JP7006186B2 - Image formation system - Google Patents

Description

The present invention relates to an image forming system having an image defect detection function.

Conventionally, as shown in FIG. 1, an image formed on a paper P output from an image forming apparatus is read by a first reading unit 41 and a second reading unit 42, and the scanned image is subjected to image processing to obtain an image. Functions for adjustment, correction, and detection of image defects (also called "spoilage detection") have been developed. Paper that is determined to have image defects (hereinafter sometimes referred to as "spoiled paper") needs to be ejected (abnormally ejected) to a tray different from the normal output tray.

As shown in FIG. 1, a predetermined time (processing completion time T1) is required from the time when the paper passes through the first reading unit 41 and the reading is completed until the image processing for detecting the image defect is completed. Since the paper on which the image is formed is conveyed during that time, the target paper is ejected to the normal paper ejection tray at a position ahead of the position at the time when the image defect determination is completed (downstream in the paper conveying direction). It is necessary to provide a switching unit for switching the transport route for discharging to a tray different from the route. Therefore, there is a problem that the transport path of the device becomes long (the width of the device becomes large).

FIG. 2 is an explanatory diagram showing the prior art. In FIG. 2A, the post-processing device 220 is connected to the downstream side of the image reading device 210. The post-processing device 220 includes a paper ejection tray 221 on which normal paper P is conveyed and a purge tray 222 on which spoiled paper is ejected. FIG. 2A shows a state in which the spoiled paper cannot be discharged in time because the transport path is short and the processing completion time T1 is not secured. FIG. 2B shows a state in which the transport path of the image reading device 210 is long and the size of the device is increased, although the transport path is long and the processing completion time T1 is secured.

If only one sheet of paper is ejected as having an image defect (spoiled paper) and the subsequent normal paper is ejected to a normal output tray, page omission will occur. For this reason, even if the subsequent paper existing on the transport path is normal, it is necessary to eject all the subsequent paper as spoiled paper to a tray different from the usual one, and there is a problem that the spoiled paper is wasted.

For example, in Patent Document 1, it is determined whether the paper on which the image is formed is defective based on the detection result of the defect detection unit, and if it is determined to be defective, the page determined to be defective and the subsequent pages are reprinted. Disclosed is an image forming apparatus that prints and ejects paper to a paper ejection destination different from the paper ejection destination immediately before the defect determination.

Japanese Unexamined Patent Publication No. 2014-144627

However, Patent Document 1 does not mention shortening the transport path of the device to suppress an increase in the width of the device. In addition, when the number of pages of the job extends over a plurality of pages, there is no mention of suppressing spoiled paper by effectively utilizing the normal paper remaining on the subsequent transport path when an image defect occurs. Further, since the reprinted page is ejected to a paper ejection destination different from the paper ejection destination immediately before the defect determination, the work of combining the page group before reprinting and the reprinted page group is separately required. Workers need to pay attention to the order and perform the coalescence work, and check if there are any page omissions.

The present invention has been made in consideration of the above situation, and at least either suppresses an increase in the width of the device (for example, the width of the image reading device) or reduces the amount of spoiled paper when an image defect occurs. The purpose is to achieve.

The image forming system of one aspect of the present invention includes a paper conveying unit that conveys the fed paper, an image forming unit that forms an image on the paper, an image reading unit that reads an image formed on the paper, and the image. Located on the downstream side of the reading unit, it is configured so that two sheets of paper can be stacked and stacked. A two-sheet stacking section, a post-processing section that performs post-processing on the paper on which an image is formed located on the downstream side of the two-sheet stacking section, and a paper ejection section that ejects paper that is not conveyed to the post-processing section. A control unit that controls paper feeding, transfer, image formation, operation of the two-sheet stacking unit, and switching of the paper transfer destination, acquires the reading information of the image reading unit, and determines whether the paper is normal or abnormal. Be prepared.
The control unit reads an image by the control unit between the time when the second sheet is introduced into the two-sheet stacking unit and the time when the second sheet is ejected when the two sheets are not stacked and ejected. Judgment of normality / abnormality of the paper based on the reading information of the part is completed. Then, when the control unit determines that the paper is abnormal based on the reading information of the image reading unit, the control unit stops the operation of forming an image on the paper, and the page determined to be abnormal and the subsequent pages are the transport paths. It is controlled to eject a part or all of the image-formed paper remaining in the paper to the paper ejection unit.

In the present specification, among the papers introduced in the two-sheet stacking portion, the paper introduced earlier is referred to as "first sheet", and the paper introduced later is referred to as "second sheet".

According to at least one aspect of the present invention, the width of the apparatus (for example, the width of the image reading apparatus) is increased by controlling the two-sheet stacking portion so as to effectively utilize the normal paper remaining on the subsequent transport path when an image defect occurs. It is possible to suppress the problem and reduce the amount of spoiled paper when image defects occur.
Issues, configurations and effects other than those described above will be clarified by the following description of the embodiments.

It is explanatory drawing (1) which shows the prior art. It is explanatory drawing (2) which shows the prior art. It is schematic cross-sectional view which shows the structural example of the image formation system which concerns on 1st Embodiment of this invention. It is a block diagram which shows an example of the control system of each apparatus constituting the image formation system which concerns on 1st Embodiment of this invention. It is a block diagram which shows the functional example of the control part of the image forming apparatus which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows an example of the transfer mechanism of the relay transfer device which concerns on 1st Embodiment of this invention. It is a flowchart which shows the procedure example of the two-sheet stack operation of the relay transfer apparatus which concerns on 1st Embodiment of this invention. It is explanatory drawing in the case of stacking two sheets of paper in the two-sheet stacking part of the relay transfer apparatus which concerns on 1st Embodiment of this invention. It is a flowchart which shows the procedure example of the double stack discharge of the relay transfer apparatus which concerns on 1st Embodiment of this invention. It is explanatory drawing in the case of ejecting two sheets of paper from the two-sheet stacking part of the relay transfer apparatus which concerns on 1st Embodiment of this invention. It is a flowchart which shows the procedure example of discharge only one piece of the relay transfer apparatus which concerns on 1st Embodiment of this invention. It is explanatory drawing in the case of ejecting one sheet from the two-sheet stacking part of the relay transfer apparatus which concerns on 1st Embodiment of this invention. When the number of pages of the job according to the first embodiment of the present invention is one, two sheets of paper are introduced into the two-sheet stacking portion 55, and then one sheet of paper is discharged to the post-processing device 60. It is explanatory drawing of the operation which introduces the next form. When the number of pages of the job according to the first embodiment of the present invention is one, after introducing two sheets of paper into the two-sheet stacking portion 55 and then ejecting one sheet of paper to the post-processing device 60. It is explanatory drawing of the operation which introduces the next sheet while continuously ejecting one sheet to a purge tray. It is explanatory drawing which shows the unit of the spoiler paper suppression control processing which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows the processing example at the time of image defect occurrence and after the job restart in the case where the number of pages of a job which concerns on 2nd Embodiment of this invention is 2 or more. It is explanatory drawing which shows the operation example after the job restart of the relay transfer apparatus which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the procedure example of the spoiler paper suppression control processing of the relay transfer apparatus which combined the 1st Embodiment and 2nd Embodiment of this invention. It is a flowchart which shows the procedure example of the spoiler paper suppression control processing of the relay transfer apparatus at the time of resuming a job which concerns on 1st and 2nd Embodiment of this invention.

Hereinafter, examples of embodiments for carrying out the present invention (hereinafter, referred to as “embodiments”) will be described with reference to the accompanying drawings. In the present specification and the accompanying drawings, components having substantially the same function or configuration are designated by the same reference numerals and duplicated description will be omitted.

<1. First Embodiment>
[Overall configuration of image formation system]
FIG. 3 is a schematic cross-sectional view showing a configuration example of the image forming system 1 according to the first embodiment.
The image forming system 1 shown in FIG. 3 includes an image forming device 10, an image reading device 40, a relay transfer device 50, and a post-processing device 60.

The image forming apparatus 10 performs a process of forming an image on paper based on an input job. The image reading device 40 reads an image formed on paper by the image forming device 10 (hereinafter, also referred to as “output image”), and supplies the reading information to the image forming device 10. The relay transfer device 50 is used to ensure the productivity of the post-processing in the post-processing device 60 with respect to the productivity of the image forming device 10 that performs the image forming processing at high speed. The post-processing device 60 performs a predetermined post-processing on the conveyed paper.

The image forming apparatus 10 is connected to the client terminal so as to be able to communicate with each other via a network (not shown) such as a LAN. For example, a personal computer is applied to the client terminal. The client terminal generates input image data (print data) to be printed by a document creation or image creation application based on a user's input operation. Further, the client terminal has a function of generating a print job including print data and print setting information (also referred to as “job ticket”) and outputting the print job to the image forming apparatus 10.

In the image forming system 1, paper can be conveyed between the image forming apparatus 10, the image reading device 40, the relay conveying device 50, and the post-processing apparatus 60, and can communicate with each other via a wired LAN or a dedicated line. Has been done. The image reading device 40, the relay transfer device 50, and the post-processing device 60 perform in-line processing in synchronization with the image forming device 10.

As an example, the image forming apparatus 10 includes an operation panel 20, a document reading unit 30, a plurality of paper feed trays 121, a paper conveying unit 120, an image forming unit 11, and a fixing device 12. The operation panel 20 is configured such that a display unit such as a display panel and an operation unit such as a touch panel are overlapped with each other, so that an operator can input instructions and display information. The user sets a document in the document scanning unit 30, designates a desired image forming mode from the operation panel 20, and instructs the start of printing.

When the image forming apparatus 10 receives the instruction to start printing, the document is sent from the document reading unit 30 to the reading surface 31 of the image reading unit 30, and the document is read by the reading surface 31 to generate scanned image data. The image forming apparatus 10 feeds the paper designated by the job from the paper feed tray 121 to the paper conveying unit 120, and the image forming unit 11 forms a toner image based on the scanned image data.

An image forming unit 11 is provided in the middle of the paper conveying unit 120. For example, the image forming unit 11 includes an image forming unit including an exposure unit (not shown), a developing unit, a photoconductor drum, a transfer unit, and the like, and can form a toner image on paper. Alternatively, the image forming apparatus 10 forms a toner image on the paper by the image forming unit 11 based on the image data of the job instructed from the client terminal or the like. Then, the image forming apparatus 10 fixes the toner image on the paper by the fixing device 12, and then conveys the paper to the image reading device 40. The image forming unit may correspond to a plurality of colors (cyan, magenta, yellow, black, etc.).

A fuser 12 on which the paper on which the toner image is formed is conveyed is arranged on the downstream side (also simply referred to as “downstream side”) of the image forming unit 11 in the paper conveying direction. The fuser 12 fixes the toner image transferred to the surface side of the paper by pressurizing and heating the paper to be conveyed. The paper to which the fixing process has been performed is transported to the image reading device 40 by the paper transport unit 120 or to the reverse transport unit 130.

The paper transport unit 120 is connected to a reverse transport unit 130 that branches on the downstream side of the fuser 12 and joins the paper transport unit 120 on the upstream side of the image forming unit 11. The reversing transport unit 130 is provided with a reversing unit 131 that inverts the paper and returns the paper to the paper transport unit 120. The paper whose front and back or front and back are inverted by the reversing unit 131 is conveyed to the paper transport unit 120 on the upstream side of the image forming unit 11 or the paper transport unit 120 on the downstream side of the fixing device 12 through the reversing transport unit 130. Then, the paper is ejected from the image forming apparatus 10 and then carried into the image reading apparatus 40.

The image reading device 40 is a device that reads an image formed on the paper conveyed from the image forming device 10. The image reading device 40 is arranged below the first reading unit 41 (an example of the image reading unit), which is a top surface scanner arranged above the transport path (paper transport section 430) on which the paper is conveyed, and below the transport path. A second reading unit 42 (an example of an image reading unit), which is a bottom surface scanner, is provided. The first reading unit 41 optically scans the upper surface of the paper conveyed from the image forming apparatus 10 to read the information (output image) on the upper surface, and generates the scanned image data as the reading information. Further, the second reading unit 42 optically scans the lower surface of the conveyed paper to read the information (output image) on the lower surface and generate the scanned image data. The generated scanned image data is sent to the control unit 100.

The relay transfer device 50 is a device that relays the paper transferred from the image reading device 40 and transfers it to the post-processing device 60, and includes a two-sheet stacking unit 55 and a purge tray 51 (an example of a paper ejection unit). The relay transfer device 50 has a straight transfer function, a purge tray paper ejection function, and a reverse transfer function. In the straight transfer function, the first sheet transfer unit 530 transfers the paper straight from the front-stage device (image reading device 40 in FIG. 3) to the rear-stage device (post-processing device 60 in FIG. 3). The purge tray ejection function ejects the paper conveyed from the pre-stage device to the first paper transport unit 530 to the purge tray 51 via the second paper transport unit 540. Paper with defective images that is not conveyed to the post-processing device 60 is ejected to the purge tray 51.

The reverse transfer function includes a function for stacking two introduced sheets and ejecting them at the same time (stacking transfer function), and a function for ejecting only one of the two introduced sheets, which was introduced earlier (a function for ejecting only one sheet). There is an individual transport function). In the present specification, the temporary holding of the paper into which the two-sheet stacking portion 55 (stack portion 532) is introduced may be referred to as “stack”. The function of ejecting two stacked sheets one by one is a function that has never existed before. By transporting the paper conveyed from the image reading device 40 to the post-processing device 60 via the two-sheet stacking unit 55, the second sheet of paper is introduced into the two-sheet stacking unit 55 (two sheets). Until the second sheet of paper is ejected (when the sheets are not stacked and ejected), until the determination of the image defect of the sheet based on the reading information of the image reading device 40 by the control unit 100 (FIG. 4) is completed. Time Tw (waitable time) can be secured.

The post-processing device 60 is a device that performs post-processing on the paper conveyed from the relay transfer device 50, and includes a post-processing unit 65, a paper discharge tray 61, and a sub tray 62. The post-processing device 60 has a straight transfer function (first paper transfer path 630), a sub-tray paper discharge function (second paper transfer path 640, sub-tray 62), and a post-processing function (post-processing unit 65). The post-processing unit 65 can perform post-processing on a plurality of sheets of paper at the same time. The post-processing unit 65 has, for example, a punch function for punching holes at predetermined positions on paper, a folding function such as middle folding and Z folding, and a binding function. In the binding function, the saddle stitch booklet, which is saddle stitched paper, is ejected.

The overall configuration of the image forming system 1 is not limited to this in the present invention. As an example, the first reading unit 41 and the second reading unit 42 of the image reading device 40 may be provided on the downstream side of the fixing device 12 in the image forming device 10. For example, the first reading unit 41 and the second reading unit 42 are provided between the branch point from the paper transport unit 120 to the reverse transport unit 130 and the discharge port of the image forming apparatus 10.

Further, although the relay transfer device 50 includes a purge tray 51, a sub tray of the post-processing device 60 or another tray (not shown) may be used as the purge tray. Since the waitable time Tw can be secured by providing the double-layered portion 55 of the present embodiment, the purge tray can be provided in the relay transfer device 50.

[Control system of image formation system]
Next, the control system of each device constituting the image forming system 1 will be described.
FIG. 4 is a block diagram showing an example of a control system of each device constituting the image forming system 1.

(Image forming device)
The image forming apparatus 10 includes an operation panel 20, a document reading unit 30, an image forming unit 11, a fixing device 12, a control unit 100, a communication unit 110, a paper transfer unit 120, a reverse transfer unit 130, an external communication unit 140, and a memory 150. Have.

The control unit 100 controls the operation of each unit in the image forming apparatus 10, and also instructs the image reading device 40, the relay transfer device 50, and the post-processing device 2 to operate. The communication unit 110 transmits and receives data to and from the image reading device 40. The paper transport unit 120 is a mechanism including a paper feed roller (not shown) that takes out the paper from the paper feed tray 121 and feeds the paper, and a transport roller (not shown) that transports the paper to the subsequent device (image reading device 40). Is. The reversing transport unit 130 is provided with a reversing unit 131, and is a mechanism for reversing the paper transported from the downstream side of the paper transport unit 120 and then returning the paper to the upstream side of the paper transport unit 120. The external communication unit 140 transmits and receives data to and from an external device (client terminal, mobile terminal such as a management device server, etc.) of the image forming system 1.

The memory 150 is a volatile memory such as RAM or a large-capacity non-volatile memory. The memory 150 stores the image formation mode (print setting information) instructed via the operation panel 20 and the scanned image data read by the document scanning unit 30 in association with each other.

The control unit 100 determines whether the paper is normal / abnormal from the reading information of the image reading device 40, and based on the determination result, the first paper transport unit 530, the second paper transport unit 540, and the two-sheet stacking unit of the relay transfer device 50. The paper transport operation by the unit 55 is controlled.

(Image reader)
The image reading device 40 includes a control unit 400, a communication unit 410, 420, a paper transport unit 430, a first reading unit 41, a second reading unit 42, and a memory 440.

The control unit 400 controls the operation of each unit in the image reading device 40 based on the instruction of the control unit 100 of the image forming apparatus 10. The communication unit 410 transmits and receives data to and from the image forming apparatus 10, and the communication unit 420 transmits and receives data to and from the relay carrier device 50. The paper transport unit 430 includes a transport roller (not shown), receives paper from the front stage device (image forming device 10), and transports the paper to the rear stage device (relay transfer device 50).

(Relay transfer device)
The relay transfer device 50 includes a control unit 500, a communication unit 510, 520, a first paper transfer unit 530, a second paper transfer unit 540, a two-sheet stacking unit 55, a paper detection sensor 560, and a memory 550.

The control unit 500 controls the operation of each unit in the relay transfer device 50 based on the instruction of the control unit 100 of the image forming apparatus 10. The communication unit 510 transmits and receives data with the image reading device 40, and the communication unit 520 transmits and receives data with the post-processing device 60. The first paper transport unit 530 and the second paper transport unit 540 include transport rollers (not shown). The first paper transport unit 530 receives the paper from the front stage device (image reading device 40) and transports the paper straight to the rear stage device (post-processing device 60). The second paper transport unit 540 receives paper from the front-stage device via the first paper transport unit 530 or the two-sheet stacking unit 55, and transports the paper to the purge tray 51.

The two-sheet stacking unit 55 performs a two-sheet stacking operation, two-sheet stacking discharge, one-sheet ejection, and the like under the control of the control unit 500 instructed by the control unit 100. The paper detection sensor 560 is provided near the confluence of the first paper transport unit 530 and the discharge transport unit 533, and outputs a detection signal (detection result) according to the presence or absence of paper. The paper detection sensor 560 transmits information on whether or not the paper has passed a predetermined position of the first paper transport unit 530 to the control unit 500.

(Post-processing device)
The post-processing device 60 includes a control unit 600, a communication unit 610, 620, a first paper transport unit 630, a second paper transport unit 640, a memory 650, and a post-processing unit 65.

The control unit 600 controls the operation of each unit in the post-processing device 60 based on the instruction of the control unit 100 of the image forming apparatus 10. The communication unit 610 transmits and receives data to and from the relay carrier 50, and the communication unit 620 transmits and receives data to and from the latter stage device when the latter stage device is connected. The first paper transport unit 630 and the second paper transport unit 640 include transport rollers (not shown). The first paper transport unit 630 receives the paper from the front-stage device (relay transport device 50) and transports the paper straight to the output tray 61. The second paper transport unit 640 receives the paper from the first paper transport unit 630 and discharges the paper to the sub tray 62. The post-processing unit 65 performs a predetermined post-processing on the conveyed paper based on the instruction of the control unit 600.

The image forming device 10, the image reading device 40, the relay transfer device 50, and the post-processing device 60 transmit and receive each other's status information via the communication unit of each device. The control unit of each device outputs the information of its own device as status information to other devices. The status information includes, for example, information such as the operating status of each device, the presence / absence of an abnormality, and the content of the abnormality. The operating state of the apparatus is, for example, process information, and includes information such as which page of the job is currently being fed and printed by the image forming apparatus 10. The image forming apparatus 10 acquires the status information of each apparatus at any time, and reflects the status information of each apparatus in the instruction to each apparatus.

[Function of image forming device]
Next, the function of the control unit 100 of the image forming apparatus 10 will be described.
FIG. 5 is a block diagram showing a functional example of the control unit 100 of the image forming apparatus 10.

The control unit 100 includes an image defect detection unit 101 and a paper transport control unit 102.
The image defect detection unit 101 performs a process of detecting an image defect of the paper by image processing from the reading information of the first reading unit 41 and / or the second reading unit 42, and determines whether the paper is normal / abnormal based on the detection result. judge. Then, the image defect detection unit 101 supplies the normal / abnormal determination result of the paper to the paper transport control unit 102.

The paper transfer control unit 102 generates a control signal based on the determination result of the image defect detection unit 101 and the process information, and the first paper transfer unit 530, the second paper transfer unit 540, and the two-sheet stacking unit of the relay transfer device 50. The operation of the unit 55 is controlled. For example, when the determination result is abnormal on the paper, the paper transport control unit 102 stops the operation of forming an image on the paper, and the transport path (first) during transport between the page determined to be abnormal and the subsequent pages. It is controlled so that a part or all of the paper (remaining paper) remaining in the paper transport unit 530) is discharged to the purge tray 51 as spoiled paper.

[Transfer mechanism of relay transfer device]
Next, the transport mechanism of the relay transport device 50 will be described.
FIG. 6 is an explanatory diagram showing an example of a transport mechanism of the relay transport device 50.

In the relay transfer device 50, paper is introduced from the first paper transfer unit 530 via the introduction transfer unit 531 and the introduced (stacked) paper is introduced into the first paper transfer unit 530 via the discharge transfer unit 533. A double-layered portion 55 for discharging to the downstream side of the portion is provided. The two-sheet stacking portion 55 includes a stack portion 532, a first guide member 534, a second guide member 535, a vertical matching plate 536, and a refeed roller 537.

The stack portion 532 of the two-sheet stacking unit 55 is, for example, a hollow member arranged in the vertical direction, and stacks up to two sheets of paper introduced from the first paper transport unit 530 with the rear end facing upward. It is configured to be possible.

The first guide member 534 has a curved shape as an example, and is provided near a branch point (introduction portion) where paper is introduced from the first paper transport portion 530 to the stack portion 532. The first guide member 534 is switched between a straight transport position in which the first paper transport section 530 transports straight and an introduction position in which the paper is introduced into the stack section 532. When the first guide member 534 is in the straight transport position indicated by the broken line, the paper transported through the first paper transport section 530 is conveyed straight without passing through the two-sheet stacking section 55. On the other hand, when the first guide member 534 is in the introduction position shown by the solid line, the paper conveyed through the first paper transfer unit 530 is guided by the introduction transfer unit 531 and introduced into the stack unit 532.

The second guide member 535 has a curved shape as an example, and is provided near the branch point between the introduction transport portion 531 and the discharge transport portion 533 at the upper end of the stack portion 532. The position of the second guide member 535 is switched between the introduction position for introducing the paper and the ejection position for ejecting the paper, thereby partitioning the upper ends of the first and second sheets of paper. It is configured so that it can be done.

When the second guide member 535 is on the left side (introduction position) shown by the solid line, the introduction transfer section 531 and the stack section 532 are in a state where paper can be passed and the discharge transfer section 533 is closed. .. As a result, when the second guide member 535 is in the introduction position, the paper conveyed to the introduction transfer section 531 is introduced into the stack section 532.

Further, when the second guide member 535 is on the left side (discharge position) indicated by the wavy line, the discharge transfer unit 533 and the stack unit 532 are in a state where paper can be passed and the introduction transfer unit 531 is closed. Will be. As a result, when the second guide member 535 is in the ejection position, the paper stacked in the stack portion 532 is guided to the ejection transport unit 533 and ejected in cooperation with the vertical matching plate 536.

The vertical matching plate 536 is arranged near the lower end of the stack portion 532, and is configured to be movable at least three positions in the vertical direction by a drive mechanism (not shown). The first position is a position A that supports the paper introduced into the stack portion 532 so that the upper end of the paper is below the second guide member 535. The second position is higher than the first position, and is a position B such that the upper end of the paper introduced into the stack portion 532 is above the second guide member 535 and below the refeed roller 537. .. Further, the third position is a position where the upper end of the paper introduced into the stack portion 532 abuts on the refeed roller 537.

The refeed roller 537 is a pair of rollers that convey the paper stacked in the stack unit 532. The re-feeding roller 537 is arranged above the second guide member 535 and below the transport roller provided in the introduction transport unit 531 (position close to the second guide member 535). Only the re-feeding roller 537 is expressed as if the two rollers constituting the roller pair are in contact with each other. do.

Further, a discharge switching unit 541 is provided near the branch point between the first paper transport unit 530 and the second paper transport unit 540. The discharge switching unit 541 discharges the normal discharge position for transporting the paper to the post-processing device 60 or the paper to the purge tray 51 under the control of the control unit 500 in response to the instruction from the control unit 100 of the image forming apparatus 10. Can be switched to the abnormal discharge position.

[Two-sheet stack operation]
Next, the two-sheet stack operation of the relay transfer device 50 having the above configuration will be described.
FIG. 7 is a flowchart showing a procedure example of the two-sheet stack operation of the relay transfer device 50.
FIG. 8 is an explanatory diagram when two sheets of paper are stacked on the two-sheet stacking portion 55 of the relay transfer device 50.

In FIG. 7, first, after the job is started, the control unit 100 of the image forming apparatus 10 determines that the paper should be introduced from the first paper transport unit 530 to the stack unit 532 of the two-sheet stacking unit 55, and the paper to be introduced. Is determined whether or not is the first sheet (S1). Then, when the paper to be introduced is the first sheet (YES in S1), the control unit 100 switches the position of the second guide member 535 to the left side (introduction position) (S2). At this time, the position of the first guide member 534 is also the introduction position. In the following description, the description of the position of the first guide member 434 will be omitted.

Next, the control unit 100 moves the vertical matching plate 536 to the position A (S3), and introduces the paper P1 sent out from the paper feed tray 121 into the stack unit 532 (S4, FIG. 8A). Next, the control unit 100 switches the second guide member 535 to the right side (discharge position) (S5), then raises the vertical matching plate 536 to move to the position B (S6, FIG. 8B), and determines in step S1. Proceed to processing.

Next, in step S1, the control unit 100 determines whether or not the sheet to be introduced is the first sheet (S1). Then, when the paper to be introduced is not the first sheet, that is, the second sheet (NO in S1), the control unit 100 switches the position of the second guide member 535 to the left side (introduction position) (S7). , Paper P2 is introduced into the stack portion 532 (S8, FIG. 8C). When the process of step S8 is completed, two sheets of paper P1 and P2 are stacked in the stacking unit 532, and the two-sheet stacking operation is completed.

In the following description, when two sheets of paper are stacked in the stack portion 532, the previously introduced paper such as paper P1 is referred to as the “first sheet”, and the later introduced paper such as paper P2 is used. It is called "the second piece".

[Two-sheet stacking discharge]
Next, the double-layered discharge of the relay transport device 50 will be described.
FIG. 9 is a flowchart showing a procedure example of double-layered ejection of the relay transfer device 50.
FIG. 10 is an explanatory diagram when two sheets of paper are ejected from the two-sheet stacking portion 55 of the relay transfer device 50.

In FIG. 9, first, the control unit 100 of the image forming apparatus 10 moves the vertical matching plate 536 from the position B shown in FIG. 8C to the position A after the stacking of the two sheets is completed (S11). Next, the control unit 100 switches the position of the second guide member 535 to the right side (discharge position) (S12, FIG. 10). After that, the control unit 100 moves the vertical matching plate 536 to a position where the upper ends of the two sheets P1 and P2 abut against the refeed roller 537, and drives the refeed roller 537 to eject the two sheets. (S13). Then, when the lower ends of the two sheets P1 and P2 pass through the refeed roller 537, the ejection of the two sheets P1 and P2 is completed.

In this way, when the control unit 100 stacks the two sheets P1 and P2 stacked on the stack unit 532 and ejects them, the control unit 100 moves the vertical matching plate 536 to the position A and then ejects the second guide member 535 before ejecting. Is moved to the introduction position, and then the second guide member 535 is switched to the discharge position. After that, the control unit 100 moves the vertical matching plate 536 to abut the two sheets P1 and P2 against the refeed roller 537 and ejects them.

[Discharge only one sheet]
Next, only one piece of the relay transfer device 50 will be discharged.
FIG. 11 is a flowchart showing an example of a procedure for discharging only one piece of the relay transfer device 50.
FIG. 12 is an explanatory diagram when one sheet of paper is ejected from the two-sheet stacking portion 55 of the relay transfer device 50.

In FIG. 11, first, the control unit 100 of the image forming apparatus 10 switches the position of the second guide member 535 to the left side (introduction position) after the two-sheet stack is completed (S21). Actually, as shown in FIG. 8C, when the stack of two sheets is completed, the position of the second guide member 535 is at the introduction position, so that the control unit 100 does not instruct anything. After that, the control unit 100 moves the vertical matching plate 536 to a position where the upper end of the first sheet of paper P1 abuts on the refeed roller 537 (FIG. 12), and drives the refeed roller 537 to drive the first sheet. Paper P1 is ejected (S22). Then, when the lower end of the first sheet of paper P1 passes through the refeed roller 537, the ejection of the first sheet of paper P1 is completed.

In this way, when the control unit 100 ejects only one of the two sheets P1 and P2 stacked in the stack unit 532, the control unit 100 is the first from the state when the second sheet is stacked in the stack unit 532. 2 Move the guide member 535 to the introduction position. Then, the control unit 100 moves the vertical matching plate 536 while partitioning the upper ends of the first and second sheets P1 and P2 by the second guide member 535, and re-feeds only the first sheet P1. It hits the roller 537 and is discharged.

[Operation at the time of 1-page job]
Next, when the number of pages of the job is one, the relay transfer device 50 introduces two sheets of paper into the two-sheet stacking unit 55, and then ejects the sheets one by one to the two-sheet stacking unit 55. The operation of introducing the paper of the above will be described. The process of printing a plurality of pages when the number of pages of a job is one corresponds to, for example, a case where a job of one page is repeated a plurality of times and a plurality of copies of one page are printed.

In FIG. 13, when the number of pages of a job is one, two sheets of paper are introduced into the two-sheet stacking portion 55, and then the next sheet is introduced while discharging one sheet to the post-processing device 60. It is explanatory drawing about operation.
In FIG. 14, when the number of pages of a job is one, one sheet of paper is introduced into the two-sheet stacking portion 55, one sheet of paper is ejected to the post-processing device 60, and then one sheet of paper is taken. It is explanatory drawing of the operation which introduces the next paper while discharging to a purge tray 51.

First, the control unit 100 switches the second guide member 535 to the left side (introduction position) and introduces the paper P1 into the stack unit 532 (FIG. 13A). At this time, the control unit 100 determines the image defect of the introduced paper when the paper is introduced. In FIG. 13A, the image defect determination result of the introduced paper P1 is no image defect. In the following description, no image defect (normal) is referred to as "OK", and image defect present (abnormal) is referred to as "NG". (1) shown in FIG. 13A represents the first sheet, and (2) represents the second sheet. Currently, the first sheet is "NG" and the second sheet is not introduced, so it is described as "None". In the following description, the description of the position and movement of the second guide member 535 and the vertical matching plate 536 will be omitted.

Next, the control unit 100 moves the second guide member 535 and the vertical matching plate 536, and introduces the paper P2 into the stack unit 532 (FIG. 13B). At this time, the image defect determination result of the paper P2 by the control unit 100 is that there is an image defect (NG). The two-sheet stacking operation of FIGS. 13A and 13B is performed by the procedure of the two-sheet stacking operation shown in FIG. 7.

Next, the control unit 100 ejects only the normal paper P1 to the post-processing device 60 (FIG. 13C) while leaving the two sheets P2 in the stacking unit 55 (FIG. 13C), and two sheets of the next paper P3 to the stacking unit 532. Introduced as an eye (Fig. 13D). The operation of ejecting one sheet of paper in FIG. 13C is performed by the procedure of ejecting only one sheet shown in FIG. Here, as shown in FIG. 13D, the control unit 100 lowers the vertical alignment plate 536 while ejecting the paper P1 to move to the position A, and then switches the second guide member 535 to the right side (discharging position). After that, the control unit 100 raises the vertical matching plate 536 and moves to the position B while continuing to eject the paper P1 (FIG. 14E). In this state, the upper end of the paper P2 does not abut on the refeed roller 537, and the upper end of the paper P2 is partitioned to the discharge side by the second guide member 535. This state is the same as the state when the second sheet of paper shown in FIG. 8C is introduced.

In this state, the paper P3 is transported from the first paper transport unit 530 to the introduction transport unit 531 to introduce the paper P3 into the stack unit 532 (FIG. 14E). After that, since the paper P2 is NG paper, the control unit 100 controls the two-sheet stacking unit 55, the discharge switching unit 541, and the second paper transport unit 540, and discharges the paper P2 to the purge tray 51. Then, the control unit 100 introduces the next paper P4 into the stack unit 532 as the second sheet while discharging the paper P2 to the purge tray 51 (FIG. 14F).

<2. Second embodiment>
The second embodiment describes an example of processing when an image defect occurs and after the job is restarted when the number of pages of the job is two or more.

FIG. 15 is an explanatory diagram showing a unit of the spoiled paper suppression control process according to the second embodiment.
As shown in FIG. 15, in the present embodiment, the control unit 100 basically performs a spoiled paper suppression control process after the printing process, using two sheets (two pages) stacked on the stack unit 532 as a unit. For example, the paper ejection process is performed according to the image defect determination result of the papers P1 and P2 stacked first in the stack unit 532, and then the paper is ejected according to the image defect determination result of the papers P2 and P3 stacked in the stack unit 532. Controls such as performing discharge processing are repeated until the end of the job. At this time, when the spoiled paper is detected, the control unit 100 executes the spoiled paper suppression control process. For example, when two sheets of paper P2 and P3 are stacked and ejected, the paper ejection process is then performed according to the image defect determination result of the papers P4 and P5.

[Operation for multi-page jobs]
FIG. 16 is an explanatory diagram showing an example of processing when an image defect occurs and after the job is restarted when the number of pages of the job according to the second embodiment is two or more.
FIG. 17 is an explanatory diagram showing an operation example of the relay transfer device 50 according to the second embodiment after the job is restarted.

FIG. 16A shows a process (process when NG occurs) when an image defect is detected on the paper. The example of the job shown in FIG. 16A is an example of a job including the printing process of page 7. The image defect determination result of each sheet of this job is that the sheet P1 is normal (no image defect), the sheet P2 and the sheet P3 are abnormal (there is an image defect), and the sheets P4 to P6 are normal. The paper P7 has been fed when the job is paused, but the image is not formed.

In FIG. 16A, after the job starts, the control unit 100 introduces the papers P1 and P2 into the stack unit 532, first conveys only the normal paper P1 to the post-processing device 60 (normally ejects), and then ejects the paper P3. It is introduced as the second sheet to the stack portion 532. Since the papers P2 and P3 are abnormal, the control unit 100 temporarily suspends the image forming process by the image forming unit 11, stacks two sheets of the papers P2 and P3, and discharges them from the stacking unit 532 to the purge tray 51. Next, the control unit 100 introduces the papers P4 and P5 into the stack unit 532. Here, since the control unit 100 stacks the papers P4 and P5 on the stacking unit 532 because the image defect determination result of the papers P4 and P5 is normal and after it is determined to be abnormal (of the papers P2 and P3). do.

Here, it is assumed that the image-formed paper P6 remains in the image forming apparatus 10 or the image reading apparatus 40, and the paper P6 is normal. However, the papers P4 and P5 are already stacked in the stack unit 532, and normal paper P6 cannot be introduced into the stack unit 532. Therefore, the control unit 100 transports the paper P6 straight by the first paper transport unit 530 and discharges the paper P6 from the second paper transport unit 540 to the purge tray 51. Further, the control unit 100 leaves the paper P7, which has been fed and has not formed an image, remaining in the apparatus as it is on the transport path.

Then, the control unit 100 restarts the job from the page where the abnormality first occurs after removing the cause of the abnormality by, for example, image correction processing. In the example of FIG. 16A, the control unit 100 forms an image corresponding to the page of the paper P2 determined to be abnormal on the paper P2', and then forms an image corresponding to the page of the paper P3 on the paper P3'. Then, the control unit 100 transfers the papers P2'and P3'of the image-formed (reprinted) pages straight to the post-processing apparatus 60 by the first paper transport unit 530 (FIG. 17A). After that, the control unit 100 confirms whether or not the paper P3'in which the page finally determined to be abnormal by the paper detection sensor 560 is reprinted has passed through the ejection unit of the two-sheet stacking unit 55. For example, the paper passage may be determined based on whether or not the set time has elapsed since the passage of the rear end of the paper was detected or the passage of the front edge of the paper was detected. Then, when the control unit 100 confirms that the paper P3'has passed through the ejection unit of the two-sheet stacking unit 55, the control unit 100 stacks two normal sheets P4 and P5 stacked on the stacking unit 532. It is transported to the post-processing device 60 and inserted into the restart job (FIG. 17B).

Further, the control unit 100 forms an image corresponding to the page of the paper P6, which was normal but was discharged to the purge tray 51, on the paper P6'and introduces the image into the stack unit 532. Next, an image is formed on the paper P7 for which the image has not been formed when the job is paused, and the image is introduced into the stack portion 532 as the second sheet. Then, if the paper P6'and the paper P7 are normal, the control unit 100 stacks two sheets of the paper P6'and the paper P7 and conveys them to the post-processing apparatus 60.

As described above, when the control unit 100 determines that the first sheet of paper (first sheet) stacked in the stacking unit 532 is abnormal, the control unit 100 transfers the first sheet of paper determined to be abnormal to the purge tray 51. After ejecting, if the subsequent image-formed paper is normal, up to two sheets are stacked on the stack portion 532, and the subsequent image-formed paper (paper P6 in FIG. 16) is passed through the two-sheet stacking portion 55. It is discharged to the purge tray 51 without being discharged.

After that, the control unit 100 restarts the job from the page first determined to be abnormal. After resuming the job, the control unit 100 sequentially uses images of pages other than the pages of the two sheets of paper until the pages of the two sheets of paper (papers P4 and P5 in FIG. 16B) stacked on the stacking unit 532 are reached. The sheets are formed and conveyed to the post-processing device 60 without passing through the two-sheet stacking portion 55. At this time, the control unit 100 transfers the paper (for example, paper P2', P3') of the page on which the image is formed again to the relay transfer device 50 after being inverted by the reverse transfer unit 130. Then, the control unit 100 inserts the two sheets stacked in the stack unit 532 between the corresponding pages of the restarted job, and introduces the next sheet into the stack unit 532.

<3. Third Embodiment>
Next, as a third embodiment, a procedure example of the spoilage paper suppression control process of the relay transfer device 50 in which the first embodiment and the second embodiment are combined will be described.
[Procedure for spoilage paper suppression control processing]
FIG. 18 is a flowchart showing a procedure example of the spoilage paper suppression control process of the relay transfer device 50 in which the first embodiment and the second embodiment are combined. This flowchart shows the spoiled paper suppression control process of the first embodiment and the second embodiment in an integrated manner. The image defect determination result of the paper described on the left shoulder of each processing step in FIG. 18 shows the information stored in the memory 150 immediately before the execution of each processing step referred to by the control unit 100. If one of the two stacked sheets of paper is ejected and the later-introduced paper is moved to the position of the earlier-introduced paper in the stack portion 532, the corresponding paper is used. The information is rewritten from "(2) OK" to "(1) OK". The control unit 100 controls the operations of the relay transfer device 50, the image forming device 10, the image reading device 40, and the post-processing device 60 based on the information of the image defect determination result of the paper stored in the memory 150.

First, the control unit 100 introduces the first sheet of paper into the two-sheet stacking unit 55 (stack unit 532) (S31). Next, the control unit 100 determines the image defect of the introduction paper (S32). If the introduction paper is abnormal (NG in S32), the control unit 100 introduces the next paper into the two-sheet stacking unit 55 (S33) while ejecting the introduction paper to the purge tray 51, and then in step S32. Proceed to processing. As described above, when the paper previously introduced into the two-sheet stacking unit 55 is abnormal after the job is started, the control unit 100 discharges the paper determined to be abnormal to the purge tray 51 and new paper. Is repeated in the process of introducing the two sheets into the stacking portion 55.

On the other hand, when the introduction paper is normal (OK in S32), the control unit 100 introduces the next paper into the two-sheet stacking unit 55 as the second sheet (S34). Next, the control unit 100 determines the image defect of the introduction paper (S35). Here, when the introduction paper is normal (OK in S35), the information [(1) OK, (2) OK] that the first sheet is OK and the second sheet is OK by the control unit 100 is stored in the memory 150. Written in. Next, the control unit 100 determines whether or not the job being executed is a job with a plurality of pages and there is a history (NG occurrence history) determined to be abnormal in the same job (S36).

If the determination process in step S36 is not a multi-page job, or if there is no NG occurrence history in the same job (NO in S36), the control unit 100 stacks two OK paper sheets and conveys them to the post-processing device 60. While doing so, the next sheet is introduced into the two-sheet stacking portion 55 (S37), and then the process proceeds to step S32. On the other hand, if the job is a plurality of pages and there is an NG occurrence history in the same job (YES in S36), the control unit 100 proceeds to the process of step S42 (job pause process).

If the introduction paper is abnormal in the determination process of step S35 (NG in S35), the information stored in the memory 150 is [(1) OK, (2) NG]. The control unit 100 stacks two sheets of the next sheet while leaving only the second sheet (introduction sheet) in the two-sheet stacking unit 55 and transporting only the first normal sheet to the post-processing device 60. It is introduced into the section 55 as a second sheet (S38).

Next, the control unit 100 determines the image defect of the introduction paper (S39). If the introduction paper is normal (OK in S39), the information stored in the memory 150 is [(1) NG, (2) OK]. The control unit 100 ejects only the first abnormal paper to the purge tray 51 while leaving the second sheet (introduction paper) in the two-sheet stacking unit 55, while discharging the next sheet to the two-sheet stacking unit 55. Introduced as the second sheet (S40).

Next, the control unit 100 determines the image defect of the introduction paper (S41). If the introduction paper is abnormal (NG in S41), the information stored in the memory 150 becomes [(1) OK, (2) NG], and the control unit 100 proceeds to the process of step S38 (combiner). A). On the other hand, when the introduction paper is normal (OK in S41), the information stored in the memory 150 becomes [(1) OK, (2) OK], and the control unit 100 forms an image by the image forming unit 11. Pause the process (job). Then, when the job is temporarily stopped, the control unit 100 holds two OK papers in the two-sheet stacking unit 55, and the subsequent image-formed paper remaining in the apparatus is straightened by the first paper transport unit 530. It is conveyed through the path and is discharged to the purge tray 51 by the discharge switching unit 541 and the second paper transport unit 540 (S42). After that, the control unit 100 restarts the job when the conditions for restarting the job such as the image correction process are satisfied. The process after resuming the job will be described in detail with reference to FIG. 19 described later.

If the introduction paper is abnormal in the determination process of step S39 (NG in S39), the information stored in the memory 150 becomes [(1) NG, (2) NG], and the control unit 100 is executing. It is determined whether or not the job is a one-page job (S43). In the case of a one-page job (YES in S43), the control unit 100 leaves only the second sheet (introduction sheet) in the two-sheet stacking unit 55, and only the first abnormal sheet is purged in the purge tray 51. The next sheet is introduced into the two-sheet stacking portion 55 as the second sheet (S44), and then the process proceeds to step S39.

If the determination process in step S43 is not a one-page job (NO in S43), the control unit 100 stacks two OK papers and ejects them to the purge tray 51, and introduces the next paper into the two-sheet stacking unit 55. (S45), and then proceed to the process of step S32.

In the above flowchart, when the determination of the abnormality of the paper introduced in the two-sheet stacking unit 55 occurs continuously for a predetermined number of times, the control unit 100 stops the image forming process by the image forming unit 11 and gives a warning. Output. Examples of the warning method include displaying an error message (for example, "contact a service person") on the operation panel 20, turning on or blinking the indicator lamp, and notifying by voice.

In the above flowchart, the combination of OK and NG is 2 such that the first sheet of paper introduced in the two-sheet stacking portion 55 is OK and the second sheet is NG [(1) OK, (2) NG]. A warning may be output even if it continues more than once. If [(1) OK, (2) NG] continues twice and no warning is output, the paper is ejected from the two-sheet stacking portion 55 as follows. As a premise, it is assumed that the papers P1 to P4 are (1) OK, (2) NG, (3) OK, and (4) NG. In this case, after the papers P1 and P2 are introduced into the two-sheet stacking portion 55, the papers P1 are conveyed to the post-processing device 60, and the papers P2 are discharged to the purge tray 51. After that, the job is temporarily stopped, but since the paper P3 (OK paper) cannot be ejected from the two-sheet stacking portion 55 until after the paper P2 (NG paper) is reprinted, the two-sheet stacking portion 55 Papers P3 and P4 are stacked on the paper. Then, after resuming the job, the paper P2 is reprinted and straight-conveyed, the paper P3 is discharged from the two-sheet stacking portion 55 to the post-processing device 60, and then the paper P4 (NG paper) is discharged to the purge tray 51.

In this way, the control unit 100 of the image forming apparatus 10 follows the first sheet and the first sheet introduced in the two-sheet stacking unit 55 when the job of one page is executed a plurality of times in succession. When it is determined that both of the second sheets introduced in the above-mentioned manner are normal, the next sheet is transferred from the two-sheet stacking unit 55 while stacking the first sheet and the second sheet to the post-processing apparatus 60. It is introduced into the two-sheet stacking portion 55 [(1) OK, (2) OK].
Further, when the control unit 100 determines that the first sheet introduced into the two-sheet stacking unit 55 is normal and the second sheet is abnormal, the two-sheet stacking unit 55 determines that the first sheet is normal. While transporting only the paper of 1 to the post-processing apparatus 60, the next paper is introduced into the two-sheet stacking portion 55 as the second sheet [(1) OK, (2) NG].
Further, when the control unit 100 determines that the first sheet introduced into the two-sheet stacking unit 55 is abnormal, only the first sheet determined to be abnormal from the two-sheet stacking unit 55 is purged in the purge tray 51. The next sheet is introduced into the two-sheet stacking portion 55 as the second sheet while being discharged to [(1) NG, (2) OK or NG].

Further, the control unit 100 of the image forming apparatus 10 has a first sheet introduced in the two-sheet stacking unit 55 and a second sheet introduced following the first sheet when executing a job of a plurality of pages. When it is determined that both the sheets are normal, the first sheet and the second sheet determined to be normal are stacked from the two-sheet stacking unit 55 and conveyed to the post-processing apparatus 60 [(1) OK, (2). ) OK].
Further, when the control unit 100 determines that the first sheet introduced into the two-sheet stacking unit 55 is normal and the second sheet is abnormal, the two-sheet stacking unit 55 determines that the first sheet is normal. While transporting only the paper of 1 to the post-processing apparatus 60, the next paper is introduced into the two-sheet stacking portion 55 as the second sheet [(1) OK, (2) NG].
Further, when the control unit 100 determines that the first sheet introduced into the two-sheet stacking unit 55 is abnormal and the second sheet is normal, the two-sheet stacking unit 55 determines that the first sheet is abnormal. While transporting only the paper of No. 1 to the purge tray 51, the next paper is introduced into the two-sheet stacking portion 55 as the second sheet [(1) NG, (2) OK].
Further, when the control unit 100 determines that both the first sheet and the second sheet introduced into the two-sheet stacking unit 55 are abnormal, the first sheet determined to be abnormal by the two-sheet stacking unit 55. While stacking the paper and the second paper and ejecting them to the purge tray 51, the next paper is introduced into the two-sheet stacking portion 55 [(1) NG, (2) NG].

[Procedure for spoilage paper suppression control processing when resuming a job]
FIG. 19 is a flowchart showing a procedure example of the spoilage paper suppression control process of the relay transfer device 50 at the time of restarting the job according to the first and second embodiments.

First, the control unit 100 restarts the job from the page first determined to be abnormal (S51). More specifically, if there is a page that is determined to be abnormal in succession to that page (paper P3) before the page that was finally determined to be abnormal (paper P3 in FIG. 16A), the oldest corresponding page (paper P3 in FIG. 16A). If there is no page determined to be abnormal from the paper P2) or before the page determined to be abnormal at the end, the job is restarted from that page.

At this time, the control unit 100 may reduce the printing speed to half (1/2) of the normal printing speed. The printing speed, which is half the normal printing speed, is the same as the printing speed (productivity) when printing by skipping one sheet of paper. Further, the control unit 100 does not print the page reserved in the stack unit 532 of the two-sheet stacking unit 55. Further, the control unit 100 widens the paper spacing before and after the page held in the stack unit 532 for insertion (for example, one page). For example, when the papers P4 and P5 are stacked on the stack portion 532 as shown in FIG. 16, the space between the papers P3'and the paper 6'is set by one page. As a result, after the job is restarted, two sheets of paper P4 and paper P5 can be stacked and inserted between the paper P3'and the paper 6'. Therefore, the decrease in productivity can be minimized.

After restarting the job, the control unit 100 re-forms the image of the page (for example, paper P2', P3) by the image forming unit 11 until the page of the paper stacked on the two-sheet stacking unit 55 (for example, paper P4) is reached. ') Is inverted by the inversion transport unit 130 and then conveyed to the post-processing apparatus 60 without passing through the two-sheet stacking unit 55.

Further, the control unit 100 completes the paper abnormality / normality determination process before the paper to be conveyed straight through the two-sheet stacking unit 55 reaches the discharge switching unit 541 for switching the paper ejection destination. It is desirable to control the first paper transport unit 530 to reduce the paper transport speed. Alternatively, the corresponding paper may be stopped on the first paper transport unit 530. This is because the transport path length in the case of straight transport is shorter than that in the case of passing through the two-sheet stacking portion 55, but the paper abnormality / normality determination process is performed by the time the ejection switching unit 541 switches the ejection destination. This is to make it in time.

Next, the control unit 100 determines whether or not the paper of the reprinted page has passed through the stack ejection unit by the paper detection sensor 560 (S52), and the paper of the reprinted page passes through the stack ejection unit. If not (NO in S52), this determination process is continued.

On the other hand, when the paper of the reprinted page has passed through the stack ejection unit (YES in S52), the control unit 100 ejects the paper of the normal page temporarily held in the stack unit 532, and between the papers of the restart job. (S53).

Next, the control unit 100 ejects the paper of the normal page temporarily held in the stack unit 532, and introduces the image-formed paper into the stack unit 532 after the subsequent job is restarted, and sequentially stacks two sheets. Discharge. The two-sheet stacking and discharging process is executed based on the flowchart of FIG.

According to the first to third embodiments described above, by using a conventional relay transfer device having a stacking function so that only one sheet can be ejected, the paper (spoiled paper) determined to be abnormal is ejected. It is possible to suppress an increase in the device width (for example, the image reading device width) for the purpose. Further, when an image defect occurs, up to two normal sheets of normal paper are stacked in the double-sheet stacking portion 55 of the relay transport device 50, and the double-sheet stacking portion 55 is provided so as to effectively utilize the normal paper among the remaining papers on the transport path as much as possible. By controlling, it is possible to reduce the number of spoiled papers.

<4. Modification example>
In each of the above-described embodiments, the control unit 100 of the image forming apparatus 10 controls the paper transfer and the two-sheet stacking unit 55, but the control unit 500 of the relay transfer device 50 may control the two-sheet stacking unit 55. In this case, the image defect determination result of the paper described on the left shoulder of each processing step shown in FIG. 18 may be at least written in the memory 550 of the relay transfer device 50 so that the control unit 500 can refer to it.

Further, although the description has been made assuming single-sided printing in each of the above-described embodiments, the present invention can also be applied to double-sided printing.

Furthermore, the present invention is not limited to the above-described embodiments, and it goes without saying that various other application examples and modifications can be taken as long as they do not deviate from the gist of the present invention described in the claims. be.

For example, the above-described embodiment describes the configuration of the apparatus and the system in detail and concretely in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the components described above. Further, it is possible to replace a part of the configuration of one embodiment with a component of another embodiment. It is also possible to add components of another embodiment to the configuration of one embodiment. Further, it is also possible to add, delete, or replace a part of the configuration of each embodiment with other components.

In addition, some or all of the above-mentioned components, functions, processing units, processing means, and the like may be realized by hardware, for example, by designing an integrated circuit. Further, each of the above components, functions, and the like may be realized by software by the processor interpreting and executing a program that realizes each function. Information such as programs, tables, and files that realize each function can be placed in a memory, a hard disk, a recording device such as an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

1 ... Image forming system, 10 ... Image forming apparatus, 11 ... Image forming unit, 40 ... Image reading device, 41 ... First reading unit (image reading unit), 42 ... Second reading unit (image reading unit), 50 ... Relay transport device, 51 ... Purge tray, 55 ... Two-sheet stacking unit, 60 ... Post-processing device, 61 ... Sub tray, 62 ... Paper output tray, 65 ... Post-processing unit, 100 ... Control unit, 101 ... Image defect detection unit, 102 ... Paper transfer control unit, 120 ... Paper transfer unit, 130 ... Reverse transfer unit, 131 ... Reverse unit, 530 ... First paper transfer unit, 540 ... Second paper transfer unit, 532 ... Stack unit, 534 ... First guide member , 535 ... 2nd guide member, 536 ... Vertical matching plate, 537 ... Refeed roller, 541 ... Switching unit, 560 ... Paper detection sensor

Claims (10)

A paper carrier that conveys the fed paper and
An image forming unit that forms an image on the paper,
An image reading unit that reads an image formed on the paper,
It is located on the downstream side of the image reading unit and is configured so that two sheets of paper can be stacked and stacked. The function of stacking and ejecting the two stacked sheets of paper and the function of stacking and ejecting the two sheets of paper are only one sheet in first-in, first-out manner. A two-ply stack that has the function of discharging,
A post-processing unit that performs post-processing on the paper on which an image is formed located on the downstream side of the two-sheet stacking unit, and a post-processing unit.
A paper ejection unit that ejects paper that is not conveyed to the post-processing unit,
It controls the paper feeding, the feeding, the image formation, the operation of the two-sheet stacking section, and the switching of the feeding destination of the paper, acquires the reading information of the image reading section, and determines whether the paper is normal or abnormal. With a control unit to
The image by the control unit between the time when the second sheet of paper is introduced into the two-sheet stacking portion and the time when the second sheet of paper is ejected when the two sheets of the paper are not stacked and ejected. The determination of the image defect of the paper based on the reading information of the reading unit is completed, and the determination of the image defect is completed.
When the control unit determines that the paper is image defective based on the reading information of the image reading unit, the control unit stops the operation of forming an image on the paper, and the page determined to be image defect and thereafter. An image forming system that controls a part or all of the paper remaining in the transport path during transport to be discharged to the paper discharge section. When the control unit executes a job on one page a plurality of times in succession,
When it is determined that both the first paper introduced into the two-sheet stacking portion and the second paper introduced following the first paper are normal, the first paper is introduced from the two-sheet stacking portion. The next paper is introduced into the two-sheet stacking unit while the paper of No. 1 and the second paper are overlapped and discharged to the post-processing unit.
Alternatively, when it is determined that the first paper introduced into the two-sheet stacking portion is normal and the second paper is abnormal, the first sheet determined to be normal from the two-sheet stacking portion is determined. While discharging only the paper to the post-processing unit, the next paper is introduced into the two-sheet stacking unit.
Alternatively, when it is determined that the first paper introduced into the two-sheet stacking portion is abnormal, only the first paper determined to be abnormal from the two-sheet stacking portion is sent to the paper ejection portion. The image forming system according to claim 1, wherein the next paper is controlled to be introduced into the two-sheet stacking portion while being ejected. When the control unit executes a multi-page job, the control unit
When it is determined that both the first paper introduced into the two-sheet stacking portion and the second paper introduced following the first paper are normal, it is determined to be normal from the two-sheet stacking portion. The first paper and the second paper were overlapped and discharged to the post-processing unit.
Alternatively, when it is determined that the first paper introduced into the two-sheet stacking portion is normal and the second paper is abnormal, the first sheet determined to be normal from the two-sheet stacking portion is determined. While discharging only the paper to the post-processing unit, the next paper is introduced into the two-sheet stacking unit.
Alternatively, when it is determined that the first paper introduced into the two-sheet stacking portion is abnormal and the second paper is normal, the first sheet determined to be abnormal from the two-sheet stacking portion. While transporting only the paper to the paper ejection section, the next paper is introduced into the two-sheet stacking section.
Alternatively, when it is determined that both the first paper and the second paper introduced into the two-sheet stacking portion are abnormal, the first paper determined to be abnormal from the two-sheet stacking portion is used. The image forming system according to claim 1, wherein the second paper is stacked and ejected to the paper ejection portion, and the next paper is controlled to be introduced into the two-sheet stacking portion. The control unit
When it is determined that the first paper introduced into the two-sheet stacking portion is abnormal, the first paper determined to be abnormal is ejected to the paper ejection portion, and then the subsequent image-formed paper is formed. If is normal, up to two sheets are stacked in the two-sheet stacking section, and the subsequent image-formed paper is ejected to the paper ejection section without passing through the two-sheet stacking section.
After that, if there is a page that is continuously determined to be abnormal before the page that is determined to be abnormal, the control unit starts from the oldest page that corresponds to the page, or before the page that is determined to be abnormal last. If there is no page determined to be abnormal, the job is restarted from that page, and images of pages other than the two pages of the paper are displayed until the two pages of the paper are stacked in the two-sheet stacking portion. The paper is sequentially formed into paper and conveyed to the post-processing unit without passing through the two-sheet stacking unit.
Then, according to claim 3, the two sheets of the paper stacked in the two-sheet stacking portion are inserted between the corresponding pages of the restarted job, and the next paper is controlled to be introduced into the two-sheet stacking portion. The image forming system described. Further, it is provided with a reversing transport unit that inverts the front end and the rear end of the paper on which the image is formed by the image forming unit, and the two-sheet stacking unit reverses the front end and the rear end of the introduced paper and ejects the paper. Has the function of
After restarting the job, the control unit reverses the paper of the page on which the image is formed again by the reversing transport unit until the page of the paper stacked in the two-sheet stacking unit is reached, and then the two-sheet stacking unit. The image forming system according to claim 4, wherein the image is conveyed to the post-processing unit without passing through the image forming unit. In the control unit, the paper is conveyed straight without passing through the two-sheet stacking unit, but before the paper reaches the discharge switching unit that switches the transfer destination of the paper to the post-processing unit or the paper ejection unit. The image forming system according to claim 4, wherein the paper transport speed is reduced so that the abnormality / normality determination process is completed. When the control unit determines that the paper previously introduced into the two-sheet stacking unit is abnormal after the start of the job, the control unit newly ejects the determined paper to the paper ejection unit. The image forming system according to any one of claims 1 to 6, wherein the two sheets of paper are introduced into the two-sheet stacking portion. A claim that the control unit stops the operation of forming an image on the paper and outputs a warning when the determination of the abnormality of the paper introduced in the two-sheet stacking unit occurs continuously for a predetermined number of times. The image forming system according to any one of 1 to 7. The two-sheet stacking portion is
A stacking section that allows you to stack up to two sheets of paper with the rear edge of the introduced paper facing up.
A guide member configured to be switched between an introduction position for introducing the paper and an ejection position for ejecting the paper and to partition the upper ends of the first and second sheets.
A re-feeding roller that conveys the paper stacked in the stack portion, and
The first position is located near the lower end of the stack portion to support the stacked paper so that the upper end of the paper is below the guide member, and the upper end of the paper is the guide member. It comprises a second position above and below the refeed roller and a vertical alignment plate that moves the third position where the top edge of the paper abuts the refeed roller.
When the two sheets of paper stacked in the stack unit are stacked and ejected, the control unit moves the vertical matching plate to the first position and then introduces the guide member to the introduction position before ejecting the two sheets. After switching the guide member to the ejection position, the vertical matching plate is moved to the third position, and the two sheets of the paper are abutted against the refeed roller and ejected.
Further, when only one of the two sheets of paper stacked in the stack portion is ejected, the guide member is moved to the introduction position from the state when the second sheet is stacked in the stack portion. By moving the vertical matching plate to the third position while partitioning the upper ends of the first and second sheets by the guide member, only the first sheet of the paper is re-fed. The image forming system according to any one of claims 1 to 8, wherein the image forming system is controlled so as to be abutted against a roller and discharged. The image forming system according to claim 9, wherein the re-feeding roller is arranged above the guide member and below the transport roller provided in the introduction transport path for introducing the paper into the stack portion.

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