Post-processing device

Abstract

To provide a post-processing device that can prevent productivity from declining in performing a punching process to a sheet supplied from an image forming device.SOLUTION: When a receiving part receives a second sheet after a first sheet received by the receiving part is retreated to a second retreating path, the first sheet that is conveyed by a third conveying roller from the second retreating path and the second sheet received by the receiving part are conveyed while overlapping with each other. Subsequently, the second sheet is conveyed in an opposite direction of the conveying direction to be conveyed to a punch unit, so as to be subjected to a punching process. When the second sheet is conveyed to the punch unit, the first sheet is controlled so that the sheet is conveyed in synchronization with the second sheet.SELECTED DRAWING: Figure 15

Description

Technical Field

[0001] The present invention relates to a post-processing device capable of performing post-processing on an image-formed sheet.

Background Art

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

[0003] Patent Document 1 describes a sheet stacking device capable of preventing misalignment when aligning a plurality of sheets stacked on a stacking tray.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] There is a demand for improving productivity when performing a punching process on a sheet supplied from an image forming apparatus.

[0006] An object of the present invention is to provide a post-processing device that prevents a decrease in the quality of the product when performing a punching process on a sheet supplied from an image forming apparatus.

Means for Solving the Problems

[0007] The post-processing device according to the present invention includes a receiving unit that receives a sheet, a first conveying roller that conveys the sheet received by the receiving unit, a first guide unit that forms a conveying path together with the first conveying roller and is configured to be able to switch the conveying path of the sheet, a second guide unit located downstream of the first guide unit, a post-processing unit located downstream of the second guide unit and performing post-processing on the sheet bundle conveyed through the conveying path, a first retracting path provided on one side with respect to the conveying path and receiving the sheet conveyed by the first conveying roller through the first guide unit and the second guide unit to retract the sheet when there is a sheet bundle ahead of the post-processing unit, a second conveying roller provided on the first retracting path and holding the sheet conveyed to the first retracting path and conveying the sheet along the first retracting path, a second retracting path provided on the other side with respect to the conveying path and receiving the sheet reversely conveyed by the second conveying roller through the second guide unit and the first guide unit to retract the sheet, a third conveying roller provided on the second retracting path and holding the sheet conveyed to the second retracting path and conveying the sheet along the second retracting path, and a punch unit located upstream of the first retracting path and the second retracting path and performing a punching process on the sheet received by the receiving unit. After the first sheet received by the receiving unit is retracted to the second retracting path, when the receiving unit receives a second sheet, the first sheet conveyed from the second retracting path by the third conveying roller and the second sheet received by the receiving unit are conveyed overlapping each other, and then the second sheet is conveyed in the direction opposite to the conveying direction to be conveyed to the punch unit for the punching process. When the second sheet is conveyed to the punch unit, the first sheet is controlled to be conveyed in synchronization with the second sheet.

Advantages of the Invention

[0008] According to the present invention, it is possible to prevent a decrease in the quality of the product when performing post-processing on the sheet supplied from the image forming apparatus.

Brief Description of the Drawings

[0009]

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Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential for the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are given the same reference numerals, and duplicate explanations are omitted.

[0011] [Image Forming Apparatus] The image forming apparatus A in the image forming system shown in FIG. 1 will be described. The illustrated image forming apparatus A shows an electrostatic printing mechanism and includes 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 mounting on an installation surface (for example, a floor surface). Further, inside the apparatus housing 1, a paper feeding unit 2, an image forming unit 3, a paper discharging unit 4, and a data processing unit 5 are incorporated.

[0012] The sheet feeding unit 2 is configured to include cassette mechanisms 2a to 2c that store sheets of a plurality of sizes for image formation, and feeds out the sheets of the size designated by the main body control unit 90 to the sheet feeding path 6. For this purpose, a plurality of cassettes 2a to 2c are detachably arranged in the apparatus housing 1, and each cassette incorporates a separating mechanism for separating the internal sheets one by one and a sheet feeding mechanism for feeding out the sheets. In the sheet feeding path 6, a conveying roller 7 for feeding the sheets supplied from the plurality of cassettes 2a to 2c to the downstream side is provided, and at the end of the path, a registration roller pair 8 for aligning the leading edges of the sheets is provided.

[0013] In addition, a large-capacity cassette 2d and a manual feed tray 2e are connected to the sheet feeding path 6. The large-capacity cassette 2d is configured to include an option unit that stores sheets of a size that is consumed in large quantities, and the manual feed tray 2e is configured to be able to supply special sheets such as thick paper sheets, coated sheets, and film sheets for which separation and feeding are difficult.

[0014] The image forming unit 3 is shown as an example of an electrophotographic printing mechanism, and a photoreceptor 9 (drum, belt), a light emitter 10 that emits an optical beam to the photoreceptor 9, a developing device 11 (developer), and a cleaner (not shown) are arranged around the rotating photoreceptor. The illustrated one shows a monochrome printing mechanism. An electrostatic latent image is optically formed on the photosensitive drum 9 by the light emitter 10, and toner ink is adhered to the latent image by the developing device 11. Then, in accordance with the timing of image formation on the photoreceptor 9, the sheet is sent from the sheet feeding path 6 to the image forming unit 3, the image is transferred onto the sheet by the transfer charger 12, and fixed by a fixing unit (roller) 13 arranged in the paper discharge path 14. In the paper discharge path 14, a paper discharge roller 15 and a paper discharge port 16 are arranged, and the sheet is conveyed to a sheet post-processing device B described later.

[0015] Scanner unit A2 includes a platen 17 for placing an image document, a carriage 18 that reciprocates 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 the reflected light from the document on the platen 17 to a photoelectric conversion unit 19. Illustration 21 is a second platen (traveling platen), and an image is read from the sheet sent from the feeder unit A3 by the carriage 18 and the reduction optical system 20. The photoelectric conversion unit 19 transfers the image data after photoelectric conversion to the image forming unit 3.

[0016] Feeder unit A3 includes a paper feed tray 22, a paper feed path 23 that guides the sheet sent out from the paper feed tray to the traveling platen 21, and a paper discharge tray 24 that stores the document for which image reading has been performed on the platen.

[0017] The image forming apparatus A is not limited to the above mechanism, and printing mechanisms such as an offset printing mechanism, an inkjet printing mechanism, and an ink ribbon transfer printing mechanism (thermal transfer ribbon printing, sublimation type ribbon printing, etc.) can be adopted.

[0018] [Sheet Post-processing Apparatus] Sheet post-processing apparatus B is an apparatus that post-processes the sheets discharged from the paper discharge port 16 of the image forming apparatus A. For example, (1) a function of stacking and storing the imaged sheets (printout mode), (2) a function of sorting and storing the imaged sheets (jogging sorting mode), (3) a function of binding the imaged sheets after aligning and integrating them (binding process mode), and (4) a function of folding and finishing the bound book after aligning and binding the imaged sheets (bookbinding process mode).

[0019] Note that in this embodiment, the sheet post-processing apparatus B does not necessarily have all of the above functions, and is appropriately configured according to the apparatus specifications (design specifications). In this embodiment, as an example, it is assumed to have a function of folding and finishing the bound book after aligning and binding the imaged sheets.

[0020] FIG. 2 shows the configuration of the sheet post-processing apparatus B, and FIG. 3 shows the configuration around the straight path 28. The sheet post-processing apparatus B processes a sheet carried in from a straight path inlet 26 connected to the paper discharge port 16 of the image forming apparatus A, and then stores it in a storage unit (the first stack tray 49, the second stack tray 61, and the third stack tray 71, which will be described later). In the illustrated apparatus, the sheet sent to the straight path 28 is transferred from the processing unit B1 including the 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"). Further, the sheet sent to the straight path 28 is transferred from the saddle unit B2 to the second stack tray 61 (hereinafter referred to as the "second tray"). Note that since the straight path 28 is formed in a substantially straight line, it can convey thick paper and the like.

[0021] The processing unit B1 is disposed at the path outlet (straight path paper discharge port 35) of the straight path 28. After sorting and stacking the sequentially sent sheets and performing a binding process, the sheets are stored in the first tray 49. The saddle unit B2 is disposed at the path outlet (saddle path paper discharge port) of the saddle path 32 branched from the straight path 28. It is a post-processing unit that sorts and stacks the sequentially sent sheets, performs a saddle stitch (it may not perform a saddle stitch), performs a folding process, and then stores the sheets in the second tray 61. Hereinafter, each configuration will be described in detail.

[0022] <Apparatus housing> As shown in FIG. 2, the sheet post-processing apparatus B includes an apparatus housing 27, a straight path 28 built inside the apparatus housing and having a straight path inlet 26 and a straight path paper discharge port 35, a processing unit B1 and a saddle unit B2 that post-process the sheet sent from the straight path 28, and the first stack tray 49, the second stack tray 61, and the third stack tray 71 that store the sheets sent from each post-processing unit. The illustrated apparatus housing 27 is disposed at substantially the same height as the housing 1 of the image forming apparatus A located on the upstream side, and the paper discharge port 16 of the image forming apparatus A and the straight path inlet 26 of the sheet post-processing apparatus B are connected on the installation surface.

[0023] The housing 27 of the sheet post-processing device is configured to include the device frame 70. The device frame 70 forms the framework of a box-type device as shown in FIG. 6, for example, and includes a front-side side frame frame 70f located in the front in the state of FIG. 1, a rear-side side frame frame 70r located in the rear, and a stay member (connection reinforcing member) that connects between both side frame frames. A straight path 28, a processing unit B1, a saddle unit B2, etc., which will be described later, are attached between the left and right side frame frames. The device housing 27 is not limited to the illustrated shape and can be in a form suitable for design. Needless to say, the device frame 70 is not limited to the connection stay structure between the left and right side frames, and various frame structures such as a monocoque structure can be adopted.

[0024] <Sheet loading path> As shown in FIG. 3, the straight path 28 is configured as a substantially straight path that traverses the apparatus housing 27 in a substantially horizontal direction, and includes a straight path inlet 26 that is continuous with the paper discharge port (main body paper discharge port) 16 of the image forming apparatus A, and a straight path paper discharge port 35 that is located on the opposite side across the apparatus from this inlet (straight path inlet 26). In the straight path 28, a conveying mechanism capable of conveying a sheet from the straight path inlet 26 toward the straight path paper discharge port 35 and also capable of conveying from the straight path paper discharge port 35 toward the straight path inlet 26 is provided. In order from the straight path inlet 26 side, an inlet roller 29, a first conveying roller 201, a second conveying roller 202, and a third conveying roller 203 are arranged. Also, at the straight path paper discharge port 35, a paper discharge roller 36 (including a sheet conveying mechanism such as a belt) is arranged as a conveying mechanism. Further, in the vicinity of the straight path inlet 26, an inlet sensor S1 for detecting the leading and trailing edges of the received sheet and a lateral registration detection sensor S0 (detection unit) for detecting the end face position (side edge) parallel to the sheet conveying direction are arranged. Also, in the vicinity of the straight path paper discharge port 35, a paper discharge sensor S2 for detecting the leading and trailing edges of the sheet is arranged. The sheet discharged from the straight path paper discharge port 35 is discharged to the first tray 49 via the first paper discharge path 31 connected to the straight path paper discharge port 35, or is guided to the processing unit B1. Further, a punch unit 100 for punching a punch hole in the sheet is arranged in the straight path 28.

[0025] <Layout of the sheet loading path> In the straight path 28, as shown in FIGS. 2 and 3, the "saddle path 32", "saddle buffer path P2", "processing unit buffer path P1", and "upper conveyance path 30" are arranged in this order from the straight path inlet 26 toward the straight path paper discharge port 35. At the branch portion with each of the above paths, a saddle path flapper 33b, a saddle buffer path flapper 33a, a processing unit buffer path flapper 200, and an upper conveyance path flapper 34 are arranged as a conveyance switching mechanism (branch mechanism) for the conveyed sheet. In the present embodiment, the saddle buffer path P2 and the upper conveyance path 30 are configured as a retraction path for retracting the sheet. Further, as shown in FIG. 2, a saddle portion B2 is provided on one side across the straight path 28, and the saddle buffer path P2 and the upper conveyance path 30 are provided on the opposite side (the other side). Thereby, the conveyance efficiency of the sheet located in the retraction path to the saddle portion B2 can be further improved.

[0026] Among the above paths, the saddle path 32, the saddle buffer path P2, and the processing unit buffer path P1 are configured as a switchback path for conveying the sheet in a direction opposite to the conveying direction from the straight path inlet 26 to the straight path paper discharge port 35 and loading it into each of the above paths. Further, the upper conveyance path 30 is configured to be loaded by conveying the sheet in the same direction as the conveying direction from the straight path inlet 26 to the straight path paper discharge port 35.

[0027] <Path Branching Mechanism> The saddle path flapper 33b, saddle buffer path flapper 33a, and processing unit buffer path flapper 200, which are the above-described sheet branching mechanisms, are each composed of a flapper guide that is movable so as to be able to switch the conveyance path of the sheet carried in from the straight path inlet 26, and are connected to a drive mechanism (not shown) such as an electromagnetic solenoid or a mini motor. The above-described saddle path flapper 33b guides the sheet sent from the straight path inlet 26 to the saddle path 32. The saddle buffer flapper 33a guides the sheet sent from the straight path inlet 26 to the saddle buffer path P2. The processing unit buffer flapper 200 guides the sheet sent from the straight path inlet 26 to the processing unit buffer path P1 via the processing unit buffer rollers 301a and 301b. The upper conveyance path flapper 34 includes a flapper guide that is movable so as to switch the conveyance path so as to convey the sheet sent from the straight path inlet 26 to either the straight path discharge port 35 or the upper conveyance path 30, and is connected to a drive mechanism (not shown) such as an electromagnetic solenoid or a mini motor.

[0028] <Upper conveyance path> Connected to the straight path 28 is an upper conveyance path 30 (printout discharge path) that conveys sheets other than those discharged to the straight path discharge port 35. At the path branching portion, there is provided an upper conveyance path flapper 34 for guiding the sheet to the upper conveyance path 30. Further, the upper conveyance path 30 is provided with upper conveyance rollers 303 (303a, 303b) for guiding the sheet to the third tray 71. By these components, the sheet guided to the upper conveyance path 30 is discharged from the upper conveyance path discharge port 40 to the third tray 71 (overflow tray). In this embodiment, the upper conveyance path 30 is also used as a sheet storage path.

[0029] <Saddle path> The straight path 28 is connected to a saddle path 32 for carrying the sheet into the saddle section B2, and the path branching section is provided with a saddle path flapper 33b for guiding the sheet to the saddle path 32. The sheet guided from the saddle path 32 to the saddle section B2 via the saddle path discharge port is subjected to intermediate binding and folding processes, and then discharged to the second tray 61 via the substantially horizontal saddle discharge path 68.

[0030] <Saddle buffer path> The straight path 28 is connected to a saddle buffer path P2 for temporarily carrying and waiting the sheets to be subjected to intermediate binding and folding processes in the saddle section B2, and a saddle buffer path flapper 33a is configured to guide the sheet to the saddle buffer path P2. Further, the saddle buffer path P2 is provided with conveying rollers 302 (302a, 302b) for carrying the sheet and temporarily waiting.

[0031] A fourth tray discharge port 305 is provided on the downstream extension of the saddle buffer path P2. Therefore, the sheet carried into the saddle buffer path P2 can be discharged and stacked onto the fourth tray 310. In this case, the fourth tray 310 is disposed vertically above the saddle buffer path P2. Note that the fourth tray 310 may be shared with the exterior component on the top surface of the saddle post-processing device B, may be fixed to the device housing, or may be configured to be vertically movable in a substantially vertical direction with a drive mechanism.

[0032] In addition, the device can be made more compact by arranging the saddle buffer path P2 at a position overlapping vertically above the punch unit 100. However, when a space for bouncing the punch unit 100 upward is required to remove the sheet staying in the punch unit 100, the saddle buffer path P2 may be arranged at a position not overlapping vertically above the punch unit 100.

[0033] <Conveying roller shift mechanism in the loading path> Here, the conveyance shift mechanism provided in the conveyance roller on the above-described conveyance path will be described with reference to FIGS. 6 and 7. The first conveyance roller 201, the second conveyance roller 202, the third conveyance roller 203, and the conveyance rollers 302a and 302b are each configured to include a drive roller 111 and a driven roller 112 that are rotatably supported by bearing on the left and right side frame frames 70f and 70r. A drive rotation shaft is connected to the drive roller shaft 113 by a transmission mechanism 116 (the one shown in the figure is a gear transmission), and a drive motor (not shown) common to the paper discharge roller 36 is connected to the drive rotation shaft 115. Further, the driven roller shaft 114 is supported by bearing on the left and right side frame frames 70f and 70r so as to be freely movable.

[0034] Each of the above-described conveyance rollers is rotatably attached to a shift member 117 that connects the drive roller shaft 113 and the driven roller shaft 114. By the shift member 117, the drive roller shaft 113 and the driven roller shaft 114 are connected so as to move integrally in the axial direction (thrust direction), and are rotatable independently in the radial direction. The drive roller shaft 113 is supported by bearing on the left and right side frame frames 70f and 70r, and the end of the drive roller shaft 113 is located within the range indicated by the axial movement region of the conveyance roller on the front side of the side frame frame 70f, and the other end is located on the rear side of the side frame frame 70r. The shift member 117 (for example, a block member made of synthetic resin) is supported by the drive roller shaft 113 and the driven roller shaft 114, and integrally connects both roller shafts.

[0035] A rack 117a is integrally formed on the shift member 117 and meshes with a shift motor M9 attached to the side frame frame 70r (apparatus frame; the same applies hereinafter) and a transmission pinion 117b. With such a configuration, it becomes possible to move the shift member 117 in the axial direction of the conveyance roller (shift movement) by the rotation of the shift motor M9 (the one shown in the figure is a stepper motor capable of forward and reverse rotation).

[0036] A driven gear 118 is integrally formed on the drive rotating shaft 115, and the rotation of the drive motor is transmitted to the driven gear 118. Further, the driven rotating shaft 119 is configured such that the conveying roller pair (drive roller and driven roller) is pressed into contact so as to rotate passively with the rotation of the drive rotating shaft 115.

[0037] In the present embodiment, the drive rotating shaft 115 and the driven rotating shaft 119 are connected to each other and configured such that one of them is driven to move axially and the other follows. Alternatively, one of the drive roller 111 and the driven roller 112 may be attached to the rotating shaft so as to be slidable (sliding) axially, and the other roller may be moved axially and configured to be interlocked with the movement.

[0038] <Conveying shift operation> Here, the shift operation (jog sorting mode) of the sheet carried into the sheet post-processing apparatus B will be described. The sheet fed from the image forming apparatus A is conveyed in the order of the straight path inlet 26, the inlet roller 29, the first conveying roller 201, the second conveying roller 202, and the third conveying roller 203. At this time, the delivery timing of the sheet is also detected by the inlet sensor S1 simultaneously. The sheet carried in by the inlet roller 29 is detected by the lateral registration detection sensor S0 for the end position of the sheet while passing through the straight path 28. The lateral registration detection sensor S0 detects how much the lateral registration error X of the sheet has occurred with respect to the center (central) position.

[0039] When the lateral registration error X by the lateral registration detection sensor S0 is detected, a shift operation of the sheet (also referred to as "lateral registration detection process") is performed in which each of the first conveying roller 201, the second conveying roller 202, and the third conveying roller 203 moves a predetermined amount in the front and back directions while conveying in order. Thereafter, the sheet is diverted by the upper conveying path flapper 34 of the branching mechanism to the straight path discharge port 35 or the upper conveying path 30 and conveyed, and discharged onto the first tray 49 or the second tray 71.

[0040] <Processing unit> The processing unit B1 is a post-processing unit configured to include a processing tray 37 that is disposed downstream of the straight path 28 and aligns and stacks the sheets sent from the straight path paper discharge port 35, and a binding mechanism that binds the stacked sheet bundle. As shown in FIG. 3, a step is formed at the straight path paper discharge port 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 port 35 and the processing tray 37 to reverse the conveyance direction from the paper discharge port and guide the sheet onto the tray.

[0041] A sheet loading mechanism for loading the sheet from the paper discharge port onto the tray is disposed between the straight path paper discharge port 35 and the processing tray 37. The processing tray 37 is provided with a positioning mechanism for positioning the sheet at a predetermined binding position and a sheet bundle unloading mechanism for discharging the bound sheet bundle to the downstream first tray 49. Each configuration will be described later.

[0042] Note that the processing tray 37 shown in FIG. 3 supports the sheet sent from the straight path paper discharge port 35 in a bridging manner between the downstream first tray 49. That is, the sheet sent from the straight path paper discharge port is configured to be supported in a bridging manner with its front end on the uppermost sheet of the downstream first tray 49 and its rear end on the processing tray 37.

[0043] <Saddle part> The saddle part B2 is a post-processing unit that aligns and stacks the sheets sent from the straight path 28, and performs binding processing on the central part and inner folding processing (hereinafter referred to as "magazine finishing"). A second tray 61 is disposed downstream of the saddle part B2 to store the bound sheet bundle. It should be noted that one sheet or a plurality of sheets may be aligned and stacked, and only inner folding processing may be performed on the central part without performing middle binding processing.

[0044] The saddle portion B2 includes a guide member 66 that stacks the sheets in a bundle, a tip restricting stopper 67 that positions the sheet at a predetermined position on the guide member 66, a stapling device 63 (center stapling unit) that binds the central portion of the sheet positioned by the tip restricting stopper 67, and a folding mechanism (folding roll pair 64 and folding blade 65) that folds the sheet bundle at the central portion after the binding process.

[0045] The center stapling unit 63 employs a mechanism that is generally known, in which the sheet bundle is sandwiched between a head unit and an anvil unit and is moved along the central portion (line) of the sheet for stapling. Further, as shown in FIG. 2, the folding mechanism is configured such that the folding line of the sheet bundle is inserted into the mutually pressed folding roll pair 64 by the folding blade 65 and is folded by the rolling of the roll pair.

[0046] The illustrated processing unit B1 and the straight path 28 are arranged in a substantially horizontal direction, the saddle path 32 that guides the sheet to the saddle portion B2 is arranged in the vertical direction, and the guide member 66 that aligns and stacks the sheets is arranged in a substantially vertical direction. By arranging the straight path 28 in the direction crossing the apparatus housing 27 and arranging the saddle path 32 and the saddle portion B2 in the vertical direction, the apparatus can be made slimmer.

[0047] A second tray 61 is arranged on the downstream side of the saddle portion B2 and can store the sheet bundle folded in a magazine shape. The second tray 61 is arranged below the first tray 49. This is because it is assumed that the usage frequency of the first tray 49 is higher than that of the second tray 61, and the position of the first tray 49 is set to a height at which it is easy to take out the sheets on the tray.

[0048] <Punch unit> With reference to FIG. 5, a punch unit 100 disposed on a straight path 28 and punching punch holes in a sheet fed from a straight path inlet 26 will be described. The punch unit 100 arranges a plurality of punch members 101a to 101e at predetermined intervals in a direction orthogonal to the sheet conveyance direction of the straight path 28, and punches a selected number of holes in the sheet.

[0049] FIG. 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 vertically movably on the unit frame 102, a drive cam that reciprocates each punch member vertically (reciprocates in the punching direction), and a drive motor M7 that drives this drive cam.

[0050] Reference numeral 104 in the figure is a waste box, which is disposed below the punch member 101 and stores punched waste paper pieces. The waste box 104 is slidably attached to a guide rail (not shown) on a device frame 70 (different from the unit frame). Reference numeral 106 in the figure is a rotation operation member, which forcibly rotates the drive cam when a jam occurs in the punch member 101 or when an abnormality occurs in the drive motor M7, and separates (peels off) the punch member 101 that has bitten into the sheet. For this reason, the rotation operation member 106 is constituted by a manual rotation knob connected to the rotation shaft 107 of the drive cam.

[0051] As shown in FIG. 5, the unit frame 102 includes an upper frame 102a having a predetermined length in a direction orthogonal 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 at predetermined intervals in a direction orthogonal to the sheet conveyance direction (hereinafter referred to as the "conveyance orthogonal direction") on the upper frame 102a so as to be reciprocally movable (vertically movable) in the punching direction. Punching holes (dies) are formed in the lower frame 102b at positions facing each punch portion 101. Further, a drive rotation shaft 107 is disposed on the unit frame 102, and a drive cam for moving each punch member 101 up and down is attached to the drive rotation shaft 107. A drive motor M7 is connected to the drive rotation shaft 107 via a transmission mechanism.

[0052] The drive cam is composed of a cylindrical cam member axially attached to the drive rotating shaft 107 and corresponding to a plurality of punch members 101, and each punch member is connected to this cam member by a connecting pin. Then, due to the rotation of the drive rotating shaft 107 by a predetermined angle, the punch member 101 moves up and down in the punching direction. At this time, the first group 101b, 101d of the plurality of punch members (for example, two-hole punching) moves up and down in the punching direction at the first rotation angle of the drive rotating shaft 107, and the second group 101a, 101c, 101e (for example, three-hole punching) moves up and down in the punching direction at a different second rotation angle.

[0053] Therefore, when the binding process control unit 95 described later reciprocally rotates the drive rotating shaft 107 within a preset angle range by controlling the motor M7, the punch members 101b, 101d of the first group can be made to perform a punching motion, and when reciprocally moved within a different angle range, the punch members 101a, 101c, 101e of the second group can be made to perform a punching motion.

[0054] The waste box 104 is disposed below the punch member 101, supported by a guide rail (not shown) provided on the apparatus frame, and is detachable from the front side of the apparatus.

[0055] Also, a drive motor M7 is connected to the drive rotating shaft 107 via a speed reduction mechanism (gear transmission mechanism), and a rotating member is passed through a hole provided in the side frame 70f so that an operator can manually rotate it, and is disposed on the front side of the side frame 70f. And on the front side of the apparatus, a front cover is disposed so as to be openable and closable, and the rotation operation member 106 can be operated in the open cover state. Note that when the cover is in the open state, the drive power is not supplied (cut off) to the drive motor M7.

[0056] [Configuration of the processing unit] Next, the configurations of the sheet loading mechanism, sheet positioning mechanism, binding processing mechanism, and sheet bundle unloading mechanism of the processing unit B1 will be described.

[0057] <Sheet Loading Mechanism> As shown in Fig. 3, between the straight path paper discharge port 35 and the processing tray 37, there are arranged a reverse transfer mechanism for switchback transporting the sheet from the straight path paper discharge port 35 in the paper discharge direction and the opposite direction of paper discharge, a guide mechanism (sheet guide member) 44 for guiding the sheet to the tray side, and a scraping rotating body 46 for guiding the sheet to the rear end regulating portion.

[0058] The reverse transfer mechanism includes a lifting roller 41 that moves up and down between an operating position where it engages with the sheet carried onto the processing tray 37 and a separated standby position, and a paddle rotating body 42 that transfers the sheet in the direction opposite to the paper discharge direction. The lifting roller 41 and the paddle rotating body 42 are attached to a swing bracket 43.

[0059] A swing bracket 43 is arranged on the apparatus frame 27 so as to be swingable about a rotating shaft (for example, a paper discharge roller shaft). The rotating shafts of the lifting roller 41 and the paddle rotating body 42 are supported by bearings on the swing bracket 43. And a lifting motor (not shown) is connected to the swing bracket 43, and the swing bracket 43 moves the mounted lifting roller 41 and paddle rotating body 42 up and down between an operating position where they engage with the sheet and a standby position separated from the sheet.

[0060] Also, a drive motor (not shown) is connected to the lifting roller 41 and the paddle rotating body 42, and the drive is transmitted such that the lifting roller 41 rotates in the forward and reverse directions and the paddle rotating body 42 rotates in the reverse direction (the direction opposite to the paper discharge direction). Further, a driven roller 48 that is in pressure contact with the lifting roller 41 is arranged on the processing tray 37, and a single sheet or a bundled sheet is nipped and discharged to the downstream side.

[0061] Between the lifting roller 41 and the scraping and rotating body 46 (to be described later), a guide mechanism is arranged to guide the rear end of the sheet carried onto the processing tray 37 toward the sheet end regulating portion 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. When the sheet is discharged from the straight path discharge port 35, the sheet guide member 44 retracts to the dotted line position, and after the rear end of the sheet passes through the straight path discharge port 35, the rear end of the sheet is guided onto the processing tray 37. For this reason, a drive mechanism (not shown) is connected to the sheet guide member 44, and it moves up and down according to the timing of guiding the rear end of the sheet from the straight path discharge port 35 onto the processing tray 37.

[0062] <Sheet positioning mechanism> On the processing tray 37, positioning mechanisms 38 and 39 for positioning the sheet at a predetermined binding position are arranged. The illustrated ones include a sheet end regulating portion 38 that abuts and regulates the rear end of the sheet, and a side edge aligning portion 39 that positions the side edge of the sheet at a reference (center reference, one - side reference) position.

[0063] As shown in FIG. 3, the sheet end regulating portion 38 is composed of a stopper member that abuts and regulates the rear end of the sheet. Also, the side edge aligning member 39, which will be described later with reference to FIG. 9, discharges the sheet from the straight path 28 with the center as the reference. Depending on the type of binding mode, positioning with the same center reference or positioning with one - side reference is executed.

[0064] <Side edge alignment mechanism> As shown in FIG. 9, the side edge alignment plates 39F and 39R project upward from the paper placement surface 37a of the processing tray 37 and have a regulating surface 39x that engages with the side edge of the sheet. A pair of them are arranged opposite to each other left and right. And this pair of side edge aligning portions 39 are arranged on the processing tray 37 so as to be reciprocally movable within 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 for moving the aligned sheet bundle in either the left or right direction (offset conveyance).

[0065] That is, the moving strokes of the left and right side edge alignment plates 39F and 39R are set by the amount of movement for aligning sheets of different sizes and the offset amount of the sheet bundle after alignment. Note that the side edge alignment plates 39F and 39R are moved by a predetermined amount to the right when performing right corner binding and to the left when performing left corner binding for the sheets carried out based on the center reference during corner binding (offset movement). This offset movement can be either executed one by one each time a sheet is carried into the processing tray 37 (for each carried-in sheet) or moved for each bundle in order to perform the binding process after aligning the sheets in a bundle form.

[0066] Therefore, as shown in FIG. 9, the side edge alignment unit 39 is configured to include a right side edge alignment member 39F (front side of the apparatus) and a left side edge alignment member 39R (rear side of the apparatus). On both side edge alignment members, a regulating surface 39x that engages with the side edge of the sheet is supported on the processing tray 37 so as to move in the approaching or separating direction from each other. The processing tray 37 is provided with a slit groove (not shown) that penetrates the front and back surfaces, and the side edge alignment unit 39 having a regulating surface 39x that engages with the side edge of the sheet is slidably fitted to this slit groove.

[0067] Each of the side edge alignment plates 39F and 39R is slidably supported by a plurality of guide rollers 80 (which may be rail members) on the back side of the tray, and a rack 81 is integrally formed. Alignment motors M1 and M2 are connected to the left and right racks 81 via pinions 82. The left and right alignment motors M1 and M2 are composed of stepping motors, and the positions of the left and right side edge alignment plates 39F and 39R are detected by a position sensor (not shown). Based on the detected values, each alignment member is configured to be positionally moved in either the left or right direction by a specified amount of movement. Note that the present invention is not limited to the illustrated rack and pinion mechanism, and each side edge alignment plate 39F and 39R may be fixed to a timing belt, and the timing belt may be connected to a motor that reciprocates left and right via pulleys.

[0068] With the above configuration, the binding process control unit 95 described later waits for the left and right side edge alignment members 39F and 39R at a predetermined standby position (sheet width size + α position) based on the sheet size information provided from the image forming apparatus A. Then, during "multi-binding", a sheet is loaded onto the processing tray 37, and the alignment operation is started at the timing when the sheet end hits the sheet end regulating unit 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). Then, the sheet loaded onto the processing tray 37 is positioned based on the sheet center and stacked in a bundle. By repeating this sheet loading operation and alignment operation, the sheets are partially aligned and accumulated in a bundle on the processing tray 37. At this time, sheets of different sizes are positioned based on the center reference. Also, during "corner binding", a sheet is loaded onto the processing tray 37, and the alignment operation is started at the timing when the sheet end hits the sheet end regulating unit 38. This alignment operation is performed by making the moving amounts of the alignment plate on the binding position side and the alignment plate on the opposite side of the binding position different. Then, the moving amount is set so that the sheet corner is positioned at a preset binding position.

[0069] <Binding processing mechanism> On the processing tray 37, a binding processing mechanism 47 for binding the sheet bundle accumulated on the paper placement surface 37a is arranged. The paper placement surface 37a on the processing tray 37 is positioned at a predetermined binding position by a positioning mechanism (sheet end regulating unit 38 and side edge alignment unit 39). The binding processing mechanism 47 is configured as a binding unit 47 (hereinafter the same as "staple unit") that stitches the sheet bundle with staple pins.

[0070] On the processing tray 37, a binding processing mechanism 47 for binding the rear end of the sheet carried in from the straight path discharge port 35 is arranged, and the binding processing mechanism 47 is composed of a staple unit 47 that can move along the rear end of the paper placement surface 37a of the processing tray 37 as shown in FIG. 8.

[0071] Figs. 8 and 9 show the staple unit 47 disposed on the processing tray 37. In Fig. 9, a stitching position Cp1 is set at the corner of the sheet located on the left side in the drawing. The staple unit 47 moves along the first running rail 53 and the second running rail 54 formed on the apparatus frame 27b with a predetermined stroke SL1.

[0072] Fig. 9 shows the sheet carried into the processing tray 37 and the movement stroke SL1 of the stitching unit 47. Sheets of different sizes are carried into the processing tray 37 from the largest size sheet to the smallest size sheet centered. A pair of left and right side edge alignment plates 39F and 39R align different size sheets so that the stitching side edges of the sheets (the one shown in the figure is the left side edge) coincide. For this reason, the left and right side edge alignment plates 39F and 39R are respectively connected to different drive motors M1 and M2, and the stitching process control unit 95 described later sets the movement amounts of the left and right side edge alignment plates 39F and 39R according to the sheet size.

[0073] Note that the stitching process control unit 95 described later aligns the sheet centered in stitching processes other than stitching the sheet corners, for example, in the multi-stitching mode described later. In this case, the left and right side edge alignment plates 39F and 39R position the sheet at the stitching position by moving the same amount closer to the center of the sheet from the standby position.

[0074] Explaining with reference to Fig. 9, the stitching unit 47 moves with a stroke SL1 between the standby position Wp1 (the first standby position) and the stitching position Cp1. That is, the staple unit 47 reciprocates between the standby position Wp1 and the stitching position Cp1 along the running rails 53 and 54 (such as guide grooves and guide rods). The first standby position Wp1 is set outside the largest size sheet to be stitched on the processing tray 37.

[0075] FIG. 10 shows the configuration of the stapling unit 47. On the apparatus frame 27b, a pair of left and right pulleys 58a and 58b are arranged along the moving region (left - right direction in FIG. 9) of the stapling unit 47, and a timing belt 59 (toothed belt) is stretched between the two pulleys. A drive motor M3 (stepping motor) is connected to one of the pulleys 58a.

[0076] <Staple moving mechanism> As shown in FIG. 8, the stapling unit 47 is mounted on the apparatus frame (chassis frame) 27b fixed to the side frame frames 70f and 70r by passing through an opening provided in the side frame frame 70f of the apparatus frame 70 so as to be movable in a predetermined stroke. On the apparatus frame 27b, a first running rail 53 and a second running rail 54 are arranged. 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 stapling unit 47 (hereinafter referred to as the "moving unit" in this section) so as to be reciprocally movable in a predetermined stroke, and at the same time control its angular posture.

[0077] The first running rail 53 and the second running rail 54 are formed with a rail surface 53x and a running cam surface 54x so as to reciprocate within the moving range of the moving unit. As shown in FIG. 10, a timing belt 59 connected to a drive motor (running motor) M3 is fixed to the stapling unit 47. The timing belt 59 is wound around a pair of pulleys 58a and 58b pivotally supported by the apparatus frame 27b, and a drive motor M3 is connected to one of the pulleys. Therefore, by the forward and reverse rotation of the drive motor M3, the stapling unit 47 reciprocates with a stroke SL1.

[0078] The staple unit 47 is engaged with the first and second traveling rails 53 and 54 as follows. As shown in FIG. 8, the staple unit 47 is provided with a first rolling roller 83 (rail fitting member) that engages with the traveling rail surface 53x and a second rolling roller 84 (cam follower member) that engages with the traveling cam surface 54x. Further, ball-shaped sliding rollers 47x (two places are shown in the figure) that engage with the support surface of the frame 27b are formed on the staple unit 47. Further, a guide roller 47y that engages with the bottom surface of the bottom frame portion frame is formed on the staple unit 47, preventing the staple unit 47 from floating from the apparatus frame 27b.

[0079] With the above configuration, the staple unit 47 is movably supported by the apparatus frame 27b with the sliding rollers 47x and the guide rollers 47y. Further, the first rolling roller 83 rotates along the traveling rail surface 53x, and the second rolling roller 84 rotates along the traveling cam surface 54x and travels along the rail surface 53x and the cam surface 54x while rotating.

[0080] <Stack Tray Lifting Mechanism> As shown in FIG. 11, the sheet post-processing apparatus B is provided with a first tray 49. The first tray 49 is configured to move up and down according to the loading amount of the sheets. For this reason, guide rollers 85 are provided at two positions above and below at the base end portion of the first tray 49, and the guide rollers 85 are fitted and supported by lifting guides 86 provided on the apparatus frame 27. And a lifting gear 88 is provided at the base end portion of the first tray 49 and is connected to a lifting rack gear 87. Further, a lifting motor M4 is connected to the lifting gear 88. Therefore, by controlling the rotation of the lifting motor M4, the first tray 49 moves up and down according to the loading amount of the sheets.

[0081] <Sheet Bundle Carry-Out Mechanism> The processing tray 37 is provided with a sheet bundle discharging mechanism for discharging the stapled sheet bundle toward the downstream first tray 49. As a configuration for conveying the sheet bundle downstream, there are known a method of conveying with a pair of rollers that are in pressure contact with each other (discharging roller mechanism), and a conveyor mechanism that pushes out the rear end of the sheet with an extrusion member that moves from the upstream side to the downstream side along the tray surface. The illustrated apparatus employs both of them.

[0082] Fig. 12 shows the sheet bundle discharging mechanism. The conveyor mechanism is configured to include an extrusion protrusion 45 that transfers the sheet bundle from the stapling position (processing position) located upstream along the processing tray 37 to the downstream stack tray (first tray) 49, a conveyor belt 45v that moves the extrusion protrusion, and a drive motor M6. The processing tray 37 is provided with a driven roller 48 at its discharge port (the boundary between the paper placement surface 37a and the first tray 49), and a lifting roller 41 that is disposed opposite to and in pressure contact with the driven roller 48. The driven roller 48 and the lifting roller 41 constitute the discharging roller mechanism.

[0083] Therefore, the processing tray 37 is provided with a conveyor mechanism 45, 45v that transfers the sheet bundle so as to push it out from the upstream side to the downstream side, and a discharging roller mechanism 48, 41 that nips and discharges the sheet bundle. Fig. 12(a) shows a state where the sheet bundle is located at the stapling position on the processing tray 37. At this time, the conveyor mechanism 45, 45v and the discharging roller mechanism 48, 41 are in an operating state. Fig. 12(b) shows a state during the transfer of the sheet bundle from the processing position to the downstream side. The sheet bundle is sent downstream by the movement of the extrusion protrusion 45 and the rotation of the discharging roller mechanism 48, 41. Fig. 12(c) shows a state immediately before discharging the sheet bundle to the downstream first tray 49. On the processing tray, the sheet bundle is gradually (slowly) sent downstream by the rotation of the discharging roller mechanism 48, 41. At this time, the extrusion protrusion 45 waits at the illustrated position and returns (moves backward) to the initial position.

[0084] <Configuration of Staple Unit> Regarding the above staple unit, its configuration will be described with reference to FIG. 13. The staple unit 47 is unitarily configured separately 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 for rotating the drive cam 47d are mounted on the unit frame 47a.

[0085] And, on the drive cam 47d, a staple head 47b and an anvil member 47c are arranged to face each other at the stapling position. The staple head 47b is biased by a biasing spring (not shown) on the drive cam 47d from the upper standby position to the lower staple position (anvil member) and moves up and down. And, a needle cartridge 52 is detachably mounted on the unit frame 47a.

[0086] The needle cartridge 52 stores linear blank needles, and supplies the needles to the staple head 47b by a needle feeding mechanism. The staple head portion 47b incorporates a former member for bending a linear needle into a U-shape inside, and a driver for pressing the bent needle into the sheet bundle. With such a configuration, the drive motor M4 rotates the drive cam 47d and stores energy in the biasing spring. Then, when the rotation angle reaches a predetermined angle, the staple head portion 47b rapidly descends toward the anvil member 47c side. In this operation, the staple needle is bent into a U-shape and then pierced into the sheet bundle by the driver. And, its tip is bent by the anvil member 47c and stapled.

[0087] Also, a needle feeding mechanism is incorporated between the needle cartridge 52 and the staple head 47b, and a sensor (empty sensor) for detecting the absence of needles is arranged in the needle feeding mechanism. Also, a cartridge sensor (not shown) for detecting whether the needle cartridge 52 is inserted or not is arranged on the unit frame 47a.

[0088] The staple cartridge 52 has a structure in which staple pins connected in a strip shape are stacked and stored in a box-shaped cartridge, and a structure in which they are stored in a roll shape. Further, the unit frame 47a is provided with a circuit for controlling each of the above 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 staple pins are empty. Further, the staple control circuit controls the drive motor M4 to execute a staple operation with a staple pin signal, and is configured to transmit an "operation end signal" when the staple head portion 47b moves from the standby position to the staple position and returns to the standby position again.

[0089] <Description of Control Configuration> The control configuration in the image forming system of FIG. 1 will be described with reference to FIG. 14. The image forming system shown in FIG. 14 includes a control unit 90 (hereinafter referred to as "main body control unit") of the image forming apparatus A and a control unit 95 (hereinafter referred to as "binding process control unit") of the sheet post-processing apparatus B. The main body control unit 90 controls a print control unit 91, a paper feed control unit 92, and an input unit 93 (control panel).

[0090] Then, based on the user operation received via the input unit 93 (control panel), settings for "image forming mode" and "post-processing mode" are made. In the image forming mode, for example, mode settings such as color / monochrome printing, double-sided / single-sided printing, and image forming conditions such as sheet size, sheet paper quality, number of printed copies, and enlarged / reduced printing are set. Also, in the "post-processing mode", for example, "printed copy mode", "bookbinding process paper discharge mode", "staple binding process mode", and "jog sorting mode" are set.

[0091] Further, the main body control unit 90 transfers data such as the fact that it is the post-processing mode, the number of sheets, the number of copies, and the paper thickness information of the sheets to be image 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.

[0092] Regarding the post - processing mode described above, the "print - out mode" is a mode in which the sheet from the straight - path paper discharge port 35 is accommodated in the stack tray 49 through the processing tray 37 without binding processing. In this case, the sheets are stacked and accumulated on the processing tray 37, and the stacked sheet bundle is carried out to the stack tray 49 by a job - end signal from the main control unit 90.

[0093] The "product - processing paper - discharge mode" is a mode in which the imaged sheets are collated, bound, folded, and then book - bound. Details will be described later with reference to FIG. 15.

[0094] The "staple - binding processing mode" is a mode in which the sheets from the straight - path paper discharge port 35 are accumulated and collated on the processing tray 37, the sheet bundle is bound, and then accommodated in the stack tray 49. In this case, the sheets to be imaged are specified by the operator so that they are generally sheets of the same paper thickness and the same size. In this staple - binding processing mode, either "multi - binding", "right - corner binding", or "left - corner binding" is selected and specified.

[0095] In the " jog - sorting mode", the sheets imaged by the image forming apparatus A are divided into a group that is offset - moved and accumulated and a group that is accumulated without offset - movement. In the stack tray, the sheet bundles that are alternately offset - moved and the sheet bundles that are not offset - moved are stacked.

[0096] <Binding processing control unit> The binding processing control unit 95 operates the sheet post - processing apparatus B according to the post - processing mode set by the image forming control unit 90. The binding processing control unit 95 is configured to include a control CPU. A ROM 96 and a RAM 97 are connected to the binding processing control unit 95, and the operation of the sheet post - processing apparatus B in this embodiment is executed by the control program stored in the ROM 96 and the control data stored in the RAM 97. For this reason, the binding processing control unit 95 controls the drive circuits of all the drive motors described above, and performs start, stop, and forward - reverse rotation control of each motor.

[0097] Even while post - processing is being performed in the processing unit B1, image formation continues to be performed by the image forming apparatus A. Therefore, in the present embodiment, a buffer operation is performed to store the sheets conveyed from the image forming apparatus A in the sheet post - processing apparatus B. Thereby, without reducing the frequency at which sheets are supplied from the image forming apparatus A, that is, without reducing the productivity of the image forming apparatus A, post - processing can be continuously performed.

[0098] With reference to FIGS. 15 to 30, an overview of the sheet buffer operation in the sheet post - processing apparatus B will be described. FIGS. 15 to 29 show cross - sectional views seen from the side direction of the sheet post - processing apparatus B. FIG. 30 is a diagram showing the configuration around the processing unit buffer path flapper 200. Hereinafter, the buffer operation of the sheet when there is a sheet bundle on which binding processing has been performed in advance by the binding unit 47 will be described. For example, when the binding process control unit 95 acquires sensor information provided in the binding unit 47 and detects a preceding sheet bundle, it performs the following processing.

[0099] In FIG. 15(a), the sheet bundle SS1 represents a preceding sheet bundle and is in a state where binding processing is being performed by the binding unit 47. In this example, the number of sheets in the sheet bundle on which binding processing is performed by the binding unit 47 is three. Note that the number of sheets in the sheet bundle is not limited to three and may be less than three or more than three. In FIG. 15(a), the upper conveyance path flapper 34 is in an open - upward state, whereby the sheets conveyed on the straight path 28 are conveyed in the direction of the lifting roller 41 and the driven roller 48. Also, at this time, the sheet support 401 is in the standby position, and the processing unit buffer path flapper 200 can rotate downward.

[0100] Here, the possible positions of the sheet support 401 will be described. FIGS. 30(a) to 30(c) are enlarged views of the vicinity of the processing unit buffer path flapper 200 and the sheet support 401. The processing unit buffer path flapper 200 provided between the second conveyance roller 202 and the third conveyance roller 203 is configured to be rotatable downward in the drawing direction.

[0101] FIG. 30(a) shows a state in which the processing unit buffer path flapper 200 is opened upward and the sheet support 401 is positioned below the second conveyance roller 202. In the present embodiment, the position of the sheet support 401 at this time is referred to as the standby position. Also, in the state of FIG. 30(a), the processing unit buffer path flapper 200 is rotatable downward.

[0102] FIG. 30(b) shows a state in which the processing unit buffer path flapper 200 is opened upward and the sheet support 401 has moved to the side of the processing unit buffer path flapper 200. In the present embodiment, the position of the sheet support 401 at this time is referred to as the support position. When the sheet support 401 is in the support position, the sheet conveyed from the second conveyance roller 202 side can be supported from below. With such a configuration, it is possible to prevent the leading end of the sheet from drooping and causing jams or the like.

[0103] FIG. 30(c) shows a state in which the sheet support 401 is in the standby position and the processing unit buffer path flapper 200 has rotated downward. When the processing unit buffer path flapper 200 is in the state of rotating downward, the sheet conveyed from the third conveyance roller 203 side can be guided to the processing unit buffer path P1.

[0104] For example, in the sheet post-processing apparatus B, the sheet conveyed from the second conveyance roller 202 side passes through the third conveyance roller 203, and when the trailing edge of the sheet passes through the second conveyance roller 202, the processing unit buffer path flapper 200 rotates downward, reverses the conveyance direction of the sheet, and guides and conveys it to the processing unit buffer path P1 (reverse conveyance). In order to perform such an operation quickly, the arm length of the processing unit buffer path flapper 200 is configured to be long. On the other hand, since the rotation space of the processing unit buffer path flapper 200 becomes large, the distance between the second conveyance roller 202 and the third conveyance roller 203 becomes large. As a result, there is a high possibility that the leading edge of the sheet conveyed from the second conveyance roller 202 side will sag, causing jams or the like. In the present embodiment, when conveying the sheet on the straight path 28 formed by the second conveyance roller 202 and the third conveyance roller 203, the sheet support 401 is moved to the support position as shown in FIG. 30(b). Thereby, the above-described situation can be prevented.

[0105] In FIG. 15(b), the upper conveyance path flapper 34 changes from the state of being open upward to the state of being open downward. Thereby, the sheet conveyed on the straight path 28 is conveyed to the upper conveyance path 30. Also, the sheet support 401 moves to the support position. Thereby, the sheet conveyed on the straight path 28 is supported from below by the sheet support 401.

[0106] FIG. 16(a) shows a state in which the sheet S1 has been sent from the image forming apparatus A. The sheet S1 corresponds to the first sheet in the sheet bundle processed in the subsequent binding unit 47. In FIG. 16(a), the sheet S1 is shown in a state of having been conveyed to the second conveyance roller 202. As described above, since the sheet support 401 has moved to the support position, it is possible to prevent the leading edge of the sheet S1 from sagging downward and causing jams or the like.

[0107] FIG. 16(b) shows the state where the sheet S1 has been conveyed to the upper conveyance roller 303a. Thus, when the preceding sheet bundle SS1 in the binding unit 47 is being processed, the sheet sent subsequently from the image forming apparatus A can be retracted to the upper conveyance path 30.

[0108] FIG. 17(a) shows the state where the sheet S1 has been conveyed to the upper conveyance roller 303b. At this time, the processing of the binding unit 47 for the preceding sheet bundle SS1 is completed, and the discharge of the preceding sheet bundle SS1 to the first tray 49 has started.

[0109] FIG. 17(b) shows the state where the conveyance direction of the sheet S1 is reversed, the sheet S1 is conveyed to the position of the punch unit 100, and skew correction (tilt correction) and positioning are performed based on the rear end of the sheet. Then, the punch unit 100 punches a punch hole in the sheet S1. At this time, the preceding sheet bundle SS1 is being discharged to the first tray 49.

[0110] FIG. 18(a) shows the state where, after the punching process of the punch hole by the punch unit 100, the conveyance direction of the sheet S1 is reversed and the sheet S1 is conveyed again to the upper conveyance path 30. The sheet S1 is conveyed until the rear end passes through the position of the second conveyance roller 202. Then, the sheet support 401 moves from the support position to the standby position. Thereby, the processing unit buffer path flapper 200 can be rotated downward.

[0111] FIG. 18(b) shows the state where the conveyance direction of the sheet S1 is reversed and the conveyance direction of the sheet S1 is changed by the rotation of the processing unit buffer path flapper 200. Thereby, the sheet S1 is reversely conveyed to the processing unit buffer path P1.

[0112] FIG. 19(a) shows the state where the sheet S1 passes through the processing unit buffer roller 301a and is being conveyed through the processing unit buffer path P1.

[0113] FIG. 19(b) shows a state where the processing unit buffer roller 301a has stopped and the sheet S1 has been retracted to the processing unit buffer path P1. Also shown is a state where the sheet S2 has been sent from the image forming apparatus A. The sheet S2 corresponds to the second sheet in the sheet bundle that is processed together with the sheet S1 in the subsequent binding unit 47. For illustrative purposes, the sheet S2 is shown by a dotted line to distinguish it from the other sheets.

[0114] FIG. 20(a) shows a state where the sheet support 401 has moved to the support position. This can prevent the leading edge of the sheet S2 from drooping downward and causing a jam or unexpected contact with the sheet S1 that has been retracted to the processing unit buffer path P1.

[0115] FIG. 20(b) shows a state where the sheets S1 and S2 are being conveyed synchronously. In this embodiment, the leading edge of the sheet S1 is conveyed with a predetermined interval delay relative to the leading edge of the sheet S2. The synchronization of the conveyance operation between the sheets here is performed, for example, based on the detection timing when the sheet is supplied from the image forming apparatus A to the straight path inlet 26, by conveyance control using pulse counting. As a result, the leading edges of the respective sheets in the sheet bundle are shifted in order. Therefore, when the sheet bundle is scraped into the rear end portion of the paper placement surface 37a of the processing tray 37 by the scraping rotator 46 at the subsequent stage, it will sequentially contact the rear end portion, and the leading edge portions of all the sheets in the sheet bundle can be operated to contact the rear end portion in a state where they are aligned.

[0116] FIG. 21(a) shows a state where the sheets S1 and S2 are overlapping and being conveyed synchronously along the upper conveyance path 30. Here, the rear end of the sheet S2 has passed through the punching unit 100. Then, when the sheets S1 and S2 are conveyed to a predetermined position on the upper conveyance path 30, the conveyance directions of the sheets S1 and S2 are reversed.

[0117] Figure 21(b) shows a state in which the conveyance directions of the sheet S1 and the sheet S2 are reversed, the sheet S2 is conveyed to the punch unit 100, and skew correction (tilt correction) and positioning are performed with reference to the rear end. Here, the sheet S1 is conveyed to the processing unit buffer path P1. Also in the conveyance here, the sheet S1 and the sheet S2 are conveyed synchronously. Then, the punch unit 100 punches punch holes in the sheet S2.

[0118] Figure 22(a) shows a state in which after the punch holes are punched by the punch unit 100, the punch unit 100 has moved to the retracted position.

[0119] Figure 22(b) shows a state in which the conveyance directions of the sheet S1 and the sheet S2 are reversed, and the sheet S1 and the sheet S2 are overlapped and synchronously conveyed to a predetermined position on the upper conveyance path 30. Then, the sheet support 401 moves from the support position to the standby position. As a result, the processing unit buffer path flapper 200 becomes rotatable downward.

[0120] Figure 23(a) shows a state in which the conveyance directions of the sheet S1 and the sheet S2 are reversed, and the conveyance direction of the sheet has changed due to the rotation of the processing unit buffer path flapper 200. As a result, the sheet S1 and the sheet S2 are guided to the processing unit buffer path P1. Also in the conveyance here, the sheet S1 and the sheet S2 are conveyed synchronously.

[0121] Figure 23(b) shows a state in which the processing unit buffer roller 301a has stopped and the sheet S1 and the sheet S2 have retracted to the processing unit buffer path P1.

[0122] Figure 24(a) shows the state where the sheet S3 has been sent from the image forming apparatus A. The sheet S3 corresponds to the third sheet (the final sheet) among the stack of sheets to be processed in the subsequent binding unit 47. At this time, the sheet support 401 moves from the standby position to the support position. This can prevent the leading edge of the sheet S3 from drooping downward and causing jams or unexpected contact with the sheets S1 and S2 that are retracted in the processing unit buffer path P1. Also, at this time, the upper conveyance path flapper 34 changes from the state of opening downward to the state of opening upward.

[0123] Figure 24(b) shows the state where the processing unit buffer roller 301a rotates, and further, the sheets S3, S1, and S2 overlap and are conveyed synchronously. In the present embodiment, the leading edge of the sheet S2 is conveyed with a predetermined interval delay compared to the leading edge of the sheet S3. The synchronization of the conveyance operation between the sheets here is performed, for example, by conveyance control based on pulse counting based on the detection timing when the sheet is supplied from the image forming apparatus A.

[0124] Figure 25(a) shows the state where the sheets S3, S1, and S2 overlap and are conveyed synchronously. Here, since the upper conveyance path flapper 34 is in the state of opening upward, the sheets S1, S2, and S3 are conveyed in the direction of the lifting roller 41 and the driven roller 48.

[0125] Figure 25(b) shows the state where the conveyance directions of the sheets S3, S1, and S2 are reversed, the sheet S3 is conveyed to the punch unit 100, and skew correction (tilt correction) and positioning are performed with reference to the rear end. Here, the sheets S3, S1, and S2 are conveyed to the processing unit buffer path P1. Also in this conveyance, the sheets S3, S1, and S2 are conveyed synchronously. Then, the punch unit 100 punches punch holes in the sheet S3.

[0126] FIG. 26(a) shows a state where the punch unit 100 has moved to the retracted position after the punching of the punch holes by the punch unit 100.

[0127] FIG. 26(b) shows a state where the conveyance directions of sheets S1 to S3 are reversed, and sheet S3 overlaps with sheets S1 and S2 and is conveyed synchronously.

[0128] FIG. 27(a) shows a state where the rear ends of sheets S1 to S3 have been conveyed to a position where they pass through the paper discharge roller 36. Then, by reversing the lifting roller 41 and the driven roller 48, the sheet bundle of sheets S1 to S3 is conveyed to the binding unit 47.

[0129] FIG. 27(b) shows a state where the sheet bundle of sheets S1 to S3 is scraped into the rear end portion of the paper placement surface 37a of the processing tray 37 by the scraping rotator 46.

[0130] FIG. 28(a) shows a state where the binding unit 47 performs a binding process on the sheet bundle of sheets S1 to S3. FIG. 28(b) shows a state where after the binding process by the binding unit 47, the sheet bundle SS2 of sheets S1 to S3 is discharged to the first tray 49 by the lifting roller 41 and the driven roller 48. FIG. 29 shows a state where the sheet bundle SS2 of sheets S1 to S3 has been discharged to the first tray 49.

[0131] As described above, according to the present embodiment, productivity can be further improved in a configuration in which post-processing is performed on the sheets continuously supplied from the image forming apparatus A. In particular, even when performing binding processes at two or more locations, or when performing time-consuming post-processing such as pressure binding in which the sheets are pressure-bonded and bound, the image forming apparatus can be operated without stopping its operation. Also, in FIGS. 21(b) and 25(b), it was explained that the sheet S1 is conveyed in synchronization with the sheet S2, and the sheet S3 is conveyed in synchronization with the sheets S1 and S2. Thereby, rubbing between the sheet to be perforated and the sheet not to be perforated (perforated sheet) can be prevented, and degradation of the quality of the product such as rubbing of the image or the sheet surface can be prevented. In the above description, the operation when there is a preceding sheet bundle SS1 has been explained. When there is no preceding sheet bundle SS1, the above-described buffer operation is not performed on the sheet supplied from the image forming apparatus A. In that case, for example, the sheet supplied from the image forming apparatus A is reversely conveyed from the straight path 28 to the processing unit buffer path P1 without performing the buffer operation to the upper conveyance path 30, and then, in synchronization with the sheet newly supplied to the straight path inlet 26 from the image forming apparatus A, it is conveyed to the elevating roller 41 and the driven roller 48. Then, by reversing the elevating roller 41 and the driven roller 48, the sheet bundle is conveyed to the binding unit 47.

[0132] In the present embodiment, the highly accurate perforation processing mode (high-precision punch mode) has been described. However, in the case of more productive perforation processing (high-productivity punch mode), it is also possible for the operator to set to perform the perforation processing by stopping the sheet during conveyance without performing the reversing operation to the punch position.

[0133] The disclosure of the present embodiment includes the following post-processing apparatus. (Item 1) A receiving unit for receiving a sheet, and A first conveyance roller for conveying the sheet received by the receiving unit, A first guide portion that forms a conveyance path together with the first conveyance roller and is configured to be able to switch the conveyance path of the sheet, a second guide portion located downstream of the first guide portion, A post-processing portion that is located downstream of the second guide portion and executes post-processing on the sheet bundle conveyed through the conveyance path, A first retraction path provided on one side with respect to the conveyance path, and when there is a sheet bundle ahead of the post-processing portion, receiving the sheet conveyed by the first conveyance roller through the first guide portion and the second guide portion and retracting the sheet, A second conveyance roller provided on the first retraction path, holding the sheet conveyed to the first retraction path, and conveying the sheet along the first retraction path, A second retraction path provided on the other side with respect to the conveyance path, and receiving the sheet reversely conveyed by the second conveyance roller through the second guide portion and the first guide portion and retracting the sheet, A third conveyance roller provided on the second retraction path, holding the sheet conveyed to the second retraction path, and conveying the sheet along the second retraction path, A punch unit located upstream of the first retraction path and the second retraction path, and performing a punching process on the sheet received by the receiving portion, Comprising After the first sheet received by the receiving portion is retracted to the second retraction path, when the receiving portion receives a second sheet, the first sheet conveyed by the third conveyance roller from the second retraction path and the second sheet received by the receiving portion are conveyed overlapping each other, and then, the second sheet is conveyed in the direction opposite to the conveyance to be conveyed to the punch unit and the punching process is performed, When the second sheet is conveyed to the punch unit, the first sheet is controlled to be conveyed in synchronization with the second sheet, A post-processing apparatus characterized by this. (Item 2) The post-processing apparatus according to item 1, wherein the punching process is performed on the first sheet by the punching unit before the receiving portion receives the second sheet. (Item 3) After the punching process is performed on the second sheet by the punching unit, the first sheet conveyed by the third conveying roller from the second retracting path and the second sheet on which the punching process has been performed by the punching unit are overlapped with each other and conveyed to the post-processing unit. The post-processing apparatus according to item 1 or 2, characterized in that (Item 4) The post-processing apparatus according to any one of items 1 to 3, wherein the second retracting path receives all of the length in the conveying direction of the sheet reversely conveyed by the second conveying roller from the rear end of the sheet via the second guide portion and the first guide portion and retracts the sheet. (Item 5) The post-processing apparatus according to any one of items 1 to 4, wherein when there is no preceding sheet bundle in the post-processing unit, the sheet conveyed by the first conveying roller is conveyed to the post-processing unit without being retracted to the first retracting path. (Item 6) The post-processing apparatus according to any one of items 1 to 5, wherein the first sheet and the second sheet are controlled to be overlapped with each other with their leading ends shifted and conveyed to the post-processing unit. (Item 7) The post-processing apparatus according to any one of items 1 to 6, wherein the first sheet is controlled to be overlapped with the second sheet in a state of being delayed and conveyed to the post-processing unit. (Item 8) The post-processing apparatus further includes control means for controlling the sheet support provided below the first guide portion to move between a standby position and a support position. The post-processing apparatus according to any one of items 1 to 7, wherein the control means moves the sheet support to the support position when the sheet received by the receiving portion is conveyed through the first guide portion. (Item 9) When the control means retracts the sheet reversely conveyed by the second conveying roller to the second retracting path via the second guide portion and the first guide portion, the post-processing apparatus according to item 8, wherein the sheet support is moved to the standby position. (Item 10) The post-processing apparatus according to item 8 or 9, wherein the first guide portion is capable of rotating downward when the sheet support is in the standby position. (Item 11) The post-processing apparatus according to any one of items 1 to 10, wherein the post-processing is a binding process. (Item 12) The post-processing apparatus according to any one of items 1 to 11, wherein the receiving portion receives the sheet discharged from the image forming apparatus. (Item 13) The post-processing apparatus according to any one of items 1 to 12, wherein the conveying path is substantially linear.

[0134] The invention is not limited to the above embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, claims are attached to disclose the scope of the invention.

Explanation of Reference Numerals

[0135] 28 Straight path: 201 Inlet roller: 202, 203 Shift roller: 203 Intermediate conveying roller: 33a Upper flapper: 33b Lower flapper

Claims

1. A receiving part for receiving a sheet, A first conveying roller for conveying the sheet received by the receiving part, A first guide part configured to form a conveying path together with the first conveying roller and to be able to switch the conveying path of the sheet, and a second guide part located downstream of the first guide part, A post-processing part located downstream of the second guide part and performing post-processing on the sheet bundle conveyed through the conveying path, A first retracting path provided on one side with respect to the conveying path, and when there is a sheet bundle ahead of the post-processing part, receiving the sheet conveyed by the first conveying roller through the first guide part and the second guide part and retracting the sheet, A second conveying roller provided on the first retracting path, holding the sheet conveyed to the first retracting path, and conveying the sheet along the first retracting path, A second retracting path provided on the other side with respect to the conveying path, and receiving the sheet reversely conveyed by the second conveying roller through the second guide part and the first guide part and retracting the sheet, A third conveying roller provided on the second retracting path, holding the sheet conveyed to the second retracting path, and conveying the sheet along the second retracting path, A punch unit located upstream of the first retracting path and the second retracting path and performing a punching process on the sheet received by the receiving part, Comprising, After the first sheet received by the receiving part is retracted to the second retracting path, when the receiving part receives a second sheet, the first sheet conveyed by the third conveying roller from the second retracting path and the second sheet received by the receiving part are conveyed overlapping each other, and then, the second sheet is conveyed in the direction opposite to the conveying to be conveyed to the punch unit and the punching process is performed, When the second sheet is conveyed to the punch unit, the first sheet is controlled to be conveyed in synchronization with the second sheet, A post-processing device characterized by the above.

2. The post-processing device according to claim 1, characterized in that the punching process is performed on the first sheet by the punch unit before the receiving part receives the second sheet.

3. After the punching process is performed on the second sheet by the punching unit, the first sheet conveyed by the third conveying roller from the second retracting path and the second sheet on which the punching process has been performed by the punching unit are conveyed to the post-processing unit while overlapping each other. The post-processing apparatus according to claim 1, characterized in that.

4. The second retracting path receives all of the lengths in the conveying direction of the sheet reversely conveyed by the second conveying roller from the rear end of the sheet via the second guide portion and the first guide portion, and retracts the sheet. The post-processing apparatus according to claim 1, characterized in that.

5. When there is no preceding sheet bundle in the post-processing unit, the sheet conveyed by the first conveying roller is conveyed to the post-processing unit without being retracted to the first retracting path. The post-processing apparatus according to claim 1, characterized in that.

6. The first sheet and the second sheet are controlled to be conveyed to the post-processing unit while overlapping each other with their leading ends displaced. The post-processing apparatus according to claim 1, characterized in that.

7. The first sheet is controlled to be conveyed to the post-processing unit while overlapping the first sheet in a state delayed with respect to the second sheet. The post-processing apparatus according to claim 1, characterized in that.

8. Further comprising control means for controlling the sheet support provided below the first guide portion to move between a standby position and a support position, When the sheet received by the receiving portion is conveyed through the first guide portion, the control means moves the sheet support to the support position. The post-processing apparatus according to claim 1, characterized in that.

9. When the control means retracts the sheet reversely conveyed by the second conveying roller to the second retracting path via the second guide portion and the first guide portion, the control means moves the sheet support to the standby position. The post-processing apparatus according to claim 8, characterized in that.

10. The first guide portion is capable of a downward rotation operation when the sheet support is in the standby position. The post-processing apparatus according to claim 8, characterized in that.

11. The post-processing is a binding process. The post-processing apparatus according to claim 1, characterized in that.

12. The receiving portion receives the sheet discharged from the image forming apparatus. The post-processing apparatus according to claim 1, characterized in that.

13. The post-treatment device according to claim 1, wherein the conveyance path is substantially linear.

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