21 in advance, and image data is read from an image passing through the space on the second platen glass 21.

Overall Configuration of Sheet Processing Apparatus

Next, an overall configuration of the sheet processing apparatus B that performs a process such as a stapling process, a folding process, and the like on sheets conveyed from the image forming apparatus A will be described next with reference to FIG. 2. FIG. 2 illustrates a detailed configuration of the sheet processing apparatus B. The sheet processing apparatus B is capable of stacking sheets on a first tray (first stacking tray) 49, a saddle discharge unit 131, and a second tray (second stacking tray) 71 that will be described later after processing the sheets received through an inlet portion 26 serving as an inlet of a conveyance path 28 continuous from the discharge port 16. In the present embodiment, a path refers to the entirety of a path in which a sheet is conveyed by a conveyance guide, a conveyance roller, and the like.

In the illustrated apparatus, the sheet conveyed to the conveyance path 28 serving as a first conveyance path is discharged onto a first tray 49 after being processed by a processing portion B1 that will be described later, or the sheet conveyed in the conveyance path 28 is discharged onto the second tray 71, or is discharged to a saddle discharge unit 131 after being processed by a saddle portion B2 that will be described later. Each apparatus includes a controller, a communication portion, and the like as indicated by blocks representing the overall control configuration of the apparatus illustrated in FIG. 3, and thus the apparatus is controlled.

The processing portion B1 serving as an end binding processing portion is disposed below a path outlet (passing portion 35) of the conveyance path 28, and is capable of accumulating a plurality of sheets sequentially passed on thereto from the conveyance path 28 through the passing portion 35 for each copy to form a sheet bundle, and executing a binding process on an end portion of the sheet bundle. The sheet bundle subjected to the binding process is stacked on the first tray 49 serving as a stacking portion. The trailing end (upstream end) of the sheet or sheet bundle stacked on the first tray 49 abuts a stacking wall 50 provided on the upstream side in the sheet discharge direction of the first tray 49, and is thus stacked along the stacking wall 50.

The first tray 49 is capable of moving up and down with respect to a processing tray 37 that will be described later, and supports thereon a sheet bundle subjected to the binding process by a binding processing mechanism 47 that will be described later. In the present embodiment, the first tray 49 and the second tray 71 are capable of moving up and down by an unillustrated lifting/lowering mechanism. That is, in the present embodiment, when delivering out the sheet onto the first tray 49 or the second tray 71 serving as a stacking tray, the first tray 49 or the second tray 71 is moved up or down to maintain the position of the uppermost sheet on the stacking surface of the tray constant with respect to the discharge roller pair 42 and a second discharge roller 207 such that the alignment of the stacked sheets is not degraded.

The saddle portion B2 is disposed below the passing portion of the saddle path 32 serving as a second conveyance path branching downward in the vertical direction from the conveyance path 28, accumulates a plurality of sheets sequentially passed on thereto from the conveyance path 28 through the saddle path 32 and the passing portion for each copy to form a sheet bundle, performs a folding process after executing a saddle binding process or without performing the saddle binding process, and discharges the sheet bundle to the saddle discharge unit 131. Detailed description of each configuration will be given below.

Housing

As illustrated in FIG. 2, the sheet processing apparatus B includes a housing 27, the conveyance path 28, the processing portion B1, the saddle portion B2, the first tray 49, the saddle discharge unit 131, the second tray 71, and the like. The conveyance path 28, the processing portion B1, and the saddle portion B2 are disposed inside the housing 27. In addition, the conveyance path 28 includes the inlet portion 26 and the passing portion 35 for the sheet. The processing portion B1 and the saddle portion B2 process the sheet passed on thereto from the passing portion 35 of the conveyance path 28. The first tray 49, the saddle discharge unit 131, and the second tray 71 support thereon a sheet conveyed from each processing portion. The illustrated housing 27 is connected to a housing 1 of the image forming apparatus A positioned upstream thereof in the sheet conveyance direction in the conveyance path 28. Further, the housing 27 and the housing 1 are disposed such that the height of the discharge port 16 of the image forming apparatus A from the installation surface and the height of the inlet portion 26 of the sheet processing apparatus B from the installation surface are approximately equal, and the discharge port 16 and the inlet portion 26 are connected.

Sheet Introduction Path

The conveyance path 28 serving as a sheet introduction path is configured as an approximately linear path traversing the housing 27 in an approximately horizontal direction, and includes the inlet portion 26 continuous with the discharge port (body discharge port) 16 of the image forming apparatus A and the passing portion 35 positioned on the opposite side across the apparatus with respect to the inlet portion 26. In the conveyance path 28, an inlet roller 29, a first conveyance roller 201, a second conveyance roller 202, and a third conveyance roller 203 serving as conveyance rollers capable of conveying the sheet in a first direction from the inlet portion 26 toward a first discharge path 31 and capable of conveying the sheet in a second direction from the first discharge path 31 toward the inlet portion 26. That is, the inlet roller 29, the first conveyance roller 201, the second conveyance roller 202, and the third conveyance roller 203 are capable of conveying the sheet in the first direction and the second direction opposite to the first direction in the conveyance path, and are arranged in this order from the inlet portion 26 side in the first direction.

The first discharge path 31 is connected to the passing portion 35 of the conveyance path 28, and the first conveyance roller 36 is disposed at a connecting portion of these. The sheet passed on from the conveyance path 28 to the first discharge path 31 and discharged from the first discharge path 31 is stacked on the first tray 49 or guided to the processing portion B1. To be noted, each conveyance roller described above may be a different member capable of conveying a sheet such as a conveyance belt.

Layout of Sheet Introduction Path

The saddle path 32 and the upper conveyance path 30 that are branch paths are connected to the conveyance path 28 as illustrated in FIG. 2. The saddle path 32 and the upper conveyance path 30 are arranged in this order from the inlet portion 26 toward the first discharge path 31 in the first direction. In addition, the saddle path 32 branches downward from the conveyance path 28 in the vertical direction, and the upper conveyance path 30 branches upward from the conveyance path 28 in the vertical direction. A saddle path switching member 33 and an upper conveyance path switching member 34 serving as switching members that switch the conveyance direction of the conveyed sheet are respectively disposed at the respective branching portions between the conveyance path 28 and the saddle path 32 and between the conveyance path 28 and the upper conveyance path 30.

Branching Portion of Path

The upper conveyance path switching member 34 is constituted by a switching guide capable of moving to change the conveyance path of the sheet introduced from the inlet portion 26 to convey the sheet to the first discharge path 31 or the upper conveyance path 30, and is moved by a driving portion (not illustrated) such as an electromagnetic solenoid or a mini motor.

Upper Conveyance Path

The upper conveyance path 30 (print-out discharge path) in which a sheet other than a sheet to be discharged to the first discharge path 31 is conveyed branches from the conveyance path 28, and the upper conveyance path switching member 34 for guiding the sheet to the upper conveyance path 30 is provided at the path branching portion thereof. In addition, in the upper conveyance path 30, a fourth conveyance roller 204, a fifth conveyance roller 205, a sixth conveyance roller 206, and a second discharge roller 207 are provided in the upper conveyance path 30 as conveyance rollers that guide the sheet to the second tray 71. As a result of this, the sheet guided to the upper conveyance path 30 is discharged onto the second tray 71 (overflow tray) from an upper conveyance path discharge port 40.

The processing portion B1 is constituted by a processing tray 37 serving as a placement portion that places thereon a sheet conveyed through the first discharge path 31 provided downstream of the conveyance path 28 and accumulates a plurality of placed sheets for each copy, and a binding processing mechanism 47 that performs a binding process on the accumulated sheet bundle. Further, the processing portion B1 performs a binding process on the sheet bundle placed on the processing tray 37. The binding processing mechanism 47 is disposed below the conveyance path 28 in the vertical direction. As illustrated in FIG. 2, a step is formed in the first discharge path 31, and the processing tray 37 is disposed below the step. A first switchback path in which the sheet is guided onto the processing tray 37 after reversing the conveyance direction in a state in which part of the sheet has been discharged onto the first tray 49 through the discharge port 31a of the first discharge path 31 is provided between the first discharge path 31 and the processing tray 37.

Specifically, in the first discharge path 31, an upper conveyance roller 41 and a lower conveyance roller 48 that nip and convey the sheet are provided. The upper conveyance roller 41 and the lower conveyance roller 48 constitute a discharge roller pair 42 serving as a discharge portion. The upper conveyance roller 41 is capable of coming into and out of contact with and from the lower conveyance roller 48, and the sheet can be conveyed in a direction toward the first tray 49 and a direction opposite to this direction in a state in which the sheet is nipped between the upper conveyance roller 41 and the lower conveyance roller 48. Further, the sheet can be conveyed toward the processing tray 37 through the first switchback path by the upper conveyance roller 41 and the lower conveyance roller 48.

In addition, the upper conveyance roller 41 and the lower conveyance roller 48 (that is, the discharge roller pair 42) discharge the sheet or sheet bundle on the processing tray 37 onto the first tray 49 serving as a stacking tray (stacking portion) through the discharge port 31a. The discharge port 31a is a portion opening at a position above the lower conveyance roller 48 in the housing 27. Further, the discharge roller pair 42 discharges the sheet conveyed to the first discharge path 31 without passing the processing tray 37 onto the first tray 49 through the discharge port 31a.

The binding processing mechanism 47 includes a trailing end regulating portion 47a that abuts an end portion (trailing end) of the sheet and positions the sheet. A reversing portion 38 that conveys the sheet conveyed to the processing tray 37 by the upper conveyance roller 41 and the lower conveyance roller 48 toward the trailing end regulating portion 47a is disposed on the processing tray 37. Further, the binding processing mechanism 47 performs a binding process on an end portion of a sheet bundle constituted by a plurality of sheets which are placed on the processing tray 37 and a position of an end portion of which is regulated by the trailing end regulating portion 47a. In addition, the binding processing mechanism 47 includes a sheet bundle discharge mechanism that discharges the sheet bundle onto the first tray 49 after performing the binding process on the end portion of the sheet bundle.

To be noted, the binding processing mechanism 47 illustrated in FIG. 2 supports the sheet conveyed from the first discharge path 31 such that the sheet bridges the processing tray 37 and the first tray 49 provided downstream thereof. That is, the sheet conveyed from the first discharge path 31 is supported such that the leading end portion of the sheet is supported on the uppermost sheet on the first tray 49 provided on the downstream side, and the trailing end portion of the sheet is supported on the processing tray 37.

Saddle Path

The saddle path 32 for conveying the sheet to the saddle portion B2 described above is coupled to the conveyance path 28, and the saddle path switching member 33 for guiding the sheet to the saddle path 32 is provided at the path branching portion thereof. The sheet guided to the saddle portion B2 through the saddle path 32 is subjected to the half-folding process, and after being subjected to the folding process, is discharged to the saddle discharge unit 131 via a post-folding path guide 114, a post-second roller path guide 116, a pre-clamp guide 119, and a saddle discharge guide 124. In the present embodiment, the saddle discharge guide 124 serving as a discharge guide portion is used as an auxiliary guide for appropriately stacking the sheet on the saddle discharge unit 131.

Control Configuration

The outline of a control configuration of the image forming system 1000 will be described with reference to FIG. 3. First, the image forming apparatus A includes a controller 310, an operation portion 302, a conveyance controller 303, an image processing portion 304, a driving portion 305, and a communication portion 306. The controller 310 includes a central processing unit: CPU 311, a read-only memory: ROM 312, and a random access memory: RAM 313. The CPU 311 controls each component while reading out a program corresponding to a control procedure stored in the ROM 312. In addition, the RAM 313 stores work data and input data, and the CPU 311 performs control with reference to data stored in the RAM 313 on the basis of the program described above and the like.

The operation portion 302 is, for example, an operation panel provided in the image forming apparatus A and connected to the controller 310, and an operator operates the apparatus and performs various settings thereby. The conveyance controller 303 controls the various conveyance rollers that convey the sheet and the switching members that switch the conveyance path in the image forming apparatus A. The image processing portion 304 controls the image forming portion 3. The driving portion 305 controls various motors and the power source. The communication portion 306 communicably connects an external device 301 such as a personal computer and a communication portion 321 of the sheet processing apparatus B with the controller 310.

The sheet processing apparatus B includes a stacker controller 330, a conveyance controller 322, an end binding controller 323, a discharge process controller 324, and the communication portion 321. The stacker controller 330 includes a CPU 331, a ROM 332, and a RAM 333 similarly to the controller 310. The conveyance controller 322 controls the various conveyance rollers that convey the sheet and the switching members that switch the conveyance path in part of the sheet processing apparatus B other than the saddle portion B2. The end binding controller 323 controls the processing portion B1. The discharge process controller 324 controls various stacking trays onto which sheets are discharged and on which the discharged sheets are stacked. The communication portion 321 communicably connects the communication portion 306 of the image forming apparatus A and a communication portion 341 of the saddle portion B2 with the stacker controller 330. To be noted, the communication between the communication portion 306 and the communication portion 321 may be performed by wired communication or wireless communication.

The saddle portion B2 includes a saddle controller 350, a conveyance controller 342, a saddle binding controller 343, a half-folding controller 344, a folding reinforcement process controller 345, and a communication portion 341. The saddle controller 350 includes a CPU 351, a ROM 352, and a RAM 353 similarly to the controller 310. The conveyance controller 342 controls the various conveyance rollers that convey the sheet and the switching members that switch the conveyance path in the saddle portion B2. The saddle binding controller 343 controls the saddle binding processing portion 104. The half-folding controller 344 controls a half-folding processing mechanism C1. The folding reinforcement process controller 345 controls a folding reinforcement processing portion C2. The communication portion 341 communicably connects the communication portion 321 of the sheet processing apparatus B with the saddle controller 350. To be noted, although a configuration in which the saddle controller 350 communicates with the stacker controller 330 via the communication portions 341 and 321 is employed in the present embodiment, a configuration in which each unit is controlled by the same controller may be employed. In addition, although the conveyance controller 322, the end binding controller 323, the discharge process controller 324, the stacker controller 330, and the saddle controller 350 are provided as elements that control the sheet processing apparatus B in the present embodiment, a configuration in which each unit is controlled by the same controller may be employed.

Saddle Portion

The saddle portion B2 will be described with reference to FIGS. 2 and 4. The saddle portion B2 includes the half-folding processing mechanism C1 and the folding reinforcement processing portion C2. The half-folding processing mechanism C1 accumulates sheets conveyed from the conveyance path 28 for each copy to form a sheet bundle, performs a binding process on a center portion in the conveyance direction (center portion in a second conveyance direction that is a conveyance direction of the saddle path roller 100 serving as a second conveyance portion that will be described later) of the sheet bundle, and performs a half-folding process (hereinafter also referred to as a “magazine finish”) in which the sheet bundle is folded at a position subjected to the binding process. The folding reinforcement processing portion C2 is disposed downstream of the half-folding processing mechanism C1 in the conveyance direction of the sheet bundle (downstream in the first conveyance direction that is the conveyance direction of a saddle third roller pair 118 serving as a conveyance portion and a first conveyance portion that will be described later), and performs a square back process of forming a folding line on the spine of the sheet bundle subjected to the half-folding process or performs a folding reinforcement process (described in detail later) on the sheet bundle. Further, the saddle discharge unit 131 is disposed downstream of the folding reinforcement processing portion C2 in the first conveyance direction, and the sheet bundle subjected to a bookbinding process is stacked on the saddle discharge unit 131. To be noted, only the half-folding process of folding the center portion in the conveyance direction may be performed without performing the saddle binding process, the square back process, and further the folding reinforcement process after accumulating one sheet or a plurality of sheets for each copy.

Half-Folding Processing Mechanism

The half-folding processing mechanism C1 includes a leading end regulating stopper 109, a saddle binding processing portion (saddle binding stapling unit) 104, and a half-folding processing portion 112, accumulates sheets into a bundle shape, and performs the half-folding process and the saddle binding process. That is, the sheet conveyed from the conveyance path 28 to the saddle path 32 is conveyed to the saddle stacking tray 150 serving as an accumulation portion and a second accumulation portion by the saddle path roller 100 serving as a second conveyance portion. The saddle stacking tray 150 forms a sheet bundle by accumulating a plurality of sheets conveyed in the second conveyance direction by the saddle path roller 100 through the saddle path 32. The sheet bundle accumulated on the saddle stacking tray 150 is positioned at a predetermined position on the saddle stacking tray 150 by the leading end regulating stopper 109. The saddle binding processing portion 104 performs the binding process on a center portion in the conveyance direction (middle portion in the second conveyance direction) of the sheet bundle positioned by the leading end regulating stopper 109. The half-folding processing portion 112 includes the folding plate 112a and the folding roller pair 113, and by conveying the sheet bundle by the folding roller pair 113 while poking the vicinity of the position subjected to the binding process by the saddle binding processing portion 104 (center portion in the conveyance direction of the sheet bundle in the binding process) by the folding plate 112a, the sheet bundle is folded and conveyed such that the spine of the sheet bundle is on the downstream side in the conveyance direction. To be noted, the half-folding processing portion 112 is also capable of performing the half-folding process on a sheet bundle (or a single sheet) not subjected to the binding process. Here, the half-folding process is a process of folding the sheet bundle in half by forming a folding line near the center of the sheet bundle. The folding line formed by the half-folding processing portion 112 does not need to be positioned at the center of the sheet bundle, and may be displaced from the center within the range of the tolerance of parts. In addition, the folding position may be changed by user settings.

The saddle binding processing portion 104 is a mechanism that performs the binding process of moving a head unit and an anvil unit along the sheet center portion (line) while nipping the sheet bundle between the head unit and the anvil unit. In addition, for the half-folding processing portion 112, as illustrated in FIGS. 2 and 4, a configuration in which the sheet bundle is inserted in the nip of the folding roller pair 113 in pressure contact with each other by the folding plate 112a, and the sheet bundle is conveyed while being folded by the rotation of the folding roller pair 113 is employed.

Folding Reinforcement Processing Portion

The folding reinforcement processing portion C2 performs, on the sheet bundle, the square back process to form a square back shape along the folding line of the sheet bundle subjected to the half-folding process, or a folding reinforcement process to further perform folding reinforcement on the sheet bundle subjected to the half-folding process by nipping the sheet bundle by a roller pair. The folding reinforcement processing portion C2 includes a lower clamp unit 120 and an upper clamp unit 121 serving as a pair of clamp units (nipping units), a square back processing unit (first pressing unit) 134 including a pressing roller 123 serving as a first roller, and a folding reinforcement processing unit (second pressing unit) 500 including a pair of folding reinforcement rollers 501 and 502 serving as a pair of second rollers (see FIG. 20C and the like that will be described later). In the description below, a case of performing the square back process will be mainly described, and the folding reinforcement process will be described later. In addition, illustration of the folding reinforcement processing unit 500 is omitted in FIGS. 2, 4, and 7A to 9.

The lower clamp unit 120 and the upper clamp unit 121 relatively move along the thickness direction (direction in which a virtual line connecting rotational axes of the saddle third roller pair 118 extends, or direction orthogonal to a saddle third roller conveyance direction 118c of the saddle third roller pair 118) of the sheet bundle conveyed by the saddle third roller pair 118 that will be described later, and thus nip the sheet bundle and release the nipping of the sheet bundle. The pressing roller 123 moves along the width direction of the sheet bundle (direction orthogonal to the conveyance direction of the sheet bundle, front-rear direction of FIGS. 2 and 4), and thus presses the spine of the sheet bundle. Further, the folding reinforcement processing portion C2 performs a square back process of forming a corner on the spine of the sheet bundle by pressing, by the pressing roller 123, the spine of the sheet bundle nipped between the lower clamp unit 120 and the upper clamp unit 121 in a state in which the spine of the sheet bundle protrudes downstream with respect to the lower clamp unit 120 and the upper clamp unit 121 in the first conveyance direction. To be noted, examples of the “corner” described above include a curved surface, and refers to a boundary between the front cover and the spine of the sheet bundle and a boundary between the spine and the back cover of the sheet bundle. In addition, the “width direction of the sheet bundle” is a direction along the front-rear direction of the image forming apparatus A and the sheet processing apparatus B, and may be simply referred to as a “width direction” in the description below.

Specifically, the folding reinforcement processing portion C2 nips part of the sheet bundle from both sides in the vertical direction (thickness direction of the sheet bundle) by the lower clamp unit 120 and the upper clamp unit 121 in a state in which the spine of the sheet bundle subjected to the half-folding by the half-folding processing mechanism C1 protrudes downstream in the first conveyance direction. The pressing roller 123 presses the spine of the sheet bundle nipped between the lower clamp unit 120 and the upper clamp unit 121, while moving in the width direction of the sheet bundle orthogonal to the conveyance direction of the sheet bundle and to the thickness direction of the sheet bundle. In this manner, the folding reinforcement processing portion C2 performs the square back process of forming a corner on the spine of the sheet bundle. The square back process is a process of forming two corners on the spine of the sheet bundle by forming two streaks on the spine of the sheet bundle as illustrated in FIGS. 11C and 11D by crushing the spine of the sheet bundle illustrated in FIGS. 11A and 11B that will be described later by the pressing roller 123. The two corners on the spine of the sheet bundle are formed at positions between which the staples embedded in the sheet bundle in the binding process by the saddle binding processing portion 104 are positioned in the thickness direction of the sheet bundle. In addition, the two corners formed on the spine of the sheet bundle are formed at positions between which a folding line formed in the half-folding process by the half-folding processing portion 112 is positioned.

To be noted, a half-folding conveyance mechanism that conveys the sheet bundle subjected to the half-folding process by the half-folding processing mechanism C1 to the folding reinforcement processing portion C2 positioned downstream and stops the conveyance is disposed between the half-folding processing mechanism C1 and the folding reinforcement processing portion C2.

As described above, the processing portion B1 and the conveyance path 28 are arranged in approximately the horizontal direction, the saddle path 32 that guides the sheet to the saddle portion B2 is disposed in approximately the vertical direction, and the saddle stacking tray 150 that accumulates the sheets for each copy is disposed to approximately follow the vertical direction. As described above, by disposing the conveyance path 28 along a direction traversing the housing 27 and disposing the saddle path 32 and the saddle portion B2 along approximately the vertical direction, the apparatus can be made slimer, that is, the width of the apparatus in the horizontal direction can be reduced.

The saddle discharge unit 131 is disposed downstream of the saddle portion B2 in the conveyance direction of the sheet bundle, and accommodates a sheet bundle folded into a magazine shape. The saddle discharge unit 131 that is illustrated is disposed below the first tray 49 in the vertical direction. This is because the apparatus has specifications set in consideration of the fact that the frequency of use of the first tray 49 is higher than the frequency of use of the saddle discharge unit 131 and the first tray 49 is set to a height where the sheet on the tray is easy to pick up.

Configuration of Saddle Portion

Next, the configuration of each of the half-folding processing mechanism C1, the half-folding conveyance mechanism C3, and the folding reinforcement processing portion C2 constituting the saddle portion B2 will be described in more detail.

Details of Half-Folding Processing Mechanism

As illustrated in FIG. 2, the saddle path switching member 33 is switched so as to convey the sheet to the saddle path 32, and thus guides the sheet to the half-folding processing mechanism C1. A saddle inlet roller 101, a sorting portion 102, a trailing end pressing guide 103, a saddle binding processing portion 104, a pull-in separation roller 105, a half-folding processing portion 112, a first alignment roller 107, a second alignment roller 108, a leading end regulating stopper 109, and a leading end gripper 110 are disposed in this order from the upper side (upstream side) in the vertical direction that is the inlet side in the height direction of the half-folding processing mechanism C1.

The saddle inlet roller 101 conveys the sheet passed on thereto from the saddle path 32 by the saddle path roller 100 further downward. The sorting portion 102 moves the sheet conveyed downward from the saddle inlet roller 101 to the right side in FIG. 2, and accumulates the sheet on the saddle stacking tray 150. The trailing end pressing guide 103 presses the trailing end of the sheet stacked on the saddle stacking tray 150. The saddle binding processing portion 104 performs the binding process on the center portion in the conveyance direction of the sheet bundle accumulated on the saddle stacking tray 150. The pull-in separation roller 105 supports the conveyance of the sheet conveyed to the saddle stacking tray 150, and is a roller that pulls in this sheet toward the leading end regulating stopper 109. The pull-in separation roller 105 is disposed so as to be capable of coming into contact and out of contact with and from an opposing roller 105a.

The half-folding processing portion 112 includes a folding roller pair 113, the folding plate 112a serving as a pressing portion, and a roller guide 111. The folding roller pair 113 forms a folding line in the half-folding process. The folding plate 112a pushes the sheet into the nip portion of the folding roller pair 113. The roller guide 111 covers the folding roller pair 113. The first alignment roller 107 and the second alignment roller 108 convey the sheet conveyed to the saddle stacking tray 150, and aligns the sheet in the height direction of the sheet. The leading end regulating stopper 109 abuts the leading end (lower end) of the sheet conveyed thereto, and determines the position of the leading end of the sheet in the height direction. The leading end gripper 110 presses the leading end (lower end) of the sheet stacked on the leading end regulating stopper 109.

The saddle inlet roller 101 and the pull-in separation roller 105 are driven by the same motor. The trailing end pressing guide 103 is provided at a position opposing the sorting portion 102 with respect to the saddle stacking tray 150. The saddle binding processing portion 104 is disposed downstream of the sorting portion 102 and the trailing end pressing guide 103 and upstream of the pull-in separation roller 105.

The sheet conveyed from the saddle path 32 to the saddle portion B2 is conveyed to the leading end regulating stopper 109 moved to a position corresponding to the size by the saddle inlet roller 101. The pull-in separation roller 105 has an auxiliary conveyance function for precisely conveying the conveyed sheet to the leading end regulating stopper 109 in the saddle stacking tray 150. The roller guide 111 partially covers the folding roller pair 113 so as to suppress the leading end of the sheet getting caught at the folding roller pair 113 at this time and efficiently convey the sheet.

The first alignment roller 107 and the second alignment roller 108 cause the conveyed sheet to precisely abut the leading end regulating stopper 109, and thus performs an alignment process in the sheet height direction.

The sorting portion 102 moves the sheet conveyed to the leading end regulating stopper 109 to the trailing end pressing guide 103, and by pressing the trailing end (upper end) of the moved sheet by the trailing end pressing guide 103, preparation for receiving the next sheet is performed. At this time, the trailing end pressing guide 103 has moved to a position corresponding to the size and is standing by.

The leading end (trailing end) of the sheet bundle formed by stacking a plurality of sheets on the saddle stacking tray 150 is fixed by being gripped by the leading end gripper 110. In this state, the binding process is performed on the center portion in the second conveyance direction of the sheet bundle by the saddle binding processing portion 104. After the binding process, the leading end regulating stopper 109 is moved down while the leading end (lower end) of the sheet bundle is still gripped by the leading end gripper 110. At this time, by moving down the leading end regulating stopper 109 such that the position in the sheet where the sheet is pushed into the folding roller pair 113 by the folding plate 112a is a position of ½ of the sheet size, the sheet bundle is moved down from the binding position.

When performing the half-folding process, the roller guide 111 is retracted, the fixation by the leading end gripper 110 is released, and then the center portion of the sheet bundle is pushed into the nip portion of the folding roller pair 113 by the folding plate 112a. As a result of this, the half-folding process is performed on the sheet bundle.

The saddle inlet roller 101, the pull-in separation roller 105, the sorting portion 102, and the trailing end pressing guide 103 are controlled by the conveyance controller 342 (FIG. 3). In addition, the leading end regulating stopper 109, the leading end gripper 110, the saddle binding processing portion 104, the first alignment roller 107, and the second alignment roller 108 are controlled by the saddle binding controller 343 (FIG. 3). Further, the folding roller pair 113 and the folding plate 112a are controlled by the half-folding controller 344 (FIG. 3).

Half-Folding Conveyance Mechanism

The configuration of the half-folding conveyance mechanism C3 will be described with reference to FIGS. 2 and 4. The half-folding conveyance mechanism C3 is a mechanism that passes on the sheet bundle subjected to the half-folding process by the half-folding processing mechanism C1 to the folding reinforcement processing portion C2. Specifically, the half-folding conveyance mechanism C3 first conveys the sheet bundle subjected to the half-folding process as it is by the folding roller pair 113 such that the spine of the sheet bundle is positioned downstream of the fore edge in the conveyance direction, and passes on the sheet bundle to the post-folding path guide 114. The post-folding path guide 114 is disposed at a position downstream of the folding roller pair 113 in the conveyance direction and is disposed along a direction (approximately horizontal direction herein) bending downward in the vertical direction from a folding roller conveyance direction 113c (FIG. 2) following a line (first virtual line α2 that will be described later, FIG. 4) perpendicular to a straight line passing through the rotational center of each roller of the folding roller pair 113 serving as a first conveyance roller pair.

Here, as illustrated in FIG. 4, a straight line orthogonal to a first line α1 passing through the rotational centers of the folding roller pair 113 and to the width direction (direction orthogonal to the conveyance direction of the sheet bundle, front-rear direction of FIGS. 2 and 4) and passing through the nip of the folding roller pair 113 not nipping the sheet bundle is set as the first virtual line α2. In this case, the folding roller pair 113 is disposed such that the first virtual line α2 is parallel to the horizontal direction or is inclined upward in the vertical direction toward the downstream side in the conveyance direction with respect to the horizontal direction. In the present embodiment, the first virtual line α2 is inclined upward in the vertical direction toward the downstream side in the conveyance direction with respect to the horizontal direction. In contrast, the post-folding path guide 114 is provided to extend in a direction inclined with respect to the first virtual line α2, and is provided to extend approximately in the horizontal direction in the present embodiment.

The post-folding path guide 114 guides the conveyance of the sheet bundle, and guides the sheet bundle to a saddle second roller pair 115 positioned on the downstream side in the conveyance direction. A saddle second roller conveyance direction 115c that is a direction following a line perpendicular to a straight line passing through the rotational center of each roller of the saddle second roller pair 115 is provided along a direction inclined downward in the vertical direction toward the downstream side in the conveyance direction. The saddle second roller pair 115 is driven by the half-folding controller 344 and conveys the sheet bundle.

The sheet bundle conveyed by the saddle second roller pair 115 is passed on to the post-second roller path guide 116 disposed on the downstream side in the conveyance direction and disposed parallel to the saddle second roller conveyance direction 115c (FIG. 2), and is guided by the post-second roller path guide 116. In addition, the post-second roller path guide 116 includes a post-second roller path upper guide 116a that guides the upper surface of the sheet bundle and a post-second roller path lower guide 116b that guides the sheet bundle. A saddle conveyance sensor 117 is disposed at a position above the guide surface of the post-second roller path upper guide 116a and between the inlet port for the sheet bundle and the discharge port for the sheet bundle. The saddle conveyance sensor 117 detects the position of the leading end of the sheet bundle.

The post-second roller path guide 116 guides the conveyance of the sheet, and guides the sheet to the saddle third roller pair 118 positioned downstream in the conveyance direction. The saddle third roller conveyance direction 118c (FIG. 2) that is a direction following a line (second virtual line B2 that will be described next, FIG. 4) perpendicular to a straight line passing through the rotational center of each roller of the saddle third roller pair 118 is provided along a direction inclined downward in the vertical direction toward the downstream side in the conveyance direction.

The saddle third roller pair 118 serving as a conveyance portion and a conveyance roller pair is driven by the half-folding controller 344, and nips and conveys the sheet bundle subjected to the saddle binding process and the half-folding process such that the spine of the sheet bundle is positioned downstream of an end portion on the fore edge side in the conveyance direction. That is, the saddle third roller pair 118 conveys the sheet bundle such that the spine of the sheet bundle serves as the leading end. In the case where the direction in which the sheet bundle is conveyed by the saddle third roller pair 118 also serving as a first conveyance portion is set as the first conveyance direction (saddle third roller conveyance direction 118c), the saddle path roller 100 serving as a second conveyance portion that conveys the sheet to the half-folding processing mechanism C1 is positioned upstream of the saddle third roller pair 118 in the first conveyance direction. Further, the saddle path roller 100 conveys the sheet in a second conveyance direction different from the first conveyance direction at a position upstream of the saddle third roller pair 118 in the first conveyance direction. In the description below, the upstream side and the downstream side in the first conveyance direction (saddle third roller conveyance direction 118c) in which the sheet bundle is conveyed by the saddle third roller pair 118 may be sometimes simply referred to as the “upstream side” and the “downstream side”.

To be noted, 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 half-folding controller 344 controls this motor to control the driving of each roller pair. The saddle third roller pair 118 nips the sheet bundle subjected to half-folding by the half-folding processing portion 112, conveys the sheet bundle toward the folding reinforcement processing portion C2, and is positioned immediately upstream of the folding reinforcement processing portion C2.

Here, as illustrated in FIG. 4, a straight line that is orthogonal to a second line β1 passing through the rotational centers of the saddle third roller pair 118 and to the width direction and that passes the nip of the saddle third roller pair 118 not nipping the sheet bundle is set as a second virtual line B2. In this case, the saddle third roller pair 118 is provided such that the second virtual line B2 intersects with the first virtual line α2 and is inclined downward in the vertical direction toward the downstream side of the folding roller pair 113 in the conveyance direction.

In other words, the saddle third roller pair 118 is disposed such that the second virtual line β2 is inclined downward in the vertical direction toward the downstream side 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. Further, the folding roller pair 113 conveys the sheet bundle in the horizontal direction or a direction (folding roller conveyance direction 113c) inclined upward in the vertical direction toward the downstream side in the conveyance direction with respect to the horizontal direction. In contrast, the saddle third roller pair 118 conveys the sheet bundle in a direction (saddle third roller conveyance direction 118c) inclined downward in the vertical direction toward the downstream side in the conveyance direction with respect to the horizontal direction.

Therefore, in the case of the present embodiment, the half-folding conveyance path C4 serving as a third conveyance path in which the sheet bundle is conveyed 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 passed on to the saddle third roller pair 118. That is, the half-folding conveyance path C4 includes the post-folding path guide 114 and the post-second roller path guide 116, and the conveyance path between the post-folding path guide 114 and the post-second roller path guide 116 is bent. In other words, the direction in which the sheet bundle is guided by the post-second roller path guide 116 is inclined with respect to the direction in which the sheet bundle is guided by the post-folding path guide 114.

As described above, by making the conveyance direction of the sheet bundle by the folding roller pair 113 and the conveyance direction of the sheet bundle by the saddle third roller pair 118 different and bending the conveyance path between the post-folding path guide 114 and the post-second roller path guide 116, the width (length in the second conveyance direction, length in the left-right direction of FIG. 2) of the sheet processing apparatus B can be reduced, and thus the apparatus can be miniaturized. In addition, by discharging the sheet bundle downward by the saddle third roller pair 118 with the folding roller conveyance direction 113c serving as the sheet conveyance direction of the saddle third roller pair 118 directed diagonally downward, the sheet bundle processed by the saddle portion B2 can be discharged to a position lower in the apparatus. As a result of this, the saddle discharge unit 131 to which the sheet bundle processed by the saddle portion B2 is discharged can be disposed in a lower portion of the apparatus, and thus the amount by which the first tray 49 positioned above the saddle discharge unit 131 can be moved down can be increased. As a result of this, the sheet stacking amount of the first tray 49 can be increased. To be noted, in the case where “horizontal”, “vertical”, “parallel”, and the like are mentioned in the layout of the conveyance path guides for the sheet or sheet bundle and the conveyance direction of the sheet or sheet bundle, cases where an angle is formed with respect to the horizontal direction, the vertical direction, or the parallel direction due to the tolerance or the like are also included.

Details of Folding Reinforcement Processing Portion

The folding reinforcement processing portion C2 will be described by using FIGS. 5 to 10 with reference to FIGS. 2 and 4. As described above, the square back processing unit 134 including the lower clamp unit 120 and the upper clamp unit 121 serving as a pair of clamp portions and the pressing roller 123 is provided. A clamping mechanism C5 including the lower clamp unit 120 and the upper clamp unit 121 includes a pre-clamp guide 119 as illustrated in FIG. 5. The pre-clamp guide 119 is disposed at a position downstream of the saddle third roller pair 118 in the conveyance direction and is disposed along a direction bent downward in the vertical direction with respect to the saddle third roller conveyance direction 118c, and guides the conveyance of the sheet bundle.

The pre-clamp guide 119 includes a pre-clamp upper guide portion 119a serving as a first guide portion that guides the upper surface of the sheet bundle, and a pre-clamp lower guide portion 119b serving as a second guide portion that guides the lower surface of the sheet bundle. The pre-clamp upper guide portion 119a and the pre-clamp lower guide portion 119b are respectively integrally formed with a pair of first clamp portions 119c and 119d that will be described later, and are provided to extend upstream from upstream end portions of the first clamp portions 119c and 119d in the saddle third roller conveyance direction 118c. In addition, at a receiving position of the lower clamp unit 120 and the upper clamp unit 121 that will be described later, the first clamp portions 119c and 119d, the pre-clamp upper guide portion 119a, and the pre-clamp lower guide portion 119b are disposed at positions apart, in the thickness direction, from a line extending in the saddle third roller conveyance direction 118c from a nip of the saddle third roller pair 118, by a distance larger than a half of the maximum thickness of the sheet bundle that can be passed through the apparatus (the thickness of the sheet bundle after performing the half-folding process on the sheet bundle of the maximum thickness that can be conveyed in the apparatus). That is, the distance 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 (maximum thickness of the sheet bundle that can be subjected to the half-folding process by the half-folding processing mechanism C1). To be noted, at least one of the pre-clamp upper guide portion 119a and the pre-clamp lower guide portion 119b may be omitted.

The lower clamp unit 120 and the upper clamp unit 121 serving as a pair of clamp units relatively move along the thickness direction of the sheet bundle conveyed by the saddle third roller pair 118, and thus nips the sheet bundle and release the nipping. That is, the lower clamp unit 120 and the upper clamp unit 121 are relatively movable to a receiving position where the sheet bundle conveyed from the saddle third roller pair 118 can be received and a nipping position where the sheet bundle is nipped. Further, the lower clamp unit 120 and the upper clamp unit 121 move from the receiving position to the nipping position and thus nip 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.

The upper clamp unit 121 and the lower clamp unit 120 include the pair of first clamp portions 119c and 119d, and a pair of second clamp portions 142 and 143 positioned downstream of the pair of first clamp portions 119c and 119d in the conveyance direction. In the present embodiment, the lower clamp unit 120 serving as one clamp unit is fixed, and the upper clamp unit 121 serving as another clamp unit is movable. That is, the upper clamp unit 121 moves in a direction to approach the lower clamp unit 120, and thus the sheet bundle is nipped. To be noted, a configuration in which the upper clamp unit 121 is fixed and the lower clamp unit 120 is movable may be employed, and a configuration in which both of these are movable may be employed. In either case, in the square back process, an upper clamping surface (upper clamping pressing portion) 142a of the second clamp portion 142 of the upper clamp unit 121 that is a surface opposing the lower clamp unit 120 and a lower clamping surface (lower clamping pressing portion) 143a of the second clamp portion 143 of the lower clamp unit 120 that is a surface opposing the upper clamp unit 121 nip the sheet bundle (see FIGS. 5 and 11A to 11D).

The lower clamping surface 143a of the lower clamp unit 120 and the upper clamping surface 142a of the upper clamp unit 121 are respectively parallel to surfaces of the pair of first clamp portions 119c and 119d opposing each other. In addition, the pair of first clamp portions 119c and 119d and the pair of second clamp portions 142 and 143 are disposed downstream of the pre-clamp guide 119 in the conveyance direction of the sheet bundle. Further, the sheet bundle conveyed while being guided by the pre-clamp guide 119 is conveyed by a predetermined amount while further being guided by the pair of first clamp portions 119c and 119d and the pair of second clamp portions 142 and 143. To be noted, the pre-clamp lower guide portion 119b and the pre-clamp upper guide portion 119a are respectively fixed to the lower clamp unit 120 and the upper clamp unit 121. In the present embodiment, the pre-clamp upper guide portion 119a moves approximately in the vertical direction (thickness direction of the sheet bundle) together with the upper clamp unit 121.

Square Back Processing Unit

Next, an inner configuration of the square back processing unit 134 will be described with reference to FIGS. 5 to 10. The square back processing unit 134 presses, toward the lower clamp unit 120 and the upper clamp unit 121, the spine of the sheet bundle protruding downstream in the conveyance direction with respect to the lower clamp unit 120 and the upper clamp unit 121 in a state in which the sheet bundle is clamped by the lower clamp unit 120 and the upper clamp unit 121. In addition, the square back processing unit 134 performs the square back process to form a corner on the spine of the sheet bundle by moving in the width direction of the sheet bundle in the state of pressing the spine of the sheet bundle toward the lower clamp unit 120 and the upper clamp unit 121.

The square back processing unit 134 includes, as elements for supporting and moving the pressing roller (square back processing roller) 123 serving as a first roller, a unit frame 147, roller pressurizing portions 138a and 138b, pressurizing springs 145a and 145b, an upper movement regulating portion 139, and a lower movement regulating portion 140. The pressing roller 123 is disposed such that the outer peripheral surface thereof is in contact with a downstream end surface of each of the lower clamp unit 120 and the upper clamp unit 121 as illustrated in FIGS. 5 and 10. In addition, a roller shaft 141 is disposed on the radially inner side of the pressing roller 123, and the pressing roller 123 is rotatable with respect to the roller shaft 141 as illustrated in FIG. 6B.

As illustrated in FIGS. 6A and 6B, the unit frame 147 includes a pair of side plates 147a disposed on the two sides of the pressing roller 123, a rear side plate 147b disposed on the left side of the downstream side (FIG. 6B) in the first conveyance direction of the pressing roller 123, and an upper side plate 147c and a lower side plate 147d that are provided on the two sides of the pressing roller 123 in the rotational axis direction so as to be bent from two end portions of the rear side plate 147b. The unit frame 147 is configured in this manner, and thus accommodates the pressing roller 123 in a space enclosed by the side plates and exposes the pressing roller 123 on the upstream side in the first conveyance direction.

In the present embodiment, the rear side plate 147b, the upper side plate 147c, and the lower side plate 147d are formed integrally, and has an approximate C shape in section view as illustrated in FIG. 6B. To be noted, these may be formed as separate members, or may be formed integrally with the pair of side plates 147a. The two end portions of the roller shaft 141 of the pressing roller 123 are respectively rotatably supported by the upper side plate 147c and the lower side plate 147d. In addition, the upper side plate 147c and the lower side plate 147d are provided to extend upstream of the pressing roller 123 in the first conveyance direction, and the upper movement regulating portion 139 and the lower movement regulating portion 140 are respectively supported at distal end portions of the upper side plate 147c and the lower side plate 147d.

That is, the upper movement regulating portion 139 is provided at a distal end portion of a support shaft 139a fixed to the upper side plate 147c and provided to extend downward from the upper side plate 147c. In addition, the lower movement regulating portion 140 is provided at a distal end portion of a support shaft 140a fixed to the lower side plate 147d and provided to extend upward from the lower side plate 147d. In addition, the upper movement regulating portion 139 is a roller rotatably provided at the distal end portion of the support shaft 139a, and the lower movement regulating portion 140 is a roller rotatably provided at the distal end portion of the support shaft 140a. To be noted, although two lower movement regulating portions 140 are provided side by side in the present embodiment, the number of the lower movement regulating portions 140 may be one. In addition, two upper movement regulating portions 139 may be also provided. The upper movement regulating portion 139 and the lower movement regulating portion 140 are positioned on the respective sides of the pressing roller 123 in the rotational axis direction of the roller shaft 141.

The roller pressurizing portions 138a and 138b are each coupled to the roller shaft 141 from the outside in the roller thickness direction of the pressing roller 123 and from the downstream side in the conveyance direction. Pressurizing springs 145a and 145b are disposed between the roller pressurizing portions 138a and 138b and the rear side plate 147b of the unit frame 147, and the roller shaft 141 is urged by the pressurizing springs 145a and 145b. The roller shaft 141 is configured to be movable in the conveyance direction, and therefore the pressurizing force by which the pressing roller 123 pressurizes the spine of the sheet bundle by the urging force of the pressurizing springs 145a and 145b changes in accordance with the change in the protruding amount of the spine of the sheet bundle from the lower clamp unit 120 and the upper clamp unit 121 that will be described later.

In addition, the pressing roller 123 is urged by the pressurizing springs 145a and 145b via the roller shaft 141, and is therefore pressurized by the lower clamp unit 120 and the upper clamp unit 121. In contrast, the upper movement regulating portion 139 and the lower movement regulating portion 140 are disposed on the opposite side to the pressing roller 123 across the lower clamp unit 120 and the upper clamp unit 121 so as to respectively oppose the lower clamp unit 120 and the upper clamp unit 121 (FIG. 5). That is, the upper movement regulating portion 139 and the lower movement regulating portion 140 are disposed on the upstream side of the lower clamp unit 120 and the upper clamp unit 121 in the conveyance direction of the sheet bundle (first conveyance direction) so as to respectively oppose the upper clamp unit 121 and the lower clamp unit 120.

As illustrated in FIGS. 9 and 10, an end surface 120a on the upstream side of the lower clamp unit 120 is in contact with the lower movement regulating portion 140. In addition, an end surface 121a on the upstream side of the upper clamp unit 121 is in contact with the upper movement regulating portion 139. In the present embodiment, the lower movement regulating portion 140 and the upper movement regulating portion 139 are each a roller having a rotation shaft in a direction (up-down direction of FIG. 10, an approximately vertical direction in the present embodiment) orthogonal to the width direction of the sheet bundle and the conveyance direction of the sheet bundle, and respectively rotate in contact with the end surfaces 120a and 121a. As a result of this, upstream movement of the lower clamp unit 120 and the upper clamp unit 121 caused by the pressurizing force applied from the pressing roller 123 to the lower clamp unit 120 and the upper clamp unit 121 is restricted.

The conveyance amount of the sheet bundle conveyed by the saddle third roller pair 118 is counted by the folding reinforcement process controller 345 when the leading end of the sheet bundle is detected by the saddle conveyance sensor 117 described above, and the sheet bundle is stopped after being conveyed by a predetermined conveyance amount. Specifically, as illustrated in FIG. 11A that will be described later, the sheet bundle is stopped in a state in which the spine of the sheet bundle subjected to the half-folding protrudes downstream in the conveyance direction more than the upper clamp unit 121 and the lower clamp unit 120. In the present embodiment, in the square back process, the conveyance amount of the sheet bundle by the saddle third roller pair 118 is controlled, and thus the protruding amount of the spine of the sheet bundle from the upper clamp unit 121 and the lower clamp unit 120 is adjusted.

Upper Clamp Unit and Lower Clamp Unit

The upper clamp unit 121 moves from a receiving position for receiving the sheet bundle to a clamp holding position (nipping position) for holding the sheet bundle, thus the sheet bundle is pressurized between the upper clamp unit 121 and the lower clamp unit 120, and the sheet bundle is held by the upper clamping surface 142a and the lower clamping surface 143a. At this time, the leading end of the sheet bundle protrudes by a predetermined protrusion amount P1 from respective end surfaces 120c and 121b on the downstream side 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 the clamp holding in the conveyance direction as illustrated in FIG. 11B.

The upper clamp unit 121 operates by driving a clamp driving motor 132 (FIGS. 7A and 7B) by the folding reinforcement process controller 345. As illustrated in FIGS. 7A and 7B, the folding reinforcement processing portion C2 transmits a drive transmitted by a clamp driving train 133 constituted by a pulley, a belt, and a gear train further to a clamp driving link 122, and thus moves the upper clamp unit 121 connected to the clamp driving link 122 in the thickness direction of the sheet bundle. A plurality of second springs 802 serving as clamp springs that pressurize the sheet bundle are provided between the clamp driving link 122 and the upper clamp unit 121, and while the movement amount of the clamp driving link 122 remains constant, the contraction amount of the second spring 802 changes in accordance with the thickness of the sheet bundle, and thus the pressurizing force changes. Similarly, the clamp holding position described above also changes in accordance with the thickness of the sheet bundle. In addition, as will be described in detail later, the clamp holding position (nipping position) differs between a case of performing a square back process and a case of performing a folding reinforcement process, and 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. Further, the upper clamp unit 121 is moved to the second position in the square back process, and the upper clamp unit 121 is moved to the first position in the folding reinforcement process.

Folding Reinforcement Processing Portion

As illustrated in FIG. 11C that will be described later, the folding reinforcement processing portion C2 performs the square back process on the sheet bundle held between the lower clamp unit 120 and the upper clamp unit 121 in a state of protruding from the end surfaces 120c and 121b by the predetermined protrusion amount P1, by pressurizing the spine of the sheet bundle while moving, in the width direction of the sheet bundle in a scanning manner, the pressing roller 123 disposed on the downstream side in the conveyance direction.

During the square back process, the folding reinforcement processing unit 500 (see FIG. 12 and the like that will be described later) is moved by operating a driving motor 135 (FIG. 7B) by the folding reinforcement process controller 345. The square back processing unit 134 is coupled to the folding reinforcement unit 500 as will be described later, and is thus moved by the driving motor 135 via the folding reinforcement processing unit 500. The folding reinforcement processing unit 500 is coupled to a driving belt 137 illustrated in FIG. 8. The driving belt 137 is disposed in the width direction of the sheet bundle. In addition, the folding reinforcement processing unit 500 and the square back processing unit 134 are movable in the width direction of the sheet bundle along a guide rail 120b illustrated in FIG. 9 that will be described later. The driving belt 137 rotates by receiving a driving force transmitted from the driving motor 135 via a driving train 136 (FIG. 7B) constituted by a gear train. As a result of this, as will be described in detail later, the folding reinforcement processing unit 500 can be moved alone, and the square back processing unit 134 and the folding reinforcement processing unit 500 can be moved together, in a scanning manner in the width direction of the sheet bundle.

That is, in the present embodiment, a driving mechanism 135a that moves the square back processing unit 134 and the folding reinforcement processing unit 500 coupled together in the direction of the sheet bundle is provided. The driving mechanism 135a includes the driving motor 135 serving as a drive source, the driving belt 137, and the driving train 136. The driving motor 135 moves the folding reinforcement processing unit 500 in the width direction of the sheet bundle, and moves the square back processing unit 134 and the folding reinforcement processing unit 500 in the width direction of the sheet bundle in the case where the square back processing unit 134 is coupled to the folding reinforcement processing unit 500 via a coupling mechanism 600 (see FIG. 14 and the like) that will be described later.

To be noted, the home position of the square back processing unit 134 is provided on the front side (right side of FIG. 12 that will be described later (F side)) of the sheet processing apparatus B. For example, the square back process is performed on the sheet bundle by moving the folding reinforcement processing unit 500 coupled to the square back processing unit 134 positioned at the home position toward the rear side (left side of FIG. 12 (R side)). An unillustrated sensor is provided at the home position of the square back processing unit 134, and thus the position of the square back processing unit 134 can be detected. To be noted, the home position of the square back processing unit 134 may be set on the rear side, and the scanning movement of the square back processing unit 134 in the width direction may be performed from the rear side toward the front side. To be noted, in the case where, for example, the length of the sheet bundle in the width direction (F-R direction) is small (case where the sheet bundle is formed from sheets of a small size), the square back process may be performed on the second sheet bundle by moving the square back processing unit 134 from the front side toward the rear side after performing the square back process on the first sheet bundle by moving the square back processing unit 134 from the rear side toward the front side. In the case of this configuration, a home position may be provided on each of the front side and the rear side of the sheet processing apparatus B, and a home position sensor may be provided on each of the front side and the rear side.

In addition, in one square back 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 reciprocated in one square back process. For example, whether the pressing roller 123 is moved in one direction or reciprocated may be set in accordance with the number of sheets included in the sheet bundle or the type of the sheet. This setting may be automatically performed by the controller, or may be performed by an operator such as a user or a service worker. Further, whether the pressing roller 123 is moved in one direction or reciprocated may be arbitrarily settable by the operator in each square back process.

The lower clamp unit 120 includes the guide rail 120b formed along the width direction of the sheet bundle as illustrated in FIGS. 9 and 10. The lower movement regulating portion 140 moves along the guide rail 120b in engagement with the guide rail 120b when the square back processing unit 134 moves in the width direction of the sheet bundle. The guide rail 120b is formed in an approximate C shape in section view by combining a plurality of members as illustrated in FIG. 10 such that part of the lower movement regulating portion 140 formed in a roller shape can enter the guide rail 120b. The lower surface of the radially outer side of the lower movement regulating portion 140 is engaged with the lower surface of the guide rail 120b, and the outer peripheral surface of the lower movement regulating portion 140 is in contact with the end surface 120a. As a result of this, the movement in the sheet bundle thickness direction is restricted when the square back processing unit 134 moves. To be noted, the guide rail 120b may be a groove formed in one member provided on the upstream side of the lower clamp unit 120 in the conveyance direction.

After the square back process is completed, as will be described later, the driving motor 135 (FIG. 7B) is operated to move the square back processing unit 134 in the width direction via the folding reinforcement processing unit 500 and cancel the coupling between the folding reinforcement processing unit 500 and the square back processing unit 134, and thus the folding reinforcement processing unit 500 is moved alone. As a result of this, the square back processing unit 134 and the folding reinforcement processing unit 500 are retracted from the conveyance path for the sheet bundle. Further, the clamp driving motor 132 (FIGS. 7A and 7B) is operated to move the upper clamp unit 121 in a direction away from the sheet bundle (FIG. 11D described later). As a result of this, the sheet bundle can be conveyed further downstream. To be noted, the sheet bundle can be also discharged without performing the square back process described above or the folding reinforcement process that will be described later.

Discharge Portion

As illustrated in FIG. 2, the sheet bundle having passed the saddle portion B2 is conveyed toward the saddle discharge guide 124 disposed further downstream of the pressing roller 123 in the first conveyance direction, by the saddle third roller pair 118. The saddle discharge guide 124 is supported to be swingable about a first fulcrum 124b including a rotation shaft parallel to the rotational axis of each roller of the saddle third roller pair 118. The first fulcrum 124b is positioned above an extension line of the conveyance direction (first conveyance direction, saddle third roller conveyance direction 118c) of the sheet bundle by the saddle third roller pair 118. Further, the saddle discharge guide 124 is disposed to hang down in the vertical direction from the first fulcrum 124b.

In addition, the saddle discharge guide 124 is formed such that the side surface thereof on the upstream side in the first conveyance direction is inclined upstream in the first conveyance direction from the first fulcrum 124b toward a middle portion 124a in the vertical direction. In addition, the side surface of the saddle discharge guide 124 on the upstream side in the first conveyance direction is inclined downstream in the first conveyance direction from the middle portion 124a toward the lower end in 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 such that the middle portion 124a in the vertical direction protrudes upstream in the first conveyance direction as compared with the other part. Further, in the side surface of the saddle discharge guide 124 on the upstream side in the first conveyance direction, a guide surface 124d is provided in a portion from the middle portion 124a to the lower end.

The guide surface 124d is positioned below an extension line obtained of the saddle third roller conveyance direction 118c, comes into contact with the sheet bundle conveyed by the saddle third roller pair 118, and guides the sheet bundle downward. The saddle discharge guide 124 is capable of pivoting about the first fulcrum 124b when the sheet bundle comes into contact with the guide surface 124d. To be noted, depending on the stiffness of the sheet bundle, there is a case where the sheet bundle does not come into contact with the guide surface 124d of the saddle discharge guide 124, and even in the case where the contact occurs, since the amount of the pivot changes depending on the stiffness, the saddle discharge guide 124 does not necessarily pivot.

In addition, a second fulcrum 124c is provided at a lower end portion of the saddle discharge guide 124, and a saddle discharge roller 125 that will be described later is coupled to the lower end portion of the saddle discharge guide 124 so as to be pivotable about the second fulcrum 124c. The second fulcrum 124c is positioned below the guide surface 124d, and includes a pivot shaft parallel to the pivot shaft of the first fulcrum 124b.

When the sheet bundle continues to be conveyed by the saddle third roller pair 118, the sheet bundle is passed onto a saddle discharge unit 131 disposed downstream of the square back processing unit 134 in the first conveyance direction and below the saddle discharge guide 124 in the vertical direction. 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.

The saddle discharge upstream belt 127 is positioned below the guide surface 124d of the saddle discharge guide 124, and guides and conveys the sheet bundle guided downward by the guide surface 124d further downstream. The saddle discharge upstream belt 127 is inclined downward in the vertical direction toward the downstream side in the conveyance direction. The saddle discharge downstream belt 129 serving as a sheet bundle discharge portion receives the sheet bundle conveyed from the saddle discharge upstream belt 127, and further guides and conveys the received sheet bundle downstream. The saddle discharge downstream belt 129 is inclined upward in the vertical direction toward the downstream side in the conveyance direction. Therefore, the sheet bundle guided to the saddle discharge upstream belt 127 by the guide surface 124d is conveyed by the saddle discharge upstream belt 127 in a direction inclined downward in the vertical direction, and is then conveyed by the saddle discharge downstream belt 129 in a direction inclined upward in the vertical direction.

In addition, the saddle discharge upstream sensor 128 that detects the sheet bundle on the upstream side is disposed on the upstream side in a conveyable region of the saddle discharge upstream belt 127, and the saddle discharge downstream sensor 130 that detects the sheet bundle on the downstream side is disposed on the upstream side in a conveyable region of the saddle discharge downstream belt 129.

The sheet bundle passed on 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 is then stacked. The saddle discharge upstream belt 127 nips the sheet bundle at a nip point between the saddle discharge upstream belt 127 and the saddle discharge roller 125 described above on the downstream side in the conveyance direction. The sheet bundle present on the saddle discharge upstream belt 127 is configured to suppress opening on the opening portion side (fore edge side) at this nip point. The position of this nip point can change about a second fulcrum 124c in accordance with the thickness of the sheet bundle.

While the succeeding sheet bundle is processed, the preceding sheet bundle is conveyed upstream in the conveyance direction by the saddle discharge upstream belt 127, and is stopped after a predetermined conveyance amount since being detected by the saddle discharge upstream sensor 128 or the saddle discharge downstream sensor 130. The position where the preceding sheet bundle stops corresponds to a position where the opening on the opening portion side of the preceding sheet bundle can be suppressed at the nip point between the saddle discharge upstream belt 127 and the saddle discharge roller 125, and to a position where the succeeding sheet comes into contact with the upper surface of the preceding sheet bundle when being discharged. That is, in the present embodiment, the succeeding sheet bundle is stacked on the preceding sheet bundle such that the sheet bundles partially overlap each other in the saddle discharge unit 131.

As described above, the saddle discharge unit 131 discharges the succeeding sheet bundle onto the upper surface of the preceding sheet bundle without entering the opening portion of the preceding sheet bundle, and thus the sheet bundles are stably stacked without occurrence of a failure such as getting caught by the preceding sheet bundle, getting curled against the preceding sheet bundle, or pushing out the preceding sheet bundle. That is, by appropriately changing the conveyance amount described above in accordance with the size of the sheet bundle, the succeeding sheet bundle can be stably stacked on the preceding sheet bundle.

The saddle discharge port 126 is disposed at a position downstream of the saddle discharge guide 124 in the first conveyance direction and between the saddle discharge upstream belt 127 and the saddle discharge downstream belt 129. The sheet bundle conveyed to the saddle discharge unit 131 passes through the saddle discharge port 126 to be discharged to the outside of the sheet processing apparatus B, and thus the user can easily access the discharged sheet bundle.

To be noted, in the case where another apparatus is present on the downstream side of the saddle discharge unit 131, the sheet bundle can be passed on to the downstream apparatus by continuing the conveyance without the stacking. In addition, in the present embodiment, a discharge cover 151 serving as a cover member is provided on the outside of the saddle discharge port 126. The discharge cover 151 is disposed so as not to interrupt discharge of the sheet bundle from the saddle discharge port 126 and such that an operator such as a user cannot access the inside of the apparatus through the saddle discharge port 126.

Control of Square Back Process

Next, the control of the square back process of the present embodiment will be described with reference to FIGS. 11A to 11D. As described above, the folding reinforcement processing portion C2 performs the square back process of forming a corner on the spine of the sheet bundle subjected to the saddle binding process and the half-folding process. In the description below, a control mode for performing the square back process may be referred to as a square back processing mode, and a control mode for performing the folding reinforcement process may be referred to as a folding reinforcement processing mode. In addition, the half-folding controller 344 illustrated 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 by the same driving system.

The square back processing mode will be described. The square back processing mode is a mode in which a corner is formed on the spine of a sheet bundle Sb by pressing the pressing roller 123 against the spine of the sheet bundle Sb. The half-folding controller 344 conveys the sheet bundle Sb subjected to the half-folding to the gap between the upper clamp unit 121 and the lower clamp unit 120 in the separated state in response to detection of the leading end of the sheet bundle Sb by the saddle conveyance sensor 117. Then, as illustrated in FIG. 11A, the half-folding controller 344 stops the conveyance of the sheet bundle Sb in a state in which a spine Ssp of the sheet bundle Sb protrudes further downstream in the first conveyance direction than the end surfaces 121b and 120c on the downstream side in the first conveyance direction of the upper clamp unit 121 and the lower clamp unit 120.

In this state, the folding reinforcement process controller 345 drives the clamp driving motor 132 (FIGS. 7A and 7B) and thus moves the upper clamp unit 121 toward the lower clamp unit 120, and as illustrated in FIG. 11B, the sheet bundle Sb is nipped by the upper clamp unit 121 and the lower clamp unit 120. At this time, the spine Ssp of the sheet bundle Sb protrudes further downstream than the end surfaces 121b and 120c on the downstream side in the first conveyance direction of the upper clamp unit 121 and the lower clamp unit 120 by P1.

Next, the folding reinforcement process controller 345 operates the driving motor 135 (FIG. 7B), and thus moves the square back processing unit 134 in the width direction of the sheet bundle Sb via the folding reinforcement processing unit 500. At this time, as illustrated in FIG. 11C, the pressing roller 123 of the square back processing unit 134 moves in the width direction while pressurizing the spine Ssp of the sheet bundle Sb, and thus the square back process is performed on the spine Ssp of the sheet bundle Sb. Then, as illustrated in FIG. 11D, the folding reinforcement process controller 345 drives the clamp driving motor 132 (FIGS. 7A and 7B), thus separates the upper clamp unit 121 from the lower clamp unit 120, and releases the nipping of the sheet bundle Sb. In the first mode, the square back process is finished here, and the discharge operation of the sheet bundle Sb described above is performed.

To be noted, as described above, since the pressing roller 123 strongly orthogonally presses the spine of the sheet bundle in the square back process, it is desired that the saddle binding process is performed on the sheet bundle before performing the square back process. This is because in the case where the square back process is performed on the sheet bundle not subjected to the saddle binding process, a sheet on the inside of the sheet bundle is displaced by the pressing force of the pressing roller 123. In contrast, in the folding reinforcement process described later, since the spine of the sheet bundle is just nipped by the pair of folding reinforcement rollers 501 and 502, the folding reinforcement process may be performed on the sheet bundle subjected to the half-folding process without performing the binding process. That is, the sheet processing apparatus B of the present embodiment performs the folding reinforcement process on the sheet bundle subjected to the half-folding process or the sheet bundle subjected to the saddle binding process and the half-folding process, and performs the square back process on the sheet bundle subjected to the saddle binding process and the half-folding process. The sheet bundle is a bundle of sheets on which images have been formed by the image forming portion 3.

Movement Configuration of Folding Reinforcement Processing Unit and Square Back Processing Unit

Next, the movement configuration of the folding reinforcement processing unit 500 and the square back processing unit 134 will be described with reference to FIGS. 12 to 19B. As described above, the sheet bundle Sb subjected to the square back process by the square back processing unit 134 has a corner formed on the spine thereof, and thus the opening thereof after being discharged is suppressed. Meanwhile, also in the case where the square back process is not performed, that is, in the case where a product not having the corner on the spine is desired, suppressing the opening of the sheet bundle is desired for suppressing a stacking failure of the sheet bundle after the discharge of the sheet bundle. Therefore, in the sheet processing apparatus B of the present embodiment, the folding reinforcement processing unit 500 that performs folding reinforcement on the sheet bundle is provided in addition to the square back processing unit 134. The folding reinforcement processing unit 500 performs the pressing process on the folding line of the sheet bundle by moving in the width direction of the sheet bundle while nipping the folding line of the sheet bundle. As a result of providing the folding reinforcement processing unit 500 as described above, the opening of the sheet bundle subjected to the half-folding process or the saddle binding process and the half-folding process can be suppressed more also in the case of not performing the square back process.

The product not having the corner on the spine mentioned herein is, for example, a product that has been subjected to the half-folding process or the saddle binding process and the half-folding process but is not instructed to be subjected to the square back process by the user, or a product on which the square back process cannot be performed. For example, the product on which the square back process cannot be performed is a product obtained by performing the half-folding process or the saddle binding process and the half-folding process on a sheet bundle including a number of sheets less than the lower limit (for example, five) on which the square back process can be performed. In the case where a product like this is desired, although the square back process cannot be performed on the sheet bundle of a small number of sheets even in the case where the sheet bundle is constituted by sheets of a large grammage, for example, a case of performing the half-folding process on four sheets of 100 g/m², the opening of the sheet bundle can be suppressed by performing the folding reinforcement process as in the present embodiment.

The folding reinforcement processing unit 500 includes a pair of folding reinforcement rollers 501 and 502 that perform the folding reinforcement process of nipping the sheet bundle protruding downstream in the conveyance direction (downstream in the saddle third roller conveyance direction 118c (FIG. 4)) with respect to the lower clamp unit 120 and the upper clamp unit 121 while moving in the width direction of the sheet bundle in a state in which the sheet bundle is nipped by the lower clamp unit 120 and the upper clamp unit 121.

The folding reinforcement processing unit 500 is disposed downstream of the lower clamp unit 120 and the upper clamp unit 121 similarly to the square back processing unit 134, and moves in the width direction of the sheet bundle similarly to the square back processing unit 134. That is, in the present embodiment, the square back process and the folding reinforcement process can be selectively performed on the sheet bundle nipped by the lower clamp unit 120 and the upper clamp unit 121. Further, in the present embodiment, as described above, the folding reinforcement processing unit 500 is configured to be moved in the width direction by operating the driving motor 135 (FIG. 7B), and as a result of coupling the square back processing unit 134 to the folding reinforcement processing unit 500, both units can be moved in the width direction by driving the driving motor 135.

In addition, in the present embodiment, as will be described in detail later, to perform two processes of the square back process and the folding reinforcement process, the position where the pair of folding reinforcement rollers 501 and 502 nip the sheet bundle in the folding reinforcement process is set to be downstream of the position where the surface of the pressing roller 123 comes into contact with the spine of the sheet bundle in the square back process in the conveyance direction. As a result of this, even when the folding reinforcement processing unit 500 moves together with the square back processing unit 134 when performing the square back process, the sheet bundle pressurized by the pressing roller 123 does not interfere with the folding reinforcement processing rollers 501 and 502. In addition, when performing the folding reinforcement process, the coupling between the folding reinforcement processing unit 500 and the square back processing unit 134 is cancelled, the folding reinforcement processing unit 500 is moved alone, and therefore the pressing roller 123 does not interfere with the sheet bundle being subjected to the folding reinforcement. In the description below, the configuration of coupling and coupling cancellation between the folding reinforcement processing unit 500 and the square back processing unit 134 will be described in detail.

Coupling Mechanism

First, the coupling mechanism 600 of the folding reinforcement processing unit 500 and the square back processing unit 134 will be described with reference to FIGS. 12 to 17B. FIG. 12 illustrates a state in which the coupling between the square back processing unit 134 and the folding reinforcement processing unit 500 is cancelled and in which the square back processing unit 134 and the folding reinforcement processing unit 500 is at the home position. In the present embodiment, in a movable range of each unit, the home position of the square back processing unit 134 is set at an end portion on the F side (front side), and the home position of the folding reinforcement unit 500 is set at an end portion on the R side (rear side).

That is, the home position of the square back processing unit 134 is a position displaced in the width direction of the sheet bundle from a passage region that a sheet bundle of the maximum size conveyed downstream in the conveyance direction of the lower clamp unit 120 and the upper clamp unit 121 passes. In the present embodiment, the home position of the square back processing unit 134 is displaced toward the F side from the passage region. In contrast, the home position of the folding reinforcement processing unit 500 is displaced in the width direction of the sheet bundle from the passage region toward the opposite side to the home position of the square back processing unit 134. In the present embodiment, the home position of the folding reinforcement processing unit 500 is set at a position displaced from the passage region toward the R side.

As described above, in the present embodiment, at the home position, the square back processing unit 134 and the folding reinforcement processing unit 500 are respectively positioned on the F side and the R side of the region that the sheet bundle of the maximum size passes. Therefore, in a state in which each unit is at the home position, the sheet bundle can be discharged downstream in the conveyance direction through a gap between the lower clamp unit 120 and the upper clamp unit 121. To be noted, the home position of the square back processing unit 134 may be set on the R side, and the home position of the folding reinforcement processing unit 500 may be set on the F side. In addition, the home positions of both units may be set on the R side or the F side as long as the sheet bundle can be discharged through the gap between the lower clamp unit 120 and the upper clamp unit 121.

FIG. 13 is a perspective view of the folding reinforcement processing unit 500 at the home position as viewed from the F side. FIG. 14 is a perspective view of the square back processing unit 134 at the home position, the coupling mechanism 600, and a coupling cancellation mechanism 700 as viewed from the R side. As illustrated in FIG. 13, the folding reinforcement processing unit 500 includes engagement pins 503 and 504 serving as first engagement portions. The engagement pins 503 and 504 are provided more on the F side than the folding reinforcement rollers 501 and 502 of the folding reinforcement processing unit 500.

Meanwhile, the coupling mechanism 600 coupling the square back processing unit 134 and the folding reinforcement processing unit 500 is supported by the square back processing unit 134. The coupling mechanism 600 includes hooks 601 and 602 serving as second engagement portions capable of engaging with the engagement pins 503 and 504. The hook 601 is capable of engaging with the engagement pin 503. The hook 602 is capable of engaging with the engagement pin 504. To be noted, the first engagement portions and the second engagement portions are not limited to the pins and hooks, and other elements may be used instead as long as the coupling can be cancelled by the coupling cancellation mechanism 700 that will be described later. For example, the first engagement portion may be a member provided with a hole or a groove capable of engaging with the hook instead of a pin. In addition, the second engagement portion may be a rod-like member such as a pin or a plate-like member instead of the hook. In this case, the rod-like member or the plate-like member is configured to be capable of engaging with the R-side surface of the pin and retracting from the engagement position in the case where the first engagement portion is a pin, and is configured to be capable of entering or retracting from the hole or the groove in the case where the first engagement portion is a member provided with a hole or a groove.

In addition, the coupling mechanism 600 is provided with a link 603 coupling the hooks 601 and 602 to each other to integrally pivot the hooks 601 and 602. A spring 604 is engaged with the hook 602, and urges the hook 602 such that the hook 602 is positioned at a coupled position. Since the hook 601 is coupled to the hook 602 via the link 603, the hook 601 is also positioned at a coupled position by the urging force of the spring 604. The coupled position is a position in a state in which the hooks 601 and 602 are engaged with the engagement pins 503 and 504 as illustrated in FIGS. 17A and 17B that will be described later, and as illustrated in FIG. 14, the hooks 601 and 602 are configured to be positioned at the coupled position by the urging force of the spring 604 even in a state in which the hooks 601 and 602 are not engaged with the engagement pins 503 and 504.

More detailed description will be given below. The hook 601 is disposed at a position that is above the hook 602 and that corresponds to the engagement pin 503, and is pivotably supported via a pivot shaft 601b with respect to the unit frame 147 of the square back processing unit 134. The pivot shaft 601b pivotably supports a portion of the hook 601 on the root end side thereof (on the F side thereof). An inclined portion 601a that is inclined upward toward the R side at the coupled position is formed at a distal end portion (R-side end portion) of the hook 601. In addition, an engagement portion 601c including an engagement surface facing toward the F side at the coupled position is formed at a position more on the F side than the inclined portion 601a at the distal end portion of the hook 601. A coupling shaft 601d coupled to the link 603 is provided at a middle portion of the hook 601, that is, between the pivot shaft 601b and the engagement portion 601c.

The hook 602 is disposed at a position corresponding to the engagement pin 504, and is pivotably supported via a pivot shaft 602b with respect to the unit frame 147 of the square back processing unit 134. The pivot shaft 602b pivotably supports a portion of the hook 602 on the root end side thereof (on the F side thereof). An inclined portion 602a that is inclined upward toward the R side at the coupled position is formed at a distal end portion (R-side end portion) of the hook 602. In addition, an engagement portion 602c including an engagement surface facing toward the F side at the coupled position is formed at a position more on the F side than the inclined portion 602a at the distal end portion of the hook 602. A coupling shaft 602d coupled to the link 603 is provided between the pivot shaft 602b and the engagement portion 602c. In addition, a spring 604 serving as an urging portion that urges the hook 602 in a direction to pivot in a counterclockwise direction of FIG. 12 about the pivot shaft 602b of the hook 602 is provided between the hook 602 and the unit frame 147. In the present embodiment, the spring 604 that is a tensile spring is provided between part of the unit frame 147 and a portion of the hook 602 lower than the pivot shaft 602b.

In the case of coupling the folding reinforcement processing unit 500 to the square back processing unit 134, the folding reinforcement processing unit 500 is moved by the driving motor 135 to the F side of the sheet processing apparatus B toward the square back processing unit 134 positioned at the home position as illustrated in FIG. 15. In this case, as illustrated in FIG. 16A, as a result of the movement of the folding reinforcement processing unit 500, the engagement pin 503 abuts the inclined portion 601a of the hook 601, and the engagement pin 504 abuts the inclined portion 602a of the hook 602.

Then, as illustrated in FIG. 16B, as a result of the folding reinforcement processing unit 500 further moving toward the F side, the inclined portion 601a of the hook 601 is pushed by the engagement pin 503, and thus the hook 601 pivots rightward (in the clockwise direction) in the drawing about the pivot shaft 601b. The inclined portion 602a of the hook 602 is pushed by the engagement pin 504, and thus the hook 602 pivots rightward in the drawing about the pivot shaft 602b. That is, the folding reinforcement processing unit 500 is moved closer to the square back processing unit 134, and thus the hooks 601 and 602 are lifted up by the engagement pins 503 and 504. At this time, the urging force of the spring 604 acts on the hook 602 and also on the hook 601 via the link 603, and the hooks 601 and 602 each pivot in the clockwise direction against the urging force of the spring 604 as a result of the inclined portions 601a and 602a being pushed by the engagement pins 503 and 504.

As illustrated in FIG. 17A, as a result of the folding reinforcement processing unit 500 further moving toward the F side, the hooks 601 and 602 climb over the engagement pins 503 and 504, and thus the engagement between the hooks 601 and 602 and the engagement pins 503 and 504 is complete. That is, when the engagement pins 503 and 504 pass under the distal end portions of the hooks 601 and 602 lifted up by the engagement pins 503 and 504 and reach positions more on the F side than the engagement portions 601c and 602c of the hooks 601 and 602, the hooks 601 and 602 pivot in the counterclockwise direction about the pivot shafts 601b and 602b by the urging force of the spring 604, and thus return to the coupled position. As a result of this, the folding reinforcement processing unit 500 and the square back processing unit 134 are coupled to each other.

When the folding reinforcement processing unit 500 is moved toward the R side by the driving motor 135 in this state, 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 illustrated in FIG. 17B, when the folding reinforcement processing unit 500 is moved, the square back processing unit 134 moves together with the folding reinforcement processing unit 500 as a result of the engagement between the engagement pins 503 and 504 and the hooks 601 and 602.

By coupling the folding reinforcement processing unit 500 and the square back processing unit 134 to each other as described above, the movement of the two units in the width direction can be performed by a single drive source. Specifically, the folding reinforcement process controller 345 (FIG. 3) moves the folding reinforcement processing unit 500 alone in the width direction of the sheet bundle by driving the driving motor 135 in the case of performing the folding reinforcement process. In contrast, in the case of performing the square back process, the folding reinforcement process controller 345 moves the folding reinforcement processing unit 500 toward the square back processing unit 134 positioned at the home position, and couples the square back processing unit 134 to the folding reinforcement processing unit 500 by the coupling mechanism 600. Then, the square back processing unit 134 and the folding reinforcement processing unit 500 are moved in the width direction of the sheet bundle. As described above, the folding reinforcement processing unit 500 can be moved alone, or the folding reinforcement processing unit 500 and the square back processing unit 134 can be moved in a coupled state, by the driving motor 135 that is a single drive source. Therefore, drive sources for moving the respective units do not have to be provided, and thus the size and cost of the apparatus can be reduced.

Coupling Cancellation Mechanism

Next, the coupling cancellation mechanism 700 that cancels the coupling between the folding reinforcement processing unit 500 and the square back processing unit 134 for moving the folding reinforcement processing unit 500 alone in the folding reinforcement process as described above will be described with reference to FIGS. 18A to 19B. The coupling cancellation mechanism 700 is a mechanism that cancels the coupling between the square back processing unit 134 and the folding reinforcement processing unit 500 coupled by the coupling mechanism 600 described above. The coupling cancellation mechanism 700 includes a rack 704 serving as an operation portion that operates the hooks 601 and 602 in a direction to cancel the engagement between the engagement pins 503 and 504 and the hooks 601 and 602 in the engaged state, and a driving motor 701 serving as a drive source for coupling cancellation that drives the rack 704.

The coupling cancellation mechanism 700 is disposed at a position on the F side of and adjacent to the square back processing unit 134 positioned at the home position. The driving motor 701 is supported by a frame C21 of the folding reinforcement processing portion C2, and is disposed on the rear side of a motor frame 701a fixed to the frame C21 as viewed from the discharge port side of the sheet bundle. A through hole 701b is provided in the motor frame 701a, and a drive shaft 701c of the driving motor 701 protrudes toward the discharge port side from this through hole 701b. A belt 702 is stretched from a pulley 701d fixed to the drive shaft 701c to a pulley 703a (see FIG. 14) fixed to a gear 703 that engages 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 as a result of driving the driving motor 701.

The rack 704 is supported to be movable in the width direction with respect to the motor frame 701a. The rack 704 includes a teeth portion 704a that engages with the gear 703, and a pressing portion 704b that abuts an 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 pivot shaft 602b. As described above, when the gear 703 is rotationally driven by the driving motor 701, the rack 704 moves in the width direction due to the engagement between the gear 703 and the teeth portion 704a. Then, the pressing portion 704b provided at an end portion of the rack 704 on the R side abuts the abutting portion 602e or is separated from the abutting portion 602e.

Cancellation of the coupling between the square back processing unit 134 and the folding reinforcement processing unit 500 is performed by the coupling cancellation mechanism 700 described above in a state in which the square back processing unit 134 and the folding reinforcement processing unit 500 are moved to the F side as illustrated in FIG. 18A. The position where the coupling cancellation is performed is the home position of the square back processing unit 134. That is, the coupling cancellation mechanism 700 cancels the coupling between the square back processing unit 134 and the folding reinforcement processing unit 500 in a state in which the square back processing unit 134 coupled to the folding reinforcement processing unit 500 is at the home position.

Specifically, in a state in which each unit is at this position, the driving motor 701 is driven to rotate the drive shaft 701c rightward (in the clockwise direction) in the drawing. Then, the gear 703 rotates rightward in the drawing via the pulley 701d, the belt 702, and the pulley 703a, and the rack 704 engaged with the gear 703 moves from the F side toward the R side as illustrated in FIG. 18B. Then, the pressing portion 704b of the rack 704 abuts the abutting portion 602e of the hook 602.

When the rack 704 further moves to the R side, the abutting portion 602e is pressed by the pressing portion 704b, and thus the hook 602 pivots rightward in the drawing about the pivot shaft 602b against the urging force of the spring 604 as illustrated in FIG. 19A. As a result of the pivoting of the hook 602, the hook 601 coupled thereto via the link 603 also pivots about the pivot shaft 601b. That is, the hook 602 pivots in the clockwise direction about the pivot shaft 602b, and thus the link 603 coupled to a position on the hook 602 more on the distal end side than the pivot shaft 602b is lifted up. Since the link 603 is coupled to a position on the hook 601 more on the distal end side than the pivot shaft 601b, the hook 601 is lifted up by the link 603, and therefore the hook 601 pivots in the clockwise direction about the pivot shaft 601b. As a result of this, the engagement pins 503 and 504 of the folding reinforcement 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 cancelled, and thus the folding reinforcement processing unit 500 becomes capable of moving alone.

In this state, by moving the folding reinforcement processing unit 500 toward the R side in a direction away from the square back processing unit 134 by the driving motor 135, only the folding reinforcement processing unit 500 is moved toward the R side in a state in which the square back processing unit 134 is left on the F side as illustrated in FIG. 19B. That is, in the case of cancelling the engagement between the square back processing unit 134 and the folding reinforcement processing unit 500, the driving motor 135 moves the folding reinforcement processing unit 500 in a direction away from the square back processing unit 134 after cancelling the engagement between the engagement pins 503 and 504 and the hooks 601 and 602.

The rack 704 is moved toward the F side by rotating the drive shaft 701c of the driving motor 701 in an opposite direction (counterclockwise direction) from the state illustrated in FIG. 19B. As a result of this, the pressing portion 704b is separated from the abutting portion 602e of the hook 602, and as illustrated in FIG. 12 described above, the hook 602 returns to the coupled position by the urging force of the spring 604. At this time, the hook 601 also returns to the coupled position via the link 603. That is, a situation in which the hooks 601 and 602 re-engage with the engagement pins 503 and 504 is suppressed by moving the rack 704 toward the F side by driving the driving motor 701 in a state in which the folding reinforcement processing unit 500 is away from the square back processing unit 134.

To be noted, when cancelling the coupling between the square back processing unit 134 and the folding reinforcement processing unit 500, the folding reinforcement processing unit 500 may be separated from the square back processing unit 134 by, for example, instead of moving the folding reinforcement processing unit 500 by driving the driving motor 135 as described above, being pushed by a protrusion portion provided on the hook 601 or the hook 602 or a member interlocked with the hook when the hook 602 pivots as a result of the abutting portion 602e being pushed by the pressing portion 704b of the rack 704. That is, it suffices as long as the folding reinforcement processing unit 500 is away from the square back processing unit 134 such that the engagement pins 503 and 504 do not re-engage with the hooks 601 and 602 when returning the hooks 601 and 602 to original positions after the engagement between the engagement pins 503 and 504 and the hooks 601 and 602 is cancelled. In addition, the link 603 may be omitted in the case of a configuration in which the coupling cancellation mechanism 700 is provided with two pressing portions 704b, and the two pressing portions 704b can respectively cancel the engagement of the hooks 601 and 602.

As described above, in the present embodiment, as a result of providing the coupling mechanism 600 coupling the folding reinforcement processing unit 500 and the square back processing unit 134 together and the coupling cancellation mechanism 700 that cancels this coupling, the folding reinforcement processing unit 500 can be moved alone, or the folding reinforcement processing unit 500 and the square back processing unit 134 can be moved in a coupled state, in the width direction by the driving motor 135 that is a single drive source.

Folding Reinforcement Process

Next, the folding reinforcement process by the folding reinforcement processing unit 500 will be described with reference to FIGS. 20A to 20D. To be noted, FIGS. 20A to 20D and FIGS. 21A to 21C that will be described later are illustrated such that the movement direction of the upper clamp unit 121 is the up-down direction, but the movement direction of the upper clamp unit 121 is inclined with respect to the up-down direction in an actual situation as illustrated in FIGS. 4 and 5 and the like. To be noted, the same applies to FIGS. 22A to 23C of the second and third embodiments.

As described above, the folding reinforcement processing unit 500 includes the pair of folding reinforcement rollers 501 and 502 that perform the folding reinforcement process of nipping the sheet bundle protruding downstream in the conveyance direction with respect to the lower clamp unit 120 and the upper clamp unit 121 while moving in the width direction of the sheet bundle in a state in which the sheet bundle is nipped by the lower clamp unit 120 and the upper clamp unit 121. In addition, in the conveyance direction of the sheet bundle, an upstream end portion of the nip of the pair of folding reinforcement rollers 501 and 502 is positioned downstream of a position where the surface of the pressing roller 123 comes into contact with the spine of sheet bundle in the square back process. To be noted, the pair of folding reinforcement rollers 501 and 502 may partially overlap with the pressing roller 123 as viewed in the width direction as long as the upstream end portion of the nip of the pair of folding reinforcement rollers 501 and 502 is positioned downstream of the position where the surface of the pressing roller 123 comes into contact with the spine of the sheet bundle in the conveyance direction. In addition, the upstream end portion of the nip of the pair of folding reinforcement rollers 501 and 502 may be positioned downstream of the downstream end of the pressing roller 123 in the conveyance direction.

In the present embodiment, the upstream end portion of the nip of the folding reinforcement rollers 501 and 502 is positioned downstream of the position where the pressing roller 123 presses the spine of the sheet bundle in the conveyance direction (saddle third roller conveyance direction 118c) as described above. Therefore, the protrusion amount of the sheet bundle from the lower clamp unit 120 and the upper clamp unit 121 is set to differ between a case of performing the square back process and a case of performing the folding reinforcement process. That is, the protrusion amount of the sheet bundle from the end surfaces 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 folding reinforcement process is set to be larger than the protrusion amount of the sheet bundle from the end surfaces 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 square back process.

FIGS. 20A to 20D are diagrams illustrating the operation of a folding reinforcement processing mode performed by the folding reinforcement processing unit 500. The upper clamp unit 121 and the lower clamp unit 120 include the pair of first clamp portions 119c and 119d and the pair of second clamp portions 142 and 143 positioned downstream of the pair of first clamp portions 119c and 119d in the conveyance direction as described above. In addition, the pre-clamp upper guide portion 119a and the pre-clamp lower guide portion 119b are respectively integrally formed with the pair of first clamp portions 119c and 119d to extend upstream from the upstream end portions of the first clamp portions 119c and 119d in the conveyance direction of the sheet bundle.

In addition, in the present embodiment, the first clamp portion 119d and the second clamp portion 143 included in the lower clamp unit 120 serving as one clamp unit are configured as fixed clamp portions that do not move when performing the folding reinforcement process and the square back process. In contrast, the first clamp portion 119c and the second clamp portion 142 included in the upper clamp unit 121 serving as the other clamp unit are configured as movable clamp portions that are movable in the thickness direction of the sheet bundle when performing the folding reinforcement process and the square back process. The first clamp portion 119c, the second clamp portion 142, and the pre-clamp upper guide portion 119a integrally move in the thickness direction of the sheet bundle.

In the present embodiment, when performing the square back process, the pair of first clamp portions 119c and 119d and the pair of second clamp portions 142 and 143 nip the sheet bundle. In contrast, when performing the folding reinforcement process, the pair of first clamp portions 119c and 119d are configured to nip the sheet bundle, and the pair of second clamp portions 142 and 143 are configured not to nip the sheet bundle. Alternatively, when performing the folding reinforcement process, the pair of first clamp portions 119c and 119d and the pair of second clamp portions 142 and 143 are configured to nip the sheet bundle, and the nipping pressure of the pair of second clamp portions 142 and 143 nipping the sheet bundle is set to be lower than in the case of the square back process. This point will be described in detail later.

In the case of performing the folding reinforcement process, first, the half-folding controller 344 (FIG. 3) conveys the sheet bundle Sb subjected to half-folding to the gap between the upper clamp unit 121 and the lower clamp unit 120 away from each other in response to detection of the leading end of the sheet bundle Sb by the saddle conveyance sensor 117 (FIG. 4). Then, as illustrated in FIG. 20A, the half-folding controller 344 stops the conveyance of the sheet bundle Sb in a state in which the spine Ssp of the sheet bundle Sb protrudes further downstream in the conveyance direction with respect to the end surfaces 121b and 120c on the downstream side in the conveyance direction of the upper clamp unit 121 and the lower clamp unit 120.

In this state, the folding reinforcement process controller 345 drives the clamp driving motor 132 (FIGS. 7A and 7B) and thus moves the upper clamp unit 121 toward the lower clamp unit 120, and as illustrated in FIG. 20B, the sheet bundle Sb is nipped by the upper clamp unit 121 and the lower clamp unit 120. As described above, in the folding reinforcement process, the sheet bundle is nipped by the pair of first clamp portions 119c and 119d, and the pair of second clamp portions 142 and 143 do not nip the sheet bundle or do nip the sheet bundle but the nipping pressure of the pair of second clamp portions 142 and 143 is set to be lower than in the case of the square back process.

At this time, the spine Ssp of the sheet bundle Sb protrudes further downstream than the end surfaces 121b and 120c on the downstream side in the conveyance direction of the pair of second clamp portions 142 and 143 included in the upper clamp unit 121 and the lower clamp unit 120 by P2. The protrusion amount P2 is larger than the protrusion amount P1 (FIG. 11B) in the square back processing mode described above.

Next, the folding reinforcement process controller 345 operates the driving motor 135 (FIG. 7B), and thus moves the folding reinforcement processing unit 500 in the width direction of the sheet bundle Sb. Specifically, only the folding reinforcement processing unit 500 is moved in the width direction in which the square back processing unit 134 is not coupled thereto. At this time, as illustrated in FIG. 20C, the folding reinforcement rollers 501 and 502 nip the sheet bundle Sb protruding downstream in the conveyance direction with respect to the upper clamp unit 121 and the lower clamp unit 120 while moving in the width direction of the sheet bundle Sb in a state in which the sheet bundle Sb is nipped by the upper clamp unit 121 and the lower clamp unit 120.

When the folding reinforcement rollers 501 and 502 move in the width direction, the folding reinforcement roller 501 rotates about a rotation shaft 501a, and the folding reinforcement roller 502 rotates about a rotation shaft 502a. As a result of this, the folding of the sheet bundle is reinforced by the folding reinforcement rollers 501 and 502. The respective rotation shafts 501a and 502a are rotatably supported by an unillustrated support member. The rotation shafts 501a and 502a each extend in a direction intersecting with (ideally orthogonal to) the width direction of the sheet bundle Sb and the movement direction of the upper clamp unit 121. In addition, the rotation shafts 501a and 502a extend in a direction intersecting with (ideally orthogonal to) the roller shaft 141 (FIG. 11C) of the pressing roller 123 of the square back processing unit 134. That is, whereas the pressing roller 123 of the square back processing unit 134 presses the spine of the sheet bundle in a plane orthogonal to the spine Ssp of the sheet bundle Sb, the folding reinforcement rollers 501 and 502 of the folding reinforcement processing unit 500 nip the spine of the sheet bundle from both sides in the thickness direction.

The folding reinforcement processing unit 500 is moved in the front-rear direction (width direction, front-rear direction of the sheet surface of FIG. 20C) of the sheet processing apparatus B by the driving motor 135 (FIG. 7B) as described above, and thus nips the spine Ssp of the sheet bundle Sb and performs the folding reinforcement. The folding reinforcement processing unit 500 may be configured to perform the folding reinforcement by moving in one direction in the width direction with respect to the spine of the sheet bundle, or may be configured to perform the folding reinforcement by reciprocating movement. The user may select the number of movements of the folding reinforcement processing unit 500.

After the folding reinforcement by the folding reinforcement processing unit 500, as illustrated in FIG. 20D, the folding reinforcement process controller 345 drives the clamp driving motor 132 (FIGS. 7A and 7B), and thus separates the first clamp portion 119c of the upper clamp unit 121 from the first clamp portion 119d of the lower clamp unit 120 to release the nipping of the sheet bundle Sb. Then, the discharge operation of the sheet bundle Sb described above is performed.

As described above, in the present embodiment, the protrusion amount of the spine of the sheet bundle with respect to the upper clamp unit 121 and the lower clamp unit 120 is configured to differ between the folding reinforcement process and the square back process. As a result of this, the folding reinforcement process and the square back process can be selectively performed by using the same upper clamp unit 121 and lower clamp unit 120. Therefore, the clamps to nip the sheet bundle do not have to be prepared for each process, and the same driving system can be used for the clamps. As a result of this, the size and cost of the apparatus can be reduced.

To be noted, in the present embodiment, the protrusion amount P2 of the spine Ssp of the sheet bundle Sb in the folding reinforcement process is set to be larger than the protrusion amount P1 of the sheet bundle Sb in the square back process. When performing the square back process, to orthogonally press (form a corner on) the spine Ssp of the sheet bundle Sb, the pressing roller 123 needs to come into surface contact with the upper clamp unit 121 and the lower clamp unit 120. Therefore, the pressing roller 123 used in the square back process needs to be disposed at a position closer to the upper clamp unit 121 and the lower clamp unit 120 than the folding reinforcement rollers 501 and 502. In contrast, the folding reinforcement rollers 501 and 502 do not have to come into contact with the upper clamp unit 121 and the lower clamp unit 120. Therefore, by setting the nipping position of the spine of the sheet bundle by the folding reinforcement rollers 501 and 502 of the folding reinforcement processing unit 500 to be farther than the position where the pressing roller 123 of the square back processing unit 134 presses the sheet bundle, the square back process and the folding reinforcement process can be performed by using the same clamp driving system.

Clamp Nipping Pressure

Next, the nipping pressure by which the upper clamp unit 121 and the lower clamp unit 120 nip the sheet bundle in the square back process and the folding reinforcement process will be described with reference to FIGS. 21A to 21C. Here, in the square back process, to form a corner on the spine of the sheet bundle by pressing the spine orthogonally, the nipping pressure of the upper clamp unit 121 and the lower clamp unit 120 (hereinafter also simply referred to as a “clamp nipping pressure”) needs to be a high pressure such that the sheet bundle is not displaced from the upper clamp unit 121 and the lower clamp unit 120 when the spine of the sheet bundle is pressed by the pressing roller 123. In contrast, in the folding reinforcement process, the folding reinforcement is performed by nipping the spine portion of the sheet bundle by the folding reinforcement rollers 501 and 502. The upper clamp unit 121 and the lower clamp unit 120 nip the sheet bundle when moving the folding reinforcement rollers 501 and 502 in the width direction along the spine of the sheet bundle, but if the sheet bundle is nipped by the clamp nipping pressure for the square back process, a nipping mark may be left in the vicinity of the spine of the sheet bundle. Therefore, In the folding reinforcement process, the clamp nipping pressure is set to be lower than in the case of the square back process.

As described above, a configuration in which different clamps are provided for respective processes and the clamps are each driven by a different driving system to change the clamp nipping pressure between the square back process and the folding reinforcement process can be considered, but in this case, the size and manufacturing cost of the apparatus increase. Therefore, in the present embodiment, the nipping pressure of the sheet bundle by the upper clamp unit 121 and the lower clamp unit 120 is configured to be changeable, and the nipping of the sheet bundle is performed by the same driving system in the square back process and the folding reinforcement process by employing the following configuration. Particularly, in the present embodiment, by using a spring, it is made possible to selectively use the first clamp portions 119c and 119d used in the folding reinforcement process and the second clamp portions 142 and 143 used in the square back process.

In the present embodiment, the nipping pressure by which the upper clamp unit 121 and the lower clamp unit 120 nip the sheet bundle in the case of performing the square back process is set to be higher than the nipping pressure by which the upper clamp unit 121 and the lower clamp unit 120 nip the sheet bundle in the folding reinforcement process. Therefore, the upper clamp unit 121 and the lower clamp unit 120 include a first spring 801 serving as a first urging portion and a second spring 802 serving as a second urging portion for generating a nipping pressure for nipping the sheet bundle. Further, the clamp nipping pressure is generated by the first spring 801 when performing the folding reinforcement process, and the clamp nipping pressure is generated by the first spring 801 and the second spring 802 when performing the square back process.

Specific description will be given. The lower clamp unit 120 serving as one clamp unit among the upper clamp unit 121 and the lower clamp unit 120 includes the first clamp portion 119d that is one of the pair of first clamp portions 119c and 119d, the second clamp portion 143 that is one of the pair of second clamp portions 142 and 143, and the first spring 801 that urges the one first clamp portion 119d toward the other first clamp portion 119c of the pair of first clamp portions 119c and 119d.

In contrast, the upper clamp unit 121 serving as 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 of the pair of second clamp portions 142 and 143, and the second spring 802 that urges the other second clamp portion 143 toward the one second clamp portion 142.

The lower clamp unit 120 further includes a fixed member 120d to which the one second clamp portion 143 is fixed to be unmovable in a direction (up-down direction of FIGS. 21A to 21C) following the thickness direction of the sheet bundle. The fixed member 120d is supported by an unillustrated support member. The fixed member 120d includes a first portion 120d1 disposed below the second clamp portion 143 and a second portion 120d2 protruding upstream (rightward in FIGS. 21A to 21C) from the first portion 120d1 in the conveyance direction. The one first clamp portion 119d is provided to be movable in the thickness direction of the sheet bundle with respect to the fixed member 120d. The first clamp portion 119d is positioned closer to the upper clamp unit 121 than the one second clamp portion 143 in a state in which the sheet bundle is not nipped by the pair of first clamp portions 119c and 119d as illustrated in FIG. 21A. In addition, the first spring 801 is disposed between the second portion 120d2 of the fixed member 120d and the one first clamp portion 119d.

The upper clamp unit 121 further includes a movable member 121c capable of moving to a first position and a second position closer to the lower clamp unit 120 than the first position in the thickness direction of the sheet bundle. The other first clamp portion 119c integrally moves with the movable member 121c. That is, the movable member 121c includes a first portion 121cl disposed above the second spring 802 and a second portion 121c2 fixed to the first portion 121cl and integrally formed with the first clamp portion 119c. Therefore, the first clamp portion 119c moves in the thickness direction of the sheet bundle together with the movable member 121c. To be noted, the pre-clamp upper guide portion 119a is integrally formed with the first clamp portion 119c, and therefore the pre-clamp upper guide portion 119a also moves together with the movable member 121c and the first clamp portion 119c.

The other second clamp portion 142 is provided to be movable in the thickness direction of the sheet bundle with respect to the movable member 121c. In addition, the second spring 802 is disposed between the first portion 121c1 of the movable member 121c and the other second clamp portion 142. The urging force of the first spring 801 is weaker than that of the second spring 802. Therefore, as will be described later, in the case of nipping the sheet bundle by the first clamp portions 119c and 119d and the second clamp portions 142 and 143 by moving down the movable member 121c, the first spring 801 contracts before the second spring 802 contracts.

FIG. 21A illustrates a state in which the upper clamp unit 121 and the lower clamp unit 120 are away from each other and in which the 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 in a state in which the spine Ssp of the sheet bundle Sb protrudes downstream in the conveyance direction with respect to the end surfaces 121b and 120c on the downstream side in the conveyance direction of the upper clamp unit 121 and the lower clamp unit 120.

When performing the folding reinforcement process, the movable member 121c is moved to the first position from the state of FIG. 21A. Then, as illustrated in FIG. 21B, the sheet bundle Sb is nipped by the pair of first clamp portions 119c and 119d, and thus the first spring 801 is compressed between the second portion 120d2 of the fixed member 120d and the one first clamp portion 119d. At this time, the second spring 802 is not compressed between the first portion 121c1 of the movable member 121c and the second clamp portion 142, or is compressed but the compression amount thereof is small and thus the urging force thereof is small. Therefore, the clamp nipping pressure in the folding reinforcement process is mostly based on an urging force generated by elastic compression of the first spring 801.

In contrast, when performing the square back process, the movable member 121c is moved to the second position, and as illustrated in FIG. 21C, the sheet bundle Sb is nipped by the pair of first clamp portions 119c and 119d and the pair of second clamp portions 142 and 143. That is, the movable member 121c is further moved down from the position of FIG. 21B. As a result of this, the first spring 801 can be compressed between the second portion 120d2 of the fixed member 120d and the one first clamp portion 119d, and the second spring 802 can be compressed between the first portion 121cl of the movable member 121c and the other second clamp portion 142. Therefore, the clamp nipping pressure in the square back process is based on an urging force generated by elastic compression of the first spring 801 and the second spring 802.

As described above, in the present embodiment, the clamp nipping pressure is changed by changing the position to which the movable member 121c is moved down, by using the first spring 801 and the second spring 802. Therefore, the nipping of the sheet bundle can be performed by the same driving system in the square back process and the folding reinforcement process. As a result of this, the size and cost of the apparatus can be reduced as compared with a configuration in which a different drive source or a different clamp is provided for each process. In addition, since the first clamp portions 119c and 119d for the folding reinforcement process are disposed on the upstream side and the second clamp portions 142 and 143 for the square back process are disposed on the downstream side in the conveyance direction of the sheet bundle, two clamp nipping pressures can be realized and two processes of the folding reinforcement process and the square back process can be performed by using just one movement mechanism.

Second Embodiment

A second embodiment will be described with reference to FIGS. 22A to 22C. A 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 the first embodiment described above. In contrast, in the present embodiment, the first spring 803 and the second spring 802 are provided in an upper clamp unit 121A. Other elements and effects are substantially the same as in the first embodiment described above. Therefore, the same elements will be denoted by the same reference signs, description and illustration thereof will be omitted or simplified, and parts different from the first embodiment will be mainly described below.

In the present embodiment, a lower clamp unit 120A serving as one clamp unit among an upper clamp unit 121A and the lower clamp unit 120A includes one first clamp portion 119d of the pair of first clamp portions 119c and 119d, and the one second clamp portion 143 of the pair of second clamp portions 142 and 143.

In contrast, the upper clamp unit 121A serving as the other clamp unit of the upper clamp unit 121A and the lower clamp unit 120A includes the other first clamp portion 119c of the pair of first clamp portions 119c and 119d, the other second clamp portion 142 of the pair of second clamp portions 142 and 143, a first spring 803 serving as a first urging portion that urges the other first clamp portion 119c toward the one first clamp portion 119d, and the second spring 802 serving as a second urging portion that urges the other second clamp portion 142 toward the one second clamp portion 143. Further, the clamp nipping pressure is generated by the first spring 803 when performing the folding reinforcement process, and the clamp nipping pressure is generated by the first spring 803 and the second spring 802 when performing the square back process.

The lower clamp unit 120A further includes the fixed member 120d to which the one first clamp portion 119d and the one second clamp portion 143 are fixed to be unmovable in a direction following the thickness direction of the sheet bundle. In contrast, the upper clamp unit 121A further includes the movable member 121c capable of moving to a first position and a second position closer to the lower clamp unit 120A than the first position in the thickness direction of the sheet bundle, and a pressing portion 121d that moves together with the movable member 121c. The pressing portion 121d is fixed to the movable member 121c so as to protrude upstream in the conveyance direction (rightward in FIGS. 22A to 22C) from the movable member 121c.

The other first clamp portion 119c and the other second clamp portion 142 are provided to be movable in the thickness direction of the sheet bundle with respect to the movable member 121c. Therefore, the first clamp portion 119c is also movable with respect to the pressing portion 121d fixed to the movable member 121c. In addition, in the present embodiment, the first clamp portion 119c and the second clamp portion 142 are relatively movable with respect to each other. The other first clamp portion 119c is closer to the lower clamp unit 120A than the other second clamp portion 142 in a state in which the sheet bundle is not nipped by the pair of first clamp portions 119c and 119d.

The first spring 803 is disposed between the pressing portion 121d and the other first clamp portion 119c, and the second spring 802 is disposed between the movable member 121c and the other second clamp portion 142. The urging force of the first spring 803 is weaker than that of the second spring 802. Therefore, as will be described later, in the case of nipping the sheet bundle by the first clamp portions 119c and 119d and the second clamp portions 142 and 143 by moving down the movable member 121c, the first spring 803 contracts before the second spring 802 contracts.

FIG. 22A illustrates a state in which the upper clamp unit 121A and the lower clamp unit 120A are away from each other and in which the sheet bundle Sb is received between the upper clamp unit 121A and the lower clamp unit 120A. In this state, the conveyance of the sheet bundle Sb is stopped in a state in which the spine Ssp of the sheet bundle Sb protrudes downstream in the conveyance direction with respect to the end surfaces 121b and 120c on the downstream side in the conveyance direction of the upper clamp unit 121A and the lower clamp unit 120A.

When performing the folding reinforcement process, the movable member 121c is moved to the first position from the state of FIG. 22A. Then, as illustrated in FIG. 22B, the sheet bundle Sb is nipped by the pair of first clamp portions 119c and 119d, and thus the first spring 803 is compressed between the pressing portion 121d and the other first clamp portion 119c. At this time, the second spring 802 is not compressed between the movable member 121c and the second clamp portion 142, or is compressed but the compression amount thereof is small and thus the urging force thereof is small. Therefore, the clamp nipping pressure in the folding reinforcement process is mostly based on an urging force generated by elastic compression of the first spring 803.

In contrast, when performing the square back process, the movable member 121c is moved to the second position, and as illustrated in FIG. 22C, the sheet bundle Sb is nipped by the pair of first clamp portions 119c and 119d and the pair of second clamp portions 142 and 143. That is, the movable member 121c is further moved down from the position of FIG. 22B. As a result of this, 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 movable member 121c and the other second clamp portion 142. Therefore, the clamp nipping pressure in the square back process is based on an urging force generated by elastic compression of the first spring 803 and the second spring 802.