Paper transport device and image forming system

Abstract

To achieve cost reduction by making it possible to determine the presence or absence of paper located at a separation point without providing a separate sensor for detecting the presence or absence of the paper located at the separation point.SOLUTION: Based on detection results of a discharge sensor 19 and a bridge sensor 240, a control unit 110 determines the presence or absence of paper P located at a separation point between inside and outside of a drawer unit 230 at the time a jam occurs, and when it determines that the paper P is present, it executes a separation resolution process to remove the paper P from the separation point.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a paper transport device and an image forming system, and more particularly to a technique for determining whether or not a paper sheet is located at a location where the paper sheet is separated, and for removing the paper sheet from the location where the paper sheet is separated. [Background technology]

[0002] There are known image forming devices in which a portion of the paper transport path can be pulled out to the outside. In such a typical image forming device, when a paper jam occurs, the user pulls out the portion of the paper transport path and removes the paper from the paper transport path to clear the jam.

[0003] In the above-described general image forming apparatus, when a jam occurs, the paper may stop straddling the removable paper transport path and the non-removable paper transport path, and if the user pulls out the removable paper transport path, the paper may tear, resulting in a so-called "separation."

[0004] To solve such problems, for example, Patent Document 1 discloses a technology in which, when a jam occurs, if it detects the presence of a sheet straddling a transport path that can be pulled out and a transport path that cannot be pulled out, the sheet remaining on the transport path is transported toward a retraction section. Patent Document 2 discloses a technology in which, when it detects the presence of a sheet straddling a transport path of the image forming apparatus main body and a transport path of the drawer unit, the drawer unit is locked to the apparatus main body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-280303 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-134753 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the techniques disclosed in Patent Documents 1 and 2 require a separate sensor to detect the presence or absence of paper at the separation point, which increases costs. Furthermore, to prevent separation, a retraction section or locking mechanism for retracting paper is provided, which further increases costs.

[0007] To provide an apparatus for determining the presence or absence of paper at a separation point without providing a separate sensor for detecting the presence or absence of paper at the separation point, thereby achieving cost reduction. [Means for solving the problem]

[0008] A paper transport device according to one aspect of the present invention comprises a paper transport path, a portion of which is configured as a drawer unit that can be pulled out, a pair of rollers that transport paper along the paper transport path, a paper detection unit that detects the presence or absence of paper being transported along the paper transport path, and a control unit that determines the presence or absence of paper located at a jam point between the inside and outside of the drawer unit at the time a jam occurs based on the detection result of the paper detection unit, and if it determines that paper is present, executes a jam resolution process to remove the paper from the jam point.

[0009] An image forming system according to another aspect of the present invention includes an image forming device that forms an image on paper, a post-processing device that performs post-processing on the paper, and the above-mentioned paper transport device that receives paper from the image forming device and transports it to the post-processing device. [Effects of the Invention]

[0010] According to the present invention, the presence or absence of paper at the separation point is determined using the detection results of the paper detection unit that detects the presence or absence of paper being transported along the paper transport path. Therefore, compared to when a separate sensor is provided to detect the presence or absence of paper at the separation point, the number of sensors can be reduced, thereby achieving cost reductions for the product. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a front cross-sectional view showing a configuration of an image forming system. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of a relay unit. [Figure 3] FIG. 2 is a functional block diagram showing the main internal configuration of the image forming apparatus. [Figure 4] FIG. 10 is a diagram showing a state in which two sheets of paper are respectively positioned at a separation point between the inside and outside of the drawer unit. [Figure 5] 10 is a flowchart showing a process for resolving a bitter separation. [Figure 6] FIG. 10 is a diagram showing a state in which downstream paper has been discharged from the drawer unit. [Figure 7] 10A and 10B are diagrams illustrating a state in which the upstream paper is retained in the drawer unit without being positioned at the separation point. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Configuration of image forming system 1] An image forming system 1 according to one embodiment of the present invention will be described below with reference to the drawings.

[0013] Fig. 1 is a front cross-sectional view showing the configuration of an image forming system 1 according to one embodiment of the present invention. Referring to Fig. 1, the image forming system 1 includes an image forming device 10, a relay unit 20, and a post-processing device 30. The image forming device 10 forms an image on a sheet P. The relay unit 20 receives the sheet P from the image forming device 10 and relays it to the post-processing device 30. The post-processing device 30 receives the sheet P from the relay unit 20 and performs post-processing on the sheet P.

[0014] [Configuration of image forming apparatus 10] Image forming apparatus 10 is an internal paper discharge type digital multifunction peripheral. Image forming apparatus 10 includes, within its housing, an image reading unit 11, an image forming unit 12, a fixing unit 13, and a paper feed unit 14. Within the housing of image forming apparatus 10, a transport path 15 is formed, extending from paper feed unit 14 via image forming unit 12 and fixing unit 13.

[0015] The image reading unit 11 includes an original transport unit 6 that transports an original placed on an original table. The image reading unit 11 optically reads an image of an original transported by the original transport unit 6 or an original placed on a platen glass 7, and generates image data.

[0016] The image forming unit 12 includes a photosensitive drum, a charging device, an exposure device, a developing device, and a transfer device. The image forming unit 12 forms a toner image based on image data on a sheet P by an electrophotographic process.

[0017] The fixing unit 13 applies heat and pressure to the paper P on which the toner image has been formed, thereby fixing the toner image to the paper P. In this way, an image is formed on the paper P.

[0018] The paper feed unit 14 includes a plurality of paper feed cassettes. The paper feed unit 14 uses a pickup roller to pull out the paper P stored in one of the plurality of paper feed cassettes one by one and feeds the paper to the conveyance path 15.

[0019] A pair of transport rollers 15A is provided at an appropriate position on the transport path 15. The pair of transport rollers 15A transports the paper P along the transport path 15. The transport path 15 branches into a first transport path 16 and a second transport path 17 downstream of the fixing unit 13 in the paper transport direction.

[0020] The first transport path 16 is formed to extend from the branching point to the discharge port, and the second transport path 17 is formed to extend from the branching point to the connection between the image forming apparatus 10 and the relay unit 20.

[0021] A switching claw 18 is provided at the branch point between the first transport path 16 and the second transport path 17. The switching claw 18 switches the transport direction of the paper P to either the first transport path 16 or the second transport path 17 by switching its position under the control of the control unit 110, which will be described later.

[0022] A first discharge roller pair 16A is provided at the downstream end in the paper transport direction of the first transport path 16. The first discharge roller pair 16A discharges the paper P guided into the first transport path 16 by the switching claw 18 from the discharge opening to the outside of the image forming apparatus 10.

[0023] A second discharge roller pair 17A is provided at the downstream end in the paper transport direction of the second transport path 17. The second discharge roller pair 17A discharges the paper P guided to the second transport path 17 by the switching claw 18 toward the relay unit 20.

[0024] [Configuration of relay unit 20] The image forming apparatus 10 is provided with an internal paper discharge space. A relay unit 20 is disposed in the internal paper discharge space. The upper surface of the housing of the relay unit 20 functions as a discharge tray for stacking the paper P discharged by the first discharge roller pair 16A.

[0025] Fig. 2 is a schematic diagram showing the configuration of the relay unit 20. Referring to Fig. 2, the relay unit 20 includes a relay transport path 210 and bridge roller pairs 220A to 220E. The relay transport path 210 is formed so as to extend from the connection between the image forming apparatus 10 and the relay unit 20 to the connection between the post-processing apparatus 30 and the relay unit 20.

[0026] The bridge roller pairs 220A to 220E transport the paper P along the relay transport path 210. The bridge roller pairs 220A to 220E are arranged in this order from the upstream side to the downstream side in the paper transport direction.

[0027] The second discharge roller pair 17A and the bridge roller pair 220A, 220B are upstream roller pairs located upstream in the paper transport direction, and are controlled to be driven in conjunction with each other in the separation resolution process described below. The bridge roller pair 220C, 220D, 220E are downstream roller pairs located downstream in the paper transport direction, and are controlled to be driven in conjunction with each other in the separation resolution process described below.

[0028] The second conveying path 17 and the relay conveying path 210 function as a paper conveying path for conveying the paper P from the image forming device 10 to the post-processing device 30. A portion of the relay conveying path 210 is configured as a drawer unit 230 that can be drawn forward (toward the viewer in the drawing). The bridge roller pairs 220A to 220D are arranged inside the drawer unit 230.

[0029] A discharge sensor 19 is provided near the second discharge roller pair 17A and upstream of the second discharge roller pair 17A in the paper transport direction. A bridge sensor 240 is provided between the bridge roller pair 220C and the bridge roller pair 220D.

[0030] The discharge sensor 19 and the bridge sensor 240 are photosensors that detect the presence or absence of paper P being transported on the paper transport path, and include a light-emitting element and a light-receiving element that are arranged opposite each other. The discharge sensor 19 and the bridge sensor 240 output an OFF signal when paper P is detected, and output an ON signal when paper P is not detected.

[0031] The discharge sensor 19 and the bridge sensor 240 are not limited to photo sensors. The discharge sensor 19 and the bridge sensor 240 may be any sensor that can detect the presence or absence of paper P, and may be, for example, a mechanical sensor that has a configuration that physically detects contact with paper P.

[0032] The relay unit 20, the discharge sensor 19, the second discharge roller pair 17A, and the second transport path 17 constitute a paper transport device in the claims.

[0033] [Configuration of post-processing device 30] The post-processing device 30 includes a punch unit 31, a staple unit 32, a paper folding unit 33, a main bin 34, multiple sub-bins 35, a discharge tray 36, a branch guide 37, a pair of discharge rollers 38, a paper receiving tray 39, and a pair of transport rollers 40. The main bin 34 and each sub-bin 35 are raised and lowered by a lifting mechanism to positions corresponding to the pair of discharge rollers 38.

[0034] The punching section 31 performs punching on the paper sheet P conveyed from the relay unit 20. After punching, the paper sheet P is guided by a branch guide 37 to a pair of discharge rollers 38 or a paper receiving tray 39. The pair of discharge rollers 38 discharges the paper sheet P into one of the main bin 34 or multiple sub-bins 35.

[0035] The stapler 32 staples the stack of sheets P that have been guided to and stored on the sheet receiving tray 39. The stack of sheets P that has undergone staple processing is either discharged by a pair of discharge rollers 38 into one of the main bin 34 and multiple sub-bins 35, or conveyed by a pair of conveyor rollers 40 toward the paper folding unit 33.

[0036] The folding unit 33 performs a folding process to fold the bundle of sheets P conveyed by the conveyance roller pair 40 in the center. The bundle of sheets P after the folding process is discharged onto the discharge tray .

[0037] [Configuration related to control of image forming system 1] 3 is a functional block diagram showing the main internal configuration of image forming apparatus 10. Referring to FIG. 3, image forming apparatus 10 further includes a display unit 21, an operation unit 22, an HDD (Hard Disk Drive) 23, an image processing unit 24, an image memory 25, a facsimile communication unit 26, a communication unit 27, a conveyance unit 28, an interface unit 29, and a control unit 100.

[0038] The display unit 21 is a display device including a liquid crystal display, an organic EL (organic light-emitting diode) display, etc. The display unit 21 displays various screens.

[0039] The operation unit 22 includes a plurality of hard keys including a start key for inputting instructions to start execution of each process that can be executed by the image forming apparatus 10. The operation unit 22 also includes a touch panel that is placed over the display unit 21. User instructions are input into the operation unit 22.

[0040] The HDD 23 is a large-capacity storage device for storing various data such as image data. The HDD 23 stores various control programs for realizing general operations of the image forming apparatus 10. As part of the various control programs, the HDD 23 stores a resolution program for executing a separation resolution process, which will be described later.

[0041] Image processing unit 24 performs image processing as necessary on the image data generated by image reading unit 11. Image memory 25 includes an area for temporarily storing the image data generated by image reading unit 11. Facsimile communication unit 26 transmits and receives image data via a public line.

[0042] The communication unit 27 includes a communication module such as a LAN (Local Area Network) board, etc. The communication unit 27 performs data communication with an external device such as a PC (Personal Computer) via a network.

[0043] The transport section 28 includes a transport roller pair 15A, a first discharge roller pair 16A, a second discharge roller pair 17A, etc., and a transport motor. The transport motor is driven to rotate the transport roller pair 15A, the first discharge roller pair 16A, the second discharge roller pair 17A, etc.

[0044] The relay unit 20 and the post-processing device 30 are electrically connected to the interface section 29. The interface section 29 includes a plurality of terminals for electrically connecting with the relay unit 20 and the post-processing device 30.

[0045] The control unit 100 includes a processor, a random access memory (RAM), a read only memory (ROM), etc. The processor is, for example, a central processing unit (CPU), a micro processing unit (MPU), or an application specific integrated circuit (ASIC).

[0046] The control unit 100 is electrically connected to the document transport unit 6, image reading unit 11, image forming unit 12, fixing unit 13, paper feeding unit 14, display unit 21, operation unit 22, HDD (Hard Disk Drive) 23, image processing unit 24, image memory 25, facsimile communication unit 26, communication unit 27, transport unit 28, and interface unit 29, etc.

[0047] The control unit 100 functions as a control unit 110 when a control program stored in the ROM or HDD 23 is executed by the processor. The control unit 110 may be configured by a logic circuit, without relying on operations based on the control program.

[0048] The control unit 110 is responsible for overall control of the image forming apparatus 10. That is, the control unit 110 controls the operation of each unit of the image forming apparatus 10. The control unit 110 also controls the operation of each unit of the relay unit 20 and the post-processing device 30 via the interface unit 29.

[0049] Each part of the image forming apparatus 10 is connected to a power supply, and each part of the image forming apparatus 10 operates when power is supplied from the power supply.

[0050] In the image forming system 1 having such a configuration, when a user inputs an instruction to start execution of, for example, copy processing and post-processing into the operation unit 22, the control unit 110 causes the image reading unit 11 to read the image of the original document, and controls the operation of the paper feed unit 14, the pair of transport rollers 15A, the image forming unit 12, and the fixing unit 13 to form the image of the original document on the paper P.

[0051] The control unit 110 causes the switching claw 18 to guide the paper P on which the image of the original document has been formed to the second transport path 17, and rotates the second discharge roller pair 17A and the bridge roller pairs 220A to 220E to transport the paper P to the post-processing device 30 through the relay transport path 210. The control unit 110 controls the operation of each part of the post-processing device 30 to perform post-processing such as punching, stapling, or folding on the paper P transported to the post-processing device 30.

[0052] In addition, when post-processing is not required, such as when the user inputs an instruction to start only the copy process into the operation unit 22, the control unit 110 causes the switching claw 18 to guide the paper P on which the image of the original document is formed to the first conveying path 16, and drives the first discharge roller pair 16A to rotate, thereby discharging the paper P onto the top surface of the housing of the relay unit 20.

[0053] [Resolving a bitter separation] 4 is a diagram showing two sheets of paper P positioned at a separation point between the inside and outside of the drawer unit 230. Hereinafter, the sheet of paper P that straddles the upstream end of the drawer unit 230 in the paper transport direction and the outside of the drawer unit 230 will be referred to as "upstream sheet of paper P1," and the sheet of paper P that straddles the downstream end of the drawer unit 230 in the paper transport direction and the outside of the drawer unit 230 will be referred to as "downstream sheet of paper P2."

[0054] As shown in Figure 4, when the upstream paper P1 and the downstream paper P2 are positioned at the separation point of the drawer unit 230, if the user pulls out the drawer unit 230 toward the front (in a direction perpendicular to the paper transport direction), separation occurs, causing the upstream paper P1 and the downstream paper P2 to tear.

[0055] In order to prevent such a jam from occurring, in this embodiment, the control unit 110 operates in accordance with the above-mentioned resolution program to determine whether or not paper P is located at the jamming point between the inside and outside of the drawer unit 230 at the time the jam occurs, based on the detection results of the discharge sensor 19 and the bridge sensor 240, and if it determines that paper P is present, it executes a jamming resolution process to remove paper P from the jamming point.

[0056] [Operation] 5 is a flowchart showing the process of eliminating the separation of the parties involved. Hereinafter, the operation of the image forming system 1 when the process of eliminating the separation of the parties involved is executed will be described with reference to FIG.

[0057] When the control unit 110 receives an instruction to start execution of, for example, copy processing and post-processing via the operation unit 22, it monitors whether a jam has occurred in the relay unit 20. For example, when a jam of paper P is detected because the bridge sensor 240 does not output an OFF signal within a predetermined time after the discharge sensor 19 outputs an OFF signal, the control unit 110 starts execution of a separation resolution process.

[0058] When the control unit 110 starts executing the separation resolution process, it first determines whether or not there is paper P located at the separation point between the inside and outside of the drawer unit 230 based on the detection results of the discharge sensor 19 and the bridge sensor 240 (step S10).

[0059] In step S10, the control unit 110 first determines whether or not there is upstream paper P1 at the time the jam occurred. Specifically, the control unit 110 measures a first elapsed time from the time the discharge sensor 19 output an OFF signal. Based on the first elapsed time at the time the jam was detected and a predetermined transport speed of the paper P, the control unit 110 calculates the distance between the discharge sensor 19 and the leading edge of the paper P in the paper transport direction that caused the discharge sensor 19 to output an OFF signal at the time the jam was detected.

[0060] If the calculated distance is longer than the distance L1 from the discharge sensor 19 to the upstream end of the drawer unit 230 in the paper transport direction, the control unit 110 determines that the leading edge of the paper P in the paper transport direction is located inside the drawer unit 230, that is, that the upstream paper P1 is "present." If the calculated distance is equal to or less than the distance L1, the control unit 110 determines that the upstream paper P1 is "absent."

[0061] Next, the control unit 110 determines whether or not there is downstream paper P2 at the time the jam occurred. Specifically, the control unit 110 measures a second elapsed time from the time the output of the bridge sensor 240 switched from an OFF signal to an ON signal. Based on the second elapsed time at the time the jam was detected and a predetermined transport speed of the paper P, the control unit 110 calculates the distance between the bridge sensor 240 and the rear end in the paper transport direction of the paper P that caused the bridge sensor 240 to output the OFF signal and the ON signal at the time the jam was detected.

[0062] If the calculated distance is shorter than distance L2 from bridge sensor 240 to the downstream end of drawer unit 230 in the paper transport direction, control unit 110 determines that the rear end of paper P in the paper transport direction is located inside drawer unit 230, that is, that downstream paper P2 is "present." If the calculated distance is distance L2 or more, control unit 110 determines that downstream paper P2 is "absent."

[0063] If the control unit 110 determines that both the upstream paper P1 and the downstream paper P2 are "absent," it determines that the paper P located at the split location is "absent" (NO in step S10) and terminates the split resolution process.

[0064] On the other hand, if the control unit 110 determines that at least one of the upstream paper P1 and the downstream paper P2 is "present," it determines that the paper P located at the separation point is "present" (YES in step S10), and determines whether the length of the paper P in the paper transport direction (hereinafter referred to as "paper length") is less than or equal to a predetermined length (step S11).

[0065] The predetermined length is not particularly limited as long as it is shorter than the length of the drawer unit 230 in the paper transport direction, that is, as long as it is a length that allows the paper P to remain inside the drawer unit 230 without being positioned at a separation point. In this embodiment, the control unit 110 sets the distance L3 from the upstream end of the drawer unit 230 in the paper transport direction to the bridge sensor 240 as the predetermined length.

[0066] (1) When the paper length is less than the predetermined length If the control unit 110 determines that the paper length is less than or equal to a predetermined length (YES in step S11), it rotates the downstream roller pair and executes a downstream paper discharge process to discharge the downstream paper P2 from inside the drawer unit 230 (step S12).

[0067] Specifically, in step S12, the control unit 110 rotates the bridge roller pairs 220C, 220D, and 220E for a time period corresponding to the distance L4 from the bridge roller pair 220C to the downstream end of the drawer unit 230 in the paper transport direction plus the length of the paper.

[0068] After processing step S12, the control unit 110 executes an upstream paper transport process (step S13) to rotate the upstream roller pair and transport the upstream paper P1 to a retention position where the upstream paper P1 can be retained inside the drawer unit 230 without spanning between the inside and outside of the drawer unit 230.

[0069] Specifically, in step S13, the control unit 110 drives and rotates the second discharge roller pair 17A and the bridge roller pair 220A, 220B until the bridge sensor 240 outputs an OFF signal. After the process of step S13, the control unit 110 ends the separation resolution process.

[0070] For example, when the control unit 110 executes the process of step S12 in a state in which the downstream sheet P2 and the upstream sheet P1 are each located at a split location in the drawer unit 230 as shown in Fig. 4, the downstream sheet P2 is completely ejected from inside the drawer unit 230 as shown in Fig. 6. This reliably prevents the downstream sheet P2 from being split when the drawer unit 230 is drawn out.

[0071] Furthermore, when the control unit 110 executes the process of step S13, the upstream-side sheet P1 remains inside the drawer unit 230 without spanning between the inside and outside of the drawer unit 230, as shown in Fig. 7. This reliably prevents the upstream-side sheet P1 from being separated when the drawer unit 230 is drawn out. The user can easily remove the upstream-side sheet P1 by drawing out the drawer unit 230.

[0072] Furthermore, because the upstream paper P1 is transported to the retention position, the drive time of the upstream roller pair, etc. can be shortened compared to when the upstream paper P1 is transported until it is discharged from inside the drawer unit 230. As a result, the possibility of a disappointing separation due to the user pulling out the drawer unit 230 while the upstream paper P1 is being transported can be reduced.

[0073] (2) When the paper length is longer than the predetermined length If the control unit 110 determines that the paper length is longer than a predetermined length (NO in step S11), it executes a full paper discharge process by rotating the downstream roller pair and the upstream roller pair, etc., to discharge all of the paper P (in this case, the upstream paper P1 and the downstream paper P2) remaining in the drawer unit 230 from inside the drawer unit 230 (step S14).

[0074] Specifically, in step S14, control unit 110 drives second discharge roller pair 17A and bridge roller pairs 220A to 220E to rotate for a time period corresponding to the length of drawer unit 230 in the paper transport direction plus the length of the paper. After processing step S14, control unit 110 ends the separation resolution process.

[0075] In this way, when the length of the paper P located at the splitting point of the drawer unit 230 is longer than a predetermined length, all of the paper P is discharged from inside the drawer unit 230, so that it is possible to reliably prevent the paper P from being splitting when the drawer unit 230 is drawn out.

[0076] According to the above embodiment, the control unit 110 determines whether or not paper P is located at the separation point between the inside and outside of the drawer unit 230 at the time the jam occurs based on the detection results of the discharge sensor 19 and the bridge sensor 240, and if it determines that paper P is present, it executes a separation resolution process to remove paper P from the separation point.

[0077] In this way, the presence or absence of paper at the separation point is determined using the detection results of the discharge sensor 19 and the bridge sensor 240, so the number of sensors can be reduced compared to when a separate sensor is provided to detect the presence or absence of paper at the separation point, thereby achieving a reduction in product costs.

[0078] Furthermore, according to the above embodiment, the control unit 110 determines whether there is upstream paper P1 and downstream paper P2 at the time the jam occurs, thereby enabling appropriate separation resolution processing to be performed according to the position of the paper P located at the separation location.

[0079] Furthermore, according to the above embodiment, when the paper length is equal to or shorter than a predetermined length, the control unit 110 executes the upstream paper transport process in step S13, and when the length of the paper in the paper transport direction is longer than the predetermined length, the control unit 110 executes the all-paper discharge process in step S14. This allows appropriate separation resolution processing to be executed according to the paper length.

[0080] Furthermore, according to the above embodiment, if the paper length is equal to or shorter than a predetermined length, the control unit 110 executes the downstream paper ejection process in step S12 before executing the upstream paper transport process. This allows the downstream paper P2 to be ejected smoothly and the upstream paper P1 to be transported to the retention position even when the upstream paper P1 and the downstream paper P2 are located at the separation point of the drawer unit 230. As a result, the upstream paper P1 and the downstream paper P2 can be removed from the separation point without interfering with each other. Furthermore, separation can be prevented without the need for a separate mechanism for preventing separation.

[0081] (Other variations) In the above embodiment, the control unit 110 determines whether the downstream sheet P2 is present at the time of the jam based on the output of the bridge sensor 240. However, the present invention is not limited to such an embodiment. For example, the control unit 110 may determine whether the downstream sheet P2 is present based on the output of the discharge sensor 19.

[0082] In this case, the control unit 110 measures a third elapsed time from the time when the output of the discharge sensor 19 switched from an OFF signal to an ON signal. Based on the third elapsed time at the time when the jam was detected and the predetermined transport speed of the paper P, the control unit 110 calculates the distance between the discharge sensor 19 and the rear end in the paper transport direction of the paper P that caused the discharge sensor 19 to output the OFF signal and the ON signal at the time when the jam was detected.

[0083] If the calculated distance is shorter than the distance from the discharge sensor 19 to the downstream end of the drawer unit 230 in the paper transport direction, the control unit 110 determines that the rear end of the paper P in the paper transport direction is located inside the drawer unit 230, that is, that downstream paper P2 is "present." If the calculated distance is equal to or greater than the above distance, the control unit 110 determines that downstream paper P2 is "absent."

[0084] In the above embodiment, the drawer unit 230 provided on the relay conveyance path 210 is shown as an example of the drawer unit, but the present invention is not limited to such an embodiment. The drawer unit may be provided on any paper conveyance path along which paper is conveyed, and may be provided on the conveyance path 15, for example.

[0085] In the above embodiment, a digital multifunction peripheral is shown as an example of the image forming apparatus 10, but the present invention is not limited to such an embodiment. The image forming apparatus 10 may be any image forming apparatus with internal paper discharge, such as a laser printer or an inkjet printer.

[0086] The configuration and processing of the embodiment described above using FIGS. 1 to 7 are merely one embodiment of the present invention, and the present invention is not limited to these configurations and processing. [Explanation of symbols]

[0087] 1. Image forming system 10 Image forming device 20 Relay unit 30 After-treatment device 10 Control Unit 17 Second conveying path 19 Emission sensor 210 Relay transport route 220A, 220B, 220C, 220D, 220E Bridge Roller Pair 230 Drawer Unit 240 Bridge Sensor

Claims

1. a paper transport path, a portion of which is configured as a drawer unit that can be drawn out; a pair of rollers that transport paper along the paper transport path; a paper detection unit that detects the presence or absence of the paper being transported on the paper transport path; A paper transport device comprising: a control unit that determines whether or not the paper is located at the separation point between the inside and outside of the drawer unit at the time the jam occurs based on the detection results of the paper detection unit; and if it determines that the paper is present, executes a separation resolution process to remove the paper from the separation point.

2. The paper transport device described in claim 1, wherein the control unit determines whether there is upstream paper spanning between the upstream end of the drawer unit in the paper transport direction and the outside of the drawer unit at the time a jam occurs, and whether there is downstream paper spanning between the downstream end of the drawer unit in the paper transport direction and the outside of the drawer unit.

3. the roller pair further includes an upstream roller pair disposed upstream in the paper transport direction, and a downstream roller pair disposed downstream in the paper transport direction, The control unit When the length of the paper in the paper transport direction is equal to or shorter than a predetermined length that is shorter than the length of the drawer unit in the paper transport direction, an upstream paper transport process is executed as the separation resolution process, in which the upstream roller pair is rotationally driven to transport the upstream paper to a retention position where the upstream paper can be retained inside the drawer unit without spanning between the inside and outside of the drawer unit, A paper transport device as described in claim 2, wherein when the length of the paper in the paper transport direction is longer than the predetermined length, the upstream roller pair and the downstream roller pair are rotated to perform a full paper discharge process as the separation resolution process to discharge all of the paper remaining in the drawer unit from inside the drawer unit.

4. The paper transport device of claim 3, wherein the control unit, when the length of the paper in the paper transport direction is less than the predetermined length, performs a downstream paper discharge process as the separation resolution process by rotating the downstream roller pair before performing the upstream paper transport process to discharge the downstream paper from inside the drawer unit.

5. an image forming device that forms an image on a sheet; a post-processing device that performs post-processing on the paper; and the paper transport device according to claim 1 that receives the paper from the image forming device and transports it to the post-processing device.

Images