JP5030844B2 - Paper discharge device and image forming apparatus - Google Patents

Description

The present invention the trailing edge of the sheet conveyed, the paper discharge detection device of the configuration that leads to the rear end fence for integration by aligning the paper, and an image forming apparatus provided with the paper discharge detection device .

  A paper post-processing device called a finisher that performs post-processing such as stapling on the paper after image formation discharged from the image forming device may be connected to an image forming device such as a copying machine, a printer, or a facsimile machine. . This type of post-processing apparatus is provided with a rear end fence that is inclined so that the rear end side is downward with respect to the paper conveyance direction, and a tray on which image-formed paper is inclined in the vertical direction is provided. The paper is ejected and the trailing edge of the paper is abutted against the trailing edge fence to align the paper in the vertical direction, and the jogger fence is used to align the paper in the horizontal direction. Some perform processing.

  In this case, since the tray is inclined in the vertical direction, when the paper discharged to the tray by the discharge roller provided in the vicinity of the tray falls by its own weight toward the rear end fence, it falls on the discharge roller. May end up. If the sheet falls toward the discharge roller, the sheet is caught in the discharge rotor, causing jamming and misalignment.

  For this reason, various proposals have been made and implemented in this type of paper discharge device (for example, Patent Document 1).

  FIGS. 15A to 15E are explanatory diagrams of the configuration and operation of the main part of the paper discharge device using the configuration described in Patent Document 1, and are the paper discharge drive roller 200 and the driven roller 201, and the paper P 15a and a paper rear end guide 203 that guides the rear end in the transport direction toward the paper stacking unit 202, and a protruding side surface portion 203a is provided on the downstream side of the paper rear end guide 203 in the paper transport direction, as shown in FIG. As shown in FIG. 15A, the protruding side surface portion 203a receives the conveyance force of the sheet P when entering the sheet and is retracted to a position where the conveyance of the sheet P is not hindered. Projecting from the nip N portion between the paper ejection driving roller 200 and the driven roller 201 to the paper stacking portion 202 side, and the ejection side surface 203a ejects the ejection port (nip ejection at the nip) by the paper ejection driving roller 200 and the driven roller 201. ) Is set to configuration to close the.

With the above configuration, in the paper discharge device described in Patent Document 1, the protruding side surface portion 203a prevents the paper P from being caught, and the paper trailing edge does not flow backward in the direction of the paper discharge driving roller 200 and the driven roller 201. Even the printed paper is surely guided to the paper stacking unit 202 side.
Japanese Patent No. 3850590

  However, in the paper discharge device described in Patent Document 1, after the paper rear end guide 203 provided for preventing the paper backflow at the time of paper discharge is retracted by the paper P that has entered, FIGS. As shown in FIG. 5B, the paper P may bounce back and push down the leading edge of the paper P. As a result, the paper entering angle into the paper stacking section 202 becomes large, and the leading edge of the paper comes into contact with the paper stacking section 202. Thereafter, as shown in FIG. 15 (e), the paper P may buckle and curl and may not be stacked normally.

  The present invention solves the problems of the prior art, maintains a retracted posture of the paper trailing edge guide, and does not affect the paper intrusion operation by the paper trailing edge guide, and An object of the present invention is to provide an image forming apparatus including a paper discharge device.

To achieve the above object, a first aspect of the present invention, it passes through a sheet discharge means having at least one pair of the pairs of output rollers forming Ru and a discharging driving roller and the driven roller, the the paper discharge unit Paper And a paper trailing edge guide that closes the paper conveyance path so that the paper trailing means does not return to the nip of the paper discharging means. The paper trailing edge guide is formed on a side formed by a portion of the paper discharging side. An end portion, a protruding portion located upstream of the side end portion in the paper conveyance direction, and an edge positioned between the protruding portion on the discharge driving roller side of the side end portion and the protruding portion. The paper rear end guide includes a closed position where the side end blocks the paper conveyance path so that the paper that has passed through the paper discharge means does not return to the nip of the paper discharge means, and the paper discharge means Hinders the transport of paper discharged by When the paper enters the nip of the paper discharge means with the paper rear end guide being in the closed position, the front end of the paper is The paper trailing edge guide is moved to the retracted position by contacting the edge portion on the upstream side of the nip with respect to the sheet conveyance direction and pressing the portion without contacting the nip, When the end guide is moved to the retracted position, the sheet portion upstream of the sheet in the sheet conveying direction is brought into sliding contact with the protruding portion to hold the sheet trailing end guide at the retracted position, and the edge so as not to tip of the end contacts the sheet, characterized in that the paper guide rail is formed by this arrangement, the sheet trailing end guide is retracted by the presence of collision caused partial attitude Can maintain To become kill manner, the sheet rear end guide can be prevented depressing the paper edge, it is possible to prevent a paper jam by rounding conventional such paper.

According to a second aspect of the present invention, there is provided an image forming apparatus comprising the paper discharge device according to the first aspect, wherein paper jams due to paper rounding are prevented, and paper is discharged to the paper discharge portion. Since the sheets can be aligned and collected, the paper post-processing can be performed satisfactorily.

According to the paper sheet discharge apparatus according to the present invention, the collision force portion formed on the sheet trailing end guide, paper guide rail is regulated by the sheet being conveyed in the nip near the retracted position, the retracted posture is maintained This arrangement prevents the paper trailing edge guide from pushing down the paper leading edge, prevents paper jams due to paper curling as in the past, and aligns the paper well at the stacking location. Can be integrated.

  According to the image forming apparatus according to the present invention, by including the paper discharge device according to the present invention, it is possible to prevent paper jamming due to paper rounding and the like so that the paper can be aligned and stacked on the paper discharge portion. Paper post-processing can be performed satisfactorily.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a sheet post-processing apparatus including a sheet discharging apparatus according to an embodiment of the present invention.

  In FIG. 1, an entrance sensor 36 that detects the carry-in of paper, an entrance roller 1 for carrying paper into the inside, at a conveyance path entrance b following the paper discharge path a in the copying machine A that is an image forming apparatus, A branching claw 8 is provided for switching the paper transport path. The branching claw 8 divides a paper conveyance path conveyed in the direction of the paper discharge tray 12 and a paper conveyance path conveyed to the stapling apparatus 11.

  On the transport path in the direction of the paper discharge tray 12, an upper transport roller 2 for transporting the paper from the branching claw 8 to the paper discharge tray 12, and a paper discharge sensor for detecting the paper transported by the upper transport roller 2 38, a discharge roller 3 for discharging the paper to the paper discharge tray 12, a feed roller 7 for collecting the paper at a predetermined position on the paper discharge tray 12, and a paper surface lever 13 for detecting the paper on the paper discharge tray 12. A paper surface sensor 33 for detecting the position of the paper surface lever 13 is disposed.

  The discharge tray 12 is moved up and down and left and right by a vertical motor 51 that moves up and down the discharge tray 12 and a shift motor 52 that shifts the discharge tray 12 in the horizontal direction shown in FIG.

  In the transport path in the direction of the stapling device 11, a lower transport roller 4 for transporting the paper from the branch claw 8 to the stapling device 11, and a paper discharge sensor 37 for detecting the paper transported by the lower transport roller 4. A paper discharge device 60 and the like to be described later are arranged. The lower transport roller 4 is driven by a transport motor 54 shown in FIG. The stapling device 11 is provided below the staple tray 21, and the staple tray 21 discharges the jogger fence 9 for aligning sheets, the return roller 5, and the sheet bundle bound to the position behind the jogger fence 9. Discharge belts 10 for each are arranged.

  As shown in FIG. 2, the jogger fence 9 is driven by a jogger motor 26 via a jogger belt 49, and the return roller 5 is supported by a tapping solenoid 30 so that the pendulum movement is possible. A drive belt 47 transmits the driving force of the paper discharge motor 55 shown in FIG. 7 to the return roller 5 and the paper discharge roller 6 of the paper discharge device 60.

  Further, as shown in FIG. 3, a rear end fence 19 for abutting the paper side is provided below the jogger fence 9. As shown in FIG. 4, the rear end fence 19 includes fixed pieces 19a and 19b and movable deformable pieces 19c and 19d that move together when the stapling apparatus 11 moves. As shown in FIG. 4, the stapling apparatus 11 is driven by the stapler moving motor 27 via the staple belt 50 and moves laterally.

  Further, as shown in FIG. 5, a discharge belt 10 is provided on the front side of the jogger fence 9 and is driven by a discharge motor 57. The discharge belt 10 is provided with a discharge belt home sensor 39 that detects that the discharge belt 10 is located at the home position.

  The paper discharge sensor 37 shown in FIG. 2 detects the trailing edge of the paper, and immediately issues an ON command to the sloping solenoid 30 of the return roller 5 to activate the pendulum movement of the return roller 5. 5 is arranged at a position where it can hit the trailing edge of the paper.

  As shown in FIG. 6, the discharge tray 12 is suspended by a pair of upper and lower lift belts 48, and these upper and lower lift belts 48 are driven by a vertical motor 51 through a gear train and a timing belt, and the vertical motor 51 It goes up and down by forward or reverse rotation. The home position of the paper discharge tray 12 and the height at the time of movement are detected by the lever 13 that can be rotated in the vertical direction and the paper surface sensors 32 and 33. When the paper discharge tray 12 is full of paper, the lower limit sensor 34 detects it. Is done. Further, when the moving roller 7 is pushed up by the paper discharge tray 12 when the paper discharge tray 12 is raised, the upper limit switch 31 is turned off, the rotation of the vertical motor 51 is stopped, and the paper discharge tray 12 is damaged by overrun. It is preventing.

  Next, the configuration of the control circuit will be described with reference to FIG.

  Signals from the switches and sensors in the sheet post-processing apparatus are input to the CPU 70 via the I / O interface. In accordance with the input signal, the CPU 70 moves up and down the motor 51 for raising and lowering the tray, the shift motor 52 for shifting the tray, the branch solenoid 53 for the branch claw 8, the tapping solenoid 30 that drives the return roller 5, the upper transport roller 2 and the like. A conveyance motor 54 for driving the lower conveyance roller 4, a paper discharge motor 55 for driving the return roller 5 and the paper discharge roller 6, a staple motor 56 for driving the staple device 11, a discharge motor 57 for driving the discharge belt 10, and a jogger fence A jogger motor 26 for moving 9 and a stapler moving motor 27 for moving the stapling apparatus 11 are rotated. The pulse signal of the transport motor 54 is input to the CPU 70 and counted, and the hit solenoid 30 is controlled according to this count. The sheet alignment control means includes a CPU 70 and an operation program for the CPU 70.

  Regarding the operation of the present embodiment having the above-described configuration, first, the operation when the non-staple mode in which stapling is not performed is selected will be described.

  When the copied paper is sent out from the copying machine A, the paper is sent by the entrance roller 1 and the upper transport roller 2 and is discharged onto the paper discharge tray 12 by the discharge roller 3. The alignment rollers 7 align the sheets in the vertical direction and are stacked on the sheet discharge tray 12. At this time, the closing roller 7 is decelerated when the paper discharge sensor 38 detects the trailing edge of the paper, thereby improving the stacking property.

  Then, when the copied paper is sequentially discharged to the paper discharge tray 12, the paper surface lever 13 is raised to operate the paper surface sensor 33, and the vertical motor 51 is rotated by the output signal of the paper surface sensor 33 to discharge the paper. Keep the tray 12 at the proper height at all times. In the sort and stack modes, the shift motor 52 is rotated by the command signal output from the control panel (not shown) of the copying machine A, and the discharge tray 12 is shifted. Sort until the job ends. At the end of the job, the discharge tray 12 is lowered (for example, about 30 mm).

  Next, a case where the non-punch mode and the stapling mode for stapling are selected will be described.

  When the staple mode is selected, as shown in FIG. 2, the jogger fence 9 moves from the home position and stands by at a position (about 7 mm) away from the paper width. When the sheet is transported by the lower transport roller 4 driven by the transport motor 54 and the rear end of the sheet passes the paper discharge sensor 37, the jogger fence 9 is jogged inward (about 5 mm) from the standby position (as indicated by the arrow in FIG. 2). Reciprocating motion in the direction shown). Further, the paper discharge sensor 37 detects that when the trailing edge of the paper passes, and inputs the signal to the CPU 70. As a result, the CPU 70 counts the pulses transmitted from the carry motor 54 from the time when this signal is received, and turns on the strike solenoid 30 when a predetermined number of pulses have been counted. The return roller 5 performs a pendulum motion by turning on / off the hitting solenoid 30, returns the sheet in the direction in which the sheet was struck when it is turned on, and abuts against the rear end fence 19 to perform vertical alignment of the sheet.

  At this time, every time the paper stored in the staple tray 21 passes the entrance sensor 36 or the paper discharge sensor 37, the signal is input to the CPU 70, and the number of papers is counted.

  After a predetermined time has elapsed after the hitting solenoid 30 is turned off, the jogger fence 9 is moved inward (about 2 mm) by the jogger motor 26 and stopped temporarily, and the paper horizontal alignment is completed. Thereafter, the jogger fence 9 returns (about 7 mm) and waits for the next sheet to arrive. This operation is performed up to the last page. On the last page, jogging is performed again (about 7 mm), and both ends of the sheet bundle are pressed to prepare for the stapling operation. After a predetermined time elapses, the stapling device 11 is operated and a closing process is performed. At this time, if a plurality of bindings are designated, after one binding process is completed, the stapler moving motor 27 is driven, and the stapling device 11 is moved to an appropriate position along the rear end of the sheet, so that the second position. The binding process is performed.

  When the binding process is completed in this manner, the discharge motor 57 is rotated in FIG. 5 to drive the discharge belt 10. At this time, the paper discharge motor 55 for the discharge roller 3 also starts to rotate to receive the sheet bundle lifted by the discharge claw 10a. At this time, the jogger fence 9 is controlled so that the operation differs depending on the size and the number of sheets to be bound. For example, when the number of sheets to be bound is smaller than the set sheet or smaller than the set size, the trailing edge of the sheet bundle is hooked and conveyed by the discharge claw 10a while holding the sheet bundle by the jogger fence 9.

  Then, the jogger fence 9 is retracted (about 2 mm) after a predetermined pulse by the discharge belt home sensor 39, and the restriction on the paper by the jogger fence 9 is released. The number of the predetermined pulses is set after the discharge claw 10a collides with the rear end of the sheet bundle and passes through the front end of the jogger fence 9. If the number of sheets to be bound is larger than the set number or larger than the set size, the jogger fence 9 is retracted (about 2 mm) in advance and discharged. In any case, when the sheet bundle passes through the jogger fence 9, the jogger fence 9 further moves (about 5 mm) and returns to the standby position to prepare for the next sheet. It is also possible to adjust the binding force according to the distance of the jogger fence 9 to the paper. The above series of operations is repeated until the last job.

  Next, the configuration of the paper discharge device 60 according to the present embodiment will be described with reference to FIGS. FIG. 8 is a side view for explaining the structure of the main part of the paper discharge device, FIG. 9 is a front view for explaining the structure of the roller portion of the paper discharge device, and FIG. FIG. 11 is an explanatory view of the main part of the paper discharge device when discharging the guide and the guide roller.

The paper discharge device 60 discharges the paper P to the staple tray 21 serving as a stacking unit, and discharges the driving roller 100 (discharge roller 6 in FIG. 2) for rear end alignment at the rear end fence 19; A paper discharge roller pair which is a paper discharge means composed of a driven roller 103 which rotates following the rotation of the discharge drive roller 100, a guide roller 101 provided coaxially with the paper discharge drive roller 100, and a discharge roller The rear end in the transport direction of the paper P discharged from the paper roller pair 100, 103 is blocked by its discharge port (discharge side of the nip) so that it does not enter the nip of the paper discharge roller pair 100, 103. And a paper rear end guide 102 as guide means for guiding P in the direction of the rear end fence 19. As described above, the paper discharge device 60 includes a paper discharge unit having at least one pair of paper discharge rollers including the paper discharge driving roller 100 and the driven roller 103, and a sheet that has passed through the paper discharge unit. And a paper trailing edge guide 102 for closing the paper conveyance path so as not to return to the nip.

The paper discharge drive roller 100 of the paper discharge device 60 of this example is provided in the center of the rotating shaft 110 with two axially spaced apart, and the driven roller 103 is also the outer periphery of the two paper discharge drive rollers 100. And two are provided so that the outer periphery may contact, respectively. The two driven rollers 103 are rotatably supported by the support shaft 111, and the support shaft 111 is elastically pressed in the direction of the rotation shaft 110 by the coil spring 104, and the outer periphery of each driven roller 103 is each discharge driving roller 100. It is comprised so that it may contact the outer periphery of this reliably and may be driven and rotated reliably.

  The guide roller 101 is formed of a low friction member such as a thermoplastic resin, and is pivotally supported on the rotary shaft 110 so as to be positioned outside the two paper discharge driving rollers 100. Three are provided at intervals in the axial direction. Each guide roller 101 has a diameter that is the same as or slightly larger than that of the paper discharge drive roller 100, and has a substantially H-shaped radial cross section.

  In addition, six paper rear end guides 102 are provided, and the lower end edge 102a of each paper rear end guide 102 enters the recess 101a of each guide roller 101. Each sheet trailing edge guide 102 is configured to rotate around a fulcrum A. A side end portion 102b on the sheet discharge (conveyance) direction side (upper left side in FIG. 8) of each sheet rear end guide 102 is positioned in a shape protruding outward in the discharge direction from the nip portion of the discharge roller pair 100, 103. The lower edge 102 a of each paper trailing edge guide 102 is positioned so as to enter the recess of the guide roller 101.

  The side end portion 102b of the paper trailing edge guide 102 is set so as not to protrude from the outer periphery of the paper discharge driving roller 100 to the paper stacking side (staple tray 21 side). Each paper trailing edge guide 102 is pushed up around the fulcrum A to the position shown in FIG. 11 by the paper P conveyed by the paper discharge driving roller 100, and released from being pushed up by the paper P after the paper trailing edge has passed. It returns to the position shown in FIG. The returning operation of each sheet trailing edge guide 102 is performed by the weight of the sheet trailing edge guide 102.

  With this configuration, when the paper P is discharged through the paper discharge roller pair of the paper discharge driving roller 100 and the driven roller 103, the paper discharge device 60 causes each paper trailing edge guide 102 to support the fulcrum A with the paper P. It rotates clockwise around the center and is positioned as shown in FIG. When the paper P is discharged from the paper discharge roller pair 100, 103, each paper rear end guide 102 rotates counterclockwise around the fulcrum A and returns as shown in FIG. 102a protrudes from the nip portion of the discharge roller pair toward the paper stacking side.

  As a result, the rear end in the transport direction of the paper P sent from the nip portion of the paper discharge roller pair 100, 103 is discharged by the side end 102b of each paper rear end guide 102 when the return roller 5 switches back. Backflow to the roller 100 is prevented, and smooth entry to the rear end fence 19 side is possible.

  In particular, in the present embodiment, the paper trailing edge guide is shaped in consideration of the following.

That is, as shown in the operation explanatory diagrams of FIGS. 11 and 14, when the sheet is discharged, the sheet rear end guide 102 is connected to the side end portion 102b, which is a portion that closes the discharge side of the sheet conveyance path, and the discharge roller pair 100, The protruding portion 102c disposed between the nip N portion 103 and the nip N portion is regulated and pushed up by the sheet P in the vicinity of the nip N (FIG. 14B), and the posture is maintained (FIG. 14). (C)). The paper P in the vicinity of the nip N is strong and can support the paper trailing edge guide 102. Further, the bottom end 102d of the side end portion 102b of the paper trailing edge guide 102 is in a position retracted from the paper transport path so as not to hinder paper discharge. As described above, the paper rear end guide 102 includes the side end portion 102b formed by the portion on the paper discharge side, the protruding portion 102c positioned on the upstream side in the paper transport direction from the side end portion 102b, and the side end. An edge 102a positioned between the protruding portion 102c and the leading end 102d of the portion 102b on the discharge driving roller 100 side, and the sheet trailing edge guide 102 receives the sheet passing through the sheet discharging means. In order not to return to the nip N of the paper discharge means, the position between the closed position where the side end portion 102b blocks the paper conveyance path and the retreat position where the conveyance of the paper discharged by the paper discharge means is not hindered. Is supported movably. Moreover, as shown in FIGS. 12 and 14A, when the paper P enters the nip N of the paper discharge means with the paper trailing edge guide 102 in the closed position described above, the leading edge of the paper P is The sheet trailing edge guide 102 is not contacted with the protruding portion 102c but is brought into contact with and pressed against the edge 102a upstream of the nip N in the sheet conveyance direction, so that the sheet trailing edge guide 102 is moved to the position shown in FIGS. When the sheet trailing edge guide 102 is moved to the retracted position as shown in FIGS. 11, 14B, and 14C, the sheet is conveyed more than the leading edge of the sheet P. The sheet portion on the upstream side in the direction slides on the protruding portion 102c to hold the sheet trailing edge guide 102 in the retracted position, and the edge 102a and the leading edge 102d of the side edge portion 102b do not contact the sheet P. So that the trailing edge of the paper Is the id 102 is formed.

  As shown in FIGS. 12 and 14A, in the posture in which the paper trailing edge guide 102 is returned, the protruding portion 102c is configured such that the leading edge of the paper entering first comes into contact with the guide roller 101. As a result, the paper P can smoothly enter the nip N, and the paper P is not damaged such as scratches or breakage.

  That is, as shown in FIG. 13, when the paper P enters the nip N, the front end of the paper comes into contact with the paper rear end guide 102 before the guide roller 101 (FIG. 13A). The leading edge of the sheet is pushed down by 102 (FIG. 13B), the contact angle with the guide roller 101 increases, and the leading edge of the sheet may be damaged, such as a scratch or breakage.

  Further, the fulcrum A, which is the rotation center of the paper trailing edge guide 102, is provided in the vicinity of the nip N in this example, and is arranged so as to minimize the moment load applied to the protruding portion 102c of the paper trailing edge guide 102. Yes. Thereby, when the paper P pushes up the paper trailing edge guide 102, the load applied to the paper P can be reduced, and damage such as scratches or breakage of the paper can be prevented.

  The present invention relates to a paper discharge apparatus provided in a post-processing apparatus that is provided integrally with or attached to an image forming apparatus such as a copying machine, a printer, or a facsimile machine, or that performs post-processing on paper discharged from the image forming apparatus. The present invention is effective when applied to an image forming apparatus provided with the paper discharge device.

1 is a schematic configuration diagram of a sheet post-processing apparatus including an embodiment of a sheet discharge apparatus of the present invention. The perspective view which shows the principal part of the jogger fence part in this embodiment Explanatory drawing of the lower structure of the jogger fence part in this embodiment The perspective view which shows the principal part of the jogger fence part and stapling apparatus in this embodiment. The perspective view which shows the principal part of the discharge | release belt part in this embodiment, and expands and shows the part. The perspective view which shows the principal part of the paper discharge tray part in this embodiment, and expands and shows the part. The block diagram which shows schematic structure of the control circuit in this embodiment Side view for explaining the configuration of the main part of the paper discharge device of the present embodiment Front view for explaining a configuration of a roller portion in the paper discharge device of the present embodiment. The perspective view which shows the paper trailing edge guide and guide roller part in the paper discharge apparatus of this embodiment Explanatory drawing at the time of discharge of the main part in the paper discharge device of this embodiment Explanatory drawing at the time of paper intrusion of the main part in the paper discharge device of this embodiment (A), (b) is explanatory drawing of the subject in the conventional paper discharge apparatus. (A)-(c) is explanatory drawing of the paper discharge operation | movement of the principal part in the paper discharge apparatus of this embodiment. (A)-(e) is explanatory drawing of a structure and operation | movement of the principal part of the conventional paper discharge apparatus.

Explanation of symbols

60 paper discharge device 100 discharging driving roller 103 driven roller 102 paper guide rail 102a paper trailing guide edge 102b paper guide rail side edge 102c paper guide rail of the side end of the projecting portion 102d paper guide rail earlier end P paper N nip that put the part

Claims (2)

A sheet discharge means having at least one pair of the pairs of output rollers forming Ru and a discharging driving roller and the driven roller, the conveyance sheet having passed through the the paper discharge means is the paper so as not to return to the nip of the paper discharging means In a paper discharge device having a paper trailing edge guide for closing a path,
The paper rear end guide includes a side end formed by a portion on the paper discharge side, a protruding portion located upstream of the side end in the paper transport direction, and a discharge driving roller side of the side end. And an edge located between the tip of the protrusion and the protruding portion,
The paper trailing edge guide includes a closed position where the side edge blocks the paper conveyance path so that the paper that has passed through the paper discharging means does not return to the nip of the paper discharging means, and the paper discharging means. It is supported so as to be movable between a retreat position that does not hinder the conveyance of discharged paper,
When the paper trailing edge guide is in the closed position and the paper enters the nip of the paper discharge means, the leading edge of the paper does not hit the protruding portion and is upstream of the nip in the paper conveyance direction. The paper trailing edge guide is moved to the retracted position by abutting and pressing the edge portion on the side, and when the paper trailing edge guide is moved to the retracted position, The paper portion on the upstream side in the paper transport direction is in sliding contact with the protruding portion to hold the paper trailing edge guide at the retracted position, and the edge and the tip of the side edge are not in contact with the paper. the paper discharge detection device, characterized in that the sheet trailing end guide are formed. An image forming apparatus comprising the paper discharge device according to claim 1 .

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