Sheet processing device

Abstract

To provide a sheet processing device for further improving skew correction accuracy when performing punching processing of punch holes on sheets discharged from an image forming device.SOLUTION: A sheet processing device comprises: an abutting part provided in a conveyance passage, the abutting part positioning a sheet at a predetermined position by abutting the sheet; a punching part for punching the sheet positioned by the abutting part; a first conveyance roller pair provided on a downstream side of the punching part and the abutting part and configured to convey the sheet along the conveyance passage; a second conveyance roller pair provided on a downstream side of the first conveyance roller pair; a roller pair separation control part for separating or nipping the first conveyance roller pair; and a rotation control part for controlling rotation of each of the first conveyance roller pair and the second conveyance roller pair.SELECTED DRAWING: Figure 30

Description

[Technical Field]

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

[0002] A punch unit may be used to punch holes in sheets on which an image has been formed by image forming apparatus A. In this process, to accurately punch holes in the trailing edge of the sheet, positioning and skew correction are performed based on the trailing edge of the sheet. Specifically, positioning and skew correction are performed by switching back the sheet and abutting it against an abutment section to form a loop in the sheet. Since the punch unit generally punches holes in the trailing edge of the sheet, it is installed upstream of the sheet processing device, and the roller downstream of the punch unit and closest to the punch unit is rotated in the reverse direction to switch back the sheet and abut it against the abutment section. This is because the switchback movement is performed by the roller closest to the abutment section, reducing transport drive loss.

[0003] In recent years, there has been a demand for space-saving sheet processing devices, but if a punch unit is provided on the upstream side of the sheet processing device to reduce the size of the device, the punch unit will be installed between the downstream roller of the image forming device and the upstream roller of the sheet processing device, at a roller pitch that is adjusted to the smallest size sheet, which means that the upstream roller of the sheet processing device and the punch unit on its upstream side will have to be located close to each other.

[0004] Furthermore, in the commercial printing field, the number of small-sized sheets being handled is increasing, and if the spacing between conveying rollers (roller pitch) is set to accommodate such sheets, it becomes necessary to place units that require abutment correction, such as punch units, within the narrow roller pitch. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-273724 Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-described situation, if the sheet is transported using the roller closest to the unit that strikes the sheet to correct skew, the striking portion and the roller may become too close, resulting in an insufficient distance for forming a loop in the sheet.

[0007] SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet processing apparatus that further improves the accuracy of correcting skewed sheets when processing sheets discharged from an image forming apparatus. [Means for solving the problem]

[0008] In order to solve the above problem, the sheet processing device of the present invention is a sheet processing device that performs a perforation process on a sheet sent from an image forming device, and is equipped with a stop section that is provided on a conveying path and positions the sheet at a predetermined position by the sheet hitting it, a perforation section that perforates the sheet positioned by the stop section, a first pair of conveying rollers that is provided downstream of the perforation section and the stop section and conveys the sheet along the conveying path, a second pair of conveying rollers that is provided downstream of the first pair of conveying rollers, a roller pair control section that separates or nips the first pair of conveying rollers, and a rotation control section that controls the rotation of each of the first pair of conveying rollers and the second pair of conveying rollers, and is characterized in that the rotation control section controls the rotation of the second pair of conveying rollers so that the sheet is conveyed to the stop section while the roller pair control section separates the first pair of conveying rollers, and in the space where the first pair of conveying rollers are separated, the sheet hits the stop section, causing the sheet to bend. [Effects of the Invention]

[0009] According to the present invention, it is possible to further improve the accuracy of correcting skew of a sheet when processing a sheet discharged from an image forming apparatus. [Brief explanation of the drawings]

[0010] [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. 10 is a diagram illustrating a separation mechanism for the first conveyor roller. [Figure 15] FIG. 2 is a diagram showing the configuration of a control unit and its surroundings. [Figure 16] 10A and 10B are diagrams for explaining the operation of sheet transport control. [Figure 17] 10A and 10B are diagrams for explaining the operation of sheet transport control. [Figure 18] 10A and 10B are diagrams for explaining the operation of sheet transport control. [Figure 19]10A and 10B are diagrams for explaining the operation of sheet transport control. [Figure 20] 10A and 10B are diagrams for explaining the operation of sheet transport control. [Figure 21] 10A and 10B are diagrams for explaining the operation of sheet transport control. [Figure 22] 10A and 10B are diagrams for explaining the operation of sheet transport control. [Figure 23] 10A and 10B are diagrams for explaining the operation of sheet transport control. [Figure 24] 10A and 10B are diagrams for explaining the operation of sheet transport control. [Figure 25] 10A and 10B are diagrams for explaining the operation of sheet transport control. [Figure 26] 10A and 10B are diagrams for explaining the operation of sheet transport control. [Figure 27] 10A and 10B are diagrams for explaining the operation of sheet transport control. [Figure 28] 10A and 10B are diagrams for explaining the operation of sheet transport control. [Figure 29] 10A and 10B are diagrams for explaining the operation of sheet transport control. [Figure 30] 10 is a flowchart showing a sheet transport control process. [Figure 31] FIG. 2 is a diagram illustrating a configuration of a butting portion. [Figure 32] FIG. 2 is a diagram illustrating a configuration of a butting portion. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. 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.

[0012] [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.

[0013] 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 shown in Fig. 14 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 registration roller pair 8 that aligns the leading edges of each sheet at the end of the path.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.).

[0019] [Sheet post-processing device] The sheet post-processing device B (sheet processing device) 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).

[0020] In this embodiment, the sheet post-processing device B does not need to have all of the above functions, and may be configured appropriately according to the device specifications (design specifications).

[0021] 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 transfers 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 is 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.

[0022] 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.

[0023] <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.

[0024] 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.

[0025] <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 (punching unit) that punches holes in the sheet is arranged in the straight path 28.

[0026] <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.

[0027] 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.

[0028] <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.

[0029] <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.

[0030] <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.

[0031] <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.

[0032] 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.

[0033] 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.

[0034] <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.

[0035] 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.

[0036] A rack 117a is formed integrally with the shift member 117, and is engaged with a shift motor M8 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 M8 (the illustrated one is a stepping motor that can rotate forward and backward).

[0037] 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.

[0038] 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.

[0039] <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.

[0040] 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 third tray 71.

[0041] <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.

[0042] 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.

[0043] 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.

[0044] <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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] <Punch unit> The straight path 28 is provided with a punch unit 100 that punches holes in sheets fed from the straight path inlet 26. The punch unit 100 has a configuration for punching holes in fed sheets, and it has a high-precision mode and a high-productivity mode. Here, an example of the high-precision mode will be described in detail. As shown in FIG. 3, the trailing edge of the sheet in the sheet conveyance direction passes the inlet sensor S1, and the sheet is conveyed in the conveyance direction by a predetermined number of pulses. When the sheet is sandwiched between the first conveyance roller 201 and the second conveyance roller 202, the first conveyance roller 201 and the second conveyance roller 202 simultaneously rotate in the reverse direction, causing the sheet to switch back. The first conveyance roller 201 has a roller pressure separation mechanism that conveys the sheet in the sheet conveyance direction by forward rotation and separates the roller pressure by reverse rotation, enabling the roller pressure separation to be performed by the same drive. Note that sheet conveyance and separation may be performed by separate drives. When the sheet switches back, the first conveyor roller 201 begins to separate from the roller pressure, and the sheet is fed into the punch unit 100 by only the second conveyor roller 202, and the trailing end of the sheet in the sheet conveyance direction abuts against the abutment portion 1501 in the punch unit 100. By the time the trailing end of the sheet in the sheet conveyance direction abuts against the abutment portion 1501, the first conveyor roller 201 has completed the separation from the roller pressure. The sheet that has abutted against the abutment portion 1501 is then further conveyed a predetermined amount (a predetermined pulse amount) and forms a loop (curved shape) between the first conveyor roller 201 and the second conveyor roller 202, and the formed loop corrects skew. The amount by which the sheet that has abutted against the abutment portion 1501 is further conveyed may vary depending on the basis weight and surface information of the sheet. Thereafter, the punch unit 100 punches a punch hole at a predetermined position in the sheet, and the sheet is conveyed in the conveyance direction. When the first conveyor roller 201 is rotated forward, the separation is released and the rollers are brought into pressure contact.

[0050] 14 will be described. The mechanism for separating the first conveyance roller 201 includes a conveyance roller shaft 1404 and a spacing shaft 1403 connected to a conveyance motor (not shown), a pinion roller 1405 that is pressed against the conveyance roller shaft 1404 by the elastic force of a spring (not shown), a pinion rack 1402 that holds the pinion roller 1405, and a pinion gear 1401 that is connected to the pinion rack 1402 and held on the axis of the spacing shaft 1403. When the conveyance motor (not shown) rotates the conveyance roller shaft 1404 in the sheet conveyance direction, the drive of the spacing motor M9 to the spacing shaft 1403 is cut off, and when the conveyance motor (not shown) rotates the conveyance roller shaft 1404 in the direction opposite to the sheet conveyance direction, the drive of the spacing motor M9 is transmitted to the spacing shaft 1403, and the pinion rack 1402 moves in a direction away from the sheet path. As a result, the pinch rollers 1405 held by the pinion rack 1402 are released from pressure contact. The pressure contact separation mechanism may be a cam or lever mechanism. The separation mechanism for the first conveyor roller 201 shown in Fig. 14 is an example of a roller pair control unit, and the separation mechanism for the first conveyor roller 201 may be realized by other configurations.

[0051] Next, a description will be given of the punch unit 100. 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 drive motor M7 to rotate the drive rotation 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 rotation 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 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, side edge alignment plates 39f, 39r protrude upward from paper loading surface 37a of processing tray 37, have regulating surfaces 39x that engage with the side edges of sheets, and are arranged in a pair facing each other on the left and right. This pair of side edge alignment sections 39 is arranged on processing tray 37 so that it can move back and forth with a predetermined stroke. This stroke is set by the size difference between maximum size sheets and minimum size sheets and the offset amount by which the sheet stack is moved to the left or right (offset transport) after alignment.

[0068] That is, 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 bundle 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 to the right for right-corner binding and to the left for left-corner binding (offset movement). 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 bundle of sheets to perform binding after aligning them into a bundle.

[0069] 9, the side edge alignment section 39 is configured to include a right edge alignment member 39f (on the front side of the device) and a left edge alignment member 39r (on the rear side of the device), 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. Alignment motors M1, M2 are connected to the left and right racks 81 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. During "multi-binding," 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. Repeated sheet feed and alignment operations result in the sheets being collated and stacked into a bundle on the processing tray 37. Sheets of different sizes are positioned based on the center. During "corner binding," 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. The binding processing mechanism 47 is composed of a staple unit 47 that can be moved along the rear end of the paper carrying 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 side edge of the sheet (the left edge in the illustration). For this reason, 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 are moved toward the sheet center by the same amount from the standby position to position the sheets at the binding position.

[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 cam surface 54x.

[0083] <Stack tray lifting mechanism> As shown in Fig. 11, the sheet post-processing device B is provided 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 lifting guides 86 provided on the device frame 27. A lifting gear 88 is provided at the base end of the first tray 49 and is connected to a lifting rack gear 87. A drive motor (lifting motor) M4 is connected to the lifting gear 88. Therefore, by controlling the rotation of the drive 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. 15. The image forming system shown in Fig. 15 includes a control unit 90 (hereinafter referred to as the "main body control unit") of image forming apparatus A and a control unit 95 (hereinafter referred to as the "binding process control unit") of sheet post-processing apparatus B. 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 stack 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 stack 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] In the "staple binding processing mode," sheets from the straight path paper discharge outlet 35 are accumulated and collated on the processing tray 37, and this sheet bundle is bound and then stored in the stack tray 49. In this case, the operator specifies that the sheets on which images are to be formed should, in principle, be of the same thickness and size. 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 by image forming apparatus A are separated into a group that is offset and accumulated, and a group that is accumulated without offset. The stack tray alternately stacks the sheet bundles that have been offset and the sheet bundles that have not been offset.

[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 main body 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 using a control program stored in the ROM 96 and 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 described above, and starts, stops, and controls the forward and reverse rotation of each motor. Such drive motors include a conveyance motor that drives a conveyance roller, and the binding process control unit 95 also operates as a rotation control unit for the conveyance roller.

[0100] In addition to the above-described post-processing mode, a process of punching holes by the punch unit 100 may be performed on sheets on which images have been formed by the image forming apparatus A. In this process, positioning is performed based on the rear edge of the sheet to accurately punch holes in the rear edge of the sheet. Specifically, positioning and skew correction are performed by switching back the sheet and striking it against an abutment portion to form a loop in the sheet. When the process of punching holes is performed, an instruction is also sent from the main body control unit 90 to the binding process control unit 95.

[0101] Generally, the roller located downstream of the punch unit 100 and closest to the punch unit 100 is rotated in the reverse direction to switch back the sheet and make it strike the strike portion.

[0102] In recent years, there has been a demand for space-saving sheet processing devices, but if a punch unit is provided on the upstream side of the sheet processing device to reduce the size of the device, the punch unit will be installed between the downstream roller of the image forming device and the upstream roller of the sheet processing device, at a roller pitch that is adjusted to the smallest size sheet, which means that the upstream roller of the sheet processing device and the punch unit on its upstream side will have to be located close to each other.

[0103] Furthermore, in the commercial printing field, the number of small-sized sheets being handled is increasing, and if the distance between conveying rollers (roller pitch) is set to accommodate such sheets, it becomes necessary to place a punch unit within that narrow roller pitch.

[0104] In this situation, when the sheet is switched back by the roller downstream of the punch unit 100 and closest to the punch unit 100, the distance (loop space) for forming a loop in the sheet becomes insufficient.

[0105] Therefore, in this embodiment, the nip of the roller downstream of the punch unit 100 and closest to the punch unit 100 is released, and the sheet is switched back by the reverse operation of the roller located downstream of the released roller. This makes it possible to secure a sufficient distance (loop space) for forming a loop in the sheet.

[0106] The operation of punching holes in sheets within the sheet processing apparatus B will be described below with reference to Figures 16 to 29. Figures 16 to 27 show cross-sectional views of the sheet processing apparatus B as seen from the side. Note that for the sake of illustration, some of the configuration above the straight path 28 is omitted in Figures 16 to 27. Also, Figures 28 and 29 show views of the sheet processing apparatus B as seen from above.

[0107] 16 shows a state in which the sheet processing apparatus B receives the sheet ST discharged from the image forming apparatus A. When the sheet ST passes through the entrance rollers 29, the first conveying rollers 201 and the second conveying rollers 202 start rotating to convey the sheet ST downstream in the conveying direction.

[0108] 31 and 32 are diagrams showing the configuration of the abutment section 1501. The abutment section 1501 includes a spring 3101, an abutment member 3102, and a rotating member 3103. When a sheet ST has not been received from the image forming apparatus A, the abutment section 1501 is in the state shown in FIG. 32. That is, the pulling force of the spring 3101 causes the abutment member 3102 to rotate around the rotating member 3103 as a fulcrum, and the sheet ST bounces up onto the conveyance path on the straight path 28. At this time, when the sheet ST is conveyed from left to right in the figure (switchback), the sheet ST abuts against the recessed portion of the abutment member 3102 and stops. On the other hand, when the sheet ST is conveyed from right to left in the figure, although the sheet ST hits the inclined portion of the abutment member 3102, it can continue to be conveyed by pressing down the abutment member 3102 as shown in FIG. When the rear end of the sheet ST passes through the abutment member 3102 from right to left in the figure, the tensile force of the spring 3101 causes the abutment member 3102 to return to the state shown in Fig. 32. That is, in the state shown in Fig. 16, the abutment portion 1501 is in the state shown in Fig. 31.

[0109] FIG. 17 shows a state in which the leading edge of the sheet ST has been conveyed by the rotation of the first conveying roller 201 and the second conveying roller 202 until it has passed the second conveying roller 202.

[0110] Fig. 18 shows a state in which the rear end of the sheet ST has been conveyed to the punch member 101. The position of the sheet ST in Fig. 18 is a position where the punch unit 100 can punch a punch hole at a specified position in the rear end of the sheet ST. When the sheet ST is conveyed to the position shown in Fig. 18, the rotation of the first conveyance roller 201 and the second conveyance roller 202 stops. In the state shown in Fig. 18, the abutment portion 1501 is in the state shown in Fig. 32. In Fig. 18, the abutment member 3102 is conceptualized as a solid black rectangle.

[0111] 19 shows a state in which the switchback conveyance of the sheet ST is started and the first conveying roller 201 is separated (the nipped state is released). In this manner, in this embodiment, when the sheet ST is conveyed to a predetermined position, the rotation of the first conveying roller 201 and the second conveying roller 202 stops, and the switchback conveyance of the sheet ST is started, the nipped state of the first conveying roller 201 is released.

[0112] 20 shows a state in which the sheet ST is continuously conveyed by switching back. Here, the second conveying rollers 202 rotate so as to convey the sheet ST upstream in the conveying direction. As a result, the sheet ST abuts against the abutting member 3102.

[0113] 28(a) shows a state in which the sheet ST has switched back and hit the abutment member 3102. In this embodiment, the abutment member 3102 is composed of abutment member 3102a and abutment member 3102b. Hereinafter, unless otherwise specified, they will be collectively referred to as the abutment member 3102. Note that this shows a state in which the sheet ST is oblique with respect to the conveyance direction. Therefore, the sheet ST hits the abutment member 3102a first.

[0114] 21 shows a state in which the sheet ST is further switched back and conveyed. Because the second conveying roller 202 continues to rotate, the sheet ST is further pushed in the direction in which it abuts against the abutment member 3102. At this time, the sheet ST is pushed a distance of about 8 mm, resulting in a loop (curved deflection).

[0115] 28(b) shows a state in which the sheet ST is further pushed in the switchback direction after hitting the abutment member 3102. Wavy lines 2701 and 2702 indicate the state in which the sheet ST is bent. As a result of the sheet ST being bent in this way, the skew of the sheet ST relative to the abutment members 3102a and 3102b near the rear end (the leading end in the switchback direction) of the sheet ST is corrected, and the punch unit 100 can punch holes at specified positions.

[0116] 21, the sheet ST is deflected in the space where the first conveying rollers 201 are spaced apart. With this configuration, even if the sheet processing apparatus B becomes smaller and the distance between the first conveying rollers 201 and the punch unit 100 becomes narrower, it is possible to ensure a sufficient space for deflecting the sheet ST to position punch holes and correct skew of the sheet.

[0117] Fig. 22 shows a state in which the punch member 101 has descended onto the sheet ST to punch holes. Fig. 29 is a view of the sheet ST at this time as seen from above. As shown in Fig. 29, a punch hole 2801 has been punched in the sheet ST by the punch member 101. Fig. 23 shows a state in which the punch member 101 has moved upward.

[0118] 24 shows a state in which the sheet ST starts to be conveyed downstream in the conveying direction. Here, the second conveying roller 202 starts to rotate so as to convey the sheet ST downstream in the conveying direction. This eliminates the deflection of the sheet ST. In addition, as the sheet ST starts to be conveyed downstream in the conveying direction, the first conveying roller 201 is in a nip state.

[0119] 25 and 26 show a state in which the sheet ST is further conveyed downstream in the conveying direction. Note that, when conveying the sheet ST, rollers other than the second conveying roller 202 are also rotating. For example, in FIG. 25, the paper discharge roller 36 is also rotating so as to convey the sheet ST downstream in the conveying direction.

[0120] 27 shows a state in which the sheet ST is transported further downstream in the transport direction. Here, the sheet ST is discharged to the first tray 49. In the present embodiment, a configuration is described as an example in which the sheet ST is discharged to the first tray 49 after punching holes by the punch unit 100. However, the sheet ST may be transported to the processing section B1 or the saddle section B2 after punching holes.

[0121] In this way, in this embodiment, the sheet ST can bend in the space between the first conveying roller 201 when it is separated from the first conveying roller 201, so that even when the device is made smaller, productivity in punching the holes can be prevented from decreasing.

[0122] 30 is a flowchart showing the processing executed by the binding process control unit 95 in this embodiment. The processing in FIG. 30 is realized, for example, by the binding process control unit 95 reading a program stored in the ROM 96 into the RAM 97 and executing the program.

[0123] In S101, the binding process control unit 95 detects the receipt of the sheet ST on which the image has been formed by the image forming apparatus A. The receipt of the sheet ST is detected based on a detection signal of the sheet ST by the inlet sensor S1, for example.

[0124] In S102, the binding process control unit 95 starts rotating the first conveying roller 201 and the second conveying roller 202 (rotating in the forward direction) so as to convey the sheet ST downstream in the conveying direction. S101 and S102 correspond to the states shown in FIGS. 16 and 17.

[0125] In S103, the binding process control unit 95 determines whether the sheet ST has reached a predetermined position. Here, the predetermined position is a position where the punch unit 100 can punch a punch hole at a specified position on the rear end of the sheet ST. The process of S103 is repeated until it is determined that the sheet ST has reached the predetermined position, and if it is determined that the sheet ST has reached the predetermined position, the process proceeds to S104.

[0126] In S104, the binding process control unit 95 stops the operations of the first conveying roller 201 and the second conveying roller 202. S104 corresponds to the state shown in FIG.

[0127] In S105, the binding process control unit 95 starts rotating (rotating in the reverse direction) the second conveyance rollers 202 so as to convey the sheet ST upstream in the conveyance direction. Specifically, for example, the binding process control unit 95 first causes the sheet ST to be switched back and conveyed by a first predetermined amount. With the start of the switchback conveyance, the first conveyance rollers 201 are separated. At this time, the sheet ST is in a position as shown in FIG. 28(a). Then, the binding process control unit 95 causes the sheet ST to be further switched back and conveyed by a second predetermined amount. At this time, the sheet ST is in a position as shown in FIG. 28(b), and a deflection occurs in the sheet ST. Due to the deflection, the rear end of the sheet ST comes into contact evenly with the abutment portions 1501a and 1501b, thereby positioning the sheet ST. The first predetermined amount and the second predetermined amount are, for example, the number of pulses of a stepping motor used to control the conveyance of the sheet ST. After the sheet ST has been switched back and conveyed by the second predetermined amount, in S106, the binding process control section 95 stops the second conveying rollers 202. S105 and S106 correspond to the states shown in FIGS.

[0128] In S107, the binding process control unit 95 performs a punching process for forming punch holes using the punch unit 100. Specifically, for example, the binding process control unit 95 lowers the punch member 101 toward the sheets ST. S107 corresponds to the state shown in FIG.

[0129] In S108, the binding process control section 95 retracts the punching members 101 from the sheets ST. S109 corresponds to the state shown in FIG.

[0130] In S109, the binding process control unit 95 starts rotating the second conveying rollers 202 so as to convey the sheet ST downstream in the conveying direction. At this time, the flexure that has occurred in the sheet ST is eliminated. As the sheet ST starts to be conveyed downstream in the conveying direction, the first conveying rollers 201 are brought into a nip state. This makes it possible to accept the subsequent sheet supplied from the image forming apparatus A. S109 corresponds to the state shown in FIG. 24.

[0131] In S110, the binding process control unit 95 controls the transport of the sheet ST. For example, it controls the operation of each roller so that the sheet ST is discharged onto the first tray 49. S110 corresponds to the states shown in FIGS. 25, 26, and 27. After S110, the process in FIG. 30 ends.

[0132] As described above, according to this embodiment, the nip of the roller downstream of the punch unit 100 and closest to the punch unit 100 is released, and the sheet is switched back by the reverse operation of the roller located downstream of the released roller. This ensures sufficient space for forming a loop in the sheet. Furthermore, in this embodiment, the abutting portion 1501 is configured as shown in FIGS. 31 and 32 . However, the abutting portion 1501 may be configured to be movable between an abutting position located on the straight path 28 and a retracted position where the abutting portion 1501 is retracted to another position above the straight path 28. In this case, for example, the binding process control unit 95 moves (lowers) the abutting portion 1501 from the retracted position to the abutting position in S105, and moves (raises) the abutting portion 1501 from the abutting position to the retracted position in S109.

[0133] In this embodiment, the conveying direction when positioning a sheet and correcting skew has been described as a switchback conveying direction, but the present invention can also be applied to devices with a normal conveying direction (progressive). For example, when performing processes such as perforating, binding, creasing, or folding on the leading edge or center of a sheet, the leading edge of the sheet is brought into contact with an abutment to perform positioning and skew correction. However, if the abutment and the nearest roller are located close to each other, the distance for loop formation when conveyed by the nearest roller is insufficient. In such cases, the nearest roller can be separated and the sheet conveyed by the roller upstream of it, ensuring the distance for loop formation.

[0134] The present invention is particularly effective for external sheet processing devices rather than for sheet processing devices installed in the internal space of an image forming apparatus. In the case of sheet processing devices installed in the internal space of an image forming apparatus, they are generally attached directly to the image forming apparatus, but in the case of external sheet processing devices, various optional devices are installed between the image forming apparatus and the external sheet processing device, which increases the possibility of sheets skewing.

[0135] The disclosure of this embodiment includes the following sheet processing apparatus. (Item 1) A sheet processing apparatus that performs a punching process on a sheet sent from an image forming apparatus, an abutment portion that is provided in the conveyance path and that positions the sheet at a predetermined position by the sheet abutting against the abutment portion; a punching section that punches holes in the sheet positioned by the abutting section; a first conveying roller pair provided downstream of the punching portion and the abutting portion and configured to convey the sheet along the conveying path; and a second conveying roller pair provided downstream of the first conveying roller pair. a roller pair separation control section that separates or nips the first conveying roller pair; a rotation control unit that controls the rotation of each of the first conveying roller pair and the second conveying roller pair; Equipped with the rotation control unit controls the rotation of the second conveying roller pair so that the sheet is conveyed to the abutting portion while the roller pair separation control unit separates the first conveying roller pair, In a space where the first conveying roller pair is separated, the sheet abuts against the abutting portion, thereby causing the sheet to bend. A sheet processing apparatus characterized by: (Item 2) 2. The sheet processing apparatus according to item 1, wherein the sheet is deflected across a space between the first pair of conveying rollers and the second pair of conveying rollers and a space where the first pair of conveying rollers are separated. (Item 3) 3. The sheet processing apparatus according to item 1 or 2, wherein after the sheet is transported toward the downstream side of the transport path, the rotation control unit reverses the second transport roller pair so that the sheet is transported to the abutment portion. (Item 4) Item 4. The sheet processing apparatus according to item 3, wherein when the rear end of the sheet is transported to a position corresponding to the perforation section, the rotation control section reverses the second transport roller pair so that the sheet is transported to the abutment section. (Item 5) 5. The sheet processing apparatus according to item 4, wherein the rotation control unit transports the sheet a first predetermined amount until the sheet reaches the abutment portion, and then transports the sheet further in the direction of the abutment portion a second predetermined amount. (Item 6) 6. The sheet processing apparatus according to item 5, wherein the rotation control unit causes the sheet to bend when the sheet has been conveyed by the second predetermined amount. (Item 7) The abutting portion is When the leading edge of the sheet advances from the upstream side to the downstream side of the conveying path to the abutting portion, the sheet continues to be conveyed, and when the leading edge of the sheet advances from the downstream side to the upstream side of the conveying path to the abutting portion, the sheet stops by abutting against the abutting portion. 7. The sheet processing apparatus according to any one of items 1 to 6, characterized in that the sheet processing apparatus is configured as follows. (Item 8) 8. The sheet processing apparatus according to any one of items 1 to 7, wherein the punching section punches holes in the positioned sheet by causing bending in the sheet. (Item 9) The sheet processing apparatus described in any one of items 1 to 8, characterized in that after the punching section has performed punching, the rotation control section rotates the second pair of conveying rollers so that the sheet is conveyed toward the downstream side of the conveying path. (Item 10) 10. The sheet processing apparatus according to item 9, wherein after the punching section has punched the sheet, the first conveying roller pair is in a nip state when the sheet is conveyed toward the downstream side of the conveying path. (Item 11) 11. The sheet processing apparatus according to any one of items 1 to 10, further comprising a post-processing unit that performs post-processing on the sheet after the punching unit has punched holes. (Item 12) A sheet processing apparatus that processes sheets sent from an image forming apparatus, an abutment portion that is provided in the conveyance path and that positions the sheet at a predetermined position by the sheet abutting against the abutment portion; a processing section that processes the sheet positioned by the abutting section; a first pair of conveying rollers that convey the sheet along the conveying path toward the processing section and the abutting section and are close to the abutting section; and a second pair of conveying rollers that are farther from the abutting section than the first pair of conveying rollers. a roller pair separation control section that separates or nips the first conveying roller pair; a rotation control unit that controls the rotation of each of the first conveying roller pair and the second conveying roller pair; Equipped with the rotation control unit controls the rotation of the second conveying roller pair so that the sheet is conveyed to the abutting portion while the roller pair separation control unit separates the first conveying roller pair, In a space where the first conveying roller pair is separated, the sheet abuts against the abutting portion, thereby causing the sheet to bend. A sheet processing apparatus characterized by:

[0136] 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]

[0137] 28 Straight path: 201 Inlet roller: 202, 203 Shift roller: 203 Intermediate conveying roller: 33a Upper flapper: 33b Lower flapper

Claims

1. A sheet processing apparatus that performs a punching process on a sheet sent from an image forming apparatus, an abutment portion that is provided in the conveyance path and that positions the sheet at a predetermined position by the sheet abutting against the abutment portion; a punching section that punches holes in the sheet positioned by the abutting section; a first conveying roller pair provided downstream of the punching portion and the abutting portion and configured to convey the sheet along the conveying path; and a second conveying roller pair provided downstream of the first conveying roller pair. a roller pair separation control section that separates or nips the first conveying roller pair; a rotation control unit that controls the rotation of each of the first conveying roller pair and the second conveying roller pair; Equipped with the rotation control unit controls the rotation of the second conveying roller pair so that the sheet is conveyed to the abutting portion while the roller pair separation control unit separates the first conveying roller pair, In a space where the first conveying roller pair is separated, the sheet abuts against the abutting portion, thereby causing the sheet to bend. A sheet processing apparatus characterized by:

2. 2. The sheet processing apparatus according to claim 1, wherein the sheet is deflected across a space between the first pair of conveying rollers and the second pair of conveying rollers and a space where the first pair of conveying rollers are separated.

3. 2. The sheet processing apparatus according to claim 1, wherein after the sheet is transported toward the downstream side of the transport path, the rotation control unit reverses the rotation of the second transport roller pair so that the sheet is transported to the abutment portion.

4. 4. The sheet processing apparatus according to claim 3, wherein when the trailing end of the sheet is conveyed to a position corresponding to the perforation portion, the rotation control unit reverses the rotation of the second conveying roller pair so that the sheet is conveyed to the abutment portion.

5. 5. The sheet processing apparatus according to claim 4, wherein the rotation control unit transports the sheet a first predetermined amount until the sheet reaches the abutment portion, and then transports the sheet further in the direction of the abutment portion a second predetermined amount.

6. 6. The sheet processing apparatus according to claim 5, wherein the sheet is deflected when the rotation control unit conveys the sheet by the second predetermined amount.

7. The abutting portion is When the leading edge of the sheet advances from the upstream side to the downstream side of the conveying path to the abutting portion, the sheet continues to be conveyed, and when the leading edge of the sheet advances from the downstream side to the upstream side of the conveying path to the abutting portion, the sheet stops by abutting against the abutting portion.

2. The sheet processing apparatus according to claim 1, wherein the sheet processing apparatus is configured as follows.

8. The sheet processing apparatus according to claim 1 , wherein the punching section punches holes in the sheet that has been positioned by the occurrence of bending in the sheet.

9. 2 . The sheet processing apparatus according to claim 1 , wherein after the punching unit has punched the sheet, the rotation control unit rotates the second conveying roller pair so that the sheet is conveyed downstream along the conveying path.

10. 10. The sheet processing apparatus according to claim 9, wherein, after the punching section has punched the sheet, when the sheet is transported downstream along the transport path, the first transport roller pair is in a nip state.

11. The sheet processing apparatus according to claim 1 , further comprising a post-processing unit that performs post-processing on the sheet after the punching unit has punched holes in the sheet.

12. A sheet processing apparatus that processes sheets sent from an image forming apparatus, an abutment portion that is provided in the conveyance path and that positions the sheet at a predetermined position by the sheet abutting against the abutment portion; a processing section that processes the sheet positioned by the abutting section; a first pair of conveying rollers that convey the sheet along the conveying path toward the processing section and the abutting section and are close to the abutting section; and a second pair of conveying rollers that are farther from the abutting section than the first pair of conveying rollers. a roller pair separation control section that separates or nips the first conveying roller pair; a rotation control unit that controls the rotation of each of the first conveying roller pair and the second conveying roller pair; Equipped with the rotation control unit controls the rotation of the second conveying roller pair so that the sheet is conveyed to the abutting portion while the roller pair separation control unit separates the first conveying roller pair, In a space where the first conveying roller pair is separated, the sheet abuts against the abutting portion, thereby causing the sheet to bend. A sheet processing apparatus characterized by:

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