Sheet processing device and image forming system

Abstract

To correctly guide a sheet to a nip part upon executing fold processing.SOLUTION: A sheet processing apparatus for executing fold processing to a sheet comprises: a rotating body pair 22 for holding a sheet with nip parts and executing rotation, thus pulling-in the sheet and executing fold processing; a pushing member 23 for pushing out the sheet into the nip parts of the rotating body pair; and a pushing guide member 40 having a guide part for pushing out the sheet into the nip parts when the pushing member pushes out the sheet into the nip parts. The pushing member and the pushing guide member are relatively moved so that a distance from a pushing tip part to the guide part when the pushing member pushes out the sheet into nip parts is made longer than a distance from the tip part to the guide part when the sheet begins to be pushed out.SELECTED DRAWING: Figure 18

Description

Technical Field

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[0003]

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

Background Art

[0002] Conventionally, as post-processing of sheets discharged from image forming apparatuses such as copiers, printers, facsimiles, and multifunction devices thereof, a sheet processing apparatus that folds a sheet bundle into a booklet shape has been provided. For example, there is known a sheet processing apparatus that bends a sheet at a predetermined position of a sheet carried out from an image forming apparatus with a push plate, pushes it into a nip portion of a pair of folding rollers, and folds it in half while conveying it with the pair of folding rollers.

[0003] Among sheet processing apparatuses that perform folding on sheets, there are sheet processing apparatuses that perform not only double folding but also inner triple folding in which folding is performed at two different positions on the sheet so that one end of the sheet is folded inside the folded sheet.

[0004] When performing the above inner triple folding, when the sheet is pushed out to the nip portion of the pair of folding rollers with a push plate in order to perform the second folding, the end portion on the side to be folded into the sheet folded in half in the first folding may be turned up.

[0005] To prevent this, a curl prevention member having a shape along the outer diameter of the folding roller is integrally provided on the push plate, and when the sheet is pushed with the push plate to perform the second folding, the curl prevention member guides the end portion of the sheet to be folded into the nip portion, so that a configuration has been proposed in which the end portion is not curled (Patent Document 1).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] In the above-mentioned Patent Document 1, the anti-curling member is used for the second folding process. However, the anti-curling member can also be used to guide the sheet toward the folding roller pair when performing the first folding process (including the normal double-fold process), not just the second folding process. However, in the configuration of Patent Document 1, when the veneer protrudes near the nip portion of the folding roller pair, it is necessary to ensure a distance between the anti-curling member and the tip of the veneer so that the anti-curling member does not come into contact with the outer circumference of the folding roller. This distance needs to be longer as the diameter of the folding roller increases.

[0008] Furthermore, if the distance between the tip of the veneer and the anti-peeling member increases, the timing at which the anti-peeling member guides the sheet when the veneer begins to protrude will be delayed. As a result, there will be a loss of sheet transport before the anti-peeling member makes contact with the sheet, which may cause the sheet to crease or bend.

[0009] The present invention has been made in view of the above problems, and its purpose is to provide a sheet processing device that enables accurate guidance of a sheet to the nip portion when folding, and an image forming system equipped therewith. [Means for solving the problem]

[0010] A typical configuration according to the present invention for achieving the above objective is a sheet processing apparatus that performs an inner triple fold on a sheet by performing a first fold process, then performing a second fold process at a position different from the crease formed by the first fold process, so that one end of the sheet folded by the first fold process is on the inside of the folded sheet, comprising: a pair of folding rollers that perform the folding process on the sheet at the nip portion; a pressing member that pushes the sheet toward the nip portion to perform the folding process on the sheet; an opening prevention member that prevents the sheet folded in half by the first fold process from opening beyond a certain point so that one end of the sheet folded by the first fold process enters the nip portion when the second fold process is performed; and a moving mechanism that moves the pressing member and the opening prevention member toward the pair of folding rollers, then stops the opening prevention member so that it does not come into contact with the outer circumference of the pair of folding rollers, and moves the pressing member further toward the nip portion beyond the position where the opening prevention member stops. The opening prevention member is configured to be displaceable relative to the pressing member in the return direction when, during the execution of the second folding process, the opening prevention member receives a load of a certain amount or more from the sheet in the return direction, which is opposite to the direction of movement toward the folding roller pair. It is characterized by the following: [Effects of the Invention]

[0012] In this invention, the sheet can be pressed further by the pressing member even after it has been guided by the pressing member to the vicinity of the folding roller pair. Therefore, the pressing of the sheet into the nip portion and the guiding of the sheet can be performed accurately. [Brief explanation of the drawing]

[0013] [Figure 1] An explanatory diagram of the overall configuration of the image forming system of this embodiment. [Figure 2] An explanatory diagram of the overall configuration of the sheet processing device in an image forming system. [Figure 3] A cross-sectional view showing the folding apparatus of a sheet processing device. [Figure 4] A plan view showing a sheet folding processing device. [Figure 5] (a) and (b) are cross-sectional diagrams illustrating the three-fold operation of the sheet. [Figure 6](a)(b) are cross-sectional explanatory views of the inner three-fold operation of the sheet. [Figure 7] (a)(b) are cross-sectional explanatory views of the inner three-fold operation of the sheet. [Figure 8] (a)(b) are cross-sectional explanatory views of the inner three-fold operation of the sheet. [Figure 9] (a)(b) are cross-sectional explanatory views of the inner three-fold operation of the sheet. [Figure 10] (a)(b) are cross-sectional explanatory views of the inner three-fold operation of the sheet. [Figure 11] (a)(b) are cross-sectional explanatory views of the inner three-fold operation of the sheet. [Figure 12] Partial perspective view of the sheet folding processing device. [Figure 13] Explanatory diagram of the arrangement of the folding roller pair, folding blade, and pressing guide member. [Figure 14] (a)(b)(c) Operating explanatory diagram of the pressing guide member [Figure 15] (a)(b) are cross-sectional explanatory views of the operation of the folding blade and blade guide member. [Figure 16] (a)(b) are cross-sectional explanatory views of the operation of the folding blade and blade guide member. <000​​​​​​​​​​​​​​​​​​​​​​​ [Figure 25] A cross-sectional diagram illustrating the operation of the folding blade and blade guide member. [Figure 26] A cross-sectional diagram illustrating the operation of the folding blade and blade guide member. [Figure 27] A cross-sectional diagram illustrating the operation of the folding blade and blade guide member. [Figure 28] A cross-sectional diagram illustrating the operation of the folding blade and blade guide member. [Figure 29] A cross-sectional diagram illustrating the operation of the folding blade and blade guide member. [Figure 30] (a) and (b) are cross-sectional diagrams of the deflection guide member. [Figure 31] (a) and (b) are cross-sectional diagrams of the deflection guide member. [Figure 32] (a) and (b) are cross-sectional diagrams of the deflection guide member. [Figure 33] A plan view showing a sheet folding processing device. [Modes for carrying out the invention]

[0014] Next, a preferred embodiment of the present invention, a sheet processing apparatus and an image forming system equipped therewith, will be described with reference to the drawings. Figure 1 schematically shows 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 the figure, the image forming system 100 consists of an image forming apparatus A and a sheet processing apparatus B attached thereto.

[0015] <Overall configuration of the image forming apparatus> Image forming apparatus A consists of an image forming unit A1, a scanner unit A2, and a feeder unit A3. The image forming unit A1 includes a feeding unit 2, an image forming unit 3, an output unit 4, and a data processing unit 5 inside the apparatus housing 1.

[0016] The feeding unit 2 consists of multiple cassette mechanisms 2a, 2b, and 2c, each storing image forming sheets of different sizes, and feeds sheets of a specified size onto the feeding path 2f from the main control unit (not shown). Each cassette mechanism 2a, 2b, and 2c is detachably installed from the feeding unit 2 and contains a separation mechanism for separating the sheets one by one and a feeding mechanism for feeding the sheets. The feeding path 2f is provided with transport rollers for feeding the sheets supplied from each cassette mechanism 2a, 2b, and 2c downstream, and pairs of registration rollers at the ends of the path for aligning the leading edges of each sheet.

[0017] The feed path 2f is connected to a high-capacity cassette 2d and a manual feed tray 2e. The high-capacity cassette 2d consists of an optional unit that stores sheets of sizes consumed in large quantities. The manual feed tray 2e is configured to supply special sheets such as cardboard sheets, coated sheets, and film sheets that are difficult to feed separately.

[0018] In this embodiment, the image forming unit 3 is configured using an electrophotographic method and comprises a rotating photosensitive drum 3a and, arranged around it, a light emitter 3b that emits an optical beam, a developer 3c, and a cleaner (not shown). The illustrated diagram is a monochrome printing mechanism in which the photosensitive drum 3a, whose circumferential surface is uniformly charged, is irradiated with light corresponding to the image signal by the light emitter 3b to optically form a latent image, and toner is deposited onto this latent image by the developer 3c to form a toner image.

[0019] In conjunction with the timing of image formation on the photosensitive drum 3a, the sheet is sent from the supply path 2f to the image forming unit 3, and the toner image formed on the photosensitive drum 3a is transferred to the sheet by applying a transfer bias from the transfer charger 3d. The sheet with the transferred toner image is heated and pressurized as it passes through the fuser 6 to fix the toner image, and is discharged from the discharge port 4b by the discharge roller 4a and transported to the sheet processing device B described later.

[0020] The scanner unit A2 comprises a platen 7a on which an image document is placed, a carriage 7b that reciprocates along the platen 7a, a photoelectric conversion means 7c, and a reduction optical system 7d that guides the reflected light from the document on the platen 7a by the carriage 7b to the photoelectric conversion means 7c. The photoelectric conversion means 7c photoelectrically converts the optical output from the reduction optical system 7d into image data and outputs it as an electrical signal to the image forming unit 3.

[0021] Furthermore, scanner unit A2 is equipped with a traveling platen 7e to read the sheets sent from feeder unit A3. Feeder unit A3 consists of a feed tray 8a for loading the original sheets, a feed path 8b that guides the original sheets sent from the feed tray 8a to the traveling platen 7e, and an output tray 8c for storing the original sheets that have passed through the traveling platen 7e. The original sheets from the feed tray 8a are read by the carriage 7b and the reduction optical system 7d as they pass through the traveling platen 7e.

[0022] <Overall configuration of the sheet processing device> Next, we will explain the overall configuration of the sheet processing device B, which performs post-processing on the sheets sent from the image forming apparatus A.

[0023] Figure 2 is an explanatory diagram of the configuration of the sheet processing apparatus B according to this embodiment. The sheet processing apparatus B includes an apparatus housing 11 provided with an inlet 10 for introducing sheets from the image forming apparatus A. The apparatus housing 11 is positioned in alignment with the housing 1 of the image forming apparatus A so that the inlet 10 communicates with the outlet 4b of the image forming apparatus A.

[0024] The sheet processing device B includes a sheet loading path 12 for transporting sheets introduced from the loading entrance 10, a first discharge path 13a, a second discharge path 13b, and a third discharge path 13c branching off from the sheet loading 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 composed of flapper guides that change the transport direction of the sheets being transported in the sheet loading path 12.

[0025] The first path switching means 14a switches, by a driving means (not shown), between a mode that guides the sheet from the loading entrance 10 in the direction of the first discharge path 13a, which transports it horizontally, and the second discharge path 13b, which transports it downwards, and a mode that guides it to the third discharge path 13c, which transports it upwards. The first discharge path 13a and the second discharge path 13b are connected in such a way that a sheet that has been introduced into the first discharge path 13a can be switched back and transported to the second discharge path 13b by reversing the transport direction.

[0026] The second route switching means 14b is positioned downstream of the first route switching means 14a with respect to the direction of transport of the sheets being transported along the sheet loading route 12. The second route switching means 14b, by a drive means (not shown), switches between a mode in which sheets that have passed through the first route switching means 14a are introduced into the first discharge path 13a, and a mode in which sheets that have been introduced into the first discharge path 13a are switched back and transported to the second discharge path 13b.

[0027] The sheet processing device B comprises a first processing unit B1, a second processing unit B2, and a third processing unit B3, each performing different post-processing operations. Furthermore, a punch unit 15 is positioned in the sheet loading path 12 to punch holes in the loaded sheets.

[0028] The first processing unit B1 is a binding processing unit that collects, aligns, and binds multiple sheets discharged from the discharge port 16a at the downstream end of the first discharge path 13a with respect to the conveying direction of the sheets being transported along the sheet loading path 12, and discharges them onto a loading tray 16b provided on the outside of the device housing 11. The first processing unit B1 also includes a sheet transport device 16c for transporting sheets or sheet bundles, and a binding processing unit 16d for binding sheet bundles. At the downstream end of the first discharge path 13a, there is a pair of discharge rollers 16e for discharging sheets from the discharge port 16a and for switchback transport from the first discharge path 13a to the second discharge path 13b.

[0029] The second processing unit B2 is a folding processing unit that bundles multiple sheets that are transported back from the second discharge path 13b, binds the sheet bundles, and then folds them. As will be described later, the second processing unit B2 includes a folding processing device F that folds the incoming sheets or sheet bundles, and a binding processing unit 17a that is positioned immediately upstream of the folding processing device F along the sheet transport direction of the sheets being transported to the second discharge path 13b and binds the sheet bundles. The folded sheet bundles are discharged by the discharge roller 17b onto a loading tray 17c provided on the outside of the device housing 11.

[0030] The third processing unit B3 performs jog sorting, which divides the sheets sent from the third discharge path 13c into two groups: one group that is stacked with a predetermined offset in the sheet width direction perpendicular to the transport direction, and another group that is stacked without offsetting. The jog-sorted sheets are discharged onto a loading tray 18 located outside the device housing 11, where the offset sheet bundles and the non-offset sheet bundles are stacked.

[0031] Figure 3 schematically shows the overall configuration of the second processing unit B2. As described above, the second processing unit B2 includes a folding processing device F that folds the sheet bundles, which are fed in from the second discharge path 13b and assembled into two halves, and a binding processing unit 17a that binds the sheet bundles before folding. The binding processing unit 17a shown is a stapler that binds the sheet bundles by driving staples into them.

[0032] A sheet transport path 20 is connected to a second discharge path 13b for transporting 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 loading tray 21, a sheet loading tray 21, which constitutes part of the sheet transport path, is provided downstream of the sheet transport path 20 for positioning and loading sheets to be folded. Immediately upstream of the sheet loading tray 21, a binding processing unit 17a and its staple receiving section 17d are provided in opposing positions, with the sheet transport path 20 in between.

[0033] On one side of the sheet loading tray 21, a pair of folding rollers 22, which serve as a folding rotating body pair, is arranged facing one side of the sheet or sheet bundle loaded on the sheet loading tray. The folding roller pair 22 consists of a pair of folding rollers 22a and 22b whose roller surfaces are pressed against each other, and the nip portion 22c, which is the pressed contact portion, is positioned toward the sheet loading tray 21. The folding rollers 22a and 22b are arranged side by side on the upstream and downstream sides, respectively, along the direction in which the sheets are transported into the sheet loading tray 21 from the upstream side to the downstream side, with approximately equal spacing from the sheet loading tray 21. In this invention, the rotating part of the folding rotating body pair is not limited to the folding rollers 22a and 22b of this embodiment, but can be composed of a rotating belt or the like. Furthermore, the folding roller pair 22 can be constructed by arranging a plurality of folding rollers (rotating bodies) in series along the axial direction of each folding roller 22a and 22b.

[0034] As shown in Figure 3, each folding roller 22a, 22b of the folding roller pair 22 of this embodiment has a roller surface which consists of a first roller surface 22a2, 22b2 with a constant radius R1 around the rotation axis 22a1, 22b1, and a second roller surface 22a3, 22b3 whose distance from the rotation axis of the rotation axis is smaller than the radius R1 of the first roller surface. The first roller surfaces 22a2, 22b2 are formed of a rubber material or the like with a relatively high coefficient of friction, similar to ordinary roller surfaces. In contrast, the second roller surfaces 22a3, 22b3 are formed of a plastic resin material or the like with a lower coefficient of friction than the first roller surfaces 22a2, 22b2.

[0035] The rotation axes 22a1 and 22b1 of the folding rollers 22a and 22b are rotated by a common drive motor or other driving means. This allows the rotational positions of the first roller surfaces 22a2 and 22b2 and the second roller surfaces 22a3 and 22b3 to be constantly synchronized.

[0036] On the opposite side of the folding roller pair 22, with the sheet loading tray 21 in between, a folding blade 23 is positioned as a protruding member. The folding blade 23 is supported on a blade carrier 24 with its tip facing the nip portion 22c of the folding roller pair 22. The blade carrier 24 is provided to be movable by a moving mechanism consisting of a cam member or the like in a direction that crosses the sheet loading tray 21 at approximately a right angle, that is, in a direction that intersects with the transport direction of the sheets being transported from the second discharge path 13b to the sheet loading tray 21.

[0037] In Figure 3, in the front-to-back direction, i.e., along the axis of the folding roller, a pair of cam members 25 (only one is shown in the figure), each consisting of a mirror-symmetrical eccentric cam, are positioned opposite each other on either side of the blade carrier 24. The cam members 25 rotate around a rotation axis 25a located at their eccentric position by a driving means such as a drive motor. A cam groove 25b is formed along the outer circumference of the cam member 25.

[0038] The blade carrier 24 is provided with a cam pin 24c that slidably fits into the cam groove 25b, acting as a cam follower.

[0039] The blade carrier 24 reciprocates in a direction approaching or moving away from the sheet loading tray 21 when the cam member 25 is rotated by the drive motor. As a result, as shown in Figure 3, the folding blade 23 can be moved linearly back and forth along the protruding path connecting the initial position, where the tip of the folding blade 23 is not yet in the sheet transport path formed by the sheet loading tray 21, and the maximum protruding position, where it is sandwiched between the nip portion 22c of the folding roller pair 22.

[0040] A restricting stopper 26 is positioned at the lower end of the sheet loading tray 21 to restrict the leading edge of the loaded sheet in the direction of transport. The restricting stopper 26 is provided to be able to move up and down along the sheet loading tray 21 by a sheet lifting mechanism 27.

[0041] The sheet lifting mechanism 27 of this embodiment is a conveyor belt mechanism consisting of a pair of pulleys 27a and 27b positioned along the sheet loading tray 21, near the upper and lower ends, and a transmission belt 27c wrapped around both pulleys, which are located below the blade carrier 24 in its initial position where the tip of the folding blade 23 is not in the sheet transport path formed by the sheet loading tray 21 on the back side of the sheet loading tray 21. The regulating stopper 26 is fixed on the transmission belt 27c. By rotating the drive-side pulley 27a or 27b with a driving means such as a drive motor, the regulating stopper 26 moves up and down between the lower end position shown in Figure 3 and a desired height position, thereby moving a sheet or sheet bundle along the sheet loading tray 21.

[0042] Furthermore, the folding processing device F of this embodiment is further equipped with a sheet side alignment mechanism for aligning and aligning the side edges of sheets being transported into the sheet loading tray 21. As shown in Figure 4, this sheet side alignment mechanism has a pair of sheet side alignment members 28a and 28b symmetrically arranged on both sides of the sheet loading tray 21 in the sheet width direction (a direction perpendicular to the sheet transport direction). Figure 4 is a schematic plan view of the folding processing device F as seen from above. The sheet side alignment members 28a and 28b are held so as to be movable so as to be able to move relatively closer to and further apart in the sheet width direction. When a sheet is transported into the sheet loading tray 21 and its leading edge abuts against the regulating stopper 26, the sheet side alignment members 28a and 28b are moved to align the sheet's position in the width direction.

[0043] <Inner tri-fold processing> The sheet processing device B of this embodiment is capable of performing an inward tri-fold on sheets that have been transported to the sheet loading tray 21, which serves as a sheet transport path, by the folding processing device F. Inward tri-fold processing is a process in which a sheet is folded in half by the first folding process, and then, when the sheet is folded a second time at a location different from the first folding position, one end of the sheet folded by the first folding process is folded inward by the sheet folded by the second folding process, thereby performing a tri-fold. Here, the general operation of the folding processing device F of this embodiment when performing an inward tri-fold processing will be explained with reference to Figures 5 to 11. Figures 5 to 11 are schematic cross-sectional diagrams showing the movement of each part along the flow of the sheet S when the inward tri-fold processing is performed.

[0044] In this embodiment, the sheet loading tray 21 is formed at an angle to the vertical, and the sheet S is transported so that the leading edge S1 of the sheet S1 is downward and the trailing edge S2 is upward, with one side of the sheet S1 guided by the guide surface 21a that forms the sheet loading tray 21, until the leading edge of the sheet S1 strikes the regulating stopper 26 and stops (Figure 5(a)). At this time, the position of the regulating stopper 26 is such that the first folding position of the sheet S that the leading edge S1 strikes is opposite the folding blade 23. The folding blade 23 is positioned to push the sheet S out from the side of the guide surface 21a of the sheet loading tray 21 toward the folding roller pair 22. In other words, the guide surface 21a of the sheet loading tray 21 and the folding roller pair 22 are positioned in corresponding positions with the sheet S in between.

[0045] In this state, after the sheet width direction is aligned by the aforementioned sheet side alignment members 28a and 28b, the folding blade 23 is operated to fold the sheet S in half and push the folded portion out towards the nip portion 22c of the folding roller pair 22 (Figure 5(b)). Synchronized 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 pull 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 (Figure 6(a)).

[0046] Next, in order to perform the second folding process, when the rear end S2 of the sheet that has been folded the first time reaches a predetermined position, sheet transport is stopped (Figure 6(b)), and the folding roller pair 22 and the discharge roller 17b are driven in reverse to perform the switchback transport process. The rear end S2 of the sheet becomes the end that is folded inward into the sheet folded by the second folding process when the sheet is folded in three inward (hereinafter referred to as the "folded end"). Then, when performing the switchback transport process, the folded end S2 is pushed downward (towards the sheet loading tray 21 where the front end S1 of the sheet is located) by the L-shaped pressing guide member 30 (Figure 7(a)), and the pressing guide member 30 again guides the sheet S being transported in the direction where the restricting stopper 26 of the sheet loading tray 21 is located (Figure 7(b)). The configuration and operation of this pressing guide member 30 will be described in detail later.

[0047] When the leading edge of the sheet S reaches the regulating stopper 26, which has been moved to the sheet receiving position in advance by the switchback transport (Figure 8(a)), the pressing guide member 30 is returned to the retracted position and then moved to the reverse transport guide position (Figure 8(b)), and the regulating stopper 26 is moved to a position where the second folding position is opposite to the folding blade 23 (Figure 9(a)). After the movement is complete, the pressing guide member 30 is moved to a guide position parallel to the guide surface 21a of the sheet loading tray 21 (Figure 9(b)).

[0048] Next, the folding blade 23 is operated again to push the sheet S toward the nip portion 22c of the folding roller pair 22 (Figure 10(a)). At this time, the blade guide member 40, which is an ejection guide member located on the upper part of the folding blade 23, protrudes, guiding the folded end S2 of the sheet so that it is pushed toward the nip portion 22c (Figure 10(b)). The configuration and operation of this blade guide member 40 will be described in detail later.

[0049] The sheet S, which has been sent to the folding roller pair 22 by the protrusion of the folding blade 23, undergoes a second folding process as it passes through the nip section 22c (Figure 11(a)), and the inwardly tri-folded sheet S is discharged by the discharge roller 17b (Figure 11(b)).

[0050] <Pressure guide member> Next, the pressing guide member 30, which is the pressing member mentioned above, will be described with reference to Figures 12 to 14. Figure 12 is a perspective view of the folding processing device F with the pressing guide member 30 exposed, and Figure 13 is a diagram showing the rotational trajectory of the pressing guide member 30 and its relationship to other members. Figure 14 is an explanatory diagram of the operation of the pressing guide member 30.

[0051] (Shape of the pressing guide member) The pressing guide member 30 presses the folded end S2 of the sheet downward when the sheet that has undergone the first folding process is being transported in a switchback manner, and also guides it to be transported to the sheet loading 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 towards the front end S1 of the sheet on the sheet loading tray 21 when the sheet that has undergone the first folding process is being transported in a switchback manner.

[0052] As shown in Figure 12 (and Figure 4), the pressing guide members 30 are positioned on the opposite side of the sheet loading tray 21 from the side where the folding roller pair 22 is located, sandwiching the sheet S guided by the guide surface 21a of the sheet loading tray 21. In this embodiment, three of them are mounted in a row at approximately equal intervals on a pivot shaft 31, which is a support member arranged in the sheet width direction. The two on the sides are positioned so as to contact both ends of the sheet S being transported by the sheet loading tray 21, and the one in the center is positioned so as to contact the sheet being transported approximately in the center in the width direction.

[0053] The above-mentioned pressing guide member 30 is movable by a means of movement. In this embodiment, the pivot shaft 31 is connected to the pressing guide motor 33 via a drive transmission member 32 such as a drive belt, and the pivot shaft 31 rotates when the pressing guide motor 33 is driven, and the three pressing guide members 30 are configured to rotate integrally with it.

[0054] As shown in Figure 13, the pressing guide member 30 has a rotating part 30a that can rotate around the pivot axis 31 and a guide part 30b that serves as a first guide surface for guiding the sheet S being transported in a switchback manner. The guide part 30b is connected to the rotating part 30a at approximately a right angle, and the member is composed of an L-shaped cross-section. The area between the rotating part 30a and the guide part 30b, that is, the L-shaped corner at the tip of the rotating part 30a, is formed as a pressing part 30c that presses against the sheet S.

[0055] The pressing guide member 30 is provided so as to be exposed through a notch formed in the guide surface 21a. When a sheet S is loaded into the sheet loading tray 21, the pressing guide member 30 is retracted to a retracted position (see Figure 5(a)). When in this retracted position, the rotating part 30a is provided so as to be substantially flush with the guide surface 21a. Therefore, the rotating part 30a functions as part of the guide surface 21a and acts as a guide surface (second guide surface) that guides the sheet loaded into the sheet loading tray 21. Furthermore, when the pressing guide member 30 is in the retracted position, it is sufficient to prevent the guide part 30b from protruding from the guide surface 21a, thus reducing the storage space required for the pressing guide member 30 in the retracted state.

[0056] (Position of the center of rotation) As shown in Figure 13, the pivot axis 31, which is the pivot center of the pressing guide member 30 in this embodiment, is positioned upstream of the nip line L1 connecting the nip portion 22c of the folding roller pair 22 and the tip of the folding blade 23 in the conveying direction in which the sheet S is transported into the sheet loading tray 21, and is positioned on the opposite side of the guide surface 21a of the sheet loading tray 21 from the side where the folding roller pair 22 is positioned. Furthermore, the pivot axis 31 in this embodiment passes through the rotation axis 22a1 of the folding roller 22a, which is positioned upstream of the nip line L1 in the sheet transporting direction among the folding rollers 22a and 22b, i.e., the folding roller 22a that is closer to the pivot axis 31, and is positioned downstream of the axis L2 parallel to the nip line L1 in the conveying direction.

[0057] Furthermore, the rotating part 30a is set to rotate in a direction that presses the pressing part 30c toward the side to which the sheet S is being conveyed in a switchback manner.

[0058] Therefore, when the sheet S that has undergone the first folding process is transported in a switchback manner, as shown in Figure 14(a), when the pressing guide member 30 in the retracted position rotates, the pressing part 30c pushes down the folded end S2 of the sheet from above to below, as shown in Figure 14(b). As a result, the folded end S2 is guided downstream (downward) in the sheet transport direction from where the sheet S was received into the sheet loading tray 21 before the first folding process of the sheet loading tray 21 while being transported in a switchback manner. In other words, the pressing part 30c changes the orientation of the folded end S2 of the sheet towards the direction of the leading edge S1 of the sheet on the sheet loading 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 downstream in the sheet transport direction from where the sheet S was received into the sheet loading tray 21 before the first folding process.

[0059] Furthermore, as shown in Figure 14(c), when the pressing portion 30c rotates to the guide position where it is positioned at the guide surface 21a, the pressing portion 30c contacts the sheet and then pushes down the folded end S2 of the sheet, pulling it from the nip portion 22c side towards the guide surface 21a side, while also guiding it in the direction where the restricting stopper 26 of the sheet loading tray 21 is located. Therefore, even if the folded end S2 of the sheet is curled upward, the sheet will not move upward on the sheet loading tray 21, but will be reliably transported downward.

[0060] (Rotation range of the rotating part) In this embodiment, the length of the rotating portion 30a of the pressing guide member 30, that is, the length from the pivot axis 31, which is the pivot point, to the pressing portion 30c, is set to be longer than the shortest distance to the first roller surface 22a2 of the folding roller 22a that is closer to the pivot axis 31, and shorter than the shortest distance to the second roller surface 22a3, as shown in Figure 13.

[0061] As described above, even if the length of the rotating part 30a is set to be longer than the shortest distance to the first roller surface 22a2, the folding roller pair 22 stops when the sheet is switched back so that the second roller surfaces 22a3 and 22b3 face the rotating part 30a, so that the rotating part 30a does not interfere with the folding roller pair 22 even when it is rotated. Furthermore, since the rotating part 30a can be set to be longer than the shortest distance to the first roller surface 22a2, which is the large diameter part of the folding roller 22a, the pressing part 30c presses the sheet being conveyed in a switchback position closer to the nip part 22c, thus guiding it to the sheet loading tray 21 more reliably.

[0062] Furthermore, if the rotating portion 30a is lengthened, the rotating shaft 31 must be positioned away from the folding blade 23 in the sheet conveying direction in order to prevent the rotating pressing guide member 30 from interfering with the folding blade 23. Consequently, the rotating shaft 31 must also be positioned away from the folding roller pair 22. In this embodiment, as described above, the rotating shaft 31 is configured to be positioned between the nip line L1 and the rotation axis L2 in the sheet conveying direction. Therefore, the position where the pressing portion 30c presses the sheet being conveyed in a switchback manner can be brought closer to the nip section 22c without unnecessarily lengthening the rotating portion 30a.

[0063] Here, in addition to using rollers of different diameters having first roller surfaces 22a2, 22b2 and second roller surfaces 22a3, 22b3 with different diameters as in this embodiment, it is also possible to use a roller pair with a constant diameter. In that case, however, the length of the rotating portion 30a must be shorter than the shortest distance to the outer circumference of the folding roller on the side closer to the pivot axis.

[0064] Furthermore, as shown in Figure 13, the pressing guide member 30 of this embodiment has a shape in which the guide portion 30b is located inside the rotation trajectory L3 of the rotating portion 30a and does not protrude outside that area. As a result, even when the long rotating portion 30a is rotated as described above, the guide portion 30b does not interfere with the folding roller pair 22.

[0065] As described above, when the sheet that has undergone the first folding process is transported in a switchback manner, it is guided by the pressing guide member 30 and returned to the sheet loading tray 21. After the sheet comes into contact with the restricting stopper 26 and the switchback transport is completed, the pressing guide member 30 is returned to its retracted position. At this time, the rotating portion 30a, which is the second guide surface of the pressing guide member 30, is moved to a reverse transport guide position that protrudes slightly towards the sheet transport path side from the guide surface 21a so that it guides the sheet S being transported in the reverse direction on the sheet loading tray 21 (see Figure 8(b)).

[0066] After the pressing guide member 30 moves to the reverse transport guide position, the restricting stopper 26 is raised to reverse transport the sheet so that the second folding position is opposite the folding blade 23. At this time, the sheet S is guided by the rotating part 30a of the pressing guide member 30, and is transported without getting caught on the notches for attaching the pressing guide member formed on the guide surface 21a (see Figure 9(a)).

[0067] <Blade guide component> After the sheet, which has been transported via switchback as described above, moves to a position opposite the folding blade 23 for the second folding, 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 on the upper part of the folding blade 23 is configured to guide the folded end S2 of the sheet (see Figure 10(b)).

[0068] 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 show the operation of the folding blade 23 and the blade guide member 40 when the second folding process is performed on the sheet.

[0069] (Blade guide component configuration) The blade guide member 40 moves in the protruding direction of the folding blade 23 when the sheet S is subjected to a second folding process, guiding the sheet edge on the fold side formed by the first folding process, i.e., the folded sheet edge S2, in the protruding direction relative to the folding blade 23, and guiding it to the nip portion 22c of the folding roller pair 22. To this end, as shown in Figure 15, the blade guide member 40 has a contact portion 40a that abuts against the rear end of the sheet, and a fitting hole portion 40b with a partial notch is formed at one end of the contact portion 40a, and this fitting hole portion 40b is rotatably fitted into a shaft portion 40f formed in the base portion 40e. Furthermore, an arm portion 40c is integrally provided at the other end of the contact portion 40a, and an engaging projection portion 40d is formed at the end of this arm portion 40c. The engaging projection portion 40d is slidably engaged into an elongated hole 50 formed in the frame of the sheet processing device B. This elongated hole 50 is formed near the top of the blade carrier 24, substantially parallel to the guide surface 21a of the sheet loading tray 21.

[0070] The base portion 40e is slidably mounted to the blade carrier 24 in a direction parallel to the direction of movement of the blade carrier 24. A tension spring 51 is installed between the locking portion 40e1 formed on the base portion 40e and the locking portion 24a formed on the blade carrier 24.

[0071] The blade carrier 24 is provided with a pressing projection 24b that can contact and press against the base portion 40e. This pressing projection 24b is rotatably mounted on the blade carrier 24 and is biased counterclockwise in Figure 15 by a coil spring 52 attached to the pivot shaft. As a result, when the blade carrier 24 moves in the blade protrusion direction, the pressing projection 24b contacts the base portion 40e and presses against it, causing the blade guide member 40 to move integrally with the blade carrier 24. The coil spring 52 provided on the pressing projection 24b acts as a so-called torque limiter, and rotates clockwise when a force greater than a predetermined amount in the clockwise direction is applied to the pressing projection 24b.

[0072] (Angle change of the contact point relative to the direction of movement of the folding blade) In the above configuration, as shown in Figure 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 is in a position where the contact portion 40a contacts the pivot axis 31, which is the pivot point of the pressing guide member 30. This state is the home position of the blade guide member 40. At this time, the contact portion 40a is upright so as to be substantially flush with the guide surface 21a. Then, from the home position, as the blade carrier 24 moves in the blade protrusion direction, the blade guide member 40 is pressed by the pressing projection 24b and moves together with the blade carrier 24, moving until the abutment portion 40e2, which is upright and formed at the rear end of the base portion 40e, contacts the pivot axis 31, as shown in Figure 15(b).

[0073] As described above, when the blade guide member 40 moves in the blade protruding direction, the engaging projection 40d is guided by the elongated hole 50 and slides downward, causing the contact portion 40a to rotate around the shaft portion 40f. The shaft portion 40f is provided at one end of the contact portion 40a that is closer to the folding blade 23. This one end refers to the region between the center of the contact portion 40a and the end closer to the folding blade 23. In other words, the shaft portion 40f is provided in one of the regions closer to the folding blade 23 than the center of the contact portion 40a. Therefore, in the state shown in Figure 15(a) where the blade guide member 40 is in the home position, the contact portion 40a is in an upright position, with an angle of approximately right angle to the direction of movement of the blade carrier 24, i.e., the direction of movement of the folding blade 23. As the blade carrier 24 moves in the direction in which the folding blade 23 is ejected, as shown in Figure 15(b), the other end of the contact portion 40a moves so as to approach the movement trajectory of the shaft portion 40f, which is the pivot center, that is, it rotates so as to tilt upstream in the direction in which the folding blade 23 is ejected, and the angle of the contact portion 40a with respect to the direction of movement changes to an acute angle (the angle on the upstream side in the ejection direction becomes smaller) as the blade carrier 24 moves. As described above, one end of the contact 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 contact portion 40a, is configured to slide along the elongated hole 50, so that the blade guide member 40 can change its angle with respect to the direction of movement in conjunction with the movement of the blade guide member 40 without providing any special driving means.

[0074] Furthermore, as shown in Figure 15(a), a projection 40f1 is formed on the shaft portion 40f, which serves as the pivot axis of the contact portion 40a. On the other hand, the notch formed in the fitting hole portion 40b that engages with the shaft portion 40f is wider than the width of the projection 40f1, and the blade guide member 40 is rotatable within the range of the notch.

[0075] 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. At this time, the notched surface of the fitting hole portion 40b comes into contact with the projection 40f1, and the contact portion 40a is restricted from rotating any further. Therefore, with the contact portion 40a in contact with the pivot shaft 31, the blade guide member 40 is restricted from moving any further, and the contact portion 40a maintains an upright position in the home position.

[0076] Furthermore, in this embodiment, the blade guide member 40 is composed of a contact portion 40a and an arm portion 40c that are linear in cross-section, and the arm portion 40c is formed at a predetermined angle with respect 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 the side where the engaging projection 40d is provided is located further away from the guide surface 21a on the side opposite to the folding roller pair 22. That is, it is located further away from the guide surface 21a in the direction that returns the folding blade 23 from the nip portion 22c side to the home position. Therefore, the elongated hole 50 into which the engaging projection 40d engages can be positioned further away from the guide surface 21a on the side opposite to the folding roller pair 22, and can be positioned in a location that does not interfere with the guide surface 21a. Consequently, when the blade guide member 40 is in the home position, the contact portion 40a can be configured to function as a guide portion for the sheets being transported on the sheet loading tray 21.

[0077] (Operation of the folding blade and blade guide member) Next, the operation of the blade guide member 40 when the folding blade 23 is operated to perform a second folding operation on the sheet will be explained with reference to Figures 16 to 19.

[0078] Figure 16(a) shows the blade carrier 24 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 extends the folding blade 23 toward the nip portion 22c of the folding roller pair 22 from the home position is referred to as the "extension direction," and the direction in which it returns from the nip portion 22c side to the home position is referred to as the "return direction."

[0079] When in the home position described above, the tip of the folding blade 23 is approximately flush with the guide surface 21a or on the return side of the guide surface 21a (first position), and is spaced away from the sheet S on the sheet loading tray 21. Therefore, the sheet being transported on the sheet loading tray 21 guided by the guide surface 21a will not get caught on the tip of the blade. Even if the tip of the folding blade 23 protrudes further towards the folding roller 22 than the guide surface 21a, if the sheet being transported to the sheet loading tray 21 by another guide member does not get caught on the tip of the blade, the tip of the blade can be said to have retracted from the sheet transport path, and this state may be considered the first position. Furthermore, when the blade guide member 40 is in the home position, the contact portion 40a of the blade guide member 40 is in contact with the pivot shaft 31. At this time, the pressing projection 24b is spaced away from the base portion 40e.

[0080] Next, to extend 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 ejection direction. As a result, the pressing projection 24b comes into contact with the base portion 40e, and the blade guide member 40 moves integrally with the blade carrier 24 and the folding blade 23 in the ejection direction (Figure 16(b)). At this time, the tip of the folding blade 23 is configured to protrude further in the ejection direction than the tip of the blade guide member 40.

[0081] As the blade carrier 24 moves further in the protruding direction, the tip of the folding blade protrudes by a predetermined amount, and as shown in Figure 17(a), the first folding process is performed, and the tip of the folding blade 23 comes into contact with the sheet S which is stopped on the sheet loading tray 21 at the second folding position (second position). At this time, as mentioned above, because the tip of the folding blade 23 protrudes further in the protruding direction than the blade guide member 40, the folding blade 23 comes into contact with the folding position of the sheet S before the blade guide member 40. As a result, the protrusion of the folding blade 23 causes the tip of the folding blade facing the folding position of the sheet to come into contact with the sheet accurately without deviating from the folding position, and the folding process is performed at the correct folding position.

[0082] Furthermore, even if the tip of the folding blade does not necessarily protrude from the blade guide member 40, as long as it is in the same position as the blade guide member 40 in the protruding direction, it is possible to suppress misalignment when the blade tip contacts the folding position of the sheet.

[0083] In the above state, when the blade carrier 24 moves in the protruding direction, the folding blade 23 causes the second folding position of the sheet S to protrude toward the nip portion 22c of the folding roller pair 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, guiding this folded end S2 to be pushed toward the nip portion 22c (Figure 17(b)).

[0084] As described above, the blade guide member 40 guides the folded end S2 of the sheet to the nip portion 22c, so that the folded end S2 of the sheet moves toward the nip portion 22c without being curled up. Also, as it approaches the nip portion 22c, the protruding blade guide member 40 may interfere with the outer circumference of the folding rollers 22a and 22b. At this time, as described above, as the blade guide member 40 of this embodiment moves in the protruding direction, the angle of the contact portion 40a with respect to the protruding direction changes to an acute angle (from the state in Figure 17(a) to the state in Figure 17(b)). Therefore, the contact portion 40a can enter closer to the vicinity of the nip portion 22c, and the folded end S2 of the sheet can be reliably guided toward the nip portion.

[0085] As the blade carrier 24 moves further in the protruding direction, and the abutment portion 40e2 contacts the pivot axis 31 as shown in Figure 17(b), the blade guide member 40 is restricted from moving any further in the protruding direction. Note that when the blade guide member 40 is moved to its furthest point in the protruding direction, the tip of the blade guide member 40 (the end on the folding roller pair 22 side with respect to the protruding direction) protrudes towards the nip portion 22c side beyond the tangent line (of the two folding rollers 22a and 22b) connecting the outer circumference of the folding rollers 22a and 22b on the sheet loading tray 21 side. On the other hand, as the blade carrier 24 is pushed out in the protruding direction by the rotation of the cam member 25, as shown in Figure 18(a), the pressing projection 24b rotates clockwise against the biasing force of the coil spring 52 because a force exceeding a certain level is applied to the coil spring 52, and it tucks into the lower part of the base portion 40e. As a result, the pressing projection 24b no longer presses against the blade guide member 40, and the blade guide member 40 remains stationary while only the folding blade 23 moves in the protruding direction, reaching a position (third position) where the blade tip protrudes to its maximum extent and pushes the sheet S towards the nip portion 22c. At this time, the tip of the folding blade 23 protrudes more than the tip of the contact portion 40a of the blade guide member 40. That is, the distance from the blade tip to the tip of the contact portion at the third position is greater than the distance from the blade tip to the tip of the contact portion at the second position. As a result, the sheet is reliably drawn into the nip portion 22c of the folding roller pair 22, which rotates in the folded state at the second folding position, and the sheet tip S1 is also drawn into the nip portion 22c, resulting in a tri-fold state.

[0086] Furthermore, when the folding blade 23 is extending outwards from the sheet, that is, when the tip of the folding blade is moving from the second position to the third position, a large load is applied to the blade guide member 40 in the return direction. For example, when folding multiple sheets stacked together, if the rigidity of the sheets is high, a large load is applied to the blade guide member 40 during the folding process. In this case, if a load exceeding a certain level is applied, the blade guide member 40 can move relative to the folding blade 23 in the return direction against the frictional force with the pressing projection 24b which is pressed against the bottom surface of the base portion 40e by the biasing force of the coil spring 52. As a result, the blade guide member 40 will not be damaged when a large load is applied to the blade guide member 40 during the sheet folding process.

[0087] After the tip of the folding blade reaches the third position, when the cam member 25 rotates further, the blade carrier 24 moves in the return direction together with the folding blade 23 (Figure 18(b)). At this time, as described above, the pressing projection 24b is pressed against the base portion 40e of the blade guide member 40 by the biasing force of the coil spring 52, so the blade guide member 40 also moves integrally with the blade carrier 24, that is, simultaneously with the folding blade 23, in the return direction due to the frictional force between the pressing projection 24b and the bottom surface of the base portion 40e.

[0088] As the cam member 25 rotates further and the blade carrier 24 moves in the return direction, the contact portion 40a of the blade guide member 40 contacts the pivot shaft 31, and the blade guide member 40 returns to its home position. The blade guide member 40 is then restricted from moving any further in the return direction (Figure 19(a)). As the cam member 25 rotates further, the blade guide member 40 remains stationary while only the folding blade 23 moves in the return direction and returns to its home position (Figure 19(b)).

[0089] As described above, when the blade carrier 24 moves in the return direction, the folding blade 23 and the blade guide member 40 move simultaneously 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 retracts from the sheet being pulled in by the folding roller pair 22 and the discharge roller 17b faster than the folding blade 23. Therefore, the conveying load on the blade guide member 40 of the sheet S being pulled in by the discharge roller 17b, etc., is reduced.

[0090] (Relative arrangement of blade guide member and pressure guide member) In this embodiment, two blade guide members 40 are arranged at predetermined positions in the sheet width direction, as shown in Figure 4, a schematic plan view of the folding processing device F. 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. When these protruding tip portions 23a protrude the sheet, the sheet is pushed out toward the nip portion 22c of the folding roller pair 22 and the folding process is performed. The blade guide members 40 are positioned above one of the six protruding tip portions 23a, that is, on the upstream side in the direction in which the sheet is being fed into the sheet loading tray 21. Therefore, the folded end 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.

[0091] In order to guide the folded end S2 of the sheet to the nip portion 22c, it is desirable for the blade guide member 40 to be positioned above all six protruding tips 23a (23a1) formed therein, 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 protruding tips 23a1 formed on both ends in the sheet width direction, thereby reducing the number of parts. Furthermore, the folded end S2 of the sheet that is pushed out by the folding blade 23 during the second folding process is more prone to curling near the edges than in the center in the sheet width direction. By guiding this portion toward the nip portion with the blade guide member 40, the aforementioned curling can be effectively prevented.

[0092] Furthermore, the two blade guide members 40 are positioned above the protruding tip 23a1, which is formed slightly closer to the center than both ends in the width direction of the minimum width sheet that can be transported to the sheet loading tray 21. This is because when the sheet is pushed out with the protruding tip 23a, it is more effective to push slightly closer to the center than to the ends in the width direction of the sheet, and the blade guide members 40 are positioned corresponding to the position of the protruding tip 23a1.

[0093] In this embodiment, the pressing guide members 30 are positioned further outward in the sheet width direction than the two blade guide members 40, relative to the position of the blade guide members 40. Specifically, the two pressing guide members 30 are spaced approximately the same distance apart as the width of the smallest sheet that can be processed by the folding processing device F, and are positioned to press and guide both ends of the sheet in the width direction when folding the smallest size sheet. In this embodiment, in addition to the two pressing guide members 30 that can press and guide both ends of the sheet, there is also a pressing guide member 30 that can press and guide the center of the sheet in the width direction, for a total of three pressing guide members 30. More specifically, the smallest sheet that can be processed by the folding processing device F in this embodiment is A4, and the length of the short side of a typical A4 size sheet is 210 mm. The two pressing guide members 30, which can press and guide both ends of the sheet in the width direction, are formed to have a length of 18 mm in the sheet width direction. The length of the straight line connecting the outer ends of each of these two pressing guide members 30 is 226 mm, which is longer than the width of an A4 size sheet. The edges of an A4 size sheet in the width direction overlap 10 mm on each side of a portion of the surface of the pressing guide member 30 near the center in the width direction. The maximum size sheet that can be processed by the folding processing device F is A3, and the length of the short side of a typical A3 size sheet is 297 mm. By setting the length of the straight line connecting the outer ends of each of the two pressing guide members 30, which can press and guide both ends of the sheet in the width direction, to be longer than the width of the minimum size sheet, the guiding effect can be provided even to the edges of the maximum size sheet.

[0094] When the sheet that has undergone the first folding process is being fed back and transported, as described above, the pressing guide member 30 presses the folded end S2 of the sheet to guide it back to the sheet loading tray 21. 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 positioned outside the blade guide member 40 in the sheet width direction. In this embodiment, the pressing guide members 30 positioned on both sides in the sheet width direction are spaced approximately the same distance apart as the width of the smallest size sheet, while the blade guide member 40 is positioned further inside and spaced shorter than the width of the smallest size sheet.

[0095] In this embodiment, the thrusting tips 23a2 are positioned on the outside of each pressing guide member 30. The thrusting tips 23a2 are intended to prevent wrinkles from forming on the sheet when thrusting a large sheet in the sheet width direction, and are positioned inside the edges of the largest sheet (they are not necessary in devices that only handle the smallest size sheet as described above). In other words, it is desirable to position the pressing guide member 30 and the blade guide member 40 to match the smallest size sheet, but if necessary, the thrusting tips 23a2 may be positioned separately on the outside of the pressing guide member 30. To put it another way, the blade guide member 40 is positioned inside the two pressing guide members 30 in the sheet width direction, and the thrusting tips 23a1 are positioned corresponding to the position of the blade guide member 40, and further thrusting tips 23a2 may be positioned on the outside of the two pressing guide members 30 depending on the size of the sheet being handled.

[0096] Furthermore, if the difference between the minimum and maximum sizes handled by the device is large, a blade guide member 40, a thrust tip 23a1 on which the blade guide member 40 is provided, and two pressing guide members 30 may be provided to correspond to the minimum size, and a blade guide member 40, a thrust tip 23a2 on which the blade guide member 40 is provided, and two pressing guide members 30 may be provided to correspond to the maximum size. In this embodiment, a configuration is shown in which two thrust tip 23a1s on which the blade guide member 40 is provided are arranged on either side of the center of the sheet S, but it may also be configured with one thrust tip 23a1 and one blade guide member 40.

[0097] In this embodiment, the pressing guide member 30 is positioned between the thrusting tips 23a1 and 23a2 so as not to interfere with the thrusting tips 23a1 and 23a2 when the pressing guide member 30 moves to the guide position. Therefore, each component can be arranged in a space-saving manner.

[0098] <Drive Control> Next, the control configuration of the drive system when folding the sheet will be explained. As shown in the block diagram in Figure 20, the control unit 60 controls the driving of the folding roller motor 61 that drives and rotates the folding roller pair 22, the discharge roller motor 62 that drives and rotates the discharge roller 17b, and the restrictor stopper motor 63 that operates the sheet lifting mechanism 27 for raising and lowering the restrictor stopper 26, in accordance with the steps in the flowcharts shown in Figures 21 and 22. Similarly, the control unit 60 also controls the driving of the cam motor 64 that drives the cam member 25 for operating the blade carrier 24, and the press guide motor 33 that rotates the press guide member 30.

[0099] Figures 21 and 22 are flowcharts showing the drive control procedure when the sheet S is transported to the sheet loading tray 21, the leading edge of the sheet abuts against a regulating stopper 26 which is stopped at a predetermined position, and the folding process is executed from a state where the first folding position is opposite the folding blade 23.

[0100] When the folding process is executed, the cam motor 64 is driven, causing the blade carrier 24 to move in the protruding direction, and the folding blade 23 contacts the first folding position of the sheet S and protrudes toward the nip portion 22c (S1). Simultaneously, the folding roller motor 61 and the discharge roller motor 62 are driven, causing the folding roller pair 22 and the discharge roller 17b to rotate in the forward direction (S2). Each of the motors is a pulse motor, and the number of drive pulses is counted when a motor is driven.

[0101] As the cam member 25 rotates, the folding blade 23 protrudes a predetermined amount so that the first fold of the sheet S extends to the nip portion 22c of the folding roller pair 22, then the direction of travel reverses and it moves in the return direction to return to the home position (S3).

[0102] As the folding blade 23 protrudes, the sheet S protrudes towards the nip portion 22c of the folding roller pair 22, and is folded while being gripped and conveyed by the folding roller pair 22. It is then conveyed together with the folding roller pair 22 by the discharge roller 17b, which constitutes the sheet conveying means. When the sheet is gripped and conveyed by the discharge roller 17b (S4), the folding roller motor 61 stops when the folding rollers 22a and 22b have their second roller surfaces 22a3 and 22b3 facing each other (S4, S5). As a result, the folding roller pair 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 low coefficient of friction. In this embodiment, whether the sheet has been transported to the discharge roller 17b and whether the second roller surfaces 22a3 and 22b3 of the folding roller pair 22 are facing each other is determined by the motor's pulse count. However, other configurations are also possible, such as detecting the sheet S with a sensor and controlling the motor drive according to the detection result.

[0103] Then, when the folded end S2 of the conveyed sheet S reaches a predetermined area (S7), the discharge roller motor 62 is stopped to stop the sheet conveyance (S8). This predetermined area is the area between the rotational trajectory L3 of the pressing guide member 30 and the guide surface 21a of the sheet loading tray 21 where the folded end S2 of the sheet is located (see Figure 14(a)). By stopping the sheet so that the folded end S2 is within this area, when the pressing guide member 30 is rotated, the pressing portion 30c can reliably press the sheet S in the direction of switchback conveyance (see Figure 14(b)), and furthermore, the folded end S2 being conveyed in the switchback direction can be guided by the guide portion 30b (see Figure 14(c)).

[0104] After stopping the folded end S2 of the sheet S 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 reaches a position (the position shown in Figure 14(c)) where it can guide the sheet S being transported in a switchback manner (S9). In addition, along with the rotation of the pressing guide member 30, the restricting stopper motor 63 is driven to move the restricting stopper 26 to a position where it can receive the sheet S being transported in a switchback manner.

[0105] As described above, after the pressing guide member 30 rotates, the discharge roller motor 62 and the folding roller motor 61 are driven in reverse (S10). As a result, the discharge roller 17b and the folding roller pair 22 rotate in reverse, and the sheet S is conveyed in a switchback manner. At this time, as described above, the sheet is guided by the pressing guide member 30, so the sheet is conveyed in a switchback manner in the direction in which the regulating stopper 26 of the sheet loading tray 21 is located, without any conveying problems.

[0106] The discharge roller motor 62 and the folding roller motor 61 are driven to transport the sheet S in a switchback manner. Once the sheet S has passed through the nip portion 22c of the folding roller pair 22 and has fallen until it contacts the regulating stopper 26, completing the switchback transport (S11), the drives of the discharge roller motor 62 and the folding roller motor 61 are stopped (S12). Here, the completion of the switchback transport 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 to determine that a predetermined amount of sheet S has been transported.

[0107] 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 Figure 14(c)) to the retracted position (see Figure 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 moving the pressing guide member 30 from the retracted position to the guide position, the speed is reduced and it is rotated in order to press the stopped sheet S to change its orientation for switchback transport, whereas when moving it from the guide position to the retracted position, it is returned quickly, which allows the timing of the next operation to be advanced.

[0108] Then, after moving the pressing guide member 30 to the reverse transport guide position (see Figure 9(a)) (S13), the restricting stopper motor 63 is driven to move the sheet S so that the second folding position is opposite the folding blade 23 (S14). In this state, the cam motor 64, folding roller motor 61, and discharge roller motor 62 are driven to perform the second folding operation (S15-S17).

[0109] In this embodiment, each component is driven by a separate motor, but it is also possible to drive each component by using a common motor and switching the drive using a clutch or the like.

[0110] <Other Embodiments> In the embodiment described above, an example was shown in which, when the folding blade 23 and the blade guide member 40 are moved relative to each other, the angle of the contact portion 40a with respect to the base portion 40e changes as the engaging projection 40d of the blade guide member 40 slides in the elongated hole 50. However, the angle of the contact portion 40a with respect to the base portion 40e may be fixed and not changed without providing the link mechanism. Even in this case, the folding blade 23 is configured to move relative to the blade guide member 40, and even after the movement of the blade guide member 40 stops during protrusion, the folding blade 23 is extended to push the sheet towards the nip portion 22c, thereby ensuring that the sheet is pushed towards the nip portion 22c without interfering the blade guide member 40 with the folding roller pair 22. Furthermore, the configuration can be simplified by not providing an angle changing mechanism.

[0111] In the embodiment described above, the folding rollers 22a and 22b are shown 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, the folding rollers 22a and 22b may be composed of rollers with a constant outer diameter, such as circular rubber rollers. In this case, when the sheet is passing through the folding roller pair, it is always held between the nip portions of the folding roller pair, so the amount of sheet being transported can be controlled by the rotation of the folding roller pair. Therefore, when stopping the folded end of the sheet at a predetermined position (see Figure 7(a)), this can be controlled by the amount of drive of the folding rollers.

[0112] In the embodiment described above, an example was shown in which the movement in the return direction from the tip of the folding blade being in the third position was initiated simultaneously by the folding blade 23 and the blade guide member 40. However, for example, the folding blade 23 and the blade guide member 40 may be configured to be operated by separate drive systems, so that the movement in the return direction is initiated first by the folding blade 23, followed by the blade guide member 40.

[0113] Even when the tip of the folding blade protrudes to the third position and the sheet folding portion is nipped by the folding roller pair 22, the folded end S2 is not yet nipped by the nip portion 22c (see Figure 18(a)) and is nipped later. In this case as well, by returning the blade guide member 40 later than the folding blade 23 as described above, even when the folding blade 23 starts moving in the return direction, the folded end S2 is guided by the blade guide member 40 and is reliably pulled into the nip portion 22c.

[0114] Furthermore, in the embodiments described above, an example was shown in which the amount of sheet transported and the amount of rotation of the pressing guide member 30 were controlled by counting the number of motor pulses. However, in addition to motor pulses, for example, a photosensor for detecting the sheet or a photosensor for detecting the pressing guide member 30 may be provided, and the sheet transport or the rotation of the pressing guide member may be controlled by detecting when the sheet has been transported to a predetermined position or when the pressing guide member 30 has been rotated to a predetermined angle.

[0115] Furthermore, in the embodiment described above, a restricting stopper 26 is provided at the lower end of the sheet loading tray 21 to restrict the leading edge of the loaded sheet in the transport direction by contacting it, and the restricting stopper 26 is provided so as to be able to move up and down along the sheet loading tray 21 by a sheet lifting mechanism 27. In other embodiments, pairs of rollers for transporting the sheet may be arranged on the upstream and downstream sides of the sheet transport direction, sandwiching the folding blade 23 and folding roller pair 22 of the sheet loading tray 21. In that case, when the sheet S that has undergone the first folding process is transported in a switchback manner, it can be returned to either the upstream or downstream side of the sheet transport direction, sandwiching the folding blade 23 and folding roller pair 22 of the sheet loading tray 21.

[0116] <Variation> Figures 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 for parts common to the embodiment described above, and their descriptions are omitted. Figure 23 is a perspective view showing the blade guide member 140 in the protruding direction. Although a pressing guide member 30 is provided to the right of the blade guide member 140 in Figure 23, it is omitted from the illustration for convenience.

[0117] The blade guide member 140 consists of a contact portion 140a, an arm portion 140c, an engaging projection 140d, a locking portion 140e, a pivot point 140f, a pressed portion 140g, and a locking projection 140h. The contact portion 140a is a member that contacts and guides the sheet. One end of the contact portion 140a is provided with a pivot point 140f, and the other end is provided with an arm portion 140c, an engaging projection 140d that slidably engages with an elongated hole 50 formed in the frame of the sheet processing device B, and a locking portion 140e formed to tension a tension spring 151 between the arm portion 140c and a locking portion 124a formed in the frame of the sheet processing device B. This tension spring 151 biases the blade guide member 140 upward in Figure 25. Furthermore, in Figure 25, a pressed portion 140g is provided on the back side (upstream side in the protruding direction) of the contact portion 140a, which is contacted by a pressing projection 124b1 described later. The pressed portion 140g is pushed out in the protruding direction by the pressing projection 124b1, causing the contact portion 140a to rotate clockwise in Figure 25 around the pivot point 140f. In other words, the contact portion 140a is configured to change angle from an upright position approximately perpendicular to the folding blade 23a as shown in Figure 25, to a position where the part of the contact portion 140a opposite the pivot point 140f tilts towards the upstream side in the protruding direction around the pivot point 140f, as shown in Figure 26. Furthermore, the locking projection 140h, which is bent from the pivot point 140f, acts as a stopper to prevent the pressed portion 140g from coming off the pressing projection 124b1 when the pressing projection 124b1 is pressing against the pressed portion 140g.

[0118] The blade carrier 124 holds the folding blade 23 and the slide rail 124c, and (similar to the embodiment described above) is configured to move integrally in the ejection and retraction directions by a cam 25. The slide rail 124c holds the pressing member 124b so that it can slide in the ejection and retraction directions. The pressing member 124b has a pressing projection 124b1 formed at the downstream end in the ejection direction, a locking portion 124b2 formed at the upstream end in the ejection direction into which a spring 124e engages, and a contact portion 124d formed between the pressing projection 124b1 and the locking portion 124b2.

[0119] Figure 24 is a top view of the blade guide member 140 and the blade carrier 124. Figure 24(a) shows the blade carrier 124 in its home position (the protruding tip 23a1 is in the first position), Figure 24(b) shows the blade carrier 124 moved by a predetermined amount in the protruding direction by the cam 25 (the protruding tip 23a1 is in the second position), and Figure 24(c) shows the blade carrier 124 moving further in the protruding direction so that the protruding tip 23a1 protrudes to its maximum extent and the sheet S protrudes towards the nip portion 22c (the protruding tip 23a1 is in the third position).

[0120] The blade carrier 124 is provided with a locking portion 124f to which one end of a spring 124e is attached. The other end of the spring 124e is attached to a locking portion 124b2 of the pressing member 124b, and this spring 124e biases the pressing member 124b in the protruding direction (downward in Figure 24) on the slide rail 124c.

[0121] Referring to Figure 25, the pressing member 124b and the slide rail 124c are provided with projections 124b3 and 124c1, respectively. The engagement of projections 124b3 and 124c1 restricts the movement of the pressing member 124b in the ejection direction, even when the spring 124e biases the pressing member 124b in the ejection direction in the home position. When the blade carrier 124 moves in the ejection direction in this state, the slide rail 124c also moves in the ejection direction, and the projections 124c1 provided on the slide rail 124c also move in the ejection direction. As the projections 124c1 move, the pressing member 124b, which is biased by the spring 124e, also moves in the ejection direction at the same time.

[0122] As the pressing member 124b moves in the protruding direction from the state shown in Figure 25, the pressing projection 124b1 presses against the pressed portion 140g of the blade guide member 140, causing the contact portion 140a of the blade guide member 140 to move in the protruding direction. At this time, the blade guide member 140 rotates clockwise around the pivot point 140f while the engaging projection 140d slides downward through the elongated hole 50, in opposition to the biasing force of the tension spring 151.

[0123] When the blade carrier 124 moves to the state shown in Figure 26 (with the thrust tip 23a1 in the second position), the contact portion 124d of the pressing member 124b abuts against the pivot axis 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 biases the pressing member 124b in the thrusting direction, it cannot move any further in that direction. At this position, the contact portion 140a of the blade guide member 140 guides the sheet toward the folding roller pair 22, and the thrust tip 23a abuts against the sheet, folding it and pushing the sheet toward the roller pair.

[0124] Furthermore, when the blade carrier 124 moves in the protruding direction, it reaches the state shown in Figure 27. In Figure 27, the blade guide member 140 remains stopped in the position shown in Figure 26, while only the blade carrier 124, the folding blade 23 (protruding tip 23a), and the slide rail 124c move in the protruding direction, moving to a position (third position) where the protruding tip 23a1 protrudes to its maximum extent and pushes the sheet S towards the nip portion 22c. At this time, the protruding tip 23a1 of the folding blade 23 protrudes more than the tip of the contact portion 140a of the blade guide member 140. That is, the distance from the blade tip to the tip of the contact portion at the third position is greater than the distance from the blade tip to the tip of the contact portion at the second position. As a result, the sheet is reliably pulled into the nip portion 22c of the folding roller pair 22, which rotates in the folded state at the second folding position, and the sheet tip S1 is also pulled into the nip portion 22c, resulting in a tri-fold state.

[0125] Subsequently, the blade carrier 124 moves in the return direction. At this time, the pressing member 124b is still stopped at the position shown in Figure 26. Figure 28 shows the state where the protruding tip 23a1 has returned to the second position. Here, the projection 124c1 provided on the slide rail 124c engages with the projection 124b3 provided on the pressing member 124b. In this state, if the blade carrier 124 is moved further in the return direction, the slide rail 124c and the pressing member 124b move simultaneously in the return direction, counteracting the biasing force of the spring 124e. When the pressing member 124b moves further in the return direction than the position shown in Figure 28, the pressing projection 124b1 moves away from the pressed portion 140g of the blade guide member 140, so the blade guide member 140 changes angle to the upright position shown in Figure 29 due to the biasing force of the tension spring 151.

[0126] Furthermore, when the folding blade 23 is pushing out the sheet, that is, 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 sheets stacked together and the rigidity of the sheet is high, a large load is applied to the blade guide member 140 during the folding process. In this case, if a load exceeding a certain level is applied, the blade guide member 140 can move relative to the folding blade 23 in the return direction against the spring 124e. As described above, since the blade guide member 140 is biased in the pushing direction by the spring 124e via the pressing member 124b, if a load exceeding the biasing force of the spring 124e is applied to the blade guide member 140, the blade guide member 140 is configured to 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 the sheet folding process.

[0127] Figures 30 to 33 illustrate a deflection guide 170 provided between the folding roller 22a and the guide surface 21a of the sheet loading tray 21. The deflection guide 170 has a flexible guide member 170a (such as Mylar) that contacts the sheet S and guides the sheet S, and one end of the guide member 170a is fixed to a bracket 172. The bracket 172 has an engaging piece 171 that protrudes toward the folding roller 22a, and this engaging piece 171 is positioned by engaging with the engaging portion 22d (see Figure 33) of the folding roller 22a. The engaging portion 22d of the folding roller 22a has a first roller surface 22a2 with a constant radius R1 around the rotation axis of the rotation shaft 22a1, and a second roller surface 22a3 whose distance from the rotation axis of the rotation shaft is smaller than the radius R1 of the first roller surface 22a2. With the engaging piece 171 engaged with the engaging portion 22d, the folding roller 22a rotates, allowing the bracket 172 that holds the guide member 170a to rotate around the pivot axis 173. The surface of the engaging portion 22d with which the engaging piece 171 engages is made of a plastic resin material or the like with a low coefficient of friction.

[0128] In this embodiment, the guide member 170a is provided with a guide region capable of guiding the sheet S being transported. The lower end of the guide region in Figure 30 is called the first end 170a1, and the upper end is called the second end 170a2. If the bracket 172 can also guide the sheet S, the sheet guide region of the bracket 172 is also considered part of the guide member 170a, and the second end 170a2 becomes the upper end of the guide region of the bracket 172.

[0129] In this embodiment, the space between the first transport guide member 181 and the second transport guide member 182 that constitute the sheet transport path 20 is called the guide space 180, and the space between the first loading guide member 184 and the second loading guide member 185 that form the sheet loading tray 21 is called the storage space 183.

[0130] Figure 30 shows the sheet S being transported from the guide space 180 toward the storage space 183 (this direction is called the first transport direction) with the engaging piece 171 engaged with the first roller surface 22a2 and the guide member 170a positioned at the first guide position. Figure 31 shows the sheet S (in this figure, a sheet S that has been folded once) being transported from the storage space 183 toward the guide space 180 (this direction is called the second transport direction) with the engaging piece 171 engaged with the second roller surface 22a3 and the guide member 170a positioned at the second guide position.

[0131] Figure 32(a) shows the state in which the guide member 170a is positioned at the first guide position, and Figure 32(b) shows the state in which the guide member 170a is positioned at the second guide position. The dashed line 186 in the figures is a line (hereinafter referred to as the imaginary line 186) connecting the transport guide end 181a, which is the downstream end in the first transport direction of the first transport guide member 181, and the loading guide end 184a, which is the downstream end in the second transport direction of the first loading guide member 184.

[0132] As shown in Figure 32(a), when the guide member 170a is positioned in the first guide position, the first end 170a1 of the guide member 170a is positioned on the opposite side of the folding roller 22a (guide surface 21a side) in the thickness direction of the sheet S being conveyed, relative to the imaginary line 186. The second end 170a2 is positioned on the folding roller 22a side in the thickness direction of the sheet S, relative to the imaginary line 186. As a result, as shown in Figures 30(a) and 30(b), when the sheet S is conveyed in the first conveying direction, the leading edge of the sheet S (the downstream end in the first conveying direction) can be guided from the guide space 180 to the storage space 183.

[0133] On the other hand, as shown in Figure 32(b), when the guide member 170a is positioned at the second guide position, the first end 170a1 of the guide member 170a is positioned on the folding roller 22a side in the thickness direction of the sheet S being conveyed, relative to the imaginary line 186. The second end 170a2 is positioned on the opposite side of the folding roller 22a (guide surface 21a side) in the thickness direction of the sheet S, relative to the imaginary line 186. As a result, as shown in Figures 31(a) and 31(b), when the sheet S is conveyed in the second conveying direction, the leading edge of the sheet S (the downstream end in the second conveying direction) can be guided from the storage space 183 to the guide space 180.

[0134] As shown in Figure 33, multiple guide members 170a are provided in the width direction of the sheet S. In this embodiment, two guide members 170a are arranged on both sides of the center of the sheet width, inside the smallest sheet width in the sheet width direction. The dashed lines in Figure 33 indicate the folding rollers 22a and 22b, and the engaging piece 171 is provided at a position corresponding to the engaging portion 22d of the folding roller 22a. In addition, the guide members 170a are arranged at positions corresponding to the two innermost protruding tips 23a of the six protruding tips 23a, 23a1, and 23a2.

[0135] The guide member 170a guides the sheet S not only when conveying the sheet S in the first and second conveying directions, but also when the folding blade 23 is ejected. As described above, Figure 25 shows the state in which the folding position of the sheet S is positioned opposite the folding blade 23 during the folding process. In Figure 25, the guide member 170a is positioned in the first guide position.

[0136] In this state, when the folding blade 23 is moved in the protruding direction, the sheet S stabilizes in position between the guide member 170a and the contact portion 140a of the blade guide member 140, thereby suppressing misalignment of the sheet during the folding process. As described above, since the guide member 170a is made of flexible Mylar or the like, when the sheet S comes into contact with it, the guide member 170a guides the sheet S while bending in the protruding direction.

[0137] When the tip 23a1 of the folding blade 23 pushes the sheet S into the nip portion 22c of the folding roller pair 22 and the folding roller pair 22 is rotated by a predetermined amount, the engaging piece 171 engages with the second roller surface 22a3 and the guide member 170a is positioned at the second guide position (see Figure 28). This is because if the guide member 170a continues to bias the sheet S in the unfolding direction even after the folded end S2 of the sheet S has been folded into the nip portion 22c, the conveying load on the sheet S by the folding roller pair 22 will increase. Therefore, it is desirable to move the guide member 170a to the second guide position and guide the sheet S toward the nip portion 22c once the folded 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 has begun.

[0138] From the above, the guide member 170a of the deflection guide 170 is positioned at the first guide position when transporting the sheet S in the first transport direction (sheet transport for receiving the sheet S into the sheet loading tray 21) to guide the sheet S from the guide space 180 to the storage space 183, and is positioned at the second guide position when transporting the sheet S in the second transport direction (sheet transport when transporting the sheet S received into the sheet loading tray 21 to the binding processing unit 17a, or when the second folding position of the sheet S is positioned to face the folding blade 23 in order to perform a second folding process after the first folding process is completed) to guide the sheet S from the storage space 183 to the guide space 180.

[0139] Furthermore, during the folding process, the guide member 170a is positioned in the first guide position to guide the sheet S so that the folding position does not shift until the folding blade 23 pushes the sheet S into the nip portion 22c of the folding roller pair 22. After the folding position of the sheet S reaches the nip portion 22c, it is positioned in the second guide position to guide the sheet S to the nip portion 22c while reducing the transport load.

[0140] In this embodiment, the guide member 170a was moved between the first and second guide positions by bringing the engaging piece 171 into contact with the circumferential surface (engaging portion 22d) of the folding rollers 22a of different diameters. However, it may be moved using a different drive source. Also, although the configuration shown places the guide member 170a between the folding roller 22a and the guide surface 21a, it may be placed between the folding roller 22b and the guide surface 21a, or in both places.

[0141] Furthermore, although this embodiment shows a configuration in which the first guide position of the guide member 170a during sheet transport and the first guide position of the guide member 170a during folding are the same, they do not need to be exactly the same and can be changed as appropriate. It goes without saying that the second position can also be changed as appropriate.

[0142] Furthermore, although all the embodiments described above show a method in which the sheet S is folded twice to create an inward tri-fold, if the blade guide members 40 and 140 are provided even in a single folding process (the first folding process for an inward tri-fold or the folding process when folding in half), the sheet S can be properly guided during the folding process. [Explanation of symbols]

[0143] A...Image forming apparatus B...Sheet processing device F...Folding processing device L1 ...Nip wire L2 ... axis of rotation L3 ... Rotation trajectory S...Seat S1 ... Front of the seat S2 ... Folded end 20 ... Sheet transport path 21...Seat loading tray 21a ... Guide surface 22 ...Folding roller pair 22a, 22b ... Folding rollers 22a1, 22b1 ... axis of rotation 22a2, 22b2 ... First roller surface 22a3, 22b3 ... Second roller surface 22c ...nipple area 23…Folding blade 23a ... thrust tip 24…Blade carrier 24a...Locking part 24b ... Pressing projection 24c ...cam pin 25 ... Cam component 25a ... Rotation axis 25b ... Cam groove 26... Regulatory stopper 27 ...Seat lifting mechanism 27c ... transmission belt 28a, 28b ... Sheet side alignment members 30 ...Pressure guide member 30a ... Rotating part 30b ... Guide section 30c ... Pressing part 31 ... Rotating shaft 32 ... Drive transmission member 33 ...Pressure guide motor 40 ... Blade guide member 40a...Abutment part 40b…Mating hole part 40c ... Arm section 40d...Engagement protrusion 40e...Base part 40e1 ... Locking part 40e2 …Abutting section 40f...Shaft part 40f1…protrusion 50...long hole 51 ...Tension spring 52 ... coil spring 60 ... Control Unit 61 ... Folding roller motor 62 ... Discharge roller motor 63... Regulator stopper motor 64... Cam motor 124…Blade Carrier 140 ... Blade guide member 170 ... Bias Guide

Claims

1. In a sheet processing device 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 an inward triple fold so that one end of the sheet folded by the first folding process becomes the inside of the folded sheet, A pair of folding rollers that perform the aforementioned folding process on the sheet at the nip portion, A pressing member for pressing the sheet toward the nip portion in order to perform the aforementioned folding process on the sheet, When performing the second folding process, an opening prevention member prevents the sheet folded in the first folding process from opening beyond a certain point, such that one end of the sheet folded in the first folding process enters the nip portion. The device includes a moving mechanism that moves the push-in member and the opening prevention member toward the folding roller pair, then stops the opening prevention member so that it does not come into contact with the outer circumference of the folding roller pair, and moves the push-in member further toward the nip portion beyond the position where the opening prevention member stops, The sheet processing apparatus is characterized in that the opening prevention member is configured to be displaceable relative to the pressing member in the return direction when the opening prevention member receives a load of a certain amount or more from the sheet in the return direction opposite to the direction of movement toward the folding roller pair during the execution of the second folding process.

2. The sheet processing apparatus according to claim 1, characterized in that the moving mechanism moves the opening prevention member in conjunction with the movement of the pushing member.

3. An image forming apparatus for forming an image on a sheet, A sheet processing device that folds a sheet sent from the image forming apparatus, It has, The image forming system is characterized in that the sheet processing apparatus is the sheet processing apparatus described in claim 1 or claim 2.

Images