Sheet processing apparatus and image forming system

Abstract

To provide a sheet processing device that prevents a transportation failure caused by the hooking of a sheet to a rotor pair.SOLUTION: A sheet processing device comprises: a projecting member projecting a sheet in the projecting direction from a space between a first transportation guide and a first loading guide; a rotor pair for folding the sheet by holding the sheet projected by the projecting member with a nip part and rotating; guide means provided in a first direction between the first transportation guide and the first loading guide, and guiding the sheet in the first direction, or a second direction inverse to the first direction, at a space between the first transportation guide and the first loading guide; and pressing means pressing a folded sheet in the pressing direction of bringing one side sheet facing via a fold close to the other side sheet at a space between the first loading guide and the first transportation guide, when moving the folded sheet to the second direction by setting the fold at a leading side.SELECTED DRAWING: Figure 35

Description

[Technical Field]

[0001] The present invention relates to a sheet processing apparatus for folding sheets sent from an image forming apparatus, for example, and an image forming system including the same. [Background technology]

[0002] Conventionally, there have been provided sheet processing devices that process sheets sent from image forming devices such as copiers, printers, facsimiles, and combination devices thereof. For example, a sheet processing device is known that protrudes a sheet sent from the image forming device with a thrusting plate, pushes the sheet into a nip portion of a pair of folding rollers, and folds the sheet in half by sandwiching the sheet between the pair of folding rollers and transporting it.

[0003] In this sheet processing apparatus, the pair of folding rollers and the abutment plate are arranged opposite to each other across a stacking guide that stacks sheets sent from an image forming apparatus, and the sheet is fed between the stacking guide and the pair of folding rollers, and the sheet is subjected to the folding process described above. In order to prevent the sheet passing between the stacking guide and the pair of folding rollers from getting caught on the pair of folding rollers during this process, a configuration has been proposed in which a guide member is brought into contact with the circumferential surface of the folding roller to guide the sheet (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2017-114648 Summary of the Invention [Problem to be solved by the invention]

[0005] Among sheet processing devices that fold sheets, there is a sheet processing device that performs a triple fold, in which a sheet that has already been folded is further folded in a different position. In this sheet processing device, when the folded sheet is sent again between the pair of folding rollers and the stacking tray, it is considered that the sheet is conveyed in the opposite direction to the conveying direction of the first folding. In this case, with the configuration described in Patent Document 1, there is a risk that the sheet may get caught on the pair of folding rollers when it is sent again between the pair of folding rollers and the stacking tray.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a sheet processing apparatus that can prevent a sheet from being caught between a pair of folding rollers and causing a transport failure, and an image forming system equipped with the same. [Means for solving the problem]

[0007] A typical configuration according to the present invention is as follows: A sheet processing apparatus that performs a first folding process on a sheet, and then performs a second folding process at a position different from the crease formed by the first folding process, thereby performing a triple inner fold so that one end of the sheet folded by the first folding process is on the inside of the folded sheet, the sheet processing apparatus comprising: a first conveying unit that conveys the sheet in a first direction; The sheet guide includes a first guide that guides the sheet, and a second guide that is disposed opposite the first guide and also guides the sheet. No. 1 the conveying guide pair is disposed downstream of the first guide in the first direction with a predetermined gap between the first guide and the conveying guide pair, a third guide that guides the sheet that has passed through the first conveying guide pair; and a fourth guide that is disposed opposite the third guide and guides the sheet; have Second transport Guide pair and A protruding direction from the second guide side toward the first guide side and the first conveying guide pair and the Straddling the second transport guide pair a protruding member that protrudes the sheet in the protruding direction; and a sheet protruded by the protruding member. Regarding the above Folding process Folding roller pair and, a return means for returning the fold of the folded sheet that has been subjected to the first folding process by the folding roller pair to between the first conveying guide pair and the second conveying guide pair, and a second conveying unit for conveying the folded sheet returned by the return means to the first conveying guide pair with the fold at the leading edge; the first guide in the first direction Third Guide and in the protruding direction the second guide and the folding roller of the pair of folding rollers arranged upstream in the first direction It is set up between The folded sheet conveyed by the second conveying section is guided by the first conveying guide pair. a guide means for guiding the a moving mechanism that moves the guide means to a receiving position that receives the crease of the folded sheet and an opening prevention position that prevents the folded sheet from opening beyond a certain level; and a control unit that controls the first conveying unit, the pushing member, the pair of folding rollers, the returning means, the second conveying unit, and the moving mechanism. Equipped with When the folded sheet is conveyed by the second conveying unit with the fold at the leading edge toward the first conveying guide pair after the first folding process has been performed on the sheet by the folding roller pair, the control unit moves the guide unit to the opening prevention position after the guide unit receives the fold at the receiving position, and pushes out the folded sheet with the push-out member after the fold has been guided by the first conveying guide pair, and performs the second folding process by the folding roller pair. It is characterized by: [Effects of the Invention]

[0008] According to the present invention, it is possible to prevent a sheet from being caught on the pair of rotating bodies and causing a transport failure. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an explanatory diagram of the overall configuration of an image forming system according to an embodiment of the present invention. [Figure 2] FIG. 1 is an explanatory diagram of the overall configuration of a sheet processing apparatus in an image forming system. [Figure 3] FIG. 2 is a cross-sectional view showing a folding processing device of the sheet processing device. [Figure 4] FIG. [Figure 5] (a)(b) is a cross-sectional view illustrating the inward three-folding operation of a sheet. [Figure 6] (a)(b) is a cross-sectional view illustrating the inward three-folding operation of a sheet. [Figure 7] (a)(b) is a cross-sectional view illustrating the inward three-folding operation of a sheet. [Figure 8] (a)(b) is a cross-sectional view illustrating the inward three-folding operation of a sheet. [Figure 9] (a)(b) is a cross-sectional view illustrating the inward three-folding operation of a sheet. [Figure 10] (a)(b) is a cross-sectional view illustrating the inward three-folding operation of a sheet. [Figure 11] (a)(b) is a cross-sectional view illustrating the inward three-folding operation of a sheet. [Figure 12] FIG. [Figure 13] FIG. 4 is an explanatory diagram illustrating the arrangement of a pair of folding rollers, a folding blade, and a pressing guide member. [Figure 14] (a)(b)(c) Explaining the operation of the pressure guide member [Figure 15] 10A and 10B are cross-sectional explanatory views of the operation of the folding blade and the blade guide member. [Figure 16] 10A and 10B are cross-sectional explanatory views of the operation of the folding blade and the blade guide member. [Figure 17] 10A and 10B are cross-sectional explanatory views of the operation of the folding blade and the blade guide member. [Figure 18] 10A and 10B are cross-sectional explanatory views of the operation of the folding blade and the blade guide member. [Figure 19] 10A and 10B are cross-sectional explanatory views of the operation of the folding blade and the blade guide member. [Figure 20] FIG. 2 is a control block diagram of a folding operation in the sheet folding processing device. [Figure 21] 10 is a flowchart of a folding operation in the sheet folding processing device. [Figure 22] 10 is a flowchart of a folding operation in the sheet folding processing device. [Figure 23] FIG. [Figure 24] 10A, 10B, and 10C are top views illustrating the operation of the folding blade and the blade guide member. [Figure 25] 10A and 10B are cross-sectional explanatory views of the operation of the folding blade and the blade guide member. [Figure 26] 10A and 10B are cross-sectional explanatory views of the operation of the folding blade and the blade guide member. [Figure 27] 10A and 10B are cross-sectional explanatory views of the operation of the folding blade and the blade guide member. [Figure 28] 10A and 10B are cross-sectional explanatory views of the operation of the folding blade and the blade guide member. [Figure 29] 10A and 10B are cross-sectional explanatory views of the operation of the folding blade and the blade guide member. [Figure 30] 10(a) and 10(b) are cross-sectional explanatory views of a deflection guide member. [Figure 31] 10(a) and 10(b) are cross-sectional explanatory views of a deflection guide member. [Figure 32] 10(a) and 10(b) are cross-sectional explanatory views of a deflection guide member. [Figure 33] FIG. [Figure 34] (a)(b) is a cross-sectional view illustrating the operation of the deflection guide. [Figure 35] (a)(b) is a cross-sectional view illustrating the operation of the deflection guide. [Figure 36] (a)(b) is a cross-sectional view illustrating the operation of the deflection guide. [Figure 37] (a)(b) is a cross-sectional view illustrating the operation of the deflection guide. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, a sheet processing apparatus according to a preferred embodiment of the present invention and an image forming system equipped with the same will be described with reference to the drawings. Fig. 1 shows a schematic diagram of the overall configuration of an image forming system equipped with a sheet processing apparatus according to an embodiment of the present invention. As shown in Fig. 1, the image forming system 100 includes an image forming apparatus A that forms an image on a sheet, and a sheet processing apparatus B that processes the sheet sent from the image forming apparatus A.

[0011] <Overall configuration of image forming apparatus> The image forming apparatus A is made up of an image forming unit A1, a scanner unit A2, and a feeder unit A3. The image forming unit A1 has a device housing 1 equipped with a paper feed section 2, an image forming section 3, a paper discharge section 4, and a data processing section 5.

[0012] The paper feed unit 2 is composed of multiple cassette mechanisms 2a, 2b, and 2c, each storing image formation sheets of different sizes, and feeds sheets of a size specified by a main body control unit (not shown) to a paper feed path 2f. Each cassette mechanism 2a, 2b, and 2c is detachably installed from the paper feed unit 2 and includes a separation mechanism that separates the sheets stored therein one by one and a paper feed mechanism that feeds the sheets. The paper feed path 2f is provided with a conveyance roller that feeds the sheets supplied from each cassette mechanism 2a, 2b, and 2c downstream, and a pair of registration rollers at the end of the path that aligns the leading edges of each sheet.

[0013] The paper feed path 2f is connected to a large-capacity cassette 2d and a manual feed tray 2e. The large-capacity cassette 2d is an optional unit that stores sheets of sizes that are consumed in large quantities. The manual feed tray 2e is configured to be able to feed special sheets such as cardboard sheets, coated sheets, and film sheets that are difficult to separate and feed.

[0014] In this embodiment, the image forming unit 3 is configured using an electrophotographic system and includes a rotating photosensitive drum 3a, a light emitter 3b that emits an optical beam, a developing unit 3c, and a cleaner (not shown) arranged around the photosensitive drum 3a. The illustrated mechanism is a monochrome printing mechanism in which the photosensitive drum 3a, whose circumferential surface is uniformly charged, is irradiated with light by the light emitter 3b in accordance with an image signal to optically form a latent image, and the developing unit 3c applies toner to this latent image to form a toner image.

[0015] In synchronization with the timing of image formation on the photosensitive drum 3a, a sheet is sent from the paper feed path 2f to the image forming unit 3, and a transfer bias is applied from the transfer charger 3d to transfer the toner image formed on the photosensitive drum 3a onto the sheet. The sheet onto which the toner image has been transferred is heated and pressurized as it passes through the fixing unit 6 to fix the toner image, and is then discharged from the paper discharge port 4b by the paper discharge rollers 4a and transported to the sheet processing device B, which will be described later.

[0016] The scanner unit A2 includes a platen 7a on which an original image is placed, a carriage 7b that reciprocates along the platen 7a, a photoelectric conversion unit 7c, and a reduction optical system 7d. The reduction optical system 7d guides light reflected from the original image on the platen 7a by the carriage 7b to the photoelectric conversion unit 7c. The photoelectric conversion unit 7c photoelectrically converts the optical output from the reduction optical system 7d into image data and outputs it to the image forming unit 3 as an electrical signal.

[0017] The scanner unit A2 also has a traveling platen 7e to read sheets fed from the feeder unit A3. The feeder unit A3 is composed of a paper feed tray 8a on which original sheets are stacked, a paper feed path 8b that guides the original sheets fed from the paper feed tray 8a to the traveling platen 7e, and a paper discharge tray 8c that stores the original sheets that have passed the traveling platen 7e. As the original sheets from the paper feed tray 8a pass the traveling platen 7e, they are read by the carriage 7b and the reduction optical system 7d.

[0018] <Overall configuration of sheet processing device> Next, the overall configuration of the sheet processing apparatus B that processes the sheets sent from the image forming apparatus A will be described.

[0019] 2 is an explanatory diagram of the configuration of sheet processing apparatus B according to this embodiment. Sheet processing apparatus B includes apparatus housing 11 having a transport opening 10 for introducing sheets from image forming apparatus A. Apparatus housing 11 is positioned in alignment with apparatus housing 1 of image forming apparatus A so that transport opening 10 communicates with sheet discharge opening 4b of image forming apparatus A.

[0020] The sheet processing apparatus B includes a sheet transport path 12 that transports a sheet introduced from a transport opening 10, a first discharge path 13a, a second discharge path 13b, and a third discharge path 13c branching off from the sheet transport path 12, a first path switching means 14a, and a second path switching means 14b. The first path switching means 14a and the second path switching means 14b are each formed of a flapper guide that changes the transport direction of a sheet transported on the sheet transport path 12.

[0021] The first path switching means 14a is switched by a driving means (not shown) between a mode in which the sheet from the conveyance opening 10 is guided toward the first discharge path 13a that conveys the sheet laterally and the second discharge path 13b that conveys the sheet downward, and a mode in which the sheet is guided toward the third discharge path 13c that conveys the sheet upward. The first discharge path 13a and the second discharge path 13b are connected so that a sheet once introduced into the first discharge path 13a can be reversed in its conveying direction and switched back to be conveyed to the second discharge path 13b.

[0022] The second path switching means 14b is disposed downstream of the first path switching means 14a in the conveying direction of the sheet conveyed through the sheet conveying path 12. The second path switching means 14b is switched by a driving means (not shown) between a mode in which the sheet that has passed through the first path switching means 14a is introduced into the first discharge path 13a and a mode in which the sheet that has once been introduced into the first discharge path 13a is switched back and conveyed to the second discharge path 13b.

[0023] The sheet processing apparatus B includes a first processing section B1, a second processing section B2, and a third processing section B3, each of which performs a different process. Further, a punch unit 15 is disposed in the sheet transport path 12 to punch holes in the transported sheets.

[0024] The first processing unit B1 is a binding processing unit that performs a collating and stapling process. The first processing unit B1 accumulates, collates, and staples multiple sheets conveyed from a sheet discharge port 16a at the downstream end of the first sheet discharge path 13a in the sheet conveying direction along the sheet conveying path 12, and discharges the sheets to a stacking tray 16b provided outside the device housing 11. The first processing unit B1 also includes a sheet conveying device 16c that conveys sheets or a sheet stack, and a binding processing unit 16d that binds the sheet stack. A pair of discharge rollers 16e is provided at the downstream end of the first sheet discharge path 13a to discharge sheets from the sheet discharge port 16a and to switchback-convey the sheets from the first sheet discharge path 13a to the second sheet discharge path 13b.

[0025] The second processing unit B2 is a folding processing unit that folds the sheets conveyed in a switchback manner from the second discharge path 13b into a sheet bundle consisting of multiple sheets, binds the sheet bundle, and then folds it. The second processing unit B2 includes a folding processing unit F that folds the conveyed sheets or sheet bundle, and a binding processing unit 17a that is arranged immediately upstream of the folding processing unit F in the sheet conveyance direction of the sheets conveyed to the second discharge path 13b and binds the sheet bundle. The folded sheet bundle is discharged by discharge rollers 17b to a stacking tray 17c provided outside the device housing 11.

[0026] The third processing unit B3 performs jog sorting, which separates the sheets sent from the third discharge path 13c into a group that is accumulated by offsetting the sheets by a predetermined amount in the sheet width direction perpendicular to the conveyance direction, and a group that is accumulated without offsetting the sheets. The jog-sorted sheets are discharged onto a stacking tray 18 provided outside the device housing 11, and the offset sheet bundles and the non-offset sheet bundles are stacked.

[0027] 3 shows a schematic diagram of the overall configuration of the second processing section B2. As described above, the second processing section B2 includes a folding device F that folds in half the sheet bundle that has been conveyed from the second discharge path 13b and accumulated and collated, and a binding unit 17a that binds the sheet bundle before folding. The illustrated binding unit 17a is a stapler that staples the sheet bundle.

[0028] A sheet transport path 20 is connected to the second discharge path 13b in order to transport sheets to the folding processing device F. With respect to the transport direction of sheets transported from the second discharge path 13b to the sheet stacking tray 21, the sheet stacking tray 21, which constitutes a part of the sheet transport path, is provided downstream of the sheet transport path 20 in order to position and stack sheets to be folded. Immediately upstream of the sheet stacking tray 21, the binding processing unit 17a and its staple receiving portion 17d are provided in opposing positions across the sheet transport path 20.

[0029] On one side of the sheet stacking tray 21, a pair of folding rollers 22 serving as a pair of folding rotors is disposed so as to face one surface of a sheet or a bundle of sheets stacked on the sheet stacking tray 21. The pair of folding rollers 22 includes a pair of folding rollers 22a and 22b whose roller surfaces are pressed against each other, and a nip portion 22c, which is the pressing portion, is disposed facing the sheet stacking tray 21. The folding rollers 22a and 22b are arranged side by side at approximately equal intervals from the sheet stacking tray 21 on the upstream and downstream sides along the conveyance direction of the sheet conveyed from the upper upstream side to the lower downstream side of the sheet stacking tray 21. Note that in the present invention, the rotating portions of the pair of folding rotors are not limited to the folding rollers 22a and 22b of this embodiment, and may be constituted by a rotating belt or the like. Furthermore, the pair of folding rollers 22 may be constituted by a plurality of folding rollers (rotating bodies) continuously arranged in series along the axial direction of each of the folding rollers 22a and 22b.

[0030] As shown in FIG. 3, each of the folding rollers 22a and 22b of the pair of folding rollers 22 of this embodiment has a roller circumferential surface including a first roller surface 22a2 and a second roller surface 22a3 and a second roller surface 22b3. The first roller surfaces 22a2 and 22b2 have a constant radius R1 centered on the rotational axis of the rotation shafts 22a1 and 22b1, respectively. The distance of the second roller surfaces 22a3 and 22b3 from the rotational axis of the rotation shafts 22a1 and 22b1, respectively, is smaller than the radius R1 of the first roller surface. The first roller surfaces 22a2 and 22b2 are formed of a rubber material or the like with a relatively high coefficient of friction, similar to a typical roller surface. In contrast, the second roller surfaces 22a3 and 22b3 are formed of a plastic resin material or the like with a lower coefficient of friction than the first roller surfaces 22a2 and 22b2.

[0031] Rotation shafts 22a1 and 22b1 of folding rollers 22a and 22b are rotated by a common drive means such as a drive motor, etc. This allows the rotational positions of first roller surfaces 22a2 and 22b2 and second roller surfaces 22a3 and 22b3 to be always synchronized with each other.

[0032] A folding blade 23 serving as a protruding member is disposed on the opposite side of the folding roller pair 22 across the sheet stacking tray 21. The folding blade 23 is supported by a blade carrier 24 with its tip pointing toward the nip portion 22c of the folding roller pair 22. The blade carrier 24 is provided so as to be movable by a moving means formed of a cam member or the like in a direction that crosses the sheet stacking tray 21 at a substantially right angle, that is, in a direction that intersects with the conveyance direction of the sheets conveyed from the second discharge path 13b to the sheet stacking tray 21.

[0033] 3, i.e., in the axial direction of the folding rollers, a pair of cam members 25 (only one of which is shown in the figure) consisting of mirror-symmetrical eccentric cams are provided on both sides of the blade carrier 24 in opposing positions. Cam member 25 rotates around rotation shaft 25a provided at the eccentric position by driving means such as a drive motor. Cam member 25 has a cam groove 25b formed along its outer periphery.

[0034] The blade carrier 24 is provided with a cam pin 24c as a cam follower that slidably fits into the cam groove 25b.

[0035] When the drive motor rotates the cam member 25, the blade carrier 24 travels back and forth in a direction approaching or receding from the sheet stacking tray 21. As a result, as shown in Fig. 3, the blade carrier 24 can move the folding blade 23 back and forth in a straight line along a protrusion path connecting the initial position and the maximum protrusion position. The initial position is a position where the tip of the folding blade 23 does not enter the sheet conveying path formed by the sheet stacking tray 21. The maximum protrusion position is a position where the tip of the folding blade 23 is sandwiched between the nip portion 22c of the folding roller pair 22.

[0036] A regulating stopper 26 for restricting the leading edge of the conveyed sheet in the conveying direction by contacting it is disposed at the lower end of the sheet stacking tray 21. The regulating stopper 26 is provided so as to be movable up and down along the sheet stacking tray 21 by a sheet lifting mechanism 27.

[0037] The sheet lifting mechanism 27 in this embodiment is a conveyor belt mechanism consisting of a pair of pulleys 27a, 27b arranged near the upper and lower ends of the sheet stacking tray 21 and a transmission belt 27c wound around the pulleys. The sheet lifting mechanism 27 is located below the blade carrier 24 when it is in its initial position. The initial position of the blade carrier 24 is behind the sheet stacking tray 21, where the leading edge of the folding blade 23 does not enter the sheet conveyance path formed by the sheet stacking tray 21. The regulating stopper 26 is fixed to the transmission belt 27c. The drive-side pulley 27a or 27b is rotated by a driving means such as a drive motor, thereby moving the transmission belt 27c stretched around the pulleys. As a result, the regulating stopper 26 fixed to the transmission belt 27c moves up and down between the lower end position shown in FIG. 3 and a desired height position. The lifting and lowering of the regulating stopper 26 allows a sheet or a stack of sheets to move along the sheet stacking tray 21.

[0038] The regulating stopper 26 and the sheet lifting mechanism 27 constitute a sheet moving means that moves the sheet in the conveying direction (first direction) or in a moving direction (second direction) opposite to the conveying direction. Note that, as an example of the moving means, a configuration in which the leading edge of the sheet in the conveying direction (the end on the downstream side in the first direction) conveyed to the sheet stacking tray 21 is supported and moved by the regulating stopper 26 is shown here, but the present invention is not limited to this. For example, the sheet moving means may have other configurations, such as a configuration in which a pair of rollers moves the sheet, or a configuration in which the side of the sheet is gripped and moved, as long as it is configured to move the sheet in the conveying direction or in a moving direction (second direction) opposite to the conveying direction.

[0039] The folding device F of this embodiment also includes a sheet side alignment mechanism for aligning the side edges of sheets conveyed to the sheet stacking tray 21. As shown in FIG. 4, this sheet side alignment mechanism has a pair of sheet side alignment members 28a, 28b symmetrically arranged on both sides of the sheet stacking tray 21 in the sheet width direction (direction perpendicular to the sheet conveying direction). Note that FIG. 4 is a schematic plan view of the folding device F as seen from above. The sheet side alignment members 28a, 28b are held movably so as to be able to move relatively close to and away from each other in the sheet width direction. When a sheet is conveyed to the sheet stacking tray 21 and its leading edge abuts against the regulating stopper 26, the sheet side alignment members 28a, 28b are moved to align the sheet widthwise position.

[0040] <Inner tri-fold processing> The sheet processing device B of this embodiment is capable of folding a sheet in three after it has been conveyed by the folding device F to the sheet stacking tray 21, which serves as the sheet conveyance path. The folding process involves folding the sheet in half in a first folding process, and then folding the sheet a second time at a position different from the initial folding position. The folding process involves folding one edge of the sheet folded in the first folding process into the inside of the sheet folded in the second folding process. The operation of the folding device F of this embodiment when folding in three will now be described with reference to FIGS. 5 to 11. FIGS. 5 to 11 are cross-sectional schematic diagrams showing the movement of each component along the flow of the sheet S when folding in three.

[0041] In this embodiment, the sheet stacking tray 21 is formed at an angle with respect to the vertical direction. The sheet S is conveyed so that the sheet leading edge S1 is downward and the sheet trailing edge S2 is upward while being guided by a guide surface 21a that forms the sheet stacking tray 21 on one side, and the sheet leading edge S1 hits the regulating stopper 26 and stops (FIG. 5A). At this time, the regulating stopper 26 is positioned so that the first folding position of the sheet S against which the sheet leading edge S1 hits is positioned opposite the folding blade 23. The folding blade 23 is positioned so that it pushes the sheet S from the side of the guide surface 21a of the sheet stacking tray 21 toward the folding roller pair 22. In other words, the guide surface 21a of the sheet stacking tray 21 and the folding roller pair 22 are positioned so that they correspond to each other with the sheet S sandwiched therebetween.

[0042] In this state, the sheet side alignment members 28a and 28b align the sheet widthwise position, and then the folding blade 23 is operated to fold the sheet S in half and protrude the folded portion into the nip portion 22c of the folding roller pair 22 (FIG. 5(b)). In synchronization with the protruding operation of the folding blade 23, the folding roller pair 22 and the discharge roller 17b are driven in the forward direction to draw the sheet S into the folding roller pair 22 and the discharge roller 17b. As a result, the sheet S is pressed by the nip portion of the folding roller pair 22, and the first folding process is performed (FIG. 6(a)).

[0043] Next, to perform the second folding process, sheet conveyance is stopped when the trailing edge S2 of the sheet, which has been folded the first time, reaches a predetermined position (FIG. 6(b)), and the pair of folding rollers 22 and the discharge roller 17b are driven in the reverse direction to perform a switchback conveyance process. When the sheet is folded inward in three, the trailing edge S2 of the sheet becomes the edge (hereinafter referred to as the "folded edge") that is folded inside the sheet folded in the second folding process. During the switchback conveyance process, the folded edge S2 is pressed downward (toward the sheet stacking tray 21 where the leading edge S1 of the sheet is located) by the L-shaped pressure guide member 30 (FIG. 7(a)). The pressure guide member 30 again guides the sheet S, which is conveyed in the direction of the regulating stopper 26 of the sheet stacking tray 21 (FIG. 7(b)). The configuration and operation of this pressure guide member 30 will be described in detail later.

[0044] The switchback transport causes the leading edge of the sheet S to reach the regulating stopper 26, which has been moved to the sheet receiving position in advance (FIG. 8(a)). Then, the pressing guide member 30 is returned to the retracted position and then moved to the reverse transport guide position (FIG. 8(b)), and the regulating stopper 26 is moved to a position where the second folding position faces the folding blade 23 (FIG. 9(a)). After the movement is complete, the pressing guide member 30 is moved to a guide position where it is parallel to the guide surface 21a of the sheet stacking tray 21 (FIG. 9(b)).

[0045] Next, the folding blade 23 is operated again to push the sheet S into the nip portion 22c of the pair of folding rollers 22 (FIG. 10(a)). At this time, the blade guide member 40, which is a pushing guide member arranged above the folding blade 23, protrudes to guide the folded end S2 of the sheet so that it is pushed into the nip portion 22c (FIG. 10(b)). The configuration and operation of this blade guide member 40 will be described in detail later.

[0046] The sheet S is sent to the pair of folding rollers 22 by the protrusion of the folding blade 23, and undergoes a second folding process by passing through the nip portion 22c (Figure 11(a)), and the sheet S, folded in three, is discharged by the discharge roller 17b (Figure 11(b)).

[0047] <Pressure guide member> Next, the pressing guide member 30, which is the pressing member, will be described with reference to Figs. 12 to 14. Fig. 12 is a perspective view of the folding processing device F with the pressing guide member 30 exposed, and Fig. 13 is a diagram showing the rotation trajectory of the pressing guide member 30 and its relationship with other members. Fig. 14 is an explanatory diagram of the operation of the pressing guide member 30.

[0048] (Shape of pressure guide member) When a sheet that has been folded the first time is conveyed in a switchback manner, the pressing guide member 30 presses the folded end S2 of the sheet downward and guides the sheet so that the sheet is conveyed to the sheet stacking tray 21. In other words, the pressing guide member 30 is also a direction changing member that changes the orientation of the folded end S2 of the sheet toward the sheet leading edge S1 of the sheet stacking tray 21 when a sheet that has been folded the first time is conveyed in a switchback manner.

[0049] 12 (and see FIG. 4), the pressing guide members 30 are arranged on the opposite side to the side where the folding roller pair 22 is arranged, with the sheet S guided by the guide surface 21a of the sheet stacking tray 21 sandwiched between them. In this embodiment, three pressing guide members 30 are attached to a rotating shaft 31, which is a support member arranged in the sheet width direction, at approximately equal intervals. The two on both sides are arranged at positions where they can abut on both ends of the sheet S being transported on the sheet stacking tray 21, and the central one is arranged at a position where it can abut on approximately the center in the width direction of the sheet being transported.

[0050] The pressing guide members 30 can be moved by a moving means. In this embodiment, a rotating shaft 31 is connected to a pressing guide motor 33 via a drive transmission member 32 such as a drive belt, and the rotating shaft 31 rotates when driven by the pressing guide motor 33, and the three pressing guide members 30 can rotate integrally with the rotating shaft 31.

[0051] 13, the pressing guide member 30 has a rotating portion 30a that is rotatable about a rotating shaft 31, and a guide portion 30b that serves as a first guide surface that guides the sheet S being conveyed in a switchback manner. The pressing guide member 30 is configured as a member with an L-shaped cross section, in which the guide portion 30b is connected to the rotating portion 30a at a substantially right angle. The portion between the rotating portion 30a and the guide portion 30b, i.e., the corner of the L-shape that is the tip of the rotating portion 30a, is formed as a pressing portion 30c that presses the sheet S.

[0052] The pressing guide member 30 is provided so as to be exposed from a notch formed in the guide surface 21a. When the sheet S is transported to the sheet stacking tray 21, the pressing guide member 30 is retracted to a retracted position (see FIG. 5(a)). When in this retracted position, the rotating portion 30a is provided so as to be substantially flush with the guide surface 21a. Therefore, the rotating portion 30a functions as part of the guide surface 21a, and acts as a guide surface (second guide surface) that guides the sheet transported to the sheet stacking tray 21. When the pressing guide member 30 is in the retracted position, it is only necessary to prevent the guide portion 30b from protruding from the guide surface 21a, so that the storage space for the pressing guide member 30 in the retracted state can be reduced.

[0053] (Position of rotation center) As shown in FIG. 13 , the rotation shaft 31 serving as the rotation center of the pressing guide member 30 is disposed upstream of a nip line L1 connecting the nip portion 22c of the pair of folding rollers 22 and the tip of the folding blade 23 in the conveying direction in which the sheet S is conveyed to the sheet stacking tray 21. The rotation shaft 31 of the pressing guide member 30 is disposed on the opposite side of the guide surface 21a of the sheet stacking tray 21 from the side on which the pair of folding rollers 22 is disposed. Furthermore, the rotation shaft 31 of the pressing guide member 30 passes through the rotation shaft 22a1 of the folding roller 22a, of the folding rollers 22a, 22b, which is closer to the rotation shaft 31, and is disposed downstream of an axis L2, which is parallel to the nip line L1, in the conveying direction. The folding roller, of the folding rollers 22a, 22b, which is closer to the rotation shaft 31 is the folding roller disposed upstream of the nip line L1 in the sheet conveying direction.

[0054] The rotating portion 30a is set so as to rotate in a direction in which the pressing portion 30c presses the sheet S toward the side where the sheet S is to be switched back and conveyed.

[0055] Therefore, when the sheet S that has been folded the first time is conveyed in a switchback manner, the pressing guide member 30, which is in the retracted position, rotates as shown in FIG. 14(a). Then, as shown in FIG. 14(b), the pressing portion 30c of the pressing guide member 30 presses the folded end S2 of the sheet downward from above the folded end S2. As a result, the folded end S2 is guided to the downstream side (downward) of the sheet conveyance direction in which the sheet S is received in the sheet stacking tray 21 before the first folding process of the sheet stacking tray 21 while being conveyed in a switchback manner. In other words, the pressing portion 30c changes the orientation of the folded end S2 of the sheet toward the sheet leading edge S1 of the sheet stacking tray 21. After changing the orientation of the folded end S2, the pressing guide member 30 remains in that position, thereby guiding the folded end S2 to the downstream side of the sheet conveyance direction in which the sheet S is received in the sheet stacking tray 21 before the first folding process.

[0056] 14(c), the pressing portion 30c rotates to the guide position where it has rotated to the position of the guide surface 21a. Then, the pressing portion 30c comes into contact with the sheet and presses down so as to pull the folded end S2 of the sheet from the nip portion 22c side toward the guide surface 21a side, and guides the sheet in the direction in which the regulating stopper 26 of the sheet stacking tray 21 is disposed. Therefore, even if the folded end S2 of the sheet is curled upward, the sheet will not proceed upward in the sheet stacking tray 21, but will be reliably conveyed downward.

[0057] (Rotation area of ​​the rotating part) 13, the length of rotating portion 30a of pressing guide member 30 is set to be longer than the shortest distance to first roller surface 22a2 of folding roller 22a closer to rotation shaft 31 and shorter than the shortest distance to second roller surface 22a3. Note that the length of rotating portion 30a of pressing guide member 30 is the length from rotation shaft 31, which is the rotation fulcrum, to pressing portion 30c. Furthermore, of the two folding rollers 22a, 22b, folding roller 22a is the folding roller closer to rotation shaft 31.

[0058] When the sheet is switched back, the pair of folding rollers 22 is stopped so that the second roller surfaces 22a3, 22b3 face the rotating portion 30a. As a result, even if the length of the rotating portion 30a is set longer than the shortest distance to the first roller surface 22a2, the rotating portion 30a does not interfere with the pair of folding rollers 22 when it is rotated. Furthermore, the length of the rotating portion 30a can be set longer than the shortest distance to the first roller surface 22a2, which is the large-diameter portion of the folding roller 22a. Therefore, the pressing portion 30c presses the sheet being switched back at a position closer to the nip portion 22c, and the sheet is guided more reliably to the sheet stacking tray 21.

[0059] When the length of the rotating portion 30a is increased, the rotating shaft 31 must be positioned away from the folding blade 23 in the sheet conveying direction to prevent the rotated pressing guide member 30 from interfering with the folding blade 23. As a result, the rotating shaft 31 must also be positioned away from the pair of folding rollers 22. In this regard, in this embodiment, as described above, the rotating shaft 31 is configured to be positioned between the nip line L1 and the axis line L2 in the sheet conveying direction. Therefore, the position where the pressing portion 30c presses the sheet being switchback-conveyed can be brought closer to the nip portion 22c without unnecessarily increasing the length of the rotating portion 30a.

[0060] Here, the pair of folding rollers may be different diameter rollers having first roller surfaces 22a2, 22b2 and second roller surfaces 22a3, 22b3 with different diameters, or a pair of rollers with a fixed roller diameter may be used. In this case, however, the length of rotating portion 30a must be shorter than the shortest distance to the outer periphery of the folding roller closest to the rotation axis.

[0061] 13, the pressing guide member 30 of this embodiment has a shape in which the guide portion 30b is located inside the rotation locus L3 of the rotating portion 30a and does not protrude outside that area. As a result, even when the rotating portion 30a, which is configured to be long as described above, is rotated, the guide portion 30b does not interfere with the folding roller pair 22.

[0062] When the sheet that has been folded the first time as described above is conveyed in a switchback manner, it is returned to the sheet stacking tray 21 while being guided by the pressing guide member 30. After the sheet abuts against the regulating stopper 26 and the switchback conveyance is completed, the pressing guide member 30 is returned to the retracted position. At this time, the rotating portion 30a that serves as the second guide surface of the pressing guide member 30 moves the sheet stacking tray 21 to a reverse conveyance guide position that protrudes slightly toward the sheet conveyance path beyond the guide surface 21a so as to guide the sheet S that is conveyed in the reverse direction (see FIG. 8(b)).

[0063] After the pressing guide member 30 has moved to the reverse conveyance guide position, the regulating stopper 26 is raised to convey the sheet in the reverse direction so that the second folding position faces the folding blade 23. At this time, the sheet S is guided by the rotating portion 30a of the pressing guide member 30, and is therefore conveyed without getting caught on notches for attaching the pressing guide member formed on the guide surface 21a (see FIG. 9(a)).

[0064] <Blade guide member> After the second folding position of the sheet conveyed in the switchback manner as described above moves to a position facing the folding blade 23, the pressing guide member 30 is moved to the retracted position, and the folding blade 23 is operated to perform the second folding operation. At this time, the blade guide member 40 provided above the folding blade 23 is configured to guide the folded end S2 of the sheet (see FIG. 10(b)).

[0065] Next, the configuration and operation of the blade guide member 40 will be specifically described with reference to Figures 15 to 19. Figure 15 is an explanatory diagram of the rotation of the blade guide member 40, and Figures 16 to 19 are diagrams showing the operation of the folding blade 23 and the blade guide member 40 when performing the second folding process on the sheet.

[0066] (Configuration of blade guide member) When folding the sheet S for the second time, the blade guide member 40 moves in the protruding direction of the folding blade 23 to guide the sheet edge on the crease side formed by the first folding process relative to the folding blade 23, i.e., the folded edge S2 of the sheet, in the protruding direction and into the nip portion 22c of the pair of folding rollers 22. To this end, as shown in FIG. 15 , the blade guide member 40 has a contact portion 40a that contacts the rear end of the sheet. One end of the contact portion 40a is formed with a fitting hole 40b having a partial cutout, and this fitting hole 40b is rotatably fitted onto a shaft portion 40f formed on the base portion 40e. An arm portion 40c is integrally formed with the other end of the contact portion 40a, and an engagement protrusion 40d is formed at the end of the arm portion 40c. The engagement protrusion 40d slidably engages with an elongated hole 50 formed in the frame of the sheet processing device B. The slot 50 is formed in the vicinity of the upper portion of the blade carrier 24 and substantially parallel to the guide surface 21 a of the sheet stacking tray 21 .

[0067] The base portion 40e is attached to the blade carrier 24 so as to be slidable in a direction parallel to the movement direction of the blade carrier 24. A tension spring 51 is attached between a locking portion 40e1 formed on the base portion 40e and a locking portion 24a formed on the blade carrier 24.

[0068] The blade carrier 24 is provided with a pressing protrusion 24b that can come into contact with and press the base portion 40e. The pressing protrusion 24b is rotatably provided on the blade carrier 24 and is biased counterclockwise in FIG. 15 by a coil spring 52 attached to the rotation shaft. As a result, when the blade carrier 24 moves in the blade protruding direction, the pressing protrusion 24b comes into contact with and presses the base portion 40e, and the blade guide member 40 moves integrally with the blade carrier 24. The coil spring 52 provided on the pressing protrusion 24b acts as a so-called torque limiter, and is configured to rotate clockwise when a clockwise force greater than or equal to a predetermined value is applied to the pressing protrusion 24b.

[0069] (Angle change of the contact part relative to the direction of movement of the folding blade) In the above configuration, as shown in FIG. 15(a), when the blade carrier 24 is in the home position, the blade guide member 40 is pulled by the tension spring 51 and the abutting portion 40a is in a position where it abuts against the rotation shaft 31, which serves as the rotation fulcrum of the pressing guide member 30. This state is the home position of the blade guide member 40. At this time, the abutting portion 40a stands upright so as to be substantially flush with the guide surface 21a. When the blade carrier 24 moves in the blade protruding direction, the blade guide member 40 is pressed by the pressing protrusion 24b and moves from the home position together with the blade carrier 24. The blade guide member 40 moves from the home position until the abutting portion 40e2 formed upright at the rear end of the base portion 40e abuts against the rotation shaft 31, as shown in FIG. 15(b).

[0070] As described above, when the blade guide member 40 moves in the blade protruding direction, the engaging protrusion 40d slides downward while being guided by the elongated hole 50, and the contact portion 40a rotates around the shaft 40f. The shaft 40f is provided at one end of the contact portion 40a closer to the folding blade 23. This one end refers to the area between the center of the contact portion 40a and the end closer to the folding blade 23. In other words, the shaft 40f is provided in a region closer to the folding blade 23 than the center of the contact portion 40a. Therefore, when the blade guide member 40 is in the home position shown in FIG. 15(a), the contact portion 40a is at a substantially right angle to the movement direction of the blade carrier 24, i.e., the movement direction of the folding blade 23, and is in an upright state. The contact portion 40a is configured so that the angle of the contact portion 40a with respect to the movement direction becomes acute (so that the angle on the upstream side of the protruding direction becomes smaller) as the blade carrier 24 moves in the direction in which the folding blade 23 protrudes. As the blade carrier 24 moves in the direction in which the folding blade 23 is protruding, the other end of the abutting portion 40a moves closer to the movement path of the shaft portion 40f, which is the center of rotation of the abutting portion 40a, as shown in Figure 15(b). In other words, the abutting portion 40a rotates so as to fall toward the upstream side in the protruding direction of the folding blade 23. As described above, one end of the abutting portion 40a is configured to be rotatable around the shaft portion, and the end of the arm portion 40c, which is provided extending from the other end of the abutting portion 40a, is configured to be slidable along the elongated hole 50. This makes it possible for the angle of the blade guide member 40 relative to the movement direction to be changed in conjunction with the movement of the blade guide member 40, without the need for a special driving means.

[0071] 15(a), a protrusion 40f1 is formed on the shaft 40f that serves as the rotation axis of the abutment portion 40a. Meanwhile, a notch formed in the fitting hole 40b that fits with the shaft 40f is formed wider than the width of the protrusion 40f1, and the blade guide member 40 is rotatable within the range of the notch.

[0072] In the above configuration, when the blade carrier 24 moves to the home position, the base portion 40e is pulled by the tension spring 51, and at this time the notched surface of the fitting hole 40b abuts against the protrusion 40f1, restricting further rotation of the abutting portion 40a. Therefore, with the abutting portion 40a abutting against the rotation shaft 31, further movement of the blade guide member 40 is restricted, and the abutting portion 40a maintains an upright state at the home position.

[0073] Furthermore, in the blade guide member 40 of this embodiment, the contact portion 40a and the arm portion 40c are formed as linear members in cross section, and the arm portion 40c is formed at a predetermined angle relative to the contact portion 40a. As a result, even if the contact portion 40a is configured to be substantially flush with the guide surface 21a when the blade guide member 40 is in the home position, the end of the arm portion 40c on which the engaging protrusion 40d is provided is located away from the guide surface 21a on the side opposite the folding roller pair 22. That is, it is located on the side of the guide surface 21a in the direction in which the folding blade 23 returns from the nip portion 22c to the home position. Therefore, the elongated hole 50 with which the engaging protrusion 40d engages can be located away from the guide surface 21a on the side opposite the folding roller pair 22, and can be positioned so as not to interfere with the guide surface 21a. Therefore, when the blade guide member 40 is in the home position, the contact portion 40a can be configured to function as a guide for sheets transported through the sheet stacking tray 21.

[0074] (Operation of folding blade and blade guide member) Next, the operation of the blade guide member 40 when the folding blade 23 is operated to perform the second folding operation on the sheet will be described with reference to FIGS.

[0075] 16(a) shows a state in which the blade carrier 24 is in the home position, and at this time the blade guide member 40 is also in the home position. In the following description, the direction in which the blade carrier 24 protrudes the folding blade 23 from the home position into the nip portion 22c of the folding roller pair 22 is referred to as the "protrusion direction," and the direction in which the blade carrier 24 returns the folding blade 23 from the nip portion 22c side to the home position is referred to as the "return direction."

[0076] When in the home position, the tip of the folding blade 23 is substantially flush with the guide surface 21a or is located further toward the return direction than the guide surface 21a (first position) and is separated from the sheet S in the sheet stacking tray 21. Therefore, a sheet guided by the guide surface 21a and transported through the sheet stacking tray 21 will not be caught by the tip of the blade. Note that even when the tip of the folding blade 23 protrudes toward the folding roller 22a from the guide surface 21a, if a sheet transported to the sheet stacking tray 21 by another guide member does not get caught by the tip of the blade, it can be said that the tip of the blade is retracted from the sheet transport path. Therefore, this state may be referred to as the first position. Furthermore, when the blade guide member 40 is in the home position, the abutting portion 40a of the blade guide member 40 is in a position abutting the pivot shaft 31. At this time, the pressing protrusion 24b is separated from the base portion 40e.

[0077] Next, to protrude the folding blade 23, the cam drive motor is driven, causing the cam member 25 to rotate and move the blade carrier 24 in the protruding direction. Then, the pressing protrusion 24b comes into contact with the base portion 40e, and the blade guide member 40 moves in the protruding direction together with the blade carrier 24 and the folding blade 23 (FIG. 16(b)). At this time, the tip of the folding blade 23 is configured to protrude further in the protruding direction than the tip of the blade guide member 40.

[0078] When the blade carrier 24 moves further in the protruding direction, the tip of the folding blade 23 protrudes a predetermined amount and comes into contact with the sheet S stopped on the sheet stacking tray 21 (second position), as shown in FIG. 17(a). At this time, the sheet S has been folded a first time, and the second folding position faces the folding blade 23 and is stopped on the sheet stacking tray 21. Also, at this time, as described above, the tip of the folding blade 23 protrudes further in the protruding direction than the blade guide member 40, so the folding blade 23 comes into contact with the folding position of the sheet S before the blade guide member 40. Therefore, due to the protrusion of the folding blade 23, the tip of the folding blade facing the folding position of the sheet accurately comes into contact without being deviated from the folding position of the sheet, and the folding process is performed at the correct folding position.

[0079] Furthermore, the tip of the folding blade does not necessarily have to protrude relative to the blade guide member 40, but as long as it is in the same position as the blade guide member 40 in the protruding direction, it is possible to prevent the tip of the blade from shifting when it abuts the folding position of the sheet.

[0080] When the blade carrier 24 moves in the protruding direction in the above state, the folding blade 23 protrudes the second folding position of the sheet S toward the nip portion 22c of the pair of folding rollers 22. At the same time, the contact portion 40a of the blade guide member 40 contacts the folded end S2 of the sheet that has been folded the first time, and guides the folded end S2 so as to push it toward the nip portion 22c (FIG. 17(b)).

[0081] As described above, because the blade guide member 40 guides the folded end S2 of the sheet toward the nip portion 22c, the folded end S2 of the sheet moves toward the nip portion 22c without turning up. Furthermore, as the blade guide member 40 approaches the nip portion 22c, there is a risk that the protruding blade guide member 40 may interfere with the outer peripheries of the folding rollers 22a and 22b. In this case, as described above, the angle of the contact portion 40a of the blade guide member 40 relative to the protruding direction changes to an acute angle as the blade guide member 40 moves in the protruding direction (changing from the state shown in FIG. 17(a) to the state shown in FIG. 17(b)). Therefore, the contact portion 40a can enter closer to the nip portion 22c, thereby reliably guiding the folded end S2 of the sheet toward the nip portion.

[0082] When blade carrier 24 moves further in the protruding direction and abutment portion 40e2 abuts against rotation shaft 31 as shown in FIG. 17(b), further movement of blade guide member 40 in the protruding direction is restricted. Note that, when blade guide member 40 has moved to the furthest position in the protruding direction, the tip of blade guide member 40 (the end on the folding roller pair 22 side in the protruding direction) protrudes toward nip portion 22c beyond a tangent line (between two folding rollers 22a and 22b) connecting the outer peripheries of folding roller 22a and folding roller 22b on the sheet stacking tray 21 side. On the other hand, when blade carrier 24 is pushed out in the protruding direction by rotation of cam member 25, pressing protrusion 24b applies a force of a certain level or more to coil spring 52, so that pressing protrusion 24b rotates clockwise against the biasing force of coil spring 52 and slides under base portion 40e, as shown in FIG. 18(a). As a result, the pressing protrusion 24b no longer presses the blade guide member 40, and the blade guide member 40 remains stationary, and only the folding blade 23 moves in the protruding direction until the blade tip protrudes to the maximum extent and moves to a position (third position) where the folding blade 23 protrudes the sheet S into the nip portion 22c. At this time, the tip of the folding blade 23 protrudes farther than the tip of the contact portion 40a of the blade guide member 40. That is, the distance from the blade tip to the contact portion tip at the third position is greater than the distance from the blade tip to the contact portion tip at the second position. As a result, the sheet is reliably drawn into the nip portion 22c of the rotating folding roller pair 22 in a state where it has been folded at the second folding position, and the sheet tip S1 is also drawn into the nip portion 22c, resulting in a three-fold state.

[0083] Note that when the folding blade 23 is protruding a sheet, that is, when the tip of the folding blade is moving from the second position to the third position, if a large load is applied to the blade guide member 40 in the return direction, for example, when folding a stack of multiple sheets and the sheets are highly rigid, a large load is applied to the blade guide member 40 during the folding process. In this case, when a load exceeding a certain level is applied, the blade guide member 40 can move in the return direction relative to the folding blade 23 against the frictional force with the pressing protrusion 24b, which is pressed against the bottom surface of the base portion 40e by the biasing force of the coil spring 52. This prevents the blade guide member 40 from being damaged when a large load is applied to the blade guide member 40 during the folding process of the sheets.

[0084] When the cam member 25 rotates further after the tip of the folding blade reaches the third position, the blade carrier 24 moves in the return direction together with the folding blade 23 (FIG. 18(b)). At this time, as described above, the pressing protrusion 24b is pressed against the base portion 40e of the blade guide member 40 by the biasing force of the coil spring 52. Therefore, the frictional force between the pressing protrusion 24b and the bottom surface of the base portion 40e causes the blade guide member 40 to move integrally with the blade carrier 24, i.e., simultaneously with the folding blade 23, in the return direction.

[0085] When the cam member 25 further rotates and the blade carrier 24 moves in the return direction, the abutment portion 40a of the blade guide member 40 abuts against the rotation shaft 31, and the blade guide member 40 returns to the home position. Further movement of the blade guide member 40 in the return direction is restricted (FIG. 19(a)). When the cam member 25 further rotates, only the folding blade 23 moves in the return direction and returns to the home position, with the blade guide member 40 not moving (FIG. 19(b)).

[0086] As described above, when the blade carrier 24 moves in the return direction, the folding blade 23 and the blade guide member 40 simultaneously move in the return direction, and the blade guide member 40 returns to its home position before the blade carrier 24 and the folding blade 23 return to their home positions. In other words, the blade guide member 40 retreats from the sheet drawn in by the pair of folding rollers 22 and the discharge roller 17b earlier than the folding blade 23. This reduces the transport load of the sheet S drawn in by the discharge roller 17b and the like, which is exerted by the blade guide member 40.

[0087] (Arrangement relationship between the blade guide member and the pressure guide member) In this embodiment, as shown in FIG. 4, which is a schematic plan view of the folding device F, two blade guide members 40 are arranged at predetermined positions in the sheet width direction. The folding blade 23 in this embodiment has six protruding tip portions 23a formed at approximately equal intervals in the sheet width direction on the protruding side. These protruding tip portions 23a protrude the sheet, causing the sheet to be protruded into the nip portion 22c of the folding roller pair 22, thereby performing folding processing. The blade guide member 40 is arranged above the protruding tip portion 23a1 of the six protruding tip portions 23a, i.e., on the upstream side in the conveying direction of the sheet conveyed to the sheet stacking tray 21. Therefore, the folding end portion S2 of the sheet S protruded by the folding blade 23 is guided by the blade guide members 40 on both sides in the width direction.

[0088] To guide the folded edge S2 of the sheet into the nip 22c, it is desirable to position the blade guide member 40 above all six of the thrust tips 23a (23a1), but positioning it at all of them would increase the number of parts. In contrast, in this embodiment, as described above, the blade guide member 40 is positioned at the two thrust tips 23a1 formed on both ends of the sheet in the width direction, thereby reducing the number of parts. Furthermore, the folded edge S2 of the sheet pushed out by the folding blade 23 during the second folding process is more likely to curl up near the edge than in the center in the sheet width direction. Therefore, by guiding this portion toward the nip with the blade guide member 40, this curling can be effectively prevented.

[0089] The two blade guide members 40 are arranged above the protruding tip 23a1, which is formed slightly closer to the center than either end in the sheet width direction of the smallest width sheet that can be conveyed to the sheet stacking tray 21, rather than at either end. This is because, when protruding a sheet with the protruding tip 23a, it is more effective to protrude the sheet slightly closer to the center than the end in the sheet width direction, and the blade guide members 40 are arranged to correspond to the position of the protruding tip 23a1.

[0090] With respect to the position of the blade guide member 40, the pressing guide member 30 of this embodiment is disposed further outward in the sheet width direction than the two blade guide members 40. Specifically, the two pressing guide members 30 are disposed at a distance substantially equal to the width of the smallest size sheet that can be processed by the folding processing device F, and are disposed at positions where they can press and guide both widthwise edges of the sheet when folding the smallest size sheet. Note that in this embodiment, in addition to the two pressing guide members 30 that can press and guide both widthwise edges of the sheet, another pressing guide member 30 that can press and guide the center of the sheet width direction is provided, for a total of three pressing guide members 30. More specifically, the smallest size sheet that can be processed by the folding processing device F in this embodiment is A4, and the width in the short direction of a typical A4-size sheet is 210 mm. The two pressing guide members 30 that can press and guide both widthwise edges of the sheet are formed to have a length of 18 mm in the sheet width direction. The length of a straight line connecting the outer edges of the two pressure guide members 30 is 226 mm, which is longer than the width of an A4 size sheet, and the widthwise edges of an A4 size sheet overlap 10 mm on each side of a portion near the center of the widthwise surface of the pressure guide members 30. The maximum size sheet that can be processed by the folding device F is A3, and the width in the short direction of a typical A3 size sheet is 297 mm. By setting the length of a straight line connecting the outer edges of the two pressure guide members 30, which can press and guide both ends of the widthwise direction of the sheet, longer than the width of the smallest size sheet, it is possible to provide a guide effect for the edges of even the largest size sheet.

[0091] When the sheet that has undergone the first folding process is fed back and the pressing guide member 30 presses the folded end S2 of the sheet to guide it back to the sheet stacking tray 21 as described above, pressing and guiding both ends in the sheet width direction is effective in preventing curling. For this reason, the two pressing guide members 30 are arranged outboard in the sheet width direction than the blade guide member 40. In this embodiment, the pressing guide members 30 arranged on both sides in the sheet width direction are arranged at a distance substantially equal to the width of the minimum size sheet, and the blade guide member 40 is arranged further inward at a distance shorter than the width of the minimum size sheet.

[0092] In this embodiment, the pushing guide members 30 each have a push tip 23a2 disposed on the outer side. The push tip 23a2 is intended to prevent wrinkles from forming in the sheet when pushing a large sheet in the sheet width direction, and is disposed inside both ends of the largest sheet size. Push tip 23a2 is not required in devices that handle only the minimum size sheets described above. In other words, it is desirable to position the pushing guide members 30 and the blade guide member 40 to accommodate the smallest size sheet, but a separate push tip 23a2 may be disposed outside the pushing guide member 30 as needed. In other words, the blade guide member 40 is disposed inside the two pushing guide members 30 in the sheet width direction, and the push tip 23a1 is disposed corresponding to the position of the blade guide member 40. Further push tip 23a2 may be disposed outside the two pushing guide members 30 depending on the size of the sheet being handled.

[0093] Furthermore, if there is a large difference between the minimum and maximum sizes that the device can handle, it is possible to provide a blade guide member 40, a thrust tip 23a1 provided with the blade guide member 40, and two pressing guide members 30 corresponding to the minimum size, and a blade guide member 40, a thrust tip 23a2 provided with the blade guide member 40, and two pressing guide members 30 corresponding to the maximum size. Note that, although this embodiment shows an aspect in which two thrust tips 23a1 provided with blade guide members 40 are provided on either side of the center of the sheet S, it is also possible to configure with one thrust tip 23a1 and one blade guide member 40.

[0094] In this embodiment, the pressing guide member 30 is disposed between the thrusting tip portions 23a1 and 23a2 so as not to interfere with the thrusting tip portions 23a1 and 23a2 when the pressing guide member 30 moves to the guide position. This allows the various components to be disposed in a space-saving manner.

[0095] <Drive control> Next, the control configuration of the drive system when folding a sheet will be described. As shown in the block diagram of Fig. 20, control unit 60 controls the drive of folding roller motor 61, which drives and rotates folding roller pair 22, discharge roller motor 62, which drives and rotates discharge roller 17b, and regulation stopper motor 63, which operates sheet lifting mechanism 27 to lift and lower regulation stopper 26, in accordance with the procedures of the flowcharts shown in Figs. 21 and 22. Similarly, control unit 60 also controls the drive of cam motor 64, which drives cam member 25 to operate blade carrier 24, and pressure guide motor 33, which rotates pressure guide member 30.

[0096] 21 and 22 are flowcharts showing the drive control procedure when a sheet S is transported to the sheet stacking tray 21, the leading edge of the sheet strikes the regulating stopper 26 stopped at a predetermined position, and the first folding position is positioned opposite the folding blade 23, and then a folding process is performed.

[0097] When the folding process is performed, the cam motor 64 is driven to move the blade carrier 24 in the protruding direction, and the folding blade 23 abuts against the first folding position of the sheet S and protrudes into the nip portion 22c (S1). At the same time, the folding roller motor 61 and the discharge roller motor 62 are driven to rotate the pair of folding rollers 22 and the discharge roller 17b in the forward direction (S2). Each of the motors uses a pulse motor, and when the motor is driven, the number of drive pulses is counted.

[0098] As the cam member 25 rotates, the folding blade 23 protrudes the first folded portion of the sheet S by a predetermined amount up to the nip portion 22c of the pair of folding rollers 22, and then reverses its direction of travel and moves in the return direction to return to the home position (S3).

[0099] The sheet S, which is protruded into the nip portion 22c of the pair of folding rollers 22 by the protrusion of the folding blade 23, is folded while being sandwiched and conveyed by the pair of folding rollers 22, and is then conveyed by the discharge roller 17b, which, together with the pair of folding rollers 22, constitutes a sheet conveying means. When the sheet is sandwiched and conveyed by the discharge roller 17b (S4), the folding roller motor 61 stops when the second roller surfaces 22a3 and 22b3 of the folding rollers 22a and 22b face each other (S4, S5). As a result, the pair of folding rollers 22 no longer nip the sheet, and the sheet is conveyed by the discharge roller 17b. At this time, the sheet is conveyed by the discharge roller 17b while being guided by the second roller surfaces 22a3 and 22b3, which have a small coefficient of friction. In this embodiment, whether the sheet has been conveyed to the discharge roller 17b and whether the second roller surfaces 22a3 and 22b3 of the pair of folding rollers 22 face each other is determined by counting pulses of the motor, but this is not limited to this. Alternatively, the sheet S may be detected by a sensor, and the drive of the motor may be controlled in accordance with the detection result.

[0100] Then, when the position of the folded end S2 of the conveyed sheet S reaches within a predetermined area (S7), the driving of the discharge roller motor 62 is stopped to stop the sheet conveyance (S8). This predetermined area is the area between the folded end S2 of the sheet and the rotation trajectory L3 of the pressing guide member 30 and the guide surface 21a of the sheet stacking tray 21 (see FIG. 14(a)). The sheet is stopped so that the folded end S2 is within this area. This allows the pressing portion 30c to reliably press the sheet S in the switchback conveyance direction when the pressing guide member 30 is rotated (see FIG. 14(b)). Furthermore, the folded end S2 being conveyed in the switchback conveyance can be guided by the guide portion 30b (see FIG. 14(c)).

[0101] After the folded end S2 of the sheet S is stopped within the area, the pressing guide motor 33 is driven to rotate the pressing guide member 30 so that the guide portion 30b of the pressing guide member 30 can guide the sheet S being switched back (the position shown in FIG. 14(c)) (S9). In addition, together with the rotation of the pressing guide member 30, the regulating stopper motor 63 is driven to move the regulating stopper 26 to a position where it can accept the sheet S being switched back.

[0102] After the pressing guide member 30 has rotated as described above, the discharge roller motor 62 and the folding roller motor 61 are driven in the reverse direction (S10). This causes the discharge roller 17b and the pair of folding rollers 22 to rotate in the reverse direction, causing the sheet S to be switched back and conveyed. At this time, since the sheet is guided by the pressing guide member 30 as described above, the sheet is switched back and conveyed in the direction in which the regulating stopper 26 of the sheet stacking tray 21 is disposed without causing any conveyance problems.

[0103] The discharge roller motor 62 and the folding roller motor 61 are driven to switchback convey the sheet S, and the sheet S that has passed through the nip portion 22c of the folding roller pair 22 falls until it abuts against the regulating stopper 26, completing the switchback conveyance (S11). When the switchback conveyance is completed, the driving of the discharge roller motor 62 and the folding roller motor 61 is stopped (S12). Here, the completion of the switchback conveyance of the sheet S may be determined by counting the number of drive pulses of the discharge roller motor 62 and the folding roller motor 61 and determining whether the sheet S has been conveyed a predetermined amount.

[0104] Next, the pressing guide motor 33 is driven to return the pressing guide member 30 to the retracted position. At this time, the speed at which the pressing guide member 30 is returned from the guide position (see FIG. 14(c)) to the retracted position (see FIG. 14(a)) is set to be faster than the speed at which the pressing guide member 30 is moved from the retracted position to the guide position. When the pressing guide member 30 is moved from the retracted position to the guide position, the speed is reduced to press and change the orientation of the stopped sheet S for switchback conveyance, whereas when the pressing guide member 30 is moved from the guide position to the retracted position, the speed is returned quickly, thereby making it possible to advance the timing for executing the next operation.

[0105] Then, after the pressing guide member 30 is moved to the reverse conveyance guide position (see FIG. 9(a)) (S13), the regulating stopper motor 63 is driven to move the second folding position of the sheet S to a position facing the folding blade 23 (S14). In this state, the cam motor 64, the folding roller motor 61, and the discharge roller motor 62 are driven to perform the second folding operation (S15 to S17).

[0106] In this embodiment, a motor is provided to drive each member individually, but it is also possible to use a common motor and drive each member by switching the drive using a clutch or the like.

[0107] <Other embodiments> In the above-described embodiment, when the folding blade 23 and the blade guide member 40 are moved relative to each other, the engaging protrusion 40d of the blade guide member 40 slides through the elongated hole 50, changing the angle of the abutting portion 40a relative to the base portion 40e. However, the angle of the abutting portion 40a relative to the base portion 40e may be fixed and unchangeable without providing the link mechanism. Even in this case, the folding blade 23 is configured to be movable relative to the blade guide member 40, and the folding blade 23 continues to protrude and protrude the sheet into the nip portion 22c even after the movement of the blade guide member 40 stops during protrusion. This allows the sheet to be reliably protruded into the nip portion 22c without interfering with the blade guide member 40 and the folding roller pair 22. Furthermore, the configuration can be simplified by not providing an angle changing mechanism.

[0108] In the above-described embodiment, folding rollers 22a and 22b are configured as rollers having first roller surfaces 22a2 and 22b2 with a constant circular outer diameter and second roller surfaces 22a3 and 22b3 with a smaller outer diameter. However, folding rollers 22a and 22b may also be configured as rollers with a constant outer diameter, such as circular rubber rollers. In this case, when a sheet passes through the pair of folding rollers, the sheet is constantly sandwiched in the nip portion of the pair of folding rollers, so the sheet conveyance amount can be controlled by the rotation of the pair of folding rollers. Therefore, when stopping the folded edge of the sheet at a predetermined position (see FIG. 7(a)), the amount of drive of the folding rollers can be controlled.

[0109] In the above-described embodiment, an example has been shown in which the folding blade 23 and the blade guide member 40 start moving in the return direction simultaneously when the tip of the folding blade is in the third position. However, for example, the folding blade 23 and the blade guide member 40 may be configured to be operated by different drive systems, and the folding blade 23 may start moving in the return direction first, followed by the blade guide member 40.

[0110] Even when the tip of the folding blade protrudes to the third position and the folded portion of the sheet is nipped by the pair of folding rollers 22, the folded end S2 has not yet been nipped by nip portion 22c (see FIG. 18(a)), and is nipped later. Even in this case, by returning the blade guide member 40 slower than the folding blade 23, even if the folding blade 23 starts to move in the return direction, the folded end S2 is guided by the blade guide member 40, and is therefore reliably drawn into nip portion 22c.

[0111] In the above-described embodiment, an example was shown in which the sheet transport amount and the rotation amount of the pressure guide member 30 were controlled by counting the number of motor pulses, but this is not limited to this. In addition to motor pulses, for example, a photosensor that detects the sheet or the pressure guide member 30 may be provided, and this sensor detects that the sheet has been transported to a predetermined position or that the pressure guide member 30 has been rotated to a predetermined angle. In this way, a configuration may be adopted in which the sheet transport or the rotation amount of the pressure guide member is detected to control the sheet transport or the rotation of the pressure guide member.

[0112] In the above-described embodiment, the regulating stopper 26 is disposed at the lower end of the sheet stacking tray 21 to abut against and regulate the leading edge of the conveyed sheet in the conveying direction, and the regulating stopper 26 is provided so as to be movable up and down along the sheet stacking tray 21 by the sheet lifting mechanism 27. In other embodiments, roller pairs may be disposed to convey the sheet on the upstream side or downstream side in the sheet conveying direction, sandwiching the folding blade 23 and the folding roller pair 22 of the sheet stacking tray 21 between them. In this case, the sheet S that has been subjected to the first folding process can be returned to either the upstream side or the downstream side in the sheet conveying direction, sandwiching the folding blade 23 and the folding roller pair 22 of the sheet stacking tray 21 between them, when being switchback-conveyed.

[0113] <Modification> 23 to 29 show modified examples of the blade guide member 40 and blade carrier 24 (blade guide member 140 and blade carrier 124). The function of the blade guide member 140 is the same as in the embodiment described above, and the same reference numerals are used to designate components that are common to the embodiment described above, and a description thereof will be omitted. FIG. 23 is a perspective view showing a state in which the blade guide member 140 has moved in the protruding direction. Note that a pressing guide member 30 is provided on the right side of the blade guide member 140 in FIG. 23, but is not shown for convenience.

[0114] The blade guide member 140 is composed of a contact portion 140a, an arm portion 140c, an engaging protrusion 140d, a locking portion 140e, a pivot point 140f, a pressed portion 140g, and a locking protrusion 140h. The contact portion 140a is a member that contacts and guides a sheet. One end of the contact portion 140a is provided with the pivot point 140f. The other end of the contact portion 140a is provided with the arm portion 140c, an engaging protrusion 140d that slidably engages with an elongated hole 50 formed in the frame of the sheet processing apparatus B, and a locking portion 140e formed to tension a tension spring 151 between the arm portion 140c, the engaging protrusion 140d that slidably engages with an elongated hole 50 formed in the frame of the sheet processing apparatus B, and a locking portion 124a formed in the frame of the sheet processing apparatus B. The blade guide member 140 is biased upward in FIG. 25 by the tension spring 151. 25, a pressed portion 140g that is in contact with a pressing protrusion 124b1 (described later) is provided on the back side of the abutting portion 140a (upstream side in the protruding direction). The pressed portion 140g is pushed in the protruding direction by the pressing protrusion 124b1, causing the abutting portion 140a to rotate clockwise in FIG. 25 around a rotation fulcrum 140f. In other words, the abutting portion 140a is configured to be angle-changeable from an upright position that is substantially perpendicular to the folding blade 23 as shown in FIG. 25 to a position that is tilted toward the upstream side in the protruding direction around the rotation fulcrum 140f as shown in FIG. The locking protrusion 140h bent from the rotation fulcrum 140f is a stopper that prevents the pressed portion 140g from coming off the pressing protrusion 124b1 when the pressing protrusion 124b1 is pressing the pressed portion 140g.

[0115] The blade carrier 124 holds the folding blade 23 and the slide rail 124c, and is configured to be movable integrally in the protruding direction and the returning direction by the cam member 25 (as in the embodiment described above). The slide rail 124c holds the pressing member 124b so that it can slide in the protruding direction and the returning direction. The pressing member 124b has a pressing protrusion 124b1 formed at the downstream end of the pressing member 124b in the protruding direction, a locking portion 124b2 formed at the upstream end of the pressing member 124b in the protruding direction and locking with the spring 124e, and a contact portion 124d formed between the pressing protrusion 124b1 and the locking portion 124b2.

[0116] Figure 24 is a top view of the blade guide member 140 and the blade carrier 124. Figure 24(a) shows the state in which the blade carrier 124 is in the home position (the thrusting tip 23a1 is in the first position). Figure 24(b) shows the state in which the blade carrier 124 has been moved a predetermined amount in the thrusting direction by the cam member 25 (the thrusting tip 23a1 is in the second position). Figure 24(c) shows the state in which the blade carrier 124 has further moved in the thrusting direction, causing the thrusting tip 23a1 to protrude to the maximum extent and thrust the sheet S into the nip portion 22c (the thrusting tip 23a1 is in the third position).

[0117] A locking portion 124f to which one end of a spring 124e is attached is provided on the blade carrier 124. The other end of the spring 124e is attached to a locking portion 124b2 of the pressing member 124b, and the pressing member 124b is biased in the protruding direction (downward in FIG. 24) on the slide rail 124c by this spring 124e.

[0118] 25, pressing member 124b and slide rail 124c are provided with protrusions 124b3 and 124c1, respectively. Protrusions 124b3 and 124c1 engage with each other, restricting the movement of pressing member 124b in the protruding direction even when spring 124e biases pressing member 124b in the protruding direction at the home position. When blade carrier 124 moves in the protruding direction in this state, slide rail 124c moves in the protruding direction, and protrusion 124c1 on slide rail 124c also moves in the protruding direction. As protrusion 124c1 moves, pressing member 124b biased by spring 124e also moves in the protruding direction.

[0119] 25, the pressing member 124b moves in the protruding direction, causing the pressing protrusion 124b1 to press the pressed portion 140g of the blade guide member 140 and move the abutting portion 140a of the blade guide member 140 in the protruding direction. At this time, the blade guide member 140 rotates clockwise around the rotation fulcrum 140f against the biasing force of the tension spring 151 while the engaging protrusion 140d slides downward through the elongated hole 50.

[0120] 26 (the thrusting tip 23a1 is in the second position), the abutment portion 124d of the pressing member 124b abuts against the rotation shaft 31 of the pressing guide member 30, restricting the movement of the pressing member 124b in the thrusting direction. As a result, even if the spring 124e urges the pressing member 124b in the thrusting direction, it cannot move any further in the thrusting direction. At this position, the abutment portion 140a of the blade guide member 140 guides the sheet toward the folding roller pair 22, and the thrusting tip 23a abuts against the sheet to thrust it toward the folding roller pair.

[0121] When the blade carrier 124 moves further in the protruding direction, the state shown in FIG. 27 is reached. In FIG. 27, the blade guide member 140 remains stationary at the position shown in FIG. 26, and only the blade carrier 124, the folding blade 23 (protruding tip portion 23a), and the slide rail 124c move in the protruding direction, moving to a position (third position) where the protruding tip portion 23a1 protrudes to its maximum and protrudes the sheet S into the nip portion 22c. At this time, the protruding tip portion 23a1 of the folding blade 23 protrudes farther than the tip of the abutting portion 140a of the blade guide member 140. That is, the distance from the blade tip to the abutting tip at the third position is greater than the distance from the blade tip to the abutting tip at the second position. As a result, the sheet is reliably drawn into the nip portion 22c of the pair of folding rollers 22, which are rotating, in a state where it is folded at the second folding position, and the sheet tip S1 is also drawn into the nip portion 22c, resulting in a three-fold state.

[0122] The blade carrier 124 then moves in the return direction. At this time, the pressing member 124b remains stopped at the position shown in FIG. 26. FIG. 28 shows the state in which the thrusting tip 23a1 has returned to the second position. Here, the protrusion 124c1 on the slide rail 124c engages with the protrusion 124b3 on the pressing member 124b. If the blade carrier 124 is moved further in the return direction in this state, the slide rail 124c and the pressing member 124b simultaneously move in the return direction against the biasing force of the spring 124e. When the pressing member 124b moves in the return direction beyond the position shown in FIG. 28, the pressing protrusion 124b1 moves in a direction away from the pressed portion 140g of the blade guide member 140, and the blade guide member 140 changes angle to the upright position shown in FIG. 29 due to the biasing force of the tension spring 151.

[0123] Note that when the folding blade 23 is protruding a sheet, i.e., when the protruding tip 23a1 is moving from the second position to the third position, if a large load is applied to the blade guide member 140 in the return direction, for example, when folding multiple stacked sheets and the sheets are highly rigid, a large load is applied to the blade guide member 140 during folding. In this case, if a load exceeding a certain level is applied, the blade guide member 140 can move in the return direction relative to the folding blade 23 against the spring 124e. As described above, the blade guide member 140 is biased in the protruding direction by the spring 124e via the pressing member 124b. Therefore, when a load greater than the biasing force of the spring 124e is applied to the blade guide member 140, the blade guide member 140 can move in the return direction along the slide rail 124c. This prevents the blade guide member 140 from being damaged when a large load is applied to the blade guide member 140 during sheet folding.

[0124] <Deflection Guide> The sheet processing apparatus further includes a deflection guide 170 as a guide means for guiding a sheet between the first transport guide member 181 and the first stacking guide member 184, and a pressing means for pressing a folded sheet via its fold. The deflection guide 170 and the pressing means will be described below with reference to Figures 30 to 33.

[0125] In the following description, a configuration in which the deflection guide 170 serving as the guide means also serves as the pressing means, i.e., a configuration in which the guide means and the pressing means are the same member, is described as an example, but the present invention is not limited to this. A pressing means may be provided separately from the deflection guide 170 serving as the guide means.

[0126] 30 to 33 are diagrams illustrating a deflection guide 170 provided between the folding roller 22a and the guide surface 21a of the sheet stacking tray 21. The deflection guide 170 has a flexible guide member 170a (such as Mylar) that comes into contact with and guides the sheet S, and one end of the guide member 170a is fixed to a bracket 172. The bracket 172 has an engagement piece 171 that protrudes toward the folding roller 22a, and this engagement piece 171 is positioned by engaging with an engagement portion 22d (see FIG. 33) of the folding roller 22a. The engagement portion 22d of the folding roller 22a has a first roller surface 22a2 that has a constant radius R1 centered on the rotational axis of the rotation shaft 22a1, and a second roller surface 22a3 that is spaced a distance from the rotational axis of the rotation shaft 22a1 that is smaller than the radius R1 of the first roller surface 22a2. When folding roller 22a rotates with engagement piece 171 engaged with engagement portion 22d, bracket 172 holding guide member 170a is configured to be rotatable around rotation shaft 173. The surface of engagement portion 22d with which engagement piece 171 engages is formed of a plastic resin material or the like having a small coefficient of friction.

[0127] In this embodiment, guide member 170a is provided with a guide area capable of guiding conveyed sheet S, and the lower end of the guide area in Fig. 30 is called first end 170a1, and the upper end is called second end 170a2. If bracket 172 is also capable of guiding sheet S, the sheet guide area of ​​bracket 172 is also considered to be part of guide member 170a, and second end 170a2 is the upper end of the guide area of ​​bracket 172.

[0128] In this embodiment, the space sandwiched between the first transport guide member 181 and the second transport guide member 182 that form the sheet transport path 20 is called a guide space 180. The space sandwiched between the first stacking guide member 184 and the second stacking guide member 185 that form the sheet stacking tray 21 is called a storage space 183.

[0129] The first transport guide member 181 guides the sheet. The second transport guide member 182 is disposed opposite the first transport guide member 181 and guides the sheet. The first transport guide member 181 and the second transport guide member 182 form a transport guide pair and guide the sheet transported between the first transport guide member 181 and the second transport guide member 182 in a first direction. The first transport guide member 181 and the second transport guide member 182 guide the sheet in a second direction that is opposite to the first direction. Here, the first direction is the direction of arrow y1 shown in FIG. 30(a) and is a first transport direction described later. The second direction is the direction of arrow y2 shown in FIG. 31(a) and is a second transport direction described later.

[0130] The first stacking guide member 184 is disposed downstream of the first transport guide member 181 in the first direction with a predetermined gap between it and the first transport guide member 181, and guides the sheets. The second stacking guide member 185 is disposed opposite the first stacking guide member 184 and guides the sheets. The first stacking guide member 184 and the second stacking guide member 185 form a stacking guide pair (storage section), and guide the sheets transported between the first stacking guide member 184 and the second stacking guide member 185 via the transport guide pair in the first direction. The first stacking guide member 184 and the second stacking guide member 185 also guide the sheets in the second direction.

[0131] The second transport guide member 182 and the second stacking guide member 185 are members corresponding to the sheet stacking tray 21 shown in Fig. 5 and the like. Here, the second transport guide member 182 and the second stacking guide member 185 are configured as one sheet stacking tray 21, but this configuration is not limiting. The second transport guide member 182 and the second stacking guide member 185 may be separate guide members, that is, the sheet stacking tray 21 may be one member in the transport direction, or may be configured with multiple guide members.

[0132] The deflection guide 170 as a guide means is provided between the first conveying guide member 181 and the first stacking guide member 184 in the first direction. The deflection guide 170 is provided between the folding roller pair 22 and the second conveying guide member 182 in the protruding direction of the folding blade 23.

[0133] The deflection guide 170 is arranged to be movable between a first guide position shown in FIG. 30 and a second guide position shown in FIG. 31 between the first transport guide member 181 and the first stacking guide member 184, centered on a rotation axis 173.

[0134] Fig. 30 shows how the sheet S is transported from the guide space 180 toward the storage space 183 (this direction is called the first transport direction) with the engagement piece 171 engaged with the first roller surface 22a2 and the guide member 170a positioned at the first guide position. Fig. 31 shows how the sheet S (in this figure, a sheet S that has been folded once) is transported from the storage space 183 toward the guide space 180 (this direction is called the second transport direction) with the engagement piece 171 engaged with the second roller surface 22a3 and the guide member 170a positioned at the second guide position.

[0135] Fig. 32(a) shows a state in which the guide member 170a is positioned at the first guide position, and Fig. 32(b) shows a state in which the guide member 170a is positioned at the second guide position. The dashed-dotted line 186 in the figure is a line (hereinafter referred to as the imaginary line 186) connecting a transport guide end 181a, which is the downstream end of the first transport guide member 181 in the first transport direction, and a load guide end 184a, which is the downstream end of the first load guide member 184 in the second transport direction.

[0136] The first guide position shown in Figures 30 and 32(a) is a guide position where the deflection guide 170 guides the sheet in a first direction (the direction of arrow y1 shown in Figure 30(a), the first conveying direction). The second guide position shown in Figures 31 and 32(b) is a guide position different from the first guide position, and is a guide position where the deflection guide 170 guides the sheet in a second direction (the direction of arrow y2 shown in Figure 31(a), the second conveying direction) that is opposite to the first direction. The guide member 170a is positioned at the first guide position or the second guide position with respect to the virtual line 186.

[0137] 32(a), when guide member 170a is positioned at the first guide position, first end 170a1 of guide member 170a is positioned on the opposite side of folding roller 22a (guide surface 21a side) in the thickness direction of sheet S from imaginary line 186. Second end 170a2 is positioned on the folding roller 22a side in the thickness direction of sheet S from imaginary line 186. This allows the leading edge of sheet S (downstream end in the first conveying direction) to be guided from guide space 180 to storage space 183 when sheet S is conveyed in the first conveying direction as shown in FIGS.

[0138] That is, the deflection guide 170 can receive a sheet transported from between the first transport guide member 181 and the second transport guide member 182 at the first guide position shown in Figure 32(a) and guide it to between the first stacking guide member 184 and the second stacking guide member 185.

[0139] The first end 170a1 of the deflection guide 170 is the end on the downstream side in the first transport direction, and the second end 170a2 of the deflection guide 170 is the end on the upstream side in the first transport direction.

[0140] 32(b), when guide member 170a is positioned at the second guide position, first end 170a1 of guide member 170a is positioned closer to folding roller 22a in the thickness direction of sheet S than imaginary line 186. Second end 170a2 is positioned on the opposite side of folding roller 22a (guide surface 21a side) in the thickness direction of sheet S than imaginary line 186. This allows the leading edge of sheet S (downstream end in the second conveying direction) to be guided from storage space 183 to guide space 180 when sheet S is conveyed in the second conveying direction as shown in FIGS.

[0141] That is, the deflection guide 170 can receive a sheet transported from between the first stacking guide member 184 and the second stacking guide member 185 at the second guide position shown in Figure 32(b) and guide it to between the first transporting guide member 181 and the second transporting guide member 182.

[0142] 32(a), first end 170a1 of guide member 170a is positioned closer to guide surface 21a than imaginary line 186. However, the present invention is not limited to this. For example, if the leading edge of a sheet is guided between first stacking guide member 184 and second stacking guide member 185 when the sheet is conveyed in the first conveying direction, first end 170a1 of guide member 170a may be positioned on imaginary line 186. In this case, when deflection guide 170 is positioned at the first guide position, second end 170a2 is positioned closer to folding roller pair 22 than first end 170a1 in the protruding direction.

[0143] 32(b), the second end 170a2 of the guide member 170a is positioned closer to the guide surface 21a than the imaginary line 186. However, the present invention is not limited to this. For example, if the leading edge of the sheet is guided between the first transport guide member 181 and the second transport guide member 182 when the sheet is transported in the second transport direction, the second end 170a2 of the guide member 170a may be positioned on the imaginary line 186. In this case, when the deflection guide 170 is positioned at the second guide position, the first end 170a1 is positioned closer to the folding roller pair 22 than the second end 170a2 in the protruding direction.

[0144] Furthermore, in this example, the guide means is configured to be movable between the first guide position and the second guide position, but this is not limiting. The guide means may be configured to be fixed to the sheet processing apparatus. For example, the guide means may be configured such that the first end 170a1 and the second end 170a2 are positioned closer to the pair of folding rollers 22 than the imaginary line 186, and the intermediate portion between the first end 170a1 and the second end 170a2 is positioned closer to the guide surface 21a than the imaginary line 186. If the guide means has such a shape, it may be configured to be fixed to the sheet processing apparatus.

[0145] As shown in Fig. 33, a plurality of guide members 170a are provided in the width direction of sheet S. In this embodiment, two guide members 170a are arranged on either side of the center of the sheet width inside the smallest sheet width in the sheet width direction. The broken lines in Fig. 33 indicate folding rollers 22a and 22b, and engagement piece 171 is provided at a position corresponding to engagement portion 22d of folding roller 22a. Furthermore, guide member 170a is arranged at a position corresponding to the two innermost pushing tips 23a of the six pushing tips 23a, 23a1, and 23a2.

[0146] The guide member 170a guides the sheet S not only when the sheet S is transported in the first transport direction and the second transport direction, but also when the folding blade 23 performs a protruding operation. As described above, Figure 25 shows a state in which the folding position of the sheet S is positioned opposite the folding blade 23 when performing the folding process. In Figure 25, the guide member 170a is positioned at the first guide position.

[0147] In this state, when folding blade 23 is moved in the protruding direction, the position of sheet S is stabilized between guide member 170a and abutment portion 140a of blade guide member 140, thereby preventing the sheet from shifting position during folding. As described above, guide member 170a is made of flexible Mylar or the like, so when sheet S abuts guide member 170a, it guides sheet S while being bent in the protruding direction.

[0148] When the pushing tip 23a1 of the folding blade 23 pushes the sheet S into the nip portion 22c of the folding roller pair 22 and then the folding roller pair 22 is rotated a predetermined amount, the engagement piece 171 engages with the second roller surface 22a3 and the guide member 170a is positioned at the second guide position (see FIG. 28). This is because if the guide member 170a continues to urge the sheet S in the return direction even after the folding end S2 of the sheet S is folded into the nip portion 22c, the conveying load of the sheet S by the folding roller pair 22 becomes large. Therefore, when the folding position of the sheet S reaches the nip portion 22c of the folding roller pair 22 and the folding process by the folding roller pair 22 begins, it is desirable to move the guide member 170a to the second guide position and guide the sheet S toward the nip portion 22c.

[0149] As described above, when the sheet S is transported in the first transport direction (sheet transport for receiving the sheet S into the sheet stacking tray 21), the guide member 170a of the deflection guide 170 is positioned at the first guide position, and guides the sheet S from the guide space 180 to the storage space 183. When the sheet S is transported in the second transport direction (sheet transport for transporting the sheet S received in the sheet stacking tray 21 to the binding processing unit 17a, or sheet transport for bringing the second folding position of the sheet S into opposition to the folding blade 23 for performing the second folding process after the first folding process has been completed), the guide member 170a of the deflection guide 170 is positioned at the second guide position, and guides the sheet S from the storage space 183 to the guide space 180.

[0150] Furthermore, when performing the folding process, the guide member 170a is positioned at the first guide position to guide the sheet S so as not to shift the folding position until the folding blade 23 pushes the sheet S into the nip portion 22c of the pair of folding rollers 22. Then, after the folding position of the sheet S reaches the nip portion 22c, the guide member 170a is positioned at the second guide position to guide the sheet S to the nip portion 22c while reducing the conveying load.

[0151] As described above, deflection guide 170 is provided so as to be movable about rotation shaft 173 between a first guide position shown in FIG. 32(a) and a second guide position shown in FIG. 32(b). Deflection guide 170 is biased by a biasing member (not shown) in a direction in which engagement piece 171 abuts against engagement portion 22d of folding roller 22a (see FIG. 33). Therefore, deflection guide 170 is moved between the first guide position and the second guide position depending on the abutment position with engagement portion 22d of folding roller 22a, which is rotated forward or backward.

[0152] 34 to 37, the deflection guide 170 of this example functions as a pressing means for pressing the folded sheet Sf when the folded sheet Sf is moved in the second conveyance direction by the regulating stopper 26 with the fold line Sf1 formed by the folding process leading. The deflection guide 170 presses the folded sheet Sf between the first stacking guide member 184 and the first conveyance guide member 181 in a pressing direction that moves the sheet Sf2 on one side, which is opposed across the fold line Sf1 of the folded sheet Sf, toward the sheet Sf3 on the other side. In other words, the deflection guide 170 also functions as the pressing means, and the deflection guide 170 and the pressing means are the same member.

[0153] 34 to 37, the operation of the deflection guide 170 to press in the pressing direction when the deflection guide 170 moves the folded sheet Sf that has been folded the first time to the second folding position between the first stacking guide member 184 and the first conveying guide member 181. This pressing operation is performed during the operations shown in FIGS. 8(b) to 9(a) and step S14 in FIG. 22, which were described in the above-described embodiment.

[0154] The deflection guide 170 in this example is movable between a first guide position shown in FIG. 32(a), a second guide position shown in FIG. 32(b), and a third guide position between the first guide position and the second guide position.

[0155] As shown in FIGS. 30 and 31, engagement portion 22d of folding roller 22a (see FIG. 33) has first roller surface 22a2, second roller surface 22a3, and also has third roller surface 23a4. Third roller surface 23a4 is located between first roller surface 22a2 and second roller surface 22a3 in the rotation direction of folding roller 22a. A third distance (radius R3) from the axis of rotation shaft 22a1 of folding roller 22a to third roller surface 23a4 is smaller than the first distance (radius R1) from the axis to first roller surface 22a2 and is larger than the second distance (radius R2) from the axis to second roller surface 22a3. Therefore, deflection guide 170 is positioned at a third guide position between the first guide position and the second guide position when engagement piece 171 abuts against third roller surface 23a4 of folding roller 22a (see FIG. 35(b)).

[0156] Note that, although the configuration shown here is one in which deflection guide 170 can be moved to a third guide position between the first guide position and the second guide position, the present invention is not limited to this. For example, when a sheet that has been folded the first time is guided in the second direction by deflection guide 170, it is also possible to press one sheet on one side of the folded sheet against the other sheet by moving deflection guide 170 from the second guide position to the first guide position.

[0157] In the case of the inner triple folding process described above, the folded sheet Sf that has been folded the first time is moved between the first stacking guide member 184 and the second stacking guide member 185. Thereafter, the regulating stopper 26 is raised so that the second folding position is a position facing the folding blade 23, and the folded sheet Sf is moved in the second conveyance direction (second direction) with the fold Sf1 at the leading edge (see FIG. 34(a)). At this time, the deflection guide 170 is positioned at the second guide position with the engagement piece 171 engaged with the second roller surface 22a3 of the folding roller 22a.

[0158] The deflection guide 170 positioned at the second guide position receives the fold Sf1 of the folded sheet Sf conveyed from between the first stacking guide members 184 and 185 and guides it in the second conveying direction (see FIG. 34(b)). The deflection guide 170 positioned at the second guide position has a larger space between the first end 170a1 and the guide surface 21a than between the second end 170a2 and the guide surface 21a (see FIG. 35(a)). Therefore, in the space between the first end 170a1 and the guide surface 21a, the sheet Sf2 on one side may bulge toward the folding roller 22a via the fold Sf1, possibly resulting in buckling.

[0159] Therefore, the folded sheet Sf is pressed by a deflection guide 170.

[0160] First, in the second conveying direction, after the fold Sf1 of the folded sheet Sf reaches the deflection guide 170 (see FIG. 34(b)), the movement of the regulating stopper 26 is temporarily stopped (see FIG. 35(a)) before the fold Sf1 passes through the deflection guide 170. More specifically, after the fold Sf1 of the folded sheet Sf reaches the first end 170a1 of the deflection guide 170, the movement of the regulating stopper 26 is temporarily stopped before the fold Sf1 passes through the second end 170a2.

[0161] Then, by rotating folding roller 22a, deflection guide 170, which also serves as a pressing means, is moved from the second guide position toward the first guide position. More specifically, folding roller 22a is rotated to bring third roller surface 23a4 of folding roller 22a into contact with engagement piece 171 of deflection guide 170, which had been in contact with second roller surface 22a3 of folding roller 22a. As a result, deflection guide 170, which also serves as a pressing means, is moved from the second guide position to the third guide position.

[0162] This causes the deflection guide 170 to function as a pressing means. That is, the deflection guide 170 presses the folded sheet Sf between the first stacking guide member 184 and the first transport guide member 181 in a pressing direction that moves the sheet Sf2 on one side toward the sheet Sf3 on the other side via the fold Sf1. This prevents the folded sheet Sf from bulging between the first stacking guide member 184 and the first transport guide member 181 (see FIG. 35(b)).

[0163] After the deflection guide 170 has restrained the bulge of the folded sheet Sf, the regulating stopper 26 resumes rising, and the conveyance (movement) of the folded sheet Sf in the second conveyance direction resumes (see FIG. 36(a)). At this time, the bulge of the folded sheet Sf has been restrained, so the folded sheet Sf is guided in the second conveyance direction while being restrained from buckling.

[0164] After pressing the folded sheet Sf in the pressing direction, the movement of the regulating stopper 26 is stopped before the fold Sf1 of the folded sheet Sf reaches the first transport guide member 181 in the second transport direction (see FIG. 36(b)).

[0165] Then, after stopping the movement of restriction stopper 26, folding roller 22a is rotated to return deflection guide 170 to the second guide position (see FIG. 37(a)). More specifically, folding roller 22a is rotated to bring second roller surface 22a3 of folding roller 22a into contact with engagement piece 171 of deflection guide 170, which had been in contact with third roller surface 23a4 of folding roller 22a. This causes deflection guide 170, which also serves as a pressing means, to return from the third guide position to the second guide position.

[0166] Thereafter, the regulating stopper 26 resumes rising, and the conveyance (movement) of the folded sheet Sf in the second conveyance direction resumes (see FIG. 37(b)). The folded sheet Sf is guided by the deflection guide 170 returned to the second guide position, and the fold Sf1, which is the leading edge of the folded sheet Sf, is guided between the first conveyance guide member 181 and the second conveyance guide member 182.

[0167] The sheet processing device (folding processing device) of this example is capable of feeding multiple sheets between the aforementioned conveying guide pair and stacking guide pair and performing folding processing on a sheet stack consisting of the multiple sheets.

[0168] 34 to 37 show a state in which one sheet is fed between the conveying guide pair and the stacking guide pair, but the deflection guide 170 also functions as a pressing means for a sheet stack consisting of multiple sheets that has been subjected to the first folding process. In other words, the deflection guide 170 functions as the pressing means when feeding the sheet stack consisting of multiple sheets that has been subjected to the first folding process to the second folding position.

[0169] In addition, in the case of a single folded sheet, when it is guided to the second folding position, the force tending to expand between first conveying guide member 181 and first stacking guide member 184 is weaker than in the case of a sheet stack consisting of two or more folded sheets. Therefore, when a single folded sheet that has been subjected to the first folding process is sent to the second folding position, it is not necessary to apply pressure using deflection guide 170. In this case, productivity is improved.

[0170] Furthermore, for a sheet stack consisting of up to a predetermined number of sheets (for example, four sheets) that have been folded the first time, the deflection guide 170 functions as a pressing means and then returns to the second guide position. However, for a sheet stack consisting of more than the predetermined number of sheets (here, five or more sheets), the deflection guide 170 does not have to return to the second guide position after functioning as a pressing means. Whether or not to return the deflection guide 170 to its original position can be set in the service mode.

[0171] As described above, according to this example, the sheet is guided by the deflection guide 170 between the first transport guide member 181 and the first stacking guide member 184, which makes it possible to prevent poor transport caused by the sheet getting caught on the pair of folding rollers. Furthermore, when the folded sheet is sent to the second folding position, bulging is suppressed between the first transport guide member 181 and the first stacking guide member 184, which makes it possible to prevent buckling of the sheet or poor transport caused by the sheet getting caught on the pair of folding rollers.

[0172] In this embodiment, guide member 170a is moved between the first guide position and the second guide position by abutting engagement piece 171 against the circumferential surface (engagement portion 22d) of folding roller 22a having a different diameter, but it may also be moved using a separate drive source. Also, while the embodiment shows a mode in which guide member 170a is disposed between folding roller 22a and guide surface 21a, it may also be disposed between folding roller 22b and guide surface 21a, or may be disposed on both sides.

[0173] In addition, in this embodiment, the first guide position of the guide member 170a during sheet conveyance and the first guide position of the guide member 170a during folding processing are the same position, but they do not need to be exactly the same position and can be changed as appropriate. Needless to say, the second position can also be changed as appropriate.

[0174] Furthermore, in all of the above-described embodiments, the sheet S is folded twice to form an inward third fold, but even in a single folding process (the first folding process for an inward third fold or a folding process for a double fold), if the above-described blade guide members 40 and 140 are provided, the sheet S can be properly guided during the folding process. [Explanation of symbols]

[0175] A...Image forming device B...Sheet processing device F...Folding device S...Seat Sf...folded sheet Sf1...crease Sf2, Sf3...sheets 21...Sheet stacking tray 21a...Guide surface 22...Folding roller pair 22a, 22b ... folding rollers 22a1, 22b1 ... Rotating shaft 22a2, 22b2 ... First roller surface 22a3, 22b3 ... Second roller surface 22a4 ...Third roller surface 22c...Nip section 22d...Engagement part 23...Folding blade 24,124 ... Blade carrier 25...Cam member 26...Regulation stopper 27 ... Seat lifting mechanism 30...Press guide member 40,140 ...Blade guide member 60...Control unit 61...Folding roller motor 62...Discharge roller motor 63 ...Regulation stopper motor 64...Cam motor 100...Image forming system 170...Deflection guide 170a ... Guide member 170a1...first end 170a2…Second end 171 ... engaging piece 172...Bracket 173... Rotating shaft 180... Guidance space 181 ... First conveying guide member 182 ... Second conveying guide member 183...Storage space 184 ... First loading guide member 185 ... Second loading guide member 186 ... virtual line

Claims

1. A sheet processing device that performs a first folding process on a sheet, then performs a second folding process at a position different from the crease formed by the first folding process, and performs an inner triple fold so that one end of the sheet folded by the first folding process is on the inside of the folded sheet, a first conveying unit that conveys the sheet in a first direction; a first conveying guide pair including a first guide that guides the sheet conveyed by the first conveying unit and a second guide that is disposed opposite the first guide and guides the sheet; a second conveying guide pair including a third guide disposed downstream of the first guide in the first direction with a predetermined gap between the first guide and the third guide, the third guide guiding the sheet that has passed through the first conveying guide pair, and a fourth guide disposed opposite the third guide and guiding the sheet; a protruding member configured to be movable in a protruding direction from the second guide side toward the first guide side, and to protrude a sheet straddling the first conveying guide pair and the second conveying guide pair in the protruding direction; a pair of folding rollers that perform the folding process on the sheet protruded by the protruding member; a return means for returning the fold of the folded sheet that has been subjected to the first folding process by the folding roller pair to a position between the first conveying guide pair and the second conveying guide pair; a second conveying unit that conveys the folded sheet returned by the returning means to the first conveying guide pair with the fold at the leading edge; a guide means provided between the first guide and the third guide in the first direction and between the second guide and a folding roller of the pair of folding rollers arranged upstream in the first direction in the protruding direction, the guide means guiding the folded sheet conveyed by the second conveying unit to the pair of first conveying guides; a moving mechanism that moves the guide means to a receiving position that receives the crease of the folded sheet and an opening prevention position that prevents the folded sheet from opening beyond a certain level; a control unit that controls the first conveying unit, the pushing member, the pair of folding rollers, the returning means, the second conveying unit, and the movement mechanism, and a control unit configured to, when the second conveying unit conveys the folded sheet with the fold at the leading edge toward the first conveying guide pair after the first folding process has been performed on the sheet with the folding roller pair, move the guide unit to the opening prevention position after the guide unit receives the fold at the receiving position, and push out the folded sheet with the push-out member after the fold has been guided to the first conveying guide pair, and perform the second folding process with the folding roller pair.

2. The sheet processing device described in Claim 1, characterized in that the control unit transports the sheet from the first transport guide pair to the second transport guide pair using the first transport unit while positioning the guide means closer to the opening prevention position than the receiving position.

3. The sheet processing device described in Claim 1, characterized in that the control unit performs the folding process on the sheet while the guide means is positioned at the receiving position.

4. An image forming system that performs a first folding process on a sheet on which an image has been formed, and then performs a second folding process at a position different from the crease formed by the first folding process, thereby performing an inner triple fold so that one end of the sheet folded by the first folding process is on the inside of the folded sheet, an image forming unit that forms an image on a sheet; a first conveying unit that conveys a sheet on which an image has been formed by the image forming unit in a first direction; a first conveying guide pair including a first guide that guides the sheet conveyed by the first conveying unit and a second guide that is disposed opposite the first guide and guides the sheet; a second conveying guide pair including a third guide disposed downstream of the first guide in the first direction with a predetermined gap between the first guide and the third guide, the third guide guiding the sheet that has passed through the first conveying guide pair, and a fourth guide disposed opposite the third guide and guiding the sheet; a protruding member configured to be movable in a protruding direction from the second guide side toward the first guide side, and to protrude a sheet straddling the first conveying guide pair and the second conveying guide pair in the protruding direction; a pair of folding rollers that perform the folding process on the sheet protruded by the protruding member; a return means for returning the fold of the folded sheet that has been subjected to the first folding process by the folding roller pair to a position between the first conveying guide pair and the second conveying guide pair; a second conveying unit that conveys the folded sheet returned by the returning means to the first conveying guide pair with the fold at the leading edge; a guide means provided between the first guide and the third guide in the first direction and between the second guide and a folding roller of the pair of folding rollers arranged upstream in the first direction in the protruding direction, the guide means guiding the folded sheet conveyed by the second conveying unit to the pair of first conveying guides; a moving mechanism that moves the guide means to a receiving position that receives the crease of the folded sheet and an opening prevention position that prevents the folded sheet from opening beyond a certain level; a control unit that controls the first conveying unit, the pushing member, the pair of folding rollers, the returning means, the second conveying unit, and the movement mechanism, and a control unit configured to move the guide means to the opening prevention position after the guide means receives the fold at the receiving position when the folded sheet is transported toward the first transport guide pair with the fold at the leading edge in the second transport unit after the first folding process has been performed on the sheet with the folding roller pair, and to move the guide means to the opening prevention position after the fold has been guided to the first transport guide pair, and to push out the folded sheet with the push-out member after the fold has been guided to the first transport guide pair, and to perform the second folding process with the folding roller pair.

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