JP2010247957A - Sheet postprocessing device and image forming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further accurately detect a loading height of sheets carried onto a processing tray with a simple constitution. <P>SOLUTION: A sheet transfer means 26a is lifted after stopping by lowering up to abutting on the uppermost surface of the loading sheet on the processing tray 29, and is measured until the sheet transfer means 26a reaches a specific height position, and a measuring height from the uppermost surface of the loading sheet is determined based on its measured value, and is set as a lowering quantity to the next sheet, so that for example, even if a curl part is generated in the sheet since the sheet is sent at a high speed, the sheet transfer means 26a is allowed to abut once on the uppermost surface of the loading sheet on the processing tray 29, and a sheet loading height detecting value can be accurately provided as a height measurement reference value in a state where the sheet has an original loading height by the abutting action of the sheet transfer means 26a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sheet post-processing apparatus and an image forming system having post-processing means for performing post-processing of a sheet.

  The sheet post-processing apparatus is used by being connected to, for example, an image forming apparatus, and after receiving a sheet of a recording medium or the like on which an image is formed from the image forming apparatus or the like, the sheets are aligned in a bundle and stapled It is configured to perform a binding operation. In performing the staple binding operation, a sheet such as a recording medium received on the processing tray is conveyed by the sheet transfer unit (switchback roller), guided to the sheet end regulating unit, and aligned, and then the staple binding operation is performed. To give. The sheet transfer means (switchback roller) at that time is configured such that the height position is changed according to the sheet stacking height detected by an appropriate sensor.

JP 2006-82153 A JP 05-169396 A

  However, since the above-described detection of the sheet stacking height is conventionally performed using the swinging action of a relatively light flag-like member, for example, a sheet is fed at a high speed or a curled portion is formed on the sheet. If this occurs, the lightweight flag-like member may swing more than the actual sheet stacking. If detection is performed in such an overswing state, the lighter flag-shaped member may exceed the actual sheet stacking height. There is a risk of determining that the sheet is at a high position. If the sheet height is incorrect, the switchback roller stops at a high position, so that the necessary contact pressure cannot be applied to the sheet and the sheet cannot be conveyed to a predetermined position.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet post-processing apparatus and an image forming system that can accurately detect the height of a sheet loaded on a processing tray with a simple configuration.

  In order to achieve the above object, according to the present invention, the sheet conveying means is lowered from above the sheet carried into the processing tray, and the sheet is guided to a predetermined position of the processing tray by the sheet conveying means brought into contact with the sheet. In the sheet post-processing apparatus, wherein the sheet transfer unit is configured to change a lowered position according to a stacking height of the stacked sheets on the processing tray. The means is lowered until it comes into contact with the processing tray, stopped, and then measured until the sheet conveying means reaches a certain height position after being raised, and the next of the sheet conveying means is measured based on the measured value. It is comprised so that it may become the descent | fall amount with respect to descent | fall of this. For example, the sheet transporting unit is lowered and stopped until it comes into contact with the uppermost surface of the stacked sheets on the processing tray, and then measured until the sheet conveying unit reaches a certain height position after being lifted. A configuration is adopted in which the lowering amount of the sheet transporting unit with respect to the next transported sheet is set based on the measured value.

  According to the present invention having such a configuration, for example, even if a sheet is fed at a high speed or a curled portion is generated on the sheet, the sheet transfer means is temporarily provided on the uppermost surface of the stacked sheets on the processing tray. Since the stacking height is measured after the stacked sheets are corrected to the original stacking height by the pressing action when they are brought into contact with each other, the detection value of the stacking height of the stacked sheets can be obtained with high accuracy. .

  At this time, in the present invention, it is preferable that the distance is measured a plurality of times, and the descending amount is determined from a plurality of obtained measurement values.

  According to the present invention having such a configuration, errors relating to height measurement are reduced by measuring a plurality of times, and the stacked height of the stacked sheets can be obtained more accurately.

  As described above, according to the present invention, the sheet transporting unit is lowered and stopped after being brought into contact with the uppermost surface of the stacked sheets on the processing tray, and then lifted to reach the certain height position. By measuring the distance and determining the measurement height from the top surface of the stacked sheet (position of the top surface of the stacked sheet on the processing tray) based on the measured value and setting it as the descending amount for the next sheet, for example, high speed Even if a sheet is fed or a curled portion is generated on the sheet, the stacked sheet is not loaded by the pressing action when the sheet transfer means is once brought into contact with the uppermost surface of the stacked sheet on the processing tray. Since the stack height is measured after the height is corrected and the detection value of the stack height of the stacked sheets is obtained with high accuracy, the sheet loaded on the processing tray is configured. The stacking height of the bets, can be detected accurately with a simple configuration, the reliability of the sheet post-processing apparatus and an image forming system can be inexpensive and significantly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory side view showing an overall configuration of an example of an image forming system to which the present invention is applied. FIG. 2 is an enlarged side view illustrating an overall configuration of a post-processing device (sheet handling device) of the image forming system illustrated in FIG. 1. FIG. 3 is an enlarged partial cross-sectional explanatory view showing a staple unit provided in the post-processing apparatus of FIG. 2 and a structure in the vicinity thereof. It is a configuration explanatory view of the rear end regulating means and alignment means of the processing tray. 4A and 4B are explanatory views of a paper discharge mechanism of the processing tray, in which FIG. 4A is a side view illustrating a standby state of the switchback roller, and FIG. 5B is a side view illustrating a sheet engagement state of the switchback roller. It is a flowchart regarding the height detection operation | movement of a switchback roller. It is explanatory drawing of the sheet | seat alignment mechanism of a processing tray, (a) is explanatory drawing which shows the whole structure, (b) shows the state with little sheet | seat stacking amount, (c) shows the state with much sheet | seat loading amount. (D) is the positional relationship between the carry-in guide and the carry-out guide, (e) shows the configuration of the kick means, and (f) is an explanatory view showing the drive mechanism. FIG. 10 is a flowchart illustrating a conveyance control operation in a “plain paper mode” among conveyance modes for stacked sheets on a processing tray. FIG. 9 is a side explanatory view schematically showing the state of each stage in the “plain paper mode” shown in FIG. 8. The position movement mechanism of the alignment plate in a processing tray is shown, (a) is explanatory drawing which shows the regulation state of a large size sheet (b) and a medium size sheet. FIG. 4 is a diagram illustrating a position movement mechanism of an alignment plate in a processing tray, (c) is an explanatory view showing a restricted state of a small size sheet, and (d) is an offset state of a large size sheet. It is a perspective view which shows the whole structure of a sheet bundle carrying-out means. It is explanatory drawing which shows the planar structure of a sheet bundle carrying-out means. It is explanatory drawing of the guide mechanism of a sheet bundle carrying-out means. It is explanatory drawing of the drive mechanism of a sheet bundle carrying-out means. 4A and 4B are explanatory views of a grip mechanism of the sheet bundle carrying-out means, where FIG. 4A is an explanatory view of a state where a sheet bundle is nipped, and FIG. It is explanatory drawing of the grip mechanism of a sheet bundle carrying-out means, Comprising: (c) is explanatory drawing of the state which carried out the sheet bundle to the stack tray. FIG. 4 is an explanatory diagram of an operation state of the sheet bundle carrying-out means, where (a) is a first standby position state, and (c) is a side explanatory view showing an initial state of retreating to a second standby position. FIG. 6 is an explanatory diagram of an operation state of the sheet bundle carrying-out means, (e) is a second standby position state, (f) is a state where the sheet bundle is nipped, and (g) is a side explanatory view showing a state where the sheet bundle is unloaded. is there. FIG. 6 is an explanatory diagram of an operation state of the sheet bundle carrying-out means, (h) shows a state where the sheet bundle is transferred onto the stack tray, (i) shows a state where the sheet bundle is carried out onto the stack tray, and (j) shows a sheet bundle. (K) is side explanatory drawing which shows the state immediately after having loaded on a stack tray, and the state which returned to the 1st standby position. It is explanatory drawing of the positioning mechanism of the punch unit in the apparatus of FIG. It is explanatory drawing of the positioning state in the positioning mechanism of the punch unit of FIG. FIG. 2 is a block diagram of a control configuration in the image forming system of FIG. 1.

  Hereinafter, an embodiment in which the present invention is applied to an image forming system provided with a sheet post-processing apparatus B in a copying machine A as an image forming apparatus will be described in detail with reference to the drawings.

[Configuration of image forming system]
The image forming system shown in FIG. 1 includes a sheet post-processing apparatus B connected to an image forming apparatus A that forms an image on a sheet-like recording medium such as a cut sheet. A carry-in port 23 a of the sheet post-processing apparatus B is connected to the paper discharge port 3 of the apparatus A. Then, the sheet-like recording medium on which an image is formed by the image forming apparatus A is configured to be stapled by the sheet post-processing apparatus B and stored in the stack tray 21 or the saddle tray 22.

[Configuration of Image Forming Apparatus]
As shown in FIG. 1, the image forming apparatus A in such an image forming system sends a sheet-like recording medium such as a cut sheet from the paper feeding unit 1 to the image forming unit 2, and the image forming unit 2. Then, after printing on the sheet-like recording medium, the sheet is discharged from the discharge port 3. The sheet feeding unit 1 stores a plurality of sizes of sheet-like recording media in the sheet feeding cassettes 1a and 1b, and feeds the designated sheet-like recording media one by one to the image forming unit 2. The image forming unit 2 includes, for example, an electrostatic drum 4, a laser light emitter 5 disposed around the electrostatic drum 4, a developing device 6, a transfer charger 7, and a fixing device 8. An electrostatic latent image is formed on the electrostatic drum 4 by a laser light emitter 5, toner is adhered to the electrostatic drum 4 by a developing device 6, an image is transferred onto a sheet-like recording medium by a transfer charger 7, and a fixing device 8 is used. Fix by heating. The sheet-like recording medium on which the image is formed in this manner is sequentially carried out from the paper discharge port 3. Reference numeral 9 in the figure denotes a circulation path. The sheet-like recording medium printed on the front side from the fixing device 8 is turned upside down via the switchback path 10 and then fed to the image forming unit 2 again. This is a double-sided printing path for printing on the back side of the sheet-like recording medium. The sheet-like recording medium printed on both sides in this way is carried out from the paper discharge port 3.

  Reference numeral 11 in the drawing denotes an image reading apparatus, which scans an original 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 the image processing unit, for example, and then transferred to the storage unit 17, and an image signal corresponding to the image data is sent to the laser emitter 5. Reference numeral 15 in the drawing denotes a document feeder, which is a feeder device that feeds document sheets stored in a document tray 16 to the platen 12.

  The image forming apparatus A having the above-described configuration is provided with an image forming apparatus control unit (controller) 150 as shown in FIG. 23, and image forming conditions such as sheet size designation, number of copies to be printed from the control panel 18. Printing conditions such as designation, single-sided / double-sided printing designation, and enlargement / reduction printing designation are set. On the other hand, 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, and the image data is stored in the buffer memory 19 from the data storage unit 17. The data signals are transferred and sequentially transferred from the buffer memory 19 to the laser emitter 5.

  From the control panel 18, post-processing conditions are also input and designated simultaneously with the image forming conditions such as single-sided / double-sided printing and enlargement / reduction printing described above. As post-processing conditions at this time, for example, “print-out mode”, “binding finishing mode”, “booklet finishing mode”, or the like is selected.

[Configuration of sheet post-processing apparatus]
The sheet post-processing apparatus B receives a sheet-like recording medium on which an image is formed from the paper discharge port 3 of the image forming apparatus A, and (i) whether the sheet-like recording medium is stored in the stack tray 21 without post-processing (printing) (Out mode), (ii) after sheet-like recording media from the sheet discharge outlet 3 are aligned in a bundle and stapled, and then stored in the stack tray (first stack tray) 21 (binding finish mode), iii) The sheet-like recording media from the paper discharge outlet 3 are aligned in a bundle and stapled at the center, and then folded into a booklet and stored in the saddle tray (second stack tray) 22 (booklet finishing mode). Therefore, it is configured as follows.

  In particular, as shown in FIG. 2, the casing (apparatus frame) 20 of the sheet post-processing apparatus B is provided with a carry-in port 23a, which is a discharge port of the image forming apparatus A. 3 is connected. In the casing 20, the sheet-like recording medium from the carry-in entrance 23a is partly collected and stacked, and the sheet-like recording medium from the carry-in entrance 23a is partly accumulated. A second processing unit BX2 for finishing a booklet is provided. A first loading path P1 is provided between the first processing unit BX1 and the loading port 23a, and a second loading path P2 is provided between the second processing unit BX2 and the loading port 23a. The sheet-like recording medium from the opening 23a is distributed and guided to the first processing unit BX1 and the second processing unit BX2. The carry-in entrance 23a is provided with a carry-in roller 23, a sheet sensor S1, and a path switching means (flapper member) 24 that distributes the sheet-like recording medium to the first or second carry-in paths P1 and P2.

  A “buffer path P 3” is provided between the punch unit 60 and the processing tray 29 in the first transport path P 1. This buffer path P3 is used when a post-processing such as stapling is performed on a stack of sheet-like recording media (hereinafter referred to as a sheet bundle) that are stacked and arranged on the processing tray 29 during the post-processing operation. The subsequent sheet-like recording medium sent to 23a is temporarily retained. For this reason, the buffer path P3 is branched and arranged in the first transport path P1 in the vertical direction of the casing 20, as shown in FIG. The sheet-like recording medium from the first transport path P1 is switched back and stays in this path. Therefore, when the post-processing (edge binding processing described later) is performed on the sheet bundle that has been aligned and stacked on the processing tray 29, the subsequent sheet-like recording medium sent to the carry-in port is temporarily retained, and the processing sheet on the processing tray 29 is stored. After the sheet is carried out, the succeeding sheet-like recording medium in this path can be transferred to the processing tray 29.

  The first carry-in path P1 is disposed substantially horizontally in the upper part of the apparatus housing constituted by the casing 20, and the first processing unit BX1 is disposed downstream of the first carry-in path P1, and the stack tray 21 is disposed downstream thereof. Is arranged. A punch unit 60 (to be described later) is disposed between the carry-in port 23 and the first processing unit BX1 in the first carry-in path P1. In the first carry-in path P1, a paper discharge roller 25 and a paper discharge outlet 25x are provided at the exit end of the path, and a paper discharge sensor S2 is disposed in the paper discharge outlet 25x, and passes through the first carry-in path P1. The sheet-shaped recording medium to be detected is detected to detect jam and to count the number of passing sheets. Then, a processing tray 29 described below is arranged with a step formed downstream of the paper discharge port 25x.

  Further, the second carry-in path P2 is arranged substantially vertically in the lower part of the casing 20, the second processing unit BX2 is arranged on the downstream side of the second carry-in path P2, and the saddle is arranged on the downstream side thereof. A tray 22 is arranged. Further, a trimmer unit (cutting unit) 90 is disposed in the second carry-in path P2 in the vicinity of the saddle tray 22. Furthermore, a conveyance roller 27 is provided in the second carry-in path P2, and a stacking guide 45, which will be described later, is disposed with a step formed on the downstream side thereof.

[Configuration of first processing unit]
Here, the first processing unit BX1 described above includes a processing tray 29 disposed in the first carry-in path P1, an end binding unit 31 disposed in the processing tray 29, and an aligning unit 51.

[Processing tray structure]
As shown in FIG. 3, the processing tray 29 is formed of a synthetic resin plate or the like, and includes a sheet support surface 29a for stacking and supporting sheet-like recording media. The sheet support surface 29a is arranged with a step formed downstream of the paper discharge port 25x of the first carry-in path P1, and is configured to stack and store sheet-like recording media from the paper discharge port 25x. The illustrated sheet support surface 29 a is formed to have a length shorter than the length of the sheet in the sheet discharge direction, supports the rear end of the sheet from the sheet discharge outlet 25 x, and the sheet front end is above the uppermost sheet of the stack tray 21. To support (bridge support).

On the downstream side of the processing tray 29 in the transport direction, a sheet end regulating means 32 is provided, and a leading end of the sheet carried into the processing tray 29 is abutted and aligned. Above the processing tray 29, a switchback roller (first friction rotator; the same applies hereinafter) 26 (moving drive roller 26a, fixed) that transfers the sheet-like recording medium carried on the processing tray 29 to the sheet end regulating means 32. Drive roller 26b), alignment means 51 and side alignment means 34 are arranged.
Each configuration will be described below.

[Configuration of sheet edge regulating means]
The processing tray 29 is provided with sheet end regulating means 32 for positioning the leading edge of the loaded sheet. The sheet end regulating means 32 shown in FIG. 4 is configured by a stopper member having a sheet end surface regulating surface 32a that abuts and regulates the leading edge of the sheet, and a sheet upper surface regulating surface 32b that regulates the upper sheet surface of the uppermost sheet. . The sheet end regulating means 32 is disposed at the downstream edge of the processing tray 29, and a post-processing set in advance by abutting and regulating the leading edge of the sheet transferred by the switchback roller 26 and the aligning means 51 described later. The sheet is positioned at a position (binding position; the same applies hereinafter). At this time, the sheet upper surface regulating surface 32b regulates the warping surface of the sheet with the curled tip, and the sheet end surface regulating surface 32a regulates the position of the sheet edge.

  The illustrated sheet end surface regulating surface 32a and sheet upper surface regulating surface 32b are formed of a stopper member integrally formed of a resin, a metal plate, or the like. However, both the regulating surfaces can be formed of individual members. . In the illustrated sheet end regulating means 32, a fixed stopper member 32A is disposed at the center in the sheet width direction, and first and second movable stopper members 32B and 32C are disposed at predetermined intervals on the left and right ends of the sheet, respectively. It is comprised with the stopper member. In addition, 32s in the figure is a leaf spring attached to each stopper member in order to correct the curl at the front end of the sheet.

  As described above, the first and second movable stopper members 32B and 32C positioned at the left and right end portions of the sheet are moved according to the sheet size. Therefore, the right slide member 38a and the left slide member 38b are fitted and supported on the bottom wall of the processing tray 29 so as to be movable in the sheet width direction. The first movable stopper member 32B and the second movable stopper member 32C are fixed to the left and right slide members 38a and 38b. The left and right slide members 38a and 38b are connected so as to be interlocked with alignment plates 34L and 34R that align the seat sides as will be described later.

  The sheet end regulating means 32 configured as described above is configured such that at least the sheet upper surface regulating surface 32b can move up and down in the sheet stacking direction. This is because when the sheet bundle on the processing tray 29 is unloaded from the processing tray by the sheet bundle unloading means 100 described later, the sheet bundle on the tray 29 may be lifted upward by the sheet bundle unloading means 100. This is because the sheet upper surface regulating surface 32b is moved upward following the upward movement of the sheet.

  Therefore, as shown in FIG. 4, the fixed stopper member 32 </ b> A is pivotally supported by the bottom wall of the processing tray 29 so as to be swingable, and is urged and supported by the urging spring 33 downward in the drawing. The first and second movable stopper members 32B and 32C are attached to the left and right slide members 38a and 38b, respectively, so as to be elastically deformable (32α portion in the drawing).

[Configuration of sheet transfer means]
The processing tray 29 is provided with a sheet transfer means (switchback roller) 26 for temporarily stopping the sheet discharged from the sheet discharge outlet 25x and then switching it back to guide the sheet end regulating means 32. The sheet transporting unit 26 is configured by a friction rotating body such as a roller or a belt that transports a sheet conveyed from the sheet discharge outlet 25x to the processing tray 29 side to the sheet end regulating unit 32. This will be described below according to the illustrated switchback roller mechanism.

  As shown in FIG. 5, the switchback roller 26 is disposed above the processing tray 29 and is configured to convey the sheet discharged from the sheet discharge outlet 25x in the forward and reverse directions. The switchback roller 26 moves up and down between an operating position in contact with the conveyed sheet (state shown in FIG. 5B) and a standby position spaced above the sheet (state shown in FIG. 5A). It is axially supported by the elevating support arm 28 so as to move. That is, the lifting support arm 28 is supported by an apparatus frame (not shown) so as to be swingable by a swinging rotary shaft 28a. The swinging rotary shaft 28a is supported by a lift motor (arm driving means; hereinafter) via a pinion 28p. Similarly, MY is connected. A position sensor S3 is disposed in the vicinity of the lift support arm 28, and the position of the lift support arm 28 is detected and lift control is performed between the standby position and the operating position.

  The movable switchback roller 26a, which is axially supported by the elevating support arm 28, is connected to a forward / reverse motor (not shown) via a transmission means (coupling), and discharges the sheet carried on the processing tray 29 in the paper discharge direction. In addition, the paper is conveyed in the reverse direction in the opposite direction. Therefore, the roller rotating shaft 26z of the switchback roller 26a is supported by a long groove 28u formed in the lifting support arm 28, and is supported so as to be vertically movable in the sheet stacking direction (vertical direction in FIG. 5). The lift support arm 28 is provided with a paper surface contact sensor Ss. In addition, 28z in the drawing shows a leaf spring that always urges the roller rotating shaft 26z downward, and when the switchback roller 26a is lowered, the paper surface contact sensor Ss is prevented from being erroneously detected due to the lift of the shaft. It is. With this leaf spring 28z, the switchback 26a comes into contact with the uppermost sheet with a constant pressing force (contact pressure).

"Paper contact sensor"
The lift support arm 28 is provided with a paper surface contact sensor Ss for detecting the position of the roller rotation shaft 26z that moves up and down along the long groove 28u. The paper surface contact sensor Ss is configured to detect the position of the roller rotation shaft 26z that moves (moves upward) in the long groove 28u by the contact pressure with which the switchback roller 26a contacts the uppermost sheet on the processing tray. For this reason, the lift support arm 28 is provided with a sensor lever 30 having a rotation center o1 at a position different from the swing rotation shaft 28a, and a roller rotation shaft 26z is axially connected to the tip of the sensor lever 30. The paper surface contact sensor Ss is configured by a photo sensor that detects a sensor flag 30f formed at the rear end of the sensor lever 30.

  The switchback roller 26a configured as described above is configured such that the lifting support arm 28 is moved up and down by the lifting motor MY, so that the standby position above the processing tray (FIG. 5A) and the sheet carried on the processing tray are transferred. It moves up and down with respect to the operation position (FIG. 5B) in contact with. Then, it is detected by the paper surface contact sensor Ss disposed on the elevating support arm 28 that the switchback roller 26a comes into contact with the sheet carried on the processing tray 29. The detection of the stacking height of the sheet at this time has been conventionally performed by swinging a relatively light flag-like member. For example, when the sheet is fed at a high speed or a curled portion is generated on the sheet. The flag-like member may swing more than the actual sheet stacking height and stop, which may cause an error in the detection value.

"Configuration of control means"
Therefore, the lifting control means 165 for controlling the lifting motor MY is configured as follows. The raising / lowering control means 165 is comprised by control CPU160 mentioned later, and raises / lowers the raising / lowering support arm 28 between a standby position and an operating position. First, the lifting control means 165 stops the lifting support arm 28 at the standby position by the position sensor S3 disposed in the vicinity of the lifting support arm 28. First, an initial operation for determining the current height position of the switchback roller 26a is executed.

  That is, as shown in FIG. 6, first, the lowering of the switchback roller 26a provided on the lifting / lowering support arm 28 is started together with the lifting / lowering support arm 28 (step 1). When 26a comes into contact with the switchback roller 26b, as described above, when the paper surface contact sensor Ss for detecting the position of the roller rotation shaft 26z is turned on (step 2), the descent is stopped (step 3). Thereafter, the switchback roller 26a is started to rise together with the lifting support arm 28 (step 4), and the distance (height) H0 until the paper surface contact sensor Ss is turned off is measured (step 5). ). Such measurement is repeatedly performed a plurality of times (for example, three times), an average value is calculated based on the obtained measurement values, and the average value is calculated from the switchback roller (fixed drive roller) 26b. Determine and store as H0. Then, the measured height H0 is set as a descending amount with respect to the next first sheet. Thereafter, the switchback roller 26a is moved up to the home position (position sensor S3ON) together with the lifting support arm 28 to be in a standby state (step 6).

  When the first sheet is conveyed, the leading edge of the sheet carried out from the above-described sheet discharge port 25x is detected by the sheet sensor S2, and the switchback roller 26 passes the leading edge of the sheet (step 7). ), The elevating motor MY is rotated counterclockwise in FIG. Then, the elevating support arm 28 rotates counterclockwise in FIG. 5 about the swinging rotation shaft 28a. As a result, the roller rotating shaft 26z of the switchback roller 26a is supported by the long groove 28u, so that the switch back roller 26a is moved from the standby position (FIG. 5 (a)) to the operating position (FIG. 5 (b)) at substantially the same speed as the lifting support arm 28. (Step 8 in FIG. 6). At this time, the sensor lever 30 connected to the switchback roller 26a moves (lowers) in the same direction at the same speed as the lifting support arm 28. Further, the switchback roller 26a at this time descends to a predetermined height calculated from the above-described measured height H0 from the tray conveyance surface (step 9 in FIG. 6).

  Next, the switchback roller 26a starts to rise (step 11 in FIG. 6), and the distance (height) H1 until the paper surface contact sensor Ss for detecting the position of the roller rotation shaft 26z reaches a certain height position is set. Measure (Step 12 in FIG. 6). Such measurement is repeatedly performed a plurality of times (for example, three times), an average value is calculated based on the obtained measurement values, and is determined as the measurement height H1 from the top surface of the stacked sheets. Remember. Then, the measured height H1 is set as a descending amount with respect to the next second sheet. Thereafter, the switchback roller 26a is lifted to the home position (height 22 mm) together with the lifting support arm 28 to enter a standby state (step 13 in FIG. 6), and the same switchback is performed for the second and subsequent sheets. The sheet is conveyed by the roller 26a.

As described above, in the present embodiment, when the Nth sheet is conveyed, the leading edge of the sheet carried out from the discharge port 25x is detected by the sheet sensor S2, and the leading edge of the sheet has passed the switchback roller 26a. Thereafter (step 14 in FIG. 6), the switchback roller 26a is lowered from the standby position (FIG. 5 (a)) to the operating position (FIG. 5 (b)) together with the lifting support arm 28 (step 15 in FIG. 6). When the switchback roller 26a at this time descends to a predetermined height calculated from the measured height _HN-1 from the top surface of the paper measured last time (step 16 in FIG. 6), the switchback roller 26a stops descending (FIG. 6). 6, the switchback roller 26 a is rotated in the clockwise direction in the drawing, and the leading edge of the sheet is drawn into the stack tray 21. Then, after the rear end of the sheet has passed through the paper discharge port 25x, the switchback roller 26a is reversely rotated and conveyed back to the sheet end regulating means 32 side. During the sheet conveyance process, the sheet and the switchback roller 26a are engaged with a constant pressing force regardless of the amount of sheets stacked on the processing tray, and a predetermined conveying force set in advance is applied to the sheet. .

  Next, the switchback roller 26a starts to rise (step 18 in FIG. 6), and the distance (height) HN until the paper surface contact sensor Ss for detecting the position of the roller rotation shaft 26z is turned off is measured (step in FIG. 6). 19). Such measurement is repeatedly performed a plurality of times (for example, three times), an average value is calculated based on the obtained measurement values, and is determined as a measurement height HN from the top surface of the paper. Remember. Then, the measured height HN is set as a descending amount with respect to the next (N + 1) th sheet. Thereafter, the switchback roller 26a rises to the home position together with the lifting support arm 28 and enters a standby state (step 20 in FIG. 6), and the same sheet back conveyance by the switchback roller 26a is performed for the (N + 1) th and subsequent sheets. Is performed (step 21 in FIG. 6).

  At this time, the raising / lowering control means 165 makes the lowering speed (rotational speed of the raising / lowering motor MY) Va of the raising / lowering support arm 28 equal to the speed (free fall speed) Vr at which the movable switchback roller 26a falls by its own weight in the long groove 28u. Or it is set so as to be later (Va ≦ Vr). This is to prevent the paper surface contact sensor Ss from erroneously detecting rebound or the like when the lowering speed Va of the elevating support arm 28 is made faster than the switchback roller 26a that freely falls in the long groove 28u and the roller becomes unstable. In other words, the speed Vr at which the switchback roller 26a falls is limited by the speed of the lifting support arm 28 and is gently lowered to prevent erroneous detection due to chattering of the paper surface contact sensor Ss.

  Next, when the peripheral surface of the switchback roller 26a abuts on the uppermost sheet on the processing tray 29, the switchback roller 26a stops on the uppermost sheet (step 10 in FIG. 6). Rotate in the same direction and descend. At this time, in the paper surface contact sensor Ss, the sensor lever 30 rotates in the clockwise direction (indicated by the arrow in FIG. 5B) around the center rotation center o1. Then, the paper surface contact sensor Ss detects the sensor flag 30 f of the sensor lever 30 and turns “ON”. The lift motor MY is stopped by the detection signal of the paper surface contact sensor Ss. By controlling in this way, the switchback roller 26a always abuts on the uppermost sheet with a constant pressure contact force (for example, its own weight) Pt regardless of the amount of sheets stacked on the processing tray 29 (FIG. 5 ( b)).

  Concurrently with the lowering of the switchback roller 26a to the operating position, the elevation control means 165 drives a forward / reverse motor (not shown) to rotate the switchback roller 26a in the forward / reverse direction. Then, the sheet carried on the uppermost sheet of the processing tray 29 from the sheet discharge outlet 25x receives a certain conveying force and is transferred in the sheet discharge direction and the sheet discharge opposite direction. In the illustrated apparatus, when the sheet from the sheet discharge outlet 25x is conveyed in the sheet discharge direction from the sheet discharge outlet, the switchback roller 26a is rotated in the clockwise direction in the figure to discharge the leading end of the sheet to the stack tray 21. On the other hand, when the sheet is conveyed to the processing tray 29, after the rear end of the sheet passes through the paper discharge port 25x, the switchback roller 26a is temporarily stopped and then reversely rotated to the sheet end regulating means 32 side of the processing tray 29. Transport switchback. In this sheet conveyance process, the lowering amount of the switchback roller 26a is determined by using the value measured at the previous rising time, so that the sheet and the switchback roller 26a have a constant pressing force regardless of the sheet stacking amount on the processing tray. And a predetermined conveying force set in advance is applied to the sheet.

  According to such a configuration, for example, even if a sheet is fed at a high speed or a curled portion is generated on the sheet, the sheet transfer unit 26a is temporarily brought into contact with the uppermost surface of the stacked sheets on the processing tray 29. In addition, the sheet stacking height detection value can be obtained with high accuracy as a reference position for height measurement in a state where the sheet has the original stacking height by the contact action of the sheet transport unit 26a. In the present embodiment, the distance until the paper surface contact sensor Ss is turned off is measured, but the time until the paper contact sensor Ss is turned off is measured, and the switchback roller 26a is lowered for that time. It is also good time to do. Moreover, although the average value of a plurality of measured values is calculated, the calculation is not essential, and a value selected from a plurality of values (for example, three middle values) may be used as the measured value.

"Alignment mechanism"
An alignment mechanism (alignment means) 51 is provided on the processing tray 29 to transfer the sheet to the sheet end regulating means 32 together with the switchback roller 26a. As shown in FIG. 7A, the aligning unit 51 is a friction that is arranged below the sheet discharge outlet 25x and scrapes the rear end of the sheet carried into the processing tray 29 and transports it toward the sheet end regulating unit 32. A rotating body 52 is used.

  The friction rotating body 52 is composed of a rotating body such as a rubber material, sponge (porous foam), other rollers, and a belt, and engages with the uppermost sheet on the tray and transfers it in a predetermined direction by the friction force. The illustrated friction rotator 52 is configured to move up and down according to the amount of sheets stacked on the processing tray 29. For this reason, a friction rotating body (roller) 52 is supported by a support on an elevating support arm 54 that is rotatably supported by an oscillation frame 53 on an apparatus frame (not shown). A driving pinion 53p is attached to the oscillating rotating shaft 53, and a stepping motor MC is connected to the driving pinion 53p. A torque limiter (not shown) is built in between the drive pinion 53p and the swing rotation shaft 53. Therefore, when the friction rotating body 52 attached to the lifting support arm 54 comes into contact with the uppermost sheet on the processing tray 29, the torque limiter idles by the reaction force, and always engages with the uppermost sheet with a constant pressure. .

  For this reason, regardless of the amount of sheets stacked on the processing tray 29, the friction rotating body 52 engages on the uppermost sheet, and the lifting support arm 54 stops at this position. Then, after the elevating support arm 54 stops on the uppermost sheet, a torque limiter (not shown) idles and applies a predetermined pressing force to the friction rotating body 52. An idle pulley is supported on the swing rotation shaft 53, and a drive motor (not shown) is connected to the pulley. The rotational force of the drive motor is transmitted from the pulley to the friction rotating body 52 by a belt or the like. The friction rotating body 52 configured in this way rotates the sheet counterclockwise in FIG. 7 at the operation position shown in FIGS. 7B and 7C and directs the sheet carried on the processing tray toward the sheet end regulating means 32. It is designed to be transported.

  The above-mentioned lifting support arm 54 is provided with a carry-in guide 54 a on the upstream side of the friction rotating body 52 and a carry-out guide 54 b on the downstream side. The carry-in guide 54a is formed in a guide shape for guiding the sheet leading end to the friction rotating body 52, and the carry-out guide 54b is positioned between the friction rotating body 52 and the sheet end regulating means 32. The guide shape is configured to guide each.

"Import guide"
As shown in FIG. 7A, the carry-in guide 54a is integrally formed with the lifting support arm 54 so that the sheet carry-in side is high and the friction rotator side is low so as to guide the sheet leading edge in the circumferential direction of the friction rotator 52. An inclined taper surface 54a1 is provided. Therefore, even if the trailing edge of the sheet fed toward the sheet edge regulating means 32 by the switchback roller 26a is curled and warped, it is guided to the friction rotating body 52 along the tapered surface 54a1. . Since this carry-in guide 54a is integrally formed with the lifting support arm 54, it is lifted upward according to the amount of sheets stacked on the processing tray. The carry-in guide 54a is formed integrally with the friction rotator 52 as described above. When the roller diameter of the rotator is reduced (for miniaturization), the sheet with the trailing edge curled is caught in the roller and jammed. Therefore, when guiding with the carry-in guide, the angular relationship between the guide surface (the taper surface described above) and the roller peripheral surface changes according to the sheet stacking amount, causing jamming. In order to solve such a problem, the friction rotating body 52 and the carry-in guide 54a are integrated so as to move up and down according to the sheet stacking amount.

"Unloading guide"
The carry-out guide 54 b includes a guide surface 54 b 1 that guides the rear end side of the sheet fed by the friction rotating body 52 from above and guides it to the sheet end regulating means 32. Similarly to the carry-in guide 54a, the carry-out guide 54b is integrally formed with the lifting support arm 54 and is configured integrally with the friction rotating body 52. Accordingly, the sheet is moved upward in accordance with the sheet stacking amount on the processing tray.

  Therefore, as shown in FIG. 7D, the carry-in guide 54a and the carry-out guide 54b have a gap (L1) between the carry-in guide 54a and the uppermost sheet with respect to the uppermost sheet of the processing tray 29. (L1> L2) is set larger than the interval (L2).

"Configuration of kicker means"
The carry-in guide 54a guides the sheet from the paper discharge port 25x to the friction rotating body 52 in cooperation with the kicker means 55 arranged on the upstream side. The kicker means 55 will be described. As described above, a step is formed between the paper discharge outlet 25x and the processing tray 29, and the trailing edge of the sheet sent from the paper discharge outlet 25x by the switchback roller 26a falls onto the processing tray 29. Therefore, a kicker means 55 is provided at the paper discharge port 25x.

  As shown in FIG. 7A, the kicker means 55 includes a base end swing lever 55a and a front end kick lever 55b attached to the apparatus frame by a rotating shaft 56. A drive motor 57 is connected to the rotating shaft 56 of the base end swing lever 55a by a gear. In addition, the shaft is pivotally connected to the tip of the tip kick lever 55b. As shown in FIGS. 7E and 7F, the rotary shaft 56 is swung at a predetermined rotation angle by a drive motor 57, and a shaft fulcrum 55b1 of the tip kick lever 55b is connected to the rotary shaft 56 via a gear and a belt. It is connected. 7 (e), the kicker means 55 at the broken line position (standby position) rotates the drive motor 57 in the clockwise direction in the figure, and the base end swing lever 55a swings in the arrow a direction (counterclockwise) in the figure. . At this time, since the tip kick lever 55b is connected to the rotating shaft 56, the gear, and the belt, the tip kick lever 55b rotates in the direction indicated by the arrow b (clockwise). Accordingly, when the drive motor 57 is rotated forward (clockwise in the drawing), the kicker means 55 is moved from the broken line state to the solid line state in FIG. 7E. At this time, the sheet rear end from the sheet discharge outlet 25x is moved to the lower processing tray. Strike 29.

  A control CPU 160, which will be described later, determines that the trailing edge of the sheet has passed the discharging roller 25 based on a detection signal that the trailing edge of the sheet has passed through the discharge sensor S2 of the discharge outlet 25x, and energizes the drive motor 57 to supply the trailing edge of the sheet Kick down onto the tray. The rear end of the sheet dropped by the kicker means 55 is arranged to be guided to the friction rotating body 52 by the carry-in guide 54a.

  Here, in the “plain paper mode” when the type of sheet (recording medium) used is plain paper, as shown in FIGS. 8 and 9, the sheet is unloaded from the paper discharge port 25 x described above. The leading edge of the sheet is detected by the sheet sensor S2, and at the timing when the leading edge of the sheet passes through the switchback roller 26a after the expected time when the leading edge of the sheet has passed immediately below (see step 111 in FIG. 8 and (a) in FIG. 9). ), The switchback roller 26a is lowered together with the lifting support arm 28, the sheet is sandwiched between the lower fixed roller 26b, and the sheet is conveyed in the discharge direction by the normal rotation of the switchback roller 26a (FIG. 8). Step 112 and (b) of FIG. 9). After the trailing edge of the sheet has moved slightly past the discharge roller pair 25 by the conveyance of the switchback roller 26a, the sheet is conveyed by a predetermined amount by the switchback roller 26a and stopped (see step 113 in FIG. 8).

  Next, the reverse rotation of the switchback roller 26a is started, and the sheet is conveyed on the processing tray 29a toward the sheet end regulating means 32 (see step 114 in FIG. 8 and (c) in FIG. 9). At this time, when the return roller 51b provided at the front end portion of the return guide member 51a is lowered together with the return guide member 51a of the aligning means 51, and a predetermined amount is sent after the front end of the sheet hits the return roller 51b. Then, the switchback roller 26a is raised together with the lifting support arm 28 (see step 115 in FIG. 8 and (d) in FIG. 9). Then, by rotating the return roller 51b described above, the sheet is abutted against the sheet end regulating means 32, and thereafter, after further sheet conveyance is performed, the sheet alignment is completed (see FIG. 8). (See step 116).

[Configuration of side alignment means]
The processing tray 29 is provided with side aligning means 34 for aligning and aligning sheets. The side aligning unit 34 employs either a center reference for aligning with respect to the center of the sheet carried into the processing tray 29 from the sheet discharge outlet 25x or a side reference for aligning with respect to the left and right side edges of the sheet. Is done. The operation will be described with reference to the perspective view shown in FIG. 4 and the operation state diagrams shown in FIGS.

  As shown in FIG. 4, the side alignment means 34 includes a left alignment plate 34L that engages with the left edge of the sheet on the processing tray 29, and a right alignment plate 34R that engages with the right edge of the sheet. The left and right alignment plates 34L and 34R are fitted and supported in guide grooves (see FIG. 4) formed in the sheet support surface 29a of the processing tray, respectively, and can be moved in the sheet width direction. As shown in FIG. 10, a pair of pulleys 35 is disposed along the guide groove on the bottom of the processing tray 29, and a belt 36 is bridged over the pulleys 35. The left and right alignment plates 34L and 34R are fixed to the belt 36. Further, shift motors MZ1 and MZ2 are connected to one of the pulleys 35.

  The left alignment plate 34L and the right alignment plate 34R, which are formed as a pair on the left and right sides in such a configuration, are moved to the left and right in the sheet width direction by driving the shift motors MZ1 and MZ2. Therefore, the left and right shift motors MZ1 and MZ2 are synchronously driven in the opposite direction by the same amount so that the sheets carried on the processing tray can be aligned with the center reference. FIG. 10A shows a state in which large size sheets are aligned, and FIG. 10B shows a state in which medium size sheets are aligned. FIG. 11C shows a state in which small-size sheets are aligned. On the other hand, the sheet bundle aligned on the processing tray with the center reference can be offset by rotating the left and right shift motors MZ1, MZ2 in the same direction by the same amount. FIG. 11D shows a case where the large size sheet is offset. In this way, offsetting a large-size sheet by a predetermined amount requires that the post-processing means 31 be moved to the side of the apparatus when the post-processing position is biased to the sheet corner (corner staple described later), and the size of the apparatus is increased. Bring. Thus, post-processing such as corner binding can be performed by offsetting the sheet bundle accumulated on the processing tray 29 by a predetermined amount. This achieves a compact and compact device.

[Linking mechanism of alignment plate and movable stopper]
The pair of left and right alignment plates 34L and 34R configured as described above are interlocked with the sheet end regulating means 32 described above as follows. The sheet end regulating means 32 includes a left movable stopper (second movable stopper member) 32C and a right movable stopper (first movable stopper member) 32B. The left and right movable stoppers 32B and 32C are arranged on the processing tray 29. Are connected to left and right slide members 38a and 38b which are fitted and supported so as to be movable in the sheet width direction.

  Therefore, the left and right movable stoppers 32B and 32C are coupled to the left and right alignment plates 34L and 34R by a coupling spring 37 as shown in FIG. That is, the right slide member 38a having the right movable stopper 32B is connected by the connecting spring 37a, and the left slide member 38b having the left movable stopper 32C is connected by the connecting spring 37b. The left and right alignment plates 34L and 34R reciprocate between the strokes LS1 in the sheet width direction. On the other hand, the left and right movable stoppers 32B and 32C are driven between the strokes LS2. For this reason, stop members (not shown) are arranged on the processing tray 29 side in the left and right movable stoppers 32B and 32C.

  The strokes LS1 and LS2 are set such that LS1> LS2, and the left and right movable stoppers 32B and 32C move by the same amount until they hit the stop member in conjunction with the movement of the left and right alignment plates 34L and 34R. . The movable stoppers 32B and 32C stop at this position after hitting the stop member, and the alignment plates 34L and 34R further move. At this time, the connecting springs 37a and 37b connecting the two extend (extend). Accordingly, the left and right alignment plates 34L and 34R move between strokes LS1 corresponding to the sheet size, and the movable stoppers 32B and 32C move between strokes LS2. The reason why the strokes of the left and right movable stoppers 32B and 32C are set to be short is that a sheet bundle carrying-out means 100 described later is arranged at the center of the sheet.

  As described above, when the left and right movable stoppers 32B and 32C constituting the sheet end regulating means 32 are interlocked with the side aligning means 34, and the movement strokes of the both are made different, in the illustrated embodiment, a connection spring 37 is used. As described above, the “sliding transmission mechanism” or “deceleration transmission mechanism” may be used for the left and right alignment plates 34L, 34R and the left and right movable stoppers 32B, 32C.

  In the case of the “sliding transmission mechanism”, the left and right alignment plates 34L and 34R and the left and right movable stoppers 32B and 32C are connected by a sliding friction clutch, and after the left and right movable stoppers 32B and 32C hit the stop member, the clutch plate Is configured to slide. The “deceleration transmission mechanism” connects the left and right alignment plates 34L and 34R and the left and right movable stoppers 32B and 32C with a gear transmission mechanism. At this time, the alignment plates 34L and 34R move with a stroke LS1, and the movable stoppers 32B and 32C. Sets the gear ratio to move with stroke LS2.

  The control of the side alignment means 34 will be described. The left and right alignment plates 34L and 34R are provided with position sensors at preset home positions, and the left and right alignment plates 34L and 34R are positioned at the home position when the apparatus is activated. Therefore, the control CPU 160, which will be described later, receives the size information of the sheet on which the image is formed from the image forming apparatus A, and based on this information, the control unit 166 positions the left and right alignment plates 34L, 34R at predetermined standby positions. This standby position is set to a position (a position for forming an alignable moving width) that is a predetermined amount away from the width size of the sheet sent to the processing tray 29. Therefore, the control CPU 160 turns the left and right shift motors MZ1 and MZ2 in the opposite directions after the expected time that the trailing edge of the sheet unloaded from the sheet discharge outlet 25x is loaded onto the processing tray (after the timer time has elapsed from the sheet discharge sensor S2). Synchronously rotate by a predetermined amount. Then, the sheets carried on the processing tray are aligned and aligned.

"Corner staple binding mode"
Further, the control CPU 160 moves the left and right alignment plates 34L and 34R by a predetermined amount in the sheet width direction and offsets when binding a sheet bundle that has been aligned and stacked on the processing tray by a stapling unit (edge binding unit) 31 described later. Is configured to do. In the case of an apparatus configuration in which the stapling means 31 is moved to this position when binding the sheet corner, the apparatus is enlarged in the sheet width direction. Therefore, the apparatus shown in the figure offsets the sheet bundle on the processing tray by driving the shift motors MZ1, MZ2 of the left and right alignment plates 34L, 34R in the same direction by the same amount in the corner staple binding mode.

"Two-point staple binding mode"
Further, when the user sets the two-point binding by the stapling means (end binding unit) 31 described later, the control CPU 160 moves the stapling means 31 to the second closed position after the one-side stapling is completed. The left and right alignment plates 34L and 34R are moved in the back direction opposite to the stapling means 31, as shown in FIG. It is comprised so that it may move toward.

[Configuration of sheet bundle carry-out means]
The processing tray 29 is provided with a sheet bundle carrying-out means 100 for carrying out the processed sheet bundle to the downstream stack tray 21. The sheet bundle carrying-out means 100 is disposed at the bottom of the processing tray 29, protrudes above the sheet support surface 29a and engages with the sheet bundle, and mounts and supports the sheet engaging member 105. It is comprised with the carrier member 110. FIG. 12 is an explanatory diagram showing a perspective configuration of the sheet bundle carrying-out means 100, FIG. 13 is an explanatory diagram showing a planar configuration, and FIG. 15 is an explanatory diagram of a drive mechanism.

  As shown in FIGS. 11 and 16, the sheet bundle carrying-out means 100 includes a sheet engaging member 105, a carrier member 110, an engaging member driving means 127, and a carrier member driving means 114. The sheet engaging member 105 includes a movable gripper 105a and a fixed gripper 105b. The carrier member 110 is mounted with the sheet engaging member 105 and is configured to reciprocate from the base end portion (post-processing position) of the processing tray 29 to the front end portion (bundle unloading position). Each configuration will be described below.

"Sheet engaging member"
The sheet engaging member 105 is constituted by an engaging member such as a protruding piece or a gripper that engages with the rear end edge of the sheet bundle stacked on the processing tray, and is a guide formed on the sheet support surface 29 a of the processing tray 29. It arrange | positions in the groove | channel 29G. As shown in FIG. 13, a guide groove 29 </ b> G is formed in the processing tray 29 between the processing position and the stack tray 21 disposed on the downstream side of the processing tray 29. ). In the illustrated example, two guide grooves 29G1, 29G2 are formed at a distance in the sheet width direction, and the sheet engaging member 105 is disposed in each of the left and right guide grooves 29G1, 29G2 as follows.

  The illustrated sheet engaging member 105 includes a gripper mechanism that grips and carries out the trailing edge of the sheet bundle on the processing tray 29. As shown in FIGS. 11 and 16, the movable gripper 105a and the fixed gripper 105b are connected to each other by a pivot pin (connection shaft) 106 so as to swing. A biasing spring 107 is provided between the movable and fixed grippers so that the tip nip portion 105ax of the movable gripper 105a and the tip nip portion 105bx of the fixed gripper 105b are always in pressure contact (FIG. 16A). reference).

  Therefore, the fixed gripper 105b is fitted and supported in a guide groove 115 formed in the carrier member 110 so as to be movable in the unloading direction. The rear end of the movable gripper 105a is connected to a traveling belt 116 built in the carrier member 110 by a connecting spring 117. Accordingly, when a traveling belt 116 of the carrier member 110 described later moves to the left in FIG. 16, the fixed gripper 105b and the movable gripper 105a move in the sheet bundle carrying-out direction with the leading end nip portions 105ax and 105bx being in pressure contact with each other (FIG. 16 ( a) state). When the traveling belt 116 is fed back to the right side in FIG. 16, the movable gripper 105a swings clockwise around the pivot pin 106, and the tip nip portion 105ax is separated from the tip nip portion 105bx of the fixed gripper 105b to release the nip. (State shown in FIG. 16B).

"Carrier material"
Next, the carrier member 110 for mounting and supporting the above-described sheet engaging member (hereinafter referred to as “gripper member (means)”) 105 will be described. As shown in FIGS. 13 and 16, the carrier member 110 is composed of an appropriately shaped frame member that supports the gripper member (means) 105, and extends in the sheet bundle carrying-out direction along the guide groove 29 </ b> G formed in the processing tray 29. It is supported movably.

  Explaining the support structure, the rear end portion 110b of the carrier member 110 is supported so as to linearly reciprocate along the slide member 119 shown in FIG. The tip 110a of the carrier member 110 reciprocates in a loop along the loop guide groove 29Ga described below. As a result, the gripper member (means) 105 mounted on the carrier member 110 is moved from the standby position to the carry-out position by an upper path protruding on the process tray, and after the sheet bundle is carried to the stack tray 21, it is placed in the process tray. It returns to the standby position with the lower pass. 111 shown in the figure is a guide pin provided at the tip of the carrier member 110 and is fitted in the loop guide groove 29Ga.

`` Slide member ''
As shown in FIG. 13, the slide member 119 is fitted and supported by a guide rail 121 disposed at the bottom of the processing tray 29, and can reciprocate with a predetermined stroke in the same direction as the guide groove 29G (the vertical direction in FIG. 13). It is supported. A driving rotary shaft 125 is mounted on the slide member 119, and a rear end portion 110 b of the carrier member 110 is axially coupled to the driving rotary shaft 125. FIG. 16 shows the state of this shaft connection. The carrier member 110 is connected so as to reciprocate with a predetermined stroke in the sheet bundle carrying-out direction by the drive rotation shaft 125 of the rear end portion 110b, and at the same time, the front end portion 110a thereof is The drive rotation shaft 125 can be swung around. A drive arm (crank member) 126 described later is connected to the slide member 119, and the drive arm (crank member) 126 reciprocates between predetermined strokes. Further, a driving pulley of a travel belt 116 described later is connected to the driving rotating shaft 125, and an engaging member driving means 127 is connected to the driving rotating shaft 125.

"Loop guide groove"
Loop guide grooves 29Ga facing each other are formed on the left and right side walls of the guide groove 29G (see FIG. 13). A guide pin 111 formed at the tip 110a of the carrier member 110 is fitted and supported in the loop guide groove 29Ga. As shown in FIG. 14, the loop guide groove 29Ga is formed in a loop shape having an upper travel path 113a and a lower travel path 113b along the sheet support surface 29a of the processing tray. The guide pin 111 moves from the standby position to the carry-out position along the upper travel path 113a (outward path), and moves from the carry-out position to the standby position along the lower travel path 113b (return path).

  As described above, when the carrier member 110 supported by the slide member 119 and the loop guide groove 29Ga moves from the standby position to the stack tray 21 side as shown in FIG. 14, the guide pin 111 follows the upper travel path 113a to move the carrier member. 110 moves in a substantially horizontal posture. When returning from the stack tray 21 to the standby position, the guide pin 111 follows the lower travel path 113b and the carrier member 110 moves in an inclined state.

  Further, as shown in FIG. 14, the guide groove 29G is formed with a loop groove 112 for guiding the guide pin 108 provided in the sheet engaging member (movable gripper member) 105a. The movable gripper 105a and the fixed gripper 105b move along the loop groove 112.

  As will be described later, the sheet engaging member (gripper member) 105 mounted on the carrier member 110 is a sheet engaging member when the guide pin 111 of the carrier member 110 is guided by the upper travel path 113a and moves in the sheet bundle unloading direction. The joint member (gripper member) 105 has an operating posture protruding above the processing tray 29. When the guide pin 111 is guided to the lower travel path 113b and moves to the standby position, the sheet engaging member (gripper member) 105 is guided to the guide groove. It is designed to be in a standby position that is immersed inside. This state will be described later with reference to FIGS.

  As shown in FIG. 16, the carrier member 110 configured as described above is provided with a pair of pulleys 130a and 130b before and after the sheet bundle carrying-out direction, and a traveling belt 116 is bridged between the pulleys. One drive pulley 130b is supported by the drive rotation shaft 125 described above. Accordingly, the rotation of the drive rotation shaft 125 causes the sheet engaging member (gripper member) 105 to overlap with the carrier member 110 in the base end storage position (state shown in FIG. 18A described later) and the carrier member 110 in the sheet bundle carrying-out direction. It is configured to be movable between the protruding tip carry-out position (state shown in FIG. 20H described later).

"Seat engagement member mounting structure"
The above-described carrier member 110 is disposed at the bottom of the processing tray 29, and a sheet engaging member (gripper member) 105 is mounted on the top. As described above, the sheet engaging member (gripper member) 105 has the movable gripper 105a connected to the upper portion of the fixed gripper 105b by the pivot pin 106. Therefore, the fixed gripper 105b is supported by the carrier member 110 so as to be movable in the sheet bundle carrying-out direction. 115 is a slide guide groove formed in the carrier member 110, and a fixed gripper 105b is fitted and supported in the guide groove 115. The movable gripper 105 a is pivotally supported by the fixed gripper 105 b by a pivot pin 106, but its rear end is connected to a traveling belt 116 built in the carrier member 110 by a connection spring 117. The carrier member 110 and the sheet engaging member (gripper member) 105 include carrier driving means 114 and engaging member driving means 127, respectively, as shown in FIGS.

"Carrier drive means"
As shown in FIG. 13, the carrier member 110 is connected (coupled) to a slide member 119 with a drive rotating shaft 125. Accordingly, as conceptually shown in FIG. 16, a shaft pin 122 is integrally formed with the slide member 119, and a drive arm 126 is fitted to the shaft pin 122. The drive arm 126 is connected to the drive motor MH so as to swing around a swing shaft 131 supported by the device frame by a crank member. The drive arm 126 and the shaft pin 122 are connected by a slit (long hole). Accordingly, when the drive arm 126 is moved back and forth by a predetermined angle by the drive motor MH, the slide member 119 reciprocates back and forth with a predetermined stroke. By the back and forth movement of the drive arm 126, the rear end portion 110b of the carrier member 110 moves back and forth along a linear locus, and the front end portion 110a moves back and forth along the loop guide groove 29Ga along the loop locus. As described above, the carrier member 110 includes the carrier driving means 114 that moves the carrier member 110 in the sheet bundle carrying-out direction along the processing tray 29.

"Engagement member drive means"
The fixed gripper 105 b and the movable gripper 105 a constituting the sheet engaging member (gripper member) 105 are connected to each other by a pivot pin 106. The fixed gripper 105b is supported by the carrier member 110 so as to be movable back and forth in the sheet bundle carrying-out direction along the slide guide groove 115. Further, the rear end portion of the movable gripper 105a is connected to the traveling belt 116 of the carrier member 110 by a connection spring 117 (see FIG. 16 above). Therefore, as conceptually shown in FIG. 16, a driving motor ME is connected to the driving pulley 130b of the traveling belt 116 provided on the carrier member 110. The drive motor ME is composed of a motor that can rotate forward and backward. When the drive motor ME is rotated in the forward direction, the traveling belt 116 moves in the left direction in FIG. Following the movement of the traveling belt 116, the movable / fixed clippers 105a and 105b move along the slide guide groove 115 from the standby position to the unloading position (bundle unloading direction).

  When the drive motor ME is rotated in the reverse direction, the movable / fixed clippers 105a and 105b move from the carry-out position to the standby position (return direction) as shown in FIG. At the same time, when the traveling belt 116 further moves to the rear side from the standby position, the connection spring 117 moves in the clockwise direction following the drive pulley 130b. With the backward movement of the drive pulley 130b, the connecting spring 117 pulls the rear end portion of the movable gripper 105a downward. At this time, the movable gripper 105a rotates clockwise around the pivot pin 106, and the nip portion 105ax at the tip is expanded upward (see FIG. 16B). As described above, the sheet engaging member (gripper member) 105 includes the engaging member driving means 127 that moves the sheet engaging member (gripper member) 105 in the sheet bundle carrying-out direction along the carrier member 110.

"Operation of sheet engaging member"
The operation of the sheet engaging member (gripper member) 105 configured as described above will be described. The structure of the control means of the gripper means (gripper member) 105 will be described later, but “first standby position Gp1” “second standby position Gp2” “nip position Gp3” “bundle unloading position Gp4” “nip release position Gp5” ”And“ first standby position Gp1 ”.

"First standby state"
The control means 167, which will be described later, moves the gripper means (gripper member; the same applies hereinafter) 105 to the first standby position Gp1 shown in FIG. 18A by "initial operation" (described later) when the apparatus is activated. At the first standby position Gp1, the gripper means 105 is in a standby posture immersed in the guide groove 29G of the processing tray 29. The sheet carried on the processing tray 29 in this posture is abutted and aligned with the sheet end regulating means 32 as shown in FIG. Accordingly, in this posture, sheets are aligned and collected from the discharge outlet 25x on the processing tray 29, and post-processing is performed at a preset processing position of the sheet bundle.

"Retraction operation of gripper means"
Upon receiving a job end signal from the image forming apparatus A, the control unit 167 moves the gripper unit 105 backward toward the second standby position Gp2 on the rear side. For this reason, the control means 167 reversely rotates the drive motor MH of the drive arm 126 described above by a predetermined amount. In the process of retreating toward the second standby position Gp2, the gripper means 105 moves the guide pin 111 of the carrier member 110 from the lower travel path 113b of the loop guide groove 29Ga to the upper travel path 131a, and its movable gripper. 105a protrudes above the sheet support surface 29a (see FIG. 18C). At this time, the leading edge of the sheet is pushed upward by the movable gripper 105a. However, the sheet end regulating means 32 is elastically deformed as shown in FIG. This ensures a smooth movement of the gripper means 105.

"Second standby position state"
Next, the control means 167 rotates the drive motor MH of the drive arm 126 in the reverse direction by a predetermined amount and then stops it. And the control means 167 rotates the drive motor ME of the drive pulley 130b provided in the carrier member 110 clockwise (refer FIG. 16 (a) (b)). Then, the movable gripper 105a shifts from the nip posture of FIG. 19 (c) to the nip release posture of FIG. 19 (e). In this state, the gripper means 105 is positioned at the second standby position Gp2.

"Nip operation"
Next, the control means 167 rotates the drive motor MH of the drive arm 126 in the forward direction, and moves the carrier member 110 in the bundle carry-out direction. Simultaneously with this drive control, the control means 167 rotates the drive pulley 130b of the carrier member 110 in the clockwise direction (see FIGS. 16A and 16B). At this time, the gripper means 105 can be made stationary by adjusting the moving speed Vb of the traveling belt 116 with respect to the moving speed Vc of the carrier member 110. That is, when the gripper means 105 is moved in the direction opposite to the moving direction of the carrier member 110 with respect to the sheet on the processing tray, the gripper means 105 is stationary when viewed from the sheet. For example, when the speeds Vc and Vb are set to the same speed (Vc = −Vb), the gripper means 105 is stationary. As a result, the gripping operation by the gripper means 105 can be performed reliably.

  Next, the control means 167 continues the forward rotation of the drive motor MH of the drive arm 126 and simultaneously rotates the drive pulley 130b of the carrier member 110 in the counterclockwise direction (see FIGS. 16A and 16B). Then, as described in FIGS. 16A and 16B, the connection spring 117 is loosened by the movement of the traveling belt 116, and the movable gripper 105 a is pressed against the fixed gripper 105 b by the biasing spring 107. At this time, the rear end portion of the sheet bundle on the processing tray is nipped. This state is shown in FIG.

`` Move bundle transfer position ''
The control means 167 stops the drive pulley 130b of the carrier member 110 and continues the forward rotation of the drive motor MH of the drive arm 126. Then, the sheet bundle nipped by the gripper means 105 is transferred along the processing tray 29 to the state shown in FIG. The control means 167 rotates the driving pulley 130b of the carrier member 110 counterclockwise with the sheet bundle being transferred to the carry-out position in the state shown in FIG. Then, the fixed / movable grippers 105a and 105b connected to the traveling belt 116 protrude above the processing tray from the carrier member 110 in the state shown in FIG. As a result, the rear end of the sheet bundle is carried out onto the stack tray 21, and the front end is stored on the uppermost sheet on the tray.

"Nip released"
Next, the control means 167 temporarily stops the drive motor MH of the drive arm 126. Then, the carrier member 110 falls in the loop guide groove 29Ga. Then, the gripper means 105 drops onto the uppermost sheet on the tray in the state shown in FIG. Therefore, the control means 167 rotates the drive motor MH of the drive arm 126 in the reverse direction. Then, the carrier member 110 returns to the first standby position side along the lower travel path 113b of the loop guide groove 29Ga. At this time, the sheet bundle nipped by the gripper means 105 is blocked by the side wall of the tray and released from the nip (the state shown in FIG. 20 (j)).

"Return state"
Further, the control means 167 continues the rotation of the drive motor MH of the drive arm 126 to return the carrier member 110 from the bundle carry-out position Gp4 to the first standby position Gp1. Then, the gripper means 105 returns to the state of being submerged in the guide groove 29G of the processing tray 29 to the state of FIG.

[Configuration of punch unit]
In the first carry-in path P1, the punch unit 60 is disposed between the carry-in roller 23 and the paper discharge roller 25, and a file hole is punched in a sheet passing through the first carry-in path P1. The configuration of the punch unit 60 will be described with reference to FIG. The punch unit 60 includes a punch member 62, a blade receiving member (die) 63, a drive cam 64, and a drive motor MX. A plurality of punch members 62 are arranged on the unit frame 61 at intervals in the sheet width direction, and are supported by bearings so as to be vertically movable in the punching direction. Each punch member 62 is meshed with a drive cam 64 (slide groove cam, eccentric rotation cam, etc.), and moves up and down with the drive cam 64 connected to the drive motor MX to punch a file hole. Further, the blade receiving member 63 is disposed to face the punch member 62 with a sheet passing through the first carry-in path P1 interposed therebetween.

  The unit frame 61 is supported by an apparatus frame (not shown) so as to be movable in the seat width direction. This is to align the side edge of the sheet sent to the first carry-in path P1 with the punch position. That is, the sheet sent to the first carry-in path P1 is sent in a dimensional error of the sheet itself, a positional deviation in the width direction (left-right deviation), or a state inclined rightward or leftward (right skew, left skew). At this time, if punch holes are formed regardless of the position of the side edge of the sheet, the sheet edge becomes uneven when filing. Therefore, the following positioning mechanism is required.

[Positioning mechanism]
The positioning mechanism for matching the relative positions of the punch unit (post-processing unit) 60 and the sheet edge is composed of a sheet end detection unit 67 and a positioning unit 68. The sheet end detection means 67 is constituted by sensor means 66 for detecting the side edge of the sheet sent to the processing position, and the positioning means 68 moves the relative position between the sheet and the post-processing means 60 based on the detection information. It is configured as follows.

"Sheet edge detection means"
As shown in FIG. 21, the sheet edge detecting means 67 includes a sensor means 66 for detecting the left and right side edges of the sheet sent to the processing position, and the sensor means 66 from the preset initial position in the sheet width direction. And shift means 69 which moves to the position. The sensor means 66 is composed of a pair of light emitting elements 66a and light receiving elements 66b arranged to face each other, and is arranged at a position for detecting the side edge according to the sheet size. In the figure, the A4 detection sensor S4a and the B5 detection sensor S5b are arranged at positions where the sheet side edge is detected because the sheet size is JIS standard A4 size and B5 size. The sensor means 66 is disposed on the unit frame 61 that supports the punch member 62.

"Positioning means"
As described above, the unit frame 61 on which the punch member 62 and the sensor means 66 are mounted is supported by a guide rail (not shown) so as to be movable in the sheet width direction. The unit frame 61 is provided with a rack gear 61R, and a drive motor MX is connected to a pinion 61P that meshes with the rack gear 61R. As a result, the unit frame 61 can move to the right and left of the stepping motor (drive motor) MX in the right and left directions in the sheet width direction.

"Sensor position control means"
The sensor position control means 169 includes a control CPU 160 described later. The sensor position control means 169 is electrically connected to the driver circuit of the stepping motor MX so as to move the unit frame 61 from the preset home position to the left and right in the sheet width direction. Therefore, the sensor position control means 169 moves the sensor means 66 to the outside in the sheet width direction when the sensor means 66 detects the sheet when the sensor means 66 is at the initial position (home position) (FIG. 22). (C) The position of the sheet edge is detected by moving in the right and left direction. (Ii) When the sheet is not detected, the sensor means 66 is moved inward in the sheet width direction (right and left in FIG. 22B) to move the sheet edge. It is configured to detect an edge.

  In detecting the position of the sheet edge, when the sensor means 66 changes from “OFF to ON” or “ON to OFF”, this position is determined as the sheet edge, and the unit frame 61 is stopped. Then, the positional relationship between the sensor means 66 and the punch member 62 is set so that the post-processing means (punch member) 62 mounted on the unit frame 61 punches a punch hole at a set distance from the edge of the sheet. Has been.

[Description of control configuration]
The control configuration of the above-described image forming system will be described with reference to the block diagram of FIG. The image forming system shown in FIG. 1 includes a control unit (hereinafter referred to as “main body control unit”) 150 of the image forming apparatus A and a control unit (hereinafter referred to as “post-processing control unit”) 160 of the post-processing apparatus B. The main body control unit 150 includes an image formation control unit 151, a paper feed control unit 152, and an input unit 153. Then, “image formation mode” and “post-processing mode” are set from the control panel 118 provided in the input unit 153. As described above, the image forming mode sets the number of printouts, sheet size, enlarged / reduced printing, duplex / single-sided printing, and other image forming conditions. Then, the main body control unit 150 controls the image formation control unit 151 and the paper feed control unit 152 according to the set image forming conditions, and after the image is formed on a predetermined sheet, the sheets are sequentially carried out from the main body discharge port 3. .

  At the same time, the post-processing mode is set by input from the control panel 18. The post-processing mode is set to, for example, “print-out mode”, “staple binding finishing mode”, “sheet bundle folding finishing mode”, or the like. Therefore, the main body control unit 150 transfers the post-processing finishing mode and the number of sheets, the upper number of copies, and the binding mode (one-position binding or two or more bindings) information to the post-processing control unit 160. At the same time, the main body control unit 150 transfers a job end signal to the post-processing control unit 160 every time image formation is completed.

  The post-processing control unit 160 includes a control CPU 161 that operates the post-processing apparatus B according to a designated finishing mode, a ROM 162 that stores an operation program, and a RAM 163 that stores control data. The control CPU 161 includes a sheet conveyance control unit 164a that performs conveyance of the sheet sent to the carry-in entrance 23a, a sheet accumulation operation control unit 164b that performs sheet accumulation operation, and a binding operation control that performs sheet binding processing. A unit 164c and a sheet bundle folding operation control unit 164d that executes a sheet bundle folding operation.

  The sheet conveyance control unit 164a is connected to the control circuit for the drive motor (not shown) of the carry-in roller 23 and the paper discharge roller 25 in the first carry-in path P1 described above, and from the sheet sensor S1 disposed in the carry-in path. The detection signal is configured to be received. The sheet stacking operation control unit 164b is connected to a drive circuit of a forward / reverse rotation motor of the switchback roller 26a and a shift motor of a sheet end regulating member in order to stack sheets on the processing tray 29. Further, the binding operation control unit 164 c is connected to a drive circuit of a drive motor MD built in the end binding unit 31 of the processing tray 29 and the saddle stitching staple unit 40 of the accumulation guide 45.

  The sheet bundle folding operation control unit 164d is connected to a drive circuit of a drive motor that drives and rotates the folding rolls 46a and 46b and a drive circuit of a clutch unit. The sheet bundle folding operation control unit 164d is connected to a control circuit of shift means for controlling the movement of the conveying roller 27 of the second carry-in path P2 and the leading end stopper 43 of the stacking guide 45 to predetermined positions, and is arranged in these paths. Wired so as to receive a detection signal from the sheet sensor.

The control unit configured as described above causes the post-processing apparatus B to execute the next processing operation.
"Printout mode"
In this mode, the image forming apparatus A forms an image of a series of documents from the first page, for example, and sequentially unloads from the main body discharge port 3 face down, and the sheet sent to the first carry-in path P1 is discharged to the discharge roller 25. Led. Therefore, after the expected time that the leading edge of the sheet reaches the switchback roller 26a of the processing tray 29 based on the signal that the leading edge of the sheet is detected at the paper discharge port 25x, the sheet conveyance control unit 164a moves the switchback roller 26a from the upper standby position onto the tray. The roller is lowered and rotated in the clockwise direction in FIG. Then, the sheet that has entered the processing tray 29 is transported toward the stack tray 21 by the switchback roller 26a and is stored on the tray. In this way, the subsequent sheets are sequentially carried out to the stack tray 21 and accumulated and stored on the tray.

  Accordingly, in this printout mode, the sheet on which the image is formed by the image forming apparatus A passes through the first carry-in path P1 of the post-processing apparatus B and is accommodated in the stack tray 21, for example, n pages sequentially from page 1 in a face-down posture. It will be loaded and stored in order.

"Staple binding finish mode"
In this mode, the image forming apparatus A forms an image of a series of documents from the first page to the nth page in the same manner as in the above-described mode, carries out the document from the main body discharge port 3 in a face-down state, and enters the first carry-in path P1. The fed sheet is guided to the paper discharge roller 25. Therefore, after the expected time that the leading edge of the sheet reaches the switchback roller 26a of the processing tray 29 based on the signal that the leading edge of the sheet is detected at the paper discharge port 25x, the sheet conveyance control unit 164a moves the switchback roller 26a from the upper standby position onto the tray. Then, the switchback roller 26a is rotated clockwise in FIG. Next, the sheet conveyance control unit 164a drives the switchback roller 26a to rotate counterclockwise in FIG. 2 after the estimated time when the sheet trailing edge is carried onto the processing tray 29. Then, the sheet that has entered from the paper discharge port 25x is switched back and conveyed onto the processing tray 29. By repeating this sheet conveyance, a series of sheets are stacked on the processing tray 29 in a face-down state.

  Note that each time the sheets are stacked on the processing tray 29, the control CPU 161 operates the side aligning unit 34 to align the width direction positions of the sheets to be stacked. Next, the control CPU 161 operates the edge binding unit 31 in response to a job end signal from the image forming apparatus A to bind the trailing edge of the sheet bundle stacked on the processing tray. After this stapling operation, the control CPU 161 moves the sheet bundle carrying-out means 100. Then, the staple-bound sheet bundle is carried out and stored in the stack tray 21. As a result, a series of sheets formed by the image forming apparatus A is stapled and stored in the stack tray 21.

  As mentioned above, although the embodiment of the invention made by the present inventor has been specifically described, the present invention is not limited to the above embodiment, and it goes without saying that various modifications can be made without departing from the scope of the invention. Nor.

  In each of the above-described embodiments, the present invention is applied to an image forming system including a copying machine. However, an image forming system including another image forming apparatus such as a printer, or an image forming apparatus. The present invention can be similarly applied to a single case or a single sheet cutting apparatus.

  As described above, the sheet post-processing apparatus and image forming system according to the present invention can be widely applied to a wide variety of image forming apparatuses such as printers and copiers, and other apparatuses.

A Image forming apparatus 2 Image forming section B Sheet post-processing apparatus BX1 First processing section BX2 Second processing section 20 Casing (apparatus frame)
21 Stack tray (elevating tray)
22 Saddle Tray 23 Carry-in Roller 25 Paper Discharge Roller 26 Switch Back Roller 27 Carrying Roller 29 Processing Tray 31 Edge Binding Unit (Post-Processing Unit)
40 Saddle Stapling Unit (Saddle Stitching Unit)
44 Folding mechanism (middle folding unit)
45 Stacking guide 46 Folding roller pair 47 Folding blade 51 Alignment means 60 Punch unit 70 Driver 75 Clincher 85 Sheet transfer path (paper discharge path)
90 Trimmer unit (sheet cutting device)
95 Support frame 150 Main body control unit 160 Post-processing control unit 201 Trimmer entrance roller pair (bundle conveying means)
202 Bundle conveying press means (pressing means, bundle conveying means)
202b Bundle press roller 202c Bundle press roller 202d, 202e Rotating arm 202f Link rod 203 Paper discharge roller pair 204 Cutting means 204 Cutting blade (cutting means)
205 Sheet retainer 207 Scrap flapper 208 Dust chute 209 Scrap box 210 Registration plate (positioning means)
210a Standing wall portion 211 Registration removal driving portion T Middle folded sheet bundle

Claims (5)

The sheet transporting unit is lowered from above the sheet carried into the processing tray, and the sheet transporting unit brought into contact with the sheet guides the sheet to a predetermined position of the processing tray to perform post-processing. ,
In the sheet post-processing apparatus, wherein the sheet transfer unit is configured such that the lowered position is changed according to the stacking height of the stacked sheets on the processing tray.
The sheet conveying means is lowered and stopped until it comes into contact with the processing tray, and after that, the sheet conveying means is measured until the sheet conveying means reaches a certain height position, and the sheet conveying means is measured based on the measured value. A sheet post-processing apparatus, wherein the sheet post-processing apparatus is configured to have a descending amount with respect to a next descending of the means.   The sheet conveying means is lowered and stopped until it comes into contact with the uppermost surface of the stacked sheets on the processing tray, and then measured after the sheet conveying means reaches a certain height position after being raised. 2. The sheet post-processing apparatus according to claim 1, wherein the sheet post-processing apparatus is configured to set the amount of lowering of the sheet transporting unit with respect to a sheet conveyed next based on the value.   The sheet post-processing apparatus according to claim 1, wherein the sheet post-processing apparatus is configured to perform the measurement a plurality of times and determine the descending amount from a plurality of obtained measurement values.   An image forming apparatus comprising: an image forming unit that forms an image, wherein the sheet post-processing device according to claim 1 is connected to the image forming unit.   An image forming system, wherein the sheet post-processing apparatus according to claim 1 is connected to an image forming apparatus that forms an image.

Images