Sheet processing device and image forming system equipped with the sheet processing device

Abstract

The present invention provides a sheet processing device that reduces the possibility of preceding sheets loaded onto the processing tray being carried along by the subsequent sheet loading operation. [Solution] The sheet processing device includes control means that, when receiving a subsequent sheet while a preceding sheet is already on the tray, controls the device to receive the subsequent sheet while holding the preceding sheet down with a conveying member.

Description

Technical Field

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

Background Art

[0002] A sheet processing apparatus is connected to an image forming apparatus, and is known as an apparatus that conveys an imaged sheet to a processing tray, performs processing such as binding, and stacks the sheet on a stacking tray. Patent Document 1 discloses a processing tray for performing processing. This processing tray widely employs a switchback method in which after receiving the conveyed sheet from above, it conveys the sheet in a direction opposite to the conveyed direction and abuts it against an abutting portion for alignment. Therefore, the processing tray is inclined downward toward the abutting portion so that the sheet is also sent toward the abutting portion by utilizing gravity.

[0003] The processing tray is provided with a conveying member for conveying the sheet in the switchback direction and a member for aligning the width direction of the sheet. This conveying member is known to convey the sheet with a weak pressure toward the abutting portion in order to prevent buckling due to excessive scraping.

[0004] In addition, for miniaturization of the apparatus, a bridge method in which the leading end of the sheet stacked on the processing tray is exposed to the stacking tray is widely employed. Particularly in the case of a sheet having a long conveyance direction length, the rear end side of the sheet is stored along the inclination of the processing tray, but the leading end side of the sheet hangs down to the stacking tray.

[0005] In this way, each time the sheet is discharged onto the processing tray, it is sequentially aligned to form a bundle of sheets. However, when a subsequent sheet contacts the sheet on the processing tray from above, there is a problem that the sheet that has already been aligned on the processing tray is dragged in the direction in which the subsequent sheet is conveyed.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2013-159414 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The present invention aims to provide a sheet processing apparatus that reduces the possibility of sheets on a processing tray being moved by subsequent sheets by using a conveying means that conveys sheets toward abutment members. [Means for solving the problem]

[0008] To solve the above problems, the sheet processing apparatus according to the present invention comprises: a transport path through which sheets are transported from an inlet to an outlet; a tray for receiving sheets discharged from the outlet from above; a restricting member provided on the outlet side of the tray for restricting the rear end of the discharged sheet; a transport member for transporting the sheet toward the restricting member; a binding section for binding the sheet restricted by the restricting member; and a control means for controlling the transport member to position it closer to the tray than the sheet transporting position when receiving a subsequent sheet discharged from the outlet while there are already sheets stacked on the tray. [Effects of the Invention]

[0009] According to the present invention, when a subsequent sheet reaches the processing tray, the already loaded sheet is held by the conveying member, preventing the subsequent sheet from being carried along with the already loaded sheet even if it comes into contact with it, thereby reducing the possibility of deterioration in alignment. [Brief explanation of the drawing]

[0010] [Figure 1] Diagram showing an image forming system [Figure 2] Diagram showing the configuration of the sheet processing device. [Figure 3] Diagram showing the transport path and the vicinity of the tray. [Figure 4] Diagram showing the tray configuration [Figure 5] Diagram showing the configuration of the side edge alignment plate. [Figure 6] Diagram showing the sheet ejection mechanism [Figure 7] Diagram showing the binding mechanism [Figure 8] Diagram showing the mechanism to prevent abduction. [Figure 9] Diagram showing the mechanism to prevent abduction. [Figure 10] Diagram showing the mechanism to prevent abduction. [Figure 11] Diagram showing the mechanism to prevent abduction. [Figure 12] Diagram showing the mechanism to prevent abduction. [Figure 13] Diagram showing the mechanism to prevent abduction. [Modes for carrying out the invention]

[0011] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0012] [Image Forming Apparatus] The image forming apparatus A in the image forming system shown in Figure 1 will be described below. The illustrated image forming apparatus A represents an electrostatic printing mechanism and consists of an image forming unit A1, a scanner unit A2, and a feeder unit A3. The apparatus housing 1 is provided with mounting legs 25 for installation on a mounting surface (e.g., the floor). Inside the apparatus housing 1 are a paper feeding unit 2, an image forming unit 3, a paper discharge unit 4, and a data processing unit 5.

[0013] The paper feeding unit 2 is configured to include cassette mechanisms 2a to 2c for storing sheets of a plurality of sizes for image formation, and feeds out the sheets of the size designated by the main body control unit 90 to the 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 internal sheets one by one and a paper feeding mechanism for feeding out the sheets. In the paper feeding path 6, a conveying roller 7 for feeding the sheets supplied from the plurality of cassettes 2a to 2c to the downstream side is provided, and at the end of the path, a registration roller pair 8 for aligning the leading edges of the sheets is provided.

[0014] In addition, a large-capacity cassette 2d and a manual feed tray 2e are connected to the paper feeding path 6. The large-capacity cassette 2d is configured to include an option unit for storing sheets of a size that is consumed in large quantities, and the manual feed tray 2e is configured to be able to supply special sheets such as thick paper sheets, coated sheets, and film sheets for which separation and feeding are difficult.

[0015] The image forming unit 3 is shown as an example of an electrophotographic printing mechanism, and a photoreceptor 9 (drum, belt), a light emitter 10 that emits an optical beam to the photoreceptor 9, a developing device 11 (developer), and a cleaner (not shown) are arranged around the rotating photoreceptor. The one shown is a monochrome printing mechanism. An electrostatic latent image is optically formed on the photosensitive drum 9 by the light emitter 10, and toner ink is attached to this latent image by the developing device 11. Then, in accordance with the timing of image formation on the photoreceptor 9, the sheet is sent from the paper feeding path 6 to the image forming unit 3, the image is transferred onto the sheet by the transfer charger 12, and is fixed by the fixing unit (roller) 13 arranged in the paper discharge path 14. In the paper discharge path 14, a paper discharge roller 15 and a paper discharge port 16 are arranged, and the sheet is conveyed to the sheet post-processing device B described later.

[0016] Scanner unit A2 includes a platen 17 for placing an image document, a carriage 18 that reciprocates along the platen 17, a light source mounted on the carriage 18, and a reduction optical system 20 (a combination of mirrors and lenses) that guides the reflected light from the document on the platen 17 to the photoelectric conversion unit 19. Illustration 21 is the second platen (running platen), and the carriage 18 and the reduction optical system 20 perform image reading on the sheet sent from the feeder unit A3. The photoelectric conversion unit 19 transfers the photoelectrically converted image data to the image forming unit 3.

[0017] 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 document for which image reading has been performed on the platen.

[0018] 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.

[0019] [Sheet post-processing device] The sheet post-processing device B is, for example, a device that post-processes the sheet discharged from the paper discharge port 16 of the image forming apparatus A, and includes (1) a function of stacking and storing the image-formed sheet (printout mode), (2) a function of sorting and storing the image-formed sheet (jog sorting mode), (3) a function of binding and processing the image-formed sheets by aligning and integrating them (binding processing mode), and (4) a function of folding and finishing the binding after aligning and binding the image-formed sheets (bookbinding processing mode).

[0020] In this embodiment, the sheet post-processing device B does not necessarily 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 to have a function of folding and finishing the binding after aligning and binding the image-formed sheets.

[0021] Figure 2 shows the configuration of the sheet post-processing device B, and Figure 3 shows the configuration around the straight path 28. The sheet post-processing device B processes the sheets fed in from the straight path inlet 26 connected to the paper output slot 16 of the image forming apparatus A, and then stores them in the storage section (the first stack tray 49, second stack tray 61, and third stack tray 71, described later). The illustrated device transfers the sheets sent to the straight path 28 from the processing unit B1, which includes 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"). It also transfers the sheets sent to the straight path 28 from the saddle section B2 to the second stack tray 61 (hereinafter referred to as the "second tray"). Since the straight path 28 is formed in a substantially straight shape, it can also transport cardboard and the like.

[0022] Processing unit B1 is located at the exit of the straight path 28 (straight path paper output 35) and aligns and stacks the sheets as they are fed sequentially, performs binding, and then stores them in the first tray 49. Saddle unit B2 is located at the exit of the saddle path 32, which branches off from the straight path 28 (saddle path paper output 35) and is a post-processing unit that aligns and stacks the sheets as they are fed sequentially, performs saddle stitching (or sometimes saddle stitching), folds them, and stores them in the second tray 61. The following describes each component in detail.

[0023] <Device Housing> As shown in Figure 2, the sheet post-processing device B comprises a device housing 27, a straight path 28 built inside the device housing which has a straight path inlet 26 and a straight path paper output port 35, a processing unit B1 and a saddle unit B2 for post-processing the sheets sent from the straight path 28, and 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 positioned at approximately the same height as the housing 1 of the image forming apparatus A located upstream, and the paper output port 16 of the image forming apparatus A and the straight path inlet 26 of the sheet post-processing device B are connected on the installation surface.

[0024] The housing 27 of the seat aftertreatment device includes a device frame 70. The device frame 70 forms the framework of the device and includes a front side frame 70f located at the front in the state shown in Figure 1, a rear side frame 70r located at the rear, and stay members (connecting reinforcing members) that connect the two side frame frames. The straight path 28, processing unit B1, saddle section B2, etc., which will be described later, are attached between these left and right side frame frames. The device housing 27 is not limited to the shape shown and can be designed in a form that is suitable for the design, and the device frame 70 can also be various frame structures such as a monocoque structure, not limited to the left and right side frames and connecting stay structure.

[0025] <Sheet Loading Route> As shown in Figure 3, the straight path 28 is a substantially straight path that crosses the device housing 27 in a substantially horizontal direction, and includes a straight path inlet 26 connected to the paper discharge port (main paper discharge port) 16 of the image forming apparatus A, and a straight path paper discharge port 35 located on the opposite side across the device from this loading inlet (straight path inlet 26). The straight path 28 has a transport mechanism that allows sheets to be transported from the straight path inlet 26 to the straight path paper discharge port 35 and also from the straight path paper discharge port 35 to the straight path inlet 26, and the inlet roller 29, first transport roller 201, second transport roller 202, and third transport roller 203 are arranged in order from the straight path inlet 26 side. In addition, a paper discharge roller 36 is arranged at the straight path paper discharge port 35 as a transport mechanism. In other words, the straight path 28 has a transport mechanism for transporting sheets. Several rollers are arranged. The straight path 28 can also be described as the main sheet transport path, formed from the straight path inlet 26, which is the sheet receiving port, to the straight path paper output port 35, which is the sheet output port. Near the straight path inlet 26, an inlet sensor S1 is positioned to detect the leading and trailing ends of the sheet to be received, and a lateral register detection sensor S0 (detection unit) is positioned to detect the end face position (side edge) parallel to the sheet transport direction. Near the straight path paper output port 35, a paper output sensor S2 is positioned to detect the leading and trailing ends of the sheet. Sheets discharged from the straight path paper output port 35 are either discharged to the first tray 49 via the first paper output path 31 connected to the straight path paper output port 35, or guided to the processing unit B1. A punch unit 100 for punching holes in the sheet is also positioned on the straight path 28.

[0026] <Processing Unit> Processing Unit B1 is a post-processing unit located downstream of the straight path 28 and includes a processing tray 37 that aligns and accumulates sheets sent from the straight path paper output port 35, and a binding processing mechanism that binds the accumulated sheet bundles. As shown in Figure 3, the processing tray 37 is positioned below the straight path paper output port 35 of the straight path 28, forming a step, and a first paper output path (first switchback path) 31 is formed between the straight path paper output port 35 and the processing tray 37, which reverses the transport direction from the paper output port and guides the sheets onto the tray.

[0027] Between the straight-path paper output port 35 and the processing tray 37, a sheet loading mechanism is provided to load sheets from the paper output port onto the tray. The processing tray 37 is equipped with a positioning mechanism to position sheets at predetermined binding positions and a sheet bundle discharge mechanism to discharge the bound sheet bundles to the downstream first tray 49. Each of these components will be described later.

[0028] Furthermore, the processing tray 37 shown in Figure 3 bridges and supports the sheets fed from the straight-path paper output port 35 between itself and the downstream first tray 49. In other words, the sheet fed from the straight-path paper output port 35 is supported by bridging its leading edge onto the top sheet of the downstream first tray 49 and its rear end onto the processing tray 37.

[0029] [Configuration of the Processing Unit] Next, the configurations of the sheet loading mechanism, sheet positioning mechanism, binding mechanism, and sheet bundle discharge mechanism of the processing unit B1 will be described.

[0030] <Sheet feeding mechanism> As shown in Figure 3, between the straight-path paper output port 35 and the processing tray 37, there is a reversal transport mechanism that switches back and transports the sheet from the straight-path paper output port 35 in the paper output direction and the opposite direction of paper output, a guide mechanism (sheet guide member) 44 that guides the sheet towards the tray, and a scraping rotating body 46 that guides the sheet to the rear end restricting section.

[0031] The reversing transport mechanism includes a lifting roller 41 that moves up and down between an operating position that engages with the sheet being transported onto the processing tray 37 and a standby position that is separated from it, and a paddle rotating body 42 that transports the sheet in the opposite direction to the paper discharge. The lifting roller 41 and the paddle rotating body 42 are attached to a swing bracket 43.

[0032] A swing bracket 43 is positioned on the device frame 27 so as to be able to swing around a rotation axis (e.g., the paper discharge roller axis), and the rotation axes of the lifting roller 41 and the paddle rotor 42 are supported by bearings on the swing bracket 43. 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 rotor 42 up and down between an operating position in which they engage with the sheet and a standby position separated from the sheet.

[0033] Furthermore, a drive motor (not shown) is connected to the lifting roller 41 and the paddle rotor 42, and the drive is transmitted so that the lifting roller 41 rotates in the forward and reverse directions, and the paddle rotor 42 rotates in the reverse direction (opposite direction of paper discharge). In addition, a driven roller 48 is arranged in the processing tray 37, which presses against the lifting roller 41, and nips a single sheet or a bundle of sheets and discharges it downstream.

[0034] Between the lifting roller 41 and the scraping rotating body 46 (described later), a guide mechanism is positioned to guide the rear end of the sheet fed onto the processing tray 37 toward the sheet end restricting section 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 Figure 3. The sheet guide member 44 retracts to the dotted line position when a sheet is discharged from the straight-path paper discharge port 35, and guides the rear end of the sheet onto the processing tray 37 after the rear end of the sheet has passed through the straight-path paper discharge port 35. For this purpose, a drive mechanism (not shown) is connected to the sheet guide member 44, and it moves up and down in accordance with the timing of guiding the rear end of the sheet from the straight-path paper discharge port 35 onto the processing tray 37.

[0035] The configuration of the scraping rotating body 46 shown in Figure 4 will be explained. Figure 4(a) shows a view from the side, and Figure 4(b) shows a view from above. The scraping rotating body 46 moves the elastic belt 46b (hereinafter referred to as the knurled belt) toward the sheet edge regulating portion 38 by bringing it into contact with the sheet.

[0036] The elastic belt 46b (knurled belt) receives driving force from multiple planetary gears 46g arranged on the inside of the belt, and is rotatable with one of these planetary gears 46g acting as a pivot point 46c. Details of this configuration are disclosed in Japanese Patent Publication No. 2016-160014.

[0037] The difference in the rotation angle around the pivot point 46c causes the distance between the elastic belt 46b and the already loaded sheets on the processing tray 37 to vary, and by utilizing the elasticity of the elastic belt 46b, scraping is achieved with weak nip pressure. This prevents the scraping member 46 from scraping the sheets too much and prevents the sheets from buckling when they come into contact with the sheet edge restricting portion 38.

[0038] <Sheet Positioning Mechanism> The processing tray 37 is equipped with positioning mechanisms 38 and 39 for positioning sheets at predetermined binding positions. The illustrated mechanism includes a sheet edge restricting section 38 that abuts and restricts the rear end of the sheet, and a side edge alignment plate 39 that positions the side edge of the sheet at a reference position (center reference, one-sided side reference).

[0039] As shown in Figure 3, the sheet edge restricting portion 38 is composed of a stopper member that abuts against and restricts the rear end of the sheet. Positioning is also performed by the side edge alignment plate material 39.

[0040] <Side Edge Alignment Mechanism> As shown in Figures 3 to 5, the side edge alignment plates 39f and 39r protrude upward from the paper loading surface 37a of the processing tray 37 and have regulating surfaces 39x that engage with the side edges of the sheets, and are arranged in pairs on the left and right so as to face each other. These pair of side edge alignment plates 39 are positioned on the processing tray 37 so as to be able to reciprocate within a predetermined stroke. This stroke is set by the size difference between the largest and smallest size sheets and the offset amount which moves the aligned sheet bundle in either the left or right direction (offset transport).

[0041] In other words, the movement stroke of the left and right side edge alignment plates 39f and 39r is set by the amount of movement required to align sheets of different sizes and the offset amount of the sheet bundle after alignment. This offset movement can be performed either one sheet at a time each time a sheet is loaded into the processing tray 37 (for each loaded sheet), or by moving the bundle as a whole in order to perform the binding process after the sheets have been aligned into a bundle.

[0042] Therefore, as shown in Figure 5, the side edge alignment plate 39 is composed of a right side edge alignment plate material 39f (front side of the device) and a left side edge alignment plate material 39r (rear side of the device), and both side edge alignment plate materials are supported on the processing tray 37 so that regulating surfaces 39x that engage with the side edge of the sheet move toward or away from each other. The processing tray 37 is provided with a slit groove (not shown) that penetrates both sides, and the side edge alignment plate 39 having a regulating surface 39x that engages with the side edge of the sheet is slidably fitted into this slit groove.

[0043] Each side edge alignment plate 39f, 39r is slidably supported on the back side of the tray by a plurality of guide rollers 80 (which may also be rail members), and a rack 81 is integrally formed. Alignment motors M1, M2 are connected to the left and right racks 81 via pinions 82. The left and right alignment motors M1, M2 are stepping motors and are configured to detect the positions of the left and right side edge alignment plates 39f, 39r using position sensors (not shown), and to move each alignment member in either the left or right direction by a specified amount of movement based on the detected value. Note that the rack-pinion mechanism is not limited to the one shown, and each side edge alignment plate 39f, 39r may be fixed to a timing belt and connected by pulleys to a motor that reciprocates the timing belt left and right.

[0044] The side edge alignment plate 39f has a built-in spring SP to absorb tolerances in the width direction of the sheet when it is pressed in during sheet alignment. During sheet alignment, the sheet is aligned by pressing it in until the spring SP extends, that is, so that the distance between the pair of side edge alignment plates 39f and r is positioned slightly inward from the sheet width.

[0045] With the configuration described above, the binding processing control unit 95, which will be described later, places the left and right side edge alignment plates 39f and 39r at a predetermined standby position (sheet width + α position) based on the sheet size information provided by the image forming apparatus A. Then, in the case of "multi-binding", sheets are loaded onto the processing tray 37, and the alignment operation is started when the edge of the sheet hits the sheet edge regulating unit 38. This alignment operation is performed by rotating the left and right alignment motors M1 and M2 by the same amount in opposite directions (approaching direction). As a result, the sheets loaded onto the processing tray 37 are positioned with respect to the sheet center and stacked in bundles. Through the repetition of this sheet loading operation and alignment operation, the sheets are bundled and accumulated on the processing tray 37.

[0046] <Binding Mechanism> The processing tray 37 is equipped with a binding mechanism 47 that binds the stacks of sheets accumulated on the paper-loading surface 37a. The paper-loading surface 37a on the processing tray 37 is positioned at a predetermined binding position by a positioning mechanism (sheet edge regulating section 38 and side edge alignment plate 39). The binding mechanism 47 is configured as a binding unit 47 (hereinafter referred to as "staple unit") that binds the stacks of sheets with staples.

[0047] <Sheet Bundle Discharge Mechanism> The processing tray 37 is equipped with a sheet bundle discharge mechanism that discharges the bound sheet bundles toward the first tray 49 downstream. Known configurations for transporting sheet bundles downstream include a method using a pair of rollers that press against each other (discharge roller mechanism) and a conveyor mechanism that pushes out the rear end of the sheets with an extrusion member that moves along the tray surface from upstream to downstream. The device in Figure 6 employs both of these methods.

[0048] Figure 6 shows the sheet bundle discharge mechanism. The conveyor mechanism includes an extrusion projection 45 that transfers the sheets from the binding position (processing position) located upstream along the processing tray 37 to the stack tray (first tray) 49 downstream, a conveyor belt 45v that moves the extrusion projection, and a drive motor M6. A driven roller 48 is positioned at the discharge outlet (boundary between the paper loading surface 37a and the first tray 49) of the processing tray 37, and a lifting roller 41 that presses against the driven roller 48 is positioned opposite it, and the driven roller 48 and the lifting roller 41 constitute the discharge roller mechanism.

[0049] Therefore, the processing tray 37 is equipped with conveyor mechanisms 45 and 45v that push the sheet bundle from the upstream side to the downstream side, and discharge roller mechanisms 48 and 41 that nip the sheet bundle and discharge it. Figure 6(a) shows the state in which the sheet bundle is located at the binding position on the processing tray 37. At this time, the conveyor mechanisms 45 and 45v and the discharge roller mechanisms 48 and 41 are in operation. Figure 6(b) shows the state in the process of transporting the sheet bundle from the processing position to the downstream side, where the sheet bundle is sent downstream by the movement of the extrusion projection 45 and the rotation of the discharge roller mechanisms 48 and 41. Figure 6(c) shows the state just before the sheet bundle is discharged to the first tray 49 on the downstream side, where the sheet bundle is gradually (at a low speed) sent downstream on the processing tray by the rotation of the discharge roller mechanisms 48 and 41.

[0050] <Configuration of the staple unit> The configuration of the staple unit described above will be explained according to Figure 7. Staple Unit 47 is configured as a separate unit from the seat post-processing device B. A box-shaped unit frame 47a, a drive cam 47d pivotably supported on the unit frame 47a, and a drive motor M4 that rotates the drive cam 47d are mounted on the unit frame 47a.

[0051] The drive cam 47d has a staple head 47b and an anvil member 47c positioned opposite each other at the stapling position. The staple head 47b is biased by a biasing spring (not shown) on the drive cam 47d to move up and down from an upper standby position to a lower stapling position (anvil member). The needle cartridge 52 is detachably mounted on the unit frame 47a.

[0052] The needle cartridge 52 houses a straight blank needle, and the needle feeding mechanism supplies the needle to the staple head 47b. The staple head 47b contains a former member that bends the straight needle into a U-shape and a driver that presses the bent needle into the sheet bundle. With this configuration, the drive motor M4 rotates the drive cam 47d, storing energy in the biasing spring. When the rotation angle reaches a predetermined angle, the staple head 47b rapidly descends towards the anvil member 47c. In this action, the staple needle is bent into a U-shape and then inserted into the sheet bundle by the driver. The tip of the needle is then bent by the anvil member 47c and stapled.

[0053] Furthermore, a needle feeding mechanism is built between the needle cartridge 52 and the staple head 47b, and the needle feeding mechanism is equipped with a sensor (empty sensor) for detecting the absence of a needle. In addition, a cartridge sensor (not shown) is equipped on the unit frame 47a for detecting whether or not the needle cartridge 52 is inserted.

[0054] The staple cartridge 52 employs a structure in which staples connected in a strip are stacked and stored in a box-shaped cartridge, and a structure in which they are stored in a roll. The unit frame 47a is provided with circuits for controlling each of the above-mentioned sensors and a circuit board for controlling the drive motor M4, and is configured to emit a warning signal when the staple cartridge 52 is not stored or when the staples are empty. The staple control circuit controls the drive motor M4 to perform stapling operations in response to the staple signal, and is configured to emit an "operation completion signal" when the staple head unit 47b moves from the standby position to the stapling position and then returns to the standby position.

[0055] The operation of receiving the second and subsequent sheets into the processing tray 37 will be described in detail with reference to Figures 8 to 13. Note that (a) in each figure shows a view from the side, and (b) shows a view from above.

[0056] The sheets S1 fed by the paper output roller 36 are sequentially sent onto the processing tray 37 (Figures 8 and 9), where alignment processing is performed by the scraping rotating body 46 and the side edge alignment plate 39 (Figure 10), and the sheets are placed on the tray in an aligned state.

[0057] At this time, if the sheets loaded on the processing tray are longer than a predetermined transport direction length (A4R or larger in this embodiment), the loaded sheets that have completed alignment processing will come into contact with subsequent sheets transported by the paper discharge roller 36, and a force will act on the loaded sheets in the pushing direction. Therefore, it is necessary to hold the loaded sheets in place so that they do not move. This is more pronounced when the transport direction length of the sheets is long, the basis weight is greater than a predetermined value, or when various coatings are applied to the sheet surface, causing the sheets to adhere to each other easily. In this embodiment, coated paper with a sheet size of A4R or larger and a basis weight of 400 g / m² or larger is used.

[0058] Therefore, in this embodiment, the scraping rotating body 46 is kept in a stopped state and moved toward the processing tray 37, thereby holding down the sheet on the sheet. Furthermore, the side edge alignment plate 39 is moved to a position where it aligns with the sheet, thereby holding down the sheet from the sheet width direction as well.

[0059] By holding the already loaded sheet S1 with the scraping rotating body 46 and the side edge alignment plate 39 in this manner, even if a subsequent sheet S2 comes into contact with the already loaded sheet S1, it is possible to reduce alignment problems such as being pushed out or carried along.

[0060] Furthermore, the number and area of ​​the scraping rotating bodies 46 can be increased to further prevent sheet movement, and the amount the side edge alignment plate 39 is pushed inward from the sheet can be increased compared to when the sheet is aligned to further enhance the holding force. The dotted lines in Figures 11 and 12 show the intended position of the side edge alignment plate 39 pushed inward from the width of the sheet S1. In reality, the spring built into the side edge alignment plate keeps the position of the side edge alignment plate 39 unchanged, but pushes it further inward. It is preferable that the amount of push-in at this time exceeds the expansion and contraction range of the spring.

[0061] Furthermore, the scraping rotating body 46 uses the elasticity of the elastic belt 46b to scrape the sheet. However, by lowering the pressing position during the sheet receiving operation to a lower height than the scraping position and bringing it closer to the sheet, the contact pressure can be increased, thereby improving the sheet holding force.

[0062] When using the scraping rotating body 46 as a sheet holder in the sheet receiving operation, the holding force can be further increased by bringing it closer to the sheet until the gap in the elastic belt 46b is compressed. Specifically, the greatest holding force can be generated when the planetary gear 46g, located inside the elastic belt 46b, is pressing down on the sheet, that is, when the sheet and the elastic belt 46g are sandwiched between the planetary gear 46g and the tray 37 (see Figure 11).

[0063] As shown in Figure 13, once the trailing edge of the subsequent sheet S2 passes through the paper output roller 36 and is placed on the processing tray 37, the side edge alignment plate 39 moves a predetermined distance away from the sheet edge, and the scraping rotating body 46 also rises to a scraping position with less pressing force, performing the sheet alignment operation of S2. Subsequently, the alignment operation is performed sequentially, and the binding operation described above is carried out.

[0064] As described above, this embodiment makes it possible to provide a sheet processing device that reduces the possibility of previously loaded sheets being carried along by subsequent sheets without adding any special configurations to the processing tray.

[0065] The invention is not limited to the above embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. The elastic belt 46b in this embodiment can be replaced with, for example, a sponge roller or a flexible paddle member to achieve similar effects. It is also effective when the processing tray 37 has little inclination toward the abutment member. [Explanation of Symbols]

[0066] B Post-processing device 37 Tray 39 Side edge alignment plate 46 Scraping rotating body 46b Elastic belt 46c Scraping rotating body pivot center 46g Planetary gear S1 Leading sheet (pre-loaded sheet) S2 Following sheet

Claims

1. A sheet processing apparatus comprising: a transport path for transporting sheets from an inlet to an outlet; a tray for receiving sheets discharged from the outlet from above; a restricting member provided on the outlet side of the tray for restricting the rear end of the discharged sheet; a transport member for transporting the sheet toward the restricting member; a binding section for binding the sheet restricted by the restricting member; and a control means for controlling the transport member to position it closer to the tray than the sheet transporting position when receiving a subsequent sheet discharged from the outlet while there are already sheets loaded on the tray.

2. The sheet processing apparatus according to claim 1, wherein the conveying member comprises a flexible elastic belt and a drive transmission unit provided inside the elastic belt for transmitting power to the elastic belt, and when the conveying member is positioned closer to the tray than the position for conveying the sheet, the drive transmission unit compresses the deflection of the elastic belt.

3. An image forming system comprising: an image forming apparatus for forming an image on a sheet; and the sheet processing apparatus according to claim 1.

Images