JP2010006480A - Paper folding device, paper conveying device, paper post-treatment device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an improved, compact and inexpensive paper center folding device with a short processing time, a high output quality and high reliability; a paper conveying device, a paper post-treatment device and an image treatment device having this. <P>SOLUTION: The paper folding device is provided with a folding roller and a folding plate for applying folding to a bundle of sheets; a means for reversely conveying the folded bundle of sheets; and a means for re-intruding the reversely conveyed bundle of sheets to a nip of the folding roller. After attitude is changed in the state in which the folding part is inclined, re-intrusion is performed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a sheet folding apparatus and an image forming apparatus that are integrated into an image forming apparatus such as a copying machine, a printer, and a printing machine, and a separate unit for the image forming apparatus. An image forming apparatus (system) comprising a sheet conveying apparatus and a sheet post-processing apparatus for performing a predetermined process on a sheet (recording medium) on which an image has been formed and discharging the sheet, and further comprising the separate apparatus and the image forming apparatus main body. About.

2. Description of the Related Art A post-processing device that is disposed as a separate auxiliary device downstream of an image forming apparatus main body and performs binding processing or folding processing on output recording paper or the like is widely known. These post-processing devices have recently been multi-functionalized and generalized the saddle-stitching process in addition to the conventional edge-stitching process, and the folding quality of booklets that have been saddle-stitched as an output quality improvement means. The improvement means of this is proposed. However, many of them are limited in function because the machine is large or complex. Note that the post-processing mechanism may be incorporated in the image forming apparatus itself, but the above situation is the same in this case.
As an example of a conventional separate device, for example, in Patent Document 1, as an external device, after a crease is made by a pair of folding rollers and a protruding plate, a pressure roller arranged with a shaft inclined at a predetermined angle downstream is used. There has been proposed a folding apparatus that performs an additional folding process. In this method, the folding part is pressurized locally and the pressing force per unit length is increased to improve the folding quality.
However, with this configuration, it is possible to improve the folding quality. However, if an expensive pressure roller is newly required and transported across both the pressure roller and the additional folding roller, each roller section In this case, the paper transport direction does not match (slightly intersects), so the paper slips with respect to either roller, so that the image surface is soiled, and in the worst case, the paper is torn. May have a significant impact on quality.
As a method for solving this problem, a method in which the distance between the pressure rollers is arranged so as to be pressed by the downstream roller after passing through the nip of the upstream pressure roller is considered. Is required, which further increases costs and tends to increase in size. Another method is to release the nip of the upstream pressure roller before it is sandwiched by the downstream pressure roller to eliminate the transfer of the conveying force. However, a complicated mechanism is required and delivery is performed. It is difficult to set the paper conveyance timing at the time, the conveyance reliability tends to be lowered, and the cost increases.

As another example, Patent Document 2 proposes a means for improving the folding quality by providing means for applying heat and pressure to the fold, but this not only consumes electric power but also a heating roller. In addition, a control means for controlling the temperature is required, and there is a problem that the cost becomes high. In addition, in Patent Document 3 or Patent Document 4, a pair of folding rollers are rotated in forward and reverse directions to perform a plurality of diffraction processes, and the number of reciprocal folding is increased as the number of sheets increases. Proposed. However, as the number of times increases, there is a problem that the processing time increases and productivity decreases.
Japanese Patent Application Laid-Open No. 2004-228561 proposes a paper that aims at an additional folding effect by moving the additional folding roller in a direction orthogonal to the sheet conveying direction and locally pressing the folding unit. However, when the additional folding roller is reciprocated, the sheet bundle must be stopped, resulting in poor productivity.
In addition to this, a paper processing apparatus including a half-fold processing mechanism has been filed by the present applicant (Patent Document 6). In the device disclosed in Patent Document 6, an end-face stitching stapler and a saddle stitching stapler are provided at the lower end and substantially the center of the same sheet processing tray. The end-face stitching stapler is driven via a timing belt by a forward / reversely movable stapler moving motor, and moves in the sheet width direction in order to bind a predetermined position of the sheet edge. A stapler movement HP sensor that detects the home position of the end-face stitching stapler is provided at one end of the movement range, and the binding position in the sheet width direction is controlled by the amount of end-face stitching stapler movement from the home position. The Then, the bound sheet bundle is conveyed to the middle folding processing tray side and folded in half.
JP 2001-261220 A JP-A-11-157247 JP-A-9-183568 Japanese Patent No. 3254363 JP 2004-59304 A JP 2003-95527 A

  The present invention has been devised in view of the above-mentioned difficulties found in the prior art, and is an improved half-folding means that is compact and low-cost, has a short processing time, high output quality, and high reliability. It is an object of the present invention to provide a sheet transport device, a sheet post-processing device, and an image processing device that are provided.

In order to solve the above-mentioned problem, a sheet folding device according to claim 1 is a pair of folding rollers forming a nip for folding a bundle of sheets, and a bundle of sheets in the nip of the folding roller. A folding plate for feeding the sheet with the folding line portion at the top, and a reverse conveying means for conveying the sheet bundle folded by the folding roller back to a position where the folded portion is pulled upstream from the nip portion of the folding roller; Re-conveying means for re-entering the sheet bundle into the nip after reverse conveyance, and the control means changes the posture of the folding unit to be inclined with respect to the folding roller and re-enters the nip. Features.
A paper folding device according to a second aspect of the present invention is the paper folding device according to the first aspect, wherein the paper folding device is arranged at an upstream position of the nip portion and spaced apart in a direction orthogonal to the paper bundle conveying direction, A pair of switchback rollers constituting reverse conveying means / reconveying means, and the control means controls the difference in the rotational direction of each of the switchback rollers or the difference in the conveyance amount, whereby The posture is changed and oblique re-conveyance is performed.
According to a third aspect of the present invention, there is provided the paper folding device according to the first or second aspect, wherein the control unit is configured to change the posture based on an output from the folding number information acquisition unit. The skew amount is determined and controlled.
According to a fourth aspect of the present invention, in the paper folding apparatus according to the third aspect, the control means sets the skew amount to be larger and performs posture change control as the number of folded sheets increases. It is characterized by performing.
According to a fifth aspect of the present invention, there is provided a paper conveying apparatus including the paper folding apparatus according to any one of the first to fourth aspects.
A sixth aspect of the present invention is a paper post-processing apparatus having the paper folding device according to any one of the first to fourth aspects.
A seventh aspect of the present invention is an image forming apparatus having the sheet folding device according to any one of the first to fourth aspects.
According to an eighth aspect of the present invention, there is provided an image forming apparatus comprising the paper conveying apparatus according to the fifth aspect or the paper post-processing apparatus according to the sixth aspect.

  According to the present invention, a compact and low-cost, short processing time, high output quality, high reliability, and a folding device with improved folding characteristics, a paper transport device having the same, and a paper post-processing device In addition, an image processing apparatus can be provided. In the present invention, a crease is formed by a folding roller constituting a half-folding device such as a paper conveying device, the paper bundle is switched back, and the fold is inclined with respect to the folding roller and reenters the folding roller. Thus, additional folding is performed, and the amount of fold inclination with respect to the folding roller is variable according to the number of intermediate folds. By providing this configuration, the processing time is short, and by performing the middle folding and additional folding with the same folding roller, it is compact and low-cost, and the folding section is conveyed diagonally so that it can be locally applied to the folding section. By applying pressure and increasing the pressing force per unit length, a folding device or the like capable of performing folding processing with high output quality and high reliability is provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a system configuration of an image forming system including a sheet post-processing apparatus as a sheet processing apparatus and an image forming apparatus (main body) as a sheet processing apparatus according to an embodiment of the present invention. The entire sheet post-processing apparatus and a part of the image forming apparatus main body are shown.
FIG. 2 is an enlarged cross-sectional view showing a schematic configuration of a main part of a center folding mechanism (a center folding processing apparatus) which is a characteristic part of the present embodiment.
In this embodiment, the image forming apparatus (main body unit) may be any of various known configurations, and the printing method is not limited. In short, it suffices if it is configured to sequentially feed individual single-sheet sheets on which images have been formed to a sheet post-processing apparatus described in detail later. Therefore, detailed description will not be given in the specification.
On the other hand, although the sheet post-processing apparatus shown in the embodiment includes a feature part this time, a paper post-processing apparatus having a similar configuration as an overall configuration has already been filed and published by the present applicant (Patent Document 6). In the present specification and the accompanying drawings, the same reference numerals are given to the same parts as those of the device disclosed in Patent Document 6 (hereinafter referred to as an already-applied device).
Accordingly, in the present specification, there is also an intention to clarify the invention, and a description overlapping with that of Patent Document 6 is omitted or simplified for a portion that is the same as the above-mentioned already-applied apparatus and is not directly related to the present invention. It is.

The outline of the sheet post-processing apparatus will be described below. In FIG. 1, a sheet post-processing apparatus PD is attached to a side portion of the image forming apparatus PR, and a sheet-like recording medium (hereinafter simply referred to as a sheet) discharged from the image forming apparatus PR is a sheet post-processing apparatus PD. Led to.
The sheet passes through a conveyance path A having post-processing means (in this embodiment, punch unit 100 as a punching means) for post-processing each sheet, and is conveyed to the upper tray 201. The branching claw 15 and the branching claw 16 respectively distribute to the conveyance path C that leads to the conveyance path D that leads to the processing tray F that performs alignment, staple binding, and the like.
Note that the image forming apparatus PR is already well known and is not shown in FIG. 1 at all, that is, an image processing circuit that converts input image data into printable image data, and an output from the image processing circuit. Optical writing device that performs optical writing on the photoconductor based on the image signal generated, a developing device that develops the latent image formed on the photoconductor by optical writing, and a toner image that is visualized by the developing device is transferred to the paper And a fixing device for fixing the toner image transferred on the paper.
The image processing circuit, the optical writing device, the developing device, the transfer device, and the fixing device constitute an image forming unit. The image-formed paper on which the toner image is fixed in the image forming apparatus PR is sent to the paper post-processing device PD, and desired post-processing is performed by the paper post-processing device PD. Here, the image forming apparatus PR is of an electrophotographic system as described above, but any known image forming apparatus such as an ink jet system or a thermal transfer system can be used.

The sheet is guided to the end surface binding processing tray F through the transport paths A and D, and alignment and stapling are performed on the end surface binding processing tray F. Next, by a branch guide plate 54 and a movable guide 55 which are deflecting means, the sheet is distributed to the conveyance path C leading to the shift tray 202 and the middle folding processing tray G for folding. The sheet that is folded in the middle folding processing tray G is guided to the lower tray 203 through the conveyance path H.
Further, a branching claw 17 is disposed in the conveyance path D, and is held in the state shown in the figure by a low load spring (not shown). After the trailing edge of the sheet passes through this, the conveyance rollers 9, 10 and the staple discharge roller 11 is configured such that at least the transport roller 9 is reversed so that the rear end is guided and retained in the paper storage portion E and can be transported while being superposed on the next paper. By repeating this operation, two or more sheets can be overlapped and conveyed as a bundle.
In the conveyance path A common to the upstream of the conveyance path B, the conveyance path C, and the conveyance path D, an inlet sensor 301 that detects a sheet received from the image forming apparatus PR, and an inlet roller 1, a punch unit 100, The punch and waste hopper 101, the conveying roller 2, the branching claw 15 and the branching claw 16 are sequentially arranged. The branching claw 15 and the branching claw 16 are held in the state shown in FIG. 1 by a spring (not shown). By turning on a solenoid (not shown), the branching claw 15 is rotated upward and the branching claw 16 is rotated downward. The paper is distributed to the conveyance path B, the conveyance path C, and the conveyance path D according to the combination of the rotation states.
In this paper post-processing apparatus, punching (punching unit 100), paper alignment + edge binding (jogger fence 53, edge binding stapler S1), paper alignment, paper sorting (shift tray 202), medium, Various processes such as a binding process and a half-folding process (by the folding plate 74, the conveyance roller 81, the conveyance roller 82, and the folding roller 82) executed by the sheet folding apparatus, which is a feature of the present invention, can be performed.

As shown in FIG. 2.) Shift tray section, 2.1) Shift tray lifting mechanism, 2.2) Paper discharge section, ) End face binding processing tray, 3.2) Paper discharge mechanism, 3.3) Processing mechanism, The detailed configuration and operation of the sheet bundle deflecting mechanism are not directly related to the present invention, and are described in detail in Patent Document 6 [1.1 in Patent Document 6] Following the overall configuration. Therefore, the description in this specification is omitted.
In this embodiment, the staple processing tray F and the middle folding processing tray G are arranged in a state where the middle folding processing tray G side is vertically inclined and the staple processing tray F side is inclined at a steep angle with the arc of the surface of the discharge roller 56 as a bent portion. Is integrated. A smaller inclination angle of the staple processing tray F is desirable because the vertical projection area becomes smaller and the occupied floor area becomes smaller.
However, in this embodiment, the folding mechanism shown in FIG. 4, that is, the folding plate 74, the link arm 76, the folding plate drive cam 75 and the folding plate drive motor 166 are arranged in the middle folding processing tray G (below the bundle conveyance guide plate). 91, 92) and the staple processing tray F. At this time, these folding mechanisms are positioned between the end-face stitching stapler S1 and the saddle stitching stapler S2.

In the case of half-folding, it is necessary to position the central portion of the sheet bundle at a position where folding is performed by a folding plate described later. Therefore, in this embodiment, a movable rear end fence 73 is provided under the bundle conveyance guide plate 91, and the rear end of the sheet bundle (the rear end after folding processing, which becomes the front end during conveyance) is brought into contact with the movable rear end fence 73. In this contacted state, the sheet bundle is moved up and down to control the center of the sheet bundle at the folding position.
The movable rear end fence 73 is fixed to a drive belt 73c stretched between a drive pulley 73a and a driven pulley 73b, and is driven in the vertical direction by a rear end fence moving motor (not shown). The driving mechanism of these movable rear end fences 73 is arranged in the space between the staple processing tray F and the middle folding processing tray G, and is designed so as not to increase the vertical projection area, similarly to the folding mechanism described above. Yes.
A half-fold provided on the downstream side of the staple processing tray F is a half-fold of a sheet bundle (in some cases, a single sheet) that is appropriately processed and aligned by each processing unit in order or in cooperation. This is performed in the processing tray G. The saddle stitched sheet bundle is guided from the staple processing tray F to the center folding processing tray G by the sheet bundle deflection mechanism.

Hereinafter, the configuration of the half-fold processing tray G will be described.
5.1) Configuration of the middle folding processing tray As shown in FIGS. 1 and 2, the middle folding processing tray G is provided on the downstream side of the sheet bundle deflection mechanism including the branch guide plate 54 and the movable guide 55. The center folding processing tray G is provided in a substantially vertical posture on the downstream side of the sheet bundle deflecting mechanism. The center folding mechanism is at the center, the bundle transport guide plate upper 92 is above, and the bundle is transported downward. A guide plate lower 91 is disposed. Further, an upper bundle conveying roller 71 is provided above the bundle conveying guide plate 92, and a lower bundle conveying roller 72 is provided below the bundle conveying guide plate.
A movable rear end fence 73 is disposed so as to cross the bundle conveyance guide plate lower 91, and can be moved in the sheet conveyance direction (vertical direction in the figure) by a moving mechanism including a timing belt 73a and its driving mechanism. Yes. As shown in FIG. 1, the drive mechanism includes a drive pulley 73b, a driven pulley 73c, and a stepping motor 73d that drives the drive pulley 73b.

Next, the folding mechanism that is a characteristic part of the present embodiment will be described in detail. The center folding mechanism shown in an enlarged manner in FIG. 2 is provided at substantially the center of the center folding processing tray G, and serves as a folding plate 74 and a sheet (bundle) reverse transport unit and a re-transport unit. Conveying means 81 (including a pair of upper and lower bundle conveying rollers 503), a folding roller 82 (upper and lower pair), and a conveying path H for conveying a sheet bundle. A rear transport roller 83 (lower paper discharge roller) is disposed on the downstream side of the transport path H.
The folding roller (pair) 82 is pressed by a pressing means such as a spring (not shown). The bundle conveying means 81 disposed on the upstream side of the folding roller 82 includes a bundle conveying roller 503 (upper / lower pair) for conveying the sheet bundle and a drive motor 500, and is configured to have a drive control unit (not shown). ), The paper bundle is reversely conveyed, the posture is changed, and the paper is conveyed again. A folding portion passage sensor 323 is provided between the bundle conveying means 81 and the folding roller 82.

FIG. 3 shows a mechanism part of the bundle conveying means 81. FIG. 3A is a side view (503a side), as viewed from above. FIG. 3C shows the arrangement in the vicinity of the bundle conveying means 81. Two sets of the bundle conveying means 81 are provided approximately symmetrically with respect to the sheet conveying center.
In each bundle conveying means 81, the lower bundle conveying roller 503 of the pair of upper and lower bundle conveying rollers is individually provided on the left and right via a timing pulley 502 and a timing belt 501, as shown in FIG. It is connected to the motor 500 and is configured to be rotatable in the forward and reverse directions according to the rotation of the drive motor.
Each bundle conveying means is independently controlled so that the bundle conveying roller 503 rotates independently on the left and right sides, and the posture of the sheet can be changed by changing the rotation amount of the bundle conveying at the time of conveying each sheet. It has become a structure. That is, by controlling the difference between the rotation directions of the switchback rollers or the difference in the transport amount with the control means, the posture of the sheet bundle can be changed, and the transport can be performed while maintaining an oblique posture. The operation of the bundle conveying means 81 will be described in detail later with reference to FIGS.

5.2) Folding plate and operating mechanism thereof FIGS. 4A and 4B are operation explanatory views of the moving mechanism of the folding plate 74 for performing the middle folding. The folding plate 74 is supported by loosely fitting the long hole portions 74 a to the two shafts 64 c erected on the front and rear side plates 64 a and 64 b, and the shaft portion 74 b erected from the folding plate 74 is further linked to the link arm 76. When the link arm 76 swings about the fulcrum 76a, the folding plate 74 reciprocates left and right in FIGS. 4 (a) and 4 (b). That is, the shaft portion 75b of the folding plate driving cam 75 is loosely fitted in the long hole portion 76c of the link arm 76, and the link arm 76 swings due to the rotational movement of the folding plate driving cam 75. 2, the folding plate 74 reciprocates in a direction perpendicular to the upper and lower bundle conveyance guide plates 91 and 92.
The folding plate drive cam 75 is rotated by the folding plate drive motor 166 in the direction of the arrow in FIG. The stop position is determined by detecting both end portions of the half-moon shaped shielding portion 75a by the folding plate HP sensor 325.

FIG. 4A shows the home position completely retracted from the sheet bundle storage area of the half-fold processing tray G. FIG. When the folding plate drive cam 75 is rotated in the direction of the arrow, the folding plate 74 moves in the direction of the arrow and protrudes into the sheet bundle accommodation area of the middle folding processing tray G. FIG. 4B shows a position where the center of the sheet bundle of the center folding processing tray G is pushed into the nip of the folding roller 82. When the folding plate drive cam 75 is rotated in the direction of the arrow, the folding plate 74 moves in the direction of the arrow in FIG. 4B and retracts from the sheet bundle accommodation area of the center folding processing tray G.
In this embodiment, the folding function is premised on binding a bundle of sheets, but it can also be used when folding a single sheet. In this case, since only one sheet is required and saddle stitching is not necessary, when one sheet is discharged, the sheet is fed to the middle folding processing tray G side, and folding processing is executed by the folding plate 74 and the folding roller 82 to lower the lower tray. The paper is discharged to 203.

6). ) Control Device As shown in FIG. 5, the control device 350 is the same as that disclosed in Patent Document 6, and includes a microcomputer having a CPU 360, an I / O interface 370, and the like. Various signals are input to the CPU 360. That is, each switch of the control panel of the image forming apparatus PR main body, the inlet sensor 301, the upper discharge sensor 302, the shift discharge sensor 303, the prestack sensor 304, the staple discharge sensor 305, the paper presence sensor 310, the discharge belt. Home position sensor 311, staple movement home position sensor 312, stapler oblique home position sensor 313, jogger fence home position sensor 314, bundle branch guide home position sensor 315, bundle arrival sensor 321, movable rear end fence home position sensor 322, folding part Signals from the sensors such as the passage sensor 323, the lower discharge sensor (folding portion passage sensor) 324, the folding plate home position sensor 325, the paper surface detection sensors 330, 330a, 330b, and 505 are received. / O interface 370 via the input to the CPU 360.

  The CPU 360 drives the tray lifting / lowering motor 168 for the shift tray 202, the discharge guide plate opening / closing motor 167 for opening / closing the opening / closing guide plate, the shift motor 169 for moving the shift tray 202, and the tapping roller 12 based on the input signal. The unillustrated tapping roller motor, solenoids such as tapping SOL 170, a conveying motor for driving each conveying roller, a discharging motor for driving each discharging roller, a discharging motor 157 for driving the discharging belt 52, and an end face binding stapler S1 are moved. The stapler moving motor 159, the oblique motor 160 that obliquely rotates the end-face stitching stapler S1, the jogger motor 158 that moves the jogger fence 53, the bundle branch drive motor 161 that rotates the branch guide plate 54 and the movable guide 55, and the bundle is conveyed. Bundle (not shown) for driving the conveying roller Feed motor, the rear end fence moving motor (not shown) for moving the movable rear fence 73, the folding the folding plate driving motor 166 to move the plate 74, controls the driving of such unillustrated folding roller drive motor for driving the folding roller 82. Further, the rotation direction and rotation speed of the bundle conveyance drive motor 500 (see FIG. 3) are controlled.

The paper post-processing apparatus according to the present embodiment can take various discharge forms according to the post-processing mode set by the user (details of the discharge forms are not described). Each discharge mode, ie, (1) non-stipple mode A, (2) non-stipple mode B, (3) sort, stack mode, (4) stipple mode, (5) saddle stitch binding mode, etc. After a series of predetermined processes that are selectively determined according to the above, a sheet folding process is performed as necessary.
That is, when the binding process suitable for the specified discharge form is completed, the discharge motor is driven and the discharge belt 52 is driven. At the same time, the paper discharge motor is driven, and the shift paper discharge roller 6 starts to rotate so as to accept the sheet bundle lifted by the discharge claw 52a.
The control of each of the above operations is executed by the CPU 360, but these series of controls are the same as in the case of Patent Document 6. Here, the detailed description of each operation is omitted, and in the following, it is also executed by the CPU 360. (5) Only the operation in the saddle stitch binding mode will be described in detail.

(5) Saddle binding mode:
In this saddle stitch binding mode, the sheet is transported to the end face binding processing tray F through the transport path A and the transport path D, aligned and centered in the staple processing tray F, and then further folded in the center folding processing tray G. This is a mode in which the folded sheet bundle is discharged from the conveyance path H to the lower tray 203. In this mode, both the branch claw 15 and the branch claw 16 rotate counterclockwise, and the path from the transport path A to D is opened. In addition, the branch guide plate 54 and the movable guide plate 55 are closed, and the sheet bundle is guided to the middle folding processing tray G, and the middle folding is performed. Note that the saddle stitching process itself is equivalent to a known one, but the half-folding process is unique to the embodiment, and an improved half-folding process is executed.
An outline of the existing saddle stitching process will be described. In the saddle stitch binding mode, the paper sorted by the branch claw 15 and the branch claw 16 from the conveyance path A is guided to the conveyance path D, passes through the conveyance roller 7, the conveyance roller 9, and the conveyance roller 10, and then the staple paper discharge roller 11. Is discharged to the staple processing tray F. In the staple processing tray F (see FIG. 2), the sheets sequentially discharged by the discharge rollers 11 are aligned in the same manner as in the staple mode, and the same operation is performed until immediately before the stapling.

After the sheet bundle is temporarily aligned in the end-face binding processing tray F, the discharge belt 52 starts to rotate, and the sheet bundle is conveyed downstream in the conveying direction by a distance set for each sheet size by the discharge claw 52a, and the center of the sheet bundle is conveyed. Binding processing is performed by the saddle stitching stapler S2. The bound sheet bundle is conveyed by a discharge claw 52a to the downstream side in the conveyance direction for a predetermined distance set for each sheet size, and temporarily stops. This travel distance is managed by the drive pulse of the discharge motor.
Thereafter, the leading end portion of the sheet bundle is sandwiched between the discharge roller 56 and the pressure roller 57, and the path formed by the rotation of the branch guide plate 54 and the movable guide 55, that is, the path guided to the half-fold processing tray G. Is again conveyed downstream by the discharge claw 52 a and the discharge roller 56. The discharge roller 56 is provided on the drive shaft of the discharge belt 52 as described above, and is driven in synchronization with the discharge belt 52.
The sheet bundle abutted against the movable rear end fence 73 is released from the pressurization of the lower bundle conveying roller 72, and thereafter, the vicinity of the staple portion is pushed in a substantially right angle direction by the folding plate 74, and the opposing folding roller 81 to the nip. The folding roller 81 rotating in advance folds the center of the sheet bundle by conveying the sheet bundle guided to the nip under pressure.

Next, the middle folding process is performed. The flowchart of FIG. 6 shows the flow of operation of the half-folding apparatus. Hereinafter, the operation will be specifically described with reference to the operation explanatory diagrams (I) to (VI) showing the state of each step of the sheet of FIG.
As shown in (I) in FIG. 7, the sheet bundle is conveyed toward the folding roller 82 by the folding plate 74 and the bundle conveying roller 503 with the folded portion of the sheet bundle as the head. That is, the saddle-stitched sheet bundle is conveyed upward along with the movement of the movable rear end fence 73 while the pressurization of the lower bundle conveying roller 72 is released, and then the vicinity of the stapled staple portion is folded around the folding plate 74. Is pushed in a substantially right angle direction, and is further pushed into the nip of the folding roller 82 facing the head portion in the traveling direction. At this time, the bundle conveying roller 503 is separated and does not hinder the progress of the sheet bundle (it may be driven or controlled to assist the advancement in cooperation).
(II) The folding roller 82 that has been rotated in advance conveys the pressed sheet bundle under pressure, thereby folding the folded portion at the center of the sheet bundle. In this way, the first half-folding operation to the sheet bundle is performed.
When the leading folded portion of the sheet bundle folded by the folding roller 82 slightly passes through the nip of the folding roller 82, the conveyance is stopped and the sheet bundle is temporarily stopped. This passage time can be detected by the folding portion passage sensor 323.

(III) The folding roller 82 and the bundle conveying roller 503 are reversely rotated, so that the switchback conveying is performed until the nip of the sheet bundle passes through the folding roller 82.
(IV) Next, the bundle conveying rollers are rotated so as to rotate in opposite directions, thereby rotating the sheet bundle held by the left and right bundle conveying rollers to a posture inclined with respect to the folding roller axis.
(V) In the state of (IV), the bundle conveying roller rotates in the same direction in the same direction, and the bundle of sheets is conveyed to the folding roller 82 in an inclined state and is further folded by the folding roller 82 to enhance folding. Perform the action. At this time, when the folding portion enters the folding roller 82 in an oblique state, it becomes possible to locally pressurize the folding portion and increase the pressing force per unit length.
(VI) The sheet bundle whose folding is strengthened by the folding roller 82 in this way is directed toward the lower tray (discharge tray) 203 after the folded portion reaches the rear discharge roller 83. The posture is corrected by rotating at a speed difference in the discharge direction, and the sheet is discharged onto the lower tray 203 and stacked in order.
At this time, when the rear end of the sheet bundle is detected by the lower paper discharge sensor (folding section passage sensor) 324, the folding plate 74 and the movable rear end fence 73 are returned to the home position, and the pressing force of the lower bundle conveying roller 72 is also increased. Return and prepare for the next sheet. If the next job is the same sheet size and the same number of sheets, the movable rear end fence 73 may stand by at that position.

As the skew amount θ in the above-described processing increases, the additional folding effect increases (because the pressing force per unit length with respect to the fold increases). Therefore, in the embodiment, it is set to gradually increase to 0 to 5 ° as the number of sheets increases. For this reason, in the embodiment, as shown in the flowchart of FIG. 8, in the middle folding process, the number of folded sheets is counted, the skew amount of the sheet bundle is determined according to the obtained number of folded sheets, and this skew amount is calculated. As described above, the amount of conveyance of the bundle conveyance roller at the time of control is changed, and the above-described half-folding process is executed. The sheet post-processing apparatus according to the embodiment configured as described above realizes folding processing that is compact and low-cost as intended, has a short processing time, has high output quality, and high reliability.
In the above-described embodiment apparatus, when the posture is changed, the pair of left and right bundle conveying rollers 503 are controlled to rotate in opposite directions, but the fold portion is switched back so that the folding roller 82 is switched. It is also possible to change the desired posture by controlling to stop the bundle conveying roller 503 remaining after the driving of one (one of the left and right pair) bundle conveying rollers is stopped for a predetermined time at the timing of the removal. The flowchart is omitted because only minor changes are required from the flowchart of FIG. Alternatively, the posture of the sheet bundle can be controlled in the same manner by stopping the driving of the left and right bundle conveying rollers 503 and reversing the other bundle conveying rollers 503 for a predetermined time.
In this way, a set of two bundle conveying rollers (switchback rollers) 503 is provided at one place on each of the left and right sides, and the difference in the rotational direction or the difference in the conveying amount of these bundle conveying rollers 503 is controlled by the control means. By doing so, it becomes possible to change the posture of the sheet bundle. As it is, it is possible to carry out oblique re-conveyance while changing the posture obliquely.

  Note that the posture change can be realized by a method other than the method for controlling the driving of the bundle conveying roller 503 as in the above-described embodiment. For example, it is disadvantageous in terms of space and needs to be used in combination with an appropriate conveying means, which is disadvantageous in cost. However, as shown in FIG. This gripper 504 is provided, and the dedicated gripper 504 is driven to rotate while holding the sheet bundle, so that the attitude of the sheet bundle can be controlled even if a configuration for rotating the sheet bundle is adopted. The amount of skew can be made variable. A switchback operation is performed by a simple re-transporting means (not shown) for transporting in a fixed direction by a pair of transportable rollers that can be slidable in cooperation with the gripper 504. The switchback operation may be realized by using a configuration in which the gripper 504 itself moves horizontally in the sheet bundle conveying direction also serving as the re-conveying means. Even in the mechanism shown in FIG. 9, the same folding characteristic improvement effect as in the first embodiment can be obtained.

1 is a diagram illustrating a system configuration of an image processing system including a sheet processing apparatus and an image forming apparatus mainly showing a sheet post-processing apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating details of a staple processing tray and a half-fold processing tray of the sheet post-processing apparatus of FIG. 1. (A)-(c) is a figure which shows the mechanism part of the bundle conveyance means 81 in embodiment. FIGS. 2A and 2B are operation explanatory views of the folding plate moving mechanism of the sheet post-processing apparatus of FIG. 1, in which FIG. 1A shows a state before entering a middle folding operation, and FIG. Indicates the state. FIG. 2 is a block diagram mainly illustrating a configuration of a control system of the image forming system according to the embodiment, particularly a control configuration of a sheet post-processing apparatus. It is a flowchart which shows the flow of operation | movement of the middle folding apparatus in embodiment. (I)-(VI) are operation | movement explanatory drawings of the middle folding apparatus in embodiment. It is a flowchart of the procedure which sets the amount of skews in the middle folding process. It is a figure which shows the mechanism part of the other bundle conveyance means which concerns on this invention.

Explanation of symbols

  6 shift discharge roller, 8 pre-stack roller, 32 end fence, 51 rear end fence, 52 discharge belt, 52a discharge claw, 53 jogger fence, 54 branch guide plate, 55 movable guide, 56 discharge roller, 60 link arm, 61 Cam, 66 Support rail, 73 Movable rear end fence, 73a Timing belt, 73b Drive pulley, 73c Drive pulley, 73d Drive motor, 74 Fold plate, 75 Fold plate drive cam, 76 Link arm, 81 Bundle conveying means 81, 82 Fold Roller (upper / lower pair), 83 rear transport roller (lower paper discharge roller), 203 lower tray (paper output tray), 323 folding section passage sensor, 324 lower paper ejection sensor (folding section passage sensor), 500 bundle transport driving motor, 501 timing belt, 502 timing Over Li, 503 bundle conveying rollers (upper and lower pair), 504 gripper, F staple processing tray, the processing tray folding in G, PD sheet post-processing apparatus, PR image forming apparatus, S1 end face binding stapler, in S2 stitching stapler

Claims (8)

A folding roller forming a nip for folding the bundle of sheets in pairs;
A folding plate for feeding the sheet bundle to the nip of the folding roller with the folding line portion as the head;
Reverse conveying means for reversely conveying the sheet bundle folded by the folding roller to a position where the folded portion is pulled upstream from the nip portion of the folding roller;
Re-conveying means for re-entering the sheet bundle into the nip after reverse conveyance,
The sheet folding apparatus, wherein the control unit changes the posture of the folding unit to be inclined with respect to the folding roller and re-enters the nip. Each switchback roller includes a pair of switchback rollers arranged at a position upstream of the nip portion and spaced apart in a direction orthogonal to the sheet bundle conveyance direction and constituting the reverse conveyance means and the reconveyance means. by controlling the difference in the rotational direction of the difference or the transport amount by the control means, the paper folding apparatus according to claim 1, characterized in that performing the attitude change and oblique reconveyed of the sheet bundle.   3. The sheet folding apparatus according to claim 1, wherein the control unit determines and controls a skew amount at the time of changing the posture based on an output from the folding number information obtaining unit.   4. The sheet folding apparatus according to claim 3, wherein the control unit performs posture change control by setting the skew amount to a larger value as the number of folded sheets increases.   A sheet conveying apparatus comprising the sheet folding apparatus according to claim 1.   A sheet post-processing apparatus comprising the sheet folding apparatus according to claim 1.   An image forming apparatus comprising the sheet folding device according to claim 1.   An image forming apparatus comprising the sheet conveying apparatus according to claim 5 or the sheet post-processing apparatus according to claim 6.

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