Sheet processing apparatus and image forming system

Abstract

To achieve accurate folding by ensuring movement of a folded sheet.SOLUTION: A sheet processing device executes first folding for a sheet, then executes second folding at a position different from that of a fold formed through the first folding, and executes folding so as to set one end of the sheet folded through the first folding inside the folded sheet. The first folding is executed for the sheet conveyed to an intermediate tray 21 by a folding roller pair 22, and control is executed so as to grip the sheet by gripping means 50 when the sheet subjected to the first folding is moved to a prescribed position of the intermediate tray 21 by moving a restriction stopper 26.SELECTED DRAWING: Figure 13

Description

[Technical field]

[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 technology]

[0002] Conventionally, there has been provided a sheet processing apparatus that folds a stack of sheets into a booklet as post-processing of sheets discharged from an image forming apparatus such as a copier, a printer, a facsimile, or a combination of these. For example, a sheet processing apparatus is known that folds a predetermined position of a sheet conveyed from an image forming apparatus to a sheet stacker with a butting plate, pushes the sheet into a nip between a pair of folding rollers, and folds the sheet in half while conveying it with the pair of folding rollers.

[0003] Among sheet processing devices that fold sheets, there are some that not only fold in half, but also fold the sheet in two different places and fold one edge of the sheet inside the folded sheet. In such devices, the sheet that has been folded the first time is switched back and returned to the stacker, and the sheet is folded a second time in a different position from the first time, resulting in an inner triple fold (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2012-56674 Summary of the Invention [Problem to be solved by the invention]

[0005] In the sheet folding device described in the above-mentioned Patent Document 1, after folding the sheet at the first folding position, the folded sheet is switched back and conveyed to a conveying path formed by guide members arranged at a predetermined interval, and the sheet is returned. At this time, a force is generated in the direction in which the edge of the sheet opens as the folded portion of the sheet tries to return to its original shape. For this reason, the edge of the sheet rubs against the guide member as it falls, but the frictional force at this time may prevent the sheet from falling smoothly.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a sheet processing device that can reliably move a folded sheet to perform folding processing with high accuracy, and an image forming system equipped with the same. [Means for solving the problem]

[0007] A representative configuration of the present invention for achieving the above object 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 folded sheet, the sheet processing apparatus includes a conveying path that guides a sheet conveyed in a predetermined conveying direction, position adjustment means having an abutment portion that an end of the sheet conveyed to the conveying path abuts against and that can move in the conveying direction and in a direction opposite to the conveying direction relative to the conveying path to adjust the position of the sheet, gripping means that can move integrally with the position adjustment means and can grip the sheet sent to the position adjustment means, a pushing member that pushes out the sheet whose position has been adjusted by the position adjustment means, and a sheet pushed out by the pushing member. Nip Nip and nipping the sheet in a predetermined direction. By rotating Before A pair of rotating bodies for performing folding processing on the sheet; The pair of rotors and the protruding member The sheet conveyed to the conveying path In contrast A first folding process is performed by the pair of rotating bodies, and the first folding process is Execution The folded sheet is when the pair of rotating bodies rotates in a direction opposite to the predetermined direction to return the sheet to the conveying path, the position adjustment means is moved to a position where the gripping means can grip the sheet before the sheet passes through the nip portion;The sheet is gripped by the gripping means. In this state, the folded sheet is moved to a predetermined position on the conveying path by the position adjustment means. and a control unit that controls the Effect of the Invention

[0008] In the present invention, when the folded sheet is returned to the conveying path, the sheet is gripped and moved, so that even if an opening force is applied to the folding position of the folded sheet, the sheet can be accurately moved to a specified position, resulting in a highly accurate folding process. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram of an overall configuration of an image forming system according to an embodiment of the present invention. [Diagram 2] FIG. 1 is an explanatory diagram of an overall configuration of a sheet processing apparatus in an image forming system. [Diagram 3] FIG. 3 is a cross-sectional view showing a folding processing device of the sheet processing device; [Figure 4] FIG. 2A is a cross-sectional view showing a gripping state of the gripping means, and FIG. 2B is a perspective view thereof. [Diagram 5] FIG. 2A is a cross-sectional view showing a gripping means in a released state, and FIG. 2B is a perspective view thereof. [Figure 6] FIG. 3 is a plan view showing the sheet folding device; [Figure 7] Block diagram of folding process control configuration [Figure 8] Flowchart showing the inner three-fold processing procedure [Figure 9] Flowchart showing the inner three-fold processing procedure [Figure 10] (a) and (b) are cross-sectional views illustrating the inward three-fold folding of a sheet. [Figure 11] (a) and (b) are cross-sectional views illustrating the inward three-fold folding of a sheet. [Figure 12] (a) and (b) are cross-sectional views illustrating the inward three-fold folding of a sheet. [Figure 13] (a) and (b) are cross-sectional views illustrating the inward three-fold folding of a sheet. [Figure 14](a) and (b) are cross-sectional views illustrating the inward three-fold folding of a sheet. [Figure 15] (a) and (b) are cross-sectional views illustrating the inward three-fold folding of a sheet. [Figure 16] (a) and (b) are cross-sectional views illustrating the inward three-fold folding of a sheet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [First embodiment] Next, a sheet processing apparatus according to a preferred embodiment of the present invention and an image forming system including the same will be described with reference to the drawings. Fig. 1 shows a schematic diagram of the overall configuration of an image forming system including a 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 attached thereto.

[0011] <Image forming device> The image forming apparatus A is made up of an image forming unit A1, a scanner unit A2, and a feeder unit A3. The image forming unit A1 includes a feeding section 2, an image forming section 3, a discharge section 4, and a data processing section 5 inside a device housing 1.

[0012] The feeding section 2 is composed of multiple cassette mechanisms 2a, 2b, and 2c that store image formation sheets of different sizes, and feeds out sheets of a size specified by a main body control unit (not shown) to a feeding path 2f. Each cassette mechanism 2a, 2b, and 2c is installed detachably from the feeding section 2, and each has a built-in separation mechanism that separates the internal sheets one by one and a feeding mechanism that feeds out the sheets. The feeding path 2f is provided with a conveying roller that feeds the sheets supplied from each cassette mechanism 2a, 2b, and 2c downstream, and a pair of registration rollers at the end of the path that aligns the leading edge of each sheet.

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

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

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

[0016] The scanner unit A2 includes 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 light reflected 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 to the image forming unit 3 as an electrical signal.

[0017] The scanner unit A2 also includes a traveling platen 7e to read sheets fed from the feeder unit A3. The feeder unit A3 is composed of a feed tray 8a on which original sheets are stacked, a feed path 8b that guides the original sheets fed from the feed tray 8a to the traveling platen 7e, and a discharge tray 8c that stores the original sheets that have passed 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 the traveling platen 7e.

[0018] <Sheet processing device> Next, the overall configuration of the sheet processing apparatus B that performs post-processing on the sheets sent from the image forming apparatus A will be described.

[0019] 2 is a diagram illustrating the configuration of the sheet processing apparatus B according to this embodiment. The sheet processing apparatus B includes an apparatus housing 11 having an inlet 10 for introducing a sheet 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 discharge port 4b of the image forming apparatus A.

[0020] The sheet processing apparatus B includes a sheet carry-in path 12 for transporting a sheet introduced from an entrance 10, a first discharge path 13a, a second discharge path 13b, and a third discharge path 13c branched off from the sheet carry-in path 12, a first path switching means 14a, and a second path switching means 14b. The first path switching means 14a and the second path switching means 14b are each formed of a flapper guide for changing the transport direction of a sheet transported through the sheet carry-in path 12.

[0021] The first path switching means 14a is switched by a driving means (not shown) between a mode in which the sheet from the carry-in entrance 10 is guided to the first discharge path 13a which transports the sheet horizontally as it is and the second discharge path 13b which transports the sheet downward, and a mode in which the sheet is guided to the third discharge path 13c which transports the sheet upward. The first discharge path 13a and the second discharge path 13b are connected so that a sheet once introduced into the first discharge path 13a can be switched back and transported to the second discharge path 13b by reversing the transport direction.

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

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

[0024] The first processing section B1 is a binding processing section that accumulates, collates, and binds a plurality of sheets discharged from a discharge port 16a at the downstream end of the first discharge path 13a in relation to the conveying direction of the sheets conveyed through the sheet carry-in path 12, and discharges the sheets to a stacking tray 16b provided outside the device housing 11. The first processing section B1 also includes a sheet conveying device 16c that conveys a sheet or a sheet stack, and a binding processing unit 16d that binds the sheet stack. A pair of discharge rollers 16e is provided at the downstream end of the first discharge path 13a to discharge the sheets from the discharge port 16a and to switch back and convey the sheets from the first discharge path 13a to the second discharge path 13b.

[0025] The second processing section B2 is a folding processing section that forms a sheet bundle from a plurality of sheets conveyed in a switchback manner from the second discharge path 13b, binds the sheet bundle, and then folds the sheet bundle. As described later, the second processing section B2 includes a folding processing device F that folds the conveyed sheets or sheet bundle, and a binding processing unit 17a that is disposed immediately upstream of the folding processing device F along the sheet conveying direction of the sheets conveyed to the second discharge path 13b and binds the sheet bundle. The folded sheet bundle is discharged by discharge rollers 17b to a stacking tray 17c provided outside the device housing 11.

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

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

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

[0029] <Folding device> On one side of the intermediate tray 21, a pair of folding rollers 22 as a pair of folding rotating bodies is disposed so as to face one surface of the sheet or sheet bundle loaded on the intermediate tray 21. The pair of folding rollers 22 is composed of a pair of folding rollers 22a, 22b whose roller surfaces are pressed against each other, and a nip portion 22c, which is a pressing portion, is disposed facing the intermediate tray 21. The folding rollers 22a, 22b are arranged in parallel with the intermediate tray 21 at approximately equal intervals on the upstream side and the downstream side along the conveying direction of the sheet conveyed from the upper upstream side to the lower downstream side on the intermediate tray 21. In the present invention, the rotating portion of the pair of folding rotating bodies is not limited to the folding rollers 22a, 22b of this embodiment, and may be constituted by a rotating belt or the like. Furthermore, the pair of folding rollers 22 may be constituted by continuously arranging a plurality of folding rollers (rotating bodies) in series along the axial direction of each of the folding rollers 22a, 22b.

[0030] A folding blade 23 serving as a protruding member is disposed on the opposite side of the folding roller pair 22 across the intermediate tray 21. The folding blade 23 is supported by a blade carrier 24 with its tip facing the nip portion 22c of the folding roller pair 22. The blade carrier 24 is provided so as to be movable by a moving means constituted by a cam member or the like in a direction crossing the intermediate tray 21 at a substantially right angle, that is, in a direction intersecting the conveying direction of the sheet conveyed from the second discharge path 13b to the intermediate tray 21.

[0031] 3, i.e., in the axial direction of the folding rollers, a pair of cam members 25 (only one of which is shown in the figure) consisting of mirror-symmetric eccentric cams are provided at opposing positions on both sides of the blade carrier 24. The cam member 25 rotates around a rotation shaft 25a provided at the eccentric position by a driving means such as a driving motor. The cam member 25 has a cam groove 25b formed along its outer circumferential edge.

[0032] The blade carrier 24 is provided with a cam pin 24c serving as a cam follower, which is slidably fitted into the cam groove 25b.

[0033] When the drive motor rotates the cam member 25, the blade carrier 24 reciprocates in a direction approaching or receding from the intermediate tray 21. As a result, as shown in Fig. 3, between an initial position where the tip of the folding blade 23 does not enter the sheet conveying path formed by the intermediate tray 21 and a maximum protruding position where the tip is sandwiched between the nip portion 22c of the pair of folding rollers 22, the folding blade 23 can be freely moved forward and backward in a straight line along a protruding path connecting these two positions.

[0034] A regulating stopper 26 is disposed at the lower end of the intermediate tray 21. The regulating stopper 26 serves as a position adjusting means for adjusting and positioning the sheet in the sheet conveying path by contacting the leading edge of the conveyed sheet in the conveying direction. The regulating stopper 26 is provided so as to be movable up and down along the intermediate tray 21 by a sheet lifting mechanism 27.

[0035] The sheet lifting mechanism 27 of this embodiment is a conveyor belt mechanism that is arranged below the blade carrier 24 when the tip of the folding blade 23 is in an initial position behind the intermediate tray 21, which is a position where the tip of the folding blade 23 does not enter the sheet conveying path formed by the intermediate tray 21, and is composed of a pair of pulleys 27a, 27b arranged near the upper and lower ends along the intermediate tray 21, and a transmission belt 27c wound around both pulleys. The regulating stopper 26 is fixed on the transmission belt 27c. By rotating the drive pulley 27a or 27b on the driving side by a driving means such as a driving motor, the regulating stopper 26 moves up and down between the lower end position shown in FIG. 3 and a desired height position, thereby moving the sheet or sheet stack along the intermediate tray 21 and positioning it at the desired height.

[0036] As described above, the regulating stopper 26 can move up and down along the intermediate tray 21, and the gripping means 50 is attached to the regulating stopper 26, so that the regulating stopper 26 can move up and down integrally with the regulating stopper 26. The gripping means 50 grips the sheet conveyed to the intermediate tray 21, and ensures the movement of the sheet accompanying the movement of the regulating stopper 26.

[0037] 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 is able to grip a sheet, 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 sheet, and (b) is a perspective view thereof.

[0038] As shown in Fig. 4, the gripping means 50 is attached to the regulating stopper 26. The regulating stopper 26 has a contact portion 26b on a base portion 26a that is movable along the guide surface 21a of the intermediate tray 21 by the drive transmission from the transmission belt 27c. The contact portion 26b positions the sheet when the lower end of the sheet conveyed to the intermediate tray 21 comes into contact with the contact portion 26b, and during folding processing, the position of the contact portion 26b is adjusted to move the sheet to the folding position. The contact portion 26b is continuously formed with a standing portion 26c bent at a right angle, so that the sheet that comes into contact with the contact portion 26b can be stored without falling off.

[0039] The gripping means 50 is attached to the base 26a, and moves integrally with the base 26a when the base 26a moves along the guide surface 21a. The gripping means 50 has a standing portion 50b formed integrally with a support portion 50a attached to the base 26a so as to be slidable in a direction along the thickness of the sheet perpendicular to the conveying direction of the sheet conveyed to the intermediate tray 21, and a gripping portion 50c is formed on the inner side of the standing portion 50b. Furthermore, at a position opposite to the gripping portion 50c across the sheet conveying path to the intermediate tray 21, a facing portion 50d is provided integrally with the base 26a.

[0040] An elastic member (not shown) such as a spring is attached between the base 26a and the support portion 50a, and the standing portion 50b is always biased toward the facing portion 50d. As a result, the gripping portion 50c is normally pressed against the facing portion 50d, and is in a state in which it can grip a sheet conveyed to the intermediate tray 21, that is, in a so-called gripping state (see FIGS. 4(a) and (b)).

[0041] As shown in Fig. 5(a), the base 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 therewith slides in the direction of the arrow shown in Fig. 5(a), and the gripping portion 50c abuts against and separates from the opposing portion 50d. This makes it possible to control the grip means between a grip state and a released grip state.

[0042] The support portion 50a is disposed below the contact portion 26b of the regulating stopper 26, i.e., at a position far from the pair of folding rollers 22, so that the support portion 50a can grip the sheet that is positioned by contacting the contact portion 26b without interfering with the positioning of the sheet that contacts the contact portion 26b. The gripping portion 50c that is a gripping portion that grips the sheet is disposed above the contact portion 26b, i.e., at a position close to the pair of folding rollers 22. Therefore, the sheet whose end portion contacts the contact portion 26b can be securely gripped.

[0043] Furthermore, the folding device F of this embodiment further includes a sheet side alignment mechanism for aligning the sides of the sheet conveyed to the intermediate tray 21. As shown in FIG. 6, this sheet side alignment mechanism has a pair of sheet side alignment members 28a, 28b arranged symmetrically on both sides of the sheet width direction (direction along the surface of the sheet perpendicular to the sheet conveying direction) of the intermediate tray 21. Note that FIG. 6 is a schematic plan view of the folding device F seen from above. The sheet side alignment members 28a, 28b are held movably so that they can relatively approach and move away from each other in the sheet width direction. For a sheet conveyed to the intermediate tray 21 and whose leading edge abuts against the regulating stopper 26, the sheet side alignment members 28a, 28b are moved to align the sheet width direction position.

[0044] <Control Unit> Next, the control configuration of the drive system when folding a sheet will be described. As shown in the block diagram of Fig. 7, the control unit 60 inputs detection signals and various processing signals from various detection sensors, and controls the driving of various drive motors and the like in response to the input signals. For example, the control unit 60 inputs detection signals from a regulating stopper HP sensor 61 that detects whether the regulating stopper 26 is in the home position, a folding blade HP sensor 62 that detects whether the folding blade 23 is in the home position, a pressing guide HP sensor 64 that detects whether the pressing guide member 30 (see Fig. 10) described later is in the home position, and the like.

[0045] 8 and 9 in response to the input signal, the control unit 60 drives and controls a restriction stopper motor 65 that drives the sheet lifting mechanism 27 that lifts and lowers the restriction 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 a discharge roller motor 68 that drives and rotates the discharge roller 17b that serves as a sheet conveying means, a pressing guide motor 69 that operates the pressing guide member 30, and a grip cam motor 70 that drives and rotates the grip cam 50e of the gripping means 50.

[0046] <Folding in three> 8 and 9 are flow charts showing the operation procedure of each member when folding a sheet conveyed to the intermediate tray 21 in three by the folding device F. Note that the inward three-fold process refers to a process in which a sheet is folded in two in a first folding process, and then folded a second time at a position different from the initial folding position, so that one edge of the sheet folded in the first folding process is folded inside the sheet to be folded in the second folding process, thereby folding the sheet in three.

[0047] In the folding processing device F of this embodiment, when performing an inner triple fold process, the sheet folded in half by the first folding process is gripped by the gripping means and the regulating stopper 26 is moved to the intermediate tray 21, thereby reliably moving the sheet to the specified position.

[0048] The operation of the folding device F of this embodiment when performing an inner triple fold process will be described below with reference to the flowcharts in FIGS. 8 and 9 and the cross-sectional schematic diagrams in FIGS. 10 to 16 showing the movement of each part along the flow of the sheet S when the inner triple fold process is performed.

[0049] When the folding process is started, the regulating stopper 26 moves to the "first folding process position" (S1). This first folding process position is a position where the first folding position of the sheet S faces the folding blade 23 when the leading edge E1 of the conveyed sheet abuts against the abutting portion 26b. At this time, the gripping cam 50e of the gripping means 50 rotates to release the grip, i.e., the gripping portion 50c is separated from the opposing portion 50d, and the regulating stopper 26 is in a state where it can receive the sheet.

[0050] In this embodiment, the intermediate tray 21 is formed at an angle to the vertical direction, as shown in Figure 10 (a), and when a sheet S is transported to the intermediate tray 21 (S2), one side of the sheet S is guided by the guide surface 21a that forms the intermediate tray 21, and the sheet S is transported so that it falls with the sheet leading edge E1 facing down and the sheet trailing edge E2 facing up, and the sheet leading edge E1 hits the abutment portion 26b of the regulating stopper 26 and stops.

[0051] The folding blade 23 is disposed at a position where it protrudes the sheet S from the side of the guide surface 21a of the intermediate tray 21 toward the pair of folding rollers 22. In other words, the guide surface 21a of the intermediate tray 21 and the pair of folding rollers 22 are disposed at corresponding positions with the sheet S sandwiched therebetween.

[0052] When the folding process is performed, as shown in FIG. 10(b), the cam motor 66 is driven to move the blade carrier 24 toward the pair of folding rollers 22, and the folding blade 23 abuts on the first folding position of the sheet S and protrudes into the nip portion 22c (S3). At the same time, the folding roller motor 67 and the discharge roller motor 68 are driven to rotate the pair of folding rollers 22 and the discharge roller 17b in the forward direction (S4). When a pulse motor is used for each of the motors, the number of drive pulses is counted by a counter when the motor is driven. When a DC motor is used for each of the motors, the slits of a code wheel (slit plate) attached to the rotation shaft of the motor are read by a sensor, and the number is counted by a counter. The count value makes it possible to detect the conveyance amount of the sheet, the amount of sheet protrusion, etc.

[0053] When the sheet S protruded by the folding blade 23 reaches the nip portion 22c by the pair of folding rollers 22 and is nipped (S5), the regulating stopper 26 starts to move to the "receiving position" (S6). The receiving position is a position where the sheet end E1 on the side farther from the folding position can abut against the abutting portion 26b of the regulating stopper 26 just before passing through the nip portion 22c of the pair of folding rollers 22 when the sheet that has been subjected to the first folding process by the pair of folding rollers 22 is switched back to the intermediate tray 21 by the pair of folding rollers 22 rotating in the reverse direction.

[0054] As described above, when the regulating stopper 26 is moved in a direction approaching the sheet during the folding operation, if the regulating stopper 26 comes into contact with the sheet end protruding by the folding blade 23, the folding position of the sheet may be shifted relative to the folding blade 23. However, in this embodiment, as described above, the regulating stopper 26 is moved to the receiving position after the sheet S is nipped in the nip portion 22c, so that even if the regulating stopper 26 comes into contact with the sheet end, the folding position of the sheet will not be shifted.

[0055] The movement of the regulating stopper 26 may be started before the sheet reaches the nip portion 22c of the pair of folding rollers 22. In that case, it is necessary to move the regulating stopper 26 at a sheet conveying speed slower than the speed at which the sheet is protruded by the folding blade 23 so that the moving regulating stopper 26 does not abut on the sheet end protruding into the nip portion 22c.

[0056] After the folding blade 23 protrudes the sheet, the first fold of the sheet S is protruded a predetermined amount up to the nip portion 22c of the pair of folding rollers 22, and then the direction of travel is reversed by the rotation of the cam member 25, and the blade moves in the return direction to the home position (S7).

[0057] 11(a), the sheet S protruded into the nip portion 22c where the first roller surfaces 22a2, 22b2 of the pair of folding rollers 22 are in pressure contact with each other is pressed by a predetermined pressure while being sandwiched and conveyed by the pair of folding rollers 22, and is then conveyed by the discharge roller 17b which constitutes the sheet conveying means together with the pair of folding rollers 22. At this time, the regulating stopper 26 has completed its movement to the receiving position.

[0058] Next, in order to perform the second folding process, as shown in FIG. 11(b), the sheet conveyance is stopped when the sheet trailing end E2, which has been folded the first time, reaches a predetermined position (S8, S9). The predetermined position is a position where the sheet trailing end E2, which is closer to the fold, is conveyed into the sheet conveyance path formed by the intermediate tray 21. Above the folding blade 23, an L-shaped pressing guide member 30 is arranged rotatably about a rotating shaft 30a. It is preferable that the sheet conveyance is stopped when the sheet trailing end E2 reaches the predetermined position when the sheet is conveyed to a position where the sheet trailing end E2 is below the rotating shaft 30a (toward the intermediate tray 21 where the sheet leading end E1 is located). From this state, the folding roller pair 22 and the discharge roller 17b are driven in the reverse direction to perform the switchback conveyance process. The sheet trailing end E2 becomes an end (hereinafter referred to as a "folding end") that is folded inside the sheet folded by the second folding process when the sheet is folded in three.

[0059] When the switchback conveying process is performed, the L-shaped pressing guide member 30 (see FIG. 11(b)), which is located at the home position, is rotated about the rotating shaft 30a as the center, as shown in FIG. 12(a) (S10). The rotation of the guide member 30 causes the folding end E2 to be pressed downward (toward the intermediate tray 21 where the sheet leading end E1 is located). In this state, when the folding roller pair 22 and the discharge roller 17b are driven in the reverse direction (S11), the sheet S is switched back and conveyed to the intermediate tray 21. At this time, the folding end E2 of the sheet is guided by the guide surface of the pressing guide member 30 and conveyed to the intermediate tray 21 (see FIGS. 12(a) and 12(b)).

[0060] Then, as shown in Fig. 13(a), the pair of folding rollers 22 rotate to convey the sheet S until the fold of the sheet S passes through the nip portion 22c (S12). When the sheet S passes through the nip portion 22c, the sheet end portion E1 is pressed against the contact portion 26b of the regulating stopper 26 waiting at the receiving position as described above, and the sheet end portion E1 is abutted and corrected (registered) along the surface of the contact portion 26b. In this embodiment, the conveyance amount from when the sheet end portion E1 conveyed by the pair of folding rollers 22 abuts against the contact portion 26b until the sheet passes through the nip portion 22c is as small as about 1 mm to 3 mm, and the sheet end portion does not buckle.

[0061] As described above, after a short time has elapsed since the sheet S left the nip portion 22c, the grip cam 50e is rotated to put the gripping means into a gripping state (S13). Gripping the sheet S after a predetermined time has elapsed since the sheet S left the nip portion 22c is more effective when multiple sheets are simultaneously folded, rather than folding one sheet as in this embodiment. When multiple sheets are folded as a bundle, a shift corresponding to the thickness of the sheet bundle occurs at the positions of the folded portions (creases) of the inner sheet and the outer sheet. Then, when the sheet bundle is switched back and conveyed in the opposite direction to the direction in which the first folding process is performed, the crease of the sheet that is on the inner side of the folded sheet bundle leaves the nip portion 22c of the folding roller pair 22 earlier than the crease of the sheet that is on the outer side. Then, the sheet bundle may be separated and conveyed in the direction of the regulating stopper 26. At that time, as described above, by receiving the sheet while keeping the grip released for a predetermined time, the end of the sheet abuts against the stopped abutment portion 26b, and the abutment correction of the multiple sheets can be performed. The predetermined time period may be as short as one second or less.

[0062] After the sheet S is gripped as described above, the regulating stopper 26 is lowered to the "reversal position" (S14) as shown in Fig. 13(b). The reversal position is a position where the sheet is moved to a position where the pressing guide member 30 can rotate without interfering with the sheet S as shown in Fig. 14(a). The amount of sheet transport to the reversal position is determined according to the sheet size and folding position.

[0063] When the sheet that has passed through the nip portion 22c of the pair of folding rollers 22 is returned to the inversion position of the intermediate tray 21 by free fall, the sheet that has been folded in half has a shape similar to the barb of a fishing hook up to the sheet end E2 on the closer side from the fold, which may cause a transport load and prevent the sheet from moving smoothly. However, in this embodiment, as described above, the regulating stopper 26 is moved while gripping the sheet S, so that the sheet is reliably transported to the inversion position even if there is a transport load on the sheet.

[0064] In this embodiment, as described above, the regulating stopper 26 is lowered after the folded sheet that has been folded once passes through the nip portion 22c of the pair of folding rollers 22. However, it is also possible to have the regulating stopper 26 wait at a position where the sheet end E1 abuts against the abutting portion 26b before the folded sheet passes through the nip portion 22c, and to grip the sheet with the gripping means 50 before the folded sheet passes through the nip portion 22c, and to lower the regulating stopper 26. In this case, the sheet moving speed by the regulating stopper 26 is controlled to be slower than the sheet conveying speed by the pair of folding rollers 22. By controlling the speed in this manner, the sheet is not pulled even when the sheet is moved by both the pair of folding rollers 22 and the regulating stopper 26.

[0065] Next, after the regulating stopper 26 moves to the reversing position, as shown in Fig. 14(b), the sheet grip by the gripping means is released (S15), and the pressing guide member 30 is returned to the retreated position (home position) (S16). By releasing the sheet grip as described above, even if the registration is lost when the sheet is pulled back, the sheet comes into contact with the contact portion 26b due to its own weight, and the abutment correction of the sheet end is performed.

[0066] After the grip is released once as described above, the sheet is gripped by the gripping means 50 (S17), and the regulating stopper 26 is moved to the "second folding position" (S18). This second folding position is a position where the second folding position of the sheet conveyed by the movement of the regulating stopper 26 faces the folding blade 23 (see FIG. 15(a)). If the regulating stopper 26 is raised with the sheet S abutting against the abutting portion 26b, the sheet may bounce at the moment the regulating stopper 26 stops, causing the registration to be lost; however, in this embodiment, the sheet is moved to the second folding position while being gripped, so there is no risk of the registration being lost.

[0067] In this embodiment, the sheet is gripped before the regulating stopper 26 is moved to the second folding processing position, but the same effect can be obtained by gripping the sheet while the regulating stopper 26 is rising.

[0068] After the regulating stopper 26 moves to the second folding processing position, the sheet grip by the gripping means 50 is released (S19), and the cam motor 66 is driven to operate the folding blade 23 again, so as to push the sheet S into the nip portion of the folding roller pair 22 (S20), as shown in Figure 15(b).

[0069] 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 (S21). As a result, the sheet S sent to the pair of folding rollers 22 by the protrusion of the folding blade 23 is folded in a state where the folded end E2 of the sheet is folded inside the sheet to be folded in the second folding process, as shown in FIGS. 16(a) and 16(b).

[0070] Then, the sheet S folded in three as described above is discharged onto the stacking tray 17c, and the folding process is completed (S22, S23).

[0071] As described above, in this embodiment, when the folded sheet S is returned to the intermediate tray 21, the sheet can be gripped and moved to accurately move the sheet to a predetermined position even if an opening force acts on the folded sheet at the folding position. In addition, when moving the sheet, moving it in a gripped state can suppress loss of registration. [Explanation of symbols]

[0072] A … Image forming device F … Folding device S...Seat 17b ... Discharge roller 21 … Middle tray 21a … Guide surface 22 ... Folding roller pair 22a, 22b ... Folding rollers 22c...Nip section 23 … Folding blade 24 ... Blade carrier 25 ... Cam member 26 ...Regulation stopper 26a...Base 26b...Abutting part 26c…Standing part 30 ... Pressure guide member 50 … Grip means 50a...Support part 50b…Standing part 50c...gripping part 50d...Opposing part 50e ... Grip Cam 60 ... Control section 100 ... Image forming system

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 folded sheet, a conveying path that guides a sheet conveyed in a predetermined conveying direction; a position adjustment unit having a contact portion with which an end portion of the sheet conveyed to the conveying path comes into contact, and capable of moving relative to the conveying path in the conveying direction and in a direction opposite to the conveying direction to adjust a position of the sheet; a gripping means that is movable integrally with the position adjustment means and is capable of gripping the sheet fed to the position adjustment means; a protruding member for protruding the sheet whose position has been adjusted by the position adjustment means; a pair of rotating bodies having a nipping portion for nipping the sheet protruded by the protruding member, and rotating in a predetermined direction while nipping the sheet to perform a folding process on the sheet; a control unit that, when a first folding process is performed by the pair of rotating bodies on the sheet transported to the transport path by the pair of rotating bodies and the push-out member, and the folded sheet after the first folding process is returned to the transport path by the pair of rotating bodies rotating in a direction opposite to a previous predetermined direction, moves the position adjustment means to a position where the gripping means can grip the sheet before the sheet passes through the nip portion, and controls the position adjustment means to move the folded sheet to a predetermined position on the transport path with the sheet gripped by the gripping means; A sheet processing apparatus comprising:

2. The sheet processing device according to claim 1, characterized in that, when the folded sheet that has been folded the first time is returned to the conveying path by the pair of rotating bodies rotating in the opposite direction, the control unit controls the position adjustment means to move to a position where the end of the sheet can abut against the abutment portion before the sheet passes through the nip portion.

3. 3. The sheet processing apparatus according to claim 1, wherein when the pair of rotating bodies rotates in the opposite direction to return the folded sheet that has undergone the first folding process to the conveying path, the control unit controls the position adjustment means to move to a position where the gripping means can grip the sheet before the sheet passes through the nip portion, and controls the gripping means to grip the sheet after the sheet passes through the nip portion.

4. 2. The sheet processing apparatus according to claim 1, wherein the control unit controls the position adjustment means to move at a speed slower than the sheet transport speed by the pair of rotating bodies when the position adjustment means moves the folded sheet that has been folded a first time in a direction returning it to the transport path.

5. 5. The sheet processing device according to claim 1, wherein the control unit controls the gripping means to grip the sheet when the position adjustment means moves the folded sheet that has been folded the first time from a predetermined position on the conveying path to a second folding position.

6. 6. The sheet processing apparatus according to claim 5, wherein the control unit controls the gripping means to release the grip on the sheet after the position adjustment means moves the sheet to the second folding processing position.

7. an image forming apparatus for forming an image on a sheet; a sheet processing device that performs folding processing on the sheet sent from the image forming device; having 7. An image forming system, comprising: the sheet processing apparatus according to claim 1.

Images