Inspection device, image forming device, inspection device control method, and program

Abstract

Properly calibrate your inspection equipment. [Solution] The inspection device includes an inspection means that reads paper with an image formed on it that is transported from the image forming means using a reading means and detects abnormalities in the formed image by comparing it with a reference image, a storage means that stores calibration data, a judgment means that judges whether to perform calibration to adjust the reference image or the formed image used by the inspection means, a calibration execution means that performs calibration and stores the calibration data in the storage means if it is determined that calibration should be performed, a reading means that reads out the calibration data from the storage means if it is determined that calibration should not be performed, and an adjustment means that adjusts the reference image or the formed image based on the calibration data stored in the storage means or the calibration data obtained by performing calibration.

Description

[Technical Field]

[0001] The present invention relates to an inspection device, an image forming device, a control method for an inspection device, and a program for inspecting whether or not a printing abnormality has occurred in a printed matter output by a printing device. [Background technology]

[0002] In printed materials printed and output by a printing device, coloring materials such as ink and toner may adhere to unintended locations on the paper, resulting in stains. Furthermore, in some cases, the coloring materials on the printed material do not adhere sufficiently to the areas where an image should be formed, resulting in color loss, where the color of those areas is lighter than the original color. Such printing defects, such as stains and color loss, reduce the quality of printed materials. Therefore, it is necessary to inspect printed materials for such printing defects and ensure the quality of printed materials.

[0003] Visual inspection by an inspector to check for printing anomalies requires a lot of time and cost, so an inspection system that performs inspection automatically without relying on visual inspection has been proposed. Specifically, the system aligns the digital image used for printing (reference image) with the scanned image obtained by scanning the printed matter, and performs image matching and judgment processing to detect the presence or absence of printing anomalies and judge the image quality of the printed matter.

[0004] Patent Document 1 proposes a method for an image inspection device that converts a digital image used for printing into a reference image and compares it with a scanned image of the printed matter, and when a variation in color value is detected, prompts the user to calibrate the inspection device.The proposed method makes it possible to notify the user that calibration of the inspection device is necessary when a variation in color value occurs. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-187585 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the proposed inspection device only detects variations in color values ​​before notifying the user of the need for calibration, so it is not possible to notify the user of the need for calibration before variations in color values ​​actually occur. Depending on the characteristics of the paper being printed on, variations in color values ​​may be predictable before printing. In such cases, it is not possible to notify the user of the need for calibration, which can result in printing continuing despite abnormal printing. Furthermore, variations in print position and other factors other than color values ​​are not taken into consideration when performing calibration.

[0007] An object of the present invention is to properly calibrate an inspection device. [Means for solving the problem]

[0008] The inspection device of the present invention comprises an inspection means that reads, by a reading means, paper on which an image is formed and which is transported from an image forming means, and detects abnormalities in the formed image by comparing it with a reference image; a storage means that stores calibration data; a judgment means that judges whether to perform calibration to adjust the reference image or the formed image used by the inspection means; a calibration execution means that, if it is determined that calibration is to be performed, performs calibration and stores the calibration data in the storage means; a reading means that, if it is determined that calibration is not to be performed, reads out the calibration data from the storage means; and an adjustment means that adjusts the reference image or the formed image based on the calibration data stored in the storage means or the calibration data obtained by performing the calibration. [Effects of the Invention]

[0009] The inspection device of the present invention allows the inspection device to be properly calibrated. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an example of a system configuration including an inspection apparatus according to an embodiment. [Figure 2] FIG. 1 is a block diagram illustrating a hardware configuration of an image forming apparatus according to an embodiment. [Figure 3] FIG. 2 is a diagram illustrating a mechanism of an image forming apparatus according to an embodiment. [Figure 4] FIG. 1 is a schematic explanatory diagram of the internal configuration of an inspection device according to an embodiment. [Figure 5] FIG. 2 is a block diagram illustrating the configuration of an inspection device control unit of an inspection device according to an embodiment. [Figure 6] FIG. 3 is a diagram illustrating a control flow of an inspection apparatus according to an embodiment. [Figure 7] 10 is an example of a UI according to an embodiment. [Figure 8] 10 is an example of a calibration chart according to an embodiment. [Figure 9] FIG. 4 is a diagram illustrating a flow of distortion information generation processing according to an embodiment. [Figure 10] FIG. 10 is a diagram illustrating the flow of alignment processing according to an embodiment. [Figure 11] FIG. 10 is a schematic diagram showing the arrangement of control points in the distortion information generation process. [Figure 12] 5A and 5B are schematic diagrams illustrating updating of control points in the distortion information generation processing. [Figure 13] FIG. 3 is a diagram illustrating a control flow of an inspection apparatus according to an embodiment. [Figure 14] 10 is an example of a confirmation screen according to an embodiment. [Figure 15] FIG. 3 is a diagram illustrating a control flow of an inspection apparatus according to an embodiment. [Figure 16] FIG. 3 is a diagram illustrating a control flow of an inspection apparatus according to an embodiment. [Figure 17] 10 shows an example of a calibration interval setting screen of an inspection apparatus according to an embodiment. [Figure 18] FIG. 3 is a diagram illustrating a control flow of an inspection apparatus according to an embodiment. [Figure 19] FIG. 3 is a diagram illustrating a control flow of an inspection apparatus according to an embodiment. [Figure 20] 10 is an example of a UI for selecting an item to be performed in calibration according to an embodiment. [Figure 21] 10 is an example of a UI according to an embodiment. [Figure 22] FIG. 1 is a diagram illustrating a control flow of an inspection apparatus according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0012] First Embodiment A printing system including an inspection device according to this embodiment will be described with reference to Fig. 1. The printing system includes an image forming apparatus 101, an inspection apparatus 102, a finisher 103, a print server 105, and a client PC 106. The image forming apparatus 101, the print server 105, and the client PC 106 are communicatively connected via a network 104. The configuration of the printing system is not limited to that shown in Fig. 1, and the printing system may be connected via any network configuration, such as a LAN, the Internet, or an intranet.

[0013] The image forming apparatus 101 processes various input data and produces a printout. The inspection apparatus 102 receives the printed matter printed and discharged by the image forming apparatus 101 and inspects the contents of the printed matter. The finisher 103 receives the output paper (printed matter) inspected by the inspection apparatus 102 and performs post-processing such as bookbinding.

[0014] The image forming apparatus 101 is connected to an external print server 105 and a client PC 106 via a network 104. The inspection apparatus 102 is connected one-to-one to the image forming apparatus 101 via a communication cable. The finisher 103 is also connected one-to-one to the image forming apparatus 101 via a communication cable separate from the above. The inspection apparatus 102 and the finisher 103 are also connected to each other via a separate communication cable.

[0015] This allows the image forming apparatus 101, the inspection apparatus 102, and the finisher 103 to communicate with each other. The first embodiment illustrates an in-line inspection system that performs image formation, image inspection, and finishing in an integrated manner. In the embodiment illustrated in FIG. 1, the image forming apparatus 101 and the inspection apparatus 102 are described as an in-line inspection system, but this is not intended to limit the present invention, and they may be integrated into a single apparatus. For example, the inspection apparatus 102 may be integrated into the image forming apparatus 101 to form a device that constitutes the image forming apparatus 101. Furthermore, for example, the image forming apparatus 101 may include the inspection apparatus 102 as an inspection unit, and the inspection apparatus 102 may be a separate apparatus from the image forming apparatus 101, or may be integrated into the image forming apparatus 101.

[0016] The hardware configuration of an image forming apparatus 101 according to this embodiment will be described with reference to Fig. 2. This image forming apparatus 101 is an example of the image forming apparatus of the present invention, and includes a controller 201, a printer unit 202, and a UI (user interface) unit (operation unit) 203.

[0017] A client PC 106 or print server 105 on the network 104 creates PDL data from image data or document data using a software application such as a printer driver (not shown). The client PC or print server 105 then transmits the PDL data to the image forming apparatus 101 via the network 104 (e.g., a local area network). In the image forming apparatus 101, a controller 201 receives the transmitted PDL data. The controller 201 is connected to a printer unit 202, and upon receiving PDL data from the client PC 106 or print server 105, the controller 201 converts the PDL data into print data that can be processed by the printer unit 202 and outputs the print data to the printer unit 202.

[0018] The printer unit 202 prints an image based on the print data output from the controller 201. Note that the printer unit 202 according to this embodiment is an electrophotographic printer engine. However, the printing method is not limited to this, and may be, for example, an inkjet method or other method.

[0019] The UI unit 203 is operated by a user and is used by the user to select various functions and give operational instructions. The UI unit 203 includes a display unit with a touch panel on its surface, a keyboard with various keys such as a start key, a stop key, and a numeric keypad, and the like.

[0020] Next, the controller 201 will be described in detail. The controller 201 has a network interface (I / F) unit 204, a CPU 205, a RAM 206, a ROM 208, an image processing unit 209, an engine interface (I / F) unit 207, and an internal bus 210. The various units of the controller 201 are connected to each other via the internal bus 210. The network I / F unit 204 is an interface for receiving PDL data transmitted from the client PC 106 or the print server 105. The CPU 205 controls the entire image forming apparatus 101 using programs and data stored in the ROM 208, and also executes the processes performed by the controller 201, which will be described later.

[0021] The RAM 206 provides a work area used when the CPU 205 executes various processes. The ROM 208 stores programs and data for causing the CPU 205 to execute various processes described below, as well as setting data for the controller 201.

[0022] The image processing unit 209 performs image processing for printing on the PDL data received by the network I / F unit 204 in accordance with settings from the CPU 205, and generates print data that can be processed by the printer unit 202. The image processing unit 209 particularly performs rasterization on the received PDL data to generate image data (RIP data) having multiple color components per pixel.

[0023] Here, multiple color components refer to independent color components in a color space such as RGB (red, green, blue). Image data has, for example, 8-bit (256 gradations) values ​​for each color component per pixel. That is, the image data is multi-valued bitmap data containing multi-valued pixel data. In addition to the image data, rasterization also generates attribute data indicating the attributes of each pixel in the image data. This attribute data indicates the type of object the pixel belongs to, such as text, line, graphic, image, or background. The image processing unit 209 uses the generated image data and attribute data to generate print data by performing image processing such as color conversion from the RGB color space to the CMYK (cyan, magenta, yellow, black) color space and screen processing.

[0024] The engine I / F unit 207 is an interface that transmits print data generated by the image processing unit 209 to the printer unit 202. The internal bus 210 is a system bus that connects the above-mentioned units and transmits control signals and the like.

[0025] The mechanism of the image forming apparatus 101 according to this embodiment will be described with reference to FIG. The image forming apparatus 101 includes a scanner unit 301, a laser exposure unit 302, a photosensitive drum 303, an imaging unit 304, a fixing unit 305, a paper feed / transport unit 306, a paper storage unit 308, and a printer control unit 309 that controls these components. The scanner unit 301 illuminates a document placed on a platen to optically read the document image and converts the image into an electrical signal to create image data. The laser exposure unit 302 directs a beam of light, such as a laser beam, modulated according to the image data onto a rotating polygon mirror 307 that rotates at a constant angular velocity, and irradiates the photosensitive drum 303 as reflected scanning light. The imaging unit 304 includes four development units, one for each color: CMYK (cyan, magenta, yellow, and black). Each development unit rotates the photosensitive drum 303, charges it with a charger, and develops the latent image formed on the photosensitive drum by the laser exposure unit 302 with toner. The toner image is then transferred to paper to form an image. The minute toner particles remaining on the photosensitive drum without being transferred are collected. In this way, the image forming unit 304 realizes image formation by having a series of four developing units (developing stations) for the electrophotographic process.

[0026] The image forming unit 304 has four development units arranged in order: cyan (C), magenta (M), yellow (Y), and black (K). After a predetermined time has elapsed since the start of image formation at the cyan station, the image forming unit 304 sequentially performs image formation operations for magenta, yellow, and black.

[0027] The fixing unit 305 has rollers, belts, etc., and further includes a heat source such as a halogen heater. The fixing unit 305 uses heat and pressure to melt and fix the toner on the paper onto which the toner image has been transferred by the image creating unit 304. When printing on cardboard paper, the speed at which the paper passes through the fixing unit 305 must be, for example, half the normal speed because the paper is thick and has poor thermal conductivity. As a result, when printing on cardboard paper, the paper transport speed of each unit other than the fixing unit 305 is also halved, and the printing speed of the image forming apparatus 101 itself is halved.

[0028] The paper feed / transport unit 306 has one or more paper storage units 308, such as a paper cassette or a paper deck. In response to instructions from the printer control unit 309, the paper feed / transport unit 306 separates one sheet from the multiple sheets stored in the paper storage unit 308 and transports it to the image creation unit 304. Toner images of each color are transferred onto the transported sheet by the developing station described above, and a full-color toner image is finally formed on the sheet. When images are to be formed on both sides of the sheet, the paper that has passed through the fixing unit 305 is controlled to pass through a double-sided transport path 310, which transports the sheet again to the image creation unit 304.

[0029] The printer control unit 309 communicates with the controller 201, which controls the entire image forming apparatus 101, and executes control in accordance with the instructions. The printer control unit 309 also issues instructions to ensure smooth operation in harmony as a whole, while managing the status of each of the above-mentioned scanner, laser exposure, image creation, fixing, and paper feed / transport units.

[0030] The internal configuration of the inspection device 102 according to this embodiment will be described with reference to Figures 4(a) and 4(b). In Figure 4(a), a sheet (printed matter) output from the image forming device 101 is drawn into the inspection device 102 by a paper feed roller 401. Thereafter, the printed matter is read by an imaging unit 403 located on the conveyor belt 402 while being conveyed by the conveyor belt 402. The imaging unit 403 functions as a reading means.

[0031] The imaging unit 403 has an imaging function equipped with, for example, a contact image sensor (CIS), and captures an image of the paper passing through the inspection device 102, and transmits the captured image to the inspection device 102 via the inspection device control unit 405. The CIS is an image sensor that integrates a sensor (light receiving element), a light source (LED), and a rod lens array (equal magnification imaging lens), and can get closer to the surface of the paper and read the image printed on the paper more compactly than a camera. Note that the CIS of the imaging unit 403 is an example of a sensor, and other types of sensors such as a CCD image sensor may also be used, and the imaging method is not limited thereto.

[0032] The inspection device control unit 405 performs inspection processing using image data (scanned image) obtained by scanning and reading the printed matter with the imaging unit 403. The inspection device control unit 405 also controls the entire inspection device 102. The inspected printed matter is sent to the finisher 103. After inspection, the printed matter is discharged by discharge rollers 404. Although not shown here, the imaging unit 403 may be configured to read from below the conveyor belt 402 so that it can also handle double-sided printed matter.

[0033] FIG. 4B is a top view of the conveyor belt 402 as viewed from the imaging unit 403 side. When reading the printed matter 410, the CIS of the imaging unit 403 illuminates the printed matter 410 with a light source and reads it with a sensor. The skew detection illumination device 411 is a device for detecting whether the printed matter 410 is skewed with respect to the conveyance direction when it is conveyed on the conveyor belt 402. The skew detection illumination device 411 illuminates the conveyed printed matter 410 with light from an oblique direction, and the imaging unit 403 reads an image of a shadow at the edge of the printed matter 410 to detect skew of the printed matter 410. In this embodiment, the imaging unit 403 is configured to read the shadow image of the edge of the printed matter 410, but a configuration in which a reading sensor other than the imaging unit 403 is used may also be used.

[0034] The configuration of the inspection apparatus control unit 405 of the inspection apparatus 102 according to this embodiment will be described with reference to Fig. 5. The inspection apparatus control unit 405 has an image input unit 501, a communication unit 502, a control unit 503, a storage unit 504, an operation display unit 505, and an inspection processing unit 506. The inspection apparatus control unit 405 is controlled by the control unit 503. The control unit 503 has a CPU 515 and a memory 516. The CPU 515 loads a program stored in the storage unit 504 into the memory 516 of the control unit 503 and executes it to realize various processes described below.

[0035] The image input unit 501 receives a scanned image obtained by reading a printed material with the imaging unit 403. The CPU 515 stores this received scanned image in the storage unit 504. The communication unit 502 also communicates with the controller 201 of the image forming apparatus 101. This communication involves receiving image data (reference image) used for printing that corresponds to the scanned image, and sending and receiving inspection control information. The CPU 515 also stores the received reference image and inspection control information in the storage unit 504.

[0036] The operation display unit 505 functions as a display unit and is a display screen that can display various menus, print data information, etc. The operation display unit 505 also functions as a reception unit that receives operations from the user. The operation display unit 505 also functions as a display control means.

[0037] Inspection control information is transmitted and received between the inspection device 102 and the image forming device 101. One type of inspection control information is synchronization information, such as print job information, number of copies to be printed, and page order information, for matching the scanned image (inspection image) of the printed material with the reference image of the print data. The other type of inspection control information is inspection result information and control information for controlling the operation of the image forming device 101 accordingly. When performing double-sided printing or printing multiple copies, the order of the scanned image scanned by the inspection device 102 and the reference image used to print it may differ. The synchronization information is required to synchronize the reference image with the scanned image when the order of the scanned image and the reference image differs. Furthermore, because one reference image may correspond to multiple scanned images, the synchronization information is required to synchronize the reference image with the scanned image. The inspection control information transmitted and received between the inspection device 102 and the finisher 103 is inspection result information and control information for controlling the operation of the finisher 103 accordingly.

[0038] The operation of the inspection processing unit 506 is controlled by the CPU 515 of the control unit 503. The inspection processing unit 506 sequentially inspects pairs of corresponding scanned images and reference images based on synchronization information, which is one type of inspection control information transmitted and received between the image forming apparatus 101 and the image forming apparatus 101. Details of the inspection processing unit 506 will be described later. When the inspection processing is completed, the determination result is sent to the control unit 503 and displayed on the operation display unit 505. If the determination result indicates that an image abnormality has occurred, the control of the image forming apparatus 101 and the finisher 103 is switched through the communication unit 502 in a manner designated in advance by the user via the operation display unit 505. For example, the image forming processing by the image forming apparatus 101 is stopped, and the paper output tray of the finisher 103 is switched to an escape tray.

[0039] Next, a description will be given of the functional configuration of the inspection processing unit 506. The inspection processing unit 506 includes a skew detection unit 507, a color conversion unit 508, a resolution conversion unit 509, an image deformation unit 510, a position alignment unit 511, a matching unit 512, a determination unit 513, and a calibration unit 514. The components of the inspection processing unit 506 may be realized by the CPU 515 loading a program stored in the storage unit 504 into the memory 516 of the control unit 503 and executing it. Some or all of the components of the inspection processing unit 506 may be realized by a dedicated processing circuit such as an ASIC.

[0040] The skew detection unit 507 is a module that detects the skew angle of the scanned image. As described above with reference to FIG. 4(b), the imaging unit 403 scans the shadow of the edge of the printed material that is created when the printed material is drawn into the inspection device 102 and transported on the transport belt 402 and is irradiated by the skew detection irradiation device 411. The skew detection unit 507 detects the skew angle of the printed material using the shadow of the edge of the scanned image. Based on the skew angle thus detected, the image transformation unit 510, which will be described later, performs correction processing.

[0041] The color conversion unit 508 is a module that performs color conversion between the scanned image and the reference image. The reference image is rasterized in the CMYK color space by the image processing unit 209, and the scanned image is drawn in the RGB color space read by the imaging unit 403. The color conversion unit 508 converts the reference image into an RGB image. For example, the conversion may be performed using a CMYK to RGB lookup table (hereinafter referred to as LUT) shown in Table 1. [Table 1]

[0042] When the color conversion unit 508 uses an LUT, it performs color conversion to RGB for pixels on grid points by referring to a conversion table, and for pixels not on grid points of the LUT, it obtains RGB by interpolating from adjacent grid points.

[0043] Furthermore, the LUT is stored for each paper type and characteristics. This is because the RGB values ​​of a scanned image vary significantly depending on the paper type and characteristics. The LUT is stored in the storage unit 504 along with paper type information, and when the color conversion unit 508 references the LUT, it determines the LUT reference destination from the corresponding ID based on the paper type information.

[0044] The resolution conversion unit 509 is a module that converts the resolution of the scanned image and the reference image. The scanned image and the reference image may have different resolutions when input to the inspection device control unit 405. Furthermore, the resolution of the image used by each module of the inspection processing unit 506 may differ from the resolution of the input image. In such cases, the resolution conversion unit 509 converts the image resolution. For example, assume that the scanned image has a resolution of 600 dpi in the main scan direction and 300 dpi in the sub-scan direction, and the reference image has a resolution of 1200 dpi in the main scan direction and 1200 dpi in the sub-scan direction. If the resolution required by the inspection processing unit 506 is 300 dpi in both the main scan and the sub-scan, the scanned image and the reference image are each reduced in size to 300 dpi in both the main scan and the sub-scan. The scaling method used here may be a known method that takes into account the computational load and the required accuracy. For example, scaling using the SINC function imposes a heavy computational load but can achieve highly accurate scaling results. Furthermore, if scaling is performed using the nearest neighbor method, the calculation load is light, but the resulting scaling results will be low in accuracy.

[0045] The image deformation unit 510 generates distortion information based on an image acquired by a calibration unit 514 (described later). The method of generation will be described later. The registration unit 511 performs registration processing between the scanned image and the reference image. Details of the registration processing will be described later.

[0046] The matching unit 512 is a module that matches a scanned image with a reference image. The scanned image and reference image input to this matching unit 512 are images with the same resolution. Furthermore, it is assumed that the scanned image has been corrected by the alignment unit 511 so that the scanned image and reference image can be compared. The matching unit 512 performs a matching process between the reference image and the scanned image, whose resolution has been adjusted by the resolution conversion unit 509 and whose position has been aligned by the alignment unit 511.

[0047] The calibration unit 514 adjusts the LUT and distortion parameters. The calibration unit 514 adjusts the LUT and distortion parameters by reading a calibration chart. Calibration charts include a color chart such as calibration chart 800 in FIG. 8(a) and a chart with a cross mark pattern such as calibration chart 810 in FIG. 8(b). The color chart of calibration chart 800 in FIG. 8(a) is used to correct color values. On the other hand, the calibration chart 810 in FIG. 8(b), in which cross marks, dot patterns, lines and spaces, etc. are arranged in a grid pattern, is used to correct paper misalignment and printing distortion.

[0048] The calibration unit 514 first reads a calibration chart 800 as shown in FIG. 8A to adjust the LUT used in the color conversion unit 508. Patches that match the grid points of the LUT can be printed on the calibration chart 800. RGB values ​​are obtained by reading the CMYK values ​​that match the grid points using the imaging unit 403. The LUT is adjusted based on the correspondence between the CMYK values ​​of the calibration chart and the read RGB.

[0049] The calibration unit 514 then reads a calibration chart 810 as shown in FIG. 8(b) to adjust the distortion parameters used in the alignment unit 511. The calibration chart 810 can acquire more accurate information by reducing the spacing between marks. Although a cross is used as the shape of the marks, there is no limitation to the shape, and they may be, for example, squares. The method for adjusting the LUT and distortion parameters will be described in detail later.

[0050] The process flow for inspection performed by the inspection device 102 will be described with reference to Fig. 6. The process described below is performed by the inspection processing unit 506. For example, this is realized by the CPU 515 of the control unit 503 of the inspection device 102 reading a program stored in the storage unit 504 into the memory 516 and executing it. Below, the step numbers of each process included in the flowchart are indicated by numbers beginning with "S". This also applies to the subsequent flowcharts.

[0051] A print job is input to the image forming apparatus 101 from the client PC 106 or the print server 105. The flow of FIG.

[0052] First, in step S601, the CPU 515 receives RIP data and paper type related to a print job from the image processing unit 209 of the image forming apparatus 101 via the communication unit 502. This RIP data is a reference image used for print output.

[0053] Next, in S602, the CPU 515 determines whether there is calibration data corresponding to the paper type received from the image forming apparatus 101. The calibration data is a set of paper information, an LUT used by the color conversion unit 508, and distortion information used by the image transformation unit 510. The calibration data is stored in the storage unit 504 as a calibration data list, and the CPU 515 performs processing to read out the calibration data that matches the paper type received from the image forming apparatus 101. Table 2 is an example of a calibration data list. [Table 2]

[0054] As examples, the cases where the paper type received from the image forming apparatus 101 is "plain paper" and "coated paper" will be described. First, when the paper type received from the image forming apparatus 101 is plain paper, plain paper is included in the paper types in the calibration data list, and ID001 is hit. The CPU 515 performs processing to read out the LUT and distortion information for ID001 from the storage unit 504. On the other hand, when the paper type received from the image forming apparatus 101 is coated paper, there is no matching paper type in the calibration list, and therefore it is determined that calibration of the inspection device 102 needs to be performed.

[0055] In S602, if the CPU 515 determines that there is a paper type that matches the received paper type and the paper type in the calibration data list (if YES), the process proceeds to S608. On the other hand, in S602, if the CPU 515 determines that there is no paper type that matches the received paper type and the paper type in the calibration data list (if NO), the process proceeds to S603 because it is necessary to perform calibration of the inspection device 102.

[0056] Next, in S603, the CPU 515 displays a UI screen 701 shown in FIG. 7A via the operation display unit 505 to notify the user that calibration of the inspection device 102 will be performed. The UI screen 701 is a notification screen that displays a message that calibration of the inspection device 102 will be performed. It is also a confirmation screen that requests confirmation from the user. For example, the operation display unit 505 displays a message saying, "This is a new paper type. Calibration will be performed." Then, when the user operates the confirmation button 702, the CPU 515 advances the process to S604.

[0057] Next, in S604, the CPU 515 performs a print output process for the calibration charts. As the calibration charts, the color calibration chart 800 shown in Fig. 8(a) and the cross pattern calibration chart 810 shown in Fig. 8(b) are used.

[0058] The calibration chart is RIP data and is stored in advance in the storage unit 504. Note that the method of acquiring the calibration chart is not limited to this. It is sufficient that a predetermined chart can be acquired, and PDL data for the calibration chart may be input from the controller 201 of the image forming apparatus 101. Alternatively, PDL data for the calibration chart may be input from an external device such as the client PC 106. The calibration chart read out from the storage unit 504 by the CPU 515 is transmitted to the image forming apparatus 101 via the communication unit 502. In the image forming apparatus 101, the printer unit 202 prints out the calibration chart.

[0059] Next, in S605, the CPU 515 performs processing to scan and read the printed image of the calibration chart that has been printed out by the image forming apparatus 101 and transported to the inspection apparatus 102. The image input unit 501 uses the imaging unit 403 to read the printed image of the calibration chart. First, the printed image of the calibration chart 800 is read. Next, the printed image of the calibration chart 810 is read. Then, the calibration unit 514 performs calibration based on the RIP data of the calibration chart and the scanned image of the printed image of the calibration chart.

[0060] Next, in S606, the calibration unit 514 generates an LUT based on the calibration chart 800. The calibration unit 514 creates an LUT by associating patches corresponding to the CMYK grid points of the calibration chart 800 with RGB values ​​read by scanning a printed image of the calibration chart 800.

[0061] Next, in S607, the calibration unit 514 generates distortion information from the mark information of the calibration chart 810 scanned and read in S605. The distortion information generation process will be described in detail later.

[0062] Next, in S608, the CPU 515 performs a calibration data registration process. The newly calibrated paper type is added to the calibration list of Table 2, and the calibration list is updated. Table 3 shows an example when coated paper is added to the calibration list. [Table 3] Then, the CPU 515 stores the LUT and distortion information corresponding to the added ID003 in the storage unit 504, completing the registration of the calibration data.

[0063] Steps S609 to S616 are for printing the print data after calibration is complete and inspecting the printed matter. In step S609, the color conversion unit 508 performs color conversion on the reference image that is the source of the print data. To make the reference image closer to the scanned image, the color conversion unit 508 uses an LUT corresponding to the paper type registered in the calibration list. The LUT is either the one referenced in step S602 or the one newly added in step S608.

[0064] Next, in S610, the resolution conversion unit 509 converts the resolution of the reference image. At this time, the CPU 515 first causes the resolution conversion unit 509 to convert the reference image to a predetermined resolution (for example, 300 dpi×300 dpi).

[0065] Next, in S611, the CPU 515 determines that the inspection device 102 is in a state where it can accept a print job, and issues a print execution command to the controller 201 of the image forming device 101. When the controller 201 accepts this command, in S611, printing based on the RIP data and paper information of the print job begins.

[0066] Next, in step S612, the CPU 515 performs processing to read the printed matter printed out by the image forming apparatus 101 using the imaging unit 403 and acquire a scanned image. Next, in S613, the alignment unit 511 aligns the scanned image with the reference image. The alignment will be described later.

[0067] Then, in S614, the comparison unit 512 compares the scanned image with the reference image. First, the comparison unit 512 compares the scanned image with the reference image. Then, the determination unit 513 determines whether or not there is an image abnormality in the printed scanned image. The reference value used to determine whether or not there is an image abnormality is based on a set value stored in advance in the storage unit 504.

[0068] Next, the process proceeds to S615, where the CPU 515 controls to display the results of the inspection process in S614 on the operation and display unit 505. At this time, simply displaying the final judgment result makes it difficult for the user to understand what kind of image abnormality was found. For this reason, the final judgment result is superimposed on the scanned image and displayed on the operation and display unit 505. This superimposition may be performed by any method that makes it easy to grasp the location of the image abnormality. For example, the location of the image abnormality may be displayed in red on the scanned image as the final judgment result. Then, in S616, the CPU 515 controls the process to repeatedly execute the processes from S611 to S615 until all printing is completed.

[0069] Next, the distortion information generation process of S607 will be described with reference to Fig. 9. The process shown in this flowchart is performed by the inspection processing unit 506. For example, this is realized by the CPU 515 of the control unit 503 of the inspection device 102 reading out a program stored in the storage unit 504 into the memory 516 and executing it.

[0070] First, in S901, the CPU 515 controls the process of acquiring a reference image. The reference image is the RIP data used to print out the calibration chart 810 used in S604.

[0071] Next, in S902, the CPU 515 controls a process for detecting the mark position from the reference image. The method for detecting the mark position is not particularly limited, but an example is to extract the pixel area of ​​the mark by template matching, obtain the center of gravity of that pixel area, and use that as the mark position. At this time, an index is simultaneously calculated based on the mark position, such as the mark being in the jth row and ith column from the top left of the paper, so that each mark can be identified. The mark position may be stored in advance in the storage unit 504. If the mark position written in the reference image can be predicted, it may be used without detection.

[0072] Next, in S903, the alignment unit 511 aligns the scanned image of the calibration chart 810 acquired in S605 with the reference image using affine transformation. For example, the alignment method involves performing affine transformation by acquiring an affine matrix that minimizes the sum of the Euclidean distances between the mark positions. Affine transformation is a transformation that rotates, translates, scales, and shears the entire image. Using affine transformation, the scanned image can be aligned with the reference image while maintaining local distortions within the image. In the case of double-sided printing, the alignment unit 511 aligns both the front and back sides.

[0073] Next, in S904, the calibration unit 514 detects the mark positions and acquires the mark indexes from the scanned image aligned in S903 in the same manner as in step S902, and generates distortion information. In the case of double-sided printing, processing is performed for both the front and back sides. This completes the distortion information generation process.

[0074] Next, the alignment processing of S613 will be described with reference to Fig. 10. The processing shown in this flowchart is processing performed by the alignment unit 511 and image deformation unit 510 of the inspection processing unit 506. For example, this is realized by the CPU 515 of the control unit 503 of the inspection device 102 reading out a program stored in the storage unit 504 into the memory 516 and executing it.

[0075] In this embodiment, the image deformation method will be described using free-form deformation (FFD), but is not limited to this. It is desirable to use an image deformation method that matches the shape, such as thin plate spline (TPS) or landmark LDDMM method. The image that forms the basis of the print data is called reference image T. The inspection object image obtained by printing the reference image and scanning the printout is called scanned image I. The image obtained by performing distortion correction on scanned image I is called distortion-corrected image I'. Note that T(x,y), I(x,y), and I'(x,y) respectively represent pixel values ​​at coordinates (x,y).

[0076] First, in S1001, the alignment unit 511 performs pre-alignment. For example, a registration method may be used in which feature points are extracted from an image, an affine matrix is ​​obtained so as to minimize the sum of Euclidean distances of the feature points, and an affine transformation is performed.

[0077] Next, in S1002, the CPU 515 controls the process of acquiring the distortion information of the calibration data read in S602 or the distortion information generated in S608.

[0078] Next, in S1003, the image transformation unit 510 arranges control points on the scanned image and the reference image based on the distortion information. L×M control points are arranged in a grid pattern on a certain scanned image I. In order to improve the accuracy of distortion correction, it is desirable that the number of control points is greater than the number of marks on the calibration chart 810. Furthermore, the coordinates of the control point in the lth row and mth column are set to p m,l Let (l=1,..,L, m=1,..,M).

[0079] Here, the transformation formula for generating distortion-corrected image I' from scanned image I is shown in formula (1) below. w(x, y) is expressed by formula (2) below, and is a formula for obtaining the coordinates after distortion correction of the coordinates (x, y) in scanned image I. The bases B0(t), B1(t), B2(t), and B3(t) in formula (2) below are respectively expressed by formulas (3) to (6) below. Also, u and v are respectively expressed by formulas (7) and (8) below. Also, δ x , δ y are respectively expressed by the following formulas (9) and (10): where H and W are the vertical and horizontal sizes of the image, respectively.

number

[0080] The arrangement of the control points will be described with reference to Fig. 11. Fig. 11 is a schematic diagram showing a state in which a control point 1101 is arranged at optimal coordinates in accordance with the distortion of an image 1102. In S1003, the optimal coordinates p of the control point are calculated using the distortion information. m,l (l=1, .., L, m=1, .., M) are obtained. As a method of obtaining the coordinates of the control points, for example, the least squares method can be used to analytically obtain the coordinates of the control points. In other words, the correspondence between the mark positions in the scanned image of the calibration chart 810 and the reference image is regarded as the correspondence between the feature points in the scanned image and the reference image. When the scanned image of the calibration chart 810 is deformed using equation (1), the control point coordinates are obtained so as to minimize the deviation of the mark positions in the reference image. The sum of squared errors of the mark positions is expressed by the following equation (11). In equation (11), the number of rows and the number of columns of the marks on the calibration chart 810 are respectively expressed as μ pieces, M μ In addition, the following formula (11) expresses the mark positions at the jth row and the ith column of the index of the reference image and the scanned image of the calibration chart 810 as μ t (i,j) ,μ s (i,j)Equation (11) is differentiated by a vector whose elements are the coordinates of all control points. Then, when the differential value is set to 0, the vector whose elements are the coordinates of all control points can be obtained as the control point coordinates to be found.

number

[0081] In this embodiment, the 16 grid points p(u,v), p(u+1,v), ..., p(u+3,v+3) are used to derive the distortion-corrected image I', but this is not limiting. For example, four grid points with close Euclidean distances (x,y) may be used.

[0082] Next, in S1004, the image deformation unit 510 deforms the scanned image I using equation (1) based on the control point coordinates acquired in S1003, and generates a distortion-corrected image I'. This distortion-corrected image I' is stored as an initial distortion image.

[0083] Next, in S1005 and subsequent steps, any minute distortions that could not be completely corrected in S1004 are corrected. Minor distortions refer to distortions that occur when printing and scanning, but that did not occur at the time of calibration of the inspection device 102. In this embodiment, a method for optimizing control points used for free-form deformation based on a comparison between a scanned image and an initial distortion image will be described. Hereinafter, the scanned image will be referred to as T, the initial distortion-corrected image as I', and the image that has undergone the updated distortion correction process as the aligned image I''. Note that T(x,y), I'(x,y), and I''(x,y) respectively represent pixel values ​​at coordinates (x,y).

[0084] In S1005, the image deformation unit 510 updates the positions of the control points. The distortion correction update process will be described with reference to Fig. 12. The update formula for the positions of the control points for distortion correction is shown in the following formula (12). μ represents a weighting coefficient, which may be a value such as 0.1, and may be changed in accordance with the speed of updating the control points. ∇ c is expressed by the following equation (13), and the control point p m,lA set of pixel locations in the neighborhood of m,l is the differential value of the sum of squares of the difference between the pixel values ​​of the aligned image I' and the scanned image T.

number

[0085] Next, in S1006, the image transformation unit 510 updates the pixels based on the equation (1).

[0086] Next, in S1007, the CPU 515 performs a process of determining whether pixel updating has been completed. For example, the CPU 515 obtains the distance d between the aligned image I'' and the scanned image T, and determines whether pixel updating has been completed based on the distance d. The distance d is expressed by the following equation (14).

number

[0087] In S1007, if the distance d is equal to or less than a preset threshold, the position alignment unit 511 determines that the pixel update is complete. On the other hand, if the distance d is not equal to or less than the preset threshold, the position alignment unit 511 determines that the pixel update is not complete. Another method of determination is to set an upper limit on the number of updates in advance and determine that the update is complete when the upper limit is reached.

[0088] In S1007, if the CPU 515 determines that the pixel update has not been completed, it controls the process to return to S1005. In S1007, if the CPU 515 determines that the pixel update has been completed, it ends the distortion correction process. This completes the distortion correction process.

[0089] As described above, by using the inspection process and calibration unit 514 to calibrate the inspection device 102 in accordance with the predictable variations in color and distortion that occur when changing paper, it is possible to reduce prints that may have image abnormalities.

[0090] <Modification 1 of the First Embodiment> The inspection process according to the first modification of the first embodiment of the present invention will be described below. In the first embodiment described above, the inspection device 102 is calibrated in accordance with color variations due to changes in paper. However, since the user may wish to determine whether or not to calibrate the inspection device 102, in Modification 1, the user selects whether or not to calibrate the inspection device 102.

[0091] The inspection process of Modification 1 will be described with reference to Fig. 13. The process described below is performed by inspection processing unit 506. For example, this is realized by CPU 515 of control unit 503 of inspection device 102 reading a program stored in storage unit 504 into memory 516 and executing it. S1301, S1302, and S1305 to S1317 are similar to S601, S602, and S604 to S616, and therefore description thereof will be omitted.

[0092] In S1302, the CPU 515 displays a UI screen 703 shown in FIG. 7B via the operation display unit 505 to notify the user that calibration of the inspection device will be performed. The UI screen 703 displays a message that prompts the user to select whether or not to perform calibration. For example, the operation display unit 505 displays a message saying, "This is a new paper type. Do you want to perform calibration?" The UI screen 703 also has a Yes button 704, a No button 705, and a Close button 706 that the user can select.

[0093] In S1303, the CPU 515 determines through the operation display unit 505 whether or not calibration of the inspection device 102 should be performed. When the user operates the Yes button 704, the CPU 515 advances the process to S1305 and performs control to start calibration of the inspection device 102. On the other hand, when the user operates the No button 705 or the Close button 706, the CPU 515 determines that calibration of the inspection device 102 is not necessary, and advances the process to S1310.

[0094] The first embodiment and the first modified example of the first embodiment may be switchable by the user. A setting screen 1401 as shown in Fig. 14 may be displayed on the operation display unit 505 to allow the user to make a selection. On the setting screen 1401, when the user operates a button 1402, the first embodiment may be executed, and when the user operates a button 1403, the first modified example of the first embodiment may be executed.

[0095] As described above, Modification 1 allows the user to determine whether or not to perform calibration of the inspection device 102. In addition, the user can select whether to forcibly perform calibration, or whether or not to perform calibration.

[0096] <Modification 2 of the First Embodiment> The inspection process according to the second modification of the first embodiment of the present invention will be described below. In the first embodiment described above, the inspection device 102 is calibrated in accordance with predictable color variations due to changes in paper. In the second modification, the image forming device 101 is adjusted before the inspection device 102 is calibrated.

[0097] The flowchart in Fig. 15 is a modified example of the flowchart shown in Fig. 6. The processing described below is processing performed by inspection processing unit 506. For example, this is realized by CPU 515 of control unit 503 of inspection device 102 reading a program stored in storage unit 504 into memory 516 and executing it. S1501, S1502, and S1507 to S1519 are similar to S601, S602, and S604 to S616, and therefore description thereof will be omitted.

[0098] In S1503, the CPU 515 displays a UI screen 707 shown in FIG. 7C via the operation display unit 505 to prompt the user to calibrate the image forming apparatus 101. The UI screen 707 displays a message prompting the user to select whether or not to perform automatic gradation correction of the image forming apparatus 101 before performing calibration. For example, the operation display unit 505 displays a message asking, "Do you want to perform automatic gradation correction of the printing device before performing calibration?" The UI screen 707 also includes a Yes button 704, a No button 705, and a Close button 706 that the user can select.

[0099] This automatic gradation correction is a function provided in the image forming apparatus 101, which automatically corrects the gradation, density, and color of the printed image by printing out a test page and scanning it on the platen glass. It is also called calibration of the image forming apparatus 101.

[0100] In S1504, the CPU 515 determines whether or not calibration of the image forming apparatus 101 is to be performed via the operation display unit 505. If the user operates the Yes button 708 (in the case of YES), the CPU 515 advances the process to S1506 and causes the image forming apparatus 101 to start calibration. On the other hand, if the user operates the No button 709 or the Close button 710 (in the case of NO), the CPU 515 determines that calibration of the image forming apparatus 101 is not necessary, and advances the process to S1507.

[0101] In S1505, the CPU 515 transmits a calibration command for the image forming apparatus 101 to the image processing unit 209 via the controller 201 in the image forming apparatus 101. Upon receiving this command, the image processing unit 209 of the image forming apparatus 101 executes calibration of the image forming apparatus 101.

[0102] In S1506, the CPU 515 receives a notification that the calibration of the image forming apparatus 101 has been completed from the image processing unit 209 via the controller 201 in the image forming apparatus 101. Upon receiving the completion notification, the CPU 515 advances the process to S1507 and controls the inspection apparatus 102 to start calibration.

[0103] As described above, in the second modification, the user can select whether to perform automatic tone correction (calibration) of the image forming apparatus 101 before performing calibration of the inspection apparatus 102.

[0104] <Second embodiment> In the first embodiment, the inspection device 102 is calibrated when it is expected that changes in color, distortion, etc. will occur when the paper is changed. However, even when the paper is the same, the color and distortion of the printed matter may change over time. In the second embodiment, the inspection device 102 is calibrated not only when the paper is changed, but also at regular intervals.

[0105] In the second embodiment, calibration of the inspection device 102 is performed according to the time elapsed since the previous calibration of the inspection device 102. This allows calibration of the inspection device 102 to be performed in response to changes over time in addition to the predictable fluctuations in color and distortion due to changes in paper, making it possible to reduce prints with the possibility of image abnormalities.

[0106] Only the differences from the first embodiment will be explained below. 16 is a flowchart illustrating inspection processing by the inspection device 102 according to the second embodiment. The processing described below is processing performed by the inspection processing unit 506. For example, this is realized by the CPU 515 of the control unit 503 of the inspection device 102 reading out a program stored in the storage unit 504 into the memory 516 and executing the program.

[0107] Other than S1603 and S1609, S1601, S1602, S1604 to S1608, and S1610 to S1617 are the same as S601, S602, S604 to S607, and S609 to S617, and therefore the description thereof will be omitted.

[0108] First, in S1603, the CPU 515 checks the time that has elapsed since the previous calibration. The calibration list stores the time at which the last calibration was performed. The CPU 515 compares the time at which the calibration was performed with the current time to determine whether a predetermined time has elapsed. Table 4 shows an example of a calibration list in this embodiment. [Table 4]

[0109] For example, the current time is assumed to be "15:00, May 21, 2024." The threshold for the elapsed time is assumed to be 24 hours. When plain paper is specified as the print job, comparing the current time with the last calibration time for plain paper reveals that 27 hours have passed. Therefore, the CPU 515 determines that calibration of the inspection device 102 is necessary, and the process proceeds to S1603. On the other hand, when coated paper is specified as the print job, only one hour has passed, so the CPU 515 determines that calibration of the inspection device 102 is not necessary, and the process proceeds to S1610. The threshold for the elapsed time may be stored in advance in the storage unit 504. The operation / display unit 505 may also display a UI screen 1701 as shown in FIG. 17 to set the threshold for the elapsed time. When the user selects a threshold from a list 1702 on the UI screen 1701 and operates a button 1703, the selected threshold is saved in the storage unit 504. The threshold value is not limited to being selected from the list 1702, but the user may input a predetermined time as the threshold value.

[0110] In S1609, the calibration unit 514 registers the calibration data. In the second embodiment, the calibration time is updated for the paper type for which the calibration of the inspection device 102 has been performed in the calibration list.

[0111] As described above, the time elapsed since the calibration of the inspection device 102 is acquired, and the inspection device 102 is calibrated in accordance with changes in color and distortion over time, thereby reducing prints that may have image abnormalities.

[0112] <Third embodiment> In the first embodiment, the inspection device 102 is calibrated when it is expected that changes in color tone, distortion, and the like will occur when changing the paper. However, even when different paper types are used, there are cases where the paper characteristics are similar and calibration of the inspection device 102 is not necessary. For example, single-sided coated paper is composed of a coated paper side and a plain paper side. Therefore, in single-sided printing, calibration of the inspection device 102 is not necessary by applying the calibration data for coated paper to the printed side.

[0113] In the third embodiment, calibration data for similar paper characteristics is used for different paper types, eliminating the need to perform calibration. Only the differences from the first embodiment will be described below. 18 is a flowchart illustrating the inspection process performed by the inspection device 102 according to the third embodiment. The process described below is performed by the inspection processing unit 506. For example, this is realized by the CPU 515 of the control unit 503 of the inspection device 102 reading out a program stored in the storage unit 504 into the memory 516 and executing it.

[0114] Other than S1801, S1802, S1804, S1805, and S1808, S1803, S1806, S1807, and S1809 to S1816 are the same as S603, S603, S606, S607, and S609 to S616, and therefore description thereof will be omitted.

[0115] First, in S1801, the CPU 515 receives RIP data and paper information for a print job from the image processing unit 209 via the controller 201 in the image forming apparatus 101. Here, the paper information in this embodiment refers to paper characteristics such as the basis weight, whiteness, and paper size of the paper. Furthermore, if the paper characteristics differ between the front and back printing surfaces of the paper, the CPU 515 acquires the paper information for the front and back surfaces.

[0116] Next, in S1802, the CPU 515 determines whether there is calibration data that matches the paper information of the print job. Table 5 shows an example of a calibration data list used in this embodiment. If the paper characteristics differ between the front and back sides, the CPU 515 determines whether there is matching calibration data for each side. If there is matching calibration data for both sides, the CPU 515 proceeds to S1809. [Table 5]

[0117] A tolerance may be set in the determination in S1802 as to whether the paper information matches the calibration data. For example, if the basis weight of the paper information is "70 g / m 2 71~110g / m or less 2 " "111g / m 2 If the match is within the range of "or more than," it may be determined that there is a match. It is not necessary for all items of the paper information to match. Since it is sufficient to extract only the conditions necessary for calibrating the inspection device 102, the CPU 515 may make a determination based on, for example, the basis weight alone.

[0118] Next, in S1804 and S1805, the CPU 515 performs the same processing as in S604 and S605. Here, if it is determined in S1802 that calibration data does not exist on only one side, the calibration chart is printed out and scanned only for the side determined to have no calibration data.

[0119] In S1808, the CPU 515 registers the calibration data. For example, the calibration data list of Table 5 includes a basis weight of "200 g / m 2 ", whiteness "High", and paper size "A3" are registered as shown in Table 6. [Table 6]

[0120] With the above configuration, an example will be shown in which calibration of the inspection device 102 is omitted. 2 ", whiteness "high", paper size "A3". The back side is 200g / m 2 ", whiteness "Medium", paper size "A3". First, the front side of the paper information matches ID004 in the calibration data list. Next, the back side of the paper information matches ID004 in the calibration data list. 2 As described above, there is ID003, which has matching paper characteristics other than basis weight. Therefore, the calibration data associated with ID004 is applied to the front side, and the calibration data associated with ID003 is applied to the back side. In this way, by combining the calibration data of the inspection device 102 that has already been registered and applying separate calibration data to the front and back sides, it is possible to omit the calibration of the inspection device 102.

[0121] <Fourth embodiment> In the modified example of the first embodiment, whether or not to perform calibration of the inspection device is determined based on information about the print job at the time of printing. In the fourth embodiment, calibration of the inspection device 102 is performed when the state of the image forming device 101 changes.

[0122] 19 is a flowchart illustrating inspection processing by the inspection device 102 according to the fourth embodiment. The processing described below is processing performed by the inspection processing unit 506. For example, this is realized by the CPU 515 of the control unit 503 of the inspection device 102 reading out a program stored in the storage unit 504 into the memory 516 and executing it. Only differences from the control flow of FIG. 13, which is Modification 1 of the first embodiment, will be described below. S1904 to S1910 and S1912 to S1919 are the same as S603 to S608 and S609 to S616, and therefore description thereof will be omitted.

[0123] First, in S1901, the CPU 515 receives the RIP data of the print job, the paper type, and status information of the image forming apparatus 101 from the image processing unit 209 via the controller 201 of the image forming apparatus 101. The status information associates information on the implementation of adjustments and part replacements with the time of the adjustments in the image forming apparatus 101. As an example, the status information of the image forming apparatus 101 is shown in Table 7. [Table 7]

[0124] In S1903, the CPU 515 determines whether there is an update to the status information for the ID referenced in S1902. Here, each piece of ID information in the calibration list shown in Table 2 is linked to the status information of the image forming apparatus 101. As an example, Table 8 shows the status information for ID001 when ID001 is referenced in S1902. [Table 8]

[0125] In S1903, if the update time of the status information acquired from the image forming apparatus 101 is newer than the update time of the status information of ID001 (if YES), the CPU 515 determines that calibration of the inspection apparatus 102 is necessary. Then, the process proceeds to S1903. In the examples of Tables 7 and 8, the "tone correction implementation information" indicates a newer time. Since tone correction of the image forming apparatus 101 was performed after the calibration data of ID001 was acquired, it is determined that calibration of the inspection apparatus 102 is necessary.

[0126] In the above description, it is determined whether all status information has been updated, but this is not limited to this. The user may be able to select whether to update the status information used to determine whether calibration should be performed. For example, a setting screen 2001 shown in FIG. 20 may be displayed, and the user may select the status information of the image forming apparatus 101 to be used to determine whether calibration should be performed. The setting screen 2001 allows the user to select "Yes" or "No" using radio buttons for status information such as tone correction, registration correction, part replacement, paper jam, and service mode change. When the user operates the enter button 2002, the setting information set using the radio buttons is saved in the storage unit 504. In S1903, the CPU 515 may determine whether only the status information used to determine whether calibration should be performed, for which "Yes" has been selected, has been updated.

[0127] In S1904, the CPU 515 notifies the user via the operation and display unit 505 that calibration of the inspection device 102 will be performed. In S1904, the operation and display unit 505 displays a UI screen 2101 shown in Fig. 21. The UI screen 2101 is similar to the UI screen 701, but the message notifying the user is different. In the example of the UI screen 2101, updated status information and the update time are displayed, and a message is displayed that prompts the user to select whether or not to perform calibration.

[0128] In S1911, the CPU 515 updates the status information. If it is determined in S1903 that the status information of the image forming apparatus 101 needs to be updated, the CPU 515 updates the status information of the corresponding ID to the content of the status information received in S1901.

[0129] In the third embodiment, calibration data is stored in the storage unit 504 in association with printing information such as paper type, and execution of calibration is determined based on the time elapsed since calibration. However, this is not limiting, and execution of calibration may be determined based only on the time elapsed since calibration, regardless of the printing information.

[0130] As described above, by calibrating the inspection device 102 in accordance with the variations in color and distortion that occur as the state of the image forming device 101 changes, it is possible to reduce the number of prints that may contain image abnormalities.

[0131] <Modification of the Fourth Embodiment> Next, an inspection process according to a modified example of the fourth embodiment will be described. In the above-described fourth embodiment, the inspection device 102 is calibrated in accordance with variations in color and distortion that occur with changes in the state of the image forming device 101. In a modified example, calibration is performed based on the state of the inspection device 102 in addition to the state of the image forming device 101. If variations occur in the sensor of the imaging unit 403 or the light source, the color and distortion may vary. Furthermore, when inspections are performed repeatedly, parts may need to be replaced or the sensor may need to be cleaned, which may change the state of the sensor and light source.

[0132] A modification of the flowchart shown in FIG. 19 is shown in FIG. Steps S2201, S2202, S2204 to S2210, and S2212 to S2219 are similar to steps S1901, S1902, S1904 to S1910, and S1912 to S1910, and therefore their explanation will be omitted.

[0133] In S2203, the CPU 515 performs processing to read status information of the inspection device 102 from the storage unit 504. The status information of the inspection device 102 is information that associates items such as part replacement and cleaning of the inspection device 102 with the time of their implementation. In S2203, the CPU 515 uses the status information of the inspection device 102 together with the status information of the image forming device 101. The CPU 515 compares the status information of the image forming device 101 and the status information of the inspection device, which are held for each ID, with the status information acquired from the image forming device 101 and the inspection device 102, and if there is an update to the status information, determines that calibration of the inspection device 102 is necessary.

[0134] In S2211, the status information of the inspection device is recorded and updated together with the status information of the image forming device 101 in association with the ID of the calibration data.

[0135] 20 may be displayed, and the user may select status information of the inspection device 102 to be used to determine whether calibration should be performed. In addition to the status information of the image forming device 101, items such as part replacement and cleaning, which are status information of the inspection device 102, may be added to the setting screen 2001.

[0136] In addition, in the fourth embodiment, the calibration data is stored in the storage unit 504 in correspondence with printing information such as paper type, but the execution of calibration may be determined based only on a change in the status information, regardless of the printing information.

[0137] As described above, by calibrating the inspection device 102 in accordance with the variations in color and distortion caused by the variations in the inspection device 102, it is possible to reduce the number of prints that may have image abnormalities.

[0138] <Other embodiments> The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0139] The disclosure of this specification includes the following inspection apparatus, image forming apparatus, inspection apparatus control method, and program. (Item 1) an inspection means for reading the paper on which the image is formed and conveyed from the image forming means by a reading means and detecting any abnormality in the formed image by comparing it with a reference image; a storage means for storing calibration data; a determination unit that determines whether or not to perform calibration to adjust the reference image or the formed image used by the inspection unit; a calibration execution means for executing calibration and storing calibration data in the storage means when it is determined that calibration should be executed; a readout means for reading out calibration data from the storage means when it is determined that calibration is not to be performed; an adjustment unit that adjusts the reference image or the formed image based on the calibration data stored in the storage unit or the calibration data obtained by performing the calibration; An inspection device comprising: (Item 2) the storage means stores the calibration data in association with paper information; the determining means determines that calibration should be performed when calibration data corresponding to paper information of a print job is not stored in the storage means; Item 1. The inspection device according to item 1. (Item 3) the storage means stores the calibration data in association with the time at which the calibration was performed; the determination means determines that calibration should be performed when a predetermined time has elapsed since the time when the previous calibration was performed. Item 3. The inspection device according to item 1 or 2. (Item 4) the storage means stores the calibration data in association with status information of the image forming means; the determining means determines that calibration should be performed when the status information of the image forming means is updated; Item 3: The inspection device according to any one of items 1 to 3. (Item 5) the storage means stores the calibration data in association with status information of the inspection device; the determination means determines that calibration should be performed when the status information of the inspection device is updated. 5. The inspection device according to any one of items 1 to 4. (Item 6) The paper information is paper type. 6. The inspection device according to any one of items 2 to 5. (Item 7) The paper information is paper characteristics. The inspection device according to any one of items 2 to 6. (Item 8) If the determination means determines that calibration is to be performed, an operation display means for displaying a notification screen for notifying a user of the execution of the calibration; 8. The inspection device according to any one of items 1 to 7, (Item 9) the notification screen is a screen that allows the user to select whether or not to perform the calibration. Item 9. The inspection device according to item 8. (Item 10) a second operation display means for displaying status information of the image forming means on a UI screen that allows a user to select the status information; The determination means determines that calibration should be performed when the state information selected on the UI screen is updated. The inspection device according to any one of items 4 to 9. (Item 11) a third operation display means for displaying a UI screen on which the predetermined time can be selected; The inspection device according to any one of items 3 to 10. (Item 12) An image forming apparatus, an image forming means for forming an image on a sheet; a reading means for reading the paper on which an image is formed; The inspection device according to any one of items 1 to 11, An image forming apparatus comprising: (Item 13) A control method for an inspection device including a storage means for storing calibration data and an inspection means for reading a sheet of paper on which an image is formed and which is conveyed from an image forming means by a reading means and detecting an abnormality in the formed image by comparing the image with a reference image, the method comprising: a determination unit that determines whether or not to perform calibration for adjusting the reference image or the formed image used by the inspection unit; If it is determined that calibration should be performed, the calibration is performed and calibration data is stored in the storage means; If it is determined that calibration is not to be performed, the calibration data is read out from the storage means; an adjustment unit adjusts the reference image or the formed image based on the calibration data stored in the storage unit or the calibration data obtained by performing the calibration; Control method. (Item 14) A program for controlling a computer of an inspection device including a storage means for storing calibration data and an inspection means for reading a paper sheet on which an image is formed and conveyed from an image forming means by a reading means and detecting an abnormality in the formed image by comparing the image with a reference image, Computer, determining whether to perform calibration to adjust the reference image or the formed image used by the inspection means; If it is determined that calibration should be performed, the calibration is performed and calibration data is stored in the storage means; If it is determined that calibration is not to be performed, the calibration data is read out from the storage means; adjusting the reference image or the formed image based on the calibration data stored in the storage means or the calibration data obtained by performing the calibration; Here's a program to make it work.

[0140] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0141] 100: Image forming device, 102: Inspection device, 103: Finisher, 105: Print server, 106: Client PC

Claims

1. an inspection means for reading the paper on which the image is formed and conveyed from the image forming means by a reading means and detecting any abnormality in the formed image by comparing it with a reference image; a storage means for storing calibration data; a determination unit that determines whether or not to perform calibration to adjust the reference image or the formed image used by the inspection unit; a calibration execution means for executing calibration and storing calibration data in the storage means when it is determined that calibration should be executed; a readout means for reading out calibration data from the storage means when it is determined that calibration is not to be performed; an adjustment unit that adjusts the reference image or the formed image based on the calibration data stored in the storage unit or the calibration data obtained by performing the calibration; An inspection device comprising:

2. the storage means stores the calibration data in association with paper information; the determining means determines that calibration should be performed when calibration data corresponding to paper information of the print job is not stored in the storage means; The inspection device according to claim 1 .

3. the storage means stores the calibration data in association with the time at which the calibration was performed; the determination means determines that calibration should be performed when a predetermined time has elapsed since the time when the previous calibration was performed. The inspection device according to claim 1 .

4. the storage means stores the calibration data in association with status information of the image forming means; the determining means determines that calibration should be performed when the status information of the image forming means is updated; The inspection device according to claim 1 .

5. the storage means stores the calibration data in association with status information of the inspection device; the determination means determines that calibration should be performed when the status information of the inspection device is updated. The inspection device according to claim 1 .

6. The paper information is paper type. The inspection device according to claim 2 .

7. The paper information is paper characteristics. The inspection device according to claim 2 .

8. If the determination means determines that calibration is to be performed, an operation display means for displaying a notification screen for notifying a user of the execution of the calibration; The inspection device according to claim 1 .

9. the notification screen is a screen that allows the user to select whether or not to perform the calibration. The inspection device according to claim 8.

10. a second operation display means for displaying a UI screen on which the user can select status information of the image forming means; the determination means determines that calibration should be performed when the state information selected on the UI screen is updated. The inspection device according to claim 4.

11. a third operation display means for displaying a UI screen on which the predetermined time can be selected; The inspection device according to claim 3 .

12. An image forming apparatus, an image forming means for forming an image on a sheet; a reading means for reading the paper on which an image is formed; The inspection device according to any one of claims 1 to 11, An image forming apparatus comprising:

13. A control method for an inspection device including a storage means for storing calibration data and an inspection means for reading a sheet of paper on which an image is formed and which is conveyed from an image forming means by a reading means and detecting an abnormality in the formed image by comparing the image with a reference image, the method comprising: a determination unit that determines whether or not to perform calibration for adjusting the reference image or the formed image used by the inspection unit; If it is determined that calibration should be performed, the calibration is performed and calibration data is stored in the storage means; If it is determined that calibration is not to be performed, the calibration data is read out from the storage means; an adjustment unit adjusts the reference image or the formed image based on the calibration data stored in the storage unit or the calibration data obtained by performing the calibration; Control method.

14. A program for controlling a computer of an inspection device including a storage means for storing calibration data and an inspection means for reading a paper sheet on which an image is formed and conveyed from an image forming means by a reading means and detecting an abnormality in the formed image by comparing the image with a reference image, Computer, determining whether to perform calibration to adjust the reference image or the formed image used by the inspection means; If it is determined that calibration should be performed, the calibration is performed and calibration data is stored in the storage means; If it is determined that calibration is not to be performed, the calibration data is read out from the storage means; adjusting the reference image or the formed image based on the calibration data stored in the storage means or the calibration data obtained by performing the calibration; Here's a program to make it work.

Images