Inspection equipment and inspection system

Abstract

To improve usability in setting an inspection level for inspecting an image on a sheet.SOLUTION: There is provided an inspection system comprising: reading means for optically reading a sheet on which an object image is formed to generate read image data; inspection means for inspecting the object image by comparing the read image data with correct answer image data at an inspection level set out of a plurality of candidate levels to generate a first inspection result; and control means for controlling display of an inspection result on a display device, where, depending on the first inspection result satisfying a predetermined condition, the control means controls the display device so as to display, on a screen, a second inspection result acquired in the case of inspecting the object image at one or more candidate levels different from the inspection level out of the plurality of candidate levels and re-sets the inspection level on the basis of user input.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present disclosure relates to an inspection system for inspecting images on sheets. [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 with a scanner disposed after the printer and analyzing the read image.

[0003] For example, Patent Document 1 discloses a technique for determining whether or not the images match each other at different inspection levels for each inspection area when comparing scanned image data corresponding to an inspection target image 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 tolerates image defects varies depending on various factors such as the purpose of the printed matter, cost, and productivity. A user cannot always set an optimal inspection level before printing and inspection are started. If an inspection level is set too high, the number of sheets that are determined to be defective even though they are within the acceptable range increases. On the other hand, if an inspection level is set too low, the probability of missing defects that should be detected increases. When an undesirable inspection result is output, a user can change the inspection level setting and instruct printing and inspection again, but it has been difficult for the user 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, there is provided an inspection system comprising: a reading means for optically reading a sheet on which a target image is formed and generating read image data, an inspection means for inspecting the target image by comparing the read image data with answer image data at an inspection level set from among a plurality of candidate levels and generating a first inspection result, and a control means for controlling display of the inspection result on a display device, wherein the control means controls the display device to display on a screen a second inspection result obtained when the target image is inspected at one or more candidate levels different from the inspection level among the plurality of candidate levels in response to the first inspection result satisfying a predetermined condition, and resets the inspection level based on a user input. Corresponding methods and computer programs are also provided. Effect of the Invention

[0008] The present disclosure provides improved usability when setting an inspection level for inspecting an image on a sheet. [Brief description 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. [Diagram 2] FIG. 4 is a block diagram showing an example of a configuration of an external controller according to an embodiment. [Diagram 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 a configuration of a reader controller according to an embodiment. [Diagram 5] FIG. 4 is an explanatory diagram showing an example of the configuration of a job setting screen. [Figure 6] FIG. 13 is an explanatory diagram showing an example of the configuration of a correct image registration screen. [Figure 7] FIG. 13 is an explanatory diagram showing an example of the configuration of a correct image confirmation screen. [Figure 8] FIG. 13 is an explanatory diagram showing an example of the configuration of an inspection area setting screen. [Figure 9] FIG. 13 is an explanatory diagram showing an example of the configuration of an additional registration screen. [Figure 10] FIG. 13 is an explanatory diagram showing an example of the configuration of a detailed setting screen. [Figure 11] FIG. 13 is an explanatory diagram showing an example of the configuration of an examination status screen. [Figure 12] FIG. 13 is an explanatory diagram showing an example of the configuration of an examination result screen. [Figure 13] 11 is a flowchart showing an example of the flow of a correct image registration process. [Figure 14] 11 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 PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0011] <1. System Overview> FIG. 1 is a schematic diagram showing a configuration of an inspection system 1 according to an 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 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 a print job 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 in the PC 10. When a user requests printing, the printer driver generates page description language (PDL) data representing an image to be printed, and transmits a print instruction together with the generated PDL data to the external controller 50. The printer driver can display a print dialogue on the display of the PC 10 in cooperation with a job control unit 60 of the external controller 50, which will be described later, and the user can specify various control parameters related to printing and inspection in the print dialogue.

[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 called an image processing controller, a digital front end, or a print server. The configuration of the external controller 50 will be described in further detail later.

[0014] The image forming apparatus 100 is an apparatus that executes a print job to form an image on a sheet. In this embodiment, the 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 printing (quality of the image on the sheet) based on the generated read image data. Therefore, the image forming apparatus 100 may be called 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 by electrophotography. 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 sections 121Y, 121M, 121C, and 121K, an intermediate transfer body 126, a transfer section 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 a button, a numeric keypad, a touch panel, and a switch. The detailed configuration of the printer controller 200 will be described later in detail.

[0018] The image forming unit 121Y forms a yellow (Y) toner image on the intermediate transfer body 126. The image forming unit 121M forms a magenta (M) toner image on the intermediate transfer body 126. The image forming unit 121C forms a cyan (C) toner image on the intermediate transfer body 126. The image forming unit 121K forms a black (K) toner image on the intermediate transfer body 126. Since the image forming units 121Y, 121M, 121C, and 121K have the same configuration, the configuration of the image forming unit 121Y will be described as an example. The image forming unit 121Y includes a photosensitive drum 122, a charger 123, an exposure unit 124, and a developing unit 125. The photosensitive drum 122 is a drum-shaped photosensitive body having a photosensitive layer on its surface. The photosensitive drum 122 rotates in the direction of the arrow R in the figure around the drum axis. 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 here) 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 developer 125 develops the electrostatic latent image on the photosensitive drum 122 by supplying toner (yellow here) 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 the 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 state in which they are superimposed on 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, and rotates in a clockwise direction in the figure. The intermediate transfer body 126 transports the full-color toner image to the position of the transfer unit 127 (transfer nip).

[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 feeding mechanism and transported along a transport path 133.

[0020] A sheet picked up from the paper feed tray 131 or 132 is conveyed to the transfer nip in accordance with the timing when the toner image on the intermediate transfer body 126 reaches the transfer nip under the control of the printer controller 200. The transfer unit 127 transfers the toner image carried on the intermediate transfer body 126 to the sheet at the transfer nip. The fixing device 128 includes a heater and a pressure roller. The fixing device 128 heats the toner image transferred to the sheet by the heater and presses it by the pressure roller. As a result, the toner on the sheet melts and the toner image is fixed to the sheet. Although FIG. 1 shows an example in which the image forming apparatus 100 includes one fixing device 128, the image forming apparatus 100 may further include a second fixing device used, for example, to increase gloss or improve fixability.

[0021] The conveying path 133 branches into conveying paths 134 and 135 downstream of the fixing device 128. The sheet that has passed through the fixing device 128 is conveyed from the conveying path 133 to the conveying path 135. When the rear end of the sheet enters the conveying path 135, the conveying direction is reversed, and the sheet is discharged to the reader unit 150 by the 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. In 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 by the fixing device 128. The sheet with images formed on both sides is discharged to the inserter 140 by the discharge rollers 137.

[0022] <2-2.Insert> The inserter 140 includes an insert tray 141. An additional sheet to be inserted between a series of sheets on which an image is formed by the printer unit 120 is placed on the insert tray 141. When an insert function is enabled in a print job, the inserter 140 merges the additional sheet supplied from the insert tray 141 between the 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 for controlling the insertion of such additional sheets. Alternatively, the insertion of the additional sheets may be controlled by the printer controller 200 or the reader controller 250. The inserter 140 discharges 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 is 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 later in detail.

[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 lower surface of the 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 upper surface of the 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 an RGB signal value at each pixel position. The reader unit 150 discharges each sheet that has passed through the flow reading glass 154 to a 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 a sheet discharge destination in a print job, the 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 in 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 the front and back of the sheets discharged to the stack tray 171. When the stack tray 171 is not specified as a sheet discharge destination, the stacker 170 discharges each received sheet (for example, a sheet that is 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 bookbinding (e.g., saddle-stitching) on ​​a sheet or a stack of sheets received from the stacker 170. When 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. When it is specified to perform post-processing, one or more sheets are once taken into the post-processing mechanism 181, and after the specified post-processing is performed, the post-processed sheet or the 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. Instead, 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 and 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. Example of control function configuration> <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 a 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 each other via a system bus 59.

[0028] The first communication I / F 51 is an interface for the external controller 50 to communicate 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 of 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, a button, a touch panel, and a switch. The CPU (Central Processing Unit) 56 is a processing circuit that controls the overall function of the external controller 50 by executing a computer program stored in the memory 57 or the HDD 58. The memory 57 may be, for example, any combination of a RAM (Random Access Memory) and a 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 a print instruction, the issuance of a print job to the image forming apparatus 100, and the feedback of the job execution result to the user. For example, when a user instructs printing, the job control unit 60 generates input image data (RIP data) in a bitmap format by rasterizing PDL data representing an image to be printed. The job control unit 60 may further perform image processing such as color conversion, gradation correction, and binarization on the input image data. Then, the job control unit 60 outputs a print job including the generated input image data and control parameters that can be acquired via a UI such as a print dialogue to the image forming apparatus 100.

[0030] Regardless of the description here, the external controller 50 may be omitted from the configuration of the inspection system 1. When 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 in an integrated or distributed manner.

[0031] <3-2.Printer controller> Fig. 3 is a block diagram showing an example of the configuration of the printer controller 200. Referring to Fig. 3, the 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 a 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 each other 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 device of the operation panel 110. The CPU 206 is a processing circuit that controls the overall function of the printer controller 200 by executing a computer program stored in the memory 207 or the HDD 208. The memory 207 may be any combination of RAM and ROM, for example. 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 according to control parameters included in the print job. The print control unit 210 can display 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 the reader controller 250. Referring to Fig. 4, the 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 each other 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 read image data generated by the first reading sensor 153 reading the lower surface of the sheet. The image processing circuit 252 performs image processing such as ADC, color conversion, and noise removal on the read image data generated by the second reading sensor 155 reading the upper 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 the overall function of the reader controller 250 by executing a computer program 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 an inspection function is enabled in a print job, the inspection unit 260 causes the reader unit 150 to read a sheet on which an image is 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 generated by the first reading sensor 153 for the lower surface of each sheet and processed by the image processing circuit 251. In the case of double-sided printing, the inspection unit 260 further acquires read image data generated by the second reading sensor 155 for the upper surface of each sheet 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 read image data with the correct image data corresponding to a correct image (reference image) that serves as a reference for the inspection. For example, the inspection unit 260 divides the inspection target image and the correct image into a plurality of segments, and compares partial images between the inspection target image and the correct image for each segment. The inspection unit 260 may determine that there is no defect (satisfies the pass criterion) if the amount of deviation of the contents of the partial images is equal to or less than a first threshold, and determine that there is a defect (does not satisfy the pass criterion) if the amount of 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 correct image and present in the inspection target image is equal to or less than a second threshold, and determine 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 correct image, and determine whether there is a defect based on a comparison of the recognized characters. These comparison methods may be combined with each other in any manner.

[0038] In this embodiment, the inspection unit 260 inspects the image to be inspected at an inspection level set from among a plurality of candidates for the inspection level (hereinafter, referred to as candidate level). The higher (stricter) the inspection level is, the smaller the difference between the image to be inspected and the correct image can be detected as a printing defect. For example, it is assumed that the inspection level "A" is higher than the inspection level "B". In this case, the judgment threshold (for example, the above-mentioned first threshold and / or second threshold) used for inspection at the inspection level "A" is smaller than the judgment threshold used for inspection at the inspection level "B". In the following description, the inspection level is represented by an integer value, and a larger number corresponds 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 an embodiment, the inspection unit 260 may inspect whether the inspection target image includes defects (also called printing defects) within the range of each of one or more inspection areas registered in advance in association with the correct answer image. Areas not included in any of the inspection areas may be excluded from inspection. Even if there is a difference between the inspection target image and the correct answer image in an area excluded from inspection, the difference is not detected as a printing defect. In addition, when two or more inspection areas are registered in association with the correct answer 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 in the subject area and a second inspection area may be set in the background area, and a relatively high inspection level may be set in the first inspection area and a relatively low inspection level may be set in the second inspection area. The inspection area may be specified by the user using, for example, the PC 10 or the operation panel 110. In addition, the inspection unit 260 may automatically specify an area recognized by analyzing the correct answer image (for example, a face area or a person area recognized through image recognition) as the inspection area.

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

[0041] In some embodiments, printing defects detected by the inspection unit 260 may be classified into multiple defect types, which may include, for example, two or more of the following: Stains (dot-shaped stains) Streaks (linear stains) - Misalignment (displacement of printed image) Color shift (color tone deviation) - Incorrect concentration (too high concentration / too low concentration) - Image or text loss 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 inspection target image by different inspection methods for different inspection items. For example, the detection of stains can be performed based on simple pixel value comparison with a relatively small segment size, while the detection of streaks can be performed based on edge comparison together with pixel value comparison with a relatively large segment size. In addition, the inspection unit 260 can inspect two or more defect types at different inspection levels. For example, when some small stains are allowed but the occurrence of streaks is not allowed, a relatively low inspection level can be specified for stains 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 the results 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 print defect detected for each image to be inspected, and for an image to be inspected in which a print defect has been detected, the results include the type of the detected print defect and position information indicating the position of the print defect. The inspection unit 260 may record the inspection results in an inspection log stored in the memory 257 together with identification information of the image to be inspected (e.g., sheet number and front / back classification) and the inspection date and time. The inspection unit 260 may control the stacker 170 to discharge a defective sheet in which a print defect has been detected to the escape tray 172. Alternatively, the defective sheet may be discharged to the same discharge destination as the normal sheet, or the discharge position of the defective sheet may be shifted from the discharge position of the normal sheet at the same discharge destination. By shifting the discharge position, the burden of the user's work of removing the defective sheet from the stack of discharged sheets can be reduced.

[0043] <4. Example of user interface configuration> This section describes some examples of configurations of inspection-related UIs provided to a 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, a job setting screen 400 includes five setting fields 401, 402, 403, 405, and 406 for basic settings of a print job, an inspection setting section 410, and buttons 418 and 419. The setting field 401 is a field that accepts input of the number of copies to be printed. The setting field 402 is a field that accepts designation of a color mode (e.g., full color or monochrome). The setting field 403 is a field that accepts designation of a printing side (e.g., single-sided or double-sided). The setting field 405 is a field that accepts designation of a paper feed tray. The setting field 406 is a field that accepts designation of a discharge 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 for allowing 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 on, so the inspection is enabled. Other objects in the inspection setting section 410 may be operable only when the check box 411 is set to on. The preview window 412 displays a preview of a representative correct image when a correct image to be used for the inspection is registered. In the example of FIG. 5, the correct image is not registered, so the preview window 412 does not display a preview of the correct image. The button 413 is a button for calling a correct image registration function of the reader unit 150. An example of a UI related to the registration of a correct image will be described later with reference to FIG. 6 to FIG. 9. The setting field 415 is a field for receiving a designation of a discharge destination of a defective sheet (for example, the same as that of a normal sheet or an escape tray). The setting field 416 is a field that accepts the designation of the surface to be inspected (for example, only the front side, only the back side, or both sides). The designation of the print surface in the setting field 403 and the designation of the surface 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, and both sides may be inspected when single-sided printing is performed). The button 417 is a button for calling up a detailed inspection setting function. An example of a UI for detailed inspection setting will be described later with reference to FIG. 10.

[0047] The button 418 is a button for canceling the issuance of the print job and closing the job setting screen 400. The button 419 is a button for instructing the start of execution of the print job. When the user operates the button 419, the job control unit 60 issues a print job including the input image data and the 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 transmits an inspection start instruction to the reader controller 250 together with the control parameters indicating the inspection-related settings. In response to the inspection start instruction, the inspection unit 260 of the reader controller 250 executes the 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 is not started 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 independent of the job setting screen 400 (for example, callable from the job setting screen 400). Also, the inspection setting section 410 or the inspection setting screen may further include an object for receiving an instruction to print a 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. Registration of 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 correct 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 an input of the number of correct 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 correct images need to be registered. The setting field 432 is a field for receiving an input of the number of times reading is repeated for registering one correct image. For example, the inspection unit 260 may generate one correct image corresponding to the printed image by synthesizing (for example, superimposing or averaging) K read images generated by reading K sheets (K is a natural number) on which the same printed image is printed. The setting field 433 is a field for receiving a designation of the read side (for example, one side or both sides) of the correct sheet. The button 435 is a button for calling up a correct image previously registered as a correct image for a new print job. The button 438 is a button for canceling the registration of the correct image and closing the correct image registration screen 430. The button 439 is a button for instructing the start of reading of the correct answer sheet. When the user operates the 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 a 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 the page of the correct image to be confirmed to be switched. In the following description, the term "page" is used to indicate a position in a series of images (test target images or correct image) that is identified by a combination of a sheet and a face (front / back). The preview window 442 is a window in which a preview of the correct image of the page selected in the selection field 441 is displayed. 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 face. When the object 445a, 445b, or 446 is operated, the display of the preview of the correct image in the preview window 442 is switched together with the selection of the page in the selection field 441. 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, a pinch in, a pinch out, or a swipe).

[0054] The button 443 is a button for a user who judges that there is no problem with the (unregistered) correct image displayed in the preview window 442 to instruct the registration of the correct image. When the user operates the button 443, the inspection unit 260 registers the corresponding correct image in association with the page selected in the selection field 441. The button 444 is a button for a user who judges that there is a problem with the correct image (for example, due to the occurrence of a printing defect, a missing image, or a mistaken correct answer sheet) to cancel the registration of the correct image. When the user operates the button 444, the inspection unit 260 may discard the corresponding correct answer image. The button 448 is a button for collectively canceling the registration of the correct answer images generated by reading a series of correct answer sheets. The button 449 is a button for collectively instructing 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 that may be further displayed on the display when at least one correct answer image is registered. Referring to FIG. 8, the 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 allows switching of the page of the correct answer image that is the target of the setting of the inspection area. The preview window 452 is a window that displays the correct answer 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 correct answer image of the page selected in the selection field 451. When the check box 453 is off, the inspection level is not set for each inspection area for the selected correct answer image, and the inspection level can be set for the entire correct answer image. When the check box 453 is on, it is possible to set the inspection level for each inspection area for the selected correct answer image.

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

[0058] The level setting section 454a and the level setting section 454b may have the same configuration, so the level setting section 454b will be described as an example here. 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 for allowing the user to specify whether or not to enable inspection for "stains", which is one of the inspection items. The objects 455b and 455c are buttons for changing the inspection level for "stains". For example, when the user desires a detailed inspection for "stains" (when the user desires that sheets with only small stains be detected as defective sheets), the user sets the check box 455a to on and operates the object 445b to increase the inspection level. Conversely, when the user desires only a rough inspection for "stains", the user sets the check box 455a to on and operates the object 445c to decrease the inspection level. A user who does not wish to inspect for "stains" sets check box 455a to off. Check box 456a is an object for allowing 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." Such inspection level settings in level setting section 454b are applied to custom area A.

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

[0060] The button 457 is a button for canceling the setting of the inspection area and returning to the previous screen. The button 458 is a button for transitioning to a screen for additional registration of a correct image. The button 458 may be displayed on the inspection area setting screen 450 when, for example, there is a page for which the correct image is selected not to be registered on the correct image confirmation screen 440 of FIG. 7. When the user operates the button 458, the inspection unit 260 stores the setting of the inspection area and the inspection level received via the inspection area setting screen 450 in the memory 257, and then displays an additional registration screen for additional registration of the correct image on the display. The button 459 is a button for completing the registration of the correct image. When the user operates the button 459, the inspection unit 260 stores the setting of the inspection area and the 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 an alternative selection of whether to additionally register a correct image only for a specific page or to all pages for which a correct image has not been registered. When additionally registering a correct image only for a specific page, the user selects the radio button 471a, selects a target page in the setting field 472, and operates the button 473. Then, the selected page is 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. When additionally registering a correct image for all pages, the user selects the 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 sheet for additional registration. When the user operates the button 479, the inspection section 260 controls the reader unit 150 to read the correct sheet conveyed from the inserter 140 and generate read image data, and generates correct image data for additional registration based on the read image data.

[0062] While the reading of the 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 answer sheet for additional registration is completed, the inspection unit 260 displays a confirmation screen similar to that described with reference to 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 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 setting 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, 489. The check boxes 481a, 482a, and 483a are objects for allowing the user to specify whether to enable the inspection of the candidates for the inspection items "stain", "streak", and "misalignment". In the example of FIG. 10, the check boxes 481a and 482a are set to "on", and in this case, it becomes possible to enable the inspection of "stain" and "streak" in 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 "stain". Similar objects for changing the inspection level for "streak" and "misalignment" also exist. The check box 484 is an object for allowing the user to specify whether to enable the setting of the automatic inspection area for the correct image. Check box 485 is an object for allowing 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 together 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 for allowing the user to specify whether defective sheets that may be detected during inspection are to 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 of the detailed settings and closing detailed settings screen 480. Button 489 is a button for completing the change of the detailed settings. When button 489 is operated by the user, inspection unit 260 reflects the change of the detailed settings accepted via detailed settings screen 480 in the settings stored in memory 257, and closes detailed settings screen 480. The inspection-related settings accepted via 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. Display of inspection progress> 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 an inspection level set via the above-mentioned UI, 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 a display while the 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 what percentage of the total number of inspection target images has been inspected. The image window 492 is a window that displays a reduced view of the latest 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 the 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 the sheet that is transported from the inserter 140 thereafter. The button 499 is a button for interrupting the execution of a 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 a second inspection result when the inspection target image 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 the second inspection level. Then, the inspection unit 260 controls the display device to display the acquired second inspection result on the screen. As one example, the predetermined condition may include that the inspection target image is determined to include a printing defect in the first inspection result. As another example, the predetermined condition may include that the inspection target image is determined to include a printing defect multiple times consecutively in the first inspection result. As a further example, the predetermined condition may include that the number of times the inspection target image is determined to include a printing defect in the first inspection result exceeds a predetermined threshold. As yet another example, the predetermined condition may include that the inspection has reached a specific page designated in advance. The inspection section 260 can reset the inspection level from the first inspection level to any one of the second inspection levels based on a user input acquired in response to the display of such a screen.

[0070] In response to the first inspection result satisfying a predetermined condition, the inspection unit 260 provisionally obtains a second inspection result by comparing the inspection target image and 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 as 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 each other, for example.

[0071] Fig. 12 is an explanatory diagram showing an example of the configuration of the inspection result screen 500. Referring to Fig. 12, the inspection result screen 500 includes a target image window 501, an inspection 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 in which a reduced view of the inspection target image in which a printing defect is detected is displayed. A mark 506 is superimposed on the target image window 501 to indicate the location of one or more printing defects detected based on the difference between the scanned image data and the correct image data. The inspection result section 502 is a section in which information on the first inspection result at the current inspection level is written. In the example of FIG. 12, the inspection result section 502 describes the identification information of the page in which the printing defect is detected, the name of the inspection area in which the printing defect is detected, the defect type, and the position information of the printing defect. The correct image window 503 is a window in which a reduced view of the correct image used to inspect the inspection target image is displayed. The current setting section 504 is a section in which information on the current settings of the inspection area and inspection level associated with the correct image is written.

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

[0075] Preview windows 511a, 511b, and 511c respectively show the inspection results when the inspection target image is inspected for the presence or absence of streaks with the inspection levels set to "1," "2," and "3." However, 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." Also, 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 embodiment, the user input for resetting the inspection level may specify any 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 case of the user input for the buttons 512a, 512c, 522a, or 522c in FIG. 12. In another embodiment, the user input for resetting the inspection level may specify any 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 embodiments, and a user input that commonly increases or decreases the inspection level for a plurality of defect types may be adopted. A user input that commonly increases or decreases the inspection level for a plurality of inspection areas may be adopted.

[0077] The button 531 is a button for triggering re-inspection at the inspection level after the resetting. The operation of the button 531 becomes possible after at least one inspection level has been reset according to a user input. When the button 531 is operated by the user, the inspection unit 260 executes re-inspection at the inspection level after the resetting for the inspection target image in which a printing defect was once detected. If no printing defect is detected in this re-inspection, the inspection result for the inspection target image can be corrected from defective to normal. That is, the inspection result can be corrected immediately. The button 532 is a button for stopping the inspection of the subsequent inspection target image. The button 533 is a button for triggering the resumption of the inspection. When the button 533 is operated by the user, the inspection unit 260 resumes the inspection of the subsequent sheet. When the inspection level is reset, the inspection of the subsequent sheet is performed at the inspection level after the resetting.

[0078] In a modified example, the provisional result section 505 may selectively display only the second test results at a smaller number of candidate levels, instead of comprehensively displaying the second test results at all candidate levels. The inspection unit 260 may select the second test level at which the second test results should be displayed based on a user input, or may select the second test level according to a predefined condition. For example, the inspection unit 260 may determine an upper limit number of second test levels so as 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 number. In particular, when the candidate levels are multiple, the time required for generating and previewing the test results can be reduced by limiting the number of second test levels in this way. In addition, the display area can be efficiently utilized to improve the visibility of the test results.

[0079] In another variation, the provisional result section 505 may display the second inspection results only for the inspection items in which printing defects were detected, instead of displaying the second inspection results for all enabled inspection items. For example, in a case where inspection for stains and streaks is enabled, when an inspection target image is detected to include streaks but not stains, the inspection unit 260 may perform a provisional inspection at one or more second inspection levels only for streaks and display the second inspection results on the display. In this case, the inspection unit 260 may accept a user input for resetting the inspection level only for streaks. In this case, it becomes easy to optimize the inspection level for the same type of printing defect as the actually detected printing defect. In addition, the time required for generating and previewing the inspection result may be shortened, and the visibility of the inspection result 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 by the inspection system 1 in this embodiment. The correct image registration process in Fig. 13 can be started in response to, for example, operation of button 439 on correct image registration screen 430 shown in Fig. 6. In the following description, a processing step is abbreviated as 'S'.

[0081] First, in S101, the inspection unit 260 acquires settings for reading the answer sheet. The settings acquired here may include, for example, the number of correct images to be registered, the number of times to repeat reading for registering one correct image, and the designation of the reading side of the 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 the sake of simplicity, 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 answer sheet. Then, in S107, the first reading sensor 153 generates read image data. The image processing circuit 251 executes necessary image processing (for example, resolution conversion, noise removal, superimposition, and averaging) on ​​the read image data.

[0084] Next, in S109, the inspection unit 260 determines whether reading of all the correct answer sheets is completed. If there is a next sheet to be read, the process returns to S103. If reading of all the correct answer sheets is 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 of each page on the displayed correct image confirmation screen 440, and if there is no problem, instructs to register the correct image.

[0086] 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 sheet for additional registration is read. If registration of correct images for all pages is 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 answer image data. Next, in S119, the inspection unit 260 displays the inspection area setting screen 450 on the display. Then, if the user selects to customize the inspection area / inspection level (S119-YES), in S121, the inspection unit 260 accepts the setting of the inspection area and inspection level for the correct answer 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 settings related to the inspection. The settings acquired here may include, for example, the discharge destination of 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 result at a candidate level other than the inspection level when a defect is detected. In addition, in S203, the inspection unit 260 acquires registered correct answer 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 of explanation, it is assumed here 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 according to the settings acquired in S201. For example, the inspection unit 260 determines the presence or absence of 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 registered in advance in association with the correct image.

[0093] Next, in S213, the inspection unit 260 determines whether a printing defect is detected in the inspection target image. For example, when a difference exists that exceeds a threshold corresponding to a pre-set inspection level for a defect type (inspection item) for which inspection is enabled, a printing defect may be detected in the inspection target image. If a printing defect is detected, the process proceeds to S220. On the other hand, if a printing defect is not detected, the inspection target image 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 every time the inspection of one inspection target image is completed. Then, the process proceeds to S233.

[0095] In S220, the inspection unit 260 executes an inspection result display process, and causes the display to display an inspection result screen 500 showing the second inspection results at one or more candidate levels together with the first inspection result (indicating a printing defect) at the current inspection level. A detailed flow of the inspection result display process executed here will be described later in more detail. The inspection unit 260 may reset at least one inspection level based on a user input acquired via the inspection result screen 500.

[0096] The subsequent process branches depending on whether or not the user has instructed the inspection target image to be re-examined. If the user has instructed the inspection target image to be re-examined, the process returns to S211, and the inspection target image is inspected again at the inspection level after the re-setting. If the user has not instructed the inspection target image to be re-examined, the process proceeds to S233.

[0097] In S233, the inspection unit 260 discharges the sheet to a discharge destination according to the inspection result. For example, a sheet for which no printing defects are detected as a result of the inspection 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. Display of test results> FIG. 15 is a flowchart showing an example of a 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 a current inspection level. The first inspection result may include, for example, defect type and position information for each detected printing defect.

[0101] Then, 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. The second inspection results may also include defect type and location information for each detected printing defect.

[0102] Next, in S223, the inspection unit 260 causes the display to display an inspection result screen 500 showing the first inspection result and the second inspection result. For example, on the inspection result screen 500, a mark indicating the position of the printing defect detected at the current inspection level is superimposed on a reduced view of the image to be inspected based on the first inspection result. Similarly, a mark indicating the position of the printing defect detected at each candidate level is 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 to restart the inspection or to re-inspect on the inspection result screen 500 is received, the inspection unit 260 ends the display of the inspection result. After that, the process proceeds to S231 in Fig. 14, where the image to be inspected is re-inspected or the subsequent sheet is inspected.

[0105] <6. Summary> Various embodiments, examples, and modifications of the technology according to the present disclosure have been described above with reference to FIGS. 1 to 15. According to the above-described embodiment, the reading means of the inspection system optically reads a sheet on which a target image is formed, and generates read image data. The inspection means inspects the target image by comparing the read image data with the correct image data at an inspection level set from among a plurality of candidate levels, and generates a first inspection result. The control means acquires a second inspection result when the target image is inspected at one or more candidate levels different from the inspection level among the plurality of candidate levels, in response to the first inspection result satisfying a predetermined condition. Then, the control means 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 grasp how to change the inspection level from visual information on the screen displaying the inspection result, and can give an appropriate instruction to reset the inspection level to the inspection system. This improves usability when setting an inspection level for inspecting an image on a sheet.

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

[0107] In addition, 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 in parallel on the screen. Therefore, the user can intuitively understand how the number of printing defects increases or decreases when the inspection level is reset by comparing the two inspection results. This further improves usability.

[0108] In the above-described embodiment, 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 a 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 purpose of the printed matter. In another embodiment, the user input may specify a 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 specially for a limited portion that is important in the target image, 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-mentioned 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. It can also be realized 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 modifications and variations are possible 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 apparatus, 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 holding means for holding a reference image to be used for inspection; a reading means having a first reading section for reading a first surface of a sheet on which an image is formed and a second reading section for reading a second surface of the sheet; a setting means for setting an inspection level for inspection within the 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; a display means for displaying a result of the inspection by the inspection means; Equipped with The inspection means includes: inspecting a first read image of a first sheet read by the reading means in a first inspection area at a first inspection level designated by a user, and inspecting the first read image in the first inspection area at a second inspection level different from the first inspection level; the display means displays a first test result for the test at the first test level and a second test result for the test at the second test level. Inspection equipment.

2. An inspection device as described in claim 1, wherein the display means displays the first inspection result and the second inspection result on the same screen.

3. An inspection device as described in claim 2, wherein the inspection area is an area corresponding to a portion of the read image.

4. An inspection device as described in claim 3, wherein the setting means is capable of setting the inspection level in one of 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 portion of the read image.

5. An inspection device as described in Claim 4, wherein the reading means reads a sheet transported via an inserter from an image forming device that forms an image on a sheet.

6. An inspection device as described in claim 2, wherein the display means displays the first inspection result and the second inspection result in parallel on the same screen.

7. An inspection device as described in claim 1, wherein the inspection area is an area corresponding to the entire read image.

8. An inspection device as described in claim 1, wherein the inspection area is an area corresponding to a portion of the read image.

9. An inspection device as described in claim 1, wherein the inspection means performs the inspection in the first inspection area of ​​the first read image at the first inspection level to generate the first inspection result, and performs the inspection in the first inspection area of ​​the first read image at the second inspection level to generate the second inspection result without causing the reading means to read the first sheet again.

10. An inspection apparatus as described in claim 1, wherein the inspection means sets the first inspection level before the first sheet is read by the reading means, and sets the second inspection level after the first sheet is read by the reading means.

11. 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 a user input after the first sheet is read by the reading means; the inspection means performs the inspection in the first inspection area of ​​the first read image at the second inspection level to generate the second inspection result, without causing the reading means to read the first sheet again.

2. The inspection device according to claim 1.

12. An inspection device as described in claim 1, wherein the display means displays a first object on the screen to allow a user to specify the second inspection level after the first sheet is read by the reading means.

13. The second inspection level is higher than the first inspection level; The second test result detects more defects than the first test result.

2. The inspection device according to claim 1.

14. An inspection device as described in claim 1, wherein the inspection means performs the inspection in the first inspection area of ​​the first read image at the second inspection level when a defect is detected in the first inspection result.

15. An inspection device as described in claim 1, wherein the setting means is capable of setting the inspection level in one of 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 portion of the read image.

16. The inspection device according to claim 1, wherein the setting means is capable of setting a defect type specified by a user as the defect type to be detected by the inspection means.

17. The inspection device as described in claim 1, wherein the reading means reads a sheet transported via an inserter from an image forming device that forms an image on a sheet.

18. The inspection means detects defects based on a difference between the read image and the reference image, the first inspection results indicate a location of each defect detected at the first inspection level; the second inspection results indicate a location of each defect detected at the second inspection level.

2. The inspection device according to claim 1.

19. The inspection apparatus of claim 12, wherein the first object accepts user input specifying one of one or more of the second inspection levels.

20. The inspection means is capable of inspecting two or more defect types at inspection levels different from each other, the first inspection level is set for one of the two or more defect types; 2. The inspection device according to claim 1.

21. The inspection means is capable of inspecting two or more defect types at inspection levels different from each other, 2 . The inspection device 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 for the type of defect detected in the first inspection result.

22. One or more of the inspection areas are registered in association with the reference image; the inspection means inspects the read image within the range of each registered inspection area; 2. The inspection device according to claim 1.

23. The inspection apparatus of claim 22, wherein the second inspection level is set for one of one or more of the inspection areas registered in association with the reference image.

24. An inspection device as described in 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 number.

25. The inspection device described in Claim 24, wherein the upper limit number is determined based on the size of the available display area of ​​the display means.

26. An inspection device as described in 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 printing job.

27. ​​An image forming apparatus for forming an image on the sheet; An inspection device according to any one of claims 1 to 26, An inspection system including:

Images