JP2010168208A - Sheet folding device and image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet folding device capable of reliably preventing any skew in the sheet conveying direction, and preventing folding wrinkles and degradation of the folding accuracy. <P>SOLUTION: The sheet folding device includes a plurality of fore end stopper means 141 for holding a deflection part by a roller by deflecting a sheet to determine the folding position in the conveying direction, folding roller pairs 111 which are butted to the stopper means 141 to form the deflection, conveying roller pairs 503 for conveying the sheet toward the folding roller pairs 111, and resist roller pairs 502 for correcting any skew of the sheet to be conveyed by the conveying roller pairs 503. A guide roller 504 is coaxially supported on one side of the resist roller pairs. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sheet folding apparatus and an image forming apparatus, and more particularly to a sheet conveying mechanism including a folded sheet.

  A post-processing device attached to the image forming apparatus in addition to a case where a sheet such as a recording sheet printed out by an image forming apparatus such as a copying machine, a printer, or a printing machine is discharged from the image forming apparatus. In some cases, various folding processes may be performed via the.

  For folding, as shown in FIG. 3, there is one fold line, two folds that are simply folded in two, three fold lines that are folded inwardly and two fold lines are folded inward, Z-shaped There are Z-folding that folds into two, simple four-folding that folds the folded surface further inward, and quadruple folding that can be folded inward by attaching a fold line to each of the folded surfaces.

  The folding process includes a conveying roller that conveys the sheet to be folded and a damming member that stops the leading edge of the sheet, and the sheet continues to be conveyed with the leading edge abutting the damming member. There is a configuration in which a step of making a crease is repeated when a buckling deformed portion that is generated when being conveyed is conveyed by a conveying roller (for example, Patent Document 1).

  On the other hand, as a configuration of the sheet discharge portion subjected to the folding process, there is a configuration in which the discharge portion is differentiated by distinguishing between the case where the folding process is performed and the case where the folding process is not performed (for example, Patent Document 2). .

  On the other hand, the folding process is performed after the image forming process for the sheet to be folded. In the sheet conveyance process, the skew (skew) in the conveyance direction is corrected by, for example, stopping the leading edge of the sheet. To be done. The purpose of this is to prevent wrinkles and deterioration of folding accuracy when folding is performed while skewed.

As a configuration for correcting the skew of the sheet, the driving state of the folding roller and the driven roller used for the folding process is controlled in a state where the leading edge of the sheet conveyed to the folding position is stopped, so that the sheet is stopped. A configuration in which a sheet is held at a nip portion of each roller to perform skew correction has been proposed (for example, Patent Document 3).
As another configuration, there is a configuration in which a registration roller used in the conveyance path is used instead of the folding roller and the driven roller (for example, Patent Document 4).

  In order to ensure folding accuracy, for example, when the configuration disclosed in Patent Document 3 is used, when performing skew correction by abutting the leading end of the sheet against a pair of registration rollers, the code used in this embodiment is used. As illustrated in FIG. 28, when the skew correction resist driven roller 502A2 of the registration roller pair 502 and the driven roller 111A2 of the folding driven roller 111 located in front of the skew correction resisting roller 502A2 are slanted in the conveying direction. (In FIG. 28, it is indicated as oblique bending), and the oblique bending may be introduced into the folding roller. For this reason, there exists a possibility that the generation | occurrence | production of a wrinkle and folding accuracy may deteriorate.

  In view of the problems in the conventional sheet folding apparatus, an object of the present invention is to provide a sheet having a configuration capable of reliably preventing skew in the sheet conveyance direction and preventing deterioration of folding and folding accuracy. An object of the present invention is to provide a folding device and an image forming apparatus.

In order to achieve this object, the present invention has the following configuration.
(1) In a sheet folding apparatus that folds a sheet discharged from an image forming apparatus by holding it between a pair of folding rollers,
A plurality of front end stopper means for holding the bent portion between the rollers by bending the sheet and determining the folding position in the conveying direction;
A pair of folding rollers that form deflection by abutting against the stopper means;
A pair of conveying rollers for conveying the sheet toward the pair of folding rollers;
A registration roller pair that corrects skew of the sheet conveyed by the conveyance roller pair,
A sheet folding apparatus, wherein a guide roller is coaxially supported on one side of the registration roller pair.

(2) The sheet folding device according to (1), wherein the guide roller is disposed inside the registration roller in the axial direction.

(3) The sheet folding apparatus according to (1) or (2), wherein the guide roller is made of a low friction material.

(4) The sheet folding apparatus according to (1) or (2), wherein the guide roller has a fluorine coating portion.

(5) The sheet folding apparatus according to (1) or (2), wherein the guide roller is hollow.

(6) The sheet folding apparatus according to (1) or (2), wherein the guide roller is configured by a bearing member.

(7) The sheet folding apparatus according to (1) or (2), wherein a plurality of the guide rollers are provided on an axis of one of the registration roller pairs.

(8) One of the registration roller pairs on which the guide rollers are coaxially supported is provided so as to be able to contact and separate from the other of the registration roller pairs by a driving means. (1) to (7) The sea folding device according to any one of the above.

(9) The conveyance path for conveying the sheet toward the folding roller is provided with a registration detection unit on the upstream side in the sheet conveyance direction with respect to one of the registration roller pairs. The sheet folding apparatus according to (1), wherein the row state can be detected.

(10) An image forming apparatus using the sheet folding apparatus according to any one of (1) to (9).

(11) The image forming apparatus according to (10), wherein the sheet folding apparatus is provided in a sheet post-processing apparatus.

  According to the present invention, since the registration roller is provided separately from the registration roller pair for the conveyed sheet, the sheet can be flattened by each roller and the roller, thereby preventing the sheet from being bent. can do.

  Further, according to the present invention, since the registration rollers are arranged on the inner side of the registration roller pair in the axial direction of the registration roller pair and are made of a low friction material, in the sheet width direction corresponding to the direction perpendicular to the sheet conveyance direction. It is possible to reliably contact the inside of the registration roller pair, and it is possible to prevent conveyance resistance when contacting for flattening.

1 is a schematic diagram illustrating a system configuration of an image forming apparatus to which a sheet folding device according to the present invention is applied. It is a schematic diagram for demonstrating the principal part structure of the sheet folding apparatus which concerns on this embodiment. It is a schematic diagram for demonstrating the process of the double folding mode by the sheet folding apparatus shown in FIG. FIG. 4 is a diagram for explaining a sheet conveyance state at a stage that is continuously executed from the process illustrated in FIG. 3. FIG. 5 is a view for explaining a sheet conveyance form at a stage further advanced from the process shown in FIG. 4. FIG. 6 is a diagram for explaining a sheet conveyance state at a stage advanced from the process illustrated in FIG. 5. FIG. 7 is a diagram for explaining a sheet conveyance mode in a stage that is continuously executed from the process illustrated in FIG. 6. FIG. 8 is a diagram for explaining a sheet conveyance process in a stage that is continuously executed from the process illustrated in FIG. 7. It is a schematic diagram for demonstrating one process of the Z folding mode by the sheet folding apparatus shown in FIG. FIG. 10 is a diagram illustrating a sheet conveyance process at a stage advanced from the process illustrated in FIG. 9. FIG. 11 is a diagram for explaining a sheet conveyance process at a stage advanced from the process illustrated in FIG. 10. FIG. 13 is a diagram for explaining a sheet conveyance process at a stage advanced from the process illustrated in FIG. 12. FIG. 13 is a diagram for explaining a sheet conveyance process in a process continuously executed from the folding process illustrated in FIG. 12. It is a figure which shows the conveyance state of the sheet | seat in the step advanced from the process shown in FIG. It is a figure which shows the conveyance state of the sheet | seat in the step advanced from the process shown in FIG. FIG. 16 is a diagram illustrating a sheet conveyance state at a stage advanced from the process illustrated in FIG. 15. It is a figure which shows the conveyance state of the sheet | seat in the step advanced from the process shown in FIG. It is a figure which shows the conveyance state of the sheet | seat in the step advanced from the process shown in FIG. It is a schematic diagram for demonstrating one process of the Kannon four-fold mode by the sheet folding apparatus shown in FIG. FIG. 20 is a diagram illustrating a sheet conveyance state at a stage advanced from the position illustrated in FIG. 19. FIG. 20 is a diagram illustrating a sheet conveyance state at a stage advanced from the position illustrated in FIG. 19. It is a figure for demonstrating the structure of the characteristic part in this embodiment. It is a figure which shows the partial modification of the structure used for the characteristic part shown in FIG. It is a figure which shows another modification of the structure used for the characteristic part shown in FIG. It is a figure which shows the drive structure used for the characteristic part shown in FIG. It is a typical block diagram for demonstrating the control structure which makes object the characteristic part shown in FIG. It is a schematic diagram which shows the modification regarding the application example of the sheet folding apparatus shown in FIG. It is a figure equivalent to FIG. 22 for demonstrating the problem in a prior art example.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 shows an image forming apparatus 1000 provided with a sheet folding apparatus according to the present invention. The image forming apparatus 1000 is continuous with a post-processing apparatus 1001 equipped with a sorter and a binding apparatus. 1002 is mediated.

FIG. 2 is a schematic diagram showing a main configuration of the sheet folding apparatus 1002.
In FIG. 2, the sheet folding apparatus 1002 is provided with a branch portion in which a first switching claw 121 is arranged in the middle of a discharge path EP for discharging a sheet such as recording paper introduced from the sheet receiving portion IP in FIG. The first transport path 101 is continuous at a position branched from the paper discharge path EP via the branch portion.

  In the middle of the first conveyance path 101, a second switching claw 126 capable of switching between an introduction direction to a folding roller, which will be described later, and an introduction direction to the second conveyance path 102 is disposed. The second conveyance path 102 is provided continuously with the first conveyance path 101.

  The continuous position of each of the first and second transport paths 101 and 102 is located at the first transport path 101 at a position where the sheet moving direction can be switched to a different direction from the second transport path 102 by the second switching claw 126. A first folding roller 111 having a part of the peripheral surface thereof and a second folding roller 112 capable of nipping and conveying the sheet are disposed opposite to the first folding roller 111.

  A sheet is discharged from the first nip portion P1 with a first nip portion P1 corresponding to a first clamping portion configured by the first folding roller 111 and the second folding roller 112 facing each other. The third conveyance path 103 and the fourth conveyance path 104 are merged on the side, and a third switching claw 125 (see FIG. 4) capable of switching the moving direction of the sheet is disposed at the merge position. Has been. The second conveyance path 102 that is continuous with the first conveyance path 101 is provided with a fourth switching claw 126 that guides the sheet to either the second conveyance path 102 or the first folding roller 111. ing.

  A third folding roller 113 capable of sandwiching a sheet introduced from the third conveying path 103 is opposed to the second folding roller 112, and the second nip portion P2 is formed between the second folding roller 112 and the second folding roller 112. It is composed.

The middle of the fourth transport path 104 is branched, and the fifth transport path 105 is continuous at the branch position.
A fourth switching claw 122 for switching the moving direction of the sheet is disposed at the joining position of the fourth conveyance path 104 and the fifth conveyance path 105.

  Further, the fourth conveyance path 104 is branched in the middle thereof, and an extended end of the branched sub-conveyance path 104 </ b> A joins the fifth conveyance path 105.

  A fourth folding roller 114 capable of sandwiching and transporting the moving sheet is disposed at the branch position of the fourth transport path 104 and the sub-transport path 104A. The fourth folding roller 114 includes: A fifth folding roller 115 that is positioned on the side of the sub-conveying path 104A and capable of nipping and conveying the sheet is in contact with the sheet. A transport roller 116 is provided in front of the branch position of the fourth transport path 104 with respect to the sub-transport path 104A so as to face and contact the fourth folding roller and to sandwich and transport the sheet.

  A seventh conveyance path 107 continuous with the sheet accommodating portion 131 is joined to the end portion in the extension direction of the sixth conveyance path 106, and the moving direction of the sheet is defined between the accommodating portion 131 and the sheet discharge path at this merging position. A fifth switching claw 123 for switching to EP is disposed.

In the second conveyance path 102, the third conveyance path 103, and the fourth conveyance path 104, first to third stoppers 141 to 143 that stop the leading edge or the folding position of the sheet are provided in the extending direction of the conveyance path. It is provided so that it can move along.
Each of the stoppers 141 to 143 can be moved to a position where the leading end position of the sheet and the folding position can be stopped in each conveyance path in accordance with information on the sheet length and the folding position in a control unit (not shown).

On the other hand, the first conveyance path 101 is provided with first and second skew correction rollers 501 and 502 for correcting and correcting the skew of the introduced sheet. These first and second skew correction rollers are arranged. As will be described in detail later, it is composed of a pair of registration rollers. In addition, near the second nip portion P2, a not-shown quadrant folding guide for use in performing quadrant folding is provided.
In FIG. 2, reference numeral 500 indicates a hitting roller.

The first to third switching claws 121, 126, 125 and the fourth and fifth switching claws 122, 123 are set as the initial positions shown by solid lines in FIG. 1.
That is, the first and second switching claws 121 and 126 are set to guide the sheet introduced from the sheet receiving portion IP toward the first conveyance path 101, and the third switching claw 125 is set to the first and first switching claws 125. The direction of guiding the sheet moving from the nipping nip P <b> 1 of the second folding rollers 111 and 112 toward the third conveyance path 103 is set, and the fourth switching claw 122 guides the sheet toward the fourth conveyance path 104. The fifth switching claw 123 is set to guide the sheet toward the seventh conveyance path.
The direction of each switching claw is switched according to a sheet folding mode to be described later.

  As shown in FIG. 3, the sheet folding apparatus 1002 having the above-described configuration can perform various folding processes such as bi-folding, Z-folding, outer tri-folding, inner tri-folding, simple four-folding, and Kannon quadruple folding. Yes, each of these folding processes is performed by the selection of a conveyance path and a conveyance procedure using each folding roller described below. In the following description, the arrows indicating the moving direction of the sheet in the sheet receiving unit IP and the discharge unit EP are omitted, and some symbols other than members related to the folding mode are omitted. Set aside.

(A) Folding The folding process uses the procedure shown in FIGS.
(A-1)
In FIG. 4, the first switching claw 121 is set in the direction for guiding the sheet toward the first conveyance path 101, and the second switching claw 126 is set in the direction for introducing the sheet into the second conveyance path 102. The set sheet introduced from the sheet receiving unit IP is conveyed to the second conveyance path 102 via the first conveyance path 101. At this time, in the second conveyance path 102, as shown in FIG. 5, the first stopper 141 is positioned so that the leading edge of the sheet corresponds to the folding position.
(A-2)
As shown in FIG. 5, the sheet conveyed toward the second conveyance path 102 passes through the first folding roller 111 and is introduced into the second conveyance path 102. In the second conveyance path 102, the position of the first stopper 141 is set in order to define the leading edge of the sheet at a position corresponding to the introduced sheet folding length, and the leading edge of the sheet is stopped by the first stopper 141. Is done.
When the conveyance of the sheet is continued, as shown in FIG. 6, the sheet whose tip is stopped is bent and deformed in the vicinity of the first nip portion P1 to form a bulge.
(A-3)
As shown in FIG. 7, when a state in which the sheet bulges in the vicinity of the first nip portion P <b> 1 is obtained, the second fold roller 112 rotates with the first fold roller 111, thereby causing the sheet bulge portion. Is nipped and conveyed so as to be introduced into the fifth nip portion P2.
Note that the conveyance amount up to the stop position at the leading end of the sheet and the conveyance amount for causing the bulge are set by controlling the rotation amount of each conveyance roller and folding roller in the control unit.
(A-4)
As shown in FIG. 8, the sheet that is nipped and conveyed while being folded between the first folding roller 111 and the second folding roller 112 is introduced into the sixth conveyance path 106 and the fifth switching is performed. It is conveyed toward the discharge part EP through the guide of the claw 123.

(B) Z-folding For this folding process, the procedure shown in FIGS. 9 to 12 is used.
(B-1)
In this case, the first switching claw 121 is similar to the state shown in FIG. 1, while the second switching claw 126 directs the sheet toward the first nip portion P1 as shown in FIG. The position to be introduced is set, and the third switching claw 125 is set in a direction to introduce the sheet into the third conveyance path 103, and the fourth switching claw 122 further sets the sheet to the fourth conveyance path 104. It is set to the direction of introduction.
As shown in FIG. 10, the sheet is introduced into the first conveyance path 101 by setting the positions of the first switching claw 121 and the second switching claw 126, and the leading end of the sheet is guided to the second switching claw 126. As a result, the first folding roller 111 and the second folding roller 112 pass through the first nip portion P1.
(B-2)
When the sheet that has passed through the first nip portion P1 is continuously conveyed in a state in which the leading end is stopped by the second stopper 142 that has been moved to a position where the fold position of the sheet can be set, it is shown in FIG. Thus, a bulge is formed in the vicinity of the position that has passed through the first nip portion P1.
(B-3)
The sheet bulge enters the second nip portion P2 formed by the second folding roller 112 and the third folding roller 113 by continuing the conveyance of the sheet, and the fold portion is shown in FIG. As shown, it passes through the third nip portion P3 and is hit by a fourth stopper 143 located in the fourth transport path 104.
(B-4)
When the sheet in the state shown in FIG. 12 is further conveyed, as shown in FIG. 12, the sheet is composed of a fourth folding roller 114 located in the fourth conveying path 104 and an opposing roller thereof. By entering the fourth nip portion P4, a new crease different from the crease stopped by the fourth stopper 143 is formed and conveyed toward the sixth conveyance path 106. As a result, the sheet is conveyed in a Z-folded state with a crease at a position opposite to the fold formed first.

(C) Outer tri-fold, inner tri-fold, simple quad fold Of these folds, the procedure up to the first crease is the same as in the case of bi-fold. A second crease process is performed.
(C-1)
At the time of the second crease processing, the third switching claw 125 is set in advance so as to introduce the sheet into the third conveyance path 103.
FIGS. 13 and 14 show the middle of the first crease process in the case of performing the inner trifold. In FIG. 13, the tip of the second conveying path 102 is blocked by the first switching claw 141. As the conveyed sheet continues to be conveyed, as shown in FIG. 14, the sheet bulges in the vicinity of the first nip portion P1.
(C-2)
As shown in FIG. 15, the sheet bulge passes through the first nip portion P <b> 1 due to continuous conveyance, and the fold position is introduced into the third conveyance path 103 and is stopped by the second stopper 142. The
(C-2)
If the conveyance is continued in a state where the first fold position is stopped by the second stopper 142, the sheet swells at the position where it has passed through the first nip portion P1, as shown in FIG.
(C-3)
If conveyance of the sheet in which the swelling has occurred is continued, the second crease process is performed when the sheet passes through the second nip portion P2 constituted by the second folding roller 112 and the third folding roller 113. Then, as shown in FIG. 17, the sheet is conveyed toward the fifth conveyance path 105 via the fifth switching claw 122 that has been switched in advance in the sheet introduction direction to the fifth conveyance path 105. The
(C-4)
The sheet introduced into the fifth conveyance path 105 is moved to the seventh conveyance path 107 by the fifth switching claw 123 in which the direction in which the sheet is introduced in advance toward the seventh conveyance path 107 is set. As shown in FIG. When post-processing is required, the direction of the fifth switching claw 123 is directed toward the discharge path EP, and thus moves toward the discharge path EP.
It should be noted that the folding state of the sheet used to explain the inner trifold is neglected with respect to the length of the piece, with the folding direction in the folding state shown in FIG. 3 being the same state in order to avoid the complexity of the drawing. is doing.

(D) Kannon quadruple folding This folding process is performed three times as shown in FIG. For this reason, the second folding process is performed by the same procedure as the case of Z-folding listed in (B), outer tri-folding, inner tri-folding, and simple four-folding listed in (C).

FIGS. 19 to 21 show a state in which the sheet subjected to the second folding process is subjected to the third folding process in the fourth conveyance path 104.
(D-1)
In this case, as shown in FIG. 19, the fourth switching claw 122 passes through the second nip portion P2 constituted by the second folding roller 112 and the third folding roller 113, and then the fourth switching claw 122 A sheet is introduced into the conveyance path 104.
In the 4th conveyance path 104, the 3rd stopper 143 is positioned so that the 3rd folding position may be acquired previously.
(D-2)
As shown in FIG. 20, the sheet that has passed through the second nip portion P2 and the folding position is stopped by the third stopper 104 is continuously conveyed, as shown in FIG. It swells toward the fourth nip portion P4 constituted by the folding roller 115.
(D-3)
The swelled portion of the sheet is subjected to a third crease when passing through the fourth nip portion P4 by continuing the conveyance of the sheet.
(D-4)
As shown in FIG. 21, the sheet subjected to the third crease process moves from the fourth nip portion P4 toward the sub-transport path 104A continuous to the fourth transport path 104, and the sixth transport path. When transported toward 016, depending on the contents of the subsequent processing, the discharge path EP to the post-processing apparatus or the seventh transport path 107 is directed to the accommodating portion 131 via the fifth switching claw 123. Are transported.

The features of the present embodiment will be described as follows for the conveyance mode of the sheet subjected to the folding process as described above.
A feature of the present embodiment lies in correction of skew of a sheet by a conveying member used for a pre-stack in which sheets are stacked and stacked at the time of sorting or binding performed after folding operation.

In the present embodiment, the first and second transport paths 101 and 102 correspond to the positions where the pre-stacking is performed. That is, the conveyance path provided at the position immediately before the crease processing is used for the prestack.
As for the sheet, the first stopper 141 provided in the second conveyance path 102 is positioned, and the sheets that are stopped by the stopper 141 are accumulated.

For correcting the skew of the sheet, one of the first and second skew correction rollers 501 and 502 arranged in the first conveyance path 101 is positioned upstream of the first folding roller 111 in the sheet moving direction. A skew correction roller 502 is used.
The skew correction roller 502 is composed of a pair of registration rollers that can be rotated and stopped. One of the skew correction rollers 502 is driven on the side of the sheet conveyance path (hereinafter also referred to as a skew correction registration drive roller for convenience), and the other is driven. It is a driven roller (hereinafter also referred to as a skew correction resist driven roller for convenience) that moves to the side.

  FIG. 22 is a schematic diagram for explaining the characteristic part in the present embodiment, and this figure shows the second skew arranged on the upstream side with respect to the first folding roller 111 in the sheet movement direction (conveyance direction). A view of the roller 502 as viewed from the front surface side of the sheet S in the first conveyance path 101 is indicated by (A), and in (A), an arrow view in the direction indicated by reference numeral (B) is indicated by (B). It is shown.

In the first conveyance path 101, the skew correction roller including a pre-stack movement conveyance roller 503 and a registration roller pair in order from the upstream side in the sheet movement direction until the sheet S reaches the first folding roller 111. 501, 502 and the first folding roller 111 are arranged.
Although the first and second skew correction rollers 501 and 502 have the same configuration, the second skew correction roller 502 will be described below. As shown in FIG. The skew correction registration driving roller 502A1 and the skew correction registration follower roller 502A2 which are opposed to each other are sandwiched therebetween.

In the present embodiment, a guide roller 504 that is coaxially supported by the rotation shaft 501B on the skew correction registration driven roller 502A2 side is provided.
The guide roller 504 is disposed on the inner side of the skew correction registration driven roller 501A2 in the axial direction of the rotation shaft 502B on the skew correction registration driven roller 501A2.

Since the present embodiment is configured as described above, it is possible to correct sheet skew (skew) for the following reason.
Prior to the correction of the skew, the cause of the skew will be described as follows.
As shown in FIG. 28, with respect to the attachment interval (L) of the conveyance roller 503 in the axial direction of the conveyance roller 503, the skew correction registration driven roller 501A2 of the skew correction roller 502 in the axial direction is targeted. While the mounting interval (L + α) is larger and it is possible to eliminate the problem that it is not possible to handle a sheet with a large sheet width as in the case where the mounting interval between the rollers is set, a conveyance force for the sheet is given. As a result, unevenness occurs in the position where the sheet is fed, and the sheet is likely to be skewed (skew) because a uniform conveying force cannot be obtained in the axial direction.

On the other hand, in the vicinity of the first folding roller, there is a case where a folding blade (not shown) is arranged so as to guide the sheet to a position exceeding the nip portion of the folding roller.
When folding multiple sheets at the same time, the folding blade only folds the outermost sheet that is in direct contact with the folding roller. The purpose of this is to enable the nip action on the sheet to be folded over by forcibly guiding it.

However, a so-called relief portion is provided on the folding roller side so as not to cause the nip action of the sheet at the position where the folding blade enters the nip portion. For this reason, a nip portion and a non-nip portion are generated in the width direction of the sheet, and this causes a deviation in the sheet conveyance speed, so that the skew of the sheet is likely to occur.
For this reason, skew (skew) generated on the sheet is further fed while the skew correction resist correction roller is stopped, and the skew is corrected in the width direction. Is done.

  However, skew (skew) may recur until the sheet fed from the skew correction registration driven roller reaches the folding roller. This is because the nip portion of the folding roller is one place, and there are not provided multiple positions where the folding roller and the sheet contact in the width direction. The cause is that unevenness is suppressed. That is, when one nip portion is provided, the sheet is likely to be displaced obliquely with respect to the conveying direction with the position as a reference point.

Therefore, in this embodiment, a guide roller is provided separately from the skew correction resist driven roller so as to eliminate the inclination in the width direction with respect to the sheet entering the folding roller.
As a result, the sheet is flattened before entering the folding roller, and is prevented from being inclined in the width direction by the guide roller added to the skew correction resist driven roller. In other words, by increasing the nip portion, it is possible to prevent the inclination in the width direction of the sheet that occurs when the nip is performed at one place.

  In addition, as shown in FIG. 22, the guide roller 504 is arranged at a position equally divided within the axial length of the folding roller 111 with the axial center of the folding roller 111 as a boundary, so that the folding roller 111 Since the nip portion can be increased at a position close to the center of the axial length, it is possible to easily suppress the sheet from tilting in the width direction.

  This is because the skew correction roller 502 disposed near the folding roller 111 in the sheet conveyance direction is used as a target, and the contact is made at a position where the inclination angle becomes smaller as the distance from the folding roller 111 is shorter. Therefore, even if an inclination in the width direction of the sheet using the center of the axial length of the folding roller 111 as a fulcrum occurs, the inclination is reduced by receiving resistance due to contact with the guide roller 504, and skewing can be suppressed. .

  In this embodiment, the contact condition between the guide roller 504 and the sheet includes that the sheet can be flattened and that skew (skew) can be prevented. Therefore, the following structure is adopted as the structure of the guide roller 504. ing.

  First, the outer diameter of the guide roller 504 is slightly smaller than the outer diameter of the skew correction resist driven roller 502A.

  Second, the guide roller 504 is made of a low friction coefficient material.

  Third, a surface coated with fluorine as a low friction coefficient material.

  Fourthly, as shown in FIG. 23, the guide roller 504 is a hollow member.

  Fifth, a bearing member that supports the rotation shaft 502B of the skew correction roller 502 is used as the guide roller 504.

  Sixth, as shown in FIG. 24, a plurality of skew correction rollers 502A2 are arranged inside the skew correction roller 502A2 in the axial direction of the skew correction roller 502. In this case, the folding rollers 111 are arranged so as to be allocated to the positions for the time being centered on the axial length center.

Seventh, as shown in FIG. 25, the skew registration driven roller 502A2 in which the guide roller 504 corresponds to one of the skew correction rollers 502 is received by a link lever 505 that can swing by receiving a driving force from a driving motor. The skew correction driving roller 501A1 corresponding to the other of the skew correction rollers 502 can be contacted and separated.
That is, in FIG. 25, the skew correction registration driven roller 502A2 is disposed in contact with the skew correction drive roller 501A by an urging means (not shown).
The rotation end 502B of the skew correction registration driven roller 502A2 is in contact with the swing end of a displacement lever 505 provided so as to be swingable. The displacement lever 505 is a base portion mounted on the support shaft 505A. A sector gear 505B is formed on the peripheral surface.
The sector gear 505B meshes with one of a reduction gear group 507 that receives a driving force from a driving gear 506A that is coaxially supported with a pulley 506 that is interlocked with the driving motor M.
The drive motor M is configured such that the amount of rotation is changed between when a single sheet is folded and when a plurality of sheets are folded together, and FIG. 25A shows a case where a single sheet is folded. FIG. 25B shows the case of overfolding.

  As a result, when the sheet targeted for one sheet is moved, the guide roller 504 is brought into contact with the sheet, whereby the sheet can be flattened and the inclination in the width direction can be suppressed. In the case of folding, a passage for temporarily stacking the sheets can be formed.

Eighth, the guide roller 504 and the skew correction registration driven roller 502A1 that is coaxially supported with the guide roller 504 rotate only when the sheet is skewed (skew).
FIG. 26 is a diagram showing a configuration for this purpose. In FIG. 26, a sensor capable of detecting when the sheet is skewed (skewed) in the width direction on both sides of the conveying roller 503 in the sheet width direction. 510 is arranged, and the sensor 510 is connected to the controller 600 of the drive motor M that rotationally drives the rotation shaft 502B of the skew correction registration driven roller 502A2.

The controller 600 outputs a rotation drive signal when the skew of the sheet is detected. As a result, when the skew (skew) of the sheet occurs, the guide roller 504 rotates together with the skew correction registration roller 502A2 so that the sheet can be flattened and skewed by light contact can be suppressed. .
With the configuration related to the guide roller 504 as described above, the sheet is flattened by the guide roller, and further the light contact makes it possible to suppress the inclination in the width direction of the sheet. As a result, the sheet does not bend obliquely, so that the occurrence of creases during folding can be reliably prevented.

  The sheet folding apparatus 1002 as described above is used by being attached to the post-processing apparatus attached to the image forming apparatus shown in FIG. 1, and may be included in the sheet post-processing apparatus 1001 as shown in FIG. Is possible. In other words, when the sheet folding apparatus 1002 is provided in the sheet processing apparatus 1001 having a post-processing function, the sheet folding apparatus 1002 is attached to the image forming apparatus 1000, and the sheet post-processing apparatus 1001 equipped with the sheet folding apparatus 1002 is used as the image forming apparatus. 1000 can be attached.

DESCRIPTION OF SYMBOLS 100 Sheet folding apparatus 201 1st folding roller 202 2nd folding roller 203 3rd folding roller 204 4th folding roller 205 1st nip part 206 2nd nip part 207 3rd nip part 700 Stack part 700B Tray 702 Paper surface Detection sensor 705 Control unit 1000 Image forming apparatus 1001 Post-processing apparatus θ1, θ2 Inclination angle

JP 2004-284742 A JP 2006-76779 A JP 2006-117383 A JP 2005-8333 A

Claims (11)

In a sheet folding apparatus for sandwiching a sheet discharged from an image forming apparatus between a pair of folding rollers and folding the sheet,
A plurality of front end stopper means for holding the bent portion between the rollers by bending the sheet and determining the folding position in the conveying direction;
A pair of folding rollers that form deflection by abutting against the stopper means;
A pair of conveying rollers for conveying the sheet toward the pair of folding rollers;
A registration roller pair that corrects skew of the sheet conveyed by the conveyance roller pair,
A sheet folding apparatus, wherein a guide roller is coaxially supported on one side of the registration roller pair.   The sheet folding apparatus according to claim 1, wherein the guide roller is disposed inside the registration roller in the axial direction.   The sheet folding apparatus according to claim 1, wherein the guide roller is made of a low friction material.   The sheet folding apparatus according to claim 1, wherein the guide roller has a fluorine coating portion.   The sheet folding apparatus according to claim 1, wherein the guide roller is hollow.   The sheet folding apparatus according to claim 1, wherein the guide roller is configured by a bearing member.   The sheet folding apparatus according to claim 1, wherein a plurality of the guide rollers are provided on an axis in one of the registration roller pair.   8. One of the registration roller pairs on which the guide rollers are coaxially supported is provided so as to be able to contact with and separate from the other of the registration roller pairs by a driving unit. Sea folding device.   The conveyance path for conveying the sheet toward the folding roller is provided with a registration detection unit on the upstream side in the sheet conveyance direction with respect to one of the registration roller pairs, and the registration detection unit detects the skew state of the conveyed sheet. The sheet folding apparatus according to claim 1, wherein the sheet folding apparatus can be detected.   An image forming apparatus using the sheet folding apparatus according to claim 1.   The image forming apparatus according to claim 10, wherein the sheet folding apparatus is provided in a sheet post-processing apparatus.

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