JP5488023B2 - Sheet folding apparatus and image forming apparatus - Google Patents

Description

  The present invention means a plurality of sheet-like recording media (meaning all sheet-like recording media such as paper and OHP sheets. These are collectively referred to as “paper” in this specification). The present invention relates to an image forming apparatus such as a sheet folding apparatus capable of folding various types, a copying machine including the sheet folding apparatus, a printer, a facsimile, and a digital complex machine having a combination of these functions.

  Various folding processes capable of performing a plurality of types of folding processes on a sheet on which an image is formed by an image forming apparatus such as a copying machine have been proposed. The plural types of folding processes are, for example, two-fold, Z-fold, outer three-fold, inner three-fold, simple four-fold, and Kannon four-fold. These folds are performed by introducing a portion that becomes a fold of the sheet into the nip of the folding roller and passing through the nip of the folding roller.

  The folding rollers are set to have a number of nips corresponding to the maximum number of folds, and in the case of three folding, four or five folding rollers are used. The friction coefficient of the folding roller may be deteriorated due to factors with time due to the number of sheets passing, paper dust, or the like. The paper is bent at the folding roller placement position in the middle of the conveyance path by abutting the leading end against the stopper, and the bending is guided to the nip of the folding roller to perform the folding process. However, when the friction coefficient decreases, the paper is folded. Since it becomes difficult to be drawn into the nip of the roller, slip occurs. However, the sheet is conveyed without stopping. Therefore, the sheet does not wind around the folding roller 2 at the folding roller position, and a gap is left between the folding roller and the sheet. The sheet is conveyed while being lifted or bent by the gap between the nip part and the sheet.

  FIG. 9 is a diagram for explaining the relationship between a folding roller in the prior art (corresponding to a fourth folding roller in an embodiment described later) and a sheet, and FIG. 10 shows fourth and fifth folding rollers 24 and 25, and an opening / closing guide. 11 is a front view showing the relationship of the driven roller 68 with respect to the plate 75 and the fourth folding roller, and FIG. 11 is a perspective view of the conveyance guide plate viewed from the conveyance surface side. Hereinafter, the fourth folding roller will be described. This fourth folding roller is a roller used for Z-folding.

  In FIG. 9, the Z-fold paper 74 in which a fold is formed at a position ¼ from the leading edge of the paper by a second folding roller and a third folding roller (not shown) is driven by the fourth folding roller 24 and the fourth folding roller 24. When transported by the roller 68, the Z-fold paper 74 is nipped by the driven roller 68 with respect to the fourth folding roller 24. In this state, the Z-fold paper 74 is separated from the fourth folding roller 24 except for the portion where the folding roller 24 and the driven roller 68 are nipped. As described above, since the Z-fold paper 74 is not conveyed in close contact with the outer peripheral surface of the fourth folding roller 24, the paper 74 or the sheet bundle is conveyed between the outer peripheral surface of the fourth folding roller 24. For this purpose, an opening / closing guide 75 is provided after securing a clearance (hereinafter referred to as a conveyance clearance).

  Further, when the friction coefficient decreases due to deterioration of the fourth folding roller 24 and the fifth folding roller 25, dirt due to paper dusting, etc., the paper is separated from the outer peripheral surface of the second folding roller 24 as shown in FIG. 10: Q portion), it becomes impossible to properly enter the nip of the fourth and fourth folding rollers 24, 25 (FIG. 10: P portion). For this reason, the Z-fold fold cannot be formed with high accuracy, creases occur, and quality may be degraded.

  The open / close guide plate 75 is provided in the case where a paper jam occurs in the immediate vicinity of the fourth folding roller 24 on the upstream side in the paper conveyance direction so that the conveyance path space (conveyance gap) between the outer peripheral surface of the roller and the guide plate can be increased. It is called like this because it can be opened and closed.

  On the other hand, the invention described in Patent Document 1 or 2 is known as this type of technology. Among them, Patent Document 1 (Japanese Patent No. 3817424) discloses a purpose of enabling stable and highly accurate sheet folding processing that prevents folding and causes less instability and poor conveyance during sheet stacking. A pair of folding rollers for performing a folding process while nipping and conveying the sheet, wherein at least one roller of the pair of folding rollers includes a single large-diameter portion and both sides of the large-diameter portion along the axial direction of the roller. In the invention, the small diameter portion is provided corresponding to the sheet width in the axial direction of the folding roller pair of the sheet that can be folded. At this time, in order to prevent the generation of wrinkles, a gap is made except for the central part of the nip of the folding roller.

  Further, in Patent Document 2 (Japanese Patent No. 4238777), it is difficult to produce a high-quality folded sheet because the conveyance of the sheet is not stable, the fold position is shifted, or wrinkles are generated. In order to solve this problem, a pair of upstream folding rollers composed of a folding roller and a pressure roller in pressure contact with the folding roller, and a pair of downstream folding rollers composed of a folding roller and a pressure roller in pressure contact with the folding roller. , The sheet is nipped by the two folding roller pairs, the sheet is conveyed in the first direction by the upstream folding roller pair, and the downstream folding roller pair By conveying the sheet in the second direction opposite to the first direction, the sheet is folded, and the sheet is conveyed by the two folding roller pairs with the crease portion at the head. In the folding device having a folding section for folding the sheet, the inner width of the sheet in the thickness direction of the conveying path is increased or decreased reversibly along the conveying path on the downstream conveying path of the pair of folding rollers on the downstream side. An invention in which a movable guide member to be changed is provided is described.

  In Patent Document 2, a pair of folding rollers is configured as a pair, and a driven roller is arranged for each folding roller. It is also described that the driven roller disposed corresponding to the folding roller on the downstream side in the conveying direction can be released from the nip.

  However, as shown in FIG. 9 and FIG. 10, when the sheet is conveyed around the fourth folding roller 24 without being wound around the fourth folding roller 24 as shown in FIGS. The lifted portion or the bent portion of the paper 74 is stiff due to the pressure action of the driven roller, and the stiffened portion 74a is bent and bent. This ironing causes iron marks 74b such as small folds and wrinkles as shown in FIG. 13 and damages the paper.

  Such ironing traces 74b can be prevented from being transported by being uniformly pushed into the nip if the entire width of the sheet is uniform and has a constant transport force. In order to generate a uniform and constant conveying force over the entire width of the sheet, the driven roller 68 may be formed in a solid shape over the entire width of the sheet as shown in FIG. However, when the roller shape is formed over the entire width, not only the cost is increased, but also the protrusions of the driven rollers 68 and 70 provided on the open / close guide plate 68 divide the open / close guide plate 75, and the structure of the open / close guide plate 75 Becomes complicated.

  Further, as shown in FIG. 15, by arranging a plurality of short fourth folding roller driven rollers 80, a uniform and constant conveying force can be obtained over the entire width of the paper. In the meantime, the floating and bending of the sheet cannot be eliminated, and the creased portion is bent and bent, resulting in a crease mark as shown in FIGS.

  In the invention described in Patent Document 1, the problem is not solved because there is a gap other than the central portion.

  In the invention described in Patent Document 2, the sheet is guided to the nip between the folding roller and the driven roller by the movable guide member, and consideration is given to the stability of sheet conveyance. The flatness when entering is not taken into consideration.

  Furthermore, in the invention described in Patent Document 2, the driven roller disposed corresponding to the folding roller on the downstream side in the transport direction can be released from the nip, and after the paper is nipped in the nip, the paper is separated from the folding roller. Can be done. As a result, the driven roller is not sticky, so it is effective to prevent the ironing mark from being left.However, since the paper is lifted or bent over the entire width of the paper, it causes a conveyance failure and a conveyance failure occurs. May cause wrinkles.

  In any case, in the prior art, it has not been possible to achieve both prevention of iron traces and prevention of conveyance failure.

  Therefore, the problem to be solved by the present invention is to achieve both the prevention of iron traces and the prevention of conveyance failure.

In order to solve the above-described problems, the present invention is configured to sandwich a sheet that has been carried in between a driven roller and one folding roller positioned upstream of the pair of folding rollers in the sheet conveying direction and guide the sheet to the nip of the pair of folding rollers. , a sheet folding apparatus that performs clamping to folding processing in the nip of the folding roller pair, made from a sheet-like member having elasticity, is provided with means pushing pressing the entire width of the sheet on the one folding row La that It is characterized by.

In the embodiments described below, the driven roller fourth folding roller driven roller 68, the pair of folding rollers fourth and fifth folding rollers 24 and 25 pairs, one folding row La and the fourth folding roller 24, the pressing means pressing member 74,74H, is the paper folding device code ZF, the image forming apparatus in PR, corresponding.

  According to the present invention, it is possible to achieve both the prevention of iron traces and the prevention of conveyance failure.

1 is a diagram illustrating a system configuration of an image forming apparatus according to an embodiment of the present invention. It is a perspective view of the opening-and-closing guide plate provided with the pressing member in this embodiment. It is a front view of the opening-and-closing guide plate in this embodiment. It is a front view which shows the closed state of the opening / closing guide plate of FIG. It is the figure which looked at the state at the time of paper pressing of the pressing member which has elasticity in this embodiment from the paper conveyance direction. It is the front view which looked at the state of Drawing 5 from the front. It is a front view of the opening-and-closing guide plate which decomposes | disassembles and shows the attachment state of a pressing member when the thin board which has rigidity in this embodiment is used with a pressing member. It is a front view which shows the initial state of the opening-and-closing guide plate provided with the thin plate-shaped pressing member shown in FIG. It is a figure for demonstrating the relationship between a folding roller and a paper in a prior art. It is a front view which shows the relationship between a 4th and 5th folding roller, an opening-and-closing guide plate, and a 4th folding roller driven roller. It is the perspective view which looked at the conveyance guide plate of FIG. 10 from the conveyance surface side. It is explanatory drawing which shows the state with the stiffness which is a problem of a prior art. It is explanatory drawing which shows the state of the ironing trace produced when the paper with a stickiness is pinched | interposed in nip. It is explanatory drawing for demonstrating a problem when a driven roller is formed in the solid shape covering the full paper width. It is explanatory drawing for demonstrating a problem when many short-width driven rollers are arrange | positioned and conveyed.

  In the present invention, a uniform and constant conveying force can be reliably obtained over a long period of time reliably over the entire width of the paper, and both the prevention of iron traces and the prevention of conveyance failure are achieved. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1. Overall Configuration FIG. 1 is a diagram showing a system configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus according to the present embodiment includes an image forming apparatus main body PR, a sheet folding apparatus ZF, and a sheet post-processing apparatus FR. The image forming apparatus main body PR is any one of a copying machine, a printer, a facsimile machine, and a digital multifunction machine having at least two of these functions in combination.

  If a sheet, in this case, an image-formed sheet conveyed from the image forming apparatus main body 3 needs to be folded by the sheet folding apparatus ZF, the folding process necessary for the sheet folding apparatus ZF is performed. If the folding process in the apparatus ZF is unnecessary, the sheet folding apparatus is bypassed and conveyed to the sheet post-processing apparatus FR. The sheet post-processing apparatus FR has a known function and mechanism, and can perform processes such as punching, alignment, edge binding, center folding, saddle stitching, and sorting.

  The sheet folding device ZF is provided with a horizontal conveyance path 13 for discharging the sheet straight from the sheet receiving port 13a to the sheet discharge port 13b. When folding the sheet, the first switching claw 31 is used to fold the sheet. The conveyance direction is changed to the folding processing unit side, and the folded sheet returns downstream from the installation place of the first switching claw 31 to the horizontal conveyance path 13 from the ninth conveyance path 9 to the sheet post-processing apparatus FR side from the discharge port. It is carried out.

  The conveyance path branched from the horizontal conveyance path 13 by the first switching claw 31 is the first conveyance path 1, the second conveyance path 2, the third conveyance path 3, the fourth conveyance path 4, the fifth conveyance path 5, and the sixth conveyance. It comprises a path 6, a seventh transport path 7, an eighth transport path 8, a ninth transport path 9, a tenth transport path 10, an eleventh transport path 11, and a paper discharge transport path 12. The first conveyance path 1 and the second conveyance path 2 are divided by a first fold nip between the first and second folding rollers 21 and 22, and the second conveyance path 2 and the third conveyance path 3 are first and third folds. The third conveyance path 3 and the fourth conveyance path 4 are divided at the third folding nip between the second and third folding rollers 22 and 23. The fourth conveyance path 4 and the fifth conveyance path 5 are divided by the second switching claw 32, and the sixth conveyance path 6 is divided by the third folding nip between the fourth and fifth folding rollers 24, 25, and the seventh The conveyance path 7 extends from a junction point downstream of the fifth and sixth conveyance paths 5 and 6 to the third switching claw 33, and the eighth conveyance path extends from the branch point of the third switching claw 33 to the fourth of the horizontal conveyance path 13. It extends to the switching claw 34. The ninth transport path 9 extends from the branch point of the third switching claw 33 to the paper discharge port of the horizontal transport path 13. The tenth transport path 10 is a transport path following the twelfth transport path 12 from the first switching claw 31, and is a junction point of the eleventh transport path 11 of the paper storage section discharge transport path 12 extending to the paper storage section (stack tray) 41. The part up to. The eleventh conveyance path 11 is a conveyance path that starts from the horizontal conveyance path 13 between the first switching claw 31 and the fourth switching claw 35 and continues to the discharge conveyance path 12, and the tenth conveyance path 10 and the discharge conveyance path. 12 junction points are terminated.

  The first switching claw 31 guides the paper supplied from the paper receiving port 13 a to the downstream side of the horizontal conveyance path 13, either the first conveyance path 1 or the tenth conveyance path 10. The first conveyance path 1 is provided with an overlap / fold order prevention mechanism 61 and a skew correction mechanism 65, and a conveyance roller pair for conveying the paper. A second conveyance path 2 communicating with the first conveyance path 1 on the downstream side of the first conveyance path 1 includes an overlapped folding sheet horizontal alignment mechanism (jogger) 67, an overlapped folding sheet vertical alignment mechanism (tapping roller) 66, and A first stopper 51 is provided.

  A third transport path 3 communicating with the first transport path 1 and the second transport path 2 is located upstream of the second transport path 2 (on the first transport path 1 side). Is provided with a second stopper 52. The third conveyance path 3 communicates with the fourth conveyance path 4 via the second folding nips of the second and third folding rollers 22 and 23, and the fourth conveyance path 4 includes a conveyance roller pair and a third stopper 53. Is provided. A first folding roller 21 and a second folding roller 22 are provided between the upstream side of the second conveyance path 2 and the upstream side of the third conveyance path 3, and in the vicinity of the first and second folding rollers 21 and 22. In addition, a folding blade 62 is provided opposite to the first folding nip, and an inner three-fold end turning prevention mechanism 63 is provided on the upstream side of the third conveying path 3.

  A sixth transport path 6 that branches from the fourth transport path 4 is provided at an intermediate portion of the fourth transport path 4. The sixth transport path 6 is connected to the upstream of the pair of exit transport rollers on the upstream side of the paper discharge port 13 b of the horizontal transport path 13 through the seventh transport path 7 and the ninth transport path 9. Between the 4th conveyance path 4 and the 6th conveyance path 6, the 4th folding roller 24 and the 5th folding roller 25 which form a 3rd folding nip are provided, and the 4th conveyance path which opposes this 3rd folding nip. On the side of 4, a four-folded folding tip turning prevention mechanism 64 is arranged. Further, an additional folding roller group 26 including a plurality of conveyance roller pairs is installed in the seventh conveyance path 7. In addition, a fourth folding roller driven roller 68 is disposed on the upstream side of the four-folded folding tip turning prevention mechanism 64 and downstream of the second switching claw 32.

  In the first to twelfth transport paths 1 to 12, a transport roller is appropriately disposed at a position necessary for transporting the paper, and it is intended that no paper jam occurs.

2. Folding operation With the above-described configuration, each folding operation of two-folding, Z-folding, outer three-folding, inner three-folding, simple four-folding, and four-tone folding is possible. Further, overlapping folding is also performed as necessary. Details of each folding operation will be described below.

2.1 Z-folding In Z-folding, the loaded paper is guided to the first transport path 1 by the first switching claw 31. The sheet passes through the first fold nip between the first fold roller 21 and the second fold roller 22, and the sheet leading end abuts against a second stopper 52 that can move to a fold position disposed in the third conveyance path 3. When the sheet hits the second stopper 52, the bent portion of the sheet enters the second folding nip between the second folding roller 22 and the third folding roller 23, and the first folding is performed. The first folded sheet is conveyed to the fourth conveyance path 4 by the second switching claw 32.

  When the leading edge of the sheet hits the third stopper 53 that can be moved to the folding position arranged in the fourth conveyance path 4, the sheet is bent in the space portion upstream of the nip between the fourth folding roller 24 and the fifth folding roller 25. Then, the bent portion is caused to enter the third folding nip between the fourth folding roller 24 and the fifth folding roller 25, the second folding is performed, and the Z-folding is completed. The sheet that has been Z-folded passes through the sixth transport path 6, the seventh transport path 7, and the ninth transport path 9, passes through the horizontal transport path 13, and is discharged from the paper discharge port 13b to the subsequent sheet post-processing device FR. Is done. At that time, the third switching claw 33 is switched to the side for guiding the sheet to the ninth transport path 9. As a result, the Z-fold downstream paper discharge process is performed. When the paper is discharged to the succeeding paper post-processing device FR, punch processing or the like can be executed by the paper post-processing device FR.

  On the other hand, when the third switching claw 33 has been switched to the guide side to the eighth conveyance path 8, the sheet passes through the eighth conveyance path 8, the fourth switching claw 34, and the fifth switching claw 35 to the eleventh. The paper reaches the transport path 11 and is discharged to the paper storage section 41 via the paper discharge transport path 12 to the paper storage section 41. Thereby, the Z-fold paper storage unit paper discharge process is performed.

2.2 Folding In the two-folding, the conveyed paper is guided to the second transport path 2 via the first transport path 1 by the first switching claw 31. When the leading edge of the sheet hits the first stopper 51 that can move to the folding position disposed in the second conveyance path 2, the space on the upstream side of the first folding nip between the first folding roller 21 and the second folding roller 22 The paper bends. As the bending progresses, the sheet enters the first folding nip, and the first folding is performed at the first folding nip, whereby the second folding is completed.

  After completion of folding, the sheet does not enter the third conveyance path 3, passes through the nip between the second folding roller 22 and the third folding roller 23, and is guided to the fifth conveyance path 5 by the second switching claw 32. The sheet is accommodated in the sheet accommodating portion 41 via the seventh conveyance path 7, the eighth conveyance path 8, the horizontal conveyance path 13, the eleventh conveyance path 11, and the paper discharge conveyance path 12. The third, fourth, and fifth switching claws 33, 34, and 35 are switched so that the conveyance path communicates.

2.3 Outer three-fold, inner three-fold, simple four-fold In these folding operations, the loaded paper is guided by the first switching claw 31 to the second transport path 2 via the first transport path 1. The When the leading edge of the sheet hits the first stopper 51 of the second conveyance path 2, the sheet bends in the same manner as when folded in half, and is folded in two at the first folding nip by the same operation and conveyed to the third conveyance path 3. Is done. When the leading edge of the sheet hits the second stopper 52 of the third conveyance path 3, the bent portion of the sheet enters the nip between the second folding roller 22 and the third folding roller 23 in the same manner as in the case of Z-folding. Folding is performed.

  At this time, the first stopper 51 and the second stopper 52 are stopped at controlled positions depending on the outer three, inner three, and simple four folding modes and the paper size, and the first and second folding positions are set. The folding direction is set. After the folding process is completed twice, the sheet is guided to the fifth conveyance path 5 by the second switching claw 32, and the seventh conveyance path 7, the eighth conveyance path 8, the horizontal conveyance path 13, and the eleventh conveyance path 11. The paper is stored in the paper storage unit 41 via the paper discharge conveyance path 12. The third, fourth, and fifth switching claws 33, 34, and 35 are switched so that the conveyance path communicates.

2.2.3 Quadrifold folding In quadrant folding, the loaded paper is guided to the second transport path 2 via the first transport path 1 by the first switching claw 31. When the leading edge of the sheet hits the first stopper 51 of the second conveyance path 2, the sheet bends in the same manner as when folded in half, and is folded in two at the first folding nip by the same operation and conveyed to the third conveyance path 3. Is done. When the leading edge of the sheet hits the second stopper 52 of the third conveyance path 3,
As in the case of Z-folding, the bent portion of the sheet enters the nip between the second folding roller 22 and the third folding roller 23, and the second folding is performed.

  The sheet is guided to the fourth conveyance path 4 by the second switching claw 32. When the leading edge of the sheet comes into contact with the third stopper 53 of the fourth conveyance path 4, the bent part of the sheet enters the third folding nip between the fourth folding roller 24 and the fifth folding roller 25 and moves toward the sixth conveyance path 6 side. Then, the third folding is performed, and the four-fold folding is completed. At the time of the third folding, the kannon quadruple tip turning prevention mechanism 64 operates to hold the bent portion. As a result, the leading edge and the trailing edge of the paper folded in the first folding and the second folding are pressed, and the third folding is performed without turning the paper edge.

  In the four-fold folding, one end is folded at the first folding nip and the other end is folded at the second folding nip. Finally, a so-called quadrant folding is completed in which the central portion is folded inward and both ends are folded toward the central portion.

  After the folding is completed, the folded sheet is guided to the sixth transport path 6 and passes through the seventh transport path 7 to the eighth transport path 8, the horizontal transport path 13, the eleventh transport path 11, and the discharge transport path. 12 through the paper storage unit 41.

2.2.4 Multiple sheets are folded and folded When the three sheets are folded and folded as an example, the first sheet is routed by the first switching claw 31 via the first transport path 1 and the second sheet. Guided to the transport path 2. The leading edge of the sheet comes into contact with the first stopper 51 of the second transport path 2 and stops. At this time, the leading edge of the sheet is reliably abutted against the first stopper 51 by the overlapping folded sheet vertical alignment mechanism (striking roller) 66. In this state, the overlapped folded sheet horizontal alignment mechanism (jogger) 67 executes the alignment operation in the sheet width direction. Next, the overlap folding order prevention mechanism 61 presses the rear end side of the sheet.

  The second sheet is guided to the second conveyance path 2 by the first switching claw 31 via the first conveyance path 1. Since the stacking / folding order preventing mechanism 61 presses the rear end side of the first sheet, the second sheet is conveyed so as to overlap the first sheet. When the leading edge of the second sheet hits the first stopper 51 disposed in the second conveyance path 2 and stops, vertical alignment and horizontal alignment are performed in the same manner as the first sheet, and one stacking folding order prevention mechanism 61 is provided. Hold the back edge of the second sheet. Similarly, the third sheet is aligned, and the folding blade 62 simultaneously pushes the third sheet into the nip between the first folding roller 21 and the second folding roller 22 to perform the first folding.

  At this time, the leading end of the folding blade 62 is pushed in until the nip position between the first folding roller 21 and the second folding roller 22 is exceeded. This eliminates the phenomenon that only the outermost sheet, for example, the third sheet, in contact with the folding roller is folded. The second and subsequent folding and discharging operations are the same as the folding and discharging operations.

3. 3. Pressing member 3.1 Example of biasing by elastic sheet member FIGS. 2 to 6 are views for explaining a pressing member that is a feature of the present invention. FIG. 2 is a perspective view of an opening / closing guide plate provided with a pressing member. The pressing member 73 is made of a sheet member such as PET paper, and is provided at the end of the opening / closing guide plate 69 on the downstream side in the sheet conveyance direction. It is provided over substantially the entire width of the sheet so as to cross the four-fold roller driven roller 68. As shown in the front view of the opening / closing guide plate in FIG. 3, the pressing member 73 is attached to the inclined recess portion 69b of the opening / closing guide plate 69 by sticking with a double-sided tape. Further, as shown in FIG. 2, a slit 73a is provided in a portion where the driven roller 68 of the fourth folding roller 24 is disposed, and the two driven rollers 68 can project from the slit 73a.

  The open / close guide plate 69 is swingably supported by a swing shaft 69a protruding from the end on the upstream side in the paper transport direction (upper side in the drawing) with respect to the fixed guide plate 72 of the fourth transport path 4, and is downstream in the paper transport direction. A magnet 76 provided at an end in the width direction (lower side in the drawing) is magnetically held when the stationary guide plate 72 formed of sheet metal is closed. A driving roller 71 is provided on the upstream side of the fixed guide plate 72 in the sheet conveying direction, and the open / close guide plate 69 includes two conveying driven rollers 70 at positions where the driving roller 71 can roll.

  4 is a front view showing the closed state of the opening / closing guide plate 69, FIG. 5 is a view of the pressing member when the sheet is pressed from the sheet conveyance direction, and FIG. 6 is a front view of the state of FIG. In these states, the conveyance driven roller 70 and the fourth folding roller driven roller 68 are pressed against the opposite conveyance driving roller 71 and the fourth folding roller 24 by a spring (not shown), and the conveyance driving roller 71 and the fourth folding roller 24 are pressed. When the roller 24 is driven to rotate, it follows the rotation. The pressing member 73 presses the sheet against the fourth folding roller 24. However, since the pressing member 73 is configured by a sheet member made of PET material, a certain pressure is applied to the sheet by bending.

  For example, when Z-folding is performed, the second folding roller 22 and the third folding roller 23 fold a quarter length of the paper length. Next, the leading end of the sheet in the conveyance direction comes into contact with the third stopper 53 stopped at a predetermined position, and bending occurs near the nip between the fourth folding roller 24 and the fifth folding roller 25, and the predetermined folding position is reached at the nip. A second fold is applied to the Z-fold. At that time, as shown in FIGS. 5 and 6, the Z-fold paper 74 is pressed against the fourth folding roller 24 by the pressing member 73 over the entire width of the paper. As a result, a uniform conveying force can be obtained over the entire paper width, and no bending or sheet floating occurs during conveyance at locations other than the fourth folding roller driven roller 68. As a result, the vertical wrinkles due to the driven roller 68 described with reference to FIGS. 12 and 13 do not occur, and naturally the ironing trace 74b does not occur.

3.2 Example of Energizing by Elastic Member As the pressing member, a thin plate member having rigidity can be used in addition to the PET material as described above. In this case, the sheet is surely pressed against the fourth folding roller, and an elastic member that elastically urges the thin plate-shaped pressing member toward the fourth folding roller is used to correspond to the thickness of the sheet.

  7 and 8 are for explaining an example in which a rigid thin plate is urged by the elastic member. FIG. 7 is an exploded view of the opening / closing guide plate 69 showing the attachment state of the thin plate-like pressing member 73H. FIG. 8 is a front view showing an initial state of the open / close guide plate 69 provided with a thin plate-like pressing member 73H. In these drawings, a protrusion 73Ha serving as a rotation fulcrum is provided at the upstream end of the pressing member 73H in the sheet conveying direction, and a hole 69c serving as a rotation fulcrum is provided on the inner surface of the recessed portion 69b. It has been drilled. The protrusion 73a of the pressing member 73H is inserted into the hole 69c of the opening / closing guide plate 69 and is held so as to be swingable. On the other hand, a compression spring 78 is disposed as an elastic member between the opening / closing guide plate 69 and the pressing member 73H, and is attached so as to be held at the position.

  The other parts are as described with reference to FIGS.

  With this configuration, when the open / close guide plate 69 is closed, the open / close guide plate 69 is held by the magnets on the fixed guide plate 72 facing the open / close guide plate 69. At this time, the conveying drive roller 71 and the fourth folding roller 24 facing the conveying driven roller 70 and the fourth folding roller driven roller 68 are brought into contact in a pressurized state as described above, and conveying pressure is applied. At this time, the pressing member 73 </ b> H is pressed against the fourth folding roller 24, but maintains a state where a certain pressure is applied between the pressing member 73 </ b> H and the fourth folding roller 24. As a result, when the sheet is conveyed, the sheet itself is conveyed while expanding the pressing member 73H, so that the pressing member 73 expands by the thickness of the sheet. However, the sheet is conveyed in a state where a certain pressure is applied across the entire width of the sheet by the compression spring 78.

  For example, in the case of Z-folding, when the second folding is performed, the Z-fold paper 74 is pressed against the fourth folding roller 24 over the entire width of the paper by the pressing member 73H. As a result, a uniform conveying force can be obtained over the entire paper width, and no bending or sheet floating occurs during conveyance at locations other than the fourth folding roller driven roller 68. This eliminates the occurrence of ironing marks.

As described above, according to the present embodiment,
1) The Z-fold paper 74 is pressed against the fourth folding roller 24 by the pressing members 73 and 73H over the entire width of the paper, and a uniform conveying force is obtained over the entire paper width. However, there is no occurrence of bending or paper floating during conveyance, and the paper 74a does not stick. Similarly, even when the friction coefficient is lowered due to deterioration of the fourth folding roller 24 and the fifth folding roller 25, dirt due to paper dusting, or the like, the paper does not float and the paper does not stick. Therefore, the iron mark 74b can be prevented from sticking to the paper.
2) When the folding member 73 is composed of a sheet member made of a PET material, the PET material is a polymer material, and an elastic force suitable for the material can be obtained and can be partially deformed. Stable pressing force can be obtained without the occurrence of deformation and sag over time due to paper. Thereby, it becomes possible to provide a stable conveying force over a long period of time.
3) Further, when the thin plate-shaped pressing member 73H having rigidity is used, the compression spring 78 elastically biases with an appropriate pressure, so that a conveyance gap corresponding to the sheet thickness can be obtained during the sheet conveyance. It is possible and does not cause poor conveyance.
There are effects such as.

  In this embodiment, the case of Z-folding of a paper folding processing apparatus capable of multiple types of folding processing has been described as an example, but this is particularly problematic when iron marks are generated during the second folding. The present invention is a folding device that folds paper by a pair of folding rollers, and is applied to all devices that use a narrow driven roller at the nip of the pair of folding rollers. It is. The present invention is not limited to the present embodiment, and various modifications are possible. All technical matters included in the technical idea of the invention described in the scope of claims are the subject of the present invention.

68 (fourth folding roller) driven roller 21 first folding roller 22 second folding roller 23 third folding roller 24 fourth folding roller 25 fifth folding roller 74 (sheet-like) pressing member 74H (thin plate-like rigidity) ) Pressing member 68 Opening / closing member 51, 52, 53 Stopper ZF Paper folding device PR Image forming device

Japanese Patent No. 3817424 Japanese Patent No. 4238777

Claims (6)

The loaded paper is sandwiched between the driven roller and one folding roller located upstream of the pair of folding rollers in the sheet conveying direction and guided to the nip of the folding roller pair, and is sandwiched by the nip of the folding roller pair and folded. A paper folding device for processing,
Made sheet-like member having elasticity, the sheet folding apparatus characterized by comprising means pressing presses the entire width of the sheet on the one folding row La. The sheet folding device according to claim 1,
The sheet folding apparatus, wherein the sheet-like member is made of a polymer material that is elastically deformable . The sheet folding device according to claim 1 ,
The sheet folding apparatus , wherein the pressing unit includes a thin plate member having rigidity, and an elastic biasing unit that elastically biases the thin plate member toward the one folding roller . The paper folding device according to any one of claims 1 to 3 ,
The paper folding apparatus, wherein the pressing means is attached to a member facing the one folding roller . The sheet folding device according to any one of claims 1 to 4,
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 conveying roller that forms a deflection by abutting against the stopper means;
A plurality of folding roller pairs provided along the paper conveyance path and capable of folding at each nip;
With
The sheet folding device , wherein the folding roller pair is one of the plurality of folding roller pairs . An image forming apparatus comprising the sheet folding device according to claim 1.

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