JP2020111423A - Sheet folding apparatus and image formation system - Google Patents

Abstract

To form a good fold that is not thick without increasing the size and cost of an apparatus and without causing a crease or a wrinkle on a sheet.SOLUTION: When performing reciprocation operation that puts in and out at or in the vicinity of folds A1 to A5 to nips of pairs of fold rollers 55 and 56 by rotatably driving the fold rollers 55 and 56 in which the folds A1 to A5 are formed after forming all of the desired number of folds A1 to A5 are formed on a sheet P alternating in forward and backward directions, and when the reciprocation operation is performed to the nips of the pairs of fold rollers 55 and 56, the reciprocation operation to the nips of the pair of fold rollers 56 forming the fold A5 of a last fold surface C6 among the pairs of fold rollers 55 and 56 is first performed based on a discrimination result by a control unit 80 (discrimination means).SELECTED DRAWING: Figure 4

Description

The present invention relates to a sheet folding apparatus that performs folding processing on a sheet, and an image forming system such as a copying machine, a printer, a facsimile, or a composite machine thereof.

2. Description of the Related Art Conventionally, a sheet folding apparatus that is a post-processing apparatus connected to an image forming apparatus such as a copying machine or a printer and that forms a plurality of folds on a sheet is widely known (for example, see Patent Document 1). ).

Specifically, the sheet folding apparatus in Patent Document 1 is configured to convey a sheet downward, and a pair of folding rollers configured to convey the sheet in the forward and reverse directions of the horizontal direction below the pair of conveying rollers. And a pair of movable guide members (deflecting means) that guide the sheet conveyed by the pair of conveying rollers toward one of the nips of the pair of folding rollers. Then, the sheet conveyed by the pair of conveying rollers is conveyed while being guided toward the one folding roller pair by the pair of movable guide members, or while being guided toward the other folding roller pair. A plurality of fold lines are formed by the pair of folding rollers, and the bellows are folded.

On the other hand, in Patent Document 2, in a sheet folding apparatus that forms a fold line at one position of a sheet, in order to reinforce the fold line, a pair of folding rollers holding the fold line at a nip is rotated forward and backward to reciprocate the sheet. Techniques for doing so are disclosed. Further, in Patent Document 2, for the purpose of strengthening the fold formed on the sheet, a technique of further pressing the fold formed by the folding roller pair by the second folding roller pair, and forming the fold by the folding roller pair A technique of stopping the rotation drive of the pair of folding rollers is disclosed.

The conventional sheet folding apparatus may not be able to form a good crease on the sheet because it is not thick.
In order to solve such a problem, it is conceivable to apply the technology of Patent Document 2 to reciprocally move the folds formed on the sheet by the pair of folding rollers at the nip of the pair of folding rollers. However, in that case, there is a possibility that blind spots may occur at the rear end of the sheet or wrinkles may occur at the sheet. Further, by applying the technique of Patent Document 2, in addition to a pair of folding rollers that form a fold on a sheet, a pair of folding rollers that further presses the fold formed on the sheet by the pair of folding rollers is further provided. A policy to set it up can be considered. However, if such a pair of folding rollers is further provided, the device becomes large and the cost becomes high.

The present invention has been made to solve the above-mentioned problems, and does not increase the size and cost of the apparatus, does not cause creases or wrinkles on the sheet, and forms good folds that are not bulky. It is to provide a sheet folding device and an image forming system which can be performed.

The sheet folding apparatus according to the present invention includes a pair of folding rollers that respectively form folds on the sheet, and a plurality of folds that are sequentially formed on the sheet by sequentially forming the folds on the sheet by alternately using the pair of folding rollers. A fold of the final fold that is formed last among the two folds, and a deciding means for deciding which fold of the pair of fold rollers is to be formed. After all of the folds are formed on the sheet, a reciprocating operation is performed in which the folding roller pairs having the folds are alternately driven in the forward and reverse directions to move the folds or the vicinity thereof into and out of the nip of the folding roller pairs. When the reciprocating operation is performed with respect to the nip of the pair of folding roller pairs, the final folding surface of the pair of folding roller pairs of the pair of folding roller pairs is determined based on the determination result by the determining unit. The reciprocating operation with respect to the nip of the pair of folding rollers having the fold is first performed.

Advantageous Effects of Invention According to the present invention, a sheet folding device and an image forming apparatus capable of forming a good crease that is not bulky on a sheet without increasing the size and cost of the device and without causing creases or wrinkles A system can be provided.

1 is an overall configuration diagram showing an image forming system according to an embodiment of the present invention. It is a block diagram which shows the principal part of a sheet folding device. It is a figure showing an example of operation of a sheet folding device at the time of folding processing. It is a figure which shows operation|movement following FIG. FIG. 4 is a diagram showing an operation different from that of FIG. 4 following FIG. 3. (A) A schematic view showing a state where the fold line on the final folding surface is located on the side of the second folding roller pair, and (B) A schematic diagram showing a state where the fold line on the final folding surface is located on the side of the first folding roller pair. And, It is a flow chart which shows control in a sheet folding device. It is a flowchart following FIG. 9 is a flowchart following FIG. 8. It is a flowchart following FIG. 7-FIG. FIG. 4A is a schematic view showing a state in which a blind spot is generated on the rear end of the sheet, and FIG. 6B is a schematic diagram showing a state in which wrinkles are generated on the final sheet surface. In a sheet folding apparatus as a modified example 1, (A) a schematic view showing a state where the length of the final sheet surface is shorter than a first predetermined value, and (B) a length of the final sheet surface is shorter than a second predetermined value. 3 is a schematic view showing a long state. It is a figure which shows operation|movement of the sheet folding apparatus as a modified example 2. FIG. 11 is a diagram showing a reciprocating operation performed by a sheet folding device as a third modification. FIG. 11 is a table showing settings of reciprocating operation performed by a sheet folding apparatus as a modified example 4.

Hereinafter, modes for carrying out the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and the duplicated description thereof will be appropriately simplified or omitted.

First, the overall configuration and operation of the image forming system 100 will be described with reference to FIG.
In the present embodiment, the sheet folding apparatus 50 is detachably installed in the image forming apparatus 1 and constitutes one image forming system 100 together with the image forming apparatus 1.

In FIG. 1, reference numeral 1 is a digital multi-function peripheral as an image forming apparatus having a copying function and a printer function, 2 is a document transporting table on which a document is transported, 3 is a document reading unit for optically reading image information of the document, 4 Denotes an exposure unit that irradiates the photosensitive drum 5 with exposure light based on the image information read by the document reading unit 3.
Further, 5 is a photosensitive drum 5 (image forming unit) on which a toner image (image) is formed, 10 is a feeding unit in which a sheet P such as paper is stored in a roll shape, and 20 is an unfixed image on the sheet P. A fixing device 30 for fixing the image forming apparatus 100 is an operation panel for displaying various information and inputting operation conditions in the image forming system 100.
In the present embodiment, the image forming apparatus 1 is configured such that a roll-shaped sheet P (roll paper) is cut by the feeding unit 10 to have a desired length, and a plurality of large sheets such as A0 and A1 sizes. An image can be formed on a sheet P of a size.

Further, in FIG. 1, reference numeral 50 denotes a sheet folding device (post-processing device) that performs a folding process as a post-process on the sheet P discharged and carried in from the image forming apparatus 1.
Further, 51 is a pair of conveying rollers for conveying the sheet P, 53, 54 are a pair of movable guide members for guiding the sheet P conveyed by the conveying roller pair 51 toward the pair of folding rollers 55, 56, and 55, 56 are sheets. A pair of folding rollers forming a fold line at P are shown.
Further, 67 is a pair of discharge rollers for discharging the sheet P to the outside of the apparatus, 68 is a discharge tray on which the sheet P is discharged and stacked, and 90 is a sheet feeding section for manual feeding.

An operation of the image forming system 100 during normal image formation will be described with reference to FIG.
When the image forming apparatus 1 is used as a copying machine, first, when a document is placed on the document transport table 2, the document is transported by the transport rollers and passes over the document reading unit 3. At this time, the document reading unit 3 optically reads the image information of the document passing above. At this time, the size of the document is also detected.
Then, the optical image information read by the document reading unit 3 is converted into an electric signal and then transmitted to the exposure unit 4 (writing unit). Then, the exposure unit 4 emits exposure light (laser light) based on the image information of the electric signal toward the surface of the photosensitive drum 5 of the image forming unit.
When the image forming apparatus 1 is used as a printer, image information is input to the exposure unit 4 from an external terminal such as a personal computer and is directed from the exposure unit 4 to the surface of the photosensitive drum 5 based on the image information. Exposure light is emitted.

On the other hand, in the image forming unit, the photoconductor drum 5 is rotated counterclockwise in FIG. 1, and the surface of the photoconductor drum 5 is subjected to a predetermined image forming process (charging process, exposing process, developing process). An image (toner image) corresponding to the image information is formed.
After that, the image formed on the photosensitive drum 5 is transferred onto the sheet P conveyed by the registration rollers at the transfer portion.

On the other hand, the sheet P conveyed to the position of the photoconductor drum 5 operates as follows.
First, one of the plurality of feeding units 10 of the image forming apparatus 1 is automatically or manually selected.
Then, the sheet P wound around the feeding unit 10 in a roll shape is cut according to the size of the document (or image information input from an external terminal), and the sheet P is conveyed to the conveyance path K0. ..
Then, the sheet P passes through the transport path K0 and reaches the position of the registration roller. Then, the sheet P that has reached the position of the registration roller is conveyed at the same timing so as to be aligned with the image formed on the photosensitive drum 5.
Then, the sheet P after the transfer process reaches the fixing device 20 via the transport path after passing through the position of the photoconductor drum 5 (transfer portion). Then, the image on the sheet P is thermally fixed by the fixing device 20. Then, the sheet P having the image fixed thereon is ejected from the image forming apparatus 1.

Here, in the present embodiment, the sheet folding device 50 is installed in the image forming apparatus 1. Then, the sheet P discharged from the image forming apparatus 1 is conveyed to the sheet folding apparatus 50, and the conveyed sheet P is folded.
Specifically, referring to FIG. 1, first, the sheet P conveyed from the image forming apparatus 1 to the sheet folding apparatus 50 passes through the first and second conveyance paths K1 and K2, and the position of the conveyance roller pair 51 is reached. Reach Then, the sheet P is transported by the transport roller pair 51 and guided by the pair of movable guide members 53, 54 toward the one folding roller pair 55 or the other folding roller pair 56. To do. Then, the sheet P is subjected to folding processing such as bellows folding by the pair of folding rollers 55 and 56. Then, the folded sheet P is discharged outside the apparatus by the discharge roller pair 67 and is stacked on the discharge tray 68.
The sheet folding device 50 will be described later in more detail with reference to FIGS.

Here, the sheet folding unit 50 according to the present embodiment is provided with a sheet feeding unit 90 for manual feeding. Then, when it is desired to directly perform the folding process on the sheet P without using the image forming apparatus 1, the sheet P is set in the manual sheet feeding unit 90. The sheet P set in the manual sheet feeding unit 90 is conveyed into the sheet folding device 50 via the third conveying path K7. Then, in the sheet folding device 50, the folding process is performed on the sheet P in the same manner as described above.

Hereinafter, the characteristic configuration and operation of the sheet folding apparatus 50 according to the present embodiment will be described in detail.
Referring to FIG. 2, the sheet folding device 50 includes a conveyance roller pair 51, a pair of folding roller pairs 55 and 56, a pair of movable guide members 53 and 54, a conveyance guide plate 57, and a sheet detection sensor 61. ~ 63, etc. are installed.

The conveyance roller pair 51 conveys the sheet P toward the folding roller pairs 55 and 56.
More specifically, the conveying roller pair 51 is formed by a driving roller and a driven roller in pressure contact with each other to form a nip, and is rotationally driven in a direction indicated by an arrow in FIG. 2 by a conveying motor 91 as a first driving unit. As a result, the sheet P nipped by the nip of the pair of transport rollers 51 is transported downward in the substantially vertical direction in FIG.

Each of the pair of folding rollers 55 and 56 functions as a folding processing unit that forms a fold line on the sheet P.
More specifically, the pair of folding rollers 55, 56 is a virtual tangent line passing through the nip of the transport roller pair 51 arranged on the upstream side thereof (a virtual tangent line extending in a substantially vertical direction along the transport direction indicated by a dashed arrow in FIG. 2). It is arranged so as to straddle each line. Specifically, the first folding roller pair 55 is arranged on the left side of FIG. 2 with respect to the above virtual tangent line, and the second folding roller pair 56 is arranged on the right side of FIG. 2 with respect to the above virtual tangent line. Has been done.
Further, the pair of folding rollers 55 and 56 are formed so that the sheet P can be conveyed in the forward and reverse directions therebetween. Specifically, both the virtual tangent line passing through the nip of the first folding roller pair 55 and the virtual tangent line passing through the nip of the second folding roller pair 56 are virtual lines extending in a substantially horizontal direction, and should be coincident with each other. It is configured. Then, as shown in FIGS. 3B and 3D, the pair of folding rollers 55 and 56 rotate in the same direction, so that the sheet P is fed between the two folding roller pairs 55 and 56. It may be conveyed in the direction (left side of FIG. 2) or in the opposite direction (right side of FIG. 2 ).

The pair of folding rollers 55 and 56 are an upper roller (following roller) arranged near the conveying roller pair 51 and a lower roller (driving roller) arranged farther from the conveying roller pair 51, respectively. And are pressed to form a nip.
Then, in the state where the sheet P is folded back, it is conveyed to the nip of the pair of folding rollers 55 and 56, and the fold A is formed in the folded portion of the sheet P by the pressure in the nip.

Further, the pair of folding rollers 55 and 56 are configured to be separately driven to rotate by being driven by the drive motors 94 and 95 as the third drive means. Specifically, the first driving motor 94 rotationally drives the first folding roller pair 55, and the second driving motor 95 rotationally drives the second folding roller pair 56. The two drive motors 94 and 95 are both forward/reverse bidirectional rotation type motors, and are rotated in the forward direction under the control of the control unit 80 to rotate the folding roller pair 55, 56 in the forward direction. The pair of folding rollers 55 and 56 is rotated in the opposite direction by rotating in the opposite direction under the control of the control unit 80.
Further, in the present embodiment, in order to improve the transportability of the sheet P between the two folding roller pairs 55 and 56, the transport guide plate 57 is installed so as to face the lower surface of the sheet P.
In the present embodiment, the two drive motors 94 and 95 rotate the two folding roller pairs 55 and 56 separately, but one drive motor (driving mechanism) drives the two folding rollers. The pair 55, 56 may be configured to be integrally driven to rotate.

Here, in the present embodiment, the sheet P transported by the transport roller pair 51 is guided toward one of the pair of folding rollers 55 toward the other folding roller pair 56 or toward the other folding roller pair 56. There is provided a pair of movable guide members 53 and 54 that guides each other.
The pair of movable guide members (the first movable guide member 53 and the second movable guide member 54) form a nip between the transport roller pair 51 in the transport path from the transport roller pair 51 to the folding roller pairs 55 and 56. They are arranged so as to straddle a virtual tangent line (a virtual line extending in the substantially vertical direction described above) that passes therethrough, and are configured to be individually movable in the vertical direction. Specifically, the first movable guide member 53 is arranged on the right side of FIG. 2 with respect to the above-mentioned virtual tangent line, and the second movable guide member 54 is arranged on the left side of FIG. 2 with respect to the above-mentioned virtual tangent line. Has been done. The first movable guide member 53 and the second movable guide member 54 are both formed in a substantially arcuate shape and are line symmetrical (symmetrical) with respect to the above-mentioned virtual tangent line.

In addition, referring to FIG. 2, the first and second movable guide members 53 and 54 are configured to be separately rotated by first and second moving mechanisms 92 and 93 as second driving means. ing.
Specifically, the first moving mechanism 92 rotates the rotation shaft of the first movable guide member 53 clockwise or counterclockwise to move the guide shaft 53a of the first movable guide member 53 along the guide rail. By doing so, the first movable guide member 53 is moved up and down. Then, the first moving mechanism 92 is driven in the forward and reverse directions by the control of the control unit 80, so that the first movable guide member 53 moves to the reference position shown in FIG. 2 and FIG. It will move to the guide position shown in FIG.
Similarly, the second moving mechanism 93 rotates the rotating shaft of the second movable guide member 54 clockwise or counterclockwise to move the guide shaft 54a of the second movable guide member 54 along the guide rail. Thus, the second movable guide member 54 is moved up and down. Then, the second moving mechanism 93 is driven in the forward and reverse directions by the control of the control unit 80, whereby the second movable guide member 54 moves to the reference position shown in FIG. 2, FIG. It will move to the guide position shown in FIG.
A guide that guides the sheet P toward the nip of the first folding roller pair 55 by moving the first and second movable guide members 53 and 54 to the guide positions shown in FIG. It will function as a member. A guide that guides the sheet P toward the nip of the second folding roller pair 56 by moving and stopping the first and second movable guide members 53 and 54 to the guide positions shown in FIG. 3B and the like. It will function as a member.
The moving mechanisms 92 and 93 for moving the pair of movable guide members 53 and 54 up and down are not limited to those described above, and various forms can be used.

Here, as shown in FIG. 2, three sheet detection sensors 61 to 63 are installed in the sheet folding apparatus 50 in the present embodiment. Each of these sheet detection sensors 61 to 63 is a reflective photosensor including a light emitting element and a light receiving element, and optically detects whether or not the sheet P is present at that position.
Specifically, the first sheet detection sensor 61 is arranged on the upstream side in the transport direction with respect to the nip of the transport roller pair 51. The second sheet detection sensor 62 is disposed on the side away from the second folding roller pair 56 (the left side in FIG. 2) with respect to the nip of the first folding roller pair 55. The third sheet detection sensor 63 is arranged on the side away from the first folding roller pair 55 (the right side in FIG. 2) with respect to the nip of the second folding roller pair 56.

Then, the first sheet detection sensor 61, the second sheet detection sensor 62, and the third sheet detection sensor 63 detect the leading edge, the trailing edge, and the fold of the sheet P, respectively, and the timer 81 waits for a time after they are detected. The conveyance motor 91, the first and second moving mechanisms 92 and 93, and the first and second drive motors 94 and 95 are individually controlled at the target operation timing while measuring the Has been given.
In this way, by controlling the motors 91 to 94 by the control unit 80 based on the detection results of the three sheet detection sensors 61 to 63, desired folds can be formed on the sheet P with high accuracy.
The specific folding processing operation will be described later in more detail with reference to the operation diagrams of FIGS. 3 to 5 and the flowcharts of FIGS. 7 to 10.

Here, in the present embodiment, the control unit 80 sequentially forms the fold lines A1 to A5 (see FIG. 6A and the like) on the sheet P by alternately using the pair of folding roller pairs 55 and 56. Of the plurality of folding surfaces C1 to C6 sequentially formed on P (see FIG. 6A, etc.), the fold A5 of the final folding surface C6 that is formed last is one of the pair of folding rollers 55, 56. It also functions as a determination unit that determines whether a pair of folding rollers is used. In other words, the control unit 80 (determination means) determines the orientation (posture) of the final folded surface.

For example, as shown in FIG. 6(A), when the sheet P is subjected to bellows folding to form five folds A1 to A5, first, the first fold A1 between the first fold surface C1 and the second fold surface C2 is The second folding roller pair 56 forms the second folding line C2 of the second folding surface C2 and the third folding surface C3, and the second folding line C2 forms the second folding line A2. The third fold A3 with the fourth fold surface C4 is formed by the second folding roller pair 56, and then the fourth fold A4 with the fourth fold surface C4 and the fifth fold surface C5 is formed by the first fold roller pair 55. After being formed, the fifth folding line A5 of the fifth folding face C5 and the sixth folding face C6 (final folding face) is finally formed by the second folding roller pair 56. In such a case, the control section 80 (determination means) determines that the fold line A5 of the final folding surface C6 is formed by the second folding roller pair 56.
Further, as shown in FIG. 6B, when the sheet P is subjected to bellows folding to form four folds A1 to A4, first, the first fold A1 between the first fold surface C1 and the second fold surface C2 is The second folding roller pair 56 forms the second folding line C2 of the second folding surface C2 and the third folding surface C3, and the second folding line C2 forms the second folding line A2. The third fold A3 with the fourth fold surface C4 is formed by the second folding roller pair 56, and finally the fourth fold A4 with the fourth fold surface C4 and the fifth fold surface C5 (final fold surface) is the first. It is formed by the pair of folding rollers 55. In such a case, the control section 80 (determination means) determines that the fold A4 of the final folding surface C5 is formed by the first folding roller pair 55.

As the discriminating means for discriminating the pair of folding rollers forming the fold line on the final folding surface in this manner, a unit based on the sheet length detected by the first sheet detection sensor 61 can be used. Specifically, the first sheet detection sensor 61 optically detects the sheet front end and the sheet rear end B of the sheet P, and the control unit 80 determines the length of the sheet P based on the detection time and the conveyance speed of the sheet P. The length (length in the carrying direction) is calculated to determine which pair of folding rollers forms the fold on the final folding surface. In such a case, in addition to the control unit 80, the first sheet detection sensor 61 functions as a discriminating means.
Note that the determination unit is not limited to such one, and, for example, based on the information relating to the folding process input by the user to the operation panel 30 (see FIG. 1), the fold on the final folding surface can be determined. It is also possible to determine whether it is formed by a pair of folding rollers.

Here, in the present embodiment, after the desired number of folds A1 to A5 are all formed on the sheet P, the folding roller pairs 55 and 56 having the folds A1 to A5 formed thereon are alternately rotationally driven in the forward and reverse directions. , A reciprocating operation (reciprocating mode) of moving the folds A1 to A5 or the vicinity thereof into and out of the nip of the pair of folding rollers 55 and 56 is performed.
Specifically, in the example of FIG. 6A, the first fold line A1, the third fold line A3, and the fifth fold line A5 (or the vicinity thereof) move in and out of the nip of the second folding roller pair 56. , The second folding roller pair 56 is alternately driven in the forward and reverse directions to reciprocate the sheet P in the left-right direction in FIG. 6(A). Furthermore, after the sheet P is moved to the first folding roller pair 55 side, the second folding line A2 and the fourth folding line A4 (or their vicinity) move in and out of the nip of the first folding roller pair 55, The first folding roller pair 55 is alternately rotationally driven in the forward and reverse directions to reciprocate the sheet P in the left-right direction in FIG.
By alternately reciprocating the fold line (or the vicinity thereof) to the upstream and downstream sides of the nip in this manner, a firm fold line is formed. That is, not a thick fold, but a thin fold and a good fold is formed. Further, since such a fold can be strengthened without providing an auxiliary folding processing means different from the pair of folding rollers 55 and 56, the apparatus does not become large and the cost is not increased.
It should be noted that such strengthening of the folds can be achieved even if the folds are not completely put in and out of the nip, but if a portion of the sheet near the folds is put in and out of the nip.

In the present embodiment, when such a reciprocating operation (reciprocating mode) is performed, and when a reciprocating operation (reciprocating mode) is performed on the nip of the pair of folding rollers 55 and 56, respectively. In addition, based on the discrimination result by the control unit 80 (discrimination means) described above, the reciprocating operation (reciprocating mode) of the pair of folding rollers 55 and 56, which has the fold on the final folding surface, with respect to the nip. ) Is controlled so that it is performed first.
Therefore, in the example of FIG. 6A described above, first, three folds A1, A3, A5 (or, with respect to the nip of the second folding roller pair 56 in which the fold A5 of the final folding surface C6 is formed). A first reciprocating operation for moving the two folds A2, A4 (or the vicinity thereof) into and out of the nip of the first folding roller pair 55 is performed. Will be done.
On the other hand, in the example of FIG. 6(B), first, two folds A2, A4 (or their vicinity) with respect to the nip of the first folding roller pair 55 in which the fold A4 of the final folding surface C5 is formed. A first reciprocating operation for taking in and out of the second folding roller pair 56, and then a second reciprocating operation for taking in and out two folds A1, A3 (or their vicinity) with respect to the nip of the second folding roller pair 56. become.

By changing the order in which the reciprocating operation is performed in accordance with the direction of the fold of the final folding surface in this manner, it is possible to reduce the problem that the sheet rear edge B has a blind spot and the final folding surface C6 of the sheet P has wrinkles. To be done.
Specifically, as shown in FIG. 11A, the reciprocating operation of the second folding roller pair 56 having the fold line A5 of the final folding surface C6 with respect to the nip is not performed first, but the first folding roller on the opposite side is performed. When the reciprocating operation with respect to the nip of the pair 55 is first performed, the right fold lines A1, A3, and A5 are not reinforced and the final folding surface C6 is unstable and the sheet P is in a floating state. When the sheet is moved to 55, the sheet rear end B of the final folding surface C6 does not fit into the nip of the first folding roller pair 55, so that the sheet is easily scraped. Further, as shown in FIG. 11B, the final folding surface C6 in an unstable and floating state is reciprocally moved upstream and downstream of the nip of the first folding roller pair 55, so that the final folding surface C6 is smooth. Wrinkles tend to occur without moving back and forth.
On the other hand, in the present embodiment, the reciprocating operation is first performed from the side of the folding roller pair 56 on which the fold A5 of the final folding surface C6 is formed, and the final folding surface C6 is in close contact with the lower folding surface. Since the reciprocating operation is performed on the side of the folding roller pair 55 on the opposite side, the occurrence of such a problem can be reduced.

In the example of FIG. 6, when the length of the folding surface of the sheet P (the length in the transport direction) is longer than the distance between the nips of the pair of folding rollers 55 and 56 (the sheet P is in both nips). The case where the reciprocating operation is performed in the state where the sheet P is sandwiched is described above. However, even when the length of the folding surface of the sheet P is short with respect to the distance between the nips, the same is repeated twice. The divided reciprocating motion can be performed. In that case, in order to smoothly transfer (convey) the sheet P between the nips of the pair of folding rollers 55 and 56, it is preferable to install a conveyor belt on the conveyor path between the two nips.
When the length of the folding surface of the sheet P is equal to the distance between the nips of the pair of folding rollers 55 and 56, the reciprocating operation with respect to the fold is performed on the side of the one folding roller pair 56. During this time, the second reciprocating operation can be omitted because the reciprocating operation with respect to the fold is also performed on the other folding roller pair 55 side.

Hereinafter, with reference to FIGS. 3A to 3F and FIGS. 4A to 4F, folding to form five folds A1 to A5 (see FIG. 6A) on the long sheet P. The operation of the sheet folding device 50 when performing the processing (bellows folding) will be described in detail.
Further, by using FIGS. 3A to 3F and FIGS. 5A to 5F, folding in which four folds A1 to A4 (see FIG. 6B) are formed on the long sheet P. The operation of the sheet folding device 50 when performing the processing (bellows folding) will be described in detail.
Since the folding process performed by the sheet folding apparatus 50 according to the present embodiment is executed based on the control flow shown in FIGS. 7 to 10, FIGS. 3(A) to 3(F) and 4(A). ~(F) (or Fig. 5(A) to (F)), the relationship with steps S1 to S39 in the control flows of Figs. 7 to 10 will be shown as appropriate. ..

First, when the leading edge of the sheet P is detected by the first sheet detection sensor 61 installed in the vicinity of the nip entrance of the conveyance roller pair 51 (FIG. 7: Step S1), the conveyance motor 91 is turned on and the conveyance roller pair 51 moves. It is rotationally driven (FIG. 7: step S2). Then, the first drive motor 94 is turned on and the first folding roller pair 55 is rotationally driven in the forward direction (FIG. 7: step S3). Furthermore, after the time T1 has elapsed since the first sheet detection sensor 61 was turned on, the first moving mechanism 92 is turned on to move the first movable guide member 53 from the reference position to the guide position (FIG. 7: step S4). , S5). In this way, as shown in FIG. 3A, the sheet P conveyed by the conveying roller pair 51 is guided to the nip of the first folding roller pair 55 by the first movable guide member 53. ..
Then, after the first movable guide member 53 is returned to the reference position (FIG. 7: step S6) and the time T2 (>T1) has elapsed after the first sheet detection sensor 61 was turned on, the first drive motor 94 is turned on. It is turned off to stop the rotation of the first folding roller pair 55 (FIG. 7: Step S7).
After that, as shown in FIG. 3B, the first and second drive motors 94 and 95 are turned on, and the first and second folding roller pairs 55 and 56 are rotationally driven in the opposite directions (FIG. 7: Step S8). Also, after the time T3 (>T2) has elapsed since the first sheet detection sensor 61 was turned on, the second moving mechanism 93 is turned on and the second movable guide member 54 is moved from the reference position to the guide position ( (FIG. 7: Steps S9 and S10). As a result, as shown in FIG. 3B, the sheet P is conveyed to the conveying roller pair 51 and the first folding roller pair 55 while the second folding guide member 54 is being formed in a state where the folded portion is lightly formed. Will be guided to the nip of the second folding roller pair 56.
Then, as shown in FIG. 3C, when the head of the sheet P (the portion where the lightly folded portion is formed) reaches the nip of the second folding roller pair 56, the pressure of the nip causes a firm fold A1. The (first fold) is formed. After that, the second movable guide member 54 is returned from the guide position to the reference position (FIG. 7: Step S11), and it is determined whether there is the next folding process (whether to form the second fold) (FIG. 7: Step S12).
In the operation example of FIG. 3, since it is set to form the second fold line A2, the control after step S13 of FIG. 8 is performed, but the next fold line is not formed at step S12 of FIG. When it is determined that the sheet P is discharged, the sheet P is discharged toward the discharge tray 68 after the control (reciprocating mode) after step S27 in FIG. 10 is performed. The control flow of FIG. 10 will be described later.

After that, referring to FIG. 3C, after the time T5 has elapsed since the fold line A1 of the sheet P was detected by the third sheet detection sensor 63, the rotation of the folding roller pair 55, 56 by the drive motors 94, 95. The driving is stopped (FIG. 8: steps S13 and S14).
Thereafter, as shown in FIG. 3D, the drive motors 94 and 95 are turned on, and the pair of folding rollers 55 and 56 are rotationally driven in the forward direction (FIG. 8: step S15). In addition, the first movable guide member 53 is moved from the reference position to the guide position after a time T6 (>T5) has elapsed since the third sheet detection sensor 63 was turned on (FIG. 8: steps S16 and S17). As a result, the sheet P is guided by the first movable guide member 53 and is nipped by the first folding roller pair 55 while being conveyed to the conveyance roller pair 51 and the folding roller pair 56 in a state where the folded portion is lightly formed. Will be headed for. Then, as shown in FIG. 3D, when the head of the sheet P (the portion where the lightly folded portion is formed) reaches the nip of the first folding roller pair 55, the pressure of the nip causes a firm fold A2. (Second fold) will be formed. After that, the first movable guide member 53 is returned from the guide position to the reference position (FIG. 8: step S18), and it is determined whether there is the next folding process (whether to form the third fold) (FIG. 8: Step S19).
In the operation example of FIG. 3, since it is set to form the third fold line A3, the control after step S20 of FIG. 9 is performed, but the next fold line is not formed at step S19 of FIG. When it is determined that the sheet P is discharged, the sheet P is discharged toward the discharge tray 68 after the control (reciprocating mode) after step S27 in FIG. 10 is performed.

After that, referring to FIG. 3D, after a time T7 has elapsed since the second fold line A2 of the sheet P was detected by the second sheet detection sensor 62, the pair of folding rollers 55, 56 by the drive motors 94, 95. The rotation drive of is stopped (FIG. 9: steps S20 and S21).
Thereafter, as shown in FIG. 3E, the drive motors 94 and 95 are turned on, and the folding roller pair 55 and 56 are rotationally driven in the opposite direction (FIG. 9: step S22). In addition, after the time T8 (>T7) has elapsed since the second sheet detection sensor 62 was turned on, the second movable guide member 54 is moved from the reference position to the guide position (FIG. 9: steps S23 and S24). As a result, the sheet P is guided by the second movable guide member 54 and is nipped by the second folding roller pair 56 while being conveyed to the conveyance roller pair 51 and the folding roller pair 55 in a state where the folded portion is lightly formed. Will be headed for. Then, as shown in FIG. 3(E), when the leading edge (the portion where the lightly folded portion is formed) of the sheet P reaches the nip of the second folding roller pair 56, a firm fold A3 (third fold) is formed. Will be formed. After that, the second movable guide member 54 is returned from the guide position to the reference position (FIG. 9: step S25), and it is determined whether there is the next folding process (whether to form the fourth fold) (FIG. 9:). Step S26).
In the operation example of FIG. 3, since it is set to form the fourth fold line A4, the control after step S13 of FIG. 8 is performed again, but the next fold line is formed at step S26 of FIG. When it is determined that the sheet P is not to be discharged, the sheet P is discharged toward the discharge tray 68 after the control (reciprocating mode) after step S27 in FIG. 10 is performed.

After that, as shown in FIG. 3F, the fourth fold line A4 is formed on the sheet P (FIG. 8: Steps S13 to S18). Then, it is determined whether there is the next folding process (whether to form the fifth fold) (FIG. 8: step S19).
In the operation examples of FIGS. 3 and 4, since the fifth fold line A5 is set, the control after step S20 of FIG. 9 is performed, but the next fold line of step S19 of FIG. 8 is performed. If it is determined that the sheet P is not formed, the sheet P is discharged toward the discharge tray 68 after the control (reciprocating mode) after step S27 in FIG. 10 is performed.

Thereafter, as shown in FIG. 4A, the fifth fold line A5 is formed on the sheet P (FIG. 9: Steps S20 to S25). Then, it is determined whether or not there is the next folding process (whether to form the sixth fold) (FIG. 9: step S26).
In the operation example of FIGS. 3 and 4, since the sixth fold is set not to be formed, the control after step S27 of FIG. 10 is performed, but the next fold is performed at step S26 of FIG. If it is determined to form, the control after step S13 in FIG. 8 is performed again.

As shown in FIG. 4A, when all the preset folds A1 to A5 are formed on the sheet P, the rotational drive of the transport roller pair 51 by the transport motor 91 is stopped. Further, the second movable guide member 54 is moved from the guide position to the reference position.
Further, at this time, when the first sheet detection sensor 61 is turned off and the sheet rear end B of the sheet P is detected (FIG. 10: Step S27), the length of the sheet P is lengthened by the calculation unit of the control unit 80 (discrimination means). (Sheet length) is calculated (FIG. 10: step S28). Then, based on the result, it is determined whether the fold A5 (fifth fold) of the final folding surface C6 is formed by the first folding roller pair 55 (FIG. 10: step S29).
In the operation example of FIG. 4, it is determined that the fold line A5 (fifth fold line) of the final folding surface C6 is formed by the second folding roller pair 56 instead of the first folding roller pair 55, and thus FIG. However, if it is determined in step S29 of FIG. 10 that the fold line on the final folding surface is formed by the first pair of folding rollers 55, the control will be performed later. The control after step S30 of FIG. 10 described using FIG. 5 is performed.

When it is determined in step S29 in FIG. 10 that the fold line A5 (see FIG. 6A) on the final folding surface is formed by the second folding roller pair 56, as shown in FIG. The sheet P is moved so that the folds A1, A3, A5 on the side of the second folding roller pair 56 are located near the nip of the second folding roller pair 56 (FIG. 10: step S35). Then, as shown in FIGS. 4B and 4C, the second folding roller pair 56 is alternately rotated in the forward and reverse directions to reciprocally move the sheet P, whereby the folds A1, A3, A5 (or , And its vicinity) is put in and taken out from the nip of the second folding roller pair 56 (FIG. 10: step S36). At this time, the timing for switching the reciprocating movement of the sheet P is set based on the ON/OFF signal of the third sheet detection sensor 63. By performing the first reciprocating motion in this manner, the folds A1, A3, A5 on the side of the second folding roller pair 56 are strengthened. The number of reciprocations during the reciprocating operation at this time is not limited to one.
Thereafter, as shown in FIG. 4D, the sheet P is moved so that the folds A2 and A4 on the opposite side of the first folding roller pair 55 are located near the nip of the first folding roller pair 55. (FIG. 10: Step S37). Then, as shown in FIGS. 4D and 4E, the first folding roller pair 55 is alternately rotated in the forward and reverse directions to reciprocally move the sheet P, so that the folds A2 and A4 (or the folds A2 and A4). The vicinity) is put in and taken out from the nip of the first folding roller pair 55 (FIG. 10: step S38). At this time, the timing for switching the reciprocating movement of the sheet P is set based on the ON/OFF signal of the second sheet detection sensor 62. By performing the second reciprocating motion in this way, the folds A2 and A4 on the side of the first folding roller pair 55 are also strengthened. The number of reciprocations during the reciprocating operation at this time is not limited to one.
Finally, as shown in FIG. 4(F), the pair of folding rollers 55 and 56 are rotationally driven in the opposite direction to eject the sheet P, for which all the reciprocating operations have been completed, toward the ejection tray 68, After that, the drive motors 94 and 95 are also turned off and the present flow ends (FIG. 10: step S39).

Next, referring to FIGS. 5A to 5F, the reciprocating operation (reciprocating mode) when the fold A4 of the final folding surface C5 (see FIG. 6B) is formed by the first folding roller pair 55. ) Will be described.
When the four folds A1 to A4 set in advance on the sheet P are formed by the operations of FIGS. 3A to 3F described above, as shown in FIG. The rotation drive of the transport roller pair 51 by the above is stopped. Further, the first movable guide member 53 is moved from the guide position to the reference position.
Then, in step S29 of FIG. 10, it is determined that the fold line A4 (see FIG. 6B) of the final folding surface is formed by the first folding roller pair 55, as shown in FIG. 5A. Then, as shown in FIG. 5B, the sheet P is moved so that the folds A2 and A4 on the first folding roller pair 55 side are located near the nip of the first folding roller pair 55 (FIG. 5B). 10: Step S30). Then, as shown in FIGS. 5B and 5C, the first folding roller pair 55 is alternately rotated in the forward and reverse directions to reciprocally move the sheet P, whereby the folds A2 and A4 (or the folds A2 and A4). The vicinity) is put in and taken out from the nip of the first folding roller pair 55 (FIG. 10: step S31). At this time, the timing for switching the reciprocating movement of the sheet P is set based on the ON/OFF signal of the second sheet detection sensor 62. By performing the first reciprocating motion in this manner, the folds A2 and A4 on the side of the first folding roller pair 55 are strengthened. The number of reciprocations during the reciprocating operation at this time is not limited to one.
Thereafter, as shown in FIG. 5D, the sheet P is moved so that the folds A1 and A3 on the opposite side of the second folding roller pair 56 are located near the nip of the second folding roller pair 56. (FIG. 10: Step S32). Then, as shown in FIGS. 5D and 5E, the second folding roller pair 56 is alternately rotated in the forward and reverse directions to reciprocally move the sheet P, and thereby the folds A1 and A3 (or the folds A1 and A3). (Near) is put in and taken out from the nip of the second folding roller pair 56 (FIG. 10: step S33). At this time, the timing for switching the reciprocating movement of the sheet P is set based on the ON/OFF signal of the third sheet detection sensor 63. By performing the second reciprocating motion in this way, the folds A1 and A3 on the side of the second folding roller pair 56 are also strengthened. The number of reciprocations during the reciprocating operation at this time is not limited to one.
Finally, as shown in FIG. 5F, the pair of folding rollers 55 and 56 are rotationally driven in the opposite direction, and the sheet P, for which all the reciprocating operations have been completed, is discharged toward the discharge tray 68, After that, the drive motors 94 and 95 are also turned off and the present flow ends (FIG. 10: step S34).

In the operation example using FIGS. 3 and 4, the folding process for forming the five folds A1 to A5 on the sheet P will be described. In the operation example using FIGS. 3 and 5, the four folds A1 are formed on the sheet P. Although the folding process for forming A4 to A4 has been described, other folding processes (for example, one-fold, three-fold, Z-fold, double-sided folding, etc.) should be performed according to the control flow shown in FIGS. Can also

Here, in the present embodiment, the moving speed V1 of the sheet P when the above-described reciprocating operation (reciprocating mode) is performed with respect to the nip of the pair of folding rollers 55 and 56 is one of the values for the next reciprocating operation. The rotational speeds of the drive motors 94 and 95 are set to be slower (V1<V2) than the moving speed V2 of the sheet P when the sheet P is moved from the side of the pair of folding rollers to the side of the other pair of folding rollers. Are in control.
In the reciprocating operation of the sheet P, the pressure at the nip of the pair of folding rollers 55 and 56 is slowly applied to the folds to form a firm fold, so that the moving speed V1 of the sheet P is slowed. On the other hand, the operation of moving the sheet P from one folding roller pair side to the other folding roller pair side is related to the speed of the entire processing operation regardless of the degree of reinforcement of the folds. For this reason, the moving speed V2 is increased.
Note that in the present embodiment, the moving speed V0 of the sheet P when forming the fold described in FIG. 3 before the reciprocating operation of the fold is performed from the moving speed V1 of the sheet P when the reciprocating operation is performed. Is also set late (V0<V1). This is because when the pressure is first applied to the sheet P at the nip of the pair of folding rollers 55 and 56, it is desired to take the most time to form a firm fold.

<Modification 1>
FIG. 12(A) is a schematic diagram showing a state in which the length X1 of the final sheet surface C6 is shorter than the first predetermined value W1 in the sheet folding device 50 according to the modified example 1, and FIG. 12(B) is It is a schematic diagram showing a state where the length X2 of the final sheet surface C6 is longer than a second predetermined value W2 (>W1).
In the modified example 1, as in the case of the present embodiment, after the desired number of folds A1 to A5 are all formed on the sheet P, the folding roller pairs 55 and 56 in which the folds A1 to A5 are formed are reversed. A reciprocating operation (reciprocating mode) is carried out in which the folds A1 to A5 (or the vicinity thereof) are alternately driven to rotate in the direction and put in and out from the nip of the pair of folding rollers 55 and 56.
Here, in the modified example 1, as shown in FIG. 12A, when the length X1 of the final folding surface C6 is shorter than the first predetermined value W1 (X1<W1), the control unit 80 (determining means) Based on the determination result, the reciprocating operation with respect to the nip of the folding roller pair 56 in which the fold A5 of the final folding surface C6 is formed is not performed, but only the reciprocating operation with respect to the nip of the other folding roller pair 55 is performed. Specifically, in the example of FIG. 12A, the length X1 of the final folding surface C6 is shorter than the first predetermined value W1, and the nip of the second folding roller pair 56 in which the fold A5 of the final folding surface C6 is formed. On the other hand, when the sheet trailing edge B approaches the second folding roller pair 56 when the reciprocating operation of taking in and out the folds A1, A3, A5 is performed, the nip of the second folding roller pair 56 On the other hand, the reciprocating operation for taking in and out the folds A1, A3, A5 is not performed, but only the reciprocating operation for taking in and out the folds A2, A4 with respect to the nip of the first folding roller pair 55 is performed. If the reciprocating operation of taking the folds A1, A3, A5 in and out of the nip of the second folding roller pair 56 in a state where the sheet rear end B approaches the second folding roller pair 56, the final This is because a problem that the folding surface C6 is displaced is likely to occur.
In Modification 1, as shown in FIG. 12B, when the length X2 of the final folding surface C6 is longer than the second predetermined value W2 (which is larger than the first predetermined value W1) ( X2>W2), based on the determination result by the control unit 80 (determining means), the reciprocating operation is performed with respect to the nip of the folding roller pair 56 in which the fold A5 of the final folding surface C6 is formed, and the other folding roller pair 55 The reciprocating motion with respect to the nip is not performed. Specifically, in the example of FIG. 12B, the length X2 of the final folding surface C6 is longer than the second predetermined value W2, and the nip of the first folding roller pair 55 in which the fold A5 of the final folding surface C6 is formed. On the other hand, if the sheet trailing edge B approaches the first folding roller pair 55 if the reciprocating operation of taking in and out the folds A2 and A4 is performed, the nip of the first folding roller pair 55 is Therefore, the reciprocating operation of moving the folds A2, A4 in and out is not performed, but only the reciprocating operation of moving the folds A1, A3, A5 in and out of the nip of the second folding roller pair 56 is performed. If the reciprocating operation of taking the folds A2 and A4 in and out of the nip of the first folding roller pair 55 is performed in a state where the sheet rear edge B approaches the first folding roller pair 55, the sheet rear edge is moved. This is because a problem that B does not enter the nip of the first folding roller pair 55 and is easily scraped easily occurs.
In Modification 1, when the length X3 of the final folding surface C6 is greater than or equal to the first predetermined value W1 and less than or equal to the second predetermined value W2 (W1≦X3≦W2), the same as in the present embodiment. After the reciprocating operation is performed on the nip of the folding roller pair (second folding roller pair 56) in which the fold A5 of the final folding surface C6 is formed, based on the determination result by the control unit 80 (determining means), The reciprocating operation is performed with respect to the nip of the folding roller pair (first folding roller pair 55).
The length of the final folding surface C6 can be obtained based on the detection result of the first sheet detection sensor 61 and the like, as in the present embodiment.
Then, even when the reciprocating operation is performed as in the modified example 1, the sheet folding device 50 does not become large and cost is high and the sheet P does not become messy as in the case of the present embodiment. Good folds that are not thick can be formed without causing wrinkles or the like. In particular, in the modified example 1, when the distance between the reciprocating fold and the rear end B of the final folding surface is short, the reciprocating movement with respect to the fold is not performed. That is, the reciprocating operation in which the trailing edge B of the sheet P passes through the nip of the pair of folding rollers is not performed. As a result, the effects as described above are exhibited.
In the modified example 1, when the length X1 of the final folding surface C6 is shorter than the first predetermined value W1, the control is performed only to reciprocate the nip of the first folding roller pair 55 and the length of the final folding surface C6. When X2 is longer than the second predetermined value W2, both the control for performing only the reciprocating motion with respect to the nip of the second folding roller pair 56 and the control for performing both of the control are performed. It can also be configured to perform only one control.

<Modification 2>
13A to 13F are diagrams showing the operation of the sheet folding apparatus 50 as the second modification, and are diagrams corresponding to FIGS. 4A to 4F in the present embodiment, respectively. ..
As shown in FIGS. 13(A) to 13(F), also in Modification 2, as in the present embodiment, when all the folds A1 to A5 set in advance on the sheet P are formed, the final sheet is formed. The side of the second folding roller pair 56 on which the fold line A5 of the surface C6 is formed is reciprocated with respect to the first, third, and fifth fold lines A1, A3, and A5, and is then on the opposite side. The folding roller pair 55 reciprocates with respect to the second and fourth folds A2 and A4.
Here, in the second modification, when the sheet P moves from the fold A5 side of the final folding surface C6 to the sheet rear end B side, the final folding surface C6 is pressed by the pair of movable guide members 53 and 54. doing.
Specifically, as shown in FIG. 13D, on the side of the second folding roller pair 56 where the fold A5 of the final sheet surface C6 is formed, the first, third, and fifth folds A1, A3, and A5 with respect to the fold A5 are formed. After the first reciprocating operation is completed, the sheet P is secondly folded in order to perform the second reciprocating operation with respect to the second and fourth folds A2 and A4 on the opposite side of the first folding roller pair 55. When moving from the roller pair 56 side to the first folding roller pair 55 side, the first moving mechanism 92 is controlled so that the final sheet surface C6 of the sheet P is pressed downward by the lower surface of the first movable guide member 53. ing. Thereby, when the sheet P moves from the second folding roller pair 56 side to the first folding roller pair 55 side, the folds A2 and A4 of the sheet P are smoothly guided to the nip of the first folding roller pair 55. become.
In the second modification, as shown in FIGS. 13E and 13F, in order to discharge the sheet P that has finished the second reciprocating operation to the outside of the apparatus, the sheet P is placed on the first folding roller pair 55 side. The second moving mechanism 93 is controlled so that the final sheet surface C6 of the sheet P is pressed downward by the lower surface of the second movable guide member 54 even when the sheet is moved from the second folding roller pair 56 side to the second folding roller pair 56 side. As a result, when the sheet P moves from the first folding roller pair 55 side to the second folding roller pair 56 side, the fold lines A1, A3, A5 of the sheet P are smoothly guided to the nip of the second folding roller pair 56. Will be.
Even in the case where the reciprocating operation is performed as in the second modification, the sheet folding device 50 does not become large or costly, and the sheet P does not become messed up, as in the case of the present embodiment. Good folds that are not thick can be formed without causing wrinkles or the like.

<Modification 3>
14A to 14D are diagrams showing the reciprocating operation performed by the sheet folding apparatus 50 as the third modification.
In Modification 3, the rotational driving of the pair of folding rollers 55 and 56 is stopped at a predetermined timing during the reciprocating operation (reciprocating mode).
Specifically, as shown in FIGS. 14A to 14D, also in the modification 3, when all the folds A1 to A5 that are set in advance on the sheet P are formed, first, the final sheet surface C6 is formed. On the side of the second folding roller pair 56 on which the fold line A5 is formed, the first reciprocating operation is performed with respect to the first, third, and fifth fold lines A1, A3, and A5. At this time, as shown in FIG. 14C, when the first, third, and fifth folds A1, A3, and A5 are sandwiched by the nip of the second folding roller pair 56, the second folding roller pair 56 The rotation is temporarily stopped for a predetermined time. As a result, the nip pressure is applied to the folds A1, A3, A5 for a long time, so that the folds A1, A3, A5 are further strengthened. Although FIG. 14 illustrates only the first reciprocating operation performed on the second folding roller pair 56 side, the second reciprocating operation performed on the first folding roller pair 55 side is similarly performed. 2, the rotation of the first folding roller pair 55 is temporarily stopped for a predetermined time at the timing when the fourth folding lines A2 and A4 are sandwiched by the nip of the first folding roller pair 55. Even when the reciprocating operation is performed in the same manner as in the present embodiment, the sheet folding apparatus 50 does not increase in size and cost, and the sheet P does not suffer from creases or wrinkles. A good fold line that is not thick can be formed.

<Modification 4>
FIG. 15 is a table showing the setting of the reciprocating operation performed by the sheet folding apparatus 50 according to the modification 4, and such a control table is stored in the storage unit of the control unit 80.
In Modified Example 4, as in the case of the present embodiment, when all the preset number of folds are formed on the sheet P, the reciprocating operation (reciprocating mode) with respect to the folds is performed.
Here, in Modification 4, the number of times the sheet is reciprocated in the reciprocating operation is the size (sheet width) of the sheet P in the width direction (the direction orthogonal to the transport direction and the direction perpendicular to the paper surface of FIG. 1 ). The size is controlled to be increased or decreased by at least one of the number of folds A formed on the sheet P (the number of folds).
Specifically, in the example of FIG. 15, the first and second reciprocating motions increase as the number of folding surfaces C formed on the sheet P increases from 1 to 10 surfaces, 11 to 20 surfaces, and 21 to 30 surfaces. The control is performed so that the number of times the fold line is reciprocated with respect to each nip is increased. As the number of folds A (the number of folding surfaces) increases, it becomes more difficult to strengthen the folds, so the number of reciprocating operations is increased.
Further, in the example of FIG. 15, when the sheet width size of the sheet P is 594 mm or more, the number of times the fold line is reciprocated with respect to the nip in the first and second reciprocating operations is controlled to increase. As the sheet width size increases, it becomes difficult to strengthen the folds, so the number of reciprocating operations is increased.
Then, even when the reciprocating operation is performed as in the modified example 4, as in the case of the present embodiment, the sheet folding device 50 does not become large or costly without being damaged. Good folds that are not thick can be formed without causing wrinkles or the like. In particular, by changing the number of reciprocating operations according to the difficulty of strengthening the fold, as in Modification 4, it is possible to efficiently strengthen the fold.
In Modification 4, the number of reciprocating operations is controlled to be increased or decreased based on both the size of the sheet P in the width direction and the number of folds A formed on the sheet P. The number of reciprocating operations can be increased or decreased based on only the size in the direction, or the number of reciprocating operations can be increased or decreased based on only the number of folds A formed on the sheet P. it can.

As described above, the sheet folding apparatus 50 according to the present embodiment sequentially forms the folds A1 to A5 on the sheet P by alternately using the pair of folding rollers 55 and 56 to sequentially form the folds on the sheet P. Of the plurality of folding surfaces C1 to C6, the controller 80 that determines which one of the pair of folding roller pairs 55 and 56 forms the fold A5 of the final folding surface C6 that is formed last. (Discrimination means) is provided. Then, after the desired number of folds A1 to A5 are all formed on the sheet P, the pair of folding rollers 55 and 56 on which the folds A1 to A5 are formed are alternately rotationally driven in the forward and reverse directions to fold the folds A1 to A5 or the vicinity thereof. When the reciprocating operation of moving the paper into and out of the nip of the pair of folding rollers 55 and 56 is performed and the reciprocating operation is performed to the nip of the pair of folding roller pairs 55 and 56, respectively, the control unit 80 Based on the determination result by the (determination means), the reciprocating operation of the pair of folding rollers 55 and 56, which has the fold A5 of the final folding surface C6, with respect to the nip is first performed. ..
As a result, the sheet folding device 50 does not become large in size and cost, and it is possible to form good folds A1 to A5 that are not thick on the sheet P without causing creases or wrinkles.

In the present embodiment, the present invention is applied to the image forming system 100 in which the monochrome image forming apparatus 1 is installed, but it goes without saying that the present invention is applied to an image forming system in which a color image forming apparatus is installed. The present invention can be applied.
Further, in the present embodiment, the present invention is applied to the image forming system in which the electrophotographic image forming apparatus 1 is installed. However, the application of the present invention is not limited to this, and other types of image forming apparatuses may be used. The present invention can of course be applied to an image forming system in which an image forming apparatus (for example, an inkjet type image forming apparatus, a stencil printing apparatus, etc.) is installed.
Even in such cases, the same effect as that of the present embodiment can be obtained.

Further, in the present embodiment, the present invention is applied to the sheet folding apparatus 50 that performs only the folding process, but other processes (for example, punching process, binding process, stamping process, etc.) in addition to the folding process. The present invention can also be applied to a sheet folding apparatus capable of performing (1).
Further, in the present embodiment, the present invention is applied to the sheet folding apparatus 50 connected to the image forming apparatus 1, but the application of the present invention is not limited to this, and the sheet forming apparatus is connected to the image forming apparatus 1. Even if the sheet folding apparatus 50 is an independent apparatus, the present invention can be naturally applied.
Further, in the present embodiment, the sheet P (roll paper) in a roll shape is configured to be stored in the feeding unit 10 of the image forming apparatus 1. However, the sheet cut into a predetermined size (cut sheet) It can also be configured to store paper).
Even in such cases, it is possible to obtain substantially the same effects as those of the present embodiment.

It should be noted that the present invention is not limited to the present embodiment, and it is obvious that the present embodiment can be appropriately modified, other than what is suggested in the present embodiment, within the scope of the technical idea of the present invention. is there. Further, the number, position, shape, etc. of the constituent members are not limited to those in the present embodiment, and any number, position, shape, etc. suitable for carrying out the present invention can be adopted.

In this specification and the like, “sheet” is defined to include not only paper but also all sheets to be folded.

1 image forming apparatus,
50 sheet folding device (post-processing device),
51 transport roller pair,
53 first movable guide member (movable guide member),
54 second movable guide member (movable guide member),
55 first folding roller pair (folding processing section),
56 second folding roller pair (folding processing section),
61 first sheet detection sensor (entrance sensor),
62 second sheet detection sensor,
63 third sheet detection sensor,
80 control unit (discriminating means),
91 transport motor (first drive means),
92 first moving mechanism (second driving means),
93 second moving mechanism (second driving means),
94 first drive motor (third drive means),
95 second drive motor (third drive means),
100 image forming system,
P sheet,
A1-A5 folds,
B sheet rear edge,
C1-C6 Folded surface.

JP, 2006-232410, A JP, 2003-267626, A

Claims (8)

A pair of folding rollers that respectively form folds on the sheet,
Among the plurality of folding surfaces sequentially formed on the sheet by sequentially forming the folds on the sheet by alternately using the pair of folding rollers, the fold of the final folding surface formed last is the pair of folding rollers. A discriminating means for discriminating which of the pair of folding rollers forms the pair;
Equipped with
After the desired number of folds are formed on the sheet, the folding roller pairs having the folds are alternately driven to rotate in the forward and reverse directions to move the folds or the vicinity thereof into and out of the nip of the folding roller pairs. When the operation is executed, and when the reciprocating operation is performed with respect to the nip of the pair of folding roller pairs, among the pair of folding roller pairs, based on the determination result by the determining unit, The sheet folding apparatus, wherein the reciprocating operation is first performed with respect to a nip of a pair of folding rollers forming a fold on the final folding surface. When the length of the final folding surface is shorter than the first predetermined value, the reciprocating operation with respect to the nip of the pair of folding rollers forming the fold of the final folding surface is not performed based on the determination result by the determining means. The sheet folding apparatus according to claim 1, wherein only the reciprocating operation is performed with respect to the nip of one folding roller pair. When the length of the final folding surface is longer than the second predetermined value which is larger than the first predetermined value, the pair of folding rollers forming the fold of the final folding surface based on the discrimination result by the discriminating means. 3. The sheet folding apparatus according to claim 2, wherein the reciprocating operation is performed with respect to the nip, and the reciprocating operation is not performed with respect to the nip of the other folding roller pair. A pair of movable guide members for guiding the sheet conveyed by the pair of conveying rollers toward one of the pair of folding rollers or the other pair of folding rollers;
The final folding surface is pressed by the movable guide member when the sheet moves from the fold side of the final folding surface to the sheet rear end side. Sheet folding device. The sheet folding apparatus according to any one of claims 1 to 4, wherein the rotational drive of the pair of folding rollers is stopped for a predetermined time at a predetermined timing during the execution of the reciprocating operation. The number of times the sheet is reciprocated in the reciprocating operation is increased or decreased depending on at least one of the size in the width direction of the sheet and the number of folds formed on the sheet. The sheet folding device according to any one of the above. The moving speed of the sheet when the reciprocating operation is performed with respect to the nip of the folding roller pair is such that the sheet is moved from one folding roller pair side to the other folding roller pair side in order to perform the next reciprocating operation. The sheet folding apparatus according to any one of claims 1 to 6, wherein the sheet folding apparatus is slower than a moving speed of the sheet when the sheet is moved. An image forming apparatus for forming an image on a sheet, and the sheet folding apparatus according to claim 1 for forming a fold line on the sheet on which the image is formed by the image forming apparatus. An image forming system characterized by the above.

Images