JP2020189717A - Sheet folding device and image forming device - Google Patents

Abstract

To provide a sheet folding device which can surely perform processing for folding a sheet.SOLUTION: A sheet folding device C comprises: a resist roller pair 33 that feeds out a sheet to a center conveyance passage 42; a folding roller pair 34 that nips a folding position of the sheet to form a folding line; a loop formation space 50 for forming a loop in the sheet, at an upstream side of the folding roller pair; a pushing plate 35 that moves to a pushing position where the folding roller pair is caused to nip the sheet; and a guide part 70. The guide part allows the loop in the sheet to be formed in the loop formation space so that the loop extends from the folding roller pair toward an upstream side, below the center conveyance passage, and regulates the loop in a height direction. When the pushing plate moves to the pushing position while pushing a predetermined position of the sheet having the loop formed in the loop formation space, the folding roller pair nips the predetermined position of the sheet to form a folding line.SELECTED DRAWING: Figure 2

Description

The present invention relates to a sheet folding device that folds a sheet and an image forming apparatus that includes a sheet folding mechanism that folds a sheet.

Conventionally, a sheet folding device that folds a sheet image-formed by an image forming device such as a copying machine or a printer at a predetermined position is widely known. The folding process includes a so-called Z-fold in which the sheet is folded in half at the center position, the sheet is folded inward at two places, and the sheet is alternately folded inward and outward and folded in three.

A paper piece folding device having a feed roller pair on the upstream side of the horizontal upper guide plate, a paper folding roller pair on the downstream side, and a paper piece guide deflection member (that is, a thrust member) on the upstream side of the paper folding roller pair. It is known (see, for example, Patent Document 1). In this device, the paper piece guide deflection member moves from the second position where the paper piece guide deflection member retracts diagonally downward on the upstream side of the paper folding roller pair to the first position where the tip is brought close to the paper piece inlet of the paper folding roller pair. A predetermined position of the paper piece hanging in the space in front of the folding roller is pulled into the paper piece insertion port, and the paper piece is folded in half or Z-folded.

On the other hand, an in-body paper ejection type image forming apparatus is widely adopted, which is designed to have a compact plane size and is vertically designed, and has a paper ejection space provided between an image reading unit and an image forming unit. Further, there is known a configuration in which a sheet processing apparatus that folds and ejects an image-formed sheet is arranged in a paper ejection space of the image forming apparatus (see, for example, Patent Document 2).

JP-A-2002-68583 Japanese Unexamined Patent Publication No. 2012-224451

In the conventional device described in Patent Document 1, since the predetermined position of the hanging piece of paper is pushed and moved by the small roller at the tip of the thrust member, it is possible to pull it into the paper piece inlet of the paper folding roller pair, for example, especially for thick paper. In the case of a sheet with high rigidity, that is, a strong seat, it is not always easy. Therefore, there is a risk of causing a sheet folding failure or a transport failure.

Further, the conventional apparatus described in Patent Document 1 tends to be large in size because a space for hanging a piece of paper to be folded is indispensable in front of a pair of paper folding rollers. Therefore, it has been difficult to dispose of this in the paper ejection space of the in-body paper ejection type image forming apparatus.

The present invention has been made in view of the above-mentioned conventional problems, and in a sheet folding device that abuts a thrust member at a predetermined position of a sheet and folds it with a pair of folding rollers, the sheet is surely folded. The purpose is.
Further, an object of the present invention is to provide a compact sheet folding device that can be installed even in a narrow space.

The sheet folding device of the present invention
A feed roller that transports the sheet in the transport direction,
A pair of folding rollers arranged on the downstream side in the transport direction of the feed roller and
A thrust member that can move from the upstream side in the transport direction toward the folding roller pair,
A loop forming space for forming a loop on the sheet is provided on the upstream side in the transport direction of the folding roller pair.
When the thrust member abuts a predetermined position of the sheet on which the loop is formed in the loop forming space and moves to a thrust position to be niped by the folding roller pair, the folding roller pair nips the folding position of the sheet. A sheet folding device that forms creases
A loop of the sheet is formed in the loop forming space so as to extend from the folding roller pair toward the upstream side in the transport direction, and a guide portion for restricting the loop of the sheet in the height direction intersecting the transport direction is further provided. It is characterized by being prepared.

In another aspect of the present invention, the image forming apparatus of the present invention includes an image forming unit for forming an image on a sheet and the above-described sheet folding apparatus of the present invention for folding a sheet sent from the image forming unit. It is characterized by having.

According to the sheet folding device of the present invention, a loop is formed in the loop forming space from the folding roller pair toward the upstream side in the transport direction by the guide portion, and is regulated in the height direction. Therefore, the folding roller pair is in the thrust position. The predetermined position of the sheet sent to the sheet can be smoothly niped, and the sheet can be reliably folded. Further, the loop forming space and the entire device can be made compact in the height direction.

The whole block diagram of the image formation system by this invention. Schematic diagram of the sheet folding device. (A) is a perspective view showing the entire drive mechanism of the seat folding device, and (b) is an enlarged part of the main part thereof. The schematic block diagram which shows the 1st sheet reversal part of a sheet folding apparatus. The schematic block diagram which shows the 2nd sheet reversal part of an image forming apparatus. The block diagram which shows the control composition of the sheet folding apparatus. The figures (a) and (b) are a plan view of the sheet before the folding process and an end view of the sheet Z-folded in the first folding mode so that one crease is aligned with the tip side of the sheet in the sheet transport direction. The figures (a) and (b) are a plan view of the sheet before the folding process and an end view of the sheet Z-folded in the second folding mode so that one fold is aligned with the rear end of the sheet in the sheet transport direction. A flowchart illustrating the entire folding operation of the sheet folding device. The flowchart explaining the folding operation setting process of FIG. The flowchart explaining the resist process of FIG. The flowchart explaining the folding loop processing of FIG. FIGS. (A) to (f) are diagrams showing the folding process in the first folding mode in the order of steps. FIGS. (A) to (f) are diagrams showing the folding process of the first folding mode according to the modification of FIG. 13 in the order of steps. FIGS. (A) to (d) are diagrams showing the folding process of the second folding mode according to the second embodiment in the order of steps. The flowchart explaining the save process of FIG. The flowchart explaining the crease formation process of FIG. The flowchart explaining the thrust process of FIG. A flowchart illustrating guide processing. The flowchart explaining the carry-out process of FIG. The figures (a) and (b) are views of the sheet before the folding process and the folded sheet after the folding process in the first folding mode in a plan view. FIGS. (A) to (c) are explanatory views showing a sheet reversing operation of the first sheet reversing section. The figures (a) and (b) are views of the folded sheet immediately after the folding process in the second folding mode and the folded sheet after passing through the first reversing portion, respectively. The figures (a) to (c) show the sheet before the folding process which was inverted in the second sheet inversion section, the folding sheet immediately after the folding process in the second folding mode, and the folding sheet which was further inverted in the first inversion section. A plan view of each.

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

[Image formation system]
FIG. 1 shows the overall configuration of an image forming system of a preferred embodiment according to the present invention. The image forming system of the figure includes an image forming device A, a sheet post-processing device B, and a sheet folding device C. The sheet image-formed by the image forming apparatus A is conveyed through the sheet folding apparatus C and 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 in detail 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 has a paper feeding unit 2, an image forming unit 3, a paper ejection unit 4, and a main body control unit (in the device housing 1). (Not shown). An image reading unit 5 including a scanner unit and an automatic document feeding unit 6 are integrally provided on the upper portion of the device housing 1. The image forming apparatus A of the present embodiment is a so-called in-body paper ejection type, and a front U-shaped paper ejection space E is provided between the image forming unit 3 and the paper discharging unit 4 and the image reading unit 5 in FIG. A sheet post-processing device B and a sheet folding device C are arranged in the paper ejection space E, which is largely defined. In addition to the electrostatic printing mechanism, various other image forming mechanisms such as an inkjet image forming method, an offset printing method, and a silk printing method can be adopted for the image forming apparatus A.

In the paper feed unit 2, a plurality of paper feed cassettes 2a and 2b having different sheet sizes are detachably provided in the device housing 1. The paper feed unit 2 containing the sheet for forming an image feeds a sheet having a size instructed by the main body control unit from the corresponding paper feed cassette to the paper feed path 8. A resist roller 9 is provided in the paper feed path 8, and the sheets whose tips are aligned by the resist rollers are fed to the downstream image forming unit 3 at a predetermined timing.

The image forming unit 3 has 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 developer adheres 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 is transferred is conveyed to the fixing device 11 to be heated and pressurized, and after fixing the toner image, it is carried out to the paper ejection path 12 of the paper ejection unit 4.

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

A sheet circulation path (not shown) can be provided in the paper ejection unit 4. In the sheet circulation path, for example, the paper discharge path 12 is connected to the paper feed path 8 on the downstream side of the fixing device 11 on the upstream side of the resist roller 9. The image-formed sheet sent from the image forming unit 3 to the paper ejection path 12 is switched back to the sheet circulation path by reversing the paper ejection roller of the paper ejection path 12, and the surface is inverted upside down and the image forming unit is again formed. By sending to 3, an image can be formed on both sides of the sheet.

The image reading unit 5 includes a platen 26 on which the original paper is placed, a reading carriage 27 that moves along the platen, and an optical reading means 28 including, for example, a CCD device. The manuscript paper 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 paper set in the paper feed tray 29 to the platen 26.

In the paper ejection space E, the sheet folding device C is arranged at the right end over substantially the entire width to the left and right, and the sheet post-processing device B is continuously arranged up to the left side surface position of the device housing 1. As will be described later, the second paper discharge port 16 of the paper discharge unit 4 is connected to the sheet carry-in port 32a of the sheet folding device C, and the sheet discharge port 32b of the sheet folding device C is the sheet carry-in port of the sheet post-processing device B. It is connected to the port 107. The upper surface of the sheet folding device C forms a substantially flat sheet ejection tray 19 in the paper ejection space E. The first paper ejection port 15 of the paper ejection unit 4 is arranged above the sheet ejection tray 19 so as to open into the paper ejection space.

According to the above-described configuration, the image forming apparatus A reads the document sent from the automatic document feeding unit 6 by the image reading unit 5, and the image forming unit 3 displays an image on the sheet sent from the paper feeding unit 2 according to the read image data. Form. When the image-formed sheet is not folded by the sheet folding device C and post-processed by the sheet post-processing device B, the image-formed sheet is conveyed from the paper ejection unit 4 through the first paper ejection path 13, and is conveyed from the first paper ejection port 15 Is carried out to the sheet discharge tray 19 in the paper discharge space E. When the image-formed sheet is subjected to the folding process and / or the post-processing, the sheet is conveyed from the paper ejection unit 4 via the second paper ejection path 14, and is conveyed from the second paper ejection port 16 to the sheet folding device C. It is fed, and further transported to the sheet post-processing device B and carried out.

[Sheet post-processing device]
As shown in FIG. 1, the sheet post-processing device B includes a transport path 101 for transporting sheets from the sheet folding device C, post-processing equipment such as a staple unit ST1, and a binding processing tray 104 in the housing 100. .. On one side of the housing 100 (left side in FIG. 1), a paper ejection tray 106 for loading and storing sheets ejected from the sheet aftertreatment device B is provided so as to project outward from the paper ejection space E. .. The sheet post-processing device B is arranged so that the sheet carry-in port 107 of the transport path 101 is connected to the sheet discharge port 32b of the sheet folding device C, which will be described later.

The paper ejection port 109 of the transport path 101 is arranged above the binding processing tray so as to face the paper mounting surface of the binding processing tray 104. The sheet sent from the sheet folding device C is discharged from the paper ejection port 109 of the transport path 101 to the paper loading surface of the binding processing tray 104 when the staple binding process is performed by the staple unit ST1. The plurality of sheets accumulated in the binding processing tray 104 are moved to the upstream side in the sheet transport direction on the binding processing tray, and after aligning the upstream end, that is, the rear end in the sheet transport direction, a predetermined position on the sheet rear end side. Is stapled by the staple unit ST1 to form a sheet bundle. The needle-bound sheet bundle is conveyed from the binding processing tray 104 in the sheet transport direction, and is discharged from the discharge port at the downstream end to the paper discharge tray 106 below.

The sheet sent from the sheet folding device C and not subjected to the needle binding process and / or other post-processing by the sheet post-processing device B is discharged from the paper ejection port 109 of the transport path 101 and is discharged as it is from the binding processing tray 104. It is discharged to the output tray 106 from the discharge port at the downstream end.

[Overall configuration of sheet folding device]
As shown in FIG. 2, the sheet folding device C has a transport path 32 formed inside the housing 31 from the sheet carry-in port 32a on the image forming device A side to the sheet discharging port 32b on the sheet post-processing device B side. There is. In the transport path 32, a resist roller pair 33 is arranged on the upstream side, a folding roller pair 34 on the downstream side, and a veneer 35 arranged between the two roller pairs along the sheet transport direction. As described above, the sheet folding device C connects the sheet carry-in port 32a to the second paper discharge port 16 of the image forming device A and the sheet discharge port 32b to the sheet carry-in port 107 of the sheet post-processing device B. Be placed.

As described above, the sheet discharge tray 19 is provided on the upper surface of the housing 31 of the sheet folding device C, and the first paper discharge port 15 of the paper discharge portion 4 that opens into the paper discharge space E is arranged above the sheet discharge tray 19. There is. The sheet discharge tray 19 is formed on the upper surface of the sheet folding device C alone, or optionally in cooperation with the upper surface of the sheet aftertreatment device B adjacent to the upper surface.

Further, an additional folding mechanism 36 can be optionally provided in the vicinity of the sheet discharge port 32b of the transport path 32. In a folding processing mechanism such as a sheet folding device C, in order to reliably fold the conveyed sheet at the crease position, it is possible to provide an additional folding mechanism that pressurizes the sheet at the crease position on the downstream side after the folding processing. It is well known to those skilled in the art.

[Resist roller pair]
The resist roller pair 33 includes an upper drive roller 33a and a lower driven roller 33b arranged so as to sandwich the transport path 32 in the drawing. The driven roller 33b is pressed against the roller surface of the driving roller 33a by, for example, an appropriate spring means (not shown), whereby the driven roller 33b follows the rotation of the driving roller 33a by a resist motor described later. And rotate.

The sheet sent out from the image forming apparatus A by the discharge roller pair 37 near the second paper discharge port 16 has its tip directed to the nip portion 38 which is the pressure contact portion of the roller surface of the resist roller pair 33 which has stopped rotating. Align the tip position by abutting. The sheet whose tip positions are aligned and the skew is corrected in this way is conveyed toward the folding roller pair 34 by driving the resist roller pair 33 at a predetermined timing.

In another embodiment, the resist roller pair 33 can be replaced by a discharge roller pair 37 that ejects the sheet from the image forming apparatus A to the sheet folding apparatus C. As a result, the number of parts of the sheet folding device C can be reduced, the manufacturing cost can be reduced, and the entire device can be miniaturized in the sheet transport direction. In this case, it is preferable that the discharge roller pair 37 has a function of aligning the tip positions of the sheets carried into the transport 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 arranged so as to sandwich the transport path 32 in the drawing. Both rollers 34a and 34b are pressed against each other by, for example, an appropriate spring means (not shown) in order to nip and fold the tip and crease of the sheet sent from the resist roller pair 33 as described later. At the same time, in such a pressure-welded state, the rotation is synchronously rotated in the sheet transport direction by a common folding roller drive motor described later.

The folding roller pair 34 is arranged so that the nip portion 38 of the resist roller pair 33 is located above the 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 resist roller pair 33 are both substantially horizontal, and the tangent line 38a is oriented up and down by a certain height so as to pass above the tangent line 39a. Has been done.

[Transport route]
As shown in FIG. 2, the transport path 32 includes a sheet carry-in path 41 from the sheet carry-in inlet 32a to the resist roller pair 33 along the sheet transport direction, and a central transport path 42 from the resist roller pair to the folding roller pair 34. And a sheet carry-out path 43 from the folding roller pair to the sheet carry-out port 32b.

The sheet carry-in path 41 has an upper carry-in guide 41a and a lower carry-in guide 41b arranged vertically facing each other along the sheet transport direction so as to guide the tip of the sheet to be carried in to the nip portion 38 of the resist roller pair 33. Have. In the upper carry-in guide 41a, when the tip of the sheet is abutted against the nip portion 38 of the resist roller pair 33 to align the tip positions as described above, the sheet sent from the upstream side to the discharge roller pair 37 is the sheet carry-in path. In order to secure a space that can bend in a loop shape in 41, the space is greatly expanded upward from the vicinity of the resist roller pair 33 toward the inlet side.

As shown in FIG. 2, the central transport path 42 is vertically opposed to each other along the sheet transport direction so as to guide the sheet whose tips are aligned by the resist 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 transported by the vertical transport guides 45 and 46 from both sides in the thickness direction in the central transport path 42 in a state of being restricted from the top and bottom in the present embodiment.

As described above, the tangent line 38a passing through the nip portion 38 of the resist roller pair 33 and the tangent line 39a passing through the nip portion 39 of the folding roller pair 34 are arranged horizontally and at different vertical heights, so that the upper transport guide 45 is arranged. , 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 both tangent lines 38a, 39a from the upstream side to the downstream side. It has an inclined portion 45c inclined downward toward the side.

As shown in FIG. 2, the inclined portion 45c is formed linearly from the upstream end of the second horizontal portion 45b to the diagonally upward right side in the drawing. The inclined portion 45c and the second horizontal portion 45b intersect linearly, and the connecting portion is composed of a relatively large obtuse-angled corner portion, and a convex portion 47 that is convex substantially downward of the central transport path 42 is formed. 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 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 by a curved portion that is convex substantially downward of the central transport path 42. The connecting portion between the inclined portion 45c and the first horizontal portion 45a can be similarly curved. In yet 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 transport guide 45.

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

The lower transport guide 46 has a first lower guide portion 46a extending downstream from the resist roller pair 33 to a predetermined position along the sheet transport direction, and a predetermined position from the folding roller pair 34 to the upstream side along the sheet transport direction. It has a second lower guide portion 46b extending to. The first and second lower guide portions 46a and 46b are separated from each other so as to define a large gap 48 along the sheet transport direction, and are fixed to the housing 31 side. The gap 48 between the first and second lower guide portions 46a and 46b is selectively opened and closed by a veneer 35 that can advance and retreat horizontally toward the nip portion 39 of the folding roller vs. 34, as will be described later.

The first lower guide portion 46a extends horizontally from the resist roller pair 33 to the downstream side, substantially facing the first horizontal portion 45a of the upper transport guide 45, and further downstream from the first horizontal guide portion 51a. It has a first inclined guide portion 51b that is substantially parallel to the inclined portion 45c of the upper transport guide so as to face halfway. The downstream end of the first inclined guide portion 51b defines the hanging start position of the sheet 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 the tangent line 39a passing through the nip portion 39 of the folding roller pair 34.

The second lower guide portion 46b comprises a relatively short horizontal portion extending upstream from the folding roller pair 34 along the sheet transport direction. The second lower guide portion 46b cooperates with the second horizontal portion 45b of the upper transport guide 45 which faces vertically with the central transport path 42 in between, and regulates the sheet in the thickness direction, that is, in the vertical direction from both sides. The tip of the sheet is guided to the nip portion 39 of the folding roller vs. 34.

As shown in FIG. 2, a relatively large loop forming space 50 is provided below the gap 48 of the lower transport guide 46. Further, a loop guide portion 70 is provided below the central transport path 42, and defines the lower limit of the loop forming space 50 along the sheet transport direction. The loop guide portion 70 includes a first loop guide 71a connected to the upstream end of the second lower guide portion 46b in the sheet transport direction, and a second loop guide portion 70 extending further upstream from the upstream end of the first loop guide in the sheet transport direction. It has a loop guide 71b.

The first loop guide 71a is inclined downward from the upstream end of the second lower guide portion 46b in the sheet transport direction to the upstream side so that the separation distance in the height direction from the second horizontal portion 45b of the upper transport guide 45 gradually increases. doing. The second loop guide 71b is provided substantially horizontally from the lower end to the upstream side of the first loop guide 71a. In the present embodiment, as shown in FIG. 2, the lower end of the first loop guide 71a extends to the vicinity of the downstream end of the first lower guide portion 46a in the sheet transport direction, and the upstream end of the second loop guide 71b is a resist roller. It reaches near the lower position of 33. The loop guide portion 70 forms the loop forming space 50 in a space below the central transport path 42 that is relatively shallow in the height direction substantially orthogonal to the sheet transport direction and relatively long along the sheet transport direction.

When the veneer 35 is retracted to the lower side of the first lower guide portion 46a (indicated by a solid line in FIG. 2) and the gap 48 is opened, the sheet in the central transport path 42 is looped from the gap 48. It can be hung down to 50. When the veneer 35 advances to the folding roller pair 34 side (indicated by the imaginary line 35'in FIG. 2) and the gap 48 is closed, the sheet sent out from the resist roller pair 33 hangs down in the loop forming space 50. Instead, it can be transported toward the folding roller pair 34 along the central transport path 42.

When the veneer 35 is in the retracted position on the lower side of the first lower guide portion 46a, the sheet sent out from the resist roller pair 33 to the central transport path 42 crosses the downstream end of the first inclined guide portion 51b, and the sheet tip It hangs down in the loop forming space 50 through the gap 48 opened downward from. On the other hand, when the gap 48 is opened in a state where the tip of the sheet is nipped into the folding roller pair 34 and the folding roller pair has stopped rotating, the sheet in the central transport path 42 has a gap 48 as described later. It curves in a loop shape and hangs down in the loop forming space 50 through the loop.

The sheet that hangs in a loop shape in the loop forming space 50 curves from the folding roller vs. 34 side along the inclination of the first loop guide 71a of the loop guide portion 70 as the amount of the hanging increases, and the second loop. A loop is formed so as to extend along the guide 71b toward the upstream side in the sheet transport direction. That is, the loop has a shape that is relatively thin in the height direction and relatively long in the sheet transport direction in the loop forming space 50 whose lower limit is regulated by the loop guide portion 70, as will be described later. The loop that is long in the sheet transport direction can be smoothly pulled into the rotating folding roller pair 34 along the loop guide portion 70.

In the present embodiment, the first partition member 73 is fixedly provided on the housing 31 side immediately below the resist roller pair 33 and the veneer 35 at the retracted position. The first partition member 73 partially defines the upper portion of the loop forming space 50 and isolates the sheet or loop in the loop forming space 50 from the resist roller pair 33 and the veneer 35. In FIG. 2, the downstream end of the first partition member 73 is provided near the center of the veneer 35 in the retracted position in the sheet transport direction, but it can also be extended to the vicinity of the downstream end of the veneer 35. On the contrary, the first partition member 73 can be shortened so as to isolate only the resist roller pair 33.

Further, the second partition member 74 is similarly fixed to the housing 31 side so as to be continuous upstream from the loop guide portion 70 and the first partition member 73. The second partition member 74 defines the loop forming space 50 on the sheet transporting direction side, and prevents the sheet or loop from protruding from the loop forming space 50 on the upstream side in the sheet transporting direction.

In addition to separating the sheet and the loop from the resist roller pair 33 and the veneer 35 in the loop forming space 50, the first partition member 73 separates the loop of the sheet formed in the loop forming space 50 in the height direction. , It can function to regulate from above along the sheet transport direction. In this case, it can be said that the first partition member 73 constitutes a part of the loop guide portion 70. The first partition member 73 and the loop guide portion 70 can be provided separately on the housing 31 side, or can be provided in an integral structure.

Similar to the first partition member 73, the second partition member 74 can also be provided so as to restrict the loop of the sheet in the loop forming space 50 in the height direction and from above along the sheet transport direction. In that case, the second partition member 74 and the loop guide portion 70 can be separately fixed to the housing 31 side or configured as an integral structure.

In other words, the central transport path 42 folds the sheet from the first path portion that feeds the sheet from the resist roller pair 33 and the second path portion that can selectively open the central transport path 42 to the lower loop forming space 50. It is composed of a third path portion that 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 transport direction by the upper transport guide 45 composed of the first and second upper transport guide members. On the lower surface side of the sheet, 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 composed of a gap 48 that is opened and closed by the movement of the thrust plate 35.

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 transporting direction so as to guide the folded sheet to the sheet unloading outlet 32b. In front of the sheet carry-out port 32b, for example, an additional folding mechanism having a plurality of rolling elements that move on the lower carry-out guide 43b in the sheet width direction orthogonal to the sheet carrying direction to further fold the folded sheet. 36 is provided.

[Veneer]
As shown in FIGS. 2 and 3, the veneer 35 is formed of a flat plate member extending in the sheet width direction of the central transport path 42. The veneer 35 is horizontally arranged at substantially the same height as the nip portion 39 of the folding roller pair 34. Further, the veneer 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 veneer position shown by the imaginary lines 35'and 35 ". ing.

When the veneer 35 is in the retracted position, as shown in the figure, the gap 48 of the lower transport guide 46 is completely opened, and the second path portion of the central transport path 42 is opened to the lower loop forming space 50. To. Therefore, the sheet in the central transport path 42 can hang down from the central transport path 42 into the loop forming space 50 whose lower limit is regulated by the loop guide portion 70, as will be described later.

At the guide position of the imaginary line 35', the veneer 35 completely closes the gap 48 of the lower transport guide 46, and at the same time, forms a part of the lower transport guide 46 so as to face the upper transport guide 45 vertically. As a result, the sheet in the central transport path 42 is guided through the second path portion without hanging down in the loop forming space 50, and is transported from the first path portion to the third path portion.

At the thrust position of the imaginary line 35 ″, the veneer 35 enters between the second horizontal portion 45b of the upper transport guide 45 and the second horizontal guide portion 52a of the second lower guide portion 46b at the third path portion. This veneer position is a position for the veneer 35 to feed the crease of the sheet to the nip portion 39 of the folding roller vs. 34 at the tip thereof.

It is preferable that the thrust plate 35 is arranged at the thrust position so that the tip thereof is close to the nip portion 39 of the folding roller pair 34 in the third path portion of the central transport path 42. Therefore, the veneer 35 is arranged at the retracted position on the tangent line 39a extending upstream from the nip portion 39 or at a position slightly below the tangent line. From this retracted position, the veneer 35 moves horizontally and linearly with its tip toward the nip portion 39 of the folding roller pair 34.

The third path portion of the central transport path 42 has a narrow upper and lower predetermined height between the second horizontal portion 45b of the upper transport guide 45 and the second lower guide portion 46b of the lower transport guide 46 facing the second horizontal portion 45b. It has a straight portion extending horizontally and linearly from the folding roller pair 34 to the upstream side with a gap. The height of the upper and lower gaps is smooth when the veneer 35 is placed on both the upper and lower sides of the veneer 35 and several sheets are overlapped between the second horizontal portion 45b and the second lower guide portion 46b. Set so that it can be passed through. In the present embodiment, the thickness is set to, for example, 2 mm in consideration of the thickness of two sheets that can be used in the image forming apparatus A so that the sheet in the state of being folded in two can be passed through the veneer 35. ..

As described above, the veneer 35 is horizontally arranged in the retracted position within the height range of the narrow vertical gap extending the straight portion of the third path portion to the upstream side. However, the retracted position of the veneer 35 is not limited to this. It is different if the veneer 35 that moves toward the folding roller pair 34 can move the third path portion horizontally along the upper transport guide 45 and bring the tip closer to the nip portion 39 at the thrust position. The position can be set to the retracted position.

3A and 3B show the structure of the veneer 35 in more detail. As shown in the figure, in the present embodiment, four pairs of folding rollers 34, each of which are vertically folded rollers 34a and 34b, are attached to the upper and lower roller shafts 55 and 56. The four pairs are symmetrically arranged on each of the left and right sides with respect to the central position of the roller shafts 55 and 56 along the axial direction. At the tip of the veneer 35, four notches 57 having a shape and a size corresponding to the shape of the pair of folding rollers corresponding to the positions of the pair of folding rollers 34 are formed along the sheet width direction. It is recessed.

The movement of the veneer 35 between the retracted position, the guide position and the veneer position is performed by driving the veneer drive motor MT3 of the drive mechanism of FIG. 6 described later. The drive of the veneer drive motor MT3 is controlled by the control unit 120 shown in FIG. 6 as described later.

[Drive mechanism of sheet folding device]
3A and 3B show drive mechanisms 58 to 60 of the resist roller pair 33, the folding roller pair 34, and the veneer 35 of the sheet folding device C. The resist roller pair 33 is attached so that the drive roller 33a rotates integrally with the roller shaft 61 rotatably installed in the seat width direction. The folding roller pair 34 is attached so that the vertical folding rollers 34a and 34b rotate integrally with the roller shafts 55 and 56 which are similarly rotatably installed in the seat width direction.

The drive mechanism 58 of the resist roller pair 33 includes the resist roller drive motor MT1, the drive pulley P1 attached to the rotating shaft thereof, the driven pulley P2 attached to one end of the roller shaft 61 of the drive roller 33a, and both pulleys P1. , A timing belt TB1 hung between P2 is provided. The driving force of the resist roller drive motor MT1 is transmitted from the rotating 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 the rotating shaft thereof, 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 hung between them. Further, the drive mechanism 59 is a gear Z1 coaxially and integrally rotatably attached to the roller shaft 56, and a gear Z2 coaxially and integrally rotatably attached to the roller shaft 55 of the upper folding roller 34a and meshes with the gear 1. And.

The driving force of the folding roller drive motor MT2 is transmitted from the rotating shaft to the lower folding roller 34b via a transmission mechanism including a driving 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 the gears Z1 and Z2 that mesh with each other. As a result, the upper fold roller 34a and the lower fold roller 34b rotate in synchronization with each other in opposite directions, and the sheet nipped between the two fold rollers can be cooperatively conveyed in the sheet transfer direction.

The drive mechanism 60 of the thrust plate 35 includes a thrust plate drive motor MT3, a drive pulley P5 attached to the rotating shaft, a rotating shaft 62 erected in the seat width direction, and a driven pulley P6 attached to one end thereof. , The timing belt TB3 hung between both pulleys P5 and P6, the first rack and pinion mechanism 63 provided inward from the driven pulley P6 on the one end side of the rotary shaft 62, and the other end of the rotary shaft 62. The second rack and pinion mechanism 64 provided in the above is provided.

The first rack and pinion mechanism 63 is attached to the first pinion 63a coaxially and integrally rotatably attached to the inward side of the driven pulley P6 on the one end side of the rotating shaft 62, and to one end of the veneer 35. Has a first rack 63b that meshes with the first pinion 63a. Similarly, the second rack and pinion mechanism 64 is attached to the other end of the rotary shaft 62 so as to be coaxially and integrally rotatably attached to the second pinion 64a, and is attached to the other end of the veneer 35 to form the second pinion. It has a second rack 64b that meshes with 64a. The first and second racks 63b and 64b are arranged so that the veneer 35 moves in the horizontal direction by the 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 including 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 cooperate with each other to move the veneer 35 in the horizontal direction.

In another embodiment, the image forming system of the present invention may further include a sheet reversing portion that reverses the front and back of the conveyed sheet in the conveying direction and inverts the front and back surfaces. The sheet reversing portion can be added to the sheet folding device C and the image forming device A of FIG. 1 and provided without changing or impairing their functions described above.

[First sheet reversing part]
FIG. 4 illustrates a first sheet reversing portion 141 arranged along the sheet carry-out path 43 on the downstream side of the folding roller pair 34 and the additional folding mechanism 36 of the sheet folding device C. The first sheet reversing section 141 has a reversing path 144 branched from the sheet carry-out path 43. The inversion path 144 has a first branch path 145a and a second branch path 145b, and an inversion path 145c connected between them. The first branch path 145a branches downward from the generally horizontal sheet carry-out path 43 while curving downward, and the second branch path 145b is downstream of the first branch pass 145a and upstream from the sheet carry-out path 43. It branches while curving downward to the side. The reversing path 145c is connected to the first branch path 145a and the second branch path 145b at the upper end thereof, and extends substantially vertically downward from the connection portion with them.

A switching flapper 146 is provided at the branch portion between the sheet carry-out path 43 and the first branch path 145a. A flexible flapper 147 is provided at the connection portion between the first branch path 145a and the second branch path 145b and the reversing path 145c. The reversing path 145c is provided with a pair of reversing rollers 148 slightly below the connection portion with the first and second branch paths, that is, slightly behind the connection portion.

The switching flapper 146 is driven by, for example, an actuator 149 composed of a solenoid, and has a shielding position for blocking the first branch path 145a from the sheet carry-out path 43 and an open position for guiding the sheet carry-out path 43 to the first branch path 145a. It is possible to move between. The actuator 149 is connected to the control unit 120 of the sheet folding device C, which will be described later, and the switching flapper 146 is selectively switched to the shielding position or the open position according to the instruction of the control unit 120.

The flexible flapper 147 can be formed of, for example, a thin plate-like film member having elasticity and durability made of polyethylene terephthalate resin commercially available under the trade name of Mylar (registered trademark). The flexible flapper 147 is fixed to the connection portion between the first branch path 145a and the second branch path 145b and the reversing path 145c, the upper end side thereof is fixed to the housing 31 side of the sheet folding device C2, and the lower end side can be flexed. The second branch path 145b is normally opened to the reversal path 145c, and the first branch path 145a is blocked.

The flexible flapper 147 is pushed by the tip of the sheet conveyed from the first branch path 145a to the reversing path 145c and flexes, and the first branch path 145a is opened to allow the sheet to pass through the reversing path 145c. After passing through the sheet, it has sufficient elasticity to return to the state of blocking the original first branch path 145a. The reversing roller 148 can rotate in both directions, reverses and transports the sheet from the first branch path 145a to the back of the reversing path 145c, and nips the rear end of the sheet, that is, the vicinity of the upstream end in the sheet transport direction. It can be stopped in the held state, further rotated forward, and transported from the reversing path 145c to the sheet carrying path 43 via the second branch path 145b opened by the flexible flapper 147. As a result, the sheet guided from the sheet unloading path 43 to the reversing path 144 is switched back and transported with the front and back in the transport direction reversed and the front and back surfaces reversed, and is returned to the sheet unloading path 43.

The reversing roller 148 and the unloading roller 143 are movably connected to the reversing unloading roller drive motor MT5. The reverse unloading roller drive motor MT5 is similarly connected to the control unit 120, and is controlled by the control unit 120 to rotate forward or reverse. Further, a one-way clutch 150, which is a clutch mechanism that transmits a rotational driving force in only one direction, is interposed between the reverse unloading roller drive motor MT5 and the unloading roller 143. In the present embodiment, the one-way clutch 150 is set so that its rotational driving force is not transmitted to the unloading roller 143 when the reversing unloading roller drive motor MT5 is reversed.

[Second sheet reversing part]
FIG. 5 illustrates a second sheet reversing portion 142 arranged along the paper ejection path 12 on the downstream side of the image forming portion 3 in the device housing 1 of the image forming apparatus A. The second sheet reversing section 142 has a reversing path 154 branched from the paper ejection path 12. The reversal path 154 has a first branch path 155a and a second branch path 155b, and a reversal path 155c connected between them.

The first branch path 155a branches on the downstream side of the fuser 11 while curving downward from a portion of the paper ejection path 12 that is substantially horizontal in the figure, and is connected to the upper end of the reversing path 155c. The upper end of the reversing path 155c is also connected to the second branch path 155b, and extends downward substantially vertically. The second branch path 155b is on the downstream side of the branch portion 156 from the paper ejection path 12 to the first branch path 155a, and branches downward in a straight line from the substantially vertical output path 12 portion in the figure to the upstream side. ing.

A switching flapper (not shown) is provided at the branch portion 156 from the paper ejection path 12 to the first branch path 155a. The switching flapper is driven by an actuator (not shown) such as a solenoid, like the switching flapper 146 of the first sheet reversing unit 141, and has a shielding position for blocking the first branch path 155a from the paper ejection path 12. It is movable to and from the open position that guides the paper ejection path 12 to the first branch path 155a. Further, such an actuator can be connected to the main body control unit of the image forming apparatus A2, and the switching flapper can be selectively switched and arranged between the shielding position and the opening position according to the instruction.

A flexible flapper (not shown) is provided at the connection portion 157 between the first branch path 155a and the second branch path 155b and the reversing path 155c. This flexible flapper is formed of a thin plate-shaped film member having elasticity and durability such as polyethylene terephthalate resin, like the flexible flapper 147 of the first sheet reversing portion 141, and the upper end side thereof is a sheet folding device. It can be fixed to the housing 31 side of C2, the lower end side can be flexed, and usually the second branch path 155b is opened with respect to the reversing path 155c, and the first branch path 155a can be blocked. Therefore, the tip of the sheet guided from the paper ejection path 12 to the first branch path 155a bends by pushing the flexible flapper, opens the first branch path 155a, and passes through the reversal path 155c. After passing through the sheet, the flexible flapper returns to the state of blocking the original first branch path 155a.

The reversing path 155c is provided with a pair of reversing rollers 158 slightly below the connecting portion 157 with the first and second branch paths, that is, slightly behind it. The reversing roller 158 is rotatable in both directions and is operably connected to, for example, a reversing roller drive motor (not shown) capable of forward and reverse rotation. As a result, the reversing roller 158 transports the sheet from the first branch path 155a to the back of the reversing path 155c, and stops in a state of niping and holding the rear end of the sheet, that is, the vicinity of the upstream end in the sheet transport direction. Further, it can be conveyed from the reversing path 155c to the paper ejection path 12 via the second branch path 155b opened by the flexible flapper. As a result, the sheet guided from the paper ejection path 12 to the reverse path 154 is switched back and conveyed by reversing the front and back in the conveying direction and inverting the front and back surfaces, and is returned to the paper ejection path 12. The rotation of the reversing roller 148 is controlled by the main body control unit connected to the reversing roller drive motor.

[Control configuration of sheet folding device]
FIG. 6 conceptually shows the control configuration of the sheet folding device C. The sheet folding device C includes a control unit 120 including a control board including a CPU. The control unit 120 is connected to the main body control unit 121 of the image forming device A via the sheet post-processing device B. The main body 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 device C is transmitted from the main body control unit 121 to the control unit 120 via the sheet post-processing device B. To.

As shown in the figure, the control unit 120 is connected to the first to fifth detection sensors S1 to S5 provided along the transport path 32. The first detection sensor S1 is arranged in front of the resist roller pair 33 of the sheet carry-in path 41, and detects the tip of the sheet carried in from the image forming apparatus A via the sheet carry-in inlet 32a. The second detection sensor S2 is arranged in front of the folding roller vs. 34 of the central transport path 42, and detects the tip of the sheet transported from the resist roller pair 33 to the folding roller pair 34. As described above, the third detection sensor S3 detects the position of the veneer 35 that moves between the retracted position, the guide position, and the veneer position.

As shown in FIG. 4, the fourth detection sensor S4 reverses the connection portion between the first branch path 145a and the second branch path 145b of the reverse path 145c along the reverse path 144 of the first sheet reverse portion 141. It is provided between the roller 148 and the roller 148. The fourth detection sensor S4 detects the rear end of the sheet, that is, the upstream end in the sheet transport direction, which is guided from the sheet carry-out path 43 to the reverse path 144 through the first branch path 145a into the reverse path 145c. The fifth detection sensor S5 is provided along the sheet carry-out path 43 on the immediate upstream side of the carry-out roller 143. The fifth detection sensor S5 detects the tip of the sheet, that is, the downstream end in the sheet transport direction, which is transported by the sheet carry-out path 43 toward the carry-out roller 143. The detection results of the first to fifth detection sensors S1 to S5 are output to the control unit 120 in real time.

Here, the tip of the sheet detected by the fifth detection sensor S5 is in the sheet conveying direction of the sheet when the sheet is conveyed from the folding roller pair 34 when the sheet is conveyed along the sheet carrying path 43 without passing through the inversion path 144. It is the downstream end. When the sheet passes through the reversing path 144 and is returned to the sheet carrying-out path 43, the tip thereof is flipped back in a switchback manner by the first sheet reversing portion 141, so that the sheet is fed from the folding roller pair 34. It is the upstream end in the sheet transport direction. The sheet referred to here includes both a sheet that has not been folded by the folding roller vs. 34 and a folded sheet that has been folded.

The control unit 120 includes a folding processing information acquisition unit 124 in order to acquire and store information transmitted from the main body control unit 121 of the image forming apparatus A. The folding processing information acquisition unit 124 includes a sheet thickness information acquisition unit that acquires and stores information about the sheet to be folded, particularly information about the sheet thickness, and a size information acquisition unit that acquires and stores information about the sheet size. Is provided. Further, the control unit 120 includes a ROM 127 for storing various control control programs executed as described above and as described later, data necessary for the control programs, and a folding loop counter 128 described later. ..

Further, the control unit 120 includes a folding operation setting unit 129 connected to the folding processing information acquisition unit 124. When the folding operation setting unit 129 includes information instructing the execution of the folding process in the information acquired by the folding process information acquisition unit 124 from the main body control unit 121 of the image forming apparatus A, the folding operation setting unit 129 is based on the instruction information. Set the folding operation. According to this setting, the control unit 120 executes the sheet folding processing operation.

When the resist roller drive motor MT1, the folding roller drive motor MT2, and the veneer drive motor MT3 are further provided with the additional folding mechanism 36, the control unit 120 is provided with the additional folding drive motor MT4, and the first sheet reversing unit 141. Is provided, it is connected to the reversing carry-out roller drive motor MT5 and the actuator 149. The drive of each drive motor MT1 to MT5 and the actuator 149 is controlled based on the detection results input from the first to fifth detection sensors S1 to S5 and the various information received from the main body control unit 121 of the image forming apparatus A. , Controls the transfer of the sheet in the transfer path 32 and the folding operation of the sheet folding device C.

The folding processing operation referred to here can include reverse transfer of the sheet by the reverse unloading roller drive motor MT5 and the actuator 149 of the first sheet reversing unit 141, and sheet transfer to the sheet post-processing device B by the unloading roller 143. In that case, the control unit 120 can similarly transmit information such as sheet reversal transfer of the first sheet reversal unit 141 and sheet transfer of the unloading roller 143 to the control unit 121 of the image forming apparatus A in real time.

Further, the control unit 120 transmits information such as sheet transport and folding processing executed in the sheet folding device C to the main body control unit 121 of the image forming device A via the sheet post-processing device B in real time. Can be done. When the information received from the control unit 120 includes undesired information such as sheet transport failure or folding processing failure in the sheet folding device C, or information that should be noted or warned, the main body control unit 121 informs the user. For example, the display unit of the setting panel D can be used for notification.

The sheet folding device C of the present embodiment is suitable for alternately folding the sheet inward and outward along the sheet transport direction and folding it in three in a so-called Z-fold. In the present embodiment, a folding process (Z folding) mode in which the sheet is folded in three (Z folding) and a non-folding mode in which the sheet is not folded are set in advance. Further, the folding processing mode is preset with a first folding mode and a second folding mode.

In the first folding mode, one of the two folds formed on the sheet is arranged closest to the downstream end (tip) of the sheet in the sheet transport direction. FIG. 7A is a plan view of the sheet S before it is folded in the first folding mode, and FIG. 7B shows an example of the folded sheet SH Z-folded by the sheet folding device C from the sheet width direction. ing. In the folded sheet SH of FIG. 7B, the first fold 202 formed first is arranged at a position having a short predetermined length ΔL from the downstream end 201 in the sheet transport direction to the upstream side, and is folded back from there to the downstream side. A second crease 203 is formed at a position of a predetermined length.

As described above, in the folded sheet SH in the first folding mode, a portion Tb (hereinafter, referred to as a tab in the present specification) that protrudes by a length ΔL from the first fold 202 on the sheet tip side to the sheet tip 201 remains. The tab Tb can be reduced by bringing the position on the seat where the nip 39 is nipating, that is, the initial nip position NPi, closer to the seat tip 201 when the folding roller pair 34 is stopped to form the folding loop FL. , Cannot be completely eliminated. Therefore, the appearance of the Z-folded sheet may be impaired.

In addition, in FIGS. 7A and 7B, the sheet S and the folded sheet SH are represented so as to coincide with the tip positions in the sheet transport direction. As can be seen from the figure, according to the present embodiment, the folded sheet SH of FIG. 7B is Z-folded so that the size in the sheet transport direction is halved of the original sheet size.

In the second fold mode, one of the two folds formed on the sheet is aligned with the upstream end (rear end) of the sheet in the sheet transport direction. FIG. 8A shows a plan view of the sheet S before Z-folding in the second folding mode, and FIG. 8B shows an example of the sheet SH after Z-folding viewed from the sheet width direction. In FIG. 8B, the first crease 202 is formed at a position 1/4 of the sheet length L from the sheet tip 201 to the upstream side along the sheet transport direction, and the second fold 203 is the sheet rear end 204 It is formed in agreement with.

In the second fold mode, the initial nip position NPi is set to a position away from the seat tip 201 on the upstream side, and the position of the second crease 203 on the upstream side in the sheet transport direction is aligned with the seat rear end 204. Perform processing operation. As a result, the sheet S of FIG. 8A can be Z-folded to 1/2 of the original sheet size without generating the tab Tb of FIG. 7B.

[Processing operation of sheet folding device]
The folding operation of the sheet folding device C will be described below. 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 folding process is performed, the folding processing mode is performed in the input unit of the setting panel D. Select and enter the first fold mode or the second fold mode from. The input of the folding process mode is stored in the main body control unit 121 of the image forming apparatus A as one of the sheet information of the sheet to be folded.

The entire processing operation in the sheet folding device C will be schematically described with reference to the flowchart of FIG. First, when the first detection sensor S1 detects the tip of the sheet carried into the sheet carry-in path 41 and turns on (Y in step ST01), the control unit 120 of the sheet folding device C uses this as a trigger. The detected sheet information of the sheet is acquired from the main body control unit 121 of the image forming apparatus A via the sheet post-processing apparatus B (step ST02). This sheet information includes information on the characteristics of the sheet itself such as the size, material, thickness (including basis weight) of the sheet, the orientation of the sheet during transportation (vertical direction or horizontal direction), and the folding process to be performed in the future. Information and information on post-processing such as binding processing performed by the sheet post-processing device B after passing through the sheet folding device C are included.

In the present embodiment, the information regarding the basis weight of the sheet to be folded is acquired from the sheet information sent from the main body control unit 121 of the image forming apparatus A. In another embodiment, the sheet folding device C itself can acquire the basis weight of the sheet carried in from the image forming device A. For example, a detection technique is conventionally known in which a sound wave having a predetermined frequency is emitted toward the surface of a sheet and the basis weight is calculated from the intensity of the sound wave passing through the sheet. By providing such a detection mechanism in the sheet folding device C, even a type of sheet that is not planned to be used can be immediately dealt with.

When the sheet information acquired from the main body control unit 121 of the image forming apparatus A includes the selection of the folding process mode or the execution instruction of the folding process (Y in step ST03), the process proceeds to steps ST04 to ST08 to execute the folding process. If the sheet information from the image forming apparatus A does not include an instruction to select the folding process mode or execute the folding process, or includes an instruction not to execute the folding process, the process proceeds to step ST09 to execute the folding process.

In the non-folding process of step ST09, the veneer 35 is arranged at the guide position (35') described in relation to FIG. 2, and the resist roller pair 33, the folding roller pair 34, and the unloading roller pair 143 are rotated in this state. Drive. 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. It should be noted that, optionally, the sheet to be conveyed through the sheet carry-out path 43 can be subjected to the above-mentioned sheet inversion process by the first sheet inversion unit 141.

As a whole, the folding process of steps ST04 to ST08 includes a folding operation setting process (step ST04) in the control unit 120, a resist process by the resist roller pair 33 (step ST05), and a folding loop process by the folding roller pair 34 (step ST06). It is performed in five stages: a crease forming process (step ST07) by the veneer 35 and the folding roller pair 34, and a unloading process (step ST08) in which the folded sheet is carried out to the sheet post-processing device B. Hereinafter, the processing in each step ST04 to ST08 will be specifically described with reference to FIGS. 10 to 20.

13 (a) to 13 (f) show the process of folding the sheet S carried into the sheet folding device C into Z-fold in the first folding mode, and FIGS. 14 (a) to 13 (f) show FIG. The process of folding into Z-fold in the first folding mode is shown in the order of the steps according to the modification. Further, FIGS. 15A to 15D show the process of folding the sheet S into Z folds in the second fold mode, respectively, in the order of the steps.

[Folding operation setting process]
In the folding operation setting process, the control unit 120 is based on the information on the sheet size acquired from the image forming apparatus A in step ST02 of FIG. 9 and the information on the folding processing mode (whether the first folding mode or the second folding mode). Sets the first set transport amount Pn and the loop count value Px. The folding operation setting process is executed at the latest before the sheet is carried from the image forming apparatus A into the sheet folding apparatus C and the resist process is started according to the flowchart shown in FIG.

First, in step ST04-1, it is determined whether or not the information regarding the folding processing mode from the image forming apparatus A is the second folding mode. When the folding processing mode is the second folding mode (Y in step ST04-1), the process proceeds to step ST04-2 to set the first set transport amount Pn. The first set transfer amount Pn is the sheet transfer direction length of the sheet S to be folded at the distance R (measured at the center position of the rollers) in the sheet transfer direction between the resist roller pair 33 and the fold roller pair 34 shown in FIG. The distance Ra = R + L / 4, which is the sum of 1/4 of the L, is calculated as the sheet transfer amount of the resist roller pair 33, and is converted into the corresponding drive pulse value Pa of the resist roller drive motor MT1.

Next, the process proceeds to step ST04-3, and the loop count value Px is set. For the loop count value Px, the distance Rb obtained by adding 3/4 of the sheet transport direction length L of the sheet S to be folded to the above distance R is calculated as the sheet transport amount of the resist roller pair 33, and similarly. It is a value converted into a drive pulse value Pb of the resist roller drive motor MT1 corresponding to this.

After setting the first set transport amount Pn and the loop count value Px in this way, the control unit 120 turns on the actuator 149 of the first sheet reversing unit 141 and drives the switching flapper 146 from the shielding position to the open position. (Step ST04-4). As a result, the folding sheet carried out from the folding roller pair 34 can be guided from the sheet carrying out path 43 to the first branch path 145a of the reversing path 144, and the folding operation setting process in the second folding mode is completed.

In the first step ST04-1, when the folding processing mode is not the second folding mode, that is, the first folding mode (N in step ST04-1), the process proceeds to step ST04-5 to set the first set transport amount Pn. In this case, the first set transport amount Pn is the sheet transport in which the tip of the sheet S that has reached the folding roller pair 34 in the transport path 32 is transported after passing through the nip portion 39 until the folding roller pair 34 stops. The distance in the direction, that is, the distance Rc = R + ΔL obtained by adding the sheet transport direction length ΔL between the sheet tip 201 and the nip position by the folding roller pair 34 in FIG. 6 to the above-mentioned distance R as the sheet transport amount of the resist roller pair 33. It is a value calculated and converted into a drive pulse value Pc of the resist roller drive motor MT1 corresponding to this.

Next, the loop count value Px is set in step ST04-6. The loop count value Px is the length ΔL in the sheet transport direction between the sheet tip 201 and the nip position by the nip portion 39 when the folding roller pair 34 is stopped, and the sheet transport direction length L of the sheet S to be folded. The distance Rd = R + L / 2 + ΔL obtained by adding 1/2 to the above-mentioned distance R is calculated as the sheet transport amount of the resist roller pair 33, and similarly, the drive pulse value Pd of the resist roller drive motor MT1 corresponding to this is calculated. It is a converted value.

After setting the first set transport amount Pn and the loop count value Px in this way, the control unit 120 turns off the actuator 149 of the first sheet reversing unit 141 and drives the switching flapper 146 from the open position to the shielding position. (Step ST04-7). As a result, the folding sheet carried out from the folding roller pair 34 can be guided straight to the carrying-out roller 143 through the sheet carrying-out path 43 without passing through the reversing path 144, and the folding operation in the first folding mode. The setting process ends.

In each step ST04-2, ST04-3, ST04-5, ST04-6 for setting the first set transfer amount Pn and the loop count value Px, the sheet transfer amount of the resist roller pair 33 corresponding to the distances Ra to Rd is determined. It is not necessarily limited to the drive pulse value of the resist roller drive motor MT1. For example, the amount of rotation of the resist roller drive motor MT1 (rotation number, rotation angle, rotation time, etc.) and the amount of rotation of the drive roller 33a of the resist roller vs. 33 (rotation number, rotation angle, rotation time, etc. of the roller shaft 61). It can also be set to the value converted using.

Further, the on / off control of the actuator 149 in steps ST04-4 and ST04-7 is always executed regardless of whether the switching flapper 146 is in the shielding position or the opening position. As a result, the folded sheet carried out from the folding roller pair 34 can be reliably transferred from the carry-out roller 143 to the sheet post-processing device B without being reverse-processed or inverted in a switchback manner.

[Resist processing]
In the resist treatment, the tips of the sheets carried into the sheet folding device C are aligned to correct the sheet skew (skew). The resist process is executed according to, for example, the procedure shown in the flowchart of FIG.

When the first detection sensor S1 detects the tip of the sheet carried into the sheet carry-in path 41 and turns on (Y in step ST10), the control unit 120 is turned on while the resist roller pair 33 has stopped rotating. Measure the elapsed time from a point in time. When this elapsed time elapses for a predetermined time set in advance (Y in step ST11), the resist roller drive motor MT1 is driven (step ST12) to rotate the resist roller pair 33.

During the predetermined time of step ST11, the tip of the sheet abuts on the nip portion 38 of the resist roller pair 33, and the sheet loading path 41 provides a loop-shaped deflection necessary and sufficient for aligning the tip positions. This is the time required to form the sheet. This time can be determined in advance based on, for example, a test result or the like and set in the control unit 120.

When the resist roller pair 33 is rotated, the sheet is transported to the folding roller pair 34 along the central transport path 42. Triggered by the activation of the resist roller drive motor MT1 in step ST12, the folding loop counter 128 of the control unit 120 starts counting (step ST13). In the present embodiment, a pulse motor is adopted as the resist roller drive motor MT1, and the folding loop counter 128 counts the number of drive pulses of the resist roller drive motor MT1.

The veneer 35 is located at the guide position 35'when the sheet S is fed out of the resist roller pair 33. Therefore, as shown in FIG. 13A, the tip of the sheet is guided straight along the central transport path 42 to the upper surface of the veneer 35 and is fed straight toward the nip portion 39 of the folding roller pair 34. The sheet whose tip has passed through the convex portion 47 of the central transport path 42 is connected to the inclined portion 45c of the upper transport guide 45 and the second horizontal portion 45b in the sheet transport direction, that is, in the region 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 according to, for example, the procedure shown in the flowchart of FIG. In step ST13, the control unit 120 drives the resist roller drive motor MT1 to rotate the resist roller pair 33, and at the same time drives the fold roller drive motor MT2 to rotate the fold roller pair 34 (step ST20). As a result, the folding roller pair 34 is in a state where the tip of the sheet to be conveyed can be nipated by the nip portion 39.

Next, as shown in FIG. 13A, when the second detection sensor S2 detects the tip of the sheet to be conveyed and turns on immediately upstream of the folding roller pair 34 (Y in step ST21), The control unit 120 executes the evacuation process (step ST22). By this retracting process, the veneer 35 is moved from the guide position to the retracting position.

The evacuation process is executed according to, for example, the procedure shown in the flowchart of FIG. The control unit 120 drives the veneer drive motor MT3 in the reverse direction (step ST50), and moves the veneer 35 horizontally from the guide position 35'to the upstream side in the seat transport direction toward the retracted position. The veneer 35 of the present embodiment is provided with a detection flag (not shown) at the upstream end in the sheet transport direction.

When the third detection sensor S3 arranged 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 (Y). Step ST52). As a result, the veneer 35 is arranged at the retracted position shown in FIG. 13B, and the gap 48 between the first and second lower guide portions 46a and 46b is completely opened. As a result, in the central transport path 42, as shown in the figure, the second path portion is opened to the lower loop forming space 50. During this time, the tip of the sheet S is caught in the nip portion 39 of the folding roller pair 34 and is niped.

Next, the control unit 120 starts from the time when the second detection sensor S2 detects the tip of the sheet S in step ST21, and starts with the resist roller drive motor MT1 up to the first set transfer amount Pn set in the folding operation setting process. Is driven (Y in step ST23), the folding roller drive motor MT2 is stopped (step ST24). As a result, the folding roller pair 34 stops at a position where the tip of the sheet S advances to the downstream side from the nip portion 39 by a predetermined sheet transport amount. Further, the folding roller drive motor MT2 is stopped until it is redriven in the crease forming process (step ST07) described later.

In the case of the first folding mode, the first set transport amount Pn was set to the distance Rc = R + ΔL in step ST04-5. Therefore, as shown in FIG. 13B, the sheet S is nipped into the nip portion 39 at a position where the tip thereof advances by a length ΔL from the nip portion 39 of the folding roller pair 34 to the downstream side in the sheet transport direction. It is held in the state.

In the first fold mode, the length ΔL is set as small as possible so that the first crease on the sheet tip (downstream end in the sheet transport direction) side is formed closer to the sheet tip and the tab Tb becomes smaller. Is preferable. In this embodiment, the length ΔL is set to, for example, 10 mm.

Even after the folding roller drive motor MT2 is stopped, the resist roller drive motor MT1 is continuously driven, and the resist roller pair 33 rotates and continues to feed the sheet. As a result, as shown in FIG. 13C, the portion of the sheet S on the upstream side of the folding roller pair 34 hangs down from the gap 48 in a loop shape in the loop forming space 50, and the folding loop FL is a sheet. It is formed on the tip side of S in the sheet transport direction.

As shown in the figure, the folding loop FL is curved from the folding roller pair 34 side along the inclination of the first loop guide 71a of the loop guide portion 70, and further toward the upstream side in the sheet transport direction along the second loop guide 71b. Extend. The folded loop FL increases according to the sheet transfer amount by the resist roller pair 33, is relatively thin in the height direction, and extends relatively long in the sheet transfer direction within the loop forming space 50 regulated by the loop guide portion 70. It becomes a shape.

In the case of the modified example of the first folding mode shown in FIG. 14, the first set transport amount Pn is set to the distance Rc'= R + ΔL', (ΔL'>> ΔL) in step ST04-5. Therefore, as shown in FIG. 14A, in the control unit 120, the amount of advancement of the sheet tip from the nip portion 39 to the downstream side by the tip of the sheet S nipped by the folding roller pair 34 is the first in FIG. The folding roller driving motor MT2 is continuously driven together with the resist roller driving motor MT1 until the length ΔL'is sufficiently larger than the length ΔL in the folding mode.

The control unit 120 drives and stops the resist roller drive motor MT1 up to the first set transfer amount Pn, and at the same time temporarily stops the folding roller drive motor MT2. Immediately after that, as shown in FIG. 14B, the folding roller drive motor MT2 was reversed, and the rear end side of the sheet S was nipped and held by the resist roller pair 33, and the sheet S was held by the folding roller pair 34. The tip side is sent back to the upstream side.

As a result, the portion of the sheet S on the upstream side of the folding roller pair 34 curves in a loop shape from the gap 48 into the loop forming space 50 and hangs down to form a folding loop FL. At this time, the sheet S is smoothly back-fed from the folding roller pair 34 toward the upstream side along the inclination of the first loop guide 71a of the loop guide portion 70.

The folding loop FL becomes larger according to the sheet transport amount due to the reverse feed, and smoothly extends from the first loop guide 71a to the upstream side in the sheet transport direction along the second loop guide 71b. As shown in FIG. 14 (c), the control unit 120 reverses the folding roller drive motor MT2 so that the amount of advancement of the seat tip from the nip portion 39 of the folding roller pair 34 to the downstream side has a length ΔL. Stop it.

As a result, the folding loop FL is relatively thin in the height direction within the loop forming space 50 regulated by the loop guide portion 70, as in the case of the first folding mode shown in FIG. 13C, and the sheet is conveyed. It is formed in a shape that extends relatively long in the direction. As can be seen from the above description, the sheet transport amount due to the reverse feed of the folding roller pair 34 is a distance that is the first set transport amount Pn of the first fold mode from the distance Rc'= R + ΔL'of the first set transport amount Pn. The value obtained by subtracting Rc = R + ΔL can be set to ΔL'−ΔL.

In the case of the second folding mode, the first set transport amount Pn was set to the distance Ra = R + L / 4 in step ST04-2. In one embodiment, when the resist roller drive motor MT1 is driven to the first set transfer amount Pn, the folding roller drive motor MT2 is stopped (step ST24) so that the sheet S has a tip of the folding roller vs. 34. It is held at a position where the length L / 4 advances downstream from the nip portion 39 in the sheet transport direction.

After the folding roller drive motor MT2 is stopped, the resist roller drive motor MT1 is continuously driven, so that the sheet S sent out from the resist roller pair 33 is looped from the gap 48 in the portion upstream of the folding roller pair 34. It curves in a loop shape and hangs down in the formation space 50 to form a folded loop FL. In the second folding mode, since the tip of the sheet S advances to the downstream side from the nip portion 39 of the folding roller vs. 34 by 1/4 of the sheet length L, the folding loop FL is rearward in the sheet conveying direction of the sheet S. Formed on the end side.

The folding loop FL is curved from the folding roller vs. 34 side along the inclination of the first loop guide 71a of the loop guide portion 70, and further along the second loop guide 71b, as in the case of the first folding mode described above. It extends toward the upstream side in the sheet transport direction. The folded loop FL increases according to the sheet transfer amount by the resist roller pair 33, is relatively thin in the height direction, and extends relatively long in the sheet transfer direction within the loop forming space 50 regulated by the loop guide portion 70. It becomes a shape.

In another embodiment of the second folding mode, the control unit 120 keeps the folding roller drive motor MT2 on the resist roller drive motor MT1 even after the folding roller pair 34 has niped the tip of the sheet S conveyed by the resist roller pair 33. Drive with. When the first detection sensor S1 detects the rear end of the sheet S, the resist roller drive motor MT1 and the folding roller drive motor MT2 are stopped immediately before the rear end of the sheet S reaches the nip portion 38 of the resist roller pair 33. As a result, as shown in FIG. 15A, the folding roller pair 34 nips and holds the intermediate portion of the sheet S, and the resist roller pair 33 nips and holds the rear end of the sheet S. Stop.

Next, the control unit 120 immediately reverses the folding roller drive motor MT2 while stopping the resist roller drive motor MT1. As a result, the folding roller pair 34 reversely feeds the sheet S to the upstream side in the sheet transport direction, as shown in FIG. 15 (b). As a result, in the sheet S back-fed from the folding roller pair 34, the portion upstream of the folding roller pair 34 is curved in a loop shape from the gap 48 into the loop forming space 50 and hangs down to form a folding loop FL. ..

At this time, the sheet S is smoothly back-fed from the folding roller pair 34 toward the upstream side along the inclination of the first loop guide 71a of the loop guide portion 70. The folding loop FL becomes larger according to the sheet transport amount due to the reverse feed, and smoothly extends from the first loop guide 71a to the upstream side in the sheet transport direction along the second loop guide 71b.

As shown in FIG. 15C, the control unit 120 reverses the folding roller drive motor so that the amount of advance of the seat tip from the nip portion 39 of the folding roller pair 34 to the downstream side is L / 4 in length. Stop MT2. The control unit 120 calculates the sheet transfer amount due to the reverse feed of the folding roller pair 34 from, for example, the sheet transfer amount to the downstream side of the folding roller pair 34 after the second detection sensor S2 detects the tip of the sheet S. can do.

As a result, the sheet S is held at a position where the tip thereof advances by a length L / 4 from the nip portion 39 of the folding roller pair 34 to the downstream side in the sheet transport direction. The folded loop FL is formed on the rear end side of the sheet S in the sheet transport direction, and is relatively thin in the height direction within the loop forming space 50 regulated by the loop guide portion 70, as in each of the above-described embodiments, and is a sheet. It has a shape that extends relatively long in the transport direction.

As described above, the first set transfer amount Pn was set by converting the sheet transfer distance into the drive pulse value Pa of the resist roller drive motor MT1 corresponding to the sheet transfer amount of the resist roller vs. 33. In another embodiment, as the first set transfer amount, the rotation amount of the resist roller drive motor MT1 (rotation number of rotation shaft, rotation angle, rotation time, etc.) and the sheet delivery amount by the resist roller pair 33, that is, the drive roller 33a. The amount of rotation (number of rotations of the roller shaft 61, rotation angle, rotation time, etc.) can be used.

After the folding roller drive motor MT2 is stopped in step ST24, when the folding loop counter 128 that started counting in step 13 counts up to the predetermined count value (Y in step ST25), the control unit 120 moves to the next fold. The forming process (step ST06) is executed. The folding loop counter 128 can also be operated to count down by subtracting from the predetermined count value to "0".

[Fold formation process]
In the crease forming process, a crease is formed by a folding roller pair 34 on the sheet in which the loop is formed by the folding loop process. The folding position of the sheet can be set in advance according to the size of the sheet and the orientation of the sheet during transportation (vertical direction, horizontal direction), for example, the distance from the tip of the sheet in the sheet conveying direction. Therefore, in the present embodiment, the loop count value Px set according to the size and the folding processing mode is used for the sheet carried into the sheet folding device C in the folding operation setting processing.

The crease forming process is executed according to, for example, the flowchart shown in FIG. When the folding loop counter counts up to the loop count value Px set in the folding operation setting process, the control unit 120 starts the veneer 35 thrusting process (step ST07-1).

At this time, the folding loop FL is formed in a size suitable for forming a crease on the sheet at a predetermined folding position. Further, the folded loop FL is elongated from the gap 48 to the lower side of the central transport path 42 toward the upstream side in the sheet transport direction in the loop forming space 50 by the loop guide portion 70 defining the bottom side of the loop forming space 50, that is, the lower limit. Is regulated.

More specifically, as illustrated in FIGS. 13 (c), 14 (c) and 15 (c), the tip end side of the sheet S is moved from the folding roller pair 34 to the first loop guide 71a of the loop guide portion 70. It curves relatively gently downward on the upstream side along the line, and extends substantially linearly on the upstream side along the second loop guide 71b to form the lower portion of the folding loop FL. Further, the sheet S is curved upward in a U-shape convex to the upstream side and folded back to the downstream side at the back of the loop forming space 50 on the upstream side, and the veneer 35 and the resist roller pair 33 at the retracted position. The lower part of the fold loop FL is formed by extending the lower part in a substantially straight line to the downstream side and curving upward in the vicinity of the downstream end of the first lower guide portion 46a in a convex U shape toward the downstream side to form the upper part of the folding loop FL. It is connected to the rear end side of the seat S on the first lower guide portion 46a.

The thrusting process is performed, for example, according to the procedure shown in the flowchart of FIG. The control unit 120 drives the veneer drive motor MT3 in the forward direction (step ST53), and moves the veneer 35 horizontally to the folding roller vs. 34 side. The tip of the veneer 35 that has begun to move downstream from the retracted position abuts on the folding loop FL that hangs down from the downstream end of the first lower guide portion 46a of the lower transport guide 46, and the roller pair is folded horizontally while being pushed as it is. It moves linearly toward the nip portion 39 of 34.

The tip of the veneer 35 is formed in the folding loop FL at a predetermined position of the sheet S corresponding to the length of the tip of the sheet S extending downstream from the nip 39 of the folding roller pair 34 which is stopped at this time. bump into. As described above, the portion of the folding loop FL to which the veneer 35 is abutted is curved in a U-shape that is convex upward and upstream near the downstream end of the first lower guide portion 46a. The tip of the sheet S can be more accurately abutted by the predetermined position of the sheet S, and the deviation from the abutting position can be eliminated or made smaller.

In the case of the first folding mode and the modified example thereof, since the tip of the sheet S protrudes downstream from the nip portion 39 by a length ΔL at the predetermined position of the sheet S (FIGS. 13 (c) and 14 (c)). )), The position is a length L / 2 + ΔL from the tip of the sheet S in the sheet transport direction. In the case of the second folding mode, since the tip of the sheet S protrudes downstream from the nip portion 39 by a length L / 4 at the predetermined position of the sheet S, the length 3L / from the tip of the sheet S in the sheet transport direction. It is the position of 4.

In the first and second folding modes, the resist roller drive motor MT1 is continuously driven from before the start of movement of the veneer 35, and the sheet S is sent out from the resist roller pair 33 to the central transport path 42. In the modified example of the first folding mode of FIG. 14, the resist roller drive motor MT1 is re-driven at the same time as the movement of the veneer 35 is started, and the transfer of the sheet S is restarted from the resist roller pair 33.

In the case of the first folding mode, its modification, and the second folding mode, the control unit 120 controls the resist roller drive motor MT1 to control the sheet transfer speed of the resist roller pair 33, and at the same time, controls the veneer drive motor MT3. Control to control the moving speed of the veneer 35. In the present embodiment, the moving speed Vb of the veneer 35 is substantially equal to the sheet carrying speed Vs delivered by the resist roller pair 33, except immediately after the start of movement from the retracted position and immediately before the stop at the thrust position. It is controlled by speed (Vb = Vs).

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

For example, if the moving speed of the veneer 35 is faster than the transfer speed of the sheet by the resist roller pair 33, the sheet is pushed by the veneer 35 and moves through the central transport path 42, while the tip of the veneer 35 and the resist roller pair. There is a risk that the veneer 35 will be stretched from the predetermined position of the veneer 35 to the upstream side, or the veneer 38 of the resist roller pair 33 will slip. On the contrary, when the moving speed of the veneer 35 is slower than the transfer speed of the sheet by the resist roller pair 33, the sheet loosens between the tip of the veneer 35 and the resist roller pair 33, and therefore the second upper transfer guide 45. There is a risk of bending within the gap between the horizontal portion 45b and the veneer 35, or the abutting position of the veneer 35 shifting downstream from the predetermined position of the sheet. According to this embodiment, such a problem is solved.

It is preferable to preset the transition time hb from the start of driving of the veneer drive motor MT3 to the arrival of the seat transfer speed Vs in the moving speed of the veneer 35. In consideration of this transition time hb, in a certain embodiment, the tip of the thrust plate 35 at the retracted position is moved down on the tangent line 39a of the nip portion 39 to which the thrust plate moves in the sheet transport direction. It is arranged at a certain distance I on the upstream side from the downstream end of the first lower guide portion 46a.

This distance I is set longer than the moving distance from when the veneer 35 starts moving toward the folding roller pair 34 until the moving speed becomes Vb = Vs. As a result, the tip of the veneer 15 is abutted at a predetermined position of the folding loop FL at the same movement speed Vb as the sheet transport speed Vs, and the abutment position is maintained until just before the veneer stops at the abutment position. Moves without deviating from the predetermined position of the folding loop FL.

When the veneer 35 moves downstream on the central transport path 42, the upper and lower seat portions of the sheet S with the veneer 35 sandwiched are regulated from both the upper and lower sides by the upper transport guide 45 and the lower transport guide 46, respectively. To. The sheet S is forcibly bent in the direction of overlapping vertically while passing through the narrow gap between the upper transport guide 45 and the lower transport guide 46, and as a result, as shown in FIGS. 13 (d) and 14 (d). , Temporarily folded into a bent form at the predetermined position.

As described above, the portion of the sheet S pushed by the veneer 35 is a portion curved in a U-shape that is convex on the downstream side of the folding loop FL, and its curvature is relatively small, so that the central transport path 42 It is possible to smoothly guide from the section of the gap 48 opened downward to the narrow gap between the upper transport guide 45 and the lower transport guide 46. Further, while passing between the upper transport guide 45 and the lower transport guide 46, the contact resistance that may occur between them and the sheet S is a veneer 35 that hangs down substantially vertically from the first lower guide portion 46a. Since it is reduced as compared with the case of pushing with, it is smoothly conveyed and temporarily folded.

In the modified example of the second folding mode of FIG. 15, the resist roller drive motor MT1 is stopped with the resist roller pair 33 niping the rear end of the sheet S at the start of movement of the veneer 35 in step 35. .. Therefore, the position of the sheet S at which the tip of the moving veneer 35 abuts against the folding loop FL is further upstream than the position of the length 3L / 4 in the sheet transport direction from the tip of the sheet S in the second folding mode.

The resist roller drive motor MT1 and the resist roller pair 33 are stopped as described above while the veneer 35 further moves toward the nip portion 39 of the folding roller pair 34. Therefore, the tip of the veneer 35 moves horizontally and linearly from the position where it abuts on the sheet S to the veneer position while sliding on the lower surface thereof, as in the other embodiment described above. At this time, the sheet S is temporarily folded in a narrow gap between the upper transport guide 45 and the lower transport guide 46. The position of the sheet S abutted against the tip of the veneer 35 that has reached the veneer position is the same as the predetermined position in the second folding mode, and the length is 3 L / 4 in the sheet transport direction from the tip of the sheet S. It becomes the position.

Next, in step ST54, when the drive amount of the veneer drive motor MT3 reaches a preset second set drive amount, the control unit 120 stops the veneer drive motor MT3 (step ST55). The second set drive amount is the drive amount of the veneer drive motor MT3 required to move the veneer 35 from the retracted position to the veneer position 35 "(FIG. 2). The veneer drive motor MT3 is a resist. In the case of a pulse motor as in the roller drive motor MT1, the second set drive amount can be set by the number of drive pulses of the veneer drive motor MT3, and the second set drive amount is a thrust. It is also possible to use a rotation amount based on the rotation number, rotation angle, rotation time, etc. of the rotation shaft of the plate drive motor MT3.

When the veneer drive motor MT3 is stopped, the veneer 35 is stopped at the veneer position 35 ″. As a result, the seat S has the desired first folding position FP1 in FIGS. 13 (d), 14 (d) and FIG. As shown in FIG. 15C, the sheet S is carried to a position facing the nip portion 39 of the folding roller pair 34 in the bent form by the temporary folding described above. The folding position of the sheet S bent by the temporary folding will be described later. As described above, it is pulled into the folding roller pair 34 and is pressure-folded to form the first fold 202 of the folding sheet SH.

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

In the case of the first folding mode, its modification, and the second folding mode, when the veneer drive motor MT3 is stopped by the thrusting process in step ST07-1 (step ST55), the resist roller drive motor MT1 is driven to drive the resist roller. The pair 33 is sending out the sheet S. After the veneer drive motor MT3 is stopped in step ST55, the control unit 120 drives the resist roller drive motor MT1 to a preset third set drive amount (Y in step ST07-2), and the folding roller The drive motor MT2 is driven (step ST07-3). The third set drive amount is the registration roller pair 33 until the first folding position FP1 of the sheet S is caught in the nip portion 39 of the folding roller pair 34 by the feeding of the sheet S by the registration roller pair 33. Is set as the drive amount of the resist roller drive motor MT1 that rotates.

In the modified example of the second folding mode, when the veneer drive motor MT3 is stopped by the thrusting process in step ST07-1 (step ST55), the resist roller drive motor MT1 and the resist roller pair 33 are shown in FIG. 15 (c). It is stopped as shown in. After the veneer drive motor MT3 is stopped in step ST55, the control unit 120 drives the folding roller drive motor MT2 in step ST07-3 and at the same time drives the resist roller drive motor MT1 to fold the first folding position FP1. The sheet S is sent out so as to reach a position where it is caught in the nip portion 39 of the roller pair 34.

In the first folding mode, a modified example thereof, and the second folding mode, when the resist roller drive motor MT1 is driven to the third set drive amount, in the modified example of the second folding mode, the veneer drive motor MT3 In step ST07-3, the folding roller pair 34 is rotated by the drive of the folding roller drive motor MT2, and the first folding position FP1 of the sheet S is caught in the nip portion 39 of the folding roller pair 34 to pressurize. Be folded. As a result, the first fold F1 (202) is formed on the sheet S at a desired fold position, and is conveyed to the downstream side as shown in FIGS. 13 (e), 14 (e) and 15 (d).

The first folding position FP1 of the sheet S is conveyed in the sheet transporting direction in a bent form by the above-mentioned temporary folding, and is directly involved in the nip portion 39 of the folding roller pair 34. Therefore, the position of the first folding position F1 is set. It is stable with high accuracy without causing the conventional variation. Moreover, the first folding position FP1 is smooth because the contact resistance that may occur between the sheet S when it passes between the upper transport guide 45 and the lower transport guide 46 is reduced as described above. It can be involved in the nip portion 39. Further, the folded sheet is prevented from opening the folded portion of the sheet at the first crease, so that the appearance is improved.

Further, according to the present embodiment, the deviation of the crease forming position expected due to the difference in the sheet characteristics can be taken into consideration, the amount of the deviation can be prepared in advance, and the timing of starting the movement of the veneer 35 can be changed. .. For example, in the case of thin paper with respect to plain paper or thick paper, the misalignment of the folds formed on the folded sheet can be eliminated or reduced by delaying the timing of starting the movement of the veneer 35.

When the folding roller drive motor MT2 is driven in step ST07-3, the control unit 120 executes a retracting process for returning the veneer 35 from the thrusting position 35 "to the retracted position (step ST07-4). , The same as described with reference to FIG. 16 in step ST22 of the folding loop process.

That is, the control unit 120 reversely drives the veneer drive motor MT3 in the states of FIGS. 13 (d), 14 (d) and 15 (c), and pushes the veneer 35 from the veneer position 35 "in the sheet transport direction. 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 moved to the upstream side horizontally toward the retracted position. Stop. As a result, the veneer 35 is arranged in the retracted position as shown in FIGS. 13 (e), 14 (e) and 15 (d).

As a result, the gap 48 of the central transport path 42 is completely opened, and the lower part thereof is opened to the loop forming space 50. Therefore, the folding loop FL can be smoothly wound around the nip portion 39 of the folding roller pair 34 from the start of driving the folding roller drive motor MT2 without being hindered by the veneer 35.

The folding roller pair 34 is continuously rotationally driven even after the veneer 35 is retracted. Therefore, as illustrated in FIGS. 13 (e) and 14 (e) for the first folding mode and its modified examples, the sheet is similarly formed at its tip and formed in the second folded mode and its modified examples. Immediately after the first crease F1 is folded, the first fold F1 is first folded in three (Z fold) and then niped into the folding roller pair 34, and the sheet carry-out path 43 is conveyed downstream. As the sheet S is conveyed in this way, the folding loop FL in the loop forming space 50 gradually becomes smaller, and as illustrated in FIGS. 13 (f) and 14 (f), the central transport path 42 In the third path portion, the upper transport guide 45 and the second lower guide portion 46b of the lower transport guide 46 are squeezed from above and below to form a thin loop shape extending in the sheet transport direction.

After that, in the folding loop FL, the rear end, that is, the second folding position FP2 is forcibly bent in the direction of overlapping vertically in the narrow gap between the upper transport guide 45 and the lower transport guide 46, and the first folding position FP1 It is temporarily folded into a bent form in the same manner as above. The second folding position FP2 is conveyed in such a bent form without slipping or misalignment in the sheet conveying direction with the upstream portion of the sheet S stacked on the second folding position FP2. It is pressurized and bent at the nip portion 39 of 34.

As a result, a second crease is formed on the sheet at a desired position. In the case of the first folding mode and the modified example thereof, the second fold 203 is formed at a position of length L / 2 + ΔL from the tip of the sheet S in the sheet transport direction as shown in FIG. 7 (b). In the case of the second fold mode and the modified example thereof, the second fold 203 is formed at a position consistent with the rear end 204 of the sheet S in the sheet transport direction as shown in FIG. 8 (b). The second fold 203 is also stably formed at a desired position of the sheet S with high accuracy without causing the conventional variation on the upstream side in the sheet transport direction due to the pressure bending after the temporary folding described above. To. As a result, a Z-fold sheet SH in which the first fold 202 of the outer fold and the second fold 203 of the inner fold are formed in order in the sheet transport direction is generated.

Next, when the first detection sensor S1 detects the rear end of the sheet conveyed by the resist roller pair 33 and the folding roller pair 34 in the sheet carry-in path 41 and turns off, the control unit 120 presses the veneer 35. The guide process for moving from the retracted position to the guide position 35'is executed. At this time, the folding loop FL is set so as to have already passed through the folding roller pair 34. Therefore, even if the veneer 35 is moved to the guide position 35', there is no problem in transporting the sheet in the central transport path 42 and in the crease forming process by the folding roller pair 34.

The guide process is executed according to, for example, the procedure shown in the flowchart of FIG. The veneer drive motor MT3 is driven in the forward direction (step ST56), and the veneer 35 is horizontally moved toward the folding roller vs. 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 veneer drive motor MT3 required to move the veneer 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 by the central transport path 42 to the upper surface of the veneer 35 and the folding roller. It is transported straight toward the veneer 34. As the drive amount of the thrust plate drive motor MT3, the rotation amount of the motor (rotation speed of the rotation shaft, rotation angle, rotation time, etc.) can be used.

Next, when the second detection sensor S2 detects the rear end (upstream end) of the sheet passing through the central transport path 42 and turns off, the control unit 120 drives the folding roller drive motor MT2 from that time. When the predetermined stop drive amount set in advance is reached, the resist roller drive motor MT1 and the folding roller drive motor MT2 are stopped. Here, the predetermined stop drive amount is a drive amount of the folding roller drive motor MT2 sufficient for the rear end of the seat to pass through the folding roller pair 34.

When the sheet folding device C of the present embodiment Z-folds the sheet in the second folding mode, it is necessary to consider the circumstances described below. In the case of single-sided printing, the image forming apparatus A is usually carried out to the sheet folding apparatus C with the image forming surface facing downward and the upper end of the vertically placed original sheet facing downstream in the sheet conveying direction. To. As a result, in the folded sheet SH of FIG. 8B in the second folding mode, the lower surface becomes the image forming surface, and the sheet rear end side (upstream end side in the sheet conveying direction) of the image forming surface corresponding to the lower end of the original sheet. Is folded back. Such a folded sheet is inconvenient in actual use and may cause inconvenience.

Further, when the folded sheet whose rear end side (upstream end side in the sheet transport direction) is folded by the second folding mode is directly conveyed by the sheet post-processing device B and discharged to the output tray 106, the output tray is discharged. Above, the rear end side of the sheet becomes bulkier than usual. As a result, the number of sheets that can be loaded is smaller than the normal number of sheets that can be loaded, and the output port to the output tray is blocked, so that no more can be accommodated, and the actual number of sheets that can be loaded may be significantly reduced. Moreover, in the folded sheet, the rear end side portion of the folded sheet bulges upward on the paper output tray, and there is a risk that the alignment of the sheets to be laminated later on the folded sheet may be deteriorated.

Further, in the sheet post-processing device B of the present embodiment, as described above, the upstream end, that is, the rear end of the sheet to be carried in in the sheet transport direction is aligned, and the sheet rear end side is needle-bound by the table unit ST1. Therefore, if the folded sheet in which the rear end side of the sheet (upstream end side in the sheet transport direction) is Z-folded in the second folding mode is accumulated in the binding processing tray 104 as it is, there is an inconvenience that the binding process cannot be performed.

In another embodiment, when the sheet post-processing device B is of a type in which the tip side of the sheet to be carried in is aligned and bound, the folded sheet Z-folded in the second folding mode is carried in as it is and bound. However, if the folded sheet Z-folded in the first folding mode is carried in as it is, the binding process cannot be performed. In other words, the folding processing operation of the sheet folding device C may be limited to the first folding mode or the second folding mode depending on the post-processing conditions executed by the sheet post-processing device B on the downstream side.

In consideration of such circumstances, in the image forming system of the present embodiment, as described above, the first and second sheet reversing portions 141, which reverse the front and back of the conveyed sheet in the conveying direction and invert the front and back surfaces, It also has 142. The folded sheet Z-folded in the crease forming process (step ST07) is subjected to a sheet reversing process by the first sheet reversing unit 141 as necessary in the next unloading process (step ST08), and the sheet post-processing device B Carry out to.

[Delivery process]
The carry-out process is executed according to, for example, the flowchart shown in FIG. The control unit 120 performs a substantially different carry-out processing operation depending on whether the folding process of the folding sheet conveyed from the folding roller pair 34 is the first folding mode or the second folding mode. Therefore, it is first determined whether or not the folding processing mode of the folding sheet is the first folding mode (step ST08-1). This determination is made based on the information acquired by the control unit 120 from the main body control unit 121 of the image forming apparatus A.

When the folding processing mode of the folding sheet is the first folding mode (Y in step ST08-1), the control unit 120 drives the folding roller drive motor MT2 in the crease forming processing step ST07-3, and at the same time, reverses the unloading roller. The drive motor MT5 is driven in the forward direction (step ST08-2). At this time, since the actuator 149 has already been turned off in step ST04-7 of the folding operation setting process, the switching flapper 146 of the sheet carry-out path 43 is in the shielding position.

Therefore, the folding sheet conveyed from the folding roller pair 34 is guided straight to the carrying-out roller 143 through the sheet carrying-out path 43 without passing through the reversing path 144. In this way, the folded sheet in the first folding mode is carried out from the sheet discharge port 32b to the sheet aftertreatment device B by the carry-out roller 143 while being folded by the folding roller pair 34.

21 (a) shows the sheet S1 which is image-formed by the image forming apparatus A and carried into the sheet folding apparatus C in the first folding mode, and FIG. 21 (b) shows the sheet after the sheet S1 is folded. It is a drawing which looked at the folding sheet SH1 carried out to the post-processing apparatus B from above in the sheet transport direction, respectively. As described above, the sheet S1 is formed so that the image Im faces downward and the upper end of the vertical document sheet in the image forming apparatus A, that is, the left end of the horizontal document sheet faces the downstream side in the sheet transport direction. The folded sheet SH1 is carried out so that the upper end side of the vertically placed original sheet, that is, the left end side of the horizontally placed original sheet is Z-folded with the image Im facing downward, and the folded sheet SH1 faces the downstream side in the sheet transport direction.

After that, the control unit 120 proceeds to steps ST08-7 to ST08-10, and when the carry-out process is completed, the Z-fold process in the first folding mode is completed. Each operation of steps ST08-7 to ST08-10 will be described later.

When the folding processing mode of the folding sheet is the second folding mode (N in step ST08-1), the control unit 120 drives the folding roller drive motor MT2 in the crease forming processing step ST07-3, and at the same time, reverses the unloading roller. The drive motor MT5 is reversely driven (step ST08-3). At this time, since the actuator 149 has already been turned on in step ST04-4 of the folding operation setting process, the switching flapper 146 of the seat carry-out path 43 is in the open position. The reversal of the reversing unloading roller drive motor MT5 is not transmitted to the unloading roller 143 by the one-way clutch 150, but is transmitted only to the reversing roller 148.

Therefore, as shown in FIG. 22A, the folding sheet SH conveyed from the folding roller pair 34 is guided from the sheet carry-out path 43 to the first branch path 145a of the reversing path 114 by the switching flapper 146. Further, the folding sheet SH pushes open the flexible flapper 147 at its tip, and is conveyed to the back of the reversing path 145c by the reversing roller 148. When the fourth detection sensor S4 detects the rear end (upstream end in the sheet transport direction) of the folded sheet SH guided to the reversing path 145c (Y in step ST08-4), the control unit 120 drives the reversing carry-out roller drive motor. MT5 is temporarily stopped (step ST08-5). As a result, as shown in FIG. 22B, the folded sheet SH is held in a state of being nipped by the reversing roller 148 near the rear end.

Next, the control unit 120 immediately drives the reverse unloading roller drive motor MT5 in the forward rotation (step ST08-6). At this time, the flexible flapper 147 returns to the original state of blocking the first branch path 145a after passing through the folding sheet SH, and opens the second branch path 145b. The forward rotation of the reverse unloading roller drive motor MT5 is transmitted not only to the inverting roller 148 but also to the unloading roller 143 by the one-way clutch 150. Therefore, as shown in FIG. 22C, the folded sheet SH is switchback-conveyed from the reversing path 145c through the second branch path 145b by the reversing roller 148, returned to the sheet unloading path 43, and carried out by the unloading roller 143. Is carried out to the sheet post-processing device B.

FIG. 23 (a) shows the folding sheet SH2 when the sheet S1 of FIG. 21 (a) carried in from the image forming apparatus A is folded in the second folding mode and conveyed from the folding roller pair 34. (B) is a drawing of the folded sheet SH2 when the folded sheet SH2 is sent out from the folding roller pair 34, reverse-processed by the first reversing portion 141, and returned to the sheet carrying-out path 43, respectively, as viewed from above in the sheet conveying direction. By passing through the first reversing portion 141 in this way, in the folding sheet SH, the front end and the rear end in the sheet transport direction when sent out from the folding roller pair 34 are opposite to each other, and the front surface and the back surface are in opposite directions. Inverted.

Next, when the fifth detection sensor S5 detects the rear end of the folded sheet SH carried out by the carry-out roller 143 in the sheet carry-out path 43 (Y in step ST08-7), the control unit 120 starts from that point. After driving the reverse unloading roller drive motor MT5 by a predetermined amount (Y in step ST08-8), the guide process is executed (step ST08-9). Here, the predetermined amount is the drive amount of the reversing carry-out roller drive motor MT5 required for the rear end of the folding sheet SH to completely pass through the carry-out roller 143.

The guide process is performed in the same manner as described above in relation to FIG. That is, the veneer drive motor MT3 is driven in the normal direction to move the veneer 35 horizontally from the retracted position to the guide position 35'toward the folding roller vs. 34 side. As a result, the gap 48 of the central transport path 42 is closed by the veneer 35, so that the next sheet can be transported by the resist roller pair 33 through the central transport path 42 toward the folding roller pair 34.

After that, the control unit 120 stops the resist roller drive motor MT1, the folding roller drive motor MT2, and the reverse unloading roller drive motor MT5 (step ST08-10). As a result, the resist roller pair 33, the folding roller pair 34, and the reversing roller 148 stop rotating, and the Z-folding process of the sheet in the second folding mode is completed.

In another embodiment, the sheet image-formed by the image forming apparatus A is inverted by the second inversion unit 142 in a switchback manner, and then carried into the sheet folding processing apparatus C. The inversion process by the second inversion unit 142 is executed, for example, as follows.

First, the main body control unit 121 drives the switching flapper provided at the branch portion 156 of the paper ejection path 12 from the shielding position to the open position, and at the same time reversely drives the reversing roller drive motor of the reversing roller 158. As a result, the sheet image-formed by the image forming unit 3 is guided from the paper ejection path 12 to the first branch path 155a of the inversion path 154. Further, the sheet pushes open the flexible flapper of the connecting portion 157 with its tip, and is conveyed to the back of the reversing path 155c by the reversing roller 158.

The main body control unit 121 temporarily stops driving the reversing roller drive motor so that the reversing roller 148 holds the rear end of the sheet in a nipped state. At this time, the flexible flapper of the connecting portion 157 returns to the original state in which the rear end of the sheet passes through the connecting portion 157 and blocks the first branch path 155a, and opens the second branch path 155b. ing. Next, the main body control unit 121 drives the reversing roller drive motor in the forward rotation, whereby the sheet is switched back from the reversing path 155c through the second branch path 155b and returned to the paper ejection path 12. It is conveyed to the sheet folding processing device C.

FIG. 24A is a plan view of the sheet S2 which is carried into the sheet folding device C after the image is formed by the image forming apparatus A as described above and then inverted by the second inversion unit 142. As can be clearly seen in comparison with the sheet S1 of FIG. 21A, the image Im of the sheet S2 is upward, and the upper end side of the vertical original sheet is on the lower end side (the left side of the horizontal original sheet is on the right side). .. That is, the front end and the rear end in the sheet transport direction are opposite to those when the image is conveyed from the image forming unit 3 by the image forming apparatus A, and the front surface and the back surface are inverted.

FIG. 24B is a drawing of the folded sheet SH2 when the sheet S2 is Z-folded by the sheet folding device C in the second folding mode and conveyed from the folding roller pair 34, as viewed from above in the sheet conveying direction. .. FIG. 24 (c) shows the folded sheet SH2 when the folded sheet SH2 of FIG. 24 (b) is inverted by the first inversion unit 141 and returned to the sheet carry-out path 43.

In this way, the sheet that has been inverted after image formation by the image forming apparatus A is Z-folded by the sheet folding apparatus C in the second folding mode and then inverted again in the second folding mode, whereby Z-folded in the first folding mode. Similar to the folded sheet SH1 of b), the image Im can be folded downward and the upper end side (left end side of the horizontally placed original sheet) of the vertically placed original sheet can be Z-folded and carried out toward the downstream side in the sheet transport direction. it can. Moreover, unlike the folded sheet SH1 of FIG. 21 (b), the sheet tip (204 of FIG. 24 (b)) and the second crease 203 coincide with the sheet transport direction, and the protruding portion to the downstream side (the tab). Is advantageous in that is not formed.

Although the present invention has been described above in relation to the preferred embodiment, the present invention is not limited to the above embodiment, and can be implemented with various modifications 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 Transport path 33 Resist roller vs. 34 Folding roller vs. 35 Veneer 38, 39 Nip part 41 Sheet loading path 42 Central transport path 43 Sheet transport path 45 Top transport guide 45a 1st horizontal part 45b 2nd horizontal part 45c Inclined part 46 Lower transport guide 46a 1st lower guide part 46b 2nd lower guide part 47 Convex part 48 Gap 50 Loop forming space 51a 1st horizontal guide part 51b 1st inclined guide Units 58 to 60 Drive mechanism 120 Control unit 121 Main body control unit 124 Folding processing information acquisition unit 125 Sheet thickness information acquisition unit 126 Size information acquisition unit 128 Fold loop counter 141 First reversing unit 142 Second reversing unit 143 Carrying out roller 144 154 Reversing pass 148,158 Reversing roller 201 Sheet tip 202 First crease 203 Second crease 204 Seat rear end

Claims (6)

A feed roller that transports the sheet in the transport direction,
A pair of folding rollers arranged on the downstream side in the transport direction of the feed roller and
A thrust member that can move from the upstream side in the transport direction toward the folding roller pair,
A loop forming space for forming a loop on the sheet is provided on the upstream side in the transport direction of the folding roller pair.
When the thrust member abuts a predetermined position of the sheet on which the loop is formed in the loop forming space and moves to a thrust position to be niped by the folding roller pair, the folding roller pair nips the folding position of the sheet. A sheet folding device that forms creases
A loop of the sheet is formed in the loop forming space so as to extend from the folding roller pair toward the upstream side in the transport direction, and a guide portion for restricting the loop of the sheet in the height direction intersecting the transport direction is further provided. A sheet folding device characterized by being provided. A transport path for transporting the sheet from the feed roller to the folding roller pair in the transport direction is further provided.
The sheet folding device according to claim 1, wherein the guide portion is arranged below the transport path. The guide portion is characterized by having a first guide that inclines downward from the folding roller pair to the upstream side in the transport direction, and a second guide that extends from the first guide to the upstream side along the transport direction. The sheet folding device according to claim 1 or 2. The folding roller pair rotates to transport the sheet to the downstream side in the transport direction by a predetermined transport amount, and then rotates in the opposite direction to transport the sheet to the upstream side in the transport direction to form a loop in the loop forming space. The sheet folding apparatus according to any one of claims 1 to 3. The fourth aspect of claim 4, wherein when the folding roller pair rotates in the opposite direction to transport the sheet to the upstream side in the transport direction, the feed roller holds the upstream side in the transport direction of the sheet and stops. Sheet folding device. An image forming unit that forms an image on a sheet,
An image forming apparatus including the sheet folding apparatus according to any one of claims 1 to 5, which folds a sheet sent from the image forming unit.

Images