JP2005060092A - Sheet processing apparatus and image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet processing apparatus capable of preventing a stacking failure and a discharge failure while maintaining a small size and high productivity and capable of high-quality stacking.
In a configuration in which a buffer sheet and a sheet bundle on a processing tray 129 are discharged at the same time, the stack tray 128 stands by at the optimum first position as the sheet bundle leading edge receiving position, so that the trailing edge is leaned, taken out, and leading edge. Prevent rounding phenomenon. Furthermore, the pull-back phenomenon can be prevented by moving the sheet bundle to the second position where it is easy to separate at the start of simultaneous bundle discharge. Further, when the number of sheets bundled is large, the trailing edge of the sheet bundle can be prevented from leaning by raising the bundle receiving position.
[Selection] Figure 1

Description

  The present invention is, for example, a sheet processing apparatus that is provided in an apparatus main body of an image forming apparatus such as a copying machine or a printer and that processes a sheet sent from the apparatus main body, in particular, while processing a sheet, The present invention relates to a sheet processing apparatus capable of storing sheets fed in, and an image forming system including the sheet processing apparatus.

  2. Description of the Related Art In recent years, sheet processing apparatuses such as a sorter for sorting image-formed sheets have been developed as options for image forming apparatuses such as electrophotographic copying machines and laser beam printers. This type of sheet processing apparatus performs at least one process such as a sort process, a binding process, and an alignment process on the sheet.

  In a sheet processing apparatus having a stapler that staples staples, a sheet transported into the main body of the sheet processing apparatus passes through a transport path formed inside the main body and is stacked on a processing tray before performing a binding operation. ing.

  A sheet processing apparatus that binds a bundle of sheets stacks sheets in a bundle on a processing tray and moves a stapler as a binding unit to perform one-point binding or multiple-point binding (usually two-point binding). ing. While the binding operation is being performed, sheets for the next job cannot be stacked on the processing tray. For this reason, it is necessary to leave an interval between sheets between job units in which the binding operation is performed.

  However, productivity (productivity) falls when the space | interval of sheets is opened. That is, the number of sheets processed per unit time is reduced. As a sheet processing apparatus for preventing such a decrease in productivity, there is an apparatus in which a sheet holding unit (buffer unit) for storing sheets and waiting them is provided in a conveyance path in the middle of conveying a sheet to a processing tray. .

  This sheet processing apparatus stores a plurality of subsequent sheets in the sheet holding unit while processing a plurality of sheets stacked on the processing tray, and stores them in the sheet holding unit when the processing is completed. The sheets (buffer sheets) that have been printed are stacked on the processing tray, and subsequent subsequent sheets are supplied to the processing tray until the desired number of sheets is reached.

  There are two types of sheet processing apparatuses provided with such a sheet holding unit. First, as a first type, when the processing of the sheet bundle on the processing tray is finished, the sheet processing apparatus of the single bundle discharge system discharges the sheet bundle on the processing tray and then discharges the buffer sheet to the processing tray. (For example, refer to Patent Document 1). In the second type, when the processing of the sheet bundle on the processing tray is completed, the bundle discharging operation for discharging the sheet bundle on the processing tray from the processing tray and the operation for discharging the buffer sheet to the processing tray are performed simultaneously. There is a simultaneous bundle discharge type sheet processing apparatus. This simultaneous bundle discharge type sheet processing apparatus has been filed by the present applicant, but has not been disclosed at this time.

Further, since the simultaneous bundle discharge method stacks a part of the sheets on the processing tray and the buffer sheet, there is an advantage that the apparatus can be reduced in size compared to the single bundle discharge method in which the sheets are stacked at different places (FIG. 38). ).
JP-A-9-48545

  In the bundle discharge operation of the single bundle discharge method and the simultaneous bundle discharge method, if the stack tray that receives the front end of the sheet bundle is too high, the rear end of the sheet bundle leans against the stacking wall (rear end leaning phenomenon) or the sheet to be discharged A phenomenon that the bundle pushes the already stacked sheets on the stack tray (a take-out phenomenon) occurs. If the stack tray is too low, the leading edge of the sheet bundle to be discharged is rounded (the leading edge is rounded). These phenomena cause poor loading on the stack tray. For this reason, in the conventional single bundle discharge method, the stack tip receiving position of the stack tray is set to an optimum position where the above-described problem does not occur.

  However, in the simultaneous bundle discharging method proposed in recent years, when the stack tray position is the optimum bundle leading edge receiving position described above when the trailing edge of the sheet bundle passes through the trailing edge of the discharge roller, It takes time to separate the sheet bundle. If the return operation of the buffer sheets to the processing tray is started before these two sheet bundles are completely separated, the sheet bundle on the processing tray does not fall on the stack tray but is pulled back to the processing tray again ( Pull back phenomenon). If the bundle front end receiving position is lowered, the height difference between the rear end of the bundle and the stack tray becomes larger and the separation becomes easier, but the leading edge rounding phenomenon, which has been a problem in the past, will occur.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a sheet processing apparatus that can prevent stacking failure and discharge failure while maintaining downsizing and high productivity of the apparatus, and can perform high-quality stacking.

  In order to achieve the above object, a sheet processing apparatus of the present invention includes a buffering unit that buffers a sheet discharged from an image forming apparatus, a conveyance unit that conveys a buffered sheet from the buffering unit, and a buffer. A first stacking unit (processing tray) for stacking sheets conveyed from the ring unit; a second stacking unit disposed behind the first stacking unit; and a bundle discharging unit (swinging) configured in the first stacking unit A pair of rollers and a rear end assist), and the conveying means and the bundle discharging means discharge the sheet conveyed from the buffering means to the first stacking means and the sheet stack stacked on the first stacking means to the second stacking The simultaneous discharge control means for simultaneously discharging to the means, and after discharging the sheet bundle stacked on the first stacking means to the second stacking means, In the sheet processing apparatus having a buffering stacking control unit for stacking the buffering sheet conveyed from the stacking unit on the first stacking unit, the second stacking unit waits at the first position or moves when the simultaneous bundle discharge control is started. At the end of the simultaneous bundle discharge control, the second stacking means moves so as to be in the second position.

  In addition, there is provided second position height switching means for switching the height of the second position of the second stacking means according to the number of sheet bundles stacked on the first stacking means, and the number of sheet bundles is known. When the number is greater than the predetermined number, the second position is set higher than when the number of sheet bundles is smaller than the known predetermined number.

  As described above, if the present invention is organized and summarized, it can be integrated into the following configurations.

(1) buffering means for buffering sheets discharged from the image forming apparatus;
Conveying means for conveying the buffered sheet from the buffering means;
First stacking means for stacking sheets conveyed from the buffering means;
A second loading means disposed behind the first loading means;
Consists of a bundle discharging means configured as a first loading means,
Simultaneous discharge control means for discharging the sheet conveyed from the buffering means to the first stacking means and simultaneously discharging the sheet bundle stacked on the first stacking means to the second stacking means by the conveying means and the bundle discharging means;
Buffering stacking control for stacking the buffering sheet conveyed from the buffering means onto the first stacking means by the reverse operation of the bundle discharging means after discharging the sheet bundle stacked on the first stacking means to the second stacking means In a sheet processing apparatus having means,
The second stacking unit waits or moves to the first position at the start of simultaneous bundle discharge control,
The sheet processing apparatus, wherein at the end of the simultaneous bundle discharge control, the second stacking unit moves so as to be in the second position.

(2) second position height switching means for switching the height of the second position of the second stacking means according to the number of sheet bundles stacked on the first stacking means;
The sheet processing according to (1), wherein when the number of sheet bundles is larger than a known predetermined number, the second position is set higher than when the number of sheet bundles is smaller than a known predetermined number. apparatus.

(3) buffering means for buffering sheets discharged from the image forming apparatus;
Conveying means for conveying the buffered sheet from the buffering means;
A first stacking unit (processing tray) for stacking sheets conveyed from the buffering unit;
A second loading means disposed behind the first loading means;
Consists of a bundle discharging means (a pair of swinging rollers and a rear end assist) configured as a first stacking means,
Simultaneous discharge control means for discharging the sheet conveyed from the buffering means to the first stacking means and simultaneously discharging the sheet bundle stacked on the first stacking means to the second stacking means by the conveying means and the bundle discharging means;
Buffering stacking control for stacking the buffering sheet conveyed from the buffering means onto the first stacking means by the reverse operation of the bundle discharging means after discharging the sheet bundle stacked on the first stacking means to the second stacking means In a sheet processing apparatus having means,
The second stacking unit waits or moves to the first position at the start of simultaneous bundle discharge control,
An image forming system, wherein at the end of simultaneous bundle discharge control, the second stacking means moves so as to be in the second position.

(4) Second position height switching means for switching the height of the second position of the second stacking means according to the number of sheet bundles stacked on the first stacking means,
The image formation according to (3), wherein when the number of sheet bundles is larger than a known predetermined number, the second position is set higher than when the number of sheet bundles is smaller than a known predetermined number. system.

  In the present invention, by causing the stack tray to stand by at the optimum first position as the bundle front end receiving position, the rear end is leaned, taken out, and the front end is curled. Furthermore, the pull-back phenomenon can be prevented by moving the sheet bundle to the second position where it is easy to separate at the start of simultaneous bundle discharge. In addition, since it is not necessary to delay the start of the return control of the buffer sheet to the processing tray, it is possible to prevent a stacking failure and a discharge failure while maintaining high productivity and to perform high-quality stacking.

  In the present invention, when the number of sheets is large, the trailing edge of the sheet bundle can be prevented from leaning by raising the bundle receiving position.

  Embodiments of the present invention will be described below with reference to the drawings.

  Hereinafter, a sheet processing apparatus according to an embodiment of the present invention and a copier as an example of an image forming apparatus having the sheet processing apparatus will be described with reference to the drawings. The image forming apparatus includes a copying machine, a facsimile machine, a printer, and a complex machine of these, and the image forming apparatus equipped with the sheet processing apparatus is not limited to the copying machine.

  It should be noted that the dimensions, numerical values, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are intended to limit the scope of the present invention only to those unless otherwise specified. It is not a thing.

  In the description of the present embodiment, an example will be described in which the sheet processing apparatus is an independent apparatus configured to be detachable from the apparatus main body of the image forming apparatus as an independent apparatus. However, it goes without saying that the sheet processing apparatus of the present invention is also applied to a case where the sheet processing apparatus is integrally provided in the image forming apparatus, but there is no particular functional difference from the case of the sheet processing apparatus described below. Therefore, the description is omitted.

  FIG. 1 is a schematic cross-sectional view showing a state where a sheet processing apparatus is mounted on a copying machine. The sheet processing apparatus is specifically a finisher, for example.

(Image forming device)
The copying machine 100 includes an apparatus main body 101 and a sheet processing apparatus 119. A document feeder 102 is provided on the upper part of the apparatus main body 101. The document D is placed on the document placing unit 103 by the user, and is sequentially separated one by one by the feeding unit 104 and supplied to the registration roller pair 105. Subsequently, the document D is temporarily stopped by the registration roller pair 105, a loop is formed, and skew is corrected. Thereafter, the document D passes through the introduction path 106 and passes through the reading position 108, whereby the image formed on the surface of the document is read. The document D that has passed the reading position 108 passes through the discharge path 107 and is discharged onto the discharge tray 109.

  When reading both the front and back sides of a document, first, the document D passes through the reading position 108 as described above, whereby an image on one side of the document is read. Thereafter, the document D passes through the discharge path 107, is switched back by the reverse roller pair 110, and is sent again to the registration roller pair 105 in a state where the front and back are reversed.

  Then, in the same manner as when the image on one side is read, the skew of the original D is corrected by the registration roller pair 105, and the image on the other side is read at the reading position 108 through the introduction path 106. It is done. Then, the document D passes through the discharge path 107 and is discharged to the discharge tray 109.

  On the other hand, the image of the document passing through the reading position 108 is irradiated with light from the illumination system 111. The reflected light reflected from the document is guided to the optical element 113 (CCD or other element) by the mirror 112 and obtained as image data. Then, a laser beam based on the image data is irradiated onto, for example, the photosensitive drum 114 serving as an image forming unit to form a latent image. Although not shown in the figure, the mirror 112 may be configured to directly irradiate the photosensitive drum 114 with reflected light to form a latent image.

  The latent image formed on the photosensitive drum 114 is further formed with a toner image by toner supplied from a toner supply device (not shown). The cassette 115 is loaded with a recording medium that is a sheet of paper or plastic film. The sheet is sent out from the cassette 115 in response to the recording signal, and enters between the photosensitive drum 114 and the transfer device 116 at the timing of entry between the photosensitive drum 114 and the transfer device 116 by the registration roller pair 150. Then, the toner image on the photosensitive drum 114 is transferred to the sheet by the transfer device 116. The sheet on which the toner image is transferred passes through the fixing device 117 and is fixed by the heat and pressure of the fixing device 117.

  When images are formed on both sides of the recording medium, the sheet on which the image is fixed on one side by the fixing device 117 passes through the double-sided path 118 provided on the downstream side of the fixing device 117, and again, the photosensitive drum 114 and the transfer device. The toner image is also transferred to the back surface. Then, the toner image is fixed by the fixing device 117 and is discharged to the outside (finisher 119 side).

  FIG. 2 is a control block diagram of the entire copying machine. The entire copying machine 100 is controlled by the CPU 201. In the CPU 201, there are provided a ROM 202 that stores a sequence of each unit, that is, a control procedure, and a RAM 203 that temporarily stores various information as necessary. The document feeder controller 204 controls the document feeding operation of the document feeder 102. The image reader control unit 205 controls the illumination system 111 and the like to control reading of a document. The image signal control unit 206 receives the reading information of the image reader control unit 205 or the image information sent from the external computer 207 via the external I / F 208, processes the information, and processes the printer control unit. A processing signal is sent to 209. The printer control unit 209 controls the photosensitive drum 114 and the like based on the image processing signal from the image signal control unit 206 so that an image can be formed on the sheet.

  The operation unit 210 can input sheet size information when the user uses the copier, what kind of processing is performed on the sheet, for example, information on stapling, and the like. The information such as the operation state of the apparatus main body 101 and the finisher 119 which is a sheet post-processing apparatus can be displayed. The finisher control unit 211 controls the operation in the finisher 119 that is a sheet post-processing apparatus. The FAX control unit 212 controls the copier so that the copier can be used as a fax machine, and can exchange signals with other fax machines.

(Sheet processing equipment)
FIG. 3 is a longitudinal sectional view of the sheet processing apparatus. FIG. 4 is a longitudinal sectional view showing each drive system. FIG. 5 is a cross-sectional view of the main part of the sheet processing apparatus. FIG. 6 is a control block diagram of the sheet processing apparatus. 8 to 10 are diagrams showing the relationship between the moving speed of the rear end assist 134 and the sheet conveying speed of the swing roller pair 127 with respect to the elapsed time. FIG. 8 is a diagram of a single bundle discharge sequence in which the sheet bundle is sent out by the rear end assist 134 and the swing roller pair 127. FIG. 9 is a diagram of bundle discharge control when the starting speeds of the rear end assist 134 and the swing roller pair 127 are different. FIG. 10 is a diagram of a simultaneous bundle discharge sequence in which the sheet bundle and the buffer sheets stored in the buffer unit 140 are simultaneously conveyed by the rear end assist, the swing roller pair, and the first conveyance roller pair.

  The sheet processing apparatus 119 of this embodiment includes a buffer unit 140 that accumulates (buffers) a plurality of sheets in a straight state when the stapler unit 132 is operated.

  Since the buffer unit 140 is configured to store a plurality of sheets in a straight state, the buffer unit 140 can be flattened unlike a conventional mechanism having a buffer roller, for example, so that the sheet processing can be performed. The device can be reduced in size and weight. Furthermore, since the sheets can be stored in a straight state, unlike the buffer roller, the sheets are not rounded, so that the sheets can be handled more easily, and the sheet processing time of the sheet processing apparatus can be reduced accordingly. can do.

  The sheet processing apparatus is controlled by a finisher control unit 211. In the CPU 221 of the finisher control unit 211, a ROM 222 storing a control sequence (sequence) of the sheet processing apparatus 119 that operates based on an instruction from the CPU circuit 200 of the copying machine main body, and the sheet processing apparatus 119. A RAM 223 or the like for storing information necessary for controlling each time is provided. Further, a paper surface detection sensor 224 that operates based on an operation of a paper surface detection lever 133 described later is connected to the finisher control unit 211. The CPU 221 controls the raising / lowering of the stack tray 128 based on the sheet detection signal of the paper surface detection sensor 224. The finisher control unit 211 includes an inlet conveyance motor M2 that rotates the inlet roller pair 121, the buffer roller 124, and the first paper discharge roller pair, a bundle discharge motor M3 that rotates the swing roller pair 127 and the return roller 130, and a bundle Based on the above-described sequence, the operation of the lower bundle clutch CL and the like that transmits or rejects the rotation of the discharge motor M3 to the lower roller 127b is controlled.

  Note that the CPU circuit unit 200 and the finisher control unit 211 in FIG. 2 may be integrated.

(Explanation of single bundle discharge operation)
When the user selects the sheet binding processing display on the operation unit 210 (see FIG. 2) of the copying machine 100, the CPU circuit 200 controls each part of the apparatus main body to move the copying machine to a copying operation and finisher. A sheet binding processing signal is sent to the control unit 211.

  The operation description based on FIGS. 11 to 17 is based on the case where the CPU circuit 200 determines that the length of the sheet is long based on the sheet size information input by the user to the operation unit 210 (for example, A3 size). Or a special sheet having an attribute different from that of a normal sheet, such as thick paper, thin paper, tab paper, and color paper, depending on the sheet type information. That is, the operation explanation based on FIGS. 11 to 17 is an explanation when the operation of stacking a buffer sheet to be described later on the processing tray 129 is started after the sheet bundle is discharged to the stack tray 128. . Of course, the operation described below may be performed regardless of the length of the sheet and whether or not the sheet is a special sheet.

  The finisher control unit 211 starts the entrance conveyance motor M2 and the bundle discharge motor M3 based on the sheet binding processing signal. The finisher control unit 211 operates the buffer roller separation plunger SL1 (see FIG. 4) to move the buffer roller 124 away from the lower transport guide plate 123b, and further operates a plunger (not shown) to rotate the swing roller pair 127. The upper roller 127a is separated from the lower roller 127b. Note that the start and stop of the inlet conveyance motor M2 and the bundle discharge motor M3 may be controlled one by one in accordance with the movement of the sheet.

  The first sheet sent from the discharge roller pair 120 of the apparatus main body 101 of the copying machine 100 (see FIG. 1) is entered by the guide of the conveyance flapper 122 of the receiving roller pair 137 shown in FIGS. It is conveyed to the roller pair 121. The receiving roller pair 137 is rotated by a common transport motor M1 that rotates the discharge roller pair 120.

  As shown in FIG. 11A, the inlet roller pair 121 is rotated by an inlet conveyance motor M2 (see FIG. 4) to convey the first sheet P1. The sheet P1 is conveyed to the first paper discharge roller pair 126 by the guide 123 formed by the upper conveyance guide plate 123a and the lower conveyance guide plate 123b.

  The sheet P1 is further conveyed by the rotation of the first paper discharge roller pair 126 as shown in FIG. 11B, and is discharged to the stack tray 128 as shown in FIG. As shown in FIG. 12B, the sheet P1 falls across the stack tray 128 and the processing tray 129. Thereafter, as shown in FIGS. 13A and 13B, the upper roller 127a is lowered by a plunger (not shown), and the sheet is sandwiched between the lower roller 127b (S101 in FIG. 7).

  At this time, the upper roller 127a and the bundle discharge motor M3 (see FIG. 4) have already been rotated in the direction of the arrow. Further, the return roller 130 that can contact and separate from the processing tray 129 is also rotated in the direction of the arrow by the bundle discharge motor M3 (see FIG. 4). However, the lower roller 127b is idled by the operation of the lower bundle clutch CL (see FIG. 4) (S102). This is because, when the second and subsequent sheets are stacked after the first sheet is stacked on the processing tray 129, if the lower roller 127b is rotating, the lower roller 127b also stops the first sheet. This is because the sheet may be pushed into the side 131 to cause wrinkles on the first sheet.

  After the elapse of about 150 mmsec after the under-clutch clutch CL is actuated (S103), as shown in FIG. 14A, the rotation of the swing roller pair 127 and the return roller 130 causes the sheet to fall to the right side on the processing tray 129. Slide down in the direction of the arrow. At that time, the rear end assist 134 is in a standby position. Then, before the sheet P1 comes into contact with the stopper 131, the upper roller 127a is separated from the sheet P1. The sheet P1 is abutted against the stopper 131 by the return roller 130. Thereafter, sheet width alignment is performed by a known pair of alignment plates 144 (see FIG. 5) (S104).

  Thereafter, the subsequent sheets are similarly stacked on the processing tray 129. As shown in FIG. 15, when a predetermined number of sheets are stacked on the processing tray 129, the bundled sheets are bound by the stapler 166 shown in FIGS. The sheet bundle may be punched by a punch unit (not shown) instead of being bound by the stapler 166.

  When the sheet bundle is bound, as shown in FIG. 16A, the stack tray 128 moves to a position detected by the paper surface detection lever 133 and waits at a position where it can easily receive the discharged sheet bundle. (S105).

  As shown in FIG. 16B, the upper roller 127a rotates in the direction of the arrow with the sheet bundle P sandwiched between the lower roller 127b, and the rear end assist 134 pushes the rear end of the sheet bundle P to remove the sheet bundle. It is discharged to the stack tray 128.

  At this time, as shown in FIG. 8 and FIG. 9, the start time (T1) and the start speed (132 mm / sec) of the swing roller pair 127 and the rear end assist 134 are the same, and the same acceleration end speed (500 mm / sec). When the same time (T2) is reached, the swing roller pair 127 and the rear end assist 134 can discharge the sheet bundle without applying a pulling force or a compressing force to the sheet bundle (S106). .

  However, as shown in FIG. 9, the starting speed of the rear end assist 134 is higher than the starting speed of the swing roller pair 127 by the belts 143, 142 and the like that transmit the rotational force of the rear end assist motor M4 to the rear end assist 134. In some cases, it may be fast (assuming 300 mm / sec). In such a case, until the time T3 when the sheet conveying speed of the rocking roller pair 127 is 300 m / sec, the rear end assist 134 is stopped without starting to move, and when the sheet conveying speed of the rocking roller pair 127 is reached. , Start moving. That is, the rear end assist 134 is started after (T3−T1) = ΔT time after the swing roller pair 127 is started (S107). If the starting speed of the swing roller pair 127 is faster than that of the rear end assist 134, the start time of the swing roller pair 127 is delayed by ΔT. If the starting speed of the swing roller pair 127 and the starting speed of the rear end assist 134 are the same, ΔT is zero.

  As described above, when a time difference of ΔT is provided at the time of starting, the swing roller pair 127 and the rear end assist 134 are pulled by the sheet bundle even if the difference in the starting speeds is matched between the swing roller pair 127 and the rear end assist 134. The sheet bundle can be discharged without applying force or compression force. Further, the rubbing trace of the roller by the swing roller pair 127 does not adhere to the sheet, and the quality of the sheet bundle and the image quality of the sheet bundle are not deteriorated.

  The sheet bundle is started to be fed to the stack tray 128 side by the swing roller pair 127, the rear end assist 134, and the return roller 130 (S108). The rear end assist 134 returns to the original position (home position) when it has moved about 15 mm (S109) (S110, an operation corresponding to “HP delivery control” in FIG. 8). As shown in FIG. 17, the sheet bundle is discharged onto the stack tray 128 by the swing roller pair 127. Thereafter, when the upper roller 127a of the swing roller pair 127 is separated from the lower roller 127b, a series of sheet bundle discharging operations is completed (S111, S112).

  In FIG. 16B, when the sheet bundle starts to be discharged, the first sheet of the next sheet bundle is fed into the inlet roller pair 121.

  In the sheet processing apparatus 119 of the present embodiment, the trailing edge assist 134 pushes the trailing edge of the sheet bundle and conveys the sheet bundle. Therefore, unlike the case where the sheet bundle is discharged by rotating the roller against the surface of the sheet bundle, The sheet bundle can be reliably conveyed without damaging the surface of the sheet bundle.

(Description of buffer operation and simultaneous bundle discharge)
The explanation of the operation is as follows. When the conveyance interval between sheets is narrow and a subsequent sheet is fed while processing a sheet bundle, the subsequent sheet is stored only during the binding process (buffered). This is a description of the buffer operation.

  The sheet processing apparatus 119 uses a buffer operation command of the finisher control unit 211 when the CPU circuit 200 of the apparatus main body 101 determines that the interval between sheets sent from the apparatus main body 101 of the copying machine 100 is shorter than the sheet binding processing time. Based on this, a buffer operation is performed. In this case, the buffer roller 124 is lowered by the plunger SL1 (see FIG. 4) and is in contact with the lower conveyance guide plate 123b.

  In FIG. 18, it is assumed that a sheet bundle is stacked on the processing tray 129 based on the above-described operation. The sheet bundle is assumed to be bound by the stapler unit 132 (see FIGS. 3 and 4).

  As shown in FIG. 18A, when the first sheet P1 of the next sheet bundle is fed while the stapling process is being performed on the sheet bundle P stacked on the processing tray 129, The sheet P1 is fed into the buffer roller 124 by the inlet roller pair 121. The buffer roller 124 is rotated by an inlet conveyance motor M2 (see FIG. 4) to convey the sheet P1 downstream. At this time, the upper first paper discharge roller 126a of the first paper discharge roller pair 126 is separated from the lower first paper discharge roller 126b by the first paper discharge roller separation plunger SL2 (see FIG. 4). The first paper discharge roller separation plunger SL2 is not shown in FIG. 4 because it appears to overlap the buffer roller separation plunger SL1 in FIG. The upper roller 127a of the swing roller pair 127 is also separated from the lower roller 127b by a plunger (not shown).

  As shown in FIG. 18B, when the rear end of the sheet P1 reaches the switchback point SP, it is returned to the upstream side by the reverse rotation of the buffer roller 124 as shown in FIG. At substantially the same time, the rear end press 135 is separated from the lower transport guide plate 123b, and the rear end receiving portion 136 is opened. The switchback point SP is reached after a predetermined time after the inlet sensor S1 disposed near the downstream side of the inlet roller pair 121 shown in FIG. It can be detected by the rotational speed of the roller 124 or the like.

  The upstream end side of the sheet P1 after the downstream end of the sheet is detected is received by the rear end receiving portion 136 as shown in FIG. Thereafter, as shown in FIG. 19B, the rear end presser 135 returns to the original position and presses the sheet P1 against the lower conveyance guide plate 123b by the friction member 141 provided on the rear end presser 135.

  Thereafter, as shown in FIG. 20A, the second sheet P2 is fed. The second sheet P <b> 2 is conveyed by the entrance roller pair 121. At this time, the sheet P2 passes over the rear end press 135. Thereafter, the sheet P2 is also conveyed by the buffer roller 124 as shown in FIG.

  At this time, the first sheet P1 is pressed against the lower conveyance guide plate 123b together with the second sheet P2 by the buffer roller 124, and follows the second sheet P2 conveyed to the downstream side. Try to move. However, since the first sheet P1 is pressed against the lower transport guide plate 123b by the friction member 141 provided on the rear end press 135, it does not move.

  Similarly to the first sheet P1, the second sheet P2 is returned to the upstream side as shown in FIGS. 21 and 22 when the rear end reaches the switchback point SP. Then, the second sheet P2 is pressed against the lower conveyance guide plate 123b by the friction member 141 of the rear end press 135 so as to overlap the first sheet P1.

  Thereafter, as shown in FIG. 23A, when the third sheet P3 is fed and the rear end of the sheet P3 passes through the inlet roller pair 121, as shown in FIG. The first sheet discharge roller pair 126a sandwiches the first to third sheets with the lower first sheet discharge roller pair 126b. At this time, the third sheet P3 slightly protrudes further downstream than the first and second sheets P1 and P2. At this time, since the binding process for the sheet bundle on the processing tray 129 has been completed, the trailing edge assist 134 moves along the processing tray 129 as shown in FIG. Push up the edge. As a result, the downstream end Pa of the sheet bundle P protrudes by a length L further downstream than the downstream ends P1a and P2b of the first and second sheets P1 and P2.

  Then, as shown in FIG. 24B, the upper roller 127a is also lowered, and the three sheets P1, P2, P3 and the sheet bundle P are sandwiched by the lower roller 127b. Along with this, the trailing edge press 135 is separated from the second sheet P2, and the first sheet P1 and the second sheet P2 are released.

  Thereafter, the three sheets P1, P2, and P3 and the sheet bundle P are sandwiched and conveyed by the swing roller pair 127. Then, as shown in FIGS. 25A and 25B, when the sheet bundle P is discharged to the stack tray 128, the rear ends of the first sheet P1 and the second sheet P2 become the first discharge. After exiting from the paper roller pair 126, the upstream portion of the three sheets is received by the processing tray 129. At the same time as the simultaneous bundle discharging operation is started, the stack tray is lowered so that the sheet bundle discharged from the buffer sheet and the processing tray can be separated in a short time.

  As shown in FIGS. 26A and 26B, the three sheets are transported down on the processing tray 129 by the swing roller pair 127 and the return roller 130 and received by the stopper 131. During this time, the stack tray 128 is once lowered, lowers the upper surface of the sheet bundle below the paper surface detection lever 133, then rises again, and rises when the paper surface detection lever 133 is actuated by the upper surface of the sheet bundle. To stop. As a result, the upper surface of the sheet bundle on the stack tray 128 can be held at a predetermined height. Thereafter, the sheets are sequentially stacked on the processing tray 129 without being stored on the lower conveyance guide plate 123b, and are bound when a predetermined number of sheets are reached. During this binding operation, the first three sheets of the subsequent sheet bundle are collected on the lower conveyance guide plate 123b.

  In the above description, three sheets are stored on the lower transport guide plate 123b. However, the number of sheets (buffer sheets) stored is the sheet length, the binding time, and the sheet transport. Since it varies depending on the speed and the like, it is not limited to three.

(Explanation of stack tray control)
The tray control at the time of simultaneous bundle discharge of the sheet processing apparatus according to the present invention will be described. 36 (a) and 36 (b) are cross-sectional views showing the tray operation during simultaneous bundle discharge. 37A and 37B are diagrams showing the relationship between the moving speed of the stack tray and the sheet conveying speed of the swing roller pair 127 with respect to the elapsed time.

  First, the tray control of six or less sheet bundles in which a phenomenon that the sheet bundle generated at the time of simultaneous bundle discharge is returned to the processing tray again (retraction phenomenon) will be described.

  Simultaneous bundle discharge is started from the standby position [1] in FIG. This standby position is set to a position higher than the lower limit of the sheet bundle leading edge receiving position where the trailing edge leans, takes out, and leading edge curling does not occur. As shown in FIG. 37A, when the simultaneous bundle discharge is started, the stack tray is lowered almost simultaneously to a position where the sheet bundle is easily separated (bundle receiving position). In the case of six or less sheet bundles, the bundle receiving position is lower than that of the seven or more sheet bundles and the movement distance is long, so that the sheet bundle moves at a higher speed than the seven or more sheet bundles as shown in FIG. Thereby, when the sheet bundle lands on the stack tray, the position of the stack tray can be moved to the optimum bundle receiving position.

  As shown in [2] in FIG. 36A, the movement of the sheet bundle to the bundle receiving position is finished, and the returning operation of the buffer sheet to the processing tray is started from the state where the sheet bundle is separated from the buffer sheet. [3] in FIG. 36A is a diagram illustrating a state in which the buffer sheet is accommodated in the processing tray.

  In parallel with the return operation of the buffer sheet to the processing tray, a paper surface detection operation is performed to prepare for the next bundle discharge of the sheet bundle as shown in [4] of FIG.

  Next, simultaneous bundle discharge of seven or more sheet bundles will be described.

  With respect to seven or more sheet bundles, when the stack tray is lowered to the same position as six or less sheets at the time of simultaneous bundle discharge, the sheet bundle is bent on the stack tray due to the weight of the sheet bundle. As a result, the sheet bundle conveyance load increases, and the bundle cannot be conveyed to the expected position. As a result, a stacking failure such that the trailing edge of the sheet bundle leans against the stacking wall occurs. For this reason, the bundle receiving position of seven or more sheet bundles that are easily separated by the weight of the sheet bundle is set to a position higher than that of six or less sheet bundles.

  Simultaneous bundle discharge is started from the standby position in the state [1] in FIG. This standby position is set to a position higher than the lower limit of the sheet bundle leading edge receiving position where the trailing edge leans, takes out, and leading edge curling does not occur. Simultaneously discharging the bundle, simultaneously lowering the stack tray to the bundle receiving position.

  As shown in [2] of FIG. 36B, the movement of the sheet bundle to the bundle receiving position is finished, and the returning operation of the buffer sheet to the processing tray is started from the state where the sheet bundle is separated from the buffer sheet. It is the figure which showed a mode that the [3] buffer sheet | seat of FIG.

  In parallel with the return operation of the buffer sheet to the processing tray, a paper surface detection operation is performed as shown in [4] and [5] in FIG. 36B to prepare for the next sheet bundle bundle discharge.

(Explanation of flowchart)
(Description of sort processing operation)
A series of operations of the buffer, post-processing, and simultaneous bundle discharge of the sheet processing apparatus 119 will be described with reference to the flowcharts shown in FIGS. Note that the flowchart describes the case where two buffers are used.

  FIG. 28 is a flowchart for explaining the schematic operation of the entire sheet processing apparatus 119, and is a flowchart of sort processing. The operation of each unit shown in these flowcharts is performed under the control of the finisher control unit 211 shown in FIG.

  In the sort processing (S301), the sheet processing apparatus 119 determines whether or not the first sheet stacked on the processing tray 129 is the first sheet (S302), whether or not the buffer counter is 1 (S303), Based on the determination of whether or not the sheet is the final sheet (S304), any of the in-machine top sheet operation (S307), the buffer final sheet operation (S308), the buffer sheet operation (S309), or the intermediate sheet operation (S310) Do something.

  The in-machine top sheet sheet operation (S307) in FIG. 28 is an operation until the top sheet is stacked on the processing tray 129 and sheet processing is started, as indicated by reference numerals S401 to S420 in FIG.

  The buffer final sheet operation (S308) in FIG. 28 is an operation until the buffer sheet is stacked on the processing tray 129 and the post-processing operation is started, as indicated by reference numerals S501 to S537 in FIG. is there.

  In FIG. 28, the buffer sheet operation (S309) is an operation of accumulating (buffering) the buffer sheet in the guide 123 as indicated by reference numerals S601 to S613 in FIG.

  The intermediate sheet operation (310) in FIG. 28 is an operation until the second and subsequent sheets are stacked on the processing tray 129 and sheet processing is started, as indicated by reference numerals S701 to S716 in FIG. .

  The start of post-processing operation of reference numeral S419 in FIG. 29, reference numeral S537 in FIG. 31, and reference numeral S715 in FIG. 33 is discharged from the apparatus main body 101 of the copying machine 100, as indicated by reference numerals S201 to S221 in FIG. This is an operation of performing post-processing after stacking sheets on the processing tray 129.

(Explanation of post-processing operation)
First, the CPU 221 (see FIG. 6) controls the front alignment motor M5 and the back alignment motor M6, and is arranged along both sides in the sheet conveyance direction and approaches and separates in a direction intersecting the sheet conveyance direction. The front alignment plate 144a and the back alignment plate 144b (see FIG. 5) are brought close to the sheet to align both sides of the sheet (S201, S202). For example, in the case of a large sheet such as B4 size that needs to be aligned twice (S203), after 100 msec has elapsed (S204), the front alignment plate 144a and the back alignment plate 144b are once separated from the sheet and retracted ( S205, S206). After 50 msec (S207), the front alignment plate 144a and the back alignment plate 144b (see FIG. 5) are brought close to the sheet again, and the second alignment operation is performed (S208). After completing the series of alignment operations (S209), the CPU 221 controls the bundle discharge motor M3 to stop the reverse rotation operation of the swing roller pair 127 (S210).

  Thereafter, the CPU 221 determines whether the sheet is the final sheet in the bundle based on the final sheet information of the sheet bundle from the CPU circuit 200 of the apparatus main body 101 or based on the number of sheets from the counter for counting the number of sheets ( S211). If it is not the final sheet, the CPU 221 controls the front alignment motor M5 and the back alignment motor M6 (see FIG. 8) to return the front alignment plate 144a and the back alignment plate 144b (see FIG. 5) to the retracted positions (S222, S223). ).

  In S211, in the case of the final sheet, the final sheet in the bundle is bound to the bundle of sheets by the stapler unit 132 (S212). Then, the stapler motor M9 is controlled to bind the sheet bundle with the stapler 166 (S2113, S214). Thereafter, the CPU 221 controls the rear end assist motor M4 (see FIGS. 5 to 8) and causes the rear end assist 134 to project the sheet bundle by a length L as shown in FIG. 24 (see FIG. 24). (S215, S216).

  After that, the CPU 221 binds based on sheet attribute information input to the operation unit 210 (see FIG. 2) by the user, such as sheet size, sheet material (paper quality), thick sheet, thin sheet, tab sheet, and color sheet. When it is determined that the sheet bundle is a sheet that cannot be discharged at the same time (simultaneous bundle discharge is not possible), or when the next sheet of the bound sheet bundle is a buffer that cannot be buffered (S217), the bundle is discharged. By controlling the motor M3, only the bound sheet bundle is discharged from the processing tray 129 to the stack tray 128 (single bundle discharge), and the post-processing operation is completed (S221, S224).

  Even when the next sheet is not jammed and sent to the buffer unit 140, the CPU 221 controls the bundle discharge motor M3 to discharge only the bound sheet bundle from the processing tray 129 to the stack tray 128 ( After the single bundle is discharged, the post-processing operation is completed (S218, S221, S224).

  When both the sheet on the processing tray 129 and the buffer sheet stored in the guide 123 meet the conditions of S218 and S219, the CPU 122 controls the inlet transport motor M2, the bundle discharge motor M3, and the lower bundle clutch CL, thereby the processing tray. At the same time as the sheet bundle on 129 is discharged to the stack tray 128, the accumulated sheets are discharged from the guide 123 to the processing tray 129. That is, the bundle is simultaneously bundled (S220, S224). The simultaneous bundle discharge is executed under the control of the buffer final sheet in response to completion of the simultaneous bundle discharge preparation in S220.

  The single bundle discharge operation (S221) in FIG. 35 does not discharge the bound sheet bundle at the same time as the buffer sheets, but discharges only the bound sheet bundle on the processing tray 129, as indicated by reference numerals S101 to S112 in FIG. It is an operation to do.

(Explanation of stack tray operation)
Next, control of the stack tray at the time of simultaneous bundle discharge will be described with reference to FIG. 30 of the flowchart of the buffer final sheet and FIG. 39 of the stack tray operation flowchart.

  First, the sheet conveyed to the sheet processing apparatus 119 is conveyed to the buffer stop position, and the nip of the first discharge roller pair 126, the separation of the inlet roller pair 121, the nip of the buffer roller 124, and the release of the trailing edge paper press 135 are released. To prepare for simultaneous bundle discharge (S501 to S510). Next, after the elapse of 150 ms from the start of the swinging operation, the alignment plate is retracted and waits for completion of simultaneous bundle discharge preparation.

  When the simultaneous bundle discharge preparation is completed (S220), the stack tray operation is started (S514). In the stack tray operation, first, it is determined whether or not the sheet bundle is 6 sheets or less (S801). If it is determined that the number of sheet bundles is six or less, the stack tray 128 is lowered by 25 mm (S802) so that the buffer sheet and the processing tray sheet bundle can be easily separated. Thereby, it is possible to prevent a discharge failure such that the processing tray sheet bundle is pulled back to the processing tray again.

  Next, 150 ms elapses after the stack tray descends (S803). When 150 ms elapses after the stack tray descends, the stack tray paper surface detection operation is started (S806), and the stack tray operation is ended (S807).

  If it is determined in step S801 that the sheet bundle is not 6 sheets or less, the stack tray is lowered by 10 mm (S804), the buffer sheet and the process tray sheet bundle are easily separated, and the stack tray of the process tray sheet bundle is used. Try to relieve the bending at the top. As a result, it is possible to prevent stacking defects such as the back end leaning of the processing tray sheet bundle. Next, 200 ms elapses after the stack tray is lowered (S805). When 200 ms elapses after the stack tray descends, the stack tray paper surface detection operation is started (S806), and the stack tray operation is ended (S807).

  The above sheet processing apparatus is a simultaneous bundle discharge type sheet processing apparatus, but the present invention can also be applied to a single bundle discharge type sheet processing apparatus 10 as shown in FIG.

  In this embodiment, the predetermined number of control switches is defined as seven, but the predetermined number is not limited to this. It goes without saying that the same effect can be obtained when the control is switched by the post-processing function and the operation setting of the image forming system in addition to the control switching by the predetermined number.

1 is a schematic front sectional view of a copying machine which is an image forming apparatus including a sheet processing apparatus according to an embodiment of the present invention in an apparatus main body. Control block diagram of the copying machine of FIG. Front schematic sectional view of a sheet processing apparatus according to an embodiment of the present invention. FIG. 2 is a schematic front sectional view showing each drive system of the sheet processing apparatus according to the embodiment of the present invention. The enlarged view of the principal part of the sheet processing apparatus of embodiment of this invention Control block diagram of the sheet processing apparatus of FIG. FIG. 3 is a flowchart for explaining the operation when discharging a sheet bundle in the sheet processing apparatus of FIG. The figure for demonstrating the operation timing of a rear-end assist and a rocking | fluctuating roller pair The figure for demonstrating the operation timing of a rear-end assist and a rocking | fluctuating roller pair The figure for demonstrating the operation timing of a rear-end assist, a rocking | fluctuating roller pair, and a 1st paper discharge roller pair. FIG. 7 is a diagram for explaining the operation of the sheet processing apparatus when sheets need not be accumulated during sheet processing, and (a) is a diagram illustrating a state in which the first sheet is fed into the sheet processing apparatus; ) Is the state of receiving the first sheet FIG. 14 is a diagram for explaining the operation of the sheet processing apparatus when it is not necessary to store sheets during the sheet processing, and is a diagram for explaining the operation following FIG. 13, and FIG. FIG. 5B is a diagram illustrating a state in which the sheet passes through the sheet discharge roller, and FIG. 5B is a diagram illustrating a state in which the first sheet is dropped across the stack tray and the processing tray. FIG. 15 is a diagram for explaining the operation of the sheet processing apparatus when it is not necessary to store sheets during sheet processing, and is a diagram for explaining the operation following FIG. 14. FIG. FIG. 5B is a diagram showing a state in which the first sheet is further fed into the processing tray. FIG. 16 is a diagram for explaining the operation of the sheet processing apparatus when it is not necessary to store sheets during the sheet processing, and is a diagram for explaining the operation following FIG. 15. FIG. The figure of the state which the sheet has been sent in, (b) is the figure of the state where the first sheet is in contact with the stopper FIG. 7 is a diagram for explaining the operation of the sheet processing apparatus when it is not necessary to store sheets during sheet processing, and shows a state in which three sheets are stacked on a processing tray. FIG. 18 is a diagram for explaining the operation of the sheet processing apparatus when it is not necessary to store sheets during sheet processing, and is a diagram for explaining the operation following FIG. 17. FIG. 5B is a diagram illustrating a state in which the sheet bundle is being discharged from the processing tray to the stack tray. FIG. 5 is a diagram for explaining the operation of the sheet processing apparatus when it is not necessary to store sheets during sheet processing, and illustrates a state in which a sheet bundle is discharged from the processing tray to the stack tray. 4A and 4B are diagrams for explaining the operation of the sheet processing apparatus when collecting sheets during sheet processing. FIG. 5A is a diagram illustrating a state in which the first sheet is fed into the sheet processing apparatus, and FIG. Illustration of the first sheet received up to the switchback point FIG. 21 is a diagram for explaining the operation of the sheet processing apparatus when collecting sheets during sheet processing, and is a diagram for explaining the operation following FIG. 20, and (a) receiving the first sheet at the trailing edge receiving portion. (B) is a diagram showing a state where the first sheet is pressed onto the lower conveyance guide plate by the rear end pressing. FIG. 22 is a diagram for explaining the operation of the sheet processing apparatus when collecting sheets during sheet processing, and is a diagram for explaining the operation following FIG. 21, and (a) shows the second sheet being fed into the sheet processing apparatus. Figure (b) shows a state where the second sheet is further fed. FIG. 23 is a diagram for explaining the operation of the sheet processing apparatus when collecting sheets during sheet processing, and is a diagram for explaining the operation following FIG. 22, and (a) accepts the second sheet up to the switchback point. (B) shows a state where the second sheet is received by the rear end receiving portion. FIG. 6 is a diagram for explaining the operation of the sheet processing apparatus when sheets are collected during sheet processing, and shows a state in which the first and second sheets are stacked and pressed onto the lower conveyance guide plate by a rear end press. FIG. 25 is a diagram for explaining the operation of the sheet processing apparatus when collecting sheets during sheet processing, and is a diagram for explaining the operation following FIG. 24, and (a) shows a state in which a third sheet has been fed. Figure, (b) shows the third sheet being fed. FIG. 26 is a diagram for explaining the operation of the sheet processing apparatus when collecting sheets during sheet processing, and is a diagram for explaining the operation following FIG. 25, and (a) starts to discharge a sheet bundle from the processing tray to the stack tray. FIG. 9B is a diagram showing a state where the sheet bundle is conveyed in the discharge direction from the buffer sheet. FIG. 27 is a diagram for explaining the operation of the sheet processing apparatus when collecting sheets during sheet processing, and is a diagram for explaining the operation following FIG. 26, and (a) shows a state in which the sheet bundle is discharged from the processing tray to the stack tray. FIG. 4B is a diagram showing a state in which the buffer sheet is being sent to the processing tray. FIG. 28 is a diagram for explaining the operation of the sheet processing apparatus when collecting sheets during sheet processing, and is a diagram for explaining the operation following FIG. 27, and (a) is a diagram showing a state in which a buffer sheet is being fed into the processing tray. (B) is a figure of the state which has sent the buffer sheet further to the processing tray Illustration for explaining the operation when the protruding length of the downstream end of the sheet bundle from the downstream end of the buffer sheet is short Sort processing flowchart Flowchart for explaining in-flight top sheet operation Flowchart for explaining buffer final sheet operation Flowchart following FIG. Flow chart for explaining buffer operation Flow chart for explaining the operation Flowchart for explaining post-processing operation Flowchart following FIG. It is operation explanatory drawing at the time of simultaneous bundle discharge of a stack tray, and operation explanatory drawing when a processing tray sheet bundle is six or less sheets It is operation explanatory drawing at the time of simultaneous bundle discharge of a stack tray, and operation explanatory drawing when a processing tray sheet bundle is seven sheets or more 4A and 4B are diagrams illustrating operation timings of the stack tray and the swing roller pair. FIG. 4A is a timing diagram when there are six or less processing tray sheet bundles, and FIG. Timing explanatory diagram at the above time Sectional view of an image forming system provided with a conventional single bundle discharge type sheet processing apparatus Flow chart for explaining stack tray operation

Explanation of symbols

D Document P Sheet L Difference between protrusion length of sheet bundle and buffer sheet S1 Entrance sensor SL1 Buffer roller separation solenoid SL2 First discharge roller separation solenoid SL3 Entrance roller separation solenoid SL4 Buffer paper pressing solenoid SP Switch back point CL Under-bundle clutch M1 Common transport motor M2 Inlet transport motor M3 Bundle discharge motor M4 Rear end assist motor M5 Front alignment motor M6 Back alignment motor M7 Upper tray motor M8 Stapler shift motor M9 Stapler motor M10 Swing motor M11 Lower tray motor 10 Sheet processing device 11 Processing Tray (first sheet stacking means)
15 Copying machine (image forming device)
16 Copying Machine (Image Forming Apparatus) Main Body 18 Swing Roller Pair (Sheet Conveying Unit)
19 Stapler unit 20 Control unit (sheet discharge control means)
22 Stack tray (second sheet stacking means)
23 Buffer unit (sheet holding means)
100 Copying machine (image forming device)
DESCRIPTION OF SYMBOLS 101 Main body 102 Document feeder 104 Feed part 114 Photosensitive drum (image forming means)
119 Sheet processing device 121 Inlet roller pair 123a Upper transport guide plate 123b Lower transport guide plate 124 Buffer roller 126 First paper discharge roller pair (holding sheet transport section)
126a Upper first paper discharge roller 126b Lower first paper discharge roller 127 Swing roller pair (sheet conveying means, second sheet conveying means)
127a Upper roller 127b Lower roller 128 Stack tray (second sheet stacking means)
129 processing tray (first sheet stacking means)
130 Return roller 131 Stopper 132 Stapler unit 133 Paper surface detection lever 134 Rear end assist (first sheet conveying means)
135 Rear end holding member 136 Rear end receiving portion 137 Receiving roller pair (rotating body pair)
140 Buffer unit (sheet holding means)
141 Friction member 201 CPU
210 Operation unit 211 Finisher control unit (sheet discharge control means)
212 FAX control unit 221 CPU

Claims (4)

Buffering means for buffering sheets discharged from the image forming apparatus;
Conveying means for conveying the buffered sheet from the buffering means;
First stacking means for stacking sheets conveyed from the buffering means;
A second loading means disposed behind the first loading means;
Consists of a bundle discharging means configured as a first loading means,
Simultaneous discharge control means for discharging the sheet conveyed from the buffering means to the first stacking means and simultaneously discharging the sheet bundle stacked on the first stacking means to the second stacking means by the conveying means and the bundle discharging means;
Buffering stacking control for stacking the buffering sheet conveyed from the buffering means on the first stacking means by the reverse operation of the bundle discharging means after discharging the sheet bundle stacked on the first stacking means to the second stacking means In a sheet processing apparatus having means,
The second stacking unit waits or moves to the first position at the start of simultaneous bundle discharge control,
The sheet processing apparatus, wherein at the end of the simultaneous bundle discharge control, the second stacking unit moves so as to be in the second position. A second position height switching means for switching the height of the second position of the second stacking means according to the number of sheet bundles stacked on the first stacking means;
2. The sheet processing apparatus according to claim 1, wherein when the number of sheet bundles is larger than a known predetermined number, the second position is set higher than when the number of sheet bundles is smaller than a known predetermined number. . Buffering means for buffering sheets discharged from the image forming apparatus;
Conveying means for conveying the buffered sheet from the buffering means;
A first stacking unit (processing tray) for stacking sheets conveyed from the buffering unit;
A second loading means disposed behind the first loading means;
Consists of a bundle discharging means (a pair of swinging rollers and a rear end assist) configured as a first stacking means,
Simultaneous discharge control means for discharging the sheet conveyed from the buffering means to the first stacking means and simultaneously discharging the sheet bundle stacked on the first stacking means to the second stacking means by the conveying means and the bundle discharging means;
Buffering stacking control for stacking the buffering sheet conveyed from the buffering means on the first stacking means by the reverse operation of the bundle discharging means after discharging the sheet bundle stacked on the first stacking means to the second stacking means In a sheet processing apparatus having means,
The second stacking unit waits or moves to the first position at the start of simultaneous bundle discharge control,
An image forming system, wherein at the end of simultaneous bundle discharge control, the second stacking means moves so as to be in the second position. A second position height switching means for switching the height of the second position of the second stacking means according to the number of sheet bundles stacked on the first stacking means;
4. The image forming system according to claim 3, wherein when the number of sheet bundles is larger than a known predetermined number, the second position is set higher than when the number of sheet bundles is smaller than a known predetermined number. .

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