Sheet processing device and image formation system

Abstract

To suppress the opening of a sheet bundle even if corner spine processing is not performed.SOLUTION: A corner spine processing unit 134 performs corner spine processing for forming a corner on the back of a sheet bundle by pressing the back of the sheet bundle which protrudes downstream in the transport direction from a lower clamp unit 120 and an upper clamp unit 121 toward the lower clamp unit 120 and the upper clamp unit 121 in a state that the sheet bundle is clamped by the lower clamp unit 120 and the upper clam unit 121 and moving in the width direction of the sheet bundle in a state that the back of the sheet bundle is pressed toward the lower clamp unit 120 and the upper clamp unit 121. An increased folding processing unit 500 applies pressure processing to the creases of the sheet bundle by moving in the width direction of the sheet bundle while clamping the creases.SELECTED DRAWING: Figure 12

Description

Technical Field

[0001] The present invention relates to a sheet processing apparatus that performs cornering processing and additional folding processing 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, in a state where a sheet bundle subjected to center folding processing is clamped by a pair of clamp portions, the back portion of the sheet bundle protruding from the clamp portions is pressed by a roller to perform a process of forming a corner on the back of the sheet bundle (hereinafter, cornering process) (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, in the configuration described in Patent Document 1, by forming a corner on the back of the sheet bundle, the opening of the sheet bundle discharged onto the stacking tray can be suppressed, and the occurrence of stacking defects on the stacking tray can be suppressed. However, for a user who wants to perform only center folding processing, or only center binding processing and center folding processing, without forming a corner on the back of the sheet bundle, there is a risk of stacking defects in the sheet bundle after discharge.

[0005] Therefore, in an apparatus having a configuration for performing cornering processing on a sheet bundle, it is desired to suppress the opening of the sheet bundle even when the cornering processing is not performed.

Means for Solving the Problems

[0006] One aspect of the present invention is a conveying unit that conveys a sheet bundle that has been subjected to a middle folding process or a sheet bundle that has been subjected to a middle binding process and a middle folding process so as to be located on the downstream side in the conveying direction from the end on the short back side of the sheet bundle, a pair of clamping units that clamp the sheet bundle, and a first pressing unit that presses the back of the sheet bundle that protrudes on the downstream side in the conveying direction from the pair of clamping units toward the pair of clamping units in a state where the sheet bundle is clamped by the pair of clamping units, and the first pressing unit that performs a corner-back process of forming a corner on the back of the sheet bundle by moving in the width direction of the sheet bundle while pressing the back of the sheet bundle toward the pair of clamping units, and a second pressing unit that performs a pressing process on the fold of the sheet bundle by moving in the width direction of the sheet bundle while sandwiching the fold of the sheet bundle. A sheet processing apparatus comprising:

Effects of the Invention

[0007] According to the present invention, in an apparatus having a configuration for performing a corner-back process on a sheet bundle, even when the corner-back process is not performed, the opening of the sheet bundle can be suppressed.

Brief Description of the Drawings

[0008]

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Mode for Carrying Out the Invention

[0009] <First Embodiment> The first embodiment will be described with reference to FIGS. 1 to 21. First, the schematic configuration of the image forming system of this embodiment will be described with reference to FIG. 1.

[0010] [Image Forming System] In this embodiment, a copier is used as the image forming apparatus. A sheet processing apparatus is connected to the sheet discharge port of this copier, and the sheet processing apparatus further includes a saddle part that performs middle binding and middle folding processing inside. 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 middle binding processing, middle folding processing, corner binding processing, etc. are performed 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 multifunction 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, regarding 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 there is an operation panel or operation buttons) 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, and 2c. Each cassette 2a, 2b, 2c can store a plurality of sheets S or the like of different standard sizes selected in advance in multiple stacks. 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 having such a configuration feeds out the sheet S of the size designated 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 downstream image forming unit 3 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 for storing 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 and feeding are difficult.

[0014] The image forming unit 3 only needs to 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 it is also possible to adopt an inkjet image forming mechanism, an offset image forming mechanism, or the like.

[0015] In the image forming unit 3 shown in FIG. 1, there are provided a photosensitive member 9 formed in a drum shape or a belt shape, an exposure device 10 for exposing the photosensitive member 9, a developing device 11 for developing an electrostatic latent image on the photosensitive member 9 using toner, a charging device (not shown) for charging the photosensitive member 9, and a cleaner (not shown) for cleaning the photosensitive member 9. In FIG. 1, a monochrome printing mechanism is shown as an example. The photosensitive member 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 photosensitive member 9. The toner image formed on the photosensitive member 9 is transferred to a sheet S conveyed from the registration roller pair 8 by a transfer device 12. The sheet S onto which the toner image has been transferred is fixed by a fixing device 13. Further, the image forming apparatus A is provided with a reverse conveyance path. After the sheet S on which the toner image has been fixed by the fixing device 13 is reversed front to back, it is sent to the registration roller pair 8 again to form an image on the back surface of the sheet S. A discharge roller 15 is provided downstream of the fixing device 13 and downstream of the branch to the reverse conveyance path, and the discharge roller 15 conveys the sheet S from the discharge port 16 of the image forming apparatus A to a sheet processing apparatus B described later.

[0016] An image reading unit A2 for optically reading a document image is provided above the image forming unit A1 configured as described above, and a document feeding unit A3 is mounted further above the image reading unit A2.

[0017] The image reading unit A2 includes 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 configured by combining mirrors and lenses. Then, the reading carriage 18 is scanned along the first platen glass 17, the image of the document placed on the first platen glass 17 is irradiated 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 used by the image forming unit A1 to form an image on the sheet.

[0018] The original document feeding unit A3 includes a feeding tray 22 and a discharge tray 24, conveys the original documents placed on the feeding tray 22 one by one, passes them over the second platen glass 21, and discharges them to the discharge tray 24. When reading the original documents fed from the original document feeding unit A3 and passing over the second platen glass 21, the reading carriage 18 is pre-stopped 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 that performs processing such as stapling and folding on the sheets conveyed from the image forming device A will be described with reference to FIG. 2. FIG. 2 shows the detailed configuration of the sheet processing device B. The sheet processing device B can stack the sheets received from the receiving portion 26, which is the entrance of the conveyance path 28 connected to the discharge port 16 of the image forming device A, after processing, on the first tray (first stacking tray) 49, the saddle discharge unit 131, and the second tray (second stacking tray) 71, which will be described later. In the present embodiment, the path refers to the entire path through which the sheet is conveyed by a conveyance guide, conveyance rollers, or the like.

[0020] In the illustrated device, the sheets sent to the conveyance path 28 as the first conveyance path are discharged to the first tray 49 after being processed by the processing unit B1, which will be described later, or the sheets conveyed through the conveyance path 28 are discharged to the second tray 71, or are discharged to the saddle discharge unit 131 after being processed by the saddle portion B2, which will be described later. Each device has a control unit, a communication unit, etc., like the blocks showing the control configuration in the entire device shown in FIG. 3, and controls the device accordingly.

[0021] The processing unit B1 as the end binding processing unit is arranged below the path outlet (delivery unit 35) of the conveyance path 28, and assembles a plurality of sheets sequentially delivered from the conveyance path 28 via the delivery unit 35 into a sheet bundle, and can perform a binding process which is an example of a predetermined process on the end of this sheet bundle. The bound sheet bundle is loaded onto the first tray 49 as a loading unit. The sheet or sheet bundle loaded on the first tray 49 abuts against the loading wall 50 on the upstream side in the discharge direction of the sheets on the first tray 49 with its rear end (upstream end), and is loaded along the loading wall 50.

[0022] The first tray 49 is capable of moving up and down with respect to the processing tray 37 described later, and loads the sheet bundle bound by the binding processing mechanism 47 described later. In the present embodiment, the first tray 49 and the second tray 71 are capable of moving up and down by a lifting mechanism (not shown). That is, in the present embodiment, when feeding the sheet to the first tray 49 or the second tray 71 as a loading tray, the first tray 49 and the second tray 71 are moved up and down so as to keep the position of the uppermost sheet on the loading surface of the tray constant with respect to the discharge roller pair 42 and the second discharge roller 207 so that the alignment of the loaded sheets does not deteriorate.

[0023] The saddle part B2 is arranged below the delivery part of the saddle path 32 as the second conveyance path branching vertically downward from the conveyance path 28, and assembles a plurality of sheets sequentially delivered from the conveyance path 28 via the saddle path 32 and the delivery part into a sheet bundle, performs an intermediate binding process, or performs a folding process without performing the intermediate binding process, and discharges it to the saddle discharge unit 131. Hereinafter, each configuration will be described in detail.

[0024] [Housing] As shown in FIG. 2, the sheet processing apparatus B includes a housing 27, a conveyance 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 conveyance path 28, the processing unit B1, and the saddle unit B2 are disposed inside the housing 27. Further, the conveyance path 28 has a sheet receiving portion 26 and a sheet delivery portion 35. The processing unit B1 and the saddle unit B2 process the sheet delivered from the delivery portion 35 of the conveyance path 28. The first tray 49, the saddle discharge unit 131, and the second tray 71 stack the sheets sent from the respective processing units. The illustrated housing 27 is connected to the housing 1 of the image forming apparatus A located on the upstream side in the sheet conveyance direction in the conveyance path 28. Then, the housing 27 and the housing 1 are arranged such that the height from the discharge port 16 of the image forming apparatus A and the installation surface of the receiving portion 26 of the sheet processing apparatus B is substantially the same, and the discharge port 16 and the receiving portion 26 are connected.

[0025] [Sheet Loading Path] The conveyance path 28, which is the sheet loading path, is configured as a substantially straight path that crosses the housing 27 in a substantially horizontal direction, and includes a receiving portion 26 that is continuous with the discharge port (main body discharge port) 16 of the image forming apparatus A, and a delivery portion 35 that is located on the opposite side across the apparatus from the receiving portion 26. In this conveyance path 28, sheet conveyance is possible in a first direction from the receiving portion 26 toward the first discharge path 31, and conveyance is also possible in a second direction from the first discharge path 31 toward the receiving portion 26. Entrance rollers 29, a first conveyance roller 201, a second conveyance roller 202, and a third conveyance roller 203, which are conveyance rollers, are arranged. That is, the entrance rollers 29, the first conveyance roller 201, the second conveyance roller 202, and the third conveyance roller 203 can convey the sheet in the first direction and a second direction opposite to the first direction in the conveyance path, and are arranged in order from the receiving portion 26 side with respect to the first direction.

[0026] The first discharge path 31 is connected to the delivery section 35 of the conveyance path 28, and a first conveyance roller 36 is disposed at this connection section. The sheet delivered from the conveyance path 28 to the first discharge path 31 and discharged from the first discharge path 31 is loaded onto the first tray 49 or guided to the processing unit B1. Note that each of the above-described conveyance rollers may be another member capable of conveying a sheet, such as a conveyance belt.

[0027] [Layout of Sheet Loading Path] As shown in FIG. 2, a saddle path 32, which is a branch path, and an upper conveyance path 30 are connected to the conveyance path 28. The saddle path 32 and the upper conveyance path 30 are arranged in order from the receiving section 26 toward the first discharge path 31 with respect to the first direction. Further, the saddle path 32 branches downward in the vertical direction from the conveyance path 28, and the upper conveyance path 30 branches upward in the vertical direction from the conveyance path 28. A saddle path switching member 33 and an upper conveyance path switching member 34, which are switching members for switching the conveyance direction of the conveyed sheet, are disposed at each branching section between the conveyance path 28 and the saddle path 32 and the upper conveyance path 30.

[0028] [Branch Section of Path] The upper conveyance path switching member 34 is constituted by a switching guide that is movable so as to change the conveyance path so as to convey the sheet carried in from the receiving section 26 to either the first discharge path 31 or the upper conveyance path 30, and is moved by a drive section (not shown) such as an electromagnetic solenoid or a mini motor.

[0029] [Upper Conveyance Path] The upper conveyance path 30 (printout discharge path) for conveying sheets other than those discharged to the first discharge path 31 branches from the conveyance path 28, and a path switching member 34 for guiding the sheet to the upper conveyance path 30 is provided at the path branching portion. Further, the upper conveyance path 30 is provided with a fourth conveyance roller 204, a fifth conveyance roller 205, a sixth conveyance roller 206, and a second discharge roller 207 as conveyance rollers for guiding the sheet to the second tray 71. By these, the sheet guided to the upper conveyance path 30 is discharged from the upper conveyance path discharge port 40 to the second tray 71 (overflow tray).

[0030] The processing unit B1 includes a processing tray 37 as a placement unit for placing the sheets conveyed on the first discharge path 31 on the downstream side of the conveyance path 28 and aligning and stacking the plurality of placed sheets, and a binding mechanism 47 for binding the stacked sheet bundle. Then, the processing unit B1 performs a binding process on the sheet bundle placed on the processing tray 37. The binding mechanism 47 is arranged vertically downward with respect to the conveyance path 28. As shown in FIG. 2, a step is formed in the first discharge path 31, and the processing tray 37 is arranged below the step. Between the first discharge path 31 and the processing tray 37, a first switchback path is provided for changing the conveyance direction in the reverse direction in a state where a part of the sheet is discharged from the discharge port 31a of the first discharge path 31 to the first tray 49 and guiding the sheet onto the processing tray 37.

[0031] Specifically, the first discharge path 31 is provided with an upper conveyance roller 41 and a lower conveyance roller 48 for sandwiching and conveying the sheet. The upper conveyance roller 41 and the lower conveyance roller 48 constitute a pair of discharge rollers 42 as a discharge unit. The upper conveyance roller 41 can come into contact with and separate from the lower conveyance roller 48, and can convey the sheet in a direction toward the first tray 49 and in a direction opposite to this direction in a state where the upper conveyance roller 41 and the lower conveyance roller 48 sandwich the sheet. And it can be conveyed by the upper conveyance roller 41 and the lower conveyance roller 48 toward the processing tray 37 via the first switchback path.

[0032] Further, the upper conveyance roller 41 and the lower conveyance roller 48 (i.e., the discharge roller pair 42) discharge the sheet or the bundle of sheets on the processing tray 37 from the discharge port 31a to the first tray 49 as the stacking tray (stacking portion). The discharge port 31a is a portion opened above the lower conveyance roller 48 of the housing 27. Further, the discharge roller pair 42 discharges the sheet conveyed to the first discharge path 31 without passing through the processing tray 37 from the discharge port 31a to the first tray 49.

[0033] The binding processing mechanism 47 has a rear end regulating portion 47a that abuts against the end portion (rear end) of the sheet to position the sheet. On the processing tray 37, a scraping portion 38 is disposed that conveys the sheet conveyed to the processing tray 37 by the upper conveyance roller 41 and the lower conveyance roller 48 toward the rear end regulating portion 47a. Then, the binding processing mechanism 47 performs a binding process on the end portion of a bundle of sheets placed on the processing tray 37 and composed of a plurality of sheets whose end positions are regulated by the rear end regulating portion 47a. Further, the binding processing mechanism 47 has a sheet bundle carrying-out mechanism that carries out the bundle of sheets to the first tray 49 after performing the binding process on the end portion of the bundle of sheets.

[0034] Note that the binding processing mechanism 47 shown in FIG. 2 supports the sheet sent from the first discharge path 31 so as to straddle between the processing tray 37 and the first tray 49 on the downstream side thereof. That is, the sheet sent from the first discharge path 31 has its front end portion on the uppermost sheet of the first tray 49 on the downstream side and its rear end portion supported on the processing tray 37.

[0035] [Saddle Path] A saddle path 32 for conveying the sheet to the saddle portion B2 described above is connected to the conveyance path 28, and the path branching portion is provided with a saddle path switching member 33 for guiding the sheet to the saddle path 32. The sheet guided to the saddle portion B2 by the saddle path 32 is discharged to a saddle discharge unit 131 via a post-fold path guide 114, a second roller post-path guide 116, a pre-clamp guide 119, and a saddle discharge guide 124 in a substantially horizontal direction after being subjected to middle folding processing and folding processing. In the present embodiment, the saddle discharge guide 124 as a discharge guide portion is used as an auxiliary guide for appropriately loading the sheet onto the saddle discharge unit 131.

[0036] [Control Configuration] The schematic of the control configuration of the image forming system 1000 will be described with reference to FIG. 3. First, the image forming apparatus A includes a control unit 310, an operation unit 302, a conveyance control unit 303, an image processing unit 304, a drive unit 305, and a communication unit 306. The control unit 310 includes a CPU (Central Processing Unit) 311, a ROM (Read Only Memory) 312, and a RAM (Random Access Memory) 313. The CPU 311 controls each unit while reading a program corresponding to the control procedure stored in the ROM 312. Also, work data and input data are stored in the RAM 313, and the CPU 311 controls with reference to the data stored in the RAM 313 based on the above-described program and the like.

[0037] The operation unit 302 is, for example, an operation panel provided in the image forming apparatus A, which is connected to the control unit 310, and an operator performs operations and various settings of the apparatus. The conveyance control unit 303 controls various conveyance rollers and switching members for switching conveyance paths that convey 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 communicably connects the control unit 310 to an external device 301 such as a personal computer and the communication unit 321 of the sheet processing apparatus B.

[0038] The sheet processing apparatus B includes a stacker control unit 330, a conveyance control unit 322, an end binding control unit 323, a discharge processing control unit 324, and a communication unit 321. The stacker control unit 330 has a CPU 331, a ROM 332, and a RAM 333, similar to the control unit 310. The conveyance control unit 322 controls various conveyance rollers for conveying sheets and switching members for switching conveyance paths outside the saddle unit B2 of the sheet processing apparatus B. The end binding control unit 323 controls the processing unit B1. The discharge processing control unit 324 controls the discharge of sheets and various stacking trays on which the discharged sheets are stacked. The communication unit 321 communicably connects the communication unit 306 of the image forming apparatus A and the communication unit 341 of the saddle unit B2 to the stacker control unit 330. Note that the communication between the communication unit 306 and the communication unit 321 may be performed by wired communication or wireless communication.

[0039] The saddle unit B2 includes a saddle control unit 350, a conveyance control unit 342, a middle binding control unit 343, a middle folding control unit 344, an additional folding processing control unit 345, and a communication unit 341. The saddle control unit 350 has a CPU 351, a ROM 352, and a RAM 353, similar to the control unit 310. The conveyance control unit 342 controls various conveyance rollers for conveying sheets and switching members for switching conveyance paths in the saddle unit B2. The middle binding control unit 343 controls the middle binding processing unit 104. The middle folding control unit 344 controls the middle folding mechanism C1. The additional folding processing control unit 345 controls the additional folding processing unit C2. The communication unit 341 communicably connects the communication unit 321 of the sheet processing apparatus B to the saddle control unit 350. In this embodiment, the saddle control unit 350 is configured to communicate 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 may also be used. Also, in this embodiment, the sheet processing apparatus B has a conveyance control unit 322, an end binding control unit 323, a discharge processing control unit 324, a stacker control unit 330, and a saddle control unit 350 for controlling the sheet processing apparatus B, but a configuration in which each unit is controlled by one control unit may also be used.

[0040] [Saddle Unit] The saddle part B2 will be described with reference to FIGS. 2 and 4. The saddle part B2 has a center folding mechanism C1 and an additional folding processing part C2. The center folding mechanism C1 aligns and stacks the sheets sent from the conveyance path 28 into a sheet bundle, performs a binding process on the center part in the conveyance direction of the sheet bundle (the intermediate part in the second conveyance direction, which is the conveyance direction of the saddle path roller 100 as the second conveyance part described later), and performs a center folding process of bending the sheet bundle at the bound position (hereinafter also referred to as "magazine finishing"). The additional folding processing part C2 is arranged on the downstream side in the conveyance direction of the sheet bundle of the center folding mechanism C1 (the downstream side in the first conveyance direction, which is the conveyance direction of the saddle third roller pair 118 as the conveyance part and the first conveyance part described later), and performs a corner folding process of making a fold on the back of the center-folded sheet bundle or an additional folding process (specifically described later) on the sheet bundle. And a saddle discharge unit 131 is arranged on the downstream side in the first conveyance direction of the additional folding processing part C2 to stack the sheet bundle that has been book-bound. It should be noted that it is also possible to align and stack one or more sheets, and only perform a center folding process of bending the center part in the conveyance direction without performing a center binding process, a corner folding process, or an additional folding process.

[0041] [Center folding mechanism] The middle folding processing mechanism C1 includes a tip restricting stopper 109, a middle stapling processing unit (middle stapling staple unit) 104, and a middle folding processing unit 112. It accumulates sheets in a bundle form and performs middle folding processing and middle stapling processing. That is, the sheets conveyed from the conveyance path 28 to the saddle path 32 are conveyed by the saddle path roller 100 as the second conveyance unit to the saddle stack tray 150 as the accumulation unit and the second accumulation unit. The saddle stack tray 150 accumulates a plurality of sheets conveyed in the second conveyance direction by the saddle path roller 100 via the saddle path 32 to form a sheet bundle. The sheet bundle accumulated on the saddle stack tray 150 is positioned at a predetermined position on the saddle stack tray 150 by the tip restricting stopper 109. The middle stapling processing unit 104 performs stapling processing on the central portion (the middle portion in the second conveyance direction) in the conveyance direction of the sheet bundle positioned by the tip restricting stopper 109. The middle folding processing unit 112 has a pushing plate 112a and a pair of folding rollers 113. While pushing the vicinity of the position (the central portion in the conveyance direction of the sheet bundle) where stapling processing is performed by the middle stapling processing unit 104 with the pushing plate 112a, the sheet bundle is conveyed by the pair of folding rollers 113 to fold the sheet bundle and convey it so that the back of the sheet bundle faces the downstream side in the conveyance direction. Incidentally, the middle folding processing unit 112 can also perform middle folding processing on a sheet bundle (or a single sheet) on which middle stapling processing is not performed. Here, the middle folding processing means making a crease near the center of the sheet bundle and folding the sheet bundle in half. The crease formed by the middle folding processing unit 112 does not necessarily have to be at the center of the sheet bundle and may be shifted from the center within the range of component tolerances. Also, the folding position may be changed according to the user's setting.

[0042] The middle stapling processing unit 104 is a mechanism that moves the head unit and the anvil unit along the central portion (line) of the sheet with the sheet bundle sandwiched between the head unit and the anvil unit to perform stapling processing. Also, as shown in FIGS. 2 and 4, the middle folding processing unit 112 adopts a configuration in which the sheet bundle is inserted into the nip of the pair of folding rollers 113 that are in pressure contact with each other by the pushing plate 112a and the sheet bundle is conveyed while being folded by the rotation of the pair of folding rollers 113.

[0043] [Incremental folding processing unit] The incremental folding processing unit C2 performs a corner folding process to form a corner-back shape along the fold line (crease) of the sheet bundle that has been center-folded, or an incremental folding process in which the center-folded sheet bundle is further clamped by a pair of rollers to perform incremental folding on the sheet bundle. The incremental folding processing unit C2 includes a lower clamp unit 120 and an upper clamp unit 121 as a pair of clamp units (clamping units), and a corner folding processing unit (first pressing unit) 134 having a pressing roller 123 as a first roller, and an incremental folding processing unit (second pressing unit) 500 having a pair of incremental folding rollers 501, 502 as a pair of second rollers (see Fig. 20(b) etc. described later). Hereinafter, the case of mainly performing the corner folding process will be described, and the incremental folding process will be described later. Also, in Figs. 2, 4, 7(a) to 9, the illustration of the incremental folding processing unit 500 is omitted.

[0044] The lower clamp unit 120 and the upper clamp unit 121 move relatively along the thickness direction of the sheet bundle conveyed by the saddle third roller pair 118 described later (the direction in which a virtual line connecting the respective rotation axes of the saddle third roller pair 118 extends, or the direction orthogonal to the roller conveyance direction 118c of the saddle third roller pair 118) to clamp and release the clamping of the sheet bundle. The pressing roller 123 presses the back of the sheet bundle by moving along the width direction of the sheet bundle (the direction orthogonal to the conveyance direction of the sheet bundle, the front-back direction in Figs. 2 and 4). Then, the incremental folding processing unit C2 presses the back of the sheet bundle clamped by the lower clamp unit 120 and the upper clamp unit 121 with the back of the sheet bundle protruding downstream with respect to the lower clamp unit 120 and the upper clamp unit 121 in the first conveyance direction by the pressing roller 123 to perform a corner folding process of forming a corner on the back of the sheet bundle. Note that the above-mentioned "corner" includes a curved surface and refers to the boundary between the front cover and the back cover of the sheet bundle, and the boundary between the back cover and the back sheet. Also, the "width direction of the sheet bundle" is the direction along the front-back direction of the image forming apparatus A and the sheet processing apparatus B, and hereinafter may be simply referred to as the "width direction".

[0045] Specifically, in a state where the back of the sheet bundle mid-folded by the mid-folding mechanism C1 protrudes downstream in the first conveyance direction, the lower clamp unit 120 and the upper clamp unit 121 clamp a part of the sheet bundle from both sides in the vertical direction (the thickness direction of the sheet bundle). The pressing roller 123 presses the back of the sheet bundle clamped by the lower clamp unit 120 and the upper clamp unit 121 while moving it along the width direction of the sheet bundle, which is orthogonal to both the conveyance direction of the sheet bundle and the thickness direction of the sheet bundle. In this way, the additional folding processing unit C2 performs a corner-back processing of forming a corner on the back of the sheet bundle. The corner-back processing is a process of forming two streaks on the back of the sheet bundle shown in FIGS. 11(c) and (d) by crushing the back of the sheet bundle shown in FIGS. 11(a) and (b) described later with the pressing roller 123, thereby forming two corners on the back of the sheet bundle. The two corners on the back of the sheet bundle are formed at positions sandwiching the staple pins driven in when being stitched by the mid-stitching processing unit 104 in the thickness direction of the sheet bundle. Also, the two corners formed on the back of the sheet bundle are formed at positions sandwiching the fold line formed during the mid-folding process by the mid-folding processing unit 112.

[0046] Note that between the mid-folding mechanism C1 and the additional folding processing unit C2, a mid-folding conveyance mechanism for conveying and stopping the sheet bundle mid-folded by the mid-folding mechanism C1 to the downstream additional folding processing unit C2 is arranged.

[0047] As described above, the processing unit B1 and the conveyance path 28 are arranged in a substantially horizontal direction, the saddle path 32 for guiding the sheet to the saddle portion B2 is arranged in a substantially vertical direction, and the saddle stack tray 150 for aligning and stacking the sheets is arranged to follow a substantially vertical direction. By arranging the conveyance path 28 along the direction crossing the housing 27 in this way and arranging the saddle path 32 and the saddle portion B2 along a substantially vertical direction, it becomes possible to achieve slimming down by reducing the horizontal width of the apparatus.

[0048] On the downstream side in the conveyance direction of the sheet bundle of the saddle portion B2, a saddle discharge unit 131 is arranged to store the sheet bundle folded in a magazine shape. The illustrated saddle discharge unit 131 is arranged vertically below the first tray 49. This is because, assuming that the usage frequency of the first tray 49 is higher than that of the saddle discharge unit 131, the height position at which it is easy to take out the sheet on the tray is set for the first tray 49 in the device specifications.

[0049] [Configuration of Saddle Portion] Next, each configuration of the center folding processing mechanism C1, the center folding conveyance mechanism C3, and the double folding processing unit C2 that constitute the saddle portion B2 will be described in more detail.

[0050] [Details of Center Folding Processing Mechanism] As shown in FIG. 2, the saddle path switching member 33 is switched so as to convey the sheet to the saddle path 32, thereby guiding the sheet to the center folding processing mechanism C1. In the height direction of the center folding processing mechanism C1, in order from the upper side (upstream side) in the vertical direction which is the inlet side, a saddle inlet roller 101, a sorting beater 102, a rear end presser guide 103, a middle binding processing unit 104, a drawing separation roller 105, a center folding processing unit 112, a first alignment roller 107, a second alignment roller 108, a tip regulating stopper 109, and a tip gripper 110 are arranged.

[0051] The saddle entrance roller 101 further conveys downward the sheet delivered from the saddle path 32 by the saddle path roller 100. The sorting rake 102 gathers the sheet conveyed downward from the saddle entrance roller 101 to the right side in FIG. 2 and stacks the sheets on the saddle stack tray 150. The rear end holding guide 103 holds the rear end of the sheet loaded on the saddle stack tray 150. The middle binding processing unit 104 performs a binding process on the central part in the conveyance direction of the stack of sheets accumulated on the saddle stack tray 150. The retracting and separating roller 105 assists in the conveyance of the sheet conveyed to the saddle stack tray 150, and is a roller that draws this sheet toward the leading edge regulating stopper 109. The retracting and separating roller 105 is arranged so as to be able to contact and separate from the opposing roller 105a.

[0052] The middle folding processing unit 112 includes a pair of folding rollers 113, a pushing plate 112a as a pressing part, and a roller guide 111. The pair of folding rollers 113 forms a fold line in the middle folding process. The pushing plate 112a pushes the sheet into the nip part of the pair of folding rollers 113. The roller guide 111 covers the pair of folding rollers 113. The first alignment roller 107 and the second alignment roller 108 both convey the sheet conveyed to the saddle stack tray 150 and perform an alignment process in the height direction of the sheet. The leading edge regulating stopper 109 determines the position in the height direction of the leading edge of the sheet by hitting against the leading edge (lower end) of the conveyed sheet. The leading edge gripper 110 holds the leading edge (lower end) of the sheet loaded on the leading edge regulating stopper 109.

[0053] The saddle entrance roller 101 and the retracting and separating roller 105 are driven by the same motor. The rear end holding guide 103 is provided at a position facing the sorting rake 102 with respect to the saddle stack tray 150. The middle binding processing unit 104 is arranged on the downstream side of the sorting rake 102 and the rear end holding guide 103 and on the upstream side of the retracting and separating roller 105.

[0054] The sheet conveyed from the saddle path 32 to the saddle part B2 is conveyed by the saddle inlet roller 101 to the tip regulating stopper 109 that has moved to a position according to the size. The drawing-in and separating roller 105 has an auxiliary conveying function for accurately conveying the sheet being conveyed to the tip regulating stopper 109 in the saddle stack tray 150. At this time, in order to prevent the sheet tip from getting caught by the folding roller pair 113 and convey it efficiently, the roller guide 111 partially covers the folding roller pair 113.

[0055] The first alignment roller 107 and the second alignment roller 108 accurately abut the conveyed sheet against the tip regulating stopper 109 and perform alignment processing in the sheet height direction.

[0056] The sorting pusher 102 moves the sheet conveyed to the tip regulating stopper 109 to the rear end pressing guide 103, and presses and holds the rear end (upper end) of the sheet pushed by the rear end pressing guide 103 to prepare for receiving the next sheet. At this time, the rear end pressing guide 103 moves to a position according to the size and waits.

[0057] The tip (lower end) of the sheet bundle formed by stacking a predetermined number of sheets on the saddle stack tray 150 is fixed by being grasped by the tip gripper 110. In this state, the stitching process is performed on the central part in the second conveying direction of the sheet bundle by the intermediate stitching processing unit 104. After the stitching process, the tip regulating stopper 109 is lowered while the tip (lower end) of the sheet bundle is still grasped by the tip gripper 110. At this time, the tip regulating stopper 109 is lowered so that the position pushed into the folding roller pair 113 by the pushing plate 112a becomes the position of 1 / 2 of the sheet size, thereby lowering the sheet bundle from the stitching position.

[0058] When performing the middle folding process, the roller guide 111 is retracted, the fixing of the tip gripper 110 is released, and then the central part of the sheet bundle is pushed into the nip part of the folding roller pair 113 by the pushing plate 112a. Thereby, the sheet bundle is middle-folded.

[0059] The saddle entrance roller 101, the retracting and separating roller 105, the sorting flapper 102, and the rear-end pressing guide 103 are controlled by the conveyance control unit 342 (FIG. 3). Further, the front-end restricting stopper 109, the front-end gripper 110, the intermediate folding processing unit 104, the first aligning roller 107, and the second aligning roller 108 are controlled by the intermediate folding control unit 343 (FIG. 3). Furthermore, the folding roller pair 113 and the pushing plate 112a are controlled by the middle folding control unit 344 (FIG. 3).

[0060] [Middle Folding Conveying Mechanism] The configuration of the middle folding conveying mechanism C3 will be described with reference to FIGS. 2 and 4. The middle folding conveying mechanism C3 is a mechanism that delivers the sheet bundle that has been middle-folded by the middle folding processing mechanism C1 to the additional folding processing unit C2. Specifically, the middle folding conveying mechanism C3 first conveys the middle-folded sheet bundle as it is with the folding roller pair 113 so that the spine of the sheet bundle is located on the downstream side in the conveying direction from the fore edge, and delivers the sheet bundle to the post-folding path guide 114. The post-folding path guide 114 is in a direction that bends downward vertically with respect to the folding roller conveying direction 113c (FIG. 2) along a direction along a perpendicular line (a first virtual line α2 described below, FIG. 4) to a straight line passing through the rotation centers of the respective rollers of the folding roller pair 113 as the first conveying roller pair (a direction that is substantially horizontal here), and is arranged on the downstream side in the conveying direction of the folding roller pair 113.

[0061] Here, as shown in FIG. 4, a first line α1 passing through the rotation centers of the folding roller pair 113 and a line orthogonal to the width direction (the direction orthogonal to the conveying direction of the sheet bundle, the front-back direction in FIGS. 2 and 4) and passing through the nip of the folding roller pair 113 in a state where the sheet bundle is not pinched are defined as the first virtual line α2. In this case, the folding roller pair 113 is arranged such that the first virtual line α2 is parallel to the horizontal direction or inclined upward in the vertical direction to such an extent that it is directed downstream in the conveying direction with respect to the horizontal direction. In the present embodiment, the first virtual line α2 is inclined upward in the vertical direction to such an extent that it is directed downstream in the conveying direction with respect to the horizontal direction. On the other hand, the post-folding path guide 114 extends in a direction inclined with respect to the first virtual line α2, and in the present embodiment, it extends in a substantially horizontal direction.

[0062] The folded rear path guide 114 guides the conveyance of the sheet bundle and guides the sheet bundle to the saddle second roller pair 115 located downstream in the conveyance direction. The saddle second roller conveyance direction 115c, which is the direction along the perpendicular to the straight line passing through the rotation centers of the respective rollers of the saddle second roller pair 115, is arranged along a direction that slopes downward in the vertical direction as it goes downstream in the conveyance direction. The saddle second roller pair 115 is driven by the center folding control unit 344 to convey the sheet bundle.

[0063] The sheet bundle conveyed by the saddle second roller pair 115 is delivered to a second roller rear path guide 116 arranged parallel to the downstream side in the conveyance direction and to the saddle second roller conveyance direction 115c (FIG. 2) and is guided by the second roller rear path guide 116. Further, the second roller rear path guide 116 includes 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 conveyance sensor 117 is arranged above the guide surface of the second roller rear path upper guide 116a in the vertical direction and between the sheet bundle inlet and the sheet bundle outlet. The position of the leading end of the sheet bundle is detected by this saddle conveyance sensor 117.

[0064] The second roller rear path guide 116 guides the conveyance of the sheet and guides it to the saddle third roller pair 118 located downstream in the conveyance direction. The saddle third roller conveyance direction 118c (FIG. 2), which is the direction along the perpendicular (second virtual line β2, FIG. 4, described below) to the straight line passing through the rotation centers of the respective rollers of the saddle third roller pair 118, is arranged along a direction that slopes downward in the vertical direction as it goes downstream in the conveyance direction.

[0065] The saddle third roller pair 118 as the conveying unit and the conveying roller pair drives by the middle folding control unit 344, and sandwiches and conveys a sheet bundle subjected to the middle binding process and the middle folding process so as to be positioned on the downstream side in the conveying direction from the end on the short side of the back of the sheet bundle. That is, the saddle third roller pair 118 conveys the sheet bundle so that the back of the sheet bundle becomes the tip. When the direction in which the saddle third roller pair 118, which is also the first conveying unit, conveys the sheet bundle is defined as the first conveying direction (saddle third roller conveying direction 118c), the saddle path roller 100 as the second conveying unit that conveys the sheet to the middle folding mechanism C1 is located on the upstream side in the first conveying direction from the saddle third roller pair 118. And the saddle path roller 100 conveys the sheet in the second conveying direction different from the first conveying direction on the upstream side in the first conveying direction from the saddle third roller pair 118. Hereinafter, the upstream side and the downstream side in the first conveying direction (saddle third roller conveying direction 118c), which is the direction in which the saddle third roller pair 118 conveys the sheet bundle, may be simply referred to as the "upstream side" and the "downstream side".

[0066] Note that the folding roller pair 113, the saddle second roller pair 115, and the saddle third roller pair 118 are driven by the same motor, and the middle folding control unit 344 controls the driving of these roller pairs by controlling this motor. The saddle third roller pair 118 sandwiches the sheet bundle folded by the middle folding unit 112 and conveys it toward the double folding processing unit C2, and is located immediately upstream of the double folding processing unit C2.

[0067] Here, as shown in FIG. 4, a second line β1 passing through the centers of rotation of the saddle third roller pair 118 and a straight line that is orthogonal to the width direction and passes through the nip of the saddle third roller pair 118 in a state where the sheet bundle is not sandwiched are defined as a second virtual line β2. In this case, the saddle third roller pair 118 is provided such that the second virtual line β2 intersects the first virtual line α2 and is inclined downward in the vertical direction so that the second virtual line β2 is directed downstream in the conveying direction of the folding roller pair 113.

[0068] In other words, the saddle third roller pair 118 is arranged such that the second virtual line β2 inclines downward in the vertical direction as it goes downstream in the conveyance direction with respect to the horizontal direction. That is, in the present embodiment, the second virtual line β2 is inclined with respect to the first virtual line α2. And in the folding roller pair 113, the sheet bundle is conveyed in a direction (folding roller conveyance direction 113c) that inclines upward in the vertical direction as it goes downstream in the conveyance direction with respect to the horizontal direction or the horizontal direction. In contrast, in the saddle third roller pair 118, the sheet bundle is conveyed in a direction (saddle third roller conveyance direction 118c) that inclines downward in the vertical direction as it goes downstream in the conveyance direction with respect to the horizontal direction.

[0069] Therefore, in the case of the present embodiment, the middle folding conveyance path C4 as the third conveyance path for conveying the sheet bundle between the folding roller pair 113 and the saddle third roller pair 118 is bent such that the sheet bundle conveyed by the folding roller pair 113 is delivered to the saddle third roller pair 118. That is, the middle folding conveyance path C4 has a post-folding path guide 114 and a second roller post-path guide 116, and the conveyance path is bent between the post-folding 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-folding path guide 114.

[0070] In this way, by making the conveyance direction of the sheet bundle of the folding roller pair 113 different from the conveyance direction of the sheet bundle of the saddle third roller pair 118 and bending the conveyance path between the post-folding path guide 114 and the post-second-roller path guide 116, the width of the sheet processing apparatus B (the length in the second conveyance direction, the length in the left-right direction in FIG. 2) can be reduced, and the apparatus can be miniaturized. Further, by setting the folding roller conveyance direction 113c, which is the sheet conveyance direction of the saddle third roller pair 118, to be obliquely downward and discharging the sheet bundle downward by the saddle third roller pair 118, the sheet bundle processed in the saddle portion B2 can be discharged to a lower position of the apparatus. As a result, the saddle discharge unit 131 from which the sheet bundle processed in the saddle portion B2 is discharged can be arranged below the apparatus, and the amount by which 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. Note that in the arrangement of the conveyance path guides for the above-described sheet or sheet bundle and the conveyance direction of the sheet or sheet bundle, cases where there are angles with respect to horizontal, vertical, or parallel due to relationships such as tolerances are also included.

[0071] [Details of the double-folding processing unit] The double-folding processing unit C2 will be described with reference to FIGS. 5 to 10 while referring to FIGS. 2 and 4. As described above, it includes a lower clamp unit 120 and an upper clamp unit 121 as a pair of clamp units, and a corner-back processing unit 134 having a pressing roller 123. As shown in FIG. 5, a clamp mechanism C5 having the lower clamp unit 120 and the upper clamp unit 121 has a pre-clamp guide 119. The pre-clamp guide 119 is arranged on the downstream side in the conveyance direction from the saddle third roller pair 118 and along a direction that bends downward in the vertical direction with respect to the saddle third roller conveyance direction 118c, and guides the conveyance of the sheet bundle.

[0072] The pre-clamp guide 119 has a pre-clamp upper guide portion 119a as a first guide portion for guiding the upper surface of the sheet bundle, and a pre-clamp lower guide portion 119b as a second guide portion for guiding the lower surface of the sheet bundle. The pre-clamp upper guide portion 119a and the pre-clamp lower guide portion 119b are integrally formed with a pair of first clamp portions 119c and 119d described later, respectively, and extend further upstream from the upstream end portion in the saddle third roller conveyance direction 118c of the first clamp portions 119c and 119d. Further, the first clamp portions 119c and 119d, the pre-clamp upper guide portion 119a, and the pre-clamp lower guide portion 119b are located at a position separated from the line centered on the saddle third roller conveyance direction 118c by more than 1 / 2 of the thickness of the sheet bundle that can pass into the apparatus (the thickness of the sheet bundle when a center folding process is performed on the thickest sheet bundle that can be conveyed in the apparatus) in the thickness direction at the receiving positions of the lower clamp unit 120 and the upper clamp unit 121 described later. That is, the interval between the pre-clamp upper guide portion 119a and the pre-clamp lower guide portion 119b is larger than the maximum thickness of the sheet bundle that can be processed by the sheet processing apparatus B (the maximum thickness of the sheet bundle that can be center-folded by the center folding mechanism C1). Note that at least one of the pre-clamp upper guide portion 119a and the pre-clamp lower guide portion 119b may be omitted.

[0073] The lower clamp unit 120 and the upper clamp unit 121 as a pair of clamp units move relatively along the thickness direction of the sheet bundle conveyed by the saddle third roller pair 118 to clamp and release the clamping of the sheet bundle. That is, the lower clamp unit 120 and the upper clamp unit 121 are relatively movable between a receiving position where they can receive the sheet bundle conveyed from the saddle third roller pair 118 and a clamping position where they clamp the sheet bundle. Then, the lower clamp unit 120 and the upper clamp unit 121 move from the receiving position to the clamping position to clamp a part of the sheet bundle from both sides in the thickness direction of the sheet bundle. That is, the lower clamp unit 120 and the upper clamp unit 121 clamp the sheet bundle.

[0074] The upper clamp unit 121 and the lower clamp unit 120 include a pair of first clamp portions 119c and 119d, and a pair of second clamp portions 142 and 143 located on the downstream side in the conveyance direction from the pair of first clamp portions 119c and 119d. In the case of the present embodiment, the lower clamp unit 120 as one of the clamp units is fixed, and the upper clamp unit 121 as the other clamp unit is movable. That is, the upper clamp unit 121 moves in a direction approaching the lower clamp unit 120 to clamp the sheet bundle. However, the upper clamp unit 121 may be fixed, the lower clamp unit 120 may be movable, or both may be movable. In any case, during the corner folding process, the upper clamp surface (upper clamp pressing portion) 142a, which is the surface of the second clamp portion 142 of the upper clamp unit 121 facing the lower clamp unit 120, and the lower clamp surface (lower clamp pressing portion) 143a, which is the surface of the second clamp portion 143 of the lower clamp unit 120 facing the upper clamp unit 121, clamp the sheet bundle (see FIGS. 5 and 11(a) to (d)).

[0075] The lower clamp surface 143a of the lower clamp unit 120 and the upper clamp surface 142a of the upper clamp unit 121 are each parallel to the opposing surfaces of the pair of first clamp portions 119c and 119d. Also, the pair of first clamp portions 119c and 119d and the pair of second clamp portions 142 and 143 are arranged on the downstream side in the conveyance direction of the sheet bundle of the pre-clamp guide 119. Then, the sheet bundle conveyed while being guided by the pre-clamp guide 119 is further guided by the pair of first clamp portions 119c and 119d and the pair of second clamp portions 142 and 143 to convey a predetermined amount. Note that the pre-clamp lower guide portion 119b is fixed to the lower clamp unit 120, and the pre-clamp upper guide portion 119a is fixed to the upper clamp unit 121. In the present embodiment, the pre-clamp upper guide portion 119a moves in a substantially vertical direction (the thickness direction of the sheet bundle) together with the upper clamp unit 121.

[0076] [Corner folding unit] Next, with reference to FIGS. 5 to 10, the internal configuration of the corner-back processing unit 134 will be described. The corner-back processing unit 134 presses the back of the sheet bundle protruding downstream in the conveyance 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 in a state where the sheet bundle is clamped by the lower clamp unit 120 and the upper clamp unit 121. Further, the corner-back processing unit 134 performs a corner-back process of forming a corner on the back of the sheet bundle by moving in the width direction of the sheet bundle while pressing the back of the sheet bundle toward the lower clamp unit 120 and the upper clamp unit 121.

[0077] As a configuration for supporting and moving the pressing roller (corner-back processing roller) 123 as the first roller, the corner-back processing unit 134 includes a unit frame 147, roller pressing portions 138a and 138b, pressing springs 145a and 145b, an upper movement restricting portion 139, and a lower movement restricting portion 140. As shown in FIGS. 5 and 10, the pressing roller 123 is arranged such that the outer peripheral surface contacts the downstream end surfaces of the lower clamp unit 120 and the upper clamp unit 121, respectively. Further, as shown in FIG. 6(b), a roller shaft 141 is arranged on the inner diameter side of the pressing roller 123, and the pressing roller 123 is rotatable with respect to the roller shaft 141.

[0078] As shown in FIGS. 6(a) and 6(b), the unit frame 147 includes a pair of side plates 147a arranged on both sides of the pressing roller 123, a rear side plate 147b arranged on the left side of the pressing roller 123 on the downstream side in the first conveyance direction (FIG. 6(b)), and upper side plates 147c and lower side plates 147d arranged on both sides in the rotation axis direction of the pressing roller 123 and provided so as to bend from both end portions of the rear side plate 147b. With such a configuration, the unit frame 147 accommodates the pressing roller 123 inside each side plate and exposes the pressing roller 123 on the upstream side in the first conveyance direction.

[0079] In this embodiment, the rear side plate 147b, the upper side plate 147c, and the lower side plate 147d are integrally formed, and as shown in Fig. 6(b), they have a substantially U-shaped cross section. Note that these may be separate, or may be integrally formed with the pair of side plates 147a. Both ends of the roller shaft 141 of the pressing roller 123 are rotatably supported by the upper side plate 147c and the lower side plate 147d, respectively. Further, the upper side plate 147c and the lower side plate 147d extend upstream in the first conveyance direction from the pressing roller 123, and an upper movement restricting portion 139 and a lower movement restricting portion 140 are supported at the tip portions thereof, respectively.

[0080] That is, the upper movement restricting portion 139 is provided at the tip of a support shaft 139a that is fixed to the upper side plate 147c and extends downward from the upper side plate 147c. Further, the lower movement restricting portion 140 is provided at the tip of a support shaft 140a that is fixed to the lower side plate 147d and extends upward from the lower side plate 147d. Also, the upper movement restricting portion 139 is a roller rotatably supported at the tip of the support shaft 139a, and the lower movement restricting portion 140 is a roller rotatably supported at the tip of the support shaft 140a. Note that in this embodiment, two lower movement restricting portions 140 are arranged side by side, but one may be sufficient. Also, two upper movement restricting portions 139 may be provided. The upper movement restricting portion 139 and the lower movement restricting portion 140 are located on both sides of the pressing roller 123 in the rotational axis direction of the roller shaft 141.

[0081] Roller pressing portions 138a and 138b are connected to the roller shaft 141 on the outer side in the roller thickness direction of the pressing roller 123 and downstream in the conveyance direction, respectively. Pressure springs 145a and 145b are disposed between the roller pressing portions 138a and 138b and the rear side plate 147b of the unit frame 147, and the roller shaft 141 is biased by the pressure springs 145a and 145b. Since the roller shaft 141 is configured to be movable in the conveyance direction, the pressing force with which the pressing roller 123 presses the back of the sheet bundle by the biasing force of the pressure springs 145a and 145b changes in accordance with changes in the protruding amounts from the lower clamp unit 120 and the upper clamp unit 121 at the back of the sheet bundle, which will be described later.

[0082] Further, since the pressing roller 123 is biased by the pressing springs 145a and 145b via the roller shaft 141, it is pressed against the lower clamp unit 120 and the upper clamp unit 121. On the other hand, on the opposite side sandwiching the pressing roller 123 between the lower clamp unit 120 and the upper clamp unit 121, an upper movement restricting portion 139 and a lower movement restricting portion 140 are arranged so as to face the lower clamp unit 120 and the upper clamp unit 121 respectively (FIG. 5). That is, with respect to the conveyance direction of the sheet bundle (first conveyance direction), on the upstream side of the lower clamp unit 120 and the upper clamp unit 121, the upper movement restricting portion 139 is arranged with respect to the upper clamp unit 121, and the lower movement restricting portion 140 is arranged with respect to the lower clamp unit 120 respectively.

[0083] As shown in FIGS. 9 and 10, the upstream end face 120a of the lower clamp unit 120 is in contact with the lower movement restricting portion 140. Further, the upstream end face 121a of the upper clamp unit 121 is in contact with the upper movement restricting portion 139. In the present embodiment, the lower movement restricting portion 140 and the upper movement restricting portion 139 are rollers having a rotation axis in the width direction of the sheet bundle and the direction orthogonal to the conveyance direction of the sheet bundle (the vertical direction in FIG. 10, substantially the vertical direction in the present embodiment), and rotate while being in contact with the end faces 120a and 121a. Thereby, the pressing force applied from the pressing roller 123 to the lower clamp unit 120 and the upper clamp unit 121 restricts the lower clamp unit 120 and the upper clamp unit 121 from moving upstream.

[0084] When the saddle conveyance sensor 117 detects the leading edge of the sheet bundle conveyed by the saddle third roller pair 118, the increment folding process control unit 345 counts the conveyance amount and stops after conveying a predetermined conveyance amount. Specifically, as shown in FIG. 11(a) described later, the saddle of the folded sheet bundle is stopped in a state where it protrudes downstream in the conveyance direction from the upper clamp unit 121 and the lower clamp unit 120. In the present embodiment, in the square-back process, by controlling the conveyance amount of the sheet bundle by the saddle third roller pair 118, the protruding amount of the saddle of the sheet bundle from the upper clamp unit 121 and the lower clamp unit 120 is adjusted.

[0085] [Upper clamp unit and lower clamp unit] The upper clamp unit 121 moves from the receiving position for receiving the sheet bundle to the clamp holding position (clamping position) for holding the sheet bundle, thereby pressing the sheet bundle between itself and the lower clamp unit 120, and holding the sheet bundle by the upper clamp surface 142a and the lower clamp surface 143a. At this time, as shown in FIG. 11(b) described later, the leading edge of the sheet bundle protrudes by a predetermined protruding amount P1 from the end faces 120c and 121b on the downstream side in the conveyance direction of the second clamp portion 143 of the lower clamp unit 120 and the second clamp portion 142 of the upper clamp unit 121 after clamp holding.

[0086] The upper clamp unit 121 operates by driving a clamp drive motor 132 (Figs. 7(a) and (b)) by an accordion processing control unit 345. As shown in Figs. 7(a) and (b), the accordion processing unit C2 further transmits the drive transmitted by a clamp drive train 133 composed of a pulley, a belt, and further a gear train to a clamp drive link 122, thereby moving the upper clamp unit 121 connected to the clamp drive link 122 in the sheet bundle thickness direction. A plurality of second springs 802 as clamp springs for pressing the sheet bundle are built in between the clamp drive link 122 and the upper clamp unit 121. With the movement amount of the clamp drive link 122 remaining constant, the compression amount of the second spring 802 changes according to the thickness of the sheet bundle, so that the pressing force also changes. The aforementioned clamp holding position also changes according to the thickness of the sheet bundle. Also, the clamp holding position (clamping position) is different between the case of performing a corner folding process and the case of performing an accordion process, as will be described in detail later. The upper clamp unit 121 is movable to a first position and a second position closer to the lower clamp unit 120 than the first position. Then, in the corner folding process, the upper clamp unit 121 is moved to the second position, and in the accordion process, the upper clamp unit 121 is moved to the first position.

[0087] [Accordion processing unit] As shown in Fig. 11(c) to be described later, the accordion processing unit C2 performs a corner folding process on a sheet bundle held in a state of protruding by a predetermined protruding amount P1 from end faces 120c and 121b between the lower clamp unit 120 and the upper clamp unit 121, by pressing the back of the sheet bundle while scanning in the width direction of the sheet bundle by a pressing roller 123 arranged on the downstream side in the conveyance direction.

[0088] During the corner back processing, the doubling processing control unit 345 operates the drive motor 135 (Fig. 7(b)) to move the doubling processing unit 500 (see Fig. 12 etc. described later). The corner back processing unit 134 is connected to the doubling processing unit 500 as described later, and is moved by the drive motor 135 via the doubling processing unit 500. The doubling processing unit 500 is connected to the drive belt 137 shown in Fig. 8. The drive belt 137 is arranged in the width direction of the sheet bundle. Also, the doubling processing unit 500 and the corner back processing unit 134 are movable in the width direction of the sheet bundle along the guide rail 120b shown in Fig. 9 described later. The drive belt 137 is rotated by power transmitted from the drive motor 135 via the drive train 136 (Fig. 7(b)) composed of a gear train. As a result, although details will be described later, the doubling processing unit 500 can be scanned alone in the width direction of the sheet bundle, and further, the corner back processing unit 134 can be scanned together with the doubling processing unit 500 in the width direction of the sheet bundle.

[0089] That is, in the present embodiment, there is a drive mechanism 135a for moving the connected corner back processing unit 134 and doubling processing unit 500 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 doubling processing unit 500 along the width direction of the sheet bundle, and when the corner back processing unit 134 is connected to the doubling processing unit 500 by a connection mechanism 600 (see Fig. 14 etc. described later), it moves the corner back processing unit 134 and the doubling processing unit 500 along the width direction of the sheet bundle.

[0090] Note that the home position of the corner folding processing unit 134 is provided on the front side of the sheet processing apparatus B (the right side (F side) in FIG. 12 described later). For example, the corner folding processing unit 500 connected to the corner folding processing unit 134 in the home position is moved to the rear side (the left side (R side) in FIG. 12) to perform corner folding processing on the sheet bundle. A sensor (not shown) is provided at the home position of the corner folding processing unit 134, and it is possible to detect the position of the corner folding processing unit 134. However, the home position of the corner folding processing unit 134 may be set on the rear side, and the scanning of the corner folding processing unit 134 in the width direction may be performed from the rear side to the front side. In addition, when the length of the sheet bundle in the width direction (F-R direction) is short (in the case of a sheet bundle composed of small-sized sheets), etc., after moving the corner folding processing unit 134 from the rear side to the front side to perform corner folding processing on the first sheet bundle, the corner folding processing unit 134 may be moved from the front side to the rear side to perform corner folding processing on the second sheet bundle. In this case, home positions may be provided on both the front side and the rear side of the sheet processing apparatus B, and home position sensors may be provided on both sides.

[0091] Also, in one corner folding process, the pressing roller 123 is moved in one direction from the front side to the rear side or from the rear side to the front side, but the pressing roller 123 may be reciprocally moved in one corner folding process. For example, in one corner folding process, whether to move the pressing roller 123 in one direction or reciprocally may be set according to the number of sheets and the type of sheets included in the sheet bundle. When setting this, it may be automatically performed on the control unit side, or an operator such as a user or a service technician may set it. Furthermore, in one corner folding process, it may be possible for the operator to arbitrarily set whether to move the pressing roller 123 in one direction or reciprocally.

[0092] As shown in FIGS. 9 and 10, the lower clamp unit 120 has a guide rail 120b formed along the width direction of the sheet bundle. When the corner folding unit 134 moves in the width direction of the sheet bundle, the lower movement restricting portion 140 moves along the guide rail 120b while engaging with the guide rail 120b. The guide rail 120b is formed in a substantially U-shaped cross section by combining a plurality of members as shown in FIG. 10, and is formed so that a part of the roller-shaped lower movement restricting portion 140 can enter. The lower surface on the outer diameter side of the lower movement restricting portion 140 is engaged with the lower surface of the guide rail 120b, and the outer peripheral surface of the lower movement restricting portion 140 is in contact with the end surface 120a. Thereby, the movement in the sheet bundle thickness direction when the corner folding unit 134 moves is restricted. Note that the guide rail 120b may be a groove formed in a member on the upstream side in the conveyance direction of the lower clamp unit 120.

[0093] After the corner folding process is completed, as described later, by operating the drive motor 135 (FIG. 7(b)), the corner folding unit 134 is moved in the width direction via the double folding processing unit 500, and the connection between the double folding processing unit 500 and the corner folding unit 134 is released, and the double folding processing unit 500 is moved alone. Thereby, the corner folding unit 134 and the double folding processing unit 500 are retracted from the conveyance path of the sheet bundle. Further, by operating the clamp drive motor 132 (FIGS. 7(a) and 7(b)), the upper clamp unit 121 is moved in a direction away from the sheet bundle (FIG. 11(d) described later). Thereby, it becomes possible to convey the sheet bundle further downstream. Note that it is also possible to discharge the sheet bundle without performing the above-described corner folding process and the double folding process described later.

[0094] [Discharge unit] As shown in FIG. 2, the sheet bundle that has passed through the saddle portion B2 is conveyed toward a saddle discharge guide 124 that is disposed further downstream in the first conveyance direction than the pressing roller 123 by the saddle third roller pair 118. The saddle discharge guide 124 is swingably supported about a first fulcrum 124b having a rotation axis parallel to the rotation axis of each roller of the saddle third roller pair 118. The first fulcrum 124b is located above a line extending in the conveyance direction of the sheet bundle (the first conveyance direction, the saddle third roller conveyance direction 118c) by the saddle third roller pair 118. And the saddle discharge guide 124 is arranged so as to hang vertically downward from the first fulcrum 124b.

[0095] Also, on the side surface of the saddle discharge guide 124 on the upstream side in the first conveyance direction, it is inclined so as to face the upstream side in the first conveyance direction from the first fulcrum 124b toward the intermediate portion 124a with respect to the vertical direction. Also, on the side surface of the saddle discharge guide 124 on the upstream side in the first conveyance direction, it is inclined so as to face the downstream side in the first conveyance direction from the intermediate portion 124a toward the lower end with respect to the vertical direction. That is, the side surface of the saddle discharge guide 124 on the upstream side in the first conveyance direction is formed to bend such that the intermediate portion 124a in the vertical direction protrudes more upstream in the first conveyance direction than the other portions. And a guide surface 124d is provided between the intermediate portion 124a and the lower end on the side surface of the saddle discharge guide 124 on the upstream side in the first conveyance direction.

[0096] The guide surface 124d is located below a line extending the above-described saddle third roller conveyance direction 118c, contacts the sheet bundle conveyed by the saddle third roller pair 118, and guides this sheet bundle downward. The saddle discharge guide 124 is rotatable about the first fulcrum 124b when the sheet bundle contacts the guide surface 124d. Note that depending on the rigidity of the sheet bundle, contact with the guide surface 124d of the saddle discharge guide 124 may not occur, and even when contact occurs, the amount of rotation changes depending on the rigidity, so the saddle discharge guide 124 does not necessarily rotate.

[0097] Further, a second fulcrum 124c is provided at the lower end of the saddle discharge guide 124, and a saddle discharge roller 125, which will be described later, is connected so as to be rotatable about the second fulcrum 124c. The second fulcrum 124c is located below the guide surface 124d and has a rotation axis parallel to the rotation axis of the first fulcrum 124b.

[0098] When the sheet bundle is continuously conveyed by the saddle third roller pair 118, it is delivered to a saddle discharge unit 131 that is arranged on the downstream side in the first conveyance direction with respect to the angular back processing unit 134 and on the lower side in the vertical direction with respect to the saddle discharge guide 124. The saddle discharge unit 131 includes 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.

[0099] The saddle discharge upstream belt 127 is located below the guide surface 124d of the saddle discharge guide 124 and conveys the sheet bundle guided downward by the guide surface 124d while guiding it further downstream. The saddle discharge upstream belt 127 is inclined so as to go downward in the vertical direction as it goes downstream in the conveyance direction. The saddle discharge downstream belt 129 as a sheet bundle discharge part receives the sheet bundle conveyed from the saddle discharge upstream belt 127 and conveys it while guiding it further downstream. The saddle discharge downstream belt 129 is inclined so as to go upward in the vertical direction as it goes downstream in the conveyance direction. For this reason, the sheet bundle guided to the saddle discharge upstream belt 127 by the guide surface 124d is conveyed in a direction inclined downward in the vertical direction by the saddle discharge upstream belt 127 and then conveyed in a direction inclined upward in the vertical direction by the saddle discharge downstream belt 129.

[0100] Also, a saddle discharge upstream sensor 128 for detecting the sheet bundle on the upstream side is arranged on the upstream side within the conveyance possible region of the saddle discharge upstream belt 127, and a saddle discharge downstream sensor 130 for detecting the sheet bundle on the downstream side is arranged on the upstream side within the conveyance possible region of the saddle discharge downstream belt 129.

[0101] The stack of sheets delivered to the saddle discharge unit 131 is guided and conveyed by the saddle discharge upstream belt 127 and the saddle discharge downstream belt 129, and then the stack of sheets is loaded. The saddle discharge upstream belt 127 sandwiches the stack of sheets at the nip point between the saddle discharge roller 125 described above on the downstream side in the conveyance direction. The stack of sheets existing on the saddle discharge upstream belt 127 is configured to suppress the opening on the opening side (the small opening side) at this nip point. The position of this nip point can be changed with the second fulcrum 124c as a fulcrum according to the thickness of the stack of sheets.

[0102] When processing the subsequent stack of sheets, the preceding stack of sheets is conveyed upstream in the conveyance direction by the saddle discharge upstream belt 127, and stops with a predetermined conveyance amount after being detected by the saddle discharge upstream sensor 128 and the saddle discharge downstream sensor 130. This conveyance amount is a position where the opening on the opening side of the preceding stack of sheets can be suppressed at the nip point between the saddle discharge roller 125, and has a positional relationship such that it contacts the upper surface of the preceding stack of sheets when discharging the subsequent stack of sheets. That is, in the present embodiment, in the saddle discharge unit 131, the subsequent stack of sheets is stacked on the preceding stack of sheets (so-called, in a roofing tile shape).

[0103] In this way, the saddle discharge unit 131 discharges the subsequent stack of sheets onto the upper surface of the preceding stack of sheets without entering the opening of the preceding stack of sheets, so that no problems such as snagging, curling, or extrusion occur to the preceding stack of sheets, and it is stably stacked in a roofing tile shape. That is, by appropriately changing the above-mentioned conveyance amount according to the size of the stack of sheets, the subsequent stack of sheets can be stably stacked on the preceding stack of sheets.

[0104] The saddle discharge port 126 is arranged on the downstream side in the first conveyance direction from the saddle discharge guide 124 and between the saddle discharge upstream belt 127 and the saddle discharge downstream belt 129. The stack of sheets conveyed to the saddle discharge unit 131 is discharged to the outside of the sheet processing apparatus B by passing through the saddle discharge port 126, making it easier for the user to access the discharged stack of sheets.

[0105] In addition, when there is another device on the downstream side of the saddle discharge unit 131, it is also possible to transfer the sheet bundle to the downstream device by continuously conveying it without stacking. Further, in the present embodiment, a discharge cover 151 as a cover member is provided outside the saddle discharge port 126. The discharge cover 151 is arranged so as not to prevent the sheet bundle from being discharged from the saddle discharge port 126, and is arranged so that an operator such as a user cannot access the inside of the device through the saddle discharge port 126.

[0106] [Control of the corner folding process] Next, the control of the corner folding process of the present embodiment will be described with reference to FIGS. 11(a) to (d). As described above, the additional folding processing unit C2 performs a corner folding process of forming a corner on the back of the sheet bundle subjected to the middle binding process and the middle folding process. Hereinafter, the control for performing the corner folding process may be referred to as the corner folding process mode, and the control for performing the additional folding process may be referred to as the additional folding process mode. Further, the middle folding control unit 344 shown in FIG. 3 controls each conveyance roller pair of the folding roller pair 113, the saddle second roller pair 115, and the saddle third roller pair 118 with the same drive.

[0107] The corner folding process mode will be described. The corner folding process mode is a mode in which the pressing 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 middle folding control unit 344 uses the detection of the leading end of the sheet bundle Sb by the saddle conveyance sensor 117 as a trigger to convey the middle-folded sheet bundle Sb between the upper clamp unit 121 and the lower clamp unit 120 in a separated state. Then, as shown in FIG. 11(a), the middle folding control unit 344 stops the conveyance of the sheet bundle Sb in a state where the back Ssp of the sheet bundle Sb protrudes further downstream in the first conveyance direction than the end faces 121b and 120c on the downstream side in the first conveyance direction of the upper clamp unit 121 and the lower clamp unit 120.

[0108] In this state, the double-fold processing control unit 345 drives the clamp drive motor 132 (Figs. 7(a) and (b)) to move the upper clamp unit 121 toward the lower clamp unit 120, and as shown in Fig. 11(b), the sheet bundle Sb is clamped by the upper clamp unit 121 and the lower clamp unit 120. At this time, the back Ssp of the sheet bundle Sb protrudes by P1 downstream of the end faces 121b and 120c on the downstream side in the first conveyance direction of the upper clamp unit 121 and the lower clamp unit 120.

[0109] Next, the double-fold processing control unit 345 operates the drive motor 135 (Fig. 7(b)) to move the corner-back processing unit 134 in the width direction of the sheet bundle Sb via the double-fold processing unit 500. At this time, as shown in Fig. 11(c), the pressing roller 123 of the corner-back processing unit 134 moves in the width direction while pressing the back Ssp of the sheet bundle Sb, so that the corner-back processing is performed on the back Ssp of the sheet bundle Sb. Thereafter, as shown in Fig. 11(d), the double-fold processing control unit 345 drives the clamp drive motor 132 (Figs. 7(a) and (b)) to separate the upper clamp unit 121 from the lower clamp unit 120 and release the clamping of the sheet bundle Sb. In the first mode, the corner-back processing is completed up to this point, and the discharge operation of the sheet bundle Sb described above is performed.

[0110] Incidentally, as described above, in the corner-back process, since the back of the sheet bundle is strongly pressed vertically by the pressing roller 123, it is necessary to perform an intermediate binding process on the sheet bundle before performing the corner-back process. This is because if the corner-back process is performed on a sheet bundle that has not been subjected to the intermediate binding process, the sheets inside the sheet bundle will shift due to the pressing force of the pressing roller 123. On the other hand, in the additional folding process described later, since only the back of the sheet bundle is clamped by the pair of additional folding rollers 501 and 502, it may be performed on the sheet bundle that has been subjected to the middle folding process without performing the binding process. That is, the sheet processing apparatus B of the present embodiment is a sheet bundle formed by bundling sheets on which an image has been formed by the image forming unit 3, and performs an additional folding process on the sheet bundle that has been subjected to the middle folding process or the sheet bundle that has been subjected to the intermediate binding process and the middle folding process, and performs a corner-back process on the sheet bundle that has been subjected to the intermediate binding process and the middle folding process.

[0111] [Moving Configuration of Additional Folding Processing Unit and Corner-Back Processing Unit] Next, the moving configurations of the additional folding processing unit 500 and the corner-back processing unit 134 will be described with reference to FIGS. 12 to 19(b). As described above, the sheet bundle Sb on which the corner-back process has been executed by the corner-back processing unit 134 has corners formed on the back portion, and the opening of the sheet bundle is suppressed after being discharged. On the other hand, even when the corner-back process is not performed, that is, when a product without corners on the back is desired, it is required to suppress the opening of the sheet bundle in order to suppress the poor stacking of the sheet bundle after the sheet bundle is discharged. For this reason, in the sheet processing apparatus B of the present embodiment, in addition to the corner-back processing unit 134, an additional folding processing unit 500 that performs additional folding on the sheet bundle is provided. The additional folding processing unit 500 performs a pressing process on the fold of the sheet bundle by moving in the width direction of the sheet bundle while clamping the fold of the sheet bundle. By providing the additional folding processing unit 500 in this way, even when the corner-back process is not performed, the opening of the sheet bundle that has been subjected to the middle folding process or the sheet bundle that has been subjected to the intermediate binding process and the middle folding process can be more effectively suppressed.

[0112] Here, the product without corner folding is a product that has not received an instruction from the user to perform corner folding, such as a middle folding process, a middle binding process, or a product that has been subjected to a middle folding process, or a product on which corner folding cannot be performed. For example, it is a product in the case where a middle folding process, a middle binding process, and a middle folding process are performed with a number of sheets less than the lower limit number of sheets (for example, 5 sheets) of a sheet bundle on which corner folding can be executed. When such a product is desired, for example, when middle folding 4 sheets of a 100 g / m 2 sheet, even if the basis weight of the sheet is large, corner folding cannot be performed on a sheet bundle with a small number of sheets, but by performing an additional folding process as in this embodiment, the opening of the sheet bundle can be suppressed.

[0113] The additional folding process unit 500 has a pair of additional folding rollers 501 and 502 that perform an additional folding process of sandwiching a sheet bundle that protrudes downstream in the conveyance direction (downstream of the saddle third roller conveyance direction 118c (FIG. 4)) from the lower clamp unit 120 and the upper clamp unit 121 while moving along the width direction of the sheet bundle in a state where the sheet bundle is sandwiched by the lower clamp unit 120 and the upper clamp unit 121.

[0114] Similar to the corner folding process unit 134, the additional folding process unit 500 is disposed downstream in the conveyance direction from the lower clamp unit 120 and the upper clamp unit 121, and when performing the additional folding process, it moves along the direction of the sheet bundle in the same manner as the corner folding process unit 134. That is, in this embodiment, it is possible to selectively execute a corner folding process and an additional folding process on the sheet bundle sandwiched by the lower clamp unit 120 and the upper clamp unit 121. And in this embodiment, as described above, the additional folding process unit 500 is configured to move in the width direction by operating the drive motor 135 (FIG. 7(b)), and by connecting the corner folding process unit 134 to the additional folding process unit 500, the drive of the drive motor 135 enables the movement of both units in the width direction.

[0115] Also, in the present embodiment, although details will be described later, in order to perform two processes of the angled-back process and the additional folding process, the position where the pair of additional folding rollers 501 and 502 sandwich the sheet bundle during the additional folding process is downstream in the conveyance direction from the position where the surface of the pressing roller 123 contacts the back of the sheet bundle during the angled-back process. Thereby, even when the folding unit 500 moves together with the angled-back unit 134 during the angled-back process, the sheet bundle being pressed by the pressing roller 123 does not interfere with the additional folding rollers 501 and 502. Further, when performing the additional folding process, by releasing the connection between the additional folding unit 500 and the angled-back unit 134 and moving the additional folding unit 500 alone, the pressing roller 123 does not interfere with the sheet bundle being additionally folded. Hereinafter, the connection and disconnection configuration between the additional folding unit 500 and the angled-back unit 134 will be described in detail.

[0116] [Linkage mechanism] First, the linkage mechanism 600 between the additional folding unit 500 and the angled-back unit 134 will be described with reference to FIGS. 12 to 17(b). FIG. 12 shows a state in which the connection between the angled-back unit 134 and the additional folding unit 500 is released, and the angled-back unit 134 and the additional folding unit 500 are in their home positions. In the present embodiment, within the movement range in the width direction of both units, the home position of the angled-back unit 134 is set as the end on the F side (front side), and the home position of the additional folding unit 500 is set as the end on the R side (rear side).

[0117] That is, the home position of the corner folding processing unit 134 is a position deviated in the width direction of the sheet bundle from the passing area through which the largest-sized sheet bundle conveyed downstream in the conveyance direction of the lower clamp unit 120 and the upper clamp unit 121 passes. In the present embodiment, it is a position deviated to the F side from the passing area. On the other hand, the home position of the additional folding processing unit 500 is a position deviated from the passing area in the width direction of the sheet bundle and is on the opposite side of the home position of the corner folding processing unit 134. In the present embodiment, the home position of the additional folding processing unit 500 is set as a position deviated to the R side from the passing area.

[0118] In this way, in the present embodiment, the corner folding processing unit 134 and the additional folding processing unit 500 are positioned on the F side and the R side with respect to the area through which the largest-sized sheet bundle passes in the home position, respectively. For this reason, in a state where both units are in the home position, the sheet bundle can be discharged to the downstream side in the conveyance direction from between the lower clamp unit 120 and the upper clamp unit 121. Note that the home position of the corner folding processing unit 134 may be on the R side and the home position of the additional folding processing unit 500 may be on the F side. Also, if the sheet bundle can be discharged from between the lower clamp unit 120 and the upper clamp unit 121, the home positions of both units may be on the R side or the F side.

[0119] FIG. 13 is a perspective view of the additional folding processing unit 500 in the home position as viewed from the F side. FIG. 14 is a perspective view of the corner folding processing unit 134, the connection mechanism 600, and the connection release mechanism 700 in the home position as viewed from the R side. As shown in FIG. 13, the additional folding processing unit 500 has engagement pins 503 and 504 as the first engagement portions. The engagement pins 503 and 504 are provided on the F side of the additional folding rollers 501 and 502 of the additional folding processing unit 500.

[0120] On one side, the corner back processing unit 134 supports a connecting mechanism 600 that connects the corner back processing unit 134 and the double folding processing unit 500. The connecting mechanism 600 has hooks 601 and 602 as second engaging portions that can engage with the engaging pins 503 and 504. The hook 601 can engage with the engaging pin 503, and the hook 602 can engage with the engaging pin 504. Note that the first engaging portion and the second engaging portion are not limited to pins and hooks, and other configurations may be used as long as they can be disconnected by the disconnection mechanism 700 described later. For example, the first engaging portion may be a member with a hole or groove that can engage with a hook instead of a pin. Also, the second engaging portion may be a rod-shaped member or a plate-shaped member such as a pin instead of a hook. In this case, the rod-shaped member or the plate-shaped member can engage with the R-side surface of the pin when the first engaging portion is a pin and can be retracted from the engaging position, or can enter and retract from the hole or groove when the first engaging portion is a member with a hole or groove formed therein.

[0121] Further, the connecting mechanism 600 is provided with a link 603 that connects the hook 601 and the hook 602 and rotates them integrally. A spring 604 is engaged with the hook 602, and biases the hook 602 so that the hook 602 is located at the connecting position. Since the hook 601 is connected to the hook 602 by the link 603, the hook 601 is also located at the connecting position by the biasing force of the spring 604. As shown in FIGS. 17(a) and (b) described later, the connecting position is the position where the hooks 601 and 602 are engaged with the engaging pins 503 and 504. As shown in FIG. 14, even when the hooks 601 and 602 are not engaged with the engaging pins 503 and 504, the hooks 601 and 602 are located at the connecting position by the biasing force of the spring 604.

[0122] A more detailed description will be given. The hook 601 is disposed at a position corresponding to the engagement pin 503 above the hook 602, and is rotatably supported via a rotation shaft 601b with respect to the unit frame 147 of the chamfering processing unit 134. The rotation shaft 601b rotatably supports a portion near the base end (portion near the F side) of the hook 601. At the tip (R side end) of the hook 601, an inclined portion 601a that is inclined upward toward the R side at the connection position is formed. Further, on the F side of the tip of the hook 601 and closer to the F side than the inclined portion 601a, an engaging portion 601c having an engaging surface facing the F side at the connection position is formed. Between the intermediate portion of the hook 601, that is, between the rotation shaft 601b and the engaging portion 601c, a connection shaft 601d connected to the link 603 is provided.

[0123] The hook 602 is disposed at a position corresponding to the engagement pin 504, and is rotatably supported via a rotation shaft 602b with respect to the unit frame 147 of the chamfering processing unit 134. The rotation shaft 602b rotatably supports a portion near the base end (portion near the F side) of the hook 602. At the tip (R side end) of the hook 602, an inclined portion 602a that is inclined upward toward the R side at the connection position is formed. Further, on the F side of the tip of the hook 602 and closer to the F side than the inclined portion 602a, an engaging portion 602c having an engaging surface facing the F side at the connection position is formed. Between the intermediate portion of the hook 602, that is, between the rotation shaft 602b and the engaging portion 602c, a connection shaft 602d connected to the link 603 is provided. Further, between the hook 602 and the unit frame 147, a spring 604 is provided as a biasing portion that biases the hook 602 in the counterclockwise direction in FIG. 12 about the rotation shaft 602b. In the present embodiment, a spring 604, which is a tension spring, is provided between a position below the rotation shaft 602b of the hook 602 and a part of the unit frame 147.

[0124] When connecting the additional folding processing unit 500 and the corner folding processing unit 134, as shown in FIG. 15, move the additional folding processing unit 500 toward the corner folding processing unit 134 at the home position by the drive motor 135 on the F side of the sheet processing apparatus B. Then, as shown in FIG. 16(a), as the additional folding processing unit 500 moves, the engaging pin 503 contacts the inclined portion 601a of the hook 601, and the engaging pin 504 contacts the inclined portion 602a of the hook 602.

[0125] Next, as shown in FIG. 16(b), as the additional folding processing unit 500 further moves to the F side, the hook 601 is pushed by the inclined portion 601a against the engaging pin 503, and the hook 601 rotates clockwise (in the right-hand direction in the figure) about the rotation axis 601b. The hook 602 rotates clockwise in the figure about the rotation axis 602b by being pushed by the inclined portion 602a against the engaging pin 504. That is, by moving the additional folding processing unit 500 closer to the corner folding processing unit 134, the engaging pins 503 and 504 lift the hooks 601 and 602. At this time, the biasing force of the spring 604 acts on the hook 602 and, via the link 603, on the hook 601. However, the hooks 601 and 602 rotate clockwise against the biasing force of the spring 604 as the inclined portions 601a and 602a are pushed by the engaging pins 503 and 504, respectively.

[0126] As shown in FIG. 17(a), as the additional folding processing unit 500 further moves to the F side, the hooks 601 and 602 ride over the engaging pins 503 and 504, and the engagement between the hooks 601 and 602 and the engaging pins 503 and 504 is completed. That is, when the engaging pins 503 and 504 pass under the tip portions of the hooks 601 and 602 that have been lifted by the engaging pins 503 and 504 and the engaging pins 503 and 504 reach the F side of the engaging portions 601c and 602c of the hooks 601 and 602, the hooks 601 and 602 rotate counterclockwise about the rotation axes 601b and 602b by the biasing force of the spring 604 and return to the connected position. As a result, the additional folding processing unit 500 and the corner folding processing unit 134 are in a connected state.

[0127] In this state, when the doubling unit 500 is moved to the R side by the drive motor 135, the engagement pin 503 engages with the engagement portion 601c of the hook 601, and the engagement pin 504 engages with the engagement portion 602c of the hook 602. Then, as shown in Fig. 17(b), when the doubling unit 500 is moved, due to the engagement of the engagement pins 503 and 504 with the hooks 601 and 602, the corner folding unit 134 moves together with the doubling unit 500.

[0128] In this way, by connecting the doubling unit 500 and the corner folding unit 134, the movement of the two units in the width direction can be performed by one drive source. Specifically, when the doubling process control unit 345 (Fig. 3) executes the doubling process, it drives the drive motor 135 to move the doubling unit 500 alone along the width direction of the sheet bundle. On the other hand, when the corner folding process control unit 345 executes the corner folding process, it moves the doubling unit 500 toward the corner folding unit 134 at the home position, and connects the corner folding unit 134 to the doubling unit 500 by the connection mechanism 600. Then, the corner folding unit 134 and the doubling unit 500 are moved along the width direction of the sheet bundle. In this way, it is possible to move the doubling unit 500 alone or in a state where the doubling unit 500 and the corner folding unit 134 are connected by the drive motor 135, which is one drive source. Therefore, it is not necessary to provide a drive source for each unit to move, and the size reduction and cost reduction of the device can be achieved.

[0129] [Disconnection mechanism] Next, as described above, in order to move the doubling unit 500 alone during the doubling process, the disconnection mechanism 700 for disconnecting the connection between the doubling unit 500 and the corner folding unit 134 will be described with reference to FIGS. 18(a) to 19(b). The disconnection mechanism 700 is a mechanism for disconnecting the connection between the corner folding unit 134 and the doubling unit 500 connected by the above-described connection mechanism 600. The disconnection mechanism 700 includes a rack 704 as an operating part for operating the hooks 601 and 602 in a direction to release the engagement of the engaged engagement pins 503, 504 and the hooks 601, 602, and a drive motor 701 as a drive source for disconnecting the connection for driving the rack 704.

[0130] The disconnection mechanism 700 is disposed at a position adjacent to the F side with respect to the corner folding unit 134 in the home position. The drive motor 701 is supported by the frame C21 of the doubling unit C2, and is disposed on the back side of the motor frame 701a fixed to the frame C21 when viewed from the discharge port side of the sheet bundle. A through hole 701b is formed in the motor frame 701a, and the drive shaft 701c of the drive motor 701 projects from the through hole 701b toward the discharge port side. A belt 702 is stretched between a pulley 701d fixed to the drive shaft 701c and a pulley 703a (see FIG. 14) fixed to a gear 703 that meshes with the rack 704. The gear 703 is disposed below the drive shaft 701c and is driven via the drive shaft 701c, the pulley 701d, the belt 702, and the pulley 703a when the drive motor 701 is driven.

[0131] The rack 704 is supported so as to be movable in the width direction with respect to the motor frame 701a. The rack 704 has a tooth portion 704a that meshes with the gear 703, and a pressing portion 704b that abuts against the abutting portion 602e of the hook 602 and presses the hook 602. The abutting portion 602e is fixed to the hook 602 at a position below the rotation shaft 602b. When the gear 703 is rotationally driven by the drive motor 701 as described above, the rack 704 moves in the width direction due to the meshing between the gear 703 and the tooth portion 704a. Then, the pressing portion 704b provided at the R-side end of the rack 704 abuts against or separates from the abutting portion 602e.

[0132] The disconnection of the connection between the corner folding processing unit 134 and the double folding processing unit 500 is performed by the above-described connection disconnection mechanism 700 with the corner folding processing unit 134 and the double folding processing unit 500 moved to the F side, as shown in FIG. 18(a). The position where the disconnection is performed is the home position of the corner folding processing unit 134. That is, the connection disconnection mechanism 700 disconnects the connection between the corner folding processing unit 134 and the double folding processing unit 500 in a state where the corner folding processing unit 134 connected to the double folding processing unit 500 is in the home position.

[0133] Specifically, with both units in this position, the drive motor 701 is driven to rotate the drive shaft 701c clockwise (in the rightward direction in the figure). Then, the gear 703 rotates clockwise in the figure via the pulley 701d, the belt 702, and the pulley 703a, and the rack 704 meshing with the gear 703 moves from the F side toward the R side, as shown in FIG. 18(b). Then, the pressing portion 704b of the rack 704 abuts against the abutting portion 602e of the hook 602.

[0134] When the rack 704 further moves to the R side, the contact portion 602e is pushed by the pressing portion 704b, and as shown in FIG. 19(a), the hook 602 rotates clockwise in the drawing about the rotation shaft 602b against the biasing force of the spring 604. When the hook 602 rotates, the hook 601 connected via the link 603 also rotates about the rotation shaft 601b. That is, when the hook 602 rotates clockwise about the rotation shaft 602b, the link 603 connected to the tip side of the hook 602 rather than the rotation shaft 602b is lifted upward. Since the link 603 is connected to the hook 601 on the tip side rather than the rotation shaft 601b, when the hook 601 is lifted by the link 603, the hook 601 rotates clockwise about the rotation shaft 601b. As a result, the engagement pins 503 and 504 of the double-fold processing unit 500 are disengaged from the hooks 601 and 602. That is, the engagement between the engagement pins 503 and 504 and the hooks 601 and 602 is released, and the double-fold processing unit 500 becomes movable independently.

[0135] In this state, by moving the double-fold processing unit 500 in the R direction, which is the direction away from the corner folding processing unit 134, by the drive motor 135, as shown in FIG. 19(b), only the double-fold processing unit 500 moves to the R side while leaving the corner folding processing unit 134 on the F side. That is, when disconnecting the connection between the corner folding processing unit 134 and the double-fold processing unit 500, after releasing the engagement between the engagement pins 503 and 504 and the hooks 601 and 602, the drive motor 135 moves the double-fold processing unit 500 in the direction away from the corner folding processing unit 134.

[0136] From the state shown in FIG. 19(b), by rotating the drive shaft 701c of the drive motor 701 in the reverse direction (counterclockwise), the rack 704 is moved to the F side. As a result, the pressing portion 704b separates from the contact portion 602e of the hook 602, and as shown in FIG. 12 described above, the hook 602 returns to the connection position by the biasing force of the spring 604. At this time, the hook 601 also returns to the engagement position via the link 603. That is, by driving the drive motor 701 with the doubling process unit 500 separated from the corner folding process unit 134 to move the rack 704 to the F side, it is possible to prevent the hooks 601 and 602 from engaging with the engagement pins 503 and 504 again.

[0137] In addition, when disconnecting the connection between the corner folding process unit 134 and the doubling process unit 500, in addition to driving the drive motor 135 as described above to move the doubling process unit 500, for example, when the contact portion 602e is pushed by the pressing portion 704b of the rack 704 and the hook 602 rotates, a protruding portion provided on the hook 601 or the hook 602, or a member interlocked with the operation of the hook may push the doubling process unit 500 to separate the doubling process unit 500 from the corner folding process unit 134. In short, after the engagement between the engagement pins 503 and 504 and the hooks 601 and 602 is released, when returning the hooks 601 and 602 to their original positions, it is sufficient that the doubling process unit 500 is separated from the corner folding process unit 134 so that the engagement pins 503 and 504 do not engage with the hooks 601 and 602 again. Also, if two pressing portions 704b of the connection release mechanism 700 are provided and each can release the engagement of the hooks 601 and 602, the link 603 may be omitted.

[0138] As described above, in the present embodiment, by having a connection mechanism that connects the doubling process unit 500 and the corner folding process unit 134, and a connection release mechanism 700 that releases this connection, it is possible to move the doubling process unit 500 alone or in a state where the doubling process unit 500 and the corner folding process unit 134 are connected in the width direction by a drive motor 135 which is one drive source.

[0139] [Doubling process] Next, the doubling process performed by the doubling process unit 500 will be described with reference to FIGS. 20(a) to 20(d). Note that FIGS. 20(a) to 20(d) and FIGS. 21(a) to 21(c) described later show the moving direction of the upper clamp unit 121 as the vertical direction. However, in reality, as shown in FIGS. 4 and 5, the moving direction of the upper clamp unit 121 is inclined with respect to the vertical direction. The same applies to FIGS. 22(a) to 23(c) of the second and third embodiments.

[0140] As described above, the doubling process unit 500 performs a doubling process of sandwiching a sheet bundle that protrudes downstream in the conveyance direction from the lower clamp unit 120 and the upper clamp unit 121 while moving along the width direction of the sheet bundle in a state where the sheet bundle is sandwiched between the lower clamp unit 120 and the upper clamp unit 121. It has a pair of doubling rollers 501 and 502. Also, regarding the conveyance direction of the sheet bundle, the upstream end at the nip of the pair of doubling rollers 501 and 502 during the doubling process is located downstream in the conveyance direction from the position where the surface of the pressing roller 123 contacts the back of the sheet bundle during the corner folding process. Note that if the upstream end at the nip of the pair of doubling rollers 501 and 502 is located downstream in the conveyance direction from the position where the surface of the pressing roller 123 contacts the back of the sheet bundle, the pair of doubling rollers 501 and 502 and the pressing roller 123 may partially overlap when viewed from the width direction. Also, the upstream end at the nip of the pair of doubling rollers 501 and 502 may be located downstream from the downstream end of the pressing roller 123 in the conveyance direction.

[0141] In this embodiment, the upstream end portion of the nip of the doubling rollers 501 and 502 is positioned downstream in the conveyance direction (saddle third roller conveyance direction 118c) from the position where the pressing roller 123 presses the back of the sheet bundle. For this reason, the protruding amount of the sheet bundle from the lower clamp unit 120 and the upper clamp unit 121 is made different between the case where the corner folding process is performed and the case where the doubling process is performed. That is, the protruding amount of the sheet bundle from the end faces 121b and 120c on the downstream side in the conveyance direction of the lower clamp unit 120 and the upper clamp unit 121 in the case of performing the doubling process is made larger than the protruding amount of the sheet bundle from the end faces 121b and 120c on the downstream side in the conveyance direction of the lower clamp unit 120 and the upper clamp unit 121 in the case of performing the corner folding process.

[0142] Figs. 20(a) to (d) are diagrams showing the operations of the doubling process mode by the doubling process unit 500 in order. The upper clamp unit 121 and the lower clamp unit 120 have, as described above, a pair of first clamp portions 119c and 119d, and a pair of second clamp portions 142 and 143 positioned downstream in the conveyance direction from the pair of first clamp portions 119c and 119d. Further, the pre-clamp upper guide portion 119a and the pre-clamp lower guide portion 119b are integrally formed with the pair of first clamp portions 119c and 119d, respectively, and extend further upstream from the upstream end portions of the first clamp portions 119c and 119d in the conveyance direction of the sheet bundle.

[0143] In this embodiment, the first clamp portion 119d and the second clamp portion 143 included in the lower clamp unit 120 as one of the clamp units are fixed clamp portions that do not move when performing the doubling process and the corner folding process. On the other hand, the first clamp portion 119c and the second clamp portion 142 included in the upper clamp unit 121 as the other clamp unit are movable clamp portions that can move along the thickness direction of the sheet bundle when performing the doubling process and the corner folding process. The first clamp portion 119c, the second clamp portion 142, and the pre-clamp upper guide portion 119a move integrally along the thickness direction of the sheet bundle.

[0144] In this embodiment, when performing the corner folding process, the sheet bundle is clamped by a pair of first clamp portions 119c and 119d and a pair of second clamp portions 142 and 143. On the other hand, when performing the double folding process, the sheet bundle is clamped by a pair of first clamp portions 119c and 119d, and the pair of second clamp portions 142 and 143 do not clamp the sheet bundle. Alternatively, when performing the double folding process, the sheet bundle is clamped by a pair of first clamp portions 119c and 119d, and the clamping pressure for clamping the sheet bundle by the pair of second clamp portions 142 and 143 is made smaller than that in the case of the corner folding process. A detailed description of this point will be given later.

[0145] When performing the double folding process, first, when the middle folding control unit 344 (Fig. 3) detects the tip of the sheet bundle Sb by the saddle conveyance sensor 117 (Fig. 4) as a trigger, the middle-folded sheet bundle Sb is conveyed between the upper clamp unit 121 and the lower clamp unit 120 in a separated state. Then, as shown in Fig. 20(a), the middle folding control unit 344 stops the conveyance of the sheet bundle Sb in a state where the back Ssp of the sheet bundle Sb protrudes further downstream in the conveyance direction than the end faces 121b and 120c on the downstream side in the conveyance direction of the upper clamp unit 121 and the lower clamp unit 120.

[0146] In this state, the double folding process control unit 345 drives the clamp drive motor 132 (Figs. 7(a) and (b)) to move the upper clamp unit 121 toward the lower clamp unit 120, and as shown in Fig. 20(b), the sheet bundle Sb is clamped by the upper clamp unit 121 and the lower clamp unit 120. As described above, in the double folding process, the sheet bundle is clamped by a pair of first clamp portions 119c and 119d, and the pair of second clamp portions 142 and 143 do not clamp the sheet bundle, or the clamping pressure for clamping the sheet bundle by the pair of second clamp portions 142 and 143 is made smaller than that in the case of the corner folding process.

[0147] At this time, the back Ssp of the sheet bundle Sb protrudes by P2 more downstream than the end faces 121b and 120c on the downstream side in the conveyance direction of the pair of second clamp portions 142 and 143 of the upper clamp unit 121 and the lower clamp unit 120. The protrusion amount P2 is larger than the protrusion amount P1 (FIG. 11(b)) in the above-described angular back processing mode.

[0148] Next, the double-fold processing control unit 345 moves the double-fold processing unit 500 in the width direction of the sheet bundle Sb by operating the drive motor 135 (FIG. 7(b)). Specifically, the double-fold processing unit 500 is moved alone in the width direction without being connected to the angular back processing unit 134. At this time, as shown in FIG. 20(c), while the sheet bundle Sb is clamped by the upper clamp unit 121 and the lower clamp unit 120, the double-fold rollers 501 and 502 sandwich the sheet bundle Sb protruding more downstream in the conveyance direction than the upper clamp unit 121 and the lower clamp unit 120 while moving along the width direction of the sheet bundle Sb.

[0149] When the double-fold rollers 501 and 502 move in the width direction, the double-fold roller 501 rotates about the rotation shaft 501a, and the double-fold roller 502 rotates about the rotation shaft 502a. Thereby, the sheet bundle is double-folded by the double-fold rollers 501 and 502. Each of the rotation shafts 501a and 502a is rotatably supported by a support member (not shown). The rotation shafts 501a and 502a extend in a direction (ideally, a direction perpendicular) intersecting both the width direction of the sheet bundle Sb and the moving direction of the upper clamp unit 121. Further, the rotation shafts 501a and 502a extend in a direction (ideally, a direction perpendicular) intersecting the roller shaft 141 (FIG. 11(c)) of the pressing roller 123 of the angular back processing unit 134. That is, the pressing roller 123 of the angular back processing unit 134 presses the back of the sheet bundle on a plane perpendicular to the back SSp of the sheet bundle Sb, while the double-fold rollers 501 and 502 of the double-fold processing unit 500 sandwich the back of the sheet bundle from both sides in the thickness direction.

[0150] As described above, the additional folding processing unit 500 sandwiches the back SSp of the sheet bundle Sb by moving in the front-rear direction (width direction, the back side direction of the paper surface in Fig. 20(c)) of the sheet processing apparatus B by the drive motor 135 (Fig. 7(b)) and performs additional folding. The additional folding processing unit 500 may be configured to perform additional folding by moving in one direction in the width direction with respect to the back of the sheet bundle, or may be configured to perform additional folding by reciprocating movement. The user may be allowed to select the number of movements of the additional folding processing unit 500.

[0151] After the additional folding by the additional folding processing unit 500, as shown in Fig. 20(d), the additional folding processing control unit 345 drives the clamp drive motor 132 (Fig. 7(a), (b)) to separate the first clamp portion 119c of the upper clamp unit 121 from the first clamp portion 119d of the lower clamp unit 120 and releases the clamping of the sheet bundle Sb. Then, the discharging operation of the sheet bundle Sb described above is performed.

[0152] Thus, in this embodiment, the additional folding process and the corner-back process are used to make the protruding amount of the back of the sheet bundle from the upper clamp unit 121 and the lower clamp unit 120 different. Thereby, it becomes possible to selectively execute the additional folding process and the corner-back process using the common upper clamp unit 121 and lower clamp unit 120. For this reason, it is not necessary to prepare a clamp for clamping the sheet bundle in each process, and the driving of the clamp can be made common. As a result, the size reduction and cost reduction of the apparatus can be achieved.

[0153] In this embodiment, the protruding amount P2 of the back SSp of the sheet bundle Sb during the double-fold processing is made larger than the protruding amount P1 of the sheet bundle Sb during the corner-back processing. When performing the corner-back processing, the pressing roller 123 needs to be in surface contact with the upper clamp unit 121 and the lower clamp unit 120 in order to vertically flatten (create a corner) the back Ssp of the sheet bundle Sb. For this reason, the pressing roller 123 used for the corner-back processing must be arranged closer to the upper clamp unit 121 and the lower clamp unit 120 than the double-fold rollers 501 and 502. On the other hand, the double-fold rollers 501 and 502 for performing the double-fold processing do not need to contact the upper clamp unit 121 and the lower clamp unit 120. For this reason, by setting the clamping position of the back of the sheet bundle by the double-fold rollers 501 and 502 of the double-fold processing unit 500 farther than the position where the pressing roller 123 of the corner-back processing unit 134 presses the sheet bundle, the corner-back processing and the double-fold processing can be executed using a common clamp drive.

[0154] [Clamping pressure of the clamp] Next, the clamping pressure with which the upper clamp unit 121 and the lower clamp unit 120 clamp the sheet bundle in the corner-back processing and the double-fold processing will be described with reference to FIGS. 21(a) to 21(c). Here, in the corner-back processing, as described above, in order to make the back of the sheet bundle vertical and create a corner on the back, the clamping pressure of the upper clamp unit 121 and the lower clamp unit 120 (hereinafter also simply referred to as "clamping pressure of the clamp") needs to be a strong pressure that does not allow the sheet bundle to escape from the upper clamp unit 121 and the lower clamp unit 120 when the back of the sheet bundle is pressed by the pressing roller 123. On the other hand, in the double-fold processing, the back portion of the sheet bundle is nipped by the double-fold rollers 501 and 502 to perform double folding. The upper clamp unit 121 and the lower clamp unit 120 clamp the sheet bundle when the double-fold rollers 501 and 502 move in the width direction along the back of the sheet bundle. However, if the sheet bundle is clamped with the clamping pressure of the clamp during the corner-back processing, a clamping mark will remain near the back of the sheet bundle. For this reason, in the double-fold processing, the clamping pressure of the clamp is set lower than that during the corner-back processing.

[0155] Thus, in order to vary the clamping pressure of the clamp between the angled-back process and the double-fold process, it is conceivable to provide different clamps for each process and drive them separately, but in this case, the apparatus becomes larger in size and the manufacturing cost also increases. Therefore, in the present embodiment, by adopting the following configuration, the clamping pressure of the sheet bundle by the upper clamp unit 121 and the lower clamp unit 120 can be changed, and the sheet bundle can be clamped in the angled-back process and the double-fold process with the same drive. In particular, in the present embodiment, by using springs, it is possible to selectively use the first clamp portions 119c and 119d used in the double-fold process and the second clamp portions 142 and 143 used in the angled-back process.

[0156] In the present embodiment, the clamping pressure with which the upper clamp unit 121 and the lower clamp unit 120 clamp the sheet bundle when performing the angled-back process is made larger than the clamping pressure with which the upper clamp unit 121 and the lower clamp unit 120 clamp the sheet bundle when performing the double-fold process. For this purpose, the upper clamp unit 121 and the lower clamp unit 120 have a first spring 801 as a first biasing portion for generating the clamping pressure for clamping the sheet bundle and a second spring 802 as a second biasing portion. Then, when performing the double-fold process, the clamping pressure of the clamp is generated by the first spring, and when performing the angled-back process, the clamping pressure of the clamp is generated by the first spring 801 and the second spring 802.

[0157] Specifically described below. The lower clamp unit 120, which is one of the upper clamp unit 121 and the lower clamp unit 120, includes one of the pair of first clamp portions 119c and 119d, i.e., the first clamp portion 119d, one of the pair of second clamp portions 142 and 143, i.e., the second clamp portion 143, and a first spring 801 that biases one of the first clamp portions 119d toward the other first clamp portion 119c of the pair of first clamp portions 119c and 119d.

[0158] On the other hand, the upper clamp unit 121, which is the other clamp unit among the upper clamp unit 121 and the lower clamp unit 120, includes the other first clamp portion 119c, the other second clamp portion 143 among the pair of second clamp portions 142 and 143, and a second spring 802 that biases the other second clamp portion 143 toward the one second clamp portion 142.

[0159] The lower clamp unit 120 further includes a fixing member 120d that fixes the one second clamp portion 143 so as not to be movable in a direction along the thickness direction of the sheet bundle (the vertical direction in FIGS. 21(a) to 21(c)). The fixing member 120d is supported by a support member (not shown). The fixing member 120d has a first portion 120d1 disposed below the second clamp portion 143 and a second portion 120d2 protruding from the first portion 120d1 toward the upstream side in the conveyance direction (the right side in FIGS. 21(a) to 21(c)). The one first clamp portion 119d is disposed so as to be movable along the thickness direction of the sheet bundle with respect to the fixing member 120d. As shown in FIG. 21(a), the first clamp portion 119d is located closer to the upper clamp unit 121 than the one second clamp portion 143 in a state where the sheet bundle is not clamped by the pair of first clamp portions 119c and 119d. Further, the first spring 801 is disposed between the second portion 120d2 of the fixing member 120d and the one first clamp portion 119d.

[0160] The upper clamp unit 121 further has a moving member 121c that is movable along the thickness direction of the sheet bundle to a first position and a second position closer to the lower clamp unit 120 than the first position. The other first clamp portion 119c moves integrally with the moving member 121c. That is, the moving member 121c has a first portion 121c1 disposed above the second spring 802 and a second portion 121c2 fixed to the first portion 121c1 and formed integrally with the first clamp portion 119c. Therefore, the first clamp portion 119c moves along the thickness direction of the sheet bundle together with the moving member 121c. Since the pre-clamp upper guide portion 119a is formed integrally with the first clamp portion 119c, the pre-clamp upper guide portion 119a also moves together with the moving member 121c and the first clamp portion 119c.

[0161] The other second clamp portion 142 is disposed so as to be movable along the thickness direction of the sheet bundle with respect to the moving member 121c. The second spring 802 is disposed between the first portion 121c1 of the moving member 121c and the other second clamp portion 142. The biasing force of the first spring 801 is weaker than that of the second spring 802. Therefore, as will be described later, when the moving member 121c is lowered to sandwich the sheet bundle with the first clamp portion 119c and the second clamp portion 142 and the first clamp portion 119d and the second clamp portion 143, the first spring 801 contracts before the second spring 802.

[0162] FIG. 21(a) shows a state in which the upper clamp unit 121 and the lower clamp unit 120 are separated and a state in which a sheet bundle Sb is received between the upper clamp unit 121 and the lower clamp unit 120. In this state, the conveyance of the sheet bundle Sb is stopped with the back Ssp of the sheet bundle Sb protruding further downstream in the conveyance direction than the end faces 121b and 120c on the downstream side in the conveyance direction of the upper clamp unit 121 and the lower clamp unit 120.

[0163] When performing the additional folding process, the moving member 121c is moved to the first position from the state shown in Fig. 21(a). Then, as shown in Fig. 21(b), the sheet bundle Sb is clamped by a pair of first clamp portions 119c and 119d, thereby compressing the first spring 801 between the second portion 120d2 of the fixing member 120d and one of the first clamp portions 119d. At this time, the second spring 802 is not compressed between the first portion 121c1 of the moving member 121c and the second clamp portion 142, or even if it is compressed, the compression amount is small and the biasing force is small. Therefore, during the additional folding process, the clamping pressure of the clamp is generally based on the biasing force generated by the elastic compression of the first spring 801.

[0164] On the other hand, when performing the angled back process, the moving member 121c is moved to the second position, and as shown in Fig. 21(c), the sheet bundle Sb is clamped by a pair of first clamp portions 119c and 119d and a pair of second clamp portions 142 and 143. That is, the moving member 121c is further lowered from the position shown in Fig. 21(b). As a result, the first spring 801 can be compressed between the second portion 120d2 of the fixing member 120d and one of the first clamp portions 119d, and the second spring 802 can be compressed between the first portion 121c1 of the moving member 121c and the other second clamp portion 142. Therefore, during the angled back process, the clamping pressure of the clamp is based on the biasing forces generated by the elastic compression of the first spring 801 and the second spring 802, respectively.

[0165] Thus, in this embodiment, by using the first spring 801 and the second spring 802 to change the lowering position of the moving member 121c, the clamping pressure of the clamp is changed. Therefore, it is possible to clamp the sheet bundle in the corner folding process and the double folding process with the same drive. As a result, compared with a configuration in which a drive source is provided or a clamp is provided in each process, the size and cost of the apparatus can be reduced. Further, by arranging the first clamp portions 119c and 119d for double folding on the upstream side and the second clamp portions 142 and 143 for corner folding on the downstream side in the conveyance direction of the sheet bundle, the clamping pressures of two types of clamps can be realized with one moving mechanism, and two types of processes, namely the double folding process and the corner folding process, can be performed.

[0166] <Second Embodiment> The second embodiment will be described with reference to FIGS. 22(a) to 22(c). In the above-described first embodiment, the configuration in which the first spring 801 is provided in the lower clamp unit 120 and the second spring 802 is provided in the upper clamp unit 121 has been described. In contrast, in this embodiment, the first spring 803 and the second spring 802 are provided in the upper clamp unit 121. Since the other configurations and operations are the same as those of the first embodiment described above, the same components are denoted by the same reference numerals, and the description and illustration are omitted or simplified. Hereinafter, the description will focus on the differences from the first embodiment.

[0167] In this embodiment, the lower clamp unit 120A as one of the upper clamp unit 121A and the lower clamp unit 120A includes one of the pair of first clamp portions 119c and 119d, i.e., the first clamp portion 119d, and one of the pair of second clamp portions 142 and 143, i.e., the second clamp portion 143.

[0168] On the other hand, the upper clamp unit 121A, which is the other clamp unit among the upper clamp unit 121A and the lower clamp unit 120A, includes the other first clamp part 119c among the pair of first clamp parts 119c and 119d, the other second clamp part 142 among the pair of second clamp parts 142 and 143, a first spring 803 as a first biasing part that biases the other first clamp part 119c toward one first clamp part 119d, and a second spring 802 as a second biasing part that biases the other second clamp part 142 toward one second clamp part 143. When performing the double-fold processing, the first spring 803 generates the clamping pressure of the clamp. When performing the corner folding processing, the first spring 803 and the second spring 802 generate the clamping pressure of the clamp.

[0169] The lower clamp unit 120A further includes a fixing member 120d to which one first clamp part 119d and one second clamp part 143 are fixedly arranged so as not to be movable in the direction along the thickness direction of the sheet bundle. On the other hand, the upper clamp unit 121A further includes a moving member 121c that is movable along the thickness direction of the sheet bundle between a first position and a second position closer to the lower clamp unit 120A than the first position, and a pressing part 121d that moves together with the moving member 121c. The pressing part 121d is fixed to the moving member 121c so as to protrude from the moving member 121c toward the upstream side in the conveyance direction (the right side in FIGS. 22(a) to (c)).

[0170] The other first clamp part 119c and the other second clamp part 142 are arranged so as to be movable along the thickness direction of the sheet bundle with respect to the moving member 121c. Therefore, the first clamp part 119c is also movable with respect to the pressing part 121d fixed to the moving member 121c. In the present embodiment, the first clamp part 119c and the second clamp part 142 are relatively movable with respect to each other. The other first clamp part 119c is located closer to the lower clamp unit 120A than the other second clamp part 142 in a state where the sheet bundle is not clamped by the pair of first clamp parts 119c and 119d.

[0171] The first spring 803 is disposed between the pressing portion 121d and the other first clamping portion 119c, and the second spring 802 is disposed between the moving member 121c and the other second clamping portion 142. The biasing force of the first spring 803 is weaker than that of the second spring 802. Therefore, as will be described later, when the moving member 121c is lowered to sandwich the sheet bundle with the first clamping portions 119c and 142 and the first clamping portions 119d and 143, the first spring 803 contracts before the second spring 802.

[0172] FIG. 22(a) shows a state where the upper clamping unit 121A and the lower clamping unit 120A are separated and a state where a sheet bundle Sb is received between the upper clamping unit 121A and the lower clamping unit 120A. In this state, the conveyance of the sheet bundle Sb is stopped with the back Ssp of the sheet bundle Sb protruding further downstream in the conveyance direction than the end faces 121b and 120c on the downstream side in the conveyance direction of the upper clamping unit 121A and the lower clamping unit 120A.

[0173] When performing the double-fold processing, the moving member 121c is moved to the first position from the state of FIG. 22(a). Then, as shown in FIG. 22(b), by sandwiching the sheet bundle Sb with the pair of first clamping portions 119c and 119d, the first spring 803 is compressed between the pressing portion 121d and the other first clamping portion 119c. At this time, the second spring 802 is not compressed between the moving member 121c and the second clamping portion 142, or even if it is compressed, the amount of compression is small and the biasing force is small. Therefore, during the double-fold processing, the clamping pressure of the clamp is generally based on the biasing force generated by the elastic compression of the first spring 803.

[0174] On one hand, when performing the corner folding process, the moving member 121c is moved to the second position, and as shown in Fig. 22(c), the sheet bundle Sb is clamped by a pair of first clamp portions 119c, 119d and a pair of second clamp portions 142, 143. That is, the moving member 121c is further lowered from the position shown in Fig. 22(b). As a result, the first spring 803 can be compressed between the pressing portion 121d and the other first clamp portion 119c, and the second spring 802 can be compressed between the moving member 121c and the other second clamp portion 142. Therefore, during the corner folding process, the clamping pressure of the clamp is based on the biasing force generated when the first spring 803 and the second spring 802 are elastically compressed respectively.

[0175] Thus, in this embodiment, the first spring 803 and the second spring 802 are provided on the upper clamp unit 121 that moves during clamping, and by changing the lowered position of the moving member 121c, the clamping pressure of the clamp is changed. Therefore, similar to the first embodiment, the sheet bundle can be clamped in both the corner folding process and the double folding process with the same drive, achieving miniaturization and cost reduction of the device.

[0176] <The Third Embodiment> The third embodiment will be described with reference to Figs. 23(a) to 23(c). In the above-described first and second embodiments, the configurations of the upper clamp units 121, 121A and the lower clamp units 120, 120A having the first clamp portions 119c, 119d and the second clamp portions 142, 143 respectively were described. In contrast, in this embodiment, the clamp portions for clamping the sheet bundle are the same for both the corner folding process and the double folding process. Since the other configurations and operations are the same as those of the above-described first embodiment, the same components are denoted by the same reference numerals, and the description and illustration are omitted or simplified. Hereinafter, the differences from the first embodiment will be mainly described.

[0177] In this embodiment, the lower clamp unit 120B as one of the upper clamp unit 121B and the lower clamp unit 120B has a fixed clamp portion 811 that does not move when performing the folding and corner folding processes. On the other hand, the upper clamp unit 121B as the other clamp unit of the upper clamp unit 121B and the lower clamp unit 120B is movable along the thickness direction of the sheet bundle between a first position and a second position closer to the lower clamp unit 120B than the first position. The upper clamp unit 121B further includes a moving member 812 and a moving clamp portion 813 movably arranged along the thickness direction of the sheet bundle with respect to the moving member 812.

[0178] The first spring 804 as the first biasing portion is disposed between the moving member 812 and the moving clamp portion 813. The second spring 805 as the second biasing portion is disposed between the moving member 812 and the moving clamp portion 813 and has a shorter length than the first spring 804. Further, a support shaft 121e protruding toward the moving member 812 is provided on the surface of the moving clamp portion 813 facing the moving member 812. The second spring 805 is supported by the support shaft 121e. The second spring 805 is a coil spring, and by inserting the support shaft 121e inside the coil spring, the second spring 805 is restricted from moving in the radial direction. Further, a concave portion 121f is provided at a position corresponding to the support shaft 121e on the surface of the moving member 812 facing the moving clamp portion 813. The concave portion 121f is formed such that the support shaft 121e penetrates during the corner folding process described later, but the second spring 805 does not penetrate.

[0179] Note that the first spring 804 is also a coil spring, and similar to the second spring 805, it may be configured to be supported by a support shaft provided on the moving member 812 or the moving clamp portion 813. Alternatively, projections or recesses may be provided on the moving member 812 and the moving clamp portion 813, respectively, so that both ends of the first spring 804 are supported by the respective projections or recesses. In any case, the first spring 804 and the second spring 805 only need to be supported so as not to fall off between the moving member 812 and the moving clamp portion 813 even when the moving member 812 and the moving clamp portion 813 move relative to each other.

[0180] FIG. 23(a) shows a state in which the upper clamp unit 121B and the lower clamp unit 120B are separated, and a state in which a sheet bundle Sb is received between the upper clamp unit 121B and the lower clamp unit 120B. In this state, with the back Ssp of the sheet bundle Sb protruding further downstream in the conveyance direction than the end faces 121b and 120c on the downstream side in the conveyance direction of the moving clamp portion 813 and the fixed clamp portion 811 of the upper clamp unit 121B and the lower clamp unit 120B, the conveyance of the sheet bundle Sb is stopped.

[0181] When performing the double-fold processing, the moving member 812 is moved to the first position from the state of FIG. 23(a). Then, as shown in FIG. 23(b), by sandwiching the sheet bundle Sb between the fixed clamp portion 811 and the moving clamp portion 813, the first spring 814 is compressed between the moving member 812 and the moving clamp portion 813. At this time, the second spring 805 is not compressed between the moving member 812 and the moving clamp portion 813. Therefore, during the double-fold processing, the clamping pressure of the clamp is based on the biasing force generated by the elastic compression of the first spring 804.

[0182] On one hand, when performing the corner folding process, the moving member 812 is moved to the second position, and as shown in FIG. 23(c), the sheet bundle Sb is clamped by the fixed clamp portion 811 and the moving clamp portion 813. That is, the moving member 812 is further lowered from the position shown in FIG. 23(b). At this time, the support shaft 121e that supports the second spring 805 enters the recess 121f of the moving member 812, and the second spring 805 can be compressed between the moving member 812 and the moving clamp portion 813. Thereby, the first spring 804 and the second spring 805 can be compressed between the moving member 812 and the moving clamp portion 813. Therefore, during the corner folding process, the clamping pressure of the clamp is based on the biasing force generated when the first spring 804 and the second spring 805 are elastically compressed respectively.

[0183] In this embodiment, the biasing force of the first spring 804 is made smaller than the biasing force of the second spring 805. However, if the first spring 804 is shorter than the second spring 805, and the biasing force of the first spring 804 acts during the double folding process, and the biasing forces of the first spring 804 and the second spring 805 act during the corner folding process, the biasing forces of the two springs may be the same or the first spring 804 may be larger.

[0184] Thus, in this embodiment, by changing the lengths of the first spring 804 and the second spring 805 and changing the lowering position of the moving member 812, the clamping pressure of the clamp is changed. Therefore, similar to the first embodiment, the sheet bundle can be clamped in the corner folding process and the double folding process with the same drive, and the size reduction and cost reduction of the device can be achieved. In the above description, the first spring 804 and the second spring 805 with different lengths are provided in the upper clamp unit 121B, but the first spring and the second spring with different lengths may be provided in the lower clamp unit 120B. In this case, when the upper clamp unit moves to the first position, the first spring with a longer length is compressed, and when it moves to the second position closer to the lower clamp unit than the first position, the first spring and the second spring are compressed.

[0185] <Other Embodiments> In each of the above-described embodiments, as the square-back processing unit 134, a configuration in which the back of the sheet bundle is pressed by the pressing roller 123 has been described. However, the pressing member that presses the sheet bundle is not limited to the pressing roller 123, and any configuration may be used as long as it can move along the back while pressing the back of the sheet bundle to perform the square-back processing. For example, other configurations such as a sheet metal having a curved surface may be used. Further, as the additional folding processing unit 500, a configuration of a pair of rollers including the additional folding rollers 501 and 502 has been described. However, as long as the pressing process can be performed on the fold of the sheet bundle, other configurations other than the pair of rollers may be used. For example, a combination of one roller and the other sheet metal may be used. At this time, it is preferable to provide an inclined surface on the downstream side in the moving direction of the additional folding processing unit 500 of the sheet metal so that the back of the sheet bundle can easily enter the nip portion between the sheet metal and the roller.

[0186] In each of the above-described embodiments, the connection mechanism for connecting the square-back processing unit 134 and the additional folding processing unit 500 is configured to be performed by the engagement between the engaging portions such as pins and hooks, and the connection release mechanism is configured to release this engagement. However, the connection mechanism and the connection release mechanism may have a configuration other than the engagement and disengagement between the engaging portions as long as the connection and disconnection of both units can be performed. For example, a configuration using the magnetic attraction force of a magnet may be used. For example, a magnetic member such as iron is provided on the additional folding processing unit 500 side, and an electromagnet that generates a magnetic force by energization is provided on the square-back processing unit 134 side. Then, at the time of connection, the electromagnet is adsorbed by the magnetic member by the magnetic attraction force by energizing the electromagnet, and at the time of connection release, the magnetic attraction force between the electromagnet and the magnetic member is released by stopping the energization.

[0187] In the above-described embodiment, the square-back processing is performed on the downstream side inside the saddle portion B2 in the sheet processing apparatus B, but the same square-back processing may be performed in another housing connected to the outside. For example, it may be a single unit that performs only the square-back processing without performing the saddle stitching processing or the middle folding processing. In this case, this unit includes the above-described additional folding processing unit C2 and a conveying unit such as a pair of conveying rollers that convey the sheet bundle on which the saddle stitching processing and the middle folding processing have been performed on the additional folding processing unit C2.

[0188] Also, in the above-described embodiment, the sheet processing apparatus B has a control unit and controls each component inside the sheet processing apparatus B. However, each component inside the sheet processing apparatus B may be a component controlled by the control unit provided in the image forming apparatus.

[0189] Furthermore, as the conveyance unit that conveys the sheet inside the sheet processing apparatus B, in the above-described embodiment, a pair of rollers was described as an example, but a configuration in which the sheet is conveyed by a belt may also be used. Specifically, any of a configuration in which a belt is sandwiched and conveyed by a pair of rollers, a configuration in which a sheet is sandwiched and conveyed by a pair of belts, and a configuration in which a sheet is sandwiched by a belt and a roller may be used, and the conveyance configuration may be changed depending on the position and path for conveying the sheet. For example, at a certain position, the sheet may be conveyed by a pair of rollers, and at another position, the sheet may be conveyed by a pair of belts.

[0190] Also, in the above-described embodiment, the image forming system 1000 in which the sheet processing apparatus B is directly connected to the image forming apparatus A has been described, but other system configurations may also be used. For example, a configuration in which other processing apparatuses or conveyance apparatuses are connected between the image forming apparatus A and the sheet processing apparatus B may also be used. Further, in the above-described embodiment, the image forming apparatus A that forms a monochrome image using toner has been described as an example, but an image forming apparatus that forms a color image using toner or an image forming apparatus that forms an image on a sheet using ink may also be used.

[0191] Also, the disclosure of this embodiment includes the following configurations. (Configuration 1) A conveyance unit that conveys a sheet bundle that has been subjected to a center folding process or a center binding process and a center folding process so as to be located on the downstream side in the conveyance direction from the end portion on the narrow side of the back of the sheet bundle, A pair of clamp units that clamp the sheet bundle, A first pressing unit that presses the back of a sheet bundle protruding downstream in the conveyance direction from the pair of clamp units in a state where the sheet bundle is clamped by the pair of clamp units, the first pressing unit performing a corner-back process of forming a corner with respect to the back of the sheet bundle by moving in the width direction of the sheet bundle while pressing the back of the sheet bundle toward the pair of clamp units. A second pressing unit that performs a pressing process on the fold of the sheet bundle by moving in the width direction of the sheet bundle while sandwiching the fold of the sheet bundle. A sheet processing apparatus comprising: (Configuration 2) The protruding amount of the sheet bundle from the end surface on the downstream side in the conveyance direction of the pair of clamp units when the pressing process is performed by the second pressing unit is larger than the protruding amount of the sheet bundle from the end surface on the downstream side in the conveyance direction of the pair of clamp units when the corner-back process is performed. The sheet processing apparatus according to Configuration 1. (Configuration 3) The first pressing unit has a pressing roller that presses the back of the sheet bundle. The second pressing unit has a pair of double-fold rollers that sandwich the fold of the sheet bundle. The upstream end portion at the nip of the pair of double-fold rollers in the conveyance direction is located downstream in the conveyance direction from the position where the surface of the pressing roller contacts the back of the sheet bundle during the corner-back process. The sheet processing apparatus according to Configuration 2. (Configuration 4) The clamping pressure with which the pair of clamp units clamp the sheet bundle when performing the corner-back process is greater than the clamping pressure with which the pair of clamp units clamp the sheet bundle when performing the pressing process by the second pressing unit. The sheet processing apparatus according to any one of Configurations 1 to 3. (Configuration 5) The pair of clamp units has a first biasing portion and a second biasing portion for generating a clamping pressure for clamping the sheet bundle. When performing the pressing process by the second pressing unit, the first biasing portion generates the clamping pressure. When performing the corner-back process, the sheet processing apparatus according to Configuration 4 that generates a clamping pressure by the first biasing unit and the second biasing unit. (Configuration 6) A connecting mechanism that connects the first pressing unit and the second pressing unit, A driving source that moves the first pressing unit and the second pressing unit connected by the connecting mechanism along the direction of the sheet bundle, the sheet processing apparatus according to any one of Configurations 1 to 5. (Configuration 7) The driving source moves the second pressing unit in the width direction of the sheet bundle, and when the first pressing unit is connected to the second pressing unit by the connecting mechanism, the first pressing unit and the second pressing unit are moved in the width direction of the sheet bundle, the sheet processing apparatus according to Configuration 6. (Configuration 8) The pair of clamp units includes a pair of first clamp portions and a pair of second clamp portions located downstream of the pair of first clamp portions in the conveyance direction, When performing the corner-back process, the sheet bundle is clamped by the pair of first clamp portions and the pair of second clamp portions, When performing the pressing process by the second pressing unit, the sheet bundle is clamped by the pair of first clamp portions, and the sheet bundle is not clamped by the pair of second clamp portions, the sheet processing apparatus according to any one of Configurations 1 to 7. (Configuration 9) The pair of clamp units includes a pair of first clamp portions and a pair of second clamp portions located downstream of the pair of first clamp portions in the conveyance direction, When performing the corner-back process, the sheet bundle is clamped by the pair of first clamp portions and the pair of second clamp portions, When performing the pressing process by the second pressing unit, the sheet bundle is clamped by the pair of first clamp portions, and the clamping pressure for clamping the sheet bundle by the pair of second clamp portions is smaller than that in the case of the corner-back process, the sheet processing apparatus according to any one of Configurations 1 to 7. (Configuration 10) When the second pressing unit performs the pressing process, the protruding amount of the sheet bundle from the end surface on the downstream side in the conveyance direction of the pair of clamp units is larger than the protruding amount of the sheet bundle from the end surface on the downstream side in the conveyance direction of the pair of clamp units when performing the corner folding process. The end surface on the downstream side in the conveyance direction of the pair of clamp units is the end surface on the downstream side in the conveyance direction of the pair of second clamp portions, according to the sheet processing apparatus of Configuration 8 or 9. (Configuration 11) One of the pair of clamp units has a fixed clamp portion that does not move when performing the pressing process by the second pressing unit and the corner folding process. The other of the pair of clamp units further includes a moving member that is movable along the thickness direction of the sheet bundle between a first position and a second position closer to the one clamp unit than the first position, a moving clamp portion disposed movably along the thickness direction of the sheet bundle with respect to the moving member, a first spring disposed between the moving member and the moving clamp portion, and a second spring disposed between the moving member and the moving clamp portion and having a shorter length than the first spring. When performing the pressing process by the second pressing unit, the moving member is moved to the first position, and the sheet bundle is clamped by the fixed clamp portion and the moving clamp portion, thereby compressing the first spring between the moving member and the moving clamp portion. When performing the corner folding process, the moving member is moved to the second position, and the sheet bundle is clamped by the fixed clamp portion and the moving clamp portion, thereby compressing the first spring and the second spring between the moving member and the moving clamp portion. The sheet processing apparatus according to any one of Configurations 1 to 10. (Configuration 12) When the second pressing unit performs the pressing process, the protruding amount of the sheet bundle from the end surface on the downstream side in the conveyance direction of the pair of clamp units is larger than the protruding amount of the sheet bundle from the end surface on the downstream side in the conveyance direction of the pair of clamp units when performing the corner folding process. The end face on the downstream side in the conveying direction of the pair of clamp units is the end face on the downstream side in the conveying direction of the fixed clamp portion and the moving clamp portion, according to the sheet processing apparatus of Configuration 11. (Configuration 13) An image forming unit having an image forming portion for forming an image on a sheet, The sheet processing apparatus according to any one of Configurations 1 to 12, and is provided with, The sheet processing apparatus forms a sheet bundle in which sheets on which images are formed by the image forming portion are bundled, and performs pressing processing by the second pressing unit on a sheet bundle that has been center-folded or a sheet bundle that has been center-stapled and center-folded, and performs saddle-stitching processing on a sheet bundle that has been center-stapled and center-folded, characterized in that it is an image forming system.

Explanation of Signs

[0192] 3 ··· Image forming portion 118 ··· Saddle third roller pair (conveying portion, first conveying portion) 119c, 119d ··· First clamp portion 120, 120A, 120B ··· Lower clamp unit (one of the clamp units) 120d ··· Fixed member 121, 121A, 121B ··· Upper clamp unit (the other clamp unit) 121b, 120c ··· End face 121c ··· Moving member 121d ··· Pressing portion 123 ··· Pressing roller 134 ··· Saddle-stitching processing unit (first pressing unit) 135 ··· Driving motor (driving source) 142, 143 ··· Second clamp portion 500 ··· Double-folding processing unit (second pressing unit) 501, 502 ··· Double-folding rollers 503, 504 ··· Engagement pins (first engaging portion) 600 ··· Linking mechanism 601, 602 ··· Hooks (second engaging portion) 700 ··· Link release mechanism 701 ··· Drive motor (drive source for link release) 704 ··· Rack (operating part) 801, 803, 804 ··· First spring (first biasing part) 802, 805 ··· Second spring (second biasing part) 811 ··· Fixed clamp part 812 ··· Moving member 813 ··· Moving clamp part 1000 ··· Image forming system A ··· Image forming apparatus B ··· Sheet processing apparatus C2 ··· Double - folding processing unit (corner - back processing means)

Claims

1. A conveying unit that conveys a sheet bundle that has been subjected to a middle folding process or a sheet bundle that has been subjected to a middle binding process and a middle folding process so that it is located downstream in the conveying direction from the end of the sheet bundle on the narrow side of the back; A pair of clamping units that clamp the sheet bundle; A first pressing unit that presses the back of the sheet bundle protruding downstream in the conveying direction from the pair of clamping units in a state where the sheet bundle is clamped by the pair of clamping units, and that performs a corner-back process of forming a corner on the back of the sheet bundle by moving in the width direction of the sheet bundle while pressing the back of the sheet bundle toward the pair of clamping units; A sheet processing apparatus comprising: a second pressing unit that performs a pressing process on the fold of the sheet bundle by moving in the width direction of the sheet bundle while sandwiching the fold of the sheet bundle.

2. The protruding amount of the sheet bundle from the end surface on the downstream side in the conveying direction of the pair of clamping units when the pressing process is performed by the second pressing unit is greater than the protruding amount of the sheet bundle from the end surface on the downstream side in the conveying direction of the pair of clamping units when the corner-back process is performed. The sheet processing apparatus according to Claim 1.

3. The first pressing unit has a pressing roller that presses the back of the sheet bundle; The second pressing unit has a pair of double-folding rollers that sandwich the fold of the sheet bundle; The upstream end portion at the nip of the pair of double-folding rollers in the conveying direction is located downstream in the conveying direction from the position where the surface of the pressing roller contacts the back of the sheet bundle during the corner-back process. The sheet processing apparatus according to Claim 2.

4. The clamping pressure with which the pair of clamping units clamp the sheet bundle when performing the corner-back process is greater than the clamping pressure with which the pair of clamping units clamp the sheet bundle when performing the pressing process by the second pressing unit. The sheet processing apparatus according to Claim 1.

5. The pair of clamping units have a first biasing portion and a second biasing portion for generating a clamping pressure for clamping the sheet bundle; When performing the pressing process by the second pressing unit, the first biasing portion generates the clamping pressure; When performing the corner-back process, the first biasing portion and the second biasing portion generate the clamping pressure. The sheet processing apparatus according to Claim 4.

6. A connecting mechanism for connecting the first pressing unit and the second pressing unit; The sheet processing apparatus according to claim 1, further comprising a drive source for moving the first pressing unit and the second pressing unit connected by the connecting mechanism along the direction of the sheet bundle.

7. The drive source moves the second pressing unit in the width direction of the sheet bundle, and when the first pressing unit is connected to the second pressing unit by the connecting mechanism, the drive source moves the first pressing unit and the second pressing unit in the width direction of the sheet bundle. The sheet processing apparatus according to claim 6.

8. The pair of clamp units includes a pair of first clamp portions and a pair of second clamp portions located downstream of the pair of first clamp portions in the conveyance direction. When performing the corner folding process, the sheet bundle is clamped by the pair of first clamp portions and the pair of second clamp portions. When performing the pressing process by the second pressing unit, the sheet bundle is clamped by the pair of first clamp portions, and the sheet bundle is not clamped by the pair of second clamp portions. The sheet processing apparatus according to claim 1.

9. The pair of clamp units includes a pair of first clamp portions and a pair of second clamp portions located downstream of the pair of first clamp portions in the conveyance direction. When performing the corner folding process, the sheet bundle is clamped by the pair of first clamp portions and the pair of second clamp portions. When performing the pressing process by the second pressing unit, the sheet bundle is clamped by the pair of first clamp portions, and the clamping pressure for clamping the sheet bundle by the pair of second clamp portions is smaller than that in the case of the corner folding process. The sheet processing apparatus according to claim 1.

10. The protruding amount of the sheet bundle from the end surface on the downstream side in the conveyance direction of the pair of clamp units when performing the pressing process by the second pressing unit is larger than the protruding amount of the sheet bundle from the end surface on the downstream side in the conveyance direction of the pair of clamp units when performing the corner folding process. The end surface on the downstream side in the conveyance direction of the pair of clamp units is the end surface on the downstream side in the conveyance direction of the pair of second clamp portions. The sheet processing apparatus according to claim 8.

11. One of the pair of clamp units has a fixed clamp portion that does not move when performing the pressing process by the second pressing unit and the corner folding process. The other clamping unit of the pair of clamping units further includes a moving member movable along the thickness direction of the sheet bundle between a first position and a second position closer to the one clamping unit than the first position, a moving clamping portion disposed movably along the thickness direction of the sheet bundle with respect to the moving member, a first spring disposed between the moving member and the moving clamping portion, and a second spring disposed between the moving member and the moving clamping portion and having a shorter length than the first spring. When performing the pressing process by the second pressing unit, the moving member is moved to the first position, and the sheet bundle is clamped by the fixed clamping portion and the moving clamping portion, thereby compressing the first spring between the moving member and the moving clamping portion. When performing the corner folding process, the moving member is moved to the second position, and the sheet bundle is clamped by the fixed clamping portion and the moving clamping portion, thereby compressing the first spring and the second spring between the moving member and the moving clamping portion. The sheet processing apparatus according to claim 1.

12. The protruding amount of the sheet bundle from the end face on the downstream side in the conveyance direction of the pair of clamping units when performing the pressing process by the second pressing unit is larger than the protruding amount of the sheet bundle from the end face on the downstream side in the conveyance direction of the pair of clamping units when performing the corner folding process. The end face on the downstream side in the conveyance direction of the pair of clamping units is the end face on the downstream side in the conveyance direction of the fixed clamping portion and the moving clamping portion. The sheet processing apparatus according to claim 11.

13. An image forming unit having an image forming portion for forming an image on a sheet. The sheet processing apparatus according to any one of claims 1 to 12, and The sheet processing apparatus is a sheet bundle formed by bundling sheets on which an image has been formed by the image forming portion, and performs a pressing process by the second pressing unit on a sheet bundle that has been subjected to a middle folding process or a sheet bundle that has been subjected to a middle binding process and a middle folding process, and performs the corner folding process on a sheet bundle that has been subjected to a middle binding process and a middle folding process. An image forming system characterized by this.

Images