Image processing system, control method thereof, inspection device, and program

Abstract

To solve the problem in which: deviation of a main scanning position of a recording material leads to a determination that defects occur in different parts or occur unexpectedly even if the defects occur in a single part.SOLUTION: A printing system has a printer, and an inspection device that reads and inspects an image on a recording material formed by the printer. The inspection device reads the image formed by the printer and acquires it as an inspection image, and compares the inspection image with a reference image to inspect the inspection image. The inspection device acquires, from the printer, relevant information on a main scanning position relevant to the image formation in the printer, extracts the feature quantity of defects obtained in the inspection by using the relevant information on the main scanning position, and specifies a portion of the printer that is the cause of the defects based on the extracted feature quantity.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to Image Processing system and how to control it , Inspection equipment reference and programs. [Background technology]

[0002] There is a technology for diagnosing failures in image forming devices. Patent Document 1 describes a technology for identifying the cause of an image defect using the feature amount of a defective image. According to this technology, if a tilt occurs during paper transport, the feature amount may not be extracted accurately, so the tilt during paper transport is corrected to extract the feature amount.

[0003] In a fault diagnosis technique for diagnosing a fault in an image forming apparatus, it is required to stably identify the cause of an image defect that occurs in order to perform a diagnosis more accurately. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-29794 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, there are cases where features cannot be accurately extracted other than the inclination during paper transport. Between pages, the passing position of the recording material in the main scanning direction relative to the parts may shift due to paper transport misalignment, paper reciprocating control (hereinafter, reciprocating) for suppressing damage to the fixing and transfer member caused by the paper edge, and image memory measures for the fixing and transfer member. When such a shift occurs, the main scanning positions of the parts and the recording material do not match. Streaks, dots, and chips caused by the parts occur at the same main scanning position. However, during inspection, a read image based on the paper corner of the recording material is used to determine the main scanning position from the left edge of the image, so a shift occurs in the main scanning position where a defect occurs. Due to such a shift in the main scanning position, even if the defect is caused by the same part, it is determined that the defect is caused by a different part or a sudden defect. Such erroneous determination could also occur in the technology of the above-mentioned Patent Document 1.

[0006] An object of the present invention is to solve at least one of the problems of the above-mentioned conventional techniques.

[0007] An object of the present invention is to provide a technique for detecting defects in an image with high accuracy and stably identifying the cause of the defect. [Means for solving the problem]

[0008] In order to achieve the above object, an image processing system according to an aspect of the present invention has the following configuration: An image processing system having a printing device, a reading device, and an inspection device, a reading unit that reads, by the reading device, a printed matter on which an image is printed by the printing device on a recording material; an acquisition unit for acquiring an amount of misalignment of a recording material in a direction perpendicular to a conveyance direction of the recording material used for printing by the printing device; a detection means for detecting an image defect included in the image read by the reading means using the inspection device; a diagnostic means for diagnosing a defective part of the printing device based on a result of detection by the detection means, The diagnosing means diagnoses the defective portion based on a detection result of an image defect included in a detection target area determined based on the amount of deviation acquired by the acquiring means. death, The detection means determines a detection target area on the second page based on the position of the image defect on the first page and the amount of deviation. The present invention is characterized by the above. Effect of the Invention

[0009] According to the present invention, it is possible to detect defects in an image with high accuracy and to stably identify the cause of the defect.

[0010] Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same reference numerals are used to designate the same or similar components throughout the drawings. [Brief description of the drawings]

[0011] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. [Figure 1] 1 is a diagram showing an example of a network configuration including a printing system (image processing system) according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view illustrating an example of a hardware configuration of an image forming apparatus according to an embodiment. [Diagram 3] FIG. 4 is a schematic diagram illustrating laser exposure to a photoconductor in an image forming station. [Figure 4] 5 is a schematic diagram illustrating the relationship between a photoconductor, a laser, and a fixing unit in the image forming station. [Diagram 5] FIG. 2 is a block diagram illustrating a schematic functional configuration of an image forming apparatus, an external controller, and a client PC according to the embodiment. [Figure 6] 5 is a flowchart for explaining a printing operation executed by a printing module and a procedure of a defect inspection process for a printed material executed by an inspection module according to an embodiment. [Figure 7] 11A and 11B are diagrams for explaining an example of filter processing for emphasizing a specific shape. [Figure 8] 4 is a flowchart for explaining the procedure of image diagnosis processing according to the first embodiment. [Figure 9] FIG. 13 is a diagram showing an example in which defects that occur periodically in the sub-scanning direction cause misalignment in the main scanning position between pages during inspection. [Figure 10] 9 is a flowchart for explaining the defect feature extraction process in S815 following the main scanning position related information acquisition process in S814 of FIG. 8 by the inspection module according to the first embodiment. [Figure 11] 11A and 11B are diagrams for explaining an example of setting search conditions by acquiring a laser writing start position. [Figure 12] 10A to 10C are diagrams for explaining misalignment of a sheet relative to a reciprocating width according to the first modified example of the first embodiment. [Figure 13] 11 is a flowchart for explaining a process of performing image diagnosis processing using an actual image of a user according to Modification 2 of the first embodiment. [Figure 14] 10 is a flowchart illustrating a procedure for extracting a periodicity feature according to the second embodiment. [Figure 15] 13 is a diagram showing an example in which the laser writing position is obtained as related information of the main scanning position, and the period information is used to set the period generation range in the second embodiment. FIG. [Figure 16] 6 is a diagram showing an example of a relationship between parts of a print module and period information thereof; [Figure 17] 11 is a flowchart illustrating the procedure of a continuity feature extraction process according to the third embodiment. [Figure 18] 13A to 13C are schematic diagrams showing an example in which a streak-shaped defect that occurs continuously at the same main scanning position on a part between pages is shifted in the main scanning position during inspection, and the continuity feature extraction process according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiments of the present invention 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.

[0013] 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.

[0014] FIG. 1 is a diagram showing an example of a network configuration including a printing system (image processing system) according to an embodiment of the present invention.

[0015] This printing system 100 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.

[0016] The client PC 103 can issue a print instruction to the external controller 102 via the external LAN 104. A printer driver having a function of converting image data to be printed into a page description language (PDL) that can be processed by the external controller 102 is installed in the client PC 103. A user who wishes to print can issue a print instruction from various applications installed in the client PC 103 via the printer driver by operating the client PC 103. The printer driver transmits PDL data, which is print data, to the external controller 102 based on a print instruction from the user. When the external controller 102 receives the PDL data from the client PC 103, it analyzes and interprets the received PDL data. Then, based on the result of the interpretation, it performs a rasterization process, generates a bitmap image (print image data) with a resolution matching the image forming apparatus 101, and issues a print instruction by inputting a print job to the image forming apparatus 101. The resolution of an image formed by the image forming apparatus 101 is usually 600 dpi and high definition 1200 dpi. The following description will be given using an example of a resolution of 600 dpi.

[0017] Next, the image forming apparatus 101 will be described. In the image forming apparatus 101, a plurality of devices having different functions are connected, and it is configured to be capable of complex printing processes such as bookbinding. The image forming apparatus 101 has devices such as a printing module (printing device) 107, an inserter 108, an inspection module (inspection device) 109, a stacker 110, and a finisher 111. Each device will be described below.

[0018] The printing module 107 prints an image in accordance with a print job and ejects the printed recording material (paper). The printed recording material ejected from the printing module 107 is transported inside each device in the order of the inserter 108, the inspection module 109, the stacker 110, and the finisher 111. In the embodiment, the image forming apparatus 101 of the printing system 100 is an example of an image forming apparatus, but the printing module 107 included in the image forming apparatus 101 may also be referred to as an image forming apparatus.

[0019] The printing module 107 forms (prints) an image using toner (coloring material) on a recording material fed and conveyed from a paper feed unit disposed below the printing module 107. The inserter 108 is a device that inserts, for example, a partition recording material for separating a series of recording materials conveyed from the printing module 107 at an arbitrary position. The inspection module 109 is a device that inspects the printing defects (abnormal image) of the printed recording material on which an image is printed by the printing module 107 and conveyed through a conveying path. Specifically, the inspection module 109 reads the image printed on the conveyed printed recording material and compares the obtained read image with a reference image registered in advance to determine whether the image printed on the printed recording material is normal and inspects the presence or absence of printing defects. The stacker 110 is a device that can stack a large number of printed recording materials. The finisher 111 is a device that can execute finishing processes such as stapling, punching, and saddle stitching on the conveyed printed recording materials. The recording material processed by the finisher 111 is discharged onto a predetermined discharge tray.

[0020] 1, the external controller 102 is connected to the image forming apparatus 101, but the present embodiment can also be applied to a different configuration. For example, the image forming apparatus 101 may be directly connected to the external LAN 104, and print data may be sent from the client PC 103 to the image forming apparatus 101 without going through the external controller 102. In this case, data analysis and rasterization of the print data are performed by the image forming apparatus 101.

[0021] 2 is a cross-sectional view for explaining an example of the hardware configuration of the image forming apparatus 101 according to the embodiment. In the following, a specific operation example of the image forming apparatus 101 will be explained with reference to FIG.

[0022] In the printing module 107, various recording materials are stored in the paper feed decks 301 and 302. Of the recording materials stored in each paper feed deck, the uppermost recording material is separated one by one and fed to a conveying path 303. The image forming stations 304 to 307 each include a photosensitive drum (photoconductor) and form a toner image on the photosensitive drum using toner of a different color. Specifically, the image forming stations 304 to 307 form a toner image using toner of yellow (Y), magenta (M), cyan (C), and black (K), respectively.

[0023] The toner images of each color formed in the image forming stations 304 to 307 are transferred onto the intermediate transfer belt 308 in order, superimposed on top of each other (primary transfer). The intermediate transfer belt 308 is equipped with a detection sensor 359 that reads a position detection pattern formed to perform color misregistration correction control. The detection sensor 359 reads the position detection pattern and calculates the required correction amount. Based on the correction amount, the timing of laser emission in the image forming stations 304 to 307 is adjusted to correct the color misregistration.

[0024] 3 is a schematic diagram for explaining laser exposure to the photoconductors in the image forming stations 304 to 307. A specific operation example for laser exposure in the image forming stations 304 to 307 will be described below with reference to FIG.

[0025] The laser 708 adjusts the timing of light emission to the photoconductor 701. Adjusting the timing of light emission changes the position at which the laser 708 starts writing on the photoconductor 701. For example, the laser 708 starts writing on the photoconductor 701 from position 1601 for the recording material 1603. If the start of the light emission timing is delayed, the laser 708 starts writing on the photoconductor 701 from position 1602 for the recording material 1604. As a result of the above control, even if the defect is on the same part (component) (for example, on the photoconductor), a shift occurs in the main scanning position where the defect occurs.

[0026] The toner image transferred to the intermediate transfer belt 308 is conveyed to a secondary transfer position 309 according to the rotation of the intermediate transfer belt 308. At the secondary transfer position 309, the toner image is transferred from the intermediate transfer belt 308 to the recording material conveyed on the conveying path 303 (secondary transfer). The recording material after the secondary transfer is conveyed to a fixing unit 311. The fixing unit 311 includes a pressure roller and a heating roller. Heat and pressure are applied to the recording material while the recording material passes between these rollers, so that a fixing process is performed to fix the toner image to the recording material. The fixing unit 311 and the intermediate transfer belt 308 are equipped with a reciprocating mechanism as a measure against scratches caused by the edge of the paper. The reciprocating mechanism reduces scratches caused by the edge of the paper by changing the position in the main scanning direction where the recording material passes relative to the fixing unit 311 and the intermediate transfer belt 308. In addition, the writing position of the laser 708 in the image forming stations 304 to 307 is changed according to the reciprocating of the main scanning position of the recording material.

[0027] 4 is a schematic diagram for explaining the relationship between the photoconductors, lasers, and fixing unit 311 in the image forming stations 304 to 307. Hereinafter, a specific operation of the laser writing position in the reciprocating mode will be explained with reference to FIG.

[0028] For example, the reciprocating mechanism shifts the passage of recording material 1701 to position 1703 and the passage of recording material 1702 to position 1704 relative to the fixing unit 311. At that time, the laser 708 writes on the photoconductor 701 from position 1705 for recording material 1701 and from position 1706 for recording material 1702. As a result of the above control, as with the color shift correction control, even if there is a defect in the same part (for example, on the photoconductor), a shift occurs in the main scanning position where the defect occurs. The recording material that has passed through the fixing unit 311 is transported through the transport path 312 to the connection point 315 between the print module 107 and the inserter. In this manner, a color image is formed (printed) on the recording material.

[0029] When further fixing processing is required depending on the type of recording material, the recording material that has passed the fixing unit 311 is guided to a conveying path 314 provided with a fixing unit 313. The fixing unit 313 performs further fixing processing on the recording material conveyed on the conveying path 314. The recording material that has passed the fixing unit 313 is conveyed to a connection point 315. When an operation mode for double-sided printing is set, an image is printed on the first side, and the recording material conveyed on the conveying path 312 or the conveying path 314 is guided to a reversing path 316. The recording material that has been reversed by the reversing path 316 is guided to a double-sided conveying path 317 and conveyed to a secondary transfer position 309. As a result, at the secondary transfer position 309, a toner image is transferred to a second side of the recording material that is opposite to the first side. Thereafter, the recording material passes through the fixing unit 311 (and the fixing unit 313), completing the formation of a color image on the second side of the recording material.

[0030] When image formation (printing) in the printing module 107 is complete, the printed recording material that has been transported to the connection point 315 is transported into the inserter 108. The inserter 108 has an inserter tray 321 on which the recording material to be inserted is set. The inserter 108 inserts the recording material fed from the inserter tray 321 into an arbitrary insertion position in a series of printed recording materials transported from the printing module 107, and transports the recording material to a downstream device (inspection module 109). The printed recording materials that have passed through the inserter 108 are transported in order to the inspection module 109.

[0031] The inspection module 109 includes image reading units 331 and 332 each having a contact image sensor (CIS) on a transport path 330 along which the printed recording material from the inserter 108 is transported. The image reading units 331 and 332 are disposed in positions facing each other across the transport path 330. The image reading units 331 and 332 are configured to read the top surface (first surface) and bottom surface (second surface) of the recording material, respectively. Note that the image reading unit may be configured with, for example, a charge coupled device (CCD) or a line scan camera instead of the CIS.

[0032] The inspection module 109 performs an inspection process to inspect an image printed on a printed recording material being transported along a transport path 330. Specifically, the inspection module 109 performs a reading process to read an image on the printed recording material using image reading units 331 and 332 when the printed recording material being transported reaches a predetermined position. Furthermore, the inspection module 109 inspects the image printed on the recording material based on the image obtained by the reading process. The recording materials that have passed the inspection module 109 are transported to the stacker 110 in order.

[0033] In this embodiment, the inspection module 109 performs a process of inspecting for print defects by comparing a read image obtained by reading an image printed on a printed recording material with a reference image registered in advance. Methods of comparing images in this inspection process include, for example, a method of comparing pixel values ​​for each pixel, and a method of comparing the position of an object obtained by edge detection. Another method uses extraction of character data by OCR (Optical Character Recognition). The inspection module 109 also performs an inspection process for preset inspection items. The inspection items include, for example, misalignment of the print position of the image, color tone of the image, image density, streaks or blurs that have occurred in the image, printing defects, etc.

[0034] The stacker 110 includes a stack tray 341 as a tray on which printed recording materials transported from an inspection module 109 disposed upstream in the transport direction of the printed recording materials are stacked. The printed recording materials that have passed through the inspection module 109 are transported along a transport path 344 in the stacker 110. The printed recording materials transported along the transport path 344 are guided to a transport path 345, whereby the printed recording materials are stacked on the stack tray 341.

[0035] The stacker 110 further includes an escape tray 346 as a paper discharge tray. In this embodiment, the escape tray 346 is used for discharging printed recording materials that have been determined to have an abnormality in the printed image as a result of defect inspection by the inspection module 109. The printed recording materials conveyed along the conveying path 344 are guided to a conveying path 347 and conveyed to the escape tray 346. The printed recording materials that are conveyed in the stacker 110 without being stacked and discharged are conveyed via a conveying path 348 to the subsequent finisher 111.

[0036] The stacker 110 further includes an inverting unit 349 for inverting the orientation of the printed recording material being transported. The inverting unit 349 is used, for example, to make the orientation of the recording material input to the stacker 110 the same as the orientation of the printed recording material when it is stacked on the stack tray 341 and output from the stacker 110. Note that the inverting operation by the inverting unit 349 is not performed on the printed recording material that is not stacked in the stacker 110 and is transported to the finisher 111.

[0037] The finisher 111 executes a finishing function designated by a user on the printed recording material conveyed from the inspection module 109 arranged upstream in the conveying direction of the printed recording material. In this embodiment, the finisher 111 has finishing functions such as a staple function (one or two-point binding), a punch function (two or three holes), and a saddle stitch binding function. The finisher 111 includes two paper discharge trays 351 and 352. When the finishing process is not performed by the finisher 111, the printed recording material conveyed to the finisher 111 is discharged to the paper discharge tray 351 through a conveying path 353. When the finishing process such as stapling is performed by the finisher 111, the printed recording material conveyed to the finisher 111 is guided to a conveying path 354. The finisher 111 uses a processing section 355 to perform a finishing process designated by the user on the printed recording material conveyed along a conveying path 354, and discharges the printed recording material on which the finishing process has been performed to a paper discharge tray 352. When saddle stitching is designated, a saddle stitching processing section 356 staples the center of the sheet, folds the sheet in two, and outputs the sheet to a saddle stitching tray 358 via a sheet conveying 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 configured to be conveyed to the left side.

[0038] FIG. 5 is a block diagram illustrating the schematic functional configuration of the image forming apparatus 101, the external controller 102, and the client PC 103 according to the embodiment.

[0039] First, the print module 107 of the image forming apparatus 101 will be described.

[0040] The print module 117 includes a communication I / F (interface) 201, a network I / F 204, a video I / F 205, a CPU 206, a memory 207, a HDD unit (storage unit) 208, and a UI display unit (operation unit) 225. The print module 107 further includes an image processing unit 202 and a print unit (printer engine) 203. These are connected to each other via a system bus 209 so as to be able to transmit and receive data to and from each other.

[0041] The communication I / F 201 is connected to the inserter 108, the inspection module 109, the stacker 110, and the finisher 111 via a communication cable 260. The CPU 206 communicates through the communication I / F 201 to control each device. The network I / F 204 is connected to the external controller 102 via the internal LAN 105, and is used for communication of control data and the like. The video I / F 205 is connected to the external controller 102 via a video cable 106, and is used for data communication of image data and the like. Note that the print module 107 (image forming apparatus 101) and the external controller 102 may be connected only by the video cable 106, as long as the external controller 102 can control the operation of the image forming apparatus 101.

[0042] Various programs and data are stored in the HDD unit 208. The CPU 206 controls the operation of the entire print module 107 by expanding the programs stored in the HDD unit 208 into the memory 207 and executing them. The memory 207 stores programs and data required when the CPU 206 performs various processes. The memory 207 operates as a work area for the CPU 206. The UI display unit 225 accepts various setting inputs and operation instructions from the user, and is used to display various information such as setting information and the processing status of a print job.

[0043] The inserter 108 controls the insertion of the recording material fed from the paper feed unit and the transport of the recording material transported from the print module 107 .

[0044] Next, the inspection module 109 of the image forming apparatus 101 will be described.

[0045] The inspection module 109 includes a communication I / F 211, a CPU 214, a memory 215, an HDD unit (storage unit) 216, image reading units 331 and 332, and a UI display unit 241. These devices are connected to each other via a system bus 219 so as to be able to transmit and receive data to and from each other. The communication I / F 211 is connected to the print module 107 via a communication cable 260. The CPU 214 performs communication required for controlling the inspection module 109 via the communication I / F 211. The CPU 214 controls the operation of the inspection module 109 by executing a control program stored in the memory 215. A control program for the inspection module 109 is saved in the memory 215.

[0046] The image reading units 331 and 332 read an image (sample) of the conveyed recording material according to an instruction from the CPU 214. The CPU 214 performs a process of storing image data obtained by reading the image with the image reading units 331 and 332 in the HDD unit 216 as a reference image for defect inspection. The CPU 214 further performs an inspection process of comparing the inspection image read by the image reading units 331 and 332 with the reference image for defect inspection stored in the HDD unit 216, and inspecting the image printed on the recording material based on the comparison result. Note that, although an example of using the image data read by the image reading units 331 and 332 as the reference image for defect inspection has been described here, the present invention is not limited to this. For example, it is also possible to store a bitmap image obtained by rasterizing PDL data in the HDD unit 216 as the reference image for defect inspection and use it in the defect inspection process.

[0047] The UI display unit 241 is used to display defect inspection results, setting screens, etc. The operation unit of the inspection module 109 also serves as the UI display unit 241 and is operated by the user to accept various instructions from the user, such as changing the settings of the inspection module 109, instructions to register a reference image for defect inspection, instructions to perform image diagnosis, etc. The HDD unit 216 stores various setting information and image data required for defect inspection. The various setting information and image data stored in the HDD unit 216 can be reused.

[0048] The stacker 110 controls the printed recording material transported along the transport path so that it is discharged to a stack tray, discharged to an escape tray 346, or transported to a finisher 111 connected downstream in the transport direction of the printed recording material.

[0049] The finisher 111 controls the transport and discharge of printed recording materials, and performs finishing processes such as stapling, punching, or saddle stitching.

[0050] Next, the external controller 102 will be described.

[0051] The external controller 102 includes a CPU 251, a memory 252, an HDD unit 253, a keyboard 256, a display unit 254, network I / Fs 255 and 257, and a video I / F 258. These devices are connected to each other via a system bus 259 so as to be able to transmit and receive data to each other. The CPU 251 loads a program stored in the HDD unit 253 into the memory 252 and executes it, thereby controlling the overall operation of the external controller 102, such as receiving print data from the client PC 103, RIP processing, and transmitting print data to the image forming apparatus 101. The memory 252 stores programs and data required for the CPU 251 to perform various processes. The memory 252 operates as a work area for the CPU 251.

[0052] The HDD unit 253 stores various programs and data. The keyboard 256 is used for inputting operation instructions for the external controller 102 from the user. The display unit 254 is, for example, a display, and is used for displaying information on applications being executed in the external controller 102 and an operation screen. The network I / F 255 is connected to the client PC 103 via the external LAN 104 and is used for communication of data such as print instructions. The network I / F 257 is connected to the image forming apparatus 101 via the internal LAN 105 and is used for communication of data such as print instructions. The external controller 102 is configured to be able to communicate with the print module 107, the inserter 108, the inspection module 109, the stacker 110, and the finisher 111 via the internal LAN 105 and the communication cable 260. The video I / F 258 is connected to the image forming apparatus 101 via the video cable 106 and is used for communication of data such as image data (print data).

[0053] Next, the client PC 103 will be described.

[0054] The client PC 103 includes a CPU 261, a memory 262, an HDD unit 263, a display unit 264, a keyboard 265, and a network I / F 266. These devices are connected via a system bus 269 so as to be able to transmit and receive data to and from each other. The CPU 261 controls the operation of each device via the system bus 269 by loading a program stored in the HDD unit 263 into the memory 262 and executing it. This allows various processes to be performed by the client PC 103. For example, the CPU 261 generates print data and issues a print instruction by executing a document processing program stored in the HDD unit 263. The memory 262 stores programs and data required for the CPU 261 to perform various processes. The memory 262 operates as a work area for the CPU 261.

[0055] The HDD unit 263 stores various applications such as a word processing program, programs such as a printer driver, and various data. The display unit 264 is, for example, a display, and is used to display information about applications running on the client PC 103 and an operation screen. The keyboard 265 is used to input operation instructions for the client PC 103 from a user. The network I / F 266 is communicably connected to the external controller 102 via the external LAN 104. The CPU 261 communicates with the external controller 102 via the network I / F 266.

[0056] 1, an external controller 102 is connected to the image forming apparatus 101, but the embodiment can also be applied to a different configuration. For example, a configuration may be used in which the image forming apparatus 101 is connected to an external LAN 104, and print data is sent from a client PC 103 to the image forming apparatus 101 without going through the external controller 102. In this case, data analysis, interpretation, and rasterization of the print data are performed by the image forming apparatus 101.

[0057] Next, the defect inspection process according to this embodiment will be described with reference to FIG.

[0058] FIG. 6 is a flowchart for explaining the procedure of the print operation executed by the print module 107 according to the embodiment and the defect inspection process of the printed matter executed by the inspection module 109. Note that FIG. 6 shows the overall flow from the work before the start of the inspection to the actual inspection. The symbol "S" in the explanation of the flowchart represents a step. This also applies to the explanation of the following flowcharts. The processing of each step in FIG. 6 is executed by the CPU 206 of the print module 107 and the CPU 214 of the inspection module 109. In this embodiment, the print setting is set in advance to set the stacker 110 as the discharge destination of the printed matter (i.e., set the stack tray 341 of the stacker 110 as the discharge destination).

[0059] In S401, a print instruction is received from the client PC 103 or the external controller 102, and a print operation is started. That is, a print job is started. In this embodiment, for the sake of simplicity, the PDL data is assumed to be a portable document format (PDF) including a character image, and the following description will be given on the basis of an example in which the PDF is instructed to be directly printed to the external controller 102.

[0060] Next, the process proceeds to S402, and the CPU 251 of the external controller 102 performs PDL interpretation of the text, font type, size, paper position, etc., from the description in the PDF file according to the PDF print job accepted in S401. Then, the process proceeds to S403, and the CPU 251 rasterizes the text into a bitmap according to the resolution setting interpreted in the PDL interpretation in S402. Then, the process proceeds to S404, and the CPU 251 creates the rasterized bitmap as a reference image. Then, the process proceeds to S405, and the CPU 251 temporarily stores the reference image created in S404 in the HDD unit 253 of the external controller 102. Thereafter, the reference image stored in the HDD unit 253 is sent to the inspection module 109 and stored in the HDD unit 216 of the inspection module 109. The following description will be given assuming that the resolution of the reference image is 600 dpi.

[0061] Next, the process proceeds to S406, and the CPU 251 transmits the rasterized bitmap data from the video I / F 258 to the video I / F 205 of the print module 107 through the video cable 106. The CPU 206 of the print module 107 receives this bitmap data and causes the print unit 203 to print it.

[0062] Next, the process proceeds to S407, where the CPU 214 of the inspection module 109 executes processing to read the printed matter printed in S406 using the image reading units 331, 332. Next, the process proceeds to S408, where the CPU 214 stores the read image obtained in S407 as an inspection image in the HDD unit 216 of the inspection module 109. In this embodiment, the following description will be given assuming that the resolution when the printed matter is read by the image reading units 331, 332 is 600 dpi.

[0063] Next, the process proceeds to S409, where the CPU 214 executes a filter process for suppressing the occurrence of moire on the read image of the printed matter obtained by reading in S407. This process is performed to suppress high-frequency patterns and leave low-frequency components, so that interference fringes (moire) do not occur when resolution conversion is performed. Next, the process proceeds to S410, where the CPU 214 executes a process for converting the resolution of the read image of the printed matter after the filter process. As a result, the resolution of the read image of the printed matter after the filter process is converted to 300 dpi. The resolution after conversion is determined based on the calculation time of the deformation correction (alignment) of the reference image in S412 and the comparison process of the reference image and the read image in S413, which are performed later, and the size of the image defect to be detected. Next, the process proceeds to S411, where the CPU 214 executes gamma correction using a lookup table stored in the memory 215 of the inspection module 109 so as to match the gradation of the reference image created in S404 with the gradation of the read image converted in S410.

[0064] Next, the process proceeds to S412, where CPU 214 performs deformation correction on the reference image, and aligns the read image with the reference image that has been deformation corrected in S412. The process then proceeds to S413, where CPU 214 performs a process of comparing the read image obtained in S407 (i.e., obtained by reading the image printed on the recording material) with the reference image that has been deformation corrected in S412. When the image comparison process is thus completed, the process proceeds to S414, where CPU 214 determines whether the printed image is normal or not based on the result of the comparison process with the reference image. This determination is performed as follows.

[0065] First, a filter process for emphasizing a specific shape is applied to a difference image between a reference image and a read image. The filter process for emphasizing a specific shape will be described with reference to FIG.

[0066] FIG. 7 is a diagram for explaining an example of filter processing for emphasizing a specific shape, in which FIG. 7(A) shows an example of a filter for emphasizing a point-like defect, and FIG. 7(B) shows an example of a filter for emphasizing a line-like defect. A binarization process is performed on the difference image that has been subjected to these enhancement processes, so that if the difference value exceeds a threshold value, it is set to "1", and if it is equal to or less than the threshold value, it is set to "0". Then, in the image that has been subjected to the binarization process, it is determined whether or not there is a pixel (abnormal pixel) that has exceeded the threshold value and become "1". If a determination result is obtained that there is no pixel, it is determined to be normal, and if a determination result is obtained that there is a pixel, it is determined to be abnormal. However, the defect inspection process (inspection process) is not limited to the above method, and the type is not limited as long as it is a process that allows a user to detect a desired defect.

[0067] If the CPU 214 determines in S414 that the printed image is normal, the process proceeds to S415, where the CPU 214 displays "Inspection Result OK", which is a defect inspection result indicating that the printed image is normal, on the UI display unit 241 of the inspection module 109. The process then proceeds to S416, where the CPU 214 instructs the print module 107 to eject the printed material onto the stack tray 341 of the stacker 110. The print module 107 then instructs the stacker 110 to eject the conveyed printed material onto the stack tray 341 based on the instruction from the inspection module 109, and proceeds to the process of S419.

[0068] On the other hand, when the CPU 214 determines in S414 that the printed image is not normal (the image has an abnormality), the process proceeds to S417. In S417, the CPU 214 displays "inspection result NG", which is an inspection result indicating that the printed image is not normal, on the UI display unit 241 of the inspection module 109. Then, the process proceeds to S418, where the CPU 214 instructs the print module 107 to discharge the printed matter to the escape tray 346 of the stacker 110. Then, based on the instruction from the inspection module 109, the print module 107 instructs the stacker 110 to discharge the conveyed printed matter to the escape tray 346, and the process proceeds to S419. In S419, the CPU 214 determines whether printing of all pages and defect inspection processing have been completed, and when the CPU 214 determines that printing of all pages and defect inspection processing have not been completed, the process proceeds to S403. Then, the CPU 206 of the printing module 107 and the CPU 214 of the inspection module 109 continue the processes of S403 to S418. On the other hand, if the CPU 214 determines in S419 that printing and defect inspection processing for all pages has been completed, the CPU 214 ends the printing processing and defect inspection processing. In other words, the flow shown in FIG. 6 ends.

[0069] [Embodiment 1] Next, the image diagnosis processing according to the first embodiment will be described with reference to FIG.

[0070] 8 is a flowchart for explaining the procedure of image diagnosis processing according to the embodiment 1. The processing of each step in FIG.

[0071] In S801, the printing system 100 starts image diagnosis processing when it receives an image diagnosis instruction from a user or a serviceman via the UI display unit 241 of the inspection module 109, which also serves as an operation unit. Next, the process proceeds to S802, and the CPU 251 of the external controller 102 reads out a test chart stored in advance, rasterizes it into a bitmap, and creates the rasterized bitmap of the test chart as a reference image. This test chart is an image for fault diagnosis of the image forming apparatus 101 (hereinafter, also referred to as a test image). This test chart is a single solid color (area ratio 100%) of cyan, magenta, yellow, and black. Next, the process proceeds to S803, and the CPU 251 temporarily stores the reference image of the test chart created in S802 in the HDD unit 253 of the external controller 102. Thereafter, the reference image of the test chart stored in the HDD unit 253 is sent to the inspection module 109 and stored in the HDD unit 216 of the inspection module 109. In the following description, the resolution of the reference image of the test chart at this time is 600 dpi.

[0072] Next, the process proceeds to S804, and the CPU 251 transmits the bitmap data of the rasterized test chart from the video I / F 258 to the video I / F 205 of the print module 107 through the video cable 106. As a result, the CPU 206 of the print module 107 performs halftone processing on the bitmap data of the test chart received by the video I / F 205, and the print unit 203 prints the test chart based on the image data after the halftone processing.

[0073] Next, the process proceeds to S805, where the CPU 214 of the inspection module 109 executes processing to read the printed test chart using the image reading units 331 and 332. The process then proceeds to S806, where the CPU 214 stores the read image of the test chart obtained in S805 as an inspection image in the HDD unit 216 of the inspection module 109. In this embodiment, the following description will be given assuming that the resolution when the printed test chart is read by the image reading units 331 and 332 is 600 dpi.

[0074] Next, the process proceeds to S807, where the CPU 214 performs a filter process for suppressing the occurrence of moire on the read image of the printed matter (test chart) obtained by reading in S805. Then, the process proceeds to S808, where the CPU 214 performs a process for converting the resolution of the read image of the printed matter (test chart) after the filter process. As a result, the resolution of the read image of the printed matter (test chart) after the filter process is converted to 300 dpi. Next, the process proceeds to S809, where the CPU 214 matches the gradation of the read image whose resolution has been converted in S808 with the reference image received from the external controller 102 and stored in the HDD unit 216. Here, the CPU 214 performs a gamma correction process on the read image using a lookup table stored in the memory 215 of the inspection module 109. Then, the process proceeds to S810, where the CPU 214 performs a deformation correction on the reference image, and performs alignment between the gamma-corrected read image and the reference image that has been deformation-corrected in S810. Then, the process proceeds to S811, where the CPU 214 executes a process of comparing the read image with a reference image of a test chart that has been adjusted for conditions such as resolution. When the image comparison process is thus completed, the process proceeds to S812, where the CPU 214 determines whether the printed image (test chart image) is normal or not based on the comparison result between the reference image and the read image in the comparison process, in the same manner as the inspection process of S414 in Fig. 6. Here, if the CPU 214 determines that the printed image is normal, the process proceeds to S813, where the CPU 214 displays an image diagnosis result indicating that there is no problem on the UI display unit 241 of the inspection module 109. For example, "No problem" is displayed.

[0075] On the other hand, when the CPU 214 determines in S812 that the printed image is not normal (the image has a defect), the process proceeds to S814. In S814, the CPU 214 acquires information related to the main scanning position from the print module 107. Next, the process proceeds to S815, where the CPU 214 extracts a feature amount for an image defect, which is an image portion in which the difference data obtained in the comparison process between the reference image and the read image in S811 is larger than a predetermined amount. The feature amount of the image defect obtained by this extraction process includes, for example, color information such as whether the defect is a single color such as yellow, magenta, cyan, or black or a multi-color occurring in multiple colors, contrast information indicating the density of the defect, and shape information such as size and vertical elongation. In addition, there are also coordinate information indicating the position relative to the test chart in the print module 107 and periodicity information indicating that similar defects occur periodically in the sub-scanning direction of the test chart of the print module 107. In addition, continuity information indicating that defects in the shape of stripes caused by the same factor occur consecutively between pages is also one of the feature amounts. The process of extracting periodicity features for extracting periodicity information as a feature amount and the process of extracting continuity features for extracting continuity information as a feature amount will be described later.

[0076] Next, the process proceeds to S816, where the CPU 214 identifies parts that are causing the image defects in the printing module 107 and the inspection module 109, based on the feature amounts of the image defects obtained in S815. Next, the process proceeds to S817, where the CPU 214 determines how to deal with the image defects, based on the parts that are causing the image defects identified in S815.

[0077] These measures are divided into measures that can be automatically restored and measures that cannot be automatically restored. Measures that can be automatically restored include measures that can be automatically restored by the printing module 107, such as cleaning the wires and grids of the corona chargers that are charging means for the photosensitive drums provided in the image forming stations 304 to 307 of the printing module 107. Measures that cannot be automatically restored include measures that require user work, such as cleaning dirt from the reading surfaces of the image reading units 331 and 332 of the inspection module 109, adjusting the recording material to be used, and measures that require service technician work, such as replacing parts. Measures that cannot be automatically restored include measures to deal with fibers or foreign matter that are in the recording material before image formation.

[0078] Next, the process proceeds to S818, where the CPU 214 determines whether the action determined in S817 is an automatically recoverable action. If the CPU 214 obtains a determination result in S818 that the action determined is an automatically recoverable action, the process proceeds to S819. In S819, the CPU 214 executes automatic recovery control to deal with the cause of the image defect. On the other hand, if the CPU 214 determines in S818 that the action is not automatically recoverable, the process proceeds to S820. In S820, the CPU 214 displays the image diagnosis result and the method of action on the UI display unit 241 of the inspection module 109. When any of the above-mentioned processes in S813, S819, and S820 is completed, the flow (image diagnosis process) shown in FIG. 8 ends.

[0079] [Periodicity feature extraction] Next, the necessity for the process of extracting periodic features will be described.

[0080] FIG. 9 is a diagram showing an example in which defects that occur periodically in the sub-scanning direction appear as misalignment in the main scanning direction between pages during inspection.

[0081] As shown in FIG. 9(A), in the printing module 107, during color shift correction, the emission timing adjustment of the laser 708 in the image forming stations 304 to 307 and the variation in the recording material position due to reciprocation occur. At this time, according to the emission timing adjustment for color shift correction and the main scanning position variation of the recording material due to reciprocation, the writing position of the photoreceptor 701 varies between pages. The CPU 206 of the printing module 107 performs writing from the writing position 703 on the photoreceptor 701 for page 702. Next, the CPU 206 performs writing from the writing position 706 for page 705. Further, the CPU 206 performs writing from the writing position 703 for page 712. The defects 704, 707, and 713 are periodic defects caused by the scratch 711 of the photoreceptor 701. Therefore, as shown in FIG. 9(A), the defects 704, 707, and 713 occur at the same main scanning position with respect to the photoreceptor 701 and occur every rotation period 714 of the photoreceptor based on the diameter of the photoreceptor 701.

[0082] Here, for page 702 and page 712, the writing positions with respect to the photoreceptor 701 are the same. In this case, during inspection, the main scanning positions of defect 704 and defect 713 are the same. Also, the color information, size, and contrast information between the defects are similar. Further, since the distance in the sub-scanning direction between the defects matches the rotation period 714 of the photoreceptor, it can be determined that they have the periodic characteristics of the rotation period 714 of the photoreceptor.

[0083] However, between page 702 and page 705, the writing positions are shifted by the shift amount indicated by reference numeral 710 in the main scanning direction in FIG. 9(A). The CPU 214 of the inspection module 109 performs inspection by aligning the left end portions of the read images of page 702 and page 705 at position 709 as shown in FIG. 9(B) during inspection. Therefore, in the state during inspection, due to the shift of the main scanning positions of defect 704 on page 702 and defect 707 on page 705 by the shift amount indicated by reference numeral 710, it is difficult to determine periodicity.

[0084] Therefore, in the first embodiment, for defects occurring at the same main scanning position, even if the main scanning position is shifted during inspection, information about the image formation position is acquired and periodicity determination can be performed with high accuracy. Below, the process of acquiring information related to the main scanning position and the process of extracting periodicity features are described in detail.

[0085] Fig. 10 is a flowchart for explaining the defect feature extraction process of S815 following the acquisition process of main scanning position related information of S814 in Fig. 8 by the inspection module 109 according to the first embodiment. The purpose of this periodicity feature extraction process is to extract the fact that defects occur periodically as a defect feature amount. Furthermore, examples of the main scanning position related information include the laser writing position and the reciprocal width setting value. In this embodiment, the laser writing position will be described as an example.

[0086] FIG. 11 is a diagram for explaining an example of acquiring the laser writing start position and setting search conditions.

[0087] In S814, the CPU 214 of the inspection module 109 acquires laser writing position information starting from the photoconductor 701, which is control information for the laser 708, as information related to the main scanning position of each page. In the example of Fig. 11, the CPU 214 acquires writing position 703 as information related to the main scanning position for page 702. Next, it acquires writing position 706 as information related to the main scanning position for page 705, and acquires writing position 703 as information related to the main scanning position for page 712.

[0088] Next, the process proceeds to S1001, and the CPU 214 sets search conditions 1101 for page 705 and search conditions 1104 for page 712 from the related information of the main scanning position and the position information of the defect 704 on page 702. These search conditions are the width (range) in the main scanning direction to be searched and the center coordinate of the width. For example, a fixed value considering the paper conveyance deviation or a variable value considering the paper conveyance deviation and the size of the defect 704 in the main scanning direction is set as the width 1102 of the search conditions 1101 and 1104. The center coordinate is calculated using the related information of the main scanning position in the following manner. The laser writing position 703 on page 702 and the laser writing position 706 on page 705 are compared to calculate the deviation amount 710. The center coordinate of the search conditions 1101 is set to a position 1103 shifted by the deviation amount 710 from the position of the defect 704 on page 702 in the main scanning direction. Furthermore, since the writing start positions of page 702 and page 712 are both writing start position 703 and there is no deviation, search condition 1104 is set based on the position of defect 704 in the main scanning direction.

[0089] Next, the process proceeds to S1002, where the CPU 214 classifies defects that exist within the search conditions 1101 and 1104, and determines whether there are any similar defects. In this embodiment, color information, contrast information, and size information of the defects are calculated, and similar defects are determined. The color information is acquired from the reference image to indicate whether the color is cyan, magenta, yellow, or black. If the acquired color information of the defects does not match, the defects are not similar. If the color information of the defects matches, and the defect is cyan, contrast is calculated from the value of the complementary color R signal. If the defect is magenta, contrast is acquired from the G signal, if the defect is yellow, contrast is acquired from the B signal, and contrast is acquired from the luminance signal if the defect is black. In addition, an average value of the defect signals is acquired as contrast information of the defects. The contrast information of the defects is compared, and if the difference is greater than a threshold, the defects are deemed not similar. This threshold is determined taking into consideration the density fluctuation of the print module 107. Next, the size of the defects will be described. The width, height, and area are acquired as size information of the defects. The size information of the defects is compared, and if the difference is equal to or less than a threshold, the defects are deemed similar, and if the difference is greater than the threshold, the defects are deemed not similar. This threshold is determined by collecting defects of the same cause in advance and using known machine learning to determine a threshold that can determine that defects are the same.

[0090] The method of determining the threshold value based on the contrast information and size information is not limited to the above example. Any means capable of determining the similarity between defects may be used, and for example, defects of the same cause may be collected and analyzed in advance to determine the similarity. If the color information matches and the difference between the contrast information and the size information is equal to or less than the threshold, the defects are deemed to be similar. The method of determining the similarity between defects is not limited to the above example. Any means capable of determining whether defects have similar characteristics may be used, and for example, a known template matching method may be used to perform an integrated similarity determination based on color and shape.

[0091] Next, the process proceeds to S1003, where the CPU 214 determines whether there are similar defects, and if it is determined that there are similar defects, the process proceeds to S1004, where the CPU 214 acquires the sub-scanning distance between the defects, and then proceeds to S1005. On the other hand, if the CPU 214 determines in S1003 that there are no similar defects, the process proceeds to S1008. In S1005, the CPU 214 acquires pre-stored periodic information of the parts (periodic distance in the sub-scanning direction).

[0092] FIG. 16 is a diagram showing an example of the relationship between parts of the print module 107 and their cycle information.

[0093] In this embodiment, the periodic information of the parts is periodic information 1802 in the sub-scanning direction where defects occur due to each part 1801. Note that the periodic information may be stored in advance and calculated sequentially, such as the diameter of each part and the speed difference with the paper transport speed, to calculate the periodic distance in the sub-scanning direction where defects occur for the parts.

[0094] Next, the process proceeds to S1006, where the CPU 214 compares the calculated sub-scanning distance between the defects with the periodic information 1802. If there is any matching periodic information, the process proceeds to S1007, where the CPU 214 extracts, as a feature, that the defects occur in the part period, and ends this process. For example, if the sub-scanning distance between the defects matches the periodic information 1803 of the photoconductor drum in FIG. 16, the CPU 214 extracts, as a feature, that the defects occur in the periodic information 1803 of the photoconductor drum. Note that the method of determining this periodicity is not limited to the above example. For example, the paper interval, which is the interval at which the recording medium is conveyed (the interval from the end of the recording medium to the front end of the next recording medium), may not be constant. In that case, the information on the paper interval for each page may be acquired, and the periodicity may be determined after taking the paper interval information into consideration. Also, the maximum paper interval may be stored, and if the difference between the sub-scanning distance between the defects and the part periodic information 1802 is within a range, it may be determined that there is periodicity.

[0095] On the other hand, if the CPU 214 determines in S1006 that the sub-scanning distance does not match the periodic information of any part, the process proceeds to S1008. In S1008, the CPU 214 extracts the defect as a feature that does not occur periodically, and ends this process. When either the process of S1007 or S1008 described above is completed in this manner, the flow shown in S815 of FIG. 10 (defect feature extraction) ends.

[0096] [Variation 1] In the above-mentioned embodiment 1, an example has been described in which the laser writing start position is used as the related information of the main scanning position. However, the related information of the main scanning position is not limited to the above example. For example, the reciprocating width (a set value of the main scanning position where the recording medium passes) may be used as the related information of the main scanning position.

[0097] FIG. 12 is a diagram for explaining misalignment of a sheet with respect to a reciprocating width according to the first modification of the first embodiment.

[0098] In the printing system 100, a reciprocation width 1201 is set for the fixing unit 311 by a user or a serviceman via a UI display unit 241 that also serves as an operation unit. The CPU 206 varies the laser writing positions 703, 706, 1203, and 1206 of the photoconductor 701 relative to the recording materials 702, 705, 1202, and 1205 within the range of the reciprocation width 1201 according to the reciprocation.

[0099] A detailed description will be given of a case where the reciprocating width is acquired as related information of the main scanning position (S814) and the search conditions are set (S1001).

[0100] In S814, the CPU 214 acquires the reciprocating setting width 1201 as related information of the main scanning position. Next, in S1001, the CPU 214 sets search conditions 1208 for pages 705, 1202, and 1205 shown in FIG. 12B based on the main scanning position of the defect 704 and the reciprocating setting width 1201 (related information of the main scanning position). The center coordinates of these search conditions 1208 are set to the main scanning position of the defect 704. Also, the width of the search conditions 1208 is set to the reciprocating setting width 1201 (related information of the main scanning position). Then, the process proceeds to S1002, where the CPU 214 determines whether or not there is a similar defect within the search conditions 1208.

[0101] [Variation 2] In the above-mentioned embodiment 1, an example was described in which a test chart was used to judge image defects, but the inspection target image to be judged for image defects is not limited to the above example. For example, image defects may be judged using an image that a user wishes to output (user's actual image), and image diagnosis processing may be performed using the judged defect inspection result.

[0102] Fig. 13 is a flowchart for explaining a process for performing image diagnosis processing using an actual image of a user according to Modification 2 of Embodiment 1. In Fig. 13, the same processes as those in the flowcharts of Fig. 6 and Fig. 8 described above are denoted by the same reference numerals, and the description thereof will be omitted.

[0103] In S801, the printing system 100 starts image diagnosis processing when it receives an image diagnosis instruction from a user or a serviceman via the UI display unit 241 that also serves as an operation unit. Next, defect inspection processing is performed by the CPU 206 of the printing module 107 and the CPU 214 of the inspection module 109. Then, when it is determined that the image is not normal in the defect inspection processing, S417 and S418 are executed. Then, the process proceeds to S815, where the CPU 214 extracts defect features for the detected defects.

[0104] In addition, a user or a service person can select, via the UI display unit 241, as an image to be inspected, a test chart for identifying a defective portion or an arbitrary user image.

[0105] As described above, according to the first embodiment, by determining the periodicity of image defects using information on the image formation position in the print module, the periodicity of image defects can be determined with higher accuracy by taking into account the shift in the main scanning direction of the defect position during image formation and inspection. This allows the parts of the print module that cause the image defects to be identified with high accuracy, and by taking appropriate measures based on the identification results, the operation of the printing system can be quickly restored. In addition, by executing the process before the user starts printing, image defects can be stably found, and it is possible to ensure that there are no problems with the printing system before starting printing.

[0106] [Embodiment 2] Next, a printing system according to a second embodiment will be described. In the first embodiment described above, a periodic feature extraction process is described in which related information of the main scanning position is acquired, search conditions are set, and the presence or absence of similar defects is determined. In contrast, in the second embodiment, an aspect is described in which the presence or absence of defects is determined at the part cycle from periodic information in the periodic feature extraction process. Note that the configuration of the printing system according to the second embodiment is the same as that of the first embodiment described above, and therefore a description thereof will be omitted. [Periodicity feature extraction] The process of extracting periodic features according to the second embodiment will be described with reference to FIG.

[0107] Fig. 14 is a flowchart explaining the procedure of processing for extracting periodicity features according to embodiment 2. Like Fig. 10 described above, Fig. 14 explains the defect feature extraction processing in S815 following the acquisition processing of main scanning position related information in S814 in Fig. 8 by the inspection module 109 according to embodiment 1.

[0108] FIG. 15 is a diagram showing an example in which the laser writing start position is acquired as related information of the main scanning position, and the period information is used to set the period occurrence range in the second embodiment.

[0109] In S814, the CPU 214 acquires information related to the main scanning position. In the second embodiment, the laser writing start positions 703 and 706 in FIG.

[0110] In S1401, the CPU 214, as in the description of the first embodiment, holds the relationship between parts and periodic distances as shown in FIG. 16, and acquires periodic information by sequentially selecting parts.

[0111] Next, in S1402, the CPU 214 calculates periodic distances 1501 and 1502, which are distances in the sub-scanning direction that occur periodically for the defect 704, based on the periodic information acquired in S1401. Next, the process proceeds to S1403, where the CPU 214 calculates periodic occurrence ranges 1503 and 1504 from the related information 703 and 706 for the main scanning position acquired in S814 and the periodic information 1501 and 1502 calculated in S1402. Here, the central coordinates in the main scanning direction of the periodic occurrence ranges 1503 and 1504 are positions shifted by the difference 710 in the related information for the main scanning position from the main scanning position of the defect 704, as shown in Fig. 15B. In addition, the central coordinates in the sub-scanning direction are set to positions shifted by the periodic distance 1501 and the periodic distance 1502 from the sub-scanning position of the defect 704. The width of the period occurrence range 1503 is set based on the same concept as the width, which is one of the search conditions in embodiment 1. Furthermore, the height of the period occurrence range 1503 is set to, for example, a fixed value based on the maximum interval between sheets, or a variable value based on the size of the defect 704.

[0112] The process then proceeds to S1404, where the CPU 214 determines whether or not there is a defect similar to the defect 704 within the period occurrence range (within 1503, 1504). If it is determined that there is a similar defect, the process proceeds to S1405. Note that the method for determining whether or not there is similarity is the same as in the first embodiment described above, and therefore a description thereof will be omitted. In S1405, if there is a similar defect within the period occurrence range 1503, the CPU 214 sets the defect 704 to have the periodicity characteristic of the periodic part of the periodic information 1501. Furthermore, if there is a similar defect within the period occurrence range 1504, the CPU 214 sets the defect 704 to have the periodicity characteristic of the periodic part of the periodic information 1502.

[0113] On the other hand, if the CPU 214 determines in S1404 that there is no similar defect, the process proceeds to S1406. In S1406, the CPU 214 sets that the defect 704 does not have a periodic characteristic, and ends this process. When either the process of S1405 or S1406 described above is completed in this manner, the flow (periodic characteristic extraction) shown in FIG. 14 is ended. As described above, according to the second embodiment, by extracting periodic features, it is possible to confirm the presence or absence of similar defects within the periodic occurrence range of defects, rather than comparing all defects with each other. Therefore, when many defects are detected, periodic features can be efficiently extracted.

[0114] [Embodiment 3] Next, a printing system according to a third embodiment will be described. In the above-mentioned first and second embodiments, the processing for acquiring related information of main scanning positions and extracting periodicity features has been described. In the third embodiment, an aspect for extracting continuity information as a feature amount will be described. This continuity information is a feature amount indicating whether or not streak-shaped defects appear continuously between pages. Note that the configuration of the printing system according to the third embodiment is the same as that of the above-mentioned first embodiment, and therefore a description thereof will be omitted. [Continuity feature extraction] Next, the necessity of the process of extracting continuity features will be described.

[0115] FIG. 18 is a schematic diagram showing an example in which a streak-shaped defect that occurs continuously at the same main scanning position on a part between pages is misaligned in the main scanning position during inspection, and a process for extracting continuity features according to the third embodiment.

[0116] In the printing module 107, a dustproof glass 2001 is present between a laser 708 and a photoconductor 701. If there is dirt 2008 on the dustproof glass 2001, the light exposure is blocked and a white streak-like image defect occurs. At this time, defects 2009 to 2011 occur consecutively on the recording materials 2002, 2004, and 2005. These defects 2009 to 2011 occur at the same main scanning position on the dustproof glass 2001. However, as in the first embodiment, due to a shift in the writing start position, the main scanning position may shift during inspection, making it difficult to determine whether the image defects are consecutive.

[0117] Next, the continuity feature extraction process according to the third embodiment will be described with reference to the drawings.

[0118] Fig. 17 is a flowchart for explaining the procedure of the continuity feature extraction process according to the embodiment 3. Like Fig. 10 described above, Fig. 17 explains the defect feature extraction process in S815 following the acquisition process of main scanning position related information in S814 in Fig. 8 by the inspection module 109 according to the embodiment 1. The same reference numbers are used for the processes common to Fig. 10.

[0119] In S814, the CPU 214 acquires information related to the main scanning position. In the third embodiment, the laser writing start positions 2003 and 2006 in FIG.

[0120] 18B, the CPU 214 sets search conditions 2012 and 2013 using related information on the main scanning position, as in the first embodiment. A laser writing position 2003 on page 2002 is compared with a laser writing position 2006 on page 2004 to calculate a deviation amount 2007. The center coordinates of the search conditions 2012 are set to a position shifted by the deviation amount 2007 from the main scanning direction position of a defect 2009 on page 2002. Next, the center coordinates of the search conditions 2013 are set to the same position as the main scanning direction position of the defect 2009, since the writing positions of pages 2002 and 2005 are both writing position 2003, which has no deviation amount.

[0121] Next, the process proceeds to S1002, where the CPU 214 searches for the presence or absence of a streak similar to the streak 2009 within the search conditions 2012 and 2013. If it is determined in S1003 that a similar defect exists, the process proceeds to S1701, and if it is determined that a similar defect does not exist, the process proceeds to S1702. In S1701, the CPU 214 extracts the fact that the defects occur consecutively as a feature amount, sets that there is a continuity feature, and ends this process. Also, in S1702, the CPU 214 sets that there is no continuity because the defects do not occur consecutively, and ends this process.

[0122] As described above, according to the third embodiment, by extracting the continuity feature of the defect, it is possible to determine that the streaks are continuous even if the streaks are misaligned in the main scanning direction during inspection. This makes it possible to stably identify the cause of the image defect and take action based on the identification result, thereby enabling the printing system to quickly return to operation.

[0123] (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.

[0124] This specification discloses the following printing system, inspection apparatus and control method thereof.

[0125] [Item 1] A printing system having a printing device and an inspection device that reads and inspects an image formed on a recording material by the printing device, The inspection device includes: an image reading means for reading an image formed by the printing device and acquiring the image as an inspection image; an inspection means for inspecting the inspection image by comparing the inspection image with a reference image; an acquisition unit that acquires information related to a main scanning position regarding image formation in the printing device from the printing device; an extraction means for extracting a feature amount of a defect obtained by the inspection by the inspection means using the related information of the main scanning position; a determining unit for determining a location of the printing device that is the cause of the defect based on the feature amount; A printing system comprising:

[0126] [Item 2] 2. The printing system according to item 1, wherein the extraction means sets search conditions according to the related information of the main scanning position, and classifies defects that meet the search conditions.

[0127] [Item 3] 3. The printing system according to item 2, wherein the search conditions include a width in the main scanning direction and a center coordinate.

[0128] [Item 4] 3. The printing system according to item 2, wherein the extraction means extracts, as a feature, periodicity information in the sub-scanning direction in which the classified defects are detected.

[0129] [Item 5] the inspection device further comprises a storage means for storing periodic information in a sub-scanning direction in which defects occur due to components of the printing device; The printing system described in item 4, characterized in that the extraction means extracts periodicity information in the sub-scanning direction in which the defects are detected based on the classified defects and the periodicity information in the sub-scanning direction stored in the memory means.

[0130] [Item 6] 4. The printing system according to item 3, wherein the extraction means determines similar defects from the defects that meet the search conditions, and determines that the similar defects are defects caused by the same factor.

[0131] [Item 7] The printing system described in item 6, characterized in that the similar defects satisfy at least one of the following conditions: the color information of the acquired defects matches, the difference in contrast information between the defects is smaller than a threshold, and the difference in size between the defects is equal to or smaller than a threshold.

[0132] [Item 8] the inspection device further comprises a storage means for storing periodic information in a sub-scanning direction in which defects occur due to components of the printing device; The printing system described in item 4, characterized in that the extraction means sets a periodic occurrence range based on the periodic information in the sub-scanning direction stored in the memory means, and extracts periodicity information of the defect in the sub-scanning direction as a feature based on the periodic occurrence range and the association information of the main scanning position.

[0133] [Item 9] 9. The printing system according to any one of items 1 to 8, wherein the extraction unit extracts information on whether the defects are continuous in the sub-scanning direction as a feature amount.

[0134] [Item 10] 10. A printing system according to any one of items 1 to 9, characterized in that the information relating to the main scanning position includes either a laser writing position or information indicating a width of the main scanning position through which the recording medium passes.

[0135] [Item 11] the inspection device further comprises a storage means for storing the feature amount and periodic information in a sub-scanning direction in which defects occur due to components of the printing device in association with each other; The printing system according to any one of items 1 to 10, characterized in that the identification means refers to the storage means and identifies the part of the printing device that is the cause of the defect based on periodic information contained in the feature.

[0136] [Item 12] 12. The printing system according to any one of items 1 to 11, wherein the image is a test chart for identifying a defective portion of the printing device.

[0137] [Item 13] 13. The printing system according to any one of items 1 to 12, wherein the defect is an image portion in which difference data obtained by performing a comparison process between the inspection image and the reference image is greater than a predetermined amount.

[0138] [Item 14] An inspection device that reads and inspects an image formed on a recording material, an image reading means for reading an image formed by a printing device and acquiring the image as an inspection image; an inspection means for inspecting the inspection image by comparing the inspection image with a reference image; an acquisition unit that acquires information related to a main scanning position regarding image formation in the printing device from the printing device; an extraction means for extracting a feature amount of a defect obtained by the inspection by the inspection means using the related information of the main scanning position; a determining unit for determining a location of the printing device that is the cause of the defect based on the feature amount; An inspection device comprising:

[0139] [Item 15] 15. The inspection apparatus according to item 14, wherein the extraction means extracts periodicity information in the sub-scanning direction in which the defects are detected as a feature amount.

[0140] [Item 16] the inspection device further comprises a storage means for storing periodic information in a sub-scanning direction in which defects occur due to components of the printing device; 16. The inspection apparatus according to item 15, wherein the extraction means extracts periodicity information in the sub-scanning direction in which the defect is detected based on the defect and the periodicity information in the sub-scanning direction stored in the storage means.

[0141] [Item 17] 17. The inspection apparatus according to any one of items 14 to 16, wherein the extraction means extracts information on whether the defects are continuous in the sub-scanning direction as a feature.

[0142] [Item 18] A control method for controlling an inspection device that reads and inspects an image formed on a recording material, comprising: an image reading step of reading an image formed by a printing device and acquiring the image as an inspection image; an inspection step of inspecting the inspection image by comparing the inspection image with a reference image; an acquisition step of acquiring information related to a main scanning position regarding image formation in the printing device from the printing device; an extraction step of extracting a feature amount of a defect obtained by the inspection in the inspection step by using related information of the main scanning position; a step of identifying a location of the printing device that is the cause of the defect based on the feature amount; A control method comprising the steps of:

[0143] [Item 19] 19. A program for causing a computer to execute each step of the control method described in Item 18.

[0144] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention. [Explanation of symbols]

[0145] 101: image forming apparatus, 102: external controller, 107: print module, 109: inspection module, 331, 332: image reading unit, 304 to 307: image forming station, 701: photoconductor, 708: laser

Claims

1. An image processing system having a printing device, a reading device, and an inspection device, a reading unit that reads, by the reading device, a printed matter on which an image is printed by the printing device on a recording material; an acquisition unit for acquiring an amount of misalignment of a recording material in a direction perpendicular to a conveyance direction of the recording material used for printing by the printing device; a detection means for detecting an image defect included in the image read by the reading means using the inspection device; a diagnostic means for diagnosing a defective part of the printing device based on a result of detection by the detection means, The diagnosis means diagnoses the defective portion based on a detection result of an image defect included in a detection target area determined based on the amount of deviation acquired by the acquisition means, The image processing system according to claim 1, wherein the detection means determines a detection target area on the second page based on a position of an image defect on the first page and the amount of deviation.

2. 2. The image processing system according to claim 1, wherein the detection target area is further determined based on cycle information of components of the printing device.

3. 3. The image processing system according to claim 2, wherein the part is a photosensitive drum or a developing unit.

4. 2. The image processing system according to claim 1, wherein said diagnosing means diagnoses the defective portion based on a distance between a plurality of similar image defects detected by said detecting means.

5. 2. The image processing system according to claim 1, wherein an image is printed by the printing device on a recording material whose position has been shifted in the perpendicular direction in accordance with the amount of deviation.

6. 2. The image processing system according to claim 1, wherein the image printed on the recording material includes a solid monochrome image of cyan, magenta, yellow, and black.

7. A control method for controlling an image processing system having a printing device, a reading device, and an inspection device, comprising the steps of: a reading step of reading, by the reading device, a printed matter on which an image is printed on a recording material by the printing device; an acquisition step of acquiring a misalignment amount of a recording material in a direction perpendicular to a conveyance direction of the recording material used for printing by the printing device; a detection step of detecting an image defect included in the image read in the reading step by the inspection device; a diagnostic step of diagnosing a defective part of the printing device based on a detection result by the detection step, the diagnosing step diagnoses the defective portion based on a detection result of an image defect included in a detection target area determined based on the amount of deviation acquired in the acquiring step; The control method according to the present invention, wherein the detection step determines a detection target area on the second page based on a position of an image defect on the first page and the amount of deviation.

8. 8. The method of claim 7, wherein the detection target area is further determined based on periodicity information of components of the printing device.

9. 9. The control method according to claim 8, wherein the part is a photosensitive drum or a developing unit.

10. 8. The control method according to claim 7, wherein said diagnosing step diagnoses the defective portion based on a distance between a plurality of similar image defects detected in said detecting step.

11. 8. The control method according to claim 7, further comprising the step of printing an image by the printing device on the recording material whose position has been shifted in the perpendicular direction in accordance with the amount of deviation.

12. 8. The control method according to claim 7, wherein the image printed on the recording material includes a solid monochrome image of cyan, magenta, yellow, and black.

13. A program for causing a computer to execute a control method for controlling an image processing system having a printing device, a reading device, and an inspection device, the control method comprising: a reading step of reading, by the reading device, a printed matter on which an image is printed on a recording material by the printing device; an acquisition step of acquiring a misalignment amount of a recording material in a direction perpendicular to a conveyance direction of the recording material used for printing by the printing device; a detection step of detecting an image defect included in the image read in the reading step by the inspection device; a diagnostic step of diagnosing a defective part of the printing device based on a detection result by the detection step, the diagnosing step diagnoses the defective portion based on a detection result of an image defect included in a detection target area determined based on the amount of deviation acquired in the acquiring step; The detection step includes determining a detection target area on the second page based on a position of an image defect on the first page and the amount of deviation.

14. An inspection device comprising: a reading means for reading a printed matter on which an image is printed on a recording material by a printing device; an acquisition unit for acquiring an amount of misalignment of a recording material in a direction perpendicular to a conveyance direction of the recording material used for printing by the printing device; a detection means for detecting an image defect included in the image read by the reading means; a diagnostic means for diagnosing a defective part of the printing device based on a result of detection by the detection means, the diagnosing means diagnoses the defective portion based on a detection result of an image defect included in a detection target area determined based on the amount of deviation acquired by the acquiring means; The inspection device according to claim 1, wherein the detection means determines a detection target area on the second page based on a position of an image defect on the first page and the amount of deviation.

15. 15. The inspection apparatus of claim 14, wherein the detection target area is further determined based on periodic information of components of the printing apparatus.

16. 15. The inspection apparatus according to claim 14, wherein the diagnosing means diagnoses the defect location based on a distance between a plurality of similar image defects detected by the detecting means.

Images