Inspection device, image forming system, inspection method, and recording medium

Abstract

Provided are an inspection device, an image forming system, an inspection method, and a recording medium, which can appropriately implement inspection even when inspecting a printed matter in which an anti-transmission image is formed on a printed image of a transparent raw material. The inspection device for performing quality inspection of printed matter comprises an image acquisition unit, a first reading unit, and an abnormality detection unit. The image acquisition unit acquires a manuscript image. The first reading unit reads a printed image printed on one side of a transparent raw material based on the manuscript image from the other side opposite to the above-mentioned one side. The abnormality detection unit detects abnormalities in the printed matter based on the manuscript image and the read image read by the first reading unit.

Description

Technical Field

[0001] The present invention relates to an inspection device, an image forming system, an inspection method, and a recording medium. Background Art

[0002] In an inspection device for inspecting the quality of a printed matter having an original image printed thereon (hereinafter also referred to as "inspection"), there is known an automatic inspection technology for automatically inspecting by comparing a scanned image obtained by scanning the printed surface of the printed matter with the original image. According to such an automatic inspection technology, it is possible to save the user's time for visually checking the quality of the printed matter by checking stains, wrinkles, etc. on the printed surface, thereby helping to save manpower, particularly at a production printing site where a large amount of printing is performed.

[0003] In addition, in the field of production printing in recent years, the opportunities for printing on transparent raw materials (such as transparent sheets, etc.) are increasing. In the printing on transparent raw materials, there are "front printing" and "back printing". "Front printing" refers to printing, for example, imagining printing the original image on the surface of the transparent raw material and observing the printed image from the surface (printing surface) of the transparent raw material, just like printing on ordinary paper. In contrast, "back printing" refers to printing, imagining that the original image is mirror-flipped (flipped left and right) and then printed on the back of the transparent raw material and observing the printed image from the surface side of the transparent sheet (the side opposite to the printing surface). Since the printed image printed on the back is observed through the transparent raw material, the printed image is added with a gloss caused by the transparent raw material, and the wear and contamination of the printed surface can be prevented. As a technology related to back printing of transparent raw materials, for example, the technology of the following patent document 1 is known.

[0004] However, in the back printing, when the layer of the printed image is thin, such as when the printed image is monochrome, it is possible that the object (background) on the other side of the transparent raw material can be seen through the printed image. For example, when there is a wall on the other side of the printed matter, the background can be seen through the printed image, and sometimes the appearance of the printed image will change due to the pattern of the wall. In the case where it is not desired to see the background through, there is a method of preventing the see-through by forming an anti-see-through image (such as a white solid image) in an overlapping manner on the printed image. Therefore, when the printed matter is observed from the surface of the transparent raw material, since the anti-see-through image is formed on the printed image, the light from the background is blocked, preventing the background from being seen through.

[0005] Prior art literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-201264 Summary of the invention

[0007] However, when inspecting a printed material having a see-through preventing image formed thereon, the see-through preventing image is scanned and read in a conventional inspection device, so there is a problem that the inspection cannot be performed appropriately.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an inspection device, an image forming system, an inspection method, and an inspection program that can appropriately perform inspection even when inspecting a printed material on which a see-through preventing image is formed.

[0009] The above-mentioned object of the present invention is achieved by the following means.

[0010] (1) An inspection device for performing a quality inspection on a printed matter, the inspection device comprising: an image acquisition unit for acquiring an original image; a first reading unit for reading a printed image formed on one side of a transparent raw material based on the original image from the other side opposite to the one side; and an abnormality detection unit for detecting an abnormality of the printed matter based on the original image and the read image read by the first reading unit.

[0011] (2) In the inspection device described in (1) above, the transparent material is a sheet-shaped or plate-shaped material.

[0012] (3) In the inspection device described in (1) or (2) above, the inspection device further comprises: an anti-seepage determination unit for determining whether an anti-seepage image is formed on the printed image; and a second reading unit for reading the printed image from the printed surface side of the printed matter. When the anti-seepage determination unit determines that an anti-seepage image is formed on the printed image, the abnormality detection unit detects an abnormality of the printed matter based on the original image and the read image read by the first reading unit. On the other hand, when the anti-seepage determination unit determines that no anti-seepage image is formed on the printed image, the abnormality detection unit detects an abnormality of the printed matter based on the original image and the read image read by the second reading unit.

[0013] (4) In the inspection device described in any one of (1) to (3) above, the abnormality detection unit compares the pixel values ​​of corresponding pixel positions of a flipped image obtained by mirror-flipping either the original image or the read image with the image of the other, or compares the pixel values ​​of mirror-symmetrical pixel positions of the original image and the read image, thereby determining whether the printed matter is abnormal.

[0014] (5) In the inspection device described in any one of (1) to (3) above, the abnormality detection unit determines that the printed matter is normal when the comparison result between the original image and the read image satisfies a predetermined inspection criterion, and on the other hand, determines that the printed matter is abnormal when the comparison result does not satisfy the predetermined inspection criterion.

[0015] (6) In the inspection device described in (5) above, the inspection device further comprises: a raw material information acquisition unit for acquiring information related to the transparent raw material; and an inspection reference adjustment unit for adjusting the predetermined inspection reference based on the information acquired by the raw material information acquisition unit, wherein the raw material information acquisition unit acquires information related to the basic weight or thickness of the transparent raw material, and the inspection reference adjustment unit adjusts the predetermined inspection reference based on the basic weight or thickness.

[0016] (7) In the inspection device described in (6) above, the predetermined inspection standard is a standard for the inspection items of the quality inspection of the printed matter, and the inspection standard adjustment unit accepts the input of the inspection item and the allowable level of the inspection item when the basic weight or thickness of the transparent raw material exceeds the predetermined threshold value corresponding to each, and the abnormality detection unit calculates the detection level of the inspection item based on the original image and the read image, and judges that the printed matter is normal when the detection level satisfies the allowable level accepted by the inspection standard adjustment unit, and on the other hand, judges that the printed matter is abnormal when the detection level does not satisfy the allowable level.

[0017] (8) In the inspection device described in any one of (1) to (4) above, the inspection device further comprises: a raw material information acquisition unit for acquiring information related to the transparent raw material; and a pixel value correction unit for correcting the pixel value of the original image based on the information acquired by the raw material information acquisition unit, wherein the raw material information acquisition unit acquires information related to the color of the transparent raw material, and the pixel value correction unit corrects the pixel value of the read image based on the color of the transparent raw material.

[0018] (9) An image forming system comprising: an image forming device for forming an image on one side of a transparent raw material based on an original image and outputting it as a printed matter; an inspection device described in any one of (1) to (8) above for inspecting the quality of the printed matter; and a paper conveying device for conveying the printed matter output by the image forming device to the inspection device.

[0019] (10) An inspection method is an inspection method for an inspection device that performs quality inspection on printed materials, comprising: step (a) of acquiring an original image; step (b) of determining whether an anti-seepage image is formed on a printed image formed on one side of a transparent raw material based on the original image; and step (c) of, when it is determined that an anti-seepage image is formed on the printed image, reading the printed image from the other side opposite to the one side, and detecting an abnormality of the printed material based on the original image and the read image read from the other side; on the other hand, when it is determined that no anti-seepage image is formed on the printed image, reading the printed image from the printed surface side of the printed material, and detecting an abnormality of the printed material based on the original image and the read image read from the printed surface side of the printed material.

[0020] (11) In the inspection method described in (10) above, the transparent raw material is a sheet-like or plate-like raw material.

[0021] (12) In the inspection method described in (10) or (11) above, in step (c), the pixel values ​​of corresponding pixel positions of a flipped image obtained by mirror-flipping either the original image or the read image and the image of the other are compared, or the pixel values ​​of mirror-symmetrical pixel positions of the original image and the read image are compared, thereby determining whether the printed matter is abnormal.

[0022] (13) In the inspection method described in (10) or (11) above, in the step (c), if the comparison result between the original image and the read image satisfies a predetermined inspection criterion, the printed matter is judged to be normal; on the other hand, if the comparison result does not satisfy the predetermined inspection criterion, the printed matter is judged to be abnormal.

[0023] (14) An inspection program for causing a computer to execute the processing included in the inspection method described in any one of (10) to (13) above.

[0024] According to the present invention, the printed matter is inspected by comparing the read image read from the other side of the printed matter opposite to the printed surface with the original image, so that the inspection can be properly carried out even when inspecting the quality of the printed matter formed with an anti-transmission image. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic cross-sectional view of an image forming system according to one embodiment.

[0026] Figure 2 yes Figure 1 A schematic block diagram of an image forming system is shown.

[0027] Figure 3 It is shown Figure 2 FIG. 1 is a schematic block diagram showing a configuration of a control unit of an image forming apparatus shown in FIG.

[0028] Figure 4 It is shown Figure 2 A schematic block diagram of the structure of the control unit of the inspection device shown.

[0029] Figure 5 It is a schematic diagram illustrating a printing operation of the image forming system.

[0030] Figure 6 This is a flowchart illustrating a processing procedure of an inspection method in an inspection device.

[0031] Figure 7 It is a schematic diagram for explaining the inspection method in the case where the anti-see-through image is not formed.

[0032] Figure 8 is exemplified in Figure 6 The flowchart is a subroutine flowchart of the processing process of inspecting the printed matter printed inside.

[0033] Fig. 9 This is a schematic diagram for explaining correction of the pixel value of the document image according to the hue of the transparent sheet.

[0034] Fig.10 This is a schematic diagram illustrating a setting screen related to quality inspection of printed materials.

[0035] (Explanation of symbols)

[0036] 100: image forming system; 200: paper supply device; 210: paper supply unit; 220: paper conveying unit; 230: communication unit; 240: control unit; 300: image forming device; 310: image processing unit; 320: image forming unit; 330: paper supply unit; 340: paper conveying unit; 350: fixing unit; 360: communication unit; 370: operation display unit; 380: control unit; 400: paper conveying device; 410: paper conveying unit; 411: paper turning unit; 420: communication unit; 430: control unit; 500: inspection device; 600: post-processing device; 700: client terminal. DETAILED DESCRIPTION

[0037] Hereinafter, the embodiments of the present invention will be described with reference to the attached drawings. In addition, the same reference numerals are added to the same elements in the description of the drawings, and repeated descriptions are omitted. In addition, the dimensional ratios of the drawings are sometimes exaggerated for the purpose of description and are different from the actual ratios.

[0038] <Image Forming System 100>

[0039] Figure 1 is a schematic cross-sectional view of an image forming system 100 according to an embodiment, Figure 2 yes Figure 1 FIG. 1 is a schematic block diagram of an image forming system 100. Figure 3 It is shown Figure 2 FIG. 1 is a schematic block diagram showing a structure of a control unit 380 of the image forming apparatus 300 shown in FIG. Figure 4 It is shown Figure 2 1 is a schematic block diagram of the structure of the control unit 540 of the inspection device 500 shown.

[0040] like Figure 1 As shown, the image forming system 100 of this embodiment includes a paper feeding device 200, an image forming device 300, a paper conveying device 400, an inspection device 500, a post-processing device 600, and a client terminal 700 connected in series along the X direction (paper conveying direction). Figure 1 The structure of the image forming system 100 shown in the figure is an example, and the types and number of devices included in the image forming system 100 are not limited to Figure 1 Example shown.

[0041] <Paper Feeding Device 200>

[0042] The paper feeding device 200 supplies recording materials to the image forming device 300 according to an instruction from the image forming device 300. Figure 1 , Figure 2 As shown, the paper feeding device 200 includes a paper feeding unit 210, a paper conveying unit 220, a communication unit 230, and a control unit 240. The paper feeding unit 210, the paper conveying unit 220, the communication unit 230, and the control unit 240 are connected to each other via an internal bus 201 so as to be able to communicate with each other.

[0043] The paper feed section 210 has at least one paper feed tray for accommodating transparent raw materials (e.g., transparent sheets) as recording materials used in printing. "Transparent" includes completely transparent and semi-transparent (colored transparency, etc.). The transparent sheet (hereinafter also referred to as "sheet") can be, for example, a transparent resin sheet (film). In addition, in the present embodiment, the sheet is assumed to have no pattern, etc., that is, to be solid color. The sheets accommodated in the paper feed tray are supplied to the image forming device 300 one by one along the conveying path of the paper conveying section 220 through a plurality of conveying roller pairs.

[0044] The communication unit 230 exchanges control signals and data with the image forming apparatus 300 . The control unit 240 controls the paper feeding unit 210 , the paper conveying unit 220 , and the communication unit 230 .

[0045] <Image Forming Apparatus 300>

[0046] The image forming apparatus 300 receives a print job including print data in the form of PDL (Page Description Language) and print setting data from an external client terminal 700 via a network, and prints an image on a sheet based on the print data. The client terminal 700 may be, for example, a personal computer, a tablet terminal, a smart phone, etc. The print setting data includes information related to the number of pages, the number of copies, the type of recording material (transparent sheet, paper, etc.), size, basis weight, setting of a check function, setting of front printing / back printing, setting of an anti-transmission image, etc.

[0047] Image forming apparatus 300 includes image processing unit 310 , image forming unit 320 , paper feeding unit 330 , paper conveying unit 340 , fixing unit 350 , communication unit 360 , operation display unit 370 , and control unit 380 . These components are connected to each other via internal bus 301 so as to be able to communicate with each other.

[0048] The image processing unit 310 generates print image data based on the print setting information and print data included in the print job received by the communication unit 360 . The generated print image data is sent to the image forming unit 320 .

[0049] The image forming unit 320 forms an image on a sheet according to the print image data using a known imaging process such as an electrophotographic method including each process of charging, exposure, development, and transfer. The image forming unit 320 is configured to include a photosensitive drum as an image carrier, and a charging unit, an optical writing unit, a developing device, and a transfer unit arranged around the photosensitive drum for each color of yellow (Y), magenta (M), cyan (C), black (K), and white (W).

[0050] Yellow (Y), magenta (M), cyan (C), black (K), and white (W) toner images are formed on each photosensitive drum. The toner images are sequentially transferred to the intermediate transfer belt 321 of the transfer section in an overlapping manner. The toner images transferred to the intermediate transfer belt 321 are transferred to the sheet in a secondary manner.

[0051] In this embodiment, the yellow (Y), magenta (M), and cyan (C) toners are preferably toners with excellent melting properties and sharp melting properties that melt at low temperatures and in a short time. Since the toners with sharp melting properties are easy to mix colors and the color reproduction range of the image obtained by copying is wide, a faithful color image can be obtained in the original.

[0052] For example, such a fast-melting toner can be produced by adding a coloring material or the like to a binder resin such as a polyester resin or a styrene-acrylic resin and then using a known pulverization method or polymerization method.

[0053] On the other hand, regarding white toner, the storage elastic modulus of the binder resin is set to a value of 5 to 100 times, preferably 10 to 100 times, the storage elastic modulus of the binder resin of the color toner at the softening temperature of the binder resin of the color toner. In the case where the storage elastic modulus is less than 5 times and close to the binder resin of the color toner, the white toner may melt during fixing and cause color mixing with the color toner, and the color of the color image to be reproduced may be whitish, causing a decrease in image quality. Moreover, the white image will not become a layer independent of the color image and will not serve as an anti-transmission image. On the other hand, when the storage elastic modulus of the binder resin is 100 times or more of high elasticity, the amount of heat used to fix the white toner to the sheet increases, so it is possible that the color toner may be too melted. As a result, the so-called high temperature offset may occur. In order to avoid this phenomenon, it is necessary to set it to 100 times or less.

[0054] As the type of the binder resin of the white toner, in the example that satisfies the above-mentioned storage elastic modulus condition, it is appropriate to select from the known binder resins for toners such as polyester fiber resins and styrene-acrylic resins. In addition, as the pigment of the white toner, one or more materials such as titanium oxide, zinc oxide, barium sulfate, aluminum oxide, calcium carbonate, etc. can be used. In addition, a charging additive such as a charge control agent can also be added as needed.

[0055] The paper feeding unit 330 feeds sheets to the image forming unit 320. The paper feeding unit 330 includes a plurality of paper feeding trays, and each of the paper feeding trays can accommodate sheets of different sizes, such as A4 size and A3 size.

[0056] The paper conveying unit 340 has a conveying path and a plurality of conveying roller pairs, and conveys paper in the image forming apparatus 300. The paper conveying unit 340 also includes a paper reversing unit and a circulating conveying unit, and can reverse the front and back of a fixed sheet and discharge it, or form images on both sides of the sheet.

[0057] The fixing unit 350 fixes the toner image formed on the sheet. The fixing unit 350 includes a hollow heating roller with a heater disposed inside and a pressure roller facing the heating roller. The heating roller and the pressure roller are controlled to a predetermined temperature (for example, 100° C. or higher) by the heater, and the sheet is heated and pressurized to fix the toner image.

[0058] The sheet on which the image is fixed is supplied to the paper conveying device 400 via a paper discharge unit (not shown).

[0059] The communication unit 360 is connected to, for example, the client terminal 700 via a network, and transmits and receives data such as print jobs.

[0060] The operation display unit 370 includes an input unit and an output unit. The input unit includes, for example, a keyboard, buttons, and a touch panel, and is used by the user to input text using the keyboard, various settings, and various instructions (inputs) such as instructions to start printing using a print start button. In addition, the output unit includes a display, and is used to prompt the user with the implementation status of the printing job, etc.

[0061] The control unit 380 controls the image processing unit 310, the image forming unit 320, the paper feeding unit 330, the paper conveying unit 340, the fixing unit 350, the communication unit 360, and the operation display unit 370. Figure 3 As shown, the control unit 380 includes a CPU 381 , an auxiliary storage device 382 , a RAM 383 , and a ROM 384 .

[0062] The CPU 381 executes a control program for the image forming apparatus to realize various functions. The control program is stored in the auxiliary storage device 382 and loaded into the RAM 383 when executed by the CPU 381. The auxiliary storage device 382 includes a large-capacity storage device such as a hard disk drive, an SSD (Solid State Drive), a flash memory, etc. The calculation results accompanying the execution of the CPU 381 are stored in the RAM 383. Various parameters, various programs, etc. are stored in the ROM 384.

[0063] <Paper Conveying Device 400>

[0064] The paper conveying device 400 conveys the sheet supplied from the image forming device 300 to the inspection device 500 as it is or after the front and back sides are turned over, according to the instruction of the control unit 380. The paper conveying device 400 includes a paper conveying unit 410, a communication unit 420, and a control unit 430. These components are connected to each other through an internal bus 401 so as to be able to communicate with each other. The paper conveying unit 410 includes a conveying path and a plurality of conveying roller pairs for conveying sheets. In addition, the paper conveying unit 410 includes a paper turning unit 411 for turning the front and back sides over. The communication unit 420 exchanges control signals and data between the control unit 430 and the image forming device 300. The control unit 430 controls the paper conveying unit 410 and the communication unit 420.

[0065] <Inspection Device 500>

[0066] The inspection device 500 inspects the quality of the printed image printed on the sheet conveyed from the paper conveying device 400 according to the instruction of the control unit 380. The inspection device 500 includes a paper conveying unit 510, an image reading unit 520, a communication unit 530, and a control unit 540. These components are connected via an internal bus 501 so as to be able to communicate with each other.

[0067] The paper conveying unit 510 includes a conveying path and a plurality of conveying roller pairs, and conveys the sheet supplied from the image forming apparatus 300 toward the post-processing apparatus 600 along the conveying path.

[0068] The image reading unit 520 includes built-in sensors (hereinafter referred to as "scanners") 521 and 522 provided on the lower and upper sides of the conveying path of the paper conveying unit 510. The lower scanner 521 and the upper scanner 522 function as a first reading unit and a second reading unit, respectively, and are configured to be able to operate independently according to the instruction of the control unit 540.

[0069] The lower scanner 521 reads the lower surface of the printed matter (the sheet on which the printed image is formed by the image forming device 300) conveyed in the conveying path. That is, the lower scanner 521 reads the printed image (formed on the surface) of the printed matter printed on the back side of the sheet through the printed matter. In addition, the upper scanner 522 reads the upper surface of the printed matter conveyed in the conveying path. That is, the upper scanner 522 reads the printed image of the printed matter printed on the back side from the printing surface side (surface side) of the printed matter. The data of the scanner images (read images) read by the scanners 521 and 522 are respectively sent to the control unit 540.

[0070] The communication unit 530 exchanges control signals and data between the control unit 540 and the image forming apparatus 300 .

[0071] The control unit 540 controls the paper conveying unit 510, the image reading unit 520, and the communication unit 530. Figure 4 As shown, the control unit 540 includes a CPU 541 , an auxiliary storage device 542 , a RAM 543 , and a ROM 544 .

[0072] The CPU 541 executes the inspection program to realize various functions. The inspection program is stored in the auxiliary storage device 542 and loaded into the RAM 543 when executed by the CPU 541. The auxiliary storage device 542 includes a large-capacity storage device such as a hard disk drive, an SSD (Solid State Drive), a flash memory, etc. The calculation results accompanying the execution of the CPU 541 are stored in the RAM 543. Various parameters, various programs, etc. are stored in the ROM 544.

[0073] In the present embodiment, the control unit 540 functions as an image acquisition unit that acquires the manuscript image from the control unit 380. In addition, the control unit 540 functions as an abnormality detection unit that detects abnormalities in printed matter based on the manuscript image and the scanned image (read image) scanned by the lower scanner 521 or the upper scanner 522. Printed matter abnormality refers to the state in which the printed matter has stains, wrinkles, stripes, white spots, etc. More specifically, the abnormality detection unit compares the pixel values ​​of corresponding pixel positions with respect to the flipped image obtained by mirror-flipping the manuscript image (flipping left and right relative to the central axis) and the scanned image, thereby determining whether the printed matter is abnormal.

[0074] In addition, the abnormality detection unit can also be configured to determine whether the printed matter is abnormal based on whether the comparison result of the original image and the scanned image satisfies a predetermined inspection standard. The abnormality detection unit determines that the printed matter is normal when the comparison result satisfies the predetermined inspection standard, and determines that the printed matter is abnormal when the comparison result does not satisfy the predetermined inspection standard. The predetermined inspection standard is a judgment standard when determining whether the printed matter is abnormal based on the comparison result of the original image and the scanned image. The specific method of detecting abnormality of the printed matter will be described later.

[0075] In addition, the control unit 540 functions as a raw material information acquisition unit that acquires information related to the transparent raw material. The raw material information acquisition unit acquires, for example, the size, basic weight, and color information of the sheet from the printing setting information. In addition, the control unit 540 functions as an inspection reference adjustment unit that adjusts a predetermined inspection reference based on the information acquired by the raw material information acquisition unit. The inspection reference adjustment unit acquires information related to the basic weight or thickness of the sheet, and adjusts the predetermined inspection reference based on the basic weight or thickness. A specific example of the adjustment of the predetermined inspection reference will be described later. Furthermore, the control unit 540 functions as a pixel value correction unit that corrects the pixel value of the original image based on the color information acquired by the raw material information acquisition unit. The change of the pixel value of the original image will also be described later.

[0076] <Post-processing device 600>

[0077] The post-processing device 600 conveys or post-processes the paper supplied from the inspection device 500 according to the instruction of the control unit 380, and discharges it to the outside of the image forming system 100. The post-processing device 600 includes a paper conveying unit 610, a post-processing unit 620, a paper discharge unit 630, a communication unit 640, and a control unit 650. These components are connected to each other via the internal bus 501 so as to be able to communicate with each other.

[0078] The paper conveying unit 610 includes a conveying path and a plurality of conveying roller pairs, and conveys the printed material supplied from the inspection device 500 along the conveying path, and supplies the printed material to the post-processing unit 620 or the paper discharge unit 630 .

[0079] The post-processing unit 620 performs post-processing on the conveyed printed material. Examples of the post-processing include punching processing and cutting processing.

[0080] The paper discharge unit 630 includes a paper discharge tray and a pair of paper discharge rollers, and discharges the sheet supplied from the inspection device 500 and conveyed in the conveyance path or the post-processed sheet to the paper discharge tray.

[0081] The communication unit 640 exchanges control signals and data between the control unit 650 and the image forming apparatus 300 . The control unit 650 controls the paper conveying unit 610 , the post-processing unit 620 , the paper discharge unit 630 , and the communication unit 640 .

[0082] <Printing Operation of Image Forming System 100>

[0083] Figure 5This is a schematic diagram illustrating the printing operation of the image forming system 100. In this embodiment, a case is described in which a user prints a manuscript edited using document creation software or drawing software using the image forming device 300 in the client terminal 700, and inspects (checks) the quality of the printed material using the inspection device 500.

[0084] The printer driver of client terminal 700 generates a print job of the document edited by the user and sends it to image forming system 100. Image forming system 100 receives the print job via communication unit 360 and transfers it to image processing unit 310. The print job includes, for example, a document image of "apple" as print data.

[0085] In addition, Figure 5 In the example shown, an image of an "apple" printed on the back side (back side) is displayed on the display of the client terminal 700. It is assumed that in back printing, the original image of "apple" is printed on the back side of a sheet, and the printed matter is observed from the side opposite to the printed side (front side). Therefore, the printed image observed from the front side is an image obtained by mirror-reversing the printed image observed from the back side.

[0086] In addition, as an example, the print setting information of the print job includes the information shown in Table 1 below. In addition, the print setting information also includes other information such as the number of pages and the number of copies, but the description is omitted here. The color information includes the YMCK value or the RGB value of the color. In addition, in the case where the recording material is not a transparent raw material, the designation of the front printing / back printing can be handled as the front printing. In addition, it can also be configured so that the printing setting information includes an item of the thickness of the recording material in addition to the basic weight of the recording material.

[0087] [Table 1]

[0088]

[0089] The control unit 380 controls each unit of the image forming system 100 according to the print setting information of the print job. For example, when the control unit 380 obtains the print setting information shown in Table 1, it controls the paper feeding device 200, the image processing unit 310, the image forming unit 320, the paper conveying unit 340, the fixing unit 350, etc., so that a white image is used to prevent penetration and perform back printing on a transparent sheet of A4 size. In addition, the control unit 380 outputs instructions to the control unit 430 of the paper conveying device 400 and the control unit 540 of the inspection device 500 so that the printed matter output from the image forming device 300 is inspected. More specifically, it is as follows.

[0090] The paper feeding device 200 feeds sheets one by one to the image forming device 300 according to the instruction of the control unit 380. The image processing unit 310 of the image forming device 300 performs rasterization processing on the print data to generate print image data, and the image forming unit 320 forms a toner image on each photosensitive drum according to the print image data, and sequentially transfers the white image (W) and the color image (YMCK) to the intermediate transfer belt 221 once.

[0091] The color image corresponds to the original image, and the white image corresponds to the anti-see-through image. A color image can be formed by overlapping a single-color layer or a plurality of single-color layers. The color image and the white image transferred to the intermediate transfer belt 221 are transferred to the sheet supplied from the paper feed device 200 for the second time, and the toner images of the color image and the white image are fixed in the fixing unit 350.

[0092] On the printed matter discharged from the image forming device 300, a layer of a color image and a layer of a penetration-proof image are sequentially formed. Therefore, in the back printing on the sheet, when the penetration-proof image is formed on the original image, when the printed matter is placed on a table with a pattern and observed from the sheet side (the side opposite to the printed surface), the reflected light from the table is blocked by the penetration-proof image. Thus, it is possible to prevent or suppress the pattern of the table behind the printed matter from affecting the appearance of the printed image.

[0093] In addition, in the above example, the anti-transmission image is set to a white image, but the anti-transmission image is not limited to the white image, and can be, for example, black, gold, silver, etc. White, gold, silver, etc. are generally called special colors (or characteristic colors).

[0094] The printed matter discharged from the image forming apparatus 300 is supplied to the paper conveying device 400 . In the paper conveying device 400 , the printed matter is conveyed while the front and back sides are oriented, and supplied to the inspection device 500 .

[0095] <Inspection method>

[0096] Below, refer to Figures 5 to 10 , describing the processing procedure of the printed matter inspection method in the inspection device 500 of this embodiment. Figure 6 : is a flowchart illustrating the processing procedure of the inspection method in the inspection device 500 of this embodiment. Figure 7 Schematic diagram for explaining the inspection method when no anti-transmission image is formed. Figure 8 is exemplified in Figure 6 The subroutine flowchart of the process of checking the printed matter printed in the flowchart is shown in FIG. In addition, the CPU 541 of the control unit 540 executes the inspection program to realize Figure 6 Flowchart and Figure 8 In addition, Fig. 9 FIG. 1 is a schematic diagram for explaining how to correct the pixel value of an original image according to the color of a transparent sheet. Fig.10 This is a schematic diagram illustrating a setting screen related to quality inspection of printed materials.

[0097] like Figure 6 As shown in FIG. 1 , the document image and print setting information are first obtained (step S101). The control unit 540 obtains the corresponding print image data (document image) and print setting information from the control unit 380 for the printed matter printed by the image forming apparatus 300, and stores them in the RAM 543. Figure 5 In the example shown, although not shown in the figure for simplicity of explanation, the document image and the printing setting information are transmitted from the control unit 380 to the control unit 540 via the communication unit 530. The printing setting information obtained by the control unit 540 includes, for example, the type, size, basic weight, color information of the recording material, the setting of the inspection function, the setting of the front printing / back printing, the setting of the anti-see-through image, and the like.

[0098] Next, it is determined whether the verification function is turned on (step S102). If the verification function is set to off (step S102: No), the control unit 540 ends the process without performing the quality inspection of the printed material (termination).

[0099] On the other hand, when the inspection function is set to on (step S102: "Yes"), it is determined whether it is the back printing of the transparent recording material (step S103). When the type of recording material is a transparent material (such as a transparent sheet) and is set to be back printing (step S103: "Yes"), the control unit 540 further determines whether an anti-transmission image is set (step S104). The control unit 540 functions as an anti-transmission determination unit, and determines whether an anti-transmission image is set, thereby determining whether an anti-transmission image is formed on the printed image of the printed matter. When the anti-transmission image is set (step S104: "Yes"), the control unit 540 performs an inspection on the printed matter with back printing (step S105). More specifically, the control unit 540 performs a quality inspection on the surface on the sheet side of the printed matter, that is, the surface on the opposite side of the printed surface (hereinafter referred to as the "opposite side"). This is because, if Figure 5 As shown in the figure, when the topmost layer of the printed matter has an anti-transmission image, it is not possible to perform an appropriate inspection by using a scanner to read the printed surface of the printed matter and compare the scanned image with the original image as in the conventional inspection. That is, the printed image is covered by the anti-transmission image, so it is not possible to detect stains on the printed image. The details of the inspection for the back-printed printed matter will be described later.

[0100] On the other hand, if the type of recording material is not a transparent material (e.g., ordinary paper), or is set to surface printing (step S103: No), or the anti-transmission setting is set to OFF (step S104: No), a normal printed material inspection is performed (step S106). Figure 7 As shown, the control unit 540 reads the printed image from the printed surface side of the printed matter through the upper scanner 522, and compares the scanned image with the original image. Figure 7 In the example shown, a printed material in which a monochrome “apple” is printed on a transparent sheet is output from the image forming apparatus 300 , and the scanned image of the upper scanner 522 is compared with the original image.

[0101] When the printed image of the printed matter is monochrome, the scanned image and the original image are compared based on whether the pixel values ​​of the pixels corresponding to the pixel positions are consistent. When the pixel values ​​of the scanned image and the original image are consistent with respect to all pixels, the control unit 540 determines that the printed matter is normal. On the other hand, when the pixel values ​​are inconsistent, it is determined that the printed matter is abnormal. In addition, considering the reading characteristics of the upper scanner 522, the reading error, etc., the allowable range can be set to the degree of consistency of the pixel values. After implementing the inspection process of the printed matter in step S106, the control unit 540 ends the process of quality inspection of the printed matter (termination).

[0102] <Processing of Inspection of Printed Material (Step S105)>

[0103] like Figure 8 As shown, first determine whether the sheet is colored (step S201). In the case where the sheet is colored (S201: "Yes"), correct the color tone of the original image (step S202). In the present embodiment, it is assumed that the sheet is solid color, but it is also possible to use a sheet with the same color added to the entire surface instead of being colorless and transparent. The control unit 540 changes the pixel value of the original image according to the color information of the sheet, thereby correcting the color tone of the original image. For example, in the case where the sheet is colored in cyan, the pixel value corresponding to the cyan color of the original image is changed according to the lightness or darkness of the color of the sheet. For example, as Fig. 9 As shown in (A), when the color of the sheet is light, the correction of the pixel value of the original image is reduced. Fig. 9 As shown in (B), when the color of the sheet is dark, the pixel value correction of the original image is increased. Thus, even if the sheet is colored, inspection can be performed with good accuracy.

[0104] On the other hand, if the sheet is not colored (S201: No), the color tone of the original image is not corrected, and the process moves to step S203. In addition, it is also possible to configure the sheet without an image printed thereon to be read in advance by the upper scanner 522 or the lower scanner 521, and to correct the color tone of the original image based on the result of measuring the color state of the sheet.

[0105] Next, the document image is mirror-reversed (step S203 ). The control unit 540 generates an image (hereinafter referred to as a “reversed image”) in which the document image is mirror-reversed by exchanging pixels at left-right symmetrical positions with respect to the central axis of the document image.

[0106] Next, the printed image is read (step S204 ). The control unit 540 reads the printed image from the sheet side of the printed matter, that is, the side opposite to the printed surface, by the lower scanner 521 . The scanned image is sent to the control unit 540 .

[0107] Next, it is determined whether the thickness of the sheet is thicker than a predetermined threshold value (step S205). The control unit 540, for example, estimates the thickness of the sheet based on the basic weight and size of the sheet, and determines whether the thickness of the sheet is thicker than a predetermined threshold value. The predetermined threshold value is not particularly limited, and may be, for example, about 0.1 to 1.5 mm. In addition, when the printing setting information contains information related to the thickness of the sheet, the information may also be used for determination. When the thickness of the sheet is thicker than the predetermined threshold value, the attenuation and reflection of the light caused by the sheet become greater, so there is a possibility that the reading accuracy of the image becomes lower.

[0108] Therefore, in this embodiment, the implementation method of the inspection of the printed matter can be changed according to the thickness of the sheet. When the thickness of the sheet is thicker than a predetermined threshold value (step S205: "Yes"), the inspection of the printed matter is implemented according to a predetermined inspection standard (step S206). On the other hand, when the thickness of the sheet is less than a predetermined threshold value (step S205: "No"), it is determined whether the printed matter is abnormal based on the comparison result between the reversed image and the scanned image of the lower scanner 521. The implementation method of the inspection when the thickness of the sheet is less than a predetermined threshold value will be described later.

[0109] When the thickness of the sheet is thicker than a predetermined threshold value, the predetermined inspection standard is to detect stains, wrinkles, streaks, white spots and other detection items of the printed matter based on the comparison result of the flipped image and the scanned image of the lower scanner 521, and to judge whether the printed matter is abnormal. The control unit 540 calculates the detection level of the detection item based on the comparison result of the flipped image and the scanned image. More specifically, the control unit 540 detects the detection items of "stains", "wrinkles", "streaks" and "white spots" based on the differential image of the flipped image and the scanned image, and divides their degree into 1 to 3 levels.

[0110] On the other hand, the control unit 540 receives the detection items and their allowable levels. Fig.10 As shown, the user makes settings related to the quality inspection of printed materials on the client terminal 700. The detection items are set by checking the "detection items". In addition, the allowable level is set by entering the level in three stages from 1 to 3 in the "allowable level" column corresponding to the detection item. The allowable level is the smallest at level 1, and the allowable level is the largest at level 3. The detection items include, for example, "stains", "wrinkles", "streaks" and "white spots". The set detection items and their allowable levels are sent to the control unit 540.

[0111] The control unit 540 determines that the printed matter is normal when the detection level satisfies the permissible level, and determines that the printed image is abnormal when the detection level does not satisfy the permissible level. Fig. 9 In the example shown, when the detection levels of "stains", "streaks" and "white spots" are "1", "2" and "3" or less, respectively, the detection levels satisfy the permissible levels, so the printed matter is determined to be normal.

[0112] In addition, the stages of the detection level and the allowable level are not limited to three stages, and may be two stages, or four stages or more.

[0113] In this way, even when the thickness of the sheet is thicker than a predetermined threshold value, the quality of the printed matter can be inspected at the permissible level desired by the user with respect to the detection items.

[0114] On the other hand, if the thickness of the sheet is below the predetermined threshold value (step S205: No), the printed material is inspected (step S206). The control unit 540 compares the pixel values ​​of the corresponding pixel positions with respect to the reversed image and the scanned image of the lower scanner 521, thereby determining whether the printed image is abnormal.

[0115] In this way, Figure 6 , Figure 8In the process shown, an original image is obtained, and it is determined whether an anti-seepage image is formed on a printed image printed on one side of a transparent raw material based on the original image. Then, if it is determined that an anti-seepage image is formed on the printed image, the printed image is read from the other side opposite to the above-mentioned one side, and an abnormality of the printed matter is detected based on the original image and the scanned image read from the above-mentioned other side. On the other hand, if it is determined that an anti-seepage image is not formed on the printed image, the printed image is read from the printed surface side of the printed matter, and an abnormality of the printed matter is detected based on the original image and the scanned image read from the printed surface side of the printed matter.

[0116] In addition, in the above example, the case where the reversed image obtained by mirror-flipping the original image and the scanned image are compared is described, but the present invention is not limited to such a case, and the reversed image obtained by mirror-flipping the scanned image and the original image may be compared. Alternatively, the pixel values ​​of the mirror-symmetrical pixel positions of the original image and the scanned image may be compared.

[0117] According to the inspection device 500 of the present embodiment described above, the printed matter is inspected by comparing the scanned image and the original image read from the other side of the printed matter opposite to the printed surface, so that the inspection can be properly carried out even when inspecting the quality of the printed matter on which the anti-transmission image is formed.

[0118] As described above, in the embodiment, the inspection device 500, the image forming system 100, the inspection method, and the inspection program are described. However, it is obvious that those skilled in the art can appropriately add, modify, and omit the present invention within the scope of the technical concept.

[0119] For example, in the above-mentioned embodiment, a sheet-shaped material is exemplified and described as the transparent material, but the transparent material may be a plate-shaped material or the like.

[0120] In addition, in the above-mentioned embodiment, the case where the color image and the white image transferred once are transferred twice to the sheet and fixed simultaneously on the sheet is described, but the present invention is not limited to such a case. For example, it is also possible to configure that the color image is transferred twice to the sheet and fixed first, and then the white image is transferred twice to the sheet and fixed. In this way, it is possible to more reliably prevent the color image and the white image from mixing.

[0121] In the above embodiment, the inspection device 500 includes the control unit 540, and the control unit 540 determines whether the printed matter is abnormal. However, the present invention is not limited to such a case, and the control unit 380 of the image forming device 300 may also be configured to perform the function of determining whether the printed matter is abnormal.

[0122] In the above embodiment, the following case is described: the paper conveying device 400 conveys the printed matter supplied from the image forming device 300 to the inspection device 500 as it is without turning the front and back sides, and the upper scanner 522 reads the printed face side of the printed matter and the lower scanner 521 reads the sheet side of the printed matter in the inspection device 500. However, for example, when it is determined that a see-through preventing image is formed on the printed image, the paper conveying device 400 is configured so that the front and back sides of the sheet are turned over, so that in the inspection device 500, both the printed face side and the sheet side of the printed matter can be read by the upper scanner 522. Thus, the lower scanner 521 can be omitted.

[0123] In addition, the inspection program can be provided through a computer-readable recording medium such as a USB memory, a floppy disk, a CD-ROM, etc., or can be provided online via a network such as the Internet. In this case, the program recorded on the computer-readable recording medium is usually transferred to a memory, a storage device, etc. and stored. In addition, the inspection program can be provided as a separate application software, or can be a software incorporated into each device of the server as a function of the server.

[0124] Furthermore, part or all of the processing executed by the inspection program in the embodiments may be replaced with hardware such as a circuit.

Claims

1. An inspection device for inspecting the quality of printed matter, the inspection device comprising: An image acquisition unit that acquires an original document image; a first reading section for reading the printed matter having a printed image formed on one side of a transparent material based on the manuscript image, from the other side opposite to the one side; an abnormality detection unit that detects an abnormality of the printed matter based on the original image and the read image read by the first reading unit; A raw material information acquisition unit, which acquires information related to the transparent raw material; as well as a pixel value correction unit that corrects the pixel value of the document image based on the information acquired by the material information acquisition unit; The raw material information acquisition unit acquires information related to the color of the transparent raw material. The pixel value correction unit corrects the pixel value of the read image according to the color of the transparent material.

2. The inspection device according to claim 1, wherein: The transparent raw material is a sheet-shaped or plate-shaped raw material.

3. The inspection device according to claim 1 or 2, wherein: The inspection device also has: an anti-seepage determination unit for determining whether an anti-seepage image is formed on the printed image; as well as The second reading unit reads the printed image from the printed surface side of the printed matter, When the anti-seepage determination unit determines that an anti-seepage image is formed on the printed image, the abnormality detection unit detects abnormality of the printed matter based on the original image and the read image read by the first reading unit, and on the other hand, When the see-through prevention determination unit determines that no see-through prevention image is formed on the printed image, the abnormality detection unit detects an abnormality in the printed matter based on the document image and the read image read by the second reading unit.

4. The inspection device according to claim 1 or 2, wherein: The abnormality detection unit compares the pixel values ​​of corresponding pixel positions of a flipped image obtained by mirror-flipping either the original image or the read image with the image of the other, or compares the pixel values ​​of mirror-symmetrical pixel positions of the original image and the read image, thereby determining whether the printed matter is abnormal.

5. An inspection device for inspecting the quality of printed matter, the inspection device comprising: An image acquisition unit that acquires an original document image; a first reading section for reading the printed matter having a printed image formed on one side of a transparent material based on the manuscript image, from the other side opposite to the one side; an abnormality detection unit that detects an abnormality of the printed matter based on the original image and the read image read by the first reading unit; A raw material information acquisition unit, which acquires information related to the transparent raw material; as well as The inspection standard adjustment unit adjusts the predetermined inspection standard based on the information obtained by the raw material information acquisition unit. The raw material information acquisition unit acquires information related to the basic weight or thickness of the transparent raw material, The inspection reference adjustment unit adjusts the predetermined inspection reference according to the basic weight or thickness. The abnormality detection unit determines that the printed matter is normal when a comparison result between the document image and the read image satisfies the predetermined inspection standard, and determines that the printed matter is abnormal when the comparison result does not satisfy the predetermined inspection standard.

6. The inspection device according to claim 5, wherein: The transparent raw material is a sheet-shaped or plate-shaped raw material.

7. The inspection device according to claim 5 or 6, wherein: The inspection device also has: an anti-seepage determination unit for determining whether an anti-seepage image is formed on the printed image; as well as The second reading unit reads the printed image from the printed surface side of the printed matter, When the anti-seepage determination unit determines that an anti-seepage image is formed on the printed image, the abnormality detection unit detects abnormality of the printed matter based on the original image and the read image read by the first reading unit, and on the other hand, When the see-through prevention determination unit determines that no see-through prevention image is formed on the printed image, the abnormality detection unit detects an abnormality in the printed matter based on the document image and the read image read by the second reading unit.

8. The inspection device according to claim 5, wherein: The predetermined inspection standard is a standard for the inspection items of the quality inspection of the printed matter. The inspection reference adjustment unit receives input of the inspection item and the allowable level of the inspection item when the basic weight or thickness of the transparent material exceeds a predetermined threshold value corresponding to each. The abnormality detection unit calculates the detection level of the detection item based on the original image and the read image, and judges that the printed material is normal when the detection level satisfies the allowable level accepted by the inspection reference adjustment unit. On the other hand, when the detection level does not satisfy the allowable level, it judges that the printed image is abnormal.

9. An image forming system comprising: An image forming device forms an image on one side of a transparent raw material based on an original image and outputs it as a printed matter; The inspection device according to any one of claims 1 to 8, which inspects the quality of the printed matter; as well as The paper conveying device conveys the printed matter output by the image forming device to the inspection device.

10. An inspection method, which is an inspection method of an inspection device for inspecting the quality of printed matter, comprising: Step a, obtaining an original image; Step b, reading the printed matter having a printed image formed on one side of a transparent material according to the manuscript image from the other side opposite to the one side by a first reading unit; Step c, obtaining information related to the transparent raw material; Step d, correcting the pixel values ​​of the original image according to the information obtained in step c; as well as Step e, detecting an abnormality of the printed matter based on the original image and the read image read by the first reading unit, In the step c, information related to the color of the transparent raw material is obtained. In the step d, the pixel value of the read image is corrected according to the color of the transparent raw material.

11. The inspection method according to claim 10, wherein: The transparent raw material is a sheet-shaped or plate-shaped raw material.

12. The inspection method according to claim 10 or 11, wherein: In step e, the pixel values ​​of corresponding pixel positions of a flipped image obtained by mirror-flipping either the original image or the read image and the image of the other are compared, or the pixel values ​​of mirror-symmetrical pixel positions of the original image and the read image are compared, so as to determine whether the printed matter is abnormal.

13. An inspection method, which is an inspection method of an inspection device for inspecting the quality of printed matter, comprising: Step a, obtaining an original image; Step b, reading the printed matter having a printed image formed on one side of a transparent material according to the manuscript image from the other side opposite to the one side by a first reading unit; Step c, obtaining information related to the transparent raw material; Step d, adjusting the predetermined inspection benchmark according to the information obtained in step c; as well as Step e, detecting an abnormality of the printed matter based on the original image and the read image read by the first reading unit, In step c, information related to the basic weight or thickness of the transparent raw material is obtained. In the step d, the predetermined inspection reference is adjusted according to the basic weight or thickness. In the step e, if the comparison result between the document image and the read image satisfies the predetermined inspection standard, the printed matter is determined to be normal, and if the comparison result does not satisfy the predetermined inspection standard, the printed matter is determined to be abnormal.

14. The inspection method according to claim 13, wherein: The transparent raw material is a sheet-shaped or plate-shaped raw material.

15. A recording medium, which is a computer-readable recording medium storing an inspection program, wherein: The inspection program is for causing a computer to execute the processing included in the inspection method according to any one of claims 10 to 14.

Images