JP7131215B2 - Image forming system and image inspection method - Google Patents

Description

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

2. Description of the Related Art A sheet printed by an image forming apparatus may have stains or foreign substances on its printed surface for various reasons. For paper containing such stains and foreign matter, a method has been proposed in which the stain and foreign matter on the printing surface of the paper is detected by an automatic image inspection unit or the like before image formation is performed, and it is determined whether printing on the printing surface is possible. (See, for example, Patent Document 1).

Japanese Unexamined Patent Application Publication No. 2011-201021

However, due to the materials and the like that make up the paper, the paper contains unsuitable portions such as slight stains and foreign matter that do not affect images, characters, and the like printed on the paper surface. For this reason, if the detection accuracy of the image inspection unit is high, even minor non-conforming portions that do not affect printed images, characters, etc. contained in the paper will be detected as defects in the paper.

In the method described in Japanese Patent Application Laid-Open No. 2002-200012, the stain on the printing surface of the paper is detected. However, if the detection accuracy of the image inspection unit is high, the nonconforming portion included in the paper itself is also detected as stain. For this reason, even paper that does not affect the printing of images, characters, etc., is discarded without being printed, resulting in wasted paper.

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

The image forming system of 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 image formation and information on the surface of the sheet after image formation, and an image forming unit. a determination unit that determines an 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.

In the image inspection method of the present invention, the image inspection section acquires information on the surface of the sheet before image formation, the image formation section forms an image on the surface of the sheet, and the image inspection section acquires information on the sheet surface after image formation. Information on the surface of the paper is acquired, and the information on the surface of the paper before image formation is excluded from the information on the surface of the paper after image formation in the determination unit to determine an image formation defect in 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 caused by non-conforming portions included in the paper itself.

1 is a diagram showing a schematic configuration of an image forming system according to a first embodiment; FIG. 3 is a functional block diagram of a controller of the image forming system of the first embodiment; FIG. It is a table|surface which shows the judgment conditions of a nonconformity location. FIG. 4 is a diagram showing an example of an image forming job operation screen displayed on the operation display section of the image forming system; FIG. 5 is a diagram showing an example of a paper profile screen displayed on the operation display section of the image forming system; FIG. 10 is a diagram showing an example of a screen for changing paper profile settings displayed on the operation display unit of the image forming system; It is a figure which shows the flowchart of the image inspection method of 1st Embodiment. FIG. 10 is a diagram showing nonconforming portions of a sheet by XY coordinates; FIG. 10 is a diagram showing a nonconforming portion of a sheet and a defective image by XY coordinates; FIG. 10 is a diagram showing a schematic configuration of an image forming system according to a second embodiment; FIG. 11 is a diagram showing a flowchart of an image inspection method according to the second embodiment; FIG. 11 is a diagram showing a flowchart of an image inspection method according to the second embodiment; FIG. 4 is a diagram showing an example of an image forming job operation screen displayed on the operation display section of the image forming system; FIG. 4 is a diagram showing an example of an image forming job operation screen displayed on the operation display section of the image forming system;

Examples of embodiments for carrying out the present invention will be described below, but the present invention is not limited to the following examples.
The description will be given 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)>
An image forming system and an image inspection method according to a first embodiment of the present invention will be described below.

[Schematic Configuration of Image Forming System]
FIG. 1 shows a schematic configuration diagram of an image forming system according to the present embodiment.
Image forming system 100 shown in FIG. Note that the configuration of the image forming system 100 is not limited to this, and other devices 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 upstream of the image forming apparatus 10 in the paper conveying direction, and has a plurality of paper feeding trays in which paper (recording media) on which images are to be formed in the image forming apparatus 10 are accommodated. . When an image forming job is selected, the paper feeding device 17 takes out the paper from the paper feeding tray using a pick-up roller, a separating roller, or the like. Then, the taken-out sheets are conveyed one by one by a conveying roller or the like to the image forming apparatus 10 via the first image inspection section 15 .

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 paper for image formation to the MFP 11. be done. MFP 11 includes automatic document feeder 12 , image forming unit 13 , and operation display unit 60 .

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

The image forming section 13 includes a charging section, a photoreceptor, an exposure section, a developing section, an intermediate transfer belt, a fixing section, and the like. In the image forming unit 13, after the charging unit charges the photoreceptor, the exposure unit irradiates the photoreceptor with laser light to form an electrostatic latent image on the photoreceptor. Then, the developing section develops the electrostatic latent image on the surface of the photosensitive member to form a toner image. After that, the toner image is transferred to the intermediate transfer belt, and the toner image transferred to the intermediate transfer belt is transferred to the surface of the paper being conveyed at a predetermined timing. The paper with the transferred image is conveyed to the fixing section. The fixing unit includes, for example, a pressure roller, a fixing roller, a belt, and the like, and heats and presses the paper on which the toner image is formed, thereby fixing the toner image to the paper.

The paper feed unit 14 includes a plurality of paper storage units capable of storing papers of different sizes and types. The paper feeding unit 14 takes out the paper from the corresponding paper storage unit based on the 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 the start of a job such as image forming processing. The operation display unit 60 serves as both an operation unit and a display unit. The operation display unit 60 is configured by a touch panel including an LCD (Liquid Crystal Display) or the like, and is capable of being operated by a user and displaying information. It should be noted that it is also possible to configure the operation unit with a mouse, a tablet, or the like, and to configure it 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 arranged between the paper feeding device 17 and the image forming device 10 . The second image inspection section 16 is arranged between the image forming apparatus 10 and the post-processing apparatus 18 .
The first image inspection unit 15 and the second image inspection unit 16 are provided with line sensors 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 the image of the front surface (at least one of the top surface and the back surface) of the conveyed paper, and read the result (read image data). get. Then, the image quality is automatically inspected based on the information on the surface of the paper that has been read.

The post-processing device 18 performs post-processing on the paper received from the second image inspection unit 16 according to instructions from the MFP 11 . This post-processing includes, for example, a process of aligning the sheets into a bundle, a process of binding the bundle with staples, and the like. Post-processing device 18 also includes a plurality of output trays. For example, it has a tray for ejecting normally output paper without image formation failure and a sub-tray for ejecting paper excluded due to image formation failure.

In the above description, an electrophotographic image forming apparatus is exemplified as the image forming apparatus 10, 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 Section of Image Forming System]
FIG. 2 shows a functional block diagram of the control section of the image forming system 100 described above.
The image forming system 100 described above has a control section 20 for controlling the entire image forming system 100 . Furthermore, an engine control unit 40 and a system control unit 30 are provided so as to be mutually communicable with a control unit 20 that controls the entire image forming system 100 , and control each component of the image forming system 100 according to instructions from the control unit 20 . , a post-processing control unit 70 , an image detection unit 50 , and an operation display unit 60 .

A 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 section 40, the system control section 30, the post-processing control section 70, the image detection section 50, the operation display section 60, etc. according to programs 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 and printing conditions accepted by the operation display unit 60 . The ROM 23 includes a non-writable semiconductor memory device that stores information such as firmware, and a rewritable semiconductor memory device such as an EEPROM that provides the CPU 21 with a storage area for environment variables and the like, an HDD, and the like.

The engine control unit 40 controls a sheet conveying unit 41 that conveys sheets throughout the image forming system. Further, the engine control section 40 controls the conveyance of paper in the image forming section 42 for image formation. The engine control unit 40 is controlled by the CPU 21 of the control unit 20 executing dedicated firmware. The engine control unit 40 controls the sheet conveying operation in 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. A motor drive circuit drives each motor according to instructions from the engine control unit 40 to move the paper from the paper feed unit to the image forming unit 42 and move the paper within the image forming unit 42 .

The image detection unit 50 includes a pre-image formation nonconforming part detection unit 51 and a post-image formation defective image detection unit 52 . The image data acquired by the image detection unit 50 , the candidates for the non-conforming parts of the paper detected, and the defective image are transferred to the RAM 22 , ROM 23 , etc. of the control unit 20 . In the image detection unit 50, conventionally known methods can be applied to the method of reading the image and the method of creating the read image data.

The pre-image formation nonconformity detection unit 51 optically reads information on the surface of the paper before image formation supplied to the image forming apparatus 10 to obtain image data. Further, nonconforming portions such as stains on the paper and foreign substances are detected from the read image data. For example, the pre-image formation mismatch detection unit 51 compares pre-registered paper information (paper profile) with the image data acquired by the pre-image formation mismatch detection unit 51 to acquire a difference. Then, the difference is detected as a candidate for the 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 to obtain image data. Further, defective images are detected from the read image data. For example, the information of the reference image used for image formation is compared with the information of the surface of the sheet after image formation acquired by the defective image detection unit 52 after image formation, and the difference is acquired. Then, according to the obtained difference, a defective image is detected from the difference level, shape, and the like.

The information on the surface of the paper acquired by the pre-image formation nonconformity detection unit 51 and the post-image formation defective image detection unit 52 includes, for example, nonconformity locations such as stains and foreign substances caused by the materials constituting the paper, , image formation defects such as white spots, streaks, stains, and blurring due to image formation. In addition, the pre-image formation nonconformity detection unit 51 and the post-image formation defective image detection unit 52 can also obtain the whiteness and chromaticity of the paper as the information on the surface of the paper. By acquiring the whiteness and chromaticity as information on the surface of the paper before image formation, it is possible to identify unsuitable areas such as stains and foreign matter caused by the materials that make up the paper, and then reproduce images of the same color in the image forming unit. It provides the paper correction unit 36 with information for determining whether to form the image into a square and correct it by filling it. In addition, by obtaining the whiteness and chromaticity of the surface of the paper after correction (after image formation), the whiteness and chromaticity of the surface of the paper can be compared with the whiteness and chromaticity of the corrected area. , provides the paper correction unit 36 with information for judging whether the correction amount is appropriate.

When the image forming system 100 includes the first image inspection unit 15 arranged on the upstream side of the image forming apparatus 10 and the second image inspection unit 16 arranged on the downstream side of the image forming apparatus 10 , a pre-image formation nonconforming part detection unit 51 is provided in the first image inspection unit 15 , and a post-image formation defective image detection unit 52 is provided in the second image inspection unit 16 . Then, the pre-image formation nonconformity detection section 51 acquires information on the surface of the sheet before image formation on the upstream side of the image formation section 42 in the sheet conveying direction. Further, the post-image formation defective image detection section 52 acquires information on the surface of the sheet after image formation on the downstream side of the image formation section 42 in the sheet conveying direction.

Note that when the image forming system 100 has an image inspection section only on the downstream side of the image forming apparatus 10, the pre-image formation nonconforming portion detection section 51 and the post-image formation defective image detection section 52 are the same image inspection section. may be provided in In this case, the information on the surface of the sheet before image formation and the information on the surface of the sheet after image formation are acquired by the image inspection section downstream of the image forming section 42 in the sheet conveying direction.

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

The paper unsuitable condition storage unit 31 stores conditions for determining unsuitable paper from the information on the surface of the paper read by the image detection unit 50 . Conditions for judging nonconformance (judgment conditions) include, for example, the threshold value of the color gamut that is judged to be nonconforming parts such as dirt and foreign matter caused by the materials that make up the paper, and the threshold value of the area that is judged to be nonconforming. and at least one type of information among In addition, the paper incompatibility condition storage unit 31 stores paper types, and stores determination conditions for each paper type.

As the judgment conditions, for example, as shown in FIG. 3, a threshold value for the area of dirt or foreign matter, etc., and a threshold value for the concentration of dirt or foreign matter, etc., which are judged to be non-conforming locations for each criterion, are set as the judgment conditions, and these thresholds are set. Set standards such as “loose”, “standard”, and “strict”. Then, by selecting the set criteria, it is determined whether the non-conforming portion is due to the material of the paper or the non-conforming portion due to something else. For example, non-conforming portions due to factors other than paper materials include adhesion of toner or ink. Then, the type of nonconformity that is likely to occur according to the type of paper is registered (stored), and other nonconformity is determined as nonconformity due to other than the material of the paper. It should be noted that these determination conditions are only examples, and the types of setting criteria and the types and values of thresholds for each setting criteria can be set as appropriate.

In addition, when a user or the like sets a determination condition from the operation display unit 60, the paper incompatibility condition storage unit 31 stores the determination condition set by the user or the like. The paper incompatibility condition storage unit 31 may register and store a judgment condition set by a user or the like as a paper profile judgment condition for each paper type.

The sheet unsuitable part determination unit 32 determines that the candidates of the unsuitable parts detected by the unsuitable part detection unit 51 before image formation correspond to the sheet unsuitability based on the unsuitable judgment conditions stored in the sheet unsuitable condition storage unit 31. or judge. Then, the information on the determined nonconforming portion is sent to the paper nonconformity information storage unit 33 . The paper non-conforming part judgment unit 32 judges the position and the size of the non-conforming part represented by XY coordinates with reference to the corner of the paper as the information of the non-conforming part. It is sent to the incompatibility information storage unit 33 .

The paper nonconformity information storage unit 33 stores the information on the surface of the paper before image formation acquired by the pre-image formation nonconformity part detection unit 51 . Further, the paper nonconformity information storage unit 33 stores the information of the nonconformity portion determined by the paper nonconformity region determination unit 32 as the 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 of the nonconformity portion determined by the paper nonconformity region determination 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 image formation detected by the defective image detection unit 52 after image formation with the information of the unsuitable part of the sheet before image formation stored in the sheet unsuitable information storage unit 33. . In this way, an image formation defect in image formation and an unsuitable portion of the sheet before image formation are discriminated. Then, the determined result is sent to the image formation failure detection unit 35 .

The image formation defect detection unit 35 determines whether or not there is a defective image on the sheet based on the determination result of the determination unit 34, and detects the sheet having the image formation defect. Then, it outputs to the control section 20 that an image forming failure has occurred in the image forming section. The control unit 20 stops the image forming operation based on the information from the image formation failure detection unit 35 . Alternatively, the paper having the defective image may be discharged to a paper discharge destination different from the normal paper discharge destination without stopping the image forming operation.

The paper correction unit 36 adjusts the image forming unit 42 based on the information on the whiteness and chromaticity of the paper acquired by the pre-image formation nonconformity detection unit 51 and the information on the nonconformance portion determined by the paper nonconformity determination unit 32. , it is determined whether or not the nonconforming portion on the surface of the paper before image formation can be corrected. For example, the paper correction unit 36 compares the whiteness and chromaticity of the paper acquired by the pre-image formation nonconformity detection unit 51 with the whiteness of the white image and the chromaticity of the color image formed by the image forming unit 42 . Then, when the whiteness difference and the chromaticity difference are within a predetermined range, it is determined that the nonconforming portion can be corrected.

When the paper correction unit 36 determines that the nonconforming portion of the paper is to be corrected, the paper correction unit 36 sends to the image forming unit 42 an instruction to draw an image to fill in the nonconforming portion. Alternatively, the operation display unit 60 notifies the user of the nonconforming portion of the paper and that the nonconforming portion can be corrected, and prompts the user 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 identifies the color of the paper and the non-conforming parts, for example, from the information on the whiteness and chromaticity of the paper and the information on the non-conforming parts. . Then, the image forming unit 42 draws an image of the same color as the paper at the position of the nonconforming portion and fills the nonconforming portion with the same color as the paper, thereby correcting the nonconforming portion of the paper.

Further, the paper correction unit 36 calculates the whiteness and chromaticity of the surface of the paper and the whiteness of the correction part from the corrected (after image formation) surface information of the paper acquired by the post-image formation defective image detection unit 52 . and chromaticity to determine whether the amount of correction is appropriate. When the paper correction unit 36 determines that the correction amount is not appropriate, it instructs the image forming unit 42 to adjust the correction amount so that the correction amount becomes optimum. The image forming unit 42 corrects the paper using the correction amount adjusted for subsequent paper.

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

After selecting the paper setting command button 63, a paper profile screen is displayed as shown in FIG. As a paper profile, information items such as the paper profile name, paper type, size, etc., as well as the threshold value of the color gamut that is determined as a non-conforming part such as dirt or foreign matter caused by the material constituting the paper, and non-conformity information such as a threshold value for the area determined as , whether or not the unsuitable portion can be corrected by the paper correction unit 36, and whether or not the corrected unsuitable portion is detected as an image formation defect. The paper profile screen also displays command buttons 64 for changing paper profile settings.

After selecting the command button 64 for changing the setting of the paper profile, as shown in FIG. 6, for each paper judgment condition (area, density in FIG. Displays command buttons for selecting criteria such as "Strict". In addition, command buttons are displayed for selecting whether or not to correct the nonconforming portion in the paper correction unit 36, whether to detect the corrected nonconforming portion as an image formation defect, and the like.

The paper nonconformity detection condition setting unit 62 displays a screen for inputting conditions on the operation display unit 60 so that the user can set conditions for judging nonconformity, and accepts the conditions set by the user. In addition, the paper nonconformity detection condition setting unit 62 displays a screen on the operation display unit 60 for the user to select whether the corrected nonconforming portion is included in the judgment of image formation failure in the judgment unit 34, and accepts the user's instruction. good too.
The post-processing control section 70 performs post-processing on the sheet received via the second image inspection section 16 in accordance with an instruction from the control section 20 . This post-processing includes, for example, a process of aligning the sheets into a bundle, a process of binding the bundle with staples, and the like.

[Flow chart of image inspection method]
Next, the image inspection method described above will be described according to a flowchart. A flow chart of the image inspection method is shown in FIG.

First, paper is fed from the paper feeding device 17 or the paper feeding unit 14 to the first image inspection unit 15, and unsuitable portions such as stains and foreign matter on the paper are detected from the image data of the surface of the paper before image formation. (Step S101). In the detection of nonconformity of the paper, the nonconformity detection section 51 before image formation optically reads the information on the surface of the paper before image formation to acquire image data, and from the image data, nonconformity such as dirt or foreign matter on the paper is detected. Candidates for locations are detected. Then, the paper non-conforming part determination unit 32 compares the non-conforming part candidates detected by the non-conforming part detection unit 51 before image formation with the conditions (judgment conditions) for judging non-conformity held in the paper non-conformity condition storage unit 31. , determine whether it corresponds to nonconformity of the paper, and detect the nonconformity part of the paper.

Next, it is determined whether or not a nonconforming portion such as dirt or a foreign substance is detected on the paper (step S102). , is stored in the paper nonconformity information storage unit 33 (step S103). For example, as shown in FIG. 8, the non-conforming portion 82 detected on the surface of the paper 81 is given XY coordinates with reference to the corner 83 of the paper. 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. . Based on these XY coordinates, the non-conforming portion 82 is assigned a position in the X coordinate direction, a length in the X coordinate direction, a position in the Y coordinate direction, and a length in the Y coordinate direction. Then, the position and size of the non-conforming portion 82 given by the XY coordinates are sent to the paper non-conforming information storage section 33 as non-conforming portion information.

Further, if no non-conforming portion is detected (NO in step S102), or after the information on the non-conforming portion is stored in the paper non-conforming information storage section 33 in step S103, for all sheets used for image formation, step S102 (step S104). If the detection of nonconforming portions in step S102 has not been completed for all sheets (NO in step S104), the processing of steps S102 and S103 is repeated until the detection is completed for all sheets.

When the detection of the nonconforming portion in step S102 is completed for all sheets (YES in step S104), it is determined whether the paper correction unit 36 should correct the detected nonconforming portion of the sheet (step S105). ). Execution of correction is determined by determining whether or not the non-conforming portion can be corrected in the paper correction unit 36, and if it can be corrected, depending on whether there is an instruction from the user or the like. If correction is to be performed (YES in step S105), the paper correction unit 36 instructs the image forming unit 42 to draw an image of the same color as the paper at the position of the nonconforming portion and fill it in, thereby correcting the nonconforming portion of the paper. (step S106).

After correcting the non-conforming portion in step S106, or when correction is not performed (NO in step S105), the image forming section 42 forms an image on the paper according to the image forming job (step S107).

Next, a defective image is detected from the image data of the surface of the sheet after image formation (step S108). A defective image is detected by optically reading the sheet on which an image has been formed by the defective image detection section 52 after image formation and detecting a defective image from the image data. Then, the defective image detected in step S108 is compared with the unsuitable portion of the sheet before image formation, and it is determined whether the defective image matches the unsuitable portion (step S109).

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

Then, in the discriminating unit 34, information such as the position and size of the defective image 85 acquired in step S108 and information such as the position and size of the nonconforming part 82 stored in the paper nonconformity information storage unit 33 in step S103 are combined. By the comparison, the defective image is determined as an image formation defect in image formation and an unsuitable portion of the sheet before image formation. Then, defective images that match the nonconforming portion of the paper are excluded, and only defective images resulting from image formation are detected. In this way, it is determined whether or not all the detected defective images match the nonconforming portion of the paper.

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

If the corrected portion is not detected as a target of image formation failure in the image forming unit 42 (NO in step S113), the image forming unit 42 performs image formation on the sheet on which the image formation failure detection unit 35 detects the corrected portion 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 corrected portion is detected as a target of image formation failure in the image forming section 42 (YES in step S113), the image formation failure detecting portion 35 detects the image formed by the image forming portion 42 for the sheet on which the corrected portion is detected as a defective image. A formation defect is detected (step S112). Further, when a defective image that does not match the nonconforming portion of the paper is detected (NO in step S109), the defective image formation detection unit 35 detects image formation on 42 copies of the paper on which the defective image that does not match the nonconforming portion is formed. An image formation failure due to is detected (step S112).

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

If image formation defects have been detected for all sheets (YES in step S115), each sheet has an image formation defect detected by the image formation defect detection section 35 in step S112. is determined (step S116). Then, if the paper does not have an image formation defect (NO in step S116), all the paper is discharged to the tray, the print job ends normally (step S117), and the processing of this flowchart ends. do. If the paper has defective image formation (YES in step S116), the paper having defective image formation is ejected to a tray or the like different from the one used for normal output. The paper is separated (step S118), and the processing of this flow chart ends.

According to the above-described processing, the first image inspection unit 15 detects unsuitable portions such as stains and foreign matter on the paper before image formation, and the second image inspection unit 16 detects defective images on the paper after image formation. do. By excluding unsuitable portions before image formation from the defective image detected after image formation, unsuitable portions such as stains and foreign matter on the paper before image formation can be eliminated, and image formation defects can be detected. Therefore, minor nonconformities that do not affect image formation due to paper materials, etc., are not detected as image formation defects after image formation, thus reducing paper wastage caused by nonconformity contained in the paper itself. becomes possible.

Further, by detecting the unsuitable portion before image formation, the image forming apparatus 10 can correct the unsuitable portion. Then, it is possible to detect an image formation defect by excluding non-conforming portions due to correction from a defective image detected after image formation. Further, it is also possible to adjust the amount of correction based on the information of the defective image detected after 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 this embodiment.
An image forming system 200 shown in FIG. 10 includes an image forming apparatus 10, an image inspection section 19, and a post-processing apparatus . Note that the configuration of the image forming system 200 is not limited to this, and other devices 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 of the second embodiment includes an image forming apparatus 10, an image inspection section 19 arranged downstream of the image forming apparatus 10 in the sheet conveying direction, and an image inspection section 19 arranged downstream of the image inspecting section 19 in the sheet conveying direction. and a post-processing device 18 disposed thereon. The image forming system 200 of the second embodiment has a paper feeding device 17 and a paper feeding device 17 arranged upstream in the paper conveying direction of the image forming apparatus 10 from the image forming system 100 of the first embodiment (see FIG. 1). 1 image inspection unit 15 is removed. That is, the image inspection section 19 is provided only on the downstream side of the image forming section 13 in the sheet conveying direction. The image forming apparatus 10, the image inspection unit 19, and the post-processing device 18 can have the same configuration as the image forming system 10 of the first embodiment described above.

In the image forming system 200, the image inspection unit 19 reads the information on the surface of the paper before image formation and the information on the surface of the paper after image formation. That is, the image inspection unit 19 reads information on the surface of the paper before image formation, detects non-conforming portions due to stains and foreign matter caused by the materials constituting the paper, and determines the whiteness of the paper and the chromaticity of the paper. to get Further, after image formation, the image inspection unit 19 reads information on the surface of the paper, detects defective images due to image formation, and acquires the whiteness and chromaticity of the paper.

Note that the functional block diagram of the image forming system 200 of the second embodiment can have the same configuration as the functional block diagram shown in FIG. 2 of the first embodiment. In the functional block diagram shown in FIG. 2, the image forming system 200 of the second embodiment includes a pre-image formation nonconformity detection section 51 and a post-image formation defective image detection section 52 of the image detection section 50 . be prepared for Then, the pre-image formation nonconformity detection section 51 acquires information on the surface of the sheet before image formation on the downstream side of the image formation section 42 in the sheet conveying direction. Similarly, the post-image formation defective image detection section 52 acquires information on the surface of the sheet after image formation on the downstream side in the sheet conveying direction of the image formation section.

[Flow chart of image inspection method]
Next, an image inspection method in the image forming system 200 of the second embodiment will be described according to a flowchart. A flow chart of the image inspection method is shown in FIGS. 11 and 12. FIG.

First, before image formation, it is determined whether or not to detect unsuitable portions such as stains or foreign matter on the paper (step S201). For example, as shown in FIG. A command button 65 for detecting nonconforming portions of the previous sheet is displayed, and determination is made based on whether or not this command button 65 is selected.

In the case of detecting a nonconforming portion of the paper before image formation (YES in step S201), the image forming unit 13 does not perform image formation on the paper, and the paper passes through the image forming unit 13 as it is (blank paper passing). ) (step S202). Then, the image inspection unit 19 on the downstream side of the image forming apparatus 10 detects unsuitable portions such as stains and foreign matter on the paper from the image data of the surface of the paper before image formation (step S203). The detection of non-conforming portions in step S203 can be performed by the same method as in step S101 in FIG. 7 of the above-described first embodiment.

Next, in steps S204 to S206, the same processing as in steps S102 to S104 in FIG. 7 of the first embodiment is performed. When the detection of nonconforming portions in step S204 is completed for all 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 discharged sheet bundle, the sheet for which the non-conforming portion has been detected is discharged from the post-processing device 18 so that the order of the sheets before image formation is not deviated.

Next, the sheet on which non-conforming portions have been detected before image formation is stored again in the paper feed section 14 (step S208). Also at this time, the order of the sheets in the sheet bundle is arranged so that the sheet feeding order is the same as that in steps S201 to S206, and the sheets for which the inconsistent portions have been detected are accommodated in the sheet feeding section 14 again. After re-storing the paper, paper is fed again from the paper feeding unit 14 to the image forming apparatus 10 (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. Displayed on the display unit 60 . Then, by selecting the start of the image forming job, the unsuitable portion before the image formation is detected, and the image formation is started on the sheets accommodated in the paper feed section 14 again.

Further, if the nonconforming portion of the sheet before image formation is not detected (NO in step S201), image formation is performed on the sheet according to the image formation job (step S221). Then, a defective image is detected from the image data of the surface of the sheet after image formation (step S222), the detected defective image is compared with the unsuitable portion of the sheet before image formation, and the defective image matches the unsuitable portion. It is determined whether to do so (step S223). The processing from step S221 to step S223 can be performed in the same manner as from 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, the single image inspection unit 19 can detect unsuitable portions such as stains and foreign matter on the paper before image formation and detect defective images on the paper after image formation. For this reason, the detection of defective image formation by excluding unsuitable portions such as stains and foreign matter on the paper before image formation is performed on a single machine from the unqualified portions detected before image formation and the defective images detected after image formation. It can be realized by the image forming system 200 having only the image inspection unit 19 .

The present invention is not limited to the configurations described in the above embodiments, and various modifications and changes are possible without departing from the configuration of the present invention.

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 paper 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 unsuitable condition storage unit, 32 paper unsuitable part determination unit, 33 paper nonconformity information storage unit 34 determination unit 35 image formation failure detection unit 36 paper correction unit 40 engine control unit 41 paper conveyance unit 50 image detection unit 51 nonconformity location detection unit before image formation 52 image formation Post-defective image detection unit 60 Operation display unit 61 Paper setting unit 62 Paper non-conforming detection condition setting unit 63, 64, 65 Command buttons 70 Post-processing control unit 81 Paper 82 Non-conforming part 83 Corner 84 Image , 85 defective images

Claims (15)

an image forming unit that forms an image on paper;
Information on the surface of the sheet before image formation, which is arranged downstream of the image forming section in the sheet conveying direction and passed through the image forming section without image formation, and image formation in the image forming section. an image inspection unit that acquires information on the surface of the paper after image formation on which the
an image forming system, comprising: a discrimination unit configured to discriminate an image formation failure 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. A storage unit for storing information on the surface of the paper acquired by the image inspection unit,
The discrimination section discriminates an image formation failure in the image formation from the information on the surface of the sheet before and after the image formation stored in the storage section.
The imaging system of claim 1 . an image forming unit that forms an image on paper;
an image inspection unit that acquires information on the surface of the paper before image formation and information on the surface of the paper after image formation;
a judgment unit that judges a nonconforming portion on the surface of the paper from information on the surface of the paper before image formation;
an image forming system, comprising: a discrimination unit configured to discriminate an image formation failure 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 units, a first image inspection unit arranged upstream in the sheet conveying direction of the image forming unit, and a second image inspecting unit arranged downstream of the image forming unit in the sheet conveying direction. Equipped with an inspection department,
Acquiring information on the surface of the paper before image formation in the first image inspection unit;
Acquiring information on the surface of the paper after image formation in the second image inspection unit
4. The image forming system according to claim 3 . The image inspection unit is arranged downstream of the image forming unit in the paper conveying direction,
The image inspection unit provides information on the surface of the sheet passed through the image forming unit without image formation and information on the surface of the sheet before image formation and the sheet on which image formation has been performed in the image forming unit. to get information on the surface of the
4. The image forming system according to claim 3 . A storage unit for storing information on the surface of the paper acquired by the image inspection unit,
The discrimination section discriminates an image formation failure in the image formation from the information on the surface of the sheet before and after the image formation stored in the storage section.
The image forming system according to any one of claims 3 to 5 . The condition for determining the non-conforming portion includes information on at least one of the type of paper, the color gamut of the non-conforming portion, and the area of the non-conforming portion, and is set for each type of paper.
The image forming system according to any one of claims 3 to 6 . A setting unit capable of setting a threshold value for determining the nonconforming part is provided.
The image forming system according to any one of claims 3 to 7 . Information on the nonconforming portion is registered as a paper profile for each paper type.
The image forming system according to claim 7 . a paper correction unit that determines whether the unsuitable portion on the surface of the paper before image formation is to be corrected by filling in the image forming unit, and sends an instruction for correcting the unsuitable portion by filling to the image forming unit; Prepare
The image forming system according to any one of claims 3 to 9 . A setting unit for setting whether or not to exclude a corrected portion of the sheet in which the nonconforming portion of the sheet is corrected in the image forming unit from a determination target of the determination unit.
11. The imaging system of claim 10 . The image forming unit is configured to be capable of forming a white image,
The image inspection unit that acquires information on the surface of the paper before image formation acquires the degree of whiteness of the paper,
The paper correction unit compares the whiteness of the paper with the whiteness of the white image formed by the image forming unit, and if the difference in whiteness is within a predetermined range, the Instructing the image forming unit to perform the correction
11. The imaging system of claim 10 . When the paper correction unit determines that a correction amount of a corrected portion obtained by correcting the nonconforming portion of the paper in the image forming unit is not appropriate from information on the surface of the paper after image formation, the image forming unit Adjust the amount of correction in
11. The imaging system of claim 10 . acquiring information on the surface of a sheet of paper passed through the image forming unit without undergoing image formation, in an image inspection unit arranged downstream of the image forming unit in the sheet conveying direction ;
forming an image on the surface of the paper in the image forming unit;
obtaining, in the image inspection unit, information on the surface of the sheet after image formation has been performed in the image forming unit ;
An image inspection method in which, in a determination unit, information about the surface of the paper before image formation is excluded from information about the surface of the paper after image formation, and image formation defects in image formation are determined. In the image inspection department, information on the surface of the paper before image formation is acquired,
forming an image on the surface of the paper in an image forming unit;
acquiring information on the surface of the paper after image formation in an image inspection unit;
determining a nonconforming portion on the surface of the paper from the information on the surface of the paper before image formation in the determination unit;
An image inspection method in which, in a determination unit, information about the surface of the paper before image formation is excluded from information about the surface of the paper after image formation, and image formation defects in image formation are determined.

Images