JP2017088357A - Sheet processing device and image formation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet processing device and an image formation system capable of generating a sheet bundle folded for good appearance.SOLUTION: A sheet processing device performs second folding after making first folding with a sheet bundle. The device has a pair of holding rollers 314a, 314b for holding the sheet bundle having been folded for the first time, and a second folding part for performing second folding with the sheet bundle held by the pair of holding rollers 314a, 314b. In this case, the pair of holding rollers 314a, 314b hold the sheet bundle on the side of first folding position F1 where the first folding has been made instead of on a second folding position F2 where a second folding is performed.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a sheet processing apparatus and an image forming system.

  2. Description of the Related Art Conventionally, a sheet processing apparatus that performs a folding process on a sheet bundle in which a plurality of sheets are stacked, and an image forming system that includes the sheet processing apparatus on the downstream side of the image forming apparatus are known. The folding process is a process of folding a sheet bundle by folding the sheet bundle in a first fold and then folding it in a second fold. For example, the folding process includes a three-fold process for folding the sheet bundle in three. There are three types of tri-folds, such as three-fold winding and three-fold outer (Z-fold). The folding process can be applied not only to a sheet bundle but also to a single sheet. In this specification, for convenience, the term “sheet bundle” includes only one sheet (the same applies hereinafter).

  For example, Patent Document 1 discloses a sheet post-processing apparatus that folds a sheet bundle in three. The sheet post-processing apparatus folds the first position of the sheet bundle by pushing the sheet bundle into the nip of the first folding roller with a first pushing plate, and the sheet bundle after being folded at the first position is folded. The second position of the sheet bundle is folded by being pushed into the nip of the second folding roller with a second pushing plate. The first folding roller functions as a conveying unit that conveys the sheet bundle folded by its own folding operation to a position for performing the second folding in a state where the folding is at the head. The second folding is performed in a state where the rear end of the sheet bundle is held by the first folding roller.

JP 2013-116789 A

  However, in the method disclosed in Patent Document 1, when the second folding is performed, the rear end of the sheet bundle is sandwiched between the first folding rollers, so that the finished product after the folding process looks good. It may get worse. For example, in the case of three-fold winding, the distance from the first position to the second position increases as the sheet is located inside the sheet bundle, and the sheet swells inward. In the case of Z-folding, the distance from the first position to the second position becomes shorter as the sheet is located outside the sheet bundle in the second folding, and the folding of each sheet (due to the first folding) The positions of the creases) are uneven. This is because the second folding is performed in a state where the rear end side of each sheet is fixed by the sheet bundle being sandwiched by the first folding roller.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a sheet processing apparatus and an image forming system that can fold a bundle of sheets with good appearance.

  In order to solve this problem, the first invention provides a sheet processing apparatus that performs a second folding after a first folding is performed on a sheet bundle composed of one or more sheets. The sheet processing apparatus includes a sheet holding unit that holds a sheet bundle that has undergone the first folding, and a second folding unit that performs a second folding on the sheet bundle held by the sheet holding unit. The sheet holding unit holds the sheet bundle on the first folding position side where the first folding is performed with respect to the second folding position where the second folding is performed.

  Here, it is preferable that the first invention further includes a sheet conveying unit that conveys the sheet bundle subjected to the first folding to the sheet holding unit with the first folding position at the head. In this case, it is preferable that each of the sheet holding unit and the sheet conveying unit is configured by a pair of rollers that are pressed against each other so as to sandwich the sheet bundle from both sides.

  In the first invention, when the second folding is performed, it is preferable that the pressing force of the sheet holding unit is set to be larger than the pressing force of the sheet conveying unit.

  In the first invention, it is preferable that the sheet conveying unit is switched from the pressure contact state to the separated state when performing the second folding.

  In the first invention, it is preferable that each of the sheet conveying unit and the sheet holding unit is switched from the pressure contact state to the separated state when performing the second folding.

  In the first invention, it is preferable that the pair of rollers forming the sheet holding unit are configured to be rotatable in the forward direction and the reverse direction, respectively.

  In the first invention, the second folding part has a pair of folding rollers that are pressed against each other to form a folding nip. The second folding is performed by inserting a sheet bundle into the folding nip. Preferably, it is done.

  In the first invention, the paper holding unit is configured to be movable in the paper conveyance direction, and the paper holding unit is arranged in the conveyance direction of the paper bundle in accordance with the insertion of the paper bundle into the folding nip. It is preferable to move.

  Further, in the first invention, the sheet holding unit is disposed so as to sandwich an area where the sheet bundles are folded on each other at the first folding position in the sheet bundle subjected to the first folding. It is preferable.

  Next, a second invention includes an image forming apparatus that forms an image on a sheet, and the sheet processing apparatus described in any of the first inventions that processes the sheet supplied from the image forming apparatus. An image forming system is provided.

  According to the present invention, since the sheet bundle can be folded with good appearance, high-quality folding processing can be performed.

1 is a perspective view schematically showing the overall configuration of an image forming system according to a first embodiment. 1 is a block diagram showing a configuration of an image forming system according to a first embodiment. Explanatory drawing which shows the structure of a trifold part typically Explanatory drawing which shows the structure of a trifold part typically Explanatory drawing which shows the procedure of the trifold process which concerns on 1st Embodiment Explanatory drawing which shows the procedure of the trifold process which concerns on 2nd Embodiment Explanatory drawing which shows the procedure of the trifold process which concerns on 3rd Embodiment Explanatory drawing which shows the procedure of the trifold process which concerns on 4th Embodiment

(First embodiment)
FIG. 1 is a perspective view schematically showing an overall configuration of an image forming system 1 according to the present embodiment. FIG. 2 is a block diagram illustrating a configuration of the image forming system 1 according to the present embodiment. The image forming system 1 according to the present embodiment includes an image forming apparatus 100, an intermediate conveyance apparatus 200, a sheet processing apparatus 300, and a side stitching processing apparatus 400.

  In the following description, as shown in FIG. 1, the vertical direction (vertical direction) is the Z direction, and the arrangement direction of the image forming apparatus 100, the intermediate conveyance apparatus 200, the sheet processing apparatus 300, and the flat stitching processing apparatus 400 is the X direction. The direction perpendicular to the XZ plane is taken as the Y direction. The X direction will be described with a front side and a rear side, and the Y direction will be described with a right side and a left side. Here, the front side is the upstream side in the transport direction in the image forming system 1, and the rear side is the downstream side.

  The image forming apparatus 100 forms an image on a sheet based on the image data. The sheet on which the image is formed is discharged from the image forming apparatus 100 and sent to the intermediate conveyance apparatus 200.

  The image forming apparatus 100 is, for example, an electrophotographic image forming apparatus. The image forming apparatus 100 mainly includes a photosensitive member, a charging unit, an image exposure unit, a developing unit, a transfer unit, a fixing device, and a paper discharge unit. The surface of the photoreceptor is uniformly charged by the charging unit. The image exposure unit scans and exposes the surface of the photoreceptor with a laser beam corresponding to the image data. As a result, a latent image is formed on the surface of the photoreceptor. The developing unit reversely develops the latent image with toner, and a toner image is formed on the surface of the photoreceptor. The transfer unit transfers the toner image on the surface of the photoreceptor to a sheet directly or via an intermediate transfer member. The fixing device performs a fixing process by heating and pressing the paper on which the image is transferred. Then, the sheet subjected to the fixing process is sent to the paper discharge unit, and is discharged out of the apparatus by the paper discharge unit.

  Note that the image forming apparatus 100 can simply send out the paper to the intermediate conveyance device 200 without forming an image on the paper.

  When the intermediate conveyance device 200 receives the sheet sent from the image forming apparatus 100, the intermediate conveyance device 200 temporarily waits for the sheet, or performs creasing and cutting on the sheet. The paper that has been subjected to various types of processing is discharged from the intermediate conveyance device 200 and sent to the paper processing device 300.

  The intermediate conveyance device 200 includes, for example, a standby unit (stacker), an alignment unit, a creasing unit (creaser), and a cutting unit (slitter). The standby unit conveys the sheet sent out from the image forming apparatus 100 so as to be lowered, and temporarily stops the sheet in a state where the sheet surface is substantially along the YZ plane. The aligning unit aligns the position of the waiting sheet. The creasing section performs creasing on the aligned paper. The cutting unit cuts a blank portion of the paper while conveying the creased paper.

  The intermediate conveyance device 200 can also send the paper received from the image forming apparatus 100 to the paper processing device 300 without performing some or all of the various processes performed by the intermediate conveyance device 200.

  The sheet processing apparatus 300 is an apparatus that performs various processes on the sheet fed from the intermediate conveyance apparatus 200 (image forming apparatus 100), and is a so-called post-processing apparatus. The sheet processing apparatus 300 includes a trifold unit 310.

  3 and 4 are explanatory diagrams schematically showing the configuration of the trifold portion 310. FIG. The three-fold unit 310 sequentially superimposes sheets fed from the intermediate conveyance device 200 (image forming apparatus 100), and then folds the plurality of sheets (sheet bundle) in a first fold (first fold). After folding, a three-fold process is performed in which the second fold (second fold) is performed to fold the sheet into three. Hereinafter, in the present specification, the position of the sheet bundle folded at the first time is referred to as “first folding position”, and the position of the sheet bundle folded at the second time is referred to as “second folding position”. These folding positions are determined in advance by the paper size or user settings.

  The three-fold portion 310 includes a first folding roller 311a, a second folding roller 311b, a third folding roller 311c, a first pushing member 312a, a second pushing member 313a, and a pair of holding rollers 314a and 314b. Consists of the subject.

  Each of the folding rollers 311a, 311b, 311c is, for example, a roller whose outer peripheral surface is covered with an elastic layer.

  The first folding roller 311a and the second folding roller 311b are arranged in pressure contact with each other, and thereby a first nip (folding nip) N1 is formed at the pressure contact portion between the both folding rollers 311a and 311b. The first folding roller 311a and the second folding roller 311b have a function of performing the first folding on the sheet bundle and a function of conveying the sheet bundle on which the first folding has been performed to the pair of holding rollers 314a and 314b. ing. The first folding roller 311a and the second folding roller 311b are pressed against each other by the pressure required to fold the sheet bundle.

  The second folding roller 311b and the third folding roller 311c are arranged in pressure contact with each other, and thereby a second nip (folding nip) N2 is formed at the pressure contact portion between the both folding rollers 311a and 311b. The second folding roller 311b and the third folding roller 311c have a function of folding the sheet bundle for the second time and a function of conveying the sheet bundle subjected to the second folding to the subsequent process. The second folding roller 311b and the third folding roller 311c are pressed against each other by the pressure necessary to fold the sheet bundle.

  These folding rollers 311a, 311b, 311c can rotate through a power mechanism (not shown). For example, the power mechanism rotationally drives the second folding roller 311b, and the remaining folding rollers 311a and 311c are driven to rotate, whereby the folding rollers 311a, 311b, and 311c rotate.

  The roller directly driven by the power mechanism is not limited to the second folding roller 311b, and any one or more of the folding rollers 311a, 311b, 311c may be used as long as the three-folding operation shown in the present embodiment can be performed. It may be driven.

  Furthermore, in this embodiment, the 1st folding roller 311a and the 2nd folding roller 311b can cancel | release the said press contact state other than the press contact state mentioned above, and can change to the state mutually separated. The first folding roller 311a and the second folding roller 311b operate through a power mechanism (not shown), and can switch the state between a crimped state and a separated state. When switching from the pressure contact state to the separated state, the first folding roller 311a may be configured to move, or the second folding roller 311b may be configured to move together with the third folding roller 311c. Both may be used.

  The first pushing member 312a is a flat plate-like member, and performs the first folding in cooperation with the first folding roller 311a and the second folding roller 311b. As shown in FIG. 3, the first pushing member 312a has a tangent to the pressure contact portion (first nip N1) between the first folding roller 311a and the second folding roller 311b so that the tip thereof faces the first nip N1. It is arranged along the direction (initial position).

  The first pushing member 312a is configured to be linearly reciprocable along the direction A1 toward the first nip N1. The first pushing member 312a enters between the first folding roller 311a and the second folding roller 311b (first nip N1) through a power mechanism (not shown), or retreats from this state to the initial position. Advance / retreat operation can be performed.

  The second pushing member 313a is a plate-like member, like the first pushing member 312a, and performs the second folding in cooperation with the second folding roller 311b and the third folding roller 311c. As shown in FIG. 3, the second pushing member 313a has a tangent to the pressure contact portion (second nip N2) between the second folding roller 311b and the third folding roller 311c so that the tip of the second pushing member 313a faces the second nip N2. It is arranged along the direction (initial position).

  The second pushing member 313a is configured to be linearly reciprocable along the direction A2 toward the second nip N2. The second pushing member 313a enters between the second folding roller 311b and the third folding roller 311c (second nip N2) through a power mechanism (not shown), or retreats from this state to the initial position. Advance / retreat operation can be performed.

  The pair of holding rollers 314a and 314b are in pressure contact with each other, whereby a third nip N3 is formed at the pressure contact portion between the both holding rollers 314a and 314b. The pair of holding rollers 314a and 314b are for holding the sheet bundle folded by the first folding from both sides in the thickness direction (sheet holding unit). Each of the holding rollers 314a and 314b is a driven roller that rotates with the movement of the sandwiched sheet bundle, and includes, for example, a roller whose outer peripheral surface is covered with an elastic layer.

  As shown in FIG. 4, the pair of holding rollers 314a and 314b has a tangential direction of the third nip N3 and a tangential direction of the first nip N1 above the first folding roller 311a and the second folding roller 311b. Are arranged as follows. Further, the pair of holding rollers 314a and 314b allows the sheet bundle sent from the first folding roller 311a and the second folding roller 311b (the sheet bundle folded by the first folding) to be more than the second folding position F2. It arrange | positions so that it may hold | maintain at the 1st folding position F1 side. More specifically, the pair of holding rollers 314a and 314b holds a region S1 in which the sheet bundles are folded on each other with the first folding position F1 as a boundary with respect to the sheet bundle folded by the first folding. Has been placed.

  The pair of holding rollers 314a and 314b can release the pressure contact state in addition to the above-described pressure contact state, and transition to a state of being separated from each other. The pair of holding rollers 314a and 314b can be switched between a crimped state and a separated state through a power mechanism (not shown). When switching from the pressure contact state to the separation state, only one holding roller 314a may be moved, or only the other holding roller 314b may be moved, or both. May be.

  As one of the features of this embodiment, the pressure contact force (Fa) by the pair of holding rollers 314a and 314b, that is, the holding force of the sheet bundle is the pressure contact force (Fb) by the first folding roller 311a and the second folding roller 311b. In other words, the relationship is set to be larger than the holding force of the sheet bundle (Fa> Fb). Such a relationship of the pressure contact force may be set in the case of performing at least the second folding, and need not always be set to such a force relationship. Here, in the present embodiment, when the second folding is performed, the first folding roller 311a and the second folding roller 311b are switched to the separated state, and the pressure contact force (the first folding roller 311a and the second folding roller 311b ( Fb) is set to be zero (Fa> Fb (= 0)).

  Referring to FIGS. 1 and 2 again, in addition to the tri-fold process, the sheet processing apparatus 300 performs, for example, a half-fold process for folding the sheet into two (folded), and stacking a predetermined number of the folded sheets. The functions include a saddle stitching process for creating a saddle-stitched booklet, a square-back forming process for forming a spine on the back cover of the booklet, a cutting process for performing a small-edge cutting of the booklet, and the like. That is, the sheet processing apparatus 300 further includes a center folding unit 320, a saddle stitching unit 330, a clamp unit 340, a cutting unit 350, a square back forming unit 360, and discharge units 370 and 380.

  The middle folding unit 320 folds the sheet fed from the intermediate conveyance device 200 along the crease (a middle folding process). The saddle stitching unit 330 sequentially accumulates the sheets folded by the middle folding unit 320. When a number of sheets (sheet bundles) corresponding to a part of the booklet are accumulated, the saddle stitching unit 330 strikes the sheet bundle and outputs the saddle stitched booklet. Create (saddle stitching).

  The clamp unit 340 holds the saddle stitch booklet and performs an alignment operation for aligning the saddle stitch booklet at a predetermined position. Furthermore, the clamp part 340 can lower the edge of the saddle-stitched booklet while holding the saddle-stitched booklet, thereby allowing the edge part of the saddle-stitched booklet to enter the cutting part 350. The cutting unit 350 performs a cutting process on the edge of the saddle-stitched booklet held by the clamp unit 340. The square spine forming unit 360 performs a square spine forming process on the spine of the saddle stitch booklet, and is mounted on the clamp unit 340.

  The discharge unit 370 discharges the saddle stitch booklet to the outside. On the other hand, the discharge unit 380 discharges the sheet bundle that has been folded in three by the three-fold unit 310 to the outside.

  Note that the sheet processing apparatus 300 can also send the sheet delivered from the intermediate conveyance apparatus 200 to the side stitching processing apparatus 400 without performing various processes by the sheet processing apparatus 300.

  The side stitching processing device 400 performs side stitching processing and the like on a sheet bundle. Specifically, the side stitching processing apparatus 400 includes, for example, a staple processing unit, a page edge trimming unit, and a discharge unit. The staple processing unit performs a staple process on the sheet bundle sent from the sheet processing apparatus 300. The page edge trimming unit performs a small edge trimming to cut off a part of the edge part in order to align the edge part parallel to the spine among the bundle of sheets subjected to the stapling process. The discharge unit discharges the processed sheet bundle.

  It should be noted that the side stitching processing device 400 can also discharge the paper sent out from the paper processing device 300 without performing some or all of the various processes performed by the side stitching processing device 400.

  As shown in FIG. 2, the control system of the image forming system 1 according to the present embodiment includes a central control unit 501, an image forming control unit 502 included in the image forming apparatus 100, and an intermediate transport control unit included in the intermediate transport apparatus 200. 503, a sheet processing control unit 504 included in the sheet processing apparatus 300, a side binding processing control unit 505 included in the side binding processing apparatus 400, and an operation display unit 510.

  The central control unit 501 controls the operation of the entire image forming system 1. The image formation control unit 502 controls the operation of the image forming apparatus 100. The intermediate conveyance control unit 503 controls the operation of the intermediate conveyance device 200. The sheet processing control unit 504 controls the operation of the sheet processing apparatus 300. The side stitching processing control unit 505 controls the operation of the side stitching processing apparatus 400. The central control unit 501, the image formation control unit 502, the intermediate conveyance control unit 503, the paper processing control unit 504, and the side stitching processing control unit 505 each have a CPU, a RAM, a ROM, and the like, and are software programs corresponding to the processing contents. And various data are read and executed.

  The operation display unit 510 receives a user input operation related to the operation of the image forming system 1 and performs display output related to the operation of the image forming system 1. The operation display unit 510 includes, for example, a touch panel type operation display device, various input switches, keys, and the like, and transmits a signal corresponding to a user input content to the central control unit 501.

  In the image forming system 1, the central control unit 501 sets various conditions related to the image forming system 1 in accordance with the user input content input via the operation display unit 510. The setting contents of the various conditions include, for example, the paper size and the number of colors at the time of image formation (for example, color, grayscale, monochrome, etc.), three-fold control mode selection conditions, the number of sheets to be folded, the number of sheets to be folded This includes the type, size, basis weight of the paper to be printed, whether or not the creasing is performed by the creasing portion of the intermediate conveyance device 200, the width of the edge to be cut, and the like.

  The central control unit 501 issues a command for performing processing according to the setting contents to the control units of the image formation control unit 502, the intermediate conveyance control unit 503, the paper processing control unit 504, and the side stitching processing control unit 506. Output. Each of the control units 502, 503, 504, and 506 controls the operations of the devices 100, 200, 300, and 400 that are control targets in accordance with commands.

  Hereinafter, a series of procedures related to the tri-fold process of the image forming system 1 according to the present embodiment will be described. Here, FIG. 5 is an explanatory diagram illustrating a procedure of the tri-fold process according to the first embodiment. The central control unit 501 outputs a command for performing a trifold process to the paper processing control unit 504. In response to this, the sheet processing control unit 504 controls the tri-folding unit 310 to execute the tri-folding process as described below.

  As shown in FIG. 5A, the paper supplied from the intermediate transport device 200 is transported in the direction of arrow B1 along the transport path Pa. The conveyed sheet stops when the leading end in the conveying direction comes into contact with the stacker 315a. When performing a three-fold process on a plurality of sheet bundles, the sheets supplied from the intermediate conveyance device 200 are sequentially stacked, and the leading ends of the sheets are aligned by the stacker 315a. The stacker 315a is configured to be capable of reciprocating along the transport path Pa, and moves the sheet bundle so that the front end position of the first pushing member 312a matches the first folding position F1 of the sheet bundle.

  Next, when the first pushing member 312a enters the sheet bundle held by the stacker 315a, the sheet bundle is inserted into the first nip N1, and pressure is applied from both sides by the first folding roller 311a and the second folding roller 311b. By being added, the first folding is performed. Thus, the 1st pushing member 312a, the 1st folding roller 311a, and the 2nd folding roller 311b function as a 1st folding part which performs the 1st folding.

  The sheet bundle that has passed through the first nip N1 is conveyed by the first folding roller 311a and the second folding roller 311b, and proceeds on the conveyance path Pb with the first folding position F1 as the head.

  As shown in FIG. 5B, when the leading end (first folding position F1) of the sheet bundle enters the third nip N3, the pair of holding rollers 314a and 314b are driven to rotate to a predetermined position. When reaching, the conveyance of the sheet bundle is stopped by the conveyance stop by the first folding roller 311a and the second folding roller 311b. In this case, the pair of holding rollers 314a and 314b sandwich an area of the sheet bundle folded by the first folding where the sheet bundles are folded on each other at the first folding position F1. Here, as is apparent from the above-described operation, the first folding roller 311a and the second folding roller 311b are a pair of holding rollers, starting from the first folding position F1, with the sheet bundle folded in the first folding. It also functions as a paper transport unit for transporting to 314a and 314b.

  Next, as shown in FIG. 5C, when the second pushing member 313a moves forward toward the sheet bundle sandwiched between the pair of holding rollers 314a and 314b, the sheet bundle is moved by the tip of the second pushing member 313a. It is abutted against the gap between the second folding roller 311b and the third folding roller 311c so as to be bent. Thereby, the 2nd pushing member 313a is positioned to the 2nd folding position F2. When the second pushing member 313a is positioned, the first folding roller 311a and the second folding roller 311b are switched from the press contact state to the separated state.

  As the second pushing member 313a continues to advance, a sheet bundle is inserted into the second nip N2. Then, the second folding is performed by applying pressure from both sides by the second folding roller 311b and the third folding roller 311c. Thus, the 2nd pushing member 313a, the 2nd folding roller 311b, and the 3rd folding roller 311c function as a 2nd folding part which performs the 2nd folding.

  Then, the sheet bundle that has been folded in three through the second nip N2 is conveyed by the second folding roller 311b and the third folding roller 311c, and proceeds on the conveyance path Pc with the second folding position F2 as the head.

  As described above, in this embodiment, the sheet processing apparatus 300 is an apparatus that performs the second folding after the first folding of the sheet bundle, and holds the sheet bundle that has been folded the first time. A pair of holding rollers 314a and 314b, and a second folding unit that performs the second folding on the sheet bundle held by the pair of holding rollers 314a and 314b. In this case, the pair of holding rollers 314a and 314b hold the sheet bundle on the first folding position F1 side where the first folding is performed rather than the second folding position F2 where the second folding is performed. Yes.

  According to this configuration, the sheet bundle that has been folded for the first time can be held by the pair of holding rollers 314a and 314b. Therefore, when the second folding is performed, the rear end side of the sheet bundle is fixed. The restriction of having to be eliminated becomes unnecessary. As a result, when the second folding is performed, the fixed state of the rear end side of the sheet bundle can be released, or the fixed state can be relaxed. Can be tolerated. Thus, the sheet bundle can be folded with good appearance, and high-quality three-fold processing can be performed.

  Here, the rear end of the sheet bundle is defined on the basis of the conveyance state of the sheet bundle conveyed by the first folding roller 311a and the second folding roller 311b, and in particular, the boundary between the first folding position F1. The sheet area side end (end parallel to the folding direction) where the second folding is performed is indicated.

  Further, in the present embodiment, the sheet processing apparatus 300 includes a first folding roller 311a that conveys the sheet bundle that has been folded for the first time to the pair of holding rollers 314a and 314b with the first folding position F1 at the top, and A second folding roller 311b is provided. The first folding roller 311a and the second folding roller 311b are switched from the pressure contact state to the separated state when the second folding is performed.

  According to this configuration, when the second folding is performed, the rear end side of the sheet bundle is completely released, so that the rear end of each sheet forming the sheet bundle can be allowed to shift. As a result, the sheet bundle can be folded with good appearance, and high-quality three-fold processing can be performed.

  In the present embodiment, when the second folding is performed, the first folding roller 311a and the second folding roller 311b are switched to the separated state, and the pressure contact force is zero. However, the pressure contact force (Fa) of the pair of holding rollers 314a and 314b may be set to be larger than the pressure contact force (Fb) of the first folding roller 311a and the second folding roller 311b. Therefore, the first folding roller 311a and the second folding roller 311b may be in a pressure contact state when performing the second folding as long as the relationship of the pressure contact force (Fa> Fb) is satisfied.

  According to this configuration, when the second folding is performed, the holding force on the rear end side of the sheet bundle is weak, so that the deviation of the rear end of each sheet forming the sheet bundle can be allowed. As a result, the sheet bundle can be folded with good appearance, and high-quality three-fold processing can be performed.

  Moreover, according to this structure, when performing the 2nd folding, the 1st folding roller 311a and the 2nd folding roller 311b will be in the state pressed slightly. Therefore, when the second folding is performed, that is, when the sheet bundle is inserted into the second folding roller 311b and the third folding roller 311c, the posture of the sheet bundle can be stabilized. Thereby, the second folding can be performed neatly.

  Further, in the present embodiment, the pair of holding rollers 314a and 314b sandwich an area S1 in which the sheet bundles are folded on each other at the first folding position F1 in the sheet bundle that has been folded for the first time. (Refer to FIG. 4).

  According to this configuration, the pair of holding rollers 314a and 314b can hold the sheet bundle closer to the first folding position F1 than the second folding position F2. On the other hand, when the second folding is performed, the sheet bundle moves so as to be pulled out from the pair of holding rollers 314a and 314b. In this case, by sandwiching the region S1, when passing through the pair of holding rollers 314a and 314b, the leading end portion of the sheet folded by the first folding interferes with the pair of holding rollers 314a and 314b. Inconveniences such as rising and falling irregularly can be suppressed.

(Second Embodiment)
The image forming system 1 according to the second embodiment will be described below. The image forming system 1 according to the second embodiment is different from that of the first embodiment in the operation mode of the three-fold unit 310 of the sheet processing apparatus 300. The description common to the first embodiment will be omitted, and the following description will focus on the differences. Here, FIG. 6 is an explanatory diagram illustrating a procedure of the tri-fold process according to the second embodiment.

  As shown in FIG. 6A, when a predetermined number of sheets are stacked on the stacker 315a, the stacker 315a aligns the tip position of the first pushing member 312a with the first folding position F1 of the sheet bundle. Next, move the sheet bundle. Then, the first pushing member 312a enters toward the sheet bundle held by the stacker 315a. As a result, the sheet bundle is inserted into the first nip N1, and the first folding is performed by applying pressure from both sides by the first folding roller 311a and the second folding roller 311b.

  The sheet bundle that has passed through the first nip N1 is conveyed by the first folding roller 311a and the second folding roller 311b, and proceeds on the conveyance path Pb with the first folding position F1 as the head.

  As shown in FIG. 6B, when the leading end (first folding position F1) of the sheet bundle enters the third nip N3, the pair of holding rollers 314a and 314b are driven to rotate and reach a predetermined position. The conveyance of the sheet bundle is stopped by the conveyance stop by the first folding roller 311a and the second folding roller 311b.

  Next, as shown in FIG. 6C, the second pushing member 313a moves forward toward the sheet bundle held between the pair of holding rollers 314a and 314b. The sheet bundle is abutted against the gap between the second folding roller 311b and the third folding roller 311c so as to be bent by the second pushing member 313a. Thereby, the 2nd pushing member 313a is positioned in the 2nd folding position F2.

  In this way, when the second pushing member 313a is positioned at the second folding position F2, the first folding roller 311a and the second folding roller 311b are switched from the pressure contact state to the separated state. Similarly, the pair of holding rollers 314a and 314b are also switched from the press contact state to the separated state.

  As the second pushing member 313a continues to advance, a sheet bundle is inserted into the second nip N2. Then, the second folding is performed by applying pressure from both sides by the second folding roller 311b and the third folding roller 311c. The sheet bundle that has been folded in three through the second nip N2 is transported by the second folding roller 311b and the third folding roller 311c, and proceeds on the transport path Pc with the second folding position F2 as the head.

  As described above, in the present embodiment, when the second folding is performed, the first folding roller 311a and the second folding roller 311b and the pair of holding rollers 314a and 314b are switched from the pressure contact state to the separated state. Yes.

  According to this configuration, when the second folding is performed, the sheet bundle is transported with a symmetrical transport resistance with respect to the second folding position F2. When the conveyance resistances on both sides are unbalanced, there is a concern that creases or the like may occur, but according to the present embodiment, such a problem can be solved.

(Third embodiment)
The image forming system 1 according to the third embodiment will be described below. The image forming system 1 according to the third embodiment is different from that of the first embodiment in the operation mode of the three-fold section 310 of the sheet processing apparatus 300. The description common to the first embodiment will be omitted, and the following description will focus on the differences. Here, FIG. 7 is an explanatory diagram illustrating a procedure of the tri-fold process according to the third embodiment.

  In the present embodiment, the pair of holding rollers 314a and 314b can rotate through a power mechanism (not shown). For example, the power mechanism directly drives one holding roller 314a, and the remaining holding roller 314b rotates following the rotation of the one holding roller 314a, thereby rotating each holding roller 314a, 314b. Let The rotation operation of the holding roller 314a by the power mechanism is configured to operate not only in the forward direction but also in the reverse direction.

  As shown in FIG. 7A, when a predetermined number of sheets are stacked on the stacker 315a, the stacker 315a aligns the tip position of the first pushing member 312a with the first folding position F1 of the sheet bundle. Next, move the sheet bundle. Then, the first pushing member 312a enters toward the sheet bundle held by the stacker 315a. As a result, the sheet bundle is inserted into the first nip N1, and the first folding is performed by applying pressure from both sides by the first folding roller 311a and the second folding roller 311b.

  The sheet bundle that has passed through the first nip N1 is conveyed by the first folding roller 311a and the second folding roller 311b, and proceeds on the conveyance path Pb with the first folding position F1 as the head.

  As shown in FIG. 7B, when the leading end (first folding position F1) of the sheet bundle reaches the predetermined position after entering the third nip N3, the conveyance of the sheet bundle is stopped. The pair of holding rollers 314a and 314b are rotated along the insertion direction of the sheet bundle until the conveyance of the sheet bundle is stopped.

  Next, as shown in FIG. 7C, the second pushing member 313a moves forward toward the sheet bundle sandwiched between the pair of holding rollers 314a and 314b. The sheet bundle is abutted against the gap between the second folding roller 311b and the third folding roller 311c so as to be bent by the second pushing member 313a. Thereby, the 2nd pushing member 313a is positioned in the 2nd folding position F2.

  In this way, when the second pushing member 313a is positioned at the second folding position F2, the first folding roller 311a and the second folding roller 311b are switched from the pressure contact state to the separated state. Further, the pair of holding rollers 314a and 314b are rotated in the direction opposite to that when the sheet bundle is inserted.

  As the second pushing member 313a continues to advance, a sheet bundle is inserted into the second nip N2. Then, the second folding is performed by applying pressure from both sides by the second folding roller 311b and the third folding roller 311c. The sheet bundle that has been folded in three through the second nip N2 is transported by the second folding roller 311b and the third folding roller 311c, and proceeds on the transport path Pc with the second folding position F2 as the head.

  Thus, in the present embodiment, the pair of holding rollers 314a and 314b are configured to be rotatable in the forward direction and the reverse direction, respectively.

  The sheet bundle sandwiched between the pair of holding rollers 314a and 314b is pulled out from the third nip N3 during the second folding. At this time, the pair of holding rollers 314a and 314b rotate in the reverse direction (reverse direction with reference to the rotation direction at the time of insertion), so that the sheet bundle smoothly exits the third nip N3. Thereby, the first folding position F1 of the sheet bundle is caught by the pair of holding rollers 314a and 314b and can be prevented from being bent into a box shape.

  In the present embodiment, the pair of holding rollers 314a and 314b are configured to rotate. However, the pair of holding rollers 314a and 314b may be driven rollers.

(Fourth embodiment)
The image forming system 1 according to the fourth embodiment will be described below. The image forming system 1 according to the fourth embodiment is different from that of the first embodiment in the operation mode of the three-fold unit 310 of the sheet processing apparatus 300. The description common to the first embodiment will be omitted, and the following description will focus on the differences. Here, FIG. 8 is an explanatory diagram illustrating a procedure of the tri-fold process according to the fourth embodiment.

  Here, in this embodiment, the conveyance path Pb of the sheet bundle conveyed by the first folding roller 311a and the second folding roller 311b extends in a direction away from the third folding roller 311c while being curved. In other words, when the first folded sheet bundle is conveyed by the first folding roller 311a and the second folding roller 311b, the sheet bundle is conveyed in a direction away from the third folding roller 311c. In this case, the pair of holding rollers 314a and 314b are provided on the transport path Pb, and are configured to be able to reciprocate along the transport path Pa.

  As shown in FIG. 8A, when a predetermined number of sheets are stacked on the stacker 315a, the stacker 315a aligns the tip position of the first pushing member 312a with the first folding position F1 of the sheet bundle. Next, move the sheet bundle. Then, the first pushing member 312a enters toward the sheet bundle held by the stacker 315a. As a result, the sheet bundle is inserted into the first nip N1, and the first folding is performed by applying pressure from both sides by the first folding roller 311a and the second folding roller 311b.

  The sheet bundle that has passed through the first nip N1 is conveyed by the first folding roller 311a and the second folding roller 311b, and proceeds on the conveyance path Pb with the first folding position F1 as the head.

  As shown in FIG. 8B, when the leading end (first folding position F1) of the sheet bundle enters the third nip N3, the pair of holding rollers 314a and 314b are driven to rotate and reach a predetermined position. The conveyance of the sheet bundle is stopped by the conveyance stop by the first folding roller 311a and the second folding roller 311b.

  Next, as shown in FIG. 8C, the second pushing member 313a advances toward the sheet bundle sandwiched between the pair of holding rollers 314a and 314b. The sheet bundle is abutted against the gap between the second folding roller 311b and the third folding roller 311c so as to be bent by the second pushing member 313a. Thereby, the 2nd pushing member 313a is positioned in the 2nd folding position F2.

  In this way, when the second pushing member 313a is positioned at the second folding position F2, the first folding roller 311a and the second folding roller 311b are switched from the pressure contact state to the separated state.

  As the second pushing member 313a continues to advance, a sheet bundle is inserted into the second nip N2. At this time, the pair of holding rollers 314a and 314b starts to move in the direction approaching the second nip N along the transport path b. The movement of the pair of holding rollers 314a and 314b ends when the predetermined distance of the second nip N is reached.

  A second bundle is executed by inserting a sheet bundle into the second nip N2 and applying pressure from both sides by the second folding roller 311b and the third folding roller 311c. The sheet bundle that has been folded in three through the second nip N2 is transported by the second folding roller 311b and the third folding roller 311c, and proceeds on the transport path Pc with the second folding position F2 as the head.

  As described above, in the present embodiment, the pair of holding rollers 314a and 314b are configured to move in the conveyance direction of the sheet bundle in accordance with the conveyance of the sheet bundle inserted into the second nip N.

  The sheet bundle sandwiched between the pair of holding rollers 314a and 314b is pulled out from the third nip N3 during the second folding. In this case, if the distance between the pair of holding rollers 314a and 314b and the first folding position F1 is long, the first folding position F1 is folded in a box shape when the sheet bundle is pulled out from the third nip N3. It tends to be easier. On the other hand, when the sheet bundle comes out from the third nip N3, the position of the sheet bundle inserted into the second nip N2 becomes more stable as the position (third nip N3) is closer to the second nip N2.

  According to the present embodiment, the pair of holding rollers 314a and 314b is moved in accordance with the second folding, so that the first folding position F1 is not easily folded into a box shape and is inserted into the second nip N2. The posture of the sheet bundle to be stabilized is stabilized. Thereby, a high-quality three-fold process can be performed.

  The image forming system according to the embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications are possible within the scope of the invention. .

  For example, although the description has been given of the three-fold winding, the present invention is applicable to the three-fold outer (Z-fold).

  Moreover, in this embodiment, the structure provided with a pushing member as a 1st folding part and a 2nd folding part was demonstrated. However, you may comprise a 1st fold part and a 2nd fold part as what performs what is called buckle folding which does not have a pushing member. In other words, each of the first folding part and the second folding part only needs to have a pair of folding rollers that are pressed against each other to form a folding nip.

  In addition to the image forming system shown in this embodiment, the sheet processing apparatus itself functions as part of the present invention.

DESCRIPTION OF SYMBOLS 1 Image forming system 100 Image forming apparatus 200 Intermediate | middle conveyance apparatus 300 Paper processing apparatus 400 Side stitch processing apparatus 310 Trifold part 311a 1st folding roller 311b 2nd folding roller 311c 3rd folding roller 312a 1st pushing member 313a 2nd pushing member 314a Holding roller 314b Holding roller 320 Folding part 330 Saddle stitching part 340 Clamping part 350 Cutting part 360 Square back forming part 370 Discharge part 380 Discharge part 501 Central control part 504 Paper processing control part

Claims (10)

In a sheet processing apparatus for performing a second folding after performing a first folding on a sheet bundle of one or more sheets,
A sheet holding unit for holding the sheet bundle subjected to the first folding;
A second folding unit for performing the second folding on the sheet bundle held by the sheet holding unit,
The sheet processing apparatus, wherein the sheet holding unit holds the sheet bundle on the first folding position side where the first folding is performed with respect to the second folding position where the second folding is performed. A sheet conveying section that conveys the sheet bundle that has undergone the first folding to the sheet holding section starting from the first folding position;
2. The sheet processing apparatus according to claim 1, wherein each of the sheet holding unit and the sheet conveying unit includes a pair of rollers that are pressed against each other so as to sandwich a sheet bundle from both sides.   The paper processing according to claim 2, wherein the pressure contact force of the paper holding unit is set to be larger than the pressure contact force of the paper transport unit when the second folding is performed. apparatus.   4. The sheet processing apparatus according to claim 3, wherein the sheet conveying unit is switched from a pressure contact state to a separated state when performing the second folding. 5.   3. The sheet processing apparatus according to claim 2, wherein each of the sheet conveying unit and the sheet holding unit is switched from a press-contact state to a separated state when performing the second folding.   5. The sheet processing apparatus according to claim 2, wherein the pair of rollers forming the sheet holding unit is configured to be rotatable in a forward direction and a reverse direction. 6. The second folding part has a pair of folding rollers that are pressed against each other to form a folding nip,
The sheet processing apparatus according to claim 1, wherein the second folding is performed by inserting a sheet bundle into the folding nip. The paper holding unit is configured to be movable in the paper transport direction,
The sheet processing apparatus according to claim 7, wherein the sheet holding unit moves along a conveyance direction of the sheet bundle in accordance with the insertion of the sheet bundle into the folding nip.   The sheet holding unit is disposed so as to hold an area where the sheet bundles are folded on each other with the first folding position as a boundary in the sheet bundle subjected to the first folding. The sheet processing apparatus according to claim 1. An image forming apparatus for forming an image on paper;
The sheet processing apparatus according to any one of claims 1 to 9, which processes a sheet supplied from the image forming apparatus.
An image forming system comprising:

Images