Inspection device

Abstract

To improve usability in setting an inspection level for inspection of an image on a sheet.SOLUTION: An inspection device comprises: holding means that holds a reference image used for inspection; reading means having a first reading unit that reads a first surface of a sheet on which an image is formed, and a second reading unit that reads a second surface of the sheet; setting means that sets an inspection level for inspection in an inspection area; inspection means that, on the basis of the inspection level and the reference image, inspects read images of the sheet read by the reading means; and display means that displays a result of the inspection. The inspection means inspects a read first read image of a first sheet in a first inspection area at a first inspection level designated by a user, and inspects the first read image in the first inspection area at a second inspection level. The display means displays a result of the inspection at the first inspection level, and a result of the inspection at the second inspection level.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present disclosure relates to an inspection device for inspecting an image on a sheet. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there has been known an inspection system that inspects the quality of an image on a sheet by reading the sheet on which an image has been formed by a printer using a scanner disposed after the printer and analyzing the read image.

[0003] For example, Patent Document 1 discloses a technique for determining whether the images match at different inspection levels for each inspection area when comparing scanned image data corresponding to an image to be inspected with correct image data. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-187085 Summary of the Invention [Problem to be solved by the invention]

[0005] The degree to which a user is willing to tolerate image defects varies depending on various factors, such as the purpose of the printed matter, cost, and productivity. Users cannot always set the optimal inspection level before starting printing and inspection. If the inspection level is set too high, the number of sheets that are determined to be defective despite being within the acceptable range increases. On the other hand, if the inspection level is set too low, the probability of missing defects that should be detected increases. If an undesirable inspection result is output, the user can change the inspection level setting and instruct printing and inspection again, but it has been difficult for them to know how to change the inspection level.

[0006] In view of the above circumstances, an object of the present invention is to improve usability when setting an inspection level for inspecting an image on a sheet. [Means for solving the problem]

[0007] According to one aspect, an inspection device is provided that includes a holding means for holding a reference image to be used for inspection, a reading means having a first reading unit for reading a first side of a sheet on which an image is formed and a second reading unit for reading a second side of the sheet, a setting means for setting an inspection level for inspection of an inspection area, an inspection means for inspecting a read image of the sheet read by the reading means based on the inspection level and the reference image, and a display means for displaying results of the inspection by the inspection means, wherein the inspection means inspects a first read image of the first sheet read by the reading means in a first inspection area at a first inspection level specified by a user, and inspects the first read image in the first inspection area at a second inspection level different from the first inspection level, and the display means displays a first inspection result for the inspection at the first inspection level and a second inspection result for the inspection at the second inspection level. [Effects of the Invention]

[0008] According to the present disclosure, usability is improved when setting an inspection level for inspecting an image on a sheet. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing an example of the configuration of an inspection system according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing an example of the configuration of an external controller according to an embodiment. [Figure 3] FIG. 2 is a block diagram showing an example of the configuration of a printer controller according to an embodiment. [Figure 4] FIG. 2 is a block diagram showing an example of the configuration of a reader controller according to an embodiment. [Figure 5] FIG. 4 is an explanatory diagram showing an example of the configuration of a job setting screen. [Figure 6] FIG. 10 is an explanatory diagram showing an example of the configuration of a correct image registration screen. [Figure 7] FIG. 10 is an explanatory diagram showing an example of the configuration of a correct image confirmation screen. [Figure 8] FIG. 10 is an explanatory diagram showing an example of the configuration of an inspection area setting screen. [Figure 9] FIG. 10 is an explanatory diagram showing an example of the configuration of an additional registration screen. [Figure 10] FIG. 10 is an explanatory diagram showing an example of the configuration of a detailed setting screen. [Figure 11] FIG. 10 is an explanatory diagram showing an example of the configuration of an examination status screen. [Figure 12] FIG. 10 is an explanatory diagram showing an example of the configuration of an examination result screen. [Figure 13] 10 is a flowchart showing an example of the flow of a correct image registration process. [Figure 14] 10 is a flowchart showing an example of the flow of an inspection process. [Figure 15] 10 is a flowchart showing an example of a detailed flow of a test result display process. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0011] <1. System Overview> FIG. 1 is a schematic diagram showing the configuration of an inspection system 1 according to one embodiment. Referring to FIG. 1, the inspection system 1 includes a personal computer (PC) 10, an external controller 50, and an image forming apparatus 100. The PC 10 is connected to the external controller 50 via a network 20. The network 20 may be a wired communication network or a wireless communication network. For example, the network 20 may include one or more of a local area network (LAN), a wide area network (WAN), and a public communication line. The external controller 50 is connected to the image forming apparatus 100 via a connection line 70. The connection line 70 may be a communication network such as a LAN, or may be a dedicated line for connection with the image forming apparatus 100. As will be described later, the connection line 70 may include a line for communication and a line for image signals.

[0012] The PC 10 is a client terminal that issues print jobs to be executed by the image forming apparatus 100. The PC 10 typically includes a communication interface (I / F), an input device, a display, storage, memory, and a processor. One or more applications and a printer driver are installed on the PC 10. When a user requests printing, the printer driver generates page description language (PDL) data representing the image to be printed and sends the generated PDL data and a print instruction to the external controller 50. The printer driver, in cooperation with a job control unit 60 of the external controller 50 (described later), can display a print dialog on the display of the PC 10. The user can specify various control parameters related to printing and inspection in the print dialog.

[0013] The external controller 50 receives a print instruction from the PC 10 and issues a print job to the image forming apparatus 100. The external controller 50 may also be referred to as an image processing controller, a digital front end, or a print server. The configuration of the external controller 50 will be described in more detail later.

[0014] Image forming apparatus 100 is an apparatus that executes a print job and forms an image on a sheet. In this embodiment, image forming apparatus 100 has an inspection function that reads a sheet on which an image has been formed, generates read image data, and inspects the quality of the print (the quality of the image on the sheet) based on the generated read image data. Therefore, image forming apparatus 100 may also be referred to as an inspection apparatus.

[0015] 2. General Configuration of Image Forming Apparatus 1, the image forming apparatus 100 includes a printer unit 120, an inserter 140, a reader unit 150, a stacker 170, and a finisher 180. The printer unit 120, the inserter 140, the reader unit 150, the stacker 170, and the finisher 180 are connected to one another by signal lines such as communication cables. However, only the signal line 101 between the printer unit 120 and the reader unit 150 is shown in FIG.

[0016] <2-1. Printer unit> The printer unit 120 is an image forming unit that forms an image on a sheet. In this embodiment, the printer unit 120 is a color laser printer that can print color images using an electrophotographic method. In other embodiments, the printer unit 120 may be another type of printer, such as a monochrome laser printer or an inkjet printer. Furthermore, the printer unit 120 or the entire image forming apparatus 100 may be configured as a multifunction peripheral (MFP).

[0017] In the example of FIG. 1, the printer unit 120 includes an operation panel 110, image forming units 121Y, 121M, 121C, and 121K, an intermediate transfer member 126, a transfer unit 127, a fuser 128, paper feed trays 131 and 132, and a printer controller 200. The operation panel 110 provides a user with a user interface (UI) consisting of a combination of a display and an input device. The input device may include, for example, one or more of buttons, a numeric keypad, a touch panel, and a switch. The detailed configuration of the printer controller 200 will be described in detail later.

[0018] Image forming unit 121Y forms a yellow (Y) toner image on intermediate transfer body 126. Image forming unit 121M forms a magenta (M) toner image on intermediate transfer body 126. Image forming unit 121C forms a cyan (C) toner image on intermediate transfer body 126. Image forming unit 121K forms a black (K) toner image on intermediate transfer body 126. Since image forming units 121Y, 121M, 121C, and 121K have the same configuration, the configuration of image forming unit 121Y will be described as an example. Image forming unit 121Y includes a photosensitive drum 122, a charger 123, an exposure unit 124, and a developing unit 125. Photosensitive drum 122 is a drum-shaped photosensitive body with a photosensitive layer on its surface. Photosensitive drum 122 rotates around its drum axis in the direction of arrow R in the figure. The charger 123 uniformly charges the surface of the rotating photosensitive drum 122. The exposure unit 124 irradiates the photosensitive drum 122 with laser light in accordance with image data (representing a yellow image in this case) input from the printer controller 200. The laser light output from the exposure unit 124 scans the charged surface of the photosensitive drum 122 in the drum axial direction, thereby forming an electrostatic latent image on the surface of the photosensitive drum 122. The developing unit 125 develops the electrostatic latent image on the photosensitive drum 122 by supplying toner (yellow in this case) to the surface of the photosensitive drum 122. As a result, a toner image is formed on the surface of the photosensitive drum 122. The yellow toner image formed on the surface of the photosensitive drum 122 in the image forming unit 121Y is transferred to an intermediate transfer body 126. Furthermore, the magenta, cyan, and black toner images formed on the surfaces of the respective photosensitive drums 122 in the image forming units 121M, 121C, and 121K are transferred in order to the intermediate transfer body 126 in a manner that superimposes the yellow toner image. As a result, a full-color toner image is formed on the intermediate transfer body 126. The intermediate transfer body 126 is an endless belt member that rotates clockwise in the drawing. The intermediate transfer body 126 transports the full-color toner image to the position (transfer nip) of the transfer unit 127.

[0019] Each of the paper feed trays 131 and 132 stores a stack of sheets. The paper feed trays 131 and 132 may store the same type of sheets or different types of sheets. Although two paper feed trays 131 and 132 are shown in FIG. 1, the number of paper feed trays provided in the image forming apparatus 100 is not limited to two. When a print job is executed, sheets are picked up one by one from the paper feed tray 131 or 132 by a feed mechanism and transported along the transport path 133.

[0020] Under the control of the printer controller 200, a sheet picked up from the paper feed tray 131 or 132 is transported to the transfer nip in time with the arrival of the toner image on the intermediate transfer body 126 at the transfer nip. The transfer unit 127 transfers the toner image carried on the intermediate transfer body 126 to the sheet at the transfer nip. The fuser 128 includes a heater and a pressure roller. The fuser 128 heats the toner image transferred to the sheet with the heater and presses it with the pressure roller. This melts the toner on the sheet, and the toner image is fixed to the sheet. While FIG. 1 shows an example in which the image forming apparatus 100 includes one fuser 128, the image forming apparatus 100 may further include a second fuser used, for example, to increase gloss or improve fixability.

[0021] The conveying path 133 branches into conveying paths 134 and 135 downstream of the fuser 128. The sheet that has passed through the fuser 128 is first conveyed from the conveying path 133 to the conveying path 135. When the trailing edge of the sheet enters the conveying path 135, the conveying direction is reversed, and the sheet is discharged to the reader unit 150 by discharge rollers 137. When double-sided printing is performed, the sheet that has entered the conveying path 135 is conveyed to the conveying path 136, and then returns from the conveying path 136 to the conveying path 133, where it passes through the transfer nip again in an inverted state. At the transfer nip, a toner image is formed on the back side of the sheet by the transfer unit 127, and the toner image is fixed to the sheet in the fuser 128. The sheet with images formed on both sides is discharged to the inserter 140 by discharge rollers 137.

[0022] <2-2. Inserter> The inserter 140 includes an insert tray 141. Additional sheets to be inserted between successive sheets on which images are formed by the printer unit 120 are placed on the insert tray 141. When the insert function is enabled in a print job, the inserter 140 merges additional sheets supplied from the insert tray 141 into the gaps between sheets sequentially received from the printer unit 120 at a specified timing. Although not shown in FIG. 1 , the inserter 140 may include a controller that controls the insertion of such additional sheets. Alternatively, the insertion of additional sheets may be controlled by the printer controller 200 or the reader controller 250. The inserter 140 ejects the sheets received from the printer unit 120 and the additional sheets to the reader unit 150.

[0023] <2-3. Leader Unit> The reader unit 150 is a reading means that optically reads a sheet on which an image has been formed by the printer unit 120, and generates read image data representing the read image. In the example of FIG. 1, the reader unit 150 includes an operation panel 115, a sheet sensor 151, a flow reading glass 152, a first reading sensor 153, a flow reading glass 154, a second reading sensor 155, and a reader controller 250. The operation panel 115 provides the user with a user interface consisting of a combination of a display and an input device. The detailed configuration of the reader controller 250 will be described in detail later.

[0024] The sheet sensor 151 detects the leading edge of each sheet received from the inserter 140. The sheet sensor 151 may be, for example, a photointerrupter. The first reading sensor 153 optically reads the bottom surface of a sheet passing over the flow reading glass 152 to generate read image data and outputs the generated read image data to the reader controller 250. The second reading sensor 155 optically reads the top surface of a sheet passing under the flow reading glass 154 to generate read image data and outputs the generated read image data to the reader controller 250. The first reading sensor 153 and the second reading sensor 155 may be, for example, a contact image sensor (CIS) or a line scan camera. The timing at which the first reading sensor 153 and the second reading sensor 155 read the sheet may be controlled by the reader controller 250 based on the timing at which the sheet sensor 151 detects the leading edge of the sheet. The read image data output from each reading sensor to the reader controller 250 may be, for example, data indicating the RGB signal value of each pixel position. The reader unit 150 discharges each sheet that has passed through the flow reading glass 154 to the stacker 170.

[0025] <2-4. Stacker> The stacker 170 includes a stack tray 171 and an escape tray 172. The stack tray 171 is a large-capacity tray capable of stacking a large number of sheets. When the stack tray 171 is specified as the sheet discharge destination in a print job, sheets received from the reader unit 150 are sequentially discharged to the stack tray 171. The escape tray 172 is a tray to which sheets determined to be defective as a result of inspection by the reader unit 150 are discharged. Although not shown in FIG. 1 , the stacker 170 may include a controller that controls the discharge of sheets to these trays. Alternatively, the discharge of sheets may be controlled by the printer controller 200 or the reader controller 250. The stacker 170 may further include an inversion mechanism for inverting sheets discharged to the stack tray 171. When the stack tray 171 is not specified as the sheet discharge destination, the stacker 170 discharges each received sheet (for example, sheets that are not detected as defective) to the finisher 180.

[0026] <2-5. Finisher> The finisher 180 includes a post-processing mechanism 181, a first discharge tray 182, and a second discharge tray 183. The post-processing mechanism 181 can perform post-processing, such as stapling, punching, cutting, or binding (e.g., saddle stitching), on a sheet or a stack of sheets received from the stacker 170. If the first discharge tray 182 is specified as the sheet discharge destination in a print job, the sheets are sequentially discharged to the first discharge tray 182. If execution of post-processing is specified, one or more sheets are temporarily fed into the post-processing mechanism 181, the specified post-processing is performed, and then the post-processed sheet or stack of sheets is discharged to the second discharge tray 183. Although not shown in FIG. 1 , the finisher 180 may include a controller that controls such post-processing and discharge. Alternatively, the post-processing and discharge may be controlled by the printer controller 200 or the reader controller 250. The finisher 180 may further include a lifting mechanism for raising or lowering the position of the first discharge tray 182 or the second discharge tray 183 depending on the number of sheets to be discharged.

[0027] <3. Control function configuration example> <3-1. External Controller> Fig. 2 is a block diagram showing an example of the configuration of the external controller 50. Referring to Fig. 2, the external controller 50 includes a first communication I / F 51, a second communication I / F 52, a video I / F 53, a display 54, an input device 55, a CPU 56, a memory 57, and an HDD 58. The first communication I / F 51, the second communication I / F 52, the video I / F 53, the display 54, the input device 55, the CPU 56, the memory 57, and the HDD 58 are connected to one another via a system bus 59.

[0028] The first communication I / F 51 is an interface through which the external controller 50 communicates with other devices (e.g., PC 10) via the network 20. The second communication I / F 52 is an interface that mediates control communication between the external controller 50 and the image forming apparatus 100. The video I / F 53 is an interface that mediates communication of image data (e.g., input image data for a print job) between the external controller 50 and the image forming apparatus 100. The display 54 is a device that can display images, videos, and information. The input device 55 is a device that can accept user input. The input device 55 may include, for example, one or more of a keyboard, buttons, a touch panel, and switches. The CPU (Central Processing Unit) 56 is a processing circuit that controls the overall functions of the external controller 50 by executing computer programs stored in the memory 57 or the HDD 58. The memory 57 may be, for example, any combination of RAM (Random Access Memory) and ROM (Read-Only Memory). The RAM provides the CPU 56 with a temporary storage area for calculations. The HDD (Hard Disk Drive) 58 is a storage device capable of storing large amounts of data. The HDD 58 can store, for example, image data and various setting data in addition to computer programs.

[0029] In this embodiment, the CPU 56 functions as a job control unit 60. The job control unit 60 controls the reception of print instructions, the issuance of print jobs to the image forming apparatus 100, and the feedback of job execution results to the user. For example, when a user instructs printing, the job control unit 60 generates input image data (RIP data) in bitmap format by rasterizing PDL data representing the image to be printed. The job control unit 60 may further perform image processing such as color conversion, tone correction, and binarization on the input image data. The job control unit 60 then outputs a print job to the image forming apparatus 100, including the generated input image data and control parameters that can be acquired via a UI such as a print dialog.

[0030] Regardless of the description here, the external controller 50 may be omitted from the configuration of the inspection system 1. If the inspection system 1 does not include the external controller 50, the functions of the job control unit 60 may be implemented in one or more of the PC 10, the printer controller 200, and the reader controller 250, either integratedly or distributedly.

[0031] <3-2. Printer Controller> Fig. 3 is a block diagram showing an example of the configuration of printer controller 200. Referring to Fig. 3, printer controller 200 includes a communication I / F 201, a video I / F 202, a connection I / F 203, an operation I / F 204, a printer I / F 205, a CPU 206, a memory 207, and an HDD 208. The communication I / F 201, the video I / F 202, the connection I / F 203, the operation I / F 204, the printer I / F 205, the CPU 206, the memory 207, and the HDD 208 are connected to one another via a system bus 209.

[0032] The communication I / F 201 is an interface that mediates control communication between the printer controller 200 and the external controller 50. The video I / F 202 is an interface that mediates image data communication between the printer controller 200 and the external controller 50. The connection I / F 203 is an interface that connects the printer controller 200 to the signal line 101. The operation I / F 204 is an interface that connects the printer controller 200 to the display and input devices of the operation panel 110. The CPU 206 is a processing circuit that controls the overall functions of the printer controller 200 by executing computer programs stored in the memory 207 or the HDD 208. The memory 207 may be, for example, any combination of RAM and ROM. The RAM provides the CPU 206 with a temporary storage area for calculations. The HDD 208 is a storage device that can store large amounts of data.

[0033] In this embodiment, the CPU 206 functions as a print control unit 210. When a print job is accepted via the communication I / F 201 (or the operation panel 110), the print control unit 210 controls the printer unit 120 to form an image based on input image data on a sheet in accordance with control parameters included in the print job. The print control unit 210 displays the progress and execution results of the print job on the display of the operation panel 110, and can also report them to the job control unit 60 of the external controller 50 via the communication I / F 201.

[0034] <3-3. Reader Controller> Fig. 4 is a block diagram showing an example of the configuration of reader controller 250. Referring to Fig. 4, reader controller 250 includes image processing circuits 251 and 252, a connection I / F 253, an operation I / F 254, a CPU 256, and a memory 257. The image processing circuits 251 and 252, the connection I / F 253, the operation I / F 254, the CPU 256, and the memory 257 are connected to one another via a system bus 259.

[0035] The image processing circuit 251 performs image processing such as analog-to-digital conversion (ADC), color conversion, and noise removal on the scanned image data generated by the first scanning sensor 153 scanning the bottom surface of the sheet. The image processing circuit 252 performs image processing such as ADC, color conversion, and noise removal on the scanned image data generated by the second scanning sensor 155 scanning the top surface of the sheet. The connection I / F 253 is an interface that connects the reader controller 250 to the signal line 101. The operation I / F 254 is an interface that connects the reader controller 250 to the display and input device of the operation panel 115. The CPU 256 is a processing circuit that controls all functions of the reader controller 250 by executing computer programs stored in the memory 257. The memory 257 may be, for example, any combination of RAM and ROM. The RAM provides the CPU 56 with a temporary storage area for calculations.

[0036] In this embodiment, the CPU 256 functions as the inspection unit 260. When the inspection function is enabled in a print job, the inspection unit 260 causes the reader unit 150 to read sheets on which images have been formed by the printer unit 120, and acquires read image data. In the case of single-sided printing, the inspection unit 260 acquires read image data for the bottom surface of each sheet, which is generated by the first reading sensor 153 and processed by the image processing circuit 251. In the case of double-sided printing, the inspection unit 260 also acquires read image data for the top surface of each sheet, which is generated by the second reading sensor 155 and processed by the image processing circuit 252. In the following description, the image of each surface to be inspected, represented by the read image data, is referred to as an inspection target image.

[0037] The inspection unit 260 inspects each inspection target image by comparing the scanned image data with authentic image data corresponding to an authentic image (reference image) that serves as the inspection standard. For example, the inspection unit 260 divides the inspection target image and the authentic image into multiple segments and compares the partial images between the inspection target image and the authentic image for each segment. The inspection unit 260 may determine that there is no defect (meets the pass criterion) if the amount of positional deviation between the contents of the partial images is equal to or less than a first threshold, and that there is a defect (does not meet the pass criterion) if the deviation exceeds the first threshold. The inspection unit 260 may also determine that there is no defect if the size of a stain or streak that is not present in the authentic image but is present in the inspection target image is equal to or less than a second threshold, and that there is a defect if the size of the stain or streak exceeds the second threshold. The inspection unit 260 may also perform optical character recognition (OCR) on the inspection target image and the authentic image and determine whether there is a defect based on a comparison of the recognized characters. These comparison techniques may be combined in any manner.

[0038] In this embodiment, the inspection unit 260 inspects the image to be inspected at an inspection level selected from multiple candidate inspection levels (hereinafter referred to as candidate levels). The higher (stricter) the inspection level, the smaller the difference between the image to be inspected and the correct image that may be detected as a printing defect. For example, between inspection levels "A" and "B," inspection level "A" is assumed to be higher. In this case, the judgment threshold (e.g., the first threshold and / or second threshold described above) used for inspection at inspection level "A" is smaller than the judgment threshold used for inspection at inspection level "B." In the following description, the inspection level is represented by an integer value, with a larger integer corresponding to a higher inspection level. For example, the inspection level may be one of three candidate levels, Level 1 to Level 3, or one of five candidate levels, Level 1 to Level 5.

[0039] In one embodiment, the inspection unit 260 may inspect whether the inspection target image contains defects (also referred to as printing defects) within each of one or more inspection areas registered in advance in association with the reference image. Areas not included in any of the inspection areas may be excluded from inspection. Even if a difference exists between the inspection target image and the reference image in an area excluded from inspection, the difference will not be detected as a printing defect. Furthermore, when two or more inspection areas are registered in association with the reference image, different inspection levels may be set for the two or more inspection areas. For example, when a photographic image is printed, a first inspection area may be set for the subject area and a second inspection area may be set for the background area, with a relatively high inspection level set for the first inspection area and a relatively low inspection level set for the second inspection area. The inspection areas may be specified by the user using, for example, the PC 10 or the operation panel 110. Furthermore, the inspection unit 260 may automatically specify an area recognized by analyzing the reference image (e.g., a face area or a person area recognized through image recognition) as the inspection area.

[0040] In this embodiment, the reference image data may be generated in advance by reading a sheet on which a reference image is formed (hereinafter referred to as a reference sheet) by the printer unit 120 and stored in the memory 257. As an example, the reference sheet may be supplied from the insert tray 141 of the inserter 140 described above and read by the reader unit 150. The inspection unit 260 may generate the reference image data by performing processes such as resolution conversion, noise removal, superposition, and averaging on the read image data of the reference sheet read by at least one of the first reading sensor 153 and the second reading sensor 155. As another example, the reference sheet may be read by a scanner (not shown in FIG. 1) that may be integrated with the printer unit 120. In other embodiments, the reference image data may be data generated (without going through the printing and reading processes) based on input image data (RIP data) accepted when forming the inspection target image on a sheet.

[0041] In some embodiments, print defects detected by the inspection unit 260 may be classified into multiple defect types, such as two or more of the following: Stains (spots of dirt) Streaks (linear stains) Misalignment (displacement of printed image) Color deviation (color tone deviation) Incorrect concentration (too high / too low) Missing images or text The user can specify which defect type should be inspected as an inspection-related parameter. In the following description, the defect type to be inspected is referred to as an "inspection item." The inspection unit 260 can inspect the image to be inspected using different inspection methods for different inspection items. For example, detection of blemishes can be performed based on simple pixel value comparison using a relatively small segment size, while detection of streaks can be performed based on edge comparison as well as pixel value comparison using a relatively large segment size. In addition, the inspection unit 260 can inspect two or more defect types at different inspection levels. For example, if some small blemishes are acceptable but streaks are not, a relatively low inspection level can be specified for blemishes and a relatively high inspection level can be specified for streaks.

[0042] The inspection unit 260 may display the progress and results of the inspection on the display of the operation panel 115 and may report them to the printer controller 200 (and further to the external controller 50) via the connection I / F 253. The inspection results include the presence or absence of a printing defect detected for each inspection target image, and for an inspection target image in which a printing defect was detected, the inspection results include the type of the detected printing defect and location information indicating the location of the printing defect. The inspection unit 260 may record the inspection results in an inspection log stored in the memory 257 along with identification information of the inspection target image (e.g., sheet number and front / back distinction) and the inspection date and time. The inspection unit 260 may control the stacker 170 to discharge defective sheets in which a printing defect was detected to the escape tray 172. Alternatively, defective sheets may be discharged to the same discharge destination as normal sheets, or the discharge position of the defective sheets may be shifted from the discharge position of normal sheets at the same discharge destination. Shifting the discharge position reduces the burden on the user of removing defective sheets from a stack of discharged sheets.

[0043] <4. Example of user interface configuration> This section describes some examples of the configuration of inspection-related UIs provided to the user in the inspection system 1. These UIs may be provided via any display device under the control of at least one (control means) of the printer driver of the PC 10, the external controller 50, the printer controller 200, and the reader controller 250.

[0044] <4-1. Print job settings> 5 is an explanatory diagram showing an example of the configuration of a job setting screen 400 for setting a print job to be executed in the inspection system 1. The job setting screen 400 can be generated by the job control unit 60 of the external controller 50 and displayed on a display.

[0045] 5, the job setting screen 400 includes five setting fields 401, 402, 403, 405, and 406 for basic settings of the print job, an inspection setting section 410, and buttons 418 and 419. The setting field 401 is a field for receiving input of the number of copies to be printed. The setting field 402 is a field for receiving designation of the color mode (e.g., full color or monochrome). The setting field 403 is a field for receiving designation of the printing side (e.g., single-sided or double-sided). The setting field 405 is a field for receiving designation of the paper feed tray. The setting field 406 is a field for receiving designation of the output destination.

[0046] The inspection setting section 410 includes a check box 411, a preview window 412, buttons 413 and 417, and setting fields 415 and 416. The check box 411 is an object that allows the user to specify whether or not to enable inspection of an image printed on a sheet. In the example of FIG. 5, the check box 411 is checked, so inspection is enabled. Other objects in the inspection setting section 410 may be operable only when the check box 411 is checked. The preview window 412 displays a preview of a representative correct image when a correct image to be used for inspection has been registered. In the example of FIG. 5, the correct image has not been registered, so the preview window 412 does not display a preview of the correct image. The button 413 is a button for calling the correct image registration function of the reader unit 150. Examples of UIs related to registering correct images will be described later with reference to FIGS. 6 to 9. The setting field 415 is a field that accepts specification of a discharge destination for defective sheets (for example, the same as for normal sheets or an escape tray). The setting field 416 is a field that accepts the specification of the side to be inspected (for example, the front side only, the back side only, or both sides). The specification of the print side in the setting field 403 and the specification of the side to be inspected in the setting field 416 do not necessarily have to match (i.e., only one side may be inspected when double-sided printing is performed, or both sides may be inspected when single-sided printing is performed). The button 417 is a button for calling up a function for detailed inspection-related settings. An example of a UI for detailed inspection-related settings will be described later with reference to FIG. 10.

[0047] Button 418 is a button for canceling the issuance of the print job and closing the job setting screen 400. Button 419 is a button for instructing the start of execution of the print job. When the user operates button 419, the job control unit 60 issues a print job including input image data and control parameters indicating the settings accepted via the job setting screen 400 to the image forming apparatus 100. The print control unit 210 of the printer controller 200 accepts the print job and executes the print job according to the print-related settings. The print control unit 210 also sends an inspection start instruction to the reader controller 250 along with control parameters indicating the inspection-related settings. In response to the inspection start instruction, the inspection unit 260 of the reader controller 250 executes an inspection according to the inspection-related settings. If a correct image required for the inspection has not been registered, the inspection unit 260 may notify the print control unit 210 and the job control unit 60 of an error so that the execution of the print job will not start until the correct image is registered.

[0048] 5 shows an example in which the job setting screen 400 includes the inspection setting section 410, but the inspection setting section 410 may be provided as an inspection setting screen that is independent from the job setting screen 400 (for example, that can be called from the job setting screen 400). Furthermore, the inspection setting section 410 or the inspection setting screen may further include objects for receiving an instruction to print the correct image when the correct image has been registered (for example, a field for inputting the number of copies to be printed of the correct image and a button for triggering printing).

[0049] <4-2. Registering the correct image> 6 is an explanatory diagram showing an example of the configuration of a correct image registration screen 430 for accepting registration of a correct image. The correct image registration screen 430 can be generated by the inspection unit 260 of the reader controller 250 and displayed on a display.

[0050] Referring to FIG. 6 , the reference image registration screen 430 includes three setting fields 431, 432, and 433, and buttons 435, 438, and 439. The setting field 431 is a field for receiving input of the number of reference images to be registered. For example, when inspecting printed images on both sides of N sheets (N is a natural number), a total of N×2 reference images must be registered. The setting field 432 is a field for receiving input of the number of times scanning is repeated to register one reference image. For example, the inspection unit 260 can generate one reference image corresponding to a printed image by synthesizing (e.g., superimposing or averaging) K scanned images generated by scanning K sheets (K is a natural number) on which the same printed image is printed. The setting field 433 is a field for receiving designation of the scanned side (e.g., single-sided or double-sided) of the reference sheet. The button 435 is a button for calling up a previously registered reference image as a reference image for a new print job. Button 438 is a button for canceling the registration of the correct image and closing the correct image registration screen 430. Button 439 is a button for instructing the start of reading of the correct answer sheet. When the user operates button 439, the inspection section 260 controls the reader unit 150 to sequentially read the correct answer sheets conveyed from the inserter 140 and generate read image data, and generates correct answer image data based on the read image data.

[0051] While the reading of the correct answer sheet is in progress, the inspection unit 260 notifies the user of the progress of the reading on the display. When the reading of the correct answer sheet is completed, the inspection unit 260 displays a confirmation screen on the display to allow the user to confirm the correct answer image to be registered.

[0052] Fig. 7 is an explanatory diagram showing an example of the configuration of the correct image confirmation screen 440. Referring to Fig. 7, the correct image confirmation screen 440 includes a selection field 441, a preview window 442, buttons 443, 444, 448, 449, and objects 445a, 445b, 446, 447a, 447b, 447c.

[0053] The selection field 441 is a field that allows switching between pages of the correct image to be confirmed. In the following description, the term "page" is used to indicate a position in a series of images (images to be inspected or correct images) that is identified by a combination of a sheet and a side (front / back). The preview window 442 is a window that displays a preview of the correct image of the page selected in the selection field 441. The objects 445a and 445b are buttons for moving the selected sheet forward or backward, and the object 446 is a button for inverting the selected side. When the object 445a, 445b, or 446 is operated, the page selection in the selection field 441 and the display of the preview of the correct image in the preview window 442 are switched. The objects 447a and 447b are buttons for changing the display magnification of the preview in the preview window 442. The object 447c is a set of buttons for moving the part displayed in the preview window 442 in four directions: up, down, left, and right. Note that although this section describes an example in which several UI objects are arranged on the screen, each object may be replaced by a gesture operation by the user (for example, a flick, pinch in, pinch out, or swipe).

[0054] Button 443 is a button used by a user who has determined that there is no problem with the (unregistered) correct answer image displayed in the preview window 442 to instruct the registration of the correct answer image. When the user operates button 443, the inspection unit 260 registers the corresponding correct answer image in association with the page selected in the selection field 441. Button 444 is a button used by a user who has determined that there is a problem with the correct answer image (for example, due to a printing defect, a missing image, or a mistaken correct answer sheet) to cancel the registration of the correct answer image. When the user operates button 444, the inspection unit 260 can discard the corresponding correct answer image. Button 448 is a button used to collectively cancel the registration of correct answer images generated by reading a series of correct answer sheets. Button 449 is a button used to collectively instruct the registration of all correct answer images generated by reading a series of correct answer sheets.

[0055] 8 is an explanatory diagram showing an example of the configuration of an inspection area setting screen 450, which may be further displayed on the display when at least one correct image has been registered. Referring to FIG. 8, inspection area setting screen 450 includes a selection field 451, a preview window 452, a check box 453, level setting sections 454a and 454b, and buttons 457, 458, and 459.

[0056] The selection field 451 is a field that enables switching of the page of the reference image that is the target of the setting of the inspection area. The preview window 452 is a window that displays the reference image registered in association with the page selected in the selection field 451. The check box 453 is an object that allows the user to specify whether or not to enable the setting of the inspection area for the reference image of the page selected in the selection field 451. If the check box 453 is off, the inspection level for each inspection area of the selected reference image is not set, and the inspection level can be set for the entire reference image. If the check box 453 is on, it is possible to set the inspection level for each inspection area of the selected reference image.

[0057] Level setting section 454a includes an object for accepting an inspection level setting for an inspection area that is automatically set by inspection unit 260. In the example of FIG. 8, two face areas recognized in the correct image are set as automatic inspection areas, and marks 461 pointing to these face areas are superimposed on preview window 452. The user can specify whether or not to enable such automatic inspection area setting in the detailed settings described later. Level setting section 454b includes an object for accepting an inspection level setting for an inspection area that is set by the user. In the example of FIG. 8, a designated area specified by a user operation (e.g., touch or drag) on preview window 452 is set as the user's own inspection area (custom area A), and a mark 462 pointing to custom area A is superimposed on preview window 452.

[0058] Because the configurations of the level setting sections 454a and 454b may be similar, the level setting section 454b will be described here as an example. The level setting section 454b includes a check box 455a, objects 455b and 455c, a check box 456a, and objects 456b and 456c. The check box 455a is an object that allows the user to specify whether or not to enable inspection for "stains," one of the inspection items. The objects 455b and 455c are buttons for changing the inspection level for "stains." For example, if the user desires a more detailed inspection for "stains" (e.g., if the user desires sheets with only small stains to be detected as defective), the user turns on the check box 455a and increases the inspection level by operating the object 445b. Conversely, if the user desires only a rough inspection for "stains," the user turns on the check box 455a and decreases the inspection level by operating the object 445c. A user who does not wish to inspect for "stains" sets check box 455a to "off." Check box 456a is an object that allows the user to specify whether or not to enable inspection for "streaks," another inspection item. Objects 456b and 456c are buttons for changing the inspection level for "streaks." These inspection level settings in level setting section 454b are applied to custom area A.

[0059] Inspection unit 260 may set the color of mark 461 and the color of the frame of level setting section 454a in preview window 452 to the same color (e.g., blue), and may set the color of mark 462 and the color of the frame of level setting section 454b to the same color (e.g., green), making it easier for the user to understand which setting in which section is applied to which inspection area.

[0060] Button 457 is a button for canceling the setting of the inspection area and returning to the previous screen. Button 458 is a button for transitioning to a screen for additionally registering a correct image. Button 458 may be displayed on the inspection area setting screen 450, for example, when there is a page for which no correct image has been selected to be registered on the correct image confirmation screen 440 of FIG. 7. When the user operates button 458, the inspection unit 260 stores the settings of the inspection area and inspection level received via the inspection area setting screen 450 in the memory 257, and then displays an additional registration screen for additionally registering a correct image on the display. Button 459 is a button for completing the registration of the correct image. When the user operates button 459, the inspection unit 260 stores the settings of the inspection area and inspection level in the memory 257 and closes the inspection area setting screen 450.

[0061] FIG. 9 is an explanatory diagram showing an example of the configuration of an additional registration screen 470 for additionally registering a correct image. Referring to FIG. 9, the additional registration screen 470 includes radio buttons 471a and 471b, setting fields 472 and 475, a text field 474, and buttons 473, 478, and 479. The radio buttons 471a and 471b are objects that accept a choice between additionally registering a correct image for only a specific page or for all pages for which a correct image has not yet been registered. To additionally register a correct image for only a specific page, the user selects radio button 471a, selects the target page in the setting field 472, and operates button 473. The selected page is then added to a list of pages to be additionally registered. The text field 474 is a field that displays a list of pages to be additionally registered. To additionally register a correct image for all pages, the user selects radio button 471b. The setting field 475 is a field for receiving input of the number of times reading is repeated for additional registration of one correct image. The button 478 is a button for canceling the additional registration of the correct image and closing the additional registration screen 470. The button 479 is a button for instructing the start of reading of the correct answer sheet for additional registration. When the user operates the button 479, the inspection unit 260 controls the reader unit 150 to read the correct answer sheet conveyed from the inserter 140 and generate read image data, and generates correct answer image data for additional registration based on the read image data.

[0062] While the reading of the correct answer sheet is in progress, the inspection unit 260 notifies the user of the reading progress status on the display. When the reading of the correct answer sheet for additional registration is completed, the inspection unit 260 displays a confirmation screen similar to that described using FIG. 7 on the display.

[0063] In addition, the inspection unit 260 may send a request to print the correct image to be registered to the print control unit 210 of the printer controller 200 or the job control unit 60 of the external controller 50 in response to reading the correct image sheet for initial registration or additional registration of the correct image.

[0064] <4-3. Detailed settings related to inspection> Fig. 10 is an explanatory diagram showing an example of the configuration of a detailed setting screen 480 for detailed settings related to an inspection, which is called up from the job setting screen 400 (or some other menu screen) described using Fig. 5. The detailed setting screen 480 can be generated by, for example, the inspection unit 260 and displayed on a display.

[0065] Referring to FIG. 10 , the detailed setting screen 480 includes check boxes 481a, 482a, 483a, objects 481b, 481c, check boxes 484, 485, 486, and buttons 488 and 489. The check boxes 481a, 482a, and 483a are objects that allow the user to specify whether to enable inspection for the candidate inspection items of “stains,” “streaks,” and “misalignment,” respectively. In the example of FIG. 10 , the check boxes 481a and 482a are set to “on,” which enables inspection of “stains” and “streaks” on the inspection area setting screen 450 described with reference to FIG. 8 . The objects 481b and 481c are buttons for changing the default inspection level for “stains.” Similar objects exist for changing the inspection levels for “streaks” and “misalignment.” The check box 484 is an object that allows the user to specify whether to enable automatic setting of an inspection area for the target image. Check box 485 is an object that allows the user to specify whether or not to display provisional inspection results at a candidate level other than the current inspection level when a defect is detected during inspection. When check box 485 is set to on, the inspection unit 260 provides the user with provisional inspection results at other candidate levels along with the inspection results at the current inspection level on an inspection result screen, which will be described in detail later. Check box 486 is an object that allows the user to specify whether defective sheets that may be detected during inspection should be discharged to the escape tray 172 of the stacker 170 or to the same discharge destination as normal sheets.

[0066] Button 488 is a button for canceling the change in the detailed settings and closing the detailed settings screen 480. Button 489 is a button for completing the change in the detailed settings. When the user operates button 489, the inspection unit 260 reflects the change in the detailed settings accepted via the detailed settings screen 480 in the settings stored in memory 257 and closes the detailed settings screen 480. The inspection-related settings accepted via the detailed settings screen 480 may be applied only to an individual print job, or may be applied commonly to multiple print jobs.

[0067] <4-4. Displaying the progress of the test> When a print job for which inspection is enabled is executed, the printer unit 120 forms an inspection target image on a sheet, and the reader unit 150 optically reads the sheet. The inspection unit 260 inspects the inspection target image by comparing the read image data with the correct image data at the inspection level set via the UI described above, and generates a first inspection result. The external controller 50, the printer controller 200, or the reader controller 250 controls the display of the inspection result on the display. In the following description, it is assumed that the inspection unit 260 serves as a control means for controlling the display of the inspection result, and the inspection result is displayed on the display of the operation panel 115.

[0068] FIG. 11 is an explanatory diagram showing an example of the configuration of an inspection status screen 490 that may be displayed on the display while inspection of a series of inspection target images is in progress. Referring to FIG. 11, the inspection status screen 490 includes a status indicator 491, an image window 492, and buttons 498 and 499. The status indicator 491 is an object that indicates the percentage of the total number of inspection target images that have been inspected. The image window 492 is a window that displays a reduced view of the most recent inspection target image (or the corresponding correct answer image) that has been inspected. The button 498 is a button for stopping (skip) the inspection of subsequent inspection target images. When the user operates the button 498, the inspection unit 260 controls the first reading sensor 153 and the second reading sensor 155 so as not to read sheets that are subsequently conveyed from the inserter 140. The button 499 is a button for suspending execution of the print job. When the user operates button 499, inspection unit 260 reports to printer controller 200 that an instruction to interrupt the job has been issued. Print control unit 210 of printer controller 200 transfers this report to job control unit 60 of external controller 50, and stops driving printer unit 120.

[0069] <4-5. Resetting the inspection level> In this embodiment, the inspection unit 260 acquires second inspection results obtained when the image to be inspected is inspected at one or more candidate levels different from the current inspection level among the multiple candidate levels, in response to the first inspection result (i.e., the inspection result at the current inspection level) satisfying a predetermined condition. In the following description, the current inspection level is also referred to as the first inspection level, and the other one or more candidate levels are also referred to as second inspection levels. The inspection unit 260 then controls the display device to display the acquired second inspection results on a screen. For example, the predetermined condition may include the first inspection result judging that the image to be inspected contains a printing defect. For another example, the predetermined condition may include the first inspection result judging that the image to be inspected contains a printing defect multiple times consecutively. For another example, the predetermined condition may include the first inspection result judging that the image to be inspected contains a printing defect more than once. For another example, the predetermined condition may include the first inspection result judging that the image to be inspected contains a printing defect more than once. For another example, the predetermined condition may include the inspection reaching a specific page designated in advance. The inspection section 260 can reset the inspection level from the first inspection level to any of the second inspection levels based on a user input acquired in response to the display of such a screen.

[0070] If the first inspection result satisfies a predetermined condition, the inspection unit 260 provisionally obtains a second inspection result by comparing the inspection target image with the comparison image at each candidate level. Then, the inspection unit 260 displays the first inspection result and the second inspection result in parallel on an inspection result screen 500 such as that shown in Fig. 12. Note that the first inspection result and the second inspection result do not necessarily have to be displayed in parallel, and may be displayed across multiple screens that can be transitioned between, for example.

[0071] 12 is an explanatory diagram showing an example of the configuration of the test result screen 500. Referring to FIG. 12, the test result screen 500 includes a target image window 501, a test result section 502, a correct image window 503, a current settings section 504, a provisional result section 505, and buttons 531, 532, and 533.

[0072] The target image window 501 is a window that displays a reduced view of the inspection target image in which a printing defect has been detected. A mark 506 indicating the location of one or more printing defects detected based on the difference between the scanned image data and the reference image data is superimposed on the target image window 501. The inspection result section 502 is a section that describes information about the first inspection result at the current inspection level. In the example of FIG. 12, the inspection result section 502 describes the identification information of the page in which the printing defect was detected, the name of the inspection area in which the printing defect was detected, the defect type, and the location information of the printing defect. The reference image window 503 is a window that displays a reduced view of the reference image used to inspect the inspection target image. The current settings section 504 is a section that describes information about the current settings of the inspection area and inspection level associated with the reference image.

[0073] Interim results section 505 is a section that displays second inspection results that indicate the location of at least one printing defect that may be detected at each of one or more candidate levels. In the example of Figure 12, interim results section 505 includes preview windows 511a, 511b, and 511c, buttons 512a and 512c, preview windows 521a, 521b, and 521c, and buttons 522a and 522c.

[0074] Preview windows 521a, 521b, and 521c show the inspection results when the image to be inspected is inspected for the presence or absence of blemishes at inspection levels "1," "2," and "3," respectively. Note that inspection level "2" is equal to the current inspection level. Preview window 511a does not have any marks superimposed to indicate the location of print defects. This means that when the inspection level is reset from "2" to "1," the blemishes detected at inspection level "2" will no longer be detected as print defects. Preview window 511b has superimposed mark 513a, which indicates the same blemish detected in the first inspection results. Preview window 511c has superimposed three marks 513a, 513b, and 513c, which indicate the locations of print defects. Marks 513b and 513c indicate blemishes not detected in the first inspection results. However, the stains indicated by each mark may be actual stains, or may be small noises that are not actually stains. In other words, when the inspection level is reset from "2" to "3," more printing defects will be detected than those detected at inspection level "2." If the user does not want the stain indicated by mark 513a to be detected as a printing defect, the user operates button 512a. The inspection unit 260 then resets the inspection level for the inspection item "stain" to the specified candidate level "1." Alternatively, if the user wants the stains indicated by marks 513b and 513c to be detected as printing defects, the user operates button 512c. The inspection unit 260 then resets the inspection level for the inspection item "stain" to the specified candidate level "3."

[0075] Preview windows 511a, 511b, and 511c show the inspection results when the image to be inspected is inspected for the presence or absence of streaks with inspection levels set to "1," "2," and "3," respectively. Note that inspection level "2" is equal to the current inspection level. As in the case of "stains," when the user operates button 522a, the inspection unit 260 resets the inspection level for the inspection item "streaks" to the specified candidate level "1." When the user operates button 522c, the inspection unit 260 resets the inspection level for the inspection item "streaks" to the specified candidate level "3."

[0076] That is, in this embodiment, the user input for resetting the inspection level on the inspection result screen 500 specifies one of one or more candidate levels as the reset inspection level. In one example, the user input for resetting the inspection level may specify one of the candidate levels as the reset inspection level for one of two or more defect types. In this case, the same user input may also specify the defect type, as in the user input for buttons 512a, 512c, 522a, or 522c in FIG. 12 . In another example, the user input for resetting the inspection level may specify one of the candidate levels as the reset inspection level for one of one or more inspection areas. In this case, the same user input may also specify the inspection area. However, the present invention is not limited to these examples, and a user input that commonly increases or decreases the inspection level for multiple defect types may also be employed. Furthermore, a user input that commonly increases or decreases the inspection level for multiple inspection areas may also be employed.

[0077] Button 531 is a button for triggering a reinspection at the reset inspection level. Button 531 can be operated after at least one inspection level has been reset according to user input. When the user operates button 531, the inspection unit 260 performs a reinspection at the reset inspection level for the inspection target image in which a printing defect was once detected. If no printing defect is detected in this reinspection, the inspection result for the inspection target image can be corrected from defective to normal. In other words, the inspection result can be corrected immediately. Button 532 is a button for stopping the inspection of subsequent inspection target images. Button 533 is a button for triggering the resumption of inspection. When the user operates button 533, the inspection unit 260 resumes inspection of subsequent sheets. If the inspection level has been reset, inspection of subsequent sheets is performed at the reset inspection level.

[0078] In a variant, the interim result section 505 may selectively display only second test results for a fewer number of candidate levels, instead of comprehensively displaying second test results for all candidate levels. The inspection unit 260 may select the second test levels for which the second test results should be displayed based on user input or predefined conditions. For example, the inspection unit 260 may determine an upper limit on the number of second test levels to fit the size of the available display area, and generate the second test results by selecting a number of second test levels that does not exceed the determined upper limit. In particular, when there are multiple candidate levels, limiting the number of second test levels in this way can shorten the time required to generate and preview the test results. It also makes efficient use of the display area to improve the visibility of the test results.

[0079] In another variation, the provisional results section 505 may display second inspection results only for inspection items for which printing defects were detected, instead of displaying second inspection results for all enabled inspection items. For example, when inspection for stains and streaks is enabled and an inspection target image is detected to contain streaks but not stains, the inspection unit 260 may perform a provisional inspection for streaks only at one or more second inspection levels and display the second inspection results on the display. In this case, the inspection unit 260 may accept user input to reset the inspection level only for streaks. This makes it easier to optimize the inspection level for printing defects of the same type as the actually detected printing defect. Furthermore, the time required to generate and preview inspection results may be shortened, and the visibility of the inspection results may be improved.

[0080] <5. Processing flow> <5-1. Correct image registration process> Fig. 13 is a flowchart showing an example of the flow of a correct image registration process that can be executed in this embodiment by the inspection system 1. The correct image registration process in Fig. 13 can be started, for example, in response to an operation of button 439 on the correct image registration screen 430 shown in Fig. 6. In the following description, processing steps are abbreviated as 'S'.

[0081] First, in S101, the inspection unit 260 acquires settings for reading the correct answer sheet. The settings acquired here may include, for example, the number of correct answer images to be registered, the number of times reading is repeated to register one correct answer image, and the designation of the reading side of the correct answer sheet.

[0082] Next, in S103, the inspection unit 260 monitors the sensor signal from the sheet sensor 151 and waits for the timing to read the correct answer sheet. For simplicity of explanation, it is assumed here that only one side of the correct answer sheet is to be read. When the timing to read arrives, the process proceeds to S105.

[0083] In S105, the first reading sensor 153 optically reads the correct answer sheet. Then, in S107, the first reading sensor 153 generates read image data. The image processing circuit 251 performs necessary image processing (for example, resolution conversion, noise removal, superposition, and averaging) on the read image data.

[0084] Next, in S109, the inspection unit 260 determines whether reading of all correct answer sheets has been completed. If there is a next sheet to be read, the process returns to S103. If reading of all correct answer sheets has been completed, the process proceeds to S111.

[0085] In S111, the inspection unit 260 generates correct image data based on the scanned image data acquired through the repetition of S105 and S107, and displays a correct image confirmation screen 440 including a preview of the correct image on the display. The user checks the preview of the correct image for each page on the displayed correct image confirmation screen 440, and if there is no problem, instructs to register the correct image.

[0086] The subsequent processing branches depending on the user's operation on the correct image confirmation screen 440. If one or more correct images are discarded (S113-NO) and the user selects to register additional correct images (S115-YES), the processing returns to S101, and the correct answer sheet is read for additional registration. If the registration of correct images for all pages has been completed (S113-YES) or if the user selects not to register additional correct images (S115-NO), the processing proceeds to S117.

[0087] In S117, the inspection unit 260 acquires the registered correct image data. Next, in S119, the inspection unit 260 displays the inspection area setting screen 450 on the display. If the user selects to customize the inspection area / inspection level (S119-YES), in S121 the inspection unit 260 accepts the settings of the inspection area and inspection level for the correct image of each page. If the inspection area / inspection level is not customized, default or automatic settings related to the inspection may be used for the inspection.

[0088] <5-2. Inspection processing> Fig. 14 is a flowchart showing an example of the flow of an inspection process that can be executed by the inspection system 1 in this embodiment. The inspection process in Fig. 14 can be started, for example, when inspection is enabled on the job setting screen 400 shown in Fig. 5 and execution of a print job is triggered.

[0089] First, in S201, the inspection unit 260 acquires inspection-related settings. The acquired settings may include, for example, the destination for ejecting defective sheets, the designation of the surface to be inspected, the inspection item, the inspection area, the inspection level, and whether or not to display the inspection results at candidate levels other than the inspection level when a defect is detected. In addition, in S203, the inspection unit 260 acquires registered correct image data.

[0090] Next, in S205, the inspection unit 260 monitors the sensor signal from the sheet sensor 151 and waits for the timing to read the sheet to be inspected. For simplicity's sake, it is assumed that only one side of each sheet is to be read. When the timing to read arrives, the process proceeds to S207.

[0091] In S207, the first reading sensor 153 optically reads the sheet conveyed from the inserter 140. Next, in S209, the first reading sensor 153 generates read image data. The image processing circuit 251 executes necessary image processing on the read image data.

[0092] Next, in S211, the inspection unit 260 inspects the inspection target image by comparing the inspection target image represented by the read image data with the correct image in accordance with the settings acquired in S201. For example, the inspection unit 260 determines whether or not there is a printing defect based on the difference between the read image data and the correct image data within each range of one or more inspection areas that are registered in advance in association with the correct image.

[0093] Next, in S213, the inspection unit 260 determines whether a printing defect has been detected in the image to be inspected. For example, a printing defect may be detected in the image to be inspected if there is a difference that exceeds a threshold corresponding to a preset inspection level for a defect type (inspection item) for which inspection is enabled. If a printing defect is detected, the process proceeds to S220. On the other hand, if no printing defect is detected, the image to be inspected is determined to be normal, and the process proceeds to S215.

[0094] In S215, the inspection unit 260 updates the display of the progress of the inspection. For example, the inspection unit 260 displays the inspection status screen 490 described with reference to Fig. 11 on the display, and reflects the latest inspection results in the indicators and messages on the screen each time inspection is completed for one inspection target image. Then, the process proceeds to S233.

[0095] In S220, the inspection unit 260 executes an inspection result display process, and displays an inspection result screen 500 on the display, which shows the first inspection result (indicating a printing defect) at the current inspection level, as well as the second inspection results at one or more candidate levels. The detailed flow of the inspection result display process executed here will be described further below. The inspection unit 260 may reset at least one inspection level based on user input acquired via the inspection result screen 500.

[0096] Subsequent processing branches depending on whether the user has instructed re-inspection of the inspection target image. If the user has instructed re-inspection, processing returns to S211, and the inspection target image is inspected again at the inspection level after the reset. If the user has not instructed re-inspection, processing proceeds to S233.

[0097] In S233, the inspection unit 260 discharges the sheet to a discharge destination according to the inspection results. For example, a sheet for which no printing defects are detected as an inspection result is discharged to a discharge destination for normal sheets. A sheet for which a printing defect is detected is discharged to a discharge destination for defective sheets.

[0098] Next, in S235, the inspection unit 260 determines whether inspection of all sheets has been completed. If there is a next sheet to be inspected, the process returns to S205. If inspection of all sheets has been completed, the inspection process of FIG. 14 ends.

[0099] <5-3. Test result display processing> FIG. 15 is a flowchart showing an example of the detailed flow of the test result display process that can be executed in S220 of FIG.

[0100] 15, first, in S221, the inspection unit 260 obtains a first inspection result based on the current inspection level. The first inspection result may include, for example, defect type and position information for each detected printing defect.

[0101] Next, in S222, the inspection unit 260 performs a tentative inspection at each of one or more candidate levels different from the current inspection level to obtain corresponding second inspection results, which may also include defect type and location information for each detected printing defect.

[0102] Next, in S223, the inspection unit 260 displays an inspection result screen 500 showing the first inspection result and the second inspection result on the display. For example, on the inspection result screen 500, marks indicating the positions of printing defects detected at the current inspection level are superimposed on a reduced view of the image to be inspected based on the first inspection result. Similarly, marks indicating the positions of printing defects detected at each candidate level are superimposed on a reduced view of the image to be inspected based on the second inspection result.

[0103] In S224, the inspection unit 260 waits for a user input instructing resetting of the inspection level. When the user input instructing resetting of the inspection level is received, in S225 the inspection unit 260 resets the inspection level according to the user input. For example, the inspection unit 260 resets the inspection level of the specified inspection item to the specified candidate level.

[0104] In S226, when a user input instructing resumption of inspection or re-inspection is received on the inspection result screen 500, the inspection unit 260 ends the display of the inspection results. Thereafter, the process proceeds to S231 in Fig. 14, where re-inspection of the inspection target image or inspection of the subsequent sheet is performed.

[0105] <6. Summary> Various embodiments, examples, and modifications of the technology according to the present disclosure have been described above using FIGS. 1 to 15. According to the above-described embodiments, a reading unit of an inspection system optically reads a sheet on which a target image is formed to generate read image data. The inspection unit inspects the target image by comparing the read image data with correct image data at an inspection level selected from a plurality of candidate levels to generate a first inspection result. If the first inspection result satisfies a predetermined condition, a control unit acquires a second inspection result obtained when the target image is inspected at one or more candidate levels different from the inspection level selected from the plurality of candidate levels. The control unit then displays the acquired second inspection result on a screen and resets the inspection level based on a user input acquired thereafter. Therefore, a user can easily understand how to change the inspection level from visual information displayed on the screen displaying the inspection result and provide appropriate instructions to the inspection system for resetting the inspection level. This improves usability when setting the inspection level for inspecting an image on a sheet.

[0106] In the above-described embodiment, the predetermined condition includes determining that the target image contains a printing defect. Therefore, when an undesirable inspection result is output, the inspection level can be quickly adjusted appropriately, thereby improving usability, reducing erroneous detection of printing defects, and improving inspection productivity.

[0107] In the above-described embodiment, the first inspection result at the current inspection level and the second inspection result at one or more candidate levels can be displayed side by side on the screen. Therefore, by comparing the two inspection results, the user can intuitively grasp how the number of printing defects increases or decreases when the inspection level is reset. This further improves usability.

[0108] In the above-described embodiments, the user input for resetting the inspection level may specify one of the one or more candidate levels as the reset inspection level. In one embodiment, the user input may specify the reset inspection level for one of two or more defect types. In this case, it is possible to flexibly adjust the inspection level for each defect type according to the intended use of the printed material. In another embodiment, the user input may specify the reset inspection level for a specific inspection area registered in association with the correct image. In this case, it is possible to accept detailed adjustment of the inspection level specifically for a limited portion of the target image that is of importance, thereby achieving further improvement in usability.

[0109] The embodiments, examples, and modifications described in this specification may be combined with each other in any manner.

[0110] <7. Other embodiments> The above-described embodiment can also be realized in the form of a process in which a program for realizing one or more functions is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program, or by a circuit (e.g., ASIC) that realizes one or more functions.

[0111] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0112] 1: inspection system, 10: PC, 20: network, 50: external computer, 60: job control unit, 100: image forming device, 110, 115: operation panel, 120: printer unit, 140: inserter, 150: reader unit, 153, 155: reading sensor, 170: stacker, 171: stack tray, 172: escape tray, 180: finisher, 200: printer controller, 210: print control unit, 250: reader controller, 260: inspection unit, 400: job setting screen, 430: correct image registration screen, 440: correct image confirmation screen, 450: inspection area setting screen, 470: additional registration screen, 480: detailed setting screen, 490: inspection status screen, 500: result display screen

Claims

1. A reading means having a first reading unit for reading a first surface of a sheet on which an image is formed and a second reading unit for reading a second surface of the sheet, A setting means for setting the inspection level for inspection within the inspection area, An inspection means for inspecting the read image of the sheet read by the reading means based on the inspection level and reference image, Equipped with, The aforementioned inspection means is The first read image of the first sheet read by the reading means is inspected in a first inspection area at a first inspection level specified by the user, and then inspected in the first inspection area at a second inspection level different from the first inspection level. The entire first reading image and the first inspection result for the inspection at the first inspection level are superimposed and displayed on the display means, and the entire first reading image and the second inspection result for the inspection at the second inspection level are superimposed and displayed on the display means. Inspection device.

2. The inspection apparatus according to claim 1, wherein the inspection means inspects the entire first read image at the first inspection level and inspects the entire first read image at the second inspection level.

3. The second inspection level is higher than the first inspection level, The inspection apparatus according to claim 2, wherein the inspection defects included in the second inspection result obtained at the second inspection level are inspection defects not included in the first inspection result obtained at the first inspection level.

4. The inspection apparatus according to claim 3, wherein the first inspection level is a level set by the user, and the second inspection level is a level set automatically.

5. The inspection apparatus according to claim 4, wherein the inspection means stores the second inspection result when the second inspection level is selected by the user.

6. The inspection apparatus according to claim 5, wherein the display means displays the first inspection result and the second inspection result on the same screen.

7. The inspection apparatus according to claim 6, wherein the inspection area is an area corresponding to a portion of the read image.

8. The inspection apparatus according to claim 7, wherein the setting means can set an inspection level in one of two modes: a first mode in which an inspection level is set for an inspection area corresponding to the entire read image, and a second mode in which an inspection level is set for an inspection area corresponding to a part of the read image.

9. The inspection apparatus according to claim 8, wherein the reading means reads a sheet that has been transported via an inserter from an image forming apparatus that forms an image on the sheet.

10. The inspection apparatus according to claim 6, wherein the display means displays the first inspection result and the second inspection result in parallel on the same screen.

11. The second inspection level is higher than the first inspection level, The inspection apparatus according to claim 1, wherein the inspection defects included in the second inspection result obtained at the second inspection level are inspection defects not included in the first inspection result obtained at the first inspection level.

12. The inspection apparatus according to claim 1, wherein the first inspection level is a level set by the user, and the second inspection level is a level set automatically.

13. The inspection device according to claim 1, wherein the inspection means stores the second inspection result when the second inspection level is selected.

14. The inspection apparatus according to claim 1, wherein the display means displays the first inspection result and the second inspection result on the same screen.

15. The inspection apparatus according to claim 1, wherein the inspection area is an area corresponding to the entire read image.

16. The inspection apparatus according to claim 1, wherein the inspection area is an area corresponding to a portion of the read image.

17. The inspection apparatus according to claim 1, wherein the inspection means performs the inspection in the first inspection area of ​​the first read image at a first inspection level to generate a first inspection result, and without causing the reading means to read the first sheet again, performs the inspection in the first inspection area of ​​the first read image at a second inspection level to generate a second inspection result.

18. The inspection apparatus according to claim 1, wherein the inspection means sets a first inspection level before the first sheet is read by the reading means, and sets a second inspection level after the first sheet is read by the reading means.

19. The inspection means sets the first inspection level before the first sheet is read by the reading means, and sets the second inspection level based on user input after the first sheet has been read by the reading means. The inspection means generates the second inspection result by performing the inspection in the first inspection area of ​​the first read image at the second inspection level without causing the reading means to read the first sheet again. The inspection apparatus according to claim 1.

20. The inspection apparatus according to claim 19, wherein the inspection means stores the second inspection result when the second inspection level is selected by the user.

21. The inspection apparatus according to claim 1, wherein the display means displays a first object on the screen for the user to specify the second inspection level after the first sheet has been read by the reading means.

22. The second test level is higher than the first test level. In the second test result, there were more test defects than in the first test result. The inspection apparatus according to claim 1.

23. The inspection device according to claim 22, wherein the inspection means stores the second inspection result when the second inspection level is selected by the user.

24. The inspection apparatus according to claim 1, wherein the inspection means performs the inspection in the first inspection area of ​​the first read image at a second inspection level if there is an inspection defect in the first inspection result.

25. The inspection apparatus according to claim 1, wherein the setting means can set an inspection level in one of two modes: a first mode in which an inspection level is set for an inspection area corresponding to the entire read image, and a second mode in which an inspection level is set for an inspection area corresponding to a part of the read image.

26. The inspection apparatus according to claim 1, wherein the setting means can set the type of inspection defect to be inspected by the inspection means.

27. The inspection apparatus according to claim 1, wherein the reading means reads a sheet that has been transported via an inserter from an image forming apparatus that forms an image on the sheet.

28. The inspection means detects defects based on the difference between the read image and the reference image. The first inspection result indicates the location of each defect detected at the first inspection level. The second inspection result indicates the location of each defect detected at the second inspection level. The inspection apparatus according to claim 1.

29. The inspection means is capable of performing inspections at different inspection levels for two or more types of inspection defects. The first inspection level is set for one of the two or more types of inspection defects. The inspection apparatus according to claim 1.

30. The inspection means is capable of performing inspections at different inspection levels for two or more types of inspection defects. The inspection apparatus according to claim 1, wherein the inspection means performs the inspection in the first inspection area of ​​the first read image at the second inspection level with respect to the type of inspection defect detected in the first inspection result.

31. One or more of the inspection areas are registered in association with the aforementioned reference image. The inspection means inspects the read image within the range of each registered inspection area. The inspection apparatus according to claim 1.

32. The inspection apparatus according to claim 31, wherein the second inspection level is set for one of the one or more inspection areas registered in association with the reference image.

33. The inspection apparatus according to claim 1, wherein the inspection means performs the inspection in the first inspection area of ​​the first read image at one or more second inspection levels selected from a plurality of candidate levels so as not to exceed an upper limit.

34. The inspection apparatus according to claim 33, wherein the upper limit is determined based on the size of the available display area of ​​the display means.

35. The inspection apparatus according to claim 1, wherein the reference image is generated in advance by reading a sheet on which the reference image is formed, or is generated based on input image data of a print job.

36. An image forming apparatus that forms an image on a sheet, An inspection apparatus according to any one of claims 1 to 35, which performs an inspection on the aforementioned sheet, A testing system that includes this.

37. A reading step comprising reading the first surface of a sheet on which an image is formed with a first reading unit, and reading the second surface of the sheet with a second reading unit, A setting step to set the inspection level for inspection within the inspection area, An inspection step in which the read image of the read sheet is inspected based on the aforementioned inspection level and reference image, A display step to show the test results, It has, In the inspection step, the first read image of the first sheet is inspected in a first inspection area at a first inspection level specified by the user, and then inspected in the first inspection area at a second inspection level different from the first inspection level. In the display step, the entire first read image and the first inspection result for the inspection at the first inspection level are superimposed and displayed on the display means, and the entire first read image and the second inspection result for the inspection at the second inspection level are superimposed and displayed on the display means. Testing method.

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