note that the read display image 33e and the inspection display image 35e are shown on the right side of FIG. 11. As with FIG. 4, the read display image 33e and the inspection display image 35e are displayed by the display operation unit 9 as needed.

[0073] The flowchart is the same as that of the first embodiment (FIGS. 5 and 8), so a detailed description will be omitted. However, since the medium is semi-transparent, the transmittance measured in steps S1 and S11 is less than 100%. Furthermore, the density correction in steps S5 and S15 is essentially performed.

[0074] As described above, according to the inspection device 100 of this embodiment, the reference image 33c is obtained by subtracting the background image 32d from the reference scanned image 31b (FIG. 11) printed on a semi-transparent medium. Furthermore, the inspection image 35c is obtained by subtracting the background image 32e from the inspection scanned image 34b printed on a semi-transparent medium. The inspection device 100 then compares the reference image 33c with the inspection image 35c to inspect the inspection medium.

[0075] (Fourth embodiment) In the second embodiment, an image is formed on a transparent medium, but an image can also be formed on a semi-transparent medium.

[0076] 12 is a diagram illustrating an inspection method according to a fourth embodiment of the present invention, in which an inspection image obtained by combining a scanned image of an inspection medium with a background image is compared with a reference image. This inspection medium is a semi-transparent medium on which an inspection image 38 is formed.

[0077] The RIP image 36b is electronic data used when forming the material image 37 on a semi-transparent medium. The background image 32f is the same as the background image 32e (FIG. 11) in the third embodiment. In other words, the background image 32f is an image of the adsorption surface read by the reading unit 1 when the semi-transparent medium is adsorbed onto the adsorption surface 6d (FIG. 2) of the drum 6.

[0078] Reference image 33d is a composite image obtained by combining RIP image 36b and background image 32f. In reference image 33d, the outside of material image 37 is replaced with background image 32f, and the inside of material image 37 is material image 37 itself. In other words, the shapes of the multiple suction holes 7a (FIGS. 3A, 3B, and 3C) are not reflected inside material image 37.

[0079] The inspection image 35d is an image in which the inspection image 38 is formed on a semi-transparent medium, but in this case, a defective print image 39 is added. The comparison and judgment unit 13 (FIG. 1) performs inspection by comparing the reference image 33d with the inspection image 35d. The flowchart is the same as FIG. 10, so a description of the inspection method will be omitted. However, because the medium is semi-transparent, the transmittance measured in step S31 will be less than 100%. Furthermore, the density correction in step S35 is essentially performed.

[0080] As described above, the inspection device 100 of this embodiment generates a composite image by combining the RIP image 36b (FIG. 12) when printing the material image with the background image 32f, thereby obtaining the reference image 33d. The inspection device 100 compares the reference image 33d with the inspection image 35d printed on the semi-translucent medium, thereby inspecting the inspection medium.

[0081] (Fifth embodiment) In each of the above embodiments, the inspection device 100 performs inspection regardless of the transmittance of the medium, but if the transmittance of the medium is lower than a reference value, it may be better to suspend inspection. In this embodiment, the operator uses the operation setting screen 200 (FIG. 13) to specify the inspection suspension criteria and the medium removal method when the inspection operation is suspended.

[0082] FIG. 13 is a diagram showing an example of an operation setting screen in the fifth embodiment of the present invention. On the operation setting screen 200, a "Subtraction mode" button 201 and a "Combination mode" button 202 are arranged for the character string "1. Comparison method during inspection." When the "Subtraction Mode" button 201 is pressed, the inspection device 100 executes the inspection method of the first embodiment or the third embodiment depending on the medium type (transparent medium or semi-translucent medium). On the other hand, when the "Composition Mode" button 202 is pressed, the inspection device 100 executes the inspection method of the second embodiment or the fourth embodiment depending on the medium type.

[0083] The operation setting screen 200 has a medium transmittance input box 203 for the character string "2. Lower limit of medium transmittance for enabling inspection operation." The medium transmittance input box 203 functions as an input unit that allows the transmittance of the medium to be specified. In the case of the inspection methods of the third and fourth embodiments, it may be undesirable if the transmittance of the semi-transparent medium is too low compared to the reference value. Therefore, the inspection device 100 is configured so that the operator sets the lower limit of the medium transmittance. In other words, the inspection device 100 performs the inspection operation of each of the above embodiments when the measured value of the transmittance measured by the medium measurement unit 2 is higher than the reference value.

[0084] On the operation setting screen 200, a "pause" button 204, a "discharge to another sorter" button 205, and a "record on paper" button 206 are arranged for the character string "3. Specify the carrying-out method when inspection operation is stopped." These buttons are used to select whether to pause the inspection device 100 when it stops its inspection operation, to transport the media to a sorter other than the sorter that transports the media when it is normally inspected, or to record a mark on the paper (inspection medium). Here, a mark 44 (FIG. 14) that is recorded when the "Record on Paper" button 206 is pressed indicates that the media has not been inspected (uninspected due to inspection being stopped), and is placed outside the print area 42 of the inspection medium (for example, at the edge of the paper with the printed results). Note that inspection media with the mark 44 (FIG. 14) placed on them are transported to the same sorter that transports the media when it is normally inspected.

[0085] FIG. 14 is a diagram showing an example of a medium on which a mark indicating that inspection has been stopped when the inspection device 100 has stopped the inspection operation is attached. The inspection medium has an inspection image 38 formed in a print area 41, and a mark 44 formed as an image outside the print area 42.

[0086] 15 is a flowchart illustrating the inspection interruption process executed by the inspection method according to the fifth embodiment of the present invention. This flow is started as an interrupt for each page of processing during execution of the inspection method according to any of the above embodiments. The inspection unit 25 measures the transmittance of the medium (step S51). After processing step S51, the inspection unit 25 determines whether the measurement result of step S51 is within the interruption criteria (step S52). That is, it determines whether the measurement result is within the value (inspection interruption criteria) entered in the medium transmittance input box 203 (FIG. 13) (S52). If it is within the criteria (Yes in step S52), the inspection unit 25 continues the inspection operation (step S53). On the other hand, if it is outside the criteria (No in step S52), the inspection unit 25 interrupts the inspection operation (step S54) and displays the inspection interruption operation designation screen 210 on the display operation unit 5 (step S55). At this time, the operator specifies the inspection interruption operation using the inspection interruption operation designation screen 210 during the inspection. After processing step S55, the inspection unit 25 executes the interruption process based on the designated value (step S56). After the processing of step S53 or S56, the processing ends.

[0087] FIG. 16 is a diagram showing an example of a designation screen for designating an operation to be performed when the inspection device 100 suspends inspection. The inspection interruption operation specification screen 210 has the text "Inspection has been interrupted due to paper with low transmittance. Please specify the operation.", a "Continue" button 211, a "Continue printing / cancel inspection" button 212, and a "Cancel" button 213.

[0088] When the inspection device 100 suspends inspection, it displays an inspection suspend operation specification screen 210. If the "Continue" button 211 is pressed at that time, printing and inspection continue. If the "Continue printing / Stop inspection" button 212 is pressed, printing continues and inspection is stopped. If the "Stop" button 213 is pressed, printing and inspection are stopped.

[0089] As described above, according to the inspection device 100 of this embodiment, the operation setting screen 200 (Figure 13) can be used to select between subtraction mode (first and third embodiments) and composition mode (second and fourth embodiments), specify the lower limit of media transmittance that enables inspection operation, and specify the method of removal when inspection operation is stopped.

[0090] Furthermore, when inspection is interrupted, the inspection device 100 displays an inspection interruption operation designation screen 210 (FIG. 16) on the display operation unit 5. This allows the operator to use the inspection interruption operation designation screen 210 to select whether to continue printing and inspection, continue printing and interrupt inspection, or interrupt printing and inspection.

[0091] (Sixth embodiment) In each of the above embodiments, the background image was identified for each page of the reference medium and the inspection medium using a scanned image (step S4 (Figure 5), step S14 (Figure 8), step S34 (Figure 10)), but the background image can be identified only for the first page.

[0092] 17 is a flowchart for explaining a method for generating a reference image in the inspection method according to the sixth embodiment of the present invention. The following explanation replaces the operation example of the inspection method by subtraction according to the first embodiment. When the flow starts, the reference image generating unit 11 prints the material image 37 (FIG. 4) as a reference image on a medium (step S61). After the processing of step S61, the reading control unit 22 causes the reading unit 1 to scan the printed reference image (step S62).

[0093] After the process of step S62, the reference image generation unit 11 stores the background image 32a of the first page using the reference scanned image 31a scanned in step S62 (step S63). After the process of step S63, the image subtraction unit 14 subtracts the background image 32a from the reference scanned image 31a to generate a difference image (reference image 33a) (step S64). After the process of step S64, the reference image generation unit 11 determines the print area 41 (FIG. 6) from the difference image (reference image 33a) (step S65). The print area 41 refers to an area that remains unchanged when, for example, the outer edges of the reference image 33a and the reference scanned image 31a are compared. After the process of step S65, the reference image generation unit 11 extracts the print area 41 determined in step S65 from the reference scanned image 31a (FIG. 4) scanned in step S62 (step S66). After processing step S66, the reference image generation unit 11 stores the image extracted in step S66 as a reference image in the storage unit 30 (S67). After processing step S67, the reference image generation unit 11 determines whether the printing, scanning, etc. of the material image 37 is the final page (step S68). If it is not the final page (No in step S68), the process returns to step S61, and the reference image generation unit 11 prints the material image of the next page on the medium. On the other hand, if it is the final page (Yes in step S68), the process ends.

[0094] 18 is a flowchart for explaining a method for generating an inspection image and comparing it with a reference image in an inspection method according to a sixth embodiment of the present invention. The following explanation replaces the operational example of the inspection method using subtraction according to the first embodiment. The control unit 20 rotates the drum 6 while suspending the transport of the medium (paper) until the read background image becomes the same position image as the stored background image (step S71). After processing step S71, the inspection image generation unit 12 prints the inspection image 38 (FIG. 4) on the medium (step S72). After processing step S72, the reading control unit 22 causes the reading unit 1 to scan the printed inspection image (step S73).

[0095] After processing step S73, the image subtraction unit 14 subtracts the background image 32b from the inspection read image 34a to generate a difference image (inspection image 35a) (step S74). After processing step S74, the inspection image generation unit 12 determines the print area 41 (FIG. 6) from the difference image (inspection image 35a) (step S75). The print area 41 refers to an area that remains unchanged when the outer edges of the inspection image 35a and the inspection read image 34a are compared, for example. After processing step S75, the inspection image generation unit 12 extracts the print area 41 determined in step S75 from the inspection read image 34a (FIG. 4) scanned in step S73, and generates a comparison image for inspection (step S76).

[0096] After processing step S76, the comparison and judgment unit 13 (FIG. 1) compares the image extracted in step S76 with the reference image stored in the memory unit 30 (step S77) and inspects it. After processing step S77, the comparison and judgment unit 13 determines whether the inspection result is OK (step S78). If the inspection result is OK (Yes in step S78), the drive control unit 23 controls the sheet to be sent to a sorter for OK sheets (step S79). On the other hand, if the inspection result is NG (No in step S78), the drive control unit 23 controls the sheet to be sent to a sorter for NG sheets (step S80). After processing step S79 or S80, the control unit 20 determines whether the printing, scanning, etc. of the inspection image 38 is the final page (step S81). If it is not the final page (No in step S81), the process returns to step S71, and the control unit 20 controls the sheet to be printed on the medium with the next page of the inspection image. On the other hand, if it is the last page (Yes in step S81), the processing in FIG. 18 ends.

[0097] As described above, the inspection device of this embodiment stores the background image 32a of the first page using the reference scanned image 31a (FIG. 4) (step S63). Furthermore, the transport of the medium (paper) is suspended until the scanned background image is at the same position as the stored background image (step S71). This eliminates the need to search for a matching background image from the multiple (three) stored background images when generating the difference image (inspection image 35a) (FIG. 4) (step S74).

[0098] (Variation) The present invention is not limited to the above-described embodiments, and modifications can be made without departing from the spirit of the present invention, for example, the following (a) to (f). (a) The background images 32a, 32b (Fig. 4) and 32c (Fig. 9) in the first and second embodiments were images of the adsorption surface when the reading unit 1 viewed the paper adsorption sections 6a, 6b and 6c through a transparent medium, but they may also be images of the adsorption surface when the reading unit 1 viewed the paper adsorption sections 6a, 6b and 6c without a medium. (b) In the above embodiments, the medium measurement unit 2 measures the transmittance of the medium, but it may also measure the color. In this case, color correction is performed instead of density correction.

[0099] (c) In the first and second embodiments, a transparent medium was used, while in the third and fourth embodiments, a semi-transparent medium was used. The first and second embodiments are common to the third and fourth embodiments if a translucent medium, including a transparent medium and a semi-transparent medium, is used. However, in the first and second embodiments, the background images 32a, 32b (FIG. 4), and 32c (FIG. 9) must be obtained using a transparent medium, rather than using a medium-free state (variation example (a)).

[0100] (d) In the sixth embodiment, the drive unit 4 (FIG. 1) rotates the drum 6 while suspending the transport of the medium (step S71), but the medium may be transported (medium transport) while stopping the rotation of the drum 6. In other words, the drive unit 4 may feed the medium empty (empty feed).

[0101] (e) In the above-described embodiments, a scanned image (such as the reference scanned image 31a and the inspection scanned image 34a) is compared with multiple background images (images of the suction surfaces 6d of the paper suction units 6a, 6b, and 6c) stored in the memory unit 30 to identify one background image (step S4 (FIG. 5), step S14 (FIG. 8), and step S34 (FIG. 10)). This allows the inspection unit 25 to identify which divided surface (the suction surface of the paper suction units 6a, 6b, and 6c) the medium is attached to. The divided surface may be identified using rotation angle information of the rotating body (drum 6) detected by a sensor (e.g., a rotary encoder) included in the drive unit 4 (FIG. 1) or by using symbols attached to the divided surfaces of the cylindrical surface.

[0102] (f) In the above embodiments, the drum 6 is used as a rotating body, but the attraction surface 6d may be a flat surface. [Explanation of symbols]

[0103] 1 Reading unit 2 Media measurement unit (media sensor) 3 Printing section 9 Display operation section (input section) 6 Drum (rotating body) 6a, 6b, 6c Paper suction unit 6d Adsorption surface (holding surface) 7a Adsorption hole 7b SUS sheet 7c PFA sheet 7d Claw (coded claw) 8a Paper feed roller 8b Paper ejection roller 10 Image forming unit 11 Reference image generation unit 12 Inspection image generation unit 13 Comparison / judgment section 14 Image subtraction unit 15 Image synthesis unit 16 RIP section 20 Control Unit 21 Background image generation unit 22 Reading control unit 23 Drive control unit 24 Display operation control section 25 Inspection Department 30 Storage section 31, 31a, 31b Reference scanned image 32,32a,32b,32c,32d,32e,32f Background image (holding surface image) 33,33a,33b,33c,33d Standard image (comparison image) 33e Reading display image 35e inspection display image 34, 34a, 34b Inspection image 35, 35a, 35b, 35c, 35d Inspection images 36a, 36b RIP images 37,37a Stock Image 38,38a Inspection image 39 Bad print image 40 Transparent media 41 Print area 42 Outside print area 43 Image forming media 44 Mark (Uninspected mark) 100 Inspection equipment 200 Operation setting screen 203 Media transmittance input box 210 Inspection interruption operation specification screen

Claims

1. a holding unit that holds an inspection medium on which an image is formed; a reading unit that reads an image of the inspection medium; an inspection unit that inspects the inspection medium by comparing an inspection image obtained by image processing the image read by the reading unit with a reference image; The holding surface of the holding portion is a non-plain surface, The inspection unit changes one or both of the inspection image and the reference image based on the light transmittance of the medium. Inspection equipment.

2. the medium is a transparent medium; a background image generating unit that generates a background image by capturing an image of the holding surface without a medium or a background image by capturing an image of the transparent medium held by the holding unit; the reference image is a difference image between the background image and an image-formed transparent medium on which the image is formed and which is held by the holding unit; The inspection image is a difference image between the image of the inspection medium read by the reading unit and the background image. The inspection device according to claim 1 .

3. the medium is a transparent medium; a background image generating unit that generates a background image by capturing an image of the holding surface without a medium or a background image by capturing an image of the transparent medium held by the holding unit; the reference image is a composite image obtained by combining an image formed on the medium with the background image, The inspection image is an image obtained by reading the inspection medium by the reading unit. The inspection device according to claim 1 .

4. the medium is a light-transmitting medium, a background image generating unit that generates a background image by capturing an image of the light-transmitting medium held by the holding unit; the reference image is a difference image between an image-forming medium on which the image is formed on a light-transmitting medium held in the holding unit and the background image, The inspection image is a difference image between the image of the inspection medium read by the reading unit and the background image. The inspection device according to claim 1 .

5. the medium is a light-transmitting medium, a background image generating unit that generates a background image by capturing an image of the light-transmitting medium held by the holding unit; the reference image is a composite image obtained by combining an image formed on the medium with the background image, The inspection image is an image obtained by reading the inspection medium by the reading unit. The inspection device according to claim 1 .

6. The reference image is limited to the printing area. The inspection device according to any one of claims 2 to 5.

7. the optical transparency of the medium is the transmittance of the medium; The inspection unit performs an inspection operation when the transmittance of the medium is higher than a reference value. The inspection device according to any one of claims 2 to 5.

8. The density of the background image is changed according to the transmittance of the medium. The inspection device according to claim 7.

9. The device further includes an input unit that allows the transmittance to be specified. The inspection device according to claim 7.

10. The device further includes a medium measuring unit for measuring the transmittance of the medium. The inspection device according to claim 7.

11. Adjust the color of the background image according to the color of the medium The inspection device according to any one of claims 2 to 5.

12. a medium measurement unit for measuring the color of the medium; The inspection device according to claim 11.

13. the holding portion is a rotating body, the holding surface is a cylindrical surface divided into a plurality of parts in the rotational direction, A plurality of background images are stored for each divided surface, The inspection unit compares the images while recognizing the images of the individual division surfaces. The inspection device according to any one of claims 2 to 5.

14. The inspection medium is a medium on which different images are formed, The reference image is stored in a storage unit across multiple pages from the first page so as to correspond to the inspection medium, The inspection unit feeds the rotating body idle until the surface of the medium that is attracted to the rotating body coincides with the surface of the first page of the reference image, and performs image formation and inspection from the point where they coincide. The inspection device according to claim 13.

15. The inspection medium is a medium on which different images are formed, The reference image is stored in a storage unit across multiple pages from the first page so as to correspond to the inspection medium, The inspection unit conveys the medium until the suction surface of the medium attached to the rotating body coincides with the suction surface of the first page of the reference image, and performs image formation and inspection from the point where they coincide. The inspection device according to claim 13.

16. The inspection unit identifies the division surface to which the medium is attracted by comparing an image of the attraction surface on which the medium is attracted to the rotating body with images of each division surface stored in a storage unit. The inspection device according to claim 13.

17. Further, a drive unit that rotates the rotating body is provided. The inspection unit identifies a division surface to which the medium is attracted using rotation angle information of the rotating body detected by a sensor. The inspection device according to claim 13.

18. a code for identifying each divided surface is assigned to each divided surface of the cylindrical surface; The inspection unit uses the code to identify the division surface to which the medium is attracted. The inspection device according to claim 13.

19. An inspection device that can select either the inspection device according to claim 3 or claim 5 or the inspection device according to claim 2 or claim 4.

20. If it is determined that the inspection operation will not be performed during the inspection, the image formation and inspection will be suspended. The inspection device according to claim 1 .

21. If it is determined that the inspection operation will not be performed during the inspection, the subsequent inspection media will be discharged to a different sorter from the ones for which inspection has been completed. The inspection device according to claim 1 .

22. If it is determined that inspection will not be performed during inspection, a mark indicating that the printout has not been inspected will be added to the edge of the paper. The inspection device according to claim 1 .

23. An inspection method performed by an inspection device including a holding unit that holds an inspection medium having an image formed on the medium and has a holding surface that is not a plain surface, a reading unit that reads the image on the inspection medium, and an inspection unit that inspects the inspection medium by comparing an inspection image obtained by image processing the read image read by the reading unit with a reference image, The inspection unit changes either or both of the inspection image and the reference image based on the light transmittance of the medium. Inspection method.

Images