Sheet processing apparatus

Abstract

To provide a sheet processing device capable of surely feeding an end part of a sheet to a processing tray even if the number of buffer sheets is increased when forming a bundle by superposing the sheets supplied from an image forming device while shifting them in the carrying direction and feeding them to the processing tray.SOLUTION: When the stacked sheets are discharged from the discharge portion, the push-down member is controlled to perform the push-down operation toward the sheet stacking portion at a first timing in a case where the number of sheets stacked in the sheet stacking portion is a first number of sheets, and to perform the push-down operation toward the sheet stacking portion at a second timing earlier than the first timing in a case where the number of sheets is a second number of sheets larger than the first number of sheets.SELECTED DRAWING: Figure 15

Description

[Technical Field]

[0001] The present invention relates to a sheet processing apparatus capable of performing processing on a sheet on which an image has been formed. [Background technology]

[0002] A sheet post-processing device is known as a device that is connected to the sheet discharge port of an image forming apparatus, temporarily holds image-formed sheets in the conveying path or on a tray, performs post-processing on the sheets, and then stores the sheets in a storage stacker. Known post-processing processes include punching holes in the sheets, accumulating and binding the sheets, and folding the sheets.

[0003] Patent Document 1 describes a sheet stacking device that can prevent misalignment when aligning multiple sheets stacked on a stacking tray. It also discloses the provision of a sheet guide member to quickly drop the sheets onto the tray.

[0004] Patent document 2 discloses a buffer operation that stacks and retains multiple sheets sent from an image forming device while post-processing is being performed, and also discloses a buffer that shifts the edges of the sheets when they are stacked, thereby improving the alignment of the sheets that appear on the processing tray. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-165560 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-60303 Summary of the Invention [Problem to be solved by the invention]

[0006] It is known that the sheet guide member disclosed in Patent Document 1 acts not only on sheets coming out one by one, but also on buffered and stacked sheets coming out onto the processing tray. This is intended to press down on the sheets from above, so that the sheet stack falls onto the processing tray more quickly than if it were to fall under its own weight.

[0007] When controlling the shifting of sheet edges as disclosed in Patent Document 2, if the number of sheets to be buffered and stacked increases, the accumulated length of the shifted sheet edges will result in a range that the sheet guide member cannot press down, and the sheet edges that cannot be pressed down may get caught in the processing tray, causing transport problems.

[0008] Furthermore, in recent years, as image forming apparatuses have become faster, post-processing devices are being required to buffer a larger number of sheets so that the operation of feeding sheets from the image forming apparatus does not stop while processing is being performed.

[0009] In view of the above-mentioned circumstances, the present invention aims to provide a sheet processing device that, when stacking sheets supplied from an image forming device while shifting them in the conveying direction to form a stack and sending them to a processing tray, reliably presses the edges of the sheets and drops them into the processing tray, even if the number of sheets in the buffer increases. [Means for solving the problem]

[0010] The sheet processing apparatus according to the present invention includes a sheet stacking section on which sheets to be processed are stacked; a sheet stacking section that stacks sheets to allow multiple sheets to be processed to wait while the sheets on the sheet stacking section are being processed, and that, when the sheets stacked on the sheet stacking section are discharged, shifts the sheets in the sheet transport direction so that the lower the sheet in the sheet stacking section, the closer one end of the sheet that abuts against a regulating section will be to the regulating section; a discharge section to which the sheets stacked on the sheet stacking section are discharged; and the regulating section that abuts against and regulates one end of the multiple sheets in the sheet transport direction discharged from the discharge section. The device is characterized by comprising a push-down member that pushes down the rear end in the sheet transport direction of the sheet sent onto the sheet stacking section toward the sheet stacking section, and a control section that controls the push-down member so that when the stacked sheets are discharged from the discharge section, if the number of sheets stacked in the sheet stacking section is a first number of sheets, the push-down member performs a push-down operation toward the sheet stacking section at a first timing, and if the number of sheets is a second number of sheets greater than the first number of sheets, the push-down member performs a push-down operation toward the sheet stacking section at a second timing earlier than the first timing. [Effects of the Invention]

[0011] According to the present invention, when sheets supplied from an image forming device are stacked while being shifted in the conveying direction to form a stack and sent to a processing tray by a discharge means, even if the number of sheets in the buffer increases, the edges of the sheets can be reliably held and dropped into the processing tray. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating an external appearance of an image forming system. [Figure 2] FIG. 2 is a diagram illustrating a configuration of a sheet post-processing device. [Figure 3] FIG. 10 is a diagram showing a configuration in the vicinity of a straight path. [Figure 4] FIG. 2 is a diagram showing the configuration of a punch unit. [Figure 5]FIG. 2 is a diagram showing the configuration of a punch unit. [Figure 6] FIG. 10 is a diagram illustrating a shift mechanism of the conveying roller. [Figure 7] FIG. 10 is a diagram illustrating a shift mechanism of the conveying roller. [Figure 8] FIG. 10 is a diagram illustrating a binding mechanism. [Figure 9] FIG. 10 is a diagram illustrating a binding mechanism. [Figure 10] FIG. 10 is a diagram illustrating a binding mechanism. [Figure 11] FIG. 10 is a diagram illustrating a tray lifting mechanism. [Figure 12] FIG. 10 is a diagram illustrating a sheet discharge mechanism. [Figure 13] FIG. 2 is a diagram showing a configuration of a staple unit. [Figure 14] FIG. 2 is a diagram showing the configuration of a control unit and its surroundings. [Figure 15] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 16] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 17] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 18] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 19] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 20] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 21] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 22] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 23] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 24] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 25] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 26] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 27]FIG. 2 is a diagram illustrating sheet conveyance. [Figure 28] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 29] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 30] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 31] FIG. 2 is a diagram illustrating sheet conveyance. [Figure 32] 10A and 10B are diagrams for explaining the operation of the push-down member. [Figure 33] FIG. 10 is a diagram illustrating the arrangement of the push-down members from above. [Figure 34] 10 is a flowchart illustrating a process for controlling a paddle. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0014] [Image forming device] An image forming apparatus A in the image forming system shown in Figure 1 will now be described. The image forming apparatus A shown in the figure is an electrostatic printing mechanism, and is composed of an image forming unit A1, a scanner unit A2, and a feeder unit A3. The apparatus housing 1 is provided with mounting legs 25 for installation on an installation surface (for example, the floor). Inside the apparatus housing 1, a paper feed unit 2, an image forming unit 3, a paper discharge unit 4, and a data processing unit 5 are built in.

[0015] The paper feed unit 2 is configured to include cassette mechanisms 2a to 2c that store sheets of multiple sizes on which images are to be formed, and feeds sheets of a size specified by the main body control unit 90 to the paper feed path 6. For this purpose, multiple cassettes 2a to 2c are detachably arranged in the device housing 1, and each cassette has a built-in separation mechanism that separates the sheets inside one by one, and a paper feed mechanism that feeds out the sheets. The paper feed path 6 is provided with transport rollers 7 that feed sheets supplied from the multiple cassettes 2a to 2c downstream, and a pair of registration rollers 8 that align the leading edges of each sheet at the end of the path.

[0016] In addition, a large-capacity cassette 2d and a manual feed tray 2e are connected to the paper feed path 6, and the large-capacity cassette 2d is configured to include an optional unit for storing sheets of a size that are consumed in large quantities, while the manual feed tray 2e is configured to be able to supply special sheets such as cardboard sheets, coated sheets, and film sheets that are difficult to separate and feed.

[0017] The image forming unit 3 is shown as an example of an electrostatic printing mechanism, and includes a photosensitive member 9 (drum, belt), a light emitter 10 that emits an optical beam onto the photosensitive member 9, a developer 11, and a cleaner (not shown) that are arranged around the rotating photosensitive member. The illustrated example shows a monochrome printing mechanism, in which a latent image is optically formed on the photosensitive drum 9 by the light emitter 10, and toner ink is applied to the latent image by the developer 11. A sheet is then fed from a paper feed path 6 to the image forming unit 3 in synchronization with the image formation on the photosensitive member 9, where the image is transferred onto the sheet by a transfer charger 12 and fixed by a fixing unit (roller) 13 arranged in a paper discharge path 14. A paper discharge roller 15 and a paper discharge outlet 16 are arranged in the paper discharge path 14, and the sheet is transported to a sheet post-processing device B, which will be described later.

[0018] The scanner unit A2 is configured to include a platen 17 on which an image original is placed, a carriage 18 that moves back and forth along the platen 17, a light source mounted on the carriage 18, and a reduction optical system 20 (a combination of mirrors and lenses) that guides light reflected from the original on the platen 17 to a photoelectric conversion unit 19. Reference numeral 21 in the figure denotes a second platen (traveling platen), which reads an image on a sheet fed from the feeder unit A3 using the carriage 18 and reduction optical system 20. The photoelectric conversion unit 19 transfers the photoelectrically converted image data to the image forming unit 3.

[0019] The feeder unit A3 includes a paper feed tray 22, a paper feed path 23 that guides sheets sent from the paper feed tray to a traveling platen 21, and a paper discharge tray 24 that stores documents whose images have been read by the platen.

[0020] The image forming apparatus A is not limited to the above mechanism, and can employ printing mechanisms such as an offset printing mechanism, an inkjet printing mechanism, and an ink ribbon transfer printing mechanism (thermal transfer ribbon printing, dye sublimation ribbon printing, etc.).

[0021] [Sheet post-processing device] The sheet post-processing device B is a device for post-processing sheets discharged from the paper discharge port 16 of the image forming device A and has, for example, (1) a function for stacking and storing image-formed sheets (printout mode), (2) a function for storing image-formed sheets in portions (jog sorting mode), (3) a function for collating and accumulating image-formed sheets and binding them (binding processing mode), and (4) a function for collating and binding the image-formed sheets, and then folding them to complete the binding process (binding processing mode).

[0022] In this embodiment, the sheet post-processing device B does not need to have all of the above functions, and is configured appropriately according to the device specifications (design specifications). As an example, in this embodiment, it is assumed that the sheet post-processing device B has a function of collating and binding sheets on which images are formed.

[0023] FIG. 2 shows the configuration of the sheet post-processing device B, and FIG. 3 shows the configuration around the straight path 28. The sheet post-processing device B post-processes sheets conveyed through a straight path entrance 26 connected to the paper discharge outlet 16 of the image forming device A, and then stores the sheets in a storage unit (a first stack tray 49, a second stack tray 61, and a third stack tray 71, which will be described later). The illustrated device can transfer sheets sent to the straight path 28 from a processing unit B1, which includes a binding unit 47, to the first stack tray 49 (hereinafter referred to as the "first tray") and the third stack tray 71 (hereinafter referred to as the "third tray"). Furthermore, the sheet sent to the straight path 28 can be transferred from a saddle unit B2 to the second stack tray 61 (hereinafter referred to as the "second tray"). Since the straight path 28 is formed in a substantially straight line, even thick paper can be transported.

[0024] Processing section B1 is disposed at the path exit (straight path paper discharge outlet 35) of straight path 28, and collates and stacks sequentially fed sheets, performs a binding process, and stores them in first tray 49. Saddle section B2 is disposed at the path exit (saddle path paper discharge outlet) of saddle path 32 branching off from straight path 28, and is a post-processing section that collates and stacks sequentially fed sheets, saddle-stitches them (although saddle-stitching may not be performed), folds them, and stores them in second tray 61. Each component will be described in detail below.

[0025] <Device housing> 2, sheet post-processing device B includes a device housing 27, a straight path 28 built into the device housing and having a straight path inlet 26 and a straight path paper discharge outlet 35, a processing section B1 and a saddle section B2 that post-process the sheets fed from the straight path 28, and a first tray 49, a second tray 61, and a third tray 71 that store the sheets fed from each post-processing section. The illustrated device housing 27 is disposed at approximately the same height as the housing 1 of image forming device A located upstream, and the paper discharge outlet 16 of image forming device A and the straight path inlet 26 of sheet post-processing device B are connected on the installation surface.

[0026] The housing 27 of the seat post-processing device includes a device frame 70. The device frame 70 forms the framework of a box-shaped device, as shown in FIG. 6, and includes a front side frame 70f located at the front in the state shown in FIG. 1, a rear side frame 70r located at the rear, and stay members (connecting reinforcement members) connecting the two side frames. The straight path 28, processing section B1, saddle section B2, etc., which will be described later, are attached between the left and right side frames. The device housing 27 is not limited to the shape shown in the figure and can have any suitable shape in terms of design, and the device frame 70 is not limited to a structure consisting of left and right side frames and connecting stays, but various frame structures, such as a monocoque structure, can be used.

[0027] <Sheet delivery route> 3, the straight path 28 is configured as a substantially linear path that crosses the device housing 27 in a substantially horizontal direction, and includes a straight path entrance 26 that is connected to the paper discharge outlet (main body paper discharge outlet) 16 of the image forming device A, and a straight path paper discharge outlet 35 that is located on the opposite side of the device from the entrance (straight path entrance 26). The straight path 28 is provided with an entrance roller 29, a first conveyance roller 201, a second conveyance roller 202, and a third conveyance roller 203, arranged in this order from the straight path entrance 26 side, as a conveyance mechanism that can convey a sheet from the straight path entrance 26 to the straight path paper discharge outlet 35 and from the straight path paper discharge outlet 35 to the straight path entrance 26. In addition, the straight path paper discharge outlet 35 is provided with a paper discharge roller 36 (including a sheet conveyance mechanism such as a belt) as a conveyance mechanism. Also, an entrance sensor S1 that detects the leading and trailing edges of the received sheet and a lateral registration detection sensor S0 (detection unit) that detects the edge position (side edge) parallel to the sheet conveyance direction are arranged near the straight path entrance 26. Also, a sheet discharge sensor S2 that detects the leading and trailing edges of the sheet is arranged near the straight path paper discharge outlet 35. The sheet discharged from the straight path paper discharge outlet 35 is discharged to the first tray 49 via the first paper discharge path 31 connected to the straight path paper discharge outlet 35, or is guided to the processing unit B1. Also, a punch unit 100 that punches holes in the sheet is arranged in the straight path 28.

[0028] <Sheet delivery route layout> As shown in FIGS. 2 and 3 , the straight path 28 is arranged in the following order from the straight path entrance 26 toward the straight path discharge outlet 35: a saddle path 32, a saddle buffer path P2, a processing buffer path P1, and an upper conveying path 30. At the branching points of each of the above paths, a saddle path flapper 33b, a saddle buffer path flapper 33a, a processing buffer path flapper 200, and an upper conveying path flapper 34 are arranged as conveyance switching mechanisms (branching mechanisms) for conveyed sheets. In this embodiment, the saddle buffer path P2 and the upper conveying path 30 are configured as evacuation paths for evacuating sheets. Also, as shown in FIG. 2 , a saddle section B2 is provided on one side of the straight path 28, and the saddle buffer path P2 and the upper conveying path 30 are provided on the opposite side (the other side). This further improves the efficiency of conveying sheets positioned on the evacuation paths to the saddle section B2.

[0029] Among the above paths, the saddle path 32, the saddle buffer path P2, and the processing section buffer path P1 are configured as switchback paths that transport the sheet in the opposite direction to the transport direction from the straight path entrance 26 to the straight path paper discharge outlet 35, and carry the sheet into each of the above paths. In addition, the upper transport path 30 is configured to transport the sheet in the same direction as the transport direction from the straight path entrance 26 to the straight path paper discharge outlet 35.

[0030] <Path branching mechanism> The sheet branching mechanisms, saddle path flapper 33b, saddle buffer path flapper 33a, and processing section buffer path flapper 200, are configured with flapper guides that move to switch the transport path of a sheet carried in from the straight path entrance 26, and are connected to a drive mechanism (not shown) such as an electromagnetic solenoid or a minimotor. The saddle path flapper 33b guides a sheet sent from the straight path entrance 26 to the saddle path 32. The saddle buffer flapper 33a guides a sheet sent from the straight path entrance 26 to the saddle buffer path P2. The processing section buffer flapper 200 guides a sheet sent from the straight path entrance 26 to the processing section buffer path P1 via processing section buffer rollers 301a and 301b. The upper conveying path flapper 34 includes a movable flapper guide that switches the conveying path so that the sheet fed from the straight path entrance 26 is conveyed to either the straight path paper discharge outlet 35 or the upper conveying path 30, and is connected to a drive mechanism (not shown) such as an electromagnetic solenoid or a mini motor.

[0031] <Upper transport path> An upper conveying path 30 (printout paper discharge path) that carries in sheets other than those to be discharged to the straight path paper discharge outlet 35 is connected to the straight path 28, and an upper conveying path flapper 34 for guiding sheets to the upper conveying path 30 is provided at the path branching portion. In addition, the upper conveying path 30 is provided with upper conveying rollers 303 (303a, 303b) that guide the sheets to the third tray 71. As a result, the sheets guided to the upper conveying path 30 are discharged from the upper conveying path paper discharge outlet 40 to the third tray 71 (overflow tray). In this embodiment, the upper conveying path 30 is also used as a sheet evacuation path.

[0032] <Saddle Pass> A saddle path 32 for conveying sheets into the saddle section B2 is connected to the straight path 28, and the path branch section is provided with a saddle path flapper 33b for guiding sheets to the saddle path 32. Sheets guided from the saddle path 32 to the saddle section B2 via the saddle path paper discharge port are saddle-stitched and folded, and then discharged to the second tray 61 via the approximately horizontal saddle discharge path 68.

[0033] <Saddle buffer pass> A saddle buffer path P2 is connected to the straight path 28, and is used to temporarily transport and wait sheets to be saddle-stitched and folded in the saddle section B2. A saddle buffer path flapper 33a is provided to guide the sheets to the saddle buffer path P2. The saddle buffer path P2 is also provided with conveying rollers 302 (302a, 302b) that transport the sheets and temporarily wait them there.

[0034] A fourth tray discharge port 305 is provided on the downstream extension of the saddle buffer path P2, so that sheets carried into the saddle buffer path P2 can be discharged and stacked onto the fourth tray 310. In this case, the fourth tray 310 is disposed vertically above the saddle buffer path P2. The fourth tray 310 may be shared with an exterior component on the top surface of the sheet post-processing device B, may be fixed to the device housing, or may be provided with a drive mechanism and configured to be able to move up and down in a substantially vertical direction.

[0035] The device can be made more compact by arranging the saddle buffer path P2 in an overlapping position vertically above the punch unit 100. However, if space is required to flip the punch unit 100 upward to remove sheets retained in the punch unit 100, the saddle buffer path P2 may be arranged in a non-overlapping position vertically above the punch unit 100.

[0036] <Transport roller shift mechanism in the loading route> The conveyance shift mechanism provided on the conveyance rollers on the conveyance path will now be described with reference to Figures 6 and 7. The first conveyance roller 201, second conveyance roller 202, third conveyance roller 203, and conveyance rollers 302a and 302b each include a drive roller 111 and a driven roller 112 rotatably supported by bearings on the left and right side frames 70f and 70r. A drive rotation shaft is connected to the drive roller shaft 113 via a transmission mechanism 116 (gear transmission in the illustration), and a drive motor (not shown) shared with the sheet discharge roller 36 is connected to the drive rotation shaft 115. The driven roller shaft 114 is supported by bearings on the left and right side frames 70f and 70r so as to be able to move freely.

[0037] Each of the above-mentioned conveying rollers is rotatably attached to a shift member 117 that connects the drive roller shaft 113 and the driven roller shaft 114. The shift member 117 connects the drive roller shaft 113 and the driven roller shaft 114 so that they move together in the axial direction (thrust direction) and can rotate independently in the radial direction. The drive roller shaft 113 is supported by bearings on the left and right side frames 70f, 70r, with one end of the drive roller shaft 113 located in a range indicated by the axial movement region of the conveying roller on the front side of the side frame 70f and the other end located on the rear side of the side frame 70r. The shift member 117 (e.g., a block member made of synthetic resin) is supported by the drive roller shaft 113 and the driven roller shaft 114 and connects both roller shafts together.

[0038] A rack 117a is formed integrally with the shift member 117, and is engaged with a shift motor M9 and a transmission pinion 117b attached to the side frame 70r (device frame; the same applies below). With this configuration, the shift member 117 can be moved (shifted) in the axial direction of the conveying roller by rotating the shift motor M9 (the illustrated one is a stepping motor that can rotate forward and backward).

[0039] A driven gear 118 is formed integrally with the drive rotation shaft 115, and the rotation of the drive motor is transmitted to the driven gear 118. In addition, a pair of conveying rollers (a drive roller and a driven roller) is pressed against the driven rotation shaft 119 so that the driven rotation shaft 119 is rotated by the rotation of the drive rotation shaft 115.

[0040] In this embodiment, the drive rotation shaft 115 and the driven rotation shaft 119 are connected to each other so that the axial movement of one of them causes the other to follow. Alternatively, one of the drive roller 111 and the driven roller 112 may be attached to the rotation shaft so that it can slide (slidably) in the axial direction, and the other roller may be moved in position in the axial direction and linked to that movement.

[0041] <Transport shift operation> Here, the shift operation (jog sorting mode) of a sheet carried into the sheet post-processing device B will be described. A sheet fed from the image forming device A is conveyed in the order of straight path entrance 26, entrance rollers 29, first conveying rollers 201, second conveying rollers 202, and third conveying rollers 203. At this time, the timing of sheet delivery is also detected by entrance sensor S1. As the sheet carried in by entrance rollers 29 passes through the straight path 28, the edge position of the sheet is detected by lateral registration detection sensor S0. The lateral registration detection sensor S0 detects the extent to which a lateral registration error X occurs in the sheet relative to the center (middle) position.

[0042] When the lateral registration error X is detected by the lateral registration detection sensor S0, the first conveyance roller 201, the second conveyance roller 202, and the third conveyance roller 203 sequentially move a predetermined amount toward the front and rear while conveying the sheet, thereby performing a sheet shift operation (also referred to as "lateral registration detection process"). Thereafter, the sheet is conveyed by being sorted by the upper conveyance path flapper 34 of the branching mechanism to either the straight path paper discharge outlet 35 or the upper conveyance path 30, and is discharged onto the first tray 49 or the second tray 71.

[0043] <Processing section> Processing section B1 is a post-processing section that is disposed downstream of straight path 28 and includes a processing tray 37 that collates and stacks sheets sent from straight path paper discharge outlet 35, and a binding processing mechanism that binds the stacked sheet bundle. As shown in Fig. 3, a step is formed at straight path paper discharge outlet 35 of straight path 28, and processing tray 37 is disposed below the step, and a first paper discharge path (first switchback path) 31 is formed between straight path paper discharge outlet 35 and processing tray 37 that reverses the conveying direction from the paper discharge outlet and guides sheets onto the tray.

[0044] A sheet carry-in mechanism that carries sheets from the straight path paper discharge outlet 35 onto the tray is disposed between the straight path paper discharge outlet 35 and the processing tray 37, and the processing tray 37 is provided with a positioning mechanism that positions the sheets at a predetermined binding position and a sheet bundle carry-out mechanism that discharges the bound sheet bundle onto the downstream first tray 49. Each component will be described later.

[0045] 3 bridges the sheet fed from the straight path paper discharge outlet 35 between itself and the downstream first tray 49. That is, the sheet fed from the straight path paper discharge outlet 35 is supported in a bridge manner with its leading edge on the uppermost sheet of the downstream first tray 49 and its trailing edge on the processing tray 37.

[0046] <Saddle section> The saddle section B2 is a post-processing section that collates and stacks the sheets sent from the straight path 28, binds the center portion, and performs an inward folding process (hereinafter referred to as "magazine finishing"). A second tray 61 is disposed downstream of the saddle section B2 and stores the bound sheet stack. Note that the configuration may also be such that one or more sheets are collated and stacked, and only the center portion is inward folded without saddle stitching.

[0047] The saddle section B2 is configured to include a guide member 66 that accumulates sheets in a stack, a leading edge regulating stopper 67 that positions the sheets at a predetermined position on the guide member 66, a staple device 63 (saddle stitching staple unit) that binds the center of the sheets positioned by the leading edge regulating stopper 67, and a folding processing mechanism (a pair of folding rolls 64 and a folding blade 65) that folds the sheet stack at the center after the binding process.

[0048] The saddle stitch staple unit 63 employs a commonly known mechanism that sandwiches the sheet stack between a head unit and an anvil unit, and moves the unit along the center line of the sheets to perform the binding process. As shown in Figure 2, the folding process mechanism is configured so that a folding blade 65 inserts the fold of the sheet stack into a pair of folding rolls 64 that are pressed against each other, and the rolls roll to fold the sheet stack.

[0049] The illustrated processing section B1 and straight path 28 are arranged in a substantially horizontal direction, the saddle path 32 that guides the sheets to the saddle section B2 is arranged in a vertical direction, and the guide member 66 that aligns and stacks the sheets is arranged in a substantially vertical direction. In this way, by arranging the straight path 28 in a direction that crosses the device housing 27 and arranging the saddle path 32 and saddle section B2 in a vertical direction, it is possible to slim down the device.

[0050] A second tray 61 is disposed downstream of the saddle portion B2 and is capable of storing a stack of sheets folded like a magazine. The second tray 61 is disposed below the first tray 49. This is because it is assumed that the first tray 49 will be used more frequently than the second tray 61, and the position of the first tray 49 is set at a height that makes it easy to remove sheets from the tray.

[0051] <Punch unit> 5, a punch unit 100 that is disposed on the straight path 28 and punches holes in a sheet fed from the straight path inlet 26 will be described. The punch unit 100 has a plurality of punch members 101a to 101e arranged at predetermined intervals in a direction perpendicular to the sheet conveying direction of the straight path 28, and punches a selected number of holes in the sheet.

[0052] 4 shows the overall configuration of the punch unit 100. The punch unit 100 includes a unit frame 102, a plurality of punch members 101a to 101e arranged on the unit frame 102 so as to be vertically movable, a drive cam that moves each punch member up and down (reciprocating in the punching direction), and a drive motor M7 that drives the drive cam.

[0053] Reference numeral 104 in the figure denotes a dust box, which is disposed below the punch member 101 and stores punched waste paper. The dust box 104 is attached to a guide rail (not shown) so as to be slidable on the device frame 70 (different from the unit frame). Reference numeral 106 in the figure denotes a rotation operation member, which forcibly rotates the drive cam to separate (peel off) the punch member 101 that has bitten into the sheet when a jam occurs in the punch member 101 or when an abnormality occurs in the drive motor M7. For this reason, the rotation operation member 106 is composed of a manual rotation knob connected to a rotation shaft 107 of the drive cam.

[0054] As shown in FIG. 5, the unit frame 102 includes an upper frame 102a having a predetermined length in a direction perpendicular to the sheet conveying direction of the straight path 28, and a lower frame 102b. A plurality of punch members 101a-101e are arranged on the upper frame 102a at predetermined intervals in a direction perpendicular to the sheet conveying direction (hereinafter referred to as the "conveyance perpendicular direction") so as to be reciprocable (vertically movable) in the punching direction. The lower frame 102b has punch holes (dies) formed in positions facing each punch unit 101. A drive shaft 107 is also arranged on the unit frame 102, and a drive cam is attached to the drive shaft 107 to move each punch member 101 up and down. A drive motor M7 is connected to the drive shaft 107 via a transmission mechanism.

[0055] The drive cam is composed of a cylindrical cam member that is axially attached to the drive rotation shaft 107 and corresponds to the multiple punch members 101, and each punch member is connected to this cam member by a connecting pin. The punch members 101 move up and down in the punching direction when the drive rotation shaft 107 rotates through a predetermined angle. At this time, a first group 101b and 101d of the multiple punch members (e.g., punching two holes) moves up and down in the punching direction at a first rotation angle of the drive rotation shaft 107, and a second group 101a, 101c and 101e (e.g., punching three holes) moves up and down in the punching direction at a different second rotation angle.

[0056] Therefore, the binding process control unit 95 described later controls the motor M7 to rotate the drive shaft 107 back and forth within a predetermined angle range, causing the punch members 101b and 101d of the first group to perform a punching motion, and to rotate the drive shaft 107 back and forth within a different angle range, causing the punch members 101a, 101c, and 101e of the second group to perform a punching motion.

[0057] The dust box 104 is disposed below the punch member 101, is supported by a guide rail (not shown) provided on the device frame, and is detachable from the front side of the device.

[0058] A drive motor M7 is connected to the drive rotation shaft 107 via a speed reduction mechanism (gear transmission mechanism), and the rotating member is placed on the front side of the side frame 70f through a hole provided in the side frame 70f so that the operator can rotate it manually. A front cover is placed on the front side of the device so that it can be opened and closed, and the rotation operation member 106 can be operated when the cover is open. Note that when the cover is open, no drive power is supplied (cut off) to the drive motor M7.

[0059] [Configuration of processing unit] Next, the configurations of the sheet carry-in mechanism, sheet positioning mechanism, binding mechanism, and sheet bundle carry-out mechanism of processing section B1 will be described.

[0060] <Sheet loading mechanism> As shown in Figure 3, between the straight path paper discharge outlet 35 and the processing tray 37, there are arranged a reversing conveying mechanism that switches back and conveys the sheet from the straight path paper discharge outlet 35 in the paper discharge direction and the opposite direction to the paper discharge direction, a guide mechanism (sheet guide member) 44 that guides the sheet toward the tray, and a pick-up rotor 46 that guides the sheet to the trailing end regulating section.

[0061] The reverse conveying mechanism is composed of a lifting roller 41 that moves up and down between an operating position where it engages with the sheet being transported onto the processing tray 37 and a separated standby position, and a paddle rotor 42 (moving member) that transports the sheet in the opposite direction to paper discharge, and the lifting roller 41 and paddle rotor 42 are attached to a swinging bracket 43.

[0062] A swing bracket 43 is arranged on the device frame 27 so as to be swingable around a rotation axis (for example, the axis of the paper discharge roller), and the rotation axes of the lift roller 41 and the paddle rotor 42 are bearing-supported on the swing bracket 43. An elevation motor (not shown) is connected to the swing bracket 43, and the swing bracket 43 moves the mounted lift roller 41 and paddle rotor 42 up and down between an operating position where they engage with the sheet and a standby position spaced apart from the sheet.

[0063] A drive motor (not shown) is connected to the lift roller 41 and the paddle rotor 42, and drive is transmitted to rotate the lift roller 41 in forward and reverse directions and the paddle rotor 42 in the reverse direction (opposite the direction of paper discharge). The processing tray 37 is also provided with a driven roller 48 that is in pressure contact with the lift roller 41, and nips a single sheet or a stack of sheets to discharge them downstream.

[0064] A guide mechanism is disposed between the lift roller 41 and a take-in rotor 46 (described later) that guides the trailing edge of a sheet carried onto the processing tray 37 toward the sheet edge regulating unit 38. The guide mechanism includes a sheet guide member 44 that moves up and down from the dotted line state to the solid line state in FIG. 3, and the sheet guide member 44 retracts to the dotted line position when the sheet is discharged from the straight path paper discharge outlet 35, and guides the trailing edge of the sheet onto the processing tray 37 after the trailing edge of the sheet has passed through the straight path paper discharge outlet 35. For this reason, a drive mechanism (not shown) is connected to the sheet guide member 44, which moves up and down depending on the timing of guiding the trailing edge of the sheet from the straight path paper discharge outlet 35 onto the processing tray 37.

[0065] <Seat positioning mechanism> The processing tray 37 is provided with positioning mechanisms 38 and 39 for positioning sheets at a predetermined binding position, and the illustrated one includes a sheet end regulating section 38 that abuts and regulates the rear end of the sheet, and a side edge alignment section 39 that positions the side edge of the sheet at a reference position (center reference, one side reference).

[0066] The sheet end regulating section 38 is composed of a stopper member that abuts against and regulates the rear end of the sheet, as shown in Fig. 3. Also, the side edge aligning member 39, which will be described later in Fig. 9, ejects sheets from the straight path 28 based on the center, and depending on the type of binding mode, positions the sheets based on the same center or on one side.

[0067] <Side edge alignment mechanism> 9, the side edge alignment plates 39F, 39R protrude upward from the paper loading surface 37a of the processing tray 37, have regulating surfaces 39x that engage with the side edges of the sheets, and are arranged in a pair facing each other on the left and right. The pair of side edge alignment sections 39 are arranged on the processing tray 37 so as to be able to move back and forth with a predetermined stroke. This stroke is set based on the size difference between the maximum size sheet and the minimum size sheet and the offset amount by which the sheet stack is moved to the left or right after alignment (offset transport).

[0068] In other words, the movement stroke of the left and right side edge alignment plates 39F, 39R is set by the movement amount for aligning sheets of different sizes and the offset amount of the sheet stack after alignment. When corner binding is performed, the side edge alignment plates 39F, 39R move the sheets fed out based on the center reference by a predetermined amount (offset movement) to the right for right-corner binding and to the left for left-corner binding. This offset movement can be performed one by one each time a sheet is fed into the processing tray 37 (for each fed-in sheet), or by moving the entire stack to perform binding after aligning the sheets into a stack.

[0069] 9, the side edge alignment section 39 is configured to include a right edge alignment member 39F (on the front side of the apparatus) and a left edge alignment member 39R (on the rear side of the apparatus), and both side edge alignment members have regulating surfaces 39x that engage with the side edges of sheets, which are supported on the processing tray 37 so as to move toward or away from each other. The processing tray 37 is provided with a slit groove (not shown) that penetrates from the front to the back, and the side edge alignment section 39, which has regulating surfaces 39x that engage with the side edges of sheets, is slidably fitted into this slit groove.

[0070] Each side edge alignment plate 39F, 39R is slidably supported on a plurality of guide rollers 80 (which may be rail members) on the rear side of the tray, and a rack 81 is integrally formed therewith. The left and right racks 81 are connected to alignment motors M1, M2 via pinions 82. The left and right alignment motors M1, M2 are composed of stepping motors, and are configured to detect the positions of the left and right side edge alignment plates 39F, 39R using position sensors (not shown), and to move each alignment member in either the left or right direction by a specified amount based on the detected value. Note that the illustrated rack-pinion mechanism is not limited to this, and each side edge alignment plate 39F, 39R may be fixed to a timing belt and connected via a pulley to a motor that reciprocates the timing belt left and right.

[0071] With the above configuration, the binding process control unit 95 (described later) places the left and right side edge alignment members 39F and 39R at predetermined standby positions (the sheet width size + α position) based on sheet size information provided by the image forming apparatus A. In the "multi-binding" mode, sheets are fed onto the processing tray 37, and the alignment operation begins when the sheet edges strike the sheet edge restriction units 38. This alignment operation is performed by rotating the left and right alignment motors M1 and M2 by the same amount in opposite directions (approaching directions). The sheets fed into the processing tray 37 are then positioned based on the sheet center and stacked into a bundle. By repeating this sheet feed operation and alignment operation, the sheets are collated and stacked into a bundle on the processing tray 37. At this time, sheets of different sizes are positioned based on the center. In the "corner binding" mode, sheets are fed onto the processing tray 37, and the alignment operation begins when the sheet edges strike the sheet edge restriction units 38. This alignment operation is performed by making the movement amount of the alignment plate on the binding position side different from that on the opposite side of the binding position, and the movement amount is set so that the sheet corner is positioned at a predetermined binding position.

[0072] <Binding processing mechanism> A binding mechanism 47 that binds the sheet stack accumulated on the paper stacking surface 37a is disposed on the processing tray 37. The paper stacking surface 37a on the processing tray 37 is positioned at a predetermined binding position by a positioning mechanism (a sheet end regulating portion 38 and a side edge aligning portion 39). The binding mechanism 47 is configured as a binding unit 47 (hereinafter referred to as a "staple unit") that staples the sheet stack.

[0073] A binding processing mechanism 47 is arranged in the processing tray 37 to bind the rear end of the sheet conveyed from the straight path paper discharge outlet 35, and the binding processing mechanism 47 is configured as a staple unit that can be moved along the rear end of the paper loading surface 37a of the processing tray 37 as shown in Figure 8.

[0074] 8 and 9 show the staple unit 47 arranged on the processing tray 37. In Fig. 9, the binding position Cp1 is set at the sheet corner located on the left side of the drawing. The staple unit 47 moves at a predetermined stroke SL1 along a first traveling rail 53 and a second traveling rail 54 formed on the device frame 27b.

[0075] 9 shows sheets fed into the processing tray 37 and the movement stroke SL1 of the binding unit 47. Sheets of different sizes, from the largest size sheet to the smallest size sheet, are fed into the processing tray 37 with the center as the reference. A pair of left and right side edge alignment plates 39F, 39R aligns these sheets so that sheets of different sizes coincide with each other, based on the binding edge of the sheet (the left edge in the illustrated example). Therefore, the left and right side edge alignment plates 39F, 39R are connected to different drive motors M1, M2, respectively, and a binding process control unit 95, which will be described later, sets the movement amount of the left and right side edge alignment plates 39F, 39R according to the sheet size.

[0076] In addition, the binding process control unit 95, which will be described later, aligns the sheets based on the center reference in the binding process other than the binding process at the sheet corners, for example, in the multi-binding mode, which will be described later. In this case, the left and right side edge alignment plates 39F, 39R position the sheets at the binding position by moving the same amount from the standby position toward the sheet center.

[0077] 9, the binding unit 47 moves a stroke SL1 between a standby position Wp1 (first standby position) and the binding position Cp1. That is, the binding unit 47 moves back and forth between the standby position Wp1 and the binding position Cp1 along traveling rails 53 and 54 (guide grooves, guide rods, etc.). The first standby position Wp1 is set outside the maximum size sheets to be bound on the processing tray 37.

[0078] Fig. 10 shows the configuration of the binding unit 47. A pair of left and right pulleys 58a, 58b are arranged on the device frame 27b along the movement area (left and right direction in Fig. 9) of the staple unit 47, a timing belt 59 (toothed belt) is stretched between the two pulleys, and a drive motor M3 (stepping motor) is connected to one of the pulleys, 58a.

[0079] <Staple moving mechanism> As shown in Fig. 8, the staple unit 47 is mounted so as to be movable at a predetermined stroke on a device frame (chassis frame) 27b which is fixed to the side frames 70f, 70r by passing through an opening provided in the side frame 70f of the device frame 70. A first traveling rail 53 and a second traveling rail 54 are arranged on the device frame 27b. A traveling rail surface 53x is formed on the first traveling rail 53, and a traveling cam surface 54x is formed on the second traveling rail 54. The traveling rail surface 53x and the traveling cam surface 54x cooperate with each other to support the staple unit 47 (hereinafter referred to as "moving unit" in this section) so as to be movable back and forth at a predetermined stroke, and at the same time, control its angular posture.

[0080] The first traveling rail 53 and the second traveling rail 54 are formed with rail surfaces 53x and traveling cam surfaces 54x so as to reciprocate within the movement range of the moving unit. As shown in Fig. 10, a timing belt 59 connected to a drive motor (travel motor) M3 is fixed to the staple unit 47. The timing belt 59 is wound around a pair of pulleys 58a, 58b journaled on the device frame 27b, and the drive motor M3 is connected to one of the pulleys. Therefore, when the drive motor M3 rotates forward or backward, the staple unit 47 reciprocates with a stroke SL1.

[0081] The staple unit 47 engages with the first and second traveling rails 53, 54 as follows. As shown in Fig. 8, the staple unit 47 is provided with first rolling rollers 83 (rail fitting members) that engage with the traveling rail surfaces 53x and second rolling rollers 84 (cam follower members) that engage with the traveling cam surfaces 54x. The staple unit 47 is also formed with ball-shaped sliding rollers 47x (two rollers shown) that engage with the support surfaces of the frame 27b. The staple unit 47 is also formed with guide rollers 47y that engage with the bottom surface of the bottom frame, thereby preventing the staple unit 47 from floating up from the device frame 27b.

[0082] With the above-described configuration, the staple unit 47 is movably supported by the device frame 27b with the sliding rollers 47x and the guide rollers 47y. The first rolling rollers 83 and the second rolling rollers 84 rotate along the traveling rail surface 53x and the traveling cam surface 54x, respectively, while following the rail surface 53x and the traveling cam surface 54x.

[0083] <Stack tray lifting mechanism> As shown in Fig. 11, the sheet post-processing device B is equipped with a first tray 49. The first tray 49 is configured to be raised and lowered according to the amount of sheets stacked thereon. For this purpose, guide rollers 85 are provided at two locations, one above the other, at the base end of the first tray 49, and the guide rollers 85 are fitted and supported by lift guides 86 provided on the device frame 27. A lift gear 88 is provided at the base end of the first tray 49 and is connected to a lift rack gear 87. A lift motor M4 is also connected to the lift gear 88. Therefore, by controlling the rotation of the lift motor M4, the first tray 49 is raised and lowered according to the amount of sheets stacked thereon.

[0084] <Sheet bundle discharge mechanism> A sheet bundle discharge mechanism is disposed on the processing tray 37, which discharges the bound sheet bundle toward the downstream first tray 49. Known configurations for transporting the sheet bundle downstream include a method in which a pair of rollers press against each other (discharge roller mechanism), and a conveyor mechanism in which a pusher member moves from upstream to downstream along the tray surface to push out the trailing ends of the sheets. The illustrated device employs both of these mechanisms.

[0085] 12 shows the sheet bundle discharge mechanism. The conveyor mechanism includes a push-out protrusion 45 that transfers the sheets from a binding position (processing position) located upstream along the processing tray 37 to a stack tray (first tray) 49 located downstream, a conveyor belt 45v that moves the push-out protrusion, and a drive motor M6. A driven roller 48 is disposed at the discharge outlet (the boundary between the paper loading surface 37a and the first tray 49) of the processing tray 37, and a lift roller 41 that presses against the driven roller 48 is disposed opposite the driven roller 48, and the driven roller 48 and the lift roller 41 form a discharge roller mechanism.

[0086] Therefore, the processing tray 37 is provided with conveyor mechanisms 45, 45v that transport the sheet bundle by pushing it from the upstream side to the downstream side, and discharge roller mechanisms 48, 41 that nip and discharge the sheet bundle. FIG. 12(a) shows a state in which the sheet bundle is positioned at the binding position on the processing tray 37. At this time, the conveyor mechanisms 45, 45v and the discharge roller mechanisms 48, 41 are in operation. FIG. 12(b) shows a state in which the sheet bundle is being transported from the processing position to the downstream side, where the sheet bundle is sent downstream by the movement of the push-out protrusion 45 and the rotation of the discharge roller mechanisms 48, 41. FIG. 12(c) shows a state immediately before the sheet bundle is discharged to the first tray 49 on the downstream side, where the sheet bundle is gradually (slowly) sent downstream on the processing tray by the rotation of the discharge roller mechanisms 48, 41. At this time, the push-out protrusion 45 waits in the illustrated position and returns (rearwards) to its initial position.

[0087] <Configuration of the staple unit> The configuration of the above-mentioned staple unit will be described with reference to Fig. 13. The staple unit 47 is configured as a unit separate from the sheet post-processing device B. A box-shaped unit frame 47a, a drive cam 47d pivotally supported on the unit frame 47a, and a drive motor M4 that rotates the drive cam 47d are mounted on the unit frame 47a.

[0088] The staple head 47b and the anvil member 47c are arranged on the drive cam 47d to face each other at the stapling position, and the staple head 47b is biased by a biasing spring (not shown) on the drive cam 47d from an upper standby position to a lower staple position (anvil member) to move up and down. A staple cartridge 52 is detachably mounted on the unit frame 47a.

[0089] The staple cartridge 52 stores straight blank staples, and a staple feed mechanism supplies the staples to the staple head 47b. The staple head 47b contains a former that bends the straight staples into a U-shape and a driver that presses the bent staples into a sheet stack. With this configuration, the drive motor M4 rotates the drive cam 47d, storing energy in the spring. When the rotation angle reaches a predetermined angle, the staple head 47b swiftly descends toward the anvil member 47c. This action bends the staple into a U-shape, and the driver then inserts the staples into the sheet stack. The tip of the staple is then bent by the anvil member 47c, resulting in staple binding.

[0090] A staple feed mechanism is built in between the staple cartridge 52 and the staple head 47b, and a sensor (empty sensor) is disposed in the staple feed mechanism to detect when there are no staples. Also, a cartridge sensor (not shown) is disposed in the unit frame 47a to detect whether the staple cartridge 52 is inserted or not.

[0091] The staple cartridge 52 employs a structure in which staples connected in a band-like shape are stored in a box-shaped cartridge in layers, or in a roll-like structure. Furthermore, the unit frame 47a is provided with circuits for controlling the above-mentioned sensors and a circuit board for controlling the drive motor M4, and is configured to issue a warning signal when the staple cartridge 52 is not stored or when the staples are empty. Furthermore, the staple control circuit controls the drive motor M4 to execute the stapling operation in response to a staple signal, and is configured to issue an "operation end signal" when the staple head portion 47b moves from the standby position to the stapling position and then returns to the standby position.

[0092] <Control configuration explanation> The control configuration of the image forming system in Fig. 1 will be described with reference to Fig. 14. The image forming system shown in Fig. 14 includes a control unit 90 of image forming apparatus A (hereinafter referred to as "main body control unit") and a control unit 95 of sheet post-processing apparatus B (hereinafter referred to as "binding process control unit"). The main body control unit 90 controls a print control unit 91, a paper feed control unit 92, and an input unit 93 (control panel).

[0093] Then, the "image formation mode" and "post-processing mode" are set based on user operations received via the input unit 93 (control panel). In the image formation mode, for example, mode settings such as color / monochrome printing, double-sided / single-sided printing, and image formation conditions such as sheet size, sheet paper quality, number of printouts, enlarged / reduced printing, etc. are set. In the "post-processing mode," for example, "printout mode," "bookbinding processing paper output mode," "staple binding processing mode," and "jog sorting mode" are set.

[0094] The main body control unit 90 also transfers data indicating that the mode is the post-processing mode, the number of sheets, the number of copies, and the thickness of the sheets on which images are to be formed, to the binding process control unit 95. At the same time, the main body control unit 90 transfers a job end signal to the binding process control unit 95 each time image formation is completed.

[0095] To explain the post-processing modes, the "printout mode" is a mode in which sheets from the straight path paper discharge port 35 are stored in the first tray 49 via the processing tray 37 without being bound. In this case, the sheets are stacked on top of each other on the processing tray 37, and the stacked sheet bundle is conveyed to the first tray 49 in response to a job end signal from the main body control unit 90.

[0096] The "product processing and paper discharge mode" is a mode in which image-formed sheets are collated, bound, and then folded to complete the bookbinding process.

[0097] The "staple binding processing mode" is a mode in which sheets from the straight path paper discharge outlet 35 are accumulated and collated on the processing tray 37, and this sheet stack is bound and then stored in the first tray 49. In this case, the operator specifies that the sheets on which images are to be formed are, in principle, sheets of the same paper thickness and size, but it is also possible to specify that only some of the sheets in the sheet stack are cardboard, etc. In this staple binding processing mode, one of "multi-binding," "right corner binding," or "left corner binding" is selected and specified.

[0098] In the "jog sorting mode," sheets on which images are formed in image forming apparatus A are separated into a group in which they are offset and accumulated, and a group in which they are accumulated without offset. On first tray 49, sheet bundles that have been offset and sheet bundles that have not been offset are stacked alternately.

[0099] <Binding process control section> The binding process control unit 95 operates the sheet post-processing device B in accordance with the post-processing mode set by the image formation control unit 90. The binding process control unit 95 includes a control CPU. A ROM 96 and a RAM 97 are connected to the binding process control unit 95, and the operation of the sheet post-processing device B in this embodiment is executed by the control program stored in the ROM 96 and the control data stored in the RAM 97. For this reason, the binding process control unit 95 controls the drive circuits of all the drive motors mentioned above, and starts, stops, and controls the forward and reverse rotation of each motor.

[0100] Image formation continues in image forming apparatus A even while post-processing is being performed in processing section B1. Therefore, in this embodiment, a buffer operation is performed to accumulate sheets conveyed from image forming apparatus A in sheet processing apparatus B. This allows post-processing to be continued without reducing the frequency at which sheets are supplied from image forming apparatus A, i.e., without reducing the productivity of image forming apparatus A. The buffer operation will be described using the following figures.

[0101] An overview of the sheet conveying operation in the sheet post-processing device B will be described with reference to Figures 15 to 31. Figures 15 to 31 show cross-sectional views of the sheet post-processing device B as viewed from the side. Figures 15 to 31 explain the sheet conveying operation from when a sheet conveyed from the image forming device A is conveyed on the straight path 28, when it is bound in the processing unit B1, until it is discharged to the first tray 49. In this embodiment, the following operations are performed during the sheet conveying operation.

[0102] As one of the operations, when the paddle rotor 42 performs a sweeping operation for one sheet, if the sheet is highly rigid, the timing at which the paddle rotor 42 starts to rotate is controlled to be earlier. This prevents the sweeping operation from being delayed due to the forward conveying force of the sheet.

[0103] As one of the operations, when the lift rollers 41 rotate in the reverse direction to pick up the sheet stack, a pressure member presses the sheet stack from above to assist the pick-up operation. In the following description, a configuration in which the sheet stack is pressed from above by a pressure member 1501 (described later) instead of the sheet guide member 44 will be described. Because the pressure member 1501 presses the sheet stack by linear motion, it can press a wider area of ​​the sheet stack more quickly than the rotational motion of the sheet guide member 44. Furthermore, the conveyance of each sheet in the sheet stack is controlled so that a predetermined amount of offset is generated between the leading edges of the sheets. This is intended to apply a pick-up force to the sheets stacked below after the sheet stack exits processing unit B1. Therefore, as the number of sheets increases, the total offset length increases due to the accumulated offset amounts for each sheet, which may result in the sheets overflowing the pressure area of ​​the pressure member 1501. Therefore, in this embodiment, when the number of sheets in a sheet stack is large, the timing at which the lift rollers 41 start the pick-up operation by rotating the sheet stack in the reverse direction is advanced. This allows the total shift length to be accommodated within the pressing portion of the pressing member 1501.

[0104] As one of the operations, during the binding process in processing section B1, the sheet stack is pressed down by a pressing member 1501. This prevents the sheets from shifting within the stack when the binding process is performed due to the influence of air layers existing between the sheets.

[0105] In this embodiment, a presser member 1501 is provided downstream of the discharge rollers 36. The presser member 1501 presses down the trailing edge of the sheet when the trailing edge of the sheet passes through the nip position of the discharge rollers 36.

[0106] 32(a) and 32(b) are diagrams illustrating the arrangement of the press-down member 1501 and the paddle rotator 42. The press-down member 1501 is configured to be linearly movable by a motor and a rack-and-pinion mechanism (not shown), and can move up and down between a standby position where it does not interfere with the conveyance of the sheet that has passed the discharge rollers 36 and a pressing position. In FIGS. 32(a) and 32(b), the dotted line indicates the standby position, and the solid line indicates the pressing position. One operation of the press-down member 1501 will be described. When the press-down member 1501 is in the standby position, the leading edge of the sheet passes the discharge rollers 36 and then passes the lift rollers 41 in the forward direction. Then, based on the timing when the trailing edge of the sheet passes the discharge rollers 36, the press-down member 1501 starts to descend from the standby position. The timing when the trailing edge of the sheet passes the discharge rollers 36 is detected based on the number of pulses counted from the timing when the trailing edge of the sheet passes the sensor 3201. This pressing down operation of the pressing down member 1501 can prevent the trailing edge of the sheet from remaining on the discharge rollers 36.

[0107] Fig. 33 is a diagram showing the arrangement of the push-down members 1501 when the processing tray 37 is viewed from above. Each of the push-down members 3301, 3302, 3303, 3304, and 3305 in Fig. 33 corresponds to the push-down member 1501. In this embodiment, as an example, five push-down members 1501 are arranged in the sheet width direction, and it is possible to control which of the push-down members 1501 is driven depending on the width of the sheet. Specifically, for example, it is possible to drive the push-down members sequentially from the inside to the outside in the sheet width direction.

[0108] When a sheet is conveyed a predetermined distance in the forward direction passing through the lift rollers 41, the sheet is switched back in the reverse direction by the paddle rotator 42 and conveyed to the sheet end regulating unit 38. In this embodiment, when a sheet is switched back, the paddle rotator 42 is rotated in the direction of the arrow. As shown in Figures 32(a) and 32(b), the paddle rotator 42 is composed of two blade-shaped portions. The blade-shaped portions are made of an elastic material such as rubber. In this embodiment, the paddle rotator 42 is composed of two blade-shaped portions, but may be composed of three or more. The difference between Figures 32(a) and 32(b) will be described later.

[0109] FIG. 15(a) shows a state in which sheet S1 has been sent from image forming apparatus A. Sheet S1 corresponds to the first sheet of a sheet bundle to be bound in subsequent binding unit 47. In this embodiment, an operation of forming a bound bundle of three sheets will be described as an example of the number of sheets that form the sheet bundle. FIG. 15(a) shows a state in which sheet S1 has been conveyed up to second conveying roller 202. At this time, press-down member 1501 is in a standby position retracted upward so as not to interfere with sheet conveyance, and paddle rotator 42 is in a pick-up standby state. The pick-up standby state refers to a state in which paddle rotator 42 is not rotating.

[0110] FIG. 15(b) shows a state in which the sheet S1 has been conveyed to the sheet discharge rollers .

[0111] 16(a) shows a state in which the leading edge of the sheet S1 has passed the lifting rollers 41. At this time, the trailing edge of the sheet S1 has not yet passed the discharge rollers .

[0112] FIG. 16(b) shows a state in which the rear end of sheet S1 has passed the discharge rollers 36. At this time, the push-down member 1501 starts to move downward, and starts the operation of pushing down the rear end of sheet S1. FIG. 16(b) also shows a state in which sheet S2 has been sent from image forming apparatus A. Sheet S2 corresponds to the second sheet of the sheet stack to be bound in the subsequent binding unit 47.

[0113] In this embodiment, the push-down member 1501 moves linearly in the up-down direction (vertical direction). Therefore, compared to a case where a member that pushes down the rear end of the sheet by a rotational movement is used, the rear end of the sheet S1 can be quickly pushed down based on the timing when the rear end of the sheet S1 passes the discharge roller 36.

[0114] 17(a) shows a state in which the pressing member 1501 has moved (lowered) to the pressing position and pressed down the rear end of the sheet S1 onto the processing tray 37. Also, FIG. 17(a) shows a state in which the sheet S2 has been conveyed up to the third conveying roller 203.

[0115] FIG. 17(b) shows a state in which the rear end of sheet S1 has been conveyed to sheet end regulating section 38 due to the reverse rotation of lift rollers 41. At this time, push-down member 1501 begins to move upward so as not to interfere with the conveyance of sheet S2. FIG. 17(b) also shows a state in which sheet S2 has been conveyed to discharge rollers 36. In this embodiment, switchback conveyance is performed for one sheet by paddle rotator 42, but for the first sheet of a sheet stack, switchback conveyance is performed by lift rollers 41 because the frictional force between processing tray 37 and the sheet is higher than that generated between sheets. However, switchback conveyance may also be performed for the first sheet of a sheet stack by paddle rotator 42.

[0116] 18(a) shows a state in which the pressing member 1501 has moved to the standby position, and also shows a state in which the leading edge of the sheet S2 has passed through the nip point of the discharge rollers 36.

[0117] 18(b) shows a state in which the leading edge of the sheet S2 has passed the lifting rollers 41. At this time, the trailing edge of the sheet S2 has not yet passed the discharge rollers .

[0118] 19(a) shows a state in which the trailing edge of the sheet S2 has passed the discharge rollers 36. At this time, the press-down member 1501 starts to move downward, and starts the operation of pressing down the trailing edge of the sheet S2.

[0119] 19(b) shows a state in which the push-down member 1501 has moved to the pressing position and pushed down the trailing edge of the sheet S2 onto the sheet S1 on the processing tray 37. At this time, the paddle rotating body 42 starts to rotate and starts to pick up the sheet S2 so that the trailing edge of the sheet S2 is transported to the sheet end regulating unit 38.

[0120] 20(a) shows a state in which the rear end of sheet S2 is being pulled into sheet end regulating portion 38 by paddle rotating body 42. At this time, push-down member 1501 starts to move upward so as not to interfere with the conveyance of succeeding sheet S3.

[0121] FIG. 20(b) shows a state in which the rear end of sheet S2 has been pulled into the sheet end restriction section 38 by the paddle rotor 42. At this time, the push-down member 1501 is in the standby position. FIG. 20(b) also shows a state in which sheet S3 has been sent from image forming apparatus A. Sheet S3 corresponds to the third sheet of the sheet stack to be bound in the subsequent binding unit 47. Here, it is assumed that sheet S3 is a sheet with higher rigidity than sheets S1 and S2. Specifically, for example, sheet S3 is cardboard with a higher basis weight than sheets S1 and S2 (for example, a basis weight of 128 g / m2 or more).

[0122] FIG. 21(a) shows a state in which the leading edge of the sheet S3 has passed the third conveying roller 203. In FIG.

[0123] 21(b) shows a state in which the leading edge of the sheet S3 has passed the lifting roller 41. At this time, the trailing edge of the sheet S3 has not yet passed the discharge roller 36. In this embodiment, at this time, the paddle rotor 42 starts to rotate.

[0124] In FIG. 19B, the paddle rotator 42 begins to rotate when the trailing edge of sheet S2 is pressed down by the push-down member 1501. On the other hand, for sheet S3 with high rigidity, the paddle rotator 42 begins to rotate before the trailing edge of sheet S3 has passed the discharge rollers 36. For a highly rigid sheet, when its trailing edge passes the discharge rollers 36, the conveying force can propel the sheet out of the machine at an unexpected speed, delaying the sheet's conveyance to the sheet edge restriction unit 38 and potentially affecting the discharge timing of the next sheet. Therefore, in this embodiment, the rotation start timing (scratch start timing) of the paddle rotator 42 is advanced for sheets exceeding a predetermined basis weight or sheets that have been treated, such as with a surface coating, to increase their rigidity. This prevents the above-described situation from occurring. On the other hand, for thin paper with a basis weight of 52 g / m² or less, the rotation start timing (scratch start timing) of the paddle rotator 42 is delayed to prevent the trailing edge from remaining on the discharge rollers 36. 21(b) shows a state in which sheet S4 has been sent from image forming apparatus A. Sheet S4 corresponds to the first sheet of the sheet stack following the sheet stack of sheets S1 to S3.

[0125] 22(a) shows a state in which the trailing edge of sheet S3 has passed the discharge rollers 36. At this time, the push-down member 1501 starts to move downward and starts to push down the trailing edge of sheet S3. At this time, the rotation of the paddle rotor 42 is causing a scraping operation, so the blade-shaped portion of the paddle rotor 42 prevents sheet S3 from flying out of the apparatus at an unexpected speed. Also, FIG. 22(a) shows a state in which sheet S4 has been conveyed to the upper conveying rollers 303b by the guide of the upper conveying path flapper 34.

[0126] Image formation continues in the image forming apparatus A even while the binding process is being performed in the processing section B1. Therefore, in this embodiment, a buffering operation is performed to accumulate sheets conveyed from the image forming apparatus A in the sheet processing apparatus B. Specifically, as shown below, while the binding process is being performed on the preceding sheets, the buffering operation is performed on the upper conveying path 30 and the processing section buffer path P1 for the subsequent sheets, and the subsequent sheets are conveyed as a stack of multiple sheets through the discharge rollers 36 to the processing tray 37. This allows the binding process to be continued without reducing the frequency at which sheets are supplied from the image forming apparatus A, i.e., without reducing the productivity of the image forming apparatus A. Figure 22(a) shows a state in which the buffering operation on the upper conveying path 30 has been performed on sheet S4.

[0127] 22(b) shows a state in which the pressing member 1501 has moved to the pressing position and pressed down the rear end of sheet S3 onto sheet S2 on the processing tray 37. At this time, sheet S4 is being conveyed to processing section buffer path P1 by the guide of processing section buffer path flapper 200. FIG. 22(b) also shows a state in which sheet S5 has been sent from image forming apparatus A. Sheet S5 corresponds to the second sheet of the stack following the stack of sheets S1 to S3.

[0128] 23(a) shows a state in which the sheet S5 has been conveyed to the third conveying roller 203. At this time, the processing section buffer path flapper 200 is in a guide position that does not interfere with the conveyance of the sheet S5 on the straight path 28.

[0129] Sheets S4 and S5 are transported synchronously. In this embodiment, sheet S4 is transported so that its leading edge lags behind the leading edge of sheet S5 by a predetermined distance. Synchronization of the transport operation between sheets here is performed, for example, by pulse counting transport control based on the detection timing of the sheets being supplied from image forming apparatus A to straight path entrance 26. This causes the leading edges of each sheet in the sheet stack to be sequentially offset. Therefore, when the sheet stack is subsequently fed into the rear edge of paper loading surface 37a of processing tray 37, the sheets contact the rear edge in order, allowing the leading edges of all sheets in the sheet stack to be aligned and contact the rear edge. While the above description deals with two sheets, sheet S4 and sheet S5, the same applies to three or more sheets. For example, in the case of sheets S4, S5, and S6, sheet S4 is transported so that its leading edge lags behind the leading edge of sheet S5 by a predetermined distance, and so that sheet S5's leading edge lags behind the leading edge of sheet S6 by a predetermined distance. Therefore, the greater the number of sheets, the greater the accumulated misalignment amount, resulting in a larger cross-sectional area of ​​misalignment.

[0130] FIG. 23(b) shows a state in which sheets S4 and S5 overlap and are transported synchronously through the upper transport path 30. FIG. 23(b) also shows a state in which sheet S6 has been sent from the image forming apparatus A. Note that sheet S6 corresponds to the third sheet in the stack following sheets S1 to S3. Sheets S4 and S5 are then transported from the upper transport path 30 to the processing section buffer path P1. Therefore, the processing section buffer path flapper 200 is in a position where it can guide sheets S4 and S5 into the processing section buffer path P1. FIG. 23(b) also shows a state in which the trailing edge of sheet S3 has been pulled into the sheet edge regulating section 38 by the paddle rotor 42. At this time, the push-down member 1501 begins to move upward so as not to interfere with the transport of sheet S3.

[0131] 24(a) shows a state in which the rear end of sheet S3 has been pulled into the sheet end regulating portion 38 by the paddle rotating body 42. At this time, the push-down member 1501 is in the standby position. Also, in FIG. 24(a), sheets S4 and S5 and sheet S6 are transported synchronously with each other. In this embodiment, sheet S5 is transported so that its leading edge lags behind the leading edge of sheet S6 by a predetermined distance.

[0132] FIG. 24(b) shows how the binding unit 47 binds the sheet bundle of sheets S1 to S3. As shown in FIG. 24(b), in this embodiment, the sheet bundle of sheets S1 to S3 is pressed down by a press-down member 1501 during the binding process. This configuration prevents the sheets from shifting during the binding process. Specifically, the air gap between the sheets prevents the sheets from shifting due to the impact force of the stapler during the binding process. In this embodiment, as shown in FIGS. 32(a) and 32(b), the press-down member 1501 has an oblique cross section and moves linearly in the vertical direction, allowing it to contact the processing tray 37 over a wide area. Furthermore, while a rotational movement changes the pressing position and pressing area depending on the number of sheets in the sheet bundle, a linear movement allows the sheets to be pressed under the same conditions without changing the distance between the pressing position and the sheet edge, even if the number of sheets in the sheet bundle changes. This allows for an effective pressing operation on the sheets. FIG. 24(b) shows a state in which sheets S4 and S5 and sheet S6 overlap and are conveyed synchronously through the straight path .

[0133] 25(a) shows how the sheet bundle of sheets S1 to S3 is discharged onto the first tray 49 by the lifting roller 41 and the driven roller 48 after the binding process by the binding unit 47. Also, FIG. 25(a) shows how the leading edge of the sheet bundle of sheets S4 to S6 passes through the sheet discharge roller 36.

[0134] 25(b) shows a state in which the sheet bundle of sheets S1 to S3 has been discharged onto first tray 49. Also, FIG. 25(b) shows a state in which the trailing edge of the sheet bundle of sheets S4 to S6 has passed through discharge rollers 36.

[0135] 26(a) shows a state in which the rear end of the sheet bundle of sheets S4 to S6 is pressed down by the press-down member 1501. In this embodiment, the sheet bundle of sheets S4 to S6 is transported in the discharge direction, and then the lifting and lowering rollers 41 are rotated in the reverse direction, causing the sheet bundle of sheets S4 to S6 to be transported in a switchback manner. Then, the rear end of the sheet bundle of sheets S4 to S6 that has been transported in a switchback manner is pressed down by the press-down member 1501. Note that in this embodiment, when the sheet bundle is transported in a switchback manner, the paddle rotating body 42 does not perform a pick-up operation.

[0136] Fig. 26(b) shows a state in which the push-down member 1501 starts to push down the rear end of the sheet bundle of sheets S4 to S6. Fig. 32(a) is a diagram for explaining the operation of the push-down member 1501 to push down the sheet bundle of three sheets.

[0137] As described above, the three-sheet bundle has its edges misaligned. The three-sheet bundle is, for example, a bundle of sheets S4 to S6. When the trailing edge of the three-sheet bundle passes sensor 3201, lift rollers 41 rotate to transport the sheet bundle forward by a first predetermined amount. After rotating by the first predetermined amount, lift rollers 41 reverse to switchback-transport the sheet bundle in the opposite direction. In parallel with the operation of lift rollers 41, press-down member 1501 begins to descend from the retracted position to the pressing position based on the timing when the trailing edge of the sheet bundle passes sensor 3201.

[0138] 32(a) shows a state in which the sheet stack has been switchback-conveyed a predetermined distance in the opposite direction. Here, the predetermined switchback distance is determined in advance so that the end of the center sheet 2 of the sheet stack is near midpoint A of the cross-sectional length X of the press-down member 1501. As a result, the ends of the bottom (sheet 1) and top (sheet 3) of the sheet stack are contained within the cross-sectional length X of the press-down member 1501.

[0139] Fig. 27(a) shows a state in which the push-down member 1501 starts to push down the rear end of a five-sheet stack. Fig. 32(b) is a diagram for explaining the operation of the push-down member 1501 to push down a five-sheet stack. Note that Figs. 27(a) and 32(b) are not the operation of this embodiment, but are shown for comparison with a three-sheet stack for reference.

[0140] Similar to the three-sheet stack, the five-sheet stack has misaligned edges. Because the misalignment of the sheet edges accumulates one sheet at a time, the accumulated amount of misalignment of the sheet edges in the five-sheet stack is greater than in the three-sheet stack. In other words, assuming that sheets 4 and 5 are also present in the state shown in FIG. 32( a), the edge of sheet 5 may protrude beyond the cross-sectional length X of the press-down member 1501. If this occurs, the edge of sheet 5 may ride up on the press-down member 1501 as the sheet stack is conveyed to the sheet edge regulating unit 38, causing a jam or other problem. Jams caused by riding up on the press-down member 1501 or the sheet edge regulating member 38 are more likely to occur with soft sheets that have a low basis weight.

[0141] Therefore, in this embodiment, when the sheet bundle contains more than a predetermined number of sheets (for example, three sheets), the lift rollers 41 rotate to transport the sheet bundle in the forward direction by a second predetermined amount, which is shorter than the first predetermined amount, based on the timing when the trailing end of the sheet bundle passes the sensor 3201. In other words, the timing of the switchback transport of the sheet bundle is made earlier. As a result, when the sheet bundle is switched back by the predetermined amount in the reverse direction, the end of each sheet of the sheet bundle can be contained within the cross-sectional length X of the push-down member 1501.

[0142] 32(b) shows a state in which, based on the timing when the trailing end of the sheet stack passes sensor 3201, lift rollers 41 rotate to transport the sheet stack in the forward direction a second predetermined amount that is shorter than the first predetermined amount, and then switchback-conveys the sheet stack in the reverse direction a predetermined amount. As shown in FIG. 32(b), the end of sheet 3 in the center of the sheet stack can be positioned near midpoint A of the cross-sectional length X of press-down member 1501. In other words, the ends of sheets 1 to 5 can be contained within the cross-sectional length X of press-down member 1501.

[0143] In FIG. 32(a), the distance from the sheet edge regulating portion 38 to the edge of the sheet 1 is shown as distance Y. In FIG. 32(b), the distance from the sheet edge regulating portion 38 to the edge of the sheet 1 is shown as distance Z. In FIG. 32(b), as described above, the forward rotation amount (second predetermined amount) of the lift roller 41 is controlled to be shorter than the first predetermined amount. Therefore, as a result of switching back in the reverse direction by the predetermined amount, distance Z becomes shorter than distance Y.

[0144] Figure 27(b) shows a state in which the press-down member 1501 has moved to the pressing position and pressed down the rear ends of the sheets S4 to S6 onto the processing tray 37. That is, Figure 27(b) corresponds to Figure 32(a).

[0145] Fig. 28(a) shows a state in which the rear ends of the sheet stack of sheets S4 to S6 are pulled up to the sheet end regulating section 38 by the reverse rotation of the lifting roller 41. Fig. 28(b) shows a state in which the rear ends of the sheet stack of sheets S4 to S6 are further pulled up to the sheet end regulating section 38 by the reverse rotation of the lifting roller 41 and the driven roller 48. Thereafter, the sheets are aligned by being sandwiched between alignment plates 39f and 39r in the sheet width direction.

[0146] FIG. 29(a) shows the binding unit 47 performing the binding process on the sheet bundle of sheets S4 to S6. As shown in FIG. 29(a), in this embodiment, the sheet bundle of sheets S4 to S6 is pressed down by a press-down member 1501 during the binding process. This configuration prevents sheets from shifting during the binding process. Specifically, for example, the presence of an air gap between sheets can prevent the sheets from shifting in the conveyance direction during the binding process. In particular, if the top sheet of a stack of multiple sheets is curled, a larger air gap is created compared to when the sheet is not curled. By pressing and flattening this air gap in advance, it is possible to prevent the sheet from shifting during the binding operation and being bound as is. In this embodiment, the press-down member 1501 has an oblique cross section and moves linearly in the vertical direction, allowing it to come into contact with the processing tray 37 over a wide area. This allows for an effective pressing-down operation on the sheets. The press-down member 1501 may be configured to press down the sheet bundle during the binding process only in a predetermined mode. The predetermined mode is designated by the user via the input unit 93, for example, using a setting menu relating to the binding processing operation.

[0147] In addition, since the sheet stack is pressed down by the press-down member 1501 to perform the binding process, the risk of foreign objects or hands getting into the movement range of the binding unit during the binding operation is reduced, further increasing safety. It can also be executed when the user sets an operation mode with increased safety.

[0148] FIG. 29(b) shows a state in which the pressing member 1501 starts to move toward the standby position after the binding process for the sheet bundle of sheets S4 to S6 has been completed.

[0149] 30(a) shows a state in which the push-down member 1501 is in the retracted position after the binding process for the sheet bundle of sheets S4 to S6 has been completed. FIG. 30(b) shows a state in which the sheet bundle of sheets S4 to S6 is discharged onto the first tray 49 by the lift-up roller 41 after the binding process by the binding unit 47.

[0150] 31 shows a state in which the sheet bundle of sheets S4 to S6 has been discharged onto the first tray 49. That is, in FIG. 31, the sheet bundle of sheets S4 to S6 is stacked on top of the sheet bundle of sheets S1 to S3.

[0151] 15(a) to 23(b), it has been explained that when the stiffness of the sheet is high, the timing at which the paddle rotor 42 starts to rotate is advanced.

[0152] Fig. 34 is a flowchart showing a process for determining the rotation start timing of the paddle rotor 42 depending on the sheet type. The process of Fig. 34 is executed before the operations described in Figs. 15(a) to 31 are performed. Specifically, for example, the process is executed when the sheet type to be subjected to post-processing is set in the input unit 93. The process of Fig. 34 is realized, for example, by the CPU of the main body control unit 90 or the binding process control unit 95 reading a program stored in the ROM 96 into the RAM 97 and executing it.

[0153] In S3400, the CPU acquires information on the sheet type to be bound. In S3401, the CPU determines whether the sheet type is highly rigid based on the acquired sheet type information. Specifically, for example, if the basis weight included in the acquired sheet type information is equal to or greater than a predetermined value, the sheet type is determined to be highly rigid. Note that examples of highly rigid sheet types include sheets with a high basis weight, such as cardboard, and coated paper with a surface coating. If the sheet type is determined to be highly rigid, the process proceeds to S3403; if the sheet type is determined not to be highly rigid, the process proceeds to S3402.

[0154] In S3402, the CPU determines whether the sheet size is small, medium, or large based on the acquired sheet type information. If the sheet size is determined to be small, the process proceeds to S3404; if the sheet size is determined to be medium, the process proceeds to S3405; and if the sheet size is determined to be large, the process proceeds to S3406.

[0155] In S3405, the CPU sets the rotation start timing of the paddle rotor 42 to the default. In other words, the rotation start timing is not adjusted. Here, the rotation start timing in S3405 is set to timing B.

[0156] In S3404, the CPU sets the rotation start timing of the paddle rotor 42 to timing A, which is earlier than timing B. Meanwhile, in S3406, the CPU sets the rotation start timing of the paddle rotor 42 to timing C, which is later than timing B. Once the rotation start timing has been determined in S3404 to S3406, the processing in Figure 34 ends. Note that, although it has been described that the rotation start timing is not adjusted in S3405, the rotation start timing may be adjusted as long as the relationship between timings A to C is maintained.

[0157] In S3403, the CPU determines whether the sheet size is small, medium, or large based on the acquired sheet type information. If the sheet size is determined to be small, the process proceeds to S3407; if the sheet size is determined to be medium, the process proceeds to S3408; and if the sheet size is determined to be large, the process proceeds to S3409.

[0158] In S3409, the CPU determines the rotation start timing of the paddle rotor 42 to be timing F. However, timing F is earlier than timing A.

[0159] In S3408, the CPU sets the rotation start timing of paddle rotor 1502 to timing E, which is earlier than timing F. In S3407, the CPU sets the rotation start timing of paddle rotor 1502 to timing D, which is earlier than timing E. Once the rotation start timing is determined in S3407 to S3409, the processing of FIG. 34 ends.

[0160] As described above, the rotation start timing is controlled to be earlier as the rigidity increases and the sheet size decreases.

[0161] In S3404 to S3409, the rotation start timing of the paddle rotor 42 is determined so that the following relationship exists between each step: That is, the rotation start timing is determined to be earlier in the order of S3406, S3405, S3404, S3409, S3408, and S3407.

[0162] Here, rather than determining the rotation start timing of the paddle rotor 42 in steps S3404 to S3409, the rotation speed of the paddle rotor 42 may be determined so as to have a relationship equivalent to the above relationship. That is, the rotation speed of the paddle rotor 42 may be determined in steps S3406, S3405, S3404, S3409, S3408, and S3407, and the rotation speed may be determined so as to increase in that order. In this case, the rotation start timing of the paddle 1502 remains constant in steps S3404 to S3409. That is, instead of advancing the rotation start timing, the rotation speed of the paddle rotor 42 is increased. This achieves the same effect as a configuration that advances the rotation start timing.

[0163] The position of the paddle rotator 42 relative to the processing tray 37 may be adjustable. In this case, the closer the position of the paddle rotator 42 is to the processing tray 37, the earlier the timing at which the paddle 1502 picks up the sheet, even if the rotation start timing and rotation speed are constant. That is, rather than determining the rotation start timing of the paddle rotator 42 in steps S3404 to S3409, the position of the paddle rotator 42 relative to the processing tray 37 may be determined so as to have a relationship equivalent to the above relationship. That is, the position of the paddle rotator 42 relative to the processing tray 37 may be determined in steps S3406, S3405, S3404, S3409, S3408, and S3407, and the position of the paddle rotator 42 may be determined so as to be closer to the processing tray 37 in that order. In this case, the rotation start timing and rotation speed of the paddle rotator 42 are constant in steps S3404 to S3409. That is, instead of advancing the rotation start timing, the position of the paddle rotor 42 is brought closer to the processing tray 37. This makes it possible to obtain the same effect as with a configuration in which the rotation start timing is advanced.

[0164] In the above, the rotation start timing, rotation speed, and position of the paddle rotor 42 relative to the processing tray 37 are determined separately, but as long as the relationship between the timing of the sheet pick-up can be maintained as described above between each step, these parameters may be determined in combination.

[0165] As described above, according to this embodiment, when the paddle rotor 42 performs the sweeping operation for one sheet, if the sheet has high rigidity, the timing at which the paddle rotor 42 starts to rotate is controlled to be earlier. This prevents the sweeping operation from being delayed due to the forward conveying force of the sheet.

[0166] Furthermore, according to this embodiment, when the lift rollers 41 are rotated in the reverse direction to perform a sheet stack pick-up operation, the sheet stack is pressed down from above by the presser member 1501, thereby assisting the pick-up operation. The presser member 1501 presses down the sheet stack by linear motion, so that the sheet stack can be pressed down more quickly than by the rotational motion of the sheet guide member 44. Furthermore, when the sheet stack contains a large number of sheets, the start timing of the pick-up operation by the lift rollers 41 rotating in the reverse direction relative to the sheet stack is made earlier. This allows the cross-sectional area of ​​the misalignment caused by the accumulation of the amount of misalignment at the leading edges of the sheets to be contained within the pressing portion of the presser member 1501.

[0167] Furthermore, according to this embodiment, during the binding process in processing section B1, the sheet stack is held down by the presser member 1501. This prevents the sheets from shifting when the binding process is performed due to the air layer that exists between the sheets.

[0168] The disclosure of this embodiment includes the following sheet processing apparatus. (Item 1) a sheet stacking section on which sheets to be processed are stacked; a sheet stacking unit that stacks sheets to allow a plurality of sheets to be processed next to wait while the sheets on the sheet stacking unit are being processed, and that, when the sheets stacked on the sheet stacking unit are discharged, shifts the sheets in the sheet conveying direction so that the lower the sheet on the sheet stacking unit, the closer one edge of the sheet that abuts against the regulating unit will be to the regulating unit; a discharge section to which the sheets stacked in the sheet stacking section are discharged; a regulating section that abuts against and regulates one ends of the sheets in the sheet conveyance direction of the plurality of sheets discharged from the discharge section; a push-down member that pushes down a rear end of the sheet fed onto the sheet stacking portion in a sheet conveying direction toward the sheet stacking portion; a control unit that controls the push-down member to perform a push-down operation toward the sheet stacking unit at a first timing when the number of sheets stacked in the sheet stacking unit is a first number of sheets when the stacked sheets are discharged from the discharge unit, and to perform a push-down operation toward the sheet stacking unit at a second timing that is earlier than the first timing when the number of sheets stacked in the sheet stacking unit is a second number of sheets that is greater than the first number of sheets; A sheet processing apparatus comprising: (Item 2) a sheet stacking section on which sheets to be processed are stacked; a sheet stacking unit that stacks sheets to allow a plurality of sheets to be processed next to wait while the sheets on the sheet stacking unit are being processed, and that, when the sheets stacked on the sheet stacking unit are discharged, shifts the sheets in the sheet conveying direction so that the lower the sheet on the sheet stacking unit, the closer one edge of the sheet that abuts against the regulating unit will be to the regulating unit; a discharge section to which the sheets stacked in the sheet stacking section are discharged; a regulating section that abuts against and regulates one ends of the sheets in the sheet conveyance direction of the plurality of sheets discharged from the discharge section; a push-down member that pushes down a rear end of the sheet fed onto the sheet stacking portion in a sheet conveying direction toward the sheet stacking portion; a control unit that controls the sheet stacking unit and the push-down member so that, when the stacked sheets are discharged from the discharge unit, the push-down member performs a pressing operation at a position where one end of the sheet is closer to the regulating unit when the number of sheets stacked in the sheet stacking unit exceeds a predetermined number of sheets, rather than when the number is equal to or less than the predetermined number of sheets; A sheet processing apparatus comprising: (Item 3) the sheet stacking portion is provided with an inclined surface that is inclined downward on the upstream side in the sheet conveying direction, 3. The sheet processing apparatus according to item 1 or 2, wherein the push-down member has a contact surface configured so that the surface that comes into contact with the sheet placed on the inclined surface is substantially parallel to the inclined surface. (Item 4) 4. The sheet processing apparatus according to any one of items 1 to 3, wherein the push-down member is configured to be movable in the vertical direction by linear motion.

[0169] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0170] 28 Straight path: 201 Inlet roller: 202, 203 Shift roller: 203 Intermediate conveying roller: 33a Upper flapper: 33b Lower flapper

Claims

1. a sheet stacking section on which sheets to be processed are stacked; a sheet stacking unit that stacks sheets to allow a plurality of sheets to be processed next to wait while the sheets on the sheet stacking unit are being processed, and that stacks the sheets by shifting them in the sheet conveying direction so that the lower the sheet on the sheet stacking unit is, the closer one end of the sheet that abuts against the regulating unit will be to the regulating unit when the sheets stacked on the sheet stacking unit are discharged; a discharge section to which the sheets stacked in the sheet stacking section are discharged; the regulating section that abuts against and regulates one ends in a sheet conveyance direction of the plurality of sheets discharged from the discharge section; a push-down member that pushes down a rear end of the sheet fed onto the sheet stacking portion in a sheet conveying direction toward the sheet stacking portion; a control unit that controls the push-down member to perform a push-down operation toward the sheet stacking unit at a first timing when the number of sheets stacked in the sheet stacking unit is a first number of sheets when the stacked sheets are discharged from the discharge unit, and to perform a push-down operation toward the sheet stacking unit at a second timing that is earlier than the first timing when the number of sheets stacked in the sheet stacking unit is a second number of sheets that is greater than the first number of sheets; A sheet processing apparatus comprising:

2. a sheet stacking section on which sheets to be processed are stacked; a sheet stacking unit that stacks sheets to allow a plurality of sheets to be processed next to wait while the sheets on the sheet stacking unit are being processed, and that stacks the sheets by shifting them in the sheet conveying direction so that the lower the sheet on the sheet stacking unit is, the closer one end of the sheet that abuts against the regulating unit will be to the regulating unit when the sheets stacked on the sheet stacking unit are discharged; a discharge section to which the sheets stacked in the sheet stacking section are discharged; the regulating section that abuts against and regulates one ends in a sheet conveyance direction of the plurality of sheets discharged from the discharge section; a push-down member that pushes down a rear end of the sheet fed onto the sheet stacking portion in a sheet conveying direction toward the sheet stacking portion; a control unit that controls the sheet stacking unit and the push-down member so that, when the stacked sheets are discharged from the discharge unit, the push-down member performs a pressing operation at a position where one end of the sheet is closer to the regulating unit when the number of sheets stacked in the sheet stacking unit exceeds a predetermined number of sheets, rather than when the number is equal to or less than the predetermined number of sheets; A sheet processing apparatus comprising:

3. the sheet stacking portion is provided with an inclined surface that is inclined downward on the upstream side in the sheet conveying direction, The sheet processing apparatus according to claim 1 , wherein the pressing member has a contact surface configured so that the surface that comes into contact with the sheet placed on the inclined surface is substantially parallel to the inclined surface.

4. 2. The sheet processing apparatus according to claim 1, wherein the pressing member is configured to be movable vertically by linear motion.

Images