Bookbinding processing device and image forming system provided with bookbinding processing device

Abstract

This bookbinding processing device comprises: a conveyance control means for controlling a conveyance means so as to send a preceding sheet conveyed on a conveyance path to a buffer path; and a buffer conveyance control means for controlling a buffer conveyance means so as to convey the preceding sheet from the buffer path to the conveyance path on the basis of a detection result, of a subsequent sheet following the preceding sheet, detected by the detection means. The conveyance control means controls the conveyance means so as to send a bundle of the preceding sheet and the subsequent sheet to a bookbinding processing path.

Description

Bookbinding processing device and image forming system equipped with bookbinding processing device

[0001] The present invention relates to a bookbinding processing device that performs bookbinding processing on sheets on which images have been formed, and an image forming system that includes the bookbinding processing device.

[0002] A known image forming system that performs post-processing on sheets includes an image forming apparatus and a post-processing device that is connected to the paper discharge port of the image forming apparatus and accumulates image-formed sheets, post-processes them, and stacks them on a stacking section.

[0003] As this post-processing, a bookbinding process is known in which the stacked sheets are bound at two locations and folded in half to form a book.

[0004] Patent document 1 describes a configuration in which a sheet is received from the main body paper discharge port 3 of the image forming device A and transported to a second accumulation section 35 via a second switchback transport path SP2 branching downward from the sheet feed path P1.

[0005] Also disclosed is a configuration in which, during the bookbinding process in the second stacking section 35, the trailing end portion of the preceding sheet is placed in a waiting path P3 provided in the sheet feed path P1, thereby inserting the subsequent sheet below the preceding sheet.

[0006] However, Patent Document 1 does not have the technical idea of ​​aligning the position of the preceding sheet with the position of the succeeding sheet, because with the configuration of Patent Document 1, even if an attempt is made to advance the succeeding sheet, it is stopped by friction generated when it is sandwiched between the stopped preceding sheet and roller 30a, and in fact the succeeding sheet cannot advance from the state shown in Figure 12(c) to Figure 12(d).

[0007] Japanese Patent Application Laid-Open No. 2008-213971

[0008] SUMMARY OF THE INVENTION An object of the present invention is to provide a bookbinding processing device that can align a sheet bundle before feeding it into a bookbinding processing path.

[0009] A bookbinding processing device according to the present invention comprises a transport path for transporting sheets from an entrance to an exit, a bookbinding processing means provided below the transport path for performing bookbinding processing including binding and folding on a sheet stack, a bookbinding processing path for transporting sheets from the transport path to the bookbinding processing means, a transport means provided on the transport path for transporting sheets, a detection means for detecting that a sheet transported by the transport means has reached a predetermined position, a buffer path provided above the transport path for buffering sheets, a buffer transport means provided on the buffer path for transporting sheets, a transport control means for controlling the transport means to feed a preceding sheet transported along the transport path into the buffer path, and a buffer transport control means for controlling the buffer transport means to transport the preceding sheet from the buffer path to the transport path based on the detection result of a subsequent sheet following the preceding sheet by the detection means, and the transport control means controls the transport means to feed the bundle of the preceding sheet and the subsequent sheet into the bookbinding processing path.

[0010] According to the present invention, the sheet bundle can be fed into the bookbinding process path after being aligned.

[0011] Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar elements are designated by the same reference numerals.

[0012] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments of the present invention, and are used to explain the principles of the present invention together with the description thereof.

[0023] Fig. 1 is a diagram showing the appearance of an image forming system. Fig. 2 is a diagram showing the configuration of a sheet post-processing device. Fig. 3 is a diagram showing the configuration in the vicinity of a straight path. Fig. 4 is a diagram showing the configuration of a punch unit. Fig. 5 is a diagram showing the configuration of a punch unit. Fig. 6 is a diagram showing a conveyance roller shift mechanism. Fig. 7 is a diagram showing a conveyance roller shift mechanism. Fig. 8 is a diagram showing a binding mechanism. Fig. 9 is a diagram showing a binding mechanism. Fig. 10 is a diagram showing a tray lifting mechanism. Fig. 11 is a diagram showing a sheet discharge mechanism. Fig. 12 is a diagram showing a sheet discharge mechanism. Fig. 13 is a diagram showing a staple unit. Fig. 14 is a diagram showing the configuration around a control unit. Fig. 15 is a flowchart showing processing in a bookbinding process delivery mode. Fig. 16 is a diagram showing a sheet buffer operation in a sheet processing device. Fig. 17 is a diagram showing a sheet buffer operation in a sheet processing device. Fig. 18 is a diagram showing a sheet buffer operation in a sheet processing device. Fig. 19 is a diagram showing a sheet buffer operation in a sheet processing device. FIG. 1 is a diagram for explaining a sheet buffer operation in a sheet processing apparatus. FIG. 2 is a diagram for explaining a sheet buffer operation in a sheet processing apparatus. FIG. 3 is a diagram for explaining a sheet buffer operation in a sheet processing apparatus. FIG. 4 is a diagram for explaining a sheet buffer operation in a sheet processing apparatus. FIG. 5 is a diagram for explaining a sheet buffer operation in a sheet processing apparatus. FIG. 6 is a diagram for explaining a sheet buffer operation in a sheet processing apparatus. FIG. 7 is a diagram for explaining a sheet buffer operation in a sheet processing apparatus. FIG. 8 is a diagram for explaining a sheet buffer operation in a sheet processing apparatus. FIG. 9 is a diagram for explaining a lateral registration adjustment. FIG. 10 is a diagram for explaining a lateral registration adjustment. FIG. 11 is a diagram for explaining a lateral registration adjustment. FIG. 12 is a diagram for explaining a lateral registration adjustment.1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment. FIG. 1 is a diagram for explaining lateral registration adjustment.

[0013] 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.

[0014] [Image Forming Apparatus] An image forming apparatus A in the image forming system shown in Fig. 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 (e.g., a 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 conveying 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 (developer), and a cleaner (not shown) 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 includes a platen 17 on which an original image 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 image 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 the 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 is configured to include 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 that post-processes 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 can be configured as appropriate 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 image-formed sheets, and then folding and finishing the sheets into a book.

[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 the straight path entrance 26 connected to the sheet discharge outlet 16 of the image forming apparatus A, and then stores the sheets in storage units (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, it can also transport cardboard and the like.

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

[0025] 2, the 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 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 the image forming device A located upstream, and the discharge outlet 16 of the image forming device A and the straight path inlet 26 of the sheet post-processing device B are connected on the installation surface.

[0026] The housing 27 of the sheet 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, and other components described below are attached between the left and right side frames. The device housing 27 is not limited to the illustrated shape and can have any suitable design. Furthermore, the device frame 70 is not limited to a structure with left and right side frames and connecting stays, and various frame structures, such as a monocoque structure, can be used.

[0027] 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 inlet 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 located on the opposite side of the inlet (straight path inlet 26) across the device. The straight path 28 includes an inlet 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 inlet 26 side, as a conveyance mechanism that can convey a sheet from the straight path inlet 26 to the straight path paper discharge outlet 35 and from the straight path paper discharge outlet 35 to the straight path inlet 26. Furthermore, a paper discharge roller 36 (including a sheet conveyance mechanism such as a belt) is arranged at the straight path paper discharge outlet 35 as a conveyance mechanism. Near the straight path entrance 26, an entrance sensor Se1 is located to detect either the leading or trailing edge, or both, of the sheet being received, and a lateral registration detection sensor S0 (detection unit) is located to detect the edge position (side edge) of the sheet parallel to the conveyance direction. Near the straight path exit 35, a discharge sensor Se2 is located to detect the leading or trailing edge of the sheet. Sheets discharged from the straight path exit 35 are discharged to the first tray 49 via the first discharge path 31 connected to the straight path exit 35, or are guided to the processing unit B1. A punch unit 100 is located in the straight path 28 to punch holes in the sheet. The entrance sensor Se1 and the discharge sensor Se2 can be implemented by a photointerrupter, a combination of a flag that contacts the sheet, and a sensor, or the like.

[0028] <Layout of Sheet Carry-In Path> 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 provided 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 retracting 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, namely, the saddle path flapper 33b, the saddle buffer path flapper 33a, and the processing unit buffer path flapper 200, are configured with flapper guides that are movable 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 unit buffer flapper 200 guides a sheet sent from the straight path entrance 26 to the processing unit buffer path P1 via processing unit 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 minimotor.

[0031] <Upper Conveyance Path> An upper conveyance path 30 (printout discharge path) that conveys sheets other than those to be discharged to the straight path discharge outlet 35 is connected to the straight path 28, and an upper conveyance path flapper 34 for guiding sheets to the upper conveyance path 30 is provided at the path branch point. The upper conveyance path 30 is also provided with upper conveyance rollers 303 (303a, 303b) that guide the sheet to the third tray 71. As a result, the sheet guided to the upper conveyance path 30 is discharged from the upper conveyance path discharge outlet 40 to the third tray 71 (overflow tray). In this embodiment, the upper conveyance path 30 is also used as a sheet evacuation path.

[0032] <Saddle Path> A saddle path 32 for conveying sheets into the saddle section B2 is connected to the straight path 28, and a saddle path flapper 33b for guiding sheets to the saddle path 32 is provided at the path branch section. 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. Note that the saddle section B2 is preferably located below the straight path 28 because it also uses gravity to align the sheets.

[0033] <Saddle buffer path> 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 conveyance 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 conveyed 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 so that it can be raised and lowered 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] <Conveyor Roller Shift Mechanism in the Carry-In Path> The conveyor shift mechanism provided for the conveyor rollers on the above-mentioned conveyor path will now be described with reference to Figures 6 and 7. The first conveyor roller 201, second conveyor roller 202, third conveyor roller 203, and conveyor 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 integrally formed with the drive rotation shaft 115, and the rotation of the drive motor is transmitted to the driven gear 118. 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 be driven. 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] <Conveyance Shift Operation> Here, the shift operation (jog sorting mode) of a sheet conveyed into the sheet post-processing device B will be described. A sheet fed from the image forming device A is conveyed in the following order: straight path entrance 26, entrance rollers 29, first conveyance rollers 201, second conveyance rollers 202, and third conveyance rollers 203. At this time, the entrance sensor Se1 simultaneously detects the timing of sheet delivery. As the sheet conveyed by the entrance rollers 29 passes through the straight path 28, the edge position of the sheet is detected by the 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 Unit> Processing unit B1 is a post-processing unit that is disposed downstream of the straight path 28 and includes a processing tray 37 that collates and stacks sheets sent from the 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 the straight path paper discharge outlet 35 of the straight path 28, and the processing tray 37 is disposed below the step. A first paper discharge path (first switchback path) 31 is formed between the straight path paper discharge outlet 35 and the processing tray 37, which reverses the conveying direction from the paper discharge outlet and guides the 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 in 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 sheets fed 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 saddle section B2 may be configured to collate and stack one or more sheets, and only perform an inward folding process on the center portion without saddle stitching.

[0047] The saddle section B2 is configured to include a guide member 66 that accumulates sheets in a bundle, 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 bundle 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. The folding process mechanism, as shown in Fig. 2, 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 disposed in a substantially horizontal direction, the saddle path 32 that guides sheets to the saddle section B2 is disposed in a vertical direction, and the guide member 66 that collates and stacks the sheets is disposed in a substantially vertical direction. By disposing the straight path 28 in a direction that crosses the device housing 27 and disposing the saddle path 32 and saddle section B2 in a vertical direction in this manner, the device can be made slimmer. Note that the saddle section B2 in this embodiment refers to the tray that supports the sheets, the binding unit, and the folding unit. The saddle section B2 is disposed so that its lower end is located downstream in the conveying direction (left side in FIG. 2 ) from its upper end when the guide member 66 supports a maximum-size sheet, thereby achieving a compact size in the conveying direction.

[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> The punch unit 100, which is disposed on the straight path 28 and punches holes in a sheet fed from the straight path inlet 26, will be described with reference to Fig. 5. The punch unit 100 has multiple punch members 101a to 101e arranged at predetermined intervals in a direction perpendicular to the sheet conveyance 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 movable up and down, a drive cam that moves each punch member up and down (reciprocating in the punching direction), and a drive motor M7 that drives this drive cam.

[0053] Reference numeral 104 in the figure denotes a waste box, which is disposed below the punch member 101 and stores punched waste paper. The waste box 104 is slidably attached to a guide rail (not shown) on the device frame 70 (different from the unit frame). Reference numeral 106 in the figure denotes a rotation operating 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 operating 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 conveyance direction of the straight path 28, and a lower frame 102b. A plurality of punch members 101a to 101e are arranged on the upper frame 102a at predetermined intervals in a direction perpendicular to the sheet conveyance direction (hereinafter referred to as the "transport perpendicular direction") so as to be reciprocable (vertically movable) in the punching direction. The lower frame 102b has punch holes (dies) formed in positions opposite 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 processing control unit 95 described later controls the 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 waste box 104 is disposed below the punch member 101, is supported by a guide rail (not shown) provided on the apparatus frame, and is detachable from the front side of the apparatus.

[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 operating 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 Section] 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 switchbacks 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 transport 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 disposed 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 elevator 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 a drive force 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 and discharges 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] <Sheet positioning mechanism> Positioning mechanisms 38 and 39 that position sheets at a predetermined binding position are arranged on the processing tray 37, and the illustrated one is configured to include 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 configured with a stopper member that abuts against and regulates the rear end of the sheet, as shown in Fig. 3. Also, a side edge aligning member 39 will be described later with reference to Fig. 9. Sheets are discharged from the straight path 28 with a center reference, and depending on the type of binding mode, the sheets are positioned with the same center reference or with one side reference.

[0067] 9, side edge alignment plates 39F, 39R protrude upward from the paper mounting surface 37a of the 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 the processing tray 37 so that it can move back and forth with a predetermined stroke. This stroke is set by 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 (offset transport) after alignment.

[0068] In other words, the movement strokes of the left and right side edge alignment plates 39F, 39R are set based on 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 conveyed 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 conveyed into the processing tray 37 (for each conveyed sheet), or by moving the entire stack to perform the binding process 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 front to back, and the side edge alignment section 39, which has the regulating surface 39x that engages 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 to a motor that reciprocates the timing belt via a pulley.

[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 "multi-binding," sheets are transported 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 transported onto the processing tray 37 are then positioned based on the sheet center and stacked into a bundle. By repeating this sheet transport 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 "corner binding," sheets are transported 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 processing mechanism 47 that binds the sheet stack accumulated on the paper loading surface 37a is disposed on the processing tray 37. The paper loading 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 processing mechanism 47 is configured as a binding unit 47 (hereinafter the same as "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 running rail 53 and a second running 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 the sheets so that sheets of different sizes coincide with each other, using the binding edge of the sheet (the left edge in the illustrated example) as the reference. 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 (described later) sets the movement amount of the left and right side edge alignment plates 39F, 39R according to the sheet size.

[0076] The binding process control unit 95, which will be described later, aligns the sheets based on the center reference when performing binding processes other than binding the sheet corners, such as 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 toward the sheet center from the standby 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 sheet to be bound on the processing tray 37.

[0078] 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, the pulley 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 the device frame (chassis frame) 27b, which is fixed to the side frames 70f, 70r by passing through an opening provided in the side frames 70f of the device frame 70. A first running rail 53 and a second running rail 54 are arranged on the device frame 27b. A running rail surface 53x is formed on the first running rail 53, and a running cam surface 54x is formed on the second running rail 54. The running rail surface 53x and the running cam surface 54x cooperate with each other to support the staple unit 47 (hereinafter referred to as the "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 Figure 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 running 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 running rail surfaces 53x and second rolling rollers 84 (cam follower members) that engage with the running cam surfaces 54x. The staple unit 47 is also formed with ball-shaped sliding rollers 47x (two locations 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, 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 27 b with the sliding rollers 47 x and the guide rollers 47 y. The first rolling rollers 83 and the second rolling rollers 84 rotate along the running rail surface 53 x and the running cam surface 54 x, respectively, while following the rail surface 53 x and the cam surface 54 x.

[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 lifted and lowered according to the amount of sheets stacked thereon. To this end, 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 lifted and lowered according to the amount of sheets stacked thereon.

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

[0085] 12A to 12C show the sheet bundle discharge mechanism. The conveyor mechanism includes a pusher protrusion 45 that transports 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 pusher 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 an elevating roller 41 that presses against the driven roller 48 is disposed opposite the driven roller 48. The driven roller 48 and the elevating roller 41 constitute 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. Figure 12A 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 an operating state. Figure 12B 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 pusher protrusion 45 and the rotation of the discharge roller mechanisms 48, 41. Figure 12C 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 pusher protrusion 45 waits in the illustrated position and returns (rearwards) to its initial position.

[0087] <Configuration of Stapling Unit> The configuration of the 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 opposite to each other at the stapling position on the drive cam 47d, 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 member 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 vigorously descends toward the anvil member 47c. This action bends the staple into a U-shape, and the driver then inserts the staple into the sheet stack. The tip of the staple is then bent by the anvil member 47c, resulting in a 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.

[0091] The staple cartridge 52 employs a structure in which staples connected in a band shape are stored in a box-shaped cartridge in layers, or in a roll. 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. The staple control circuit is also configured to control the drive motor M4 to execute the stapling operation in response to a staple signal, and 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] <Explanation of Control Configuration> 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 the "main body control unit") and a control unit 95 of sheet post-processing apparatus B (hereinafter referred to as the "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, etc., 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 discharge 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. Details will be described later with reference to FIG.

[0097] In the "staple binding 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 are, in principle, sheets of the same paper thickness and size. In this staple binding 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 in which they are offset and accumulated, and a group in which they are 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 Unit> 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 is configured to include 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.

[0100] The bookbinding process paper discharge mode, which is one of the post-processing modes, will be described with reference to Figure 15. S101 to S102 indicate the process in image forming apparatus A, and S103 to S113 indicate the process in sheet post-processing apparatus B. That is, the process in S101 to S102 is realized, for example, by the main body control unit 90 reading a program stored in ROM into RAM and executing it. The process in S103 to S115 is realized, for example, by the binding process control unit 95 reading a program stored in ROM 96 into RAM 97 and executing it.

[0101] In S101, the main body control unit 90 forms an image on a sheet, and in S102, the sheet on which the image has been formed is discharged. The sheet on which the image has been formed by the image forming apparatus A is guided to the straight path 28.

[0102] In S103, the binding process control unit 95 controls each motor to transport the sheet discharged from the image forming apparatus A along a path to the leading edge regulation stopper 67. The sheet transport control in S103 will be described later.

[0103] In S104, the binding process control unit 95 moves the position of the leading edge regulating stopper 67 to a position where the sheet can be introduced. At that time, the binding process control unit 95 sets the position of the leading edge regulating stopper 67 based on the size of the sheet in the conveyance direction received from the image forming apparatus A. In S105, the binding process control unit 95 causes the moved leading edge regulating stopper 67 to introduce the sheet. The introduced sheet is brought into a state where it abuts against the receiving portion of the leading edge regulating stopper 67, so that the leading edges of the sheets are aligned.

[0104] In S106, the binding process control unit 95 determines whether the final sheet has been conveyed to the leading edge regulating stopper 67 based on the specified number of sheets for post-processing. The process from S105 is repeated until it is determined that the final sheet has been conveyed to the leading edge regulating stopper 67. If it is determined that the final sheet has been conveyed to the leading edge regulating stopper 67, the process proceeds to S107.

[0105] In S107, the binding process control unit 95 moves the leading edge regulating stopper 67 to the lowest position after the specified number of sheets have been conveyed. In S108, the binding process control unit 95 aligns the sheets in the width direction. The alignment of the sheets here is performed by a side edge regulating member (not shown).

[0106] In S109, the binding process control unit 95 rotates the folding roller 64. In S110, the binding process control unit 95 advances the folding blade 65 in the folding direction. In S111, the binding process control unit 95 determines whether the rotation amount of the folding roller 64 has reached a predetermined amount. If it is determined that the rotation amount of the folding roller 64 has not reached the predetermined amount, the process of S111 is repeated. If it is determined that the rotation amount of the folding roller 64 has reached the predetermined amount, the process proceeds to S112. In S112, the binding process control unit 95 retracts the folding blade 65. In S113, the binding process control unit 95 conveys the folded sheet, which has undergone the above-described folding process, in the paper discharge direction by the downstream saddle portion paper discharge roller. As a result, the folded sheet is stored in the second tray 61 via the saddle discharge path 68.

[0107] The above describes an example in which folding is performed after the leading edge restricting stopper 67 is moved in S107, but this is not a limitation. Other post-processing may be performed after the leading edge restricting stopper 67 is moved and before folding. For example, binding may be performed. For example, based on receiving a job end signal from the image forming apparatus A, a binding unit (saddle stitching unit) (not shown) provided in the saddle section B2 may be moved to the center of the sheets to perform binding. In this case, binding is performed at one or two specified positions.

[0108] Image formation continues in the image forming apparatus A even while post-processing is being performed in the saddle section B2. Therefore, in this embodiment, a buffer operation is performed to accumulate sheets conveyed from the image forming apparatus A in the sheet processing apparatus B. This allows post-processing to continue without reducing the frequency at which sheets are discharged from the image forming apparatus A, i.e., without reducing the productivity of the image forming apparatus A.

[0109] An overview of the sheet buffer operation in sheet processing apparatus B executed in S103 will be described with reference to Figures 16A to 23. Figures 16A to 23 show cross-sectional views seen from the side of sheet processing apparatus B. Hereinafter, the first conveying roller 201, the second conveying roller 202, and the third conveying roller 203 will be referred to as shift rollers 201, shift rollers 202, and intermediate conveying rollers 203.

[0110] First, the buffer operation for a small-sized sheet having a length in the sheet conveying direction will be described. In this embodiment, the small size is defined as a size that fits within the path length of the straight path 28.

[0111] Fig. 16A shows how the processes of S109 to S112 in Fig. 15 are performed in saddle section B2 on sheet S0, which is previously present in sheet processing apparatus B. Fig. 16A also shows a state in which sheet S1, discharged from image forming apparatus A, has been transported through straight path entrance 26 to entrance rollers 29 and shift rollers 201, and at this time, the entrance sensor Se1 detects its leading edge. In the state shown in Fig. 16A, a lateral registration error for sheet S1, which will be described later, is detected. Fig. 16B shows a state in which the leading edge of sheet S1 has been transported further to a position beyond shift roller 202. At this time, a lateral registration adjustment for sheet S1, which will be described later, is performed.

[0112] 17A shows a state in which the leading edge of sheet S1 has been conveyed to a position beyond the discharge roller 36. FIG. 17B shows a state in which the upper flapper 33a has been moved to the buffer path guide position. This buffer path guide position is set to a position where the sheet can be sent to the saddle buffer path P2 based on the leading edge detection result by the inlet sensor Se1 and the sheet length information. Note that when the sheet reaches the discharge sensor Se2, the detection result of Se2 may be used instead or in combination.

[0113] FIG. 18A shows a state in which the lower flapper 33b has been moved to the buffer path guide position. The movement of the upper flapper 33a and the lower flapper 33b forms a path for conveying sheet S1 to the saddle buffer path P2. FIG. 18B shows a state in which sheet S1 has been retracted to the saddle buffer path P2. In this manner, in this embodiment, by retracting sheet S1 to the saddle buffer path P2, subsequent sheets discharged from the image forming apparatus A can be continuously received by the straight path 28. Also, in FIG. 18B, post-processing (folding) of sheet S0 is being performed. Here, "being performed" refers not only to the folding process, but also to the state in which the folding process itself has been completed but the sheet has not yet been discharged to the second tray 61.

[0114] 19A shows a state in which sheet S1 is further conveyed toward the fourth tray discharge outlet 305 of saddle buffer path P2. At this time, post-processing for sheet S0 is being performed. FIG. 19B shows a state in which the position of the lower flapper 33b has been moved. The movement of the lower flapper 33b allows the following sheet S2 to be received by the straight path 28.

[0115] FIG. 20A shows a state in which sheet S1 is positioned at a predetermined position in saddle buffer path P2. As shown in FIG. 20A, the entire length of the sheet in the conveying direction is retracted into saddle buffer path P2. This retracted position in saddle buffer path P2 is set based on the leading edge detection result by inlet sensor Se1 and paper length information. At this time, post-processing for sheet S0 is being performed. FIG. 20B shows a state in which sheet S2, subsequently discharged from image forming apparatus A, is conveyed to inlet rollers 29 and shift rollers 201 via straight path inlet 26. At this time, the leading edge of sheet S2 is detected by inlet sensor Se1. In the state shown in FIG. 20B, lateral registration error for sheet S2, which will be described later, is detected. At this time, sheet S1 positioned in saddle buffer path P2 is adjusted to match the lateral registration error of sheet S2. This operation will be described later. At this time, post-processing for sheet S0 is being performed.

[0116] FIG. 21A shows a state in which sheets S1 and S2 are transported in synchronization to the shift rollers 202. The synchronization of transport between the sheets is performed, for example, based on the detection result of the inlet sensor Se1, sheet length information, and sheet position information obtained by the drive pulses of the stepping motor. By driving the buffer roller 302 based on the detection result of the leading edge of sheet S2 by the inlet sensor Se1, sheet S1 is sent to the straight path 28 in alignment with the leading edge of sheet S2. At this time, post-processing for sheet S0 is being performed. FIG. 21B shows a state in which sheets S1 and S2 are transported in synchronization further to just before the intermediate transport rollers 203. At this time, lateral registration adjustment is performed to center sheets S1 and S2. This operation will be described later. At this time, post-processing for sheet S0 is being performed.

[0117] FIG. 22A shows a state in which sheets S1 and S2 are conveyed overlapping each other to the discharge roller 36. At this time, the trailing edges of sheets S1 and S2 have passed through the shift roller 201. Also, at this time, post-processing for sheet S0 is being performed. FIG. 22B shows a state in which the positions of the upper flapper 33a and the lower flapper 33b have been moved. The movement of the upper flapper 33a and the lower flapper 33b forms a path for conveying sheets S1 and S2 to the saddle portion B2. At this time, sheet S0 has been discharged to the second tray 61. FIG. 23 shows a state in which sheets S1 and S2 have been conveyed to the leading edge restriction stopper 67.

[0118] As described above, according to this embodiment, even if post-processing is being performed on a sheet in the saddle section B2, the sheet S1 can be retracted to the saddle buffer path P2, and the following sheet S2 can be received from the image forming apparatus A. This allows post-processing to be performed on the sheet without impairing the productivity of the image forming apparatus A. Furthermore, as a result of the leading edges of the sheets hitting the leading edge restriction stopper 67, the sheets S1 and S2 are stacked in order from the bottom up, maintaining the order of the multiple sheets. Furthermore, because the buffered sheets S1 and S2 are fed into the saddle section B2 in an aligned state, the stack of buffered sheets can be quickly retracted from the straight path 28, thereby speeding up the timing for receiving the next sheet. The buffered sheets S1 and S2 are relatively aligned when the misalignment in the conveying direction is within a predetermined range, for example, 0 mm to +10 mm or 0 mm to -10 mm. In this embodiment, the standard value is adjusted so that the leading sheet S1, which has entered the saddle buffer path P2, is positioned approximately 2.5 mm behind the trailing edge of the trailing sheet S2. This allows the right-side sheet S1 to contact the leading edge stopper 67 first when the stack of sheets S1 and S2 is fed into the saddle portion B2, making it easier to align the sheets. Furthermore, by controlling the trailing edge of sheet S1 to be positioned within a predetermined range behind sheet S2, even taking various tolerances into account, the timing for quickly retracting sheet S1 from the straight path 28 is ensured, allowing for faster acceptance of the next sheet and increased productivity.

[0119] By locating the entrance to the saddle path 32 and the position where the sheet overlapping is completed (the exit of the saddle buffer path P2) close to each other in the conveying direction, the conveying distance for retracting the sheet from the straight path 28 is shortened, improving productivity. Furthermore, the saddle buffer path flapper 33a and the saddle path flapper 33b that feed the sheet from the straight path 28 to each path can be used for both purposes. Also, by performing the operation of feeding the sheet into the saddle buffer path P2 two or more times, it is possible to buffer three or more sheets.

[0120] In some parts of Figures 16A to 23, it is described that lateral registration error detection and lateral registration adjustment are performed. Below, lateral registration error detection and lateral registration adjustment will be described with reference to Figures 24A to 33B. The upper parts of Figures 24A to 33B are simplified diagrams illustrating the configuration near the straight path 28 in Figures 16A to 23. The lower parts of Figures 24A to 33B are diagrams of the upper straight path 28 as viewed from above. The inlet rollers 29, shift rollers 201, shift rollers 202, intermediate conveyance rollers 203, and buffer rollers 302a and 302b in the lower parts of Figures 24A to 33B correspond to the inlet rollers 29, shift rollers 201, shift rollers 202, intermediate conveyance rollers 203, and buffer rollers 302a and 302b in the upper parts of Figures 24A to 33B. As shown in the upper parts, when viewed from above, the roller pairs arranged on the straight path 28 appear to overlap each other. On the other hand, the rollers arranged in the saddle buffer path P2 appear misaligned when viewed from above because the conveying path is curved, and this is shown.

[0121] 24A shows a state in which sheet S1 has been discharged from image forming apparatus A. At this time, the central axis of sheet S1 is not normally positioned at the center in the width direction, resulting in a state in which a lateral registration error has occurred. FIG. 24B shows a state in which sheet S1 has been conveyed up to just before shift roller 201. At this time, registration detection sensor 100 detects the lateral registration error of sheet S1.

[0122] Fig. 25A shows a state in which the registration detection sensor 100 has finished detecting the lateral registration error of the sheet S1. Fig. 25B shows a state in which the sheet S1 has been transported to a position beyond the shift roller 202. At this time, the nip of the inlet roller 29 is released. In other words, the sheet S1 is nipped between the shift rollers 201 and 202. The shift rollers 201 and 202 can be shifted by the transport roller shift mechanism described above.

[0123] In Fig. 26A, the shift rollers 201 and 202 perform lateral registration adjustment so that the central axis of the sheet S1 in the conveying direction is aligned with the center. This corresponds to the state in Fig. 16B. Fig. 26B shows a state in which the sheet S1 has been conveyed to a position beyond the intermediate conveying rollers 203. At this time, the inlet rollers 29 are in a nip state, and the sheet can receive the following sheet.

[0124] Fig. 27A is a diagram showing a state in which the shift roller 201 has been returned to its original position (receiving position). Fig. 27B is a diagram showing a state in which the sheet S1 has been reversely conveyed to the saddle buffer path P2 by the intermediate conveying rollers 203, the shift rollers 202, the buffer rollers 302a, and the buffer rollers 302b. That is, in the state shown in Fig. 27B, the intermediate conveying rollers 203 and the shift rollers 202 are controlled to perform reverse rotation. At this time, the upper flapper 33a and the lower flapper 33b are in the state in which they have moved as shown in Fig. 18A.

[0125] 28A is a diagram showing a state in which the shift roller 202 has been returned to its original position (receiving position). Fig. 28B shows a state in which sheet S2 is subsequently discharged from image forming apparatus A and conveyed to a position beyond shift roller 201. At this time, the central axis of sheet S2 is not positioned at the center in the width direction, and a lateral registration error has occurred.

[0126] 29A shows a state in which the registration detection sensor 100 detects the lateral registration error of the sheet S2. FIG. 29B shows a state in which the registration detection sensor 100 has finished detecting the lateral registration error of the sheet S2 and the sheet S2 has been further conveyed to just before the shift roller 202.

[0127] Figure 30A shows a state in which the shift operation of the buffer rollers 302a and 302b adjusts the lateral registration of the sheet S1 positioned in the saddle buffer path P2 to match the lateral registration error of the sheet S2. In other words, the first shift operation is performed on the sheet S1. This corresponds to the state shown in Figure 21A. The buffer rollers 302a and 302b can be shifted by the conveyance roller shift mechanism described above. Figure 30B shows a state in which the sheets S1 and S2 are conveyed synchronously to the downstream side of the straight path 28.

[0128] FIG. 31A shows a state in which sheets S1 and S2 are transported synchronously to a position beyond the shift roller 202. At this time, the nip of the inlet roller 29 is released. In other words, sheet S2 overlaps sheet S1 and is nipped by the shift roller 201 and the shift roller 2022. FIG. 31B shows a state in which lateral registration adjustment has been performed to center sheets S1 and S2 by the shift operation of the shift rollers 201 and 202 and buffer rollers 302a and 302b. This corresponds to the state in FIG. 21B. In other words, a second shift operation is performed on sheet S1.

[0129] 32A is a diagram showing a state in which the sheets S1 and S2 are conveyed overlapping each other to a position beyond the intermediate conveying roller 203. FIG. 32B is a diagram showing a state in which the shift roller 201 has been moved to its original position (receiving position). At this time, the upper flapper 33a and the lower flapper 33b have been moved to positions where the sheets can be guided to the saddle path 32, as shown in FIG. 22B.

[0130] Fig. 33A is a diagram showing a state in which the sheet S1 and the sheet S2 are superimposed and conveyed to the saddle path 32. Fig. 33B is a diagram showing a state in which the shift roller 202 has been moved to its original position (receiving position).

[0131] In this way, according to this embodiment, it is possible to adjust the registration error of each sheet discharged from the image forming apparatus A and continuously received by the straight path 28 .

[0132] 34A to 34D are flowcharts showing the processing of the sheet buffer operation executed in the sheet processing apparatus B. The processing of Fig. 34A to 34D is realized, for example, by the binding process control unit 95 reading out a program stored in the ROM 96 into the RAM 97 and executing it. Note that although the binding process control unit 95 in this embodiment is a single control unit, it may also be a combination of individual control units corresponding to the respective rollers, etc.

[0133] In S201, sheet S1 is discharged from image forming apparatus A. The processing of S201 is executed in image forming apparatus A. In S202, the binding process control unit 95 moves the sheet support to an operating position. The sheet support is a member for preventing the sheet conveyed on the straight path 28 from falling. In S203, the binding process control unit 95 detects that sheet S1 has reached the inlet rollers 29. In S204, the binding process control unit 95 detects a lateral registration error of sheet S1 using the registration detection sensor 100.

[0134] In S205, the binding process control unit 95 separates the inlet rollers 29 (releases the nip). This is because, in a subsequent stage, the shift rollers 201 and 202 shift to adjust the lateral registration of the sheet S1. In S206, the binding process control unit 95 starts the shift operation of the shift rollers 201 and 202. Here, the shift direction is a direction that eliminates the lateral registration error of the sheet S1. In S207, the binding process control unit 95 accelerates the sheet S1 and transports it downstream of the straight path 28. In S208, the binding process control unit 95 completes the shift operation of the shift rollers 201 and 202.

[0135] In S209, the binding process control unit 95 again brings the inlet rollers 29 into a nipping state. In S210, the binding process control unit 95 returns the shift rollers 201 to their original positions (receiving positions). This corresponds to the state shown in FIG. 27A.

[0136] In S211, the binding process control unit 95 starts moving the upper flapper 33a to the buffer path guide position, and in S212, starts moving the lower flapper 33b to the buffer path guide position. In S213, the binding process control unit 95 completes moving the upper flapper 33a to the buffer path guide position, and in S214, the binding process control unit 95 completes moving the lower flapper 33b to the buffer path guide position. This corresponds to the state in FIG. 18A.

[0137] In S215, the binding process control unit 95 stops the shift rollers 202 and the intermediate conveyance rollers 203. In S216, the binding process control unit 95 reverses the shift rollers 202 and the intermediate conveyance rollers 203 to convey the sheet S1 in the reverse direction. In S217, the binding process control unit 95 starts moving the lower flapper 33b to its original position (receiving position). In S218, the binding process control unit 95 retracts the sheet S1 to the buffer path P2. In S219, the binding process control unit 95 completes moving the lower flapper 33b to its original position. This corresponds to the state in FIG. 19B. In S220, the binding process control unit 95 moves the shift rollers 202 to its original position (receiving position). This corresponds to the state in FIG. 28A.

[0138] In S221, the sheet S2 is discharged from the image forming apparatus A. The process of S221 is executed in the image forming apparatus A.

[0139] In S222, the binding process control unit 95 detects the lateral registration error of the sheet S2 using the registration detection sensor 100. In S223, the binding process control unit 95 adjusts the lateral registration of the sheet S1 positioned in the saddle buffer path P2 by shifting the buffer rollers 302a and 302b so that the sheet S1 matches the lateral registration error of the sheet S2.

[0140] In S224, the binding process control unit 95 separates the inlet rollers 29 (releases the nip) in order to adjust the lateral registration of the sheets S1 and S2 in a subsequent stage by the shifting operations of the shift rollers 201 and 202 and the buffer rollers 302a and 302b.

[0141] In S225, the binding process control unit 95 conveys the sheets S1 and S2 to the shift roller 202 in a superimposed state.

[0142] In S226, the binding process control unit 95 performs registration adjustment to align the central axis of the sheet S1 with the center by shifting the buffer rollers 302a and 302b and the shift roller 202. On the other hand, in S227, the binding process control unit 95 performs registration adjustment to align the central axis of the sheet S2 with the center by shifting the shift rollers 201 and 202. The processing of S226 and the processing of S227 are performed simultaneously in parallel.

[0143] In S228, the binding process control unit 95 again brings the inlet rollers 29 into the nip state. In S229, the binding process control unit 95 returns the shift rollers 201 to their original positions (receiving positions). This corresponds to the state shown in FIG. 32B.

[0144] In S230, the binding process control unit 95 starts moving the lower flapper 33b to the saddle path guide position, and in S231 starts moving the upper flapper 33a to the saddle path guide position. In S232, the binding process control unit 95 completes moving the lower flapper 33b to the saddle path guide position, and in S233, completes moving the upper flapper 33a to the saddle path guide position. This corresponds to the state shown in FIG. 22B.

[0145] In S234, the binding process control unit 95 reversely rotates the intermediate conveying roller 203 and the shift roller 202 to convey the sheets S1 and S2 in a stacked state to the saddle path 32 in a reverse direction.

[0146] The overlapping operation of sheets S1 and S2 shown in Figures 20B to 21A will be described in detail. The leading edge of sheet S1 in the transport direction is positioned upstream of the nip point of the shift roller 202 in the transport direction. This is because if sheets S1 and S2 were to join at the nip point of the rollers that overlap and nip them or downstream of that point, sheet S1 would come into contact with sheet S2, hindering their transport and making it impossible for them to join. In particular, in bookbinding, when a paper type with a high basis weight (for example, a paper type with a basis weight of 256 g / m2) is used for the cover, ２), the paper used for the inner pages is often of a lower basis weight than the cover, and the basis weight generally used for the inner pages is 52 to 82 g / m ２ Thinner paper has weaker stiffness and is more likely to sag, making it more difficult to join the sheets together.

[0147] The sheet S1 is buffered in a saddle buffer path P2 so that the sheets S1 and S2 can be nipped by a pair of rollers after being superimposed, and a motor for driving a conveying roller and a motor for driving a buffer roller are adjusted so that the sheets S2 and S1 move at approximately the same speed, and the sheets S1 and S2 are made to merge.

[0148] Specifically, for example, using the detection results of the inlet sensor Se1 and other sheet position sensors (not shown), the sheet S1 is made to wait at a position where the leading edge of the sheet S1 is pulled into the saddle buffer path P2 by about 3 mm from the straight path 28, that is, at a position where the leading edge of the sheet S1 is not exposed in the straight path 28, and just before the leading edge of the sheet S2 reaches the shift roller 202, the sheet S1 is accelerated to the conveying speed of the sheet S2 and merged with the straight path 28. This makes it possible to prevent scratches caused by contact between the sheets and to allow the sheets S1 and S2 to merge smoothly.

[0149] In S235, the binding process control unit 95 moves the upper flapper 33a to its original position (receiving position), and in S236, the binding process control unit 95 moves the lower flapper 33b to its original position (receiving position).

[0150] In S237, the binding process control unit 95 performs saddle processing on sheets S1 and S2 that have been conveyed to the leading edge regulating stopper 67. This corresponds to the processing of S109 to S111 in FIG. 15. In S238, the binding process control unit 95 stores sheets S1 and S2 that have been subjected to saddle processing in the second tray 61 via the saddle discharge path 68 (discharge unit). Thereafter, the processing of FIGS. 34A to 34D ends.

[0151] The following describes the differences between the buffer operation for large-size sheets, which are longer in the sheet conveyance direction than small-size sheets, and the buffer operation for small-size sheets.

[0152] 35A to 35D are flowcharts showing the processing of the buffer operation for large-sized sheets executed in the sheet processing apparatus B. The processing in Figures 35A to 35D is realized, for example, by the binding processing control unit 95 reading a program stored in the ROM 96 into the RAM 97 and executing it. The processing in Figures 35A to 35D differs from that in Figures 34A to 34D in that the processing in S303, S307, S311, S324, and S331 is performed. The processes of S301, S302, S304 to S306, S308 to S310, S312 to S323, S325 to S330, and S332 to S341 are the same as those described in S201, S202, S203 to S205, S206 to S208, S210 to S221, S222 to S227, and S229 to S238, and therefore their description will be omitted.

[0153] In S303, the binding process control unit 95 moves the upper conveying path flapper 34 to the upper conveying path guide position. This creates a path for guiding sheets conveyed on the straight path 28 to the upper conveying path 30. When the trailing edge of a small-sized sheet passes through the shift rollers 202, its leading edge is positioned near the discharge rollers 36. However, when the trailing edge of a large-sized sheet passes through the shift rollers 202, its leading edge may protrude outside the device. This can cause the sheet to become twisted or damaged. Therefore, in this embodiment, for large-sized sheets, the above-mentioned twisting or damage to the sheet can be prevented by conveying the large-sized sheet on the upper conveying path 30 as shown in Figures 36A to 39B. Note that the states in Figures 36A and 36B correspond to the states in Figures 17A and 17B for small-sized sheets. The state in Figure 37 corresponds to the state in Figure 18A for small-sized sheets. The states in Figures 38A and 38B correspond to the states in Figures 22A and 22B for small-sized sheets. 39A and 39B correspond to the states in Figures 32A and 32B for small-sized sheets. In the buffer operation for large-sized sheets, the position of the sheet may be detected using the detection result of a sensor (not shown) provided in the upper conveying path 30 for detecting the position of the sheet, or the inlet sensor Se1 may be used in combination.

[0154] In S307 and S324, the binding process control unit 95 separates the intermediate conveying rollers 203 and the upper conveying rollers 303. This allows the shift rollers 201 and 202 to perform registration adjustment for large-sized sheets.

[0155] In S311 and S331, the binding process control unit 95 again brings the intermediate conveying roller 203 and the upper conveying roller 303 into a nip state, thereby enabling conveyance of large-sized sheets.

[0156] The straight path described in this embodiment does not have to be a completely straight line, and is a sheet having a basis weight of 500 g / m ２ It is sufficient that the sheet is not damaged even when coated paper exceeding 1,750 mm / sec is conveyed at 1,750 mm / sec. Specifically, it is preferable that the curvature of the path is set to a gentle curvature not less than 100R (radius 100 mm). Furthermore, each conveying roller pair will protrude from the path surface, and the amount of this protrusion is preferably about 1 mm to 2 mm from the lower surface of the path. ２ Coated paper exceeding this limit is so-called cardboard, a type of paper used for paper packages, magazine covers, etc.

[0157] As described above, according to this embodiment, sheets continuously supplied from the image forming apparatus A can be buffered, overlapped, and then sent to the saddle stitching and center folding processing section.

[0158] Note that, in another embodiment described below, it is also possible to buffer sheets to be sent to the saddle portion B2. The other embodiment will be described with reference to Figures 40 and 41. Figure 40 shows a state in which the first sheet (preceding sheet SA) and the second sheet (subsequent sheet SB) of the next sheet bundle are buffered until the saddle processing of the preceding sheet bundle is completed.

[0159] The preceding sheet SA is sent to the upper conveying path 30, and is stopped and retained once the trailing edge of the preceding sheet retracts from the straight path 28. Next, the succeeding sheet SB is sent toward the straight path paper discharge outlet 35, and is switched back and conveyed when the trailing edge of the succeeding sheet SB in the conveying direction passes the branching portion to the upper conveying path 30 (the flappers 34a and 34b of the upper conveying path flapper 34).

[0160] As the switchback transport of the succeeding sheet SB begins, the preceding sheet SA also begins transport toward the straight path 28. Figure 41 shows a state in which the succeeding sheet SB and the preceding sheet SA are aligned. After alignment, the sheet bundle is placed into the saddle path 32.

[0161] Even with the operation of the other embodiment as described above, up to two saddle buffers can be used.

[0162] 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.

[0163] This application claims priority based on Japanese Patent Application No. 2023-142449, filed September 1, 2023, the entire contents of which are incorporated herein by reference.

[0164] 28 Straight path: 201 Inlet roller: 202, 203 Shift roller: 203 Intermediate conveying roller: 33a Upper flapper (first flapper): 33b Lower flapper (second flapper)

Claims

1. A bookbinding processing device comprising: a transport path for transporting sheets from an entrance to an exit; bookbinding processing means provided below the transport path for performing bookbinding processing including binding and folding on a stack of sheets; a bookbinding processing path for transporting sheets from the transport path to the bookbinding processing means; transport means provided on the transport path for transporting sheets; detection means for detecting that a sheet transported by the transport means has reached a predetermined position; a buffer path provided above the transport path for buffering sheets; buffer transport means provided on the buffer path for transporting sheets; transport control means for controlling the transport means to feed a preceding sheet transported along the transport path into the buffer path; and buffer transport control means for controlling the buffer transport means to transport the preceding sheet from the buffer path to the transport path based on the detection result of a subsequent sheet following the preceding sheet by the detection means, wherein the transport control means controls the transport means to feed the stack of the preceding sheet and the subsequent sheet into the bookbinding processing path.

2. A binding processing device as described in claim 1, wherein the buffer path is configured so that the preceding sheet moves and is fed in a direction from the discharge exit to the feed entrance, the binding processing path is configured so that the bundle of the preceding sheet and the succeeding sheet moves and is fed in a direction from the discharge exit to the feed entrance, and the buffer path and the binding processing path are arranged so that at least a portion of them face each other across the conveying path.

3. The binding processing device according to claim 1, wherein the conveying means is provided with a pair of rollers capable of rotating forward and reverse, the buffer path is arranged to feed the preceding sheet conveyed from the entrance to the exit by reversing the roller pair, and the binding processing path is arranged to feed the bundle of the succeeding sheet and the preceding sheet conveyed from the entrance to the exit by reversing the roller pair, and the entrance of the buffer path and the entrance of the binding processing path are positioned upstream of the roller pair in the direction from the entrance to the exit.

4. The bookbinding processing device according to claim 2 or 3, wherein the bookbinding processing means comprises a stopper for stopping the lower end of the sheet stack sent along the bookbinding processing path, and a support means for supporting the sheet stack stopped by the stopper, the support means being positioned so that its lower end is located downstream in the direction from the entrance to the exit, and the buffer transport control means controls the buffer transport means so that, when aligning the leading sheet and the trailing sheet, the rear end of the leading sheet is located upstream of the rear end of the trailing sheet in the direction from the entrance to the exit.

5. A bookbinding processing device as described in claim 1, further comprising a position detection means for detecting the position of a sheet, and the buffer transport control means controls the buffer transport means based on the detection result by the position detection means so that the leading edge of the preceding sheet being transported to the buffer path is buffered at a position a predetermined distance away from the transport path.

6. A printing apparatus comprising: an image forming means for forming an image on a sheet; a transport path for transporting the sheet on which the image has been formed by the image forming means from the image forming means to an outlet; bookbinding processing means provided below the transport path for performing bookbinding processing including binding and folding on a sheet stack; a bookbinding processing path for transporting the sheet from the transport path to the bookbinding processing means; transport means provided on the transport path for transporting the sheet; detection means for detecting that the sheet transported by the transport means has reached a predetermined position; a buffer path provided above the transport path for buffering the sheet; buffer transport means provided on the buffer path for transporting the sheet; transport control means for controlling the transport means to send a preceding sheet transported along the transport path into the buffer path; and buffer transport control means for controlling the buffer transport means to transport the preceding sheet from the buffer path to the transport path based on a detection result of a subsequent sheet following the preceding sheet by the detection means, The image forming system includes a conveying control means for controlling the conveying means so as to feed the bundle of the preceding sheet and the succeeding sheet into the bookbinding process path.

Images