JP2020037232A - Image formation system and image inspection method - Google Patents

Abstract

To provide an image formation system which can reduce the waste of sheets due to an incompatible portion included in the sheet itself.SOLUTION: An image formation system includes: an image formation unit which performs image formation on a sheet; an image inspection unit which acquires information on the surface of the sheet before the image formation and information on the surface of the sheet after the image formation; and a determination unit which determines the image formation failure in the image formation by excluding the information on the surface of the sheet before the image formation from the information on the surface of the sheet after the image formation.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming system including an image inspection unit and an image inspection method.

  Paper printed by the image forming apparatus may include stains or foreign substances on the printing surface for various reasons. A method has been proposed in which, for a sheet containing such dirt and foreign matter, a dirt or foreign matter on the printing surface of the sheet is detected by an automatic image inspection unit or the like before image formation, and whether or not printing on the printing surface is possible is determined. (For example, see Patent Document 1).

JP 2011-201021 A

  However, the paper includes non-conforming portions such as minor stains and foreign substances that do not affect images, characters, and the like printed on the surface of the paper due to the material and the like that constitute the paper. For this reason, if the detection accuracy of the image inspection unit is high, even a small nonconforming portion that does not affect the printed image or character included in the paper is detected as a paper defect.

  In the method described in Patent Literature 1, dirt on the print surface of the paper is detected. However, if the detection accuracy of the image inspection unit is high, an incompatible portion included in the paper itself is also detected as dirt. For this reason, even paper that does not affect printing of images, characters, and the like is discarded without being printed, and the paper is wasted.

  In order to solve the above-described problem, the present invention provides an image forming system and an image inspection method capable of reducing waste of paper caused by an incompatible portion included in paper itself.

  An image forming system according to the present invention includes: an image forming unit that forms an image on a sheet; an image inspection unit that acquires information on the surface of the sheet before the image is formed; and information on the surface of the sheet after the image is formed. A discriminating unit for discriminating image formation failure in image formation by excluding information on the surface of the sheet before image formation from information on the surface of the sheet afterward.

  Further, the image inspection method of the present invention obtains information on the surface of the sheet before image formation in the image inspection section, forms an image on the surface of the sheet in the image formation section, and outputs the image on the sheet after image formation in the image inspection section. The information on the front side is acquired, and the discrimination unit discriminates the image formation failure in the image formation by excluding the information on the front side of the sheet before the image formation from the information on the surface of the sheet after the image formation.

  According to the present invention, it is possible to provide an image forming system and an image inspection method capable of reducing waste of paper due to a nonconforming portion included in paper itself.

FIG. 1 is a diagram illustrating a schematic configuration of an image forming system according to a first embodiment. FIG. 3 is a functional block diagram of a control unit of the image forming system according to the first embodiment. It is a table | surface which shows the determination conditions of a non-conforming part. FIG. 6 is a diagram illustrating an example of an operation screen of an image forming job displayed on an operation display unit of the image forming system. FIG. 6 is a diagram illustrating an example of a paper profile screen displayed on the operation display unit of the image forming system. FIG. 9 is a diagram illustrating an example of a screen for changing a setting of a paper profile displayed on the operation display unit of the image forming system. It is a figure showing the flow chart of the image inspection method of a 1st embodiment. FIG. 3 is a diagram illustrating an XY coordinate of a nonconforming portion of a sheet. FIG. 6 is a diagram illustrating an irrelevant portion of a sheet and a defective image in XY coordinates. FIG. 2 is a diagram illustrating a schematic configuration of an image forming system according to a second embodiment. It is a figure showing the flow chart of the image inspection method of a 2nd embodiment. It is a figure showing the flow chart of the image inspection method of a 2nd embodiment. FIG. 6 is a diagram illustrating an example of an operation screen of an image forming job displayed on an operation display unit of the image forming system. FIG. 6 is a diagram illustrating an example of an operation screen of an image forming job displayed on an operation display unit of the image forming system.

Hereinafter, examples of embodiments for carrying out the present invention will be described, but the present invention is not limited to the following examples.
The description will be made in the following order.
1. Image forming system and image inspection method (first embodiment)
2. Image forming system and image inspection method (second embodiment)

<1. Image forming system and image inspection method (first embodiment)>
Hereinafter, a first embodiment of an image forming system and an image inspection method of the present invention will be described.

[Schematic Configuration of Image Forming System]
FIG. 1 shows a schematic configuration diagram of the image forming system of the present embodiment.
The image forming system 100 shown in FIG. 1 includes an image forming apparatus 10, a first image inspection unit 15, a second image inspection unit 16, a sheet feeding device 17, and a post-processing device 18. The configuration of the image forming system 100 is not limited to this, and another device may be connected. For example, a relay device or the like may be provided between the image forming apparatus 10 and another device.

  The paper feeding device 17 is arranged on the upstream side of the image forming apparatus 10 in the paper conveyance direction, and has a plurality of paper feeding trays for storing paper (recording medium) on which an image is formed in the image forming apparatus 10. . When an image forming job is selected, the sheet feeding device 17 takes out a sheet from a sheet feeding tray using a pickup roller, a separating roller, or the like. Then, the taken out paper is transported to the image forming apparatus 10 via the first image inspection unit 15 one by one by a transport roller or the like.

  The image forming apparatus 10 includes, for example, an MFP (multi-function peripheral) 11 having the functions of a scanner, a color copier, and a color laser printer, and a paper feed unit 14 that supplies the MFP 11 with paper for image formation. Is done. The MFP 11 includes an automatic document feeder 12, an image forming unit 13, and an operation display unit 60.

  The automatic document feeder 12 automatically feeds a document when reading the document. The automatic document feeder 12 can read an image of a document automatically conveyed by the automatic document feeder 12 by a scanner provided therein.

  The image forming unit 13 includes a charging unit, a photoconductor, an exposing unit, a developing unit, an intermediate transfer belt, a fixing unit, and the like. In the image forming unit 13, the charging unit applies a charge to the photoconductor, and then irradiates a laser beam from the exposure unit to form an electrostatic latent image on the photoconductor. Then, the electrostatic latent image is visualized on the surface of the photoreceptor in the developing unit to form a toner image. Thereafter, the toner image is transferred to the intermediate transfer belt, and the toner image transferred to the intermediate transfer belt is transferred at a predetermined timing to the surface of the sheet conveyed. The sheet on which the image has been transferred is transported to the fixing unit. The fixing unit includes, for example, a pressure roller, a fixing roller, and a belt, and performs heating and pressure processing on the sheet on which the toner image has been formed to fix the toner image on the sheet.

The paper supply unit 14 includes a plurality of paper storage units that can store paper of different sizes and types. The paper feeding unit 14 takes out the paper from the corresponding paper storage unit based on an instruction from the MFP 11 and conveys the paper to the image forming unit 13.
The operation display unit 60 has a function as an operation unit for instructing start of a job such as an image forming process. The operation display unit 60 also serves as an operation unit and a display unit. The operation display unit 60 is configured by a touch panel including an LCD (Liquid Crystal Display) and the like, and allows a user to operate and display information. The operation unit may be configured by a mouse, a tablet, or the like, and may be configured separately from the display unit.

A first image inspection unit 15 and a second image inspection unit 16 are provided before and after the image forming unit 13. The first image inspection unit 15 is disposed between the sheet feeding device 17 and the image forming apparatus 10. The second image inspection unit 16 is disposed between the image forming apparatus 10 and the post-processing device 18.
The first image inspection unit 15 and the second image inspection unit 16 include a line sensor using a CCD (Charge Coupled Device) sensor, a CIS (Contact Image Sensor), or the like. Then, the first image inspection unit 15 and the second image inspection unit 16 read an image of the front surface (at least one of the top surface and the back surface) of the conveyed paper, and read the read result (read image data). get. Then, the quality of the image is automatically inspected based on the information on the surface of the read paper.

  The post-processing device 18 performs post-processing on the sheet received from the second image inspection unit 16 according to an instruction from the MFP 11. The post-processing includes, for example, a process of aligning a sheet with a bundle and a process of binding the bundle with staples. The post-processing device 18 includes a plurality of paper discharge trays. For example, it has a tray for discharging paper output normally without occurrence of image formation failure and the like, and a sub-tray for discharging paper excluded due to occurrence of image formation failure and the like.

  In the above description, the image forming apparatus 10 is an electrophotographic image forming apparatus, but the image forming apparatus applied to the image forming system 100 is not limited to this. The image forming apparatus applied to the image forming system 100 may be, for example, an inkjet type image forming apparatus or another type of image forming apparatus.

[Functional Block Diagram of Control Unit of Image Forming System]
FIG. 2 is a functional block diagram of the control unit of the image forming system 100 described above.
The above-described image forming system 100 has a control unit 20 for controlling the entire image forming system 100. Further, an engine control unit 40 and a system control unit 30 that are provided so as to be able to communicate with a control unit 20 that controls the entire image forming system 100 and control each configuration of the image forming system 100 according to an instruction from the control unit 20. , A post-processing control unit 70, an image detection unit 50, and an operation display unit 60.

  The control unit 20 of the image forming system includes a CPU 21, a RAM 22, and a ROM 23. The CPU 21 controls the engine control unit 40, the system control unit 30, the post-processing control unit 70, the image detection unit 50, the operation display unit 60, and the like according to a program such as firmware. The RAM 22 provides the CPU 21 with a work area when the CPU 21 executes the firmware, and stores image information read by the image detection unit 50, print conditions received by the operation display unit 60, and the like. The ROM 23 includes a non-writable semiconductor memory device in which information such as firmware is stored, a rewritable semiconductor memory device such as an EEPROM for providing a storage area for environmental variables and the like to the CPU 21, an HDD, and the like.

  The engine control unit 40 controls a sheet conveyance unit 41 that conveys sheets of the entire image forming system. Further, the engine control unit 40 controls conveyance of the sheet in the image forming unit 42 for image formation. The control of the engine control unit 40 is performed by the CPU 21 of the control unit 20 executing dedicated firmware. The engine control unit 40 controls the sheet conveyance operation in the normal job processing by the control unit 20.

  The engine control unit 40 controls each motor drive circuit and each motor according to the operation mode of the image forming system 100, job conditions, and the like. The motor drive circuit drives each motor in accordance with an instruction from the engine control unit 40, and the movement of the sheet from the sheet feeding unit to the image forming unit 42 and the movement of the sheet in the image forming unit 42 are performed.

  The image detection unit 50 includes a nonconforming portion detection unit 51 before image formation and a defective image detection unit 52 after image formation. The image data acquired by the image detection unit 50, the candidate of the non-conforming portion of the detected sheet, and the defective image are transferred to the RAM 22, the ROM 23, or the like of the control unit 20. In the image detecting unit 50, a conventionally known method can be applied as a method of reading an image and a method of creating read image data.

  The non-conforming unsuitable portion detecting unit 51 optically reads information on the surface of the sheet before image formation supplied to the image forming apparatus 10 and acquires image data. Further, a nonconforming portion such as dirt or foreign matter on the paper is detected from the read image data. For example, the non-conforming non-conforming portion detecting unit 51 compares the pre-registered sheet information (paper profile) with the image data obtained by the non-conforming non-conforming portion detecting unit 51 to obtain a difference. Then, the difference is detected as a candidate of a nonconforming portion of the sheet before image formation.

  The post-image formation defective image detection unit 52 optically reads information on the surface of the sheet after image formation supplied to the image forming apparatus 10 and acquires image data. Further, a defective image is detected from the read image data. For example, information on a reference image used for image formation is compared with information on the surface of the sheet after image formation obtained by the post-image formation defective image detection unit 52 to obtain a difference. Then, according to the obtained difference, a defective image is detected from the level, shape, and the like of the difference.

  As the information on the surface of the sheet acquired by the non-conforming part detecting unit 51 before image formation and the defective image detecting unit 52 after image forming, for example, non-conforming parts such as dirt and foreign matter caused by the material constituting the sheet, and And image formation defects such as white spots, streaks, stains, and rubbing caused by image formation. Further, the non-conforming portion detection unit 51 before image formation and the defective image detection unit 52 after image formation can also obtain the whiteness of the paper and the chromaticity of the paper as information on the surface of the paper. By acquiring whiteness and chromaticity as information on the surface of the paper before image formation, non-conforming places such as dirt and foreign matter due to the material constituting the paper can be identified in the image forming unit by using the same color image as a non-conforming place. Is provided to the paper correction unit 36 to determine whether the correction is made by filling in. Also, by obtaining whiteness and chromaticity as information on the surface of the paper after correction (after image formation), the whiteness and chromaticity of the paper surface can be compared with the whiteness and chromaticity of the corrected portion. Then, information for determining whether the correction amount is appropriate is provided to the paper correction unit 36.

  When the image forming system 100 includes a first image inspection unit 15 arranged on the upstream side of the image forming apparatus 10 and a second image inspection unit 16 arranged on the downstream side of the image forming apparatus 10 The first image inspection unit 15 is provided with a non-conforming spot detection unit 51 before image formation, and the second image inspection unit 16 is provided with a defective image detection unit 52 after image formation. Then, the non-conforming pre-image forming portion detecting unit 51 acquires information on the surface of the sheet before the image forming, on the upstream side of the image forming unit 42 in the sheet conveying direction. Further, the post-image formation defective image detection unit 52 acquires information on the surface of the sheet after image formation downstream of the image formation unit 42 in the sheet conveyance direction.

  When the image forming system 100 has an image inspection unit only on the downstream side of the image forming apparatus 10, the non-conforming portion detection unit 51 before image formation and the defective image detection unit 52 after image formation are the same image inspection unit. May be provided. In this case, information on the surface of the sheet before image formation and information on the surface of the sheet after image formation are acquired by the image inspection unit downstream of the image forming unit 42 in the sheet conveyance direction.

  The system control unit 30 includes a paper mismatch condition storage unit 31, a paper mismatch location determination unit 32, a paper mismatch information storage unit 33, a determination unit 34, an image formation failure detection unit 35, and a paper correction unit 36. .

  The paper nonconformity condition storage unit 31 stores conditions for determining nonconformity of the paper from information on the surface of the paper read by the image detection unit 50. The conditions (judgment conditions) for determining non-conformity include, for example, a threshold value of a color gamut that is determined to be a non-conforming place such as dirt or a foreign substance caused by a material constituting a sheet, and a threshold value of an area that is determined to be non-conforming. And at least one type of information. Further, the paper nonconforming condition storage unit 31 stores the type of paper, and stores a determination condition for each type of paper.

  As the determination conditions, for example, as shown in FIG. 3, a threshold value of an area of dirt or foreign matter, a threshold value of a density of dirt or foreign matter, or the like, which is determined as an unsuitable portion for each reference, is set as a determination condition. For this, criteria such as “loose”, “standard”, and “strict” are set. Then, by selecting the set criterion, it is determined whether the sheet is a non-conforming part due to the material of the sheet or a non-conforming part due to the other. For example, non-conforming places other than the material of the paper include toner and ink adhesion. Then, the type or the like of the nonconforming portion that is likely to occur according to the type of the paper is registered (stored), and the other is determined as nonconforming due to a material other than the paper material. Note that these determination conditions are merely examples, and the types of setting criteria and the types and values of thresholds in each setting criteria can be set as appropriate.

  When a judgment condition is set from the operation display unit 60 by a user or the like, the sheet nonconformity condition storage unit 31 stores the judgment condition set by the user or the like. The paper nonconforming condition storage unit 31 may register and store the determination conditions set by the user or the like as the determination conditions of the paper profile for each type of paper.

  The non-conforming sheet determining unit 32 determines a non-conforming candidate candidate detected by the non-conforming non-conforming part detecting unit 51 before image formation as a non-conforming sheet based on the non-conforming determining condition stored in the non-conforming condition storing unit 31. Judge. Then, the information of the determined nonconforming part is sent to the paper nonconforming information storage unit 33. The nonconforming portion determining section 32 determines the position of the nonconforming portion and the size of the nonconforming portion represented by the XY coordinates based on the corners of the sheet, for example, as the nonconforming portion information. It is sent to the nonconformity information storage unit 33.

  The paper nonconformity information storage unit 33 stores the information on the surface of the paper before image formation obtained by the nonconforming part detection unit 51 before image formation. Further, the paper nonconformity information storage unit 33 stores information on the nonconforming part determined by the nonconforming part determination unit 32 as information on the surface of the paper before image formation. At this time, the paper nonconformity information storage unit 33 may store only the information on the nonconforming part determined by the nonconformity part determining unit 32 as the information on the surface of the paper before image formation.

  The determination unit 34 compares the information of the defective image after the image formation detected by the defective image detection unit 52 after the image formation with the information of the nonconforming portion of the sheet before the image stored in the sheet nonconformity information storage unit 33. . In this way, it is possible to determine an image formation defect in image formation and an unsuitable portion of the sheet before image formation. Then, the result of the determination is sent to the image formation failure detecting unit 35.

  The image formation failure detection unit 35 determines the presence or absence of a defective image on a sheet based on the determination result of the determination unit 34, and detects a sheet having an image formation failure. Then, it outputs to the control unit 20 that the image forming failure has occurred in the image forming unit. The control unit 20 stops the image forming operation based on the information of the image forming failure detecting unit 35. Alternatively, a sheet having a defective image may be discharged to a discharge destination different from a normal discharge destination without stopping the image forming operation.

  The paper correction unit 36 is based on the information on the whiteness and chromaticity of the paper acquired by the non-conforming portion detection unit 51 before image formation and the information on the non-conforming portion determined by the non-conforming portion determining unit 32. It is determined whether or not an incompatible portion on the surface of the sheet before image formation can be corrected. For example, the paper correcting unit 36 compares the whiteness or chromaticity of the paper acquired by the non-conforming portion detection unit 51 before image formation with the whiteness or chromaticity of the white image formed by the image forming unit 42. Then, when the whiteness difference or the chromaticity difference is within a predetermined range, it is determined that the nonconforming portion can be corrected.

When determining that the non-conforming portion of the sheet is to be corrected, the paper correcting unit 36 sends an instruction to draw an image to fill the non-conforming portion to the image forming unit 42. Alternatively, on the operation display unit 60, the user is notified that the non-conforming portion and the non-conforming portion of the paper can be corrected, and the user is allowed to select whether to execute the correction.
After receiving an instruction to correct the paper from the paper correction unit 36 or the user, the image forming unit specifies the paper color and the non-conforming part, for example, from the whiteness and chromaticity information of the paper and the information of the non-conforming part. . Then, the image forming unit 42 draws an image of the same color as the sheet at the position of the non-conforming portion, and fills the non-conforming portion with the same color as the sheet, thereby correcting the non-conforming portion of the sheet.

  Further, the paper correction unit 36 obtains the whiteness and chromaticity of the paper surface and the whiteness of the corrected portion from information on the paper surface after correction (after image formation) acquired by the defective image detection unit 52 after image formation. And chromaticity to determine whether the correction amount is appropriate. When determining that the correction amount is not appropriate, the paper correction unit 36 instructs the image forming unit 42 to adjust the correction amount so that the correction amount is optimal. The image forming unit 42 corrects the paper with the correction amount adjusted for the subsequent paper.

The operation display unit 60 is controlled by the control unit 20, and displays information and receives operation input. The operation display unit 60 includes a paper setting unit 61 and a paper mismatch detection condition setting unit 62.
The paper setting unit 61 sets paper information such as the paper type (plain paper, coated paper, etc.) and basis weight of the paper to be used. The conditions set by the user to be determined as nonconforming are stored in the paper nonconforming condition storage unit 31. This paper information may be registered in a paper profile. For example, in FIG. 4, the operation display unit 60 of the image forming system 100 displays a command button 63 for selecting a sheet setting on the operation screen of the image forming job.

  After selecting the paper setting command button 63, a paper profile screen is displayed as shown in an example in FIG. The paper profile includes information such as a paper profile name, paper type, and size, as well as a threshold of a color gamut that is determined to be a nonconforming portion such as dirt or a foreign substance caused by a material constituting the paper, and a nonconformity. , The possibility of correcting the nonconforming portion in the paper correction section 36, and information on whether or not the corrected nonconforming portion is detected as an image formation defect. A command button 64 for changing the setting of the paper profile is displayed on the paper profile screen.

  After selecting the command button 64 for changing the setting of the paper profile, as shown in an example in FIG. 6, "loose", "standard", and "standard" for each paper determination condition (in FIG. 6, area and density). A command button for selecting a criterion such as "strict" is displayed. Also, a command button for selecting whether or not the non-conforming portion can be corrected by the paper correcting section 36 and whether or not to detect the corrected non-conforming portion as an image formation defect is displayed.

The paper nonconformity detection condition setting unit 62 displays a screen for inputting a condition on the operation display unit 60 so that the user can set a condition for determining nonconformity, and accepts a condition set by the user. In addition, the paper nonconformity detection condition setting unit 62 displays the screen selected by the user on the operation display unit 60, or receives the user's instruction, by including the portion where the nonconforming portion is corrected in the determination of the image formation defect in the determination unit 34. Is also good.
The post-processing control unit 70 performs post-processing on the sheet received via the second image inspection unit 16 according to an instruction from the control unit 20. The post-processing includes, for example, a process of aligning a sheet with a bundle and a process of binding the bundle with staples.

[Flowchart of image inspection method]
Next, the above-described image inspection method will be described with reference to a flowchart. FIG. 7 shows a flowchart of the image inspection method.

  First, paper is fed from the paper feeding device 17 or the paper feeding unit 14 to the first image inspection unit 15, and an unsuitable portion such as dirt or foreign matter on the paper is detected from image data on the surface of the paper before image formation. (Step S101). In the detection of the nonconforming portion of the sheet, the nonconforming portion detecting section 51 before image formation optically reads information on the surface of the sheet before image formation to acquire image data, and from the image data, detects nonconformity such as dirt or foreign matter on the sheet. A candidate for a location is detected. Then, the paper nonconforming part determining unit 32 compares the nonconforming part candidate detected by the pre-image forming nonconforming part detecting unit 51 with a condition (determination condition) for determining nonconformity stored in the paper nonconforming condition storage unit 31. Then, it is determined whether or not the sheet is non-conforming, and the non-conforming part of the sheet is detected.

  Next, it is determined whether a nonconforming portion such as dirt or foreign matter is detected on the sheet (step S102). If a nonconforming portion is detected (YES in step S102), information on the portion determined to be nonconforming is determined. Then, the sheet nonconformity information storage unit 33 stores the information (step S103). For example, as shown in FIG. 8, an XY coordinate based on a corner 83 of a sheet is assigned to a nonconforming portion 82 detected on the surface of the sheet 81. In FIG. 8, the XY coordinates of the start point (X1-S) and the end point (X1-E) in the X coordinate, and the start point (Y1-S) and the end point (Y1-E) in the Y coordinate are given to the nonconforming portion 82. . With the XY coordinates, a position in the X coordinate, a length in the X coordinate direction, a position in the Y coordinate, and a length in the Y coordinate direction are given to the nonconforming portion 82. Then, the position and size of the nonconforming portion 82 given by the XY coordinates are sent to the sheet nonconforming information storage unit 33 as information on the nonconforming portion.

  If no nonconforming part is detected (NO in step S102), or after the nonconforming part information is stored in the sheet nonconformity information storage unit 33 in step S103, step S102 is performed on all sheets used for image formation. It is determined whether the detection of the non-conforming part has been completed (step S104). If the detection of the nonconforming portion in step S102 has not been completed for all the sheets (NO in step S104), the processing in step S102 and step S103 is repeated until the detection is completed for all the sheets.

  When the detection of the nonconforming portion in step S102 is completed for all the sheets (YES in step S104), it is determined whether the sheet correcting section 36 performs the correction on the detected nonconforming portion of the sheet (step S105). ). The execution of the correction is determined by the paper correction unit 36 as to whether or not the nonconforming portion can be corrected, and when the correction can be performed, the determination is made in accordance with a user instruction or the like. In the case of performing the correction (YES in step S105), the paper correcting unit 36 instructs the image forming unit 42 to draw and fill an image of the same color as the paper at the position of the nonconforming portion, thereby correcting the nonconforming portion of the paper. (Step S106).

  After correcting the nonconforming portion in step S106, or when not performing the correction (NO in step S105), the image forming unit 42 forms an image on a sheet according to an image forming job (step S107).

  Next, a defective image is detected from the image data on the surface of the sheet after image formation (step S108). The defective image is detected by optically reading the sheet after image formation by the defective image detection unit 52 after image formation, and detecting the defective image from the image data. Then, the defective image detected in step S108 is compared with the nonconforming portion of the sheet before image formation, and it is determined whether the defective image matches the nonconforming portion (step S109).

  For example, as shown in FIG. 9, a defective image 85 is formed on a sheet 81 after image formation, along with an inconsistent portion 82 detected before image formation and an image 84 formed normally based on image data. . In step S108, XY coordinates based on the corner 83 of the sheet are assigned to the detected defective image 85. In FIG. 9, the XY coordinates of the start point (AX1-S) and the end point (AX1-E) in the X coordinate and the start point (AY1-S) and the end point (AY1-E) in the Y coordinate are given to the defective image 85. . The XY coordinates of the start point (BX1-S) and end point (BX1-E) on the X coordinate and the start point (BY1-S) and end point (BY1-E) on the Y coordinate are given to the nonconforming portion 82. Thereby, the position in the X coordinate, the length in the X coordinate direction, the position in the Y coordinate, and the length in the Y coordinate direction are given to the defective image 85 and the nonconforming portion 82. Then, information about the defective image 85 such as the position and size given by the XY coordinates on the paper 81 after image formation and the nonconforming portion 82 are acquired.

  Then, the discriminator 34 compares the information such as the position and size of the defective image 85 acquired in step S108 with the information on the position and size of the nonconforming portion 82 stored in the paper nonconformity information storage 33 in step S103. By performing the comparison, the defective image is determined to be an image formation defect in image formation and an unsuitable portion of the sheet before image formation. Then, a defective image corresponding to a nonconforming portion of the sheet is excluded, and only a defective image formed by image formation is detected. Thereby, it is determined whether or not all the detected defective images match the nonconforming portion of the sheet.

If all the defective images match the non-conforming portions of the sheet (YES in step S109), the sheet correction unit 36 determines whether the correction has been performed in step S106 (step S110). This process is performed to correct the correction amount in step S106 when the correction location in step S106 is detected as a defective image in step S108. Therefore, when the correction is not performed in step S106 (NO in step S110), all the detected defective images are determined as the defective images that match the nonconforming portion of the sheet, and the image forming failure in the image forming unit 42 is performed. (Step S111).
On the other hand, when the correction has been performed in step S106 (YES in step S110), it is determined whether or not the corrected portion detected as the defective image is detected as the target of the image forming defect in the image forming unit 42 ( Step S113). In this processing, it is determined whether or not the correction portion is to be detected according to a paper profile registered in advance, an instruction from the user, or the like.

  If the corrected portion is not detected as a target of the image formation failure in the image forming section 42 (NO in step S113), the image forming failure detecting section 35 uses the image forming section 42 to form a sheet on which the corrected portion is detected as a defective image. Not detected as defective paper. Then, the paper correction unit 36 adjusts the correction amount in step S106 (step S114).

  When the correction location is detected as a target of the image formation failure in the image forming unit 42 (YES in step S113), the image formation failure detection unit 35 applies the image formed by the image formation unit 42 to the sheet in which the correction location is detected as the defective image. A formation failure is detected (step S112). If a defective image that does not match the nonconforming portion of the sheet is detected (NO in step S109), the image forming defect detection unit 35 performs image forming 42 (Step S112).

  Next, it is determined whether or not the detection of the image formation failure by the image forming unit 42 in the processing from step S108 to step S114 is completed for all the sheets (step S115). If the detection of the image formation failure has not been completed for all the sheets (NO in step S115), the processing from step S108 to step S114 is repeated as appropriate.

  When the detection of the image formation failure is completed for all the sheets (YES in step S115), whether each sheet has the image formation failure by the image forming unit 42 detected by the image formation failure detection unit 35 in step S112. Is determined (step S116). If the sheet does not have an image formation defect (NO in step S116), all the sheets are discharged to the tray and the print job ends normally (step S117), and the processing of this flowchart ends. I do. When the sheet has an image formation defect (YES in step S116), the sheet having the image formation defect is discharged to a tray or the like different from the normal output, so that the image formation defect starts from the normal sheet. The paper is separated (step S118), and the processing of this flowchart ends.

  According to the above-described processing, the first image inspection unit 15 detects an unsuitable portion such as dirt or foreign matter on the sheet before image formation, and the second image inspection unit 16 detects a defective image on the sheet after image formation. I do. Then, by removing non-conforming portions before image formation from defective images detected after image formation, non-conforming portions such as dirt or foreign matter on paper before image formation can be detected, and defective image formation can be detected. Therefore, a minor nonconforming portion that does not affect image formation due to the material of the sheet or the like is not detected as an image formation defect after image formation, thereby reducing paper waste due to the nonconforming portion included in the sheet itself. It becomes possible.

  Further, by detecting a nonconforming portion before image formation, the nonconforming portion can be corrected in the image forming apparatus 10. Then, the image forming defect can be detected by eliminating the non-conforming portion due to the correction from the defective image detected after the image formation. Further, the correction amount can be adjusted based on information on the defective image detected after the image formation.

<2. Image Forming System (Second Embodiment)>
Next, a second embodiment of the image forming system and the image inspection method of the present invention will be described.

[Schematic Configuration of Image Forming System]
FIG. 10 shows a schematic configuration diagram of the image forming system of the present embodiment.
The image forming system 200 illustrated in FIG. 10 includes the image forming apparatus 10, the image inspection unit 19, and the post-processing device 18. Note that the configuration of the image forming system 200 is not limited to this, and another device may be connected. For example, a relay device or the like may be provided between the image forming apparatus 10 and another device.

  The image forming system 200 according to the second embodiment includes an image forming apparatus 10, an image inspection unit 19 disposed downstream of the image forming apparatus 10 in the sheet conveyance direction, and an image inspection unit 19 downstream of the image inspection unit 19 in the sheet conveyance direction. And a post-processing device 18 arranged. The image forming system 200 according to the second embodiment is different from the image forming system 100 according to the first embodiment (see FIG. 1) in that the sheet feeding device 17 disposed on the upstream side of the image forming apparatus 10 in the sheet conveyance direction has The configuration is such that one image inspection unit 15 is removed. That is, the image inspection unit 19 is provided only on the downstream side of the image forming unit 13 in the sheet conveyance direction. The same configuration as the image forming system 10 of the above-described first embodiment can be applied to the image forming apparatus 10, the image inspection unit 19, and the post-processing apparatus 18.

  In the image forming system 200, the image inspection unit 19 reads information on the surface of the sheet before image formation and reads information on the surface of the sheet after image formation. That is, the image inspection unit 19 reads information on the surface of the sheet before image formation, detects an unsuitable portion due to dirt or foreign matter caused by a material or the like constituting the sheet, and determines the whiteness of the sheet or the chromaticity of the sheet. To get. Further, even after the image is formed, the information on the surface of the paper is read by the image inspection unit 19 to detect a defective image due to the image formation, and to obtain the whiteness of the paper and the chromaticity of the paper.

  The functional block diagram of the image forming system 200 according to the second embodiment may have the same configuration as the functional block diagram illustrated in FIG. 2 according to the first embodiment. In the image forming system 200 according to the second embodiment, in the functional block diagram shown in FIG. 2, the non-conforming portion detection unit 51 before image formation and the defective image detection unit 52 after image formation of the image detection unit 50 are different from the image inspection unit 19. Be prepared for. Then, the non-conforming pre-image forming portion detecting section 51 acquires information on the surface of the sheet before the image forming, on the downstream side of the image forming section 42 in the sheet conveying direction. Similarly, the post-image formation defective image detection unit 52 obtains information on the surface of the sheet after image formation downstream of the image formation unit in the sheet conveyance direction.

[Flowchart of image inspection method]
Next, an image inspection method in the image forming system 200 according to the second embodiment will be described with reference to a flowchart. 11 and 12 show flowcharts of the image inspection method.

  First, before forming an image, it is determined whether to detect a nonconforming portion such as dirt or foreign matter on a sheet (step S201). For example, as shown in FIG. 13, whether or not to detect a nonconforming portion of a sheet before image formation is determined in an operation screen of an image forming job in which a screen is displayed on the operation display unit 60 of the image forming system 200. A command button 65 for detecting a nonconforming portion of the previous sheet is displayed, and the determination is made based on whether or not the command button 65 is selected.

  When the non-conforming portion of the sheet before image formation is detected (YES in step S201), the image forming section 13 does not form an image on the sheet, and passes the sheet to the image forming section 13 as a blank sheet (blank sheet passing). ) (Step S202). Then, the image inspection unit 19 on the downstream side of the image forming apparatus 10 detects an unsuitable portion such as dirt or foreign matter on the paper from the image data on the surface of the paper before image formation (Step S203). The detection of the nonconforming part in step S203 can be performed by the same method as in step S101 in FIG. 7 of the first embodiment described above.

  Next, in steps S204 to S206, the same processing as steps S102 to S104 in FIG. 7 of the above-described first embodiment is performed. If the detection of the nonconforming portion in step S204 is completed for all the sheets (YES in step S206), the sheet before image formation is discharged from the image inspection unit 19 (step S207). At this time, in the sheet bundle that has been discharged, the sheet for which an unsuitable portion has been detected is discharged from the post-processing device 18 so that the order of the sheets before image formation is not shifted.

  Next, the sheet for which the non-conforming portion has been detected before image formation is stored again in the sheet feeding unit 14 (step S208). Also at this time, the sheets in the sheet bundle are aligned and the non-conforming portion is detected so that the sheet feeding order is the same as that in step S201 to step S206. After the sheets are stored again, the sheet is fed from the sheet feeding unit 14 to the image forming apparatus 10 again (step S209).

  Next, in steps S210 to S220, the same processing as steps S105 to S115 in FIG. 7 of the above-described first embodiment is performed. In the image formation in step S212, for example, as shown in an example in FIG. 14, the discharged sheet is reset on the sheet feeding unit 14, and a screen for instructing the start of the image forming job is displayed on the operation of the image forming system 200. It is displayed on the display unit 60. Then, by causing the user to select the start of the image forming job, the non-conforming portion before the image formation is detected, and the image formation is started on the sheet stored in the sheet feeding unit 14 again.

  If the non-conforming portion of the sheet before image formation is not detected (NO in step S201), an image is formed on the sheet according to the image forming job (step S221). Then, a defective image is detected from the image data on the surface of the sheet after image formation (step S222), and the detected defective image is compared with a nonconforming portion of the sheet before image formation, and the defective image matches the nonconforming portion. It is determined whether to perform (Step S223). The processing from step S221 to step S223 can be performed in the same manner as in step S107 to step S109 in FIG. 7 of the above-described first embodiment.

  Next, in steps S224 to S226, the same processing as steps S116 to S118 in FIG. 7 of the above-described first embodiment is performed, and the processing of this flowchart ends.

  According to the above-described processing, one image inspection unit 19 can detect an unsuitable portion such as dirt or foreign matter on a sheet before image formation and a defective image on a sheet after image formation. For this reason, the detection of an image forming defect by eliminating the non-conforming portions such as dirt or foreign matter on the sheet before the image forming from the non-conforming portions detected before the image forming and the defective images detected after the image forming is performed by one unit. This can be realized by an image forming system 200 including only the image inspection unit 19.

  It should be noted that the present invention is not limited to the configuration described in the above embodiment, and various modifications and changes can be made without departing from the configuration of the present invention.

  Reference Signs List 10 image forming apparatus, 100, 200 image forming system, 11 MFP, 12 automatic document feeder, 13, 42 image forming unit, 14 paper feeder, 15 first image inspection unit, 16 second image inspection unit, 17 sheet feeding device, 18 post-processing device, 19 image inspection unit, 20 control unit, 21 CPU, 22 RAM, 23 ROM, 30 system control unit, 306 motor, 31 paper nonconformity condition storage unit, 32 paper nonconformity determination unit, 33 paper nonconformity information storage unit, 34 discrimination unit, 35 image formation failure detection unit, 36 paper correction unit, 40 engine control unit, 41 paper transport unit, 50 image detection unit, 51 nonconformity part detection unit before image formation, 52 image formation Post-defective image detection unit, 60 operation display unit, 61 paper setting unit, 62 paper mismatch detection condition setting unit, 63, 64, 65 command buttons , 70 Post-processing control unit, 81 paper, 82 Non-conforming location, 83 square, 84 image, 85 defective image

Claims (13)

An image forming unit that forms an image on paper;
An image inspection unit that acquires information on the surface of the sheet before image formation and information on the surface of the sheet after image formation,
A discriminating unit for discriminating an image formation defect in the image formation by excluding information on the surface of the sheet before image formation from information on the surface of the sheet after image formation. As the image inspection unit, a first image inspection unit disposed upstream of the image forming unit in the sheet transport direction, and a second image disposed downstream of the image formation unit in the sheet transport direction. Inspection department
Acquiring information on the surface of the sheet before image formation in the first image inspection unit;
The image forming system according to claim 1, wherein the second image inspection unit acquires information on a surface of the sheet after image formation. The image inspection unit is disposed downstream of the image forming unit in the paper transport direction,
The image inspection unit includes information on the surface of the sheet before image formation that has been passed through the image formation unit without performing image formation, and the sheet after image formation in which the image formation has been performed in the image formation unit. The image forming system according to claim 1, wherein information on the surface of the image forming apparatus is obtained. A storage unit that stores information on the surface of the paper obtained by the image inspection unit,
The image according to any one of claims 1 to 3, wherein the determination unit determines an image formation failure in the image formation from information on the surface of the sheet before and after image formation stored in the storage unit. Forming system. The image forming system according to any one of claims 1 to 4, further comprising: a determination unit configured to determine a nonconforming portion on the surface of the sheet from information on the surface of the sheet before image formation. The condition for determining the nonconforming part includes at least one type of information among the type of the paper, the color gamut of the nonconforming part, and the area of the nonconforming part, and is set for each type of the paper. The image forming system according to claim 5. The image forming system according to claim 5, further comprising: a setting unit configured to set a threshold value for determining the incompatible portion. The image forming system according to claim 6, wherein information on the nonconforming portion is registered as a paper profile for each type of the paper. A sheet correction unit that determines whether the nonconforming portion of the surface of the sheet before image formation is corrected by filling in the image forming unit and sends an instruction to correct the nonconforming portion by filling the image forming unit. The image forming system according to claim 5. The image forming system according to claim 9, further comprising: a setting unit configured to set whether or not a correction portion that corrects the nonconforming portion of the sheet in the image forming unit is excluded from a determination target of the determination unit. The image forming unit is configured to be able to form a white image,
The image inspection unit that acquires information on the surface of the sheet before image formation, acquires whiteness of the sheet,
The paper correction unit compares the whiteness of the paper and the whiteness of a white image formed by the image forming unit by the determination unit, and when the difference in whiteness is within a predetermined range, The image forming system according to claim 9, wherein the correction instruction is issued to an image forming unit. The paper correction unit, when it is determined from the information on the surface of the paper after image formation that the image forming unit corrects the correction amount of the correction portion that has corrected the incompatible portion of the paper, the image forming unit The image forming system according to claim 9, wherein the correction amount is adjusted. In the image inspection section, information on the surface of the sheet before image formation is obtained,
In an image forming unit, an image is formed on the surface of the sheet,
In the image inspection unit, obtain information on the surface of the paper after image formation,
An image inspection method in which a discriminating unit discriminates image formation failure in image formation by excluding information on the surface of the sheet before image formation from information on the surface of the sheet after image formation.

Images