JP2020093857A - Sheet folding device, sheet processing device and image formation apparatus - Google Patents

Abstract

To improve the positional accuracy of a fold formed on a sheet by a sheet folding device.SOLUTION: A sheet folding device C includes: a register roller pair 33 which is arranged on the upstream side for feeding a sheet to a center conveyance path 42; a folding roller pair 34 which is arranged on the downstream side for forming a fold by nipping a folding position of the sheet; a projecting plate 35 which is movable from the upstream side to the projecting position proximate to the folding roller pair; a loop formation space 50 which is formed on the lower side of the center conveyance path; and a control unit 120. The control unit controls the sheet conveyance operation of the register roller pair and the movement of the projecting plate so that the projecting plate moves to the projecting position while pushing a prescribed portion of the sheet conveyed in the center conveyance path that is suspended into the loop formation space from the upstream side.SELECTED DRAWING: Figure 5

Description

The present invention relates to a sheet folding device that performs a folding process on a sheet, and a sheet processing device and an image forming apparatus that include a sheet folding mechanism that performs a folding process on a sheet.

2. Description of the Related Art Conventionally, a sheet folding apparatus that widely folds a sheet on which an image is formed by an image forming apparatus such as a copying machine or a printer at a predetermined position is widely known. The folding process includes two-folding at the central position of the sheet, three-folding in which the sheet is internally folded at two places, and so-called Z-folding in which the sheet is alternately folded inwardly and three-folded.

A paper piece folding device having a feed roller pair on the upstream side of a horizontal upper guide plate, a paper folding roller pair on the downstream side, and a paper piece guide deflecting member (that is, a thrust member) arranged on the upstream side of the paper folding roller pair is provided. It is known (for example, refer to Patent Document 1). In this device, the paper piece guide deflecting member moves from the second position retracted obliquely downward and upstream of the paper folding roller pair to the first position where the leading end of the paper folding roller pair is brought close to the paper piece inlet of the paper folding roller pair. A predetermined position of the piece of paper hanging in the space in front of the folding roller is drawn into the paper piece inlet, and the piece of paper is folded in half or Z-fold.

In addition, a sheet conveying roller is provided on the upstream side of the sheet conveying path where the lower guide plate and the upper guide plate are opposed to each other, and a sheet bending roller is provided on the downstream side, so that the first position for closing the notch formed in the lower guide plate and the notch Proposed is a sheet processing apparatus that includes a pressing member (that is, a pushing member) that is movable between a second position that is retracted obliquely downward on the upstream side and that similarly performs folding processing of two-fold and Z-fold on a sheet material. (For example, see Patent Document 2). From the second position, the pressing member is a sheet member that hangs down from the notch opened between the sheet conveying roller and the sheet bending roller, and is pressed against the upper guide plate by the roller at the tip of the sheet member. The sheet is moved along the plate to the first position, the bending position of the sheet material is guided to the nip of the sheet bending roller, and the sheet is bent by the rotation.

JP, 2002-68583, A JP, 2005-67741, A

In the conventional apparatus described in Patent Document 1, while the paper piece guide deflecting member pushes the paper piece with its tip (small roller) and moves to the first position close to the paper piece drawing-in port, the paper piece guide deflection member is in contact with the upper guide plate. There is a large gap at the top and bottom. Therefore, there is a possibility that the upstream paper piece portion from the tip of the paper piece guide deflecting member may loosen downward. This tendency is remarkable especially in the case of a soft and low-rigid piece of paper such as thin paper. In that case, the position where the paper piece guide deflecting member of the paper piece is abutted may shift from the predetermined portion to the upstream side or the downstream side in the sheet conveying direction while moving toward the paper piece inlet.

On the other hand, the paper piece portion on the downstream side from the abutting position of the paper piece guide deflecting member hangs downward from the tip of the paper piece guide deflecting member. Therefore, depending on the characteristics (surface smoothness, rigidity, etc.) and dimensions of the paper piece, the direction of conveyance, and the like, slipping or misalignment may occur between the paper piece and the leading end of the paper piece guide deflecting member in the sheet conveying direction. The deviation of the paper piece guide deflecting member from the predetermined portion of the paper piece is directly the positional deviation of the fold of the paper piece. As a result, the folded paper pieces have problems that the folding positions are not uniform, the dimensions in the sheet conveying direction vary, and the appearance is impaired.

As described above, the conventional device described in Patent Document 2 determines the bending position of the sheet material by the pressing member pressing the sheet material against the upper guide plate by the pressing roller at the tip of the sheet bending roller. By moving the sheet material to the first position, the slack of the sheet material is prevented from occurring on the upstream side of the tip of the pressing member. However, as in the case of Patent Document 1, the pushing member moves diagonally from the retracted position (second position) diagonally below and upstream from the first position. Therefore, on the upstream side of the pushing roller, the upper guide is provided. A vertical gap is created between the plate and the plate. Therefore, due to the rigidity and other characteristics of the sheet material, slippage occurs between the sheet material and the upper guide plate and/or the pressing roller, and like the case of Patent Document 1, the sheet material is left in the gap between the upper guide plate and the sheet material. There is a risk that slack will occur.

The present invention has been made in view of the above-mentioned conventional problems, in a sheet folding apparatus that abuts a thrust member at a predetermined position of a sheet and performs folding processing such as bi-folding and Z-folding with a folding roller pair, It is an object of the present invention to reduce the positional deviation of folds formed on a sheet and the variation in dimensions of the folded sheet.

The sheet folding apparatus of the present invention,
A feed roller for transporting the sheet in a predetermined transport direction,
A folding roller pair arranged on the downstream side in the transport direction of the feed roller along the transport direction,
An abutting member that abuts a predetermined position of the sheet and is movable to an abutting position for nipping the folding roller pair,
A sheet feeding operation of the feed roller and a control unit for controlling the movement of the pushing member to the pushing position,
The control unit controls the feed roller and the thrusting member so that the thrusting member moves to the thrusting position while pushing the predetermined position of the sheet being transported by the transporting roller along the transporting direction from the upstream side in the transporting direction. Is characterized by.

In another aspect of the present invention, a sheet processing apparatus of the present invention includes the above-described sheet folding apparatus of the present invention.

Further, in another aspect of the present invention, an image forming apparatus of the present invention includes an image forming unit for forming an image on a sheet and a sheet folding apparatus of the present invention for folding a sheet sent from the image forming unit. Alternatively, a sheet processing apparatus is provided.

According to the sheet folding apparatus of the present invention, the feed roller conveys the sheet toward the pair of folding rollers in the conveying direction under the control of the control unit, while the thrusting member is abutted at a predetermined position of the sheet and has a predetermined position. Since the sheet is pushed and moved to the pushing position, the predetermined position of the sheet is conveyed to the pushing position where it is nipped by the pair of folding rollers without shifting to the upstream side or the downstream side in the feeding direction. Therefore, the predetermined position of the sheet can be surely and stably nipped by the pair of folding rollers to form the fold, so that the positional accuracy of the fold is improved.

1 is an overall configuration diagram of an image forming system to which the present invention is applied. 1 is a schematic configuration diagram of a sheet folding apparatus according to the present invention. FIG. 6A is a perspective view showing the entire drive mechanism of the sheet folding apparatus, and FIG. Schematic which illustrates the suitable arrangement|positioning of the thrust member in a retracted position. The block diagram which shows the control structure of a sheet folding apparatus. FIG. 3 is an end view of a sheet that is folded in three (Z-fold) by a sheet folding device. The flowchart explaining the whole process operation of a sheet folding device. (A)-(f) is sectional drawing which shows the folding process of a sheet folding device in process order. The flowchart explaining the resist process of a sheet folding device. 6 is a flowchart illustrating a loop forming process of the sheet folding device. The flowchart explaining movement of a veneer to a retracted position. The flowchart explaining the crease|folding process of a sheet folding device. The flowchart explaining movement to a thrust position of a veneer. The principal part expanded sectional view which shows the veneer which moves the 2nd route part of a central conveyance path. 6 is a timing chart of drive voltages applied to the registration roller drive motor MT1 and the veneer drive motor MT3. FIG. 6 is a schematic view showing the arrangement of a veneer plate separated from the retracted position to the upstream side. The principal part expanded sectional view which shows the veneer which moves along the 2nd inclination guide part of a 2nd lower guide part. FIG. 4 is an enlarged cross-sectional view of a main portion showing the sheet winding in the nip portion of the pair of folding rollers. The flowchart explaining movement to a guide position of a veneer.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[Image forming system]
FIG. 1 shows the overall configuration of an image forming system to which the present invention is applied. The image forming system shown in the figure includes an image forming apparatus A, a sheet post-processing apparatus B, and a sheet folding apparatus C connected between them. The sheet on which the image is formed by the image forming apparatus A is conveyed through the sheet folding apparatus C, and is stored in the discharge tray by the sheet post-processing apparatus B. The image forming apparatus A, the sheet post-processing apparatus B, and the sheet folding apparatus C will be described below.

[Image forming device]
The image forming apparatus A is of a type that forms an image on a sheet by a known electrostatic printing mechanism, and includes a sheet feeding unit 2, an image forming unit 3, a sheet discharging unit 4, and a control unit (see FIG. (Not shown). An image reading unit 5 including a scanner unit is provided on the upper part of the apparatus housing 1, and an automatic document feeding unit 6 is integrally provided on the image reading unit 5. The image forming apparatus A according to the present embodiment is a so-called in-body sheet discharge type, and has a front U-shaped discharge that is largely defined between the image forming unit 3, the sheet discharge unit 4, and the image reading unit 5 in FIG. 1. The transport relay unit 7 is arranged in the paper space. In addition to the above electrostatic printing mechanism, the image forming apparatus A can employ various other image forming mechanisms such as an inkjet image forming method, an offset printing method, and a silk printing method.

The sheet feeding unit 2 is provided with a plurality of sheet feeding cassettes 2a and 2b each having a different sheet size, which are detachably provided in the apparatus housing 1. The sheet feeding unit 2 that stores sheets for image formation feeds a sheet of a size designated by the control unit from the corresponding sheet feeding cassette to the sheet feeding path 8. A registration roller 9 is provided in the paper feed path 8, and the sheet whose leading edge is aligned by the registration roller is fed to the image forming unit 3 located downstream at a predetermined timing.

The image forming unit 3 includes an electrostatic drum 10 and a print head, a developing device, a transfer charger and the like arranged around the electrostatic drum 10. The print head is composed of, for example, a laser light emitter, and forms an electrostatic latent image on the electrostatic drum 10. The developing device attaches toner ink to the electrostatic latent image to form a toner image, which is transferred to a sheet by the transfer charger. The sheet on which the toner image has been transferred is conveyed to the fixing device 11, heated and pressed, and after fixing the toner image, it is conveyed to the paper discharge path 12 of the paper discharge unit 4.

The downstream side of the paper discharge path 12 is branched into an upper first paper discharge path 13 and a lower second paper discharge path 14 in FIG. The first paper ejection path 13 and the second paper ejection path 14 are connected to an upper first paper ejection opening 15 and a lower second paper ejection opening 16 which are opened in the paper ejection space.

A sheet circulation path (not shown) can be provided in the paper discharge unit 4. In the sheet circulation path, for example, the sheet discharge path 12 is connected to the downstream side of the fixing device 11 and the sheet feed path 8 is connected to the upstream side of the registration rollers 9. The image-formed sheet sent from the image forming section 3 to the sheet discharge path 12 is switched back to the sheet circulation path by reversing the sheet discharge roller of the sheet discharge path 12, and the surface thereof is turned upside down and the image forming section is again formed. By sending the image to No. 3, an image can be formed on both sides of the sheet.

As shown in FIG. 1, the transport relay unit 7 has a substantially L-shape when viewed from the front, and has a first relay portion 17 that extends upward at the right end of the paper discharge space and the paper discharge space over substantially the entire width on the left and right. And a second relay portion 18 extending to the left side surface position of the device housing 1. The upper surface of the second relay portion 18 forms a sheet discharge tray 19 that is substantially flat in the paper discharge space.

The first relay section 17 is provided with a first relay path 20 therein, and the first sheet inlet 21 thereof is connected to the first sheet discharge port 15 of the sheet discharge unit 4, so that the first sheet outlet 22 is It is arranged above the sheet discharge tray 19 so as to open into the discharge space. In the first relay path 20, a carry-out roller driven by a motor built in the first relay unit 17 is provided near the first sheet exit 22. The image-formed sheet conveyed from the paper discharge unit 4 via the first paper discharge path 13 is carried out by the carry-out roller through the first relay path 20 to the sheet discharge tray 19 in the paper discharge space. It

A second relay path 23 is provided inside the second relay section 18, and a second sheet inlet 24 thereof is arranged so as to be connected to the second sheet discharge port 16 of the sheet discharge section 4. The second sheet outlet 25 of the second relay path 23 opens substantially on the same plane as the left side surface of the apparatus housing 1, and is connected to the sheet carry-in inlet of the sheet folding apparatus C as described later. The second relay path 23 is provided with a plurality of transport rollers that are driven by a motor incorporated in the second relay unit 18 to transport the sheet. The image-formed sheet conveyed from the sheet discharge unit 4 via the second sheet discharge path 14 is sent to the sheet folding apparatus C by the conveying rollers after passing through the second relay path 23.

The image reading unit 5 includes a platen 26 on which a document sheet is placed, a reading carriage 27 that moves along the platen, and an optical reading unit 28 including, for example, a CCD device. The document sheet on the platen 26 is scanned by the reading carriage 27 and optically read, and the optical image generated thereby is photoelectrically converted into image data by the optical reading means 28. The automatic document feeder 6 automatically feeds the document sheets set in the paper feed tray 29 to the platen 26.

With the above-described configuration, in the image forming apparatus A, the document sent from the document feeding unit 5 is read by the image reading unit 4, and according to the read image data, the image forming unit 2 forms an image on the sheet sent from the paper feeding unit 3. To do. When the folding process by the sheet folding device C and the post-processing by the sheet post-processing device B are not performed, the image-formed sheet is conveyed from the paper ejection unit 4 through the first paper ejection path 13 and passes through the first relay path 20. After passing, the sheet is discharged to the sheet discharge tray 19 in the sheet discharge space. When performing the folding processing and/or the post-processing on the sheet on which the image is formed, the sheet is conveyed from the sheet discharging unit 4 through the second sheet discharging path 14, passes through the second relay path 23, and then the sheet folding apparatus. Sent to C.

[Sheet post-processing device]
As shown in FIG. 1, the sheet post-processing apparatus B includes a first transport path 101 for transporting a sheet from the sheet folding apparatus, and second and third transport paths branched from the first transport path into a housing 100. 102, 103, a post-processing device such as a staple unit ST1, and a binding processing tray 104. On one side surface (left side surface in FIG. 1) of the housing 100, first and second discharge trays 105 and 106 for stacking and storing sheets discharged from the sheet post-processing apparatus B are provided vertically separated from each other. There is. The sheet post-processing apparatus B is arranged so that the sheet carry-in port 107 of the first transport path 101 is connected to the sheet discharge port of the sheet folding apparatus C described later.

The first paper discharge tray 105 is arranged below the paper discharge port 108 of the second transport path 102 that opens to the side surface of the housing 100. The sheet sent from the sheet folding apparatus C is conveyed from the first conveying path 101 to the second conveying path 102 when the stapler ST1 and/or other post-processing is not performed in the sheet post-processing apparatus B. Then, the sheet is directly discharged from the sheet discharge port 108 to the first sheet discharge tray 105.

The paper discharge port 109 of the third transport path 103 is arranged above the binding processing tray 104 so as to face the paper mounting surface of the binding processing tray 104. When the staple unit ST1 performs the staple binding process, the sheet sent from the sheet folding apparatus C is transported from the first transport path 101 to the third transport path 103, and the paper output port 109 of the sheet is loaded onto the binding tray 104. Is discharged to the surface. The plurality of sheets stacked on the binding processing tray 104 are staple-stitched into a sheet bundle by the stapling unit ST1, are then conveyed from the binding processing tray, and are discharged from a downstream end thereof to a second sheet discharging tray 106 below. It

[Overall structure of sheet folding device]
As shown in FIG. 2, in the sheet folding apparatus C, a conveyance path 32 from the sheet carrying-in port 32a on the image forming apparatus A side to the sheet discharging port 32b on the sheet post-processing apparatus B side is formed inside the housing 31. There is. In the conveyance path 32, a registration roller pair 33 is arranged on the upstream side in the sheet conveyance direction, a folding roller pair 34 is arranged on the downstream side, and a thrust plate 35 is arranged between the pair of rollers. As described above, the sheet folding apparatus C includes the sheet carry-in port 32a at the second sheet exit 25 of the transport relay unit 7 installed in the image forming apparatus A and the sheet discharge port at the sheet carry-in port 107 of the sheet post-processing apparatus B. 32b are arranged so as to be connected to each other.

Further, an additional folding mechanism 36 can be optionally provided near the sheet discharge port 32b of the transport path 32. In a folding mechanism such as the sheet folding device C, in order to surely fold the conveyed sheet at the fold position, an additional folding mechanism for pressing the sheet at the fold position is provided downstream after the folding process. Conventionally well known to those skilled in the art.

[Registration roller pair]
The registration roller pair 33 is composed of an upper drive roller 33a and a lower driven roller 33b, which are arranged with the conveyance path 32 in between in the figure. The driven roller 33b has its roller surface pressed against the roller surface of the driving roller 33a by, for example, a suitable spring means (not shown), so that the driven roller 33b follows the rotation of the driving roller 33a by a registration motor described later. Then rotate.

The sheet sent out from the transport relay unit 7 of the image forming apparatus A by the discharge roller pair 37 in the vicinity of the second sheet outlet 25 has the leading end thereof as a pressure contact portion of the roller surface of the registration roller pair 33 which is not rotating. The tip positions are aligned by abutting against the nip portion 38. The sheet with the leading end position aligned and the skew feeding corrected in this manner is conveyed by driving the registration roller pair 33 at a predetermined timing so that the conveyance path 32 is directed to the folding roller pair 34.

In another embodiment, the registration roller pair 33 can be replaced with a discharge roller (corresponding to the discharge roller pair 37 in FIG. 2) that discharges a sheet from the image forming apparatus A to the sheet folding apparatus C. As a result, the number of parts of the sheet folding apparatus C can be reduced, the manufacturing cost can be reduced, and the entire apparatus can be downsized in the sheet conveying direction. In this case, it is preferable that the discharge roller pair 37 have a function of aligning the leading end positions of the sheets carried into the transport path 32 as described above.

[Folding roller pair]
The folding roller pair 34 is composed of an upper folding roller 34a on the upper side and a lower folding roller 34b on the lower side, which are arranged with the transport path 32 in the drawing. The rollers 34a and 34b are pressed against each other by, for example, a suitable spring means (not shown) in order to nip and fold the leading edge and the crease of the sheet sent from the registration roller pair 33 as described later. In addition, in such a pressed state, it rotates in the sheet conveying direction in synchronization with a common folding roller drive motor described later.

The folding roller pair 34 is arranged such that the nip portion 38 of the registration roller pair 33 is located above a tangent line 39a passing through the nip portion 39 which is the pressure contact portion of the roller surface. In the embodiment of FIG. 2, the tangent line 39a and the tangent line 38a that passes through the nip portion 38 of the registration roller pair 33 are both oriented substantially horizontally, and the tangent line 38a is oriented above and below the tangent line 39a with a certain height offset. Has been done.

[Transport route]
As shown in FIG. 2, the transport path 32 includes a sheet transport path 41 extending from the sheet transport port 32a to the registration roller pair 33 and a central transport path 42 extending from the registration roller pair to the folding roller pair 34 along the sheet transport direction. And a sheet unloading path 43 extending from the pair of folding rollers to the sheet unloading port 32b.

The sheet carry-in path 41 includes an upper carry-in guide 41a and a lower carry-in guide 41b which are vertically opposed to each other along the sheet carrying direction so as to guide the leading end of the carried-in sheet to the nip portion 38 of the registration roller pair 33. Have. As described above, the upper carry-in guide 41a causes the sheet sent out from the upstream side to the discharge roller pair 37 when the leading end of the sheet is abutted against the nip portion 38 of the registration roller pair 33 and the leading end position is aligned. In order to secure a space that can be bent like a loop in 41, it is greatly enlarged upward from the vicinity of the registration roller pair 33 toward the entrance side.

As shown in FIG. 2, the central conveyance path 42 is vertically arranged along the sheet conveyance direction so as to guide the sheet whose leading edge is aligned by the registration roller pair 33 to the nip portion 39 of the folding roller pair 34. It has a transport guide 45 and a lower transport guide 46. The sheet is conveyed in the central conveyance path 42 from both sides in the thickness direction thereof by the upper and lower conveyance guides 45 and 46, and is regulated from the upper and lower sides in this embodiment.

As described above, since the tangent line 38a passing through the nip portion 38 of the registration roller pair 33 and the tangent line 39a passing through the nip portion 39 of the folding roller pair 34 are arranged horizontally and vertically displaced from each other, the upper conveyance guide 45 is , A first horizontal portion 45a horizontally extending to the downstream side along the tangent line 38a, a second horizontal portion 45b horizontally extending to the upstream side along the tangent line 39a, and the downstream side from the upstream side so as to connect both tangent lines 38a, 39a. And an inclined portion 45c inclined downward to the side.

As shown in FIG. 2, the inclined portion 45c is linearly formed from the upstream end of the second horizontal portion 45b to the diagonally upper right side in the drawing. The inclined portion 45c and the second horizontal portion 45b linearly intersect with each other, and a connecting portion thereof has a convex portion 47 which is composed of a relatively large obtuse-angled corner portion and which is generally downward in the central conveyance path 42. Has been formed. Similarly, the connecting portion between the inclined portion 45c and the first horizontal portion 45a is also formed at a relatively large obtuse angle corner portion.

In another embodiment, the connecting portion between the inclined portion 45c and the second horizontal portion 45b can be curved. In this case, the convex portion 47 is formed of a curved portion that is convex downward in the central conveyance path 42. The connecting portion between the inclined portion 45c and the first horizontal portion 45a can be similarly curved. In another embodiment, the convex portion 47 can be formed by a member separate from the second horizontal portion 45b and the inclined portion 45c of the upper conveyance guide 45.

In the present embodiment, as shown in the figure, the first horizontal portion 45a and the inclined portion 45c and the upstream side portion of the second horizontal portion 45b are formed by one continuous first upper conveyance guide member, and The downstream portion of the horizontal portion 45b is formed by another single second upper conveyance guide member. The first and second upper conveyance guide members are arranged substantially continuously so as not to hinder the conveyance of the sheet in the central conveyance path 42. In addition, the first upper conveyance guide member may be formed of a plurality of substantially continuous guide members, and the boundary between the first upper conveyance guide member and the second upper conveyance guide member is also at the position shown in FIG. Other than this, various settings can be made.

The lower conveyance guide 46 includes a first lower guide portion 46a extending from the registration roller pair 33 to a predetermined position downstream in the sheet conveyance direction, and a predetermined position upstream from the folding roller pair 34 in the sheet conveyance direction. A second lower guide portion 46b extending up to. The first and second lower guide portions 46a and 46b are fixed to the housing 31 side so as to be spaced apart from each other so as to define a large gap 48 therebetween in the sheet conveying direction. The gap 48 between the first and second lower guide portions 46a and 46b is selectively opened and closed by a projecting plate 35 that can move horizontally toward and away from the nip portion 39 of the folding roller pair 34, as will be described later.

Below the gap 48 of the lower conveyance guide 46, as shown in FIG. 2, a relatively large loop forming space 50 is provided. When the thrust plate 35 is retracted (indicated by a solid line in FIG. 2) and the gap 48 is opened, the sheet in the central conveyance path 42 can be hung from the gap 48 to the loop forming space 50. When the veneer plate 35 advances (indicated by an imaginary line 35′ in FIG. 2) and the gap 48 is closed, the sheet sent out from the registration roller pair 33 does not hang down in the loop forming space 50, and the central conveyance path 42 does not hang down. Can be conveyed toward the pair of folding rollers 34 along.

The first lower guide portion 46a extends horizontally from the registration roller pair 33 to the downstream side, and extends substantially in opposition to the first horizontal portion 45a of the upper conveyance guide 45, and further downstream from the first horizontal guide portion 51a. It has a first inclined guide portion 51b that is inclined substantially in parallel with the inclined portion 45c of the upper conveyance guide, facing the inclined portion 45c. The downstream end of the first inclined guide portion 51b defines the position where the sheet droops when the gap 48 is opened. In the present embodiment, as shown in the figure, the downstream end of the first inclined guide portion 51b is provided so as to be located above a tangent line 39a passing through the nip portion 39 of the folding roller pair 34.

The second lower guide portion 46b includes a second horizontal guide portion 52a extending horizontally from the folding roller pair 34 to the upstream side, a second inclined guide portion 52b inclined downward from the second horizontal guide portion to the upstream side, and It has a vertical guide portion 52c extending substantially vertically downward from the second inclined guide portion. The second horizontal guide portion 52a cooperates with the second horizontal portion 45b of the upper conveyance guide 45 to regulate the sheet in the thickness direction, that is, the up-down direction from both sides, while the leading end of the sheet is nipped by the folding roller pair 34. Guide to 39. The second inclined guide portion 52b is inclined toward the loop forming space so as to guide the sheet hanging in the loop forming space 50 to the nip portion 39 of the folding roller pair 34. The vertical guide portion 52c separates the sheet hanging in the loop forming space 50 from the folding roller pair 34 side together with the second inclined guide portion 52b while ensuring the size of the loop forming space 50.

When the veneer plate 35 is in the retracted position, the sheet sent out from the registration roller pair 33 to the central conveyance path 42 passes through the gap 48 opened downward from the sheet front end when passing the downstream end of the first inclined guide portion 51b. It hangs down linearly in the loop forming space 50. On the other hand, when the gap 48 is opened while the front end of the sheet is nipped by the folding roller pair 34 and the rotation of the folding roller pair is stopped, the sheet in the central conveyance path 42 will have a gap 48 as described later. Through the loop forming space 50, it bends in a loop shape and hangs down.

In other words, the central conveyance path 42 has a first path portion that feeds a sheet from the registration roller pair 33, a second path portion that can selectively open the central conveyance path 42 to the lower loop forming space 50, and a sheet that is folded. The third path portion guides the nip portion 39 of the roller pair 34. In the first to third path portions, the upper surface side of the sheet is substantially continuous in the sheet conveyance direction by the upper conveyance guide 45 including the first and second upper conveyance guide members. On the lower surface side of the seat, the first path portion is formed by the fixed first lower guide portion 46a, and the third path portion is formed by the fixed second lower guide portion 46b. The second path portion is formed by a gap 48 that is opened and closed by the movement of the thrust plate 35.

In another embodiment, the first path portion may be formed by a horizontal guide portion, omitting the first inclined guide portion 51b. In FIG. 2, the upper transport guide 45 has a position where the inclined portion 45c transitions to the second horizontal portion 45b set within the range of the gap 48 of the second path portion, but the position is not limited to this. Also in the second lower guide portion 46b, as long as the sheet hanging in the loop forming space 50 is guided to the nip portion 39 of the folding roller pair 34, the second inclined guide portion 52b may be smaller or eliminated than that shown in FIG. As long as a sufficient loop forming space 50 is secured, the vertical guide portion 52c can be reduced or eliminated.

The sheet unloading path 43 has an upper unloading guide 43a and a lower unloading guide 43b that are vertically opposed to each other along the sheet transport direction so as to guide the folded sheet to the sheet unloading port 32b. In front of the sheet outlet 32b, for example, an additional folding mechanism having a plurality of rolling elements that move on the lower delivery guide 43b in the sheet width direction orthogonal to the sheet transport direction to further fold the folds of the folded sheet. 36 are provided.

[Veneer]
As shown in FIGS. 2 and 3, the thrust plate 35 is formed of a flat plate member that extends in the sheet width direction of the central conveyance path 42. The veneer plate 35 is horizontally arranged at substantially the same height as the nip portion 39 of the folding roller pair 34. Further, the thrust plate 35 is provided so as to be horizontally movable between the retracted position below the first lower guide portion 46a shown by the solid line in FIG. 2 and the guide position and the thrust position shown by the imaginary lines 35' and 35". ing.

When the thrust plate 35 is in the retracted position, as shown in the drawing, the gap 48 of the lower transport guide 46 is completely opened, and the central transport path 42 is opened to the loop forming space 50 in which the second path portion is below. It Therefore, the sheet in the central transport path 42 can hang from the central transport path 42 into the loop forming space 50 as described later.

At the guide position of the imaginary line 35', the thrust plate 35 completely closes the gap 48 of the lower conveyance guide 46, and simultaneously forms a part of the lower conveyance guide 46 while vertically facing the upper conveyance guide 45. As a result, the sheet in the central transport path 42 is guided through the second path portion without hanging in the loop forming space 50, and is transported from the first path portion to the third path portion.

At the projecting position of the imaginary line 35″, the projecting plate 35 enters between the second horizontal portion 45b of the upper conveyance guide 45 and the second horizontal guide portion 52a of the second lower guide portion 46b at the third path portion. This thrusting position is a position where the thrusting plate 35 feeds the fold line of the sheet into the nip portion 39 of the folding roller pair 34 at its tip.

FIG. 4 is an enlarged concrete view showing an example of a preferable arrangement of the thrust plate 35 in the retracted position. As shown in the figure, a height H is formed between the second horizontal portion 45b of the upper conveyance guide 45 and the second horizontal guide portion 52a of the second lower guide portion 46b of the lower conveyance guide 46 facing the second horizontal portion 45b. The upper and lower gaps are defined. As a result, the third path portion of the central conveyance path 42 has a straight line portion 66 that extends horizontally and linearly from the folding roller pair 34 to the upstream side.

The height H of the straight line portion 66 is set between the second horizontal portion 45b of the upper transport guide 45 and the second horizontal guide portion 52a of the lower transport guide 46 on both the upper and lower sides of the thrust plate 35 located in the straight line portion. Set so that several sheets can be passed smoothly in an overlapping state. In the present embodiment, the thickness of two sheets that can be used in the image forming apparatus A is set in consideration of the thickness of two sheets so that the sheet folded in two can be passed. Thereby, the pushing plate 35 can smoothly move to the pushing position in the third path portion while pushing the sheet with the leading end in the folding process described later.

It is preferable that the thrust plate 35 is arranged such that, at the thrust position, the tip end thereof is close to the nip portion 39 of the folding roller pair 34 within the gap of the linear portion 66 of the third path portion. Therefore, the veneer plate 35 of FIG. 4 is horizontally arranged within the height H range of the extension line 66a extending the straight portion 66 to the upstream side at the retracted position. From this retracted position, the veneer 35 moves horizontally and linearly with its tip end facing the nip portion 39 of the folding roller pair 34.

More specifically, in FIG. 4, the veneer plate 35 of the present embodiment is arranged on the tangent line 39a extending from the nip portion 39 to the upstream side or at a position slightly below the tangent line 39a. Thereby, the tip of the thrust plate 35 can be brought closer to the nip portion 39 at the thrust position, which is convenient.

The retracted position of the thrust plate 35 is not limited to the height H range of the extension line 66a of the linear portion 66. If the thrust plate 35 that moves toward the pair of folding rollers 34 moves horizontally along the upper transport guide 45 along the third path portion and the tip can be brought close to the nip portion 39 at the thrust position, The retreat position can be provided at a position different from 4.

3A and 3B show the configuration of the thrust plate 35 in more detail. As shown in the figure, in the present embodiment, four pairs of folding rollers 34, which are respectively composed of upper and lower folding rollers 34a and 34b, are attached to the upper and lower roller shafts 55 and 56. The four pairs are symmetrically arranged along the axial direction of the roller shafts 55 and 56, two pairs on the left and right sides with respect to the central position thereof. Four notches 57 having a shape and size corresponding to the shape of the pair of folding rollers 34 are provided at the tip of the thrust plate 35 along the sheet width direction, corresponding to the positions of the four pairs of folding rollers 34. It is recessed.

The movement of the thrust plate 35 among the retracted position, the guide position and the thrust position is performed by driving a thrust plate drive motor MT3 of the drive mechanism shown in FIG. The drive of the thrust plate drive motor MT3 is controlled by the control unit 120 shown in FIG. 5 as described later.

[Drive mechanism of sheet folding device]
3A and 3B show driving mechanisms 58 to 60 for the registration roller pair 33, the folding roller pair 34, and the thrust plate 35 of the sheet folding apparatus C. The pair of registration rollers 33 is attached such that the drive roller 33a is integrally rotated with a roller shaft 61 that is rotatably installed in the sheet width direction. The folding roller pair 34 is mounted so that the upper and lower folding rollers 34a and 34b are also integrally rotated on roller shafts 55 and 56 that are also rotatably installed in the sheet width direction.

The drive mechanism 58 of the registration roller pair 33 includes a registration roller drive motor MT1, a drive pulley P1 attached to its rotation shaft, a driven pulley P2 attached to one end of the roller shaft 61 of the drive roller 33a, and both pulleys P1. , P2, and a timing belt TB1 wound around P2. The driving force of the registration roller drive motor MT1 is transmitted from its rotation shaft to the drive roller 33a via a transmission mechanism including a drive pulley P1, a timing belt TB1 and a driven pulley P2.

The drive mechanism 59 of the folding roller 11 includes a folding roller drive motor MT2, a drive pulley P3 attached to its rotation shaft, a driven pulley P4 attached to the roller shaft 56 of the lower folding roller 34b, and both pulleys P3 and P4. It is provided with a timing belt TB2 that is wound around. Further, the drive mechanism 59 is coaxially and integrally attached to the roller shaft 56 so as to be integrally rotatable, and the gear Z2 is coaxially and integrally attached to the roller shaft 55 of the upper folding roller 34a so as to mesh with the gear 1. With.

The driving force of the folding roller drive motor MT2 is transmitted from the rotation shaft of the folding roller drive motor MT2 to the lower folding roller 34b via a transmission mechanism including a drive pulley P3, a timing belt TB2, and a driven pulley P4. Further, the driving force of the folding roller driving motor MT2 is transmitted from the roller shaft 56 to which the driven pulley P4 is attached to the upper folding roller 34a via the gears Z1 and Z2 which mesh with each other. As a result, the upper folding roller 34a and the lower folding roller 34b rotate synchronously in mutually opposite directions, and the sheet nipped between the two folding rollers can be conveyed in the sheet conveying direction in cooperation with each other.

The drive mechanism 60 for the thrust plate 35 includes a thrust plate drive motor MT3, a drive pulley P5 attached to the rotation shaft thereof, a rotary shaft 62 installed in the seat width direction, and a driven pulley P6 attached to one end thereof. , A timing belt TB3 wound around the pulleys P5 and P6, a first rack-and-pinion mechanism 63 provided inward of the driven pulley P6 on the one end side of the rotating shaft 62, and the other end of the rotating shaft 62. And a second rack and pinion mechanism 64 provided in the.

The first rack-and-pinion mechanism 63 is attached to one end of the thrust plate 35 and a first pinion 63a coaxially and integrally rotatably attached to the one end side of the rotary shaft 62, inward of the driven pulley P6. , And a first rack 63b that meshes with the first pinion 63a. The second rack-and-pinion mechanism 64 is similarly mounted on the other end of the rotary shaft 62 so as to be coaxially rotatable with the second pinion 64 a, and is mounted on the other end of the thrust plate 35 to form the second pinion. And a second rack 64b that meshes with 64a. The first and second racks 63b and 64b are arranged so that the thrust plate 35 moves in the horizontal direction by the rotation of the first and second pinions 63a and 64a.

The driving force of the thrust plate drive motor MT3 is transmitted from the rotation shaft thereof to the first and second pinions 63a and 63b via the transmission mechanism including the drive pulley P5, the timing belt TB3 and the driven pulley P6. As a result, the first and second racks 63b, 64b move in synchronization with each other in the same direction, and cooperate with each other to move the thrust plate 35 in the horizontal direction.

[Control configuration of sheet folding device]
FIG. 5 conceptually shows the control configuration of the sheet folding apparatus C. The sheet folding apparatus C includes a control unit 120 including a control board including a CPU. As shown in the figure, the control unit 120 is connected with first to third detection sensors S1 to S3 provided along the transport path 32.

The first detection sensor S1 is arranged in front of the registration roller pair 33 in the sheet carry-in path 41, and detects the leading edge of the sheet carried in from the image forming apparatus A via the sheet carry-in port 32a. The second detection sensor S2 is arranged in front of the folding roller pair 34 on the central conveyance path 42, and detects the leading edge of the sheet conveyed from the registration roller pair 33 to the folding roller pair 34. The third detection sensor S3 detects the position of the thrust plate 35 that moves between the retracted position, the guide position, and the thrust position as described above. The detection results of the first to third detection sensors S1 to S3 are output to the control unit 120 in real time.

Further, the control unit 120 is connected to the control unit 121 of the image forming apparatus A via the sheet post-processing apparatus B. The control unit 121 is connected to an input unit and a display unit (not shown) provided on the setting panel D of the image forming apparatus A. For example, information such as the type of sheet set by the user on the setting panel D and the folding processing mode executed by the sheet folding apparatus C is transmitted from the control section 121 to the control section 120 via the sheet post-processing apparatus B. ..

If the registration roller drive motor MT1, the folding roller drive motor MT2, and the thrust plate drive motor MT3 are provided with the additional folding mechanism 36, the control unit 120 is further connected to the additional folding drive motor MT4. Based on the detection results input from the first to third detection sensors S1 to S3 and the various information received from the control unit 121 of the image forming apparatus A, the drive of each drive motor MT1 to MT3 and optionally MT4 is controlled. Controls and executes the sheet conveyance in the conveyance path 32 and the folding processing operation of the sheet folding apparatus C.

In addition, the control unit 120 can transmit information such as sheet conveyance and folding processing executed in the sheet folding apparatus C in real time to the control unit 121 of the image forming apparatus A via the sheet post-processing apparatus B. it can. When the information received from the control unit 120 includes information that is not preferable or should be cautioned or warned such as a sheet conveyance failure or a folding processing failure in the sheet folding apparatus C, the control section 121 notifies the user of it. For example, it can be notified using the display unit of the setting panel D.

The sheet folding apparatus C according to the present embodiment is suitable for alternately folding the sheet inward and outward along the sheet conveying direction and performing three-fold so-called Z-folding. FIG. 6 illustrates an example of the sheet SH that is Z-folded by the sheet folding device C from the sheet width direction. In the figure, the sheet SH is formed with a first fold line 202 at a position of a predetermined length from the front end (downstream end) 201 in the sheet conveying direction to the upstream side, and is folded back from there to a position of a predetermined length. The second fold line 203 is formed at. The folding processing operation of the sheet folding apparatus C will be described below.

[Processing operation of sheet folding device]
The sheet folding apparatus C is preset with a folding processing (Z folding) mode in which a sheet is folded in three (Z folding) and a non-folding mode in which a sheet is not folded. The user decides whether or not to fold the image-formed sheet before starting the image formation of the sheet in the image forming apparatus A, and when the fold processing is performed, the fold processing mode is set in the input section of the setting panel D. Select and enter. The input of the folding processing mode is stored in the control unit 121 of the image forming apparatus A as the sheet information of the sheet to be folded.

The entire processing operation of the sheet folding apparatus C will be schematically described with reference to the flowchart of FIG. 7. First, when the first detection sensor S1 detects the leading edge of the sheet carried into the sheet carry-in path 41 and turns on (Y in step ST1), the control unit 120 of the sheet folding apparatus C uses this as a trigger. The sheet information of the detected sheet is acquired from the control unit 121 of the image forming apparatus A via the sheet post-processing apparatus B (step ST02).

When the sheet information acquired from the control unit 121 of the image forming apparatus A includes a folding process mode selection instruction or a folding process execution instruction (Y in step ST03), the process proceeds to steps ST04 to ST06 to perform the folding process. If the sheet information from the image forming apparatus A does not include the folding processing mode selection instruction or the folding processing execution instruction, or if the folding processing execution instruction is not performed, the process proceeds to step ST07 to perform the folding processing.

In the unfolding process of step ST07, the thrust plate 35 is placed at the guide position (35'), and the registration roller pair 33 and the folding roller pair 34 are rotationally driven in this state. As a result, the sheet from the image forming apparatus A passes through the transport path 32 as it is without being folded and is carried out to the sheet post-processing apparatus B.

The folding processing of steps ST04 to ST06 is, as a whole, the registration processing by the registration roller pair 33 (step ST04), the folding loop processing by the folding roller pair 34 (step ST05), and the fold forming processing by the veneer plate 35 and the folding roller pair 34. It is performed in three stages of (step ST06). In the resist processing, the leading edge of the sheet carried into the sheet folding apparatus C is aligned to correct the sheet skew (skew). In the folding loop process, a loop for forming a fold is formed on the leading end side of the sheet. In the fold forming process, a fold is formed by the folding roller pair 34 on the sheet on which the loop is formed.

The processing in each of steps ST04 to ST06 will be specifically described below with reference to FIGS. 8 to 19. FIGS. 8A to 8F show a process sequence in which the sheet folding apparatus C carries in a sheet from the image forming apparatus A, conveys the sheet, and folds the sheet.

[Registration processing]
FIG. 8A shows a state in which the leading ends of the sheets are aligned in the resist processing of the sheet folding apparatus C. The resist processing is executed according to the procedure shown in the flowchart of FIG. 9, for example.

When the first detection sensor S1 detects the leading edge of the sheet carried into the sheet carry-in path 41 and is turned on while the pair of registration rollers 33 is stopped rotating, the control unit 120 turns it on (Y in step ST10). Measure the time elapsed from the time point. When this elapsed time exceeds a preset predetermined time (Y in step ST11), the registration roller drive motor MT1 is driven (step ST12) to rotate the registration roller pair 33.

During the predetermined time period of step ST11, the sheet leading edge is brought into contact with the nip portion 38 of the registration roller pair 33, and the sheet carry-in path 41 is deformed in a loop shape having a size sufficient and sufficient for aligning the leading edge positions. Is the time required to form a sheet. This time can be determined in advance based on, for example, a test result, and set in the control unit 120.

When the registration roller pair 33 is rotated, the sheet is conveyed to the folding roller pair 34 along the central conveyance path 42, as shown in FIG. 8B. Triggered by the activation of the registration roller drive motor MT1 in step ST12, a built-in folding loop counter (not shown) starts counting (step ST13). In the present embodiment, a pulse motor is adopted as the registration roller drive motor MT1, and the folding loop counter counts the number of drive pulses of the registration roller drive motor MT1.

When the sheet SH is delivered from the registration roller pair 33, the thrust plate 35 is arranged at the guide position 35'. Therefore, the leading edge of the sheet is guided straight to the nip portion 39 of the folding roller pair 34 while being guided by the upper surface of the thrust plate 35 through the central conveyance path 42. For the sheet whose front end has passed the convex portion 47 of the central conveyance path 42, in the area where the inclined portion 45c of the upper conveyance guide 45 and the second horizontal portion 45b are connected in the sheet conveyance direction, that is, in the area facing the gap 48, It is pushed downward by the convex portion 47 and is curved convexly toward the loop forming space 50 side.

[Fold loop processing]
The folding loop process is executed according to the procedure shown in the flowchart of FIG. 10, for example. The controller 120 drives the registration roller drive motor MT1 in step ST13, and simultaneously drives the folding roller drive motor MT2 to rotate the folding roller pair 34 (step ST20). As shown in FIG. 8B, immediately before the pair of folding rollers 34, the second detection sensor S2 detects the leading edge of the conveyed sheet to turn it on (Y in step ST21), and the control unit 120. Performs a retracting process for moving the thrust plate 35 from the guide position to the retracted position (step ST22).

The evacuation process of the veneer 35 is executed according to the procedure shown in the flowchart of FIG. 11, for example. The controller 120 drives the thrust plate drive motor MT3 in the reverse direction (step ST50) to move the thrust plate 35 horizontally from the guide position 35' to the upstream side in the sheet conveying direction toward the retracted position. A detection flag (not shown) is provided at the upstream end of the thrust plate 35 in the sheet conveying direction of the present embodiment.

When the third detection sensor S3 arranged below the first lower guide portion 46a detects the detection flag of the veneer plate 35 and turns on (Y in step ST51), the veneer plate drive motor MT3 is stopped ( Step ST52). As a result, the thrust plate 35 is arranged at the retracted position shown in FIG. 8C, and the gap 48 between the first and second lower guide portions 46a and 46b is completely opened. As a result, in the central conveyance path 42, the second path portion is opened to the lower loop forming space 50, as shown in FIG.

Next, the control unit 120 counts from the time when the second detection sensor S2 detects the sheet front end in step ST21, and drives the registration roller drive motor MT1 to a preset first set drive amount (step). (Y in ST23) and the folding roller drive motor MT2 are stopped (step ST24). Here, the first set drive amount is the drive amount of the registration roller drive motor MT1 required to reach the position where the sheet front end is nipped by the nip portion 39 of the folding roller pair 34.

As a result, the sheet is held in a state where the leading end of the sheet is nipped by the nip portion 39 of the folding roller pair 34, as shown in FIG. 8C. Even after this, the registration roller drive motor MT1 is continuously driven, and the registration roller pair 33 rotates to continue feeding the sheet. As a result, a portion of the sheet on the upstream side of the folding roller pair 34 is bent in a loop shape into the loop forming space 50 from the gap 48 and hangs down, so that a folding loop FL for forming a fold is formed on the sheet. Even after that, the loop FL becomes larger according to the amount of the sheet fed by the registration roller pair 33.

In the present embodiment, the sheet feed amount (conveyance distance) from the position where the leading edge of the sheet is detected by the second detection sensor S2 to the position where it exceeds the nip portion 39 of the folding roller pair 34 by 10 mm, the registration roller corresponding thereto. The first set drive amount is set by converting the drive amount of the drive motor MT1. Here, the drive amount of the registration roller drive motor MT1 includes the rotation amount of the motor (rotation speed of the rotation shaft, rotation angle, rotation time, etc.) and the sheet delivery amount by the registration roller pair 33, that is, the rotation amount of the drive roller 33a. (Rotation speed, rotation angle, rotation time, etc. of the roller shaft 61) can be used.

In the present embodiment, the folding position of the sheet is set in advance in accordance with the size of the sheet and the orientation (longitudinal direction, lateral direction) of the sheet during transportation, for example, the folding position represented by the distance from the leading edge of the sheet in the sheet transportation direction. Has been done. In the folding loop counter, a predetermined count value is predetermined for each size of sheet in order to form a loop on the sheet being conveyed, corresponding to the folding position. After the folding roller drive motor MT2 is stopped in step ST24, the folding loop counter that started counting in step 13 counts up to the predetermined count value (Y in step ST25), and the next fold forming process (step ST06). ) Is executed. The folding loop counter can be operated so as to count down by subtracting "0" from the predetermined count value.

[Fold formation processing]
The fold line forming process is executed according to the procedure shown in the flowchart of FIG. 12, for example. In step ST25, the control unit 120 counts up the folding loop counter, and a desired folding loop FL is formed in the loop forming space 50, and at the same time, starts the thrusting process of the thrust plate 35. At this time, the folding loop FL is formed to have a size suitable for forming a crease at a predetermined folding position on the sheet by continuously feeding the sheet by the registration roller pair 33, as shown in FIG. 8D. Has been done.

The bumping process is executed according to the procedure shown in the flowchart of FIG. 13, for example. The control unit 120 drives the veneer drive motor MT3 in the normal direction in the state where the registration roller drive motor MT1 is continuously driven and the sheet SH is sent out to the central conveyance path 42 (step ST53), and the veneer plate 35 is moved. It is moved horizontally to the folding roller pair 34 side. The tip of the thrust plate 35, which has started to move to the downstream side from the retracted position, strikes the folding loop FL at a position near the downstream end of the first lower guide portion 46a of the lower conveyance guide 46 where the folding loop FL starts to hang down.

Further, the pushing plate 35 moves toward the nip portion 39 of the folding roller pair 34 while pushing the predetermined position of the sheet with its tip. FIG. 14 shows in detail the process in which the veneer plate 35 moves to the downstream side of the second path portion of the central conveyance path 42. As shown in the figure, the veneer plate 35 horizontally moves linearly along the tangent line 39a of the nip portion 39 from the retracted position described above with reference to FIG. A portion of the sheet SH on the upstream side from the tip of the thrust plate 35 has a narrow gap between the second horizontal portion and the upper surface of the thrust plate 35 while the thrust plate 35 passes below the second horizontal portion 45b of the upper conveyance guide 45. Be transported.

The control unit 120 controls the registration roller drive motor MT1 to control the sheet conveying speed of the registration roller pair 33, and at the same time controls the veneer plate drive motor MT3 to control the moving speed of the veneer plate 35. In the present embodiment, the moving speed Vb of the thrust plate 35 is substantially equal to the sheet transport speed Vs sent out by the registration roller pair 33 except immediately after the start of the movement from the retracted position and immediately before the stop at the thrust position. It is controlled at a high speed, that is, Vb=Vs.

As a result, the sheet SH moves smoothly horizontally and linearly to the abutting position in a state where the upstream side portion from the tip of the thrust plate 35 is supported on the upper surface thereof substantially in synchronization with the thrust plate 35. .. Therefore, while the sheet SH is pushed and moved by the thrust plate 35, the abutting position of the thrust plate is prevented from being displaced from the predetermined position of the sheet to the upstream side or the downstream side in the transport direction. As a result, the following problems that may occur when the moving speed of the thrust plate 35 is different from the sheet conveying speed by the registration roller pair 33 (including the case where the sheet conveying is stopped) are prevented. ..

For example, when the moving speed of the pushing plate 35 is faster than the conveying speed of the sheet by the registration roller pair 33, the sheet is pushed by the pushing plate 35 and moves on the central conveying path 42 while the leading end of the pushing plate 35 and the registration roller pair are moved. Therefore, there is a risk that the abutting position of the thrusting plate 35 may shift from the predetermined position of the sheet to the upstream side, or the sheet may slip at the nip portion 38 of the registration roller pair 33. On the contrary, when the moving speed of the pushing plate 35 is slower than the conveying speed of the sheet by the registration roller pair 33, the sheet is slackened between the leading end of the pushing plate 35 and the registration roller pair 33, so that the second sheet of the upper conveying guide 45 is slackened. There is a risk of bending in the gap between the horizontal portion 45b and the thrust plate 35, or shifting the abutting position of the thrust plate 35 from the predetermined position of the sheet to the downstream side. According to this embodiment, such a problem is solved.

FIG. 15 is a timing chart of drive voltages applied to the registration roller drive motor MT1 and the veneer drive motor MT3 under the control of the control unit 120. On the horizontal axis of the figure, the time ha from when the registration roller drive motor MT1 is driven to when the veneer drive motor MT3 is driven is the drive pulse of the registration roller drive motor MT1 described above in relation to the folding loop counter. Is converted into time, and therefore changes depending on the driving speed of the motor MT1.

As shown in FIG. 15, a transition time hb in which the moving speed of the thrust plate 35 reaches the sheet transport speed Vs from the start of driving the thrust plate drive motor MT3 is set in advance. In consideration of this transition time hb, in the present embodiment, as shown in FIG. 16, the sheet conveyance is performed with the tip of the pushing plate 35 at the retracted position on the tangent line 39a of the nip portion 39 where the pushing plate moves. It is preferable that the first lower guide portion 46a of the lower conveyance guide 46 is disposed at a distance L upstream from the downstream end of the first lower guide portion 46a.

This distance L is set to be longer than the moving distance from when the pushing plate 35 starts moving toward the folding roller pair 34 to when the moving speed becomes Vb=Vs. As a result, the tip of the thrust plate 15 is abutted against the predetermined position of the folding loop FL at the same moving speed Vb as the sheet conveying speed Vs, and the moving speed is maintained until just before the stopping at the abutting position. Moves without deviating from the predetermined position of the folding loop FL.

In the meantime, when the sheet pushed by the thrust plate 35 and proceeding to the downstream side of the central transport path 42 enters the third path portion, the upper sheet portion sandwiching the thrust plate 35 causes the upper sheet portion to move to the second path of the upper transport guide 45. The horizontal portion 45b regulates from above, and the lower sheet portion is regulated from below by the second lower guide portion 46b of the lower conveyance guide 46. FIG. 17 shows in detail how the tip of the thrust plate 35 moves between the second horizontal portion 45b of the upper conveyance guide 45 and the second inclined guide portion 52b of the second lower guide portion 46b. Here, the sheet SH is squeezed into a form in which the portion on the downstream side from the tip of the thrust plate 35 is inclined toward the upstream side along the second inclined guide portion 52b.

Further, as shown in FIG. 8(e), the tip of the thrust plate 35 advances between the second horizontal portion 45b of the upper conveyance guide 45 and the second horizontal guide portion 52a of the second lower guide portion 46b, and these The sheet SH is regulated from above and below with a narrow gap. As a result, the sheet is bent at the predetermined position where the thrust plate 35 is abutted without slipping in the sheet conveying direction between the sheet and the tip of the thrust plate 35 while advancing along the third path portion. , Temporarily folded. This temporarily folded bent position is pressure-folded by the folding roller pair 34 to be the second folding line 203 of the folded sheet shown in FIG.

When the drive amount of the veneer drive motor MT3 reaches the preset second set drive amount (Y in step ST54), the veneer drive motor MT3 is stopped (step ST55). As a result, as shown in FIG. 8(e), the thrust plate 35 has its tip at the third path portion at the second horizontal portion 45b of the upper conveyance guide 45 and the second horizontal guide portion of the second lower guide portion 46b. The sheet is stopped at the protruding position 35″ that is inserted between the sheet 52a and 52a. As a result, the folding position FP2, which is the second folding line of the sheet, is bent by the above-described temporary folding, and is a nip portion of the folding roller pair 34. It is carried to just before 39.

In this way, by pushing the thrust plate 35 between the upper conveyance guide 45 and the second lower guide portion 46b, the sheet is forcibly bent in the direction in which the sheets are vertically overlapped at the folding position and temporarily folded. It After the sheet is temporarily folded in this manner, the sheet is nipped by the pair of folding rollers 34 at the folding position and folded, so that the folded portion of the sheet is prevented from opening at the second fold, and a folded sheet having a good appearance can be obtained. ..

Here, the second set drive amount is the drive amount of the thrust plate drive motor MT3 required to move the thrust plate 35 from the retracted position to the thrust position 35″. Can use the amount of rotation of the motor (the number of rotations of the rotation shaft, the rotation angle, the rotation time, etc.).

After the stop plate drive motor MT3 is stopped in step ST55, when the registration roller drive motor MT1 is driven to the preset third set drive amount (Y in step ST31), the control unit 120 causes the folding roller drive motor. The MT2 is driven (step ST32). Here, the third set drive amount continuously feeds the sheet even after the stop plate drive motor MT3 is stopped in step ST58, and the sheet folding position FP2 is set to the folding roller pair 34 as shown in FIG. This is the drive amount of the registration roller drive motor MT1 that rotates the registration roller pair 33 until reaching the position where the registration roller pair 33 is wound into the nip portion 39.

When the folding roller pair 34 is rotated by the driving of the folding roller driving motor MT2, as shown in FIG. 8F, the folding position which is the second folding line of the sheet is wound into the nip portion 39 of the folding roller pair 34. While being transported to the downstream side, it is pressure-folded between the upper and lower folding rollers 34a and 34b. By this pressure processing, the second fold line F2 (203) is formed at a predetermined folding position on the sheet. As described above, the folding position FP2 of the sheet is conveyed in the bent form without slipping or misalignment in the sheet conveying direction, and is wound around the nip portion 39 of the folding roller pair 34 as it is. The position of is stable with high accuracy without causing the conventional variation.

When the folding roller drive motor MT2 is driven in step ST32, the control unit 120 returns the thrust plate 35 from the thrust position 35″ to the retracted position so as not to prevent the sheet from being wound into the nip portion 39 of the folding roller pair 34. Evacuation processing is executed (step ST33) This evacuation processing is performed in the same manner as described in connection with the folding loop processing with reference to FIGS.

That is, in the state of FIG. 8E, the control unit 120 reversely drives the thrust plate drive motor MT3 to move the thrust plate 35 horizontally from the thrust position 35″ to the upstream side in the sheet transport direction toward the retracted position. When the third detection sensor S3 below the first lower guide portion 46a detects the detection flag of the veneer plate 35 and is turned on, the veneer plate drive motor MT3 is stopped. As shown in FIG. 8(f), it is arranged at the retracted position.

At this time, the gap 48 between the first and second lower guide portions 46a and 46b is completely opened, and the second path portion of the central conveyance path 42 is opened to the lower loop forming space 50. Therefore, the folding loop FL can be continuously and smoothly wound into the nip portion 39 of the folding roller pair 34 continuously from the start of winding in FIG.

The folding roller pair 34 is continuously driven to rotate even after the retracting process of the thrust plate 35. Therefore, as shown in FIG. 8( f ), the sheet is folded in three folds (Z folds) with the leading edge and the second fold F<b>2 formed by the pair of fold rollers 34 first. The sheet is nipped in a pair and conveyed to the downstream side through the sheet discharge path 43.

In this way, as the sheet is conveyed, the folding loop FL in the loop forming space 50 gradually becomes smaller. The folding loop FL enters the third path portion of the central conveyance path 42 and is squeezed from above and below by the second horizontal portion 45b of the upper conveyance guide 45 and the second inclined guide portion 52b of the second lower guide portion 46b. , Becomes a thin loop shape extending in the sheet conveying direction. Further, the folding loop FL advances between the second horizontal portion 45b and the second horizontal guide portion 52a of the second lower guide portion 46b, and from the top and bottom at the folding position FP1 of the rear end (upstream end) that becomes the first fold. Bent in half.

The folding position FP1 of the sheet is bent in this way, and is conveyed without slipping or positional deviation in the sheet conveying direction between the sheet and the upstream side portion of the sheet stacked on the folding position FP1. It is pressure-folded at the nip portion 39. Therefore, the first fold line (202 in FIG. 6) is stably formed at a desired position with high accuracy on the sheet without causing variations as in the conventional case.

As a result, as shown in FIG. 6, the Z-folded sheet SH having the first fold line 202 for the inner fold and the second fold line 203 for the outer fold is formed. In the present embodiment, as described above, the folding roller pair 34 that is not rotating forms the folding loop FL in a state where the leading end portion of the sheet is nipped, and then the folding roller pair 34 is rotated to rotate the second and first rollers. Since the fold line is bent and formed, the sheet leading end portion nipped at the time of forming the folding loop FL is Z-folded in a form protruding from the second fold line toward the leading end side (downstream side).

Next, when the first detection sensor S1 detects the trailing edge of the sheet conveyed by the registration roller pair 33 and the folding roller pair 34 and turns off in the sheet carry-in path 41 (Y in step ST34), the control unit The 120 performs a guide process for moving the thrust plate 35 from the retracted position to the guide position 35' (step ST35). At this time, the folding loop FL is set so as to have already passed the folding roller pair 34. Therefore, even if the pushing plate 35 is moved to the guide position 35 ′, there is no hindrance to the conveyance of the sheet in the central conveyance path 42 and the crease formation processing by the folding roller pair 34.

The guide processing is executed according to the procedure shown in the flowchart of FIG. 19, for example. The thrust plate drive motor MT3 is driven to rotate normally (step ST56), and the thrust plate 35 is horizontally moved to the folding roller pair 34 side. When the drive amount of the veneer drive motor MT3 reaches the preset fourth set drive amount (Y in step ST57), the veneer drive motor MT3 is stopped (step ST58).

Here, the fourth set drive amount is the drive amount of the thrust plate drive motor MT3 required to move the thrust plate 35 from the retracted position to the guide position 35'. As a result, the gap 48 between the first and second lower guide portions 46a and 46b is closed by the thrust plate 35, so that the trailing edge of the sheet is guided along the central conveyance path 42 to the upper face of the thrust plate 35, and the folding roller is guided. It is conveyed straight to the pair 34. As the amount of drive of the veneer plate drive motor MT3, the amount of rotation of the motor (the number of rotations of the rotating shaft, the rotation angle, the rotation time, etc.) can be used.

Next, when the second detection sensor S2 detects the trailing edge (upstream edge) of the sheet passing through the central conveyance path 42 and turns off (Y in step ST36), the control section 120 folds from that point. The drive amount of the roller drive motor MT2 is counted, and when the preset stop drive amount is reached (Y in step ST37), the registration roller drive motor MT1 and the folding roller drive motor MT2 are stopped (step ST38).

Here, the predetermined stop drive amount is a drive amount of the folding roller drive motor MT2 sufficient for the trailing edge of the sheet to pass through the pair of folding rollers 34. As a result, the registration roller pair 33 and the folding roller pair 34 stop rotating without causing any trouble in unloading the sheet from the sheet unloading port 32b to the sheet post-processing apparatus B, and finish the Z-folding processing of the sheet.

Although the present invention has been described above with reference to the preferred embodiments, the present invention is not limited to the above embodiments, and various modifications or changes can be made within the technical scope thereof. Needless to say.

A image forming apparatus B sheet post-processing apparatus C sheet folding apparatus 31 housing 32 transport path 33 registration roller pair 34 folding roller pair 35 veneer plates 38, 39 nip portion 41 sheet carry-in path 42 central transport path 43 sheet carry-out path 45 upper transport guide 45a 1st horizontal part 45b 2nd horizontal part 45c Inclined part 46 Lower conveyance guide 46a 1st lower guide part 46b 2nd lower guide part 47 Convex part 48 Gap 50 Loop formation space 51a 1st horizontal guide part 51b 1st inclined guide Part 52a Second horizontal guide part 52b Second tilted guide part 52c Vertical guide part 58-60 Drive mechanism 120 Control part 121 Image forming apparatus control part 201 Sheet tip 202 First fold 203 Second fold

Claims (7)

A feed roller for transporting the sheet in a predetermined transport direction,
A pair of folding rollers arranged on the downstream side in the transport direction of the feed roller along the transport direction,
An abutting member that abuts a predetermined position of the sheet and is movable to an abutting position for nipping the folding roller pair,
A sheet conveyance operation of the feed roller and a control unit that controls the movement of the thrust member to the thrust position,
The controller is configured to move the predetermined position of the sheet being conveyed by the feed roller along the conveyance direction to the protrusion position while the pushing member pushes the sheet from the upstream side in the conveying direction. A sheet folding device that controls the pushing member. The sheet folding device according to claim 1, wherein the control unit controls the sheet conveyance speed by the feed roller and the movement speed of the thrust member to the thrust position to be constant. 3. The sheet folding apparatus according to claim 1, wherein the pair of folding rollers nip and rotate a predetermined position of the sheet sent to the projecting position by the projecting member to form a fold line at the predetermined position. The sheet folding apparatus according to claim 1, wherein the control unit moves the thrust member to the thrust position based on a feed amount of the sheet fed in the transport direction by the feed roller. A transport path for transporting the sheet from the feed roller to the folding roller pair along the transport direction,
In order to hang a sheet from the transport path on the upstream side in the transport direction of the pair of folding rollers, a space formed below the transport path is further provided,
5. The sheet folding apparatus according to claim 1, wherein the thrust member abuts the predetermined position of the sheet hanging in the space from the transport path from the upstream side in the transport direction and moves to the thrust position. .. A sheet processing apparatus comprising the sheet folding apparatus according to claim 1. An image forming unit for forming an image on a sheet,
An image forming apparatus comprising: the sheet folding apparatus according to any one of claims 1 to 5 or the sheet processing apparatus according to claim 6 for folding a sheet sent from the image forming unit.

Images