Inspection system

Abstract

To detect contamination generated in an image reading unit that reads an image on a surface on which an image is not formed when one-side printing is performed.SOLUTION: An inspection system comprises: an image formation unit that forms an image on paper; a reading unit that is arranged in downstream of the image formation unit in a conveyance direction of the paper, and reads the paper, the reading unit has an upper surface reading unit which reads an upper surface of the paper conveyed by the reading unit and a lower surface reading unit which reads a lower surface of the paper conveyed by the reading unit; test image formation means that forms a test image on both surfaces of the paper; and diagnosis means that performs diagnosis of the lower surface reading unit on the basis of the test image read by the lower surface reading unit.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an inspection system that inspects an image by reading the image on paper. [Background technology]

[0002] Image forming apparatuses are known that include an image reading unit that forms an image on paper and reads the formed image. The image reading unit is located downstream of the image forming unit in the paper transport direction. This location eliminates the need for the user to take the trouble of carrying the paper with the image formed on it to the image reading unit, thereby reducing the amount of work required.

[0003] An image forming apparatus equipped with an image reading unit performs image diagnosis to check for any defects within the apparatus. The image diagnosis is performed by scanning a test chart. The test chart is read by the image reading unit, and the defective part within the apparatus that causes the image defect is diagnosed from the scanned image data. Patent Document 1 discloses a technology that detects a predetermined pattern within the image data and determines whether the predetermined pattern is caused by the image reading unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-144205 Summary of the Invention [Problem to be solved by the invention]

[0005] The image reading units provided in the inspection system are provided on both the first side of the paper and the second side (the reverse side of the first side), making it possible to read both sides of the paper in a single transport.

[0006] However, the test charts used for image diagnosis are printed on one side, so if there is dirt of the same color as the paper on the image reading unit that reads the side of the single-sided print where no image is formed, the dirt cannot be detected, and the location of the problem within the device cannot be identified.

[0007] Therefore, the object of the present invention is to detect dirt that occurs in an image reading unit that reads the image on the side on which an image is not formed when printing on one side in an inspection system that performs image diagnosis using a test chart. [Means for solving the problem]

[0008] In view of the above problems, the inspection system of the present invention is characterized by comprising an image forming unit that forms an image on paper, a reading unit that is arranged downstream of the image forming unit in the paper transport direction and reads the paper, the reading unit having an upper surface reading unit that reads the upper surface of the paper transported by the reading unit and a lower surface reading unit that reads the lower surface of the paper transported by the reading unit, a test image forming means that forms test images on both sides of the paper, and a diagnostic means that diagnoses the lower surface reading unit based on the test image read by the lower surface reading unit. [Effects of the Invention]

[0009] By detecting dirt that occurs on the image reading unit that reads the image on the side where no image is formed during single-sided printing, the defective area can be identified when performing image diagnosis using a test chart, which can prevent the occurrence of defects in subsequent jobs. [Brief explanation of the drawings]

[0010] [Figure 1] A diagram showing an example of a network configuration including a printing system. [Figure 2] 1 is a cross-sectional view showing an example of the hardware configuration of an image forming apparatus; [Figure 3] Block diagram showing the internal configuration of the image forming device, external controller, and client PC [Figure 4]Flowchart showing the procedure of image diagnosis processing [Figure 5] Flowchart showing the procedure for determining whether the reading unit is dirty [Figure 6] 10 is a flowchart showing the procedure of image diagnosis processing in the second embodiment. [Figure 7] A diagram showing an example of a test image [Figure 8] FIG. 10 is a diagram showing an example of determining whether a reading unit is dirty. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. Note that the same components are given the same reference numerals and the description thereof will be omitted.

[0012] [First embodiment] <System configuration> Fig. 1 is a diagram showing an example of a network configuration including a printing system (image processing system) according to this embodiment. As shown in Fig. 1, an inspection 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.

[0013] The client PC 103 can issue a print instruction to the external controller 102 via the external LAN 104. A printer driver is installed in the client PC 103, and has the function of converting image data to be printed into a page description language (PDL) that can be processed by the external controller 102. A user who wishes to print can issue a print instruction via the printer driver from various applications installed on the client PC 103 by operating the client PC 103. The printer driver transmits PDL data, which is print data, to the external controller 102 based on the print instruction from the user. Upon receiving the PDL data from the client PC 103, the external controller 102 analyzes and interprets the received PDL data. Based on the interpretation result, the external controller 102 performs rasterization processing to generate a bitmap image (print image data) with a resolution matching the image forming apparatus 101, and issues a print instruction by submitting a print job to the image forming apparatus 101.

[0014] Next, the image forming apparatus 101 will be described. In the image forming apparatus 101, devices with multiple different functions are connected and configured to be capable of complex printing processes such as bookbinding. The image forming apparatus 101 has an image forming section 107 (image forming section), a reading unit 108, a stacker 109, and a finisher 110. Each module will be described below.

[0015] The image forming unit 107 prints an image in accordance with a print job and ejects the printed recording material. The printed recording material ejected from the image forming unit 107 is transported inside each device in the order of the reading unit 108, stacker 109, and finisher 110. In this embodiment, the image forming device 101 of the inspection system 100 is an example of an image forming device, but the image forming unit 107 included in the image forming device 101 may also be referred to as the image forming device. The image forming unit 107 forms (prints) an image using toner (color material) on the recording material fed and transported from a paper feed unit arranged below the image forming unit 107.

[0016] The reading unit 108 is a device that diagnoses whether or not there is a defect in the image forming apparatus 101 based on the printed recording material on which an image has been printed by the image forming unit 107 and which has been transported through a transport path. Specifically, the reading unit 108 reads the image printed on the transported printed recording material and performs diagnosis from the obtained read image. The defect is diagnosed by extracting a diagnosis area from the read image and checking the difference in read signal values ​​within the extracted diagnosis area. Detailed processing by the diagnosis unit will be described later. Note that the use of the diagnosis unit is not limited to the example described above. The diagnosis unit may also be equipped with an inspection function that inspects the printed recording material for printing defects.

[0017] The stacker 109 is a device capable of stacking a large number of printed recording materials. The finisher 110 is a device capable of performing finishing processes such as stapling, punching, and saddle stitching on the conveyed printed recording materials.

[0018] The recording material processed by the finisher 110 is discharged to a predetermined discharge tray.

[0019] 1, an external controller 102 is connected to the image forming apparatus 101, but this 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 and rasterization of the print data are performed by the image forming apparatus 101.

[0020] <Hardware Configuration of Image Forming Apparatus 101> 2 is a cross-sectional view showing an example of the hardware configuration of the image forming apparatus 101. A specific example of the operation of the image forming apparatus 101 will be described below with reference to FIG.

[0021] <Description of the paper feed deck> The image forming unit 107 is provided with a plurality of paper feed decks. In this embodiment, six types of decks are provided: paper feed decks 361, 362, 363, 364, 365, and 366. Each paper feed deck stores various recording materials (paper). 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.

[0022] The paper size is automatically acquired by reading the position of a guide (not shown) inside the paper feed deck with a sensor. Other information is acquired by the user selecting and inputting it from a paper information change screen (described later). Note that, although the present embodiment has been described as an example in which only some of the paper information is acquired by a sensor provided in the paper feed deck, this is not limited to the above example. For example, a configuration may be adopted in which a sheet of paper stored in the paper feed deck is passed through, and the paper information is determined based on the image read by a reading device (described later).

[0023] Each of the image forming stations 304 to 307 includes a photosensitive drum (photoconductor) and forms 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.

[0024] 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 toner images transferred onto the intermediate transfer belt 308 are transported to a secondary transfer position 309 as the intermediate transfer belt 308 rotates. At the secondary transfer position 309, the toner image is transferred from the intermediate transfer belt 308 onto the recording material transported along the transport path 303 (secondary transfer). After the secondary transfer, the recording material is transported 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 as it passes between these rollers, thereby fixing the toner image to the recording material. After passing through the fixing unit 311, the recording material is transported via a transport path 312 to a connection point 315 between the image forming unit 107 and the reading unit 108. In this manner, a color image is formed (printed) on the recording material.

[0025] If further fixing processing is required depending on the type of recording material, the recording material that has passed through fixing unit 311 is guided to conveyance path 314 provided with fixing unit 313. Fixing unit 313 performs further fixing processing on the recording material conveyed along conveyance path 314. The recording material that has passed through fixing unit 313 is conveyed to connection point 315. Furthermore, if an operating mode for double-sided printing is set, an image is printed on the first side of the recording material, and the recording material conveyed along conveyance path 312 or conveyance path 314 is guided to reversing path 316. The recording material that has been reversed by reversing path 316 is guided to double-sided conveyance path 317 and conveyed to secondary transfer position 309. As a result, a toner image is transferred to the second side of the recording material, which is opposite to the first side, at secondary transfer position 309. Thereafter, the recording material passes through fixing unit 311 (and fixing unit 313), completing the formation of a color image on the second side of the recording material. The reverse path 316 is disposed upstream of the reading unit 108 and downstream of the image forming unit 107 in the paper transport direction.

[0026] After the image formation (printing) in the image forming section 107 is completed, the printed recording material is conveyed to the connection point 315 and then conveyed into the reading unit .

[0027] The reading unit 108 includes an upper surface reading unit 331 and a lower surface reading unit 332, each having a contact image sensor (CIS), on a transport path 330 along which the printed recording material from the image forming unit 107 is transported. The upper surface reading unit 331 and the lower surface reading unit 332 are disposed in positions facing each other across the transport path 330. The upper surface reading unit 331 and the lower surface reading unit 332 are configured to read the upper surface (first surface) and the lower surface (second surface), respectively, of the paper being transported within the reading unit 108. Note that the upper surface reading unit 331 and the lower surface reading unit 332 may be configured with a charge coupled device (CCD) or a line scan camera instead of a CIS, for example.

[0028] The reading unit 108 performs image diagnosis (diagnostic means) to determine whether or not there is a defect in the image forming apparatus 101 based on the image printed on the printed recording material being transported on the transport path 330. Specifically, the reading unit 108 performs a reading process to read the image on the printed recording material using the upper surface reading unit 331 and the lower surface reading unit 332 at the timing when the printed recording material being transported reaches a predetermined position.

[0029] The reading unit 108 performs image diagnostic processing based on a user instruction. The image diagnostic processing is preferably performed, for example, before the start of printing or when printing defects continue. The recording materials that have passed through the reading unit 108 are transported to a stacker 109 in order.

[0030] The stacker 109 includes a stack tray 341 as a tray on which printed recording materials conveyed from the reading unit 108, which is disposed upstream in the conveying direction of the printed recording materials, are stacked. The printed recording materials that have passed through the reading unit 108 are conveyed along a conveying path 344 within the stacker 109. The printed recording materials conveyed along the conveying path 344 are guided to a conveying path 345, whereby the printed recording materials are stacked on the stack tray 341.

[0031] The stacker 109 further includes an escape tray 346 as a paper discharge tray. In this embodiment, the escape tray 346 is used to discharge recording materials on which a test chart used for image diagnosis by the reading unit 108 has been printed. Printed recording materials conveyed along the conveying path 344 are guided to a conveying path 347 and conveyed to the escape tray 346. Printed recording materials conveyed in the stacker 109 without being stacked or discharged are conveyed via a conveying path 348 to the subsequent finisher 110.

[0032] The stacker 109 further includes an inverting unit 349 for inverting the orientation of the printed recording material being conveyed. The inverting unit 349 is used, for example, to make the orientation of the recording material input into the stacker 109 the same as the orientation of the printed recording material when it is stacked on the stack tray 341 and output from the stacker 109. Note that the inverting operation by the inverting unit 349 is not performed on printed recording materials that are not stacked in the stacker 109 but are conveyed to the finisher 110.

[0033] The finisher 110 executes a finishing function specified by a user on printed recording materials conveyed from the reading unit 108, which is disposed upstream in the conveyance direction of the printed recording materials. In this embodiment, the finisher 110 has finishing functions such as a stapling function (one-point or two-point binding), a punching function (two-hole or three-hole), and a saddle stitch binding function. The finisher 110 has two paper output trays 351 and 352. When a finishing process is not performed by the finisher 110, printed recording materials conveyed to the finisher 110 are discharged to the paper output tray 351 via a conveying path 353. When a finishing process such as stapling is performed by the finisher 110, printed recording materials conveyed to the finisher 110 are guided to a conveying path 354. The finisher 110 uses a finishing processing unit 355 to perform a finishing process specified by the user on the printed recording material being transported along the transport path 354, and discharges the printed recording material after the finishing process has been performed onto a paper output tray 352.

[0034] <Functional configuration diagram> FIG. 3 is a schematic functional block diagram of the image forming apparatus 101, the external controller 102, and the client PC 103. As shown in FIG.

[0035] The image forming unit 107 of the image forming apparatus 101 includes a communication I / F (interface) 201, a network I / F 204, a video I / F 205, a CPU 206, a memory 207, an HDD unit 208, and a UI display unit 225. The image forming unit 107 also includes an image processing unit 202 and a print unit 203. These are connected to each other via a system bus 209 so as to be able to send and receive data. The communication I / F 201 is connected to the reading unit 108, the stacker 109, and the finisher 110 via a communication cable 260. The CPU 206 communicates with each device via the communication I / F 201 to control the respective devices. The network I / F 204 is connected to the external controller 102 via the internal LAN 105 and is used for communicating 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 communicating data such as image data. Note that the image forming unit 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. The HDD unit 208 stores various programs and data. The CPU 206 controls the overall operation of the image forming unit 107 by executing the programs stored in the HDD unit 208. The memory 207 stores programs and data required for the CPU 206 to perform 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. For example, it accepts various instructions from the user, such as instructions to execute a diagnosis, settings, and paper information settings.

[0036] The reading unit 108 includes a communication I / F 211, a CPU 214, a memory 215, an HDD unit 216, an upper surface reading unit 331, a lower surface reading unit 332, and a UI display unit 241. These devices are connected via a system bus 219 so as to be able to send and receive data to and from each other. The communication I / F 211 is connected to the image forming unit 107 via a communication cable 260. The CPU 214 performs communication necessary for controlling the reading unit 108 via the communication I / F 211. The CPU 214 controls the operation of the reading unit 108 by executing a control program stored in the memory 215. The memory 215 stores a control program for the reading unit 108. The upper surface reading unit 331 and the lower surface reading unit 332 read images on the conveyed recording material in accordance with instructions from the CPU 214. The CPU 214 diagnoses whether or not there is a defect in the image forming apparatus 101 based on the diagnostic read images read by the upper surface reading unit 331 and the lower surface reading unit 332. The UI display unit 241 is used to display the diagnosis results, setting screens, etc. The operation unit 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 reading unit 108 and issuing instructions to perform image diagnosis. The HDD unit 216 stores various setting information and image data required for image diagnosis. The various setting information and image data stored in the HDD unit 216 can be reused.

[0037] The stacker 109 controls whether the printed recording material conveyed along the conveying path is discharged to a stack tray, discharged to an escape tray, or conveyed to a finisher 110 connected downstream in the conveying direction of the printed recording material.

[0038] The finisher 110 controls the transport and discharge of printed recording materials, and performs finishing processes such as stapling, punching, or saddle stitching.

[0039] 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 via a system bus 259 so that they can send and receive data to and from each other. The CPU 251 executes programs stored in the HDD unit 253 to control the overall operation of the external controller 102, such as receiving print data from the client PC 103, RIP processing, and sending 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.

[0040] 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 about applications currently running 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 communicating 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 communicating data such as print instructions. The external controller 102 is configured to be able to communicate with the image forming unit 107, the reading unit 108, the stacker 109, and the finisher 110 via the internal LAN 105 and a 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 communicating data such as image data (print data).

[0041] 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 that they can send and receive data to and from each other. The CPU 261 controls the operation of each device via the system bus 269 by executing a program stored in the HDD unit 263. This enables various processes to be performed by the client PC 103. For example, the CPU 261 generates print data and issues print instructions 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.

[0042] 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 the 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.

[0043] <Imaging diagnosis> The processing of image diagnosis using a test chart image according to this embodiment (hereinafter also referred to as test image diagnosis) will be described with reference to the drawings. FIG. 4 is a flowchart showing the print operation executed by the image forming unit 107 and the procedure of image diagnosis processing executed by the reading unit 108. Note that FIG. 4 shows the overall flow from the work before starting image diagnosis to the execution of diagnosis. 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. 4 is executed by the CPU 206 of the image forming unit 107 and the CPU 214 of the reading unit 108.

[0044] In S401, the inspection system 100 receives an instruction for test image diagnosis from a user or a service person via the UI display unit 241, which also serves as an operation unit. When the inspection system 100 receives the instruction for test image diagnosis, a test image is formed by a test image forming means. Details will be described later.

[0045] In this embodiment, the timing for starting the image diagnostic processing may be, for example, after startup when the power to the main body is turned on. After startup, a notification prompting the user to start the diagnosis is displayed on one or more of the UI display unit 241, the display unit 254 of the external controller 102, and the UI display unit 225 of the image forming unit 107, prompting the user to instruct the user to start the diagnosis. The timing for starting the image diagnostic processing is not limited to the above example. If the device also has an inspection function for inspecting printed recording materials for print defects, the user may be prompted to start the image diagnostic processing if the inspection function detects consecutive defects. Furthermore, a timer may be set to display a notification prompting the user to perform the image diagnostic processing at a time other than when the main body is started, and the notification may be displayed at the set time.

[0046] In S402, a test image is formed by the test image forming means. The CPU 251 of the external controller 102 reads a previously saved test chart, rasterizes it into a bitmap, and creates the rasterized bitmap of the test chart as a reference image. The test chart is an image for diagnosing faults in the image forming apparatus. FIG. 7 shows an example of a test chart used in the image diagnosis processing of this embodiment. The single-sided test chart 701 shows an example of single-sided printing in which a test image is formed on one side of a sheet of paper and no image is formed on the other side. In the single-sided test chart 701, a test image is formed on the entire image-formable area by the image forming unit 107. The test image 711 shows an area in which an image is formed using color materials. For example, the test image 711 uses a single-color image with an area ratio of 50%, and four types of test charts are printed, one for each CMYK color.

[0047] The double-sided test chart 702 in FIG. 7 is an example of a test chart for detecting contamination of the reading unit. The double-sided test chart 702 is printed on both sides of a recording material. The double-sided test chart 702 has a non-image portion 721 and a test image 722. The non-image portion 721 is an area located at the leading edge of the double-sided test chart 702 in the transport direction, where no image is formed. The test image 722 is an area located other than the leading edge of the test chart 800 in the transport direction, where an image is formed using a color material. The test image 722 is printed, for example, using a single K color with an area ratio of 50%. Here, the non-image portion 721 is intended to facilitate detection of contamination of the reading unit of a color different from the recording material, while the test image 722 is intended to facilitate detection of contamination of the reading unit of a color similar to the recording material. By reading the test image 722 with the lower surface reading unit 322, contamination of a color similar to that of the paper can be detected.

[0048] The CPU 251 transmits the rasterized test chart bitmap data from the video I / F 258 to the video I / F 205 of the image forming unit 107 via the video cable 106. The CPU 206 of the image forming unit 107 performs halftone processing on the test chart bitmap data received via the video I / F 205, and the print unit 203 prints the test chart based on the image data after halftone processing. To facilitate the detection of periodically occurring image defects, a single-sided test chart 701 is printed first, followed by a double-sided test chart 702. Note that the configuration of the test chart is merely an example and is not limited to the above example. As long as defects in the printed area are apparent using a differential image (described later), the ratio or area ratio of the image area to the non-image area may be different, and the image area may use two or more color materials. Furthermore, the double-sided test chart 702 may be configured to have two or more image areas of different colors instead of having a non-image area and an image area, so that dirt on the reading area that is difficult to detect in one image area can be easily detected in the other image area. Also, in this embodiment, only the last test chart is configured to be double-sided printed, but all pages may be double-sided printed, or only the first and last pages may be double-sided printed.

[0049] In S403, the CPU 214 of the reading unit 108 executes processing to read the printed test chart using the upper surface reading section 331 and the lower surface reading section 332. The read image of the test chart is saved as a diagnostic image in the HDD section 216 of the reading unit 108. Once the diagnostic image is saved, the process proceeds to S404. The lower surface reading section 332 reads the test image 722 formed on the lower surface of the double-sided test chart 702.

[0050] In S404, the CPU 214 compares the reference image with the scanned image to determine defects in the printing unit. In this embodiment, the reference image is compared with the scanned image to calculate a difference value. If the calculated difference value exceeds a predetermined threshold, a difference is determined to exist, and 1 is set as the differential image data. Conversely, if the calculated difference value is below the threshold, 0 is set as the differential image data. Note that the method for calculating the differential image data is not limited to the above example. In this embodiment, an example is described in which the reference image is compared with the scanned image to calculate the difference value. However, the difference value may be calculated by calculating an average value from the scanned image and using it as a reference signal, or a value assumed as a reference signal may be stored in advance in the HDD unit 216. Furthermore, a correction unit may be provided to correct the nonlinearity between the signal value and luminance of the scanned image acquired by the scanning unit, and the signal value of the scanned image may be corrected before calculating the differential image data. The differential image data, which is binary data indicating whether or not a difference exists, is stored in the HDD unit 216, and the process proceeds to S405.

[0051] When the creation of the differential image data is completed, in S405, the CPU 214 determines whether the image forming apparatus 101 is normal. This determination is made based on whether data including a 1 exists in the differential image data. If the CPU 214 obtains a determination result that the image forming apparatus 101 is normal (YES in S405), the process proceeds to S411. In S411, the CPU 214 displays the diagnosis result "No problem" indicating that the diagnosis result is normal on the UI display unit 241 of the reading unit 108. On the other hand, if the CPU 214 obtains a determination result that the image forming apparatus 101 is not normal (the differential image data includes a 1) (NO in S405), the process proceeds to S406. In the process from S406, a part in the image forming apparatus 101 that is experiencing a problem is identified based on the read image data and differential image data, and instructions are given to take action.

[0052] In S406, the CPU 214 extracts feature quantities from the scanned image data and differential image data to identify defective parts in the image forming unit 107. Difference feature extraction is performed from the scanned image corresponding to the differential region determined to have a difference in S404 from the differential image data. The feature information of the differential region obtained through this extraction process includes, for example, color material information indicating which color (yellow, magenta, cyan, or black) the defect occurs in. Also included is contrast information, which expresses the defect density contrast as a difference in the darker direction (positive direction) or the lighter direction (negative direction) using positive or negative values. Furthermore, size information, such as the width (size in the main scanning direction) and height (size in the sub-scanning direction) of the defect, and shape information, such as the shape of a dot, vertical streak, or horizontal streak, are acquired. In this embodiment, an example is described in which the shape information is acquired based on the aspect ratio of the width and height of the acquired size information. Specifically, if the aspect ratio calculated by dividing the width by the height exceeds a predetermined threshold, the shape is determined to be a horizontal streak. If the aspect ratio is below a threshold, the shape is determined to be a vertical streak, and if it does not fit either category, it is determined to be a dot. Note that the acquisition of shape information is not limited to the above example, and any method that can determine the shape of the defect, such as a dot, horizontal streak, or vertical streak, may be used. For example, a width greater than or equal to a threshold may be determined to be a horizontal streak, a height greater than or equal to a threshold may be determined to be a vertical streak, and anything else may be determined to be a dot. Furthermore, since defects may be interrupted or absent depending on the pattern in the image portion of the user image, the threshold may be changed depending on the pattern, or interrupted streaks may be merged before being determined. Other examples of information that may be used include coordinate information indicating the position in a direction perpendicular to the transport direction of the test chart in the image forming unit 107, and periodic information indicating that defects with similar characteristics occur periodically in the transport direction of the test chart in the image forming unit 107. The extracted features are saved in the HDD unit 216, and the process proceeds to S407.

[0053] In S407, the CPU 214 determines, based on the feature information of the difference region obtained in S406, whether the image defect is caused by either the upper surface reading unit 331 or the lower surface reading unit 332. Details will be described later.

[0054] In S408, the CPU 214 identifies the part among the image forming unit 107, the upper surface reading unit 331, and the lower surface reading unit 332 that is the cause of the image defect based on the characteristic information of the difference region and the determination result of whether or not it is dirt on the reading unit. From the difference region, a combination of the same color with high similarity is selected, and which part is defective is identified based on the periodic information of the selected combination. For an image defect determined to be dirt on the reading unit in S407, no determination is made on other parts. Furthermore, an image defect determined to be dirt on the reading unit at the same main scanning position is determined to be dirt on the reading unit.

[0055] In S409, the CPU 214 determines how to address the image defect based on the part identified in S407 as the cause. The addressable measures are divided into those that are automatically reversible and those that are not. Examples of automatically reversible measures include measures that are automatically reversible by the image forming unit 107, such as cleaning the wires and grids of the corona chargers, which are means for charging the photosensitive drums provided in the image forming stations 304 to 307 of the image forming unit 107. Examples of measures that are not automatically reversible include the following two examples. First, measures that require user intervention, such as cleaning the reading glass surfaces of the upper surface reading unit 331 and the lower surface reading unit 332 of the reading unit 108 or adjusting the recording material to be used, or measures that require service technician intervention, such as replacing parts. Second, measures that require intervention, such as reading abnormalities in the image reading unit or fibers or foreign matter present in the recording material before image formation. If an automatically reversible measure is found, the system may be configured to execute automatic recovery control.

[0056] In S410, the CPU 214 determines whether the action determined in S409 is an action that can be automatically restored. If the CPU 214 obtains a determination result that the action determined is an action that can be automatically restored (YES in S410), the process proceeds to S412.

[0057] In S412, the CPU 214 executes automatic recovery control to deal with the cause of the image defect.

[0058] On the other hand, if the CPU 214 obtains a determination result that the determined response is not an automatically recoverable response (NO in S410), the process proceeds to S413. In S413, the CPU 214 displays the image diagnosis result and the response method on the UI display section 241 of the reading unit 108. When any one of the processes in S411, S412, and S413 described above is completed, the flow (image diagnosis process) shown in FIG. 4 ends.

[0059] <Detection of dirt on the reading section> The dirt determination process of the reading unit (scanner) according to this embodiment will be described with reference to FIGS.

[0060] FIG. 8 shows examples of scanned images during double-sided printing, with FIG. 8(a) showing an example of an image scanned by the upper scanning unit 331 and FIG. 8(b) showing an example of an image scanned by the lower scanning unit 332. Streak 801 is an example of an image defect caused by dirt on the upper scanning unit 331. Dirt on the upper scanning unit 331 only appears in the image scanned by the upper scanning unit 331. In a configuration in which an image is scanned by a CIS during transport, as in this embodiment, dirt on the scanning unit results in a streak-like image defect parallel to the transport direction, such as streak 801. Dirt on the scanning unit refers to paper powder or dust adhering to the scanning surface of the CIS, and the color of the image defect varies depending on the type of dirt. Streak 802 and streak 803 are examples of streak-like image defects caused by the same abnormality in the image forming unit 107. When a double-sided printing operation mode is set, after an image is printed on the first side, it is reversed by the reverse path 316, and the second side is printed using the same parts used to print the first side. Therefore, for example, if there is an abnormality in the corona charger, which is the charging means for the photosensitive drum provided in the image forming stations 304 to 307 of the image forming unit 107, and a streak-like image defect occurs, the image defect will occur at nearby main scanning positions on both sides, as shown in 802 and 803.

[0061] 5 is a flowchart showing the procedure of the dirt determination process for the reading unit executed by the reading unit 108. The process of each step in FIG.

[0062] In S501, the CPU 214 reads and acquires the feature amount of the difference extracted in S406 from the HDD unit 216.

[0063] In S502, the CPU 214 determines whether the sheet for which the difference occurred was printed in a double-sided printing mode. This determination may be made from the processing information of the print job, or, in the case of a test chart, from the page number. If the CPU 214 determines that the sheet was printed in a double-sided printing mode (YES in S502), the process proceeds to S503.

[0064] In S503, the CPU 214 refers to the feature amount of the difference and determines whether the coin has been determined to have a vertical stripe shape. If the result of the determination is that the coin has a vertical stripe shape (YES in S503), it is determined that there is a possibility that the reading unit is dirty, and the process proceeds to S504.

[0065] In S504, the CPU 214 determines whether an image defect occurs at the same position on the opposite side of the image defect of interest. For example, if the main scanning position of streak 801 in FIG. 8A is x1, it checks whether an image defect occurs at the main scanning position x1 on the opposite side of FIG. 8B. Since no image defect occurs at the same main scanning position x1 on the opposite side of streak 801, the result is NO. Since streak 802 occurs at the same main scanning position x2 on the opposite side of streak 803, the result is YES. The determination of whether the positions are the same takes into account errors and determines that they are the same if they are within a certain threshold. If the determination result indicates that no image defect occurs at the same position on the opposite side of streak 801 (YES in S504), the process proceeds to S505. If the determination result indicates that no image defect occurs at the same position on the opposite side of streak 801 (NO in S504), the process proceeds to S506, where it is determined that the defect is in the reading unit.

[0066] An example will be given of streak 801 in Figure 8(a). Streak 801 is an example of an image defect caused by dirt on the upper surface reading unit 331. If a streak like streak 801 does not appear on the surface of the paper read by the lower surface reading unit 332, streak 801 is determined to be a defect caused by the upper surface reading unit 331. On the other hand, if a streak appears on the surface of the paper read by the lower surface reading unit 332 but does not appear on the surface of the paper read by the upper surface reading unit 331, it is determined to be a defect caused by the lower surface reading unit 332.

[0067] In S505, the CPU 214 refers to the feature amount acquired in S501 and determines whether an image defect occurring at the same position on the opposite surface is a defect similar to the image defect currently being considered. Here, if the defects have the same color and shape, they are determined to be similar defects. Note that other feature amounts may also be used for the determination. For example, the determination may be made based on the thickness of a streak-like defect, the size or contrast of a dot-like defect, or the defect may be extracted and the similarity calculated by image comparison. If the determination result indicates that the defects are not similar defects (YES in S505), it is determined that the causes of these image defects are different, and the process proceeds to S506, where it is determined that the defect is a defect in the reading unit.

[0068] In S507, the CPU 214 determines whether the reading unit has been checked for dirt on all image defects. If the checking is complete (YES in S507), the process ends. If the checking is not complete, the process proceeds to S501, where the next image defect is checked. In this way, if it is determined that the same defect has occurred on both sides of a sheet of paper on which a test image has been printed, it is determined that the problem is not with the reading unit but with the image forming unit.

[0069] If a defect location is identified as a result of diagnosing the test image through image diagnosis, the inspection system 100 notifies the user of this fact. As a means for notifying the user, it is preferable to configure the inspection system 100 to display a message on an operation unit that can be operated by the user, such as the UI display unit 225 or the display 241.

[0070] As described above, even if the dirt on the reading device is the same color as the background material and is unlikely to be visible on the background material, it is possible to accurately determine whether the dirt is on the reading device or due to a defect in the image forming device.

[0071] [Second embodiment] Image diagnosis processing according to this embodiment will be described. In the first embodiment, image diagnosis processing using a test chart was described. However, the effects of the present invention are not limited to the above example. For example, a configuration may be adopted in which image diagnosis is performed using a user image when the user image is printed. When the user image is printed, it is not necessarily the case that the image includes pages for which the above-mentioned reading unit dirt determination processing is possible. Therefore, even in such cases, control is performed to change the job information so that the above-mentioned reading unit dirt determination processing is possible, and dirt on the reading unit is determined.

[0072] The processing of image diagnosis using a user image according to this embodiment (hereinafter also referred to as user image diagnosis) will be described with reference to the drawings. FIG. 6 is a flowchart showing the print operation executed by the image forming unit 107 and the procedure of image diagnosis processing executed by the reading unit 108. Note that FIG. 6 shows the overall flow from the work before starting image diagnosis to the execution of diagnosis. The processing of each step in FIG. 6 is executed by the CPU 206 of the image forming unit 107 and the CPU 214 of the reading unit 108. Note that the same processing as that described above will be denoted by the same reference numerals and description thereof will be omitted.

[0073] In S601, the inspection system 100 receives an instruction to start user image diagnosis from a user or serviceman via the UI display unit 241, which also serves as an operation unit. In this embodiment, the timing to start user image diagnosis processing is when a print job is executed. Note that a configuration may be adopted in which whether or not to execute user image diagnosis is set in the job settings, and user image diagnosis is started only when the setting is ON. Furthermore, the start timing of image diagnosis processing is not limited to the above example. For example, a configuration may be adopted in which user image diagnosis is started when proof printing is executed.

[0074] In S602, the inspection system 100 determines whether the print job includes a page for which reading unit contamination determination processing is possible. Here, a page for which reading unit contamination determination processing is possible means that there is a page for which images are formed on both the front and back sides. Here, as long as there is a page for which images are formed on both the front and back sides, the pages do not have to be on the same sheet. Here, it may also be determined that the pattern is one for which reading unit contamination can be detected. A pattern for which reading unit contamination can be detected means, for example, that there is an image portion with an area and density that allows for the detection of white streak-like defects caused by reading unit contamination in the difference calculation processing described below, and a non-printed portion with an area that allows for the detection of black streak-like defects caused by reading unit contamination. If it is determined that there is a page for which reading unit contamination determination processing is possible (YES in S602), the process proceeds to S402. If it is determined that there is no page for which reading unit contamination is possible (NO in S602), the process proceeds to S603.

[0075] In S603, the inspection system 100 modifies the job information to determine whether the reading unit is dirty. If the result of the determination in S602 indicates that there are no pages for which images are formed on both the front and back sides, a page with only a non-image portion is added to the opposite side of the last page of the print job, and the operation mode for the last page is controlled to be double-sided printing. Note that a page with only a non-image portion may be added so that the operation mode for the first page, all pages, or the first and last pages is double-sided printing. Alternatively, a method may be used in which the print sides are swapped during the job and then inverted by the inverting unit 349 of the stacker 109 to align the print sides. Furthermore, a sheet for detecting dirt on the reading unit, such as the double-sided test chart 702 shown in FIG. 7, may be added to the first or last sheet of the job.

[0076] As described above, even when performing image diagnosis when printing a user image that does not include double-sided pages, it is possible to accurately determine whether the reading device is dirty or whether the image is dirty due to defects in the image forming device. [Explanation of symbols]

[0077] 100 Inspection Systems 101 Image forming device 102 External Controller 107 Image forming unit 331 Top reading unit 332 Bottom reading unit

Claims

1. an image forming unit that forms an image on paper; a reading unit disposed downstream of the image forming unit in a paper transport direction, the reading unit reading the paper; the reading unit has an upper surface reading section that reads the upper surface of the paper being transported by the reading unit, and a lower surface reading section that reads the lower surface of the paper being transported by the reading unit, a test image forming means for forming test images on both sides of a sheet of paper; a diagnostic unit for diagnosing the lower surface reading unit based on the test image read by the lower surface reading unit; An inspection system comprising:

2. the test image forming means is capable of printing the test image on one side; 2. The inspection system according to claim 1.

3. When the test image is formed by the test image forming means, the test image is formed by single-sided printing and double-sided printing.

3. The inspection system according to claim 2.

4. When the test image is formed by the test image forming means, the last sheet of paper on which the test image is formed by the test image forming means is printed on both sides.

4. The inspection system according to claim 3.

5. When the test image is formed by the test image forming means, the first paper on which the test image is formed by the test image forming means is printed on both sides.

4. The inspection system according to claim 3.

6. the diagnostic means diagnoses the top surface reading unit based on the test image read by the top surface reading unit.

2. The inspection system according to claim 1.

7. the diagnostic unit diagnoses the image forming unit based on the test images read by the upper surface reading unit and the lower surface reading unit.

7. The inspection system according to claim 6.

8. an operation unit that allows a user to operate settings related to the inspection system; a notification means for notifying the operation unit of a location where a problem has occurred based on the diagnosis; 8. The inspection system of claim 7, further comprising:

9. If the same defect is found in both the test image read by the upper surface reading unit and the test image read by the lower surface reading unit, the diagnostic means diagnoses that a malfunction has occurred in the image forming unit.

9. The inspection system of claim 8.

10. If there is a defect only in the test image read by the lower surface reading unit out of the test image read by the upper surface reading unit and the test image read by the lower surface reading unit, the diagnostic means diagnoses that a defect has occurred in the lower surface reading unit.

10. The inspection system of claim 9.

11. the paper on which the test image is formed and which is read by the lower surface reading unit has the test image and a non-image portion on which the test image is not formed; 2. The inspection system according to claim 1.

12. the test image read by the lower surface reading unit is formed using black toner; The inspection system of claim 11 .

13. an image forming apparatus having the image forming section and the reading unit; a controller that instructs the image forming device to output the test image; 2. The inspection system according to claim 1.

Images