JP2017043475A - Sheet processing device and image formation apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform stable sheet conveyance by suppressing flapping of a sheet and bend of the sheet due to the flapping when the sheet conveyed by switch back is the relatively-long sheet.SOLUTION: A sheet processing device includes: a conveyance path 42 to a first processing tray 54; a branch path 70 which branches from the conveyance path 42 and conveys the sheet to a stacker 84; a conveyance roller 44 which can convey the sheet to the first processing tray 54 or the branch path 70; a branch roller 72 of the branch path 70 which can convey the sheet to the stacker 84 or the conveyance path 42; and a control part which recognizes the conveyance length of the sheet and controls the rollers, and performs the stand-by conveyance of conveying the sheet together with the following sheet to the first processing tray 54 by switch back conveyance for stand-by in the branch path 70, and the second tray conveyance of conveying the sheet via the branch path 70 to the stacker 84 by the switch back conveyance. When the conveyed sheet length is longer than a standard, the switch back conveyance speed is made slower in comparison to the case where the sheet length is shorter than the standard.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a processing apparatus that processes a sheet conveyed from an image forming apparatus such as a copying machine or a printer, and more particularly to an improvement of a sheet processing apparatus that enables stable sheet conveyance when conveying sheets to different trays. .

  Generally, processing apparatuses that perform binding by aligning sheets conveyed from an image forming apparatus are widely known. Also known are end-face binding that accepts sheets in different positions and binds the end faces of sheets, and saddle-stitching processing that binds the approximate center in the sheet transport direction, and stops transporting subsequent sheets as much as possible. It is also shown that the preceding sheet in the apparatus waits and stays in the apparatus without being carried and is conveyed to the tray together with the subsequent sheet.

  For example, Patent Document 1 shows a straight path that guides a sheet sent from an image forming apparatus to a first tray, and a branch path that branches from this path and guides it to a second tray. The first tray is provided with an end face binding unit that binds to the end face of the sheet, and the second tray is provided with a saddle stitching unit that binds the middle in the sheet conveying direction.

In this document, so-called standby conveyance is performed, in which the subsequent sheet is temporarily switched back to the branch path to wait for securing the time for the first tray to be bound, and then conveyed together with the subsequent sheet. Is shown. In order to receive the sheet in the second tray, the sheet is once transported to the first tray side, then switched back to the branch path, and transported through the branch path. Thus, by using the branch path branched from the transport path as the standby path or as the carry-in path path to the second tray, the path becomes compact and the subsequent sheet can be processed without stopping.

Japanese Patent No. 5248785

  As described above, the first tray and the second tray are arranged at different positions, and the received sheet is subjected to end-face binding and saddle-stitching, respectively. In general, end-face binding is used to bind the end face of the sheet. It is frequently used for relatively short sheets such as B5, A4, and letter sizes, and is required to be processed at high speed. On the other hand, saddle stitching for binding the middle of the sheet conveyance direction is frequently used for sheets having a relatively long length, for example, B4, legal, and A3 sizes, and the time required for processing tends to be relatively gentle because of the long sheet.

  For this reason, in the apparatus shown in Patent Document 1, when a sheet to be stored in the first tray and subjected to end-face binding is switched back and temporarily waited in the branch path, the distance of the switchback is set for a short sheet. Therefore, even if the sheet is conveyed at a high speed, the sheet is not bent or shaken at the time of the switchback conveyance so that the alignment is not deteriorated and the sheet jam is not often caused. On the other hand, if the sheet that is stored in the second tray at the same speed and that is saddle-stitched is switched back, a relatively long distance is switched back, so that the sheet is bent and fluttered and stacked. There is a risk that the alignment may deteriorate and sheet jam may occur.

  This invention reduces the occurrence of sheet jamming by preventing the sheet from being bent or fluttered even when a relatively long sheet is conveyed when switched back and conveyed to a different tray. The issue is to provide a few devices.

The present invention adopts the following configuration in order to solve the above problems.
A transport path for receiving the sheet and transporting the sheet to the first tray; a branch path for branching from the transport path to transport the sheet to the second tray; and a downstream side of the branch position between the transport path and the branch path. A first conveying roller positioned on the conveying path and capable of conveying a sheet in either direction of the first tray or the branch path; and a sheet positioned on the branch path in any direction of the second tray or the conveying path. A second conveyance roller capable of conveyance, and a controller for recognizing the conveyance length of the sheet conveyed by the first conveyance roller and the second conveyance roller and controlling the first conveyance roller and the second conveyance roller,
The control unit includes a standby conveyance in which a sheet conveyed on the conveyance path passes through the branch position, is switched back and temporarily waits on the branch path, and is conveyed to the first tray together with a subsequent sheet, and the conveyance path After the sheet conveyed through the branch position, switchback conveyance is performed, and the second tray is conveyed to the second tray via the branch path. The conveyance speed of the switchback conveyance is determined by the sheet conveyance length. This is a sheet processing apparatus to be different.

According to the present invention, when switchback transporting to different trays and carrying it in, it is possible to reduce bending and fluttering of the sheet even when transporting a relatively long sheet, thereby preventing deterioration in alignment and preventing sheet jamming. A device with less generation can be provided.

1 is an explanatory diagram showing an overall configuration in which an image forming apparatus and a sheet processing apparatus according to the present invention are combined. 1 is an overall explanatory view of a sheet processing apparatus including an end face binding unit and a saddle stitching unit according to the present invention. FIG. Explanatory side surface explanatory drawing of an end surface binding part periphery. Drive explanatory drawing of a conveyance roller, an exit roller, and a branch roller. Explanatory drawing of the raising / lowering mechanism of a 1st discharge tray (discharge tray) and the stop position of the tray. FIG. 6A is an explanatory diagram of auxiliary guide driving for a sheet that expands and contracts on the first paper discharge tray, and FIG. FIG. 6B is a partially enlarged perspective view of the auxiliary guide. FIG. 7A is an explanatory diagram of a standby conveyance operation of sheets and an auxiliary guide position for storing them in a first processing tray (first tray), and FIG. 7A is an explanatory diagram of starting switchback in the conveyance path. FIG. 7B is an explanatory diagram illustrating a state in which the transfer route is continuously transferred from the transfer route. FIG. 8A is an explanatory diagram of the standby conveyance operation following FIG. 7, and FIG. 8A is an explanatory diagram in which the preceding sheet is made to wait on the branch path and the next sheet is carried in. FIG. 8B is an explanatory diagram in which the conveyance of the next sheet and the waiting preceding sheet is continuously started. FIG. 9A is an explanatory diagram of the standby conveyance operation following FIG. 8, and FIG. 9A is an explanatory diagram of a state in which the preceding sheet and the next sheet are combined and stored in the first processing tray. FIG. 9B is an explanatory diagram of a state where the third sheet is continuously carried in. FIG. 10A is an explanatory diagram of the second tray conveyance and auxiliary guide position for storing sheets in the stacker (second tray) for saddle stitching processing, and FIG. 10A is an explanatory diagram for starting switchback in the conveyance path. FIG. 10B is an explanatory diagram illustrating a state where the switchback conveyance is continuously performed from the conveyance route to the branch route at a low speed. FIG. 11A is an explanatory diagram of the second tray conveying operation following FIG. 10, and FIG. 11A is an explanatory diagram in which the preceding sheet conveys the branch path and accepts the next sheet to perform the passing conveyance. FIG. 11B is an explanatory diagram in which the preceding sheet is stored in a stacker (second processing tray) and the next sheet is conveyed. FIG. 12A is an explanatory diagram of a modified example of the standby conveyance operation of sheets and the auxiliary guide position for storing them in the first processing tray shown in FIG. 7, and FIG. 12A is an explanatory diagram for starting switchback in the conveyance path. FIG. 12B is an explanatory diagram of a state in which the conveyance route is continuously conveyed from the conveyance route. Explanatory drawing of the modification which added the 2nd tray conveyance for storing a sheet | seat in a stacker (2nd tray) for the saddle stitching process shown in FIG. 10, an auxiliary guide position, and the 1st discharge tray (discharge tray) position. FIG. 13A is an explanatory diagram for starting switchback in the transport path. FIG. 13B is a diagram illustrating a state in which the conveyance route is continuously conveyed from the conveyance route. Explanatory drawing which changes the conveyance speed at the time of switchback conveyance by the end surface binding by an end surface binding unit, and the saddle stitching by a saddle stitching unit. FIG. 14 is a flow explanatory diagram for changing the transport speed during switchback transport according to the transport length. Explanatory drawing of the control structure in the whole structure of FIG.

  The present invention will be described in detail below based on the preferred embodiments of the present invention shown in the drawings. FIG. 1 is an overall configuration diagram showing an image forming system including an image forming apparatus A and a sheet processing apparatus B according to the present invention, and FIG. 2 is an explanatory diagram of a detailed configuration of the sheet processing apparatus B.

[Configuration of image forming system]
The image forming system shown in FIG. 1 includes an image forming apparatus A and a sheet processing apparatus B. Then, a carry-in port 30 of the sheet processing apparatus B is connected to the main body discharge port 3 of the image forming apparatus A, and the sheets formed with the image by the image forming apparatus A are stapled by the sheet processing apparatus B and the first discharge tray 24 or It is configured to be stored in the second paper discharge tray 26. Further, an escape tray 22 that directly stores sheets without performing binding processing is disposed above the first paper discharge tray 24.

[Configuration of Image Forming Apparatus]
The image forming apparatus A will be described with reference to FIG. The image forming apparatus A is configured to send a sheet from the paper supply unit 1 to the image forming unit 2, print the sheet on the image forming unit 2, and then discharge the sheet from the main body discharge port 3. The sheet feeding unit 1 stores sheets of a plurality of sizes in sheet feeding cassettes 1 a and 1 b, and separates specified sheets one by one and feeds them to the image forming unit 2.

In the image forming unit 2, for example, an electrostatic drum 4, a print head (laser light emitter) 5, a developing device 6, a transfer charger 7, and a fixing device 8 are arranged around the electrostatic drum 4. The image forming unit 2 forms an electrostatic latent image on the electrostatic drum 4 by the laser light emitter 5, attaches toner to the developer drum 6, transfers the image onto the sheet by the transfer charger 7, and fixes the image on the sheet. In step 8, the image is formed by heating and fixing. The sheets on which images are formed in this way are sequentially carried out from the main body discharge port 3. 9 is a circulation path. A sheet printed on the front side from the fixing device 8 is reversed on the front and back via the switchback path 10 and then fed again to the image forming unit 2 to print on the back side of the sheet. This is the print path. The sheet printed on both sides in this way is turned upside down by the switchback path 10 and then carried out from the main body discharge port 3.

  11 is an image reading apparatus, which scans a document sheet set on a platen 12 with a scanning unit 13 and electrically reads it with a photoelectric conversion element (not shown). The image data is digitally processed by an image processing unit, for example, and then transferred to the data storage unit 14 to send an image signal to the laser emitter 5. 15 is a document feeder, which feeds document sheets stored in the document stacker 16 to the platen 12.

  The image forming apparatus A configured as described above is provided with an image forming control unit 200 shown in FIG. 12, and image forming conditions such as sheet size designation, color / monochrome printing designation, and number of copies to be printed from the control panel 18 via the input unit 203. Printing conditions such as designation, single-sided / double-sided printing designation, and enlargement / reduction printing designation are set. In the image forming apparatus A, image data read by the scan unit 13 or image data transferred from an external network is accumulated in the data storage unit 17. The image data is transferred from the data storage unit 17 to the buffer memory 19, and the data signal is transferred from the buffer memory 19 to the laser emitter 5 sequentially.

  From the control panel 18, sheet processing conditions are also input and specified simultaneously with the image forming conditions such as single-sided / double-sided printing, enlargement / reduction printing, and monochrome / color printing described above. As the sheet processing condition, for example, “print-out mode”, “end face binding mode”, “saddle stitching mode”, or the like is set. These processing conditions will be described later.

[Configuration of Sheet Processing Apparatus B]
As shown in FIG. 1 and FIG. 2, the sheet processing apparatus B accumulates a sheet carry-in port 30 provided on one side of the apparatus frame 20 and a single sheet or a relatively thick sheet provided on the opposite side. An escape tray 22 is disposed. Below the escape tray 22 is positioned a first paper discharge tray 24 as a paper discharge tray that can be moved up and down to collect sheets that have undergone end-face stitching and a relatively large amount of sheets. Further, below the first paper discharge tray 24, there is provided a second paper discharge tray 26 for collecting the saddle stitched or folded sheets. In the present invention, the end surface indicates the surface around the end of the sheet, that is, the front and back surfaces of the sheet edge.

[Sheet transport path]
A conveyance path 42 extending substantially linearly from the carry-in path 32 to the first processing tray outlet 50 is disposed from the carry-in entrance 30 of the sheet processing apparatus B. A punch unit 31 is provided in the carry-in path 32, and performs punching in the middle of the sheet end face and, if necessary, in the transport direction. A punch waste box 31b for accumulating punch waste generated during the punching process is detachably provided in the apparatus frame 20 below the carry-in path 32 of the punch unit 31.

  A carry-in roller 34 that conveys the sheet is disposed downstream of the punch unit 31 and conveys the sheet at high speed. A conveyance path 42 downstream of the carry-in roller 34 is provided with a conveyance roller 44 capable of rotating forward and backward to guide the sheet to the first processing tray 54 as a first tray and the first paper discharge tray 24 on the downstream side. Yes. Behind the conveyance roller 44 is a sheet conveyance path outlet 46.

On the downstream side of the conveyance path outlet 46, an outlet roller 48 capable of forward and reverse rotation is provided. The exit roller 48 switches back the sheet and conveys the sheet to the first processing tray 54, discharges the sheet straight to the first discharge tray 24, or is stacked on the first processing tray 54 and end-face binding processing. The bundle of sheets thus discharged is discharged to the first discharge tray 24.

[Escape route, branch route]
Further, the conveyance path 42 includes an escape path 38 for guiding sheets to the escape tray 22 and a stacker 84 (also a second processing tray) serving as a second tray for performing saddle stitching processing and folding processing of relatively long sheets. The branch path 70 is branched at the branch position 36. At this branch position 36, a path switching gate for selecting whether the sheet is transported to the transport path 42 as it is, transported to the escape path 38, or switched back on the transport path 42 and guided to the branch path 70. 37 is provided.
The escape path 38 is provided with an escape roller 39 for conveying the sheet and an escape outlet roller 40 for discharging the sheet to the escape tray 22.

[End face binding portion 60]
By the way, a first processing tray 54 as a first tray is provided below the conveyance path outlet 46 of the conveyance path 42, and an end surface for binding an end surface of the sheets temporarily accumulated on the first processing tray 54 at the lower end side thereof. The binding part 60 is located. The end face binding portion 60 will be described later with reference to FIG.
[Saddle Stitcher 80]
On the other hand, a relatively long sheet is once transported along the transport path 42 toward the first processing tray 54 and transported to the downstream side of the switching gate 37, and then switched back and transported to the branch path 70 for branch exit. The stacker 76 accumulates in a stacker 84 (second processing tray) as a second tray. As shown in FIG. 2, at the branch outlet 76, every time a sheet is loaded from the branch outlet roller 74 to the stacker 84, the sheet is urged to the left side in the drawing to prevent collision between the trailing edge of the preceding sheet and the leading edge of the next sheet. A flapper 78 is provided. The stacker 84 is provided with a saddle stitching portion 80 for binding the middle in the sheet conveyance direction.

[Stacker (second tray / second processing tray) and surrounding area]
The stacker 84 is provided with a stopper 85 that defines a sheet carry-in position. The stopper 85 moves in the direction of the arrow shown in the figure by driving a moving belt stretched around the upper pulley 86 and the lower pulley 87 by a stopper moving motor 85M on the side of the stacker 84. The position of the stopper 85 includes a position where the trailing edge of the sheet can be changed by the change flapper 78 when the sheet is carried into the stacker 84, a position where the saddle stitching unit 82 performs saddle stitching at a substantially center in the sheet conveyance direction, and The saddle-stitched position is pushed by a folding blade 94 that reciprocates to the pair of folding rollers 92 and stopped at a position where the sheet bundle is folded in half.
In addition, a saddle stitch aligning plate 81 is provided above and below the folding roller 92 to perform an aligning operation by pressing both side edges of the sheet from the sheet width direction every time the sheet stacker 84 is loaded.

[Saddle stitching unit 82]
The saddle stitching portion 80 is provided with an anvil 83 which is provided at a position opposite to a staple of a bundle of sheets, for example, driven by a driver in the saddle stitching unit 82 and bends a leg portion of the staple needle. Since the saddle stitching unit 82 is already widely known, a description thereof will be omitted. However, as a binding means, not only the staple needle is passed through the sheet bundle, but also an adhesive is provided at the center in the sheet conveying direction. It may be a mechanism that coats and pastes the sheets into a bundle.

[Around the second paper output tray 26]
The sheet bundle bound by the saddle stitching unit 82 is folded in half by a folding roller 92 and a folding blade 94 that pushes the sheet bundle into the folding roller 92 and a bundle discharge roller 96 positioned downstream thereof. As a result, the sheet is discharged to the second discharge tray 26. The second discharge tray 26 is provided with a rotatable roller at the front end for dropping a folded sheet bundle that is folded and discharged with the back side as the front end side to the second discharge tray 26, and is a swingable press roller. 102, and a presser lever 104 that is pressed from above so that the bundle of folded folded sheets does not spread. The folded sheet bundle is opened by the presser roller 102 and the presser lever 104, and the deterioration of the accumulation property is reduced.

[Details of branch position 36 and end face binding portion 60]
Here, the branch position 36 and the end surface binding portion 60 will be further described with reference to FIG. As described above, here, the carry-in path 32 in which the carry-in roller 34 is arranged from the carry-in entrance 30, the conveyance path 42 extending linearly from the conveyance path 42 toward the first processing tray 54, and the escape path extending from the conveyance path 42 upward in the figure. 38 and a branch path 70 for guiding a sheet extending downward and curved to the stacker 84 is shown. At the branch position 36, there is a change flapper 78 for selectively guiding the sheet on the carry-in path 32 to the escape path 38, the transport path 42, or the switch path transporting the transport path 42 in the branch path 70. Has been placed.

In this embodiment, for example, as shown in FIG. 3, the escape path 38 is closed at the solid line position, and the sheet is guided from the carry-in path 32 to the transport path 42. It is shown that the sheet conveyed from 32 is guided to the escape path 38, and the sheet that is switched back along the conveyance path 42 is guided to the branch path 70.

  In the transport path 42 described above, a transport roller 44 that rotates in the forward and reverse directions and is in contact with and away from each other is disposed immediately before the transport path exit 46 that is the final end. That is, the conveyance roller 44 can convey the sheet to the first processing tray 54 side by one-way rotation with the pressure contact state, and switchback conveyance in the opposite direction by the other rotation.

[Switchback transport]
This switchback conveyance is performed by rotating the conveyance roller 44 in the other direction after the sheet sensor 42S disposed immediately after the switching gate 37 of the conveyance path 42 detects the passage of the trailing edge of the sheet. At the time of the other rotation, the switching gate 37 is moved to a position (broken line position in FIG. 3) that closes the carry-in path 32, whereby the sheet is conveyed to the branch path 70 and taken over by the branch roller 72. When the trailing end reaches a predetermined position, the branch roller 72 is stopped, and the sheet is placed in a standby state on the branch path 70.

  By the way, on the downstream side of the transport roller 44 and at the first processing tray outlet 50 (the outlet of the first processing tray 54), there are disposed outlet rollers 48 that are forwardly and reversely rotated and separated from each other. The exit roller 48 includes an exit upper roller 48 a and an exit lower roller 48 b, which rotate in one direction while being pressed against each other, and cooperate with the transport roller 44 to form a sheet on the first discharge tray 24. The sheet is conveyed to the branch path 70 by the other rotation. Further, the exit roller 48 is also used when the sheets stacked on the first processing tray 54 to be bundled are discharged to the first paper discharge tray 24 in cooperation with the movement of a reference surface 57 described later.

[Accumulation on the first processing tray 54]
Here, the accumulation of sheets on the first processing tray 54 will be described. In the accumulation on the first processing tray 54, the sheet discharged from the conveying roller 44 is conveyed to the right side in FIG. 3 by the other rotation of the outlet roller 48 positioned on the downstream side. The transported sheet 56 is transported by rotating the scraping roller 56 around which the belt 146 with protrusions is wound counterclockwise. By this transfer, the front end of the sheet in the conveyance direction comes into contact with the reference surface 57 serving as a binding reference for the other surface and stops. At this time, the scraping roller 56 slides on the sheet and prevents the sheet tip from buckling after contacting the reference surface.

[Movement and binding processing of end face binding unit 62]
When the sheet is discharged from the conveying roller 44, the sheet is sent to the reference surface 57 and stacked on the first processing tray 54 by the rotation of the exit roller 48 and the scooping roller. In accordance with this stacking operation, the aligning plate 58 is brought into contact with both sides in the sheet width direction to align the sheet with the center in the width direction of the first processing tray 54. This process is repeated until the designated number of stacks and alignments are bundled. When the designated number is reached, the end face binding unit 62 that moves the end face of the sheet in the sheet width direction on the moving table 63 is moved to a desired binding position. This movement is made by guiding the moving pin 62b of the end face binding unit 62 into the illustrated groove rail provided on the moving base 63 in the sheet width direction.

Since the binding processing of the end surface binding unit 62 is already known, the description thereof will be omitted. However, when the end surface binding unit 62 stops at the specified binding position, the end surface binding motor 62M is driven to rotate, and a driver (not shown) is moved to move the staple. The staples are driven into a bundle of sheets, and the staple needles that have been driven are folded by an anvil and bound. This binding process is performed at a plurality of positions on the end face of the sheet corner and the end face in the width direction.

[Ejecting edge-bound sheets]
The sheet bundle that has been subjected to the binding process by the end surface binding unit 62 is moved by the reference plane moving belt 64 in the counterclockwise direction of the reference plane moving belt 64 spanned between the right pulley 65 and the left pulley 66 below the first processing tray 54. The reference surface 57 connected to the belt 64 moves in the left direction in the figure, thereby pushing out the binding end surface side of the sheet bundle toward the first paper discharge tray 24. Along with this extrusion, the sheet bundle bound by the outlet roller 48 disposed at the outlet of the first processing tray 54 is pressed from the front and back, and the sheet bundle bound to the first paper discharge tray 24 is discharged by the clockwise rotation.

[Raising and lowering the first discharge tray 24]
The first paper discharge tray 24 for collecting the sheet bundle will be described. As shown in FIG. 3, the first paper discharge tray 24 is disposed at substantially the same inclination angle as the first processing tray 54, and the binding sheet bundle discharged from the first processing tray 54 and the transport roller 42 through the transport path 42. The sheets discharged by the exit roller 48 are also collected.
On the bottom surface side of the first paper discharge tray 24, a lift motor 24M that lifts and lowers the first paper discharge tray 24 is provided, and this drive is transmitted to the lift pinion 109. The elevating pinion 109 is engaged with an elevating rack 107 that is fixed up and down on both sides of the standing surface 28 of the apparatus frame 20. Although not specifically shown, the elevator rail is guided up and down by an elevating rail provided on the standing surface 28 of the first paper discharge tray 24.

As shown in FIG. 3, an auxiliary guide 110 is provided that extends from below the first processing tray 54 to the upper surface of the first paper discharge tray 24 and guides the lower surface of the sheet conveyed from the first processing tray 54. It has been. The configuration of the auxiliary guide 110 will be described later with reference to FIG.

Incidentally, the position of the first paper discharge tray 24 or the position of the sheets stacked on the first paper discharge tray 24 is detected by a paper surface sensor 24S provided on the standing surface side. And when this paper surface sensor 24S detects, the raising / lowering motor 24M will be driven and the raising / lowering pinion 109 will rotate and it will descend | fall. In the state of FIG. 3, the upper surface of the first paper discharge tray 24 is detected by the paper surface sensor 24S, and the sheet bundle is lowered slightly from here to accept the sheet bundle. Accordingly, the upper surface of the exit position from the first processing tray 54 and the upper surface of the first paper discharge tray 24 are positioned with a step.

Next, the configuration of rotational driving and separation / contact of the conveying roller 44 and the outlet roller 48 will be described with reference to FIG.
[Rotation drive of transport upper roller 44a]
First, driving of the transport roller 44 including the transport upper roller 44a and the transport lower roller 44b is performed by a transport roller motor 44M. The transport roller motor 44M is composed of a hybrid type stepping motor, and a speed detection sensor 44S for detecting the rotational speed of the motor shaft is disposed. The driving of the conveying roller motor 44M is transmitted to the arm gear 126 via the transmission gears 120 and 122 and the transmission belt 124. The drive from the arm gear 126 is transmitted by the transmission belt 128 to the upper roller shaft 44 uj of the transport upper roller 44 a supported by the transport roller support arm 136.

[Separation of transport upper roller 44a]
Further, the transport upper roller 44a is attached so as to be rotated about the axis of the arm gear 126 so as to be separated from and in contact with the fixed transport lower roller 44b. This separation / contact is performed by a conveyance roller moving arm 130 having a rear sector gear attached to the shaft of the arm gear 126 and having a spring 134 attached to the tip of the movement arm on the front end side for urging the conveyance upper roller 44a. That is, by driving the transport roller moving arm motor 130M engaged with the rear fan gear forward and backward, the arrow that presses the transport lower roller 44b indicated by the arrow C in the release direction of the arrow O by one rotation and the arrow C by the other rotation. Move in the direction of pressure contact of C. The transport roller moving arm motor 130M is also constituted by a stepping motor, and the position of the transport roller moving arm 130 is detected by the transport roller moving arm sensor 130S.

[Rotation drive of lower conveying roller 44b, etc.]
The rotation of the lower conveying roller 44b is performed by transmitting the driving of the conveying roller motor 44M via the transmission gear 120 and the transmission belt 138 to the receiving gear 142 provided on the lower conveying roller shaft 44sj.
Further, the driving from the receiving gear 142 rotates the roller 56 by driving the gear 144 with a one-way clutch and the belt 146 with a projection that also functions as a transmission belt. Since the scraping roller 56 is transmitted via the one-way clutch-equipped gear 144, as described above, even if the receiving gear 142 rotates forward and backward, it rotates only in the direction indicated by the solid line in FIG. It is transferred only in the direction of the reference surface 57 of the processing tray 54.
The driving of the conveyance roller motor 44M is also transmitted to the lower branch roller shaft 72sj of the lower branch roller 72b of the branch roller 72 that conveys the sheet in the branch path 70 via the transmission gear 120 and the transmission belt 148.

[Speed setting of transport roller motor 44M]
With the above configuration, according to the forward / reverse rotation of the transport roller motor 44M, the transport roller 44 and the branching roller 72 are in one direction indicated by the solid line arrow in the figure and the other direction (switchback direction) in the direction indicated by the broken line arrow, Rotate in the direction of the reference plane 57. Further, the transport roller motor 44M is about 1100 mm / s when transporting the sheet to the first processing tray 54 side, and about 1100 mm / s or lower when performing switchback transport to the branch path 70 side. It can be arbitrarily set so that the sheet can be conveyed at a speed of about 600 mm / s. This speed is the rotation set speed from the start, and the average speed is lower than this set value, but in any case, the transport speed in the transport direction of the sheet, the sheet length, the transport mode of standby transport or second tray transport, etc. Is designed to be variable. This speed setting will be described later.

[Rotation drive of outlet upper roller 48a]
The exit roller 48 comprising the exit upper roller 48a and the exit lower roller 48b is driven by the exit roller motor 48M. The exit roller motor 48M is also composed of a hybrid stepping motor, and a speed detection sensor 48S for detecting the rotational speed of the motor shaft is similarly arranged. The drive of the exit roller motor 48M is transmitted to the exit arm gear 156 via the transmission gears 150 and 152 and the transmission belt 154. Drive from the exit arm gear 156 is transmitted by the transmission belt 158 to the exit upper roller shaft of the exit upper roller 48a supported by the exit roller support arm 166.

[Separation of roller 48a on exit, etc.]
The outlet upper roller 48a is attached so as to be rotated around the axis of the outlet arm gear 156 so as to be in contact with and away from the fixed lower outlet roller 48b. This separation / contact is performed by an exit roller moving arm 160 having a rear sector gear attached to the shaft of the exit arm gear 156 and having a spring 164 for biasing the exit upper roller 48a attached to the distal end side of the moving arm. . By driving the outlet roller moving arm motor 160M engaged with the rear fan gear in the forward and reverse directions, the release direction of the arrow O is rotated in one direction, and the arrow C is pressed against the outlet lower roller 48b in the arrow C by the other rotation. Move in the pressure direction. The exit roller moving arm motor 160M is also constituted by a stepping motor, and the position of the exit roller moving arm 160 is detected by the exit roller moving arm sensor 160S.
Further, the rotation of the outlet lower roller 48b is performed by transmitting the driving of the outlet roller motor 48M to the receiving gear 169 provided on the outlet lower roller shaft 48sj via the transmission gear 150 and the transmission belt 168.

[Speed setting of outlet roller motor 48M]
With the above configuration, the outlet roller 48 moves in one direction in the direction indicated by the solid line arrow and in the other direction in the direction indicated by the broken line arrow (on the first processing tray 54 after the sheet is discharged from the conveying roller 44). In the switchback direction to the reference plane 57). The exit roller motor 48M is approximately 1100 mm / s when handed over from the transport roller 44, and is approximately 600 mm / s when switched back toward the takeover reference surface. Is discharged to the first paper discharge tray 24 in cooperation with the movement of the reference surface 57, it can be set so that the sheet can be conveyed at a speed of about 300 mm / s. That is, the outlet roller motor 48M can set a speed in the range of about 1100 mm / s to about 300 mm / s.
In this embodiment, when the sheet is being conveyed by the conveyance roller 44 such as during switchback conveyance during standby conveyance, the drive motor is separated and interlocking is difficult. It is located at a separated position released from the lower roller 48b.

[Paper surface sensor 24S of first discharge tray 24]
The mechanism for raising and lowering the first discharge tray 24 has already been described with reference to FIG. 3, but the setting of the raising and lowering position will be described with reference to FIG. The raising / lowering position is set by detecting the paper surface of the paper surface sensor 24S or the upper surface of the first paper discharge tray 24. This paper surface sensor 24S is set by detecting a sensor flag 24f pivotally supported at one end. Is called. Further, an empty sensor 25 for detecting whether or not a sheet is placed is provided on the surface on which the first paper discharge tray 24 is placed. Accordingly, when the empty sensor 25 is ON, the paper surface sensor 24S detects the upper surface of the sheet, and when OFF, the height of the mounting surface on which the sheet is not mounted is detected. Will be.

[Raising / lowering position setting of first discharge tray 24]
Meanwhile, when the sheet bundle is discharged from the first processing tray 54, the raising / lowering position of the first discharge tray 24 is set so that the placement surface or the paper surface is positioned at the 24sh position of the L1 + L2 distance shown in FIG. It is. Further, when the sheets are discharged one by one, the setting is set so that the placement surface or the paper surface is positioned at the 24Sh position of the L1 distance that shortens the fall range of the sheet. In addition, when the sheet to be switched back by the transport roller 44 is short, or when the switchback transport is to make the branch path 70 wait for end-face binding, the leading edge of the sheet to be switched back to the first discharge tray 24. The position is lowered to the 24SL position of L1 + L2 + L3 distance so as not to touch the placed sheet or the placing table.
Further, when the sheet to be switched back by the transport roller 44 is long or when the switchback transport is performed to transport to the branch path for saddle stitching, the bending and fluttering of the leading edge of the sheet to be switched back are suppressed. In order to guide the sheet, an ascending setting is also made to bring the placement surface or the paper surface closer to the 24 Sh position of the L1 distance that shortens the step range.

[About the auxiliary guide 110]
Here, although somewhat touched in FIG. 3, it extends from the storage position below the first processing tray 54 to the guide position above the first paper discharge tray 24 and is carried out of the first processing tray 54 according to FIG. An auxiliary guide for guiding the lower surface of the sheet will be described. 6A shows the mechanism of the auxiliary guide 110 in FIG. 3, and FIG. 6B is a partially enlarged perspective view of the auxiliary guide 110.
As shown in FIGS. 6A and 6B, the auxiliary guide 110 is placed on the first paper discharge tray 24 or the first paper discharge tray 24 from the storage position below the first processing tray 54. It is possible to advance to the guide position above the seat. The auxiliary guide 110 is disposed adjacent to the outlet lower roller 48 b disposed in the width direction of the first processing tray outlet 50. In this embodiment, two auxiliary guides 110 are arranged in the width direction, and the side portions 115 of the auxiliary guides 110 are slidably supported by the support rails 111. Further, the auxiliary guide 110 is formed of a gently curved lever as shown in the figure, and a guide rack 112 is formed on the entire back surface of the auxiliary guide 110 in the moving direction.

As shown in FIG. 6B, the guide rack 112 is engaged with a movable pinion 117 that is provided coaxially with the outlet lower roller shaft 48sj of the outlet lower roller 48b. Driven from the auxiliary guide motor 110M is transmitted to the moving pinion 117 by a pulley 121 and a transmission belt 119 via a torque limiter 118.
Therefore, by driving the auxiliary guide motor 110M, the moving pinion 117 is also rotated, and the guide rack 112 meshed with the moving pinion 117 is also moved in accordance with this rotation direction, thereby moving the auxiliary guide 110. For example, as shown in FIG. 6A, the auxiliary guide 110 extends to the guide position above the first paper discharge tray 24 by the rotation of the moving pinion 117 in the solid line direction, and the first processing tray by the rotation in the broken line direction. Retract below 54 and move in a direction to be stored in the storage position. Also in FIG. 6B, the rotation of the moving pinion 117 and the moving direction of the auxiliary guide 110 are indicated by arrows.

The extension position of the auxiliary guide 110 is recognized by the auxiliary guide sensor 110S provided on the rear end side of the support rail 111 detecting the rear end 114 of the auxiliary guide 110. Further, since the auxiliary guide 110 is driven by the auxiliary guide motor 110M via the torque limiter 118, the auxiliary guide 110 is placed on the mounting surface of the first paper discharge tray 24 or on the sheet mounted thereon. Even if the tip contact portion 116 of the tip 113 of the 110 comes into contact, the drive does not run idle by the torque limiter 118 and the auxiliary guide 110 is not damaged.

Accordingly, when the placement surface of the first discharge tray 24 or the upper surface of the sheet placed thereon is positioned at the guide position 24Sh that is a position closer to the first processing tray outlet 50, the tip end of the auxiliary guide 110 is brought into contact. The portion 116 is closely attached to the placement surface or the top surface of the placed sheet and eliminates a step, and is more suitable as a guide for transporting the sheet (the placement surface of the first discharge tray 24 in FIG. Dash-dot line position of the placed sheet).
As described above, the configured auxiliary guide 110 serves as a sheet guide for switchback conveyance at the guide position in the second tray conveyance for conveying the sheet to the stacker 84 of the present application. This point will be described in the following flowchart of the sheet.

Here, the standby conveyance for switching back conveyance and waiting on the branch path 70 for the end face binding described above will be described. When the edge processing unit 62 performs the binding process on the first processing tray 54, the speed at which the image-formed sheet is carried in by the image forming apparatus A is high and the sheet interval is short. It is necessary to prevent the next sheet from being carried in even if it is not completed. For this reason, the first or second sheet of the sheet conveyed to the conveyance path 42 via the carry-in path 32 is temporarily switched back on the conveyance path 42, and the switchback conveyed sheet is retained on the branch path 70. It is done to wait. Then, an interval time between the sheet bundles is secured by feeding out the waiting sheet on the branch path 70 so as to be overlapped with the next second or third sheet. (So far, it is disclosed in FIG. 10 of Japanese Patent No. 5248785, which is cited as reference 1.)

[Standby transport]
In the present invention, switchback conveyance is performed from the conveyance path 42 to the branch path 70, and one or more sheets are held on the branch path 70 to stand by, and the next sheet after the standby sheet is fed out and conveyed. It is defined as “transport”. The end-face binding sheets that perform this standby conveyance are many sheets that are relatively short in the conveyance direction, for example, A4, B5, and letter size sheets. Therefore, these sheets are transported in a standby state, so that the switchback transport is not carried out greatly on the downstream side of the first processing tray 54, and is hardly bent during the transport. Even if it is bent slightly, the distance to the first processing tray 54 is relatively short, so that the bending is easily corrected by the alignment operation of the alignment plate 58.
The completion of the above-described end-face binding processing not only completes the discharge operation of the sheet bundle from the first processing tray 54 to the first discharge tray 24, but also the initial setting operation of the alignment plate 58 on the first processing tray 54. And initial position return of the reference plane moving belt 64 or other initial position setting for receiving the next sheet.

[Second tray transport]
Next, a case will be described in which saddle stitching is performed by the saddle stitching unit 82, and the sheet is folded by the folding roller 92 and the folding blade 94 and conveyed to the stacker 84 as the second processing tray in order to form a folded sheet bundle. In the conveyance to the stacker 84, the sheet conveyed to the conveyance path 42 via the carry-in path 32 is once switched back on the conveyance path 42, and the switchback conveyed sheet is conveyed from the branch path 70 to the stacker 84. become.

Conveying to the stacker 84 via the switch-branched sheet branch path 70 is herein defined as “second tray conveyance”. Since the sheet for center-side binding for carrying the second tray is folded in two, there are many sheets having a relatively long length in the carrying direction, for example, A3, B4, and legal size sheets. Accordingly, since these sheets are conveyed in the second tray, the switchback conveyance greatly protrudes to the downstream side of the first processing tray 54, and the sheet may be bent or fluttered during the switchback conveyance. Further, since the transport distance to the stacker 84 is relatively long in the second tray transport, the bend is amplified, and the bend may not be corrected even if it is aligned by the saddle stitch aligning plate 81.

In recent years, as the speed of the image forming apparatus A is increased, the sheet is conveyed at a considerably high speed, and particularly in the case of edge binding, a considerable productivity is demanded. Increases the date. Therefore, in the present invention, the switchback conveyance speed of the second tray conveyance is made slower than the switchback conveyance speed of the standby conveyance to suppress sheet bending or fluttering during the second tray conveyance.

The above points will be described with reference to the flow charts of FIGS. 7 to 11 and the flowchart of FIG.
[Standby transport for end face binding]
First, the conveying roller 44 is reversely rotated to wait on the branch path 70 in order to be stacked on the first processing tray 54 and bound to the sheet bundle in accordance with FIGS. 7 to 9, and then conveyed again to the first processing tray 54 side. “Standby conveyance” will be described.
7 to 9 exemplify the case of A4 horizontal that is used comparatively well for end face binding, and SL is the distance from the sheet sensor 42S of the conveyance path 42 to the outlet position of the outlet roller 48 (first processing tray outlet 50). Is shown. In this embodiment, SL is 120 mm to 130 mm. Accordingly, the sheet has a length slightly less than twice that of SL, and as shown in FIG.

First, FIG. 7A shows a case where the first sheet (sheet 1) for end-face binding is conveyed at about 1100 mm / s on the conveyance path, and the conveyance roller is detected when the sheet sensor 42S detects the trailing edge of the sheet. 44 temporarily stops, and this time, the conveyance roller motor 44M is switched to reverse rotation so as to reversely feed the sheet and carry it back in switchback. At this time, the front end side of the sheet is in a state where a little less than half protrudes outside the apparatus as described above.

Next, as shown in FIG. 7B, prior to the reverse rotation of the transport roller motor 44M, the switching gate 37 is moved to the position indicated by the solid line. The sheet is conveyed to the branch path 70 side by the conveyance roller 44 and conveyed toward the downstream side of the branch path 70 by the branch roller 72 rotated by the conveyance roller motor 44M. The conveyance speed of the conveyance roller motor 44M at this time is also set to a high speed so as to convey the sheet at 1100 mm / s. Of course, since the conveyance roller motor 44M temporarily stops at the time of forward rotation from the normal rotation, this 1100 mm / s is set as the conveyance target speed, and the average speed is a little slower, but the sheet is carried in from the image forming apparatus image. It is transported at high speed in time.

  In FIG. 8A, the transport roller motor 44M is stopped when the rear end of the previous sheet (sheet 1) that has been switched back reaches the position at which the next sheet (sheet 2) is not hindered at the branch position 36. As a result, the branch roller 72 is also stopped, and the preceding sheet waits for the standby next sheet to be carried in the branch path 70. The next sheet (sheet 2) is transported from the transport path 32 toward the transport path 42 at 1100 mm / s by the transport roller motor 34M.

Subsequently, in FIG. 8B, prior to the arrival of the next sheet on the conveyance path 42, the switching gate 37 is moved to a position for closing the escape path as shown. As a result, the next sheet (sheet 2) is conveyed to the conveyance path 42. At the same time, the sheet is conveyed so that it can be conveyed in an overlapped manner with the previous sheet (sheet 1) waiting on the branch path 70. At this time, as shown in the drawing, the preceding sheet (sheet 1) is conveyed with a slight shift to the rear side with respect to the leading end of the next sheet (sheet 2). As shown below, when the uppermost sheet (sheet close to the biting roller 56) is positioned far from the reference surface 57 when it is carried into the first processing tray 54, a plurality of sheets are accurately obtained by the rotation of the biting roller 56. Are aligned on the reference plane 57.
When the two sheets are overlapped, both the carry-in roller motor 34M and the carry roller motor 44M are set to carry the sheet at the same speed with a carry arrival speed of 1100 mm / s.

  Next, the process proceeds to the state shown in FIG. 9A, and before the two overlapped sheets are discharged from the conveying roller 44, the outlet upper roller 48a of the outlet roller 48 descends toward the outlet roller 48b to remove the sheet. Nip. At this time, the exit roller 48 transports at the same speed as the transport roller 44, and once the sheet is discharged from the transport roller 44, it stops. After this stop, this time, the exit roller 48 is rotationally driven to the reference surface 57 side of the first processing tray 54. As a result, the two sheets (sheets 1 and 2) are conveyed on the mounting surface of the first processing tray 54 to the reference surface 57 side, and are continuously driven by the conveying roller motor 44M via the one-way clutch gear 144. It is continuously conveyed by the roller 56. In addition, the conveyance to the reference surface 57 side of the exit roller 48 is easy to be aligned if the conveyance is decelerated from the rotation of 1100 mm / s to about 600 mm / s.

FIG. 9B shows a state where the third sheet (sheet 3) is carried into the first processing tray 54. In this case as well, before the third sheet is ejected from the transport roller 44, the upper exit roller 48a is lowered and rotated in the same direction as the transport roller 44. On the contrary, it is transferred to the reference surface 57 side together with the scraping roller 56. This is repeated until the designated number of sheets is reached, and is generated as one bundle. After the binding process by the end face binding unit 62, the first discharge tray 24 discharges the bundle.
As described above, in the standby conveyance for end face binding in FIGS. 6 to 8, the switchback conveyance speed of the conveyance roller 44 is high-speed conveyance with the set speed being 1100 mm / s.

Further, as shown in FIGS. 7 to 9, the auxiliary guide 110 is located at the storage position below the first processing tray 54. In addition, when the placement surface of the first discharge tray 24 or the upper surface of the sheet placed thereon is positioned at the separation position 24S1 that is lowered from the sheet receiving position 24Sm shown in FIGS. The back end of the back sheet does not come into contact with and separate from the mounting surface of the first paper discharge tray 24 or the upper surface of the sheet mounted thereon, so that buckling of the front end of the sheet can be avoided.

[2nd tray transport for saddle stitching]
Next, in order to stack sheets in the stacker 84 as a second tray (second processing tray) according to FIGS. 10 and 11 and to perform saddle stitching in the middle of the sheet conveying direction of the sheet bundle, the conveying roller 44 is reversed, The “second tray conveyance” in which the sheet is conveyed back to the stacker via the branch path 70 will be described.
10 and 11 exemplify the case of an A3 sheet that is used comparatively well in saddle stitching, and SL is similar to the above-described end face binding, and SL is positioned from the sheet sensor 42S of the conveyance path 42 to the exit position of the exit roller 48 (first processing tray). The distance to the exit 50) is shown. In this embodiment, since SL is 120 mm to 130 mm, the sheet for saddle stitching is about three and a half times as long as this SL. As shown in FIG. Will be out of the plane.

First, FIG. 10A shows that the second tray is conveyed to the stacker 84 via the branch path 70 for saddle stitching, and the first sheet (sheet 1) is about 1100 mm / s on the conveyance path 42. When the trailing edge of the sheet is detected by the sheet sensor 42S, the conveyance roller 44 is temporarily stopped, and this time, the conveyance roller motor 44M is switched to reverse rotation so as to reversely feed the sheet. At this time, as described above, two-thirds or more of the leading end side of the sheet protrudes outside the apparatus.

Further, the first sheet is conveyed from the first processing tray outlet 50 by the auxiliary guide motor 110M shown in FIG. 3 or 6 so that the auxiliary guide 110 guides the sheet to be conveyed by the switchback. Drive in the direction of the arrow in the figure before. Therefore, the auxiliary guide 110 is positioned at the guide surface above the upper surface of the sheet when the sheet is placed on the placement surface of the first discharge tray 24 or the placement surface. As a result, the level difference between the first discharge tray 24 placement surface at the first processing tray outlet 50 and the standing surface 28 with respect to the upper surface of the sheet placed thereon can be reduced, and the sheet to be switched back to the auxiliary guide 110. Is guided to prevent fluttering and bending.

Next, as shown in FIG. 10B, prior to the reverse rotation of the transport roller motor 44M, the switching gate 37 is moved to the illustrated position. The sheet is conveyed to the branch path 70 side by the conveyance roller 44 and conveyed toward the downstream side of the branch path 70 by the branch roller 72 rotated by the conveyance roller motor 44M. The conveyance speed of the conveyance roller motor 44M at this time is also set to be changed to a low speed so as to convey the sheet by decelerating it by 600 mm / s.
When the first sheet (sheet 1) is nipped by the branch roller 72 rotating at the same speed of 600 mm / s, the switching gate 37 is moved to a position for releasing the conveyance path 42 (position for closing the escape path). ) At the same time, the upper conveying roller 44a of the conveying roller 44 is separated from the lower conveying roller 44b and waits for the next sheet (sheet 2) to be carried. The auxiliary guide 110 guides the sheet to be switched back at the guide position above the placement surface of the first discharge tray 24 or the top surface of the placement sheet.

Note that the conveyance roller motor 44M temporarily stops at the time of forward rotation to reverse rotation, so the above-mentioned 600 mm / s is set as the conveyance target speed, and the average speed is a little slower. doing. Further, the speed is reduced from 1100 mm / s to 600 mm / s during the switchback conveyance. When the switchback conveyance is the sheet return conveyance, the sheet is particularly fluttered and is conveyed over a relatively long distance. Although the speed is reduced, if the processing speed is not particularly high, the paper sheet may be decelerated from 1100 mm / s to 600 mm / s in the reciprocating conveyance in which the paper sheet is discharged out of the apparatus.

Next, in FIG. 11A, the next sheet (sheet 2) is conveyed to the conveyance path 42 by the carry-in roller 34. In this case, since the conveying roller 44 is in a separated state as shown in the drawing, the first sheet (sheet 1) is conveyed to the stacker 84 by the branch roller 72 and the branch outlet roller 74 at 600 mm / s, and next The second sheet (sheet 2) is conveyed at 1100 mm / s along the conveyance path 42 toward the first processing tray 54 side by the carry-in roller 34. In this case, the two sheets are conveyed while being passed in opposite directions (passed conveyance).
This passing conveyance is performed in order to eliminate or reduce the waiting time of the next sheet in order to decelerate and convey the previous sheet. Further, an auxiliary guide 110 is extended to the guide position on the placement surface or the top surface of the placement sheet of the first discharge tray 24, and guides and guides the sheet to be switched back by reducing the level difference on the standing surface 28. .

In FIG. 11B, since the preceding sheet is detached from the branch roller 72 and stored in the stacker 84, the upper conveying roller 44a is lowered to bring the conveying roller 44 into the nip state, and the first discharge tray 24 side. The sheet is conveyed at a speed of 1100 mm / s. Thereafter, the sheet is continuously conveyed in the state of FIG. 10A, and this is repeated until the designated number of sheets is reached, and is generated as one bundle in the stacker 84. Then, the sheet bundle is moved to the binding position of the saddle stitching unit 82 by the stopper 85 shown in FIG.
As described above, in the second tray conveyance for saddle stitching in FIGS. 10 and 11, the switchback conveyance speed of the conveyance roller 44 is decelerated and conveyed at a set speed of 600 mm / s. In addition, the auxiliary guide 110 is extended above the placement surface of the first discharge tray 24 or the upper surface of the placement sheet to guide and guide the sheet to be switched back, thereby reducing flutter and bending at the time of sheet switchback conveyance. ing.

(Variation of standby transport: Auxiliary guide extension during standby transport)
Here, another embodiment (variation example) of standby conveyance at the time of end-face binding in FIGS. 7 to 9 will be described with reference to FIG. FIG. 12 shows that switchback conveyance is started by the conveyance roller 44 in order to perform standby conveyance as in FIG. 7, and FIG. 12A is an explanatory diagram for starting switchback in the conveyance path. FIG. 12B shows a state in which the transfer route is continuously transferred from the transfer route. In this case, in FIG. 7, the auxiliary guide 110 is positioned at the storage position stored below the first processing tray 54, but in the modified example of FIG. 12, the first paper discharge tray 24. The auxiliary guide 110 is extended on the mounting surface or the sheet upper surface of the mounting surface. Since the sheet to be transported in the standby mode has a relatively short conveyance length exposed to the outside of the apparatus, it does not generate a flutter or bend as much as a relatively long sheet during the second tray conveyance. Therefore, smoother switchback conveyance can be expected.
As described above, in this modification, the auxiliary guide 110 is extended to the guide position so that the sheet can be stably conveyed even during standby conveyance using a relatively short sheet.

(Modification of Second Tray Transport: Raising First Paper Discharge Tray 24)
FIG. 13 shows a modification in which the first discharge tray (discharge tray) is raised during the second tray conveyance for storing sheets in the stacker 84 (second tray) for the saddle stitching process shown in FIG. It is explanatory drawing of an example. FIG. 13A shows a state in which switchback is started on the transfer route, and FIG. 13B shows a state where transfer is continued from the transfer route to the branch route.
As in FIGS. 10 and 11, the auxiliary guide 110 is extended to the placement surface of the first discharge tray 24 or the guide position above the sheet placed on the placement surface during the second tray conveyance. However, as shown in FIG. 12, the guide position from the sheet receiving position 24Sm (two-dot chain line position) for receiving the sheet for discharging the sheet on the mounting surface of the first sheet discharge tray 24 or the sheet on the mounting surface. It has been moved to the raised position (solid line position) raised to the 24Sh side. To this raised position, the lifting / lowering motor 24M that lifts and lowers the first discharge tray 24 of FIGS. 3 and 5 performs the first process before the first sheet is conveyed (extruded) from the first processing tray outlet 50. This is done by driving up in the direction closest to the tray outlet 50. As a result of this rise, there is no gap between the upper end guide portion 116 of the auxiliary guide 110 and the sheet to be conveyed in the switchback is the sheet placed on the first discharge tray 24 placement surface or the placement surface. In addition, the auxiliary guide 110 and the step at this position are eliminated, and the switchback conveyance of the sheet can be performed smoothly without fluttering.

Here, the standby conveyance in FIGS. 7 to 9 described above and the conveyance speed switching in FIGS. 10 and 11 are confirmed with reference to the flowchart in FIG. Another embodiment in consideration of a different sheet size will be described with reference to FIG.
[Deceleration of switchback speed by edge binding or saddle stitching]
First, as shown in FIG. 14, when “through end surface binding mode” and “saddle binding mode” are set from the control panel 18 of the image forming unit 2, this is confirmed (Step 10). If this is end-face stitching, a sheet with a relatively short length is frequently used, so the switchback conveyance speed is kept at 1100 mm / s (Step 20). As a result, for example, one to three sheets are once switched back and conveyed to wait on the branch path 70 (branch path standby), and are then switched back and conveyed to the first processing tray 54 side together with the subsequent sheets. At this time, the auxiliary guide 110 is stored in the storage position below the first processing tray 54. When this standby conveyance is completed, the process ends and the process proceeds to the next step.

  Next, when saddle stitching is confirmed (Step 10), it is assumed that a relatively long sheet is frequently used, and the switchback conveyance speed by the conveyance roller 44 is 1100 mm / s to 600 mm / s as described in FIG. The speed is reduced to s and the switchback conveyance is performed (Step 40). The presence / absence of a subsequent sheet that is carried into the stacker 84 to be bundled is confirmed (Step 50). If there is a succeeding sheet to be bundled without being completed, the passing conveyance shown in FIG. 10B is executed. At this time, the auxiliary guide 110 guides smoothly by suppressing the fluttering of the switchback sheet conveyed by extending to the guide surface above the placement surface of the first discharge tray 24 or the sheet placed thereon. To do. Thereafter, when there is no subsequent sheet to be bundled, it is determined that the second tray conveyance process is completed, and the process proceeds to the next process such as saddle stitching.

[Variation: Speed change by sheet size in end face binding and saddle stitching]
Next, a modification of the embodiment described with reference to FIG. 14 will be described with reference to the flowchart of FIG.
Until now, in the embodiment up to FIG. 14, whether the binding mode is end-face binding for binding the end face of the sheet bundle on the first processing tray 54 or saddle-stitching for binding the sheet bundle accumulated in the stacker 84 is uniform. It has been selected whether the switchback conveyance speed is kept at 1100 mm / s or is reduced from 1100 mm / s to 600 mm / s. Even in this case, the rough processing can be covered, but there is a long sheet between the conveyance distances even in the case of end-face stitching, whereas a relatively short sheet occurs even in the case of saddle stitching.
By adopting the flow of FIG. 15, a relatively long sheet at the time of end binding or a relatively short sheet at the time of saddle stitching is stably fed.

[Change speed depending on sheet size when binding edge]
That is, when “end face stitching mode” and “saddle stitching mode” are set from the control panel 18 of the image forming unit 2, this is confirmed (Step 100). If this is end face binding, the process proceeds to the left side in the figure, and it is confirmed whether or not the length of the sheet to be subjected to end face binding is longer than a predetermined length (Step 110). In this modification, when the sheet size is B5, A4 width and letter, the length is set to be short, and for example, the lengths of A3, B4, legal and A4 lengths exceeding this are set to be long. If it is short, the switchback conveyance speed is kept at 1100 mm / s (Step 120). As a result, for example, one to three sheets are temporarily switched back and transferred to the branch path 70 (standby for the branch path), and then switched back to the first processing tray 54 side again. At this time, the auxiliary guide 110 is stored in the storage position below the first processing tray 54. When this standby conveyance is completed, the process ends and the process proceeds to the next step.
Note that the recognition of the sheet size (sheet length) in this modification is set by obtaining size information from the image formation control unit 200. Alternatively, a size detection sensor may be disposed near the carry-in entrance 30 of the sheet processing apparatus B for detection. The recognition of the sheet size is widely known, for example, when the sheet sensor detects the time when the sheet exists or is designated by the sheet cassette 1a, and the description thereof is omitted here.

On the other hand, if the sheet length is long as described above, the switchback conveyance speed by the conveyance roller 44 is reduced from 1100 mm / s to 600 mm / s, and the switchback conveyance is performed (Step 140). In this case, when this standby conveyance is performed with the succeeding sheet, it is confirmed that the preceding sheet has been nipped by the branching roller 72, and the conveyance with the next sheet is performed (Step 160). At this time, the auxiliary guide 110 extends to the placement surface of the first discharge tray 24 or a guide position above the sheet placed on the first discharge tray 24 and guides the sheet by being switched back.
When this standby conveyance is completed, the process ends and the process proceeds to the next step.

[Speed change due to sheet size during saddle stitching]
If “end stitching mode” and “saddle stitching mode” are set and the saddle stitching mode is set, the process proceeds to the right side in the figure to check whether the length of the sheet to be saddle stitched is longer than a predetermined length (Step 170). In this modification, when the sheet size is A4 vertical, it is set as short, and for example, A3, B4, and legal are set as long. Here, the A4 length that is long in the end face binding is set to be short in the saddle stitching. This is because the A4 vertical size for saddle stitching is classified as a shorter sheet in the sheet length for saddle stitching, and relatively high speed processing is required, and the branch roller 72 stops due to forward and reverse rotation. Since it rotates without any problem, the consistency does not deteriorate so much.

In this modification in which the sheet length of the saddle stitching sheet is short, in the case of A4 length, the switchback conveyance speed is kept at 1100 mm / s (Step 180). As a result, it is determined that the saddle stitched sheet has been carried into the stacker 84 (Step 190). If the second tray conveyance is completed, the process proceeds to the next step. At this time, the auxiliary guide 110 is stored in the storage position below the first processing tray 54.
If the sheet length is long as described above, the switchback conveyance speed by the conveyance roller 44 is reduced from 1100 mm / s to 600 mm / s to perform switchback conveyance (Step 200). In this case, it is confirmed that the second tray is conveyed with the succeeding sheet (Step 210), and after the preceding sheet is nipped by the branch roller 72, the sheet is conveyed with the next sheet (Step 220).
At this time, the auxiliary guide 110 is extended to the placement surface of the first discharge tray 24 or a guide position above the sheet placed thereon to guide the switchback transport sheet. Thereafter, when there is no subsequent sheet to be bundled, it is determined that the second tray conveyance process is completed, and the process proceeds to the next process such as saddle stitching.

  As described above, in the above modified example, the sheet length is not changed in the end face binding or the saddle stitching, but the speed of the switchback conveyance by the transport roller 44 is not changed depending on the end face binding or the saddle stitching. The above switchback speed was changed after confirming the above. Further, for example, the most suitable switchback speed is set even when the A4 length of the end face binding and the A4 length of the saddle stitching are the same length, and the placement surface or the placement surface of the first discharge tray 24 is placed. The auxiliary guide 110 is extended to the guide position above the sheet and the switchback sheet is guided to achieve both stable conveyance and high speed.

[Description of control configuration]
The system control configuration of the image forming apparatus described above will be described with reference to the block diagram of FIG. The system of the image forming apparatus shown in FIG. 1 includes an image forming control unit 200 of the image forming apparatus A and a sheet processing control unit 204 (control CPU) of the sheet processing apparatus B. The image formation control unit 200 includes a paper feed control unit 202 and an input unit 203. As described above, the “print mode” and the “sheet processing mode” are set from the control panel 18 provided in the input unit 203.

  The sheet processing control unit 204 is a control CPU that operates the sheet processing apparatus B in accordance with the specified sheet processing mode. The sheet processing control unit 204 includes a ROM 206 that stores an operation program and a RAM 208 that stores control data. The sheet processing control unit 204 includes a carry-in sensor 30S that detects a sheet in the carry-in path 32, a sheet sensor 42S that detects a sheet in the conveyance path 42, a branch sensor 70S that detects a sheet in the branch path 70, and a first discharge. Signals from various sensor input sections 208 such as a paper surface sensor 24S for detecting the paper surface on the paper tray 24 or an auxiliary guide sensor 110S for detecting the position of the auxiliary guide 110 extended on the first paper discharge tray 24 are input. . In this embodiment, sheet size (sheet length) information is acquired from the image formation control unit. However, the various sensor input units 208 described above may acquire the information.

    The sheet processing control unit 204 includes a carry-in roller motor 34M for the sheet carry-in path 32, a carry roller motor 44M for the carry path 42 and the branch path, an exit roller motor 48M at the exit of the first process tray 54, and the first discharge tray 24. In addition, a sheet conveyance control unit 210 that controls an auxiliary guide motor 110M that moves the auxiliary guide 110 forward and backward from the first processing tray 54 is provided. Further, the sheet processing control unit 204 controls a punch drive control unit 211 that controls a punch motor 31M that performs punching processing on a sheet by the punch unit 31, an alignment plate 58 that performs sheet stacking operation by the processing tray 29, and the like. A processing tray (first processing tray 54) control unit 212 is provided. Further, an end surface binding control unit 213 that controls the end surface binding motor 62M of the end surface binding unit 62 that performs end surface binding to the sheet bundle on the first processing tray 54, and the end surface binding sheet bundle and the first sheet discharge tray 24 onto the first sheet discharge tray 24 A lifting control unit 214 for controlling the lifting motor 24M that moves up and down according to the sheet switchback to move the first tray (first discharge tray 24) to the guide position 24Sh, the sheet receiving position Sm, and the separation position 24S1 is also provided.

Further, the sheet processing control unit 204 controls the stacker binding plate 81 for stacking sheets in the stacker 84 as the second processing tray for the saddle stitching process, and the stacker for controlling the stopper moving motor 85M of the stopper 85 for regulating the leading end of the sheet. The control unit 216 includes a saddle stitching control unit 217 that controls a saddle stitching motor 82M that binds the middle of the sheet bundle in the conveyance direction.
Further, the sheet processing control unit 204 includes a folding / discharging control unit 218 that controls a folding roller, a folding blade, and a discharging motor 92M that folds the saddle-stitched sheet bundle into two and discharges it to the second sheet discharging tray 26. Yes.
The connection between each control unit and each sensor for detecting the length of the conveyed sheet and each drive motor is the same as described in each operation mode.

[Description of sheet processing mode]
The sheet processing control unit 204 of the present embodiment configured as described above causes the sheet processing apparatus B to execute, for example, “print-out mode”, “end face binding mode”, “saddle stitching mode”, and the like. Hereinafter, this processing mode will be described.
(1) “Printout mode”
An image-formed sheet is received from the main body discharge port 3 of the image forming apparatus A, and the sheet is accommodated in the first discharge tray 24 by the conveyance roller 44 and the exit roller 48.
(2) "End binding mode"
A sheet on which an image is formed from the main body discharge port 3 is received in the first processing tray 54, and the sheets are aligned in a bundle and bound by the end face binding unit 62, and then stored in the first discharge tray 24. In this end face binding process, “standby conveyance” in which the preceding sheet is switched back and temporarily waited on the branch path 70 may be performed so as not to stop discharging the subsequent sheet from the main body discharge port 3. is there.
(3) “Saddle stitching mode”
A sheet on which an image is formed from the main body discharge port 3 of the image forming apparatus A is received by the stacker 84, the sheets are aligned in a bundle, and the saddle stitching unit 82 binds the approximate center in the sheet receiving and conveying direction, and folds it into a booklet. It is stored in the second paper discharge tray 26.
In this saddle stitching process, the sheet from the main body discharge port 3 is once discharged onto the first discharge tray 24, and then switched back to the branch path 70 and transferred to the stacker 84. It is carried out.

As described above, according to the embodiment for carrying out the present invention, the following effects can be obtained.
1. A transport path 42 for receiving the sheet and transporting the sheet to the first tray (first processing tray 54); a branch path 70 for branching from the transport path 42 and transporting the sheet to the second tray (stacker 84); A sheet that is located in the conveyance path 42 downstream of the branch position 36 between the conveyance path 42 and the branch path 70 and that can convey a sheet in either the first tray (first processing tray 54) or the branch path 70. A first conveying roller (conveying roller 44), a second conveying roller (branching roller 72) positioned in the branch path 70 and capable of conveying a sheet in any direction of the second tray (stacker 84) or the conveying path 42; Recognizing the conveyance length of the sheet conveyed by the first conveyance roller (conveyance roller 44) and the second conveyance roller (branching roller 72), the first conveyance roller (conveyance roller 44) and A control unit (sheet processing control unit 204) for controlling the second conveying roller (branching roller 72),
The control unit switches back the sheet after the sheet conveyed on the conveyance path 42 passes through the branch position 36 and temporarily waits on the branch path 70, and combines the first tray (the first tray) with the subsequent sheet. A standby transport for transporting to the processing tray 54) and a sheet transported on the transport path 42 after passing through the branch position 36, the sheet is switched back and transported to the second tray (stacker 84) via the branch path 70. The sheet processing apparatus performs the second tray conveyance to convey the switchback and varies the conveyance speed of the switchback conveyance depending on the sheet conveyance length.
According to this, when switchback transporting to different trays and carrying it in, it is possible to reduce sheet bending and fluttering even when transporting relatively long sheets, thereby preventing deterioration of alignment and occurrence of sheet jam. Can be provided.

2. 2. The sheet processing apparatus according to 1 above, wherein the control unit slows down the switchback conveyance speed when the length of the sheet to be conveyed in the switchback is longer than a predetermined standard as compared with the case of a short sheet. .
According to this, since the switchback speed is lower than when the switchback sheet is transported for a sheet longer than the predetermined standard, the fluttering and bending at the time of switchback transport of a long sheet can be suppressed. it can.

3. A sheet discharge tray (first sheet discharge tray 24) for collecting sheets is disposed on the downstream side of the first tray (first processing tray 54) disposed at the downstream end of the conveyance path 42, and the first tray One tray (first processing tray 54) is provided with an end face binding unit 62 for binding the end faces of the sheet bundle, and the second tray (stacker 84) is provided with a saddle stitching unit 82 for binding substantially the center in the sheet conveying direction. The sheet processing apparatus according to 2 above.
According to this, end face binding that requires relatively high-speed processing and saddle stitching that binds a relatively long sheet can be appropriately performed.

4. The sheet processing apparatus according to claim 2, wherein the control unit has different sheet length standards for delaying switchback conveyance between the standby conveyance and the second tray conveyance.
According to this, since the reference for slowing down the sheet conveyance speed is changed between standby conveyance and second tray conveyance, more suitable processing efficiency can be expected.

(Switchback sheets longer than the specified length are separated from the first transport roller)
5. The first conveyance roller (the conveyance upper roller 44a of the conveyance roller 44) is further configured to be movable between a pressure contact position for nipping a sheet to be conveyed and a separation position for releasing the nip of the sheet, When the length of the sheet to be transported by the switchback is longer than a predetermined standard, after nipping the second transport roller (branch roller 72), the first transport roller (the transport upper roller 44a of the transport roller 44) is moved to the separation position. 1. Move to accept the next sheet The sheet processing apparatus according to claim 1.
According to this, in the case of a long sheet that is decelerated by the switchback conveyance, the conveyance upper roller 44a is moved to the release position so that the preceding sheet and the next sheet can be conveyed. Can be handled with little loss of productivity.

6). A first tray (first processing tray) in which an apparatus frame 20, a conveyance path 42 that receives a sheet and conveys the sheet, and an end surface binding unit 62 that is located downstream of the conveyance path 42 and binds the end surface of the sheet are disposed. 54), a discharge tray (first discharge tray 24) positioned outside the apparatus frame on the downstream side of the first tray for collecting sheets discharged from the first tray (first processing tray 54), and the above-mentioned conveyance A second branch path 70 that branches at a branch position 36 on the upstream side of the first tray of the path 42 and a saddle stitching unit 82 that is located downstream of the branch path 70 and binds in the middle in the sheet conveying direction are disposed. The tray (stacker 84) is located in the conveyance path 42 on the downstream side of the branch position 36 between the conveyance path 42 and the branch path 70, and the sheet is fed in the first tray direction and the branch path direction opposite to this direction. The first conveying roller (conveying roller 44) that can be conveyed in any of the above-mentioned directions, and the sheet that is located on the above-mentioned branch path conveys the sheet in any direction of the second tray direction and the conveying path direction opposite to this direction. The second conveyance roller (branching roller 72), the first conveyance roller (conveying roller 44) and the second conveyance roller (branching roller 72) can recognize the conveyance length of the sheet conveyed, and the first conveyance roller and the first conveyance roller 2 a control unit (sheet processing control unit 204) for controlling the conveying rollers,
The control unit switches back and conveys the sheet conveyed on the conveyance path 42 after passing through the branch position 36 and temporarily waits on the branch path 70 together with the subsequent sheet to the first tray (first processing tray 54). In addition to the standby conveyance for conveyance, the second tray conveyance is performed in which the sheet conveyed on the conveyance path 42 passes through the branch position 36 and is then switched back and conveyed to the second tray (stacker 84) via the branch path 70. When the sheet length for switchback conveyance is longer than a predetermined standard, the switchback conveyance speed is slower than that for a short sheet.
According to this, when the sheet length is long in any of the switchback conveyance of the standby conveyance during the end face binding and the second tray conveyance during the saddle stitching, the sheet conveyance speed is longer than the short sheet conveyance speed. Since the conveyance speed is set to a low speed, a long sheet can be prevented from being fluttered or bent, and can be stably traveled.

7). The first conveyance roller (the conveyance upper roller 44a of the conveyance roller 44) is further configured to be movable between a pressure contact position for nipping the sheet to be conveyed and a separation position for releasing the sheet nip, and the control unit is configured to switch the switchback. When the length of the sheet to be conveyed is longer than a predetermined standard, the sheet conveyed back-switched to the second conveyance roller (branch roller 72) is nipped and then the first conveyance roller (the conveyance upper roller 44a of the conveyance roller 44). ) Is moved to the separated position so that the next sheet can be received. The sheet processing apparatus according to 1.

8. An image forming unit 2 that sequentially forms an image on a sheet and a sheet processing device B that performs a predetermined process on the sheet from the image forming unit. Or 7. An image forming apparatus having the configuration described in any of the above.
According to this, it is possible to provide an image forming apparatus having the effects 1 to 7 described above.

  In the description of the effects in the above-described embodiment, for each part of the present embodiment, the corresponding members of each component in the claims are indicated in parentheses, or a reference numeral is attached and the relationship between them is shown. Was clarified.

  Further, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the present invention, and all technical matters included in the technical idea described in the claims are described in the present invention. The subject of the invention. The embodiments described so far show preferred examples, but those skilled in the art will realize various alternatives, modifications, variations, and improvements from the contents disclosed in this specification. These are included in the technical scope described in the appended claims.

A image forming apparatus B sheet processing apparatus 2 image forming unit 20 apparatus frame 24 first discharge tray (discharge tray)
24M Lifting motor 24S Paper surface sensor 24Sh Guide position 24Sm Sheet receiving position 24Sl Separation position 26 Second paper discharge tray 30 Carry-in port 32 Carry-in route 36 Branching position 37 Switching gate 42 Carriage route 44 Carrying roller 48 Exit roller 54 First processing tray 1 tray)
57 Reference surface 58 Alignment plate 60 End surface binding portion 62 End surface binding unit 70 Branch path 72 Branch roller 80 Saddle binding portion 81 Saddle binding alignment plate 82 Saddle binding unit 84 Stacker (second processing tray / second tray)
110 Auxiliary guide 110M Auxiliary guide motor 204 Sheet processing control unit 210 Sheet conveyance control unit

Claims (8)

A transport path for receiving the sheet and transporting the sheet to the first tray;
A branch path that branches from the transport path and transports the sheet to the second tray;
A first conveyance roller that is located on a conveyance path downstream of the branch position between the conveyance path and the branch path and that can convey the sheet in any direction of the first tray or the branch path;
A second conveying roller located on the branch path and capable of conveying the sheet in any direction of the second tray or the conveying path;
A controller for recognizing a conveyance length of a sheet conveyed by the first conveyance roller and the second conveyance roller and controlling the first conveyance roller and the second conveyance roller;
The control unit performs switchback conveyance after the sheet conveyed on the conveyance path passes the branch position, temporarily waits on the branch path, and conveys the sheet to the first tray together with the subsequent sheet. Then, after the sheet conveyed on the conveyance path passes through the branch position, the sheet is switched back and conveyed to the second tray via the branch path, and the switchback conveyance is performed. A sheet processing apparatus characterized in that the speed varies depending on the sheet conveyance length. 2. The sheet processing apparatus according to claim 1, wherein when the length of the sheet to be conveyed by the switchback is longer than a predetermined standard, the control unit makes the speed of the switchback conveyance slower than the case of a short sheet. . A sheet discharge tray for stacking sheets is disposed on the downstream side of the first tray disposed at the downstream end of the conveyance path, and an end surface binding unit for binding the end surface of the sheet bundle is disposed on the first tray. The sheet processing apparatus according to claim 2, wherein a saddle stitching unit that binds substantially the center in the sheet conveyance direction is disposed in each of the two trays.   3. The sheet processing apparatus according to claim 2, wherein the control unit has a different sheet length reference for delaying the switchback conveyance between the standby conveyance and the second tray conveyance. 4. The first conveying roller is further configured to be movable between a pressure contact position for nipping the sheet to be conveyed and a separation position for releasing the sheet nip, and the control unit is configured so that the length of the sheet to be conveyed by the switchback is less than a predetermined standard. 3. The sheet processing apparatus according to claim 2, wherein, after being nipped by the second conveyance roller, the first conveyance roller is moved to a separation position so that a next sheet can be received when the length is long. A device frame;
A conveying path for receiving the sheet and conveying the sheet;
A first tray on the downstream side of the transport path and provided with an end surface binding unit that binds the end surface of the sheet;
A paper discharge tray positioned outside the apparatus frame on the downstream side of the first tray for collecting sheets discharged from the first tray;
A branch path that branches at a branch position upstream of the first tray of the transport path;
A second tray disposed on the downstream side of the branch path and provided with a saddle stitching unit for binding the middle in the sheet conveying direction;
A first conveying roller located in the conveying path downstream from the branching position and capable of conveying the sheet in any direction of the first tray direction and the branching path direction opposite to this direction;
A second conveying roller located on the branch path and capable of conveying the sheet in any direction of the second tray direction and the conveying path direction opposite to this direction;
A controller for recognizing a conveyance length of a sheet conveyed by the first conveyance roller and the second conveyance roller and controlling the first conveyance roller and the second conveyance roller;
The control unit is configured to perform a standby conveyance in which a sheet conveyed on the conveyance path passes through the branch position and is then switched back and temporarily held on the branch path, and then conveyed to the first tray together with the subsequent sheet. In addition, the sheet conveyed through the conveyance path is switched back after the sheet passes through the branch position, and the second tray is conveyed to the second tray via the branch path.
The sheet processing apparatus according to claim 1, wherein when the sheet length for switchback conveyance is longer than a predetermined standard, the switchback conveyance speed is made slower than that for a short sheet. The first conveying roller is configured to be movable between a pressure contact position for nipping the sheet to be conveyed and a separation position for releasing the sheet nip, and the control unit is configured so that the length of the sheet to be conveyed by the switchback is less than a predetermined standard. 7. The sheet according to claim 6, wherein when the sheet is long, the first transport roller is moved to the separation position after the sheet transported back to the second transport roller is nipped so that the next sheet can be received. The sheet processing apparatus according to the description. An image forming unit that sequentially forms an image on a sheet;
An image comprising: a sheet processing apparatus that performs a predetermined process on a sheet from the image forming unit, wherein the sheet processing apparatus has the configuration according to any one of claims 1 to 7. Forming equipment.

Images