Sheet processing device and image forming system

Abstract

To provide a sheet processing device causing no buckling of a folded sheet and no lowering of productivity of the sheet folding processing, and an image forming system equipped therewith.SOLUTION: In a sheet processing device, when a sheet subjected to first folding processing with a folding roller pair 22 is conveyed to a second position by switchback conveying, conveying speed in conveying with a fold set at a tip side is controlled to be faster than the conveying speed in conveying with the fold subjected to the folding processing set at a rear end side.SELECTED DRAWING: Figure 14

Description

Technical Field

[0001] The present invention relates to a sheet processing device 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 a sheet discharged from an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multi-functional device thereof, a sheet processing device that folds a sheet bundle into a booklet shape has been provided. For example, a sheet processing device is known that bends a predetermined position of a sheet carried out from an image forming apparatus to a sheet stacker 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 devices that perform folding processing on a sheet, there is a sheet processing device that performs not only double folding but also folding processing at two different positions of the sheet, and performs inner triple folding so that one end of the sheet is folded inside the folded sheet. In such a device, the sheet subjected to the first folding process is conveyed back by switchback and returned to the stacker, and the second folding process is performed on this sheet at a position different from the first time to perform inner triple folding (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] During the folding process, when the sheet that has undergone the first folding process is transported back to the transport path via a switchback, the edges of the sheet are transported along the guide surface of the guide member. However, the sheet being transported via the switchback has the fold towards the rear end and the folded, open end towards the front end. At this time, the force of the folded fold returning to its original shape causes a force to act on the open end in the direction of opening. As a result, frictional resistance increases as the end closer to the fold is transported along the guide surface, which can cause the sheet being transported via the switchback to buckle. Due to the nature of inertia, the occurrence of buckling becomes more pronounced the faster the sheet moves.

[0006] One way to avoid the occurrence of buckling is to control the sheet's movement speed to below a certain speed. For example, when a folded sheet is transported in a switchback manner, a configuration has been proposed in which the speed is slowed to reduce the resistance when the open end of the sheet collides with the guide surface, thereby preventing buckling (Patent Document 2).

[0007] However, slowing down the sheet transport speed increases the time required for folding, which reduces the productivity of the folding process.

[0008] The present invention has been made in view of the above circumstances, and its objective is to provide a sheet processing apparatus and an image forming system equipped therewith that do not cause buckling of the folded sheet and do not reduce the productivity of the sheet folding process. [Means for solving the problem]

[0009] A typical configuration according to the present invention for achieving the above objective is a sheet processing apparatus that performs a first folding process on a sheet, and then performs a second folding process at a position different from the crease formed by the first folding process, so that one end of the sheet folded by the first folding process is inside the sheet folded by the second folding process, and comprises a transport path having a guide surface for guiding a sheet being transported in a predetermined transport direction, a pair of rotating bodies capable of transporting the sheet by switching back in a first direction in which the sheet transported on the transport path is gripped by a nip portion and rotated to pull in the sheet and perform the folding process, and a contact portion having a front The sheet processing apparatus comprises: position adjustment means capable of adjusting the position of the sheet by moving in the transport direction and in the opposite direction to the transport direction; a protruding member that pushes the sheet transported on the transport path toward the nip portion of the rotating body pair; a direction changing member that can move between a standby position that does not act on the sheet being transported on the transport path and a guide position that guides the sheet that has been folded by the rotating body pair and is being transported in the second direction to change its orientation toward the transport direction; and a control unit that controls the drive of the sheet processing apparatus, wherein the control unit controls the rotating body pair and the position adjustment means so that the speed at which the sheet that has been folded for the first time by the rotating body pair is transported with the folded edge toward the leading edge is faster than the speed at which the sheet is transported with the folded edge toward the trailing edge. [Effects of the Invention]

[0010] In this invention, when transporting a folded sheet, the transport speed when the fold is towards the leading edge relative to the transport direction is increased compared to the transport speed when the fold is towards the trailing edge relative to the transport direction. This suppresses buckling of the sheet while also suppressing a decrease in the productivity of the folding process. [Brief explanation of the drawing]

[0011] [Figure 1] Diagram illustrating the overall configuration of the image forming system of this embodiment. [Figure 2] Explanatory drawing of the overall configuration of the sheet processing apparatus in the image forming system [Figure 3] Cross-sectional view showing the folding apparatus of the sheet processing apparatus [Figure 4] (a) Cross-sectional view showing the gripping state of the gripping means, (b) Perspective view thereof [Figure 5] (a) Cross-sectional view showing the gripping release state of the gripping means, (b) Perspective view thereof [Figure 6] Plan view showing the sheet folding processing apparatus [Figure 7] Block diagram of the folding process control configuration [Figure 8] Flowchart showing the inner triple-fold processing procedure [Figure 9] Flowchart showing the inner triple-fold processing procedure [Figure 10] Flowchart showing the inner triple-fold processing procedure [Figure 11] (a)(b) Cross-sectional explanatory drawing of the inner triple-fold operation of the sheet [Figure 12] (a)(b) Cross-sectional explanatory drawing of the inner triple-fold operation of the sheet [Figure 13] (a)(b) Cross-sectional explanatory drawing of the inner triple-fold operation of the sheet [Figure 14] (a)(b) Cross-sectional explanatory drawing of the inner triple-fold operation of the sheet [Figure 15] (a)(b) Cross-sectional explanatory drawing of the inner triple-fold operation of the sheet [Figure 16] (a)(b) Cross-sectional explanatory drawing of the inner triple-fold operation of the sheet [Figure 17] (a)(b) Cross-sectional explanatory drawing of the inner triple-fold operation of the sheet [Figure 18] Cross-sectional view of the sheet processing apparatus provided with a pair of folding rollers having a small diameter portion

Mode for Carrying Out the Invention

[0012] 〔First Embodiment〕 Next, while referring to the drawings, a sheet processing apparatus according to a preferred embodiment of the present invention and an image forming system including the same will be described. FIG. 1 schematically shows the overall configuration of an image forming system including the sheet processing apparatus according to an embodiment of the present invention. As shown in the figure, the image forming system 100 is composed of an image forming apparatus A and a sheet processing apparatus B installed therewith.

[0013] <Image forming apparatus> The image forming apparatus A is composed 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, a discharging unit 4, and a data processing unit 5 inside the apparatus housing 1.

[0014] The feeding unit 2 is composed of a plurality of cassette mechanisms 2a, 2b, 2c for storing image forming sheets of different sizes, and feeds out a sheet of the size designated by the main body control unit (not shown) to the feeding path 2f. Each cassette mechanism 2a, 2b, 2c is detachably installed from the feeding unit 2, and includes a separating mechanism for separating the sheets inside one by one and a feeding mechanism for feeding out the sheets. In the feeding path 2f, there are provided conveyance rollers for feeding the sheets supplied from each cassette mechanism 2a, 2b, 2c to the downstream side, and a registration roller pair for aligning the leading edges of the sheets at the end of the path.

[0015] A large-capacity cassette 2d and a manual feed tray 2e are connected to the feeding path 2f. The large-capacity cassette 2d is composed of an option unit for storing sheets of a size that is consumed in large quantities. The manual feed tray 2e is configured to be able to supply special sheets such as thick paper sheets, coated sheets, and film sheets for which separation feeding is difficult.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] <Sheet processing device> Next, we will explain the overall configuration of the sheet processing device B, which processes the sheets sent from the image forming apparatus A.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] The second processing unit B2 is a folding processing unit that folds sheets or multiple sheets that are transported via switchback from the second discharge path 13b into sheet bundles, or folds the sheet bundles after binding 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 sheets or sheet bundles are discharged by a pair of discharge rollers 17b onto a loading tray 17c provided on the outside of the device housing 11.

[0028] 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.

[0029] 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 sheets fed in from the second discharge path 13b, or sheet bundles that have been assembled and aligned 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 device that binds the sheet bundles by driving staples into them.

[0030] 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 intermediate tray 21, an intermediate tray 21, which constitutes part of the sheet transport path 20, is provided downstream of the sheet transport path 20 for positioning and loading sheets to be folded. Immediately upstream of the intermediate 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.

[0031] <Folding Processing Equipment> On one side of the intermediate 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 intermediate tray 21. 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-together part, is positioned toward the intermediate tray 21. The folding rollers 22a and 22b are arranged side by side on the upstream and downstream sides of the intermediate tray 21, respectively, along the conveying direction of the sheet being transported from the upstream side to the downstream side, with approximately equal spacing from the intermediate 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 made of a rotating belt or the like. Furthermore, the folding roller pair 22 can be made by arranging multiple folding rollers (rotating bodies) in series along the axial direction of each folding roller 22a and 22b.

[0032] On the opposite side of the folding roller pair 22, with the intermediate tray 21 in between, a folding blade 23 is positioned as an ejector 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 intermediate tray 21 at approximately a right angle, that is, in a direction that intersects with the conveying direction of the sheets being transported from the second discharge path 13b to the intermediate tray 21.

[0033] 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.

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

[0035] The blade carrier 24 reciprocates in a direction approaching or moving away from the intermediate 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 has not entered the sheet transport path 20 formed by the intermediate tray 21, and the maximum protruding position, where it is sandwiched between the nip portion 22c of the folding roller pair 22.

[0036] At the lower end of the intermediate tray 21, there is a restricting stopper 26, which is a position adjustment means that restricts the leading edge of the conveyed sheet in the direction of transport by bringing it into contact with the tray, thereby adjusting and positioning the sheet within the sheet transport path 20. The restricting stopper 26 is provided so as to be able to move up and down along the intermediate tray 21 by a sheet lifting mechanism 27.

[0037] 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 intermediate tray 21 near its upper and lower ends, and a transmission belt 27c wrapped around both pulleys, which are located below the blade carrier 24 when the blade carrier is in its initial position, where the tip of the folding blade 23 is not yet in the sheet transport path 20 formed by the intermediate tray 21 on the back side of the intermediate 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 intermediate tray 21 and positioning it at the desired height.

[0038] As described above, the restricting stopper 26 is movable up and down along the intermediate tray 21, and a gripping means 50 is attached to the restricting stopper 26, which is also movable up and down together with the restricting stopper 26. The gripping means 50 grasps the sheet that has been transported to the intermediate tray 21, ensuring that the sheet moves along with the movement of the restricting stopper 26.

[0039] Next, the configuration of the gripping means 50 will be described with reference to Figures 4 and 5. Figure 4(a) is a cross-sectional view of the gripping means 50 in a state where it can grip the seat, and (b) is a perspective view thereof. Figure 5(a) is a cross-sectional view of the gripping means 50 in a state where it has released its grip on the seat, and (b) is a perspective view thereof.

[0040] As shown in Figure 4, the gripping means 50 is attached to the restricting stopper 26. The restricting stopper 26 has a base portion 26a that is movable along the guide surface 21a of the intermediate tray 21 by drive transmission from the transmission belt 27c, and a contact portion 26b is provided on the base portion 26a. This contact portion 26b positions the sheet when the lower end of the sheet conveyed to the intermediate tray 21 comes into contact with it, and during the folding process, the sheet is moved to the folding position by adjusting the position of the contact portion 26b. The contact portion 26b has upright portions 26c that are continuously bent at right angles, and is designed to accommodate the sheet that comes into contact with the contact portion 26b so that it does not fall off.

[0041] The gripping means 50 is attached to the base 26a and moves integrally with the base 26a as the base 26a moves along the guide surface 21a. The gripping means 50 has a support portion 50a that is slidably attached to the base 26a in a direction perpendicular to the conveying direction of the sheet being transported to the intermediate tray 21 and along the thickness of the sheet, with an upright portion 50b integrally formed thereon, and a gripping portion 50c formed on the inner surface side of the upright portion 50b. Furthermore, an opposing portion 50d is integrally provided with the base 26a at a position opposite the gripping portion 50c across the sheet transport path 20 to the intermediate tray 21.

[0042] An elastic member such as a spring (not shown) is attached between the base portion 26a and the support portion 50a, so that the upright portion 50b is always biased toward the opposing portion 50d. As a result, the gripping portion 50c is normally pressed against the opposing portion 50d, creating a gripping state in which the sheet conveyed to the intermediate tray 21 can be gripped (see Figures 4(a) and 4(b)).

[0043] Furthermore, as shown in Figure 5(a), the base portion 26a is provided with a grip cam 50e engaged with the support portion 50a and a cam motor (not shown) for rotating the grip cam 50e. The grip cam 50e has a large diameter portion and a small diameter portion, and when the grip cam 50e rotates, the support portion 50a engaged with it slides in the direction of the arrow shown in Figure 5(a), causing the gripping portion 50c to come into contact with and separate from the opposing portion 50d. This makes it possible to control the gripping means 50 between a gripped state and a released grip state.

[0044] Furthermore, the support portion 50a is positioned below the contact portion 26b of the regulating stopper 26, that is, farther from the folding roller pair 22, so as not to hinder the positioning of the sheet that contacts the contact portion 26b, and so as to be able to grip the sheet that has come into contact with and been positioned by the contact portion 26b. In addition, the gripping portion 50c, which is the gripping portion that grips the sheet, is provided above the contact portion 26b, that is, closer to the folding roller pair 22. As a result, the sheet whose end comes into contact with the contact portion 26b can be securely gripped.

[0045] Furthermore, the folding processing device F of this embodiment is further equipped with a sheet side alignment mechanism for aligning and aligning the sides of sheets being transported into the intermediate tray 21. As shown in Figure 6, this sheet side alignment mechanism has a pair of sheet side alignment members 28a and 28b symmetrically arranged on both sides of the intermediate tray 21 in the sheet width direction (the direction along the sheet surface perpendicular to the sheet transport direction). Figure 6 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 closer to and further away from each other in the sheet width direction. When a sheet is transported into the intermediate 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.

[0046] <Department Head> Next, the control configuration of the drive system when folding the sheet will be explained. As shown in the block diagram of Figure 7, the control unit 60 receives detection signals from various detection sensors and various processing signals, and controls the drive of various drive motors, etc., according to the input signals. For example, it receives detection signals from the restrictor stopper HP sensor 61 which detects whether the restrictor stopper 26 is in the home position, the folding blade HP sensor 62 which detects whether the folding blade 23 is in the home position, and the pressing guide HP sensor 64 which detects whether the pressing guide member 30 (see Figure 11), which will be described later, is in the home position.

[0047] The control unit 60 then drives and controls the following in accordance with the flowcharts shown in Figures 8 to 10, based on the input signal: a regulating stopper motor 65 that drives the sheet lifting mechanism 27 to raise and lower the regulating stopper 26; a cam motor 66 that drives the cam member 25 for operating the blade carrier 24; and a folding roller motor 67 that drives and rotates the folding roller pair 22. Furthermore, the control unit 60 drives and controls the discharge roller motor 68 that drives and rotates the discharge roller pair 17b, which serves as a sheet conveying means; a pressing guide motor 69 for operating the pressing guide member 30; and a grip cam motor 70 that drives and rotates the grip cam 50e of the grip means 50.

[0048] The control unit 60 may be directly installed in the sheet processing apparatus B, or it may be installed in the main body of the image forming apparatus, and the control unit 60 may control the drive of the sheet processing apparatus B which is coupled with the image forming apparatus A.

[0049] <Tri-folding process> Figures 8 to 10 are flowcharts showing the operation procedures of each component when a sheet conveyed to the intermediate tray 21 is subjected to an inward tri-fold processing by the folding processing device F. Inward tri-fold processing is a process in which the sheet is folded in half by the first folding process, and then a second folding process is performed on the sheet at a different location than the first folding position, such that one end of the sheet folded in the first folding process is folded inward into the sheet folded in the second folding process, thereby creating a tri-fold.

[0050] In the folding processing device F of this embodiment, when performing the inner tri-fold process, the sheet that has been folded in half by the first folding process is guided by the pressing guide member 30, which is a direction changing member, to change the conveying direction of the sheet and ensure that it is reliably conveyed back to the intermediate tray 21.

[0051] The operation of the folding apparatus F of this embodiment when performing an inward tri-fold process will be described below with reference to the flowcharts in Figures 8 to 10 and the schematic cross-sectional diagrams in Figures 11 to 16 that show the movement of each part along the flow of the sheet S when the inward tri-fold process is performed.

[0052] When the folding process begins, the restricting stopper 26 moves to the "first folding position" (S1). This first folding position is the position where the first folding position of the sheet S faces the folding blade 23 when the leading edge E1 of the sheet conveyed to the intermediate tray 21 abuts against the contact portion 26b. At this time, the grip means 50 is in a released grip state as the grip cam 50e rotates, that is, the gripping portion 50c moves away from the opposing portion 50d, and the restricting stopper 26 is in a state where it can accept the sheet.

[0053] As shown in Figure 11(a), the intermediate tray 21 of this embodiment is formed at an angle to the vertical. When a sheet S is transported to the intermediate tray 21 (S2), the sheet S is transported with one side guided by the guide surface 21a that forms the intermediate tray 21, with the leading edge E1 of the sheet facing downwards and the rear edge E2 facing upwards, until the leading edge E1 of the sheet comes into contact with the contact portion 26b of the restricting stopper 26 and stops.

[0054] The folding blade 23 is positioned to project the sheet S toward the folding roller pair 22 from the side of the guide surface 21a of the intermediate tray 21. In other words, the guide surface 21a of the intermediate tray 21 and the folding roller pair 22 are positioned in corresponding positions with the sheet S in between.

[0055] When the folding process is executed, as shown in Figure 11(b), the cam motor 66 is driven to move the blade carrier 24 toward the folding roller pair 22, causing the folding blade 23 to contact the first folding position of the sheet S and protrude toward the nip portion 22c (S3). Simultaneously, the folding roller motor 67 and the discharge roller motor 68 are driven to rotate the folding roller pair 22 and the discharge roller pair 17b in the forward direction (S4). When pulse motors are used for each of the motors, the number of drive pulses is counted by a counter when the motors are driven. When DC motors are used for each of the motors, the slits of a code wheel (slit plate) mounted on the rotation axis of the motor are read by a sensor, and the number of slits is counted by a counter. The amount of sheet transported and the amount of protrusion of the folding blade 23 can be detected from the count value.

[0056] When the sheet S, which has been pushed out by the folding blade 23, reaches the nip portion 22c by the folding roller pair 22 and the sheet S is nipped (S5), the restricting stopper 26 starts to move to the "sheet receiving position" (S6). The sheet receiving position is the position where, when the conveyance of the folded sheet, which has undergone the first folding process by the folding roller pair 22, is switched back and conveyed to the intermediate tray 21 by the reversal of the folding roller pair 22, the sheet end E1 on the side furthest from the folding position comes into contact with the contact portion 26b of the restricting stopper 26 when the conveyance of the sheet stops.

[0057] As described above, if the restricting stopper 26 is moved towards the sheet during the folding operation, there is a risk that the folding position of the sheet will be misaligned with the folding blade 23 if the restricting stopper 26 comes into contact with the leading edge E1 of the sheet S that is protruding from the folding blade 23. However, in this embodiment, as described above, the restricting stopper 26 is moved to the receiving position after the sheet S has been nipped by the nip portion 22c, so even if the contact portion 26b of the restricting stopper 26 comes into contact with the sheet end portion E1, the folding position of the sheet will not be misaligned.

[0058] Alternatively, the movement of the restricting stopper 26 may be started before the sheet S reaches the nip portion 22c of the folding roller pair 22. In that case, the restricting stopper 26 must be moved at a sheet transport speed slower than the speed at which the folding blade 23 pushes the sheet out, so that the moving restricting stopper 26 does not come into contact with the leading edge E1 of the sheet S that is protruding towards the nip portion 22c.

[0059] When the folding blade 23, which has extended the sheet, 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, the rotation of the cam member 25 reverses the direction of travel and moves in the return direction, returning to the home position (S7).

[0060] As the folding blade 23 protrudes, as shown in Figure 12(a), the first folded portion of the sheet S that protrudes to the nip portion 22c of the folding roller pair 22 is pressed with a predetermined pressing force while being gripped and conveyed by the folding roller pair 22, and the folding process is performed. The sheet is then conveyed together with the folding roller pair 22 by the discharge roller pair 17b, which constitutes the sheet conveying means.

[0061] Next, in order to perform the second folding process, as shown in Figure 12(b), sheet transport is stopped when the rear end E2 of the sheet that has undergone the first folding process reaches a predetermined position (S8, S9). The predetermined position is the position where the rear end E2 of the sheet S on the side closer to the fold is transported into the sheet transport path 20 formed by the intermediate tray 21.

[0062] Above the folding blade 23, an L-shaped pressing guide member 30, which is a direction-changing member, is positioned so as to be rotatable around a pivot axis 30a. This pressing guide member 30 changes the orientation of the sheet in order to return the rear end E2 of the sheet S, which has been folded by the folding roller pair 22 and is being conveyed in a switchback manner, back to the intermediate tray 21. By rotating around the pivot axis 30a, it can move between a standby position that does not affect the change in the direction of sheet conveyance (see Figure 12(b)) and a guide position that guides the conveying sheet to change its orientation (see Figure 13(a)).

[0063] When the rear end E2 of the sheet reaches the predetermined position, it is preferable that the sheet has been transported to a position where the rear end E2 is below the pivot axis 30a (in the direction of the intermediate tray 21 where the front end E1 of the sheet is located). From this state, the folding roller pair 22 and the discharge roller pair 17b are driven in reverse to perform the switchback transport process. The rear end E2 of the sheet becomes the end that is folded inward into the sheet that is folded by the second folding process when the sheet is folded in three inward (hereinafter referred to as "folded end E2").

[0064] Then, when performing the switchback transport process, the L-shaped pressing guide member 30 (see Figure 12(b)), which is located in the home position (standby position), is rotated around the pivot axis 30a as shown in Figure 13(a) to move to the switchback guide position (S10). The rotation of the guide member 30 pushes the folded end E2 downward (towards the intermediate tray 21 where the sheet front end E1 is located). In this state, as shown in Figure 13(b), the gripping means 50 grips the sheet end E1 on the side furthest from the fold (S11). Then, as shown in Figure 14(a), the folding roller pair 22 and the discharge roller pair 17b are driven in reverse to transport the sheet in a switchback manner (S12), and the regulating stopper 26 is lowered in accordance with the speed to move to the "reversal position" (S13).

[0065] At this time, the sheet S undergoes its first folding process, and is transported with the fold facing the rear end and the folded end E2 facing the front end, so that it is open relative to the fold. In this state, as described above, the force of the folded fold trying to return to its original shape causes an opening force to act on the folded end E2, and the folded end E2, which is close to the fold and in an open state, is pressed against the guide surface 21a, causing increased frictional resistance as the sheet is transported while sliding. When the frictional resistance increases, the transported sheet becomes more prone to buckling, and the possibility of buckling increases in particular when the folded end E2 abuts against the boundary between the guide surface of the pressing guide member 30 and the guide surface 21a of the intermediate tray 21.

[0066] Therefore, in this embodiment, when the folded sheet is transported in a switchback manner, that is, when the folded edge is on the rear end side and the folded end E2 on the open side is on the front end side, the rotational peripheral speed of the folding roller pair 22 and the discharge roller pair 17b, and the downward speed of the regulating stopper 26 are controlled so that the transport speed V1 is below a certain speed. The transport speed V1 is a speed at which the frictional resistance does not increase even when the folded end E2 rubs against the guide surface 21a, and buckling does not occur, and in this embodiment it is set to 200 mm / s. As a result, the sheet is transported to the intermediate tray 21 without buckling.

[0067] In this embodiment, as described above, the regulating stopper 26 is moved while gripping the sheet S, so even if there is a transport load on the sheet, it is reliably transported to the inversion position.

[0068] As described above, the sheet, with its folded end E2 guided to the intermediate tray 21, descends as the restricting stopper 26, which grips the sheet end E1, moves to the "reversal position". The reversal position is the position where the sheet has been moved to, as shown in Figure 14(b), where the pressing guide member 30 can rotate without interfering with the sheet S. The amount of sheet transported to the reversal position is determined according to the sheet size and folding position.

[0069] Next, the restricting stopper 26 moves to the reverse position (S14), and after the restricting stopper 26 stops (S15), as shown in Figure 15(a), the gripping state of the sheet by the gripping means 50 is released (S16), and the pressing guide member 30 is returned to the standby position (S17). By releasing the gripping state as described above, even if the sheet's registration is disrupted when the sheet is transported in a switchback manner, the sheet will come into contact with the contact portion 26b due to its own weight, and the registration at the edge of the sheet is corrected.

[0070] Next, with the grip released, the restricting stopper 26 is moved to the "second folding position" (S18). This second folding position is the position where the second folding position of the sheet conveyed by the movement of the restricting stopper 26 faces the folding blade 23 (see Figure 15(b)).

[0071] When moving the sheet to the second folding position, as shown in FIGS. 15(a) and 15(b), the fold of the folded sheet is conveyed with the leading end side forward. At this time, since the end of the folded sheet is conveyed in the closing direction, the frictional resistance received from the conveyance path is smaller than when the fold is conveyed with the rear end side forward. Therefore, even if the conveyance speed of the sheet is increased, there is no risk of the sheet buckling. For this reason, in the present embodiment, the rising speed V2 of the regulation stopper 26 when conveying with the fold on the leading end side is set to 220 mm / s, which is faster than the speed V1 during the back-and-forth conveyance when conveying with the fold on the rear end side (V1 < V2). Thereby, it is possible to suppress a decrease in the productivity of the folding process.

[0072] Also, when the regulation stopper 26 is moved upward, since the gripping state by the gripping means 50 is released, the sheet end surely abuts against the abutting portion 26b. For this reason, for example, when performing a folding process on a plurality of sheets at once, when the sheet bundle passes through the nip portion 22c of the folding roller pair 22 during the back-and-forth conveyance after the first folding process, the inner sheet moves forward and is nip-released, so-called bundle misalignment and the like can be corrected.

[0073] Note that if the regulation stopper 26 that is moving upward with the gripping state of the gripping means 50 released as described above is suddenly stopped, the sheet whose end is abutting against the abutting portion 26b may shift due to inertia during deceleration toward the stop. Therefore, in the present embodiment, the gripping means 50 is operated to grip the sheet immediately before the regulation stopper 26 that is moving upward stops (S19 to S21). Thereby, the shift of the sheet when the regulation stopper​​​​​​ The folding roller motor 67 and the discharge roller motor 68 are driven in the forward direction in synchronization with the driving of the cam motor 66 (S24). As a result, the sheet S, which has been sent to the folding roller pair 22 by the protrusion of the folding blade 23, is folded in a state where the folded edge E2 of the sheet is folded inward into the sheet that is folded in the second folding process, as shown in Figure 16(b).

[0076] Then, the sheet S, which has been folded in three inwards as shown in Figures 17(a) and 17(b), is discharged onto the loading tray 17c to complete the folding process (S25, S26).

[0077] As described above, in this embodiment, by making the speed at which the folded sheet is transported with the fold facing the leading edge faster than the speed at which the folded sheet is transported with the fold facing the trailing edge, it is possible to prevent buckling of the folded sheet when it is transported in a switchback manner, while suppressing a decrease in the productivity of the folding process.

[0078] [Second Embodiment] In the embodiment described above, when a folded sheet is transported in a switchback manner, an example was shown in which the sheet is gripped by the gripping means 50 and the restricting stopper 26 is moved downward. However, the sheet may also be transported in a switchback manner without gripping it.

[0079] As described above, the intermediate tray 21 of this embodiment is formed at an angle to the vertical (see Figure 11(a)). Therefore, when the folded sheet is conveyed in a switchback manner and passes through the nip portion 22c of the folding roller pair 22, the sheet S, even if not gripped by the gripping means 50, is guided by the guide surface 21a forming the intermediate tray 21 and falls freely until the leading edge E1 of the sheet hits the contact portion 26b of the restricting stopper 26 and stops.

[0080] Therefore, in a configuration where the sheet is allowed to free-fall, when the sheet that has undergone the first folding process is transferred back to the intermediate tray 21, speed control only requires controlling the folding roller pair 22, making speed control easier.

[0081] [Third Embodiment] In the embodiment described above, the folding roller pair 22 was composed of a pair of circular rollers, and the folding roller pair 22 had the function of folding the sheet and the function of switching back and conveying the sheet. However, the means for folding the sheet and the means for switching back and conveying the sheet may be configured separately.

[0082] For example, in the sheet folding device shown in Figure 18, each folding roller 22a, 22b of the folding roller pair 22 is composed of a roller whose circumferential surface has a first roller surface (first circumferential surface) 22a2, 22b2 with a constant radius R1 around the rotation axis 22a1, 22b1, respectively, and a second roller surface (second circumferential surface) 22a3, 22b3 whose distance from the rotation axis of the rotation axis is smaller than the radius R1 of the first roller surface. In this embodiment, the first roller surfaces 22a2, 22b2 are formed of a rubber material or the like with a relatively high coefficient of friction, similar to the roller surfaces of rollers used in normal sheet conveying, and 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.

[0083] The rotation axes 22a1 and 22b1 of the folding rollers 22a and 22b are rotationally driven by a common drive motor or other driving means. This configuration allows the rotational positions to always be synchronized so that the first roller surfaces 22a2 and 22b2 and the second roller surfaces 22a3 and 22b3 face each other.

[0084] When the first roller surfaces 22a2 and 22b2 face each other, the nip portion 22c is pressed against it with a predetermined pressure, and a fold is created in the sheet S as it passes over this nip portion 22c. On the other hand, when the second roller surfaces 22a3 and 22b3 face each other, the nip portion 22c is configured to have a small gap without contact. Therefore, when the second roller surfaces 22a3 and 22b3 face each other, no pressure is applied to the sheet, and no conveying force is applied.

[0085] Then, during the sheet folding process, when the first roller surfaces 22a2 and 22b2 face each other, the sheet is passed through the nip section 22c to create a fold and is then sent to the discharge roller pair 17b. After the discharge roller pair 17b has nipped the sheet, the folding roller pair 22 is stopped with the second roller surfaces 22a3 and 22b3 facing each other, and the sheet is conveyed in a switchback manner by the discharge roller pair 17b.

[0086] As described above, in a configuration in which the sheet is transported in a switchback manner by the discharge roller pair 17b as a sheet transport means during the sheet folding process, by controlling the drive speed of the discharge roller pair 17b and the movement speed of the restricting stopper 26, the speed at which the sheet is transported with the fold towards the leading edge is faster than the speed at which the sheet is transported with the fold towards the rear edge, thereby preventing buckling of the sheet and suppressing a decrease in the productivity of the folding process. [Explanation of Symbols]

[0087] A...Image forming apparatus B...Sheet processing device S...Seat E1 ... Front of the seat E2 ... Folded end 17b... Discharge roller pair 20 ... Sheet transport path 21 ...Intermediate tray 21a... Guide surface 22 ...Folding roller pair 22a, 22b... Folding rollers 22c...Nip area 23…Folding blade 26... Regulatory stopper 30 ...Pressing guide member 50… Grip method 60 ... Control Unit

Claims

1. A sheet processing device 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, so that one end of the sheet folded by the first folding process is located inside the sheet folded by the second folding process, A conveying means for conveying a sheet; a position adjustment unit having a contact portion with which a downstream end portion of the sheet in a conveying direction of the sheet by the conveying unit comes into contact, and movable in the conveying direction and in a direction opposite to the conveying direction to adjust a position of the sheet; a protruding member that protrudes the sheet whose position in the transport direction has been adjusted by the position adjustment means; a pair of folding rollers that sandwich the sheet protruded by the protruding member and rotate in a first direction to fold the sheet, and that rotate in a second direction opposite to the first direction to return the folded sheet to the position adjustment means; a guide portion that guides the sheet returned to the position adjustment means by the pair of folding rollers that rotate in the second direction; a control unit that controls the pair of folding rollers so that a rotation speed of the pair of folding rollers in a first direction is faster than a rotation speed of the pair of folding rollers in the second direction; A sheet processing apparatus comprising:

2. 2. The sheet processing apparatus according to claim 1, wherein the control unit controls the pair of folding rollers so that the rotational speed of the pair of folding rollers when performing the second folding process is faster than the rotational speed of the pair of folding rollers when returning the sheet that has been subjected to the first folding process to the position adjustment means.

3. The sheet conveying device further includes a conveying roller pair provided downstream in a sheet conveying direction when the folding roller pair rotates in the first direction and capable of conveying the sheet together with the folding roller pair, the conveying roller pair is capable of conveying a sheet together with the folding roller pair rotating in the first direction by rotating in the first direction, and is capable of conveying a sheet together with the folding roller pair rotating in the second direction by rotating in the second direction, 3 . The sheet processing apparatus according to claim 1 , wherein the control unit controls the pair of conveying rollers so that a rotation speed of the pair of conveying rollers in the first direction is faster than a rotation speed of the pair of conveying rollers in the second direction.

4. A sheet processing device as described in any one of claims 1 to 3, characterized in that the control unit controls the position adjustment means so that the moving speed when the position adjustment means moves toward the upstream side in the conveying direction is faster than the moving speed when the position adjustment means moves toward the downstream side in the conveying direction.

5. The position adjustment means has a holding portion that holds a downstream end portion of the sheet in the conveying direction when adjusting a position of the sheet in the conveying direction, 5. The sheet processing apparatus according to claim 4, wherein when the sheet is returned to the position adjustment means by the pair of folding rollers rotating in the second direction, the holding portion holds the downstream end of the sheet.

6. A sheet processing device as described in Claim 5, characterized in that when the position adjustment means moves toward the upstream side in the conveying direction, the holding portion does not hold the downstream end portion of the sheet.

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