Sheet processing apparatus and image forming system

Abstract

To prevent a first fold position from shifting or collapsing when performing multiple fold processes on a sheet.SOLUTION: A sheet processing device is configured to apply a first fold process to a sheet conveyed on a conveying path by means of a pair of rotating bodies 22, return the sheet to the conveying path while opening the first fold of the first folded processed sheet, apply a second folding process to the folded processed sheet returned to the conveying path by means of the pair of rotating bodies, and discharge the sheet in a state with the first fold open.SELECTED DRAWING: Figure 10

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 machine thereof. 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 perform folding processes on sheets, there are sheet processing devices that not only fold in half, but also fold the sheet in two different places and perform an inner triple fold process in which one edge of the sheet is on the inside of the folded sheet (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2011-184140 [Patent Document 2] Patent Publication No. 2012-56674 Summary of the Invention [Problem to be solved by the invention]

[0005] Although the sheet processing devices described in Patent Document 1 and Patent Document 2 have different configurations, both devices disclose a technique for folding a sheet in three. However, in these devices, the length of a sheet that has been folded in three in the sheet transport direction appears to be about one-third the length of the sheet before folding. Therefore, as shown in Fig. 19, when sheets S that have been folded in three are discharged and stacked on stacking tray 200, they become unstable, and there is a risk that discharge alignment will deteriorate or the stack of stacked sheets will collapse.

[0006] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a sheet processing apparatus that improves the alignment of sheets discharged and stacked on a stacking tray while performing folding processing, and an image forming system including the same. [Means for solving the problem]

[0007] A representative configuration according to the present invention for achieving the above object includes a pair of folding rollers that are rotatable in a first direction and a second direction opposite to the first direction and rotate in the first direction to pinch a sheet to form a crease in the sheet, a pushing means that pushes the sheet toward the nip of the pair of folding rollers, an adjustment means that adjusts the position of the sheet in a direction intersecting the pushing direction of the pushing means, a stacking means that stacks the sheet on which the crease has been formed by the pair of folding rollers, and a sheet pushing means that pushes the sheet, the position of which has been adjusted by the adjustment means, and a stacking means that rotates in the first direction. The above a first folding process of forming a first fold by sandwiching the sheet with a pair of folding rollers; The pair of folding rollers rotates in the second direction while opening the first fold. In the opposite direction to the protruding direction The sheet on which the first folding process has been performed is Delivery The transport process and , A position different from the first fold is protruded by the protruding means. The position is adjusted by the adjusting means. but The sheet in the adjusted state is pushed out by the pushing means, and the sheet is folded by the pair of folding rollers rotating in the first direction. The transport process has been performed a second folding process for forming a second fold by sandwiching the sheet; is open and The second fold In a state of being folded by and a control unit that executes a discharge process for discharging the sheet toward the stacking unit. Effect of the Invention

[0008] In the present invention, when folding a sheet in two different places, a crease is made in the first place and a folding process is performed in the second place. As a result, a sheet that has been folded in two different places is discharged from the device with a part of the sheet folded inward because only a crease is made in one place. Therefore, the creases of the newly discharged sheets that have been folded and discharged are piled up following the creases of the already discharged sheets, so that the alignment of the discharged sheets is favorable. [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. 3 is a plan view showing the sheet folding device; [Diagram 5] FIG. 13 is an explanatory diagram of a pressing force adjustment configuration of a pair of folding rollers; [Figure 6] Block diagram of folding process control configuration [Figure 7] Flowchart showing the tri-folding process [Figure 8] 1A and 1B are cross-sectional explanatory views of a sheet opening and folding operation according to the first embodiment; [Figure 9] 1A and 1B are cross-sectional explanatory views of a sheet opening and folding operation according to the first embodiment; [Figure 10] 1A and 1B are cross-sectional explanatory views of a sheet opening and folding operation according to the first embodiment; [Figure 11] FIG. 1A is a perspective view of a sheet that has been opened and folded according to the first embodiment, and FIG. [Figure 12] A perspective view of a sheet folded in three [Figure 13] (a)(b) Cross-sectional view of the folding operation of a sheet folded in three [Figure 14] 1A and 1B are cross-sectional views illustrating the sheet opening and folding operation according to the second embodiment. [Figure 15] 1A and 1B are cross-sectional views illustrating the sheet opening and folding operation according to the second embodiment. [Figure 16] 1A and 1B are cross-sectional views illustrating the sheet opening and folding operation according to the second embodiment. [Figure 17] FIG. 11 is a perspective view of a sheet that has been opened and folded according to a second embodiment; [Figure 18] FIG. 1 is an explanatory diagram of a pair of folding rollers having peripheral surfaces with different radii [Figure 19] Stacking diagram of sheets folded in three 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] <Overall configuration of image forming apparatus> The image forming apparatus A is made up of an image forming unit A1, a scanner unit A2, and a feeder unit A3. The image forming unit A1 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 a transfer bias is applied from the transfer charger 3d to transfer the toner image formed on the photosensitive drum 3a onto the sheet. The sheet onto which the toner image has been transferred is heated and pressurized as it passes through the fixing 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] <Overall configuration of 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 stacks a sheet or a plurality of sheets conveyed in a switchback manner from the second discharge path 13b to form a sheet bundle, binds the sheet or the sheet bundle, and then folds it. As described later, the second processing section B2 includes a folding processing section F that folds the conveyed sheet or sheet bundle, and a binding processing unit 17a that is disposed immediately upstream of the folding processing section F along the sheet conveying direction of the sheets conveyed to the second discharge path 13b and binds the sheet bundle. The folded sheet or sheet bundle is discharged by the 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] <Folding device>

[0028] 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 in half the sheet bundle that is conveyed from the second discharge path 13b and that is a set of accumulated sheets or a set of accumulated sheets, 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.

[0029] 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.

[0030] On one side of the intermediate tray 21 in the thickness direction of the sheet, 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 stack transported to the intermediate tray 21. The pair of folding rollers 22 is composed of a pair of folding rollers 22a, 22b whose circular 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 transport direction of the sheet transported 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.

[0031] The pair of folding rollers 22 is formed of a rubber material or the like having a relatively high friction coefficient, similar to the roller surfaces of rollers used for normal sheet conveyance and the like.

[0032] A folding blade 23 is disposed on the opposite side of the folding roller pair 22 across the intermediate tray 21 as a biasing means for biasing the sheet toward the folding roller pair 22. 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.

[0033] 3, i.e., in the axial direction of the folding rollers, a pair of cam members 25 (only one of which is shown in the figure) consisting of mirror-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.

[0034] 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.

[0035] 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. This allows the folding blade 23 to move freely back and forth in a straight line along a protruding path connecting an initial position where the tip of the folding blade 23 does not enter the sheet conveying path formed by the guide surface 21a of 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 as shown in FIG.

[0036] A regulating stopper 26 is disposed at the lower end of the intermediate tray 21, which serves as a position adjustment means that abuts against the leading edge of the conveyed sheet in the conveying direction to regulate it and moves in the sheet conveying path in the conveying direction and in the direction opposite to the conveying direction to adjust the position of the sheet with respect to the intermediate tray 21. 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.

[0037] 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.

[0038] The folding device F of this embodiment further includes a sheet side alignment mechanism for aligning the side of the sheet conveyed to the intermediate tray 21, which is the edge of the sheet in the width direction intersecting with the sheet conveying direction. As shown in FIG. 4, 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 perpendicular to the sheet conveying direction) of the intermediate tray 21. FIG. 4 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. When a sheet is conveyed to the intermediate tray 21 and the leading edge of the sheet hits the regulating stopper 26, the sheet side alignment members 28a, 28b are moved to align the sheet width direction.

[0039] As described above, the sheet biased by the folding blade 23 is pressed by passing it through the nip portion 22c of the pair of folding rollers 22 to perform the folding process. However, the folding processing device F of this embodiment is configured so that the distance between the rotating shafts 22a1, 22b1 of the folding rollers 22a, 22b can be changed, and the pressing force of the nip portion 22c can be adjusted by changing the distance by driving a pressure changing motor.

[0040] 5, in the pressure changing means capable of changing the pressing force of nip portion 22c in this embodiment, folding rollers 22a, 22b are rotatably attached to one end of arm members 90a, 90b, respectively, and the other end of arm members 90a, 90b is supported by a common pivot point 91. The folding rollers 22a, 22b are pressed against each other by tension springs 92 engaged with arm members 90a, 90b, so as to apply a predetermined pressing force to the sheet passing through roller nip portion 22c.

[0041] Meanwhile, an elliptical eccentric cam 93 is attached near the pivot fulcrum 91 so as to be rotatable by the pressure changing motor 69, and each of the arm members 90a, 90b is provided with a pin 95a, 95b which can engage with the major diameter portion of the eccentric cam 93. When the eccentric cam 93 is not in contact with the pin 95a, 95b, the folding rollers 22a, 22b are in pressure contact, but when the eccentric cam 93 is rotated, it engages with the pin 95a, 95b and pushes them out. As a result, the arm members 90a, 90b rotate about the pivot fulcrum 91, and the folding rollers 22a, 22b move apart.

[0042] <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. 6, the control unit 60 inputs detection signals and various processing signals from various detection sensors, and controls the driving of various drive motors, etc. 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, an eccentric cam HP sensor 63 that detects the home position of the eccentric cam 93, etc.

[0043] 7 in accordance with 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 to operate 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, and a pressure changing motor 69 that can move the rotation shafts 22a1, 22b1 of the folding rollers 22a, 22b.

[0044] <Folding operation> 7 is a flowchart showing the operation procedure of each component when a sheet conveyed to the intermediate tray 21 is folded in three by the folding device F. The folding in three process involves folding a sheet in two in a first folding process, and then folding the sheet a second time at a position different from the initial folding position. Then, an inner three-fold is achieved by folding one end of the sheet folded in the first folding process into the sheet to be folded in the second folding process.

[0045] Here, as described above, when folding in three, if the sheets are discharged and stacked in the state where they are folded in three, the sheets will become unstable. Therefore, in the folding processing device F of this embodiment, when performing the folding in three and discharging process, after the first folding process, the sheets are not folded at the crease, but the second folding process is performed while the sheets are left open, and the sheets are then discharged as is, which is an open folding process.

[0046] The operation of folding in three by the folding device F of this embodiment will be described below with reference to the flow chart in Fig. 7 and the schematic cross-sectional views in Fig. 8 to Fig. 11 showing the movement of each part along the flow of the sheet S when folding in three is performed. Note that here, folding in three at equal intervals is taken as an example. Also, the following description will be given for a single sheet S instead of a sheet stack, but it goes without saying that the following process can also be performed for a sheet stack of multiple sheets.

[0047] 8(a), the intermediate tray 21 of this embodiment is formed at an angle with respect to the vertical direction, and the sheet S is conveyed so as to fall with the downstream edge E1 facing down and the upstream edge E2 facing up while one side of the sheet S is guided by a guide surface 21a that forms the conveying path of the intermediate tray 21, and the downstream edge E1 hits the regulating stopper 26 and stops. At this time, the position of the regulating stopper 26 has moved so that the first folding position (first folding position) of the sheet S against which the downstream edge E1 hits is a position facing the folding blade 23 (S1).

[0048] The first folding position is a position extending in the sheet width direction intersecting the conveying direction of the sheet S conveyed to the conveying path of the intermediate tray 21, where a position corresponding to 2 / 3 of the length of the conveying direction length of the sheet S before folding processing from the downstream edge E1 of the sheet S conveyed to the intermediate tray 21 abuts against the regulating stopper 26 faces the folding blade 23.

[0049] 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.

[0050] When the folding process is started, as shown in FIG. 8B, 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 against the first folding position F1 of the sheet S and protrudes into the nip portion 22c. At the same time, the folding roller motor 67 is driven to rotate the pair of folding rollers 22 in the forward direction, which is the first direction (here, the forward direction is the direction in which the folding roller 22a rotates clockwise and the folding roller 22b rotates counterclockwise) (S2). Here, the folding blade 23 starts to operate and the pair of folding rollers 22 starts to rotate at the same time, but the pair of folding rollers 22 may start to rotate after a predetermined time has elapsed or a predetermined number of pulses have been counted from the start of the folding blade 23. 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. In addition, the determination of whether the first folding position F1 has passed through the nip portion 22c may be made by a configuration other than counting the rotations of the motor, for example, by detecting the sheet S with a sensor and controlling the drive of the motor according to the detection result.

[0051] When the folding blade 23 protrudes a predetermined amount to push out the first fold of the sheet S to the nip portion 22c of the pair of folding rollers 22 by rotation of the cam member 25, the direction of travel is reversed and the blade moves in the return direction to return to the home position.

[0052] As a result of the protrusion of the folding blade 23, the sheet S is protruded into the nip portion 22c where the folding roller pair 22 is in pressure contact with each other, and while being sandwiched and transported by the folding roller pair 22, it is pressed with a predetermined pressing force and folded, thereby performing a first folding process.

[0053] Then, when the first folding position F1 has passed through the nip portion 22c by a predetermined distance, the driving of the pair of folding rollers 22 is stopped (S4). The pair of folding rollers 22 is set to stop while the edge closer to the first folding position F1 (the upstream edge E2 in this embodiment) of the downstream edge E1 and the upstream edge E2 in the conveying direction of the sheet S is on the conveying path of the intermediate tray 21. The stopping timing can be controlled by counting the driving pulses from the start of driving of the cam motor 66 that operates the folding blade 23 (S3).

[0054] Next, the pair of folding rollers 22 are rotated in a second direction opposite to the first direction to return the sheet S with the first crease to the intermediate tray 21 (S5). At this time, since both end edges E1 and E2 of the sheet S are within the sheet transport path formed by the intermediate tray 21, the sheet S is returned with the first crease open into the sheet transport path as shown in Fig. 9(a), and the sheet S, which has been released from nipping portion 22c, falls until the downstream end edge E1 abuts against the regulating stopper 26 and is returned to the sheet transport path (S6).

[0055] Next, to perform the second folding process, the regulating stopper motor 65 is driven to raise the regulating stopper 26 as shown in Figure 9(b) (S7), and the downstream edge E1 of the sheet S is moved so that the second folding position (second folding position) of the sheet S against which the downstream edge E1 of the sheet S is abutted is positioned opposite the folding blade 23 (S8).

[0056] The second folding position is a position extending in the sheet width direction intersecting the conveying direction of the sheet transported to the conveying path of the intermediate tray 21, where a position corresponding to 1 / 3 of the length of the sheet S from the downstream edge E1 faces the folding blade 23.

[0057] In this state, the cam motor 66 is driven to operate the folding blade 23 again, and as shown in FIG. 10(a), the sheet S is pushed out into the nip portion of the pair of folding rollers 22 (S9).

[0058] 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. As a result, the sheet S sent to the folding roller pair 22 by the protrusion of the folding blade 23 passes through the nip portion 22c where the first roller surfaces 22a2 and 22b2 face each other, and a pressing force is applied to the second folding position (second folding position) F2, whereby the second folding process is performed (S10).

[0059] As shown in Fig. 10(b), the sheet S that has been subjected to the second folding process is folded in two at the second folding position F2, and discharged to the stacking tray 17c by the pair of folding rollers 22 and the discharge roller 17b with the first folding position F1 open. At this time, after the second folding position F2 has passed through the nip portion 22c and before the first folding position F1 has passed through the nip portion 22c (in this embodiment, immediately after the second folding position F2 has passed through the nip portion 22c (S10), the pressure change motor 69 is operated to weaken the pressure contact force of the nip portion 22c (S11). Therefore, when the first fold passes through the nip portion 22c in an open state, it is possible to prevent a decrease in the fold retention force due to the first fold being crushed.

[0060] 11(a) and 11(b), the sheet S is discharged to the intermediate tray 21 with one third of the sheet folded inward at the second folding position F2 and the first folding position F1 open (S12). The creases of the sheets creased at the first folding position F1 are piled up on the creases of the already discharged sheets. This ensures that the sheets are optimally aligned.

[0061] In this embodiment, the second folding position F2 where the next folding process is performed is located downstream in the sheet conveyance direction to the intermediate tray 21 with respect to the first folding position F1 where the first folding process is performed, so that the sheet S that is folded at the second folding position F2 and discharged is stacked so that one edge of the sheet S that is folded toward the inside is on the lower side of the sheet S, as shown in Figures 11(a) and 11(b). Therefore, the sheet is stacked in a state where the folded one side is difficult to open due to its own weight, and even if a subsequent sheet is discharged, it does not push out the already discharged sheet, and the stacking property after discharge is good.

[0062] In addition, after the sheet S having been creased at the first folding position F1 on the upstream side in the transport direction is returned to the intermediate tray 21 as described above, when the regulating stopper 26 is raised to transport the sheet to the second folding position of the sheet to the position of the folding blade 23, there is no crease between the downstream edge E1 of the sheet abutting against the regulating stopper 26 and the second folding position F2, so that the folding blade 23 can be moved to accurately move the second folding position F2 to a position opposite the folding blade 23.

[0063] The sheet S discharged as described above can be easily folded along the first crease to fold the sheet S inwardly in three, as shown in FIG.

[0064] In addition, in this embodiment, the sheet conveying distance can be shortened to shorten the folding processing time, compared to when the sheet is discharged in a state where it is folded in three by the folding processing device F. To explain this specifically, when attempting to discharge the sheet in a state where it is folded in three by the folding processing device F, as shown in FIG. 13(a), after the first folding process, the edge E2 of the sheet S is conveyed from the conveying path of the intermediate tray 21 toward the folding roller pair 22, and then the folding roller pair 22 is rotated in reverse, and the sheet edge E2 needs to be conveyed so as to be guided to the downstream side of the conveying path of the intermediate tray 21, as shown in FIG. 13(b). In contrast, in this embodiment, after the first folding process as described above, the folding roller pair 22 is rotated in reverse to return the sheet edge E2 to the conveying path before the sheet edge E2 exits the conveying path of the intermediate tray 21, so that the sheet conveying distance is shortened, and the overall folding processing time can be shortened.

[0065] In the above description, an example in which one sheet is transported and folded is shown, but multiple sheets may be transported to the intermediate tray 21, the downstream edge E1 of each sheet is stacked in sequence at the regulating stopper 26, and the multiple sheets may be moved simultaneously to be folded by moving the regulating stopper 26. This allows multiple sheets to be folded simultaneously, improving production efficiency.

[0066] However, when folding a plurality of sheets simultaneously as described above, it is preferable to perform an open folding process in which the first fold is opened and the sheets are discharged as in this embodiment when the number of sheets is less than the predetermined number. In other words, when the sheets discharged after the open folding process are to be folded in three, they need to be folded along the first fold after being discharged. Therefore, when the number of sheets to be simultaneously folded is greater than the predetermined number, it is better to discharge the sheets folded in three by the folding device F as shown in FIG. 12, as this reduces the effort required for the subsequent folding process. Therefore, the predetermined number should be set based on which number provides better production efficiency.

[0067] Second Embodiment Next, a second embodiment of the sheet folding process with improved discharge stacking performance will be described. In the above embodiment, the first folding position F1 is located upstream of the second folding position F2 with respect to the sheet conveying direction to the intermediate tray 21, but the sheet can be folded in three with the first folding position F1 located downstream of the second folding position F2 to improve the discharge stacking performance.

[0068] 14A, the sheet conveyed to the intermediate tray 21 stops when its downstream edge E1 abuts against the regulating stopper 26. At this time, the position of the regulating stopper 26 is such that when the downstream edge E1 of the sheet conveyed to the intermediate tray 21 abuts against the regulating stopper 26, a position corresponding to 1 / 3 of the length of the sheet S in the conveying direction before folding processing from the downstream edge E1 faces the folding blade 23. That is, in this embodiment, the first folding position F1 is a position 1 / 3 of the sheet length from the downstream edge E1.

[0069] From the above state, the cam motor 66 and the folding roller motor 67 are driven to perform folding processing at the first folding position F1 (FIG. 14(b)). Then, when the first folding position F1 passes a predetermined length through the nip portion 22c, the driving of the folding roller pair 22 is stopped. This stopping of the folding roller pair 22 is set so that, of the downstream edge E1 and the upstream edge E2 of the sheet S, the downstream edge E1 closer to the first folding position F1 is on the conveying path of the intermediate tray 21.

[0070] Next, the pair of folding rollers 22 is rotated in the reverse direction to return the sheet S with the first crease to the intermediate tray 21. As in the first embodiment, since both end edges E1, E2 of the sheet S are within the sheet transport path formed by the intermediate tray 21, the sheet S is returned with the first crease open into the sheet transport path, as shown in FIG. 15(a). The sheet S, whose nip by the nip portion 22c has been released, falls until the downstream end edge E1 abuts the regulating stopper 26 and is returned to the sheet transport path.

[0071] Next, in order to perform the second folding process, the regulating stopper motor 65 is driven to lower the regulating stopper 26 as shown in Fig. 15(b) and move the regulating stopper 26 so that the second folding position F2 of the sheet S against which the downstream edge E1 of the sheet S is abutted faces the folding blade 23. This second folding position F2 is a position corresponding to 2 / 3 of the length of the sheet S in the conveying direction from the downstream edge E1, which faces the folding blade 23.

[0072] From the above state, the cam motor 66 and the folding roller motor 67 are driven to execute the second folding process (FIG. 16(a)), and the sheet is discharged directly onto the stacking tray 17c (FIG. 16(b)). As a result, as shown in FIG. 17, one-third of the sheet is folded upward at the second folding position F2, and the sheet is discharged in an open state at the first folding position F1.

[0073] Even when the folding process is performed as described above, the sheets that have been creased at the first folding position F1 are piled up with the creases of the already discharged sheets, so that the alignment of the discharged sheets is favorable. In addition, when the first folding position F1 is positioned downstream of the second folding position F2 as in this embodiment, when the first folded sheet S is returned to the intermediate tray 21 and then moved so that the second folding position faces the folding blade 23, there is no need to switch back the sheet, and therefore the conveying direction in the intermediate tray 21 is not reversed. This makes it possible to reduce the processing time required for the entire folding process compared to the folding process described above.

[0074] In addition, in the folding process of this embodiment, similarly to the first embodiment, the nip pressure may be reduced when the first folding position F1 where the crease has been made passes through the nip portion 22c again.

[0075] Third Embodiment In the above embodiment, the distance between the axes of the roller pair is variable in order to reduce the nip pressure when the first folding position F1 with the crease passes through the nip portion 22c again. However, the nip pressure may be changed by changing the roller diameter while keeping the distance between the axes of the rollers fixed.

[0076] 18, each of folding rollers 22a, 22b of folding roller pair 22 is configured by a roller having a first roller surface (first peripheral surface) 22a2, 22b2 having a constant radius R1 centered on the rotation axis of rotation shaft 22a1, 22b1, and a second roller surface (second peripheral surface) 22a3, 22b3 having a distance from the rotation axis of the rotation shaft smaller than the radius R1 of the first roller surface. Note that in this embodiment, first roller surface 22a2, 22b2 is formed of a rubber material or the like having a relatively high friction coefficient, similar to the roller surface of a roller used for normal sheet conveyance, and second roller surface 22a3, 22b3 is formed of a plastic resin material or the like having a friction coefficient smaller than that of first roller surface 22a2, 22b2.

[0077] Rotation shafts 22a1, 22b1 of folding rollers 22a, 22b are rotated by a common drive means such as a drive motor, etc. This allows the rotation positions to be always synchronized so that first roller surfaces 22a2, 22b2 and second roller surfaces 22a3, 22b3 face each other.

[0078] When the first roller surfaces 22a2 and 22b2 face each other, the nip portion 22c is pressed against the sheet S with a predetermined pressure, and the sheet S folded in half passes through the nip portion 22c to form a crease. When the second roller surfaces 22a3 and 22b3 face each other, the nip portion 22c is configured to have a small gap and not come into contact with the sheet S. Therefore, when the second roller surfaces 22a3 and 22b3 face each other, no pressure is applied to the sheet passing through the nip portion 22c.

[0079] With the above configuration, the pair of folding rollers 22 can apply a predetermined pressing force to the sheet passing through the nip portion 22c to perform the folding process, and can also pass the sheet with a lower pressing force than when the first folding position, which has been folded, passes through the pair of folding rollers 22 again, making it possible to adjust the pressing force of the nip portion 22c. Furthermore, in this embodiment, there is no need for a configuration that changes the distance between the roller axes as in the first embodiment described above, and it is possible to change the pressing force just by controlling the rotation of the folding rollers.

[0080] Other Embodiments In the above-described embodiment, the regulating stopper 26 is moved up and down as a position adjustment means for moving the sheet S, which is conveyed to the conveying path formed in the intermediate tray 21, in the conveying direction and in the direction opposite to the conveying direction, but a configuration other than the regulating stopper 26 may be used. For example, an upstream conveying roller pair (first conveying roller pair) and a downstream conveying roller pair (second conveying roller pair) capable of nipping and conveying a sheet may be provided on the upstream and downstream sides of the folding roller pair 22 in the sheet conveying direction, respectively, and the sheet may be conveyed to an arbitrary position by rotating these conveying roller pairs forward and backward.

[0081] When the position of the sheet can be adjusted by the conveying roller pair as described above, it becomes easy to reduce the size of the device because the main members for adjusting the position of the sheet can be concentrated around the pair of folding rollers 22. Furthermore, since the pair of conveying rollers can always nip and convey the sheet, the position of the sheet can be adjusted with high precision to each folding position.

[0082] In the above-described first embodiment, when the sheet is moved to a desired position by the conveying roller pair, the folding blade 23 is used as a biasing means, but it is also possible to push the sheet to the nip portion without using the folding blade 23. For example, by rotating the upstream conveying roller pair and the downstream conveying roller pair in the opposite directions, it is possible to push the folding position of the sheet S to the folding roller pair 22 and nip it by creating slack so that the sheet forms a loop at the folding position. In this case, the folding blade 23 and the cam member for moving it in the first embodiment are not required, and the device can be made even more compact. [Explanation of symbols]

[0083] A … Image forming device A1 … Image forming unit B … Sheet processing device F … Folding device F1: First fold position F2: Second fold position S...Seat 17b ... Discharge roller 17c ... Loading tray 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 60 ... Control section 100 ... Image forming system

Claims

1. a pair of folding rollers that are rotatable in a first direction and a second direction opposite to the first direction and rotate in the first direction to pinch a sheet and form a crease in the sheet; a pushing means for pushing the sheet toward the nip between the pair of folding rollers; an adjustment means for adjusting a position of the sheet in a direction intersecting a protruding direction of the protruding means; a stacking means for stacking the sheets on which the folds are formed by the pair of folding rollers; a first folding process in which the sheet whose position has been adjusted by the adjusting means is pushed out by the pushing-out means, and a first fold is formed by sandwiching the sheet between the pair of folding rollers rotating in the first direction; a conveying process in which the sheet whose position has been adjusted by the adjusting means is conveyed in a direction opposite to the pushing-out direction by the pair of folding rollers rotating in the second direction while opening the first fold; a second folding process in which the sheet whose position has been adjusted by the adjusting means is pushed out by the pushing-out means so that a position different from the first fold is pushed out by the pushing-out means, and a second fold is formed by sandwiching the sheet whose position has been adjusted by the adjusting means and the pair of folding rollers rotating in the first direction; and a control means for executing a discharge process in which the sheet whose first fold has been opened and whose sheet has been folded along the second fold is discharged toward the stacking means. A sheet processing apparatus comprising:

2. 2. The sheet processing apparatus according to claim 1, wherein the adjustment means is provided vertically below the pair of folding rollers and includes a contact member that contacts an edge of the sheet, and a moving means that moves the contact member in the intersecting direction.

3. The sheet processing apparatus according to claim 2 , wherein the control unit adjusts a position of the sheet in the intersecting direction by moving the contact member vertically upward in the intersecting direction after the first folding process is performed.

4. The sheet processing apparatus according to claim 2 , wherein the control unit adjusts a position of the sheet in the intersecting direction by moving the contact member vertically downward in the intersecting direction after the first folding process is performed.

5. 5. The sheet processing apparatus according to claim 1, wherein the pair of folding rollers is capable of changing a pressing force applied to the sheet, and the pressing force applied when the first fold is clamped in the nip when the discharge process is performed is smaller than the pressing force applied when the second folding process is performed.

6. The pair of folding rollers has a first peripheral surface having a constant radius to the roller peripheral surface and abutting against each other at a nip portion, and a second peripheral surface having a radius smaller than the radius of the first peripheral surface and not abutting against each other at the nip portion, 6. The sheet processing apparatus according to claim 1, wherein the control means controls the rotation of the pair of folding rollers so that the first peripheral surfaces face each other to form the nip portion when performing the first folding process and the second folding process, and so that the second peripheral surfaces face each other when performing the discharge process and the first fold passes through the pair of folding rollers.

7. 7. The sheet processing apparatus according to claim 1, wherein the control unit executes the second folding process when the number of sheets processed by the pair of folding rollers is equal to or less than a predetermined number.

8. A sheet processing device as described in any one of claims 1 to 7, characterized in that when performing the second folding process, the control means continues to rotate the pair of folding rollers in the first direction, thereby discharging the sheet in a state in which the first fold is open and the sheet is folded by the second fold to the loading means.

9. A sheet processing device as described in any one of claims 1 to 8, characterized in that in a sheet that has been subjected to the first folding process and the second folding process, when the portion between the first fold and the second fold is defined as a first part, the portion opposite the first part across the first fold is defined as a second part, and the portion opposite the first part across the second fold is defined as a third part, the third part is loaded onto the loading means so as to be vertically lower than the first part and the second part.

10. an image forming apparatus for forming an image on a sheet; 10. The sheet processing apparatus according to claim 1, wherein the first folding process, the second folding process, and the ejection process are performed on the sheet conveyed from the image forming apparatus; An image forming system comprising:

Images