Image reading apparatus, image inspection system, reading control method, and storage medium

Abstract

To provide an image reading device, an image inspection system, a reading control method, and a program capable of improving accuracy of inspection and colorimetry by an image inspection device without causing downtime.SOLUTION: And a control section (reading control section 41) configured to control reading by the reading section 42, wherein the control section performs shading correction of the reading section 42 on the basis of shading data acquired by causing the reading section 42 to read a white reference plate disposed to face the reading section 42 at startup or before start of printing by the image forming apparatus 30, during the reading operation of the printed matter by the reading unit 42, the image data of the unprinted area of the printed matter is extracted based on the scan data read by the reading unit 42, and the paper color data in the reading unit 42 is created based on the extracted image data of the unprinted area.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image reading device, an image inspection system, a reading control method, and a program. [Background technology]

[0002] Printed materials produced by an image forming device are defective if there is color misalignment or distortion. An image inspection device detects defects (image defects) on the printed material and inspects the quality of the printed material based on the detected image defects. The image inspection device detects image defects on the printed material based on the difference between a reference image (correct image) and the read image read by an image reading unit.

[0003] For example, Patent Documents 1 and 2 disclose a configuration for inspecting a printed matter by comparing a correct image with a read image. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-204720 [Patent Document 2] Japanese Patent Publication No. 2021-190928 Summary of the Invention [Problem to be solved by the invention]

[0005] A challenge for image scanning units used in image inspection is that the heat generated by the light source during continuous illumination changes the efficiency of the light-emitting elements and control unit, resulting in changes in illuminance (light intensity) over time. In recent years, image scanning units have replaced halogen light sources with LEDs, reducing the initial light intensity change and the temperature-related changes over time. However, when the light source is continuously illuminated for 10 minutes, 30 minutes, or an hour, the efficiency of the LED elements and driver circuits changes over time due to temperature changes, so the change in light intensity never reaches zero. When scanned data from a printed material is scanned by the image scanning unit, if the light intensity of the light source changes, the read values ​​(color tone) will differ between the first and Nth sheets. This can affect the inspection and color measurement performed by the image inspection device. If the color tone of the scanned data from the color measurement patches differs, the image inspection device will instruct the image forming device to perform incorrect color correction. One way to reduce the impact of changes in light intensity from the light source is to ensure that the light source is illuminated for a sufficient period of time before starting printing. However, the method of ensuring sufficient lighting time before printing starts has the problem that downtime occurs, and the light intensity still changes over long periods of operation.

[0006] To deal with changes in the light intensity of the light source, shading correction must be performed during continuous printing. To perform shading correction during continuous printing, printing must be stopped temporarily to read the white reference plate. This poses the problem of downtime.

[0007] The present invention aims to provide an image reading device, an image inspection system, a reading control method, and a program that can improve the accuracy of inspection and color measurement by an image inspection device without causing downtime. [Means for solving the problem]

[0008] The invention described in claim 1 has been made to achieve the above object, In the image reading device, a reading unit disposed downstream of the image forming device and configured to read a printed material on which an image has been formed by the image forming device; a control unit that controls reading by the reading unit; Equipped with The control unit Upon startup or before the image forming apparatus starts printing, the reading unit is caused to read a white reference plate disposed opposite the reading unit, and shading correction of the reading unit is performed based on shading data acquired by the reading unit; During the reading operation of the printed matter by the reading unit, image data of the unprinted area of ​​the printed matter is extracted based on the scan data read by the reading unit, and paper color data in the reading unit is created based on the image data of the extracted unprinted area.

[0009] The invention described in claim 2 is the image reading device described in claim 1, The control unit The image data of the unprinted area is averaged in the sub-scanning direction to create the paper color data. The difference between the paper color data immediately after printing starts and the paper color data after N pages have been printed is reflected in the shading data.

[0010] The invention described in claim 3 is the image reading device described in claim 1, The control unit The image data of the unprinted area is averaged in the sub-scanning direction to create the paper color data. The difference between the paper color data immediately after printing starts and the paper color data after N pages have been printed is reflected in the scanned data.

[0011] The invention described in claim 4 is the image reading device described in claim 1, The control unit determines the unprinted area based on a correct image created for inspection, and extracts image data of the determined unprinted area.

[0012] The invention described in claim 5 is the image reading device described in claim 1, The control unit is characterized in that, when the data volume of the image data of the unprinted area does not meet a specified value, it creates the paper color data based on the image data of the unprinted area for a page whose data volume meets the specified value.

[0013] The invention described in claim 6 is the image reading device described in claim 1, The control unit creates the paper color data based on image data of the unprinted area of ​​the same type of paper.

[0014] The invention described in claim 7 is the image reading device described in claim 1, The reading unit a first reading unit that reads the surface of the printed material; a second reading unit that reads the back side of the printed matter; Equipped with The control unit performing shading correction of the first reading unit based on shading data obtained by reading a white reference plate disposed opposite the first reading unit with the first reading unit, and performing shading correction of the second reading unit based on shading data obtained by reading a white reference plate disposed opposite the second reading unit with the second reading unit; During the reading operation of the printed material by the first reading unit, image data of the unprinted area of ​​the printed material is extracted based on the scan data read by the first reading unit, and paper color data for the first reading unit is created based on the image data of the extracted unprinted area; and during the reading operation of the printed material by the second reading unit, image data of the unprinted area of ​​the printed material is extracted based on the scan data read by the second reading unit, and paper color data for the second reading unit is created based on the image data of the extracted unprinted area.

[0015] The invention described in claim 8 is In an image inspection system, a reading unit disposed downstream of the image forming device and configured to read a printed material on which an image has been formed by the image forming device; a control unit that controls reading by the reading unit; an inspection unit that inspects the image based on the scan data read by the reading unit and instructs the image forming apparatus to perform color correction; Equipped with The control unit Upon startup or before the image forming apparatus starts printing, the reading unit is caused to read a white reference plate disposed opposite the reading unit, and shading correction of the reading unit is performed based on shading data acquired by the reading unit; During the reading operation of the printed matter by the reading unit, image data of the unprinted area of ​​the printed matter is extracted based on the scan data read by the reading unit, and paper color data in the reading unit is created based on the image data of the extracted unprinted area.

[0016] The invention described in claim 9 is A reading control method for an image reading device that is disposed downstream of an image forming device and has a reading unit that reads a printed material on which an image is formed by the image forming device, comprising: a control step of controlling reading by the reading unit, The control step includes: a correction step of performing shading correction on the reading unit based on shading data acquired by reading a white reference plate disposed opposite the reading unit at the time of startup or before the image forming apparatus starts printing; a creating step of extracting image data of an unprinted area of ​​the printed matter based on the scan data read by the reading unit during the reading operation of the printed matter by the reading unit, and creating paper color data for the reading unit based on the extracted image data of the unprinted area; Includes.

[0017] The invention described in claim 10 is A computer of an image reading device, which is disposed downstream of an image forming device and has a reading unit for reading a printed matter on which an image is formed by the image forming device, functioning as a control unit that controls reading by the reading unit; The control unit Upon startup or before the image forming apparatus starts printing, the reading unit is caused to read a white reference plate disposed opposite the reading unit, and shading correction of the reading unit is performed based on shading data acquired by the reading unit; This program is characterized by extracting image data of the unprinted area of ​​the printed material based on the scan data read by the reading unit during the reading operation of the printed material by the reading unit, and creating paper color data in the reading unit based on the image data of the extracted unprinted area. [Effects of the Invention]

[0018] According to the present invention, it is possible to improve the accuracy of inspection and color measurement by an image inspection device without causing downtime. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a diagram showing a schematic configuration of an image inspection system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a functional block diagram showing a control structure of the image inspection system according to the present embodiment. [Figure 3] 10 is a flowchart illustrating an example of control before printing starts. [Figure 4] 10A and 10B are diagrams illustrating an example of a method for simply determining and extracting an unprinted area from a correct image. [Figure 5] FIG. 10 is an enlarged view of the letter "A" and its surroundings printed in a simple text area. [Figure 6] 10 is a flowchart showing an example of control during a printing operation for the first page. [Figure 7] 10 is a flowchart showing an example of control (1) during the printing operation of the second page. [Figure 8] FIG. 10 is a diagram showing an example of paper color data for the first page and the Nth page. [Figure 9]10A and 10B are diagrams illustrating an example of how a difference in paper color data is reflected in each piece of data in the reading control unit. [Figure 10] 10 is a flowchart showing an example of control (2) during the printing operation of the second page. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0021] 1 and 2, an image inspection system 1 according to this embodiment includes a print controller 10, a paper feeder 20, an image forming device 30, an image reading device 40, and a paper discharge device 50. The image inspection system 1 is connected to an external device 2 such as a PC via a NIC 13 of the print controller 10 so as to be able to send and receive information to and from the external device 2.

[0022] The print controller 10 manages and controls image data when the image forming apparatus 30 is used as a network printer. Image data is input to the image forming apparatus 30 from an external device 2 connected to a LAN. The print controller 10 receives image data to be printed from the external device 2 and transmits it to the image forming apparatus 30.

[0023] The print controller 10 includes a control unit 11, an image processing unit 12, and a NIC 13. The control unit 11 includes a CPU, a ROM, a RAM, etc., and controls the overall operation of each unit of the print controller 10. The control unit 11 outputs image data input from the external device 2 via the NIC 13 to the image forming apparatus 30. The image processing unit 12 performs rasterization (RIP) processing on the image data input from the external device 2 to generate image data (RIP image data) for each color of CMYK. The NIC 13 is a communication interface that receives image data to be printed from the external device 2 via a LAN.

[0024] The paper feed device 20 includes a plurality of paper feed trays 21 and a paper feed means (not shown), and feeds paper sheets P stored in the paper feed trays 21 to the image forming device 30. The paper feed means includes, for example, a paper feed roller, a separation roller, a paper feed / separation rubber, a delivery roller, etc. Each paper feed tray 21 stores paper sheets P according to their type (paper type, basis weight, paper size, etc.). The paper feed device 20 transports paper sheets P one by one from the top of the paper sheets P stored in each paper feed tray 21 to the image forming device 30.

[0025] The image forming device 30 is a multifunction peripheral that forms an image on paper based on image data read from an original and image data received via a LAN from an external device 2. The image forming device 30 includes a control unit 31, a storage unit 32, a reading unit 33, a scanner image processing unit 34, a printer image processing unit 35, and an image forming unit 36.

[0026] The control unit 31 includes a CPU, RAM, ROM, etc. First, the CPU reads various processing programs stored in the ROM and loads them into the RAM. Next, the CPU controls the overall operation of each unit of the image forming apparatus 30 in cooperation with the various programs loaded into the RAM.

[0027] The storage unit 32 stores programs that can be read by the control unit 31, files used when the programs are executed, etc. The storage unit 32 is, for example, a large-capacity memory such as a hard disk.

[0028] The reading unit 33 is comprised of an automatic document feeder, a scanner, etc., and reads the surface of a document set on a document table to generate image data in bitmap format. The image data generated by the reading unit 33 has pixel values ​​of three colors, R (red), G (green), and B (blue), for each pixel, and is color-converted into image data having pixel values ​​of four colors, C, M, Y, and K.

[0029] The scanner image processing unit 34 generates digital image data after performing various processes on the analog image data input from the reading unit 33. The various processes include analog processing, A / D conversion processing, shading processing, etc. The generated image data is output to the printer image processing unit 35.

[0030] The printer image processing unit 35 generates print image data based on image data input from the scanner image processing unit 34 or the image processing unit 12 of the print controller 10. The print image data is image data for image formation. The print image data generated by the printer image processing unit 35 is output to the image forming unit 36.

[0031] The image forming unit 36 ​​performs electrophotographic image forming processing and forms an image made up of four colors, C, M, Y, and K, on ​​paper in accordance with the pixel values ​​of the four colors of each pixel in the print image data.

[0032] The image forming section 36 includes a paper feed section 361 , a conveying section 362 , four writing units 363 , an intermediate transfer belt 364 , a transfer section 365 , and a fixing section 366 .

[0033] The paper feed unit 361 includes a plurality of paper feed trays and a paper feed means (not shown). The paper feed means includes, for example, a paper feed roller, a separation roller, a paper feed / separation rubber, a delivery roller, etc. Each paper feed tray stores paper sheets P according to their type (paper type, basis weight, paper size, etc.). The paper feed unit 361 transports the paper sheets P one by one from the top of the paper sheets P stored in each paper feed tray to the transport unit 362.

[0034] The transport unit 362 transports the paper transported from the paper feed unit 361 to the secondary transfer position of the image forming unit 36 ​​via a paper transport path to the transfer unit 365.

[0035] The four writing units 363 are arranged in series (tandem) along the belt surface of the intermediate transfer belt 364 and form images of the respective colors of C, M, Y, and K. The writing units 363 have the same configuration except for the colors of the images they form. Each writing unit 363 includes an exposure unit 363a, a photosensitive drum 363b, a development unit 363c, a charging unit 363d, a cleaning unit 363e, and a primary transfer roller 363f.

[0036] When forming an image, each writing unit 363 first charges the photosensitive drum 363b using the charging section 363d. Next, each writing unit 363 scans the photosensitive drum 363b with a light beam emitted by the exposure section 363a based on image data, forming an electrostatic latent image. Next, each writing unit 363 supplies toner using the developing section 363c to develop the image. This forms an image (a monochromatic toner image) on the photosensitive drum 363b. Next, each writing unit 363 primarily transfers the images formed on the photosensitive drum 363b onto the intermediate transfer belt 364 by using the corresponding primary transfer roller 363f, superimposing the images one on top of the other. As a result, an image made of each color (color toner image) is formed on the intermediate transfer belt 364. Next, each writing unit 363 causes the cleaning section 363e to remove any toner remaining on the photosensitive drum 363b.

[0037] Next, image forming unit 36 ​​feeds paper from paper feed device 20 or paper feed unit 361 in time with the image on rotating intermediate transfer belt 364 reaching the position of transfer unit 365. Next, image forming unit 36 ​​performs secondary transfer of the image (color toner image) from intermediate transfer belt 364 onto paper P using transfer unit 365. Next, image forming unit 36 ​​transports the paper to fixing unit 366 for fixing. The fixing process is a process in which fixing unit 366 applies heat and pressure to the paper to fix the image to the paper. When forming images on both sides of the paper, image forming unit 36 ​​transports the paper to inversion path R1 to invert the paper surface, and then transports the paper again to the position of transfer unit 365.

[0038] The image reading device 40 is disposed after the image forming device 30. The image reading device 40 includes a reading control unit 41, a reading unit 42, and a page memory 43.

[0039] The reading control unit 41 generates RGB digital image data after performing various processes on the analog image data input from the reading unit 42. The various processes include, for example, analog processing, A / D conversion processing, shading correction processing, color conversion processing, and magnification change processing. The generated image data is output to the page memory 43. The reading control unit 41 also controls reading by the reading unit 42. That is, the reading control unit 41 functions as a control unit of the present invention. For example, the reading control unit 41 acquires shading data used for shading correction of the reading unit 42 based on the reading result reflected by the white reference plate 421d and read by the CCD 421c.

[0040] The reading control unit 41 also inspects the image by comparing the correct image for inspection with the scan data read by the reading unit 42. This makes it possible to detect stains and misprints. Furthermore, the reading control unit 41 instructs the image forming device 30 to perform color correction based on the scan data read by the reading unit 42. In this case, the scan data is image data obtained by reading a patch image for image quality adjustment by the reading unit 42. As described above, the reading control unit 41 inspects the image based on the scan data read by the reading unit 42, and instructs the image forming apparatus 30 to perform color correction. In other words, the reading control unit 41 functions as an inspection unit of the present invention.

[0041] The reading unit 42 includes a first reading unit 421 and a second reading unit 422.

[0042] The first reading unit 421 reads the surface of a printed matter (paper P) on which an image has been formed by the image forming apparatus 30. The first reading unit 421 includes a light source 421a, an optical system 421b, a CCD 421c, and a white reference plate 421d.

[0043] The light source 421a is an LED (Light Emitting Diode) or a halogen lamp, and emits light onto the paper P transported to the reading position. The optical system 421b forms an image of the light (image of the reading position) emitted from the light source 421a and reflected by the paper P on the CCD 421c. The CCD 421c reads the image formed on the paper P at a predetermined reading position. Specifically, the CCD 421c reads the light reflected by the paper P. The CCD 421c is a color line sensor that can read the entire range of the width of the paper in the width direction. The white reference plate 421d is provided at a reading position and reflects light emitted from the light source 421a. The light reflected by the white reference plate 421d is read by the CCD 421c. The white reference plate 421d is read by the CCD 421c when no paper is passing through (for example, between papers).

[0044] The second reading unit 422 reads the back side of a printed matter (paper sheet P) on which an image has been formed by the image forming device 30. The second reading unit 422 is arranged downstream of the first reading unit 421 in the transport direction of the paper sheet P. The second reading unit 422 includes a light source 422a, an optical system 422b, a CCD 422c, and a white reference plate 422d. Note that the configuration of the second reading unit 422 is similar to the configuration of the first reading unit 421, and therefore a description thereof will be omitted.

[0045] As described above, the reading unit 42 includes the first reading unit 421 that reads the front side of the paper P and the second reading unit 422 that reads the back side of the paper P. This allows the reading unit 42 to read both sides of the paper P in one pass. The reading results (analog image data) read by the first reading unit 421 and the second reading unit 422 are output to the reading control unit 41.

[0046] The page memory 43 is configured by, for example, a DRAM, and stores the image data generated by the read control unit 41.

[0047] The paper discharge device 50 is disposed after the image reading device 40, and discharges the paper P, the image of which has been read by the image reading device 40, onto a paper discharge tray 51.

[0048] Next, the control of the image inspection system 1 according to this embodiment will be described with reference to the flowcharts of FIGS. 3 is a flowchart showing an example of control before the start of printing. The control before the start of printing is started when the reading control unit 41 of the image reading device 40 receives a request to start printing from the print controller 10 or the image forming device 30.

[0049] First, the reading control unit 41 acquires information necessary for creating paper color data (step S101). Specifically, the reading control unit 41 receives and acquires print data from the print controller 10. The reading control unit 41 also receives and acquires additional information from the image forming device 30. The additional information is patch information and register mark information that is added outside the user print area by the image forming device 30. The reading control unit 41 also receives and acquires setting information from the image forming device 30. The setting information is tray setting information and paper setting information. The tray setting information is information about the trays used for printing. The paper setting information is paper data (such as paper type) that is set for each tray.

[0050] Next, the reading control unit 41 creates a correct image for inspection (step S102). The correct image is created based on the print data and additional information acquired in step S101.

[0051] Next, the reading control unit 41 determines an unprinted area (blank portion) based on the correct image created in step S102 (step S103).

[0052] FIG. 4 is a diagram showing an example of a method for simply determining and extracting an unprinted area from a correct image. The area within the dashed line in Figure 4 is the user print area E1. The user print area E1 is the area where the print data acquired in step S101 is printed. The user print area E1 includes a graphics area E11 where graphics data is printed and a text area E12 where text data is printed. Within the user print area E1, the area that is neither the graphics area E11 nor the text area E12 is determined to be an unprinted area E13. The area outside the user print area E1 is the patch and register mark addition area E2, where patches for color correction and register marks for position correction are added.

[0053] In the example shown in FIG. 4, the text area E12 is simply shown as a rectangular area. The simplified text area E12 includes blank areas such as line spacing and character spacing. FIG. 5 is an enlarged view of the vicinity of the letter "A" printed in the simplified text area E12. In detail, the actual text area E121 is the area that outlines the outline of the letter "A" as shown in FIG. 5. Of the simplified text area E12, areas that are not the actual text area E121 (line spacing and character spacing) are determined to be unprinted areas E13. In other words, the simplified text area E12 includes the actual text area E121 and the unprinted area E13. In step S103, the unprinted area E13 included in the simplified text area E12 is also determined to be an unprinted area.

[0054] Next, the reading control unit 41 determines the creation page and creation cycle of the paper color data based on the unprinted area determined in step S103 and the setting information acquired in step S101 (step S104).

[0055] When the print coverage rate of a printed matter is high, it may be difficult to obtain image data of a sufficient size (data volume) for the unprinted areas on one page. A sufficient data volume is, for example, 128 pixels of data per pixel in the main scanning direction. Therefore, if the data volume of the image data of the unprinted areas does not meet a specified value, the reading control unit 41 creates paper color data based on the image data of the unprinted areas for pages whose data volume meets the specified value. For example, if the data volume of the image data of the unprinted areas for one page does not meet the specified value, but the data volume of the image data of the unprinted areas for three pages meets the specified value, the reading control unit 41 creates paper color data based on the image data of the unprinted areas for three pages. In other words, the reading control unit 41 can determine the paper color data creation cycle based on the unprinted areas determined in step S103.

[0056] Paper color data needs to be generated for paper of the same type (same paper type). Therefore, the reading control unit 41 creates paper color data based on image data of unprinted areas on paper of the same type. In the case of a MIX job in which paper of different paper types is mixed, the pages for which paper color data is created are limited based on information that can identify that the paper is of the same type. Information that can identify that the paper is of the same type is, for example, the setting information (tray setting information and paper setting information) acquired in step S101. In other words, the reading control unit 41 can determine the pages for which paper color data is created based on the setting information acquired in step S101.

[0057] Next, the reading control unit 41 performs shading correction before the start of printing (step S105). Specifically, the reading control unit 41 performs shading correction of the reading unit 42 based on the shading data at the time of startup or before the image forming apparatus 30 starts printing. The shading data is acquired by having the reading unit 42 read a white reference plate 421d arranged opposite the reading unit 42.

[0058] Next, the reading control unit 41 transmits a print preparation completion notice to the image forming apparatus 30 (step S106), which causes the image forming apparatus 30 to start printing.

[0059] 6, 7 and 10 are flowcharts showing an example of control during a printing operation. Control during a printing operation is initiated when printing is started in the image forming apparatus 30. FIG. 6 is a flowchart showing an example of control during the printing operation of the first page.

[0060] First, the reading control unit 41 causes the reading unit 42 to read the first page of the printed matter and creates scan data of the first page (step S201).

[0061] Next, the reading control unit 41 extracts the image data of the unprinted area determined in step S103 from the scan data created in step S201 (step S202).

[0062] Next, the reading control unit 41 determines whether or not the page and cycle for creating the paper color data determined in step S104 are the same (step S203). If the reading control unit 41 determines that the page and cycle are for creating paper color data (step S203: YES), the process proceeds to the next step S204. On the other hand, if the reading control unit 41 determines that the page is not a creation page or creation cycle for paper color data (step S203: NO), the reading control unit 41 completes the control for the first page. After that, the reading control unit 41 proceeds to control (2) during the printing operation for the second page (see FIG. 10).

[0063] In step S204, the reading control unit 41 averages the image data of the unprinted area extracted in step S202 to create paper color data for the first page. Specifically, the reading control unit 41 averages the image data of the unprinted area in the sub-scanning direction to create paper color data for the first page. The created paper color data is one-dimensional data in the main scanning direction. After that, the reading control unit 41 transitions to control (1) during the printing operation of the second page (see FIG. 7).

[0064] 7 and 10 are flowcharts showing an example of control during the printing operation of the second page. Fig. 7 shows control when step S204 is executed (control (1) during the printing operation of the second page). Fig. 10 shows control when step S204 is not executed (control (2) during the printing operation of the second page).

[0065] First, the control in FIG. 7 will be described. First, the reading control unit 41 causes the reading unit 42 to read the second page of the printed matter, and creates scan data of the second page (step S301).

[0066] Next, the reading control unit 41 extracts image data of the unprinted area determined in step S103 from the scan data created in step S301 (step S302).

[0067] Next, the reading control unit 41 determines whether or not the page and cycle for creating the paper color data determined in step S104 are the same (step S303). If the reading control unit 41 determines that the page and cycle are for creating paper color data (step S303: YES), the process proceeds to the next step S304. On the other hand, if the reading control unit 41 determines that the current page is not a creation page or creation cycle for paper color data (step S303: NO), it completes the control for the second page. After that, the reading control unit 41 proceeds to control (1) during the printing operation for the third page. Since control (1) during the printing operation for the third page and subsequent pages is the same as the control in FIG. 7, the control in FIG. 7 is repeated.

[0068] In step S304, the reading control unit 41 averages the image data of the unprinted area extracted in step S302 to create paper color data for page 2. After that, the reading control unit 41 proceeds to the next step S305.

[0069] Next, the reading control unit 41 calculates the amount of change based on the paper color data of the first page created in step S204 and the paper color data of the second page created in step S304 (step S305). The amount of change is the amount of change in illuminance of the light source 421a (422a), specifically, the amount of change in RGB luminance level. The amount of change is a ratio that indicates the percentage change per pixel in the main scanning direction. In the example shown in FIG. 7, since the second page has been printed, the paper color data of the first page and the paper color data of the second page are compared. For example, in the case of control (1) during the printing operation of the fifth page, since the fifth page has been printed, the paper color data of the first page and the paper color data of the fifth page are compared.

[0070] FIG. 8 is a diagram showing an example of paper color data for the first and Nth pages. The vertical axis represents the read value (brightness) of the reading unit 42. The horizontal axis represents the main scanning position. Symbol L1 in FIG. 8 represents paper color data for the first page. Symbol L2 represents paper color data for the Nth page. In step S305, the paper color data L2 of the Nth page is divided by the paper color data L1 of the 1st page to calculate the amount of change in illuminance (=L2 / L1 [%]).

[0071] Next, the reading control unit 41 determines whether or not it is necessary to reflect the change to each data based on the amount of change calculated in step S305 (step S306). Each data is shading data or scan data. For example, if the amount of change calculated in step S305 is equal to or greater than a predetermined threshold, the reading control unit 41 determines that it is necessary to reflect the change to each data. Note that it may also be configured to determine that it is necessary to reflect the change to each data in all cases where the amount of change is not 0. If the reading control unit 41 determines that it is necessary to reflect the changes in each piece of data (step S306: YES), the process proceeds to the next step S307. On the other hand, if the reading control unit 41 determines that it is not necessary to reflect the changes to each data (step S306: NO), it completes the control for the second page. After that, the reading control unit 41 moves to control (1) during the printing operation for the third page. Since control (1) during the printing operation for the third page and subsequent pages is the same as the control in FIG. 7, the control in FIG. 7 is repeated.

[0072] In step S307, the reading control unit 41 reflects the amount of change (difference) calculated in step S305 in each data. That is, the reading control unit 41 reflects the difference between the paper color data immediately after printing starts and the paper color data after N pages have been printed in the shading data or scan data. N pages is the number of pages printed up until it is determined that the change needs to be reflected in each data. In the example shown in FIG. 7, since the second page has been printed, N=2. Note that, for example, in the case of control (1) during the printing operation of the fifth page, since the fifth page has been printed, N=5. Thereafter, the reading control unit 41 proceeds to control (1) during the printing operation of the third page. Since control (1) during the printing operation of the third page and subsequent pages is the same as the control in FIG. 7, the control in FIG. 7 is repeated.

[0073] Fig. 9 is a diagram showing an example of how the difference in paper color data is reflected in each data in the reading control unit 41. For convenience of explanation, Fig. 9 shows only the first reading unit 421, but the same control is also performed in the second reading unit 422. The reading control unit 41 first performs shading correction on the scan data read by the CCD 421c. Next, the reading control unit 41 performs color conversion processing. Next, the reading control unit 41 performs magnification processing. The scan data that has undergone magnification processing is stored in the page memory. Shading correction is a process of correcting the maximum (white) and minimum (black) values ​​of RGB luminance read by the CCD 421c so that they match the Max / Min resolution. The Max / Min resolution values ​​are 255 and 0 for 8-bit gradation. Generally, the maximum value of RGB luminance is the value read from a white reference plate 422d placed at the reading position. The minimum value is the value read from black with the light source 421a turned off. The reading control unit 41 performs shading correction at startup or before printing begins, using the maximum / minimum values ​​of RGB luminance as shading data. In step S307, the difference between the paper color data immediately after printing starts and the paper color data after printing N pages is reflected in the shading data or scanned data. When reflecting in scanned data, paper color correction is performed to reflect in the scanned data after color conversion processing, as shown in Figure 9. When reflecting in shading data, the difference is reflected in the scanned data via the shading data during shading correction, so the above paper color correction is not performed.

[0074] Next, the control of FIG. 10 will be described. First, the reading control unit 41 causes the reading unit 42 to read the second page of the printed matter and creates scan data of the second page (step S401).

[0075] Next, the reading control unit 41 extracts the image data of the unprinted area determined in step S103 from the scan data created in step S401 (step S402).

[0076] Next, the reading control unit 41 determines whether or not the page and cycle for creating the paper color data determined in step S104 are the same (step S403). If the reading control unit 41 determines that the page and cycle are for creating paper color data (step S403: YES), the process proceeds to the next step S404. On the other hand, if the reading control unit 41 determines that the paper color data creation page or creation cycle is not in progress (step S403: NO), the reading control unit 41 completes the control for the second page. After that, the reading control unit 41 proceeds to control (2) during the printing operation for the third page. Since control (2) during the printing operation for the third page and subsequent pages is the same as the control in FIG. 10, the control in FIG. 10 is repeated.

[0077] In step S404, the reading control unit 41 averages the image data of the unprinted areas extracted in steps S202 and S402 to create paper color data for the first page. That is, the reading control unit 41 averages the image data of the unprinted areas of the first and second pages to create paper color data for the first page. Thereafter, the reading control unit 41 moves to control (2) during the printing operation for the third page. Since control (2) during the printing operation for the third page and subsequent pages is the same as the control in FIG. 10, the control in FIG. 10 is repeated.

[0078] As described above, during the reading operation of the reading unit 42 on the printed matter, the reading control unit 41 first extracts image data of the unprinted area (blank portion) of the printed matter based on the scan data read by the reading unit 42. Next, the reading control unit 41 creates paper color data for the reading unit 42 based on the image data of the extracted unprinted area.

[0079] The reading control unit 41 performs shading correction for the first reading unit 421 based on shading data acquired by having the first reading unit 421 read a white reference plate 421d disposed opposite the first reading unit 421. The reading control unit 41 performs shading correction for the second reading unit 422 based on shading data acquired by having the second reading unit 422 read a white reference plate 422d disposed opposite the second reading unit 422. During the reading operation of the printed material by the first reading unit 421, the reading control unit 41 first extracts image data of the unprinted area of ​​the printed material based on the scan data read by the first reading unit 421. Next, the reading control unit 41 creates paper color data for the first reading unit 421 based on the image data of the extracted unprinted area. During the reading operation of the printed material by the second reading unit 422, the reading control unit 41 first extracts image data of the unprinted area of ​​the printed material based on the scan data read by the second reading unit 422. Next, the reading control unit 41 creates paper color data for the second reading unit 422 based on the image data of the extracted unprinted area. As described above, the reading control unit 41 performs shading correction and paper color data generation for each of the first reading unit 421 and the second reading unit 422 independently.

[0080] As described above, the image reading device 40 according to this embodiment includes the reading unit 42 and the control unit (reading control unit 41). The reading unit 42 is disposed downstream of the image forming device 30 and reads printed materials on which images have been formed by the image forming device 30. The control unit controls the reading by the reading unit 42. At startup or before the image forming device 30 starts printing, the control unit performs shading correction of the reading unit 42 based on shading data acquired by having the reading unit 42 read white reference plates 421d, 422d disposed opposite the reading unit 42. While the reading unit 42 is reading the printed material, the control unit first extracts image data of the unprinted areas of the printed material based on the scan data read by the reading unit 42. Next, the control unit creates paper color data for the reading unit 42 based on the image data of the extracted unprinted areas. Therefore, with the image reading device 40 according to this embodiment, reading results that are not affected by changes in light intensity can be obtained without stopping printing, thereby improving the accuracy of inspection and color measurement by the image inspection device without causing downtime.

[0081] The control unit also creates paper color data by averaging the image data of the unprinted area in the sub-scanning direction. The control unit reflects the difference between the paper color data immediately after printing starts and the paper color data after N pages have been printed in the shading data or the scanned data. Therefore, it is possible to compare the level difference between the paper color data of the first page and the Nth page of printing. This allows the change in illuminance of light sources 421a and 422a to be detected with high accuracy. This improves the accuracy of inspection and color measurement by the image inspection device.

[0082] The control unit also determines an unprinted area based on a correct image created for inspection, and extracts image data of the determined unprinted area. Therefore, unprinted areas (blank areas) can be detected easily and accurately, which further improves the accuracy of inspection and color measurement by the image inspection device.

[0083] Furthermore, if the data amount of the image data of the unprinted area does not meet the specified value, the control unit creates paper color data based on the image data of the unprinted area for a page whose data amount meets the specified value. Therefore, even if image data of a sufficient size cannot be obtained for one page, image data of a sufficient size can be obtained, and paper color data can be created more reliably.

[0084] The control unit also creates paper color data based on image data of unprinted areas of the same type of paper. Therefore, even in the case of a MIX job in which a mixture of paper types is involved, paper color data can be created, which in turn makes it possible to more reliably improve the accuracy of inspection and color measurement by the image inspection device.

[0085] The reading unit 42 also includes a first reading unit 421 that reads the front side of the printed material and a second reading unit 422 that reads the back side of the printed material. The control unit performs shading correction for the first reading unit 421 based on shading data acquired by having the first reading unit 421 read a white reference plate 421d disposed opposite the first reading unit 421. The control unit performs shading correction for the second reading unit 422 based on shading data acquired by having the second reading unit 422 read a white reference plate 422d disposed opposite the second reading unit 422. First, while the first reading unit 421 is reading the printed material, the control unit extracts image data of the unprinted area of ​​the printed material based on the scan data read by the first reading unit 421. Next, the control unit creates paper color data for the first reading unit 421 based on the image data of the extracted unprinted area. First, while the second reading unit 422 is reading the printed matter, the control unit extracts image data of the unprinted area of ​​the printed matter based on the scan data read by the second reading unit 422. Next, the control unit creates paper color data for the second reading unit 422 based on the image data of the extracted unprinted area. Therefore, even if a sheet-fed press capable of double-sided printing is equipped with multiple reading units 42, it is possible to independently control each reading unit 42. Therefore, even in a sheet-fed press capable of double-sided printing, it is possible to improve the accuracy of inspection and color measurement by the image inspection device.

[0086] Although the present invention has been specifically described above based on the embodiments thereof, the present invention is not limited to the above embodiments and can be modified within the scope of the present invention.

[0087] For example, in the above embodiment, the reading control unit 41 functions as the inspection unit of the present invention, but this is not limiting. For example, the control unit 31 of the image forming apparatus 30 may function as the inspection unit of the present invention. Also, the control unit (not shown) of the external device 2 may function as the inspection unit of the present invention.

[0088] In addition, in the above embodiment, the present invention is applied to a sheet-fed printer capable of double-sided printing on sheets, but the present invention is not limited to this. For example, the present invention may be applied to a roll printer that forms images on continuous paper such as roll paper. In this case, since only the front side of the paper (continuous paper) is printed, it is sufficient that the reading unit 42 is only provided on the front side (first reading unit 421).

[0089] In the above embodiment, the image forming unit 36 ​​is described as employing an electrophotographic system, but the present invention is not limited to this. For example, other printing methods such as inkjet printing or thermal dye sublimation printing may be used instead of electrophotography.

[0090] In addition, the detailed configuration and operation of each device constituting the image inspection system can be modified as appropriate without departing from the spirit of the present invention. [Explanation of symbols]

[0091] 1. Image inspection system 10 Print Controller 11 Control section 12 Image processing section 13 NIC 20 Paper feeder 21 Paper tray 30 Image forming device 31 Control Unit 32 Storage section 33 Reading unit 34 Scanner image processing unit 35 Printer image processing unit 36 Image forming unit 361 Paper feed section 362 Conveyor 363 Writing Unit 363a Exposure section 363b Photosensitive drum 363c developing section 363d Charging part 363e Cleaning Department 363f Primary transfer roller 364 Intermediate transfer belt 365 Transcription Department 366 Fixing part 40 Image reader 41 Reading control unit (control unit, inspection unit) 42 Reading unit 421 First Reading Unit 421a light source 421b Optical system 421c CCD 421d White reference plate 422 Second reading unit 422a light source 422b Optical system 422c CCD 422d White reference plate 43 page memory 50 Paper ejection device 51 Paper output tray 2 External device P Paper

Claims

1. a reading unit disposed downstream of the image forming device and configured to read a printed material on which an image has been formed by the image forming device; a control unit that controls reading by the reading unit; Equipped with The control unit Upon startup or before the image forming apparatus starts printing, the reading unit is caused to read a white reference plate disposed opposite the reading unit, and shading correction of the reading unit is performed based on shading data acquired by the reading unit; An image reading device characterized in that, during the reading operation of the printed material by the reading unit, image data of the unprinted area of ​​the printed material is extracted based on the scan data read by the reading unit, and paper color data in the reading unit is created based on the image data of the extracted unprinted area.

2. The control unit The image data of the unprinted area is averaged in the sub-scanning direction to create the paper color data.

2. The image reading device according to claim 1, wherein a difference between the paper color data immediately after printing starts and the paper color data after N pages have been printed is reflected in the shading data.

3. The control unit The image data of the unprinted area is averaged in the sub-scanning direction to create the paper color data.

2. The image reading device according to claim 1, wherein a difference between the paper color data immediately after printing starts and the paper color data after N pages have been printed is reflected in the scanned data.

4. 2. The image reading device according to claim 1, wherein the control unit determines the unprinted area based on a correct image created for inspection, and extracts image data of the determined unprinted area.

5. The image reading device according to claim 1, characterized in that, when the data volume of the image data of the unprinted area does not meet a specified value, the control unit creates the paper color data based on the image data of the unprinted area for a page whose data volume meets the specified value.

6. 2. The image reading device according to claim 1, wherein the control unit creates the paper color data based on image data of the unprinted area of ​​the same type of paper.

7. The reading unit a first reading unit that reads the surface of the printed matter; a second reading unit that reads the back side of the printed matter; Equipped with The control unit performing shading correction of the first reading unit based on shading data obtained by reading a white reference plate disposed opposite the first reading unit with the first reading unit, and performing shading correction of the second reading unit based on shading data obtained by reading a white reference plate disposed opposite the second reading unit with the second reading unit; The image reading device described in claim 1, characterized in that during the reading operation of the printed material by the first reading unit, image data of the unprinted area of ​​the printed material is extracted based on the scan data read by the first reading unit, and paper color data for the first reading unit is created based on the image data of the extracted unprinted area, and during the reading operation of the printed material by the second reading unit, image data of the unprinted area of ​​the printed material is extracted based on the scan data read by the second reading unit, and paper color data for the second reading unit is created based on the image data of the extracted unprinted area.

8. a reading unit disposed downstream of the image forming device and configured to read a printed material on which an image has been formed by the image forming device; a control unit that controls reading by the reading unit; an inspection unit that inspects the image based on the scan data read by the reading unit and instructs the image forming apparatus to perform color correction; Equipped with The control unit Upon startup or before the image forming apparatus starts printing, the reading unit is caused to read a white reference plate disposed opposite the reading unit, and shading correction of the reading unit is performed based on shading data acquired by the reading unit; An image inspection system characterized by extracting image data of unprinted areas of the printed material based on the scan data read by the reading unit during the reading operation of the printed material by the reading unit, and creating paper color data in the reading unit based on the image data of the extracted unprinted areas.

9. A reading control method for an image reading device that is disposed downstream of an image forming device and has a reading unit that reads a printed material on which an image is formed by the image forming device, comprising: a control step of controlling reading by the reading unit, The control step includes: a correction step of performing shading correction on the reading unit based on shading data acquired by reading a white reference plate disposed opposite the reading unit at the time of startup or before the image forming apparatus starts printing; a creating step of extracting image data of an unprinted area of ​​the printed matter based on the scan data read by the reading unit during the reading operation of the printed matter by the reading unit, and creating paper color data for the reading unit based on the extracted image data of the unprinted area; A reading control method including:

10. A computer of an image reading device, which is disposed downstream of an image forming device and has a reading unit for reading a printed matter on which an image is formed by the image forming device, functioning as a control unit that controls reading by the reading unit; The control unit Upon startup or before the image forming apparatus starts printing, the reading unit is caused to read a white reference plate disposed opposite the reading unit, and shading correction of the reading unit is performed based on shading data acquired by the reading unit; A program characterized by extracting image data of an unprinted area of ​​the printed material based on the scan data read by the reading unit during the reading operation of the printed material by the reading unit, and creating paper color data in the reading unit based on the image data of the extracted unprinted area.

Images