JP6066058B2 - Image forming apparatus, image forming system, and image forming method - Google Patents

Description

  The present invention relates to an image forming apparatus that forms an image on a sheet, an image forming system including the image forming apparatus, and an image forming method.

In an image forming apparatus such as a copying machine, a printer, or a multifunction machine, a toner image is formed on a photoreceptor provided in an image forming unit based on image data obtained by reading from a document reading device, and the toner Printing is performed by transferring an image onto a sheet fed from a tray and further fixing the image. Further, the sheet on which the image is formed on the front side can be reversed and conveyed by a reversing conveyance unit if desired, and can be recirculated to the sheet conveyance unit, whereby image formation and fixing can be performed on the back side.
The fixing device passes the paper through a fixing roller, a pressure belt, etc., and fixes the toner image on the paper by heating, pressing, etc., but the paper as it is formed is conveyed to the fixing device. Therefore, over time, the fixing member such as the fixing roller and the pressure belt may be soiled with toner, or the toner may adhere to the fixing member due to a paper jam. When a new sheet is passed through the fixing device, the toner on the fixing member adheres to the sheet and becomes dirty.
In addition, image formation position shift may occur in front and back printing, and the image density may change over time. Depending on the degree, these stains, misregistration, image density changes, and the like may cause the image quality to be deteriorated. For this reason, an image forming apparatus that automatically detects the occurrence of abnormality and does not generate defective products has been proposed.

For example, in the image forming apparatus disclosed in Patent Document 1, after detecting an abnormality in an image on a sheet by a sensor, the abnormal page is discharged to another tray, a reprint operation is performed, and if the same abnormality is detected again, the printing process is stopped. The process to make it.
Further, the image forming apparatus disclosed in Patent Document 2 performs a process of stopping a printing process when an abnormality of an external factor such as a lack of toner or ink that cannot be recovered is detected in document printing consisting of a plurality of pages.

JP 2004-20650 A JP 2011-197940 A

  However, in the conventional image forming apparatus described above, when an abnormality is detected, the paper remaining in the machine is simply discharged to another discharge tray or printing is stopped. Cannot be used effectively, and there is a problem that wasteful paper is generated.

  The present invention has been made against the background of the above circumstances, and provides an image forming apparatus, an image forming system, and an image forming method that enable effective use of paper remaining in the apparatus when an image abnormality is detected. The purpose is to provide.

That is, among the image forming apparatuses of the present invention, the first aspect of the present invention includes a paper transport unit for transporting paper,
An image forming unit that forms an image on the sheet, an image detecting unit that detects an image on the sheet conveyed by the sheet conveying unit on a downstream side of the image forming unit, and an image detected by the image detecting unit and a control unit for acquiring information, wherein the control unit, the image based on information of the image it is determined whether normal, the image is rather normal, if it is determined that there is image abnormality, the transport state The residual paper remaining in the machine is transported by the paper transport unit, and an original image or an image pattern is formed by the image forming unit in an image non-formation region for at least a part of the residual paper , and the image on the residual paper To detect the image on the sheet by executing control to detect the image, and determine whether the image is normal based on the information on the image, and the image is not normal and abnormal. Judge that there is If it is the same as the cause of the previous image abnormality, if it is the same as the cause of the previous image abnormality, it is possible to shift to the print stop procedure. In this case, the process is not shifted to the printing stop procedure .

  In the image forming apparatus according to a second aspect of the present invention, in the first aspect of the present invention, the image detection unit is disposed at a position for detecting an image on a sheet that has passed through a fixing device, and the control unit Based on the image information, it is determined whether at least one of the front / back position shift, color position shift, character density, image density, and toner stain of the image is normal.

The image forming apparatus according to a third aspect of the present invention is characterized in that, in the first or second aspect of the present invention, the image non-formed area is a blank surface of a blank sheet.

An image forming apparatus according to a fourth aspect of the present invention has a storage unit for storing data in any one of the first to third aspects of the present invention,
When the control unit determines that the image is not normal according to the determination, the control unit stores the page information of the sheet related to the image determined to be not normal and the factor that is not normal in a readable manner in the storage unit. And

In the image forming apparatus of the fifth aspect of the present invention, in any of the first to fourth aspects of the present invention, when the control unit determines that the image is not normal based on the information of the image, it determines that the image is not normal. It has a function of reprinting at least a page of other paper remaining in the machine in a transported state from the page of the paper that has been printed.

In the image forming apparatus according to a sixth aspect of the present invention, in the fifth aspect of the present invention, the control unit detects an image on the reprinted paper with the image detection unit, acquires image information, and It is characterized in that it is determined whether the image is normal based on information.

An image forming apparatus according to a seventh aspect of the present invention has a storage unit for storing data in any of the first to sixth aspects of the present invention, and the storage unit is determined to be not normal in the previous print operation. The page information of the paper related to the image and the abnormal factor are stored so as to be readable, and the control unit is the same page as the page in which the image is determined to be abnormal in the previous print operation in the current print operation. If the image is not normal and each of the abnormal factors on the corresponding page is the same, if the number of abnormal images for each factor exceeds the threshold, the job is stopped without continuing the current printing operation. Features.

The image forming apparatus according to an eighth aspect of the present invention is the image forming apparatus according to any one of the first to seventh aspects of the present invention, wherein the controller determines that the image is normal by the determination between pages that are continuously printed in different printing operations. In the case where there are a plurality of pages having the same cause of abnormality , the job is stopped without continuing the reprint operation when the number of image abnormalities due to the cause exceeds the threshold.

The image forming apparatus of the ninth aspect of the present invention is characterized in that, in the first to eighth aspects of the present invention, the control unit manages one or more of the following categories as an abnormal factor.
-Front / back position deviation-Color position deviation (Y / M / C / K for each color)
・ Abnormal density (for each color Y / M / C / K)
-Toner stain (for each color Y / M / C / K)

10th image forming apparatus of the present invention, in any one of the present invention of the first to ninth, the control section, when the image is determined as not normal, corrects image forming before reprinting It is characterized by that.

11th image forming system of the present invention includes an image forming unit for forming an image on a sheet, and a control unit for obtaining information of the detected image by the external device, and an image forming apparatus having,
The external apparatus having an image detection unit that detects an image on a sheet conveyed downstream of the image forming apparatus,
The control unit determines whether the image is normal based on the information of the image, and determines that the image is not normal and has an image abnormality. The image forming unit forms a manuscript image or an image pattern in an image non-formed area for at least a part of the remaining paper, and controls the image detecting unit to detect an image on the residual paper. If the image information on the sheet is acquired, the image is determined to be normal based on the image information, and the image is not normal or abnormal, If it is the same as the cause of the previous image error, it is possible to shift to the print stop procedure, and if the cause is a different image error, go to the print stop procedure. Do not migrate And features.

The image forming method of the twelfth aspect of the present invention is to detect an image on a sheet that has been transported and subjected to image formation to acquire information on the image,
Wherein the image based on information of the image it is determined whether normal, the image is rather normal, if it is determined that there is abnormal image, conveying the remaining paper remaining in the machine in the transport state by the paper transport unit In addition, an image forming unit forms a document image or an image pattern in an image non-forming region for at least a part of the residual paper, and executes control for detecting an image on the residual paper by the image detecting unit. When acquiring the information of the upper image, determining whether the image is normal based on the information of the image, and determining that the image is not normal and abnormal, the same factor as the factor of the previous image abnormality If the cause is the same as the cause of the previous image abnormality, it is possible to shift to the print stop procedure, and if the cause is a different image abnormality, the transition to the print stop procedure is not performed. It is characterized by that.

  According to the present invention, when it is determined that the image is abnormal, it is possible to further detect the image of the paper remaining in the machine, acquire image information, perform image determination using the image information, and the like. Effectively using paper, it can be used to detect permanent abnormalities and adjust image quality.

1 is a diagram schematically illustrating an image forming apparatus according to an embodiment of the present invention. Similarly, it is a figure which shows a control block. Similarly, it is a figure which shows the outline of the image forming apparatus in another form. Similarly, it is a diagram illustrating an example of residual paper when an abnormality is detected in the image forming apparatus according to the embodiment. Similarly, it is a diagram illustrating a paper discharge destination when an abnormality is detected. Similarly, it is the flowchart of the flow 1 which shows the sequence of abnormality detection. Similarly, it is the flowchart of the flow 2 which shows the sequence of the reprint after abnormality detection. Similarly, it is the flowchart of the flow 3 which shows the sequence at the time of abnormality detection in a continuous page. Similarly, it is the flowchart of the flow 4 which shows the sequence of the printing stop at the time of abnormality detection. Similarly, it is a flowchart of a flow 5 showing a sequence for determining a paper discharge destination according to an abnormality occurrence state. Similarly, it is the flowchart of the flow 6 which shows the sequence of the feedback at the time of abnormality detection. Similarly, a printing operation, a remaining paper reading operation, and a reprinting operation are described with reference to schematic sheet diagrams. Similarly, it is a diagram illustrating a sheet schematic diagram assuming the same abnormal factors in the printing operation, the remaining sheet reading operation, and the reprinting operation. Similarly, it is a diagram illustrating a sheet schematic diagram assuming the same abnormality factor in consecutive pages in a printing operation, a residual paper reading operation, and a reprinting operation.

Hereinafter, an image forming system 1 according to an embodiment of the present invention will be described with reference to the accompanying drawings.
In the image forming system 1, as shown in FIG. 1, an image forming apparatus 10 that forms an image, a relay apparatus 20, and a post-processing apparatus 30 are connected in series. The relay device 20 corresponds to an external device of the present invention.
In the present invention, the connection configuration of the image forming system is not limited to this, and may be configured only by the image forming apparatus.

The image forming apparatus 10 is provided with an automatic document feeder (ADF) 14 on the upper side, and a document fed by the automatic document feeder (ADF) 14 is imaged by a scanner unit 130 shown in FIG. Reading is possible. The document can be read on a platen glass (not shown).
Further, the LCD 141 of the operation display unit 140 is installed at a position where the platen glass is not positioned on the upper side of the image forming apparatus 10 or the relay apparatus 20. The LCD 141 is configured by a touch panel, and can be operated by an operator and information can be displayed. The LCD 141 serves as both an operation unit and a display unit. The operation unit may be configured with a mouse, a tablet, or the like, and may be configured separately from the display unit. The LCD 141 may be movable.

A plurality of paper feed trays 12 (two stages in the figure) are arranged on the lower side of the image forming apparatus 10.
In the image forming apparatus 10, a transport path 13 for transporting paper fed from one of the paper feed trays 12 is provided, and the image forming unit 11 is provided in the middle of the transport path in the image forming apparatus 10. It has been. The image forming unit 11 includes a photoconductor 11a, a charger, an LD, a developing device, and a transfer unit (not shown) arranged around the photoconductor 11a. Further, the image forming unit 11 has a conveyance path 13 on the downstream side of the photoconductor 11a. A fixing device 15 is disposed. The transport path 13 constitutes a part of the paper transport unit of the present invention.

  On the downstream side of the fixing device 15, the conveyance path 13 extends and is connected to the conveyance path 23 of the relay device 20. Further, a reverse conveyance path 16 that branches on the downstream side of the fixing device 15 and joins the conveyance path 13 on the upstream side of the image forming unit 11 is connected to the conveyance path 13. The reversing conveyance path 16 is provided with a reversing unit 17 for reversing the paper. The sheet reversed by the reversing unit 17 can be returned to the conveyance path 13 on the upstream side of the image forming unit 11 through the reversal conveyance path 16, and the sheet reversed by switching the path is downstream of the fixing unit 15. It is also possible to return to the transport path 13 and transport it to the relay device 20 as it is.

In the image forming unit 11, the surface of the photoconductor 11a is uniformly charged by the charger before the image is written, and the photoconductor 11a having the surface uniformly charged by the LD is irradiated with a semiconductor laser to thereby apply the photoconductor 11a to the photoconductor 11a. An electrostatic latent image is formed. The developing device develops the electrostatic latent image formed on the photoconductor 11a by the LD with the toner member. By this development processing, a toner image is formed on the photoreceptor 11a. The transfer unit transfers the toner image on the photoconductor 11 a onto the paper conveyed from the paper feed tray 12. The sheet onto which the toner image has been transferred is separated from the photoreceptor 11a and conveyed to the fixing device 15. The toner member remaining on the photoconductor 11a is removed by a cleaning unit (not shown).
The fixing device 15 fixes the toner image transferred to the front side of the sheet as an output image by heating the conveyed sheet. The sheet subjected to the fixing process is transported to the relay device 20 by the transport path 13 or is reversed by the reversing unit 17 through the reversal transport path 16 and then transferred to the transport path 13 on the upstream side of the image forming unit 11. Returned. The sheet that has been turned upside down can be image-formed on the back side by the image forming unit 11.

The relay apparatus 20 has a transport path 23 connected to the transport path 13 and connected to the post-processing apparatus 30 at the subsequent stage. The conveyance path 23 includes a reversing / stacking unit 21 that can reverse or stack a predetermined number of sheets conveyed through the conveyance path 23. The sheets stacked in the reversing / stacking unit 21 can be conveyed to the post-processing device 30 side at a predetermined timing, and the post-processing device 30 can be conveyed through the conveying path 23 without stacking the sheets on the reversing / stacking unit 21. The paper can also be transported to the side. Further, it is possible to carry out the reversing / stacking portion 21 and carry it back again.
An in-line sensor 25 that detects an output image on the surface of the paper conveyed on the conveyance path 23 is disposed on the conveyance path 23 on the upstream side of the reversing / stacking unit 21. The in-line sensor 25 can detect an output image with a length corresponding to the maximum width of the paper, and a CCD, CMOS, or the like arranged in a direction (for example, an orthogonal direction) intersecting the paper transport direction is used. it can. The inline sensor 25 corresponds to the image detection unit of the present invention.

  The post-processing device 30 includes a post-processing unit (not shown) corresponding to predetermined post-processing, and predetermined post-processing such as folding and saddle stitching stapling on a sheet conveyed from the relay device 20 according to the post-processing setting. Is done. The post-processing apparatus 30 includes paper discharge units 31 and 32, and can discharge paper by switching the paper discharge destination. If post-processing execution is not set, the paper can be discharged to the paper discharge unit 31 or the paper discharge unit 32 without performing post-processing.

Next, the functional configuration of the image forming apparatus 10 will be described with reference to FIG.
The image forming apparatus 10 includes a control block unit 110, a scanner unit 130, an operation display unit 140, and a printer unit 150, and further processes image data input from an external device 40 such as a terminal PC through the LAN 3, or An image processing unit (print & scanner controller) 160 that enables image data obtained by the scanner unit 130 to be transferred to the external device 40 through the LAN 3 is provided.

  The control block unit 110 has a PCI bus 112 connected to an image processing unit (print & scanner controller) 160, and a DRAM control IC 111 is connected to the PCI bus 112. An image memory (DRAM) 120 is connected to the DRAM control IC 111. The image memory (DRAM) 120 has a compression memory 121 for storing compressed image data and a page memory 122 for temporarily storing uncompressed image data to be printed before image formation. .

In addition, an HDD 119 (hard disk) is connected to the PCI bus 112 via a controller IC 118, and the HDD 119 is connected to image data acquired by the scanner unit 130 and an image processing unit (print & scanner controller) 160. The image data generated by the external device 40 is stored.
The image data acquired by the image processing unit (print & scanner controller) 160 and the image data stored in the HDD 119 are transmitted to the DRAM control IC 111 through the PCI bus 112 along with the printing operation.

The control block unit 110 includes a control CPU 113, and a DRAM control IC 111 is connected to the control CPU 113.
A RAM 114 is connected to the control CPU 113 and is used as a work area or a temporary storage of data when the control CPU 113 operates.
Further, the control CPU 113 is connected to a non-volatile memory 115 constituted by a flash memory or the like. In the non-volatile memory 115, initial print setting information of the image forming apparatus 10, machine setting information such as process control parameters, output setting initial data, an instruction to read an output image, and a case where it is determined that the read image is not normal A factor classification, a criterion for each factor when determining an abnormality, a job stop threshold for the factor, a program for operating the control CPU 113, and the like are stored.
At least one of the RAM 114, the nonvolatile memory 115, the HDD 119, and the like can function as a storage unit of the present invention.

The control CPU 113 can read nonvolatile data in the nonvolatile memory 115 and can write desired data in the nonvolatile memory 115.
The control CPU 113 controls the operation of each unit of the image forming apparatus 10 according to the machine setting information, the print setting information, the output setting, and the like.
The control CPU 113 constitutes a control unit of the present invention and controls the entire image forming apparatus 1.
The control CPU 113 can perform job output settings and operation instructions through the operation display unit 140.

The scanner unit 130 includes a CCD 131 that performs optical reading and a scanner control unit 132 that controls the entire scanner unit 130. The scanner control unit 132 is connected to the control CPU 113 so that serial communication is possible. The CCD 131 is connected to a reading processing unit 116 that processes image data read by the CCD 131, and the reading processing unit 116 is connected to the DRAM control IC 111 in a controllable manner.
The reading processing unit 116 performs various processing such as analog signal processing, A / D (Analog to Digital) conversion processing, shading processing, and the like on the analog image signal input from the CCD 131 to generate digital image data, and compress / Output to the decompression IC 117.
The scanner unit 130 reads an image of a document placed on the upper platen glass of the image forming apparatus 10 or a document automatically conveyed by an automatic document feeder (ADF) 14.

The operation display unit 140 includes an LCD 141 configured as a touch panel that serves as both a display unit and an operation unit, and an operation display unit control unit 142 that controls the entire operation display unit. The operation display unit control unit 142 is a control unit. It is connected to the CPU 113 so that serial communication is possible.
In the operation display unit 140, under the control of the control CPU 113, input of machine settings such as output condition setting and operation control condition in the image forming apparatus 10 and setting of paper information (size, paper type) of each paper feed tray are performed by the LCD 141. Input, display of setting contents, display of desired information such as a message, image display of an output image read by the inline sensor 25, operation instruction and setting input for image display, display, and the like are possible.

The DRAM control IC 111 is connected to a compression / decompression IC 117 capable of compressing or decompressing image data. The DRAM control IC 111 controls the compression process of the image data and the decompression process of the compressed image data by the compression / decompression IC 117 in accordance with an instruction from the control CPU 113 and controls the input / output of the image data to the image memory (DRAM) 120. .
The write processing unit 123 is connected to the image forming unit 11 including the LD 152 of the printer unit 150 and the like, and generates write data used for the operation of the LD 152 based on the image data.

The printer unit 150 includes the image forming unit 11, a paper feed tray 12, a conveyance path 13, a reverse conveyance path 16, a fixing device 15, and the like.
In addition, the printer unit 150 includes a printer control unit 151 that controls the entire printer unit 150 (paper feeding, image formation, paper discharge, post-processing, and the like). The printer control unit 151 performs serial communication with the control CPU 113 described above. Connected as possible. The printer control unit 151 operates according to a control command from the control CPU 113 to control the printer unit 150 to perform paper conveyance, image formation, and the like.

  Further, the DRAM control IC 161 of the image processing unit (print & scanner controller) 160 is connected to the PCI bus 112 to which the DRAM control IC 111 is connected as described above. When using the image forming apparatus 10 as a network printer or a network scanner, the image processing unit (print & scanner controller) 160 receives image data or the like from the external device 40 connected to the LAN 3 or the like. The image data acquired by the scanner unit 130 is transmitted to the external device 40 connected to the LAN 3 or the like.

  In the image processing unit (print & scanner controller) 160, an image memory 162 composed of a DRAM or the like is connected to the DRAM control IC 161. Further, in the image processing unit (print & scanner controller) 160, a DRAM control IC 161 and a controller control unit 163 for controlling the entire image processing unit (print & scanner controller) 160, a LAN control unit 164, and a LAN interface 165 are provided on a common bus. Is connected. The LAN interface 165 is connected to the LAN 3.

  Further, an inline sensor control unit 25a of an inline sensor 25 disposed in the relay device 20 is connected to the control CPU 113 in a controllable manner, and the operation of the inline sensor 25 is controlled by the control CPU 113 via the inline sensor control unit 25a. Can be controlled. Further, the reading result of the inline sensor 25 can be received by the control CPU 113.

Next, basic operations of the image forming apparatus 10 and the image forming system 1 will be described.
First, a procedure for accumulating image data in the image forming apparatus 10 will be described.
A case where the image forming apparatus 10 reads an image with the scanner unit 130 and generates image data will be described. The scanner unit 130 optically reads an image from a document by the CCD 131. At this time, the operation of the CCD 131 is controlled by the scanner control unit 132 that receives a command from the control CPU 113. The document reading may be performed while automatically feeding the document by the automatic document feeder (ADF) 14 or may be performed by placing the document on the platen glass.

  The control CPU 113 operates according to a program and issues a command to the scanner unit 130 based on an operation (reading instruction or copying instruction) by the operation display unit 140. The image read by the CCD 131 is subjected to data processing by the reading processing unit 116, and the image data subjected to the data processing is sent to the compression / expansion IC 117 via the DRAM control IC 111 and compressed by a predetermined method. The compressed data is stored in the image memory (DRAM) 120 via the DRAM control IC 111. When storing the data in the HDD 119, the data once stored in the compression memory 121 is sent to the HDD 119 via the DRAM control IC 111 and the controller IC 118.

In addition, the image data may be input to the image forming apparatus 10 via the LAN 3. Examples of the image data include data generated by an application program such as the external device 40. The method for generating image data is not particularly limited.
The image data is received by the image processing unit (print & scanner controller) 160 via the LAN 3 and the LAN interface 165, and is temporarily stored in the image memory 162 by the DRAM control IC 161. Data stored in the image memory 162 is transferred to the DRAM control IC 111 via the PCI bus 112 and temporarily stored in the page memory 122. Data stored in the page memory 122 is sent to the compression / decompression IC 117 via the DRAM control IC 111, subjected to compression processing, and stored in the compression memory 121 via the DRAM control IC 111. When storing the data in the HDD 119, the data once stored in the compression memory 121 is sent to the HDD 119 via the DRAM control IC 111 and the controller IC 118.

  When the image data is stored, output settings are made before or after storing the image data. The output setting can be performed by an operation input by an operator by displaying a setting screen on which operation input is possible on the operation display unit 140. Further, when the output setting item is selected in the initial setting and the setting input by the operator is not made, the output setting is made by the initial setting.

  When the image forming apparatus 10 outputs an image, that is, when used as a copying machine or a printer, the image data stored in the compression memory 121 is sent to the compression / decompression IC 117 via the DRAM control IC 111 to decompress the data. The expanded data is sent to the writing processing unit 123, and writing is performed by the LD 152 on the photosensitive member 11a charged by the charging unit. When image data stored in the HDD 119 is used, the image data stored in the HDD 119 is temporarily stored in the compression memory 121 via the DRAM control IC 111, and the image data stored in the compression memory 121 is DRAM-controlled. The data is decompressed by sending it to the compression / decompression IC 117 via the IC 111, and the decompressed data is sent to the write processing unit 123 in the same manner as described above.

In the printer unit 150, each unit is controlled by the printer control unit 151 that receives a command from the control CPU 113. In the image forming unit 11, the latent image written on the photoconductor 11 a is developed as a toner image by a developing unit (not shown), and the toner image is transferred to a sheet supplied by a conveyance path 13 by a transfer unit (not shown). Is fixed. In the photoreceptor 11a, after the toner image is transferred onto the paper, the residual toner is removed by a cleaning unit (not shown).
In this embodiment, the description has been made on the assumption of monochrome image formation. However, an image forming apparatus provided with a photoconductor for each color (for example, cyan, magenta, yellow, and black) may be used.

  The sheet on which the image has been formed is conveyed to the relay device 20 via the conveyance path 13, is reversed by the reversing unit 17 of the reverse conveyance path 16, and is conveyed to the relay apparatus 20 via the conveyance path 13, or the reverse conveyance path. 16 is transported to the transport path 13. The sheet circulated to the transport path 13 is subjected to image formation and fixing on the back side, and is transported to the relay device 20 through the transport path 13.

In the relay device 20, all or part of the output image on the surface of the sheet conveyed along the conveyance path 23 is read by the inline sensor 25, and the read image data is transmitted to the control CPU 113. Reading of the output image is performed according to the set instruction content. The setting contents are stored in the nonvolatile memory 115 or the like. The instruction content may be set initially or set by the user. Note that if the image to be detected is positioned on the back side when the sheet is discharged from the image forming apparatus 10 as it is, the image is reversed by the reversing unit 17 and then discharged, thereby enabling the inline sensor 25 to detect the image on the back side. To do. Inline sensors 25 may be arranged above and below the conveyance path 23 so that the front and back images of the paper can be detected at a time.
The sheets are stacked on the reversing / stacking unit 21 according to the setting, or are transported as they are along the transport path 23 to the post-processing device 30. In the post-processing device 30, predetermined post-processing is performed according to the setting, or the post-processing is performed without performing the post-processing, and the paper is discharged to the paper discharge unit 31 or the like.

In the above description, the image detection unit is provided in the subsequent device of the image forming apparatus 10. However, the image detection unit may be provided in the image forming apparatus.
FIG. 3 shows an image forming apparatus 10a provided with an inline sensor 18 corresponding to an image detection unit. The inline sensor 18 can have the same configuration as the inline sensor 25.
The image forming apparatus 10a may be further connected to another apparatus in the subsequent stage, or may be configured only by the image forming apparatus 10a. In addition, the same code | symbol is attached | subjected about the structure same as above-described embodiment, and the description is abbreviate | omitted or simplified.

In this embodiment, an in-line sensor 18 is arranged on the conveyance path 13 downstream of the fixing device 15 and upstream of the point where the reverse conveyance path 16 branches from the conveyance path 13.
In this embodiment, when forming images on the front and back sides of the paper, the output images on the front and back sides can be read by the inline sensor 18.
That is, the paper that has passed through the fixing device 15 is introduced into the paper reversing path 16, the front and the back are reversed by the reversing unit 17, and then returned to the transport path 13, whereby an image is formed on the back side of the paper. The image can be read by the inline sensor 18 on the downstream side of the fixing device 15. Then, the reading result of the inline sensor 18 is transmitted to the control CPU 113.
In this embodiment, since reading can be performed after passing through the fixing device 15 and before reaching the reversal conveyance path 16, it is not necessary to reverse the sheet only for the purpose of reading both sides with an inline sensor.

  In the image forming system 1, an image is detected by the inline sensor 18 or the inline sensor 25, and information on the image is transmitted to the control CPU 113. The control CPU 113 that has acquired the image information grasps the output image data, compares the image data with the image information detected by the inline sensors 18 and 25, and outputs the image output on the sheet. Whether it is normal or abnormal can be determined. In this case, the judgment criteria include, for example, front / back position deviation, color position deviation (for each color of Y / M / C / K), density abnormality (for each color of Y / M / C / K), and toner contamination. (For each color of Y / M / C / K), etc., a standard is determined, and if any of the items exceeds the standard or is out of the standard, it is determined to be abnormal. It can be determined that there is. The criterion for determining the abnormality can be stored in the nonvolatile memory 115 or the HDD 119, for example.

If it is determined that the image is abnormal, normally, other sheets in the transported state remain in the apparatus as shown in FIG. FIG. 4 shows image forming units 11Y, 11M, 11C, 11K, and 11CL for each of Y / M / C / K colors and CL (clear), and having an intermediate transfer belt 11d and a secondary transfer unit 11e. An apparatus 10b is shown, and an inline sensor 18 is disposed on the downstream side of the transfer unit 15 and on the upstream side of the reversing path 16. When an abnormality in the image is detected on the paper A by the inline sensor 18, the inline machine 18 is detected. In this state, the sheet B immediately after the subsequent image transfer is positioned on the conveyance path 13, and the subsequent sheet C is partially in the conveyance path 13 during feeding from the tray 12. In addition, the paper D preceding the paper A is positioned in the reversing path 16, and these papers B, C, and D are conventionally discharged as they are as paper remaining in the apparatus in the conveyance state when an abnormality is detected.

FIG. 5 shows a paper discharge destination when an image abnormality is detected in the image forming system 1 shown in FIG. Normal paper is ejected to the paper ejection unit 31, and paper (also referred to as sag paper) in which an abnormality (also referred to as sag) has been detected and paper remaining at the time of detection of abnormality (also referred to as sag paper) are discharged. The paper is discharged to the paper section 32 and distinguished.
In the present embodiment, the residual paper is not discharged as it is, but an image is detected by the inline sensors 18 and 25 and the detection result is used. Below, the example of the sequence of the flow 1 is demonstrated based on the flowchart of FIG. The following procedure is executed by control by the control unit.

With the start of printing, the image of the paper that has passed through the fixing device is read by the inline sensor (step s1). Information on the read image is acquired by the control unit, and it is determined whether an abnormality is detected based on a predetermined factor or threshold (step s2). If there is no abnormality (step s2, normal), the procedure for reading the next page is advanced (step s3), and reading is performed by the inline sensor (step s1).
The same procedure is performed on sequential pages, and when it is determined that an abnormality is detected in the image (step s2, abnormality), the abnormality factor is stored in the RAM 114, the HDD 119, etc. (step s4). In this embodiment, the abnormality factor is stored together with the page information. Table 1 is a table including page information and control information. The reading result (OK or NG) is recorded for each page based on the detection result, and in the case of abnormality (NG), the cause of the abnormality is stored. doing. In the example of Table 1, pages 1 and 2 are normal and an abnormality is first detected on page 3, and the cause is a color shift of yellow (Y).
Further, the table shows a residual flag, necessity of printing, and items to be reprinted. The remaining flag is set to ON with the start of paper feeding, and is set to OFF when an image is read by an inline sensor. In addition, in the abnormality detection determination, the reprint item No is set for those determined to be normal, and the reprint item is set to Yes for the page where the abnormality is detected (in this example, page 3).

  Next, the in-machine residual paper is calculated (step s5). In the control unit, for example, the gap between the sheets is grasped, and the in-machine residual paper can be calculated. Next, page information of the remaining paper is created (step s6). As shown in Table 2, the remaining paper page information is obtained by adding to the paper information until an abnormality is detected. Note that the remaining paper (pages 4 to 7 in this example) is set to the reprint target with the remaining flag set to ON.

  Next, control information for the remaining paper is created (step s7). In the control information, the necessity of printing is determined according to the image forming state of the remaining paper, and necessity / unnecessity is stored in the table as shown in Table 3. In this example, among pages 4 to 7 that are residual paper, pages 4 and 5 are pages on which image formation has been completed, and printing on the residual paper is unnecessary. On the other hand, since pages 6 and 7 are before image formation, printing is required.

Next, it is determined whether an image has been printed on the remaining paper (step s8). If the image has been printed (step s8, printed), it is determined whether all pages of the remaining paper have been reached (step s10). If the corresponding page has not been printed (step s8, unprinted), an image pattern is added to the print information to determine whether all pages of the remaining paper have been reached (step s10). If all pages of the remaining paper have not been reached (step s10, remaining pages are present), the process returns to step s7 and the same process is performed for the next page. If all pages have been reached (step s10, no remaining pages), the remaining paper is controlled (step s11). Specifically, for example, control is performed based on the control information created in step s7. First, it is determined whether the page has an image printed (step s12). If the page has not been printed (step 12, unprinted), a predetermined pattern is printed on the corresponding sheet. For the pattern, a chart provided for image inspection can be used. In addition, as the image pattern, the type of pattern may be selected depending on a factor that is abnormal for the page. Further, instead of an image pattern, a document image may be printed.
Whether or not the image on the remaining paper has been printed can be determined based on whether or not the image is blank, and can also be determined based on whether or not the image is printed in a specific area.
According to the above, it is possible to print the image pattern on the residual paper before the image is transferred and perform the check on the paper by inline sensor reading.

After printing the image pattern or when the image has been printed (step s12, printed), the procedure for reading the next page is advanced (step s14), and the next page image is read by the inline sensor (step s15). It is determined whether it has been detected (step s16). If there is an abnormality (step s16, abnormality), as shown in Table 4, the abnormality factor in the remaining paper is stored in the page information table (step s17), and it is determined whether all the remaining paper pages have been reached (step s17). Step s18).
Note that when storing the cause of abnormality, the residual flag remains ON even after reading the inline sensor in order to clarify that the paper is residual.
Based on the above, it is possible to perform a check on the slip sheet by inline sensor reading including the slip sheet remaining in the machine (following page) when the slip sheet is detected (first page).
Note that printing on residual paper is one of the printing operations.

If no abnormality is detected (step s16, normal), it is similarly determined whether all the remaining pages have been reached (step s18).
If all pages have not been reached (step s18, remaining pages are present), the process returns to step s11 to control the remaining paper. If all pages of the remaining paper have been reached (step s18, no remaining pages), the process is terminated.
In the above procedure, by detecting the image of the paper remaining in the apparatus, when an abnormality is detected again, the cause of the abnormality can be stored and the information can be used.

The paper in which the abnormality is detected and the paper remaining in the machine are discharged as scraped paper, and those used for normal printing can be obtained by reprinting these pages. In other words, the reprint operation can be performed by setting the range from the first page at the time of detecting the waste paper to the residual waste paper as a reprint target. Reprinting is one of printing operations.
At the time of reprinting, the sheet information and the cause of abnormality in the sheet in which the abnormality is detected and the sheet remaining in the apparatus are recorded as a table.
Further, as shown in Table 5, an abnormality list (factors and the number of occurrences) and a threshold value (number of times) for stopping printing when an abnormality occurs are set in advance for each factor category. The threshold value can be stored in the nonvolatile memory 115 or the HDD 119.

Next, the sequence during reprinting (flow 2) will be described based on the flowchart of FIG. The following procedure is executed by control by the control unit.
With the start of reprinting, the image of the paper that has passed through the fixing device is read by the inline sensor (step s20). Information on the read image is acquired by the control unit, and it is determined whether an abnormality is detected based on a predetermined factor or reference (step s21). If there is no abnormality (step s21, normal), the procedure for reading the next page is advanced (step s22), and reading is performed by the inline sensor (step s20).

  The same procedure is performed on sequential pages, and when it is determined that an abnormality in the image is detected (step s21, abnormality), the cause of the abnormality is determined, and the number of times is added to the history in Table 5 as shown in Table 6. Then, the error factor detected in the flow 1 is checked to determine whether or not the error is the same (step s23). The cause of the abnormality in the remaining paper in the previous print is stored in the table shown in Table 4, for example. The abnormalities at the time of reprinting include, for example, front / back position deviation, color position deviation (for each color of Y / M / C / K), density abnormality (for each color of Y / M / C / K), toner stain (Y / M / Standards are determined by factors such as C / K for each color), and if any item exceeds the standard or exceeds the standard, it is determined that the relevant factor is abnormal. It can be determined that there is. The criterion for determining the abnormality can be stored in the nonvolatile memory 115 or the HDD 119, for example.

  For example, as shown in the first table of Table 7, when the cause of abnormality is the same between the current reprint and the previous print (the previous print operation, the remaining paper print, the previous reprint, etc.) (step s23, The same abnormality; in this example, a yellow color shift in page 3), it is determined whether the abnormality in reprinting exceeds a threshold value (step s24). The abnormality threshold value can be stored, for example, in the nonvolatile memory 115 or the HDD 119. The threshold value may be set by the user or may be set for each user. When it is determined that the abnormality exceeds the threshold (step s24, it exceeds), the printing process is stopped and the sequence is ended (step s25).

  As shown in the second table of Table 7, when the cause of abnormality is different between the current reprint and the previous print in step s23 (step s23, different abnormality; in this example, for the first time on page 5, the magenta color When the error is detected), or the cause of the abnormality is the same in the current reprint and the previous print and the abnormality does not exceed the threshold (step s24, not exceeded), the cause of the abnormality in the current reprint is As shown in Table 7, it is added to the page information and stored (step s26).

  Next, the in-machine residual paper for reprinting is calculated (step s27). In the control unit, for example, the gap between the sheets is grasped, and the in-machine residual paper can be calculated. Next, page information of the remaining paper is created (step s28). As shown in Table 8, the remaining paper page information is obtained by adding to the paper information until an abnormality is detected. Note that the remaining paper has the remaining flag set to ON, and is further subject to reprinting.

  Next, control information for the remaining paper is created (step s29). In the control information, the necessity of printing is determined according to the position of the remaining paper, and necessity / unnecessity is stored in the table as shown in Table 8. In this example, among pages 6 to 8 that are reprint residual paper, pages 6 and 7 are pages on which image formation has been completed, and printing on the residual paper is unnecessary. On the other hand, since page 8 is before image formation, printing is required.

  Next, it is determined whether an image has been printed on the remaining paper (step s30). If the image has been printed (step s30, printed), it is determined whether all pages of the remaining paper have been reached (step s32). If the corresponding page has not been printed (step s30, unprinted), an image pattern is added to the print information to determine whether all pages of the remaining paper have been reached (step s32). If all the pages of the remaining paper have not been reached (step s32, remaining pages are present), the process returns to step s29 and the same process is performed for the next page. If all pages have been reached (step 32, no remaining pages), the remaining paper is controlled (step s33). Specifically, for example, control is performed based on the control information created in step s29. First, it is determined whether the page has an image printed (step s34). If the page has not been printed (step 34, not printed), a predetermined pattern is printed on the corresponding sheet (step s35). For the pattern, a chart provided for image inspection can be used. In addition, as the image pattern, the type of pattern may be selected depending on a factor that is abnormal for the page. Further, instead of an image pattern, a document image may be printed.

  After image pattern printing (step s35), or when the image has been printed (step s34, printed), the procedure for reading the next page is advanced (step s36), and the image on the next page is read by an inline sensor (step s37). ), It is determined whether an abnormality is detected (step s38). If there is an abnormality (step s38, abnormality), the abnormality factor is determined, added to the number of history in the abnormality list as shown in Table 6, and the error factor detected in the flow 1 is checked to determine whether the abnormality is the same. (Step s39). It is also possible to check whether the cause of the error detection is the same between the residual paper page and the corresponding page at the time of the reprint operation.

  The cause of the abnormality in the remaining paper in the previous print is stored in the table shown in Table 4, for example. The abnormalities at the time of reprinting include, for example, front / back position deviation, color position deviation (for each color of Y / M / C / K), density abnormality (for each color of Y / M / C / K), toner stain (Y / M / The standard value is determined by factors such as each color of C / K), and if any of the items exceeds the standard value, it is determined that the corresponding factor is abnormal, and if all do not exceed the standard value, it is normal. Can be determined. The reference value for abnormality determination can be stored in, for example, the nonvolatile memory 115 or the HDD 119.

  If the cause of the abnormality is the same in the remaining paper in the current reprint and the previous print (step s39, the same abnormality), it is determined whether the abnormality in the residual paper in the reprint exceeds the threshold (step s40). The abnormality threshold value can be stored, for example, in the nonvolatile memory 115 or the HDD 119. The threshold value may be set by the user or may be set for each user. If it is determined that the abnormality exceeds the threshold value (exceeding step s40), the printing process is stopped and the process is terminated (step s41). If the cause of abnormality is different between the current reprint residual paper and the previous print in step s38 (step s39, different abnormality), or the cause of abnormality is the same between the current reprint residual paper and the previous print. If the abnormality does not exceed the threshold value (step s40, it does not exceed), the cause of the abnormality in the current reprint residual paper is stored in the RAM 114, the HDD 119, etc. as shown in the table of Table 9 (step s42).

  When it is determined that there is no abnormality in the abnormality detection determination (step s38, normal), or after step s42, it is determined whether all pages of the remaining paper have been reached (step s43). If all the pages of the remaining paper have not been reached (step s43, remaining pages are present), the process returns to step s33, and the same process is performed for the next page. If all pages have been reached (step 43, no remaining pages), the process is terminated.

Next, the sequence of the flow 3 in the case where an abnormality is detected in continuous page printing between different printing operations will be described based on the flowchart of FIG.
With the start of printing, the image of the paper that has passed through the fixing device is read by the inline sensor (step s50). Information of the read image is acquired by the control unit, and it is determined whether an abnormality is detected by a predetermined factor or threshold (step s51). If there is no abnormality (step s51, normal), the procedure for reading the next page is advanced (step s52), and reading is performed by the inline sensor (step s50). The same procedure is performed on the sequential pages, and when it is determined that an abnormality is detected in the image (step s51, abnormality), the abnormality factor is determined and added to the number of history of the abnormality list as shown in Table 6, As shown in Table 1, abnormal factors are stored (step s53). Causes of abnormality include, for example, front / back position deviation, color position deviation (for each color of Y / M / C / K), density abnormality (for each color of Y / M / C / K), and toner contamination (Y / M / C). / K for each color) and the like, and are stored in the nonvolatile memory 115 and the HDD 119.

  Next, the in-machine residual paper is calculated (step s54). In the control unit, for example, the gap between the sheets is grasped, and the in-machine residual paper can be calculated. Next, page information of the remaining paper is created (step s55). As shown in Table 2, the remaining paper page information is obtained by adding to the paper information until an abnormality is detected. Note that the remaining paper is set to be reprinted with the remaining flag set to ON.

Next, control information for the remaining paper is created (step s56). In the control information, the necessity of printing is determined according to the position of the remaining paper, and necessity / unnecessity is stored in the table shown in Table 3.
Next, it is determined whether an image has been printed on the remaining paper (step s57). If the image has been printed (step s57, printed), it is determined whether all pages of the remaining paper have been reached (step s59). If the page has not been printed (step s57, not printed), an image pattern is added to the print information to determine whether all the remaining pages have been reached (step s59). If all pages of the remaining paper have not been reached (step s59, remaining pages are present), the process returns to step s56 and the same processing is performed for the next page. If all pages have been reached (step 59, no remaining pages), the remaining paper is controlled (step s60). Specifically, for example, control is performed based on the control information created in step s56. It is determined whether the page has been printed (step s61). If not printed (step 61, not printed), a predetermined pattern is printed on the corresponding sheet (step s62). For the pattern, a chart provided for image inspection can be used. In addition, as the image pattern, the type of pattern may be selected depending on a factor that is abnormal for the page. Further, instead of an image pattern, a document image may be printed.

  After the image pattern printing (step s62) or when the image has been printed (step s61, printed), the procedure for reading the next page is advanced (step s63), and the image on the next page is read by an inline sensor (step s64). ), It is determined whether an abnormality is detected (step s65). If there is an abnormality (Step s65, Abnormal), based on the abnormality factor detected in Step s51, it is determined whether an abnormality has occurred in the remaining paper page that is continuous with the abnormal paper and whether the abnormality is the same (Step s66). ). When the same abnormality has occurred in the continuous printing (step s66, the same abnormality), it is determined whether the abnormality exceeds the threshold (step s67). If the abnormality exceeds the threshold (step s67, it exceeds), the printing process is stopped and the sequence is ended (step s68). When there is no abnormality in printing continuous pages, or when there is an abnormality in printing continuous pages and the same abnormality factor is not the same (step s66, different abnormality), or the threshold is not exceeded (step s67, it is not exceeded) ), The abnormal factor is stored in the page information (step s69).

  When it is determined that there is no abnormality in the abnormality detection determination (step s65, normal), or after step s69, it is determined whether all the remaining pages have been reached (step s70). If all pages of the remaining paper have not been reached (step s70, remaining pages are present), the process returns to step s60 and the same processing is performed for the next page. If all pages have been reached (step s70, no remaining pages), the process is terminated.

Next, the sequence of the flow 4 for stopping printing when an abnormality is detected will be specifically described based on the flowchart of FIG.
With the start of the sequence, it is determined whether an abnormality has been detected as in the above-described flows (step s80). If there is no abnormality (No in step s80), a reprint operation is performed (step s81). If an abnormality is detected (step s80, Yes), it is first determined whether the front / back position is shifted (step s82). If it is a front / back position deviation (step s82, Yes), the count is added to the front / back position deviation item of the abnormality NG factor table in the abnormality history shown in Table 5 (step s83), and it is determined whether the threshold value is exceeded (step s83). Step s88). If it is not a front / back position shift (No at step s82), it is determined whether the color is shifted (step s84). If it is a color shift (step s84, Yes), it is determined whether the color is Y / M / C / K (step s87). Next, it is determined whether or not the threshold is exceeded for the corresponding color (step s88).

If it is not a color shift (No at step s84), it is determined whether the density is abnormal (step s85). If the density is abnormal (step s85, Yes), it is determined whether the color is Y / M / C / K (step s87). Next, it is determined whether or not the threshold is exceeded for the corresponding color (step s88).
If the density is not abnormal (step s85, No), it is determined whether the toner is dirty (step s86). If the toner is smeared (step s86, Yes), it is determined whether the color is Y / M / C / K (step s87). Next, it is determined whether or not the threshold is exceeded for the corresponding color (step s88).
If there is another abnormality (step s86, No), other abnormality factors are determined (step s89), printing is stopped (step s90), and the process is terminated.
If it is determined that the abnormality exceeds the threshold (step s88) and the threshold is not exceeded (No at step s88), a reprint operation is performed (step s81). As shown in Table 10, when it is determined that the threshold is exceeded in any item (step s88, Yes), printing is stopped (step s90), and the process is terminated. In the example of Table 10, the number of detections of yellow color misregistration is 6, which exceeds the threshold value of 5 times.

Next, a flow 5 sequence for selecting a paper discharge tray when an abnormality is detected will be described with reference to the flowchart of FIG.
The paper image is read by an in-line sensor (step s100), and it is determined whether it is normal reading or scanning of the waste paper after detecting an abnormality (step s101). In the case of reading paper (step s101, reading paper), the paper is discharged onto a paper tray (step s104), and it is determined whether all pages are discharged (step s105). In the case of normal reading (step s101, normal reading), it is determined whether an abnormality has been detected (step s102). If an abnormality is detected (step s102, Yes), the paper is discharged to the waste paper tray (step s104), and it is determined whether all pages are discharged (step s105). If no abnormality is detected (No in step s102), the sheet is discharged to the normal tray (step s103), and it is determined whether all pages are discharged (step s105). If all pages are not discharged (step s105, No), the process returns to step s100 to sequentially read the next page. If all pages are discharged (step s105, Yes), the process ends.

Next, the sequence of the flow 6 regarding the feedback at the time of abnormality detection is demonstrated based on the flowchart of FIG.
First, an abnormality list is read (step s110), and whether or not a front / back position deviation has occurred is determined (step s111). Table 11 shows an example of the abnormality list. In this example, the threshold value is exceeded due to an abnormality in yellow color deviation and magenta density.

If front / back position misalignment occurs (step s111, present), registration adjustment for adjusting the paper position is executed (step s112), and the process proceeds to determination of whether or not color misregistration occurs (step s113). Similarly, when there is no occurrence of front / back position deviation (step s111, no), the process similarly proceeds to determination of whether or not color deviation has occurred (step s113).
If color misregistration has occurred (Yes in step s113), color registration adjustment is performed (step s114) to adjust the corresponding color misregistration, and the process proceeds to determination of whether or not density abnormality has occurred (step s115). If no color misregistration occurs (No in step s113), the process similarly proceeds to the determination of whether or not density abnormality has occurred (step s115).

If density abnormality has occurred (step s115, present), density balance adjustment, maximum density adjustment, thinning intensity adjustment, etc. are executed (step s116), and the process proceeds to determination of whether toner contamination has occurred (step s117). If no density abnormality has occurred (step s115, no), the process similarly proceeds to the determination of the presence or absence of toner contamination (step s117).
If toner contamination has occurred (step s117, yes), blank page printing is executed, blank page cleaning is performed (step s118), and it is determined whether all NG lists have been checked (step s119). If all the NG lists have not been checked (step s119, No), the process returns to step s110, and the abnormality list is read. Although not shown in the flow of the figure, feedback control can be similarly performed for other abnormal items.
If all checks of the NG list have been completed, the process is terminated.

  According to this embodiment, it is possible not only to simply discharge a wasteful page, but also to save and feed back valid information, so that it is possible to suppress the occurrence of continuous abnormalities and suppress a wasteful reprint operation. .

FIGS. 12 to 14 are diagrams for explaining an operation at the time of detecting an abnormality in each printing operation with a schematic diagram of paper. Shading indicates that an image is being formed.
In the printing operation of FIG. 12, in printing in a job of N pages, a positional deviation is detected on page 4, and pages 5 to 7 are remaining sheets in the apparatus in the transported state. An image is formed on page 5 of the remaining paper, and no image is formed on pages 6 and 7.
These remaining sheets are sequentially discharged and images are read by an in-line sensor. At this time, on the sheets of pages 6 and 7 on which no image is formed, an image pattern is printed and the image is read. Furthermore, the reprint operation after page 4 is possible.
It should be noted that the printing on the remaining paper and the reprinting operation correspond to different printing operations.

In the printing operation of FIG. 13, in the same manner as described above, in the printing of the N-page job, the positional deviation is detected on page 4, and pages 5 to 7 are the remaining sheets in the apparatus in the transported state. . An image is formed on page 5 of the remaining paper, and no image is formed on pages 6 and 7.
These remaining sheets are sequentially discharged and images are read by an in-line sensor. At this time, on the sheets of pages 6 and 7 on which no image is formed, an image pattern is printed and the image is read.
Further, the reprinting operation after page 4 is performed, and an abnormality occurs on the same page as the printing operation and due to the same factor (image position shift in this example). In this case, it can be determined whether to continue or stop the reprint depending on whether the corresponding factor exceeds the threshold.

In the printing operation of FIG. 14, in the same manner as described above, in the printing in the N-page job, the positional deviation is detected on page 4, and the pages 5 to 7 are the remaining sheets in the apparatus in the transported state. . An image is formed on page 5 of the remaining paper, and no image is formed on pages 6 and 7.
These remaining sheets are sequentially discharged and images are read by an in-line sensor. At this time, on the sheets of pages 6 and 7 on which no image is formed, an image pattern is printed and the image is read.
In the image reading of the remaining paper, whether or not the image is normal is determined, and pages 5 and 7 are determined to be normal, but page 6 is abnormal due to the same factor (image misalignment in this example) as page 4 during the printing operation. There has occurred. For this reason, it can be determined that the same abnormality factor has occurred in a page continuous with the printing operation. In this case, it can be determined whether the reprint is continued or stopped depending on whether the cause of the abnormality exceeds the threshold.

Further, each of the above embodiments is characterized by the following configuration.
1. An in-line sensor that reads an image on the output paper after passing through the fixing is provided.
2. The in-line sensor has means for detecting front / back position deviation, color position deviation, character density abnormality, image density abnormality, and toner contamination.
3. At the time of abnormality detection, there is means for detecting an abnormality with an in-line sensor even for pages remaining in the machine.
4). A means for printing an image pattern (chart) or a document image on a page before image printing among the pages remaining in the apparatus at the time of abnormality detection.
5. Means for calculating the cause of the abnormality detected by the inline sensor and page information.
6). Means for reprinting the first page and the remaining page when an abnormality is detected.
7). When an abnormality is detected during the reprinting operation, there is means for comparing with the factor history of the corresponding page and determining whether or not the factor is the same.
8). When an abnormality of the same factor occurs between pages that are continuously printed, it has means for determining whether or not the threshold is exceeded and stopping the reprint operation.
9. Prior to the reprinting operation, a means for correcting from an abnormality factor is selected and automatically corrected.

  As described above, the present invention has been described based on the above embodiments, but the present invention is not limited to the description of the above embodiments, and can be appropriately changed without departing from the scope of the present invention. It is.

DESCRIPTION OF SYMBOLS 1 Image forming system 10 Image forming apparatus 10a Image forming apparatus 10b Image forming apparatus 11 Image forming part 18 Inline sensor 20 Relay apparatus 25 Inline sensor 30 Post-processing apparatus 113 Control CPU
115 Non-volatile memory 130 Scanner unit 140 Operation display unit 150 Printer unit

Claims (12)

A paper transport unit for transporting paper,
An image forming unit for forming an image on the paper;
An image detecting unit for detecting an image on a sheet conveyed by the sheet conveying unit on a downstream side of the image forming unit;
A control unit that acquires information of an image detected by the image detection unit,
The control unit determines whether the image is normal based on the information of the image, and determines that the image is not normal and has an image abnormality. The image forming unit forms a manuscript image or an image pattern in an image non-formed area for at least a part of the remaining paper, and controls the image detecting unit to detect an image on the residual paper. If the image information on the sheet is acquired, the image is determined to be normal based on the image information, and the image is not normal or abnormal, If it is the same as the cause of the previous image error, it is possible to shift to the print stop procedure, and if the cause is a different image error, go to the print stop procedure. Do not migrate An image forming apparatus comprising.   The image detection unit is disposed at a position for detecting an image on a sheet that has passed through the fixing device, and the control unit is configured to detect a front / back position shift, a color position shift, a character of the image based on the information on the image. 2. The image forming apparatus according to claim 1, wherein it is determined whether at least one of density, image density, and toner contamination is normal. The image forming apparatus according to claim 1, wherein the non-image forming area is a blank sheet surface of a blank sheet. A storage unit for storing data;
When the control unit determines that the image is not normal according to the determination, the control unit stores the page information of the sheet related to the image determined to be not normal and the factor that is not normal in a readable manner in the storage unit. The image forming apparatus according to claim 1.   When the control unit determines that the image is not normal based on the image information, the control unit has a function of reprinting from the page of the paper determined to be not normal to at least another page of the paper remaining in the machine in the transport state. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided.   2. The control unit according to claim 1, wherein the image detection unit detects an image on the reprinted paper, acquires image information, and determines whether the image is normal based on the image information. 5. The image forming apparatus according to 5. A storage unit for storing data, in which the page information of the paper relating to the image determined to be abnormal in the previous print operation and the abnormal factor are readable and stored;
If the image is not normal on the same page as the page in which the image is determined to be not normal in the previous print operation in the current print operation, and the respective abnormal factors on the corresponding page are the same, The image forming apparatus according to claim 1, wherein when the number of image abnormalities for each factor exceeds a threshold, the job is stopped without continuing the current print operation. When there are a plurality of pages in which the image is not normal and the cause of abnormality is the same among the pages that are continuously printed in different printing operations, the control unit performs the number of times of image abnormality for each factor due to the factor. The image forming apparatus according to claim 1, wherein when the value exceeds a threshold value, the job is stopped without continuing the reprint operation. The image forming apparatus according to claim 1, wherein the control unit manages, as an abnormal factor, one or more of the following categories.
-Front / back position deviation-Color position deviation (Y / M / C / K for each color)
・ Abnormal density (for each color Y / M / C / K)
-Toner stain (for each color Y / M / C / K)   The image forming apparatus according to claim 1, wherein the control unit performs correction related to image formation before reprinting when it is determined that the image is not normal. An image forming unit for forming an image on a sheet, and a control unit for obtaining information of the detected image by the external device, and an image forming apparatus having,
The external apparatus having an image detection unit that detects an image on a sheet conveyed downstream of the image forming apparatus,
The control unit determines whether the image is normal based on the information of the image, and determines that the image is not normal and has an image abnormality. The image forming unit forms a manuscript image or an image pattern in an image non-formed area for at least a part of the remaining paper, and controls the image detecting unit to detect an image on the residual paper. If the image information on the sheet is acquired, the image is determined to be normal based on the image information, and the image is not normal or abnormal, If it is the same as the cause of the previous image error, it is possible to shift to the print stop procedure, and if the cause is a different image error, go to the print stop procedure. Do not migrate The image forming system according to claim. Detecting the image on the paper that has been transported and subjected to image formation to obtain information on the image;
Based on the information of the image, it is determined whether the image is normal, and when it is determined that the image is not normal and there is an image abnormality, the residual paper remaining in the apparatus in the transport state is transported by the paper transport unit. A document image or an image pattern is formed by an image forming unit in an image non-formation area for at least a part of the residual paper, and control for detecting an image on the residual paper by the image detection unit is executed to If the image information is acquired, the image is determined to be normal based on the image information, and the image is determined to be abnormal and abnormal, the same factor as that of the previous image abnormality If it is the same as the cause of the previous image abnormality, it is possible to proceed to the print stop procedure, and if it is a different cause of image abnormality, do not proceed to the print suspension procedure. A picture featuring Forming method.

Images