Sheet processing apparatus and image forming system

Abstract

To provide a sheet processing device that suppresses deflection and curve of sheet-shaped medium with a leading edges aligned, and improves the degree of alignment of the edge parts after post-processing.SOLUTION: A sheet processing device that processes a sheet-shaped medium conveyed between a pair of conveyance guide members at a predetermined position in the conveyance direction includes a pushing member that pushes the predetermined position of the medium toward a processing member, and a medium pressing member that presses the medium conveyed between the pair of conveyance guide members. The medium pressing member is the sheet processing device that presses the predetermined position side after pressing an end side of the medium in the conveyance direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a sheet processing apparatus and an image forming system. [Background technology]

[0002] There are known sheet processing devices that perform an "alignment process" that aligns the edges of sheet-like media, a "folding process" that forms creases in sheet-like media, a "binding process" that binds a stack of sheets with aligned edges, and a "saddle stitching process" that folds the media in half and binds them at the crease position. There are also known image forming systems that include an image forming device that forms an image on a medium and a sheet processing device that performs the above-mentioned post-processing on the medium on which the image has been formed.

[0003] A "folding device," an example of a sheet processing device, positions a transported medium and controls it so that a predetermined position in the medium becomes a folding position in order to form a fold at a predetermined position in the medium. A known prior art for controlling a folding device is a technique in which the medium is pushed against an alignment member (stopper) that positions the leading edge of the medium so that the predetermined position coincides with the folding position, and a plate-shaped folding member (folding plate) pushes the medium toward the predetermined folding position to fold it.

[0004] Another known prior art technique is to align the edges of a sheet stack after folding by transporting the medium between a pair of plate-like members, positioning the medium with stoppers located at the edges of the plate-like members, and narrowing the distance between the plate-like members to prevent the medium from shifting during folding. In this prior art technique, narrowing the distance between the plate-like members increases friction between the plate-like members and the medium when the medium sandwiched between the pair of plate-like members is pushed toward the pair of folding rollers, increasing the resistance to transport of the medium to the pair of folding rollers and causing poor transport of the medium toward the pair of folding rollers.

[0005] Taking into consideration the above-mentioned transport defects, a known technology for suppressing curvature of the medium by narrowing the distance between a pair of plate-shaped members is to suppress curvature of the medium, and then hold the medium with a pair of rollers separate from the plate-shaped medium, separating the plate-shaped members, thereby reducing transport resistance (see Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0006] According to the technology disclosed in Patent Document 1, when a medium is sandwiched between a pair of plate-like members to prevent curvature or buckling, one end of the medium (the leading edge in the conveying direction) is restricted by a stopper, leaving no room for the medium to straighten. Therefore, when a stopper is used to position one end of the medium and perform a predetermined process (e.g., folding) on ​​the medium, as in the conventional technology, the restricted end restricts the medium's tendency to stretch toward the end when the curvature or buckling of the medium is suppressed. As a result, the restricted end (e.g., the leading edge of the medium) is more likely to deform. In other words, the conventional technology suppresses the curvature of the medium before processing in order to improve edge alignment when processing sheet-like media, resulting in issues such as reduced edge alignment accuracy and misaligned folding positions.

[0007] SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet processing apparatus that suppresses bending or curvature of sheet-like media and improves the alignment of the edges after post-processing. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a sheet processing apparatus for processing a sheet-like medium transported between a pair of transport guide members at a predetermined position in a transport direction, the sheet processing apparatus comprising: The aforementioned Predetermined position PlaceThe medium pressing device comprises a pushing member that pushes the medium toward the processing member, and a medium pressing member that presses the medium transported between the pair of transport guide members, wherein the medium pressing member comprises a pressing guide plate having an inclined surface relative to the transport guide member, and an elastic member that holds the inclined surface so that, in an initial position, the distance between the transport guide member and the pressing guide plate is wider on the predetermined position side than on the end side in the transport direction of the medium, and comprises an inclined surface holding member that presses the back surface of the pressing guide plate at least on the end side in the transport direction and on the predetermined position side, and an inclined surface moving member that moves the pressing guide plate toward the transport guide member, and presses the end side in the transport direction of the medium and then presses the predetermined position side. [Effects of the Invention]

[0009] According to the present invention, it is possible to suppress sagging or curvature of a sheet-like medium and improve the degree of alignment of the edge portion after post-processing. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing an example of the configuration of an image forming system according to the present invention; [Figure 2] 3A and 3B are diagrams illustrating an example of a folding blade used in a saddle stitching processing unit according to an embodiment of the present invention. [Figure 3] FIG. 4 is a diagram illustrating a comparative example to the first embodiment of the present invention. [Figure 4] FIG. 2 is a configuration diagram of a saddle stitching processing unit according to the first embodiment. [Figure 5] FIG. 2 is a side view of the saddle stitching processing unit according to the first embodiment, as viewed from the pressure drive mechanism side. [Figure 6] FIG. 2 is a side view of the saddle stitching processing unit according to the first embodiment. [Figure 7] 5A to 5C are explanatory views illustrating the operation of a pressing mechanism provided in the saddle stitching processing unit according to the first embodiment. [Figure 8] 5A to 5C are explanatory views illustrating the operation of a pressing mechanism provided in the saddle stitching processing unit according to the first embodiment. [Figure 9]FIG. 4 is a side view illustrating the relationship between the saddle stitching processing unit and paper sizes according to the first embodiment. [Figure 10] 5A to 5C are explanatory views illustrating the operation of a pressure drive mechanism provided in the saddle stitching processing unit according to the first embodiment. [Figure 11] 6A to 6C are diagrams illustrating the effect of a pressing mechanism included in the saddle stitching processing unit according to the first embodiment. [Figure 12] 5A and 5B are diagrams illustrating a force applied when a pressing mechanism included in the saddle stitching processing unit according to the first embodiment presses a stack of sheets. [Figure 13] 5A and 5B are diagrams showing the flow of operations during saddle stitching processing according to the first embodiment. [Figure 14] 5A and 5B are diagrams illustrating one step of saddle stitching processing according to the first embodiment. [Figure 15] 10A and 10B are views for explaining another step during saddle stitching processing according to the first embodiment. [Figure 16] 5A to 5C are diagrams showing the flow of operations during center-folding processing according to the first embodiment. [Figure 17] FIG. 10 is a configuration diagram of a saddle stitching processing unit according to the second embodiment. [Figure 18] FIG. 11 is a side view of the saddle stitching processing unit according to the second embodiment, as viewed from the pressure drive mechanism side. [Figure 19] FIG. 10 is a side view of a saddle stitching processing unit according to a second embodiment. [Figure 20] 10A to 10C are explanatory views illustrating the operation of a pressing mechanism provided in a saddle stitching processing unit according to the second embodiment. [Figure 21] FIG. 11 is a side view illustrating the relationship between the saddle stitching processing unit and paper sizes according to the second embodiment. [Figure 22] 10A and 10B are diagrams illustrating the structure of a pressing mechanism included in a saddle stitching processing unit according to a second embodiment. [Figure 23] 10A and 10B are diagrams illustrating the structure of a pressing mechanism included in a saddle stitching processing unit according to a second embodiment. [Figure 24] 13A and 13B are side views illustrating the relationship between the saddle stitching processing unit according to the second embodiment and a modification of the saddle stitching processing unit and the paper size. [Figure 25] 10A and 10B are diagrams illustrating the structure of a pressing mechanism included in a modified example of the saddle stitching processing unit according to the second embodiment. [Figure 26] 10A and 10B are diagrams showing the flow of operations during saddle stitching processing according to the second embodiment. [Figure 27] 10A and 10B are diagrams illustrating one step of saddle stitching processing according to the second embodiment. [Figure 28] 13A and 13B are views for explaining another step during saddle stitching processing according to the second embodiment. [Figure 29] 5A to 5C are diagrams showing the flow of operations during center-folding processing according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] 1 is a schematic diagram of an image forming system 600 including a sheet processing apparatus 300 as an embodiment of a sheet processing apparatus according to the present invention, and an image forming apparatus 200 that supplies a sheet P, which is a sheet-like medium after image formation, to the sheet processing apparatus 300.

[0012] The present invention can be applied not only to the image forming system 600 consisting of the image forming device 200 and the paper processing device 300, but also to an image forming device that has an image forming means that forms an image on paper P and a folding processing means that performs a folding process on the paper P on which the image has been formed.

[0013] [Schematic configuration of image forming system 600] The image forming method of the image forming apparatus 200 constituting the image forming system 600 according to this embodiment is not limited. For example, the image forming apparatus 200 may be an inkjet type image forming unit that includes an image processing circuit, a liquid ejection head that ejects liquid, and a transport device that transports paper P to the liquid ejection head, and forms an image by depositing the ejected liquid on paper P. Alternatively, an electrophotographic type image forming unit that includes an image processing circuit, a photosensitive member, an optical writing device, a developing device, a transfer device, and a fixing device may be used. Alternatively, a thermal transfer type image forming unit may be used.

[0014] The image processing circuit converts image data read by a scanner unit when the image forming apparatus 200 is a copier or image data input from an external information processing device such as a personal computer into image data suitable for image formation processing, and outputs the converted image data to the image forming unit.

[0015] When the image forming apparatus 200 is equipped with an inkjet image forming unit, the timing at which the liquid ejection head ejects ink droplets is controlled based on image data input from the image processing circuit, and the transport of the paper P relative to the position at which the ink droplets land is controlled, and the ink droplets are ejected at a predetermined timing to adhere to the paper P, forming an image. In addition, the ink droplets adhered to the paper P are dried by a drying unit to fix them, and then discharged to a subsequent stage.

[0016] When the image forming apparatus 200 is equipped with an electrophotographic image forming unit, an optical writing device optically writes onto a photoconductor based on an image signal output from an image processing circuit, forming an electrostatic latent image on the surface of the photoconductor. Then, a developing device develops the electrostatic latent image formed on the surface of the photoconductor by optical writing with toner, and a transfer device transfers the toner image visualized by the developing device onto paper P. Thereafter, a fixing device fixes the toner image transferred onto paper P.

[0017] The paper sheet P on which the toner image has been fixed by the image forming apparatus 200 is sent to the paper processing apparatus 300, where the desired post-processing is performed.

[0018] [Schematic configuration of the paper-sheet handling device 300] As shown in FIG. 1, a paper processing device 300 serving as a sheet processing device is attached to the side of the image forming device 200, and paper P discharged from the image forming device 200 is guided to the paper processing device 300.

[0019] The sheet-processing device 300 is configured to be able to perform predetermined post-processing by controlling the operation of various components within the sheet-processing device 300 using a control program executed by a control unit configured with hardware such as a CPU and a memory element. Note that the control unit including the sheet-processing device 300 is not shown in Fig. 1. The control unit may be provided in both the image forming device 200 and the sheet-processing device 300, or may be provided in either one and configured to control the entire image forming system 600.

[0020] The paper P carried into the paper processing device 300 from the image forming device 200 passes through the entrance transport path A and is transported inside. A punching unit 311 is disposed in the entrance transport path A as a post-processing unit that performs hole punching. If no hole punching process is performed, the paper P is simply transported downstream through the entrance transport path A. If no other post-processing is performed, the first branch claw 312 is set to a state in which it guides the paper P to the upper transport path B as shown in FIG. 1. This causes the paper P to be discharged onto the proof tray 313.

[0021] Furthermore, when performing "edge binding processing" in which the edges of the sheets P are aligned and bound, the first branch claw 312 is switched from the state shown in FIG. 1 to a state in which the sheets P are guided to the second branch claw 314. Then, the second branch claw 314 is set to a state in which the sheets P are guided from the intermediate conveyance path C to the staple tray 323, as shown in FIG. 1. When multiple sheets P are carried in under this state, a predetermined number of sheets P can be guided to the staple tray 323 and the binding processing can be performed.

[0022] Then, the edges of a sheet bundle Pb formed by stacking a predetermined number of sheets P on the staple tray 323 are aligned, and the edge binding staple unit 321 performs edge binding processing, and the bound sheet bundle is discharged to the sheet discharge tray 324.

[0023] When center folding or center stapling and center folding is performed, first branch claw 312 is switched from the state shown in FIG. 1 and second branch claw 314 is set to the state shown in FIG. 1 to guide sheet P to intermediate conveyance path C. Then, when the trailing end of sheet P in the conveyance direction passes second branch claw 314, second branch claw 314 is switched and intermediate conveyance roller 325 is rotated in the reverse direction. Then, sheet P is conveyed to saddle stitching processing unit 400 via lower conveyance path D.

[0024] The above configuration will be described in more detail below. Inlet transport path A is a transport path common to upper transport path B, middle transport path C, and lower transport path D, located upstream of each of them. Inlet transport path A is sequentially provided with an inlet sensor 315 that detects paper P received from image forming device 200, inlet rollers 316 downstream thereof, and a punching unit 311, and in that order a first branch claw 312 and a second branch claw 314 downstream thereof.

[0025] First branch claw 312 is biased in a certain direction by an elastic member such as a spring. When post-processing such as binding is not being performed, first branch claw 312 is held in a state in which it guides sheets P to upper conveying path B, as shown in Fig. 1. When the solenoid that drives first branch claw 312 is turned on and a driving force is applied in a direction against the bias of the spring to rotate, first branch claw 312 enters a state in which it guides sheets P toward intermediate conveying path C. Therefore, when the solenoid is off, it distributes sheets P to upper conveying path B, and when the solenoid is on, it distributes sheets P to intermediate conveying path C. Sheets P distributed to upper conveying path B are discharged to proof tray 313 by proof intermediate rollers 317 and proof discharge rollers 318.

[0026] Similarly to the first branch claw 312, the second branch claw 314 is also biased in a certain direction by an elastic member such as a spring, and is normally held in a state in which it guides the paper P from the intermediate conveyance path C to the staple tray 323, as shown in Fig. 1. When the paper P is to be discharged without being stapled, it is discharged to the paper output tray 324.

[0027] At this time, the sheet P sent to the intermediate conveying path C is shifted a certain amount in the direction perpendicular to the conveying direction by shift discharge rollers 326 configured to move the sheet P sent to the intermediate conveying path C by a certain amount in the direction perpendicular to the conveying direction of the sheet P by a driving means, and is then loaded onto the sheet discharge tray 324. The shift amount of the shift discharge rollers 326 is determined based on the sheet detection information detected by the entrance sensor 315, size information of the sheet P, etc.

[0028] When edge-stitching the paper stack Pb, the paper P transported to the intermediate transport roller 325 is brought into contact with the staple tray 323 by the pendulum motion of the tapping roller 327 that aligns the paper P, and is then transported in the opposite direction to the sheet transport direction by the return roller, with its rear end abutting against the rear end fence to align its position in the transport direction.

[0029] A jogger fence 328 that aligns the widthwise position of the sheets P is disposed above the staple tray 323. Also, a staple tray paper presence / absence sensor 329 that detects the presence or absence of sheets P on the staple tray 323 is disposed below the staple tray 323. Also, an edge-stitching staple unit 321 that performs a stapling process on the edge of a sheet bundle Pb formed from a plurality of sheets P is disposed on the rear end side (the rear end side in the transport direction from the image forming apparatus 200) that is the binding position for the sheets P placed on the staple tray 323.

[0030] [Schematic configuration of saddle stitching processing unit 400] When performing saddle stitching and center folding, the paper P is guided to the lower conveying path D by the intermediate conveying roller 325 and the second branch claw 314, and is then conveyed to the saddle stitching processing unit 400 located below by the switchback conveying roller 341 and the moving roller 342.

[0031] The saddle stitching processing unit 400 is provided with a rear end fence 410 that is movable in the conveyance direction of the paper P. The paper P is conveyed until its edge abuts against this rear end fence 410. At this time, the rear end fence 410 is moved in accordance with paper size information (size information in the conveyance direction of the paper P) from the image forming apparatus 200 so that the saddle stitching process and center folding process are performed at a targeted position, and the abutment position of the leading edge of the paper P is changed, and the paper P is made to wait at a predetermined position.

[0032] By repeating the above transport operation for multiple sheets of paper P, the positions of the ends of the sheets P that contact the rear end fence 410 are aligned, and the ends of the paper stack Pb are aligned. This completes the alignment operation of the ends of the paper stack Pb in the transport direction, with the center-folding position (folding position) for the paper stack Pb also being in a predetermined position that has been determined in advance.

[0033] Next, the saddle stitching jogger fence 420 aligns the sheet bundle Pb in the width direction, completing the alignment of the sheet bundle in the width direction.

[0034] Thereafter, the binding position (which also corresponds to the later folding position) corresponding to the center of the paper stack Pb at this standby position is moved to the position of the saddle stitch stapler 430, the stitcher is driven, and the binding process is performed between the stitcher and the clincher, thereby performing the saddle stitching process on the paper stack Pb.

[0035] As rear end fence 410 moves downward, saddle-stitched sheet bundle Pb is transported to a position where the saddle stitching position faces folding blade 440. Folding blade 440 moves toward the nip of folding roller pair 450, contacts sheet bundle Pb near the stapled portion of sheet bundle Pb from a direction approximately perpendicular to the nip, and pushes it toward the nip.

[0036] The sheet stack Pb is pushed by the folding blade 440, which serves as a pushing member, and guided to the nip of the folding roller pair 450, where it is pushed into the nip of the folding roller pair 450, which has been rotating in advance. The folding roller pair 450 applies pressure to the sheet stack Pb pushed into the nip and transports it in the discharge direction. This pressurized transport operation folds the sheet stack Pb in the center, forming a simply bound sheet stack Pb.

[0037] Thereafter, the simply bound sheet bundle Pb is discharged onto the saddle stitch tray 344 by the saddle stitch paper discharge rollers 460.

[0038] When only the center folding process is performed on the sheet bundle Pb, the saddle stitching process described above is not performed, and the rear end fence 410 is made to wait in advance at a predetermined position so that a predetermined position on the sheet bundle Pb becomes the folding position by the folding blade 440. Then, an alignment operation is performed in the conveying direction of the ends of the multiple sheets P conveyed via the lower conveying path D, and the sheets are aligned in the width direction by the saddle stitching jogger fence 420, and then the folding process is performed by the folding blade 440.

[0039] [Folding Blade 440] 2 is a diagram illustrating an example of a method for driving folding blade 440. Folding blade 440 is configured to be movable in the Y direction along grooves (grooves extending in the Y direction) provided at both ends in the X direction.

[0040] A spiral groove 441a is formed in the cam 441 on the far side in Fig. 2, and the drive shaft 442 of the folding blade 440 fits into the groove 441a. When the cam 441 rotates clockwise in Fig. 2, the drive shaft 442 moves in the Y direction along the groove 441a, and the folding blade 440 moves in the Y direction while sliding on both the groove extending in the Y direction and the groove 441a of the cam 441. This causes the folding blade 440 to push the paper stack Pb in the Y direction.

[0041] However, groove 441a formed in cam 441 is located at the same distance from the center as it approaches the center of cam 441, so folding blade 440 will no longer move in the Y direction even if cam 441 rotates further. In this way, folding blade 440 moves in the Y direction (leftward in FIG. 2) as cam 441 rotates, and even if the rotation proceeds further, folding blade 440 will remain stopped. Note that when cam 441 rotates in the reverse direction, folding blade 440 moves from its stopped state in the -Y direction (rightward in FIG. 2).

[0042] [Comparative Example to the Present Embodiment] Here, a comparative example to the saddle stitching processing unit 400 according to the embodiment of the present invention will be described with reference to Fig. 3. Fig. 3 shows an example of a unit similar to the saddle stitching processing unit 400 according to the present embodiment, which transports and positions the paper P in the gap between the plate-like members, and narrows the gap between the plate-like members to prevent the paper P from curving.

[0043] As shown in FIG. 3, the saddle stitching processing unit 400z as a comparative example transports the sheets P through a gap formed by a pair of transport guide plates 480 as transport guide members, and abuts the end (leading edge in the transport direction) of the transported sheets P against a rear end fence 410, which positions the end (leading edge) of the sheets P. This aligns the positions of the end (leading edge) of the sheets P, forming a sheet bundle Pb with aligned ends. In this case, the position of the rear end fence 410 is controlled so that a "predetermined position" as a processing position for the sheet bundle Pb, such as the saddle stitching position or folding position, and a "pushing position" where the folding blade 440 pushes the sheet bundle Pb are the same. Note that, since this comparative example illustrates center folding processing, the stapler 430 is not shown.

[0044] The operation and problems of the comparative example will be described below. As shown in FIG. 3(a), the sheet P is guided into the gap between a plurality of conveying guide plates 480 (a first conveying guide plate 480a and a third conveying guide plate 480c, and a second conveying guide plate 480b and a fourth conveying guide plate 480d) which are configured as pairs of plate-like members. As a result, the leading edge of the sheet P abuts against the trailing edge fence 410.

[0045] The leading edge of the sheet P abuts against the rear end fence 410, which serves as an alignment member, thereby determining the position of the end in the transport direction of the sheet P. Then, multiple sheets P abut against the rear end fence 410 in the same manner, forming a sheet bundle Pb with aligned ends.

[0046] Then, one of the pair of opposing conveyance guide plates 480 is moved toward the other to narrow the gap and sandwich the paper stack Pb positioned by the rear end fence 410. This straightens out any curvature or warping of each of the sheets P that make up the paper stack Pb.

[0047] Thereafter, the folding blade 440 pushes the sheet bundle Pb into a pair of folding rollers 450 as a processing member, whereby folding processing is performed at a predetermined position.

[0048] The purpose of moving one of the pair of opposing conveying guide plates 480 toward the other to narrow the gap and clamp the positioned paper stack Pb is to straighten out any curvature or sagging of each sheet P that makes up the paper stack Pb and also improve the alignment of the ends of the paper stack Pb.

[0049] 3, however, the entire opposing surface of the conveying guide plate 480 presses against the sheet P to smooth out any warping, etc., so the warping is straightened toward the edge of the sheet P depending on the shape of the warp and various other conditions. In this case, the edge of the sheet on the rear end fence 410 side is in contact with the rear end fence 410, and movement is restricted. Therefore, even if an attempt is made to straighten the curvature or warping, it cannot be straightened toward the leading edge of the sheet P in the conveying direction (toward the rear end fence 410).

[0050] As a result, as shown in Fig. 3(c), it is conceivable that the edge of the sheet P abutting against the trailing edge fence 410 may buckle or that wrinkles may form in part of the sheet P. Note that Fig. 3(c) is an enlarged view of the circle R in Fig. 3(b). As such, it is conceivable that simply pressing the sheet stack Pb in a plane to improve the alignment of the edge of the sheet P may not be enough to improve the alignment of the edge of the entire sheet stack Pb.

[0051] When the above phenomenon occurs, the operation of suppressing the sagging of the paper P (the operation of pressing the paper P with a plate-like member) causes a decrease in the degree of alignment at the edge (particularly the leading edge in the conveying direction). As a result, the center-folding position relative to the paper stack Pb shifts from the predetermined position, and the edge of the paper stack Pb after the center-folding process becomes misaligned.

[0052] As described above, the configuration shown in the comparative example has a problem in improving the alignment of the edges of the sheet stack Pb, particularly after the center folding (saddle stitching) process. There is also a problem in improving the accuracy of the center folding and saddle stitching positions. In contrast, the embodiment of the present invention addresses the above-mentioned problems by improving the alignment accuracy of the sheet edges, and also by improving the alignment accuracy of the edges of the sheet stack Pb after the center folding process. The present embodiment will be described in detail below.

[0053] [First embodiment] First, a configuration example of a first embodiment of a sheet processing apparatus according to the present invention will be described. Fig. 4 is an enlarged configuration diagram of a saddle stitching processing unit 400 provided in a sheet processing apparatus 300 according to this embodiment. Fig. 5 is a side view of the saddle stitching processing unit 400 according to this embodiment, seen from the pressure drive mechanism 470 side. Fig. 6 is a side view of the saddle stitching processing unit 400 according to this embodiment, omitting the pressure guide fixing plate 472 and pressure guide drive mechanism 474 that constitute the pressure drive mechanism 470 as an inclined surface moving member.

[0054] 4, the saddle stitching unit 400 guides the sheets P into the gap formed between four conveying guide plates 480 that make up a pair of conveying guide members, forming a stack of sheets Pb. A rear end fence 410 is disposed at the end of the conveying guide plate 480 on the leading edge side of the sheets P in the conveying direction, as an alignment member for positioning the leading edge of the sheets P.

[0055] The end (leading edge) of the sheet P in the conveying direction abuts against the rear-end fence 410, and the end of the sheet P in the conveying direction is positioned and aligned. This forms a sheet bundle Pb with aligned (aligned) ends. The position of the rear-end fence 410 is controlled so that a "predetermined position" as a processing position where the sheet bundle Pb is processed (such as saddle stitching or center folding) is the same as a "pushing position" where the folding blade 440 pushes the sheet bundle Pb. Therefore, with the ends of the sheet bundle Pb consisting of a predetermined number of sheets P aligned, the rear-end fence 410 moves to move the predetermined position (center folding position) of the sheet bundle Pb to the "pushing position (folding position)" where the sheet bundle Pb is pushed and folded by the folding blade 440. The amount of movement of the rear-end fence 410 is determined by the size of the sheet P, and is set so that the predetermined position corresponding to each size hits the folding position. Once the rear-end fence 410 has moved to the predetermined position, it stops moving. Thereafter, the folding blade 440 pushes the sheet bundle Pb into the pair of folding rollers 450, thereby performing folding processing at a predetermined position.

[0056] When performing saddle stitching, the saddle stitch stapler 430 moves the predetermined position to a position (binding position) where the saddle stitching process is performed, performs the binding process, and then moves the binding position to the folding position.

[0057] During the series of operations described above, particularly after the edges of a predetermined number of sheets P have been positioned to form a sheet stack Pb, an operation is performed to suppress curvature or warping of the sheets P that form the sheet stack Pb. This suppression operation is performed by pressing a pressure guide plate 471, which is a plate-like member arranged on part of the transport guide plate 480, toward the surface of the sheet stack Pb. The pressure guide plate 471 is positioned opposite the second transport guide plate 480b and is arranged to correspond to part of the fourth transport guide plate 480d. The pressure guide plate 471 presses the sheet stack Pb toward the second transport guide plate 480b, thereby performing an operation to straighten out any curvature or warping of the sheets P.

[0058] The pressing guide plate 471, which serves as a medium pressing member, is inclined with respect to the opposing surface of the second transport guide plate 480b. The inclined surface of the pressing guide plate 471 is inclined at a predetermined angle with respect to the transport direction of the paper P in the initial position. In other words, the pressing surface of the pressing guide plate 471 pressing the paper stack Pb is inclined so that the side closer to the rear end fence 410 is closer to the paper stack Pb and the side farther from the rear end fence 410 is farther from the paper stack Pb. In other words, the pressing surface of the pressing guide plate 471 is inclined in a direction away from the paper stack Pb as it moves away from the rear end fence 410.

[0059] The pressing guide plate 471 is held relative to the pressing guide fixing plate 472 via a pressing guide rotation fulcrum 476. The pressing guide plate 471 is rotatable relative to the pressing guide fixing plate 472 with the pressing guide rotation fulcrum 476 as a fulcrum.

[0060] In this embodiment, a pressing guide rotation fulcrum 476 that rotatably holds the pressing guide plate 471 has an elongated hole shape. The pressing guide plate 471 is held in a state in which it can move toward and away from the pressing guide fixing plate 472 by the operation of a pressing guide driving mechanism 474 that constitutes the pressing drive mechanism 470.

[0061] Furthermore, an elastic member 475 serving as an inclined surface holding member is disposed between the pressing guide plate 471 and the pressing guide fixing plate 472. The urging direction of the elastic member 475 is the direction in which the pressing guide plate 471 moves away from the pressing guide fixing plate 472. Therefore, when the pressing guide fixing plate 472 approaches the pressing guide plate 471 due to the operation of the pressing guide drive mechanism 474, the elastic member 475 urges the pressing guide plate 471 to press the paper stack Pb.

[0062] Further, near the end of the pressure guide fixing plate 472, a pressure guide stopper 473 is provided to restrict the movement of the pressure guide plate 471 in the direction of the sheet stack Pb.

[0063] The pressure guide fixing plate 472 is configured to be movable in the thickness direction of the paper-sheet stack Pb (the Y direction in FIG. 4) while maintaining its posture by the pressure guide drive mechanism 474. The pressure guide fixing plate 472 moves toward the paper-sheet stack Pb before the folding operation of the paper-sheet stack Pb by the folding blade 440. The pressure guide plate 471 then presses the paper-sheet stack Pb. This prevents the paper sheets P from curving or bending, allowing the folding process to be performed while maintaining high alignment accuracy of the edges of the paper-sheet stack Pb. Details of the movement mechanism of the pressure guide fixing plate 472 will be described later using FIG. 10.

[0064] [Relationship between the pressing guide plate 471 and the conveying guide plate 480] 5 and 6, the pressing guide plate 471 can also be considered to correspond to a part of the transport guide plate 480 (fourth transport guide plate 480d), which is a pair of plate-like members. The pressing guide plate 471 is disposed in a part of the fourth transport guide plate 480d that faces the second transport guide plate 480b, where the part is cut out, and forms part of the surface facing the second transport guide plate 480b. The pressing guide plate 471 is also shaped such that a part of the surface facing the second transport guide plate 480b is cut out.

[0065] The cutout portion of the pressure guide plate 471 corresponds to a space for arranging and moving a rear end fence 410 for regulating the position of the end of the paper sheet P. The rear end fence 410 is capable of moving in the conveyance direction in the cutout portion of the pressure guide plate 471 in accordance with the size of the paper sheet P, and positions the end of the paper sheet P (paper stack Pb) at a predetermined position.

[0066] 6, two elastic members 475 that bias the pressure guide plate 471 toward the paper stack Pb are provided, one upstream and one downstream in the paper transport direction of the pressure guide plate 471. In other words, at least one elastic member 475 is provided on the fulcrum side (see FIG. 4) where the pressure guide plate 471 rotates relative to the pressure guide fixing plate 472. At least one elastic member 475 is also provided on each of the two end faces separated by the notch on the rear end fence 410 side, which corresponds to the point of action. These elastic members 475 generate equal pressure force that presses the paper stack Pb on both end faces on the transport end side of the pressure guide plate 471, centered on the pressure guide rotation fulcrum 476.

[0067] The spring constant of each elastic member 475 is set to be the same. The spring constant may be selected appropriately depending on the degree of bending formed in the paper P. Also, different spring constants may be set on the upstream side and downstream side to correspond to the degree of bending or curvature, and the pressing force on the upstream side and downstream side may be set appropriately. Also, since it is sufficient for the elastic member 475 to supply the force with which the pressing guide plate 471 presses the paper stack Pb, it is sufficient that it is provided at at least one of the multiple locations exemplified above. Also, as exemplified in FIG. 6 etc., the elastic members 475 may be arranged at the vertices of a substantially equilateral triangle so that the pressing force is applied evenly to the pressing guide plate 471.

[0068] Furthermore, an elastic body other than a spring may be used as elastic member 475. For example, a thin plate-like member made of an elastic material may be used as elastic member 475. In that case, an elastic body may be provided on the entire surface of pressing guide fixing plate 472 (the surface on the pressing guide fixing plate 472 side).

[0069] [Pressing mechanism of pressure guide plate 471] Next, the pressing operation of the pressing guide plate 471 against the sheet bundle Pb formed by stacking sheets P will be described with reference to FIG. 7, particularly with regard to the movement of the rotating portion.

[0070] Fig. 7(a) is an enlarged view of the upper side end of pressure guide plate 471. As shown in Fig. 7(a), an arm member 4711 is provided to protrude from the end of pressure guide plate 471 on the folding blade 440 side, on the surface opposite the pressing surface for paper stack Pb. A pressure guide plate shaft 4711a is provided on arm member 4711 near the end in the protruding direction.

[0071] 7(b), an oval pressing guide plate shaft guide 4721 is provided at the end of the pressing guide fixing plate 472 on the folding blade 440 side. The pressing guide plate shaft guide 4721 has an elongated hole portion. A pressing guide bearing 4721a is attached to this elongated hole portion. The pressing guide bearing 4721a is slidable in the longitudinal direction of the elongated hole. The pressing guide bearing 4721a is urged toward the pressing guide plate 471 by a guide elastic member 4721b.

[0072] The pressing guide plate shaft 4711a is biased as described above while being rotatably attached to the pressing guide plate shaft guide 4721 via the pressing guide bearing 4721a. The biasing direction of the pressing guide plate shaft 4711a is a direction away from the pressing guide fixing plate 472.

[0073] 7(b) shows the initial state when the pressure guide plate 471 presses the paper stack Pb. In the initial state, the pressure guide plate 471 is inclined relative to the second transport guide plate 480b. In this inclined state, when the pressure guide fixing plate 472 moves toward the paper stack Pb by the operation of the pressure guide drive mechanism 474 (see FIG. 4), the pressure guide plate 471 begins to press the paper stack Pb due to the elastic force of the elastic member 475. Thereafter, as the pressure guide fixing plate 472 moves further toward the paper stack Pb, the inclination of the pressure guide plate 471 decreases, the pressure guide plate 471 approaches a parallel state with the second transport guide plate 480b, and the elastic force of the elastic member 475 no longer increases.

[0074] 7(c), the pressing guide plate 471 abuts against the sheet stack Pb and is approximately parallel to the second transport guide plate 480b, and the elastic member 475 is in a maximally contracted state. In this state, the pressing force Fp applied to the sheet stack Pb by the pressing guide plate 471 is based on the biasing force of the guide elastic member 4721b. In this way, the biasing force of the pressing guide plate 471 can eliminate the flexure formed in the sheet stack Pb.

[0075] 7(a) and 7(b), the pressure guide plate shaft guide 4721 is configured not to come into contact with the paper stack Pb while the pressure guide plate 471 is pressing the paper stack Pb. This makes it possible to prevent damage such as dents or tears from occurring in the paper stack Pb due to the pressing operation of the pressure guide plate 471.

[0076] [Effect of pressure guide plate 471] Next, an overview of the operation when the pressure guide fixing plate 472 is moved to press the paper stack Pb by the pressure guide plate 471 will be described using Figure 8. As shown in Figure 8(a), when the pressure guide fixing plate 472 moves in the direction of the paper stack Pb, the pressure guide fixing plate 472 is pressed by the elastic member 475 to press the paper stack Pb.

[0077] 8(a), this pressing operation starts from the end of sheet stack Pb on the rear end fence 410 side. Thereafter, as pressure guide fixing plate 472 moves, the position at which pressure guide plate 471 presses sheet stack Pb moves from the rear end fence 410 side toward the folding position (position of folding blade 440). Then, as shown in FIG. 8(a), when pressure guide plate 471 presses sheet stack Pb up to the side end of folding blade 440, the entire surface of pressure guide plate 471 presses sheet stack Pb.

[0078] According to the above-described operation of the pressing guide plate 471, the pressing position of the pressing guide plate 471 against the sheet P moves toward the leading edge of the sheet P in the conveyance direction, that is, from the rear end fence 410 side toward the folding blade 440 side. This movement of the pressing position causes the pressing guide plate 471 to press the sheet P while straightening out any curvature or warp in the sheet P.

[0079] That is, the pressure guide plate 471 presses the paper P so as to urge the paper P in the direction in which it would otherwise be displaced as a result of the curvature or warp being straightened toward the side where the end is open. This prevents the paper P from stretching toward the side where the end is positioned, improving the accuracy of aligning the end.

[0080] Then, as shown in Figure 8(b), when the pressure guide plate 471 reaches a state where it is pressing the paper stack Pb over its entire surface, the pressure guide fixing plate 472 moves toward the paper stack Pb, causing the pressure guide plate 471 to press the paper stack Pb via the pressure guide plate shaft 4711a.

[0081] By the pressing operation described above, the pressing guide plate 471 can move the curve or flexure of the sheet stack Pb toward the folding blade 440 without leaving it on the rear end fence 410 side. This makes it possible to align the leading edge of the sheet stack Pb evenly. As a result, it is possible to improve the accuracy of aligning the edges of the sheet stack Pb, and to improve the accuracy of the folding and binding positions.

[0082] 9 is a diagram illustrating the relative size relationship between the pressure guide plate 471 and different sized sheets P (sheet stack Pb). As already explained, the pressure surface of the pressure guide plate 471 that faces the sheet stack Pb has a rectangular shape with one side cut out inward. This cutout allows the rear end fence 410 to move up and down.

[0083] The width of the portion other than the notched portion is at least half the width (dimension in the X direction) of the paper P. In Fig. 9, the cases where the size of the paper P is A4 size and A3 size are shown as examples, and the direction of the short side is the width direction for each size.

[0084] In addition, the height dimension of the pressure guide plate 471 is a dimension that allows it to press up to a position equivalent to the length from the top surface of the rear end fence 410 to the nip of the folding roller pair 450, when the position of the rear end fence 410 when the size of the paper P is maximum is used as the base point.

[0085] [Configuration of pressure guide drive mechanism 474] Next, a description will be given of a movement mechanism for the pressure guide fixing plate 472 using the pressure guide drive mechanism 474. As shown in Fig. 10, the pressure guide fixing plate 472 is moved in the pressing direction of the paper stack Pb by the driving force of the drive motor 4740. The pressure guide drive mechanism 474 is composed of, for example, a pulley 4741 and a link arm 4742 that are rotated by the drive motor 4740. The pulley 4741 is rotatable in the forward direction (clockwise in Fig. 10) and the reverse direction (counterclockwise in Fig. 10) by receiving the rotational driving force from the drive motor 4740.

[0086] Furthermore, a connecting portion 4743 is provided on the side surface of the pressing guide fixing plate 472 facing the pulley 4741. One end of a link arm 4742 is rotatably attached to the side surface of the pulley 4741 by a rotating shaft 4745. The other end of the link arm 4742 is rotatably attached to the side surface of the pulley 4741 by a rotating shaft 4746. The connecting portion 4743 is movable in forward and reverse directions along a guide rail 4744. By rotating the pulley 4741 with the drive motor 4740, the connecting portion 4743 is moved in the Y direction along a guide rail (not shown) via the link arm 4742. By moving the connecting portion 4743, the pressing guide fixing plate 472 can be moved in the Y direction, i.e., in a direction toward or away from the pressing guide fixing plate 472.

[0087] Although the present embodiment employs a cam system, the same effect can be obtained by using other moving mechanisms such as a linear motor, a belt mechanism, a chain mechanism, or a solenoid.

[0088] [Effects of the pressure guide plate 471] Next, the effect of the pressing guide plate 471 will be described in detail with reference to FIG. 11. FIG. 11 is a diagram illustrating the relationship between the pressing guide plate 471 and the force acting on the paper stack Pb. As shown in FIG. 11, when the pressing guide plate 471 is flat, a pressing force Fp acts on the paper stack Pb in the initial stage when the pressing guide plate 471 contacts the paper stack Pb. Breaking down this pressing force Fp, as shown in FIG. 11, not only is there a force Fx, which is a force component in the X direction, but there is also a force Fz, which is a force component in the Z direction, generated, although very small, due to the relationship between the contact angle between the pressing guide plate 471 and the paper stack Pb.

[0089] The force Fz acts in a direction that moves the sheet stack Pb away from the rear end fence 410. Therefore, the force Fz changes the position of the leading edge of the sheet P that has been positioned by the rear end fence 410, and this force Fz may cause a misalignment at the end of the sheet stack Pb.

[0090] 12A and 12B show the pressing operation of the curvature-provided pressing guide plate 471 and the relationship between the pressing guide plate 471 and the force acting on the paper stack Pb. By providing an appropriate curvature to the pressing guide plate 471 as shown in FIGS. 12A and 12B, the pressing guide plate 471 can be pressed against the paper stack Pb in a state parallel to the conveyance direction of the paper P and perpendicular to the fence 422. As a result, as shown in FIG. 12C, the force Fz illustrated in FIG. 11 is not generated.

[0091] As described above, by effectively preventing the generation of force Fz from the initial stage when the pressing guide plate 471 comes into contact with the sheet stack Pb and starts pressing, the bottom end of the sheet stack Pb can be aligned more precisely by being in close contact with the rear end fence 410. In other words, the alignment accuracy of the end of the sheet stack Pb, and the accuracy of the folding position and saddle stitching position can be further improved.

[0092] [Flow of saddle stitching operation in the first embodiment] Next, the flow of the saddle stitching operation in the saddle stitching processing unit 400 according to this embodiment will be described with reference to Fig. 13. Below, the steps of the saddle stitching operation according to this embodiment will be described in the order of Figs. 13(a) to 13(g).

[0093] First, as shown in FIG. 13(a), the rear end fence 410 is moved from the home position (the dotted line position in FIG. 13(a)) to a predetermined position a to match the size of the paper P to be saddle-stitched. At the same time, the saddle-stitch jogger fence 420 is moved to a position that matches the width dimension of the paper P, and is ready to accept the paper P. The movement of the saddle-stitch jogger fence 420 is in the X direction. Here, the "predetermined position a" is a position for aligning the saddle-stitch position, which is set in advance for each size of paper P, with the position where the saddle-stitch stapler 430 will perform the binding process.

[0094] In the process illustrated in Fig. 13(a), Fig. 14(a) shows an example of the positions of the trailing edge fence 410 and the saddle stitching jogger fence 420 when the size of the paper P is A4 size. Fig. 14(b) shows an example of the positions of the trailing edge fence 410 and the saddle stitching jogger fence 420 when the size of the paper P is A3 size.

[0095] As illustrated in Figure 14(a), when the paper P is A4 size, the rear end fence 410 is located near the upper edge of the cutout portion of the pressure guide plate 471, and the saddle stitch jogger fence 420 is located near both side ends of the pressure guide plate 471.

[0096] Also, as illustrated in Figure 14(b), when the paper P is A3 size, the rear end fence 410 is located at a position equivalent to approximately half the height dimension of the cutout portion of the pressure guide plate 471, and the saddle stitching jogger fence 420 is located at its maximum width.

[0097] Returning to the saddle stitching operation, as shown in Fig. 13(b), the rear end fence 410 moves to a predetermined position a and positions the multiple sheets P discharged from the image forming apparatus 200. Then, the sheets P are stacked between the conveying guide plates 480 to form a stack of sheets Pb.

[0098] Next, as shown in Figure 13(c), the drive motor 4740 of the drive mechanism of the pressure guide fixing plate 472 is rotated forward (rotation in the direction of the arrow shown in the figure), the pressure guide drive mechanism 474 is extended, and the pressure guide plate 471 is moved to a position where it presses the paper stack Pb.

[0099] Subsequently, as shown in FIG. 13(d), when the pressing operation of the pressing guide plate 471 against the sheet stack Pb is completed, the drive motor 4740 is stopped.

[0100] Next, as shown in Fig. 13(e), the saddle stitch stapler 430 staples the sheet bundle Pb at the target binding position. At this time, the relationship between the position of the saddle stitch stapler 430 and the sheets P is as shown in Fig. 14(a) and Fig. 14(b). In Fig. 14, the "target binding position" for the sheets P is indicated by a white dotted line. In the following similar figures, the predetermined position that becomes the target binding position is also indicated by a white dotted line.

[0101] Returning to the saddle stitching operation, the rear end fence 410 is then lowered so that the target binding position of the stapled sheet bundle Pb is aligned with the folding position of the folding blade 440, as shown in Fig. 13(f). Furthermore, if the pressure guide plate 471 applies a pressing force to the sheet bundle Pb when the rear end fence 410 is lowered, the sheet bundle Pb may not be able to be smoothly lowered to the target position.

[0102] Therefore, at the same time as lowering the rear end fence 410, or before starting the lowering operation, the drive motor 4740 of the pressure guide drive mechanism 474 is slightly reversed to release the pressure of the pressure guide plate 471 on the paper stack Pb.

[0103] 13(g), the drive mechanism moves the folding blade 440 toward the nip of the pair of folding rollers 450, and the binding position of the sheet bundle Pb is pushed into the nip of the pair of folding rollers 450. This executes the saddle stitch folding process.

[0104] In the process illustrated in Fig. 13(g), Fig. 15(a) shows an example of the positions of the trailing edge fence 410 and the saddle stitching jogger fence 420 when the size of the paper P is A4 size. Fig. 15(b) shows an example of the positions of the trailing edge fence 410 and the saddle stitching jogger fence 420 when the size of the paper P is A3 size.

[0105] As illustrated in Figure 15(a), when the paper P is A4 size, the rear end fence 410 lowers to a position equivalent to approximately half the height dimension of the cutout portion of the pressure guide plate 471, thereby moving the binding position to a position opposite the nip of the folding roller pair 450.

[0106] Then, as illustrated in Figure 15(b), when the paper P is A3 size, the rear end fence 410 is moved to near the bottom end of the cutout portion of the pressure guide plate 471, and the binding position is moved to a position opposite the nip of the folding roller pair 450.

[0107] 13(g), when the bound portion of paper-sheet bundle Pb is pushed into the nip between pair of folding rollers 450, drive motor 4740 is further rotated in the reverse direction to return pressure guide fixing plate 472 to the home position. Note that pressure guide fixing plate 472 may be returned to the home position after the folding operation by folding blade 440 is completed.

[0108] In this embodiment, A4 size and A3 size are exemplified as the sizes of the paper P, but this embodiment does not limit the size of the paper P to these. For example, similar processing can be performed on B5 size or B4 size paper P.

[0109] [Flow of center-folding operation according to the first embodiment] Next, the flow of the center-folding operation in the saddle-stitching processing unit 400 according to this embodiment will be described with reference to Figure 16. The steps of the center-folding operation will be described below in the order of Figures 16(a) to 16(e). The difference from the saddle-stitching operation already described is that there is no binding process corresponding to Figures 13(e)-(f).

[0110] First, as shown in FIG. 16(a), the rear end fence 410 is moved from the home position to a predetermined position a to match the size of the sheet P to be center-folded. At the same time, the saddle stitching jogger fence 420 is moved to a position that matches the width dimension of the sheet P, and is ready to accept the sheet P. The movement of the saddle stitching jogger fence 420 is in the X direction. Here, the "predetermined position a" is a position for aligning the center-folding position, which is set in advance for each size of sheet P, with the position of the folding blade 440.

[0111] Subsequently, as shown in FIG. 16(b), a plurality of sheets P discharged from the image forming apparatus 200 are stacked between the conveying guide plates 480 to form a sheet stack Pb.

[0112] Next, as shown in Figure 16(c), the drive motor 4740 of the drive mechanism of the pressure guide fixing plate 472 is rotated forward (rotation in the direction of the arrow shown in the figure), the pressure guide drive mechanism 474 is extended, and the pressure guide plate 471 is moved to a position where it presses the paper stack Pb.

[0113] Subsequently, as shown in FIG. 16(d), when the pressing operation of the pressing guide plate 471 against the sheet stack Pb is completed, the drive motor 4740 is stopped.

[0114] 16(e), while maintaining the attitude of pressure guide plate 471 (the distance from the conveying guide plate), folding blade 440 is moved by the drive mechanism toward the nip of folding roller pair 450. As a result, the binding position of paper stack Pb is pushed into the nip of folding roller pair 450, and the center folding process is performed.

[0115] 16(e), when the bound portion of paper-sheet bundle Pb is pushed into the nip between pair of folding rollers 450, drive motor 4740 is rotated in the reverse direction to return pressure guide fixing plate 472 to the home position. Note that pressure guide fixing plate 472 may be returned to the home position after the folding operation by folding blade 440 is completed.

[0116] [Second embodiment] Next, a second embodiment of the sheet processing apparatus according to the present invention will be described. Fig. 17 is an enlarged structural view of a saddle stitching processing unit 400a provided in a sheet processing apparatus 300 according to this embodiment. Fig. 18 is a side view of the saddle stitching processing unit 400a according to this embodiment, seen from the pressure drive mechanism 470 side. Fig. 19 is a side view of the saddle stitching processing unit 400a according to this embodiment, in which the pressure guide fixing plate 472 and pressure guide drive mechanism 474 that constitute the pressure drive mechanism 470 are omitted.

[0117] The main difference between the second embodiment and the first embodiment is that the second embodiment uses a pressure roller 477 as a pressure position moving member that moves in the opposite direction to the conveying direction while pressing the paper stack Pb, instead of the pressure guide plate 471 according to the first embodiment. Note that the same components as those in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted.

[0118] As shown in Fig. 17, pressure roller 477 as a medium pressing member is configured to be movable in the stacking direction of paper stack Pb (Y direction in Fig. 17) and the length direction of paper stack Pb (Z direction in Fig. 17). Movement in the stacking direction is movement in the pressing direction of paper stack Pb, and is performed by movement of pressure guide fixed plate 472. Movement in the length direction of paper stack Pb is the direction in which pressure roller 477 moves while pressing against paper stack Pb. Movement of pressure roller 477 is performed by linear actuator 478 as a roller moving member fixed to pressure guide fixed plate 472 as a roller moving member constituting the medium pressing member.

[0119] 17 (Z direction), the pressure roller 477 sequentially presses the sheet stack Pb from the bottom end portion (rear end fence 410 side) toward the folding blade 440.

[0120] [Pressing mechanism of pressure roller 477] Next, the pressing operation of the pressure roller 477 against the paper stack Pb will be roughly explained using Figure 20. Figure 20(a) is an enlarged view of the drive mechanism of the pressure roller 477. Figure 20(b) is an explanatory view of the support mechanism of the pressure roller 477. Figure 20(c) is a diagram illustrating the pressing operation of the pressure roller 477.

[0121] The pressure roller 477 has pressure roller shafts 4771 at both ends slidably attached to pressure roller fixing plates 4782 via pressure roller bearings 4784. The pressure roller fixing plates 4782 are fixed to the linear actuator 478.

[0122] The pressure roller bearing 4784 is biased by the pressure member 4873 in a direction in which the pressure roller 477 moves away from the linear actuator 478 (the stacking direction of the paper stack Pb). When the pressure guide fixing plate 472 moves in the stacking direction of the paper stack Pb (moves a distance X in the pressing direction), the pressure roller 477 is displaced from the state shown in Figure 20(b) to the state shown in Figure 20(c) (the state in which the pressure roller 477 abuts against the paper stack Pb). This displacement causes a biasing force to act on the pressure roller 477 due to the contraction of the pressure member 4873, generating a pressing force of the pressure roller 477 against the paper stack Pb.

[0123] The linear actuator 478 is a drive mechanism that moves the plate 4781 up and down using a linear motor, and can move the pressure roller 477 via a pressure roller fixing plate 4782 attached to the end of the plate 4781 .

[0124] 21 is a diagram illustrating the relative size relationship between the pressure roller 477 and different sized stacks of paper Pb. As shown in FIG. 21, the pressure roller 477 is configured to be able to press about half the width of the maximum size (e.g., A3 size) of the stack of paper Pb.

[0125] The pressure roller 477 is disposed in a cutout portion of the pair of plate-like members, namely, the transport guide plate 480 (fourth transport guide plate 480d), and is disposed in a position facing the second transport guide plate 480b. The pressure roller shaft 4771 has a length that fits within the width of the cutout portion of the fourth transport guide plate 480d, and both ends are supported by the linear actuator 478.

[0126] [Relationship between the pressure roller 477 and the rear end fence 410] Next, the relationship between the pressure roller 477 and the trailing end fence 410 will be described with reference to Figure 22. Figure 22 is a view of the saddle stitching processing unit 400a as seen from the trailing end fence 410 side.

[0127] Fig. 22(a) illustrates a state in which paper sheet P is received and pressure roller 477 is located at the home position. Fig. 22(b) is an enlarged view of pressure roller 477 at the home position, viewed from the width direction of paper sheet P. As shown in Fig. 22(b), pressure roller 477 at the home position (initial position) is separated from paper stack Pb, which is the object to be pressed. In other words, the home position is the position where pressure roller 477 is separated from the leading edge of paper sheet P in the transport direction, facing the leading edge.

[0128] Fig. 22(c) is a diagram showing a state in which paper sheets P have been received to form a paper stack Pb, and pressure roller 477 is moving while pressing paper stack Pb. Fig. 22(d) is an enlarged view of pressure roller 477 moving while pressing paper stack Pb, as seen from the width direction of paper sheets P.

[0129] The direction of movement of the pressure roller 477 is from the rear end fence 410 side toward the folding blade 440 side, which is the opposite direction to the direction in which the paper P is conveyed into the gap formed by the conveyance guide plate 480.

[0130] As shown in FIG. 22, the pressure roller 477 is composed of multiple rollers attached to a pressure roller shaft 4771 extending in the width direction of the paper P. The multiple rollers are arranged at predetermined intervals in the axial direction of the pressure roller shaft 4771. A trailing edge fence 410 is provided at the position between the rollers. As shown in FIG. 22(c), the widthwise size of each trailing edge fence 410 is smaller than the spacing between the multiple rollers so that the trailing edge fence 410 does not interfere with the multiple rollers when the pressure roller 477 moves in the stacking direction of the paper stack Pb. As shown in FIG. 22(d), the trailing edge fence 410 is provided at a position so that the trailing edge fence 410 does not interfere with the pressure roller shaft 4771 when the pressure roller 477 moves in the stacking direction of the paper stack Pb. Configuring the size and position of the trailing edge fence 410 in this manner allows the pressure roller 477 to firmly press against the end of the paper stack Pd on the trailing edge fence 410 side, thereby improving the alignment accuracy of the end of the paper stack Pb.

[0131] Furthermore, the rear end fence 410 moves to a predetermined position in accordance with the size of the paper P, and is therefore structured to move in the spaces between the rollers that make up the pressure roller 477.

[0132] With the above structure, even when the pressure roller 477 moves from the rear end fence 410 toward the folding blade 440, it does not interfere with the rear end fence 410, and can firmly press the end of the paper stack Pb on the rear end fence 410 side.

[0133] 22, the rear end fence 410 is disposed in the gap between the rollers constituting the pressure roller 477 to prevent interference between the pressure roller 477 and the rear end fence 410. However, as shown in FIG. 23, the rear end fence 410 can also be disposed outside the axial range of the pressure roller 477. By disposing the rear end fence 410 outside the axial range of the pressure roller 477 in this way, the pressure roller 477 can be made into a single continuous roller member.

[0134] As a result, as shown in Figure 24, compared to when the pressure roller 477 is composed of multiple rollers, there are no gaps in the area where the pressure roller 477 presses the paper stack Pb, and pressure can be applied by a continuous surface, further improving the effect of removing sagging from the paper stack Pb.

[0135] [Modification of the second embodiment] Next, a modified example of the second embodiment of the sheet processing device according to the present invention will be described. Figure 25 is an enlarged structural view of the saddle stitching processing unit 400a provided in the sheet processing device 300 according to this embodiment. Note that the same components as those described so far are given the same reference numerals, and detailed description will be omitted. Figure 25, like Figure 22(a), is a view of the saddle stitching processing unit 400a as seen from the rear end fence 410 side.

[0136] 25, in this embodiment, a pressure roller 477 consisting of multiple rollers is used, and a fourth conveying guide plate 480d is provided on the saddle stitching jogger fence 420. This allows part of the pair of conveying guide plates 480 to be omitted, which also simplifies the device and reduces costs.

[0137] 25(a) is maintained in a state where the pressure roller 477 is pressing the paper stack Pb (pressure roller 477 is in the lowest position), and the pressure roller 477 is moved to the position where the folding blade 440 is located. In this case, the pressure roller fixing plate 4782 and the fourth conveying guide plate 480d interfere with each other.

[0138] Therefore, as shown in FIG. 25(b), the fourth conveying guide plate 480d is disposed near the tip of the saddle stitching jogger fence 420 and is rotatably attached to the side opposite the sheet P storage side. The driving force for rotating the fourth conveying guide plate 480d can be provided via a predetermined driving mechanism of a motor. Then, the fourth conveying guide plate 480d is retracted from the inside to the outside of the saddle stitching jogger fence 420 in conjunction with the movement of the pressure roller 477. This makes it possible to prevent the above-mentioned interference.

[0139] [Flow of saddle stitching operation in the second embodiment] Next, the flow of the saddle stitching operation in the saddle stitching processing unit 400a according to this embodiment will be described with reference to Figure 26. Below, the steps of the saddle stitching operation according to this embodiment will be described in the order of Figures 26(a) to 26(g).

[0140] First, as shown in FIG. 26(a), the rear end fence 410 is moved from the home position (the dotted line position in FIG. 26(a)) to a predetermined position a to match the size of the paper P to be saddle-stitched. At the same time, the saddle-stitch jogger fence 420 is moved to a position that matches the width dimension of the paper P, and is ready to accept the paper P. The movement of the saddle-stitch jogger fence 420 is in the X direction. Here, the "predetermined position a" is a position for aligning the saddle-stitch position, which is set in advance for each size of paper P, with the position where the saddle-stitch stapler 430 will perform the binding process.

[0141] Furthermore, prior to the movement of the rear end fence 410, the pressure roller 477 is moved from the home position to a predetermined position b. Here, the "predetermined position b" is a position where the pressure roller 477 does not interfere with the rear end fence 410 when moved toward the sheet stack Pb and can press the bottom end of the sheet stack Pb. As described above, when the image forming apparatus 200 is ready to receive the sheets P, the multiple sheets P discharged from the image forming apparatus 200 are stacked to form the sheet stack Pb. Note that the timing at which the pressure roller 477 is moved from the home position to the predetermined position b may be the same as the timing at which the rear end fence 410 is moved from the home position to the predetermined position a.

[0142] Returning to the process of the saddle stitching operation, as shown in Fig. 26(b), the drive motor 4740 of the drive mechanism of the pressure guide fixing plate 472 is rotated forward (rotation in the direction of the arrow in Fig. 26(b)), the pressure guide drive mechanism 474 is extended, and the pressure roller 477 is moved to a position where it presses the paper stack Pb.

[0143] Next, as shown in FIG. 26(c), while the pressure roller 477 is still pressing the paper P, the linear actuator 478 is driven to move the pressure roller 477 in the Z direction.

[0144] Subsequently, as shown in FIG. 26(d), when the pressure roller 477 reaches the maximum raised position (near the folding blade 440), the driving of the linear actuator 478 is stopped, and this state is maintained.

[0145] Subsequently, as shown in FIG. 26(e), the saddle stitch stapler 430 staples the sheet bundle Pb at the target binding position.

[0146] 26(a) to 26(e), the positions of the trailing edge fence 410 and the saddle stitching jogger fence 420 when the size of the paper P is A4 are shown in FIG. 27(a). Similarly, the positions of the trailing edge fence 410 and the saddle stitching jogger fence 420 when the size of the paper P is A3 are shown in FIG. 27(b).

[0147] As illustrated in Figures 27(a) and 27(b), the position of the rear end fence 410 is different whether the paper P is A4 size or A3 size, but the position of the pressing roller 477 when the pressing process and binding process are completed is the same.

[0148] Returning to the saddle stitching process, as shown in Figure 26(f), the rear end fence 410 is lowered so that the target binding position of the stapled sheet bundle Pb is aligned with the folding position by the folding blade 440. If the pressure roller 477 applies a pressing force to the sheet bundle Pb when the rear end fence 410 is lowered, there is a possibility that the sheet bundle Pb may not be smoothly lowered to the target position.

[0149] Therefore, at the same time as lowering the rear end fence 410, or before starting the lowering operation, the drive motor 4740 of the pressure guide drive mechanism 474 is rotated slightly in the reverse direction to release the pressure roller 477 from the pressure on the paper stack Pb.

[0150] 26(g), the drive mechanism moves the folding blade 440 toward the nip of the pair of folding rollers 450, and the binding position of the sheet bundle Pb is pushed into the nip of the pair of folding rollers 450. This executes the saddle stitch folding process.

[0151] 26(g), when the bound portion of paper-sheet bundle Pb is pushed into the nip of pair of folding rollers 450, drive motor 4740 is further rotated in the reverse direction to return pressure roller 477 to the home position. Note that the timing for returning pressure guide fixing plate 472 to the home position may be after the folding operation by folding blade 440 is completed. Note that the timing for returning pressure guide fixing plate 472 to the home position may be after the folding operation by folding blade 440 is completed.

[0152] 26(f) and (g), the positions of the trailing edge fence 410 and the saddle stitching jogger fence 420 when the size of the paper P is A4 are shown in FIG. 28(a). Similarly, the positions of the trailing edge fence 410 and the saddle stitching jogger fence 420 when the size of the paper P is A3 are shown in FIG. 28(b).

[0153] As shown in FIGS. 28(a) and 28(b), the pressure roller 477 moves from the position of the rear end fence 410 to the vicinity of the folding blade 440 whether the paper P is A4 size or A3 size.

[0154] In this embodiment, A4 size and A3 size are exemplified as examples of the sizes of the paper P, but this embodiment does not limit the size of the paper P to these. For example, similar processing can be performed on B5 size or B4 size paper P.

[0155] [Flow of center-folding operation according to the second embodiment] Next, the flow of the center-folding operation in the saddle-stitching processing unit 400a according to this embodiment will be described with reference to Figure 29. The steps of the center-folding operation will be described below in the order of Figures 29(a) to 29(e). The difference from the saddle-stitching operation already described is that there is no binding process corresponding to Figures 26(e)-(f).

[0156] First, as shown in Figure 29(a), the rear end fence 410 is moved from the home position to a predetermined position a to match the size of the sheet P to be center-folded. Here, the "predetermined position a" is a position for aligning the center-fold position, which is set in advance for each size of sheet P, with the position of the folding blade 330. At the same time, the saddle stitching jogger fence 420 is moved to a position that matches the width dimension of the sheet P, and is ready to accept the sheet P. The movement of the saddle stitching jogger fence 420 is in the X direction.

[0157] Furthermore, prior to the movement of the rear end fence 410, the pressure roller 477 is moved from the home position to a predetermined position b. Here, the "predetermined position b" is a position where the pressure roller 477 does not interfere with the rear end fence 410 when moved toward the paper stack Pb and can press the bottom end of the paper stack Pb.

[0158] 29(a) shows the state after the above initial adjustment operation is completed. Once the image forming apparatus 200 is ready to receive the sheets P as described above, the sheets P discharged from the image forming apparatus 200 are stacked to form a sheet bundle Pb. The timing at which the pressure roller 477 is moved from the home position to the predetermined position b may be the same as the timing at which the rear end fence 410 is moved from the home position to the predetermined position a.

[0159] Next, as shown in Figure 29(b), the drive motor 4740 of the drive mechanism of the pressure guide fixing plate 472 is rotated forward (rotation in the direction of the arrow shown in the figure), the pressure guide drive mechanism 474 is extended, and the pressure roller 477 is moved to a position where it presses the paper stack Pb.

[0160] Next, as shown in FIG. 29(c), while the pressure roller 477 is still pressing the sheet stack Pb, the linear actuator 478 is driven to move the pressure roller 477 toward the folding blade 440.

[0161] Subsequently, as shown in FIG. 29(d), when the pressure roller 477 reaches the maximum raised position, the driving of the linear actuator 478 is stopped and this state is maintained.

[0162] 29(e), while maintaining the position of pressure roller 477, the drive mechanism moves folding blade 440 toward the nip of folding roller pair 450. As a result, the binding position of paper stack Pb is pushed into the nip of folding roller pair 450, and the center folding process is performed.

[0163] When the target folding position of the paper stack Pb is pushed into the nip of the pair of folding rollers 450 by the pushing operation of the folding blade 440, the drive motor 4740 is reversed to minimize the contraction of the pressure guide drive mechanism 474 and return the pressure roller 477 to the home position. The timing for returning the pressure roller 477 to the home position may be after the folding operation by the folding blade 440 is completed.

[0164] The saddle stitching processing unit 400 or saddle stitching processing unit 400a according to the present embodiment described above can suppress misalignment of the folding position that occurs when pressing the entire surface of the paper P at once to remove slack, as in the prior art. This improves the accuracy of aligning the edges of the paper stack Pb, particularly when saddle stitching or center folding is performed.

[0165] According to this embodiment, a method for removing curvature or warping from the sheets P is to sequentially press the sheets P from the edge side that is restricted for positioning toward the edge side that is freely displaceable, thereby moving the curvature or warping toward the folding position. This allows the curvature or warping to be removed (released) without displacing the edge side that is restricted for positioning, and creates a state in which the positions of the sheets P are aligned at the folding position. In other words, folding and binding processes are performed with the distances from each edge of multiple sheets P to the folding position aligned, thereby improving the alignment accuracy of the edges of the sheet stack Pb.

[0166] The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the technical gist thereof. The present invention covers all technical matters included in the technical ideas described in the claims. The above-described embodiments are preferred examples, but a person skilled in the art can realize various modifications from the disclosed contents. Such modifications are also included in the technical scope described in the claims. [Explanation of symbols]

[0167] 200: Image forming device 300: Paper handling device 400: Saddle stitching processing unit 410: Rear fence 420: Jogger Fence 422: Fence 430: Stapler 440: Folding blade 441: Cam 441a: Groove 442: Drive shaft 450: Pair of folding rollers 460: Paper ejection roller 470: Press drive mechanism 471: Pressure guide plate 472: Pressure guide fixing plate 473: Pressure guide stopper 474: Pressure guide drive mechanism 475: Elastic member 476: Pressure guide rotation fulcrum 477: Pressure roller 478: Linear Actuator 480: Transport guide plate 480a: First conveying guide plate 480b: Second conveying guide plate 480c: Third transport guide plate 480d: Fourth transport guide plate 600: Image forming system 4711: Arm parts 4711a: Pressure guide plate shaft 4721: Pressure guide plate shaft guide 4721a: Pressure guide bearing 4721b: Guide elastic member 4740: Drive motor 4741: Pulley 4742: Link arm 4743: Connection 4744: Guide rail 4745: Rotating shaft 4746: Rotating shaft 4771: Pressure roller shaft 4781: Plate 4782: Pressure roller fixing plate 4784: Pressure roller bearing 4873: Pressure member [Prior art documents] [Patent documents]

[0168] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-018638

Claims

1. A sheet processing apparatus that processes a sheet-like medium transported between a pair of transport guide members at a predetermined position in a transport direction, a pushing member that pushes the predetermined position of the medium toward a processing member; a medium pressing member that presses the medium transported between the pair of transport guide members; Equipped with The medium pressing member is a pressure guide plate having an inclined surface relative to the conveying guide member; an inclined surface holding member that is an elastic member that holds the inclined surface so that, at an initial position, the gap between the transport guide member and the pressure guide plate is wider on the predetermined position side than on the end side in the transport direction of the medium, and that presses the back surface of the pressure guide plate at least on the end side in the transport direction and on the predetermined position side; an inclined surface moving member that moves the pressing guide plate toward the conveying guide member; Equipped with pressing the end side of the medium in the transport direction and then pressing the predetermined position side; A sheet processing apparatus characterized by:

2. A sheet processing apparatus that processes a sheet-like medium transported between a pair of transport guide members at a predetermined position in the transport direction. a pushing member that pushes the predetermined position of the medium toward a processing member; a medium pressing member that presses the medium transported between the pair of transport guide members; Equipped with The medium pressing member is a pressure guide plate having an inclined surface relative to the conveying guide member; an inclined surface holding member that is a planar elastic member that holds the inclined surface so that, in an initial position, the gap between the transport guide member and the pressure guide plate is wider on the predetermined position side than on the end portion in the transport direction of the medium, and that presses the back surface of the pressure guide plate; an inclined surface moving member that moves the pressing guide plate toward the conveying guide member; Equipped with the medium pressing member presses the end side in the transport direction and then presses the predetermined position side; A sheet processing apparatus characterized by:

3. the medium pressing member presses the medium against one of the pair of transport guide members; The sheet processing apparatus according to claim 1 or 2.

4. the medium pressing member presses the medium while moving a pressing position of the medium from an end in the transport direction toward the predetermined position; The sheet processing apparatus according to claim 1 .

5. an alignment member that aligns an edge of the medium in the transport direction; The sheet processing apparatus according to claim 1 .

6. The sheet processing apparatus according to claim 1 , wherein the pressure guide plate has a width that is at least half the width of the medium.

7. the inclination angle of the inclined surface of the pressing guide plate increases as the pressing guide plate is moved toward the transport guide member by the inclined surface moving member and comes into contact with and presses the medium; The sheet processing apparatus according to claim 1 .

8. the pressing guide plate is moved by the inclined surface moving member toward the transport guide member to contact and press the medium, and the position of the inclined surface that contacts the medium moves from the end in the transport direction toward the predetermined position. The sheet processing apparatus according to claim 1 .

9. A sheet processing apparatus that processes a sheet-like medium transported between a pair of transport guide members at a predetermined position in a transport direction, a pushing member that pushes the predetermined position of the medium toward a processing member; a medium pressing member that presses the medium transported between the pair of transport guide members; Equipped with The medium pressing member is a pressure roller that presses the medium against the transport guide member; a pressing position moving member that moves the pressing position of the pressure roller on the medium; a roller moving member that moves the pressure roller toward the transport guide member, the pressure roller is held by the pressure position moving member via an elastic member and is biased toward the transport guide member; the medium pressing member presses the end side of the medium in the transport direction and then presses the predetermined position side; A sheet processing apparatus characterized by:

10. The sheet processing apparatus according to claim 9 , wherein the pressure roller is spaced apart from the medium at an initial position opposite an end of the medium in the transport direction.

11. The sheet processing apparatus according to claim 9 , wherein the pressure roller has a length that presses approximately half of the medium in the width direction.

12. The sheet processing apparatus according to claim 9 , wherein a plurality of the pressure rollers are arranged in the width direction of the medium.

13. an image forming device that forms an image on a conveyed sheet-like medium; 13. An image forming system comprising: the sheet processing apparatus according to claim 1, which transports the medium on which an image has been formed between a pair of transport guide members and processes the medium at a predetermined position.

14. the image forming apparatus, The image forming system according to claim 13, wherein an image is formed by ejecting a liquid onto a sheet-like medium that is conveyed.

Images