Sheet processing device and image formation system with sheet processing device

Abstract

To provide a sheet processing device that reduces the resistance against the shift movement of a sheet, which is caused by the leading edge of the sheet sagging down into the tray, when the leading edge of the sheet shifted on the transfer route reaches the tray.SOLUTION: The sheet processing device is equipped with control means that controls at least one of the side edge alignment plates forming a pair of side edge alignment plates so that at least one of the side edge alignment plates is positioned in a location that can come into contact with the inner side in the width direction of the sheet shifted by a shifting part.SELECTED DRAWING: Figure 42

Description

Technical Field

[0001] The present invention relates to a sheet processing apparatus capable of performing post-processing on an image-formed sheet and an image forming system including the sheet processing apparatus.

Background Art

[0002] A sheet post-processing apparatus is known as an apparatus that is connected to a 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. Patent Document 1 describes a sheet stacking apparatus capable of preventing misalignment when aligning a plurality of sheets stacked on a stacking tray. Further, as a basic function of a sheet post-processing apparatus, a shift function for sorting by sheet unit is well known. Patent Document 2 discloses a roller shift configuration for shifting a sheet on a conveyance path.

[0003] Further, Patent Document 3 discloses a processing tray for performing post-processing. This processing tray receives and accumulates sheets from above in order to accumulate the sheets coming out of the conveyance path by utilizing gravity.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a post-processing apparatus that shifts a sheet supplied from an image forming apparatus on a conveyance path, the leading edge of the shifted sheet may reach a processing tray. In that case, since the leading edge of the sheet droops and makes surface contact with the processing tray, it becomes a resistance when shifting.

[0006] An object of the present invention is to provide a sheet processing apparatus and an image forming system including the sheet processing apparatus that reduce the resistance during the shift movement caused by the leading edge of the sheet drooping onto the tray when the leading edge of the sheet shifted on the conveyance path reaches the tray.

Means for Solving the Problems

[0007] To solve the above problems, a sheet processing apparatus according to the present invention includes a conveyance path through which a sheet is conveyed from a loading port to an unloading port, a shift unit that shifts the sheet on the conveyance path in the width direction of the sheet, a tray that receives the sheet unloaded from the unloading port from above, a processing unit that performs processing on the sheet placed on the tray, a pair of side edge alignment plates provided on the tray for aligning the side edges in the width direction of the sheet before the processing by the processing unit, and control means for controlling at least one of the pair of side edge alignment plates to be positioned at a position where it can contact the inner side in the width direction of the sheet shifted by the shift unit.

Effects of the Invention

[0008] According to the present invention, when the leading edge of the sheet shifted on the conveyance path reaches the tray, it is possible to reduce the resistance during the shift movement caused by the leading edge of the sheet drooping onto the tray.

Brief Description of the Drawings

[0009]

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Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. It should be noted 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 to the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions 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 built in.

[0012] The paper feeding unit 2 includes cassette mechanisms 2a to 2c for storing sheets of a plurality of sizes to be image-formed, and feeds out a sheet of the size designated by the main body control unit 90 to the paper 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 sheets inside one by one and a paper feeding mechanism for feeding out the sheets. A conveying roller 7 for feeding the sheets supplied from the plurality of cassettes 2a to 2c to the downstream side is provided in the paper feeding path 6, and a registration roller pair 8 for aligning the leading ends of the sheets is provided at the end of the path.

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

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

[0015] The scanner unit A2 includes a platen 17 on which an image original is placed, 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 reflected light from the original on the platen 17 to the photoelectric conversion unit 19. The illustrated 21 is a second platen (running 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 subjected to photoelectric conversion to the image forming unit 3.

[0016] The 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 running platen 21, and a paper discharge tray 24 that stores the original on which image reading has been performed by the platen.

[0017] The image forming apparatus A is not limited to the above mechanisms, 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 Device] The sheet post-processing device B is a device that post-processes the sheets discharged from the paper discharge port 16 of the image forming device A. For example, it has (1) a function of stacking and storing the image-formed sheets (printout mode), (2) a function of sorting and storing the image-formed sheets (jogging sorting mode), (3) a function of collating, binding, and processing the image-formed sheets (binding process mode), and (4) a function of folding and finishing binding the image-formed sheets after collating and binding them (bookbinding process mode).

[0019] Note that in this embodiment, the sheet post-processing device B does not necessarily need to have all of the above functions and is appropriately configured according to the device specifications (design specifications). In this embodiment, as an example, it is assumed that the device has a function of folding and finishing binding the image-formed sheets after collating and binding them.

[0020] 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 the sheets carried in from the straight path inlet 26 connected to the paper discharge port 16 of the image forming device A and then stores them in a storage unit (the first stack tray 49, the second stack tray 61, and the third stack tray 71 described later). In the illustrated device, the sheets sent to the straight path 28 are 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"). Also, the sheets sent to the straight path 28 are 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, even thick paper can be conveyed.

[0021] The processing unit B1 is arranged at the path outlet of the straight path 28 (the straight path paper discharge port 35), aligns and stacks the sequentially fed sheets, performs binding processing, and then stores them in the first tray 49. The saddle unit B2 is arranged at the path outlet of the saddle path 32 branched from the straight path 28 (the saddle path paper discharge port), aligns and stacks the sequentially fed sheets, performs folding processing after middle binding (it may not be middle bound), and is a post-processing unit that stores them in the second tray 61. Hereinafter, each configuration will be described in detail.

[0022] <Device housing> As shown in FIG. 2, the sheet post-processing device B includes a device housing 27, a straight path 28 built inside the device housing and having a straight path inlet 26 and a straight path paper discharge port 35, a processing unit B1 for post-processing the sheets sent from the straight path 28, a saddle unit B2, a first tray 49, a second tray 61, and a third tray 71 for storing the sheets sent from each post-processing unit. The illustrated device housing 27 is arranged at substantially the same height dimension as the housing 1 of the image forming device A located on the upstream side, and the paper discharge port 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.

[0023] The housing 27 of the sheet post-processing device is configured to include a device frame 70. The device frame 70 forms a box-type device framework as shown in FIG. 6, for example, and includes a front side frame frame 70f located in the front in the state of FIG. 1, a rear side frame frame 70r located in the rear, and a stay member (connecting and reinforcing member) connecting between both side frame frames. The straight path 28, the processing unit B1, the saddle unit B2, etc. 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 left and right side frames and connecting stay structure, 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 transfer inlet (straight path inlet 26). In the straight path 28, a conveyance 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 conveyance roller 201, a second conveyance roller 202, and a third conveyance roller 203 are arranged. Further, at the straight path paper discharge port 35, a paper discharge roller 36 (including a sheet conveyance mechanism such as a belt) is arranged as a conveyance mechanism. That is, a plurality of rollers for conveying a sheet are arranged in the straight path 28. Also, the straight path 28 can be said to be the main conveyance path of the sheet formed from the straight path inlet 26, which is the sheet receiving port, to the straight path paper discharge port 35, which is the sheet discharge port. Further, near 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 conveyance direction are arranged. Also, near 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 Sheet Loading Path> In the straight path 28, as shown in FIGS. 2 and 3, from the straight path inlet 26 toward the straight path paper discharge port 35, the "saddle path 32", "saddle buffer path P2", "processing unit buffer path P1", and "upper conveyance path 30" are arranged in this order. At the branch portions with each of the above paths, as conveyance switching mechanisms (branch mechanisms) for the conveyed sheet, 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. 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 switchback paths for conveying the sheet in a direction opposite to the conveyance 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 conveyance 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 composed of flapper guides that are 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-mentioned 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 carries in sheets other than those discharged to the straight path discharge port 35. At the path branching portion, an upper conveyance path flapper 34 for guiding the sheet to the upper conveyance path 30 is provided. 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, 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. That is, the upper conveyance roller 303 is, in other words, a roller that conveys the sheet on the storage path.

[0029] <Saddle Path> The straight path 28 is connected to a saddle path 32 for carrying into the saddle section B2, and the path branching section is provided with a saddle path flapper 33b for guiding a sheet to the saddle path 32. The sheet guided from the saddle path 32 to the saddle section B2 via the saddle path paper discharge port is subjected to saddle stitching and folding processes, and then discharged to the second tray 61 via a 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 a sheet to be subjected to saddle stitching and folding processes in the saddle section B2, and a saddle buffer path flapper 33a for guiding a sheet to the saddle buffer path P2 is configured. Further, the saddle buffer path P2 is provided with conveying rollers 302 (302a, 302b) for carrying a sheet and temporarily waiting.

[0031] A fourth tray paper discharge port 305 is provided on the downstream extension of the saddle buffer path P2. Therefore, it is possible to discharge and stack the sheet carried into the saddle buffer path P2 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 an 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 movable up and down in a substantially vertical direction with a drive mechanism.

[0032] In addition, the device can be made more compact by disposing the saddle buffer path P2 at a position overlapping vertically above the punch unit 100. However, when a space for springing up the punch unit 100 upward is required to remove the sheet staying in the punch unit 100, the saddle buffer path P2 may be disposed 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 rollers 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. 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 and a transmission pinion 117b attached to the side frame frame 70r (apparatus frame; the same applies hereinafter). With such a configuration, it is 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 rotary shaft 115, and the rotation of the drive motor is transmitted to the driven gear 118. Further, a pair of conveying rollers (a drive roller and a driven roller) is pressed against the driven rotary shaft 119 so as to be driven to rotate by the rotation of the drive rotary shaft 115.

[0037] In this embodiment, the drive rotary shaft 115 and the driven rotary shaft 119 are connected to each other and are configured such that one of them is driven to move in the axial direction and the other follows. In addition, one of the drive roller 111 and the driven roller 112 may be attached to the rotary shaft so as to be slidable (slid) in the axial direction, and the other roller may be moved in the axial direction 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 device 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 at the same time. 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. 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, 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 arranged on the downstream side of the straight path 28 and aligns and stacks the sheets sent from the straight path paper discharge port 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 port 35 of the straight path 28, and the processing tray 37 is arranged 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 arranged 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 bridgely supports the sheets sent from the straight path paper discharge port 35 between the downstream first tray 49. That is, the sheet sent from the straight path paper discharge port is configured to be bridged and supported 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 arranged on the downstream side 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 intermediate binding processing.

[0044] The saddle part 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 part 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 part 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 part (line) of the sheet for the binding process. Also, 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 part B1 and the straight path 28 are arranged in a substantially horizontal direction, the saddle path 32 that guides the sheet to the saddle part 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 part B2 in the vertical direction, the apparatus can be made slim.

[0047] A second tray 61 is arranged on the downstream side of the saddle part 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 in a straight path 28 and punching punch holes in a sheet sent 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 the 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 drawing 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 device frame 70 (different from the unit frame) by a guide rail (not shown). Reference numeral 106 in the drawing is a rotary operation member, which forcibly rotates the drive cam when a jam occurs in the punch member 101 or 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 rotary operation member 106 is configured 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 "conveyance orthogonal direction") on the upper frame 102a so as to be reciprocable (vertically movable) in the punching direction. Punch 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 vertically moving each punch member 101 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 axially attached to the drive rotating shaft 107 and is composed of a cylindrical cam member corresponding to a plurality of punch members 101. Each punch member is connected to this cam member by a connecting pin. Then, by rotating 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 (for example, two-hole punching) of the plurality of punch members move 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) move 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 are 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 scrap 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 the operator can manually rotate it, and it is disposed on the front side of the side frame 70f. And a front cover is disposed on the front side of the apparatus so as to be openable and closable, and the rotation operation member 106 can be operated in the open lid state. Note that when the cover is in the open lid 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 feeding 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 conveying the sheet from the straight path paper discharge port 35 in the paper discharge direction and the opposite direction of the 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 rotation axis (for example, a paper discharge roller axis). The rotation axes 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 so 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 bundle of sheets 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 restricting 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, it guides the rear end of the sheet 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 restricting portion 38 that abuts and restricts 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-sided side reference) position.

[0063] As shown in FIG. 3, the sheet end restricting portion 38 is composed of a stopper member that abuts and restricts the rear end of the sheet. Also, although the side edge aligning member 39 will be described later with reference to FIG. 9, when the sheet is discharged 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-sided 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 restricting surface 39x that engages with the side edge of the sheet, and are arranged in a pair of left and right facing each other. And this pair of side edge aligning portions 39 are arranged on the processing tray 37 so as to be reciprocally movable 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 for laterally shifting (offset conveyance) the aligned sheet bundle in either the left or right direction.

[0065] That is, the moving strokes of the left and right side edge aligning plates 39F and 39R are set by the moving amount for aligning sheets of different sizes and the offset amount of the sheet bundle after alignment. Note that the side edge aligning plates 39F and 39R are moved by a predetermined amount to the right for right corner binding and to the left for left corner binding of the sheet carried out based on the center when 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 aligning unit 39 is configured to include a right side edge aligning member 39F (on the front side of the apparatus) and a left side edge aligning member 39R (on the rear side of the apparatus), and both side edge aligning members are supported on the processing tray 37 such that the regulating surfaces 39x that engage with the side ends of the sheet move in the approaching or separating direction from each other. The processing tray 37 is provided with a slit groove (not shown) penetrating the front and back, and the side edge aligning unit 39 having the 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 aligning 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 configured as stepping motors, and detect the positions of the left and right side edge aligning plates 39F and 39R with a position sensor (not shown), and are configured to be able to move each alignment member in either the left or right direction by a specified moving amount based on the detected value. Note that the present invention is not limited to the illustrated rack-pinion mechanism, and each side edge aligning plate 39F and 39R may be fixed to a timing belt and connected to a motor that reciprocates the timing belt in the left and right directions via pulleys.

[0068] With the above configuration, the binding process control unit 95, which will be 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, in the case of "multi-binding", a sheet is carried 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 in the opposite directions (approaching direction) by the same amount. Then, the sheet carried onto the processing tray 37 is positioned based on the sheet center and stacked in a bundle. By repeating this sheet carrying operation and alignment operation, the sheets are partially aligned and integrated in a bundle on the processing tray 37. At this time, sheets of different sizes are positioned based on the center reference. Also, in the case of "corner binding", a sheet is carried 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. And 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 in the apparatus frame 27b with a predetermined stroke SL1.

[0072] Fig. 9 shows the sheet carried into the processing tray 37 and the moving 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 with the center as the reference. 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 left side edge in the illustration) coincide with each other. For this purpose, 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, which will be described later, sets the moving 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, which will be described later, performs stitching processes other than stitching the sheet corners. For example, in the multi-stitching mode to be described later, the sheets are aligned with the center as the reference. In this case, the left and right side-edge alignment plates 39F and 39R move the same amount closer to the center of the sheet from the standby position to position the sheet at the stitching position.

[0074] Referring 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 both 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 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, the staple unit 47 is formed with ball-shaped sliding rollers 47x (two places shown in the figure) that engage with the support surface of the frame 27b. Further, the staple unit 47 is formed with a guide roller 47y that engages with the bottom surface of the bottom frame portion frame, 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 roller 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 sheet loading amount. For this reason, guide rollers 85 are provided at two locations, upper and lower, 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 an elevating gear 88 is provided at the base end portion of the first tray 49 and is connected to an elevating rack gear 87. Further, an elevating motor M4 is connected to the elevating gear 88. Therefore, by controlling the rotation of the elevating motor M4, the first tray 49 moves up and down according to the sheet loading amount.

[0081] <Sheet Bundle Unloading Mechanism> The processing tray 37 is provided with a sheet bundle unloading mechanism for unloading the stapled sheet bundle toward the downstream first tray 49. As a configuration for conveying the sheet bundle downstream, a method of conveying with a pair of rollers that are in pressure contact with each other (unloading 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 are known. The illustrated apparatus employs both of them.

[0082] FIG. 12 shows the sheet bundle unloading mechanism. The conveyor mechanism is configured to include an extrusion protrusion 45 that transfers 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 unloading 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 unloading roller mechanism.

[0083] Therefore, the processing tray 37 is provided with a conveyor mechanism 45, 45v for transferring the sheet bundle so as to be pushed out from the upstream side to the downstream side, and an unloading roller mechanism 48, 41 for nipping and unloading 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 unloading 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 unloading roller mechanism 48, 41. FIG. 12(c) shows a state immediately before unloading the sheet bundle to the downstream first tray 49. On the processing tray, the sheet bundle is gradually (at a low speed) sent downstream by the rotation of the unloading 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] A staple head 47b and an anvil member 47c are disposed opposite to each other at the stitching position on the drive cam 47d. The staple head 47b is biased from an upper standby position to a lower staple position (anvil member) by a biasing spring (not shown) on the drive cam 47d and moves up and down. 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 the linear needle into a U-shape inside, and a driver for press-fitting 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. When the rotation angle reaches a predetermined angle, the staple head portion 47b rapidly descends toward the anvil member 47c. In this operation, the staple needle is bent into a U-shape and then pierced into the sheet bundle by the driver. Then, its tip is bent by the anvil member 47c to be stapled.

[0087] 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 disposed in the needle feeding mechanism. A cartridge sensor (not shown) for detecting whether the needle cartridge 52 is inserted is disposed on the unit frame 47a.

[0088] The staple cartridge 52 is structured to store staple pins connected in a strip-like manner in a box-shaped cartridge in a stacked manner or to store them 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 the 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 then 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 information, 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 above post-processing mode, the "printout mode" is a mode in which the sheets from the straight path paper discharge port 35 are accommodated in the stack tray 49 via the processing tray 37 without being bound. 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 the job end signal from the main control unit 90.

[0093] The "product processing paper discharge mode" is a mode in which the image-formed 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, and after binding this sheet bundle, it is accommodated in the stack tray 49. In this case, the sheets to be image-formed 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, any one of "multi-binding", "right corner binding", and "left corner binding" is selected and specified.

[0095] In the " jog sorting mode", the sheets image-formed by the image forming apparatus A are divided into a group that is offset and accumulated and a group that is accumulated without being offset. In the stack tray, the sheet bundles that are alternately offset and the sheet bundles that are not offset 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 the present 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] <Sheet buffer operation> The outline of the sheet buffer operation in the sheet processing apparatus B will be described. While the alignment of the sheet bundle is being performed in the side edge alignment unit 39, image formation is continuously performed by the image forming apparatus A, and sheets are supplied to the sheet processing apparatus B. The side edge alignment unit 39 needs to move to the initial position after performing side edge alignment on one sheet bundle. Therefore, for example, before the side edge alignment of the sheet bundle is completed by the side edge alignment unit 39, the next sheet bundle may be discharged to the first tray 49.

[0098] Therefore, in the present embodiment, a buffer operation is performed to store the sheets conveyed from the image forming apparatus A in the sheet processing apparatus B. Thereby, it is possible to continuously perform the post-processing until the discharge of the sheet bundle without reducing the frequency of sheet supply from the image forming apparatus A, that is, without reducing the productivity of the image forming apparatus A.

[0099] Hereinafter, with reference to FIGS. 15(A) to 40(B), the sheet buffer process will be described. Each of FIGS. 15(A) to 38(B) shows a cross-sectional view seen from the side direction of the sheet processing apparatus B and a perspective view of the arrangement of the roller pairs of the sheet processing apparatus B. Further, each of FIGS. 39(A) to 40(B) shows a cross-sectional view seen from the side direction of the sheet processing apparatus B and a plan view of the first tray 49 for explaining the alignment of the sheets by the side edge alignment unit 39. Further, hereinafter, the first conveyance roller 201 and the second conveyance roller 202 will be referred to as the shift roller 201 and the shift roller 202. The shift rollers 201 to 202 are rollers that can be shifted as described above.

[0100] In addition, in each of the following figures, the arrow X indicates the conveyance direction toward the sheet discharge side (paper discharge side) in the straight path 28, the arrow Y indicates the side direction of the sheet processing apparatus B, and the arrow Z indicates the height direction of the sheet processing apparatus B. In other words, the side direction of the sheet processing apparatus B is a direction that intersects the sheet conveyance direction.

[0101] Also, in this embodiment, for example, a case where a buffer operation is performed on a thick paper sheet supplied from the image forming apparatus A will be described as an example. A thick paper is, for example, a sheet that is thicker and has higher rigidity than plain paper. The thick paper may be, for example, a sheet with a coating on its surface. Specifically, the thick paper may be, for example, a sheet with a basis weight of 300 g / m 2 or more. Also, the operation of this embodiment may be applied to sheet types other than thick paper.

[0102] By the way, during the buffer operation, the position of the sheet bundle may be adjusted inside the sheet processing apparatus B and discharged to the first tray. When the sheet processing apparatus B is operated in the jog sorting mode described above, the position of the sheet bundle is adjusted by shifting the positions of the sheets conveyed from the image forming apparatus A in a direction intersecting the sheet conveyance direction inside the sheet processing apparatus B. For example, inside the post-processing apparatus B, an upper conveyance path 30 for retracting the sheet as described above is provided. In this way, the post-processing apparatus B has a conveyance path that is curved from the straight path 28 to the upper conveyance path 30. In such a curved conveyance path, when shifting the position of a sheet of a high-rigidity sheet type such as thick paper, the sheet may contact the roll disposed in the conveyance path due to the rigidity of the sheet. When the sheet contacts the roll, scratches, wrinkles, twists, inclination of the sheet, etc. may occur due to rubbing between the sheet and the roll, resulting in a deterioration in the quality of the discharged sheet bundle.

[0103] Therefore, in a curved (arc (R) shaped) conveyance path, even when shifting the position of a high-rigidity sheet during sheet buffering processing, a device for preventing a deterioration in the quality of the sheet bundle is required.

[0104] In the present embodiment, among a pair of rollers arranged on a curved conveyance path, the roller located outside the curved portion of the conveyance path is separated. Further, a configuration will be described in which the position of the sheet is shifted by a shift roller in a state where the roller located outside the curved portion of the conveyance path is separated. With such a configuration, even when shifting the position of a sheet with high rigidity during sheet buffer processing in a curved conveyance path, it is possible to prevent the quality of the sheet bundle from deteriorating.

[0105] Further, in the present embodiment, as an example, a case where jog sorting is performed on a thick paper sheet will be described.

[0106] First, refer to FIGS. 15(A) and 15(B). FIGS. 15(A) and 15(B) show a state in which the next sheet S1 discharged from the image forming apparatus A is received from the straight path entrance 26 and conveyed to the entrance roller 29 and the shift roller 201 of the post-processing apparatus B. The straight path entrance 26 is, in other words, an entrance for receiving a sheet from the outside.

[0107] FIG. 15(A) shows a state in which the preceding sheet bundle SS1 is discharged from the inside of the post-processing apparatus B. Also, in FIG. 15(A), the sheet support 401 has moved to the side of the processing unit buffer path flapper 200 and is in a position to support the sheet S1 being conveyed. In the present embodiment, the position where the sheet support 401 supports the sheet being conveyed is referred to as the support position.

[0108] In FIG. 15(B), the center line L-L is shown as an auxiliary line. The center line L-L is an auxiliary line for indicating the state where the shift rollers 201 to 202 are shifted or not shifted. Also, the position of the shift rollers 201 to 202 before shifting shown in FIG. 15(B) may be referred to as the initial position, and the position where the shift rollers 201 to 202 described later are shifted in the direction (Y direction) intersecting the conveyance direction may be referred to as the shift position.

[0109] Figures 16(A) and 16(B) show the state where the sheet S1 has been conveyed to the third conveyance roller 203. Figure 16(A) shows the state where the preceding sheet bundle SS1 has been discharged from the inside of the sheet processing device B to the first tray 49 and is aligned by the side edge alignment unit 391. Also, in Figure 16(A), the upper conveyance path flapper 34 is in the lowered state. Thereby, the sheet S1 is conveyed in the direction from the straight path 28 to the upper conveyance path 30 as will be described later. That is, the upper conveyance path flapper 34 can also be said to be a switching member that switches the conveyance path of the sheet between the straight path 28 and the upper conveyance path 30. Further, the sheet S1 is supported from below by the sheet support 401.

[0110] Figures 17(A) and 17(B) show the state where the sheet S1 is being conveyed on the upper conveyance path 30. When the preceding sheet bundle SS1 is being discharged from the straight path discharge port 35 or when the sheet bundle SS1 is aligned by the side edge alignment unit 391, the sheet S1 being conveyed on the straight path 28 is retracted to the upper conveyance path 30 side. By performing such a buffer operation of retracting the sheet, it is possible to continuously perform the process from the post-processing to the discharge of the sheet bundle without reducing the supply frequency of the sheet from the image forming apparatus A.

[0111] Also, as shown in Figure 17(A), the upper conveyance path 30 is provided on one side with the straight path 28 as a boundary. One side is the upper side with the straight path 28 as a boundary in the height direction of the post-processing device B. In other words, the upper conveyance path 30 is a conveyance path extending in the height direction of the post-processing device B. Thus, since the upper conveyance path 30 extends in the height direction of the post-processing device B, it is possible to perform the buffer operation of the sheet without increasing the size of the post-processing device B.

[0112] Figures 18(A) and 18(B) show a state in which a predetermined roller located on a curved path in the conveyance path of the sheet S1 is separated to shift the conveyance position of the sheet S1. As shown in FIG. 18(A), the upper conveyance path 30 has a curved portion R. The curved portion R is a curved part of the upper conveyance path 30. Further, the upper conveyance path 30 is connected to the straight path 28 via the curved portion R. The upper conveyance roller 303 is located at the curved portion R of the upper conveyance path 30. That is, FIGS. 18(A) and 18(B) show a state in which the outer roller 303b disposed on the outer side of the curvature of the curved portion R among the pair of separable upper conveyance rollers 303 is separated. Specifically, with respect to the pair of upper conveyance rollers 303, the outer roller 303b is moved without moving the inner roller 303a disposed on the inner side of the curvature, thereby separating the upper conveyance rollers 303 from each other.

[0113] By separating the outer roller 303b disposed on the outer side of the curvature in this way, it is possible to prevent the sheet S1, which is a highly rigid sheet such as cardboard, from contacting the roller 203b due to its rigidity. Therefore, when the shift rollers 201 to 202 described later are shifted, it is possible to prevent the sheet S1 from being wrinkled or twisted due to contact with the roller 203b. That is, it is possible to prevent the quality of the sheet bundle from deteriorating. Further, FIGS. 18(A) and 18(B) show a state in which the roller 203b provided on the other side with the straight path 28 as a boundary among the pair of separable third conveyance rollers 203 is separated. The other side is the lower side of the straight path 28 in the height direction of the post-processing device B. The third conveyance roller 203 is a pair of rollers disposed upstream of the upper conveyance path flapper 34 and downstream of the shift roller 202. Specifically, with respect to the pair of third conveyance rollers 203, the roller 203b is moved without moving the roller 203a provided on the upper side with the straight path 28 as a boundary, thereby separating the third conveyance rollers 203 from each other. In this way, by separating the roller 203b, it is possible to prevent the sheet S1 from contacting the roller 203b when the shift rollers 201 to 202 described later are shifted.

[0114] Also, by separating the outer roller 303b and the roller 203b in this way, the shift rollers 201 to 202 described later can shift the sheet S1 in a direction intersecting the conveyance direction while nipping the sheet S1.

[0115] Also, by separating the outer roller 303b and the roller 203b in this way, a mechanism for shifting the upper conveyance roller 303 and the third conveyance roller 203 becomes unnecessary. As a result, the degree of freedom in the internal design of the post-processing device B can be increased, and the device cost can also be suppressed.

[0116] Also, the surfaces of the third conveyance roller 203 and the upper conveyance roller 303 may include, for example, a member having viscoelasticity. Specifically, for example, the surface of the upper conveyance roller 303 may be covered with a rubber member. Since the surfaces of the third conveyance roller 203 and the upper conveyance roller 303 are members having viscoelasticity, it becomes difficult for the sheet to slip on the rollers. As a result, it becomes easier to convey the sheet. Also, even when using such rollers, by separating the outer rollers 203b and 303b outside the inner side of the curved portion R, contact between each roller and the sheet can be prevented. Note that the present invention is not limited to the third conveyance roller 203 and the upper conveyance roller 303, and the surfaces of other rollers shown in the figure may also be made of rubber.

[0117] In FIGS. 19(A) and 19(B), shift rollers 201 to 202 are shown in a state where they have shifted in a direction intersecting the conveyance direction along the straight path 28 while nipping the sheet S1. The shift by the shift rollers 201 to 202 is performed in a state where the sheet S1 conveyed to the upper conveyance path 30 side straddles the upper conveyance path 30 and the straight path 28. In other words, the upper conveyance path 30 side is the retraction path side provided above with the main conveyance path (straight path 28) as a boundary. Further, for example, the shift rollers 201 to 202 may stop rotating during the shift. Also, when the shift rollers 201 to 202 shift, as described above, the outer roller 303a and the roller 203a are in a separated state. Thereby, it is possible to prevent the sheet S1 from coming into contact with the roller 203b or the outer roller 303b and causing wrinkles or twists. In the following description, the direction in which the shift rollers 201 to 202 shift may be referred to as the Y direction.

[0118] FIGS. 20(A) and 20(B) show a state where the third conveyance roller 203 and the upper conveyance roller 303 resume nipping the sheet S1 and convey the sheet S1 to the upper conveyance path 30. Specifically, after the shift rollers 201 to 202 shift in the Y direction, the pair of upper conveyance rollers 303 bring the outer roller 303b close to the inner roller 303a disposed on the inner side of the curvature of the curved portion R. Also, after the shift of the shift rollers 201 to 202, the pair of third conveyance rollers 203 bring the roller 203b disposed below the straight path 28 close to the roller 203a disposed above the straight path 28. Further, the upper conveyance roller 303 and the third conveyance roller 203 convey the sheet S1 to the upper conveyance path 30. As shown in FIG. 20(B), the sheet S1 is conveyed to the upper conveyance path 30 in a state of having shifted in the Y direction.

[0119] Figures 21(A) and 21(B) show the state in which the sheet S1 is being conveyed on the upper conveyance path 30. As shown in Figure 21(A), after the sheet S1 passes through the shift rollers 201 to 202, the sheet support 401 moves downward from the support position. In the following description, the position of the sheet support 401 shown in Figure 21(A) may be referred to as the retracted position. As shown in Figure 21(B), after the sheet S1 passes through the shift rollers 201 to 202, the shift rollers 201 to 202 move to the initial position. Also, the sheet S1 is being conveyed on the upper conveyance path 30 in a state where it has been shifted in the Y direction.

[0120] Figure 22(A) shows the state in which the processing unit buffer path flapper 200 has descended. After the sheet S1 has retracted to the upper conveyance path 30, the processing unit buffer path flapper 200 descends to the processing unit buffer path P1 side. As a result, the sheet S1 that has retracted to the upper conveyance path 30 can be conveyed to the processing unit buffer path P1 side. That is, the processing unit buffer path flapper 200 can also be said to be a switching member that switches the conveyance path of the sheet between the straight path 28 and the processing unit buffer path P1. Figure 22(B) shows the state in which the rear end of the sheet S1 has moved to the processing unit buffer path P1 side.

[0121] Figures 23(A) and 23(B) show the state in which the sheet S1 is being conveyed on the processing unit buffer path P1. After the sheet S1 has retracted to the conveyance path 30, the rotation directions of the upper conveyance roller 303 and the third conveyance roller 203 are reversed, so that the sheet S1 is reversely conveyed to the processing unit buffer path P1 side. Also, the sheet S1 that has been reversely conveyed to the processing unit buffer path P1 side is conveyed below the processing buffer path P1 by the processing unit buffer roller 301.

[0122] Further, as shown in FIG. 23(A), the processing unit buffer path P1 is provided on the other side with the straight path 28 as a boundary. The other side is the lower side with the straight path 28 as a boundary in the height direction of the post-processing device B. The processing unit buffer path P1 is a conveyance path that extends downward in the height direction of the post-processing device B. In this way, since the processing unit buffer path P1 extends downward in the height direction of the post-processing device B, the buffer operation of the sheet can be performed without increasing the size of the post-processing device B. Further, FIG. 21(B) shows a state in which the sheet S1 is being conveyed to the processing unit buffer path P1 while being shifted in the Y direction.

[0123] FIGS. 24(A) and 24(B) show a state in which the sheet S1 conveyed to the processing unit buffer path P1 is stationary. The processing unit buffer roller 301 stops rotating while nipping the sheet S1.

[0124] FIG. 25(A) shows a state in which the processing unit buffer path flapper 200 is open. FIG. 25(B) shows a state in which the processing unit buffer roller 301 has stopped rotating while nipping the sheet S1.

[0125] FIGS. 26(A) and 26(B) show a state in which the next sheet S2 discharged from the image forming apparatus A has been conveyed to the shift roller 202 of the sheet processing apparatus B. In the present embodiment, a case where the sheet S2 is a sheet in the middle of a sheet bundle including the sheet S1 will be described as an example. The middle sheet is a sheet between the first sheet S1 of the sheet bundle and the last sheet S3 described later. As shown in FIG. 26(A), in order for the sheet S2 to pass through the straight path 28, the processing unit buffer path flapper 200 is open. Further, in order to support the sheet S2, the sheet support 401 has moved to the support position. Further, for example, the processing buffer roller 301 may start conveying the sheet S1. For example, the processing unit buffer roller 301 may reverse the rotation direction while nipping the sheet S1 and convey the sheet S1 that has been retracted to the processing unit buffer path P1 to the straight path 28 side.

[0126] Figures 27(A) and 27(B) show the state in which sheets S1 to S2 are conveyed to the upper conveyance path 30 in a merged state. That is, sheet S1 is conveyed to the upper conveyance path 30 in synchronization with the conveyance operation of sheet S2 to the upper conveyance path 30. Also, as shown in Figure 27(B), sheets S1 to S2 are merged in a state shifted in the Y direction.

[0127] Figures 28(A) and 28(B) show a state in which a predetermined roller located at the curved portion R of the conveyance path is separated in the conveyance paths of sheets S1 to S2. Specifically, it shows a state in which one of the pair of third conveyance rollers 203, roller 203b, is separated, and a state in which the outer roller 303b of the pair of upper conveyance rollers 303 is separated. Note that the separation of roller 203b and outer roller 303b is the same as the explanation in Figures 18(A) and 18(B), so the explanation is omitted. As shown in the figure, by separating roller 203b and outer roller 303b, the position of sheet S2 can be shifted as described later.

[0128] Figures 29(A) and 29(B) show a state in which the shift rollers 201 to 202 are shifted in the Y direction while nipping sheet S2. As a result, sheet S2 is shifted in the Y direction in a state straddling the upper conveyance path 30 and the straight path 28. As shown in Figure 29(B), when the shift rollers 201 to 202 are shifted, roller 203b and roller 303b are in a separated state. Thereby, sheet S2 can be shifted in the Y direction in the same manner as sheet S1. Also, since roller 203b and roller 303b are in a separated state, a gap is generated between sheet S1 and sheet S2. From this, when shifting sheet S2, it is possible to prevent rubbing between sheet S1 and sheet S2.

[0129] Figures 30(A) and 30(B) show the state in which sheets S1 to S2 are being conveyed on the upper conveyance path 30 in an overlapping state. The third conveyance roller 203 and the upper conveyance roller 303 restart the nip of the sheets S1 to S2 and convey the sheets S1 to S2 on the upper conveyance path 30. Further, as shown in FIG. 30(A), the sheet support 401 moves to the retracted position. When the sheet support 401 moves to the retracted position, the processing unit buffer path flapper 200 can rotate downward. As a result, after the sheets S1 to S2 are conveyed to the upper conveyance path 30, the sheets S1 to S2 can be guided to the processing unit buffer path P1. As shown in FIG. 30(B), the sheets S1 to S2 are conveyed on the upper conveyance path 30 in a state shifted in the Y direction.

[0130] Figures 31(A) and 31(B) show the state in which the sheets S1 to S2 are conveyed to the upper conveyance path 30. FIG. 31(A) shows the state in which the processing unit buffer path flapper 200 is lowered to convey the sheets S1 to S2 to the processing unit buffer path P1. Thereby, the conveyance path of the sheets S1 to S2 can be switched from the straight path 28 to the processing unit buffer path P1. Further, FIG. 31(B) shows the state in which the rear ends of the sheets S1 to S2 are lowered to the processing unit buffer path P1 side due to the lowering of the processing unit buffer path flapper 200. Also, the shift rollers 201 to 202 are in the state of having moved to the initial position.

[0131] Figures 32(A) and 32(B) show the state in which the sheets S1 to S2 are conveyed to the processing unit buffer path P1. Also, FIGS. 32(A) and 32(B) show the state in which the next sheet S3 discharged from the image forming apparatus A is conveyed to the entrance roller 29 and the shift roller 201 of the sheet processing apparatus B. Further, the processing unit buffer roller 301 stops rotating while nipping the sheets S1 to S2. In the present embodiment, the case where the sheet S3 is the last sheet of the sheet bundle will be described as an example.

[0132] Figures 33(A) and 33(B) show the state where the leading edge of sheet S3 has passed through the shift roller 202. Also, as shown in Fig. 33(A), the upper conveyance path flapper 34 and the processing unit buffer path flapper 200 switch the conveyance path so as to convey sheet S3 to the straight path 28. Specifically, the upper conveyance path flapper 34 and the processing unit buffer path flapper 200 are in the raised state respectively. Also, in order to support sheet S3, the sheet support 401 has moved to the support position. Further, the processing unit buffer roller 301 reverses the rotation direction while nipping sheets S1 - S2, and conveys sheets S1 - S2 that had been retracted to the processing unit buffer path P1 to the straight path 28 side.

[0133] Figures 34(A) and 34(B) show the state where sheets S1 - S3 merge at the straight path 28. As shown in Fig. 34(A), since the upper conveyance path flapper 34 is in the raised state, sheets S1 - S3 are not conveyed to the upper conveyance path 30, but are conveyed through the straight path 28 to the straight path discharge port 35 side. Sheets S1 - S2 are conveyed to the straight path 28 in synchronization with the conveyance operation of sheet S3 to the straight path 28. Also, Fig. 34(B) shows that sheets S1 - S2 and sheet S3 are being conveyed in a state shifted from each other in the Y direction.

[0134] Figures 35(A) and 35(B) show the state where a plurality of rollers are separated in order to shift sheet S3. Specifically, among the roller pairs of the lifting roller 41 and the driven roller 201, the lifting roller 41 is separated. Also, among the pair of discharge rollers 36, roller 36a is separated. Further, among the third conveyance rollers 203, roller 203b is separated. Thus, by separating the lifting roller 41 and roller 36a, which are downstream of the third conveyance roller 203 and arranged above with the straight path 28 as the boundary, it is possible to prevent the sheet from loosening.

[0135] Figures 36(A) and 36(B) show the state in which the sheet S3 is shifted in the Y direction on the straight path 28. That is, the sheet S3 is shifted in the Y direction by the shift rollers 201 to 202 on the main conveyance path. As shown in FIG. 36(B), when the shift rollers 201 to 202 move to the shift position, the sheet S3 overlaps with the sheets S1 to S2.

[0136] Figures 37(A) and 37(B) show the state in which the lifting roller 41, the paper discharge roller 36, and the third conveyance roller 203 nip the sheets S1 to S3.

[0137] Figures 38(A) and 38(B) show the state in which the sheet bundle SS2 is discharged onto the first tray 49. The sheet bundle SS2 is a bundle in which the sheets S1 to S3 overlap. As shown in FIG. 38(A), the roller pair of the lifting roller 41 and the driven roller 201 located on the straight path discharge port 35 side is arranged inclined with respect to the straight path 28. This inclination corresponds to the angle of the first tray 49. Thereby, when discharging the sheets S1 to S3 onto the first tray 49, it is possible to prevent the leading edge of the sheet bundle SS2 from colliding with the inclined surface of the first tray 49 and causing wrinkles or twists in the sheet bundle SS2.

[0138] Figures 39(A) and 39(B) show the state in which the sheet bundle SS2 is discharged onto the first tray 49. FIG. 39(B) corresponds to a view taken in the direction of arrow D1 in FIG. 39(A). The first tray 49 is, in other words, a stacking tray for stacking the sheet bundle carried out from the straight path discharge port 35. Each of the sheets S1 to S3 of the sheet bundle SS2 is shifted in the Y direction with respect to the conveyance direction by the shift by the shift rollers 201 to 202 as described above. As a result, the sheet bundle SS2 is discharged onto the first tray 49 in a state shifted in the Y direction with respect to the SS1 discharged earlier as shown in FIG. 39(B). Also, displacement may occur between the sheets S1 to S3 of the sheet bundle SS2. For this reason, as will be described later, the side edges of the sheets S1 to S3 of the sheet bundle SS2 are aligned by the side edge alignment portion 391.

[0139] Figures 40(A) and 40(B) show a state where the sheet bundle SS2 discharged onto the first tray 49 is aligned by the side-edge alignment unit 391. Figure 39(B) corresponds to a view taken in the direction of arrow D1 in Figure 39(A). As shown in Figure 40(A), when the sheet bundle SS2 is discharged onto the first tray 49, the side-edge alignment unit 391 descends and taps the side edges of the sheet bundle SS2 to align the sheet bundle SS2. Thereby, even when a shift occurs between the sheets S1 to S3 of the sheet bundle SS2, for example, when discharging onto the first tray 49, both ends of the sheet bundle SS2 can be aligned.

[0140] As described above, according to the present embodiment, a buffer operation is performed to store the sheets conveyed from the image forming apparatus A in the sheet processing apparatus B. Thereby, without reducing the frequency of sheet supply from the image forming apparatus A, that is, without reducing the productivity of the image forming apparatus A, it is possible to continuously perform the processes from post-processing to discharging the sheet bundle.

[0141] Further, in the present embodiment, among the roller pairs arranged on the curved conveyance path, the rollers located outside the curved portion of the conveyance path are separated. Also, with the rollers located outside the curved portion of the conveyance path separated, the position of the sheet is shifted. In such a configuration, even when a sheet with high rigidity is retracted and shifted on the curved conveyance path during the sheet buffer process, it is possible to prevent the quality of the sheet bundle from deteriorating.

[0142] In this example, the case where the number of sheets in the sheet bundle SS2 is three sheets S1 to S3 has been described, but it is not limited to this. The number of sheets in the sheet bundle SS2 may be, for example, more than three or less than three. Also, in this example, the sheet bundles SS1 and SS2 have been described as an example, but for example, even when the next sheet S4 (not shown) is being conveyed inside the post-processing apparatus B during the discharge of the sheet SS2.

[0143] The curvature of the curved conveyance path in this embodiment is for thick paper with high rigidity (300 g / m 2 to basis weight 500 g / m 2) is set to about 125R to 100R (radius 125 mm to 100 mm), which is the minimum value that can be conveyed. However, it is also effective when conveying a sheet with a basis weight outside this range or using it in a curved conveyance path with a curvature outside this range.

[0144] As described above, the buffer operation for storing the sheet supplied from and received by the image forming apparatus A in the sheet processing apparatus B has been explained. In the above-described configuration, when the binding process by the binding unit 47 is not performed, the sheet conveyed from the image forming apparatus A is discharged directly from the straight path 28 to the first tray 49 without being buffered in the upper conveyance path 30 and the processing unit buffer path P1. Hereinafter, such a case will be described. In such a case, for example, a large-size sheet S4 that is long in the conveyance direction and conveyed from the image forming apparatus A is discharged directly from the straight path 28 to the first tray 49. Such a case will be described below.

[0145] In the sheet processing apparatus B, a processing tray 37 is disposed below the paper discharge roller 36 with a step formed therebetween. The processing unit B1 may be configured to be capable of accommodating a sheet bundle composed of a large number of sheets, for example, 100 sheets. In that case, the drop of the sheet conveyed through the straight path 28 to the processing tray 37 becomes large, and the leading end of the sheet may be rounded as it drops onto the processing tray 37, which may cause a jam.

[0146] Incidentally, when the processing unit B1 is configured to be able to accommodate a sheet bundle composed of a large number of sheets as described above, the side edge alignment plates 39F and 39R of the side edge alignment unit 39 are also configured to be tall so as to be able to align both side surfaces of a sheet bundle composed of such a large number of sheets. Such side edge alignment plates 39F and 39R may be used as a sheet support capable of supporting the sheet conveyed from the straight path 28 from below. That is, the side edge alignment plates 39F and 39R are moved so as to be narrower than the width of the sheet conveyed from the straight path 28 and so that the centers of the side edge alignment plates 39F and 39R coincide with the center of the sheet width. With such a configuration, the drop between the paper discharge roller 36 and the processing tray 37 can be filled by the side edge alignment plates 39F and 39R, and the occurrence of rounding of the leading edge of the sheet due to the fall of the sheet as described above can be prevented.

[0147] Here, in the above case, it is assumed that the sheet supplied from the image forming apparatus A is shifted by the shift rollers 201 and 202 in the jog sorting mode and discharged to the first tray 49. In that case, the centers of the side edge alignment plates 39F and 39R are displaced from the center of the sheet width, and the side surface of the sheet comes off the side edge alignment plate and hangs downward. As a result, rounding of the sheet may occur, which may cause a jam.

[0148] Therefore, in the present embodiment, when the sheet supplied from the image forming apparatus A is shifted by the shift rollers 201 and 202, the side edge alignment plates 39F and 39R are also moved in the same direction as the shift direction. With such a configuration, it is possible to prevent the side surface of the sheet from coming off the side edge alignment plate and hanging downward. Further, the side edge alignment plates 39F and 39R are moved in synchronization with the shift operation of the shift rollers 201 and 202. With such a configuration, it is possible to prevent the printed surface of the sheet (corresponding to the lower surface of the sheet because the face is down) from rubbing against the side edge alignment plates 39F and 39R.

[0149] Hereinafter, with reference to FIGS. 41 to 44, the sheet conveyance operation in the above case will be described.

[0150] FIG. 41 shows a state before the sheet S4 is supplied from the image forming apparatus A. The side edge alignment plates 39F and 39R are first positioned at an interval wider than the sheet width of the sheet S4 (first position). The first position is, for example, the standby position of the side edge alignment plates 39F and 39R. Then, as shown in FIG. 42(b), the side edge alignment plates 39F and 39R move to a position (second position, first support position) narrower than the sheet width of the sheet S4 supplied from the image forming apparatus A. In this case, the side edge alignment plates 39F and 39R are positionally moved toward the sheet center by the same amount from the first position. Note that the dashed-dotted line in FIGS. 42(b), 43(b), and 44(b) is an auxiliary line representing the center of the conveyance path. FIG. 42(b) shows a state where the center of the sheet width coincides with the center of the conveyance path.

[0151] FIG. 42(a) shows a state where the sheet S4 is supplied from the image forming apparatus A and the leading edge of the sheet has passed through the discharge roller 36 through the straight path 28. At this time, the leading edge of the sheet S4 will be supported by the side edge alignment plates 39F and 39R, and it is possible to prevent the leading edge of the sheet from drooping onto the processing tray 37. Also, in order to enable the shift operation of the shift rollers 201 and 202, the nip states of the third conveyance roller 203, the discharge roller 36, and the elevating roller 41 are released and they are in a separated state.

[0152] FIG. 42(b) is a view of the state of FIG. 42(a) seen from above. As shown in FIG. 42(b), the centers of the side edge alignment plates 39F and 39R and the center of the sheet width are constant.

[0153] Figure 43(a) shows the state where the shift operation of the shift rollers 201 and 202 is performed. In this example, as shown in Figure 43(b), the shift operation is performed downward (the front direction in Figure 43(a)) in Figure 43(b). At this time, the side edge alignment plates 39F and 39R move in synchronization with the shift operation of the shift rollers 201 and 202. In other words, the side edge alignment plates 39F and 39R move in the same direction at the same speed as the shift rollers 201 and 202. Furthermore, in other words, the positional relationship of the side edge alignment plates 39F and 39R with respect to the center of the sheet width is maintained before and after the shift operation of the shift rollers 201 and 202. Therefore, even when the shift operation is performed, it is possible to prevent the leading edge of the sheet from coming off the side edge alignment portion and hanging downward. Also, since the side edge alignment plates 39F and 39R move in synchronization with the shift operation of the shift rollers 201 and 202, it is possible to prevent the printing surface of the sheet S4 from rubbing against the side edge alignment plates. After the shift operation, each of the third conveying roller 203, the paper discharge roller 36, and the lifting roller 41 returns to the nip state again.

[0154] Figure 44(a) shows the state where the sheet S4 is discharged to the first tray 49 through the paper discharge roller 36. Thereafter, the shift rollers 201 and 202 and the side edge alignment plates 39F and 39R return to the positions before the shift operation. That is, the side edge alignment plates 39F and 39R return from the positions (the third position, the second support position) where they moved along with the shift operation of the shift rollers 201 and 202 to the first position. At this time, the movement of the shift rollers 201 and 202 and the movement of the side edge alignment plates 39F and 39R may or may not be synchronized. However, when the rear end of the sheet passes through the nip point of the shift roller while the sheet is passing over the side edge alignment plate, returning the shift roller to the first position first enables the preparation for receiving the next sheet to be conveyed to be completed earlier, thus enhancing productivity.

[0155] After delivering the leading edge of the sheet S4 to the discharge roller, when a sheet that is continuously shifted and conveyed comes, the side edge alignment plates 39F and 39R are moved to the second position located inside the side edges of the next sheet in order to support the next sheet to be conveyed after the sheet S4.

[0156] Note that the positions (the second position, the first support position) of the side edge alignment plates 39F and 39R when supporting the sheet S4 are determined from the deviation amount in the width direction (about 5 mm) + the deviation amount due to skew (about 5 mm) + the paper width standard (sheet size tolerance). With respect to the paper width, both side edge alignment plates are positioned about 10 mm to 50 mm inward. At this time, when the paper width is narrow or wide and there is a possibility of contacting the paper end face considering each deviation amount, the side edge alignment plates 39F and 39R are moved to positions (outer side) where they do not contact the sheet.

[0157] In this embodiment, the problems occurring when shifting a sheet having a length equal to or longer than a predetermined length at which the sheet leading end reaches the processing tray 37 when shifting the sheet S4 with the shift rollers 201 and 202 have been described. Conversely, when shifting a sheet shorter than a predetermined length at which the sheet leading end does not reach the processing tray 37 when shifting the sheet with the shift rollers 201 and 202, there is no necessity to perform synchronous control of the side edge alignment plates, and the shift movements of the shift rollers and the side edge alignment plates may be synchronized, or the side edge alignment plates may be positioned in advance at the positions at the completion of shifting inside the sheet width direction.

[0158] Also, in this embodiment, the optimal form in which both of a pair of side edge alignment plates are moved has been described, but the same effects can be obtained in different embodiments shown in FIGS. 45 and 46 as other embodiments. Hereinafter, another embodiment will be described.

[0159] FIG. 45(a) shows a state in which the sheet S4 is supplied from the image forming apparatus A and the leading end of the sheet has passed through the straight path 28 and passed through the paper discharge roller 36. At this time, the leading end of the sheet S4 will be supported by the side edge alignment plate 39F, and it is possible to prevent the leading end of the sheet from drooping onto the processing tray 37. Also, in order to enable the shift operation of the shift rollers 201 and 202, the nip states of the third conveyance roller 203, the paper discharge roller 36, and the elevating roller 41 are released and they are in a separated state.

[0160] Figure 45(b) is a view of the state of Figure 45(a) seen from above. Different from Figure 42B, as shown in Figure 45(b), one of the pair of side edge alignment plates (for example, side edge alignment plate 39F in Figure 45) supports the sheet, and the other alignment plate (for example, side edge alignment plate 39R in Figure 45) is located at a retracted position retracted in the width direction. In Figure 45(b), it shows the state where side edge alignment plate 39F supports the sheet and the other side edge alignment plate 39R is located at a retracted position retracted in the width direction. However, it is also possible that side edge alignment plate 39R supports the sheet and the other side edge alignment plate 39F is located at a retracted position retracted in the width direction.

[0161] Figure 46(a) shows the state in which the shift operation of shift rollers 201 and 202 has been performed. In this example, as shown in Figure 46(b), a shift operation is performed downward (front direction in Figure 46(a)) in Figure 46(b). Here, side edge alignment plates 39F and 39R do not move in synchronization with the shift operation of shift rollers 201 and 202. That is, as shown in Figures 45(b) and 46(b), the distance a between side edge alignment plate 39F and the center of the sheet width is maintained before and after the shift operation. In this way, in this embodiment, a point contact state is formed between the sheet and one of the pair of side edge alignment plates. Thereby, when the sheet is shifted by shift rollers 201 and 202, it is possible to prevent surface contact with the processing tray 37 due to the sagging of the sheet tip, and it is possible to reduce the resistance during the shift movement. Note that whether the sheet is being conveyed in the conveyance direction during the shift movement or the sheet has stopped moving in the conveyance direction during the shift movement, the effect of reducing the resistance during the shift movement can be achieved in the same way. After the shift operation, each of the third conveyance roller 203, the paper discharge roller 36, and the lifting roller 41 returns to the nip state again.

[0162] As described above, when performing the shift operation of the sheet supplied from the image forming apparatus A, even when the sheet tip reaches the processing tray 37, the resistance during the shift movement can be reduced.

[0163] The disclosure of the present embodiment includes the following sheet processing apparatus and an image forming apparatus including the sheet processing apparatus. (Item 1) A conveyance path through which a sheet is conveyed from an inlet to an outlet, a shift unit that shifts the sheet on the conveyance path in the width direction of the sheet, a tray that receives the sheet discharged from the outlet from above, a processing unit that performs processing on the sheet placed on the tray, a pair of side edge alignment plates provided on the tray for aligning the side edges in the width direction of the sheet before the processing by the processing unit, control means for controlling at least one of the pair of side edge alignment plates so that at least one of the pair of side edge alignment plates is positioned at a position where it can contact the inner side in the width direction of the sheet shifted by the shift unit, A sheet processing apparatus, characterized by comprising the above. (Item 2) The sheet processing apparatus according to item 1, wherein the control means controls the pair of side edge alignment plates so that the pair of side edge alignment plates are positioned at positions where they can contact the inner side in the width direction of the sheet shifted by the shift unit. (Item 3) The sheet processing apparatus according to item 2, wherein the control means moves the pair of side edge alignment plates in conjunction with the shift of the sheet by the shift unit, and controls the pair of side edge alignment plates so that the pair of side edge alignment plates are positioned at positions where they can contact the inner side in the width direction of the sheet shifted by the shift unit. (Item 4) The shift unit includes a shift roller capable of conveying the sheet in the conveyance direction of the conveyance path during the shift of the sheet by the shift unit, The control means controls the shift roller so as to convey the sheet in the conveyance direction of the conveyance path during the shift operation by the shift unit, The sheet processing apparatus according to item 3, characterized by the above. (Item 5) An image forming apparatus that forms an image on a sheet, The sheet processing apparatus according to any one of Items 1 to 4, and An image forming system characterized by comprising the same.

[0164] 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 Signs

[0165] B Post-processing apparatus: R Curved portion: S1 Sheet: 26 Straight path inlet: 28 Straight path: 30 Upper conveyance path: 34 Upper conveyance path flapper: 35 Straight path paper discharge port: 201 Inlet roller: 202, 203 Shift roller: 203 Third conveyance roller: 303 Upper conveyance roller: 303b Outer roller:

Claims

1. A conveyance path through which a sheet is conveyed from an inlet to an outlet, a shift unit that shifts the sheet on the conveyance path in the width direction of the sheet, a tray that receives the sheet discharged from the outlet from above, a processing unit that performs processing on the sheet placed on the tray, a pair of side-edge alignment plates provided on the tray for aligning the side edges in the width direction of the sheet before processing by the processing unit, control means for controlling at least one of the pair of side-edge alignment plates so that at least one of the pair of side-edge alignment plates is positioned at a position where it can contact the inner side in the width direction of the sheet shifted by the shift unit, A sheet processing apparatus, characterized by comprising the above.

2. The sheet processing apparatus according to claim 1, wherein the control means controls the pair of side-edge alignment plates so that the pair of side-edge alignment plates are positioned at positions where they can contact the inner side in the width direction of the sheet shifted by the shift unit.

3. The sheet processing apparatus according to claim 2, wherein the control means moves the pair of side-edge alignment plates in conjunction with the shifting of the sheet by the shift unit, and controls the pair of side-edge alignment plates so that the pair of side-edge alignment plates are positioned at positions where they can contact the inner side in the width direction of the sheet shifted by the shift unit.

4. The shift unit includes a shift roller capable of conveying the sheet in the conveyance direction of the conveyance path during the shifting of the sheet by the shift unit, and the control means controls the shift roller so as to convey the sheet in the conveyance direction of the conveyance path during the shifting operation of the shift unit. The sheet processing apparatus according to claim 3, characterized by the above.

5. An image forming apparatus that forms an image on a sheet, and the sheet processing apparatus according to claim 1. An image forming system, characterized by comprising the above.

Images