JP7419581B2 - Sheet folding device, sheet processing device, and image forming device - Google Patents

Description

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

2. Description of the Related Art Conventionally, sheet folding apparatuses have been widely known that perform folding processing at predetermined positions on sheets on which images have been formed using an image forming apparatus such as a copying machine or a printer. Folding processes include two-folding at the center of the sheet, three-folding in which the sheet is folded inward at two locations, and so-called Z-folding in which the sheet is alternately folded inward and outward and then folded into three.

A paper folding device includes a pair of feed rollers on the upstream side of a horizontal upper guide plate, a pair of paper folding rollers on the downstream side, and a paper guide deflection member (i.e., a thrusting member) arranged on the upstream side of the pair of paper folding rollers. known (for example, see Patent Document 1). In this device, the paper piece guiding/deflecting member moves from a second position where it is retracted diagonally downward on the upstream side of the pair of paper folding rollers to a first position where the tip thereof is brought close to the paper piece inlet of the pair of paper folding rollers. A predetermined position of the piece of paper hanging down in the space in front of the folding roller is drawn into the paper piece inlet, and the piece of paper is folded in two or in a 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, and a sheet folding roller is provided on the downstream side, and a first position that closes the notch formed in the lower guide plate and a sheet conveying roller are provided on the downstream side. A sheet processing device is proposed that includes a pressing member (i.e., a thrusting member) that is movable between a second position retracted diagonally downward on the upstream side, and similarly performs two-fold and Z-fold bending processes on sheet material. (For example, see Patent Document 2). From the second position, the pressing member presses the sheet material hanging down from the notch opened between the sheet conveying roller and the sheet folding roller against the upper guide plate with the roller at its tip, and guides the sheet material over the upper guide plate. It moves along the plate to a first position, guides the sheet material to the nip of the sheet folding roller, and bends the sheet material by its rotation.

JP2002-68583A Japanese Patent Application Publication No. 2005-67741

In the conventional device described in Patent Document 1, in the case of Z-folding, a piece of paper continues to be fed from a pair of feed rollers with its leading end nipped by a pair of paper folding rollers, and is curved downward in a loop shape from the downstream end of the lower guide plate on the entrance side. let The shape, size, and degree of curvature of this loop vary depending on the rigidity and other characteristics of the paper strip, the amount of feed from the feed roller pair, etc. Since the paper folding rollers move diagonally from a retracted position that is far apart from the paper folding roller pair toward the paper strip inlet, the position of the predetermined portion of the paper strip that the tips (small rollers) abut against is not stable, and variations occur.

Furthermore, in the conventional device described in Patent Document 1, a large vertical gap exists between the paper guide and deflection member and the upper guide plate while the paper guide and deflection member moves from the retracted position to the first position close to the paper lead-in port. Therefore, there is a risk that the portion of the paper strip upstream from the tip of the paper strip guiding/deflecting member may loosen downward, and the predetermined portion of the paper strip that the tip abuts against may be misaligned in the sheet conveyance direction while moving toward the paper strip inlet. Easy to occur. Such positional deviations and variations in the abutment position of the paper pieces and after the abutment directly result in positional deviations and variations in the folds of the paper pieces, resulting in problems such as uneven folding positions and poor appearance.

As described above, in the conventional device described in Patent Document 2, the pressing member presses the sheet material against the upper guide plate with the pressing roller at the tip, and the bending position of the sheet material is adjusted to the nip of the sheet folding roller. By moving to the first position where the pressing member is guided, the sheet material is prevented from sagging on the upstream side of the tip of the pressing member. However, as in the case of Patent Document 1, the pressing member moves diagonally from the retracted position (second position) on the upstream side from the first position, so that the upper guide There will be a vertical gap between the board and the board. Therefore, if slippage occurs between the sheet material and the upper guide plate and/or the pressing roller due to the rigidity or other characteristics of the sheet material, there is a risk that the sheet material may become slack.

The present invention has been made in view of the above-mentioned conventional problems, and is aimed at stably abutting a punching member at a desired folding position of a sheet when performing folding processing such as bifolding or Z-folding on a sheet. It is an object of the present invention to provide a sheet folding device that can improve the positional accuracy of folds formed on sheets by reducing the positional deviations and variations thereof.

The sheet folding device of the present invention includes a conveyance path through which a sheet is conveyed, a feed roller disposed on the conveyance path and conveys the sheet along the conveyance path, and a downstream direction in the conveyance direction through which the feed roller conveys the sheet. a pair of folding rollers disposed on the conveyance path on the side and nipping and folding the sheet, and between the feed roller and the folding roller pair so that the sheet hangs down from the conveyance path on the upstream side in the conveyance direction; a space provided vertically below the conveyance path; and a thrust for moving the sheet to a position where it is nipped by the pair of folding rollers by piercing a predetermined position of the sheet hanging from the conveyance path into the space. The main components include:
The conveyance path includes a first path extending upstream in the conveyance direction from the pair of folding rollers, and a second path provided upstream of the first path and above the first path. a path, the thrusting member moves on an extension of the first path from a position vertically below the second path, and moves the first path of the sheet hanging in the space. It is characterized in that it is arranged so as to strike the predetermined position intersecting with the extension.

In another aspect of the present invention, a sheet processing device of the present invention is characterized by comprising the sheet folding device of the present invention described above.

Furthermore, in another aspect of the present invention, the image forming apparatus of the present invention includes an image forming unit that forms an image on a sheet, and the above-described sheet folding device of the present invention that folds the sheet sent from the image forming unit. or a sheet processing device.

According to the sheet folding device of the present invention, the punching member punches the sheet at a position close to the position where the sheet starts to droop from the conveying path, so that the sheet can be drooped depending on the rigidity and other characteristics of the sheet, the amount of feed from the feed roller, etc. Even if the condition, ie, the degree of curvature, is different, there is little positional shift or variation. Therefore, the thrusting member moving to the thrusting position can stably butt the sheet at a predetermined position, that is, a desired folding position, with high precision. As a result, the predetermined position of the sheet can be more reliably and stably fed to the nipping position where it is nipped by the pair of folding rollers, and the positional accuracy of the fold formed on the sheet is improved.

1 is an overall configuration diagram of an image forming system to which the present invention is applied. FIG. 1 is a schematic configuration diagram of a sheet folding device according to the present invention. (a) is a perspective view showing the entire drive mechanism of the sheet folding device, and (b) is an enlarged view of its main parts. FIG. 6 is a schematic diagram illustrating a preferred arrangement of the thrusting member in the retracted position. FIG. 2 is a block diagram showing a control configuration of a sheet folding device. FIG. 3 is an end view of a sheet folded into three (Z-folded) by a sheet folding device. 5 is a flowchart illustrating the entire processing operation of the sheet folding device. (a) to (f) are cross-sectional views showing the folding process of the sheet folding device in the order of steps. 5 is a flowchart illustrating registration processing of the sheet folding device. 5 is a flowchart illustrating loop forming processing of the sheet folding device. A flowchart illustrating movement of the veneer to the retracted position. 5 is a flowchart illustrating the creasing process of the sheet folding device. A flowchart illustrating movement of the veneer to the pierced position. FIG. 2 is an enlarged cross-sectional view of the main part of the sheet folding device showing movement of the veneer to the veneer position. A flowchart illustrating movement of the veneer to the guide position. (a) is a schematic sectional view showing a modified example of the lower conveyance guide of the central conveyance path, and (b) is an end view of the same as seen from the downstream side. FIG. 3 is a schematic configuration diagram showing main parts of another embodiment of a sheet folding device. FIG. 7 is a schematic configuration diagram showing main parts of yet another embodiment of a sheet folding device. (a) and (b) are cross-sectional views schematically showing the steps of the two-folding process of the sheet folding device.

Hereinafter, preferred embodiments of the present invention will be described based on 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 therebetween. A sheet on which an image has been formed by the image forming apparatus A is conveyed through a sheet folding apparatus C, and is stored in a discharge tray by a sheet post-processing apparatus B. The image forming apparatus A, sheet post-processing apparatus B, and 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 using a known electrostatic printing mechanism. (not shown). At the top of the device housing 1, an image reading section 5 consisting of a scanner unit and an automatic document feeding section 6 are integrally provided thereon. The image forming apparatus A of this embodiment is a so-called internal paper discharge type, and has a U-shaped front U-shaped discharge largely defined between the image forming section 3, the paper discharge section 4, and the image reading section 5 in FIG. A conveyance relay unit 7 is arranged in the paper space. In addition to the electrostatic printing mechanism described above, 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.

In the paper feed section 2, a plurality of paper feed cassettes 2a and 2b each having a different sheet size are removably provided in the device housing 1. The paper feed unit 2 that stores sheets on which images are to be formed feeds out sheets of the size instructed by the control unit from the corresponding paper feed cassette to the paper feed path 8. Registration rollers 9 are provided in the paper feed path 8, and the sheets whose leading edges are aligned with the registration rollers are fed to the downstream image forming section 3 at a predetermined timing.

The image forming section 3 includes an electrostatic drum 10, a print head, a developing device, a transfer charger, etc. arranged around the electrostatic drum 10. The print head is composed of, for example, a laser emitter, and forms an electrostatic latent image on the electrostatic drum 10. The developer applies toner ink to this electrostatic latent image to form a toner image, which is transferred onto a sheet by the transfer charger. The sheet onto which the toner image has been transferred is conveyed to the fixing device 11, heated and pressurized to fix the toner image, and then conveyed to the sheet discharge path 12 of the sheet discharge section 4.

The paper ejection path 12 is branched downstream into a first paper ejection path 13 on the upper side in FIG. 1 and a second paper ejection path 14 on the lower side. The first paper discharge path 13 and the second paper discharge path 14 are connected to an upper first paper discharge port 15 and a lower second paper discharge port 16, respectively, which open into the paper discharge space.

The paper discharge section 4 can be provided with a sheet circulation path (not shown). The sheet circulation path connects the paper discharge path 12 on the downstream side of the fixing device 11 to the paper feed path 8 on the upstream side of the registration rollers 9, for example. The image-formed sheet sent out from the image forming section 3 to the paper discharge path 12 is switched back to the sheet circulation path by reversing the paper discharge roller of the paper discharge path 12, and the sheet is turned over and sent to the image forming section again. 3, images 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 includes a first relay section 17 that extends upward at the right end of the sheet discharge space, and a first relay section 17 that extends substantially across the width of the sheet discharge space from side to side. and a second relay portion 18 that extends to the left side of the device housing 1. The upper surface of the second relay section 18 forms a generally flat sheet ejection tray 19 within the sheet ejection space.

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

The second relay section 18 is provided with a second relay path 23 therein, and its second sheet inlet 24 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 of the device housing 1, and is connected to the sheet inlet of the sheet folding device C as described later. The second relay path 23 is provided with a plurality of conveyance rollers that are driven by a motor built in the second relay section 18 to convey the sheet. The image-formed sheet conveyed from the sheet discharge section 4 via the second sheet discharge path 14 is sent to the sheet folding device C through the second relay path 23 by the conveyance roller.

The image reading section 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 means 28 made of, for example, a CCD device. The document paper on the platen 26 is scanned and optically read by the reading carriage 27, and the optical image generated thereby is photoelectrically converted into image data by the optical reading means 28. The automatic document feeding unit 6 automatically feeds the document paper set in the paper feed tray 29 to the platen 26.

With the above-described configuration, the image forming apparatus A uses the image reading section 4 to read the original sent from the original feeding section 5, and forms an image on the sheet sent from the paper feeding section 3 in the image forming section 2 according to the read image data. do. When the image-formed sheet is not subjected to folding processing by the sheet folding device C and post-processing by the sheet post-processing device B, the sheet is conveyed from the paper discharging section 4 via the first paper discharging path 13 and passing through the first relay path 20. The sheet passes through and is carried out to the sheet discharge tray 19 in the paper discharge space. When performing the folding process and/or post-processing on a sheet on which an image has been formed, the sheet is conveyed from the paper discharging section 4 via the second paper discharging path 14, passing through the second relay path 23, and then being sent to the sheet folding device. sent to C.

[Sheet post-processing device]
As shown in FIG. 1, the sheet post-processing device B includes, in a housing 100, a first conveyance path 101 for conveying sheets from a sheet folding device, and second and third conveyance paths branched from the first conveyance path. 102 and 103, post-processing equipment such as stapling unit ST1, and a binding processing tray 104. On one side of the housing 100 (the left side in FIG. 1), first and second paper ejection trays 105 and 106 are provided vertically apart from each other for stacking and storing sheets ejected from the sheet post-processing device B. There is. The sheet post-processing device B is arranged such that a sheet inlet 107 of the first conveyance path 101 is connected to a sheet discharge port of a sheet folding device C, which will be described later.

The first paper discharge tray 105 is arranged below the paper discharge port 108 of the second conveyance path 102 that opens on the side surface of the housing 100 . When the sheet sent from the sheet folding device C is not subjected to stapling processing and/or other post-processing by the stapling unit ST1 in the sheet post-processing device B, the sheet is transported from the first transport path 101 to the second transport path 102. , the paper is discharged as is from the paper discharge port 108 to the first paper discharge tray 105.

The paper discharge port 109 of the third conveyance path 103 is arranged above the binding tray 104 so as to face the paper loading surface of the binding tray 104. When the sheets sent from the sheet folding device C are subjected to stapling processing by the stapling unit ST1, they are transported from the first transport path 101 to the third transport path 103, and from the paper discharge port 109 to the stapling processing tray 104. discharged onto the surface. The plurality of sheets accumulated on the binding processing tray 104 are stapled into a sheet bundle by the stapling unit ST1, and then conveyed from the binding processing tray and discharged from the downstream end thereof to the lower second paper output tray 106. Ru.

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

Furthermore, an additional folding mechanism 36 can be optionally provided near the sheet discharge port 32b of the conveyance path 32. In a folding mechanism such as the sheet folding device C, in order to reliably fold the conveyed sheets at the folding position, an additional folding mechanism that presses the sheet at the folding position downstream after the folding process is provided. Conventionally well known to those skilled in the art.

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

The sheet sent out from the conveyance relay unit 7 of the image forming apparatus A by the discharge roller pair 37 near the second sheet outlet 25 has its leading end in pressure contact with the roller surface of the registration roller pair 33 whose rotation is stopped. By abutting against the nip portion 38, the positions of the tips are aligned. The sheet whose leading edge position is aligned and the skew is corrected in this manner is conveyed along the conveyance path 32 toward the folding roller pair 34 by driving the registration roller pair 33 at a predetermined timing.

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 the sheet from the image forming apparatus A to the sheet folding device C. Thereby, the number of parts of the sheet folding device C can be reduced, manufacturing costs can be reduced, and the entire device can be downsized in the sheet conveyance direction. In this case, it is preferable that the discharge roller pair 37 has a function of aligning the leading edge positions of the sheets carried into the conveyance path 32 as described above.

[Folding roller pair]
The folding roller pair 34 includes an upper upper folding roller 34a and a lower lower folding roller 34b, which are arranged across the conveyance path 32 in the figure. The roller surfaces of both rollers 34a and 34b are pressed against each other by suitable spring means (not shown), for example, in order to nip and fold the leading edge and crease of the sheet sent from the pair of registration rollers 33, as will be described later. At the same time, in such a pressed state, the folding rollers are synchronously rotated in the sheet conveyance direction by a common folding roller drive motor, which will be 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 passing through the nip portion 38 of the registration roller pair 33 are both substantially horizontal, and are oriented vertically shifted by a certain height so that the tangent line 38a passes above the tangent line 39a. has been done.

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

The sheet carry-in path 41 includes an upper carry-in guide 41a and a lower carry-in guide 41b that are vertically opposed to each other along the sheet conveyance direction so as to guide the leading edge of the sheet to be carried into the nip portion 38 of the pair of registration rollers 33. have The upper carry-in guide 41a allows the sheet to be delivered from the upstream side to the discharge roller pair 37 to be aligned with the sheet carry-in path when the leading edge of the sheet abuts against the nip portion 38 of the pair of registration rollers 33 to align the leading edge positions as described above. In order to secure a space that can be bent in a loop shape within the registration roller pair 41, the registration roller pair 33 is enlarged upwardly toward the entrance side.

As shown in FIG. 2, the central conveyance path 42 includes upper and lower sheets arranged vertically and oppositely 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 conveyance guide 45 and a lower conveyance guide 46. The sheet is conveyed through the central conveyance path 42 while being regulated by upper and lower conveyance guides 45 and 46 from both sides in the thickness direction (in this embodiment, from above and below).

As described above, since the tangent line 38a passing through the nip part 38 of the pair of registration rollers 33 and the tangent line 39a passing through the nip part 39 of the pair of folding rollers 34 are arranged horizontally and with their vertical heights shifted, the upper conveyance guide 45 , a first horizontal portion 45a extending horizontally to the downstream side along the tangent line 38a, a second horizontal portion 45b extending horizontally to the upstream side along the tangent line 39a, and a first horizontal portion 45b extending horizontally from the upstream side to the downstream side so as to connect both the tangent lines 38a and 39a. It has a slope portion 45c that slopes downward to the side.

As shown in FIG. 2, the inclined portion 45c is formed in a straight line from the upstream end of the second horizontal portion 45b diagonally upward to the right in the figure. The inclined portion 45c and the second horizontal portion 45b intersect linearly, and the connecting portion thereof has a convex portion 47 that is formed of a relatively large obtuse corner and that is convex toward the generally downward direction of the central conveyance path 42. It is 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.

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

In this embodiment, as shown in the figure, the first horizontal portion 45a, the inclined portion 45c, and the upstream portion of the second horizontal portion 45b are formed by one continuous first upper conveyance guide member, and the second The downstream portion of the horizontal portion 45b is formed by another second upper conveyance guide member. The first and second upper conveyance guide members are arranged substantially continuously so as not to interfere with the conveyance of the sheet in the central conveyance path 42. Further, the first upper conveyance guide member can 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 located at the position shown in FIG. Various other settings can be made.

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

As shown in FIG. 2, a relatively large loop forming space 50 is provided below the gap 48 of the lower conveyance guide 46. When the veneer 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 made to hang down from the gap 48 into the loop forming space 50. When the veneer 35 advances (indicated by an imaginary line 35' in FIG. 2) and the gap 48 is closed, the sheet sent out from the pair of registration rollers 33 does not hang down into the loop forming space 50, but instead flows through the central conveyance path 42. can be conveyed toward the folding roller pair 34 along the folding roller pair 34.

The first lower guide portion 46a includes a first horizontal guide portion 51a extending horizontally from the pair of registration rollers 33 to the downstream side and generally facing the first horizontal portion 45a of the upper conveyance guide 45, and further downstream from there. It has a first inclined guide portion 51b that is inclined approximately halfway and substantially parallel to the inclined portion 45c of the upper conveyance guide. The downstream end of the first inclined guide portion 51b defines the position at which the sheet guided through the central conveyance path 42 starts to hang down when the gap 48 is opened. In this embodiment, as shown in the figure, the downstream end of the first inclined guide portion 51b is located above the tangent line 39a passing through the nip portion 39 of the pair of folding rollers 34.

The second lower guide portion 46b includes a second horizontal guide portion 52a that extends horizontally from the folding roller pair 34 to the upstream side, a second inclined guide portion 52b that slopes downward from the second horizontal guide portion to the upstream side, and It has a vertical guide part 52c extending generally vertically downward from the second inclined guide part. The second horizontal guide part 52a cooperates with the second horizontal part 45b of the upper conveyance guide 45 to regulate the sheet from both sides in the thickness direction, that is, in the vertical direction, and folds the leading edge of the sheet at the nip between the pair of rollers 34. I will guide you to 39. The second inclined guide portion 52b is inclined toward the loop forming space 50 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, together with the second inclined guide portion 52b, separates the sheet hanging down into the loop forming space 50 from the folding roller pair 34 side while ensuring the dimensions of the loop forming space 50.

When the thrusting plate 35 is in the retracted position, the sheet sent out from the pair of registration rollers 33 to the central conveyance path 42 is guided by the upper conveyance guide 45 and the first lower guide portion 46a and reaches the downstream end of the first inclined guide portion 51b. When the sheet exceeds 1, the sheet hangs down in a straight line into the loop forming space 50 through a gap 48 opened downward from the leading edge of the sheet. On the other hand, when the gap 48 is opened with the leading edge of the sheet being nipped by the pair of folding rollers 34 and the pair of folding rollers having stopped rotating, the sheet in the central conveyance path 42 is moved between the gaps 48 and 34, as will be described later. It is curved into a loop shape and hangs down in the loop forming space 50 through it.

In other words, the central conveyance path 42 includes a first path section for feeding the sheet from the pair of registration rollers 33, a second path section that can selectively open the central conveyance path 42 to the loop forming space 50 below, and a second path section for folding the sheet. and a third path section that guides the roller pair 34 to the nip section 39. The first to third path sections are substantially continuous in the sheet conveyance direction on the upper surface side of the sheet by an upper conveyance guide 45 made up of the first and second upper conveyance guide members. On the lower surface side of the seat, the first path portion is formed by a fixed first lower guide portion 46a, and the third path portion is formed by a fixed second lower guide portion 46b. , the second path section is composed of a gap 48 that is opened and closed by the movement of the veneer 35.

In another embodiment, the first path portion may be formed only by a horizontal guide portion, omitting the first inclined guide portion 51b. In FIG. 2, the upper conveyance guide 45 has a transition position from the inclined portion 45c to the second horizontal portion 45b within the gap 48 of the second path portion, but the present invention is not limited thereto. As long as the second lower guide portion 46b also guides the sheet hanging down in the loop forming space 50 to the nip portion 39 of the pair of folding rollers 34, the second inclined guide portion 52b may be made smaller than that shown in FIG. 2 or eliminated. As long as sufficient loop forming space 50 is secured, the vertical guide portion 52c can be made smaller or eliminated.

The sheet unloading path 43 includes an upper unloading guide 43a and a lower unloading guide 43b that are vertically opposed to each other along the sheet conveying direction so as to guide the folded sheet to the sheet unloading port 32b. In front of the sheet ejection port 32b, there is an additional folding mechanism having a plurality of rolling elements that move on a lower ejection guide 43b in the sheet width direction perpendicular to the sheet conveyance direction to increase the number of folds in the folded sheet. 36 are provided.

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

When the veneer plate 35 is in the retracted position, the gap 48 of the lower conveyance guide 46 is completely opened, and the second path portion of the central conveyance path 42 is opened to the loop forming space 50 below, as shown in the figure. Ru. Therefore, the sheet in the central conveyance path 42 can hang down from the central conveyance path 42 into the loop forming space 50, as will be described later.

At the guide position indicated by the imaginary line 35', the thrust plate 35 completely closes the gap 48 of the lower conveyance guide 46, and at the same time vertically faces the upper conveyance guide 45 to form a part of the lower conveyance guide 46. Thereby, the sheet in the central conveyance path 42 is guided along the second path section without hanging down into the loop forming space 50, and is conveyed from the first path section to the third path section.

At the thrust position indicated by the imaginary line 35'', the thrust 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 in 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 pair of folding rollers 34 at its leading end.

FIG. 4 specifically shows an enlarged example of a suitable arrangement of the veneer plate 35 in the retracted position. As shown in the figure, there is a height H 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 thereto. A vertical gap is defined. Thereby, the third path portion of the central conveyance path 42 has a straight portion 66 that extends horizontally and linearly from the folding roller pair 34 to the upstream side.

The height H of the straight portion 66 is between the second horizontal portion 45b of the upper conveyance guide 45 and the second horizontal guide portion 52a of the lower conveyance guide 46 on both upper and lower sides of the veneer 35 located within the straight portion. Settings are made so that several sheets can be passed smoothly in an overlapping state. In this embodiment, the thickness is set to 2 mm, for example, in consideration of the thickness of two sheets that can be used in the image forming apparatus A so that a sheet folded in two can be passed through. Thereby, the pushing plate 35 can smoothly move within the third path portion to the pushing position while pushing the sheet with its tip in the folding process described later.

It is preferable that the pushing plate 35 is disposed such that, at the pushing position, its tip is close to the nip portion 39 of the pair of folding rollers 34 within the gap of the straight portion 66 of the third path portion. Therefore, in the retracted position, the veneer 35 in FIG. It is placed horizontally within the H range. From this retracted position, the thrust plate 35 moves horizontally and linearly with its tip toward the nip portion 39 of the pair of folding rollers 34.

More specifically, in FIG. 4, the veneer 35 of this embodiment is placed on or slightly below a tangent 39a extending upstream from the nip portion 39. 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 veneer 35 is not limited to the height H range of the extension line 66a of the straight portion 66. If the thrusting plate 35 that moves toward the folding roller pair 34 can move horizontally along the third path section along the upper conveyance guide 45 and bring its tip close to the nip section 39 at the thrusting position, as shown in FIG. The retracted position can be provided at a position different from 4.

FIGS. 3(a) and 3(b) show the structure of the veneer plate 35 in more detail. As shown in the figure, in this embodiment, four pairs of folding rollers 34 consisting of upper and lower folding rollers 34a and 34b are attached to upper and lower roller shafts 55 and 56, respectively. The four pairs are arranged symmetrically along the axial direction of the roller shafts 55, 56, with two pairs on each side on the left and right sides with respect to the center position thereof. At the tip of the veneer 35, four notches 57 are formed along the sheet width direction, corresponding to the positions of the four pairs of folding rollers 34, and having shapes and dimensions corresponding to the shapes of the pairs of folding rollers. It is recessed.

The movement of the thrust plate 35 between the retracted position, the guide position, and the thrust position is performed by driving the thrust plate drive motor MT3 of the drive mechanism shown in FIG. 5, which will be described later. The drive of the veneer drive motor MT3 is controlled by the control section 120 shown in FIG. 5 as described later.

[Drive mechanism of sheet folding device]
FIGS. 3A and 3B show drive mechanisms 58 to 60 for the registration roller pair 33, the folding roller pair 34, and the thrust plate 35 of the sheet folding device C. In the registration roller pair 33, a drive roller 33a is attached to a roller shaft 61 rotatably installed in the sheet width direction so as to rotate together with the roller shaft 61. In the folding roller pair 34, the upper and lower folding rollers 34a and 34b are respectively attached to roller shafts 55 and 56 that are rotatably installed in the sheet width direction so as to rotate together.

The drive mechanism 58 of the registration roller pair 33 includes a registration roller drive motor MT1, a drive pulley P1 attached to its rotating shaft, a driven pulley P2 attached to one end of the roller shaft 61 of the drive roller 33a, and both pulleys P1. , 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 rotating shaft, a driven pulley P4 attached to the roller shaft 56 of the lower folding roller 34b, and both pulleys P3, P4. A timing belt TB2 is provided. Furthermore, the drive mechanism 59 includes a gear Z1 that is coaxially and integrally rotatably attached to the roller shaft 56, and a gear Z2 that is coaxially and integrally rotatably attached to the roller shaft 55 of the upper folding roller 34a and meshes with the gear 1. Equipped with.

The driving force of the folding roller drive motor MT2 is transmitted from its rotating shaft 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 drive motor MT2 is transmitted from the roller shaft 56 to which the driven pulley P4 is attached to the upper folding roller 34a via gears Z1 and Z2 that mesh with each other. Thereby, the upper folding roller 34a and the lower folding roller 34b rotate in synchronization with each other in 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 veneer 35 includes a veneer drive motor MT3, a drive pulley P5 attached to its rotating shaft, a rotating shaft 62 installed in the sheet width direction, and a driven pulley P6 attached to one end of the rotating shaft 62. , a timing belt TB3 stretched between both pulleys P5 and P6, a first rack and pinion mechanism 63 provided on the one end side of the rotating shaft 62 inwardly from the driven pulley P6, and the other end of the rotating shaft 62. A second rack and pinion mechanism 64 is provided.

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

The driving force of the veneer drive motor MT3 is transmitted from its rotating shaft to the first and second pinions 63a and 63b via a transmission mechanism consisting of a drive pulley P5, a timing belt TB3, and a driven pulley P6. As a result, the first and second racks 63b and 64b move in synchronization with each other in the same direction, and work together to move the veneer 35 in the horizontal direction.

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

The first detection sensor S1 is arranged in front of the pair of registration rollers 33 in the sheet carry-in path 41, and detects the leading edge of the sheet carried in from the image forming apparatus A through 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 thrusting plate 35 that moves between the retracted position, the guide position, and the thrusting 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.

Furthermore, the control section 120 is connected to the control section 121 of the image forming apparatus A via the sheet post-processing device B. The control section 121 is connected to an input section and a display section (not shown) provided on a 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 mode executed by the sheet folding device C is transmitted from the control section 121 to the control section 120 via the sheet post-processing device B. .

When the registration roller drive motor MT1, the folding roller drive motor MT2, and the veneer 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 above 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 the conveyance of the sheet in the conveyance path 32 and the folding operation of the sheet folding device C.

Further, the control unit 120 can transmit information on sheet conveyance, folding processing, etc. being executed in the sheet folding device C to the control unit 121 of the image forming apparatus A via the sheet post-processing device B in real time. can. If the information received from the control unit 120 includes unfavorable information or information that requires caution or warning, such as a defective sheet conveyance or defective folding process in the sheet folding device C, the control unit 121 transmits the information to the user. For example, the display section of the setting panel D can be used to notify.

The sheet folding device C of this embodiment is suitable for folding a sheet into three by so-called Z-folding by alternately folding the sheet inward and outward along the sheet conveyance direction. FIG. 6 shows an example of a sheet SH that has been Z-folded by the sheet folding device C from the sheet width direction. In the same figure, a first fold 202 is formed on the sheet SH at a predetermined length position upstream from the leading end (downstream end) 201 in the sheet conveyance direction, and from there, the first fold line 202 is folded downstream and at a predetermined length position. A second crease 203 is formed on. The folding operation of the sheet folding device C will be explained below.

[Processing operation of sheet folding device]
The sheet folding device C is preset with a folding mode (Z-folding) in which a sheet is folded into three (Z-folding) and a no-folding mode in which the sheet is not folded. Before starting image formation on the sheet in the image forming apparatus A, the user decides whether or not to fold the sheet on which the image has been formed. Select and enter. The input of the folding process mode is stored in the control unit 121 of the image forming apparatus A as sheet information of the sheet to be subjected to the folding process.

The entire processing operation in the sheet folding device C will be schematically explained using the flowchart in 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 device C uses this as a trigger to 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).

If the sheet information acquired from the control unit 121 of the image forming apparatus A includes a selection of the folding mode or an instruction to execute the folding process (Y in step ST03), the process advances to steps ST04 to ST06 to execute the folding process. If the sheet information from the image forming apparatus A does not include a selection of a folding mode or an instruction to execute a folding process, or if it includes an instruction not to perform a folding process, the process proceeds to step ST07 to execute a non-folding process.

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

The folding process in steps ST04 to ST06 as a whole includes a resist process by the resist roller pair 33 (step ST04), a fold loop process by the fold roller pair 34 (step ST05), and a crease forming process by the veneer plate 35 and the fold roller pair 34. This is carried out in three stages (step ST06). In the registration process, the leading edge of the sheet carried into the sheet folding device C is aligned to correct sheet skew (oblique feeding). In the folding loop process, a loop for forming a fold is formed on the leading end side of the sheet. In the crease forming process, creases are formed on the sheet in which the loops have been formed by the folding roller pair 34.

The processing in each step ST04 to ST06 will be specifically explained below using FIGS. 8 to 15. FIGS. 8(a) to 8(f) show, in order of process, a process in which the sheet folding device C carries in a sheet from the image forming apparatus A, conveys it, and folds it.

[Regist processing]
FIG. 8A shows a state in which the leading edge of the sheet is aligned in the registration process of the sheet folding device C. The registration process is executed, for example, according to the procedure shown in the flowchart of FIG.

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 ST10) with the registration roller pair 33 stopped rotating, the control unit 120 detects that the built-in A fold loop counter (not shown) starts counting (step ST11). When a predetermined period of time has elapsed after the folding loop counter started counting (Y in step ST12), the registration roller drive motor MT1 is driven (step ST13) to rotate the pair of registration rollers 33.

During the predetermined period of time in step ST12, the leading edge of the sheet contacts the nip portion 38 of the pair of registration rollers 33, and a loop-shaped deflection of a size necessary and sufficient to align the leading edge position is applied to the sheet carry-in path 41. This is the time required to form the sheet into a sheet. This time can be determined in advance based on test results, etc., and set in the control unit 120, for example.

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. 8(b). At this time, the thrust plate 35 is placed at the guide position 35'. Therefore, the leading edge of the sheet is guided along the central conveyance path 42 by the upper surface of the veneer 35 and is fed straight toward the nip 39 of the pair of folding rollers 34. The sheet whose leading edge has passed through the convex portion 47 of the central conveyance path 42 is moved in the sheet conveyance direction in the area where the inclined portion 45c and the second horizontal portion 45b of the upper conveyance guide 45 connect, that is, in the area facing the gap 48. It is pushed downward by the convex portion 47 and curves convexly toward the loop forming space 50 side.

[Fold loop processing]
The folding loop process is executed, for example, according to the procedure shown in the flowchart of FIG. The control unit 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, when the second detection sensor S2 detects the leading edge of the conveyed sheet immediately upstream of the folding roller pair 34 and turns on (Y in step ST21), the control unit 120 executes a retraction process to move the thrust plate 35 from the guide position to the retraction position (step ST22).

This retraction process of the veneer 35 is executed, for example, according to the procedure shown in the flowchart of FIG. 11. The control unit 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' upstream in the sheet conveyance direction toward the retracted position. The thrust plate 35 of this embodiment is provided with a detection flag (not shown) at its upstream end in the sheet conveyance direction.

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

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

Thereby, the sheet is held in a state where the leading end is nipped in the nip portion 39 of the pair of folding rollers 34, as shown in FIG. 8(c). Even after this, the registration roller drive motor MT1 continues to be driven, and the registration roller pair 33 continues to rotate and feed out the sheet. As a result, the portion of the sheet upstream of the folding roller pair 34 hangs down from the gap 48 into the loop forming space 50, forming a folding loop FL for forming a crease in the sheet. Even after that, the loop FL increases in accordance with the amount of sheet feeding by the pair of registration rollers 33.

In this embodiment, the sheet feeding amount (conveying distance) from the position where the leading edge of the sheet is detected by the second detection sensor S2 to the position beyond the nip portion 39 of the folding roller pair 34 by 10 mm is determined by the corresponding registration roller. The first set drive amount is set in terms of 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 rotating shaft, rotation angle, rotation time, etc.) and the amount of sheet feeding 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.

For sheets that can be folded, the sheet folding device C determines the folding position, which is expressed as the distance from the leading edge of the sheet in the sheet conveyance direction, depending on the size and the orientation of the sheet at the time of conveyance (vertical direction, horizontal direction). is determined, and a predetermined count value corresponding to each folding position is set in advance 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 in step 11 counts up to the predetermined count value (Y in step ST25), the next crease forming process (step ST06) to move to.

[Crease formation process]
The crease forming process is executed, for example, according to the procedure shown in the flowchart of FIG. 12. The control unit 120 starts the punching process of the punching plate 35 at the same time as the folding loop counter counts up in step ST25. At this time, as shown in FIG. 8(d), the loop forming space 50 has a size suitable for forming a crease at a predetermined folding position on the sheet by continuous feeding of the sheet by the registration roller pair 33. A fold loop FL is formed.

The punching process is executed, for example, according to the procedure shown in the flowchart of FIG. 13. First, the veneer drive motor MT3 is driven to rotate normally (step ST53), and the veneer 35 is horizontally moved toward the folding roller pair 34 side. At this time, the tip of the thrust plate 35, which has started to move downstream from the retracted position, hits the folding loop FL on the upstream extension of the straight portion 66 of the third path portion of the central conveyance path 42. More specifically, in FIG. 4, the veneer plate 35 abuts against the folding loop FL at a position where the folding loop FL intersects with an extension line 66a extending upstream from the straight portion 66 of the third path section.

This intersection position is close to the downstream end of the first lower guide portion 46a of the lower conveyance guide 46 where the folded loop FL begins to hang down. Therefore, even if the degree of hanging, that is, the degree of curvature of the folding loop FL varies depending on the rigidity and other characteristics of the sheet, the amount of sheet feeding from the pair of registration rollers 33, etc., it does not change much. Therefore, the tip of the abutting plate 35 can be abutted with high accuracy at a predetermined position of the sheet that becomes the second fold line 203 when viewed from the sheet leading edge side, and positional deviations and variations can be eliminated or reduced.

Further, the pushing plate 35 moves toward the nip portion 39 of the pair of folding rollers 34 while pushing the sheet at a predetermined position with its tip. FIG. 14 shows in detail the process in which the thrust plate 35 moves downstream through the second path section of the central conveyance path 42. As shown in the figure, the thrust plate 35 moves horizontally and linearly along the tangent line 39a of the nip portion 39 from the retracted position described above in connection with FIG.

While the veneer plate 35 passes below the second horizontal portion 45b of the upper conveyance guide 45, a narrow gap is maintained between the top surface and the second horizontal portion 45b, which is large enough to allow two sheets to pass smoothly as described above. be done. Thereby, even if the sheet portion on the upstream side from the tip of the veneer plate 35 becomes slack, it is maintained substantially horizontally in a straight line between the narrow gaps and is conveyed. Therefore, the predetermined position of the sheet against which the abutment plate 35 is abutted is maintained without shifting from the tip of the abutment plate to the upstream side or downstream side of the sheet.

The control unit 120 controls the veneer drive motor MT3 to control the moving speed of the veneer 35. In this embodiment, the moving speed of the pushing plate 35 is substantially the same as the conveying speed of the sheet sent out by the pair of registration rollers 33, except immediately after starting the movement from the retracted position and immediately before stopping at the pushing position. is set to This prevents the following problem that may occur if the moving speed of the thrusting plate 35 is different from the sheet conveying speed by the pair of registration rollers 33.

For example, if the moving speed of the thrusting plate 35 is faster than the conveyance speed of the sheet by the registration roller pair 33, while the sheet is pushed against the thrusting plate 35 and moving through the central conveyance path 42, the tip of the thrusting plate 35 and the registration roller pair 33, and as a result, there is a risk that the abutment position of the abutting plate 35 may shift upstream from the predetermined position of the sheet, or the sheet may slip at the nip portion 38 of the pair of registration rollers 33. Conversely, if the moving speed of the veneer plate 35 is slower than the conveyance speed of the sheet by the pair of registration rollers 33, the sheet will loosen between the tip of the veneer plate 35 and the pair of registration rollers 33. There is a possibility that the sheet may curve within the gap between the horizontal portion 45b and the veneer 35, or the abutment position of the veneer 35 may shift downstream from the predetermined position of the sheet. In this embodiment, this problem is solved, and the pushing plate 35 moves together with the sheet to the pushing position without the pushing position shifting from the predetermined position of the sheet.

When the sheet that is pushed by the thrust plate 35 and moves downstream in the central conveyance path 42 enters the third path section, the sheet portion on the upper side with the thrust plate 35 in between passes through the second horizontal portion of the upper conveyance guide 45. 45b from above, and the lower sheet portion is regulated from above by the second horizontal guide portion 52a of the second lower guide portion 46b, and the sheet leading end portion on the upstream side of the nip portion 39 of the pair of folding rollers 34 is moved to the second horizontal direction. It is sandwiched between the guide part and regulated from below. As a result, while the sheet travels along the third path, the sheet does not slip upstream or downstream between the tip of the veneer 35 and reaches the predetermined position where the veneer 35 abuts. It is temporarily folded into a bent form. This temporarily folded bending position is pressed and bent by the subsequent pair of folding rollers 34 to become the second fold line 203 of the folded sheet shown in FIG.

When the drive amount of the veneer drive motor MT3 reaches a 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 tip of the thrust plate 35 is located 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 at the third path portion. 52a and stops at the punching position 35''.Thereby, the folding position FP2, which is the second fold of the sheet, is bent by the above-mentioned temporary folding and is located at the nip portion of the pair of folding rollers 34. It will be carried until just before 39th.

In this way, by inserting the veneer 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. Ru. After the sheet is temporarily folded in this way, the sheet is nipped and folded by the pair of folding rollers 34 at the folding position, thereby preventing the folded portion of the sheet from opening at the second fold line and producing a folded sheet with a good appearance. .

Here, the second set drive amount is the drive amount of the veneer drive motor MT3 required to move the veneer plate 35 from the retracted position to the thrust position 35''. can use the amount of rotation of the motor (rotation speed of the rotating shaft, rotation angle, rotation time, etc.).

After the veneer drive motor MT3 is stopped in step ST58, when the registration roller drive motor MT1 is driven to a preset third set drive amount (Y in step ST31), the control unit 120 controls the folding roller drive motor MT2 is driven (step ST32). Here, the third set drive amount is a position where the sheet is continuously fed out even after the thrust plate drive motor MT3 is stopped in step ST58, and the folding position FP2 of the sheet is caught in the nip portion 39 of the pair of folding rollers 34. This is the drive amount of the registration roller drive motor MT1 that rotates the registration roller pair 33 until .

When the folding roller pair 34 is rotated by the drive of the folding roller drive motor MT2, as shown in FIG. , while being conveyed to the downstream side, it is folded under pressure between upper and lower folding rollers 34a and 34b. By this pressure processing, a second fold line F2 (203) is formed in the sheet at a predetermined fold position. As described above, the folding position FP2 of the sheet is conveyed in a bent form without slipping or positional deviation in the sheet conveying direction, and is caught in the nip portion 39 of the pair of folding rollers 34 as it is, so that the sheet is folded at the second fold F2. The position of is stabilized with high precision without the conventional variations.

When the folding roller drive motor MT2 is driven in step ST32, the control unit 120 returns the pushing plate 35 from the pushing position 35'' to the retracted position so as not to prevent the sheet from being rolled into the nip portion 39 of the folding roller pair 34. A saving process is executed (step ST33). This saving process is performed in the same manner as described using FIG. 11 and FIGS. 8(b) and 8(c) in connection with the folding loop process.

That is, in the state shown in FIG. 8(e), the control unit 120 reversely drives the thrusting plate drive motor MT3 to move the thrusting plate 35 from the thrusting position 35'' horizontally upstream in the sheet conveyance 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 35 and turns on, the veneer drive motor MT3 is stopped.Thereby, the veneer 35 is moved. It is placed in the retracted position as shown in FIG. 8(f).

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 loop forming space 50 below. Therefore, the folding loop FL can be smoothly rolled into the nip portion 39 of the pair of folding rollers 34 continuously from the start of rolling as shown in FIG. 8(e) without being hindered by the thrust plate 35.

The folding roller pair 34 continues to be driven to rotate even after the retreating process of the veneer 35. Therefore, as shown in FIG. 8(f), the sheet is folded into three (Z-fold) with its leading edge and the second fold F2 formed by the folding roller pair 34 first, and then the folding roller The sheets are nipped in pairs and conveyed downstream along the sheet discharge path 43.

As the sheet is transported in this manner, the folding loop FL within 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. , it becomes a thin loop shape extending in the sheet conveyance direction. Furthermore, 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 is folded from above and below at the folding position FP1 at the rear end (upstream end), which becomes the first fold. It is bent in half.

The folding position FP1 of the sheet is bent in this way and is conveyed without slippage or positional deviation in the sheet conveyance direction between it and the upstream side portion of the sheet stacked thereon, and the folding roller pair 34 It is bent under pressure at the nip portion 39 of. Therefore, the first fold line (202 in FIG. 6) is stably formed at a desired position on the sheet with high precision, without causing variations as in the conventional method.

As a result, as shown in FIG. 6, a Z-folded sheet SH is generated in which a first fold line 202 of the inner fold and a second fold line 203 of the outer fold are formed. In this embodiment, as described above, the folding roller pair 34, which is not rotating, forms the folding loop FL by nipping the leading edge of the sheet, and then the folding roller pair 34 is rotated to form the second and first folding loops. Since the fold is formed by folding, the leading edge portion of the sheet that was nipped when forming the fold loop FL is Z-folded in a form that protrudes from the second fold line toward the leading edge side (downstream side).

Next, when the first detection sensor S1 in the sheet carry-in path 41 detects the rear end of the sheet being conveyed by the pair of registration rollers 33 and the pair of folding rollers 34 and turns off (Y in step ST34), the control unit 120 executes a guide process to move the thrust plate 35 from the retracted position to the guide position 35' (step ST35). At this time, the folding loop FL is set to have already passed through the folding roller pair 34. Therefore, even if the pushing plate 35 is moved to the guide position 35', there will be no problem in conveying the sheet in the central conveying path 42 and in the fold forming process by the pair of folding rollers 34.

The guide processing is executed according to the procedure shown in the flowchart of FIG. 15, for example. The veneer drive motor MT3 is driven to rotate normally (step ST56), and the veneer 35 is horizontally moved toward the folding roller pair 34 side. When the drive amount of the veneer drive motor MT3 reaches a 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 veneer 35, so that the rear end of the sheet is guided along the central conveyance path 42 by the upper surface of the veneer 35, and the rear end of the sheet is guided by the folding roller. It is conveyed straight towards pair 34. The rotation amount of the motor (rotation speed, rotation angle, rotation time, etc. of the rotating shaft) can be used as the drive amount of the veneer drive motor MT3.

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 unit 120 controls the folding process from that point on. The drive amount of the roller drive motor MT2 is counted, and when the predetermined 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 rear end of the sheet to pass through the folding roller pair 34. As a result, the pair of registration rollers 33 and the pair of folding rollers 34 stop rotating without causing any trouble in carrying out the sheet from the sheet carrying out port 32b to the sheet post-processing device B, and the Z-folding process of the sheet is completed.

16(a) and 16(b) show another embodiment of the first lower guide portion 46a forming the lower conveyance guide 46 of the central conveyance path 42. FIG. The first lower guide portion 46a of this embodiment has a lower partition wall portion 51c extending vertically downward from the downstream end of the first inclined guide portion 51b toward the loop forming space 50, as shown in FIG. Different from the embodiment.

Furthermore, a slit 51d is formed in the lower partition wall portion 51c, through which the veneer plate 35 moving toward the folding roller pair 34 passes. The slit 51d is opened at a position facing the nip portion 39 of the pair of folding rollers 34 on a tangent line 39a thereof. As a result, the veneer plate 35 is provided under the first lower guide portion 46a (the first horizontal guide portion 51a and the first inclined guide portion 51b) and on the upstream side of the lower partition wall portion 51c, as in the above embodiment. From the position, it can be moved horizontally and linearly toward the nip 39 along the tangent 39a.

By providing the lower partition wall portion 51c in the first lower guide portion 46a, the sheet hanging down from the downstream end of the first inclined guide portion 51b toward the loop forming space 50 side is placed on the lower side of the first lower guide portion 46a and the thrust plate 35. This eliminates the risk of being caught upstream. As a result, the folding loop FL of the sheet is partitioned from the registration roller pair 33 side by the lower partition wall 51c, and is formed so as to fit within the loop forming space 50 on the downstream side thereof, as shown in FIG. 16(a). Ru.

As described in connection with the above embodiment, the folding loop FL is already partitioned from the folding roller pair 34 side by the vertical guide portion 52c of the second lower guide portion 46b, and is separated into the loop forming space 50 on the upstream side thereof. formed to fit. Therefore, the folding loop FL is regulated from both the upstream side and the downstream side by the lower partition wall 51c and the vertical guide section 52c within the loop forming space 50, so even if the sheets have slightly different rigidities, they are generally the same. It is formed into a curved loop shape. As a result, the position of the abutting plate 35 against the sheet is stabilized, and the sheet can be folded at the desired predetermined position with high precision.

According to another embodiment of the present invention, the central conveyance path 42 may be provided so as to connect the registration roller pair 33 and the folding roller pair 34 in a straight line. In this case, the registration roller pair 33 and the folding roller pair 34 may be arranged with their nip portions 38 and 39 at the same height position to form the central conveyance path 42 horizontally, or may be arranged at different height positions. The central conveyance path 42 can also be inclined.

In either case, the upper conveyance guide 45 is formed into a substantially continuous straight line with the inclined portion 45c and the convex portion 47 omitted, and the first lower guide portion 46a of the lower conveyance guide 46 is formed in the first lower guide portion 46a. The inclined guide part 51b is omitted, and only the first horizontal guide part 51a is formed. A gap 47 on the downstream side of the first lower guide portion 46a is maintained between the first lower guide portion 46a and the second lower guide portion 46b, similarly to the above embodiment. It is preferable that the second lower guide portion 46b is configured similarly to the above embodiment.

FIGS. 17 and 18 schematically show a modification of such a central conveyance path 42. As shown in FIG. In the embodiment of FIG. 17, the abutment plate 35 is disposed immediately below the first lower guide portion 46a in its retracted position. In the embodiment shown in FIG. 18, the abutment plate 35 is disposed directly above the first lower guide portion 46a in an overlapping manner in its retracted position.

In the embodiments of FIGS. 17 and 18, the first lower guide portion 46a is arranged at a somewhat higher position than the second horizontal guide portion 52a of the second lower guide portion 46b, so that one sheet can pass smoothly. It is preferable to make the vertical gap with the upper conveyance guide 45 sufficiently small. As a result, the thrust plate 35 can linearly move along the tangent 39a along the central conveyance path 42 toward the nip portion 39 of the pair of folding rollers 34, similarly to the embodiment described above.

As shown in both figures, the sheet whose leading end has been folded and nipped by the pair of rollers 34 is sent out from the pair of registration rollers 33 and guided by the upper conveyance guide 45 and the first lower guide portion 46a to the first horizontal guide portion. It begins to curve from the downstream end of 51a, hangs down through the gap 48, and forms a folded loop FL in the loop forming space 50. Therefore, similarly to the embodiment described above, the veneer plate 35 can abut against the sheet near the position where the folding loop FL begins to hang down. Note that the other configurations in the embodiments of FIGS. 17 and 18 are substantially the same as those of the above embodiments, so description thereof will be omitted.

The sheet folding device C of the present invention can not only perform the above-mentioned Z-folding but also fold a sheet in two. Furthermore, the present invention has a configuration in which a pushing member is abutted against the folding position of a sheet hanging down from a conveyance path into a space defined below the conveyance path, and the sheet is pushed up to the nip portion of a pair of folding rollers and folded. If so, the same can be applied.

19(a) and 19(b) schematically show the process of folding a sheet in half using the sheet folding device C shown in FIG. As shown in FIG. 19(a), with the thrust plate 35 placed in the retracted position and the gap 48 of the central conveyance path 42 opened, the registration roller pair 33 is rotated, and the sheet Sh is transferred to the central conveyance path 42. send out. When the leading end of the sheet Sh is guided by the upper conveyance guide 45 and the lower conveyance guide 46 and passes through the first lower guide portion 46a, the sheet Sh passes through the gap 48 from its downstream end and hangs down into the loop forming space 50.

When the feed amount of the sheet from the pair of registration rollers 33 reaches a predetermined feed amount set in advance, the control unit 120 drives the thrusting plate drive motor MT3 to move the thrusting plate 35 from the retracted position toward the thrusting position. start moving. This predetermined feed amount is set so that the position where the tip of the veneer plate 35 abuts on the sheet Sh hanging down in the loop forming space 50 is a predetermined position that becomes a fold formed in the sheet.

FIG. 19(b) shows how the pushing plate 35 moves to the pushing position while pushing the sheet Sh at the predetermined position. Similar to the Z-folding embodiment described above in connection with FIG. move in a shape.

While the veneer plate 35 is moving, the sheet Sh is continuously fed out from the pair of registration rollers 33, and the moving speed of the veneer plate 35 is set to be equal to the conveyance speed of the sheet by the pair of registration rollers 33. Due to the narrow gap defined between the upper surface of the veneer 35 and the second horizontal portion 45b of the upper conveyance guide 45, the predetermined position of the sheet Sh that is abutted against the veneer 35 can be moved from the tip of the veneer 35 to the sheet Sh. It is maintained without shifting upstream or downstream of Sh.

The sheet portion on the downstream side from the tip of the veneer plate 35 hangs straight downward into the loop forming space 50 when the predetermined position reaches the area of the second lower guide portion 46b of the lower conveyance guide 46 in the sheet conveyance direction. From this state, the second lower guide portion begins to curve along the second inclined guide portion 52b, and when it enters the area of the second horizontal guide portion 52a, it is bent and temporarily folded between it and the second horizontal portion 45b. Ru.

When the thrusting plate 35 reaches the thrusting position and stops, the predetermined position of the sheet Sh is caught in the nip portion 39 of the pair of folding rollers 34 in its bent state, and folded under pressure between the upper and lower folding rollers 34a and 34b. to form a crease at a predetermined folding position. As described above, according to the present invention, the position of the fold line in bi-folding can also be stably and highly accurate without causing variations unlike the conventional method.

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

A Image forming device B Sheet post-processing device C Sheet folding device 31 Housing 32 Conveyance path 33 Registration roller pair 34 Folding roller pair 35 Throat plates 38, 39 Nip section 41 Sheet carry-in path 42 Central conveyance path 43 Sheet discharge path 45 Upper conveyance guide 45a First horizontal portion 45b Second horizontal portion 45c Inclined portion 46 Lower conveyance guide 46a First lower guide portion 46b Second lower guide portion 47 Convex portion 48 Gap 50 Loop forming space 51a First horizontal guide portion 51b First inclined guide Section 52a Second horizontal guide section 52b Second inclined guide section 52c Vertical guide sections 58 to 60 Drive mechanism 120 Control section 121 Image forming apparatus control section 201 Sheet leading edge 202 First fold line 203 Second fold line

Claims (6)

A conveyance path along which the sheet is conveyed;
a feed roller disposed on the conveyance path and conveying the sheet along the conveyance path;
a pair of folding rollers that are disposed on the conveyance path on the downstream side in the conveyance direction in which the feed roller conveys the sheet and nip and fold the sheet;
a space provided between the feed roller and the pair of folding rollers in the vertical direction of the conveyance path so that the sheet hangs down from the conveyance path on the upstream side in the conveyance direction;
a thrusting member that thrusts a predetermined position of the sheet hanging from the conveyance path into the space, and moves the predetermined position of the sheet to a position where it is nipped by the pair of folding rollers;
Equipped with
The conveyance path includes a first path extending upstream in the conveyance direction from the pair of folding rollers, and a second path provided upstream of the first path and above the first path. having a route;
The thrusting member moves from a vertically downward position of the second path on an extension of the first path, and the predetermined position intersects with the extension of the first path of the sheet hanging in the space. A sheet folding device that is arranged so as to strike the sheet. The first path is formed by an upper conveyance guide and a lower conveyance guide extending upstream in the conveyance direction from the pair of folding rollers,
2. The sheet folding device according to claim 1, wherein the second path includes a guide portion that is provided at an angle with respect to the first path and guides the sheet on the upstream side of the space. The thrusting member moves the first position for forming a third path connecting the first path and the second path and a predetermined position of the sheet in which a loop is formed in the space. a second position where the pair of folding rollers nip, and a third position where the third path is retracted from the first position where the third path is formed to open a space between the third path and the space below the third path; The sheet folding device according to claim 1 or 2, wherein the sheet folding device moves to a position of and. The third path includes an upper conveyance guide of the first path extending linearly upstream in the conveyance direction from the pair of folding rollers on the opposite side of the space with the thrusting member in between, and a first conveyance guide. 4. The sheet folding apparatus according to claim 3, wherein the sheet folding device is formed by: the pushing member moved to a position, and the pushing member moves along the upper conveyance guide. The first path includes an upper conveyance guide and a lower conveyance guide that extend linearly from the pair of folding rollers upstream in the conveyance direction so as to restrict the sheet conveyed along the first path from both sides thereof. The sheet folding device according to claim 1, wherein the pushing member moves between the upper conveyance guide and the lower conveyance guide. an image forming unit that forms an image on a sheet;
An image forming apparatus comprising: the sheet folding device according to claim 1 , which folds a sheet sent from the image forming unit.

Images