Sheet processing device and image forming system

Abstract

This provides a novel configuration for clamping a sheet bundle using a pair of clamping units. [Solution] The moving mechanism moves the first clamp 142 between the clamped position and the released position. The moving mechanism includes an upper stay 160, a spacer 801, a spring 802, and a drive transmission unit. The upper stay 160 has a first surface 161a, a second surface 162a, and a third surface 163a, and the first clamp 142 is fixed to it. The spacer 801 is located between the second surface 162a and the third surface 163a and is movable relative to the upper stay 160 in a first direction and a second direction. The spring 802 is provided between the first surface 161a and the spacer 801. The drive transmission unit moves the spacer 801 in the first direction, compressing the spring 802 between the spacer 801 and the first surface 161a, and moving the first clamp 142 to the clamped position.

Description

Technical Field

[0001] The present invention relates to a sheet processing apparatus that performs a corner-back process on a sheet, and an image forming system including the sheet processing apparatus.

Background Art

[0002] As a sheet processing apparatus, there has been proposed a configuration in which, while a sheet bundle that has been center-folded is clamped by a pair of clamp units, the back portion of the sheet bundle protruding beyond the clamp is pressed by a roller to perform a process of forming a corner on the back of the sheet bundle (hereinafter, referred to as a corner-back process) (Patent Document 1).

[0003] Further, in the configuration of Patent Document 1, in order to sandwich the sheet bundle by a pair of clamp units, a spring is disposed between the clamp and the member that moves the clamps, and a biasing force corresponding to the amount of contraction of the spring is applied to the sheet bundle.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention provides a novel configuration for sandwiching a sheet bundle by a pair of clamp units.

Means for Solving the Problems

[0006] One aspect of the present invention includes a conveying unit for conveying a sheet bundle that has been folded in the middle so that the spine of the sheet bundle is located downstream in the conveying direction from the fore-edge, or a sheet bundle that has been saddle-stitched and folded; a pair of clamping units including a first clamp and a second clamp that clamps the sheet bundle conveyed by the conveying unit together with the first clamp; a pressing unit that, when the sheet bundle is clamped by the pair of clamping units, presses the spine of the sheet bundle that protrudes downstream in the conveying direction from the pair of clamping units toward the pair of clamping units; and a moving mechanism for moving the first clamp to a clamping position in which the first clamp clamps the sheet bundle together with the second clamp, and to a release position in which the clamps on the sheet bundle are released, wherein the moving mechanism The sheet processing apparatus is characterized by comprising: a drive unit; a fixed part having a first surface, a second surface extending substantially perpendicularly from one end of the first surface, and a third surface facing the second surface and extending substantially perpendicularly from the other end of the first surface, to which the first clamp is fixed; a movable part located between the second surface and the third surface and movable relative to the fixed part in a first direction and a second direction opposite to the first direction; a biasing part provided between the first surface and the movable part and biasing the first surface and the movable part in a direction away from each other when elastically compressed; and a drive transmission unit that transmits the driving force from the drive unit to the movable part, moves the movable part in the first direction, compresses the biasing part between the movable part and the first surface, and moves the first clamp to the clamp position. [Effects of the Invention]

[0007] According to the present invention, a novel configuration can be provided for clamping a sheet bundle with a pair of clamping units. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic cross-sectional view of the image forming system according to the embodiment. [Figure 2] A schematic cross-sectional view of the sheet processing apparatus according to the embodiment. [Figure 3]A control block diagram of the image forming system according to the embodiment. [Figure 4] Enlarged cross-sectional view of the saddle portion according to the embodiment. [Figure 5] Front view of the corner back section according to the embodiment. [Figure 6] (a) Perspective view and (b) Cross-sectional view of the corner back processing unit according to the embodiment. [Figure 7] (a) A perspective view of the corner back section according to the embodiment, viewed from the front, and (b) A perspective view of the rear. [Figure 8] A perspective view showing a part of the corner back processing unit and drive unit according to an embodiment. [Figure 9] A perspective view of the vicinity of the corner back processing unit and clamp unit according to the embodiment. [Figure 10] Cross-sectional view of the corner back processing unit and clamping unit according to the embodiment. [Figure 11] A schematic diagram showing the operation of corner back processing in the embodiment, (a) the state in which the sheet bundle is stopped from being transported by the clamping unit, (b) the state in which the sheet bundle is clamped, (c) the state in which corner back processing is being performed on the sheet bundle, and (d) the state in which the clamp on the sheet bundle is released. [Figure 12] This diagram shows the corner back processing unit and clamp unit according to the embodiment as viewed from the sheet bundle discharge port side, with the upper clamp unit in the released position. [Figure 13] This diagram shows the square back processing unit and clamp unit according to the embodiment as viewed from the sheet bundle discharge port side, with the upper clamp unit in the clamp position. [Figure 14] This diagram shows the square back processing unit and clamping unit according to the embodiment, viewed from the sheet bundle discharge port side, illustrating the state in which the sheet bundle is clamped by the upper clamping unit and the lower clamping unit. [Figure 15]A side view of the corner back processing unit and clamp unit according to the embodiment, as seen from the front, showing (a) the upper clamp unit in the release position, (b) the upper clamp unit in the process of moving, and (c) the sheet bundle being clamped by the upper clamp unit and the lower clamp unit. [Figure 16] A perspective view from the front of the area around the front plate of the corner back processing unit and clamp unit according to the embodiment. [Figure 17] A perspective view from above of the upper portion of the corner back processing unit and clamp unit according to the embodiment. [Figure 18] A perspective view from the rear, showing the area around the front plate of the corner back processing unit and clamp unit according to the embodiment, with a portion of it cut away. [Modes for carrying out the invention]

[0009] Embodiments will be described using Figures 1 to 18. First, the schematic configuration of the image forming system of this embodiment will be described using Figure 1.

[0010] [Image Forming System] In this embodiment, a copier is used as the image forming apparatus, and a sheet processing apparatus is connected to the sheet discharge port of the copier. Further, a saddle part for performing middle binding and middle folding is provided inside the sheet processing apparatus. The image forming system 1000 includes an image forming apparatus A and a sheet processing apparatus B. The sheet S formed with an image by the image forming apparatus A is received by the downstream sheet processing apparatus B, and is subjected to middle binding processing, middle folding processing, corner binding processing, etc. as necessary, and then discharged to the downstream discharge part. The image forming apparatus A includes various structures such as, for example, a copier, a printer, a printing machine, a facsimile machine, and a multi-functional machine having a plurality of these functions. Hereinafter, the image forming apparatus A and the sheet processing apparatus B will be described in detail. In the following description, for the image forming apparatus A and the sheet processing apparatus B, the side where an operator such as a user operates the apparatus (for example, the side where an operation panel or operation buttons are provided) is referred to as the front side (F side, the front side of the paper surface in FIGS. 1, 2, etc.), and the side opposite to the front side is referred to as the rear side (R side, the back side of the paper surface in FIGS. 1, 2, etc.).

[0011] [Image Forming Apparatus] As shown in FIG. 1, the image forming apparatus A includes an image forming unit A1, an image reading unit A2, and an original document feeding unit A3. The image forming unit A1 includes a feeding unit 2, an image forming unit 3, a discharging unit 4, and a data processing unit 5 in a housing 1.

[0012] The sheet feeding unit 2 includes a plurality of cassettes 2a, 2b, 2c, and each cassette 2a, 2b, 2c can store a plurality of sheets S of different standard sizes selected in advance in multiple stages. The sheet S is, for example, paper, a plastic sheet, or the like. Each cassette 2a, 2b, 2c is provided with a separating mechanism for separating the internal sheets S one by one and a feeding mechanism for feeding out the sheets S. The sheet S stored in the sheet feeding unit 2 with such a configuration feeds out the sheet S of the size specified by the control unit 310 (FIG. 3) of the image forming apparatus A. The sheet S supplied from one of the plurality of cassettes 2a, 2b, 2c is further conveyed downstream by the conveying roller 7. The sheet conveyed by the conveying roller 7 has its leading edge aligned and its skew corrected by the registration roller pair 8. Then, the sheet S with its leading edge aligned by the registration roller pair 8 is fed to the image forming unit 3 on the downstream side at a predetermined timing.

[0013] A large-capacity cassette 2d and a manual feed tray 2e are connected to the image forming apparatus A. The large-capacity cassette 2d is composed of an optional unit that stores sheets of a size that is consumed in large quantities. The manual feed tray 2e is configured to be able to supply special sheets such as thick paper sheets, coated sheets, and film sheets for which separation feeding is difficult.

[0014] The image forming unit 3 may be configured to form an image on the sheet S sent from the sheet feeding unit 2, and various image forming mechanisms can be adopted. In the illustrated embodiment, an electrostatic image forming mechanism is shown as the image forming unit 3. However, the image forming unit 3 is not limited to the illustrated electrostatic image forming mechanism, and an inkjet image forming mechanism, an offset image forming mechanism, or the like can also be adopted.

[0015] The image forming unit 3 shown in Figure 1 includes a photoreceptor 9 formed in the shape of a drum or belt, an exposure device 10 for exposing the photoreceptor 9, a developing device 11 for developing the electrostatic latent image on the photoreceptor 9 using toner, a charging device (not shown) for charging the photoreceptor 9, and a cleaner (not shown) for cleaning the photoreceptor 9. Figure 1 shows a monochrome printing mechanism as an example. The photoreceptor 9 is exposed by the exposure device 10 to form an electrostatic latent image, and the electrostatic latent image is developed by the developing device 11 to form a toner image on the photoreceptor 9. The toner image formed on the photoreceptor 9 is transferred by the transfer device 12 to a sheet S transported from the registration roller pair 8. The sheet S on which the toner image has been transferred is fixed by the fixing device 13. The image forming unit A is also provided with an inversion transport path, which inverts the sheet S on which the toner image has been fixed by the fixing device 13, and then sends it back to the registration roller pair 8 to form an image on the back side of the sheet S. Downstream of the fixing device 13 and downstream of the branch to the reversal transport path, a discharge roller 15 is provided, and the sheet S is transported from the discharge port 16 of the image forming apparatus A to the sheet processing apparatus B, which will be described later, by the discharge roller 15.

[0016] An image reading unit A2, which optically reads the original image, is provided at the top of the image forming unit A1 configured in this way, and a document feeding unit A3 is mounted even higher up on the image reading unit A2.

[0017] The image reading unit A2 comprises a first platen glass 17, a second platen glass 21, a reading carriage 18 having a light source, a photoelectric conversion element 19, and a reduction optical system 20 composed of a combination of mirrors and lenses. The reading carriage 18 is scanned along the first platen glass 17 to illuminate the image of the document placed on the first platen glass 17 with light from the light source, and the reflected light from the image of the document is guided to the photoelectric conversion element 19 by the reduction optical system 20 to read the image. The photoelectric conversion element 19 converts the image data into an electrical signal and transfers it to the image forming unit 3, so that the image read by the image reading unit A2 can be formed on the sheet by the image forming unit A1.

[0018] The document feeding unit A3 comprises a feeding tray 22 and an output tray 24. It transports documents placed on the feeding tray 22 one by one, passes them over the second platen glass 21, and outputs them to the output tray 24. When scanning documents fed from the document feeding unit A3 and passing over the second platen glass 21, the scanning carriage 18 is stopped in advance below the second platen glass 21, and image data is read from the image passing over the second platen glass 21.

[0019] [Overall configuration of the sheet processing device] Next, the overall configuration of the sheet processing device B, which performs various processes such as binding and folding on sheets transported from the image forming apparatus A, will be explained using Figure 2. Figure 2 shows the detailed configuration of the sheet processing device B. After processing the sheets received by the sheet processing device B from the receiving section 26, which is the entrance to the transport path 28 connected to the discharge port 16 of the image forming apparatus A, the sheets can be loaded onto the first tray (first loading tray) 49, the saddle discharge unit 131, and the second tray (second loading tray) 71, which will be described later. In this embodiment, the term "path" refers to the entire route through which the sheets are transported by transport guides, transport rollers, etc.

[0020] In the illustrated apparatus, sheets sent to the transport path 28, which serves as the first transport route, are discharged to the first tray 49 after processing by the processing unit B1 described later, or sheets transported along the transport path 28 are discharged to the second tray 71, or sheets are discharged to the saddle discharge unit 131 after processing by the saddle unit B2 described later. Each of these devices has a control unit, a communication unit, etc., as shown in the block illustrating the control configuration of the entire apparatus in Figure 3, and controls the apparatus through these units.

[0021] The processing unit B1, which functions as an end-binding processing unit, is positioned vertically below the exit of the transport path 28. It collects sheets that have passed through the transport path 28 and been handed over to the first transport roller 36 (described later) to form a sheet bundle, and can perform a binding process, which is an example of a predetermined process, on the ends of this sheet bundle. The bound sheet bundle is loaded onto the first tray 49, which functions as a loading unit. The sheets or sheet bundles loaded onto the first tray 49 have their rear ends (upstream ends) abut against the loading wall 50 on the upstream side in the sheet discharge direction of the first tray 49, and are loaded along the loading wall 50.

[0022] The first tray 49 is movable up and down relative to the processing tray 37, which will be described later, and loads sheet bundles that have been bound by the binding mechanism 47, which will be described later. In this embodiment, the first tray 49 and the second tray 71 are movable up and down by a lifting mechanism (not shown).

[0023] The saddle section B2 is located below the transfer point of the saddle path 32, which is a second transport path branching vertically downward from the transport path 28. The sheets are sequentially transferred from the transport path 28 via the saddle path 32 and collected to form a sheet bundle. After saddle stitching, or folding without saddle stitching, the bundle is discharged to the saddle discharge unit 131. The details of each component will be described below.

[0024] [housing] As shown in Figure 2, the sheet processing apparatus B comprises a housing 27, a transport path 28, a processing unit B1, a saddle unit B2, a first tray 49, a saddle discharge unit 131, a second tray 71, and the like. The transport path 28, processing unit B1, and saddle unit B2 are located inside the housing 27. The transport path 28 also has a sheet receiving section 26 and a sheet transfer section 35. The processing unit B1 and saddle unit B2 process the sheets transferred from the transfer section 35 of the transport path 28. The first tray 49, saddle discharge unit 131, and second tray 71 load the sheets sent from each processing unit. The illustrated housing 27 is connected to the housing 1 of the image forming apparatus A, which is located upstream of the sheet transport direction in the transport path 28. The housing 27 and housing 1 are positioned such that their heights from the installation surface of the discharge port 16 of the image forming apparatus A and the receiving section 26 of the sheet processing apparatus B are approximately the same, and the discharge port 16 and the receiving section 26 are connected.

[0025] [Sheet delivery route] The transport path 28, which is the sheet loading route, is a substantially straight path that crosses the housing 27 in a substantially horizontal direction and includes a receiving section 26 connected to the discharge port (main body discharge port) 16 of the image forming apparatus A, and a transfer section 35 located on the opposite side across the apparatus from the receiving section 26. The transport path 28 is equipped with an inlet roller 29 and a first transport roller 201, which are transport rollers capable of transporting sheets in a first direction from the receiving section 26 toward the first discharge path 31, and a second transport roller 202 and a third transport roller 203, which are capable of transporting sheets in the first direction and also capable of transporting sheets in a second direction from the first discharge path 31 toward the receiving section 26. In other words, the inlet roller 29, the first transport roller 201, the second transport roller 202, and the third transport roller 203 are capable of transporting sheets in a first direction and in a second direction opposite to the first direction along the transport path, and are arranged in order from the receiving section 26 side toward the first direction.

[0026] The first discharge path 31 is connected to the transfer section 35 of the transport path 28, and a first transport roller 36 is positioned at this connection section. Sheets that are transferred from the transport path 28 to the first discharge path 31 and transported by the first transport roller 36 are either loaded onto the first tray 49 or guided to the processing unit B1. Note that the above-mentioned transport rollers may be other components capable of transporting sheets, such as transport belts.

[0027] [Layout of the sheet delivery route] As shown in Figure 2, the transport path 28 is connected to branch paths, the saddle path 32 and the upper transport path 30. The saddle path 32 and the upper transport path 30 are arranged sequentially from the receiving section 26 toward the first discharge path 31 in the first direction. The saddle path 32 branches off vertically downward from the transport path 28, and the upper transport path 30 branches off vertically upward from the transport path 28. At the branching points of the transport path 28 and the saddle path 32 and upper transport path 30, respectively, a saddle path switching member 33 and an upper transport path switching member 34 are provided to switch the transport direction of the transported sheets.

[0028] [Path branching point] The upper transport path switching member 34 is composed of a switching guide that moves to change the transport path so that the sheet brought in from the receiving section 26 is transported to either the first discharge path 31 or the upper transport path 30, and is moved by a drive unit (not shown) such as an electromagnetic solenoid or a mini motor.

[0029] [Upper transport path] The upper transport path 30 (printout transport path), which transports sheets other than those to be transported to the first transport path 31, branches off from the transport path 28, and the branching point is equipped with an upper transport path switching member 34 for guiding the sheets to the upper transport path 30. The upper transport path 30 is also equipped with a fourth transport roller 204, a fifth transport roller 205, a sixth transport roller 206, and a second transport roller 207 as transport rollers for guiding the sheets to the second tray 71. As a result, the sheets guided to the upper transport path 30 are transported from the upper transport path discharge port 40 to the second tray 71 (overflow tray).

[0030] The processing unit B1 consists of a processing tray 37, which serves as a loading unit for placing sheets transported along the first discharge path 31 downstream of the transport path 28 and for aligning and accumulating multiple sheets, and a binding mechanism 47 for binding the accumulated sheet bundles. The processing unit B1 then performs binding on the sheet bundles placed on the processing tray 37. The binding mechanism 47 is positioned vertically below the transport path 28. As shown in Figure 2, the processing tray 37 is positioned below the first discharge path 31, forming a step. Between the first discharge path 31 and the processing tray 37, there is a first switchback path that guides the sheets onto the processing tray 37 by changing the transport direction in the reverse direction while a portion of the sheets are discharged from the discharge port 31a of the first discharge path 31 to the first tray 49.

[0031] Specifically, the first discharge path 31 is equipped with an upper conveyor roller 41 and a lower conveyor roller 48 that grip and transport the sheet. The upper conveyor roller 41 and the lower conveyor roller 48 constitute a discharge roller pair 42 as a discharge section. The upper conveyor roller 41 can come into contact with and separate from the lower conveyor roller 48, and the upper conveyor roller 41 and the lower conveyor roller 48 can transport the sheet toward the first tray 49 and in the opposite direction while gripping the sheet. The upper conveyor roller 41 and the lower conveyor roller 48 can then transport the sheet toward the processing tray 37 via the first switchback path.

[0032] Furthermore, the upper transport roller 41 and the lower transport roller 48 (i.e., the discharge roller pair 42) discharge the sheets or bundles of sheets on the processing tray 37 from the discharge port 31a to the first tray 49, which serves as a loading tray (loading section). The discharge port 31a is a portion of the housing 27 that opens above the lower transport roller 48. In addition, the discharge roller pair 42 discharges sheets that have been transported to the first discharge path 31 without passing through the processing tray 37, when no processing is performed on the sheets, from the discharge port 31a to the first tray 49.

[0033] The binding mechanism 47 has a rear end regulating section 47a that contacts the end (rear end) of the sheet to position the sheet. A scraping section 38 is arranged on the processing tray 37 that conveys the sheets conveyed to the processing tray 37 by the upper conveying roller 41 and the lower conveying roller 48 toward the rear end regulating section 47a. The binding mechanism 47 then performs binding on the end of a sheet bundle consisting of multiple sheets placed on the processing tray 37, the position of which is regulated by the rear end regulating section 47a. The binding mechanism 47 also has a sheet bundle discharge mechanism that discharges the sheet bundle to the first tray 49 after performing binding on the end of the sheet bundle.

[0034] [Saddle Pass] The transport path 28 is connected to a saddle path 32 for transporting sheets to the saddle section B2 described above, and the path branching section is equipped with a saddle path switching member 33 for guiding sheets to the saddle path 32. Sheets guided to the saddle section B2 by the saddle path 32 undergo a folding process, and after the folding process, are discharged to the saddle discharge unit 131 via a substantially horizontal post-fold path guide 114, a second roller post-path guide 116, a clamp pre-guide 119, and a saddle discharge guide 124. In this embodiment, the saddle discharge guide 124, which serves as a discharge guide, is used as an auxiliary guide to ensure that sheets are properly loaded into the saddle discharge unit 131.

[0035] [Control Configuration] Using Figure 3, the control configuration of the image forming system 1000 will be outlined. First, the image forming apparatus A has a control unit 310, an operation unit 302, a transport control unit 303, an image processing unit 304, a drive unit 305, and a communication unit 306. The control unit 310 has a CPU (Central Processing Unit) 311, a ROM (Read Only Memory) 312, and a RAM (Random Access Memory) 313. The CPU 311 controls each part while reading programs corresponding to control procedures stored in the ROM 312. In addition, the RAM 313 stores work data and input data, and the CPU 311 controls by referring to the data stored in the RAM 313 based on the aforementioned programs, etc.

[0036] The operation unit 302 is connected to the control unit 310 and is, for example, an operation panel provided in the image forming apparatus A, where the operator performs the operation of the apparatus and various settings. The transport control unit 303 controls the various transport rollers and switching members that switch transport paths for transporting sheets in the image forming apparatus A. The image processing unit 304 controls the image forming unit 3. The drive unit 305 controls various motors and power supplies. The communication unit 306 connects the control unit 310 to external devices 301 such as a personal computer and the communication unit 321 of the sheet processing apparatus B so that they can communicate with each other.

[0037] The sheet processing apparatus B includes a stacker control unit 330, a transport control unit 322, an edge binding control unit 323, an discharge processing control unit 324, and a communication unit 321. The stacker control unit 330, like the control unit 310, includes a CPU 331, a ROM 332, and a RAM 333. The transport control unit 322 controls various transport rollers and switching members that switch transport paths for transporting sheets in areas other than the saddle section B2 of the sheet processing apparatus B. The edge binding control unit 323 controls the processing unit B1. The discharge processing control unit 324 controls the discharge of sheets and various loading trays on which the discharged sheets are stacked. The communication unit 321 connects the stacker control unit 330 to the communication unit 306 of the image forming apparatus A and the communication unit 341 of the saddle section B2 so that they can communicate with each other. Communication between the communication unit 306 and the communication unit 321 may be performed by wired communication or wireless communication.

[0038] The saddle unit B2 includes a saddle control unit 350, a transport control unit 342, a saddle stitching control unit 343, a center folding control unit 344, a corner spine processing control unit 345, and a communication unit 341. The saddle control unit 350, like the control unit 310, includes a CPU 351, a ROM 352, and a RAM 353. The transport control unit 342 controls the various transport rollers and switching members that switch transport paths for transporting sheets in the saddle unit B2. The saddle stitching control unit 343 controls the saddle stitching processing unit 104. The center folding control unit 344 controls the center folding processing mechanism C1. The corner spine processing control unit 345 controls the corner spine processing unit C2. The communication unit 341 connects the communication unit 321 of the sheet processing device B and the saddle control unit 350 so that they can communicate. In this embodiment, the saddle control unit 350 communicates with the stacker control unit 330 via the communication unit 341 and the communication unit 321, but a configuration in which each unit is controlled by a common control unit is also possible. Furthermore, in this embodiment, the sheet processing device B is controlled by a transport control unit 322, an edge binding control unit 323, an discharge processing control unit 324, a stacker control unit 330, and a saddle control unit 350. However, a configuration in which each unit is controlled by a single control unit is also possible.

[0039] [Saddle section] The saddle section B2 will be explained using Figures 2 and 4. The saddle section B2 has a center-folding mechanism C1 and a corner-back processing section C2. The center-folding mechanism C1 aligns and stacks the sheets sent via the transport path 28 to form a sheet bundle, performs a binding process at the center of the sheet bundle in the transport direction (the middle part of the second transport direction, which is the transport direction of the saddle path roller 100 as the second transport section, as described later), and performs a center-folding process (hereinafter also referred to as "magazine finishing") to fold the sheet bundle at the bound position. The corner-back processing section C2 is located downstream of the sheet bundle in the transport direction of the center-folding mechanism C1 (downstream of the first transport direction, which is the transport direction of the transport section and the saddle third roller pair 118 as the first transport section, as described later), and performs a corner-back processing to create a crease on the back of the center-folded sheet bundle or a corner-back processing (details will be described later) on the sheet bundle. Then, a saddle discharge unit 131 is positioned downstream of the corner-spine processing unit C2 in the first transport direction, and the bound sheet bundles are loaded onto it. It is also possible to assemble and stack one or more sheets and perform saddle stitching and corner-spine processing, or even just a center-folding process where the center of the sheet is folded in the transport direction without corner-spine processing.

[0040] [Folding mechanism] The center folding mechanism C1 includes a front-end regulating stopper 109, a saddle-stitching processing unit (saddle-stitching staple unit) 104, and a center folding processing unit 112, and stacks sheets into bundles, performs center folding, and saddle-stitching. Specifically, sheets transported from the transport path 28 to the saddle path 32 are transported by the saddle path roller 100, which serves as a second transport unit, to the stacking unit and the saddle stack tray 150, which serves as a second stacking unit. The saddle stack tray 150 stacks multiple sheets that have been transported in the second transport direction by the saddle path roller 100 via the saddle path 32 to form a sheet bundle. The sheet bundles stacked in the saddle stack tray 150 are positioned at a predetermined position on the saddle stack tray 150 by the front-end regulating stopper 109. The saddle-stitching processing unit 104 performs stapling on the center of the sheet bundle in the transport direction (intermediate part in the second transport direction) positioned by the front-end regulating stopper 109. The center folding processing unit 112 has a veneer plate 112a and a pair of folding rollers 113. By using the veneer plate 112a to press near the position where the sheet stack was stapled by the saddle stitching processing unit 104 (the center of the sheet stack in the transport direction) and transporting the sheet stack with the pair of folding rollers 113, the sheet stack is folded so that the spine of the sheet stack is on the downstream side in the transport direction. The center folding processing unit 112 can also perform center folding on sheet stacks that have not been stapled (or on a single sheet). Here, center folding refers to the process of folding the sheet stack in half by making a crease near the center of the sheet stack. The crease formed by the center folding processing unit 112 does not necessarily have to be in the center of the sheet stack and may be offset from the center within the tolerance range of the parts. The folding position may also be changed according to the user's settings.

[0041] The saddle stitching unit 104 is a mechanism that performs saddle stitching by moving the head unit and anvil unit along the center (line) of the sheet while the sheet bundle is sandwiched between the head unit and anvil unit. The center folding unit 112, as shown in Figures 2 and 4, employs a configuration in which the sheet bundle is inserted into the nip of a pair of folding rollers 113 that are pressed against each other by a veneer plate 112a, and the sheet bundle is conveyed while being folded by the rotation of the pair of folding rollers 113.

[0042] [Back and corner treatment area] The corner back processing unit C2 performs a corner back processing on the sheet bundle to create a corner back shape along the fold line of the folded sheet bundle. The corner back processing unit C2 comprises a pair of clamping units, a lower clamping unit 120 and an upper clamping unit 121, and a corner back processing unit (pressing unit) 134 having a pressing roller 123 as a first roller.

[0043] The lower clamping unit 120 and the upper clamping unit 121 clamp the sheet bundle and release it by moving relative to each other along the thickness direction of the sheet bundle (the direction in which the imaginary line connecting the respective rotation axes of the saddle third roller pair 118 extends, or the direction perpendicular to the roller transport direction 118c of the saddle third roller pair 118), which is transported by the saddle third roller pair 118, which will be described later. The pressing roller 123 presses the back of the sheet bundle by moving along the width direction of the sheet bundle (the direction perpendicular to the transport direction of the sheet bundle, the front and back directions in Figures 2 and 4). The corner back processing unit C2 then performs corner back processing on the back of the sheet bundle by pressing the back of the sheet bundle clamped by the lower clamping unit 120 and the upper clamping unit 121 with the pressing roller 123 while the back of the sheet bundle protrudes downstream from the lower clamping unit 120 and the upper clamping unit 121 in the first transport direction, thereby creating corners on the back of the sheet bundle. The term "corner" as used above includes curved surfaces and refers to the boundary between the front and back covers of the sheet bundle, and the boundary between the back and back covers. Furthermore, the "width direction of the sheet bundle" refers to the direction along the front-to-back direction of the image forming apparatus A and the sheet processing apparatus B, and will sometimes simply be referred to as the "width direction" below.

[0044] Specifically, the corner back processing unit C2 clamps a portion of the sheet bundle from both sides in the thickness direction of the sheet bundle using the lower clamp unit 120 and the upper clamp unit 121, with the back of the sheet bundle, which has been folded in the middle by the middle folding processing mechanism C1, protruding downstream in the first conveying direction. The pressing roller 123 presses the back of the sheet bundle, which is clamped by the lower clamp unit 120 and the upper clamp unit 121, while moving along the width direction of the sheet bundle, which is perpendicular to the conveying direction and the thickness direction of the sheet bundle. In this way, the corner back processing unit C2 performs corner back processing to create corners on the back of the sheet bundle. Corner back processing is a process in which the back of the sheet bundle, as shown in Figures 11(a) and (b) described later, is crushed by the pressing roller 123 to form two grooves on the back of the sheet bundle, as shown in Figures 11(c) and (d), thereby forming two corners on the back of the sheet bundle. Two corners are formed on the spine of the sheet bundle at positions that hold the staples driven in during the saddle stitching process by the saddle stitching processing unit 104, in the thickness direction of the sheet bundle. Additionally, the two corners formed on the spine of the sheet bundle are formed at positions that hold the fold created during the saddle folding process by the saddle folding processing unit 112.

[0045] Furthermore, a folding and conveying mechanism is positioned between the folding mechanism C1 and the corner back processing mechanism C2 to transport and stop the sheet bundle that has been folded in the folding mechanism C1 to the downstream corner back processing mechanism C2.

[0046] As described above, the processing unit B1 and the transport path 28 are arranged in a substantially horizontal direction, the saddle path 32 that guides the sheet to the saddle section B2 is arranged in a substantially vertical direction, and the saddle stack tray 150 that aligns and stacks the sheets is arranged to follow a substantially vertical direction. By arranging the transport path 28 along a direction that crosses the housing 27 in this way, and arranging the saddle path 32 and the saddle section B2 along a substantially vertical direction, it is possible to slim down the horizontal width of the device.

[0047] A saddle discharge unit 131 is positioned downstream of the sheet bundle in the conveying direction of the saddle section B2, and stores the sheet bundle folded in a magazine-like manner. The saddle discharge unit 131 shown in the figure is positioned vertically below the first tray 49. This is because the device is designed assuming that the first tray 49 is used more frequently than the saddle discharge unit 131, and therefore the height of the first tray 49 is set to make it easy to remove the sheets from the tray.

[0048] [Saddle section configuration] Next, we will explain in more detail the components of the saddle section B2: the folding mechanism C1, the folding and transporting mechanism C3, and the corner back processing section C2.

[0049] [Details of the folding mechanism] As shown in Figure 2, the saddle path switching member 33 guides the sheet to the center folding mechanism C1 by switching to transport the sheet to the saddle path 32. With respect to the height direction of the center folding mechanism C1, the following are arranged in order from the upper vertical side (upstream side), which is the entrance side: saddle entrance roller 101, sorting tap 102, rear end pressing guide 103, saddle stitching processing section 104, pull-in separation roller 105, center folding processing section 112, first alignment roller 107, second alignment roller 108, front end regulating stopper 109, and front end gripper 110.

[0050] The saddle inlet roller 101 further transports the sheets received from the saddle path 32 by the saddle path roller 100 downwards. The sorting beater 102 moves the sheets transported downwards from the saddle inlet roller 101 to the right side of Figure 2 and stacks the sheets in the saddle stack tray 150. The rear end pressing guide 103 holds down the rear end of the sheets stacked in the saddle stack tray 150. The saddle stitching processing unit 104 performs stitching on the center of the sheet bundle in the transport direction of the stacked sheets in the saddle stack tray 150. The pull-in / separation roller 105 assists in the transport of the sheets transported to the saddle stack tray 150 and is a roller that pulls the sheets toward the front end restricting stopper 109. The pull-in / separation roller 105 is positioned to be able to contact and separate from the opposing roller 105a.

[0051] The center folding section 112 includes a folding roller pair 113, a veneer plate 112a as a pressing part, and a roller guide 111. The folding roller pair 113 forms a fold in the center folding process. The veneer plate 112a pushes the sheet into the nip portion of the folding roller pair 113. The roller guide 111 covers the folding roller pair 113. The first alignment roller 107 and the second alignment roller 108 transport the sheets that have been conveyed to the saddle stack tray 150 and also perform alignment processing in the height direction of the sheets. The tip regulating stopper 109 determines the height position of the tip of the sheet by abutting against the tip (lower end) of the sheet that has been conveyed. The tip gripper 110 holds down the tip (lower end) of the sheet that has been loaded onto the tip regulating stopper 109.

[0052] The sheets transported from the saddle path 32 to the saddle section B2 are carried by the saddle entrance roller 101 to the front-end regulating stopper 109, which has been moved to a position appropriate to the sheet size. The pull-in / separation roller 105 has an auxiliary transport function to accurately transport the sheets in transit to the front-end regulating stopper 109 located in the saddle stack tray 150. At this time, the roller guide 111 partially covers the folding roller pair 113 to prevent the front end of the sheet from getting caught on the folding roller pair 113 and to transport it efficiently.

[0053] The first alignment roller 107 and the second alignment roller 108 accurately abut the conveyed sheet against the front-end regulating stopper 109, performing alignment processing in the sheet height direction.

[0054] The sorting and beating machine 102 moves the sheet that has been transported to the front regulating stopper 109 towards the rear end holding guide 103, and holds down the rear end (upper end) of the sheet with the rear end holding guide 103, thereby preparing to receive the next sheet. At this time, the rear end holding guide 103 moves to a position according to the size and waits.

[0055] The leading edge (lower end) of the sheet bundle formed by stacking a predetermined number of sheets on the saddle stack tray 150 is secured by the leading edge gripper 110. In this state, the saddle stitching section 104 performs a stitching process on the center of the sheet bundle in the second transport direction. After the stitching process, the leading edge regulating stopper 109 is lowered while the leading edge (lower end) of the sheet bundle is still held by the leading edge gripper 110. At this time, the leading edge regulating stopper 109 is lowered so that the position where the veneer 112a is pressed against the folding roller pair 113 is at half the size of the sheet, thereby lowering the sheet bundle from the stitching position.

[0056] When performing the center-folding process, the roller guide 111 is retracted, the tip gripper 110 is released, and then the center of the sheet bundle is folded with the veneer 112a and pushed into the nip portion of the roller pair 113. This completes the center-folding process of the sheet bundle.

[0057] The saddle inlet roller 101, the pull-in / separation roller 105, the sorting tapper 102, and the rear end pressing guide 103 are controlled by the transport control unit 342 (Figure 3). The front end restricting stopper 109, the front end gripper 110, the saddle stitching processing unit 104, the first alignment roller 107, and the second alignment roller 108 are controlled by the saddle stitching control unit 343 (Figure 3). Furthermore, the folding roller pair 113 and the veneer 112a are controlled by the saddle folding control unit 344 (Figure 3).

[0058] [Folding and transport mechanism] The configuration of the center-fold conveying mechanism C3 will be explained using Figures 2 and 4. The center-fold conveying mechanism C3 is a mechanism that transfers the sheet bundle that has been folded in the center-folding processing mechanism C1 to the corner-spine processing processing mechanism C2. Specifically, the center-fold conveying mechanism C3 first transports the center-folded sheet bundle using the folding roller pair 113 so that the spine of the sheet bundle is located downstream of the fore edge in the conveying direction, and then transfers the sheet bundle to the post-folding path guide 114. The post-folding path guide 114 is positioned along a direction (here, approximately horizontal) that bends vertically downward with respect to the folding roller conveying direction 113c (Figure 2), which is in the direction of a perpendicular line (the first imaginary line α2 described below, Figure 4) passing through the rotation centers of each roller of the folding roller pair 113 as the first conveying roller pair, and is positioned downstream of the folding roller pair 113 in the conveying direction.

[0059] Here, as shown in Figure 4, the first imaginary line α2 is defined as a straight line passing through the nip of the folding roller pair 113 when it is not gripping a sheet bundle, and is perpendicular to the width direction (the direction perpendicular to the conveying direction of the sheet bundle, the front and back direction in Figures 2 and 4), and passing through the nip of the folding roller pair 113 when it is not gripping a sheet bundle. In this case, the folding roller pair 113 is arranged such that the first imaginary line α2 is parallel to the horizontal direction or inclined vertically upward as it moves downstream in the conveying direction relative to the horizontal direction. In this embodiment, the first imaginary line α2 is inclined vertically upward as it moves downstream in the conveying direction relative to the horizontal direction. On the other hand, the post-folding path guide 114 extends in a direction inclined with respect to the first imaginary line α2, and in this embodiment, it extends in a substantially horizontal direction.

[0060] The post-fold path guide 114 guides the sheet bundle through transport and leads it to the saddle second roller pair 115 located downstream in the transport direction. The saddle second roller transport direction 115c, which is aligned with a perpendicular line to the line passing through the rotation center of each roller of the saddle second roller pair 115, is arranged to slope downward vertically as it moves downstream in the transport direction. The saddle second roller pair 115 is driven by the mid-fold control unit 344 to transport the sheet bundle.

[0061] The sheet bundles conveyed by the saddle second roller pair 115 are passed to a second roller rear path guide 116, which is located downstream in the conveying direction and parallel to the saddle second roller conveying direction 115c (Figure 2), and are guided by the second roller rear path guide 116. The second roller rear path guide 116 has a second roller rear path upper guide 116a that guides the upper surface of the sheet bundle and a second roller rear path lower guide 116b that guides the lower surface of the sheet bundle. A saddle conveying sensor 117 is positioned vertically above the guide surface of the second roller rear path upper guide 116a, and between the sheet bundle receiving port and the sheet bundle discharge port. This saddle conveying sensor 117 detects the position of the leading edge of the sheet bundle.

[0062] The second roller post-path guide 116 guides the sheet's transport and leads it to the saddle third roller pair 118 located downstream in the transport direction. The saddle third roller transport direction 118c (Figure 2), which is aligned with the perpendicular line (second virtual line β2, described below, Figure 4) to the line passing through the rotation centers of each roller of the saddle third roller pair 118, is arranged in a direction that slopes downward vertically as it moves downstream in the transport direction.

[0063] The saddle third roller pair 118, which serves as both the conveying section and the conveying roller pair, is driven by the center-folding control unit 344 and grips and conveys sheet bundles that have undergone saddle stitching and center-folding processing so that the spine of the sheet bundle is located downstream in the conveying direction from the end on the fore-edge side. In other words, the saddle third roller pair 118 conveys the sheet bundle so that the spine of the sheet bundle becomes the leading edge. If the direction in which the sheet bundle is conveyed by the saddle third roller pair 118, which is also the first conveying section, is defined as the first conveying direction (saddle third roller conveying direction 118c), then the saddle pass roller 100, which serves as the second conveying section that conveys the sheet to the center-folding processing mechanism C1, is located upstream of the saddle third roller pair 118 in the first conveying direction. The saddle pass roller 100 then conveys the sheet in a second conveying direction, which is different from the first conveying direction, upstream of the saddle third roller pair 118 in the first conveying direction. In the following, the upstream and downstream sides of the first conveying direction (saddle third roller conveying direction 118c), which is the direction in which the sheet bundle is conveyed by the saddle third roller pair 118, may simply be referred to as the "upstream side" and the "downstream side."

[0064] The folding roller pair 113, the second saddle roller pair 115, and the third saddle roller pair 118 are all driven by the same motor, and the center folding control unit 344 controls the drive of each of these roller pairs by controlling this motor. The third saddle roller pair 118 grips the sheet bundle folded by the center folding processing unit 112 and conveys it toward the corner back processing unit C2, and is located directly upstream of the corner back processing unit C2.

[0065] Here, as shown in Figure 4, the second imaginary line β2 is defined as a straight line perpendicular to the width direction and passing through the nip of the saddle third roller pair 118 when it is not gripping a sheet bundle, with the second imaginary line β1 passing through the rotation centers of the saddle third roller pair 118. In this case, the saddle third roller pair 118 is positioned such that the second imaginary line β2 intersects the first imaginary line α2, and the second imaginary line β2 is inclined vertically downward as it moves downstream in the conveying direction of the folding roller pair 113.

[0066] In other words, the saddle third roller pair 118 is positioned such that the second virtual line β2 is inclined vertically downward as it moves downstream in the transport direction relative to the horizontal. That is, in this embodiment, the second virtual line β2 is inclined with respect to the first virtual line α2. The folding roller pair 113 transports the sheet bundle in the horizontal direction or in a direction that is inclined vertically upward as it moves downstream in the transport direction relative to the horizontal (folding roller transport direction 113c). In contrast, the saddle third roller pair 118 transports the sheet bundle in a direction that is inclined vertically downward as it moves downstream in the transport direction relative to the horizontal (saddle third roller transport direction 118c).

[0067] Therefore, in this embodiment, the middle-fold transport path C4, which serves as a third transport path for transporting the sheet bundle between the folding roller pair 113 and the saddle third roller pair 118, is bent so that the sheet bundle transported by the folding roller pair 113 is handed over to the saddle third roller pair 118. That is, the middle-fold transport path C4 has a post-fold path guide 114 and a second roller post-path guide 116, and the transport path is bent between the post-fold path guide 114 and the second roller post-path guide 116. In other words, the direction in which the sheet bundle is guided by the second roller post-path guide 116 is inclined with respect to the direction in which the sheet bundle is guided by the post-fold path guide 114.

[0068] In this way, by making the conveying direction of the sheet bundles of the folding roller pair 113 different from the conveying direction of the sheet bundles of the saddle third roller pair 118, and by bending the conveying path between the post-folding path guide 114 and the post-second roller path guide 116, the width of the sheet processing device B (length in the second conveying direction, length in the left-right direction in Figure 2) can be reduced, and the device can be made smaller. In addition, by making the folding roller conveying direction 113c, which is the sheet conveying direction of the saddle third roller pair 118, diagonally downward, and by discharging the sheet bundles downward by the saddle third roller pair 118, the sheet bundles processed in the saddle section B2 can be discharged to a lower position in the device. As a result, the saddle discharge unit 131, which discharges the sheet bundles processed in the saddle section B2, can be placed lower in the device, and the amount that the first tray 49, located above the saddle discharge unit 131, can descend can be increased. As a result, the sheet loading capacity of the first tray 49 can be increased. Furthermore, the arrangement of the sheet or sheet bundle transport path guides and the transport direction of the sheet or sheet bundle may include cases where angles are introduced relative to horizontal, vertical, or parallel directions due to tolerances and other factors.

[0069] [Details of the back treatment area] The corner back processing unit C2 will be described with reference to Figures 2 and 4, and with reference to Figures 5 to 10. As described above, it comprises a lower clamp unit 120 and an upper clamp unit 121 as a pair of clamp units, and a corner back processing unit (pressing unit) 134 having a pressing roller 123. The clamping mechanism C5 having the lower clamp unit 120 and the upper clamp unit 121 has a pre-clamping guide 119, as shown in Figure 5. The pre-clamping guide 119 is positioned downstream of the saddle third roller pair 118 in the conveying direction, and is arranged in a direction that bends downward in the vertical direction with respect to the saddle third roller conveying direction 118c, and guides the conveying of the sheet bundle.

[0070] The clamping guide 119 has a clamping upper guide portion 119a as a first guide portion that guides the upper surface of the sheet bundle, and a clamping lower guide portion 119b as a second guide portion that guides the lower surface of the sheet bundle. The clamping upper guide portion 119a and the clamping lower guide portion 119b are positioned at a distance in the thickness direction from a line centered on the saddle third roller transport direction 118c that is greater than half the thickness of the sheet bundle that can pass through the device (the thickness of the sheet bundle when the center-folding process is performed on the sheet bundle of the maximum thickness that can be transported in the device). In other words, the distance between the clamping upper guide portion 119a and the clamping lower guide portion 119b is greater than the maximum thickness of the sheet bundle that can be processed by the sheet processing device B (the maximum thickness of the sheet bundle that can be folded by the center-folding mechanism C1). Note that at least one of the clamping upper guide portion 119a and the clamping lower guide portion 119b may be omitted.

[0071] The lower clamp unit 120 and the upper clamp unit 121, acting as a pair of clamping units, clamp and release the sheet bundle by moving relative to each other along the thickness direction of the sheet bundle conveyed by the saddle third roller pair 118. That is, the lower clamp unit 120 and the upper clamp unit 121 are relatively movable between a receiving position (release position) where they can receive the sheet bundle conveyed by the saddle third roller pair 118, and a clamping position (clamping position) where they clamp the sheet bundle. Then, by moving from the receiving position to the clamping position, the lower clamp unit 120 and the upper clamp unit 121 clamp a portion of the sheet bundle from both sides with respect to the thickness direction of the sheet bundle. In other words, the lower clamp unit 120 and the upper clamp unit 121 clamp the sheet bundle.

[0072] In this embodiment, the lower clamp unit 120, which is one of the clamping units, is fixed, and the upper clamp unit 121, which is the other clamping unit, is movable. That is, the upper clamp unit 121 moves toward the lower clamp unit 120 to clamp the sheet bundle. However, the upper clamp unit 121 may be fixed and the lower clamp unit 120 may be movable, or both may be movable. In any case, when processing the corner back, the sheet bundle is clamped between the upper clamp surface (upper clamp pressing part) 142a of the first clamp 142 of the upper clamp unit 121, which is the surface facing the lower clamp unit 120, and the lower clamp surface (lower clamp pressing part) 143a of the second clamp 143 of the lower clamp unit 120, which is the surface facing the upper clamp unit 121 (see Figures 5 and 11(a) to (d)).

[0073] The lower clamping surface 143a of the lower clamping unit 120 and the upper clamping surface 142a of the upper clamping unit 121 are parallel to the upper front guide portion 119a and the lower front guide portion 119b, respectively. The lower front guide portion 119b is fixed to the lower clamping unit 120, and the upper front guide portion 119a is fixed to the upper clamping unit 121. In this embodiment, the upper front guide portion 119a moves together with the upper clamping unit 121 in a substantially vertical direction (in the thickness direction of the sheet bundle).

[0074] [Square back processing unit] Next, the internal configuration of the corner back processing unit 134 will be explained using Figures 5 to 10. When the sheet bundle is clamped by the lower clamp unit 120 and the upper clamp unit 121, the corner back processing unit 134 presses the back of the sheet bundle that protrudes downstream in the conveying direction from the lower clamp unit 120 and the upper clamp unit 121 toward the lower clamp unit 120 and the upper clamp unit 121. Furthermore, while pressing the back of the sheet bundle toward the lower clamp unit 120 and the upper clamp unit 121, the corner back processing unit 134 moves in the width direction of the sheet bundle to create corners on the back of the sheet bundle.

[0075] The corner-back processing unit 134 has a unit frame 147, roller pressurizing sections 138a and 138b, pressurizing springs 145a and 145b, an upper movement restricting section 139, and a lower movement restricting section 140, as a configuration for supporting and moving the pressing roller (corner-back processing roller) 123 as the first roller. As shown in Figures 5 and 10, the pressing roller 123 is positioned so that its outer circumferential surface contacts the downstream end faces of the lower clamping unit 120 and the upper clamping unit 121, respectively. Furthermore, as shown in Figure 6(b), the pressing roller 123 has a roller shaft 141 positioned on its inner diameter side, and is rotatable relative to the roller shaft 141.

[0076] As shown in Figures 6(a) and (b), the unit frame 147 has a pair of side plates 147a positioned on both sides of the pressing roller 123, a rear side plate 147b positioned on the left side of the pressing roller 123 downstream in the first conveying direction (Figure 6(b)), and upper side plates 147c and lower side plates 147d positioned on both sides in the direction of the rotation axis of the pressing roller 123 and provided to bend from both ends of the rear side plate 147b. With this configuration, the unit frame 147 houses the pressing roller 123 inside each side plate while exposing the pressing roller 123 to the upstream side in the first conveying direction.

[0077] In this embodiment, the rear plate 147b, the upper plate 147c, and the lower plate 147d are integrally formed, and as shown in Figure 6(b), the cross-section is approximately U-shaped. These may be separate parts, or they may be integrally formed with a pair of side plates 147a. Both ends of the roller shaft 141 of the pressing roller 123 are rotatably supported by the upper plate 147c and the lower plate 147d, respectively. Furthermore, the upper plate 147c and the lower plate 147d extend upstream of the pressing roller 123 in the first conveying direction, and the upper movement restricting part 139 and the lower movement restricting part 140 are supported at their tip ends, respectively.

[0078] Specifically, the upper movement restricting part 139 is provided at the tip of a support shaft 139a that is fixed to the upper plate 147c and extends downward from the upper plate 147c. The lower movement restricting part 140 is provided at the tip of a support shaft 140a that is fixed to the lower plate 147d and extends upward from the lower plate 147d. The upper movement restricting part 139 is a roller rotatably supported at the tip of the support shaft 139a, and the lower movement restricting part 140 is a roller rotatably supported at the tip of the support shaft 140a. In this embodiment, two lower movement restricting parts 140 are arranged side by side, but one may be used. Similarly, two upper movement restricting parts 139 may also be used. The upper movement restricting part 139 and the lower movement restricting part 140 are located on both sides of the pressing roller 123 with respect to the rotation axis direction of the roller shaft 141.

[0079] Roller pressurizing sections 138a and 138b are connected to the roller shaft 141, respectively, on the outer side in the roller thickness direction of the pressing roller 123 and downstream in the conveying direction. Pressurizing springs 145a and 145b are positioned between the roller pressurizing sections 138a and 138b and the rear side plate 147b of the unit frame 147, and the roller shaft 141 is biased by the pressurizing springs 145a and 145b. Since the roller shaft 141 is configured to be movable in the conveying direction, the pressing force applied by the pressing roller 123 to the back of the sheet bundle due to the biasing force of the pressurizing springs 145a and 145b changes in accordance with the change in the amount of protrusion from the lower clamping unit 120 and upper clamping unit 121 of the back of the sheet bundle, which will be described later.

[0080] Furthermore, the pressure roller 123 is biased by pressure springs 145a and 145b via the roller shaft 141, thereby applying pressure to the lower clamp unit 120 and the upper clamp unit 121. On the opposite side of the pressure roller 123 from the lower clamp unit 120 and the upper clamp unit 121, the upper movement restricting section 139 and the lower movement restricting section 140 are positioned facing the lower clamp unit 120 and the upper clamp unit 121, respectively (Figure 5). That is, with respect to the conveying direction of the sheet bundle (first conveying direction), the upper movement restricting section 139 is positioned upstream of the lower clamp unit 120 and the upper clamp unit 121, and the lower movement restricting section 140 is positioned upstream of the lower clamp unit 120.

[0081] As shown in Figures 9 and 10, the upstream end face 120a of the lower clamp unit 120 is in contact with the lower movement restricting section 140. Similarly, the upstream end face 121a of the upper clamp unit 121 is in contact with the upper movement restricting section 139. In this embodiment, the lower movement restricting section 140 and the upper movement restricting section 139 are rollers having rotation axes in directions perpendicular to the width direction and the conveying direction of the sheet bundle (the vertical direction in Figure 10, and approximately vertical in this embodiment), respectively, and rotate while in contact with the end faces 120a and 121a. As a result, the pressure applied to the lower clamp unit 120 and the upper clamp unit 121 from the pressing roller 123 restricts their movement to the upstream side.

[0082] When the leading edge of the sheet bundle conveyed by the saddle third roller pair 118 is detected by the aforementioned saddle conveying sensor 117, the corner back processing control unit 345 counts the amount of conveyed and stops after conveying a predetermined amount. Specifically, as shown in Figure 11(a) described later, the sheet bundle is stopped with the back of the folded sheet bundle protruding downstream in the conveying direction from the upper clamp unit 121 and the lower clamp unit 120. In this embodiment, in corner back processing, the amount of the sheet bundle's back protruding from the upper clamp unit 121 and the lower clamp unit 120 is adjusted by controlling the amount of conveyed sheet bundle by the saddle third roller pair 118.

[0083] [Upper clamp unit and lower clamp unit] The upper clamp unit 121 moves from a receiving position for receiving the sheet bundle to a clamping position (clamping position) for holding the sheet bundle, thereby pressurizing the sheet bundle between itself and the lower clamp unit 120, and holding the sheet bundle with the upper clamp surface 142a and the lower clamp surface 143a. At this time, as shown in Figure 11(b) described later, the leading edge of the sheet bundle protrudes by a predetermined amount P1 from the downstream end faces 120c and 121b of the second clamp 143 of the lower clamp unit 120 and the first clamp 142 of the upper clamp unit 121, respectively, in the transport direction.

[0084] The upper clamp unit 121 operates by the corner back processing control unit 345 driving the clamp drive motor 132 (Figures 7(a) and (b)). As shown in Figures 7(a) and (b), the corner back processing unit C2 transmits the drive transmitted by the clamp drive train 133, which is composed of pulleys, belts, and a gear train, to the clamp drive links 810a and 810b (see Figure 12, etc.), thereby moving the upper clamp unit 121, which is connected to the clamp drive links 810a and 810b, in the direction of the sheet bundle thickness. Between the clamp drive links 810a and 810b and the upper clamp unit 121, there are multiple springs 802 built in as clamp springs (biasing parts) that pressurize the sheet bundle. The amount of movement of the clamp drive links 810a and 810b remains constant, but the amount of compression of the springs 802 changes according to the thickness of the sheet bundle, so that the applied pressure also changes. The clamp holding position also changes in the same way according to the thickness of the sheet bundle. Details of the movement configuration of the upper clamp unit 121 will be described later.

[0085] [Back and corner treatment area] As shown in Figure 11(c) described later, the corner back processing unit C2 performs corner back processing on a sheet bundle that is held between the lower clamp unit 120 and the upper clamp unit 121 with a predetermined protrusion amount P1 from the end faces 120c and 121b, by applying pressure to the back of the sheet bundle while scanning it in the width direction with a pressure roller 123 located downstream in the conveying direction.

[0086] During corner back processing, the corner back processing control unit 345 operates the drive motor 135 (Figure 7(b)) to move the corner back processing unit 134. The corner back processing unit 134 is connected to the drive belt 137 shown in Figure 8. The drive belt 137 is arranged in the width direction of the sheet bundle. The corner back processing unit 134 is also movable in the width direction of the sheet bundle along the guide rail 120b shown in Figure 9, which will be described later. The drive belt 137 rotates when power is transmitted from the drive motor 135 via a drive train 136 (Figure 7(b)) which is composed of a gear train. This enables the corner back processing unit 134 to scan the sheet bundle in the width direction.

[0087] In other words, this embodiment has a drive mechanism 135a that moves the corner-back processing unit 134 along the direction of the sheet bundle. The drive mechanism 135a includes a drive motor 135 as a drive source, a drive belt 137, and a drive train 136. The drive motor 135 moves the corner-back processing unit 134 along the width direction of the sheet bundle.

[0088] The home position of the corner back processing unit 134 is located on the front side of the sheet processing device B (the right side (F side) in Figure 12, which will be described later). For example, corner back processing is performed on the sheet bundle by moving the corner back processing unit 134 from its home position to the rear side. A sensor (not shown) is provided at the home position of the corner back processing unit 134, making it possible to detect the position of the corner back processing unit 134. However, the home position of the corner back processing unit 134 may be set to the rear side, and the scanning of the corner back processing unit 134 in the width direction may be performed from the rear side to the front side. Furthermore, if the length in the width direction (FR direction) of the sheet bundle is short (in the case of a sheet bundle composed of small-sized sheets), the corner back processing may be performed on the first sheet bundle by moving the corner back processing unit 134 from the rear side to the front side, and then on the second sheet bundle by moving the corner back processing unit 134 from the front side to the rear side. In this configuration, home positions may be provided on both the front and rear sides of the seat processing device B, and home position sensors may be provided on both sides.

[0089] Furthermore, in a single corner-back processing cycle, the pressure roller 123 is moved in one direction, either from the front to the rear or from the rear to the front. However, the pressure roller 123 may also be moved back and forth in a single corner-back processing cycle. For example, in a single corner-back processing cycle, the setting for whether the pressure roller 123 moves in one direction or back and forth may be configured depending on the number and type of sheets included in the sheet bundle. This setting may be performed automatically by the control unit, or it may be set by an operator such as a user or service technician. Moreover, the operator may be able to arbitrarily set whether the pressure roller 123 moves in one direction or back and forth in a single corner-back processing cycle.

[0090] As shown in Figures 9 and 10, the lower clamp unit 120 has a guide rail 120b formed along the width direction of the sheet bundle. The lower movement restricting portion 140 moves along the guide rail 120b while engaging with it as the corner back processing unit 134 moves in the width direction of the sheet bundle. The guide rail 120b is formed by combining multiple members, as shown in Figure 10, with a substantially U-shaped cross-section, and is formed so that a part of the roller-shaped lower movement restricting portion 140 can enter it. The lower surface on the outer diameter side of the lower movement restricting portion 140 engages with the lower surface of the guide rail 120b, and the outer peripheral surface of the lower movement restricting portion 140 abuts against the end face 120a. This restricts the movement of the corner back processing unit 134 in the thickness direction of the sheet bundle when it moves. Note that the guide rail 120b may also be a groove formed in a part of the lower clamp unit 120 on the upstream side in the conveying direction.

[0091] After the corner backing is complete, the corner backing unit 134 is moved in the width direction by operating the drive motor 135 (Figure 7(b)). This moves the corner backing unit 134 out of the sheet bundle transport path. Furthermore, the upper clamp unit 121 is moved away from the sheet bundle by operating the clamp drive motor 132 (Figures 7(a) and (b)) (Figure 11(d), described later). This makes it possible to transport the sheet bundle further downstream. Note that it is also possible to discharge the sheet bundle without performing the corner backing described above.

[0092] [Discharge section] As shown in Figure 2, the sheet bundle that has passed through the saddle section B2 is conveyed by the saddle third roller pair 118 toward the saddle discharge guide 124, which is located further downstream in the first conveying direction than the pressure roller 123. The saddle discharge guide 124 is supported so as to be able to swing about a first pivot point 124b, which has a rotation axis parallel to the rotation axis of each roller of the saddle third roller pair 118. The first pivot point 124b is located above the line extending from the conveying direction of the sheet bundle by the saddle third roller pair 118 (first conveying direction, saddle third roller conveying direction 118c). The saddle discharge guide 124 is positioned to hang vertically downward from the first pivot point 124b.

[0093] Furthermore, the saddle discharge guide 124 has a side surface on the upstream side in the first conveying direction that slopes towards the upstream side in the first conveying direction as it moves from the first support point 124b towards the intermediate portion 124a in the vertical direction. Also, the side surface on the upstream side in the first conveying direction of the saddle discharge guide 124 slopes towards the downstream side in the first conveying direction as it moves from the intermediate portion 124a towards the lower end in the vertical direction. In other words, the side surface on the upstream side in the first conveying direction of the saddle discharge guide 124 is formed to bend so that the intermediate portion 124a in the vertical direction protrudes more towards the upstream side in the first conveying direction than the other parts. And, a guide surface 124d is provided between the intermediate portion 124a and the lower end of the side surface on the upstream side in the first conveying direction of the saddle discharge guide 124.

[0094] The guide surface 124d is located below the line extending from the saddle third roller conveying direction 118c described above, and contacts the sheet bundle conveyed by the saddle third roller pair 118, guiding the sheet bundle downward. The saddle discharge guide 124 is rotatable around the first pivot point 124b when the sheet bundle contacts the guide surface 124d. However, depending on the rigidity of the sheet bundle, the saddle discharge guide 124 may not contact the guide surface 124d, and even if contact occurs, the amount of rotation will vary depending on the rigidity, so the saddle discharge guide 124 does not necessarily rotate.

[0095] Furthermore, a second pivot point 124c is provided at the lower end of the saddle discharge guide 124, and the saddle discharge roller 125, described later, is rotatably connected to the second pivot point 124c. The second pivot point 124c is located below the guide surface 124d and has a pivot axis parallel to the pivot axis of the first pivot point 124b.

[0096] As the sheet bundle continues to be transported by the saddle third roller pair 118, it is passed to the saddle discharge unit 131, which is located downstream of the corner back processing unit 134 in the first transport direction and vertically below the saddle discharge guide 124. The saddle discharge unit 131 has a saddle discharge upstream belt 127, a saddle discharge upstream sensor 128, a saddle discharge downstream belt 129, and a saddle discharge downstream sensor 130.

[0097] The saddle discharge upstream belt 127 is located below the guide surface 124d of the saddle discharge guide 124, and conveys the sheet bundles guided downward by the guide surface 124d while further guiding them downstream. The saddle discharge upstream belt 127 is inclined so that it is vertically downward as it moves downstream in the conveying direction. The saddle discharge downstream belt 129, which serves as the sheet bundle discharge section, receives the sheet bundles conveyed from the saddle discharge upstream belt 127 and conveys them while further guiding them downstream. The saddle discharge downstream belt 129 is inclined so that it is vertically upward as it moves downstream in the conveying direction. Therefore, the sheet bundles guided by the guide surface 124d to the saddle discharge upstream belt 127 are conveyed in a direction inclined vertically downward by the saddle discharge upstream belt 127, and then conveyed in a direction inclined vertically upward by the saddle discharge downstream belt 129.

[0098] Furthermore, a saddle discharge upstream sensor 128 is positioned on the upstream side of the conveyable area of ​​the saddle discharge upstream belt 127 to detect sheet bundles on the upstream side, and a saddle discharge downstream sensor 130 is positioned on the upstream side of the conveyable area of ​​the saddle discharge downstream belt 129 to detect sheet bundles on the downstream side.

[0099] The sheet bundles, once handed over to the saddle discharge unit 131, are guided and transported by the saddle discharge upstream belt 127 and the saddle discharge downstream belt 129, after which the sheet bundles are loaded. The saddle discharge upstream belt 127 grips the sheet bundles at a nip point between itself and the aforementioned saddle discharge rollers 125 on the downstream side in the transport direction. The sheet bundles on the saddle discharge upstream belt 127 are configured to suppress opening on the opening side (short end side) at this nip point. The position of this nip point can be changed using the second support point 124c as the support point depending on the thickness of the sheet bundle.

[0100] While processing subsequent sheet bundles, the preceding sheet bundle is transported upstream in the transport direction by the saddle discharge upstream belt 127, and stops at a predetermined transport amount after detection by the saddle discharge upstream sensor 128 and the saddle discharge downstream sensor 130. This transport amount is at a position that suppresses the opening of the opening side of the preceding sheet bundle at the nip point between it and the saddle discharge roller 125, and is positioned such that it contacts the upper surface of the preceding sheet bundle when the subsequent sheet bundle is discharged. In other words, in this embodiment, the saddle discharge unit 131 is configured to stack the subsequent sheet bundle on top of the preceding sheet bundle.

[0101] In this way, the saddle discharge unit 131 discharges the subsequent sheet bundle onto the upper surface of the preceding sheet bundle without entering the opening of the preceding sheet bundle, thereby stably loading the subsequent sheet bundle onto the preceding sheet bundle without any problems such as snagging, curling, or pushing out. In other words, by appropriately changing the amount of conveyance according to the size of the sheet bundle, the subsequent sheet bundle can be stably loaded onto the preceding sheet bundle.

[0102] The saddle discharge port 126 is located downstream of the saddle discharge guide 124 in the first conveying direction, and between the saddle discharge upstream belt 127 and the saddle discharge downstream belt 129. The sheet bundles conveyed to the saddle discharge unit 131 are discharged to the outside of the sheet processing device B by passing through the saddle discharge port 126, making it easier for the user to access the discharged sheet bundles.

[0103] Furthermore, if another device exists downstream of the saddle discharge unit 131, it is possible to transfer the sheet bundle to the downstream device by continuing to transport it without loading. In addition, in this embodiment, a discharge cover 151 is provided on the outside of the saddle discharge port 126 as a cover member. The discharge cover 151 is positioned so as not to obstruct the discharge of the sheet bundle from the saddle discharge port 126, and is also positioned so that operators such as users cannot access the inside of the device through the saddle discharge port 126.

[0104] [Arch back processing control] Next, the control of the corner spine processing in this embodiment will be explained using Figures 11(a) to (d). As described above, the corner spine processing unit C2 performs corner spine processing on the spine of the sheet bundle that has undergone saddle stitching and saddle folding processing. Hereafter, the control for performing corner spine processing may be referred to as the corner spine processing mode. In addition, the saddle folding control unit 344 shown in Figure 3 controls each of the transport roller pairs, the folding roller pair 113, the saddle second roller pair 115, and the saddle third roller pair 118, with the same drive.

[0105] The corner back processing mode will now be explained. The corner back processing mode is a mode in which the pressure roller 123 is pressed against the back of the sheet bundle Sb to form a corner on the back of the sheet bundle Sb. The center folding control unit 344, triggered by the detection of the leading edge of the sheet bundle Sb by the saddle transport sensor 117, transports the center-folded sheet bundle Sb between the upper clamp unit 121 and the lower clamp unit 120, which are separated. Then, as shown in Figure 11(a), the center folding control unit 344 stops transporting the sheet bundle Sb when the back Ssp of the sheet bundle Sb protrudes further downstream in the first transport direction than the end faces 121b and 120c of the upper clamp unit 121 and the lower clamp unit 120.

[0106] In this state, the corner back processing control unit 345 drives the clamp drive motor 132 (Figures 7(a), (b)) to move the upper clamp unit 121 toward the lower clamp unit 120, and the sheet bundle Sb is clamped by the upper clamp unit 121 and the lower clamp unit 120 as shown in Figure 11(b). At this time, the back Ssp of the sheet bundle Sb protrudes by P1 downstream from the end faces 121b and 120c on the first conveying direction downstream side of the upper clamp unit 121 and the lower clamp unit 120.

[0107] Next, the corner back processing control unit 345 operates the drive motor 135 (Figure 7(b)) to move the corner back processing unit 134 in the width direction of the sheet bundle Sb. At this time, as shown in Figure 11(c), the pressing roller 123 of the corner back processing unit 134 moves in the width direction while applying pressure to the back Ssp of the sheet bundle Sb, thereby performing corner back processing on the back Ssp of the sheet bundle Sb. After that, as shown in Figure 11(d), the corner back processing control unit 345 drives the clamp drive motor 132 (Figures 7(a), (b)) to separate the upper clamp unit 121 from the lower clamp unit 120, releasing the clamping of the sheet bundle Sb. In the first mode, the corner back processing is completed up to this point, and the above-described sheet bundle Sb discharge operation is performed.

[0108] As mentioned above, in the corner-back processing, the pressure roller 123 strongly presses the spine of the sheet bundle vertically, so it is required that the sheet bundle be saddle-stitched before the corner-back processing is performed. This is because if corner-back processing is performed on a sheet bundle that has not been saddle-stitched, the pressure from the pressure roller 123 will cause the sheets on the inside of the sheet bundle to shift.

[0109] [Regarding the movement configuration of the upper clamp unit] Next, the details of the movement configuration of the upper clamp unit 121 will be explained with reference to Figure 10 and using Figures 12 to 18. As described above, the upper clamp unit 121 has a first clamp 142 and, together with the second clamp 143 of the lower clamp unit 120, clamps the sheet bundle conveyed by the saddle third roller pair 118. In this embodiment, the movement mechanism 800 moves the first clamp 142 between a clamping position (clamping position) where the sheet bundle is clamped by the first clamp 142 and the second clamp 143, and a release position (receiving position) where the clamp is released.

[0110] Figure 12 shows the state in which the first clamp 142 of the upper clamp unit 121 is in the released position. The corner back processing unit 134 is retracted to a position outside the sheet bundle passage area in the width direction that intersects (intersects in this embodiment) the sheet bundle conveying direction. Therefore, if corner back processing is not performed, the sheet bundle can pass between the first clamp 142 and the second clamp 143 and be discharged.

[0111] Figure 13 shows the state in which the first clamp 142 of the upper clamp unit 121 is in the clamping position. If there is no sheet bundle between the upper clamp unit 121 and the lower clamp unit 120, the upper clamp unit 121 will descend to the position shown in Figure 13, and the first clamp 142 and the second clamp 143 will be able to come into contact with each other.

[0112] Figure 14 shows the state in which the sheet bundle Sb is clamped by the first clamp 142 of the upper clamp unit 121 and the second clamp 143 of the lower clamp unit 120. In the state shown in Figure 14, the corner back processing unit 134 moves in the width direction to perform corner back processing. After the corner back processing is performed, the state returns to that shown in Figure 12, and as described above, the sheet bundle is conveyed toward the saddle discharge guide 124 by the saddle third roller pair 118. The retracted position of the corner back processing unit 134 is on the front side plate 180 side, but it may also be on the rear side plate 190 side as long as it does not obstruct the discharge of the sheet bundle, and it may be changed each time the processing is performed.

[0113] The upper clamp unit 121 has an upper stay 160 as a fixing part, and the lower clamp unit 120 has a lower stay 170. The upper stay 160 is movably supported by the front side plate 180 and the rear side plate 190 that constitute the frame of the corner back section C2. The front side plate 180, as the first side plate, is the side plate on one side (front side) in the width direction, and as will be described in detail later, it movably supports one side of the upper stay 160 in the width direction. The rear side plate 190, as the second side plate, is the side plate on the other side (rear side) in the width direction, and as will be described in detail later, it movably supports the other side of the upper stay 160 in the width direction. The first clamp 142 is fixed to the upper stay 160.

[0114] On the other hand, the lower stay 170 is fixed to the front plate 180 and the rear plate 190 on both sides in the width direction. The second clamp 143 is fixed to the lower stay 170. The widthwise lengths of the first clamp 142 and the second clamp 143 are longer than the widthwise length of the maximum size of a sheet that can be processed with a corner back section C2, in other words, a sheet that can be folded in the middle folding mechanism C1, and shorter than the lengths of the upper stay 160 and the lower stay 170 in the width direction.

[0115] The first clamp 142 and the second clamp 143 are the parts that hold the sheet bundle, and therefore require particular rigidity. For this reason, in this embodiment, they are made of metal blocks. On the other hand, the upper stay 160 that fixes the first clamp 142 and the lower stay 170 that fixes the second clamp 143 are made by bending a single sheet of metal, or by combining multiple bent sheet metals. In this way, in this embodiment, the upper clamp unit 121 and the lower clamp unit 120 are made of a part formed from sheet metal and a metal block, respectively, so the clamp unit can be made smaller and lighter. As a result, the clamps can be moved without making the mechanism for driving the clamps unnecessarily large.

[0116] The upper clamp unit 121 is movable by clamp drive links 810a and 810b provided at both ends in the width direction. The clamp drive links 810a and 810b are connected by a transmission shaft 820, and the clamp drive row 133 that drives the clamp drive links 810a and 810b is fixed to the front plate 180. That is, the moving mechanism 800 that moves the first clamp 142 of the upper clamp unit 121 has a clamp drive motor 132 as a drive unit (Figures 7(a) and (b)), an upper stay 160 as a fixed unit, a spacer 801 as a movable unit (see Figure 10, etc.), a spring 802 as a biasing unit (see Figure 10, etc.), and a drive transmission unit 803. As will be described in more detail later, the drive transmission unit 803 transmits the driving force from the clamp drive motor 132 to the spacer 801, and by moving the spacer 801, the first clamp 142 is moved to the clamp position.

[0117] The drive transmission unit 803 includes a clamp drive train 133 as a link transmission unit (see Figures 15(a) to (c), etc.), clamp drive links 810a and 810b as a link mechanism, and a transmission shaft 820. As will be described later, the clamp drive train 133 transmits the drive of the clamp drive motor 132 to the transmission shaft 820. As shown in Figures 12 to 14, the transmission shaft 820 is arranged in the width direction and connects the front clamp drive link 810a and the rear clamp drive link 810b. The transmission shaft 820 then transmits the driving force from the clamp drive train 133 to the clamp drive links 810a and 810b on both sides.

[0118] The clamp drive link 810a and clamp drive row 133, which constitute the first link mechanism, are positioned on one side (front side) in the width direction relative to the front plate 180. On the other hand, the clamp drive link 810b, which constitutes the second link mechanism, is positioned on the other side (rear side) in the width direction relative to the front plate 180, and on one side in the width direction relative to the rear plate 190. By positioning the rear clamp drive link 810b on the front side relative to the rear plate 190 in this way, the device can be made smaller in the front-to-back direction (width direction) than if the clamp drive link 810b were positioned on the rear side relative to the rear plate 190. In contrast, the front clamp drive link 810a is positioned on the front side relative to the front plate 180 because the clamp drive row 133 is also positioned on the front side relative to the front plate 180.

[0119] In other words, even if the clamp drive link 810a is positioned further rear than the front plate 180, the clamp drive row 133 is positioned further front than the front plate 180, making it difficult to reduce the size in the width direction. If, for example, the clamp drive row 133 were to be positioned further rear than the front plate 180 in addition to the clamp drive link 810a, the upper clamp unit 121 and lower clamp unit 120 would be located further rear than the front plate 180, making it difficult to secure space for their installation. Conversely, if these mechanisms were to be installed further rear than the front plate 180, the front plate 180 would need to be positioned further forward, again making it difficult to reduce the size in the width direction. Therefore, in this embodiment, the clamp drive link 810a and the clamp drive row 133 are positioned on the front side (i.e., outside the device) of the front plate 180, which is easier to install, while the rear clamp drive link 810b is positioned on the front side of the rear plate 190 (i.e., inside the device). This allows for efficient arrangement of each mechanism and enables miniaturization of the device in the width direction.

[0120] [Stay Up] The upper stay 160, which serves as the fixing part, has a stay portion 160a and an engaging sheet metal 160b. As shown in Figure 10, the stay portion 160a is formed in a roughly U-shape in cross-section by bending the sheet metal. That is, the stay portion 160a has a roughly U-shape in cross-section perpendicular to the width direction, and has an open shape on the opposite side from the lower clamp unit 120 and on both sides in the width direction, and extends in the front-rear direction (width direction) as shown in Figures 12 to 14.

[0121] Specifically, the stay portion 160a has a first plate portion 161, a second plate portion 162 bent in a direction approximately right-angle from one end of the first plate portion 161, and a third plate portion 163 bent in a direction approximately right-angle from the other end of the first plate portion 161. The first plate portion 161 has a first surface 161a, the second plate portion 162 has a second surface 162a, and the third plate portion 163 has a third surface 163a. ​​These surfaces 161a to 163a are the inner surfaces of a sheet metal with a U-shaped cross-section. That is, the second surface 162a is a surface extending in a direction approximately right-angle from one end of the first surface 161a, and the third surface 163a is a surface facing the second surface 162a and extending in a direction approximately right-angle from the other end of the first surface 161a. The first clamp 142 is fixed to the surface of the first plate portion 161 opposite to the first surface 161a.

[0122] Here, "approximately right angle" generally includes the dimensional tolerance range of 89° to 91° when bending sheet metal into a U-shape. Furthermore, the stay portion 160a may be made of multiple sheet metal pieces rather than a single sheet, as long as the cross-section is U-shaped. For example, two L-shaped sheet metal pieces can be combined to form a U-shape. In this case, the two sheet metal pieces are fixed together by welding or screws. However, bending a single sheet metal piece into a U-shape is preferable in terms of strength. In addition, the upper stay 160 may be made of materials other than sheet metal, for example, by casting to create a square cross-section, or by applying plastic deformation processes such as drawing or extrusion to steel to create a U-shaped cross-section. In any case, making the stay portion 160a U-shaped in cross-section allows for weight reduction while ensuring rigidity. Note that the shape of the stay portion 160a is not limited to a U-shaped cross-section; it may also be a square cross-section. That is, it may be shaped like a hollow rectangular prism.

[0123] Furthermore, as shown in Figure 15(a), the upper stay 160 has an engaging sheet metal 160b as part of the fixing portion. The engaging sheet metal 160b is a sheet metal fixed to both ends in the width direction of the stay portion 160a, and is fixed so as to close a part of the opening at the width direction end of the stay portion 160a. The engaging sheet metal 160b has an elongated through hole 164 formed in the upper clamp unit 121 that is long in the direction of movement. The clamp shafts 811 of the clamp drive links 810a and 810b are inserted through the through hole 164, as will be described in more detail later, and the clamp shafts 811 are movable within a predetermined range with respect to the direction of movement of the spacer 801, which will be described next.

[0124] Furthermore, as shown in Figure 10, the spacer 801, which acts as a movable part, is positioned between the second surface 162a and the third surface 163a of the stay portion 160a. The spacer 801 is relatively movable with respect to the upper stay 160 in a first direction and a second direction opposite to the first direction. The first direction is the same direction in which the upper clamp unit 121 moves from the release position to the clamp position (downward direction in Figure 10), and the second direction is the same direction in which the upper clamp unit 121 moves from the clamp position to the release position (upward direction in Figure 10). In this embodiment, the spacer 801 is relatively movable with respect to the upper stay 160 while sliding against the second surface 162a and the third surface 163a. ​​A clamp shaft 811 is fixed to the spacer 801, as will be described later, and the spacer 801 moves in the first and second directions by the clamp shaft 811. Note that a part of the spacer 801 does not need to be positioned between the second surface 162a and the third surface 163a. For example, the upper portion of the spacer 801 may protrude upward from between the second surface 162a and the third surface 163a in Figure 10.

[0125] Furthermore, as shown in Figure 10, a spring 802 acting as a biasing element is provided between the first surface 161a of the stay portion 160a and the spacer 801. When elastically compressed, the spring 802 biases the first surface 161a and the spacer 801 away from each other. The spring 802 is, for example, a compression coil spring. Note that the biasing element may be other elastic members besides a spring, such as rubber.

[0126] [Drive transmission section] Next, the detailed configuration of the drive transmission unit 803 will be described using Figures 15(a) to 18. Figures 15(a) to 15(c) are front views of the corner back processing unit C2. Figure 15(a) shows the state in which the first clamp 142 of the upper clamp unit 121 is in the release position. Figure 15(b) shows the state in which the first clamp 142 is moving between the release position and the clamp position. Figure 15(c) shows the state in which the sheet bundle is clamped by the upper clamp unit 121 and the lower clamp unit 120.

[0127] The upper stay 160 is capable of reciprocating between a release position and a clamp position by a drive transmission unit 803. The front plate 180 and the rear plate 190 have through holes 180a (the rear plate 190 is not shown) through which the upper stay 160 passes, and each of the through holes 180a is open so that the upper stay 160 can move between a release position and a clamp position.

[0128] The drive transmission unit 803 transmits the driving force from the clamp drive motor 132 to the spacer 801, moving the spacer 801 in a first direction, thereby compressing the spring 802 between the spacer 801 and the first surface 161a of the upper stay 160, and moving the first clamp 142 fixed to the upper stay 160 to the clamped position. The drive transmission unit 803 also has a clamp shaft 811 as an engaging part. As described above, the clamp shaft 811 engages with the through hole 164 of the engaging sheet metal 160b, which is part of the fixed part, within a predetermined range with respect to the movement direction of the spacer 801 (i.e., the first and second directions). The drive transmission unit 803 moves the clamp shaft 811 in a second direction by the driving force from the clamp drive motor 132, engaging the clamp shaft 811 with the through hole 164 of the engaging sheet metal 160b, and further moves the clamp shaft 811 in the second direction, thereby moving the first clamp 142 to the released position.

[0129] As described above, such a drive transmission unit 803 includes a clamp drive train 133, clamp drive links 810a and 810b, and a transmission shaft 820. The clamp drive train 133 includes a motor gear 132a provided on a clamp drive motor 132 fixed to the front plate 180, a gear 1331 fixed to the front plate 180, a toothed belt 1332 wrapped around the motor gear 132a and the gear 1331, and a gear train 1333. The toothed belt 1332 is subjected to a predetermined tension by a pulley 1334. The driving force transmitted from the clamp drive motor 132 to the gear 1331 via the toothed belt 1332 is transmitted to the transmission shaft 820 by the gear train 1333.

[0130] The transmission shaft 820 is rotatably supported by the front plate 180 and the rear plate 190. As the transmission shaft 820 rotates, the driving force transmitted to the transmission shaft 820 is further transmitted to the clamp drive links 810a and 810b. Since the configuration of the clamp drive links 810a and 810b is the same, only the front clamp drive link 810a will be described below. The clamp drive link 810a has a first link 816 that rotates around the first shaft 815 when the drive of the clamp drive motor 132 is transmitted, and a second link 818 that is connected to the first link 816 via the second shaft 817, and also connected via the spacer 801 and the clamp shaft 811 which acts as the third shaft. Furthermore, the clamp drive link 810a has a third link 812 fixed to the transmission shaft 820, and a fourth link 814 which is connected to the third link 812 via shaft 813, and also connected to the first link 816 and the second link 818 via second shaft 817.

[0131] As the transmission shaft 820 rotates, the third link 812 rotates, causing the fourth link 814, which is connected to the third link 812 via shaft 813, to rotate. When the transmission shaft 820 rotates clockwise in Figures 15(a) to (c), the fourth link 814 rotates from the position shown in Figure 13(a) to Figure 13(b). Consequently, the first link 816 and the second link 818 rotate. The fourth link 814, the first link 816, and the second link 818 are each rotatably mounted relative to the second shaft 817. Therefore, the rotation of the fourth link 814 causes the second shaft 817 to move, which in turn causes the second link 818 to move. A clamp shaft 811 is fixed to one end of the second link 818.

[0132] As described above, a spacer 801 is fixed to the clamp shaft 811. The clamp shaft 811 is also inserted through a through hole 164 formed in the engaging sheet metal F160b. As described above, when the second link 818 moves, the clamp shaft 811 and spacer 801 move along the inner wall of the stay portion 160a. When the fourth link 814 rotates from the position shown in Figure 13(b) to the position shown in Figure 13(c), the first clamp 142 of the upper clamp unit 121 moves to the clamp position. At this time, as shown in Figure 13(c), the first shaft 815, the second shaft 817, and the clamp shaft 811 are positioned in a substantially straight line. In other words, the first link 816 and the second link 818 are in a substantially straight line. In this embodiment, since the first axis 815, the second axis 817, and the clamp axis 811 are positioned in a substantially straight line at the clamping position for clamping the sheet bundle, even if a strong pressure is applied to the sheet bundle from the upper clamping unit 121 at the clamping position, it is possible to suppress the first link 816 and the second link 818 from rotating due to repulsive forces such as the biasing force of the spring, and the sheet bundle can be clamped stably.

[0133] Next, the transmission of drive from the clamp drive train 133 to the transmission shaft 820 will be described. As shown in Figures 16 to 18, the drive transmitted from the clamp drive motor 132 to the clamp drive train 133 is transmitted to the gear 1335. The gear 1335 is connected to the gear 1336 (Figure 18), which is located on the opposite side of the front plate 180. The gear 1336 meshes with the gear 821 to which the transmission shaft 820 is fixed. Therefore, the driving force transmitted to the gear 1335 is transmitted to the gear 821 via the gear 1336, and the transmission shaft 820, which is fixed to the gear 821, rotates together with the gear 821. The transmission shaft 820 is connected to the rear clamp drive link 810b, and the driving force transmitted to the transmission shaft 820 is also transmitted to the clamp drive link 810b. Note that the transmission shaft 820 does not have to be a shaft with a circular cross-section, as long as it can be connected to the link mechanism. It may have other shapes such as a square cross-section.

[0134] As shown in Figure 16, the clamp shaft 811 and spacer 801 are located inside the stay portion 160a of the upper stay 160. As described above, a spring 802 is provided between the first plate portion 161 of the stay portion 160a and the spacer 801. As described above, the clamp shaft 811 and spacer 801 are slidable between the second plate portion 162 and the third plate portion 163 of the stay portion 160a by the driving force transmitted via the transmission shaft 820 by the clamp drive links 810a and 810b. The first clamp 142 is fixed to the surface of the first plate portion 161 of the stay portion 160a opposite to the first surface 161a. Also, as described above, the clamp shaft 811 engages with the through hole 164 of the engaging sheet metal 160b.

[0135] Therefore, as the clamp shaft 811 moves in the first direction by the clamp drive links 810a and 810b, the spacer 801 to which the clamp shaft 811 is fixed moves, compressing the spring 802 between the spacer 801 and the first plate portion 161 of the stay portion 160a, and moving the first clamp 142 to the clamping position. At this time, the compressed spring 802 presses against the stay portion 160a due to its elastic restoring force, and the first clamp 142 clamps the sheet bundle with pressure between itself and the second clamp 143 based on the biasing force of the spring 802.

[0136] On the other hand, the clamp shaft 811 moves in the second direction by the clamp drive links 810a and 810b, causing the clamp shaft 811 to engage with the through hole 164 of the engaging sheet metal 160b, and moving the stay portion 160a to which the engaging sheet metal 160b is fixed, and the first clamp 142 fixed to this stay portion 160a, from the clamped position to the released position.

[0137] In this embodiment, one clamp drive link 810a and one 810b are provided on the front plate 180 side and one on the rear plate 190 side, respectively, making it possible to press the first clamp 142 toward the second clamp 143 from both sides in the width direction. In addition, in this embodiment, as shown in Figure 17, multiple spacers 801 are arranged. In the illustrated example, four spacers 801 are arranged on each side in the width direction, for a total of eight spacers 801. These multiple spacers 801 are fixed to a single clamp shaft 811. That is, in this embodiment, one clamp shaft 811 is arranged in the width direction, and the clamp drive links 810a and 810b are configured to move both sides of the clamp shaft 811 in the width direction, respectively.

[0138] Similarly to the spacers 801, there are also eight springs 802, four on each side in the width direction. These multiple spacers 801 and springs 802 are arranged inside the stay portion 160a, with eight springs 802 positioned between the eight spacers 801 and the first plate portion 161 of the stay portion 160a, corresponding to the eight spacers 801.

[0139] In this embodiment, of the four sets of spacers 801 and springs 802 on the front side in the width direction, one set of spacers 801 and springs 802 is positioned in front of the clamp drive link 810a, and the remaining three sets of spacers 801 and springs 802 are positioned in the vicinity of the front plate 180, but on the rear side of the front plate 180. Similarly, of the four sets of spacers 801 and springs 802 on the rear side in the width direction, one set of spacers 801 and springs 802 is positioned in the rear of the clamp drive link 810b, and the remaining three sets of spacers 801 and springs 802 are positioned in the vicinity of the rear plate 190, but on the front side of the rear plate 190. In other words, the spacers 801 and springs 802 are positioned as far as possible on both sides in the width direction. This allows the springs 802 to be positioned as far away from the first clamp 142 as possible in the width direction, thereby increasing the pressure exerted on the first clamp 142 by the biasing force of the springs 802.

[0140] Furthermore, in this embodiment, by arranging the spring 802 inside the stay portion 160a to which the first clamp 142 is fixed, the spring 802 can be held stably with a simple configuration. In addition, the size of the upper clamp unit 121 in the direction of movement can be reduced. The number of spacers 801 and springs 802 is not limited to this, and any configuration with one or more on each side is acceptable. By making the biasing force approximately the same at the front and rear, variations in the clamping force when clamping the sheet bundle can be suppressed.

[0141] Furthermore, in this embodiment, the first link 816, second link 818, third link 812, and fourth link 814 of the clamp drive links 810a and 810b move along the front side plate 180 and the rear side plate 190, respectively. That is, the direction of the axis connecting these links is perpendicular to each side plate. Therefore, compared to a configuration in which the link mechanism rotates away from the side plate, it is possible to reduce the size in the front-rear direction (sheet bundle width direction).

[0142] Furthermore, in this embodiment, as shown in Figure 18, the front plate 180, which movably supports one side (front side) of the upper stay 160 in the width direction, is provided with a bearing 181 as a rotation guide that guides the movement of the upper stay 160 by contacting and rotating with the upper stay 160. In this embodiment, multiple bearings 181 are provided on both sides of the through hole 180a through which the upper stay 160 passes, on the rear side surface of the front plate 180. The stay portion 160a of the upper stay 160 is sandwiched between the multiple bearings 181. When the upper stay 160 moves in the first and second directions, the bearings 181 contact the outer surface of the second plate portion 162 and the outer surface of the third plate portion 163 of the stay portion 160a and rotate, thereby guiding the movement of the upper stay 160. This allows for stable movement of the upper stay 160 and stable clamping operation by the upper clamp unit 121.

[0143] Although Figure 18 only shows the configuration on the front side plate 180, multiple bearings 181 are similarly arranged on the rear side plate 190. In this embodiment, a total of six bearings 181, three on each side of the through hole 180a, are arranged along the direction of movement of the upper stay 160, but the number of bearings 181 can be set as appropriate. Furthermore, although the bearings 181 are arranged on the rear side of the front side plate 180 and the front side of the rear side plate 190 (i.e., inside each side plate), they may also be arranged on the outside of each side plate, or on the inside of one side plate and on the outside of the other side plate. Moreover, bearings 181 may be arranged on both the inside and outside sides of each side plate.

[0144] <Other Embodiments> In the embodiments described above, the corner back processing unit 134 was described in which a pressing roller 123 presses the back of the sheet bundle. However, the pressing member that presses the sheet bundle is not limited to the pressing roller 123, but any configuration that can press the back of the sheet bundle and move along the back to perform corner back processing is acceptable, and other configurations such as sheet metal with a curved surface may also be used.

[0145] In the above-described embodiment, the corner back processing is performed downstream inside the saddle section B2 within the sheet processing device B, but the same corner back processing may be performed in a separate housing connected to the outside. For example, it may be a standalone unit that performs only corner back processing without performing saddle stitching or folding. In this case, this unit has the corner back processing unit C2 described above, and a transport unit such as a pair of transport rollers that transports the sheet bundle that has undergone saddle stitching and folding processing in the corner back processing unit C2.

[0146] Furthermore, in the above-described embodiment, the sheet processing apparatus B has a control unit that controls each internal component of the sheet processing apparatus B. However, the internal components of the sheet processing apparatus B may also be controlled by a control unit provided in the image forming apparatus.

[0147] Furthermore, although the above embodiment described a pair of rollers as the conveying unit for transporting sheets within the sheet processing device B, a configuration in which sheets are transported by a belt is also possible. Specifically, it may be a configuration in which a belt is used to grip and transport the sheets with a pair of rollers, a configuration in which a belt is used to grip and transport the sheets, or a configuration in which a belt and rollers grip the sheets. The conveying configuration may be changed depending on the position and path along which the sheets are transported. For example, a pair of rollers may be used to transport the sheets at one position, and a pair of belts may be used to transport the sheets at another position.

[0148] Furthermore, although the above-described embodiment described an image forming system 1000 in which the sheet processing apparatus B is directly connected to the image forming apparatus A, other system configurations are also possible. For example, a configuration in which other processing apparatuses or transport devices are connected between the image forming apparatus A and the sheet processing apparatus B is also possible. In addition, although the above-described embodiment described an image forming apparatus A that forms monochrome images using toner as an example, it may also be an image forming apparatus that forms color images using toner, or an image forming apparatus that forms images on a sheet using ink.

[0149] Furthermore, the disclosure of this embodiment includes the following configuration. (Composition 1) A conveying unit that conveys sheet bundles that have been folded in the middle so that the spine of the sheet bundle is located downstream in the conveying direction from the end of the sheet bundle, or sheet bundles that have been saddle-stitched and folded in the middle, A pair of clamping units including a first clamp and a second clamp that clamps a bundle of sheets conveyed by the conveying unit together with the first clamp, In a state in which the sheet bundle is clamped by the pair of clamp units, a pressing unit presses the back of the sheet bundle that protrudes downstream in the conveying direction from the pair of clamp units toward the pair of clamp units, The device includes a moving mechanism that moves the first clamp to a clamping position where the first clamp clamps the sheet bundle together with the second clamp, and to a release position where the clamping of the sheet bundle is released. The aforementioned moving mechanism is The drive unit and A fixing portion having a first surface, a second surface extending substantially perpendicularly from one end of the first surface, and a third surface facing the second surface and extending substantially perpendicularly from the other end of the first surface, to which the first clamp is fixed, A movable part located between the second surface and the third surface, which is movable relative to the fixed part in a first direction and a second direction opposite to the first direction, A biasing portion is provided between the first surface and the movable portion, and when elastically compressed, biases the first surface and the movable portion in a direction away from each other, The drive transmission unit transmits the driving force from the drive unit to the moving unit, moves the moving unit in the first direction, compresses the biasing unit between the moving unit and the first surface, and moves the first clamp to the clamp position. A sheet processing apparatus characterized by the following: (Configuration 2) The aforementioned drive transmission unit is The movable part has an engaging portion that engages with a part of the fixed portion within a predetermined range with respect to the direction of movement of the movable part, The driving force from the drive unit moves the engaging portion in the second direction, thereby engaging the engaging portion with a part of the fixing portion, and further moving the engaging portion in the second direction moves the first clamp to the release position. A sheet processing apparatus according to configuration 1, characterized by the above. (Composition 3) The movable part is movable relative to the fixed part while sliding against the second and third surfaces. A sheet processing apparatus according to configuration 1 or 2, characterized by the above. (Composition 4) With respect to the width direction intersecting the conveying direction of the sheet bundle by the conveying unit, the lengths of the first clamp and the second clamp are longer than the length of the largest sheet that can be folded in the middle, and shorter than the length of the fixing unit. A sheet processing apparatus according to any one of configurations 1 to 3, characterized by the above. (Composition 5) The drive transmission unit has a link mechanism, The link mechanism includes a first link that rotates around the first axis when the drive of the drive unit is transmitted, and a second link that is connected to the first link via the second axis and also connected to the movable part via the third axis, and with the first clamp positioned at the clamp position, the first axis, the second axis and the third axis are positioned in a substantially straight line. A sheet processing apparatus according to any one of configurations 1 to 4, characterized by the above. (Composition 6) With respect to the width direction intersecting the conveying direction of the sheet bundle by the conveying unit, the fixed part is further provided with a side plate that movably supports one side of the fixed part, The first and second links move along the side plate. The sheet processing apparatus according to configuration 5, characterized by the above. (Composition 7) When the link mechanism is designated as the first link mechanism, the drive transmission unit is: A transmission shaft through which the drive of the aforementioned drive unit is transmitted, The first link mechanism moves the movable part by a drive transmitted from the transmission shaft, It has a second link mechanism that moves the movable part by a drive transmitted from the transmission shaft. A sheet processing apparatus according to configuration 5 or 6, characterized by the above. (Composition 8) With respect to the width direction intersecting the conveying direction of the sheet bundle by the conveying unit, a first side plate movably supports one side of the fixing unit, The system further comprises a second side plate that movably supports the other side of the fixed portion in the width direction, The drive transmission unit further includes a pre-link transmission unit that transmits the drive of the drive unit to the transmission shaft. The first link mechanism and the pre-link transmission section are arranged on one side in the width direction relative to the first side plate. The second link mechanism is located on the other side in the width direction of the first side plate, and on one side in the width direction of the second side plate. A sheet processing apparatus according to configuration 7, characterized by the above. (Composition 9) With respect to the width direction intersecting the conveying direction of the sheet bundle by the conveying unit, a side plate movably supports one side of the fixing unit, The system further includes a rotating guide portion provided on the side plate, which rotates in contact with the fixing portion to guide the movement of the fixing portion. A sheet processing apparatus according to any one of configurations 1 to 8, characterized by the above. (Composition 10) The fixing portion comprises a first plate portion having the first surface, a second plate portion having the second surface and bent at approximately a right angle from one end of the first plate portion, and a third plate portion having the third surface and bent at approximately a right angle from the other end of the first plate portion. The first clamp is fixed to the side of the first plate portion opposite to the first surface. A sheet processing apparatus according to any one of configurations 1 to 9, characterized by the above. (Composition 11) An image forming unit having an image forming section that forms an image on a sheet, A sheet processing device according to any one of configurations 1 to 10, comprising The sheet processing apparatus is a sheet bundle in which an image has been formed by the image forming unit, and the sheet bundle, which has undergone saddle stitching and saddle folding, is clamped by the pair of clamping units, and the back of the sheet bundle that protrudes downstream in the transport direction from the pair of clamping units is pressed toward the pair of clamping units by the pressing unit. An image forming system characterized by the following features. [Explanation of Symbols]

[0150] 3. Image forming unit 118...Saddle third roller pair (conveyor section) 120... Lower clamp unit 121... Upper clamp unit 132...Clamp drive motor (drive unit) 133...Clamp drive train (transmission section before link) 134... Corner back processing unit (pressing unit) 142...First clamp 143...Second clamp 160... Upper stay (fixing part) 160a...Stay section 160b...Engaging Sheet Metal 161...1st plate part 161a...Front page 162...Second plate part 162a...Second side 163...Third plate part 163a...3rd page 180...Front side plate (first side plate) 190...Rear side plate (second side plate) 800...Moving mechanism 801...Spacer (movable part) 802... Spring (biasing part) 803... Drive transmission section 810a... Clamp drive link (first link mechanism) 810b... Clamp drive link (second link mechanism) 811... Clamp shaft (engaging part) 820...Transmission shaft 1000...Image forming system A...Image forming apparatus B... Sheet processing device C2... Square back processing area

Claims

1. A conveying unit that conveys sheet bundles that have been folded in the middle so that the spine of the sheet bundle is located downstream in the conveying direction from the end of the sheet bundle, or sheet bundles that have been saddle-stitched and folded in the middle, A pair of clamping units including a first clamp and a second clamp that clamps a bundle of sheets conveyed by the conveying unit together with the first clamp, In a state in which the sheet bundle is clamped by the pair of clamp units, a pressing unit presses the back of the sheet bundle that protrudes downstream in the conveying direction from the pair of clamp units toward the pair of clamp units, The device includes a moving mechanism that moves the first clamp to a clamping position where the first clamp clamps the sheet bundle together with the second clamp, and to a release position where the clamping of the sheet bundle is released. The aforementioned moving mechanism is The drive unit and A fixing portion having a first surface, a second surface extending substantially perpendicularly from one end of the first surface, and a third surface facing the second surface and extending substantially perpendicularly from the other end of the first surface, to which the first clamp is fixed, A movable part located between the second surface and the third surface, which is movable relative to the fixed part in a first direction and a second direction opposite to the first direction, A biasing portion is provided between the first surface and the movable portion, and when elastically compressed, biases the first surface and the movable portion in a direction away from each other, The drive transmission unit transmits the driving force from the drive unit to the moving unit, moves the moving unit in the first direction, compresses the biasing unit between the moving unit and the first surface, and moves the first clamp to the clamp position. A sheet processing apparatus characterized by the following:

2. The aforementioned drive transmission unit is The movable part has an engaging portion that engages with a part of the fixed portion within a predetermined range with respect to the direction of movement of the movable part, The driving force from the drive unit moves the engaging portion in the second direction, thereby engaging the engaging portion with a part of the fixing portion, and further moving the engaging portion in the second direction moves the first clamp to the release position. The sheet processing apparatus according to feature 1.

3. The movable part is movable relative to the fixed part while sliding against the second and third surfaces. The sheet processing apparatus according to feature 1.

4. With respect to the width direction intersecting the conveying direction of the sheet bundle by the conveying unit, the lengths of the first clamp and the second clamp are longer than the length of the largest sheet that can be folded in the middle, and shorter than the length of the fixing unit. The sheet processing apparatus according to feature 1.

5. The drive transmission unit has a link mechanism, The link mechanism includes a first link that rotates around a first axis when the drive of the drive unit is transmitted, and a second link that is connected to the first link via a second axis and also connected to the movable part via a third axis, and with the first clamp positioned at the clamp position, the first axis, the second axis and the third axis are positioned in a substantially straight line. The sheet processing apparatus according to feature 1.

6. With respect to the width direction intersecting the conveying direction of the sheet bundle by the conveying unit, the fixed part is further provided with a side plate that movably supports one side of the fixed part, The first link and the second link move along the side plate. The sheet processing apparatus according to feature 5.

7. When the link mechanism is designated as the first link mechanism, the drive transmission unit is: A transmission shaft through which the drive of the aforementioned drive unit is transmitted, The first link mechanism moves the movable part by the drive transmitted from the transmission shaft, It has a second link mechanism that moves the movable part by a drive transmitted from the transmission shaft. The sheet processing apparatus according to feature 5.

8. With respect to the width direction intersecting the conveying direction of the sheet bundle by the conveying unit, a first side plate movably supports one side of the fixing unit, The system further comprises a second side plate that movably supports the other side of the fixed portion in the width direction, The drive transmission unit further includes a pre-link transmission unit that transmits the drive of the drive unit to the transmission shaft. The first link mechanism and the pre-link transmission section are arranged on one side in the width direction relative to the first side plate. The second link mechanism is located on the other side in the width direction of the first side plate, and on one side in the width direction of the second side plate. The sheet processing apparatus according to feature 7.

9. With respect to the width direction intersecting the conveying direction of the sheet bundle by the conveying unit, a side plate movably supports one side of the fixing unit, The system further includes a rotating guide portion provided on the side plate, which rotates in contact with the fixing portion to guide the movement of the fixing portion. The sheet processing apparatus according to feature 1.

10. The fixing portion comprises a first plate portion having the first surface, a second plate portion having the second surface and bent at approximately a right angle from one end of the first plate portion, and a third plate portion having the third surface and bent at approximately a right angle from the other end of the first plate portion. The first clamp is fixed to the side of the first plate portion opposite to the first surface. The sheet processing apparatus according to feature 1.

11. An image forming unit having an image forming section that forms an image on a sheet, A sheet processing apparatus according to any one of claims 1 to 10, comprising The sheet processing apparatus is a sheet bundle in which an image has been formed by the image forming unit, and the sheet bundle, which has undergone saddle stitching and saddle folding, is clamped by the pair of clamping units, and the back of the sheet bundle that protrudes downstream in the transport direction from the pair of clamping units is pressed toward the pair of clamping units by the pressing unit. An image forming system characterized by the following features.

Images