Image forming apparatus, image forming method, and program

Abstract

To solve the problem in which: when an image defect occurs in a read correct answer image, the image defect cannot be detected, and an image in which an image defect occurs is registered as the correct answer image.SOLUTION: An image forming apparatus reads an image printed on a recording sheet, displays an image obtained by removing a defective image from the read image on a display unit, receives an instruction to use the displayed image as a correct answer image, and registers an image created from the received image as a correct answer image used for an inspection image.SELECTED DRAWING: Figure 16

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus, an image forming method, and a program. [Background technology]

[0002] In recent years, printing systems have become known that allow an inspection device to inspect sheets printed by a printing device while they are being transported. In the inspection of printed sheets, the inspection device reads an image of the printed sheet being transported and determines whether the printed sheet is normal or not by analyzing the read image. The inspection device can detect, for example, missing barcodes or ruled lines, missing images, printing defects, missing pages, color misalignment, etc.

[0003] As a method for creating a correct image (master image, reference image) to be used for image analysis, a method is known in which a printed sheet of sufficient quality is read by an inspection device as a correct image printed in advance. By acquiring the correct image using a reading sensor on the inspection device that is used in the actual inspection process, it is possible to reduce erroneous judgments in inspections caused by the accuracy of printing sheet transport and the accuracy of sensor reading.

[0004] When acquiring a correct image, the print sheet to be read must be printed with sufficient quality as a correct image and must be read correctly by the reading sensor. For example, paper dust from the print sheet may adhere to the reading sensor of the inspection device, causing streaks in the image to be read. If an image containing streaks is used as the correct image, it may be erroneously detected as a print defect even if there is no defect in the printed matter. In Patent Document 1, the correct image to be registered and a defect detection pattern are printed on different papers, the defect detection pattern is read, and the correct image is registered after confirming that there is no defect. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP2010-173289 Public Relations Summary of the Invention [Problem to be solved by the invention]

[0006] However, even if the above-mentioned streaks caused by paper dust do not occur when the defect detection pattern is read, they may occur when the correct image is read. Therefore, in Patent Document 1, when an image defect occurs in the read correct image, the image defect may not be detected. As a result, an image with an image defect may be registered as the correct image. [Means for solving the problem]

[0007] In order to solve the above problems, an image forming apparatus according to an aspect of the present invention includes a detection unit for detecting a defective image from a plurality of images read by a reading unit; Among the multiple images read by the reading unit, the detection means The image forming apparatus includes a receiving means for receiving one or more images to be used as a reference image from among the plurality of images excluding the detected defective images, a registration means for registering as a reference image one image for which an instruction to use has been received by the reception means, or an image generated from the plurality of images for which an instruction to use has been received by the reception means, and an inspection means for reading an image formed on a recording sheet using the reference image registered by the registration means and inspecting the obtained image. Effect of the Invention

[0008] According to the present invention, it is possible to reduce the effort required for selecting a correct image to be used in an inspection process. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an overall diagram of a hardware configuration of a printing system. [Diagram 2] FIG. 1 is a block diagram illustrating a system configuration of a printing system. [Diagram 3] FIG. 2 is a schematic cross-sectional view of the mechanism of the image forming apparatus. [Figure 4] 13 shows a processing flow of an external controller when registering a normal image. [Diagram 5] 13 shows the process flow of the inspection device when registering a normal image. [Figure 6] 13 shows a process flow of the inspection device when performing inspection processing. [Figure 7] 13 is an example of a display screen before a correct image is registered in the inspection device. [Figure 8] 13 is an example of a display screen when registering a correct image from an inspection device. [Figure 9] 13 is an example of a display screen while the inspection device is reading a correct image. [Figure 10] 13 is an example of a display screen after the inspection device reads a correct image. [Figure 11] 13 is an example of a display screen of the inspection device after a correct image is registered. [Figure 12] 13 is an example of a display screen when inspection settings are made from the inspection device. [Figure 13] 13 is an example of a display screen when the inspection device judges the inspection to be OK. [Figure 14] 13 is an example of a display screen when the inspection device judges the inspection to be NG. [Figure 15] 13 is an example of a display screen when an inspection job is set from an external controller. [Figure 16] 13 is a process flow of the inspection device when performing the inspection process in the second embodiment. [Figure 17] 13 is a diagram showing an example of a display screen when registering a correct image from the inspection device in the second embodiment. [Figure 18] 13 is an example of a table for managing defect information in the second embodiment. [Figure 19] 13 is an example of a display screen after the inspection device in the second embodiment reads a correct image. [Figure 20] 13 is a diagram showing an example of a pixel of a floating streak in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

[0011] In the following description, the external controller may also be called an image processing controller, a digital front end, a print server, a DFE, etc. The image forming apparatus may also be called a multifunction device, a multifunction peripheral, or an MFP. EXAMPLES

[0012] 1 is an overall diagram of the hardware configuration of an image processing system according to this embodiment. The image processing system includes an image forming apparatus 101 and an external controller 102. The image forming apparatus 101 and the external controller 102 are communicatively connected via an internal LAN 105 and a video cable 106. The external controller 102 is communicatively connected to a client PC 103 via an external LAN 104, and a print instruction is sent from the PC 103 to the external controller 102.

[0013] A printer driver having a function of converting print data into a print description language that can be processed by the external controller 102 is installed in the client PC 103. A user who performs printing can issue a print instruction from various applications via the printer driver. The printer driver transmits print data to the external controller 102 based on the print instruction from the user. When the external controller 102 receives a print instruction from the PC 103, it performs data analysis and rasterization processing, and inputs the print data to the image forming apparatus 101 to issue a print instruction.

[0014] Next, a description will be given of the image forming apparatus 101. The image forming apparatus 101 is connected to a plurality of devices having different functions, and is configured to be capable of complex printing processes such as bookbinding.

[0015] The printing device 107 forms an image on a sheet of paper conveyed from a paper feed unit at the bottom of the printing device 107 using toner. The configuration and operating principle of this printing device 107 are as follows. A beam of light such as a laser beam modulated according to image data is reflected by a rotating polygon mirror such as a polygon mirror and irradiated onto a photosensitive drum as a scanning beam. An electrostatic latent image formed on the photosensitive drum by this laser beam is developed with toner, and the toner image is transferred to a sheet of paper attached to a transfer drum. A series of image forming processes is performed sequentially for yellow (Y), magenta (M), cyan (C), and black (K) toners to form a full-color image on the sheet of paper. The sheet of paper on which the full-color image has been formed on the transfer drum is conveyed to a fixing device. The fixing device includes rollers, belts, etc., and has a heat source such as a halogen heater built into the roller, and melts the toner on the sheet of paper to which the toner image has been transferred by heat and pressure, thereby fixing the toner to the sheet of paper.

[0016] The inserter 108 is an inserter for inserting an insertion sheet, and can insert a sheet from the inserter 108 between any sheets of paper that have been printed by the printing device 107 and transported.

[0017] The inspection device 109 is a device for reading an image on the conveyed paper and comparing it with a preregistered correct image to determine whether the printed image is normal.

[0018] The large-capacity stacker 110 is a large-capacity stacker capable of stacking a large volume of sheets. The finisher 111 is a finisher that performs finishing processing on the transported sheets. The finisher 111 is capable of performing finishing such as stapling, punching, and saddle-stitching, and discharges the bound product after finishing processing to a paper discharge tray.

[0019] The positions of the inserter 108 and the inspection device 109 are not limited to the order shown in FIG.

[0020] 1 is configured such that the external controller 102 is connected to the image forming apparatus 101, but this embodiment is not limited to the configuration in which the external controller 102 is connected. That is, the image forming apparatus 101 may be connected to an external LAN 104, and print data that can be processed by the image forming apparatus 101 may be transmitted from a client PC 103 to the image forming apparatus 101. In this case, data analysis and rasterization processing are performed in the image forming apparatus 101, and print processing is executed.

[0021] FIG. 2 is a block diagram showing a system configuration of the image forming apparatus 101, the external controller 102, and the client PC 103. As shown in FIG.

[0022] First, the configuration of the printing device 107 of the image forming apparatus 101 will be described. The printing device 107 of the image forming apparatus 101 is composed of a communication I / F 217, a LAN I / F 218, a video I / F 220, a HDD 221, a CPU 222, a memory 223, an operation unit 224, and a display 225. The printing device 107 of the image forming apparatus 101 further includes a document exposure unit 226, a laser exposure unit 227, an image creation unit 228, a fixing unit 229, and a paper feed unit 230. Each of the components is connected via a system bus 231.

[0023] The communication I / F 217 is connected to the inserter 108, the inspection device 109, the large-capacity stacker 110, and the finisher 111 via a communication cable 254, and performs communication for controlling each device. The LAN I / F 218 is connected to the external controller 102 via the internal LAN 105, and performs communication of print data, etc. The video I / F 220 is connected to the external controller 102 via a video cable 106, and performs communication of image data, etc.

[0024] The HDD 221 is a storage device in which programs and data are stored. The CPU 222 controls image processing and printing based on the programs and the like stored in the HDD 221. The memory 223 stores programs and image data required when the CPU 222 performs various processes, and operates as a work area. The operation unit 224 accepts various setting inputs and operation instructions from the user. The display 225 displays setting information of the image processing device, the processing status of a print job, and the like.

[0025] The document exposure unit 226 performs a process of reading a document when using the copy function or the scan function. The document data is read by detecting an image with a CMOS image sensor or a CIS image sensor while shining an exposure lamp on the paper placed by the user. The laser exposure unit 227 is a device that performs primary charging and laser exposure to irradiate the photosensitive drum with laser light in order to transfer a toner image. In the laser exposure unit 227, first, primary charging is performed to charge the surface of the photosensitive drum to a uniform negative potential. Next, the laser light is irradiated onto the photosensitive drum by a laser driver while adjusting the reflection angle with a polygon mirror. This neutralizes the negative charge of the irradiated part, and an electrostatic latent image is formed. The image creation unit 228 is a device for transferring toner to paper, and is composed of a development unit, a transfer unit, a toner supply unit, etc., and transfers the toner on the photosensitive drum to the paper. In the development unit, negatively charged toner from a development cylinder is attached to the electrostatic latent image on the surface of the photosensitive drum to make it visible. In the transfer unit, primary transfer is performed by applying a positive potential to the primary transfer roller to transfer the toner on the photosensitive drum surface to the transfer belt, and secondary transfer is performed by applying a positive potential to the secondary transfer outer roller to transfer the toner on the transfer belt to paper. The fixing unit 229 is a device for melting and fixing the toner on the paper to the paper using heat and pressure, and is composed of a heater, a fixing belt, a pressure belt, etc. The paper feed and transport unit 230 is a device for feeding paper, and the paper feed and transport operations are controlled by rollers and various sensors.

[0026] Next, the configuration of the inserter 108 of the image forming apparatus 101 will be described. The inserter 108 of the image forming apparatus 101 is composed of a communication I / F 232, a CPU 233, a memory 234, and a paper feed control unit 235, and each of the components is connected via a system bus 236. The communication I / F 232 is connected to the printing device 107 via a communication cable 254, and communication required for control is performed. The CPU 233 performs various controls required for paper feed according to a control program stored in the memory 234. The memory 234 is a storage device in which the control program is saved. The paper feed control unit 225 controls the paper feed unit of the inserter and the feeding and transport of paper transported from the printing device 107 while controlling rollers and sensors based on instructions from the CPU 218.

[0027] Next, the configuration of the inspection device 109 of the image forming apparatus 101 will be described. The inspection device 109 of the image forming apparatus 101 is composed of a communication I / F 237, a CPU 238, a memory 239, a photographing unit 240, a display unit 241, and an operation unit 242, and each of the components is connected via a system bus 243. The communication I / F 237 is connected to the printing device 107 via a communication cable 254, and communication required for control is performed. The CPU 238 performs various controls required for inspection according to a control program stored in the memory 239. The memory 239 is a storage device in which the control program is saved. The imaging unit 240 reads an image printed on the conveyed paper with a CIS sensor based on an instruction from the CPU 238. Note that the imaging unit 240 may acquire an image by photographing an image printed on the conveyed paper with a camera. In addition, the imaging unit 240 reads not only the printed matter to be inspected, but also the printed matter that is a candidate for a correct image when the correct image is registered. Multiple copies of printouts that are candidates for the correct image are printed per page. The pixel value of the correct image is determined by averaging the pixel values ​​of pixels in corresponding positions across the multiple copies of printed pages. If 10 copies are printed, the pixel value of the correct image is determined by averaging the pixel values ​​of pixels in corresponding positions on the 10 pages (for example, the top left pixel of the image). This makes it possible to eliminate minute fluctuation components contained in the printed material that are less than the inspection accuracy as much as possible.

[0028] The CPU 238 compares the image captured by the imaging unit 240 with the correct image stored in the memory 239 (storage unit) and judges whether the printed image is normal. The display unit 241 displays the inspection results, setting screens, etc. The operation unit 242 is operated by the user and accepts instructions such as changing the settings of the inspection device 109 and registering the correct image.

[0029] Next, the configuration of the large-capacity stacker 110 of the image forming apparatus 101 will be described. The large-capacity stacker 110 of the image forming apparatus 101 is composed of a communication I / F 244, a CPU 245, a memory 246, and a paper discharge control unit 247, and each of the components is connected via a system bus 248. The communication I / F 244 is connected to the printing apparatus 107 via a communication cable 254, and communication required for control is performed. The CPU 245 performs various controls required for paper discharge according to a control program stored in the memory 246. The memory 239 is a storage device in which the control program is saved. The paper discharge control unit 247 controls the transport of the transported paper to a stack tray, an escape tray, or a subsequent finisher 111 based on an instruction from the CPU 245.

[0030] Next, the configuration of the finisher 111 of the image forming apparatus 101 will be described. The finisher 111 of the image forming apparatus 101 is composed of a communication I / F 249, a CPU 250, a memory 251, a paper discharge control unit 252, and a finishing processing unit 253, and each component is connected via a system bus 255. The communication I / F 249 is connected to the printing device 107 via a communication cable 254, and communication required for control is performed. The CPU 250 performs various controls required for finishing and paper discharge according to a control program stored in the memory 251. The memory 251 is a storage device in which the control program is saved. The paper discharge control unit 252 controls paper transport and paper discharge based on an instruction from the CPU 251. The finishing processing unit 253 controls finishing processes such as stapling, punching, and saddle stitching based on an instruction from the CPU 251.

[0031] Next, the configuration of the external controller 102 will be described. The external controller 102 is composed of a CPU 208, a memory 209, a HDD 210, a keyboard 211, a display 212, a LAN I / F 213, a LAN I / F 214, and a video I / F 215, and is connected through a system bus 216. The CPU 208 executes processes such as receiving print data from the client PC 103, RIP processing, and sending print data to the image forming apparatus 101 based on the programs and data stored in the HDD 210. The memory 209 stores programs and data required for the CPU 208 to perform various processes, and operates as a work area. The HDD 230 stores programs and data required for operations such as printing processing. The keyboard 211 is a device for inputting operation instructions for the external controller 102. The display 212 displays information such as an application executed by the external controller 102 by video signals of still images and moving images. The LAN I / F 213 is connected to the client PC 103 via the external LAN 104, and communication such as print instructions is performed. The LAN I / F 214 is connected to the image forming apparatus 101 via the internal LAN 105, and performs communication such as print instructions. The video I / F 215 is connected to the image forming apparatus 101 via a video cable 106, and performs communication such as print data.

[0032] Next, the configuration of the client PC 103 will be described. The client PC 103 is composed of a CPU 201, a memory 202, a HDD 203, a keyboard 204, a display 205, and a LAN I / F 206, which are connected via a system bus 207. The CPU 201 creates print data and executes print instructions based on a document processing program or the like stored in the HDD 203. The CPU 201 also comprehensively controls each device connected to the system bus. The memory 202 stores programs and data required for the CPU 201 to perform various processes, and operates as a work area. The HDD 203 stores programs and data required for operations such as print processing. The keyboard 204 is a device for inputting operation instructions for the PC 103. The display 205 displays information such as an application executed by the client PC 103 by video signals of still images and moving images. The LAN I / F 206 is connected to the external LAN 104, and communication such as print instructions is performed.

[0033] In the above description, the external controller 102 and the image forming apparatus 101 are connected by the internal LAN 1905 and the video cable 106, but as long as they are configured to transmit and receive data necessary for printing, for example, a connection configuration of only a video cable may be used. Also, each of the memory 202, memory 209, memory 223, memory 234, memory 239, memory 249, and memory 251 may be a storage device for holding data and programs. For example, they may be replaced by volatile RAM, non-volatile ROM, built-in HDD, external HDD, USB memory, or the like.

[0034] FIG. 3 is a cross-sectional view of the mechanism of the image forming apparatus 101. The printing device 107 is a device that forms an image to be printed on a sheet. The paper feed decks 301 and 302 can store various sheets. In each paper feed deck, only the topmost sheet of the stored sheets can be separated and transported to the sheet transport path 303. 304 to 307 are development stations that form toner images using color toners of Y, M, C, and K, respectively, to form a color image. The toner image formed here is primarily transferred to an intermediate transfer belt 308, which rotates clockwise, and the toner image is transferred to a sheet transported from the sheet transport path 303 at a secondary transfer position 309. The display device 225 displays information on the printing status and settings of the image forming apparatus 101. A fixing unit 311 for fixing the toner image to the sheet includes a pressure roller and a heating roller, and the toner is melted and pressed by the sheet passing between the rollers, thereby fixing the toner image to the sheet. The sheet that has passed through the fixing unit 311 is conveyed to a conveying path 315 via a sheet conveying path 312. If further melting and pressing are required for fixing depending on the type of sheet, after passing through the fixing unit 311, the sheet is conveyed to a second fixing unit 313 using the upper sheet conveying path. Then, after additional melting and pressing are performed, the sheet is conveyed to 315 via a sheet conveying path 314. If the image formation mode is double-sided, the sheet is conveyed to a sheet inversion path 316, and after being inverted by the sheet inversion path 316, the sheet is conveyed to a double-sided conveying path 317, where the image on the second side is transferred to a secondary transfer position 309.

[0035] The inserter 108 for inserting an insertion sheet includes an inserter tray 321, and merges a sheet fed through a sheet transport path 322 with the transport path. This makes it possible to insert a sheet at any position in a series of sheets transported from the printing device 107 and transport them to a subsequent device.

[0036] The sheet that has passed through the inserter 108 is transported to the inspection device 109. Within the inspection device 109, CIS (Contact Image Sensors) 331 and 332 (reading means) are arranged facing each other. CIS 331 is a sensor for reading the upper surface of the recording sheet, and CIS 332 is a sensor for reading the lower surface of the recording sheet. The image sensor for reading may be a line scan camera instead of a CIS. When the sheet transported to the sheet transport path 333 reaches a predetermined position, the inspection device 109 reads images of both sides of the recording sheet using the CIS 331 and 332 and determines whether the images are normal. The inspection results performed by the inspection device 109 are displayed on a display device 241.

[0037] The large-capacity stacker 110 can stack a large amount of sheets. The large-capacity stacker 110 has a stack tray 341 as a tray for stacking sheets. A sheet that has passed through the inspection device 109 is input to the large-capacity stacker 110 through a sheet transport path 344. The sheet is stacked on the stack tray 341 via the sheet transport path 344 and a sheet transport path 345. The stacker 340 further has an escape tray 346 as a paper discharge tray. The escape tray 346 is a paper discharge tray used to discharge a sheet determined to be a defective sheet by the inspection device 109. When outputting to the escape tray 346, the sheet is transported from the sheet transport path 344 to the escape tray 346 via a sheet transport path 347. When transporting the sheet to a post-processing device downstream of the large-capacity stacker 110, the sheet is transported via a sheet transport path 348. 349 is an inversion unit for inverting the sheet. This inversion unit 349 is used when stacking sheets on the stack tray 341. When stacking on the stack tray 341, the sheets are inverted once in the inversion unit 349 so that the orientation of the input sheet is the same as the orientation of the sheet at the time of output. When conveying to the escape tray 346 or a subsequent post-processing device, the sheets are discharged as is without being flipped when stacked, so the inversion operation in the inversion unit 349 is not performed.

[0038] The finisher 111 performs finishing processing on the conveyed sheets according to a function designated by the user. Specifically, the finisher 111 has finishing functions such as stapling (one-point or two-point binding), punching (two-hole or three-hole), and saddle stitching. The finisher 111 has two discharge trays 351 and 352, and outputs sheets to the discharge tray 351 via a sheet transport path 353. However, the sheet transport path 353 cannot perform finishing processing such as stapling. When performing finishing processing such as stapling, the sheets are output to the discharge tray 352 via a sheet transport path 354, and a finishing function designated by the user is executed in a processing section 355. The discharge trays 351 and 352 can be raised and lowered, and it is also possible to operate so that the discharge tray 351 is lowered and the sheets that have been subjected to finishing processing in the processing section 355 are stacked on the discharge tray 351. When saddle stitching is specified, the sheet is stapled in the center by a saddle stitching processing unit 356, and then the sheet is folded in half and output to a saddle stitching tray 358 via a sheet transport path 357. The saddle stitching tray 358 is configured as a belt conveyor, and the saddle stitched bundle loaded on the saddle stitching tray 358 is transported to the left side.

[0039] The inspection device 109 inspects the sheet image printed by the printing device 107 according to preset inspection items. The sheet image is inspected by comparing the printed sheet image with a preset correct image. Image comparison methods include comparing pixel values ​​for each image position, comparing object positions by edge detection, and extracting character data by OCR (Optical Character Recognition). Inspection items include misalignment of print position, image color, image density, streaks and blurs, printing omissions, etc.

[0040] Hereinafter, the registration process of the correct image and the image inspection process flow will be described with reference to Figs.

[0041] 4A is a flowchart showing the flow of processing performed by the external controller 102 when registering a correct image. A program for executing the flowchart of FIG. 4A is stored in the HDD 210, read into the memory 209, and executed by the CPU 208.

[0042] In S4001, the external controller 102 determines whether a print instruction for a print job for N copies has been received. If a print instruction for N copies has been received in S4001, the process proceeds to S4002, where the external controller 102 inputs print data for N copies to the printing device 107 and instructs it to execute printing.

[0043] 4B is a flowchart showing the flow of the process performed by the printing device 107 when registering a correct image. A program for executing the flowchart of FIG. 4B is stored in the HDD 221, read into the memory 223, and executed by the CPU 222.

[0044] In S4003, the printing device 107 waits to receive a print instruction from the external controller 102. If a print instruction from the external controller 102 is received in S4003, the process proceeds to S4004, where the printing device 107 prints the job received from the external controller 102. The job received from the external controller 102 includes information on the paper feed destination and paper discharge destination in addition to image data. The printing device 107 controls the inserter 108, inspection device 109, large capacity stacker 110, and finisher 111 via the communication cable 254 in accordance with the content of the job received from the external controller 102.

[0045] 5 is a flowchart showing the flow of the process performed by the inspection device 109 when registering a correct image. A program for executing the flowchart in FIG.

[0046] In S501, the inspection device 109 acquires print settings. The setting values ​​acquired in S501 include the number of sheets of paper per copy, the sides to be inspected, and further, the number of images per sheet of paper whose pixel values ​​are to be averaged to create a correct image. In S502, the inspection device 109 waits for a sheet of paper to be transported to the inspection device 109. If a sheet of paper has been transported in S502, the process proceeds to S503, where the image of the sheet is read using the CIS 231 and CIS 232, and stored in the memory 239 of the inspection device 109. Next, in S504, the inspection device 109 determines whether images for the number of sheets of paper acquired in S501 have been read. If image reading for the number of sheets of paper has not been completed in S504, the process proceeds to S502.

[0047] In S505, a preview image is generated for previewing the image read in S503 on the display unit 241 of the inspection device 109, and in S506, display control is performed to display the image on the display unit 241 together with a UI screen. Details of the UI screen displayed at this time will be described later with reference to FIG. 10. In S507, it is determined whether or not it has been accepted from the UI that all read images should be used as correct images. If all read images have been accepted, the process proceeds to S508, where a correct image is generated by averaging the pixel values ​​of pixels at corresponding positions between multiple printed pages, and this flow ends.

[0048] If some of the scanned images are not accepted as the correct images in S507, it is determined in S509 whether or not an additional image is selected on the UI screen. If an additional image is selected, the process proceeds to S501. If not, the process proceeds to S508. The UI screen display in S509 will be described later with reference to FIG. 11.

[0049] 6 is a flowchart showing the flow of the process performed by the inspection device 109 when performing the inspection process. A program for executing the flowchart of FIG.

[0050] In S601, the inspection device 109 judges whether an inspection end instruction has been received. When the inspection end button 1303 in Fig. 13 is selected, S601 is judged as Yes. When an inspection end instruction is received in S601, the processing of the inspection device 109 is terminated. When an inspection end instruction has not been received in S601, the process proceeds to S602.

[0051] In S602, it is determined whether or not paper has been transported to the inspection device 109. If paper has not been transported in S602, the process proceeds to S601. If it is determined in S602 that paper has been transported, the process proceeds to S603. In S603, an image of the paper is read using CIS 231 and CIS 232, and is stored in memory 239 of the inspection device 109. Here, the stored image is displayed on display unit 1301 in FIG. 13.

[0052] Next, in S604, the inspection device 109 compares the image read in S603 with a correct image. The correct image is based on the settings registered for the inspection device 109 from button 703 in FIG. 7. The items compared in S604 are the inspection level set in 1201 in FIG. 12 and the items by inspection type set in 1202. Next, the process proceeds to S605, where a determination is made as to whether the image is normal or defective based on the comparison with the correct image in S604. In the process of S605, it is determined whether the image quality of the read image satisfies the image quality of the correct image.

[0053] If it is determined in S605 that the image is normal (inspection OK), the process proceeds to S606, and the inspection result is displayed on the display unit 241 of the inspection device 109 to indicate that the inspection result is OK. Fig. 13 is an example of a screen displayed in S606.

[0054] Next, the process proceeds to S607, where the inspection device 109 instructs the printing device 107 to discharge the printed sheet to the stack tray 341 of the large-capacity stacker 110. The discharge destination here is the discharge destination set in the setting unit 1503 in Fig. 15. Based on the instruction, the printing device 107 instructs the inspection device 109 to discharge the printed sheet to the stack tray 341. Next, the process proceeds to S601 to continue.

[0055] If it is determined in S605 that the image is defective (inspection NG), the process proceeds to S608, and the display unit 241 of the inspection device 109 displays that the inspection result is NG. FIG. 14 is an example of a screen displayed in S608. Next, the process proceeds to S609, and the inspection device 109 instructs the printing device 107 to discharge the printed sheet to the escape tray 346 of the large-capacity stacker 110. The discharge destination here is the discharge destination for when the inspection is NG, which was set in the setting unit 1503 in FIG. 15. Based on the instruction, the printing device 107 instructs the inspection device 109 to discharge the sheet to the escape tray 346. Next, the process proceeds to S601, and processing continues.

[0056] 7 to 15 are examples of display screens displayed on the display unit 241 of the inspection device 109, and are displayed based on instructions from the CPU 238 of the inspection device 109. FIG.

[0057] Fig. 7 is an example of a screen displayed on the display unit 241 of the inspection device 109 when the inspection device 109 is started up. Display unit 701 displays a message (701) indicating that a correct image has not been registered and therefore that a correct image must be registered in order to start inspection. If a correct image has already been registered, a message is displayed indicating that inspection can start. Display unit 702 displays a registered correct image (702). In Fig. 7, a correct image has not been registered and therefore a message is displayed indicating that the image is not registered. In addition to the correct image, area 702 may also display information related to inspection settings, such as partition paper settings.

[0058] Button 703 is a button for calling up a registration screen for a correct image. The correct image is an image to be compared with an image read by the inspection device 109, and an image read from a printed sheet that has been previously determined to be normal by visual inspection or by the inspection device 109 is used. Button 706 is a button for calling up an inspection setting screen. The inspection items and inspection accuracy (how much difference from the correct image is required to determine that an image is defective) are set according to the user's inspection purpose. Button 707 is a button for instructing the start of inspection. When inspection starts, the inspection device 109 begins inspecting the sheet image sent to it.

[0059] Fig. 8 is an example of a screen displayed on the display unit 241 of the inspection device 109 when registering a correct image. The display screen of Fig. 8 is displayed when the button 703 of Fig. 7 is selected. A setting unit 801 is a setting unit for setting the number of sheets of paper per copy of the print job to be inspected. In the case of a print job of two or more sheets per copy, the inspection device 109 can register multiple images as correct images.

[0060] The setting unit 802 is a setting unit for setting the side to be inspected. It can be set whether the inspection device 109 will inspect both sides, only the front side, or only the back side. Even if the printing is on one side, it may be set to inspect both sides to check that there is no dust on the non-printed side. The button 803 can set how many sheet images are acquired and averaged to generate a correct image. The button 804 is a button for instructing the registration of the correct image. After pressing the button 804, the inspection device 109 reads the image of the paper on which the correct image is printed that has flowed through, and registers it as the correct image. It is to be noted that the correct image data may be transmitted from the PC 103 to the external controller 102, and the inspection device 109 may read the correct image printed by the printing device 107, or the paper on which the correct image is printed may be inserted from the inserter 108 and read by the inspection device 109.

[0061] Fig. 9 is an example of a screen displayed on the display unit 241 of the inspection device 109 while a correct image is being read. Fig. 9 is displayed when button 804 in Fig. 8 is pressed. This screen is displayed until the reading of the number of sheets set in setting units 801 and 803 is completed. Button 901 is a button for instructing to stop reading of the correct image. When button 901 is pressed, the display returns to the display screen of Fig. 7 without registering the correct image.

[0062] FIG. 10 is an example of a screen displayed on the display unit 241 of the inspection device 109 after the reading of the correct image is completed. The display unit 1001 displays a preview image of the print sheet read by the inspection device 109. When there are multiple preview images, the image to be displayed can be switched by using the switch button 1002, and when inspecting both sides, the front and back, the front and back can be switched by using the switch button 1003. In addition, in order to check whether the read image contains dust streaks or the like, the image as a whole or in details can be checked by using the image enlargement / reduction button 1004. In addition, when the image movement button 1009 is instructed, the image can be enlarged and then the displayed area can be moved. Note that each of the operation buttons 1002, 1003, 1004, and 1009 is an example, and gesture operations such as flick, pinch, and swipe may be assigned to each operation without displaying these operation buttons.

[0063] The button 1005 is a button for instructing that the currently displayed image is used as a candidate image for the correct answer image after the read image of the display unit 1001 is confirmed. When the button 1005 is pressed for each acquired image, the average value of pixels at corresponding positions between the selected multiple images is calculated, and the correct answer image is generated. The button 1006 is a button for instructing that the currently displayed image is not used as a candidate image for the correct answer image, that is, not used for averaging processing. When the button 1006 is pressed for each acquired image, the image is discarded as it is and is not used for generating the correct answer image. Note that, when only one image is selected to be used as the correct answer image, the selected image is registered as the correct answer image. Also, when multiple images are selected to be used as the correct answer image, a main image may be selected from the selected multiple images, and a process of generating the correct answer image may be performed so that the weight of the selected main image is increased.

[0064] A button 1007 is a button for instructing to use all acquired images as a correct image at once, and a button 1008 is a button for instructing to discard all acquired images and not use them for generating a correct image. When the use all button 1007 is pressed, or when the use button 1005 or the do not use button 1006 is selected for all acquired images, the display screen of FIG. 11(a) is displayed.

[0065] Fig. 11(a) is an example of a screen displayed after the correct image is acquired. Compared to the display screen before the correct image is acquired in Fig. 7, the display unit 701 displays that the correct image has been registered. In addition, the registered correct image is displayed on the display unit 702. Note that the correct image displayed here is generated by averaging pixel values ​​at corresponding positions of multiple sheet images read by the CIS 331, 332.

[0066] Button 1101 is a button for clearing the registered correct image. When the correct image is cleared, the display screen of FIG. 7 is returned to. Button 1102 is a button for additionally registering a correct image. In FIG. 10, if some acquired images have been discarded but additional correct image candidates are to be acquired, pressing button 1102 makes it possible to acquire additional images. Pressing button 1102 advances to the display screen of FIG. 11(b).

[0067] FIG. 11(b) is an example of a screen for setting additional registration of a correct image. An additional page specification button 1101 is a button for specifying a page to be additionally acquired. An individual page addition button 1102 is a button for instructing that the page specified in 1101 be additionally acquired. An all pages batch addition button 1103 is a button for instructing that all pages be additionally acquired at once. A display unit 1104 displays the additionally acquired pages specified in 1102 and 1103. An additional number specification button 1105 is a button for specifying how many images to acquire for each page specified for additional acquisition. A start acquisition button 1106 is a button for starting additional acquisition. When button 1106 is pressed and acquisition of the specified number of images is completed, the display screen of FIG. 10 is displayed.

[0068] Fig. 12 is an example of a screen displayed on the display unit 241 of the inspection device 109 when making inspection settings. The display screen of Fig. 12 is displayed when button 706 in Fig. 7 is pressed. A setting unit 1201 is a setting unit for setting the inspection level. The accuracy of inspection can be changed by setting the setting unit 1201. The higher the level of inspection accuracy, the more likely the inspection device 109 is to determine that even a slight difference between a correct image and a read image is a defective image.

[0069] The setting section 1202 is a setting section for setting the inspection type. It is possible to set the inspection items according to the user's inspection purpose. Fig. 12 shows that the position, color tone, streaks, and omissions are inspected, but the density is not inspected. Note that the inspection type in this embodiment is just an example.

[0070] FIG. 13 is an example of a screen displayed on the display unit 241 of the inspection device 109 after inspection has started. The display screen of FIG. 13 is displayed when button 707 in FIG. 7 is pressed. Display unit 1301 displays an image of the print sheet last read by the inspection device 109. Display unit 1302 displays the judgment result obtained by comparing the read image in 1301 with the correct image. In the example of FIG. 13, since the image has been judged to be normal, OK is displayed. Button 1303 is a button for instructing the end of inspection. When button 1303 is pressed, the inspection device 109 ends the inspection process and returns to the display screen of FIG. 7.

[0071] Fig. 14 is an example of a screen when the last scanned image is judged to be a defective image. As a result of comparing the scanned image 1301 with the correct image, it is judged to be a defective image, and therefore, the display unit 1302 displays "NG" along with the cause and location of the NG judgment. Fig. 14 shows that the image was judged to be a defective image because a streak 1405 was detected.

[0072] Fig. 15 is an example of an inspection job setting screen displayed on the display 212 of the external controller 102. Figs. 7 to 14 are example screens for setting inspection for the inspection device 109, but instructions to feed the inspection device 109 with a printed sheet of a correct image or a printed sheet to be inspected are issued from the external controller 102. Note that the above-mentioned inspection settings may also be made from the display unit 241 of the inspection device 109.

[0073] The setting unit 1501 is a setting unit that sets the number of copies of a job. In FIG. 15, a setting is made to print 1000 copies of a job. In the example of FIG. 15, one copy is one page, and one job consists of 1000 copies. As another example, one copy may have multiple pages. The setting unit 1503 is a setting unit that sets the paper discharge destination of the inspection job. Here, a large-capacity stacker is set as the paper discharge destination, and an escape tray is set as the paper discharge destination for discharge when an image is determined to be defective during inspection. In addition to this setting, for example, the paper discharge when the inspection is OK and when the inspection is NG may be set to the same tray. In this case, the printed sheets that are NG are manually removed later based on a list of inspection results (not shown). Alternatively, when the printed sheets are discharged to the same tray, the OK and NG sheets may be discharged at different positions, and the NG printed sheets may be removed later.

[0074] Buttons 1504 and 1505 are buttons for instructing to print only N copies of the inspection job. After instructing the inspection device 109 to start registering the correct image with the button 803 in FIG. 8, when the buttons 1504 and 1505 of the external controller 102 are used to instruct to print N copies of the inspection job, the printing process by the printing device 107 and the reading of the correct image by the inspection device 109 are performed. Note that, other than this embodiment, the inspection device 109 may be configured to automatically instruct the external controller 102 to print N copies of the inspection job via the communication cable 254 and the internal LAN 105 at the same time that the button 803 in FIG. 8 is pressed. Similarly, when the correct image is additionally acquired in FIG. 11, the inspection device 109 may be configured to instruct the external controller 102 to additionally print a specific page at the same time that the button 1106 is pressed.

[0075] The button 1508 is a button for instructing the start of printing of the inspection job. When the start of printing is instructed by selecting the button 1508, the external controller 102 inputs the inspection job to the printing device 107 based on the settings in FIG. 15. After selecting the button 707 in FIG. 7 to instruct the inspection device 109 to start inspection, the button 1508 instructs the external controller 102 to start printing of the inspection job. As a result, the external controller 102 inputs print data to the printing device 107 and instructs the printing device 109 to transport the printed print sheet to the inspection device 109. When the print sheet is transported, the inspection device 109 reads an image of the print sheet and performs inspection processing. Note that, apart from this embodiment, a configuration may be adopted in which, when the button 1508 is pressed to instruct the start of printing of the inspection job, the external controller 102 instructs the inspection device 109 to start inspection. At this time, the inspection device 109 may notify the external controller 102 of whether or not a correct image has been registered, so that the external controller 102 does not start printing if a correct image has not been registered.

[0076] As described above, according to this embodiment, when registering a correct image, the image read by CIS 331 and CIS 332 can be previewed on the UI screen. This allows the user to not only visually check the print sheet, but also to check whether the correct image has been correctly read by CIS 331 and CIS 332 and decide whether to adopt it as a correct image candidate. EXAMPLES

[0077] In the first embodiment, a preview of the correct image can be displayed on the UI screen when the correct image is registered, and the user can check for himself whether the correct image has been read correctly. However, it takes time for the user to check the preview for all correct images for reading errors caused by streaks caused by paper dust, etc.

[0078] Therefore, in this embodiment, image processing is used to detect whether a reading error has occurred when reading a correct image with CIS 331 and CIS 332. A correct image detected as having a reading error is automatically removed from the preview display, thereby realizing a device that allows a user to register a correct image more easily.

[0079] The details of the embodiment of the device will be described below. Note that the description of the configuration and processing that are the same as in the first embodiment will be omitted, and only the configuration and processing that are unique to this embodiment will be described.

[0080] This embodiment differs from the process flow of the inspection device when registering a correct image in Fig. 6 described in the first embodiment. In this embodiment, the process flow of the inspection device 109 when registering a correct image is shown in Fig. 16. Fig. 16 is a flowchart showing the process flow performed by the inspection device 109 when performing inspection processing. A program for executing the flowchart in Fig. 16 is stored in the memory 246, and is executed by the CPU 238 of the inspection device 109.

[0081] In S1601, the inspection device 109 acquires print settings. The settings acquired in S1601 include the number of sheets per copy, the side to be inspected, and how many images per sheet to average to create a correct image, as shown in FIG. 17. In addition, it is possible to set whether to automatically exclude a scanned image from registration of a correct image when a streak is included in the scanned image. In addition, at the time of feedback from S1610 described later, the number of sheets to be printed is determined according to the number of scanned images already set to be used in S1610, and the number of sheets to be printed is the number that is insufficient for the number of registered correct images. In addition, in the process described below, when a streak is included in a scanned image, the scanned image is automatically excluded from the candidates for registration of a correct image. In the case of the setting not to exclude, the process is the same as that of the first embodiment.

[0082] Next, in S1602, the inspection device 109 waits for the paper to be conveyed to the inspection device 109. If the paper is conveyed in S1602, the process proceeds to S1603, where the image of the paper is read using the CIS 331 and CIS 332, and stored in the memory 239 of the inspection device 109. In S1604, the inspection device 109 applies a defective image detection process to the read image stored in the memory 239, and generates defect information. An example of a defect targeted in the defective image detection is a floating streak or a fixed streak caused by paper powder or the like. FIG. 20(a) shows an example of an image caused by a floating streak, and FIG. 20(b) shows a vertical line on a document. Note that an algorithm for detecting floating streaks may be a known technique. As an example, a filter process is performed on the read image to detect a vertical line of an expected streak width. Next, the amount of change in luminance value between the detected vertical line and surrounding pixels in the main scanning direction and the amount of change in luminance value between the detected vertical line and surrounding pixels in the sub-scanning direction are calculated. From the calculation result and the continuity in the sub-scanning direction, it is possible to determine whether the pixel is a streak pixel.

[0083] 18 is a table for managing defect information, where the defect information is a flag managed for each scanned image, and in the case of an image in which streaks have occurred due to paper dust or the like during scanning, the flag is set to 1. However, this is just one example, and a flag may be assigned to each piece of image information by utilizing the header area of ​​the image information, etc.

[0084] Returning to the explanation of FIG. 16, in S1605 the inspection device 109 acquires defect information of the read image and determines whether it is a defective image. If it is a defective image, the process proceeds to S1607. If it is not a defective image, the process proceeds to S1606. In S1606, a preview image is generated on the display unit 241 of the inspection device 109 to display a preview of the image read in S1603. Next, in S1607 the inspection device 109 determines whether it has read images for the number of sheets acquired in S1601. If in S1607 reading images for the number of sheets has not yet been completed, the process proceeds to S1602.

[0085] In S1608, the inspection device 109 generates a UI screen including the preview image generated in S1606, and displays it on the display unit 241. Details of the UI screen displayed at this time will be described later with reference to FIG. 19. In S1609, the inspection device 109 determines whether or not an instruction has been given on the UI as to whether or not to use all the read images as correct images. If an instruction has been given as to whether or not to use all the read images, the process proceeds to S1610. If not, the process proceeds to S1609.

[0086] In S1610, the inspection device 109 judges whether the number of scanned images set to be used on the UI has reached the number of acquired correct images. If the number of scanned images set to be used has reached the number of acquired correct images, the process proceeds to S1611, where a correct image is generated by averaging the scanned images, and the flow ends. If the number of scanned images set to be used by the inspection device 109 has not reached the number of acquired correct images in S1610, the process proceeds to S1601. Note that, although the inspection device 109 is configured to enter a flow for additionally printing the missing image upon the judgment in S1610, the inspection device 109 may immediately additionally print the missing image if the image is judged to be defective in S1605. In addition, the inspection device 109 may control the printing of printed matter determined to be defective in the defective image detection to a different paper output tray from that of printed matter determined to be normal. In this way, the correlation with the preview screen displayed for specifying whether or not to use the scanned image, which will be described later, is high, and the inspection device 109 can be more intuitively understood.

[0087] FIG. 19 is an example of a screen displayed on the display unit 241 of the inspection device 109 after the reading of the correct image is completed. The display unit 1001 displays a preview image of the print sheet read by the inspection device 109. The images displayed here are different from the first embodiment in that they are images excluding images determined to be defective images by defective image detection. The preview images are image 1901, image 1902, and image 1903. As an example, a configuration is shown in which three preview images can be displayed simultaneously, but this is not limited to this. 1901 is a preview image of the first printed matter. 1902 is a preview image of the second printed matter. 1903 is a preview image of the fourth printed matter. This is an example of a case in which the third printed matter is determined to be a defective image due to the occurrence of floating streaks or the like during reading. Note that an information display unit 1910 is provided, and information on the read images that are automatically excluded from candidates for the correct image by defective image detection is displayed.

[0088] Buttons 1904 to 1909 are buttons for instructing to use the currently displayed image as a candidate image for the correct answer image after checking the read image on the display unit 1001. The instruction buttons 1904 and 1905 are used to instruct whether to use the preview image 1901 as a candidate image for the correct answer image. Similarly, instruction buttons 1906 and 1907 are used for the preview image 1902, and instruction buttons 1908 and 1909 are used for the preview image 1903. The images for which the use buttons 1904, 1906, and 1908 are pressed are averaged to generate a correct answer image. The images for which the non-use buttons 1905, 1907, and 1909 are pressed are discarded as they are and are not used as the correct answer image. Note that for images for which neither the use button nor the non-use button is selected, a correct answer image is generated according to a default setting (for example, use).

[0089] When the use / non-use designation is specified for all the preview images that can be displayed, the display screen of Fig. 11 will be displayed. Note that Fig. 19 displays the scanned candidate correct images one by one, but as a confirmation method, an averaged correct image may be displayed and confirmed, or both may be displayed.

[0090] As described above, according to this embodiment, defective images are detected from the images read by the CIS 331 and CIS 332 when the correct image is registered, and defective images that occur during reading can be excluded from the preview image. This can reduce the user's confirmation effort.

[0091] (Other embodiments) The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments 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. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

Claims

1. A detection means for detecting a defective image from a plurality of images read by the reading unit; a receiving means for receiving one or more images to be used as a reference image from among the plurality of images read by the reading unit, excluding the defective image detected by the detection means; a registration means for registering, as a reference image, one image for which an instruction to use is received by the reception means, or an image generated from a plurality of images for which an instruction to use is received by the reception means; an inspection means for reading an image formed on a recording sheet by using the reference image registered by said registration means, and inspecting the image thus read.

2. The inspection device according to claim 1, characterized in that the registration means calculates an average value of pixel values ​​of pixels at corresponding positions of multiple images for which instructions to use have been received by the reception means, and registers the reference image generated by said calculation.

3. 2. The inspection device according to claim 1, wherein the reading unit is a CIS image sensor.

4. 2. The inspection device according to claim 1, wherein the reading section reads an image printed on a printed recording sheet.

5. 2. The inspection device according to claim 1, wherein the inspection means judges the image quality of the printed image.

6. The inspection device described in claim 1, characterized in that depending on the number of defective images detected by the detection means, additional images are printed on a recording sheet, the reading unit reads the images printed on the recording sheet, the images read by the reading unit are displayed on a display unit, and the acceptance means accepts an image to be used as a reference image.

7. The inspection device described in claim 2, characterized in that depending on the number of images not to be used as reference images accepted by the acceptance means, additional images are printed on a recording sheet, the images printed on the recording sheet are read by the reading unit, the images read by the reading unit are displayed on a display unit, and the acceptance means accepts the images to be used as reference images.

8. A detection step of detecting a defective image from the plurality of read images; a receiving step of receiving one or more images to be used as a reference image from among the plurality of images read out, excluding the defective image detected by the detecting step; a registration step of registering, as a reference image, one image for which an instruction to use the image is received in the receiving step, or an image generated from a plurality of images for which an instruction to use the image is received in the receiving step; an inspection step of reading an image formed on a recording sheet using the reference image registered in said registration step and inspecting the resulting image.

9. The inspection method according to claim 8, characterized in that the registration step calculates an average value of pixel values ​​of pixels at corresponding positions of multiple images for which instructions to use have been received in the reception step, and registers a reference image generated by said calculation.

10. 9. The method of claim 8, wherein the inspecting step determines the image quality of the printed image.

11. The inspection method according to claim 8, characterized in that, depending on the number of defective images detected by the detection step, an additional image is printed on a recording sheet, the image printed on the recording sheet is read, the read image is displayed on a display unit, and an image to be used as a reference image is accepted by the acceptance step.

12. The inspection method described in claim 9, characterized in that, depending on the number of images that are not used as reference images received in the reception step, additional images are printed on a recording sheet, the images printed on the recording sheet are read, the read images are displayed on a display unit, and the images to be used as reference images are received in the reception step.

13. A program for causing a computer to function as each of the means of the inspection device according to any one of claims 1 to 7.

Images