JP2020189716A - Sheet folding device and image forming device - Google Patents

Abstract

To provide a sheet folding device, which can improve an appearance of a folded sheet folded in a Z shape by the device.SOLUTION: A sheet folding device C1 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; and a control part 120 that controls a pushing plate 35 that moves to a pushing position at which the folding roller pair is caused to nip the sheet. The control part causes the resist roller pair to convey the sheet with the folding roller pair nipping a tip side of the sheet and stopping, which allows the pushing plate to move a predetermined position of the sheet having a loop formed at an upstream side of the folding roller pair to the pushing position; and activates the folding roller pair to nip a first folding position of the sheet and performs first folding, and causes the folding roller pair to convey the sheet further and to nip a second folding position of the sheet having the loop formed to match the position with a rear end of the sheet to perform second folding.SELECTED DRAWING: Figure 29

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.

JP-A-2002-68583

In the conventional apparatus described in Patent Document 1, the paper folding roller pair pulls in a predetermined amount of the tip side of the paper piece (sheet) fed by the feed roller pair, pauses in a nipped state, and then continues feeding from the feed roller pair. The predetermined position of the paper piece that is curved and suspended downward is pulled into the paper piece lead-in port of the paper folding roller pair and Z-folded by the paper piece guide deflection member that returns from the second position to the first position. In the Z-folded sheet in this way, the tip in the sheet transport direction is formed at a predetermined position on the paper piece by the paper folding roller pair by a predetermined amount that was nipled by the paper folding roller pair at the time of pausing. Since it protrudes to the downstream side from the position of, there is a risk that the appearance of the folded sheet may be spoiled depending on the amount of protrusion.

The present invention has been made in view of the above-mentioned conventional problems. In a sheet folding device in which a thrusting member is abutted at a predetermined position of a sheet and Z-folding is performed with a pair of folding rollers, the tip of the sheet is formed in the sheet transport direction. Alternatively, the purpose is to match the positions of the creases formed on the sheet with the rear end, thereby improving the appearance of the folded sheet.

The sheet folding device of the present invention has, in its first aspect,
A feed roller that is placed in the transport path and transports the sheet,
A pair of folding rollers located on the downstream side of the feed roller and niping a predetermined position of the sheet to form a crease.
A thrust member that moves to a thrust position that nips a predetermined position of the sheet to the folding roller pair,
It is equipped with a control unit that controls the operation of the feed roller, folding roller pair, and thrust member.
The control unit
The thrusting member thrusts the sheet in which a loop is formed on the upstream side of the folding roller pair by the feed roller continuing to convey the sheet while the folding roller pair nips and stops the sheet conveyed from the feed roller. The first fold, which is pushed to move to the thrust position, and the folding roller pair conveys the sheet from the stopped state and nips the first position of the sheet to form the first crease.
After the first fold, the fold roller pair forms a second fold by niping the second position of the sheet on which the loop is formed so as to align with the rear end of the sheet. It is characterized by doing.

The sheet folding device of the present invention has a second aspect thereof.
A feed roller that is placed in the transport path and transports the sheet,
A pair of folding rollers located on the downstream side of the feed roller and niping a predetermined position of the sheet to form a crease.
A thrust member that moves to a thrust position that nips a predetermined position of the sheet to the folding roller pair,
It is equipped with a control unit that controls the operation of the feed roller, folding roller pair, and thrust member.
The control unit
A loop is formed on the upstream side of the folding roller pair by the feed roller continuing to convey the sheet while the folding roller pair has stopped by niping a predetermined nip position of the sheet fed from the feed roller in the conveying direction. The thrust member pushes the sheet to move to the thrust position, and the folding roller pair conveys the sheet from the stopped state and nips the first position of the sheet to form the first crease. 1 fold and
The fold roller pair performs a second fold to form a second fold by niping the second position of the sheet on which the loop is formed by transporting the sheet after the first fold. ,
In the first folding, the control unit has a first folding mode in which the predetermined nip position of the sheet is set to the first nip position near the tip of the sheet, and the predetermined nip position of the sheet is from the first nip position. Can also be selected from the second fold mode set at the second nip position on the rear end side of the sheet. In the second fold mode, the second position of the sheet is aligned with the rear end of the sheet to nip. It is characterized by making a second fold.

Further, in another aspect of the present invention, the image forming apparatus of the present invention comprises the above-mentioned sheet folding apparatus of the present invention and a switchback reversing unit that inverts the front and back and the front and back of the sheet carried into the sheet folding apparatus in the conveying direction. It is characterized by including an image forming unit for forming an image on a sheet.

According to the first side surface of the sheet folding device of the present invention, in the second folding, the second position of the sheet in which the loop is formed on the upstream side of the folding roller pair is aligned with the rear end of the sheet and the folding roller. By niping in pairs, the second fold of the Z-folded folded sheet coincides with the rear edge of the sheet, so that a good-looking folded sheet can be formed.

According to the second aspect of the sheet folding device of the present invention, when the control unit selects the second folding mode, a loop is formed on the upstream side of the folding roller pair in the second folding as well. By aligning the second position with the rear edge of the sheet and niping it with a pair of folding rollers, the second crease of the Z-folded folded sheet coincides with the rear edge of the sheet to form a good-looking folded sheet. Can be done.

Therefore, since the image forming apparatus of the present invention includes the sheet folding apparatus of the present invention described above, the rear end of the sheet image-formed by the image forming unit is Z-folded so as to coincide with the second crease, and the appearance is good. The folded sheet can be carried out.

The whole block diagram of the image formation system by 1st Embodiment of this invention. The schematic block diagram of the sheet folding apparatus of 1st Embodiment. (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 figure which illustrates the arrangement of the thrust member in a preferable retracting position. The block diagram which shows the control configuration of the sheet folding apparatus of FIG. 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 so that one of the folds is aligned with the tip side of the sheet in the sheet transport direction. The flowchart explaining the whole processing operation of the sheet folding apparatus of FIG. FIGS. (A) to (f) are diagrams showing the folding process of the sheet folding apparatus of FIG. 2 in the order of processes. The flowchart explaining the folding loop counter setting process of FIG. The flowchart explaining the resist process of FIG. The flowchart explaining the folding loop processing of FIG. 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. An enlarged cross-sectional view of a main part of the central transport path in which the veneer moves through the second path portion. The figure which shows the veneer arranged further upstream from the evacuation position. An enlarged cross-sectional view of a main part of a veneer that moves along a second inclined guide portion of a second lower guide portion. An enlarged cross-sectional view of a main part showing the entrainment of the sheet in the nip part of the folding roller pair. The timing chart of the drive voltage applied to the resist roller drive motor MT1 and the veneer drive motor MT3. The flowchart explaining the guide process of FIG. 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 so that one fold is aligned with the rear end of the sheet in the sheet transport direction. The whole block diagram of the image formation system by 2nd Embodiment of this invention. The schematic block diagram of the sheet folding apparatus of 2nd Embodiment. The block diagram which shows the control structure of the sheet folding apparatus of FIG. The flowchart explaining the whole processing operation of the sheet folding apparatus of FIG. The flowchart explaining the folding operation setting process of FIG. The flowchart explaining the crease formation process of FIG. The flowchart explaining the carry-out process of FIG. FIGS. (A) to (f) are diagrams showing the folding process of the sheet folding apparatus of FIG. 23 in the second folding mode in the order of steps. FIGS. (A) and (b) are diagrams showing the folding process of the sheet folding apparatus of FIG. 23 in the first folding mode in the order of steps. The figures (a) and (b) are views of the sheet before the folding process in the second embodiment and the folded sheet after the folding process in the first folding mode, respectively, 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 after the folding process in the second folding mode in the second embodiment and the folded sheet passed through the first reversing portion thereafter in a plan view. FIGS. (A) to (C) show a modified example of the second embodiment, a sheet before the folding process, a folding sheet after the folding process in the second folding mode, and a folded sheet that has passed through the first reversing portion thereafter. Each is a plan view.

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 the image forming system of the first embodiment according to the present invention. The image forming system of the figure includes an image forming apparatus A1, a sheet post-processing apparatus B, and a sheet folding apparatus C1 connected between them. The sheet image-formed by the image forming apparatus A1 is conveyed through the sheet folding apparatus C1 and stored in the discharge tray by the sheet post-processing apparatus B. The image forming apparatus A1, the sheet post-processing apparatus B, and the sheet folding apparatus C1 will be described in detail below.

[Image forming device]
The image forming apparatus A1 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 A1 of the present embodiment is a so-called in-body paper ejection type, and is large between the image forming unit 3 arranged in a U-shape in the front view in FIG. 1, the paper discharging unit 4, and the image reading unit 5. The transport relay unit 7 is arranged in the defined paper ejection space. 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 A1.

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.

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

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

The second relay section 18 is provided with a second relay path 23 inside, and the second sheet inlet 24 thereof is arranged so as to be connected to the second paper ejection port 16 of the paper ejection unit 4. The second seat outlet 25 of the second relay path 23 opens on substantially the same surface as the left side surface of the device housing 1 and is connected to the seat carry-in inlet of the sheet folding device C1 as described later. The second relay path 23 is provided with a plurality of transfer rollers that are driven by a motor built in the second relay unit 18 to convey the sheet. The image-formed sheet conveyed from the paper ejection unit 4 via the second paper ejection path 14 is fed to the sheet folding device C1 through the second relay path 23 by the conveying roller.

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.

With the above configuration, the image forming apparatus A1 reads the document sent from the document feeding unit 5 by the image reading unit 4, and forms an image on the sheet sent from the paper feeding unit 3 by the image forming unit 2 according to the read image data. To do. When the image-formed sheet is not folded by the sheet folding device C1 and post-processed by the sheet post-processing device B, the image-formed sheet is conveyed from the paper ejection unit 4 via the first paper ejection path 13 and passes through the first relay path 20. It passes through and is carried out to the sheet discharge tray 19 in the paper discharge space. 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, passes through the second relay path 23, and is a sheet folding apparatus. It is sent to C1.

[Sheet post-processing device]
As shown in FIG. 1, the sheet post-processing device B has a first transport path 101 for transporting the sheet from the sheet folding device C1 into the housing 100, and second and third transports branched from the first transport path. It includes paths 102 and 103, post-processing equipment such as a staple unit ST1, and a binding processing tray 104. On one side surface of the housing 100 (the left side surface in FIG. 1), first and second paper discharge trays 105 and 106 for loading and storing sheets discharged from the sheet aftertreatment device B are provided vertically separated from each other. There is. The sheet post-processing device B is arranged so that the sheet carry-in port 107 of the first transport path 101 is connected to the sheet discharge port of the sheet folding device C1 described later.

The first paper ejection tray 105 is arranged below the paper ejection port 108 of the second transport path 102 that opens on the side surface of the housing 100. The sheet sent from the sheet folding device C1 is conveyed from the first transfer path 101 to the second transfer path 102 when the staple binding process and / or other post-processing by the staple unit ST1 is not performed in the sheet post-processing device B. As it is, it is discharged from the paper ejection port 108 to the first paper ejection tray 105.

The paper ejection port 109 of the third transport path 103 is arranged above the binding processing tray so as to face the paper loading surface of the binding processing tray 104. The sheet sent from the sheet folding device C1 is conveyed from the first transfer path 101 to the third transfer path 103 when the staple binding process is performed by the staple unit ST1, and the sheet is placed on the binding processing tray 104 from the paper ejection port 109. It is discharged to the surface. 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 second paper discharge tray 106 below.

[Overall configuration of sheet folding device]
As shown in FIG. 2, the sheet folding device C1 has a transport path 32 formed inside the housing 31 from the sheet carry-in port 32a on the image forming apparatus A1 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 C1 has a sheet carry-in port 32a at the second sheet outlet 25 of the transport relay unit 7 installed in the image forming device A1 and a sheet discharge port at the sheet carry-in port 107 of the sheet post-processing device B. 32b are arranged so as to be connected to each other.

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 the sheet folding device C1, 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 has been 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 transport relay unit 7 of the image forming apparatus A1 by the discharge roller pair 37 near the second sheet outlet 25 is a pressure contact portion of the roller surface of the resist roller pair 33 whose rotation is stopped at the tip thereof. The tip positions are aligned by abutting against the nip portion 38. 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 (corresponding to the discharge roller pair 37 in FIG. 2) that discharges the sheet from the image forming apparatus A1 to the sheet folding device C1. As a result, the number of parts of the sheet folding device C1 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.

As shown in FIG. 2, a relatively large loop forming space 50 is provided below the gap 48 of the lower transport guide 46. When the veneer 35 is retracted (indicated by a solid line in FIG. 2) and the gap 48 is opened, the sheet in the central transport path 42 can be hung from the gap 48 into the loop forming space 50. When the veneer 35 advances (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 does not hang down in the loop forming space 50, and the central transport path 42 It can be conveyed toward the folding roller pair 34 along the line.

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 includes a second horizontal guide portion 52a extending horizontally from the folding roller pair 34 to the upstream side, a second inclined guide portion 52b inclined downward from the second horizontal guide portion to the upstream side, and the like. It has a vertical guide portion 52c extending substantially vertically downward from the second inclined guide portion. The second horizontal guide portion 52a cooperates with the second horizontal portion 45b of the upper transport guide 45 to restrict the sheet from both sides in the thickness direction, that is, in the vertical direction, while folding the tip of the sheet to the nip portion of the roller vs. 34. I will guide you to 39. The second inclined guide portion 52b is inclined toward the loop forming space so as to guide the sheet hanging from the loop forming space 50 to the nip portion 39 of the folding roller vs. 34. The vertical guide portion 52c, together with the second inclined guide portion 52b, isolates the sheet hanging from the loop forming space 50 from the folding roller vs. 34 side while ensuring the dimensions of the loop forming space 50.

When the veneer 35 is in the retracted position, the sheet sent out from the resist roller pair 33 to the central transport path 42 passes through the gap 48 opened downward from the sheet tip when it exceeds the downstream end of the first inclined guide portion 51b. It hangs linearly in the loop forming space 50. 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.

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.

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

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 as 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.

FIG. 4 shows an enlarged and concrete example of a suitable arrangement of the veneer 35 in the retracted position. As shown in the figure, the height H is 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 of the lower transport guide 46 facing the second horizontal portion 45b. The upper and lower gaps of are defined. As a result, the third path portion of the central transport path 42 has a straight portion 66 extending horizontally and linearly upstream from the folding roller pair 34.

The height H of the straight portion 66 is located on both the upper and lower sides of the veneer 35 located in the straight portion, between the second horizontal portion 45b of the upper transport guide 45 and the second horizontal guide portion 52a of the lower transport guide 46. Set so that several sheets can be passed smoothly in an overlapping state. 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 A1 so that the sheets in a folded state can be passed through. As a result, the veneer 35 can smoothly move to the thrust position in the third path portion while pushing the sheet with the tip in the folding process described later.

It is preferable that the veneer 35 is arranged so that the tip of the veneer 35 is close to the nip portion 39 of the folding roller pair 34 in the gap of the straight portion 66 of the third path portion at the thrust position. Therefore, the veneer 35 of FIG. 4 is horizontally arranged in the height H range of the extension line 66a extending the straight line portion 66 to the upstream side at the retracted position. 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.

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

The retracted position of the veneer 35 is not limited to the height H range of the extension line 66a of the straight portion 66. If the 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 figure is shown in FIG. The retracted position can be provided at a position different from 4.

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. 5 described later. The drive of the veneer drive motor MT3 is controlled by the control unit 120 shown in FIG. 5 as described later.

[Drive mechanism of sheet folding device]
3 (a) and 3 (b) 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 C1. 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.

[Control configuration of sheet folding device]
FIG. 5 conceptually shows the control configuration of the sheet folding device C1 of the first embodiment. The sheet folding device C1 includes a control unit 120 including a control board including a CPU. As shown in the figure, the control unit 120 is connected to the first to third detection sensors S1 to S3 provided along the transport path 32.

The first detection sensor S1 is arranged in front of the 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 A1 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. The detection results of the first to third detection sensors S1 to S3 are output to the control unit 120 in real time.

Further, the control unit 120 is connected to the main body control unit 121 of the image forming device A1 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 A1. 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 C1 is transmitted from the main body control unit 121 to the control unit 120 via the sheet post-processing device B. To.

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 A1. The folding processing information acquisition unit 124 includes a sheet thickness information acquisition unit 125 that acquires and stores information about the sheet to be folded, particularly information about the sheet thickness, and a size information acquisition unit 125 that acquires and stores information about the sheet size. 126 and are provided.

The control unit 120 is further connected to the registration roller drive motor MT1, the folding roller drive motor MT2, and the veneer drive motor MT3, if the veneer drive motor MT3 is provided with the additional folding mechanism 36, the additional folding drive motor MT4. Based on the detection results input from the first to third detection sensors S1 to S3 and the various information received from the main body control unit 121 of the image forming apparatus A1, the drive of each drive motor MT1 to MT3 and optionally MT4 is controlled. Then, the sheet is conveyed in the transfer path 32, and the folding processing operation of the sheet folding device C1 is controlled and executed.

Further, the control unit 120 transmits information such as sheet transport and folding processing executed in the sheet folding device C1 to the main body control unit 121 of the image forming device A1 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 a sheet transport failure or a sheet folding process failure in the sheet folding device C1, 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 control unit 120 includes a ROM 127 in order to store various control control programs executed by the control unit 120 as described above and as described later, and data necessary for the control programs. Further, the control unit 120 incorporates a folding loop counter 128, which will be described later.

The sheet folding device C1 of the first embodiment is suitable for alternately folding the sheet inward and outward along the sheet transport direction and folding the sheet in three in a so-called Z-fold. FIG. 6A shows a plan view of the sheet S before the folding process, and FIG. 6B shows an example of the sheet SH Z-folded by the sheet folding device C1 from the sheet width direction. In the folded sheet SH of FIG. 6B, one of the two folds is arranged on the tip (downstream end) 201 side in the sheet transport direction. Specifically, in the folded sheet SH, a first crease 202 is formed in the vicinity of the downstream end 201 in the sheet transport direction at a predetermined length from the rear end (upstream end) 204 in the sheet transport direction to the downstream side. A second crease 203 is formed at a position of a predetermined length by folding back from the upstream side.

In FIGS. 6A and 6B, the respective sheet SHs are represented so as to have the same tip positions in the sheet transport direction. As can be seen from the figure, according to the present embodiment, the sheet SH of FIG. 6B is Z-folded so that the size in the sheet transport direction is halved of the original sheet size. The folding operation of the sheet folding device C1 will be described below.

[Processing operation of sheet folding device]
The sheet folding device C1 is preset with a folding process (Z folding) mode in which a sheet is folded in three (Z folding) and a non-folding mode in which the sheet is not folded. The user decides whether or not to fold the image-formed sheet before starting the image formation of the sheet in the image forming apparatus A1, 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 input of the folding process mode is stored in the main body control unit 121 of the image forming apparatus A1 as one of the sheet information of the sheet to be folded.

As will be described later, in the fold processing mode, one crease (for example, the first crease 202) is arranged in the vicinity of the downstream end (tip) 201 of the fold sheet SH in the sheet transport direction as shown in FIG. 6 (b). It is possible to set a first fold mode and a second fold mode in which one fold (for example, the second fold 203) is arranged so as to be aligned with the upstream end (rear end) 204 of the fold sheet SH in the sheet transport direction. it can. The case where the folding processing operation of the sheet folding device C1 is in the first folding mode will be described below.

The entire processing operation in the sheet folding device C1 will be schematically described with reference to the flowchart of FIG. 7. First, when the first detection sensor S1 detects the tip of the sheet carried into the sheet carrying path 41 and turns on (Y in step ST01), the control unit 120 of the sheet folding device C1 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 A1 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 C1 are included.

In the present embodiment, 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 A1. In another embodiment, the sheet folding device C1 itself can acquire the basis weight of the sheet carried in from the image forming device A1. For example, a detection technique has been 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 C1, 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 A1 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 ST07 to execute the folding process. If the sheet information from the image forming apparatus A1 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 ST08 to execute the folding process.

In the non-folding process of step ST08, the veneer 35 is arranged at the guide position (35'), and the resist roller pair 33 and the folding roller pair 34 are rotationally driven in this state. As a result, the sheet from the image forming apparatus A1 passes through the transport path 32 as it is without being folded, and is carried out to the sheet post-processing apparatus B.

As a whole, the folding process of steps ST04 to ST07 includes a folding loop counter 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). , And the crease forming process (step ST07) by the veneer 35 and the folding roller pair 34 are performed in four steps. In the folding loop counter setting process, the folding loop count value is set. In the resist treatment, the tips of the sheets carried into the sheet folding device C1 are aligned to correct the sheet skew (skew). In the fold loop process, a loop for forming a crease is formed on the tip end side of the sheet. In the crease forming process, creases are formed on the looped sheet by the folding rollers vs. 34.

The processing in each step ST04 to ST07 will be specifically described below with reference to FIGS. 8 to 21. 8 (a) to 8 (f) show the process in which the sheet folding device C1 carries in the sheet from the image forming device A1, conveys the sheet, and performs the folding process. It is preferable that the folding loop counter setting process is executed at the latest before the sheet is carried from the image forming apparatus A1 into the sheet folding apparatus C1 and the resist process is started.

[Fold loop counter setting process]
The folding loop counter setting process is executed, for example, according to the procedure shown in the flowchart of FIG. In the control unit 120, the size information acquisition unit 126 acquires information regarding the sheet size from the sheet information received by the sheet information acquisition unit 124 from the main body control unit 121 of the image forming apparatus A1. Based on the acquired sheet size, the control unit 120 determines the reference folding loop count value Px (step ST02-1).

As will be described later, the reference folding loop count value Px determines the timing at which the veneer 35 is activated to be abutted against the sheet, and is calculated from the sheet size by, for example, the control unit 120 according to a predetermined calculation formula set in advance. can do. Further, for each of the plurality of sheet sizes scheduled to be used in the image forming apparatus A1, the reference folding loop count value Px is set in advance and stored in the ROM 127, and corresponds to the sheet size acquired by the size information acquisition unit 126. The reference folding loop count value Px to be used can be selected by the control unit 120.

Next, the thickness information acquisition unit 125 acquires information on the thickness of the sheet from the sheet information received from the image forming apparatus A1. Based on the acquired sheet thickness, the control unit 120 determines whether or not the sheet to be folded is thin paper (step ST02-2).

When it is determined that the paper is thin (Y in step ST02-2), the control unit 120 sets the value obtained by adding the predetermined deviation amount ΔP to the reference folding loop count value Px to the folding loop counter 128 as the folding loop count value P. Set (step ST02-3). On the other hand, when it is determined that the paper is thick (N in step ST02-2), the reference folding loop count value Px is set as the folding loop count value P in the folding loop counter 128 (step ST02-4).

The reference fold loop count value Px is the standard start timing of the veneer 35 applied to thick paper, whereas the deviation amount ΔP added to it starts the veneer 35 with respect to the standard start timing. It is the amount of delay in the timing of making it. The deviation amount ΔP of the folding loop count value can be preset according to the thickness level of the thin paper, that is, the thinness level of the sheet with respect to the thickness of the thick paper or the standard sheet.

In the present embodiment, the folding loop counter setting process is performed by using a commercially available copy paper as plain paper and a sheet having a thickness larger than that as thick paper and a sheet having a thickness smaller than plain paper as thin paper. I do. In another embodiment, a sheet thicker than plain paper may be set as thick paper, and a sheet having a thickness less than or equal to plain paper may be set as thin paper. Further, it may be set in three stages of plain paper, thick paper having a larger thickness, and thin paper having a smaller thickness.

Actually, the control unit 120 can recognize the thickness of the sheet based on the type of the sheet selected by the user on the setting panel D of the image forming apparatus A1. Since the type of sheet and the thickness of the sheet to be used in the image forming apparatus A1 are known in advance, only thick paper or thin paper needs to be set in advance for each type of sheet.

[Resist processing]
FIG. 8A shows a state in which the tips of the sheets S are aligned in the resist process of the sheet folding device C1. The resist process is performed, for example, according to 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 S abuts on the nip portion 38 of the resist roller pair 33, and a loop-shaped deflection necessary and sufficient for aligning the tip positions is provided in the sheet loading path. It is the time required to form the sheet at 41. 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 S is conveyed to the folding roller pair 34 along the central transport path 42, as shown in FIG. 8 (b). 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, the tip of the sheet is guided by 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 vs. 34. In the sheet S whose tip has passed through the convex portion 47 of the central transport path 42, the inclined portion 45c of the upper transport guide 45 and the second horizontal portion 45b are connected 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. As shown in FIG. 8B, when the second detection sensor S2 detects the tip of the sheet S to be conveyed and turns on (Y in step ST21) immediately upstream of the folding roller pair 34, the control unit 120 executes an evacuation process for moving the veneer 35 from the guide position to the evacuation position (step ST22).

The evacuation process of the veneer 35 is executed, for example, according to 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. 8C, and the gap 48 between the first and second lower guide portions 46a and 46b is completely opened. As a result, in the central transport path 42, as shown in the figure, the second path portion is opened to the lower loop forming space 50.

Next, the control unit 120 starts the resist roller drive motor MT1 up to a preset first set drive amount, counting from the time when the second detection sensor S2 detects the seat tip in step ST21 (step). (Y) of ST23 and the folding roller drive motor MT2 are stopped (step ST24). Here, the first set drive amount is the drive amount of the resist roller drive motor MT1 required to reach the position where the seat tip is nipped into the nip portion 39 of the folding roller vs. 34.

As a result, as shown in FIG. 8C, the sheet S is held in a state where the tip is nipped into the nip portion 39 of the folding roller pair 34 and is nipped. After this, the resist roller drive motor MT1 is continuously driven, and the resist roller pair 33 rotates to continuously feed the sheet S. As a result, the portion of the sheet on the upstream side of the folding roller pair 34 is curved and hangs down from the gap 48 in the loop forming space 50 in a loop shape, and a folding loop FL for forming a crease is formed on the sheet. After that, the folding loop FL becomes larger according to the amount of the sheet S delivered by the resist roller pair 33.

In the present embodiment, the feed amount (transport distance) of the sheet from the position detected by the second detection sensor S2 to the position where the sheet tip exceeds the nip portion 39 of the folding roller pair 34 by a predetermined amount is the resist corresponding thereto. The first set drive amount is set in terms of the drive amount of the roller drive motor MT1. In the present embodiment, the predetermined amount of the sheet tip exceeding the nip portion 39 is set to, for example, 10 mm. By reducing the predetermined amount in this way, as will be described later, the crease (first crease 202) on the downstream side in the sheet transport direction can be arranged at a position closer to the sheet tip (downstream end). Here, the drive amount of the resist roller drive motor MT1 includes the rotation amount of the motor (rotation number of the rotation shaft, rotation angle, rotation time, etc.) and the sheet delivery amount by the resist roller pair 33, that is, the rotation amount of the drive roller 33a. (Rotation number, rotation angle, rotation time, etc. of the roller shaft 61) can be used.

In the present embodiment, the folding position of the sheet is set in advance according to the size and the orientation (vertical direction, horizontal direction) of the sheet during transportation, for example, the folding position represented by the distance from the sheet tip in the sheet transport direction. Has been done. A predetermined count value is predetermined in the folding loop counter in order to form a loop in the sheet being conveyed, corresponding to the folding position of each sheet size. After the folding roller drive motor MT2 is stopped in step ST24, the folding loop counter that started counting in step 13 counts up to the predetermined count value (Y in step ST25), and then the next crease forming process (step ST06). ) Is executed. The folding loop counter can also be operated to count down by subtracting from the predetermined count value to "0".

[Fold formation process]
The crease forming process is executed, for example, according to the procedure shown in the flowchart of FIG. The control unit 120 starts the veneer 35 thrusting process at the same time that the folding loop counter counts up in step ST25 and a desired folding loop FL is formed in the loop forming space 50. At this time, the folding loop FL has a size suitable for forming a crease on the sheet S at a predetermined folding position as shown in FIG. 8 (d) by continuously feeding out the sheet of the resist roller pair 33. It is formed.

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) while the resist roller drive motor MT1 is continuously driven and the seat S is sent out to the central transport path 42, and the veneer 35 is pushed. Move horizontally to the side of the folding roller vs. 34. The tip of the veneer 35 that has started to move downstream from the retracted position abuts on the folding loop FL at a position close to the downstream end of the first lower guide portion 46a of the lower transport guide 46 where the folding loop FL starts to hang down.

Further, the veneer 35 moves toward the nip portion 39 of the folding roller pair 34 while pushing the predetermined position of the sheet S with its tip. FIG. 15 shows in detail the process in which the veneer 35 moves downstream of the second path portion of the central transport path 42. As shown in the figure, the veneer 35 moves horizontally and linearly along the tangent line 39a of the nip portion 39 from the retracted position described above in relation to FIG. The portion of the sheet S upstream from the tip of the veneer 35 has a narrow gap between the second horizontal portion and the upper surface of the veneer 35 while the veneer 35 passes below the second horizontal portion 45b of the upper transport guide 45. Be transported.

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 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 to speed, that is, 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, there is no possibility that the veneer abutting position shifts from the predetermined position of the veneer to the upstream side or the downstream side in the transport direction. As a result, the following problems that may occur when the moving speed of the 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 vs. 33, the sheet S 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 There is a risk that the veneer 35 will be stretched between the veneer 33 and the veneer 35 will be displaced upstream from the predetermined position of the veneer 35, or the veneer S will slip on the nip 38 of the resist roller 33. 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 S loosens between the tip of the veneer 35 and the resist roller pair 33, and therefore the upper transfer guide 45 2 There is a possibility that the horizontal portion 45b and the veneer 35 may be curved in the gap, or the veneer 35 abutting position may be displaced downstream from the predetermined position of the sheet S. 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, as shown in FIG. 16, the tip of the veneer 35 at the retracted position is placed on the tangent line 39a of the nip portion 39 to which the veneer moves. In the transport direction, the lower transport guide 46 is arranged at a distance I from the downstream end of the first lower guide portion 46a to the upstream side.

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 sheet S, which is pushed by the veneer 35 and advances downstream on the central transport path 42, enters the third path portion as shown in FIG. 17, the upper sheet portion sandwiching the veneer 35 is transported upward. The second horizontal portion 45b of the guide 45 regulates from above, and the lower seat portion is regulated from below by the second lower guide portion 46b of the lower transport guide 46. FIG. 17 shows in detail the process in which the tip of the veneer 35 moves between the second horizontal portion 45b of the upper transport guide 45 and the second inclined guide portion 52b of the second lower guide portion 46b. At this time, the sheet S is narrowed down to a form in which a portion downstream from the tip of the veneer 35 is inclined upstream along the second inclined guide portion 52b.

Further, as shown in FIG. 8E, the tip of the veneer 35 advances 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, and these The seat S is regulated from above and below in a narrow gap. As a result, the sheet S is temporarily folded into a form in which the veneer 35 is bent at the predetermined position against which the veneer 35 is abutted while advancing through the third path portion. This temporarily folded bending position is pressure-folded by the later folding roller pair 34 to become the first fold 202 of the folding sheet SH shown in FIG. 6 (b).

When the drive amount of the veneer drive motor MT3 becomes a preset second set drive amount (Y in step ST54), the veneer drive motor MT3 is stopped (step ST55). As a result, as shown in FIG. 8E, the veneer 35 has a second horizontal guide portion 45b of the upper transport guide 45 and a second horizontal guide portion 46b of the second lower guide portion 46b at the tip of the third path portion. It stops at the thrust position 35 ″ that has entered between the 52a and the fold roller pair. As a result, the first fold position FP1 that becomes the first fold 202 of the sheet S is bent by the above-mentioned temporary folding. It is carried to just before the nip portion 39 of 34.

By inserting the veneer 35 between the upper transport guide 45 and the second lower guide portion 46b in this way, the sheet S is temporarily bent in the direction in which the sheet S overlaps vertically at the folding position. Folded. After the temporary folding in this way, the sheet is nipped into the folding roller pair 34 at the first folding position and folded, thereby suppressing the opening of the folded portion of the sheet at the first crease 202 and making a good-looking fold. Sheet SH can be made.

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.).

After the veneer drive motor MT3 is stopped in step ST55, when the resist roller drive motor MT1 is driven to a preset third set drive amount (Y in step ST31), the control unit 120 is driven by the folding roller drive motor. The MT2 is driven (step ST32). Here, the third set drive amount continuously feeds the seat even after the veneer drive motor MT3 is stopped in step ST58, and as shown in FIG. 18, the seat folding position FP1 is the folding roller vs. 34. This is the driving amount of the resist roller drive motor MT1 that rotates the resist roller pair 33 up to the position where it is caught in the nip portion 39.

When the folding roller pair 34 is rotated by the drive of the folding roller drive motor MT2, the folding position FP1 which is the first fold of the seat is caught in the nip portion 39 of the folding roller pair 34 as shown in FIG. 8 (f). Then, while being conveyed to the downstream side, it is pressure-bent between the vertical folding rollers 34a and 34b. By this pressure processing, the first crease F1 (202) is formed in the sheet at a predetermined fold position. Since the sheet folding position FP1 is conveyed in the sheet conveying direction in the temporarily folded form as described above and is directly involved in the nip portion 39 of the folding roller pair 34, the position of the first crease F1 varies from the conventional one. It is stable with high accuracy without causing.

FIG. 19 is a timing chart of the drive voltage applied to the resist roller drive motor MT1 and the veneer drive motor MT3 controlled by the control unit 120. The time represented by the horizontal axis in the figure is a conversion of the count number of the drive pulse of the resist roller drive motor MT1 described above in relation to the folding loop counter into time, and therefore depends on the drive speed of the motor MT1. Change.

In the figure, the resist roller drive motor MT1 is started at time t0 (step ST12 in FIG. 10), and the count of the drive pulse is started by the folding loop counter 128 (step ST13 in the same step). When the sheet is plain paper or thick paper (SP1), the veneer drive motor MT3 is activated at time t1, and the veneer 35 starts moving. The time t1 is when the fold loop counter 128 counts up the reference fold loop count value Px (step ST02-4 in FIG. 9) starting from the time t0.

Here, the reference folding loop count value Px is the feed amount of the sheet fed downstream in the transport direction after the resist treatment by the resist roller pair 33. As shown in FIG. 6A, the sheet S (FIG. 8C) held in the nip portion 39 of the folding roller pair 34 from the tip (downstream end) in the sheet transport direction. It corresponds to the distance obtained by adding the sheet transport direction length ΔL to the nip portion to 1/2 length L'= L / 2 of the sheet transport direction length L of the sheet.

As shown in FIG. 6B, the position of the fold loop count value Px in the sheet S before the fold process corresponds to the first crease 202 of the Z-folded sheet SH, and the predetermined amount from the tip 201 thereof. It is arranged rearward (upstream side) by the transport distance, that is, the distance ΔL. The intermediate position between the position of the fold loop count value Px and the position behind the seat tip 201 by a distance ΔL corresponds to the second crease 203 of the Z-folded sheet SH. Therefore, the rear end (upstream end) 204 of the Z-folded sheet SH corresponds to the position of 1/2 length L'= L / 2 of the length L of the original sheet in the sheet transport direction from the tip 201. According to this embodiment, the Z-folded sheet SH can be matched with the 1/2 size of the original sheet (for example, A4 size in the case of A3 size).

When the sheet is thin paper (SP2), the veneer drive motor MT3 is activated at time t2, and the veneer 35 starts moving. The time t2 is when the folding loop counter 128 counts up the value obtained by adding the predetermined deviation amount ΔP to the reference folding loop count value Px (step ST02-3 in FIG. 9) starting from the time t0. ..

As described above, the deviation amount ΔP of this fold loop count value is the amount of deviation of the crease forming position (the length in the sheet transfer direction, that is, the sheet transfer distance) for each different sheet characteristic measured in the preliminary test, and is driven by the resist roller. It is converted into the count number of the drive pulse of the motor MT1. According to the present embodiment, not only in the case of thin paper with respect to such plain paper or thick paper, but also in consideration of the deviation of the crease formation position expected due to the difference in sheet characteristics, the deviation amount is prepared in advance. By delaying the timing of starting the movement of the veneer 35, the misalignment of the folds formed on the folded sheet can be eliminated or reduced.

When the folding roller drive motor MT2 is driven in step ST32, the control unit 120 returns the veneer 35 from the thrusting position 35 "to the retracted position so as not to prevent the sheet from being caught in the nip portion 39 of the folding roller pair 34. The evacuation process is executed (step ST33). This evacuation process is performed in the same manner as described with reference to FIGS. 12 and 8 (b) and 8 (c) in relation to the folding loop process.

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

At this time, the gap 48 between the first and second lower guide portions 46a and 46b is completely opened, and the second path portion of the central transport path 42 is opened to the lower loop forming space 50. Therefore, the folding loop FL can be smoothly wound around the nip portion 39 of the folding roller pair 34 continuously from the start of winding in FIG. 8 (e) 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 shown in FIG. 8 (f), the sheet S is folded in a tri-fold (Z-fold) with the tip thereof and the first fold F1 formed by the folding roller pair 34 first. It is niped by a pair of rollers and is conveyed downstream along the sheet carry-out path 43.

As the sheet is conveyed in this way, the folding loop FL in the loop forming space 50 gradually becomes smaller. The folding loop FL enters the third path portion of the central transport path 42, and is squeezed from above and below by the second horizontal portion 45b of the upper transport guide 45 and the second inclined guide portion 52b of the second lower guide portion 46b. , It becomes a thin loop shape extending in the sheet transport direction. Further, the folding loop FL advances between the second horizontal portion 45b and the second horizontal guide portion 52a of the second lower guide portion 46b, and is the second folding position of the rear end (upstream end) which becomes the second fold 203. It is temporarily folded into a form that is bent in half from the top and bottom by FP2.

The second folding position FP2 of the sheet S has a bent form in this way, and is conveyed and folded in the sheet conveying direction without slipping or misalignment with the upstream portion of the sheet stacked on the sheet S. It is pressure-bent at the nip 39 of the roller vs. 34. Therefore, the second crease (203 in FIG. 6B) is formed on the sheet in a stable and highly accurate position without causing the conventional variation.

As a result, as shown in FIG. 6B, 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 is generated. In the present embodiment, as described above, the folding roller pair 34, which has stopped rotating, forms a folding loop FL with the seat tip portion niped, and then the folding roller pair 34 is rotated to form the first and second folding rollers. Fold the creases of. Therefore, the portion of the sheet transport direction length ΔL from the sheet tip that was nipped by the folding roller pair 34 at the time of forming the folding loop FL is Z-folded so as to protrude from the first fold 202 to the tip side (downstream side). ..

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 (Y in step ST34), the control unit The 120 executes a guide process for moving the veneer 35 from the retracted position to the guide position 35'(step ST35). At this time, the folding loop FL is set so as to have already passed 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 S is guided by the upper surface of the veneer 35 along the central transport path 42 and folded. It is conveyed straight toward the roller vs. 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 S passing through the central transport path 42 and turns off (Y in step ST36), the control unit 120 starts from that point. When the drive amount of the folding roller drive motor MT2 is counted and reaches a preset predetermined stop drive amount (Y in step ST37), the resist roller drive motor MT1 and the fold roller drive motor MT2 are stopped (step ST38).

Here, the predetermined stop drive amount is a drive amount of the folding roller drive motor MT2 sufficient for the rear end of the seat S to pass through the folding roller pair 34. As a result, the resist roller pair 33 and the folding roller pair 34 stop rotating without causing any trouble in carrying out the sheet from the sheet carry-out port 32b to the sheet post-processing device B, and end the Z-folding process of the sheet.

When the sheet folding device C1 of the first embodiment performs the folding processing operation in the first folding mode, as shown in FIG. 6 (b), from the first crease 202 on the sheet tip side to the downstream side in the sheet transport direction. The protruding portion Tb (hereinafter referred to as a tab in the present specification) remains up to the sheet tip 201. 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 order to eliminate the tab Tb, in the second folding 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 set to the seat rear end. The folding process operation is performed so as to match with 204. FIG. 21A shows a plan view of the sheet S before Z-folding in the second folding mode, and FIG. 21B shows an example of the sheet SH after Z-folding viewed from the sheet width direction. In FIG. 21B, 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 crease 203 is the sheet rear end 204. It is formed in agreement with. As a result, the sheet S in FIG. 21 (a) can be Z-folded to 1/2 of the original sheet size without generating the tab Tb as described above.

However, in the sheet folding device C1 of the first embodiment, when the sheet is Z-folded in the second folding mode, there is a possibility that a new problem described below may occur. In the case of single-sided printing, the image forming apparatus A1 of the present embodiment is usually a sheet folding apparatus in which the image-forming sheet has its image-forming surface facing downward and the upper end of the original sheet placed vertically is on the downstream side in the sheet transport direction. It is carried out to C1. As a result, in the second folding mode, the lower surface of the folded sheet SH of FIG. 21B becomes an image forming surface, and the sheet rear end side (upstream end in the sheet conveying direction) of the image forming surface corresponding to the lower end of the original sheet. Side) is folded to the back side. Such a folded sheet is inconvenient in actual use and may cause inconvenience.

Further, 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 to the sheet post-processing device B to the first or second paper output trays 105 and 106. When ejected, the rear end side of the sheet becomes bulkier than usual on the output tray. 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. Although it can be processed, the folded sheet Z-folded in the first folding mode cannot be bound if it is carried in as it is. In other words, the folding processing operation of the sheet folding device C1 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 order to eliminate such inconvenience, the image forming system of the second embodiment according to the present invention has a sheet reversing portion for switchback transporting the sheet being transported by inverting the front and back in the transport direction and inverting the front and back surfaces. Further prepared. The image forming system of the second embodiment shown in FIG. 22 includes an image forming device A2, a sheet post-processing device B, and a sheet folding device C2 connected between them, similarly to the first embodiment of FIG. The sheet image-formed by the image-forming device A2 is conveyed through the sheet folding device C2 and stored in the discharge tray by the sheet post-processing device B.

As shown in FIG. 22, the sheet folding device C2 includes a first sheet reversing section 141, and the image forming device A2 includes a second sheet reversing section 142. As will be described below, the first sheet reversing section 141 is added to the sheet folding device C1 of the first embodiment, and the second sheet reversing section 142 is additionally provided to the image forming device A1 of the first embodiment. Has been done. Therefore, the configurations and functions of the sheet folding device C2 and the image forming device A2 other than the first and second sheet reversing portions 141 and 142 will be omitted. Further, since the sheet post-processing device B is the same as that of the first embodiment, the description thereof will be omitted.

[First sheet reversing part]
FIG. 23 schematically shows the entire configuration of the sheet folding device C2, and the first sheet reversing portion 141 is arranged on the downstream side of the folding roller pair 34 along the sheet carry-out path 43. The sheet folding device C2 further includes a pair of unloading rollers 143 at the sheet discharging port 32b at the downstream end of the sheet unloading path 43. In the figure, the additional folding mechanism 36 described with reference to FIG. 2 of the first embodiment is omitted for the sake of simplicity. When the additional folding mechanism is provided, it is preferable to provide it between the folding roller pair 34 and the first sheet reversing portion 141, or it can be arranged on the downstream side of the first sheet reversing portion 141.

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. As shown in FIG. 24, the actuator 149 is connected to the control unit 120 of the sheet folding device C2, 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 to be arranged. ..

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]
As shown in FIG. 22, a second sheet reversing portion 142 is arranged on the downstream side of the image forming portion 3 along the paper ejection path 12 in the apparatus housing 1 of the image forming apparatus A2. 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. 24 conceptually shows the control configuration of the sheet folding device C2 of the second embodiment. The sheet folding device C2 includes a control unit 120 including a control board including a CPU, similarly to the sheet folding device C1 of the first embodiment. In the control unit 120 of the second embodiment, in addition to the first to third detection sensors S1 to S3 described in the first embodiment, the fourth and fifth detection sensors S4 and S5 are added to the motors MT1 to MT5. Therefore, it differs from the control unit 120 of the first embodiment in that the reverse unloading roller drive motor MT5 and the actuator 149 are connected, and further, the folding operation setting unit 129 connected to the folding processing information acquisition unit 124 is provided. Other points are the same as those of the control unit 120 of the first embodiment, and thus the description thereof will be omitted.

As shown in FIG. 23, the fourth detection sensor S4 reverses the connection portion between the first branch path 145a and the second branch path 145b of the reversing path 145c along the reversing path 144 of the first sheet reversing unit 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 fourth and fifth detection sensors S4 and S5 are output to the control unit 120 in real time in the same manner as the detection results of the first to third detection sensors S1 to S3.

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.

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 A2, 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. Further, the folding processing operation referred to here may include reverse transfer of the sheet by the reverse unloading roller drive motor MT5 and actuator 149 of the first sheet inverting portion 141, and sheet transfer to the sheet post-processing device B by the unloading roller 143. it can. 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 A1 in real time.

[Processing operation of sheet folding device]
The folding operation of the sheet folding device C2 will be described below. The sheet folding device C2 is preset with 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. Further, in the folding process (Z folding) mode, as shown in FIG. 6B, one crease (for example, the first crease 202) is arranged closest to the downstream end (tip) 201 of the sheet SH in the sheet transport direction. 1-fold mode and 2nd fold mode in which one fold (for example, the second fold 203) is aligned with the upstream end (rear end) 204 of the sheet SH in the sheet transport direction as shown in FIG. 21 (b). And are set.

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 2, and if the folding process is performed, further whether it is the first folding mode or the second folding mode. Is determined, and one of the folding processing modes is selected and input in the input section of the setting panel D. The input of the folding process mode is stored in the main body control unit 121 of the image forming apparatus A2 as one of the sheet information of the sheet to be folded.

The entire processing operation in the sheet folding device C2 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 carrying path 41 and turns on (Y in step ST01), the control unit 120 of the sheet folding device C2 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 A2 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 C2 are included.

The control unit 120 of the second embodiment also acquires information on the basis weight of the sheet to be folded from the sheet information sent from the main body control unit 121 of the image forming apparatus A2. In another embodiment, the sheet folding device C2 itself can acquire the basis weight of the sheet carried in from the image forming device A2. For example, using a conventionally known detection technique, a sound wave having a predetermined frequency can be emitted toward the surface of a sheet, and the basis weight can be calculated from the intensity of the sound wave passing through the sheet. By providing such a detection mechanism, even a type of sheet that is not planned to be used can be dealt with immediately.

When the sheet information acquired from the main body control unit 121 of the image forming apparatus A2 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 A2 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 (N in step ST03), the process proceeds to step ST09 and there is no folding. Execute the process.

In the non-folding process of step ST09, the veneer 35 is arranged at the guide position (35') described in connection with FIGS. 2 and 3 in the first embodiment, and in this state, the resist roller pair 33 and the folding roller pair The 34 and the unloading roller pair 143 are rotationally driven. As a result, the sheet from the image forming apparatus A2 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. 26 to 30. 29 (a) to 29 (f) show a process of folding the sheet S carried into the sheet folding device C2 in the second folding mode, and FIGS. 30 (a) to 30 (f) show folding in the first folding mode. The processing process is shown in the order of each process.

[Folding operation setting process]
In the folding operation setting process, the control unit 120 is based on the information regarding the sheet size acquired from the image forming apparatus A2 in step ST02 of FIG. 25 and the information regarding 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, for example, according to the flowchart shown in FIG. 26, at the latest before the sheet is carried from the image forming apparatus A2 into the sheet folding apparatus C2 and the resist process is started.

First, in step ST04-1, it is determined whether or not the information regarding the folding processing mode from the image forming apparatus A2 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]
The resist treatment of the present embodiment is executed in the same manner as in the case of the first embodiment described with reference to FIG. 10, and the tips of the sheets carried into the sheet folding device C2 are aligned to form a sheet skew (oblique). To correct. Therefore, detailed description will be omitted.

[Fold loop processing]
The folding loop process of the present embodiment is also executed in the same manner as in the case of the first embodiment described with reference to FIG. 11, and a loop for forming a crease on the tip end side of the sheet is formed on the sheet. Hereinafter, the same parts as those in the first embodiment will be omitted with reference to FIGS. 29 and 30.

As shown in FIGS. 29 (a) and 30 (a), the control unit 120 simultaneously drives the resist roller drive motor MT1 and the folding roller drive motor MT2 to rotate the resist roller pair 33 and the folding roller pair 34. With the veneer 35 in the guide position, the sheet S is conveyed downstream along the central transfer path 42 of the transfer path 32. When the tip of the sheet S to be conveyed is detected by the second detection sensor S2 on the immediately upstream side of the folding roller pair 34, the control unit 120 moves the veneer 35 from the guide position to the retracted position. As a result, the central transport path 42 is opened to the lower loop forming space 50 through the gap 48, as shown in FIGS. 29 (b) and 30 (b). 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. The evacuation process of the veneer 35 is the same as that of the first embodiment described in relation to FIG. 12, so the description thereof will be omitted.

Next, the control unit 120 starts from the time when the second detection sensor S2 detects the tip of the sheet S, and drives the resist roller drive motor MT1 up to the first set transfer amount Pn set in the folding operation setting process. Then, the folding roller drive motor MT2 is stopped. As a result, the sheet S is held in a state where its tip side is nipped in the nip portion 39 of the folding roller pair 34 at a predetermined position.

In the case of the second folding mode, the first set transport amount Pn was set to the distance Ra = R + L / 4. Therefore, as shown in FIG. 29 (b), the sheet S is held at a position where its tip is advanced by a length L / 4 (FIG. 21) from the nip portion 39 of the folding roller pair 34 to the downstream side in the sheet transport direction. .. In the case of the first folding mode, the first set transport amount Pn was set to the distance Rc = R + ΔL. Therefore, as shown in FIG. 30 (b), the sheet S is held at a position where the tip thereof advances by a length ΔL (FIG. 6) from the nip portion 39 of the folding roller pair 34 to the downstream side in the sheet transport direction.

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, the portion of the sheet S on the upstream side of the folding roller pair 34 is curved and hangs down from the gap 48 in the loop forming space 50 in a loop shape, and a folding loop FL for forming a crease is formed on the sheet. .. The folding loop FL increases according to the amount of sheet conveyed by the resist roller pair 33.

In the second folding mode, since the tip of the sheet S also protrudes downstream 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. On the other hand, in the first folding mode, since the tip of the sheet S is only a little length ΔL and protrudes downstream from the nip portion 39 of the folding roller pair 34, the folding loop FL is the front end of the sheet S in the sheet conveying direction. Formed on the side.

[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 corresponding to the size and the folding processing mode is used for the sheet carried into the sheet folding device C2 in the folding operation setting processing.

After the folding roller drive motor MT2 in the immediately preceding folding loop process is stopped, the folding loop counter built in the control unit 120 starts counting, and when the count is increased to a predetermined loop count value, the crease forming process (step ST06) is executed. Will be done. The folding loop counter can also be operated to count down by subtracting from a predetermined loop count value to "0".

The crease forming process is executed according to, for example, the flowchart shown in FIG. 27. 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 in the sheet at a predetermined folding position by continuously feeding the sheet of the resist roller pair 33 described above.

The thrusting process is performed, for example, according to the procedure shown in the flowchart of FIG. 14, as in the case of the first embodiment. The control unit 120 drives the veneer drive motor MT3 in the forward direction and folds the veneer 35 while the sheet S is continuously sent from the resist roller pair 33 to the central transport path 42 by the drive of the resist roller drive motor MT1. Move horizontally to the 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. In the second folding mode, the tip of the sheet S protrudes downstream from the nip portion 39 by a length L / 4, so that the predetermined position of the sheet S is as shown in FIG. 29 (c). It is a position with a length of 3L / 4 from the tip of S in the sheet transport direction. In the first folding mode, the tip of the sheet S protrudes downstream from the nip portion 39 by the length ΔL, so that the predetermined position of the sheet S is the tip of the sheet S as shown in FIG. 30 (c). It is a position of length L / 2 + ΔL in the sheet transport direction.

As described in connection with FIG. 15 in the first embodiment, when the veneer 35 moves downstream on the central transport path 42, the sheet S has upper and lower sheet portions sandwiching the veneer 35. It is regulated from both the top and bottom by the upper transport guide 45 and the lower transport guide 46, respectively. 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. 29 (d) and 30 (d). , Temporarily folded into a bent form at the predetermined position.

The control unit 120 stops the veneer drive motor MT3 when the drive amount of the veneer drive motor MT3 reaches a preset second set drive amount. 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 ″, so that the seat S has the predetermined position as described above, as shown in FIGS. 29 (d) and 30 (d). It is carried to a position facing the nip portion 39 of the folding roller pair 34 in a bent form by the temporary folding. The predetermined position of the bent sheet S is pulled into the folding roller pair 34 and pressure-folded as described later. It is the first folding position FP1 that is bent and becomes the first crease of the folding sheet.

It should be noted that the control of the sheet transport speed of the resist roller pair 33 and the moving speed of the veneer 35 while the veneer 35 moves from the retracted position to the veneer position 35 ″ is as described in the first embodiment. The description will be omitted. Further, in the veneer processing, the timing of starting the movement from the retracted position of the veneer 35 is shifted depending on whether the paper type of the sheet is plain paper or thick paper or thin paper, thereby folding the sheet. The control for eliminating or reducing the misalignment of the folds formed in the above is also as described in the first embodiment, and thus the description thereof will be omitted.

After the veneer drive motor MT3 is stopped in the thrust process (step ST07-1), the resist roller drive motor MT1 is driven to a preset third set drive amount (Y in step ST07-2). The control unit 120 drives the folding roller drive motor MT2 (step ST07-3). The resist roller pair 33 continues to feed the seat S even after the veneer drive motor MT3 is stopped, so that the first folding position FP1 of the seat S reaches a position where it is caught in the nip portion 39 of the folding roller pair 34. Up to this point, the third set drive amount is set as the drive amount of the resist roller drive motor MT1 that rotates the resist roller pair 33.

When the folding roller pair 34 is rotated by the driving of the folding roller drive motor MT2 in step ST07-3, the first folding position FP1 of the sheet S is caught in the nip portion 39 of the folding roller pair 34 and is pressure-bent. As shown in FIGS. 29 (e) and 30 (e), the motor is transported to the downstream side. By the pressure processing of the folding roller pair 34, the first crease F1 (202) is formed on the sheet S at a predetermined folding position.

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. Further, the folded sheet is prevented from opening the folded portion of the sheet at the first crease, so that the appearance is improved.

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 veneer position 35 ″ to the retracted position (step ST07-4). The gap 48 is completely opened in the transport path 42, and the lower part thereof is opened to the loop forming space 50. Therefore, the folding loop FL is hindered by the veneer 35 from the start of driving the folding roller drive motor MT2. However, it can be smoothly wound into the nip portion 39 of the folding roller pair 34. Since this retracting process is performed in the same manner as described with respect to FIG. 12 in the first embodiment, further description is omitted. To do.

Since the folding roller pair 34 is continuously rotationally driven even after the veneer 35 is retracted, the sheet S is in a state of being overlapped in a tri-fold (Z-fold) with the tip thereof and the formed first fold F1 first. It is nipped into the folding roller pair 34 and conveyed to the downstream side along the sheet carry-out path 43. As the sheet S is conveyed in this way, the folding loop FL in the loop forming space 50 gradually becomes smaller, and as shown in FIGS. 29 (f) and 30 (f), the central transport path 42 said. 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, in the case of the second folding mode, as shown in FIG. 21B, the second fold 203 is formed at a position that coincides with the rear end 204 of the sheet S in the sheet transport direction. In the case of the first folding mode, as in the case of the first embodiment, as shown in FIG. 6B, the position where the second fold 203 has a length L / 2 + ΔL from the tip of the sheet S in the sheet conveying direction. Is formed in. Due to the pressure bending after the temporary folding described above, the second fold 203 is 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. 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.

[Delivery process]
The carry-out process is executed according to, for example, the flowchart shown in FIG. 28. 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 A2.

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 SH 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 vs. 34.

FIG. 31 (a) shows the sheet S1 which is image-formed by the image forming apparatus A2 and carried into the sheet folding apparatus C2 in the first folding mode, and FIG. 31 (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 A2, 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. 32 (a), 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. 32 (b), 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, 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 to the sheet aftertreatment device B by the unloading roller 143. ..

FIG. 33 (a) shows the folded sheet SH2 when the sheet S1 of FIG. 31 (a) carried in from the image forming apparatus A2 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, inverted by the first reversing section 141, and returned to the sheet carrying path 43, 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, for example, in the same manner as described with reference to FIG. 20 in the first embodiment. 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 the modified example of the second embodiment, the sheet image-formed by the image forming apparatus A2 is inverted by the second inversion unit 142 in a switchback manner, and then carried into the sheet folding processing apparatus C2. 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 C2.

FIG. 34A is a plan view of the sheet S2 which is carried into the sheet folding device C2 after the image is formed by the image forming apparatus A2 and then inverted by the second inversion unit 142 as described above. As can be clearly seen in comparison with the sheet S1 of FIG. 31A, 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 A2, and the front surface and the back surface are inverted.

FIG. 34B is a drawing of the folded sheet SH2 when the sheet S2 is Z-folded by the sheet folding device C2 in the second folding mode and conveyed from the folding roller pair 34, as viewed from above in the sheet conveying direction. .. FIG. 34 (c) shows the folded sheet SH2 when the folded sheet SH2 of FIG. 34 (b) is inverted by the first inversion section 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 A2 is Z-folded by the sheet folding apparatus C2 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. 31 (b), the sheet tip (204 of FIG. 34 (b)) and the second crease 203 coincide with the sheet transport direction, and move to the downstream side like the tab Tb described above. It is advantageous in that the protruding portion 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.

A1, A2 Image forming device B Sheet post-processing device C1, C2 Sheet folding device 31 Housing 32 Transport path 33 Resist roller vs. 34 Folding roller vs. 35 Thrust plate 38, 39 Nip part 41 Sheet carry-in path 42 Central transport path 43 Sheet carry-out path 45 Upper transport guide 45a First horizontal portion 45b Second horizontal portion 45c Inclined portion 46 Lower transport guide 46a First lower guide portion 46b Second lower guide portion 47 Convex portion 48 Gap 50 Loop forming space 51a First horizontal guide portion 51b 1st inclined guide part 52a 2nd horizontal guide part 52b 2nd inclined guide part 52c Vertical guide part 58-60 Drive mechanism 120 Control part 121 Main body control part 124 Folding processing information acquisition part 125 Sheet thickness information acquisition part 126 Size information acquisition Part 128 Fold loop counter 141 First reversing part 142 Second reversing part 143 Carrying out roller 144, 154 Reversing path 148,158 Reversing roller 201 Sheet tip 202 First crease 203 Second fold 204 Seat rear end

Claims (7)

A feed roller that is placed in the transport path and transports the sheet,
A pair of folding rollers arranged on the downstream side of the feed roller and niping a predetermined position of the sheet to form a crease.
A thrusting member that moves the predetermined position of the sheet to a thrusting position for niping the folding roller pair,
A control unit for controlling the operation of the feed roller, the folding roller pair, and the thrust member is provided.
The control unit
A sheet in which a loop is formed on the upstream side of the folding roller pair by the feed roller continuing to convey the sheet in a state where the folding roller pair nips and stops the sheet conveyed from the feed roller. The thrust member pushes and moves to the thrust position, and the folding roller pair conveys the sheet from the stopped state and nips the first position of the sheet to form a first crease. 1 fold and
After the first fold, the fold roller pair forms a second fold by niping the second position of the sheet on which the loop is formed so as to align with the rear end of the sheet. , Performs a sheet folding device. The sheet folding device according to claim 1, wherein the first position of the sheet is a length position of two-thirds of the sheet length from the predetermined nip position of the sheet to the rear end. A feed roller that is placed in the transport path and transports the sheet,
A pair of folding rollers arranged on the downstream side of the feed roller and niping a predetermined position of the sheet to form a crease.
A thrusting member that moves the predetermined position of the sheet to a thrusting position for niping the folding roller pair,
A control unit for controlling the operation of the feed roller, the folding roller pair, and the thrust member is provided.
The control unit
With the folding roller pair niping and stopping at a predetermined nip position of the sheet fed from the feed roller in the transport direction, the feed roller continues to transport the sheet to loop on the upstream side of the folding roller pair. The thrust member pushes the sheet on which the is formed to move to the thrust position, and the folding roller pair conveys the sheet from the stopped state and nips the first position of the sheet. The first fold that forms one crease and
The second fold forming the second fold by the folding roller pair niping the second position of the sheet on which the loop is formed by conveying the sheet after the first fold. And
The control unit has a first folding mode in which the predetermined nip position of the sheet is set to the first nip position near the tip of the sheet in the first folding, and the predetermined nip position of the sheet is the first. It is possible to select the second folding mode set to the second nip position on the rear end side of the seat from the nip position of 1, and in the second folding mode, the second position of the seat is set to the rear end of the seat. A sheet folding device that performs the second folding by aligning and niping. The folding roller pair performs the first folding by superimposing the first position of the sheet pushed to the thrusting position by the thrusting member with the predetermined nip position and niping the sheet. The sheet folding device according to any one of claims 1 to 3, wherein the second position is overlapped with the rear end of the sheet and niped to perform the second folding. The sheet folding device according to any one of claims 1 to 4, further comprising a switchback reversing portion that reverses the front and back and the front and back of the sheet transported from the folding roller pair to the downstream side in the transport direction. The sheet folding device according to any one of claims 1 to 4, further comprising a switchback reversing portion that reverses the front and back and the front and back of the sheet carried into the feed roller in the transport direction. The sheet folding device according to any one of claims 1 to 6,
An image forming apparatus including an image forming unit that has a switchback reversing portion that inverts the front and back and front and back sides of a sheet carried into the sheet folding device in a conveying direction, and forms an image on the sheet.

Images