JP2020093854A - Sheet folding device, sheet processing device and image formation apparatus - Google Patents

Abstract

To provide a sheet folding device in which variations in the folding position of a folding sheet is solved or reduced.SOLUTION: A sheet folding device C includes: a feeding roller pair 33 which conveys a sheet; a folding roller pair 34 which is arranged on the downstream side of the feeding rollers; a projecting member 35 which is movable from the upstream side in the conveyance direction toward a nip part 39 of the folding roller pair; and a guide member which is arranged on the immediately-upstream side of the folding roller pair. The guide member has a second horizontal portion 45b and a second lower guide portion 46b of an upper conveyance guide 45 for regulating the sheet fed to the nip part by the projecting member from both sides in the thickness direction. The folding roller pair rotates by nipping a prescribed position of the sheet fed to the nip part to form a fold.SELECTED DRAWING: Figure 2

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.

For example, a sheet folding apparatus has been proposed which includes a pair of folding rollers arranged on one side of the center folding processing tray along the sheet bundle conveying direction and a folding blade arranged on the opposite side of the center folding processing tray. (For example, refer to Patent Document 1). This sheet folding device advances and retracts the sheet bundle toward the nip portion of the pair of folding rollers at a right angle to the conveying direction of the sheet bundle while the sheet bundle is conveyed to the center folding processing tray. Center-folding (half-folding) is performed by pushing into the nip portion of the pair.

Further, a paper piece folding device in which a conveying means feed roller pair is provided on the upstream side of a horizontal upper guide plate, a paper folding roller pair is provided on the downstream side, and a paper piece guide deflecting member, that is, a thrust plate is arranged on the upstream side of the paper folding roller pair. Are known (for example, see Patent Document 2). The paper piece guide deflecting member moves from the second position retracted obliquely downward from the paper piece inlet port on the upstream side of the paper folding roller pair to the first position in which the front end is brought close to the paper piece inlet port, and the paper sheet folding roller pair is moved. Fold the piece of paper that hangs in the space in front of, into two folds or Z folds.

JP, 2008-207924, A JP, 2002-68583, A

The sheet folding apparatus described in Patent Document 1 is limited to folding in two and cannot fold a sheet in three.

In the paper piece folding device described in Patent Document 2, the predetermined position for forming the fold line of the sheet is pressed against one roller surface of the folding roller pair by the small roller at the tip of the paper piece guide deflecting member moved to the first position. After that, the pair of folding rollers is driven and nips to fold. At this time, the portion of the sheet on the downstream side of the predetermined position is curved along the roller surface from the position where it is pressed by the paper piece guide deflecting member, so that the position nipped by the folding roller pair is not always stable. However, there is a problem in that variations easily occur. As a result, there arises a problem that the folded sheets become uneven due to variations in folding position, and the appearance is impaired.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a sheet folding apparatus that eliminates or reduces variations in folding positions in a folded sheet.

The sheet folding apparatus of the present invention, a feed roller that conveys the sheet in a predetermined conveyance direction,
A pair of folding rollers that are arranged on the downstream side of the feed roller in the transport direction, rotate by nipping a predetermined position of the sheet, and form a fold at the predetermined position.
A thrust member movable toward the pair of folding rollers,
And a guide means arranged on the upstream side in the conveying direction of the pair of folding rollers,
The thrusting member moves to the downstream side in the transport direction, projects a predetermined position of the sheet and bends it to the downstream side, and sends the predetermined position to a position at which the pair of folding rollers can nip,
The guide means is characterized in that the curved portion of the sheet is regulated from both sides in the thickness direction of the sheet at a position where the projecting member can be nipped by the pair of folding rollers.

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 guide means arranged on the upstream side in the conveying direction of the folding roller pair regulates the sheet fed toward the nip portion of the folding roller pair from both sides in the thickness direction by the thrusting member. The pair of folding rollers can surely nip a predetermined position of the sheet to form a fold line. As a result, it is possible to eliminate or reduce variations in the folding position on the folded sheet, and to form a folded sheet with a uniform folding position and a good appearance.

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. 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 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 from both sides in the thickness direction, that is, the up-down direction, and at the nip portion 39 of the folding roller pair 34, the leading end of the sheet. I will guide you to. 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.

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.

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 of FIG. 3 described later. The drive of the thrust plate drive motor MT3 is controlled by the control unit 120 shown in FIG. 4 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. 4 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. 5 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. 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 steps ST04 to ST06 will be specifically described below with reference to FIGS. 7 to 13. FIGS. 7A to 7F 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. 7A 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. 8, for example.

The control unit 120 is built in 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 (Y in step ST10) while the pair of registration rollers 33 is stopped rotating. The folding loop counter (not shown) starts counting (step ST11). After a predetermined time has elapsed after the folding loop counter starts counting (Y in step ST12), the registration roller drive motor MT1 is driven (step ST13) to rotate the registration roller pair 33.

During the predetermined time in step ST12, the sheet leading edge is brought into contact with the nip portion 38 of the registration roller pair 33, and a loop-shaped bending of a size sufficient and sufficient for aligning the leading edge positions is performed. 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 conveyance path 32, as shown in FIG. 7B. At this time, the thrust plate 35 is located 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 processing is executed according to the procedure shown in the flowchart of FIG. 9, 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. 7B, when the second detection sensor S2 detects the leading edge of the conveyed sheet immediately upstream of the pair of folding rollers 34 and turns on (Y in step ST21), 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. 10, 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. 7C, 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 is nipped by the nip portion 39 of the folding roller pair 34, as shown in FIG. 7C. 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.

The sheet folding apparatus C includes a folding position, which is represented by a distance from the sheet front end in the sheet conveying direction, according to the size of the sheet that can be folded and the orientation (longitudinal direction, lateral direction) of the sheet during conveyance. And a predetermined count value corresponding to each folding position is preset in the folding loop counter. After the folding roller drive motor MT2 is stopped in step ST24, when the count of the folding loop counter started from step 11 counts up to the predetermined count value (Y in step ST25), the next fold forming process (step ST06). Move to.

[Fold formation processing]
The crease forming process is executed, for example, according to the procedure shown in the flowchart of FIG. The controller 120 starts the thrusting process of the thrust plate 35 at the same time when the folding loop counter is counted up in step ST25. At this time, the loop forming space 50 has a size suitable for forming a fold line at a predetermined folding position on the sheet by continuously feeding the sheet by the registration roller pair 33, as shown in FIG. 7D. The folding loop FL is formed.

The thrusting process is executed according to the procedure shown in the flowchart of FIG. 12, for example. First, the thrust plate drive motor MT3 is driven to rotate normally (step ST53), and the thrust plate 35 is horizontally moved to the folding roller pair 34 side. At this time, the pushing plate 35 advances toward the nip portion 39 of the folding roller pair 34 while pushing the position where the leading end of the pushing plate 35 becomes the second fold when viewed from the sheet leading end side of the folding loop FL. The control unit 120 moves the pushing plate 35 at the same speed as the sheet conveying speed by the registration roller pair 33 so that the position of the folding loop FL pushed by the tip of the pushing plate 35 does not change during the movement of the pushing plate 35. Thus, the veneer drive motor MT3 is controlled.

The sheet that is pushed by the thrust plate 35 and proceeds to the downstream side of the third path portion of the central transport path 42 has the upper sheet portion sandwiching the thrust plate 35 and is moved upward by the second horizontal portion 45b of the upper transport guide 45. The lower sheet portion is regulated by the second horizontal guide portion 52a of the second lower guide portion 46b, and the sheet front end portion upstream of the nip portion 39 of the folding roller pair 34 serves as the second horizontal guide portion. It is sandwiched between and regulated from below. As a result, the sheet does not slip in the sheet conveying direction between itself and the tip of the thrust plate 35 while the sheet travels toward the downstream side of the third path portion, and the second fold line with which the thrust plate 35 is abutted. It is bent at the folding position (203 in FIG. 5).

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. 7E, the tip end of the thrust plate 35 is the second horizontal guide portion of the second lower guide portion 46b and the second horizontal portion 45b of the upper transport guide 45 in the third path portion. 52a and stops at the protruding position 35″. As a result, the folding position FP2, which is the second folding line of the sheet, is bent as described above, and the nip portion 39 of the folding roller pair 34 is formed. Will be transported to just before.

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 ST58, the registration roller drive motor MT1 is driven to the preset third set drive amount (Y in step ST31), and the control unit 120 causes the folding roller drive motor. The MT2 is driven (step ST32). Here, the third set drive amount is a position where the sheet is continuously sent out even after the stop plate drive motor MT3 is stopped in step ST58, and the sheet folding position FP2 is wound into the nip portion 39 of the folding roller pair 34. Up to, the drive amount of the registration roller drive motor MT1 for rotating the registration roller pair 33.

When the folding roller pair 34 is rotated by the driving of the folding roller driving motor MT2, as shown in FIG. 7F, the folding position, which is the second fold of the sheet, is rolled into the nip portion 39 of the folding roller pair 34. While being transported to the downstream side, it is folded under pressure 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. A save process is executed (step ST33) This save process is performed in the same manner as described with reference to FIGS. 10 and 7B and 7C in connection with the folding loop process.

That is, in the state of FIG. 7E, the control unit 120 drives the thrust plate drive motor MT3 in the reverse direction 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. 7(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. 7F, the sheet is folded in three folds (Z folds) with the leading edge and the second fold F2 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. 5) 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. 5, the Z-folded sheet SH having the first fold line 202 for inner fold and the second fold line 203 for outer fold is generated. 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. 13, 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 48 Gap 50 Loop forming space 51a 1st horizontal guide part 51b 1st inclined guide part 52a 2nd Horizontal guide portion 52b Second inclined guide portion 52c Vertical guide portion 58 to 60 Drive mechanism 120 Control portion 121 Image forming apparatus control portion 201 Sheet tip 202 First fold 203 Second fold

Claims (7)

A feed roller that conveys the sheet in a predetermined conveyance direction,
A pair of folding rollers arranged on the downstream side in the transport direction of the feed roller, rotating by nipping a predetermined position of the sheet, and forming a fold line at the predetermined position,
A thrust member movable toward the pair of folding rollers,
A guide means arranged on the upstream side in the conveying direction of the pair of folding rollers,
The pushing member moves to the downstream side in the transport direction, projects the predetermined position of the sheet and bends the sheet toward the downstream side, and sends the predetermined position to a position where the folding roller pair can be nipped,
The sheet folding device, wherein the guide means regulates the curved portion of the sheet from both sides in the thickness direction of the sheet at a position where the pushing member can nip the pair of folding rollers. The guide means includes a pair of guide members that are arranged to face each other and that form a path that guides a sheet to the nip portion of the pair of folding rollers.
The sheet folding apparatus according to claim 1, wherein the thrusting member enters the path formed by the pair of guide members and sends the predetermined position of the sheet to a position at which the sheet can be nipped by the folding roller pair. The guide member includes a guide member having a lower guide surface that restricts the sheet from the lower side in the thickness direction thereof and an inclined guide surface that extends downward from the upstream end of the lower guide surface toward the upstream side. The described sheet folding device. A transport path for transporting the sheet in the transport direction from the feed roller to the folding roller pair,
Between the guide means and the feed roller, further comprising a space that allows the sheet to hang downward from the transport path,
The pair of folding rollers are operable to stop rotating in a state where the leading end of the sheet being fed from the feed roller is nipped, thereby forming a loop of the sheet hanging in the space,
3. The pushing member is movable so as to push the loop in the space from an upstream side in the transport direction and send a predetermined position of the sheet to a position where it can be nipped by the folding roller pair. Item 4. The sheet folding device according to any one of Items 3. The pushing member is a flat plate-like member that is linearly movable toward the nip position of the folding roller pair so as to project the predetermined position of the sheet at its downstream end and feed the sheet to a position where the folding roller pair can nip. The sheet folding apparatus according to any one of claims 1 to 4, which comprises a member. 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