Sheet binding device and sheet post-processing device equipped with the same

Abstract

To provide a sheet binding device and a sheet post-processing device capable of avoiding interference between a staple portion and a reference plate and maintaining the alignment of a sheet stack.SOLUTION: A sheet binding device includes a processing tray, a movable reference plate, a staple unit, a moving unit, a slide member and a slide spring. When the staple unit is moved from the reference position to the staple position in an inclined state, a staple-side engaging portion presses the movable engaging member of the slide member, causing the movable reference plate to move from the initial position, and when the staple unit changes its posture from the inclined state to the parallel state, the movable reference plate returns to the initial position. When the staple unit changes its posture from the parallel state to the inclined state during movement from the staple position to the reference position, the staple-side engaging portion presses the movable engaging member, causing the movable reference plate to move from the initial position, and when the staple-side engaging portion moves away from the movable engaging member, the movable reference plate returns to the initial position.SELECTED DRAWING: Figure 16

Description

[Technical Field]

[0001] The present invention relates to a sheet binding device that binds a plurality of sheets after images have been formed on them by an image forming apparatus, and a sheet post-processing device including the same. [Background technology]

[0002] Sheet post-processing devices are known that stack multiple sheets after images have been formed on them by an image forming device such as a copier or printer, and perform processes such as binding, stapling, punching, and folding. When performing the binding process on a sheet stack, it is necessary to precisely align sheets of various sizes in a predetermined binding position. Therefore, a commonly used configuration aligns the sheets by abutting their trailing edges against a reference plate (trailing-edge stopper) that regulates the position of the sheets in the conveyance direction.

[0003] In the above configuration, the position of the reference plate that the sheet abuts in the direction perpendicular to the conveyance direction (sheet width direction) must be appropriate for the sheet size, or alignment will deteriorate. To address this issue, the number of reference plates has been increased or the width of the plate that contacts the sheet has been widened. However, when the stapler is moved to drive staples into the sheet at the specified position, there is a risk that the reference plate may be pinched or the sheet alignment may be disrupted.

[0004] Therefore, a method has been proposed in which the reference plate is moved to prevent it from being pinched and damaged by the stapler. For example, Patent Document 1 describes a paper post-processing device that includes a pair of first stoppers located on both sides of the stapler and a pair of second stoppers located outside the first stoppers, and the first stoppers are fixed to the staple unit. Because the first stoppers move integrally with the stapler in a direction perpendicular to the conveyance direction, it is easier to achieve positional accuracy between the stapler and the first stoppers, and variation in the binding position from the edge of the paper stack can be reduced.

[0005] Patent Document 2 discloses a staple processing device (sheet binding device) that prevents misalignment of sheets loaded for binding processing. The staple processing device includes a processing tray, a staple unit, a rear reference plate, a front reference plate, and an interlocking mechanism. The staple unit is movable in the sheet width direction along the edge of the sheets. The rear reference plate and the front reference plate abut against the edge of multiple sheets to align the multiple sheets. The interlocking mechanism moves the rear reference plate and the front reference plate in the sheet width direction in conjunction with the movement of the staple unit. By using the interlocking mechanism to move the reference plates in the sheet width direction in conjunction with the movement of the staple unit, interference between the staple unit and the reference plates when stapling is prevented, and sheets can be stably stapled. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-119206 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-221709 Summary of the Invention [Problem to be solved by the invention]

[0007] In the configuration of Patent Document 1, the first stopper and the stapler are positioned at a uniform distance, so when using wide paper, the distance between the two rear end stoppers becomes large, causing the paper to sag in the center and resulting in misalignment.

[0008] In the configuration of Patent Document 2, the staple unit is placed in the binding position in advance, so when the sheets are stacked, the reference plate is moved in the sheet width direction in conjunction with the movement of the staple unit to the binding position. As a result, in the case of narrow sheets, either the rear reference plate or the front reference plate may move outward in the sheet width direction, and the sheet may be received by only two reference plates. Therefore, when it is difficult to align the sheets or when the sheets are prone to skew, there is a problem of poor sheet alignment.

[0009] Furthermore, when staples are driven into the widthwise edge of a sheet, the staples are sometimes driven at an angle to prevent the sheet from tearing easily due to the holes made by the staples, which is known as diagonal binding. In this case, depending on the size of the sheets to be diagonally bound, the position at which the staple unit is rotated diagonally may overlap with the initial position of the reference plate. As a result, when the staple unit rotates, it interferes with the reference plate, preventing the staple unit from rotating and causing damage to the reference plate.

[0010] In view of the above problems, the present invention aims to provide a sheet binding device and a sheet post-processing device equipped with the same that can avoid interference between the staple portion and the reference plate when performing the binding process and can maintain the alignment of the sheet stack. [Means for solving the problem]

[0011] To achieve the above object, a first configuration of the present invention is a sheet binding device including a processing tray, a movable reference plate, a stapler, a moving unit, a slide member, and a slide spring. The processing tray is loaded with a plurality of sheets transported in a predetermined transport direction. The movable reference plate is disposed at a predetermined initial position where it can align the sheets by contacting the downstream edge of the sheets transported onto the processing tray in an alignment direction, which is opposite to the transport direction, and is movable from the initial position in a sheet width direction perpendicular to the transport direction. The stapler is disposed opposite the edge of the sheets and performs a stapling process by staple-stapling the plurality of sheets stacked on the processing tray at predetermined positions. The moving unit moves the stapler along the edge of the sheets to a reference position that is outboard of the initial position in the sheet width direction and at least one stapling position that is inboard of the initial position in the sheet width direction. The moving unit is capable of changing the orientation of the stapler between an inclined state inclined obliquely with respect to the edge of the sheets and a parallel state parallel to the edge of the sheets. The slide member has a movable reference plate attached thereto and is reciprocally movable along the sheet width direction. The slide spring biases the slide member in a direction that moves the movable reference plate closer to the initial position. The slide member has a movable engagement member that comes into contact with the staple-side engagement portion of the staple portion when the staple portion moves between the reference position and the staple position. When the movable reference plate is arranged at the initial position and the staple portion is moved from the reference position to the staple position in an inclined state, the staple-side engagement portion presses the movable engagement member, causing the movable reference plate to move inward in the sheet width direction together with the slide member against the biasing force of the slide spring. When the staple portion changes its posture from the inclined state to a parallel state before reaching the staple position, the staple-side engagement portion moves away from the movable engagement member, causing the movable reference plate to move outward in the sheet width direction together with the slide member due to the biasing force of the slide spring and return to the initial position. When the staple portion changes its position from a parallel state to an inclined state while moving from the staple position to the reference position, the staple side engagement portion presses the movable engagement member, causing the movable reference plate to move inward in the sheet width direction from the initial position together with the slide member against the biasing force of the slide spring.When the staple portion moves to the reference position, the staple-side engaging portion moves away from the movable engaging member, and the movable reference plate moves outward in the sheet width direction together with the slide member due to the biasing force of the slide spring, returning to its initial position. [Effects of the Invention]

[0012] According to the first configuration of the present invention, the movable reference plate can be positioned at a position required for performing a predetermined stapling process, and interference between the staple unit and the movable reference plate can be avoided. Therefore, stapling can be performed stably on sheets without compromising sheet alignment. Furthermore, when the staple unit changes its position from an inclined state to a parallel state, there is no risk of the movable reference plate interfering with the staple unit or impeding the rotation of the staple unit, and deformation or damage to the movable reference plate can also be prevented. Furthermore, since no drive source is required to move the movable reference plate, the sheet binding device is inexpensive and has high alignment. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an image forming system including a sheet post-processing device 1 equipped with a sheet binding unit 92 according to an embodiment of the present invention, and an image forming device 200 to which the sheet post-processing device 1 is connected. [Figure 2] FIG. 1 is a side cross-sectional view schematically illustrating a configuration of a sheet post-processing device 1 including a sheet binding unit 92 according to an embodiment of the present invention. [Figure 3] FIG. 1 is a perspective view of a sheet binding unit 92 according to the present embodiment; [Figure 4] 1 is a side view of a sheet binding unit 92 according to the present embodiment; [Figure 5] FIG. 10 is a side view schematically showing a moving portion 71P of the staple portion 71. [Figure 6] 7 is a side view of the central reference plate 73, the first reference plate 74, and the second reference plate 75 of the sheet binding unit 92, as viewed from the downstream side in the alignment direction. [Figure 7] 1 is a plan view of the first slide member 110 when viewed from the first reference plate 74 side, showing the state in which the first reference plate 74 is attached to the first slide member 110. [Figure 8]FIG. 1 is a plan view showing the internal structure of the first slide member 110. [Figure 9] FIG. 1 is a plan view showing the internal structure of the second slide member 120. [Figure 10] FIG. 10 is a plan view of the first slide member 110 and the second slide member 120 connected together, as viewed from the first reference plate 74 side, showing the state in which the slide spring 130 is contracted. [Figure 11] FIG. 10 is a plan view of the first slide member 110 and the second slide member 120 connected together, as viewed from the first reference plate 74 side, showing the state in which the slide spring 130 is extended. [Figure 12] 1 is a perspective view of the staple unit 71 as seen from the processing tray 521 side. [Figure 13] FIG. 10 is a plan view of the sheet binding unit 92 seen from above, showing a state in which the staple portion 71 is disposed at a reference position. [Figure 14] FIG. 10 is a plan view of the sheet binding unit 92 seen from above, illustrating the staple position of the staple portion 71 when performing diagonal binding on size A sheets S. [Figure 15] FIG. 10 is a plan view of the sheet binding unit 92 seen from above, illustrating the staple position of the staple portion 71 when performing diagonal binding on size B sheets S; [Figure 16] 16 is a partially enlarged view showing the inside of the first slide member 110 and the second slide member 120 of the first reference plate 74 in the state of FIG. 15. [Figure 17] 1 is a partially enlarged view showing the inside of the first slide member 110 and the second slide member 120 of the first reference plate 74 in a state where the staple unit 71 is moving from the reference position to the staple position when side-stitching size B sheets S. [Figure 18] FIG. 10 is a plan view of the sheet binding unit 92 seen from above, illustrating the standby position of the staple portion 71 when receiving the sheets S in the case of side-stitching the sheets S of size B. [Figure 19] 10 is a diagram showing a state in which the staple-side engaging portion 715 and the engaging protrusion 123b of the second engaging member 123 come into contact with each other while the staple portion 71 is returning from the center of the device to the reference position. [Figure 20] FIG. 20 is a diagram showing a state in which the second engaging member 123 starts to rotate due to the movement of the staple portion 71 from the state of FIG. 19. [Figure 21] 21 is a diagram showing a state in which the staple unit 71 has moved further toward the front side of the device from the state in FIG. 20 and the staple unit 71 and the first reference plate 74 have overlapped with each other. [Figure 22] 22 is a diagram showing a state in which the staple portion 71 is rotated obliquely from the state of FIG. 21. [Figure 23] FIG. 23 is a diagram showing a state in which the staple portion 71 has been rotated obliquely from the state shown in FIG. 22. DETAILED DESCRIPTION OF THE INVENTION

[0014] [1. Image formation system configuration]

[0023] The present invention will be described in detail below with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram showing the configuration of an image forming system including a sheet post-processing device 1 equipped with a sheet binding unit 92 according to an embodiment of the present invention, and an image forming device 200 to which the sheet post-processing device 1 is connected.

[0015] The image forming device 200 prints an image on a sheet (paper) based on image data input from outside via a network communication unit (not shown) or image data read by an image reading unit 201 arranged on top of the image forming device 200.

[0016] The sheet post-processing device 1 is detachably connected to the side of the image forming apparatus 200. The sheet post-processing device 1 performs post-processing such as punch hole formation and binding on sheets after images have been formed (printed) by the image forming apparatus 200. Note that the sheet post-processing device 1 is not limited to a device that performs post-processing on sheets automatically transported from the image forming apparatus 200, but may also be a device that transports sheets set by a user on a tray (not shown) to a position where the sheets can be post-processed and performs post-processing on the sheets.

[0017] [2. Configuration of sheet post-processing device] 2 is a side cross-sectional view schematically showing the configuration of a sheet post-processing device 1 including a sheet folding unit 100 of this embodiment. As shown in FIG. 2, the sheet post-processing device 1 includes a sheet entrance 2, a first sheet transport path 3, a first sheet discharge section 4, a second sheet transport path 5, a second sheet discharge section 6, a third sheet transport path 7, a third sheet discharge section 8, a post-processing section 9, and a post-processing control section (control section) 10.

[0018] The sheet entrance 2 is an opening provided on the side of the sheet post-processing device 1 facing the image forming device 200. A sheet transported from the image forming device 200 to the sheet post-processing device 1 passes through the sheet entrance 2 and is carried into the inside of the sheet post-processing device 1.

[0019] The first sheet transport path 3 extends substantially horizontally from the sheet entrance 2 to the first sheet discharge section 4 in a direction away from the image forming apparatus 200 (to the left in FIG. 2). The direction from the sheet entrance 2 toward the first sheet discharge section 4 is referred to as the sheet transport direction in the first sheet transport path 3. The sheet entrance 2 is located at the upstream end of the first sheet transport path 3 in the sheet transport direction. The first sheet transport path 3 has multiple transport roller pairs 3r, and transports a sheet carried into the sheet post-processing device 1 from the sheet entrance 2 toward the downstream side in the sheet transport direction.

[0020] The first sheet discharge section 4 is provided on the side of the sheet post-processing device 1 opposite to the side facing the image forming device 200. The first sheet discharge section 4 is disposed at the downstream end in the sheet conveying direction of the first sheet conveying path 3. The first sheet discharge section 4 has a first discharge opening 41, a first discharge roller pair 42, and a first discharge tray 43.

[0021] The first discharge outlet 41 is located at the downstream end of the first sheet transport path 3 in the sheet transport direction. The first discharge roller pair 42 is disposed at the first discharge outlet 41. The first discharge tray 43 is located downstream of the first discharge outlet 41 in the sheet transport direction. A sheet that has been transported along the first sheet transport path 3 and reached the first discharge outlet 41 is passed through the first discharge outlet 41 by the first discharge roller pair 42 and discharged onto the first discharge tray 43. The first discharge tray 43 is one of the final discharge locations for sheets that have been post-processed by the sheet post-processing device 1.

[0022] The second sheet transport path 5 branches off from a first branching portion (branching portion) 31 on the first sheet transport path 3 and extends horizontally and upward in a direction away from the image forming apparatus 200 (to the left in FIG. 2 ) to the second sheet discharge portion 6. The first branching portion 31 is located downstream of the punching portion 91 in the sheet transport direction of the first sheet transport path 3. The direction from the first branching portion 31 toward the second sheet discharge portion 6 is referred to as the sheet transport direction of the second sheet transport path 5. The first branching portion 31 is located at the upstream end of the second sheet transport path 5 in the sheet transport direction. The second sheet transport path 5 has multiple transport roller pairs 5r, and branches off a sheet transported along the first sheet transport path 3 at the first branching portion 31 to transport the sheet toward the second sheet discharge portion 6.

[0023] The first branching section 31 has a first switching guide 311. The first switching guide 311 rotates between a position where it guides a sheet conveyed on the first sheet conveying path 3 from the sheet entrance 2 side along the first sheet conveying path 3 to the first discharge outlet 41, and a position where it branches off from the first sheet conveying path 3 and guides the sheet to the second sheet conveying path 5. Furthermore, the first switching guide 311 rotates to a position where it guides a sheet that has been folded and passed through a second folding conveying path 106 (described later) to the second sheet conveying path 5. The first switching guide 311 is connected to a drive mechanism (not shown), and its operation is controlled by the post-processing control section 10.

[0024] The second sheet discharge section 6 is provided above the first sheet discharge section 4 on the side of the sheet post-processing device 1 opposite to the side facing the image forming device 200. The second sheet discharge section 6 is disposed at the downstream end of the second sheet transport path 5 in the sheet transport direction. The second sheet discharge section 6 has a second discharge opening 61, a second discharge roller pair 62, and a second discharge tray 63.

[0025] The second discharge outlet 61 is located at the downstream end of the second sheet transport path 5 in the sheet transport direction. The second discharge roller pair 62 is disposed at the second discharge outlet 61. The second discharge tray 63 is located downstream of the second discharge outlet 61 in the sheet transport direction. A sheet that has been transported along the second sheet transport path 5 and reached the second discharge outlet 61 is passed through the second discharge outlet 61 by the second discharge roller pair 62 and discharged onto the second discharge tray 63. The second discharge tray 63 is one of the final discharge locations for sheets that have been post-processed by the sheet post-processing device 1. In addition, sheets that are not post-processed and small-sized sheets are also discharged to the second discharge tray 63.

[0026] The third sheet transport path 7 branches off from the second branching portion 32 on the first sheet transport path 3 and extends downward to the third sheet discharge portion 8. The direction from the second branching portion 32 toward the third sheet discharge portion 8 is referred to as the sheet transport direction of the third sheet transport path 7. The second branching portion 32 is located downstream of the first branching portion 31 with respect to the sheet transport direction of the first sheet transport path 3, and is located at the upstream end of the third sheet transport path 7 in the sheet transport direction. The third sheet transport path 7 has multiple transport roller pairs 7r, and causes the sheet transported along the first sheet transport path 3 to branch off at the second branching portion 32 and be transported toward the third sheet discharge portion 8.

[0027] The second branching section 32 has a second switching guide 321. The second switching guide 321 rotates between a position where it guides a sheet conveyed on the first sheet conveying path 3 from the sheet entrance 2 side along the first sheet conveying path 3 to the first discharge outlet 41, and a position where it guides a sheet conveyed on the first sheet conveying path 3 from the sheet entrance 2 side, passes through the second branching section 32, and is switched back to the third sheet conveying path 7. The second switching guide 321 is connected to a drive mechanism (not shown), and its operation is controlled by the post-processing control section 10.

[0028] The third sheet discharge section 8 is provided below the first sheet discharge section 4 (near the lower end of the sheet post-processing device 1) on the side of the sheet post-processing device 1 opposite to the side facing the image forming device 200. The third sheet discharge section 8 has a third discharge opening 81, a third discharge roller pair 82, and a third discharge tray 83.

[0029] The third discharge outlet 81 is located at the downstream end of the third sheet transport path 7 in the sheet transport direction. The third discharge roller pair 82 is arranged at the third discharge outlet 81. The third discharge tray 83 is located downstream of the third discharge outlet 81 in the sheet transport direction. A sheet that has been transported along the third sheet transport path 7 and reached the third discharge outlet 81 is passed through the third discharge outlet 81 by the third discharge roller pair 82 and discharged onto the third discharge tray 83. The third discharge tray 83 is one of the final discharge locations for sheets that have been post-processed by the sheet post-processing device 1.

[0030] The post-processing section 9 performs predetermined post-processing on sheets on which images have been formed by the image forming device 200 and which have been transported into the sheet post-processing device 1. The post-processing section 9 includes a punching section 91, a sheet binding unit 92, a sheet folding unit 100, and a binding section 94.

[0031] The punching unit 91 is disposed on the first sheet transport path 3, immediately downstream of the sheet entrance 2. The punching unit 91 performs a punching process on the sheet transported on the first sheet transport path 3, to form punch holes.

[0032] The sheet binding unit 92 is disposed immediately upstream of the first sheet discharge section 4 in the sheet conveying direction of the first sheet conveying path 3. The sheet binding unit 92 staples (binds) a sheet bundle formed by stacking a plurality of sheets, and binds the sheet bundle. The detailed configuration of the sheet binding unit 92 will be described later.

[0033] The sheet folding unit 100 is disposed downstream of the punching section 91 and upstream of the sheet binding unit 92 in the sheet conveying direction of the first sheet conveying path 3. The sheet folding unit 100 folds a single sheet to form a crease. The sheet folding unit 100 can fold a single sheet in various ways, such as in half, Z-fold, outward three-fold, and inward three-fold.

[0034] The binding section 94 is disposed immediately upstream of the third sheet discharge section 8 in the sheet conveying direction of the third sheet conveying path 7. The binding section 94 has a center folding section 941 and a saddle stitching section 942. The binding section 94 performs center folding and saddle stitching on a sheet bundle formed by stacking a plurality of sheets, in which the sheets are folded and stitched at approximately the center in the sheet conveying direction, to form a booklet.

[0035] The post-processing control unit 10 includes a CPU, a memory unit, and other electronic circuits and electronic components (none of which are shown). The post-processing control unit 10 is communicably connected to the main body control unit of the image forming apparatus 200 (see FIG. 1). The post-processing control unit 10 receives commands from the main body control unit and, using the CPU, controls the operation of each component provided in the sheet post-processing device 1 based on control programs and data stored in the memory unit to perform processing related to the functions of the sheet post-processing device 1. The first sheet transport path 3, the first sheet discharge unit 4, the second sheet transport path 5, the second sheet discharge unit 6, the third sheet transport path 7, the third sheet discharge unit 8, and the post-processing unit 9 each receive individual commands from the post-processing control unit 10 and perform post-processing on sheets in cooperation with each other. The functions of the post-processing control unit (control unit) 10 may also be performed by the main body control unit of the image forming apparatus 200.

[0036] [3. Sheet binding unit configuration] Next, the configuration of the sheet binding unit 92 will be described with reference to Figures 3 and 4. Figure 3 is a perspective view of the sheet binding unit 92 of this embodiment. Figure 4 is a side view of the sheet binding unit 92.

[0037] As shown in FIG. 3, the sheet binding unit 92 includes a processing tray 521, a staple section 71, a central reference plate 73 (fixed reference plate), a first reference plate 74 (movable reference plate), and a second reference plate 75 (movable reference plate).

[0038] The processing tray 521 is a rectangular tray extending in the sheet width direction (arrow AA′ direction) and the carry-in direction. A plurality of sheets S (sheet stack) to be stapled are stacked on the processing tray 521. At this time, the sheets S are carried into the processing tray 521 along an alignment direction (opposite the carry-in direction) toward the lower right direction (arrow B direction) in FIG. 4. The stapled sheet stack is finally sent out in the direction opposite to the alignment direction (upper left direction in FIG. 4) by the first discharge roller pair 42 (see FIG. 2) and discharged onto the first discharge tray 43 (see FIG. 2). A lower roller 421 constituting the first discharge roller pair 42 is supported downstream of the processing tray 521 in the carry-in direction (lower left side in FIG. 3).

[0039] The processing tray 521 includes a tray center portion 522 and a width restriction member 523. The tray center portion 522 is disposed in the center in the sheet width direction on the upper surface of the processing tray 521. The tray center portion 522 is a thin plate-like member that is fixed onto the processing tray 521 with a slight height.

[0040] A pair of width restricting members 523 are arranged on either side of the tray center portion 522 in the sheet width direction. The width restricting members 523 restrict the position of the sheet S in the sheet width direction when it is carried into the processing tray 521. The width restricting member 523 is made of a thin plate-like member, similar to the tray center portion 522, and has side walls that stand upward at the ends in the sheet width direction. The processing tray 521 is formed with a guide groove 524 extending along the sheet width direction. The width restricting member 523 is reciprocally movable in the sheet width direction along the guide groove 524 via a drive mechanism (not shown) such as a rack and pinion gear. In this embodiment, the width restricting member 523 is reciprocated by the drive mechanism every time a sheet is carried into the processing tray 521. As a result, the sheets S stacked on the processing tray 521 are aligned in the sheet width direction.

[0041] The stapler 71 is disposed opposite the edge of the processing tray 521 on the downstream side (the far right side in FIG. 3, the lower right side in FIG. 4) in the alignment direction (the direction of arrow B) of the sheets S. The stapler 71 is movable along the edge of the processing tray 521 in the sheet width direction (the direction of arrow AA') perpendicular to the alignment direction, and staples the stack of sheets S.

[0042] As shown in FIG. 4, the staple portion 71 includes a staple body portion 711 and a staple movable portion 712. The staple body portion 711 is the main body of the staple portion 71 and houses a plurality of staples (not shown) therein. The staple movable portion 712 is movable up and down and drives the staples into the sheet S. A recess 713 is formed between the staple body portion 711 and the staple movable portion 712, into which the edge of the sheet S enters.

[0043] The central reference plate 73 is fixed to the processing tray 521 so as to face the end of the tray center 522 on the downstream side in the alignment direction (upper right side in FIG. 3, lower side in FIG. 5). The central reference plate 73 has a generally U-shape in a cross section perpendicular to the sheet width direction, with the upstream side in the alignment direction (upper left side in FIG. 4) being open. The central reference plate 73 abuts against the edge of the sheet S being carried into the processing tray 521, and aligns the sheet S in the carry-in direction.

[0044] The first reference plate 74 and the second reference plate 75 are arranged on the processing tray 521 at a distance in the sheet width direction so as to sandwich the central reference plate 73 in the sheet width direction. The first reference plate 74 and the second reference plate 75, together with the central reference plate 73, abut against the edge of the sheet S being carried into the processing tray 521 and align the sheet S in the carry-in direction. The first reference plate 74 and the second reference plate 75 are each supported by a guide mechanism (not shown) so as to be slidable in the sheet width direction. The first reference plate 74 and the second reference plate 75 also have a substantially U-shape similar to the central reference plate 73. The first reference plate 74 and the second reference plate 75 can stably align both ends of the sheet S in the sheet width direction in the carry-in direction. Note that, when viewed from the central reference plate 73, the first reference plate 74 side is the front side of the device, and the second reference plate 75 side is the rear side of the device. Therefore, in the following description, the arrow A direction in the sheet width direction will be referred to as the rear side of the device, and the arrow A' direction will be referred to as the front side of the device.

[0045] 5 is a side view schematically showing the moving portion 71P of the staple portion 71 of the sheet binding unit 92. The moving portion 71P moves the staple portion 71 in the sheet width direction. The moving portion 71P includes a support frame 72, a support portion 71J, a motor M, and a shaft 72S.

[0046] The support frame 72 is a rectangular sheet metal member extending in the sheet width direction and the carry-in direction, and is disposed adjacent to the processing tray 521 in the sheet post-processing device 1. The support frame 72 includes a first guide groove 721 for the stapler unit 71 to move in, and a second guide groove 722 for the first reference plate 74 and the second reference plate 75 to move in (see FIG. 13 for both). The first guide groove 721 and the second guide groove 722 are elongated openings extending along the sheet width direction of the support frame 72.

[0047] The support portion 71J supports the staple portion 71. The support portion 71J has a pair of pivotal support portions (not shown). The pair of pivotal support portions is inserted into the first guide groove 721 and the second guide groove 722, respectively. The staple portion 71 and the support portion 71J are movable together in the sheet width direction along the first guide groove 721 and the second guide groove 722.

[0048] The motor M generates a driving force that moves the staple portion 71. The motor M generates a rotational driving force in the forward and reverse directions. The shaft 72S is connected to the motor M and is rotated by the driving force of the motor M. A male screw (not shown) is formed on the circumferential surface of the shaft 72S. A shaft hole (not shown) is formed in the lower end of the support portion 71J, and the shaft 72S is inserted into the shaft hole. A female screw (not shown) is formed on the inner circumferential surface of the shaft hole of the support portion 71J. As a result, when the shaft 72S is rotated by the motor M, the staple portion 71 moves in the sheet width direction.

[0049] As described above, when diagonally binding the end of a stack of sheets S, depending on the size of the sheets S to be diagonally bound, the position at which the staple unit 71 is rotated diagonally may overlap with the first reference plate 74 or the second reference plate 75. As a result, when the staple unit 71 rotates, it may interfere with the first reference plate 74 or the second reference plate 75, preventing the staple unit 71 from rotating and causing damage to the first reference plate 74 or the second reference plate 75.

[0050] In order to solve the above problem, in this embodiment, the first reference plate 74 and the second reference plate 75 are moved in the sheet width direction in conjunction with the movement of the staple portion 71. Next, the movement mechanism of the first reference plate 74 and the second reference plate 75 will be described in more detail.

[0051] [4. First and second reference plate movement mechanisms] 6 is a side view of the central reference plate 73, the first reference plate 74, and the second reference plate 75 of the sheet binding unit 92, as seen from the downstream side in the alignment direction (the far right side in FIG. 3). As shown in FIG. 6, the central reference plate 73, the first reference plate 74, and the second reference plate 75 are supported by a support shaft 100 provided on the back side of the processing tray 521.

[0052] The central reference plate 73 is swingable about a support shaft 100, and its movement in the seat width direction (arrow AA' direction) is restricted. The first reference plate 74 and the second reference plate 75 are supported by the support shaft 100 via a first slide member 110 and a second slide member 120. The first reference plate 74 and the second reference plate 75 are movable in the seat width direction.

[0053] Fig. 7 is a plan view of the first slide member 110 with the first reference plate 74 attached, viewed from the first reference plate 74 side. Fig. 8 is a plan view showing the internal structure of the first slide member 110. Note that Figs. 7 to 11 show the first slide member 110 and the second slide member 120 to which the first reference plate 74 is attached, but the first slide member 110 and the second slide member 120 to which the second reference plate 75 is attached have exactly the same configuration except that they are bilaterally symmetrical.

[0054] The first slide member 110 has a main body portion 111, a first engagement member 113, and a compression spring 115. A fixing piece 74a formed integrally with the first reference plate 74 is fixed to the main body portion 111. One end edge (the upper end in FIG. 8) of the main body portion 111 is formed with guide portions 117a and 117b into which the support shaft 100 is slidably inserted. A spring fixing portion 118 is formed on the guide portion 117b.

[0055] The first engaging member 113 is supported by the main body 111 so as to be able to swing about a swing shaft 113a. The compression spring 115 is disposed between the main body 111 and the first engaging member 113. The first engaging member 113 is biased by the biasing force of the compression spring 115 in a direction in which it protrudes from the main body 111 (counterclockwise in FIG. 8).

[0056] 9 is a plan view showing the internal structure of second slide member 120. Second slide member 120 has a main body portion 121, a second engagement member 123, and a tension spring 125. Main body portion 121 is connected to main body portion 111 of first slide member 110 from the side opposite to first reference plate 74 (the back side in FIG. 8). One end edge (the upper end in FIG. 9) of main body portion 121 is formed with guide portions 127a and 127b into which support shaft 100 is slidably inserted. Guide portion 127a is formed with a spring fixing portion 128 and a restricting protrusion 129.

[0057] The second engaging member 123 is a cylindrical member rotatably supported on the main body 121 around a rotation axis 123a. The second engaging member 123 has an engaging protrusion 123b and a hook portion 123c. The engaging protrusion 123b protrudes in the radial direction of the second engaging member 123. The hook portion 123c protrudes in the radial direction of the second engaging member 123 at a position different in the circumferential direction from the engaging protrusion 123b.

[0058] The tension spring 125 is connected to the spring hook portion 121a of the main body portion 121 and the hook portion 123c of the second engagement member 123. The second engagement member 123 is biased by the biasing force of the tension spring 125 in a direction in which the engagement protrusion 123b protrudes from the main body portion 121 (counterclockwise direction in FIG. 9).

[0059] A torsion spring 123d is disposed inside second engaging member 123. Second engaging member 123 is divided into a portion including engaging protrusion 123b and a portion including hook portion 123c in the direction of rotation axis 123a. Torsion spring 123d biases the portion including engaging protrusion 123b in the clockwise direction.

[0060] 10 and 11 are plan views of the first slide member 110 and the second slide member 120 connected together, viewed from the first reference plate 74 side. The second slide member 120 is connected to the first slide member 110 so as to be slidable in the axial direction of the support shaft 100 (left and right directions in FIGS. 10 and 11). In other words, the first slide member 110 and the second slide member 120 are connected together so that the distance between them in the axial direction of the support shaft 100 can change.

[0061] A slide spring 130 is disposed between the first slide member 110 and the second slide member 120. The slide spring 130 is a tension spring, and both ends of the slide spring 130 are fixed to a spring fixing portion 118 of the first slide member 110 and a spring fixing portion 128 of the second slide member 120, respectively.

[0062] Figure 10 shows the normal state in which the slide spring 130 is contracted. In the state of Figure 10, the biasing force of the slide spring 130 causes the guide portion 117b of the first slide member 110 and the guide portion 127a of the second slide member 120 to abut against each other. In other words, in the state of Figure 10, the first slide member 110 and the second slide member 120 are at their furthest apart.

[0063] Fig. 11 shows a state in which slide spring 130 is extended. In the state shown in Fig. 11, guide portion 117b and guide portion 127a are separated from each other against the biasing force of slide spring 130, and guide portion 117a and guide portion 127a, and guide portion 117b and guide portion 127b are in contact with each other, respectively.

[0064] 12 is a perspective view of the staple portion 71 as viewed from the processing tray 521 side. The staple portion 71 is provided with staple-side engaging portions 715 on the side surfaces of the staple main body 711 that face the first slide member 110 and the second slide member 120. The staple-side engaging portions 715 come into contact with the first engaging member 113 and the second engaging member 123 when the staple portion 71 moves in the sheet width direction.

[0065] As will be described later, when the staple portion 71 moves from the center of the sheet width direction (center of the device) to the outside (front side of the device), an external force is applied to the first reference plate 74 by the staple portion 71, and as shown in Figure 11, the slide spring 130 extends against the biasing force, and the first slide member 110 and the second slide member 120 move in a direction approaching each other.

[0066] [5. Movement of the first and second reference plates with movement of the staple section] Next, we will explain how the first reference plate 74 and the second reference plate 75 move in accordance with the movement of the staple portion 71. Figure 13 is a plan view of the sheet binding unit 92 seen from above, illustrating a state in which the staple portion 71 is disposed at the reference position.

[0067] 13, the staple unit 71 is disposed at a reference position (home position, in this embodiment, at the front side of the device) in an inclined state at a predetermined angle with respect to the sheet width direction (direction of arrow AA′) in which the central reference plate 73, the first reference plate 74, and the second reference plate 75 are aligned. The first reference plate 74 and the second reference plate 75 are disposed at initial positions in which the guide portions 127b abut against the central regulating portion 723 (see FIG. 16).

[0068] When stapling a stack of sheets S, before the sheets S are transported onto the processing tray 521, the staple unit 71 is moved from a reference position (home position) to a predetermined staple position (position where staples are driven into the sheets S).

[0069] For example, in the case of diagonal binding, in which staples are driven diagonally into the corners of the sheets S to bind them, the motor M, which is the drive source for moving the staple unit 71, is rotated to rotate the shaft 72S by a predetermined amount via a speed reduction mechanism and a drive transmission gear (neither of which are shown). As a result, the staple unit 71 is moved to the stapling position in a diagonal state.

[0070] 14 is a diagram showing the standby position of the staple unit 71 when diagonally binding sheets S of size A. When diagonally binding sheets S of size A (for example, A4 portrait size) whose width size is larger than the distance between the first reference plate 74 and the second reference plate 75 arranged at the initial position, as shown in FIG. 14, the staple unit 71 moves in the direction of arrow A from the reference position and stops at the staple position without passing through the first reference plate 74.

[0071] In this state, size A sheets S carried in from image forming apparatus 100 are aligned and stacked one by one on processing tray 521, and staples are driven obliquely into the corners of the front side of the device (in the direction of arrow A') of the stack of sheets S to bind them. After the oblique binding is completed, motor M is rotated in the reverse direction to return staple unit 71 to the reference position (see FIG. 13).

[0072] FIG. 15 is a diagram showing the standby position of the staple unit 71 when performing diagonal binding on size B sheets S. FIG. 16 is a partially enlarged view showing the inside of the first slide member 110 and the second slide member 120 of the first reference plate 74 in the state shown in FIG. 15. As shown in FIG. 16, a biasing spring 131 is connected between the second slide member 120 and the support frame 72. The biasing spring 131 is a tension spring, and biases the second slide member 120 toward the center of the device (the direction of arrow A). The biasing force of the biasing spring 131 causes the guide portion 127b of the second slide member 120 to abut against a central regulating portion 723 formed on the support frame 72.

[0073] When the widthwise size of the sheet S is size B (for example, B5 portrait size) that is smaller than the distance between the first reference plate 74 and the second reference plate 75 arranged in the initial position, as the inclined staple portion 71 moves from the front side of the device to the center of the device, as shown in Figure 16, the staple side engagement portion 715 provided on the staple portion 71 comes into contact with the first engagement member 113 of the first slide member 110 that is connected to the first reference plate 74 arranged in the initial position.

[0074] As the staple portion 71 moves, the staple-side engaging portion 715 presses the first engaging member 113, causing the first slide member 110 to move in a direction overlapping the second slide member 120 while extending the slide spring 130 (see FIG. 10). That is, the first slide member 110 moves from the state shown in FIG. 10 to the state shown in FIG. 11. As a result, the first reference plate 74 also moves from its initial position toward the center of the device (in the direction of arrow A). The staple portion 71 stops at a predetermined staple position while moving the first reference plate 74.

[0075] In this state, size B sheets S carried in from image forming apparatus 100 are aligned and stacked one by one on processing tray 521, and staples are driven diagonally into the corners of the stack of sheets S on the front side of the device (in the direction of arrow A') to bind the sheets. After the diagonal binding is completed, motor M is rotated in the reverse direction to return staple unit 71 to the reference position (see FIG. 13). Furthermore, because staple-side engagement portion 715 moves away from first engagement member 113, first slide member 110 moves toward the front side of the device (in the direction of arrow A') due to the restoring force of slide spring 130 and returns to its initial position.

[0076] Next, we will explain the case where the size of the sheets S is size B, which is smaller than the distance between the first reference plate 74 and the second reference plate 75, and side binding is performed by driving staples parallel to the edge along the width direction (front-rear direction of the device) of the sheets S. Side binding includes one-point binding, in which the sheets S are bound at one corner of the edge, and two-point binding, in which the sheets S are bound at two points on the edge.

[0077] Fig. 17 is a partially enlarged view showing the inside of the first slide member 110 and the second slide member 120 of the first reference plate 74 when the staple unit 71 is moving from the reference position to the staple position when side-stitching size B sheets S. Fig. 18 is a view showing the standby position of the staple unit 71 when side-stitching size B sheets S.

[0078] 16, while the staple unit 71, which is arranged at the reference position in an inclined state, moves from the front side of the device to the center of the device, the staple-side engaging portion 715 provided on the staple unit 71 comes into contact with the first engaging member 113 of the first slide member 110 connected to the first reference plate 74 arranged at the initial position. Furthermore, the staple-side engaging portion 715 presses the first engaging member 113 toward the center of the device, thereby moving the first reference plate 74 toward the center of the device (in the direction of arrow A) as the staple unit 71 moves.

[0079] When the staple portion 71 moves to a predetermined position, the angle of the staple portion 71 changes to a parallel state in the direction of movement in accordance with the shapes of the first guide groove 721 and the second guide groove 722 that guide the movement of the staple portion 71. As a result, the engagement between the staple-side engaging portion 715 and the first engaging member 113 is released, and the first reference plate 74 returns to its initial position by the restoring force of the slide spring 130.

[0080] Thereafter, when the staple portion 71 further moves toward the center of the device, the staple-side engaging portion 715 comes into contact with the engaging protrusion 123b of the second engaging member 123 provided on the second slide member 120, as shown in FIG. 17. Here, the portion of the second engaging member 123 including the engaging protrusion 123b is biased by the torsion spring 123d (see FIG. 9) with a biasing force that does not interfere with the movement of the staple portion 71 and is sufficient to return the engaging protrusion 123b to its original position. Therefore, the staple portion 71 moves toward the center of the device while rotating the portion including the engaging protrusion 123b counterclockwise. In other words, the contact between the second engaging member 123 and the staple-side engaging portion 715 does not affect the movement of the staple portion 71 and the first reference plate 74.

[0081] 18, after the parallel stapling unit 71 is stopped at a predetermined standby position, size B sheets S carried in from the image forming apparatus 100 are aligned and stacked one by one on the processing tray 521, and the stapling unit 71 is moved to a predetermined position in the width direction of the stack of sheets S and staples are driven in parallel at one position to bind the sheets. After the side stitching is completed, the motor M is rotated in the reverse direction to return the stapling unit 71 to the reference position (see FIG. 13).

[0082] 19 is a diagram showing a state in which the staple-side engaging portion 715 comes into contact with the engaging protrusion 123b of the second engaging member 123 as the staple unit 71 returns from the center of the device to the reference position. When the staple unit 71 is moved to a predetermined position after receiving the sheet S, the staple-side engaging portion 715 engages with the engaging protrusion 123b of the second engaging member 123 as the parallel staple unit 71 moves toward the front of the device (in the direction of arrow A'). As a result, a pressing force acts on the second engaging member 123 in the clockwise direction. Meanwhile, the second engaging member 123 is biased in the counterclockwise direction by the tension spring 125.

[0083] The biasing force of tension spring 125 (the force restricting clockwise rotation of second engagement member 123) is greater than the biasing force of biasing spring 131 that biases second slide member 120 from the front side of the device toward the center of the device. Therefore, movement of staple portion 71 causes second slide member 120 to move from the initial position toward the front side of the device while stretching biasing spring 131. As a result, first slide member 110 and first reference plate 74 can be moved toward the front side of the device together with second slide member 120.

[0084] 20 is a diagram showing a state in which the second engagement member 123 has begun to rotate due to movement of the staple portion 71 from the state shown in FIG. 19. When the first reference plate 74 moves a predetermined amount toward the front of the device, the restricting protrusion 129 formed on the guide portion 127a of the second slide member 120 comes into contact with the end portion restricting portion 724 formed on the support frame 72. As a result, the staple portion 71 can move toward the front of the device, but the movement of the second slide member 120 toward the front of the device is restricted by the end portion restricting portion 724.

[0085] 20, second engagement member 123 rotates clockwise against the rotation restricting force of tension spring 125, and engagement protrusion 123b disengages from staple-side engagement portion 715. As a result, second engagement member 123 moves toward the center of the device (direction of arrow A) due to the biasing force (restoring force) of biasing spring 131, and guide portion 127b of second slide member 120 abuts against central restricting portion 723, returning first reference plate 74 to its initial position.

[0086] Figure 21 is a diagram showing a state in which the staple unit 71 has moved toward the front of the device from the state in Figure 20 and the staple unit 71 has overlapped with the first reference plate 74. When the staple unit 71 moves further toward the front of the device (in the direction of arrow A') from the state in Figure 20, the staple unit 71 overlaps with the first reference plate 74. At this time, the staple unit 71 begins to rotate from a parallel state to an inclined state in accordance with the shapes of the first guide groove 721 and the second guide groove 722.

[0087] When the staple portion 71 is rotated by a predetermined angle from the state shown in FIG. 21, the staple side engaging portion 715 provided on the staple portion 71 comes into contact with the first engaging member 113 of the first slide member 110 as shown in FIG.

[0088] When the staple portion 71 rotates further from the state shown in Fig. 22, the staple-side engaging portion 715 pushes the first engaging member 113 as shown in Fig. 23. This causes the first slide member 110 to move toward the center of the device (the direction of arrow A) while extending the slide spring 130, and the first reference plate 74 moves together with the first slide member 110 in the direction opposite to the moving direction of the staple portion 71 (the direction of arrow A).

[0089] Thereafter, the staple portion 71 moves toward the front side of the device (in the direction of arrow A'), causing the staple-side engaging portion 715 to separate from the first engaging member 113, and the staple portion 71 returns to the reference position in an inclined state. The first slide member 110 moves toward the front side of the device (in the direction of arrow A') due to the biasing force (restoring force) of the slide spring 130, and the first reference plate 74 returns to its initial position.

[0090] According to the above configuration, the first reference plate 74 can be disposed at a position required for performing diagonal binding, one-point binding, and two-point binding, and interference between the staple portion 71 and the first reference plate 74 can be avoided. Therefore, the sheets S can be stably stapled without compromising the alignment of the sheets S.

[0091] Furthermore, when the staple portion 71 rotates, there is no risk that the first reference plate 74 will interfere with the staple portion 71 or hinder the rotation of the staple portion 71, and it is also possible to prevent deformation or damage to the first reference plate 74. Furthermore, since no drive source is required to move the first reference plate 74, it is possible to provide an inexpensive, highly consistent sheet binding unit 92.

[0092] Although the embodiment of the present invention has been described above, the scope of the present invention is not limited thereto, and various modifications can be made without departing from the spirit of the invention. For example, in the above embodiment, the movement of the first reference plate 74 accompanying the movement of the staple unit 71 when the reference position of the staple unit 71 is set to the front side of the device has been described, but the movement of the second reference plate 75 accompanying the movement of the staple unit 71 when the reference position of the staple unit 71 is set to the rear side of the device can be similarly described.

[0093] In the above embodiment, the moving unit 71P that moves the staple portion 71 is configured to reciprocate the staple portion 71 by rotating the shaft 72S, but the present invention is not limited to this. Instead of the shaft 72S, the moving unit 71P may be configured to reciprocate the staple portion 71 by a wire or belt mechanism hung over a pulley.

[0094] In the above embodiment, the reference plates for aligning the sheet S in the carry-in direction are the central reference plate 73 and the pair of first and second reference plates 74 and 75 that are arranged at a predetermined interval in the sheet width direction across the central reference plate 73. However, the reference plates may be configured to include only one of the first and second reference plates 74 and 75. Alternatively, the reference plates may include three or more movable reference plates. [Industrial Applicability]

[0095] The present invention can be used in a sheet binding device that binds a plurality of sheets, and a sheet post-processing device that includes a sheet binding device. [Explanation of symbols]

[0096] 1 Sheet post-processing device 2 Sheet entrance 10 Post-processing control unit (control unit) 521 Processing Tray 71 Staple section 715 Staple side engagement part 71P moving part 72 Support Frame 721 First guide groove 722 Second guide groove 723 Central Regulation Department 724 End restriction part 73 Central reference plate (fixed reference plate) 74 1st reference plate (movable reference plate) 75 Second reference plate (movable reference plate) 92 Sheet binding unit (sheet binding device) 100 spindle 110 first slide member 113 First engagement member (movable engagement member) 120 second slide member 123 Second engagement member (movable engagement member) 130 Slide spring 131 bias spring S seat

Claims

1. a processing tray on which a plurality of sheets carried in along a predetermined carrying-in direction are stacked; a movable reference plate that is disposed at a predetermined initial position capable of abutting against an edge of the sheet carried onto the processing tray on a downstream side in an alignment direction that is the opposite direction to the carry-in direction, thereby aligning the sheet, and that is movable from the initial position in a sheet width direction that is perpendicular to the carry-in direction; a staple unit that is disposed opposite the edge of the sheets and performs a staple process of stapling the sheets stacked on the processing tray at predetermined positions with staples; a moving unit that moves the staple unit along the edge of the sheet to a reference position that is on the outer side of the initial position in the sheet width direction and to at least one staple position where the stapling process is performed on the inner side of the initial position in the sheet width direction; In a sheet binding device comprising: the moving unit is capable of changing the posture of the staple unit between an inclined state in which the staple unit is inclined obliquely with respect to the edge of the sheet and a parallel state in which the staple unit is parallel to the edge of the sheet, a slide member to which the movable reference plate is attached and which is reciprocally movable along the seat width direction; a slide spring that biases the slide member in a direction in which the movable reference plate approaches the initial position; Equipped with the slide member has a movable engaging member that comes into contact with the staple-side engaging portion of the staple portion when the staple portion moves between the reference position and the staple position, When the movable reference plate is disposed at the initial position and the staple portion is moved from the reference position to the staple position in the inclined state, the staple-side engaging portion presses the movable engaging member, whereby the movable reference plate moves inward in the sheet width direction together with the slide member against the biasing force of the slide spring, When the staple portion changes its posture from the inclined state to the parallel state before reaching the staple position, the staple-side engaging portion separates from the movable engaging member, and the movable reference plate moves outward in the sheet width direction together with the slide member due to the biasing force of the slide spring and returns to the initial position, When the staple portion changes its posture from the parallel state to the inclined state during movement from the staple position to the reference position, the staple-side engaging portion presses the movable engaging member, whereby the movable reference plate moves from the initial position toward the inside in the sheet width direction together with the slide member against the biasing force of the slide spring, A sheet binding device characterized in that when the staple portion moves to the reference position, the staple side engagement portion moves away from the movable engagement member, and the movable reference plate moves outward in the sheet width direction together with the slide member due to the spring force of the slide spring and returns to the initial position.

2. The slide member is a first slide member to which the movable reference plate is fixed; a second slide member connected to the first slide member so as to be movable in the seat width direction; and the slide spring biases the first slide member and the second slide member in a direction in which they move apart in the seat width direction, the movable engaging member is provided on the first slide member and includes a first engaging member that is swingable in a direction perpendicular to the moving direction of the staple portion, while the staple portion is moving from the reference position to the staple position in the inclined state, the staple-side engaging portion presses the first engaging member in the moving direction, whereby the movable reference plate moves inward in the sheet width direction together with the first slide member and the second slide member, and when the staple portion is changed in posture from the inclined state to the parallel state, the staple-side engaging portion moves away from the first engaging member, whereby the movable reference plate returns to the initial position by the biasing force of the slide spring, The sheet binding device of claim 1, characterized in that when the staple portion changes its position from the parallel state to the inclined state while moving from the staple position to the reference position, the staple side engagement portion presses the first engagement member in a direction perpendicular to the movement direction to swing it, thereby allowing the staple portion to change its position to the inclined state and moving the movable reference plate inward in the sheet width direction together with the first slide member.

3. a biasing spring that biases the second slide member toward the center in the seat width direction, the movable engaging member is provided on the second slide member and includes a second engaging member that is rotatable along the moving direction of the staple portion when a rotational load equal to or greater than a predetermined value is applied thereto; when the second slide member moves to a predetermined restriction position while the staple portion is moving from the reference position to the staple position, and the staple-side engaging portion engages with the second engaging member with the movable reference plate disposed at the initial position, the second engaging member rotates to allow the staple portion to move to the staple position without moving the movable reference plate from the initial position, When the staple side engaging portion engages with the second engaging member while the movable reference plate is disposed at the initial position during the movement of the staple portion from the staple position to the reference position, the second engaging member is pressed without being rotated to move the first slide member and the second slide member outward in the sheet width direction, A sheet binding device as described in claim 2, characterized in that when the first slide member and the second slide member move to a predetermined regulating position, the second engagement member rotates to release the engagement between the staple side engagement portion and the second engagement member, and the movable reference plate returns to the initial position together with the first slide member and the second slide member due to the biasing force of the biasing spring.

4. a pair of movable reference plates including a first reference plate and a second reference plate arranged at an interval in the sheet width direction; a fixed reference plate that is disposed between the first reference plate and the second reference plate, the fixed reference plate being restricted in its movement in the seat width direction and being swingable in a direction perpendicular to the seat width direction; and 2. The sheet binding device according to claim 1, wherein the reference position of the staple portion is located outside the initial position of the first reference plate or the second reference plate in the sheet width direction.

5. The moving unit is a motor that reciprocates the staple unit in the sheet width direction; a support frame having a guide groove formed therein, the guide groove being a path for movement of the staple portion; and 2. The sheet binding device according to claim 1, wherein the staple portion changes its position between the inclined state and the parallel state in accordance with the shape of the guide groove.

6. The stapling process includes: diagonal binding in which the staples are driven diagonally into the corners of the sheets to bind them; a side binding method in which the staples are driven parallel to the edge of the sheets to bind them together; Including, The sheet binding device according to claim 1, wherein the staple portion is disposed at the staple position in the inclined state when performing the diagonal binding, and is disposed at the staple position in the parallel state when performing the flat binding.

7. A sheet post-processing device comprising the sheet binding device according to any one of claims 1 to 6.

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