JP2012071978A - Post-treatment device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent increase in cost as well as overall enlargement and complication of a device in formation of a square back in a portion of the back of a sheet bundle.SOLUTION: The post treatment device includes a second conveying unit 12; a sheet support tray 143; a stapling processing unit 13; a middle folding processing unit 14; a backing member 144; and a roller rotation control unit 174. The roller rotation control unit 174 rotates a pair of folding rollers 142 in a direction of moving the sheet bundle in a first direction in middle folding processing, and rotates the pair of folding rollers 142 in a direction of moving the sheet bundle in a second direction when the backing member 144 presses the back portion of the sheet bundle.

Description

  The present invention relates to a post-processing apparatus and an image forming apparatus, and more particularly, to a post-processing apparatus and an image forming apparatus that can form a square back on a sheet bundle after a half-folding process.

  An image forming apparatus having a function capable of forming an image on a sheet, for example, a multifunction machine having a function of a printer, a copier, or the like, is provided with a post-processing device for performing post-processing on the printed sheet. There is.

  In general, the post-processing apparatus includes a paper transport unit that can transport the paper on which an image is formed, a post-processing mechanism that performs post-processing on the paper transported by the paper transport unit, and a post-processing mechanism that performs post-processing. And a discharge section for discharging the sheet bundle. Here, a sheet on which an image is formed by a multifunction machine or the like is conveyed by a sheet conveying unit, and the sheet is post-processed by a post-processing mechanism. The paper after the post-processing is discharged from the discharge unit to the outside of the apparatus.

  Here, the post-processing mechanism includes a mechanism for performing stapling and a mechanism for performing half-fold processing. When a user tries to make a bundle of sheets into a booklet, it is necessary to instruct the post-processing apparatus to perform a half-folding process after stapling the bundle of sheets. In this case, if the number of sheets included in the sheet bundle is large, the crease is difficult to be formed, and the vicinity of the crease (the back portion) swells. For this reason, when a plurality of sheet bundles are stacked on the discharge unit or the like, the balance may be deteriorated. Therefore, it becomes difficult to stack and stack many paper bundles.

  In order to solve such a problem, a post-processing apparatus that forms a sheet bundle so that the back portion is square-backed is considered (see Patent Document 1). This post-processing apparatus has a mechanism for fixing the vicinity of the back portion of the sheet bundle formed by folding the bundle of sheets subjected to the staple processing and flattening the back portion with a roller. Here, the back portion of the sheet bundle means the back cover portion of the folded sheet bundle.

JP 2001-260564 A

  In the conventional apparatus, in order to flatten the back portion of the folded paper bundle, there are a structure for fixing the paper bundle, a roller for flattening the back portion of the paper bundle, and a mechanism for moving the roller. Necessary. Here, it is necessary to apply a large force to the sheet bundle by the roller when the back portion of the sheet bundle is turned to the back, so that the sheet bundle does not move even if a large force is applied to the sheet bundle from the roller. The structure for fixing the sheet bundle is also large. For this reason, a large space is required to arrange such a structure, and the entire apparatus becomes large, complicated, and expensive.

  An object of the present invention is to prevent an increase in size and complexity of the entire apparatus and an increase in cost when forming a square back on the back portion of a sheet bundle.

  A post-processing apparatus according to a first aspect of the present invention is a post-processing apparatus that performs post-processing on a sheet having an image formed on a surface thereof, and includes a sheet conveying unit, a sheet holding member, a staple processing unit, a half-fold processing unit, A back support member and a roller rotation control unit are provided. The paper transport unit is a part that transports paper having an image formed on the surface. The sheet holding member is a part capable of temporarily holding the sheet conveyed by the sheet conveying unit. The staple processing unit is a part that performs a staple process on a predetermined position of the sheet bundle held by the sheet holding unit. The half-fold processing unit is substantially orthogonal to the first direction and a pressing member that presses a substantially central portion in the sheet transport direction of the sheet bundle subjected to the stapling process in the staple processing unit in a first direction substantially orthogonal to the paper surface of the sheet bundle. This is a portion having a pair of folding rollers that are arranged side by side and sandwich the sheet bundle pressed by the pressing member to bend the sheet bundle. The back support member is disposed so as to face the pressing member and is movable in the first direction and the second direction opposite to the first direction, and is folded in half after the sheet bundle is folded in the middle folding processing unit. It is a member that moves in the second direction so as to press the back portion of the sheet bundle. The roller rotation control unit rotates the pair of folding rollers in a direction in which the sheet bundle is moved in the first direction during the middle folding process, and moves the sheet bundle in the second direction when the backing member presses the back portion of the sheet bundle. This is the part that rotates the pair of folding rollers in the direction of movement.

  In this post-processing apparatus, a sheet having an image formed thereon is conveyed by the sheet conveying unit, and the sheet is temporarily held by the sheet holding unit. At this time, a stapling process is performed on the sheet bundle. Then, the substantially central portion of the sheet in the sheet conveyance direction is pressed by the pressing member, and the sheet is sandwiched between the pair of folding rollers, so that the middle folding process is performed. Thereafter, the back support member presses the back portion of the sheet bundle, and the roller rotation control unit rotates the roller pair in the direction in which the sheet bundle is moved in the second direction. Here, as shown in FIG. 12, when a sheet bundle is conveyed by a pair of rollers, the conveyance speed is greater on the inner side than on the outer side (the side in contact with the roller). That is, V2 (inner speed) in FIG. 12 is larger than V1 (outer speed). For this reason, as the conveying distance by the roller pair increases, as shown in FIG. 13, the outer side is slightly swollen with respect to the inner side. In this state (the state shown in FIG. 13), the back portion of the sheet bundle is pressed by the backing member, so that a square back can be formed.

  Here, in addition to the structure of the center folding process, a back support member is newly provided and a corner back can be formed by controlling the roller and the like, so that the apparatus is increased in size. This can prevent the cost from increasing.

  The post-processing apparatus according to a second aspect of the present invention is the post-processing apparatus according to the first aspect of the present invention, wherein the backrest member has a moving speed that is higher than a speed at which the roller pair conveys the sheet in the second direction by the roller rotation direction control unit. fast.

  Here, the back portion of the sheet bundle can be firmly pressed by the back support member, and a square back can be formed.

  The post-processing apparatus according to a third aspect is the post-processing apparatus according to the first or second aspect, wherein when the pressing member moves in the first direction so as to fold the sheet bundle in half, the backing member is The pressing member moves in the second direction in accordance with the movement of the back member in the second direction while sandwiching the sheet bundle therebetween.

  Here, since the sheet bundle is sandwiched between the backing member and the pressing member, even when the fold portion of the sheet bundle is stapled, the force acting on this point does not become too large, The paper can be prevented from being damaged.

  The post-processing apparatus according to a fourth aspect is the post-processing apparatus according to any one of the first to third aspects, wherein a difference between a moving speed of the backing member and a conveying speed of the sheet bundle of the roller pair in the second direction is obtained. The moving speed of the backing member is increased so as to increase in accordance with the thickness of the sheet bundle.

  Here, by increasing the moving speed of the backing member according to the thickness of the sheet bundle, the force for pressing the sheet bundle can be increased. For this reason, square corners can be formed regardless of the thickness of the sheet bundle.

  The post-processing apparatus according to a fifth aspect is the post-processing apparatus according to any one of the first to fourth aspects, wherein a difference between a moving speed of the backing member and a conveying speed of the sheet bundle of the roller pair in the second direction is obtained. The conveyance speed in the second direction of the sheet bundle of the roller pair is decreased so as to increase in accordance with the thickness of the sheet bundle.

  Here, the force for pressing the sheet bundle can be increased by slowing the conveying speed of the pair of rollers in the second direction according to the thickness of the sheet bundle. For this reason, square corners can be formed regardless of the thickness of the sheet bundle.

  A post-processing apparatus according to a sixth aspect of the present invention is the post-processing apparatus according to any one of the first to fifth aspects of the present invention, further comprising a sheet bundle thickness detecting unit that detects the thickness of the sheet bundle. When the detection result by the sheet bundle thickness detection means is equal to or smaller than a predetermined threshold value, the backrest member is restricted from moving in the second direction.

  Here, when the thickness of the sheet bundle is equal to or less than the threshold value, the balance is not lost when stacking without forming the square back, so that the square back can be formed only when necessary.

  A post-processing apparatus according to a seventh aspect of the present invention is the post-processing apparatus according to any one of the first to sixth aspects, wherein the sheet bundle thickness detecting mechanism includes a pair of rollers whose axis interval changes when the sheet bundle is sandwiched, And an interval detecting means for detecting an interval between the respective shafts of the roller pair.

  Here, the sheet thickness detection mechanism can calculate the thickness of the sheet bundle by detecting the distance between the shafts of the roller pair when the sheet is sandwiched.

  The post-processing apparatus according to an eighth aspect of the present invention is the post-processing apparatus according to any one of the first to seventh aspects, wherein the back member has two or more side surfaces with different areas, and the thickness of the sheet bundle Accordingly, the contact area with the sheet bundle can be changed.

  Here, when forming the square back, the width of the back portion of the sheet bundle can be changed according to the thickness, and the square back of the sheet bundle having different thicknesses can be formed.

  A post-processing apparatus according to a ninth aspect of the present invention is the post-processing apparatus according to any one of the first to eighth aspects, further comprising a discharge unit that discharges the sheet bundle to the outside of the apparatus on the first direction side of the roller pair. After the square spine is formed at the end in the first direction of the sheet bundle, the pressing member moves to the retracted position so as not to prevent the discharge of the sheet bundle, the back support member moves in the second direction, and the roller rotation direction control is performed. The section rotates the roller pair in a direction in which the sheet bundle moves in the first direction.

  Here, it is possible to prevent the backrest member from obstructing the discharge of the sheet bundle in which the corner back is formed.

  An image forming apparatus according to a tenth aspect includes an image forming unit, a fixing unit, and a post-processing device. The image forming unit is a part capable of forming an image based on image data. The fixing unit is a part that fixes the image formed by the image forming unit on the sheet. The post-processing device is a device according to any one of claims 1 to 11, which performs post-processing on a sheet on which an image is fixed.

  According to the present invention, when the square back is formed on the back portion of the booklet, it is possible to prevent the entire apparatus from becoming large and complicated and to prevent the cost from increasing.

1 is an overall schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a partially enlarged schematic view around a photosensitive drum. The surrounding enlarged view of a middle folding processing mechanism. The figure which shows the state which is performing the middle folding process operation. The figure which shows the state which is pressing the back part of a sheet | seat bundle | flux with a back member. The figure which shows the state which the backrest member has moved to the retracted position. 1 is a block diagram illustrating a configuration of an image forming apparatus. The figure which shows the state which forms the square back in the paper bundle. The figure which shows the operation | movement after forming a square back in a paper bundle. The figure which shows the flowchart of a staple processing operation | movement and a square back formation operation | movement. The figure which shows the structure of other embodiment. The figure which shows the rotational speed of a roller, and the shape of a sheet bundle. The figure which shows the rotational speed of a roller, and the shape of a sheet bundle.

[overall structure]
Hereinafter, an image forming apparatus 100 according to an embodiment of the present invention will be described with reference to FIG. Here, FIG. 1 shows an overall outline of an image forming apparatus 100 according to an embodiment of the present invention. The image forming apparatus 100 is for forming an image on a sheet. Further, the image forming apparatus 100 includes the multifunction machine 1 and a post-processing apparatus 10.

[Multifunction machine]
The multifunction device 1 has various functions such as a FAX, a copier, and a printer. The multifunction device 1 is connected to an external computer or the like, and can form an image on a sheet based on image information read from a document or image information sent from a computer.

  As shown in FIG. 1, the multifunction machine 1 includes a document reading unit 2, an image forming unit 3, a transfer unit 4, a paper storage unit 5, a first transport unit 6, and a fixing unit 7 as functional units. And a discharge unit 8. The configuration of each functional unit will be described below.

{Original reading unit}
The document reading unit 2 is a part for reading an image of a document and acquiring image information. The document reading unit 2 is disposed at the top of the multifunction device 1.

{Image forming part}
The image forming unit 3 is a part for forming an image based on image information. The image forming unit 3 is disposed between a sheet storage unit 5 and a document reading unit 2 which will be described later. Further, the image forming unit 3 includes four image forming units 30. The four image forming units 30 are arranged in a line. As shown in FIGS. 1 and 2, the four image forming units 30 include a photosensitive drum 31, a charging device 32, a laser unit 33 (see FIG. 1), a developing device 34, and a toner storage unit. 35 (see FIG. 1), a static elimination device 36, and a drum cleaning device 37. The four image forming units 30 can form yellow, magenta, cyan, and black toner images in order from the right side of FIG. The image forming units 30 have the same configuration. The yellow image forming unit 30 will be described below.

  The photosensitive drum 31 is a member capable of carrying an electrostatic latent image on the surface. Further, the photosensitive drum 31 is rotatable around a rotation axis extending perpendicular to the paper surface of FIG. The photosensitive drum 31 is disposed so as to contact a transfer belt 41 described later.

  The charging device 32 is a device for uniformly charging the surface of the photosensitive drum 31. The charging device 32 is disposed on the upper side of the photosensitive drum 31.

  The laser unit 33 is a device for irradiating the surface of the photosensitive drum 31 with laser light based on image information. The laser unit 33 is disposed above the photosensitive drum 31.

  The developing device 34 is a device capable of supplying a developer to the electrostatic latent image carried on the photosensitive drum 31. Further, each developing device 34 is disposed below the respective laser unit 33. Here, as illustrated in FIG. 2, the developing device 34 includes a developing container 341, a developing roller 342, a supply roller 343, and a stirring member 344.

  The developing container 341 is a container that can store a developer of a color corresponding to each photosensitive drum 31 therein.

  The developing roller 342 is a member for supplying a developer to the photosensitive drum 31. The developing roller 342 is supported by the developing container 341. Further, the developing roller 342 is disposed so as to face the photosensitive drum 31.

  The supply roller 343 is a member for supplying the developer inside the developing container 341 to the developing roller 342. Further, the supply roller 343 is rotatably supported by the developing container 341. Further, the supply roller 343 is disposed in parallel with the developing roller 342.

  The stirring member 344 is a member for stirring the developer in the developing container 341.

  The toner storage portion 35 is a portion for storing toner that can be supplied to the developing device 34. The toner storage unit 35 includes a toner container 351 that can store toner corresponding to the color of each developing device 34. The toner container 351 is connected to the developing device 34 by a supply path (not shown).

  The static eliminator 36 is a device for removing charges on the surface of the photosensitive drum 31. The static eliminator 36 is disposed above the photosensitive drum 31.

  The drum cleaning device 37 is a device for cleaning the developer remaining on the photosensitive drum 31 without being used for the developing operation. The drum cleaning device 37 includes a blade member 371 that contacts the surface of the photosensitive drum 31, and a waste developer storage container 372 that can store toner scraped off by the blade member 371.

{Transcription part}
As shown in FIG. 1, the transfer unit 4 includes a transfer belt 41, four primary transfer rollers 42, a secondary transfer roller 43, and a belt cleaning device 44.

  The transfer belt 41 is a member for transferring an image formed by the image forming unit 3 to a sheet. The transfer belt 41 is a member to which an image is primarily transferred from the photosensitive drum 31. Further, the transfer belt 41 is disposed below the photosensitive drum 31.

  The primary transfer roller 42 is a member for transferring the image on the photosensitive drum 31 onto the transfer belt 41. The primary transfer roller 42 is disposed so as to face the photosensitive drum 31 with the transfer belt 41 interposed therebetween. Further, each primary transfer roller 42 is connected to a voltage application device (not shown). Each primary transfer roller 42 is arranged in parallel with the direction in which the photosensitive drums 31 are arranged.

  The secondary transfer roller 43 is a member for transferring the image primarily transferred from the photosensitive drum 31 to the transfer belt 41 onto a sheet. The secondary transfer roller 43 is disposed so as to face the transfer belt 41 with the paper transport path of the paper transport unit 6 interposed therebetween.

  The belt cleaning device 44 is a device for cleaning toner, paper dust, dust and the like on the transfer belt 41. The belt cleaning device 44 is disposed above the transfer belt member 41.

{Paper storage}
The paper storage unit 5 is a part for storing paper. The paper storage unit 5 is disposed at the lower part of the multifunction machine 1. Further, the paper storage unit 5 has two paper feed cassettes 51. Each paper cassette 51 stores different types (sizes, etc.) of paper. Further, the two paper feeding cassettes 51 are stacked and arranged.

{First transport unit}
The first transport unit 6 is a part for transporting paper to each functional unit. The first transport unit 6 has a paper transport path for transporting paper in the order of the transfer unit 4, the fixing unit 7, and the discharge unit 8 from the paper storage unit 5. The paper transport unit 6 includes a paper transport guide pair 61 that guides the paper transport direction and a plurality of paper transport roller pairs 62 that transport the paper in the paper transport direction.

{Fixing part}
The fixing unit 7 is a part for fixing an image on a sheet. The fixing unit 7 is disposed downstream of the transfer unit 4 in the sheet conveyance direction. The fixing unit 7 includes a heating roller 71 that heats the image on the paper and a pressure roller 72 that presses the image on the paper.

{Discharge unit}
The discharge unit 8 is a part for discharging the sheet to the outside of the multifunction device 1. As shown in FIG. 1, the discharge unit 8 is disposed downstream of the fixing unit 7 in the sheet conveyance direction. The discharge unit 8 has a discharge roller 81. The discharge unit 8 is disposed below the document reading unit 2. The discharge unit 8 further includes a recess 82 that is recessed rightward from the left side surface of the multifunction device 1 in FIG. Then, the sheet is discharged into the recess 82.

[Post-processing equipment]
The post-processing device 10 is a device for performing post-processing on a sheet on which an image is formed. Further, the post-processing apparatus 10 is detachably attached to the side of the multifunction machine 1. Further, the post-processing apparatus 10 includes a housing 11, a second transport unit 12, a staple processing unit 13, a center folding processing unit 14, a first discharge unit 15, and a second discharge unit 16 as functional units. , And a control unit 17 shown in FIG. Each functional unit will be described in detail below.

  The housing 11 is a member in which the center folding processing unit 14, the staple processing unit 13, and the like can be disposed. In addition, a protrusion that fits into the recess 82 of the multifunction device is formed in the housing 11, and a passage port 111 through which the sheet discharged from the discharge portion 8 of the multifunction device 1 can pass is formed in the protrusion. Yes.

  The second transport unit 12 is a part for transporting a sheet that has passed through the passage port 111 and entered the housing 11 to each functional unit. The second transport unit 12 has a plurality of pairs of rollers 121 for transporting paper.

  The first discharge unit 15 (see FIG. 1) is a portion that discharges a sheet that has been discharged from the multifunction machine 1 and that is not subjected to post-processing or a sheet bundle that is not subjected to half-folding processing. The first discharge unit 15 is a pair of first discharge rollers 151 for discharging the paper inside the post-processing apparatus 10 to the outside of the post-processing apparatus 10, and is discharged from the inside of the post-processing apparatus 10 to the outside of the post-processing apparatus 10. And a first discharge tray 152 for supporting paper.

  The staple processing unit 13 is a part for performing a staple process on the sheet bundle 19 (see FIG. 3). The staple processing unit 13 is disposed in the middle of the conveyance path branched downward from the middle of the sheet conveyance path toward the first discharge unit 15. The staple processing unit 13 binds one end or a substantially central portion of the sheet bundle 19 in response to a user request. When the staple processing is performed on the sheet bundle 19, the sheet bundle 19 is moved to the staple position by the second transport unit 12.

  The middle folding processing unit 14 is a part for performing middle folding processing on the paper. Further, the center folding processing unit 14 is disposed below the stapling processing unit 13 and downstream in the paper transport direction. Here, FIG. 3 shows a partially enlarged view of the half-fold processing unit 14. As shown in FIG. 3, the middle folding processing unit 14 includes a folding blade 141, a pair of folding rollers 142, a paper support tray 143, and a back support member 144.

  The sheet support tray 143 is a member for supporting the end portion of the sheet bundle 19 that performs the folding process.

  The folding blade 141 is a member that extends in a direction substantially orthogonal to the sheet bundle 19 supported by the sheet support tray 143, and is opposite to the folding roller 142 across the sheet bundle 19 supported by the sheet support tray 143. Is located. The folding blade 141 is a plate-like member. Further, the folding blade 141 is a member that can move between the above position, that is, the retracted position (see FIG. 3) and the folding position (the position of the folding blade 141 shown in FIG. 4) located between the pair of folding rollers 142. is there.

  The pair of folding rollers 142 is a member that sandwiches the sheet bundle 19 and folds it in half. The pair of folding rollers 142 is positioned on one side (left side in the figure) of the sheet bundle 19 supported by the sheet support tray 143. For this reason, the pair of folding rollers 142 and the folding blade 141 are disposed on opposite sides of the sheet bundle that is supported by the sheet support tray. Further, the pair of folding rollers 142 is connected to a drive source (not shown), and an arrow C (see FIG. 5) is used to move the paper in a first direction indicated by arrow A and a second direction indicated by arrow B in FIG. And it is rotatable in the direction of arrow D (see FIG. 8). Further, the pair of folding rollers 142 can change the interval between the rollers when the sheet bundle 19 is sandwiched. That is, one roller 142a cannot move, and the rotation shaft of the other roller 142b can move.

  Here, the first direction means a direction along a direction perpendicular to the sheet surface of the sheet bundle 19 supported by the sheet support tray 143 and moving so that the folding blade 141 approaches the pair of folding rollers 142. is doing. That is, it means the direction indicated by the arrow A in FIG. The second direction means a direction opposite to the first direction, that is, a direction 180 degrees from the first direction, and means a direction of an arrow B in FIG. An arrow C direction and an arrow D direction indicate the rotation direction of the pair of folding rollers 142. Further, the arrow C direction is a direction in which the sheet bundle 19 is rotated so as to move in the first direction, in other words, the upper roller rotates clockwise while the lower roller rotates counterclockwise in FIG. Means direction. The direction of arrow D means the direction opposite to the direction of arrow C. Specifically, it means a direction in which the sheet bundle 19 is rotated to move in the second direction, in other words, the upper roller in FIG. 5 rotates counterclockwise, while the lower roller rotates in the clockwise direction. is doing.

  The back support member 144 is a member that presses the sheet so as to sandwich the sheet together with the folding blade 141 when forming a square back in the sheet bundle 19. The back support member 144 is disposed so as to face the folding blade 141 with the pair of folding rollers 142 interposed therebetween. Furthermore, the back support member 144 is a rectangular plate-shaped member, and the surface facing the folding blade 141 forms a flat end surface. Then, the back support member 144 is moved to the first position (see FIG. 4) separated from the pair of folding rollers 142, and the second position (see FIG. 4) that moves in the second direction from the first position and can contact the sheet bundle 19. 5) and a third position (see FIG. 5) that is moved in the direction of the arrow E perpendicular to the first direction and the second direction and retracted so as not to disturb the discharge when discharging the sheet bundle 19 to the outside of the post-processing apparatus 1. 6)).

  The second discharge unit 16 is a part that discharges the sheet bundle 19 that has been subjected to the folding process. Further, the second discharge unit 16 is provided on the side of the middle folding processing unit 14. Further, the second discharge unit 16 has a second discharge tray 161 on which the sheet bundle 19 subjected to the folding process can be stacked.

  FIG. 7 shows a block diagram of the image forming apparatus 1. The control unit 17 includes a storage unit 171 and a CPU. The control unit 17 includes a sheet bundle thickness detection unit 172, a square spine formation operation execution determination unit 173, a roller rotation control unit 174, and a back member movement control unit 175 by executing a program. ing.

  The sheet bundle thickness detection unit 172 is a part that detects the thickness of the sheet bundle 19. Further, the sheet bundle thickness detection unit 172 includes an interval detection unit 172a. The interval detection unit 172a is a portion that detects an interval between the pair of folding rollers 142 in a state where the sheet bundle 19 is sandwiched. For example, the interval detection unit 172a detects the interval T between the rotation axis of one roller 142a (see FIG. 4) and the rotation axis of the other roller 142b (see FIG. 4) in a state where the sheet bundle 19 is sandwiched. It is determined that the detection result by the interval detection unit 172a is a value corresponding to the thickness of the sheet bundle 19.

  The square spine formation operation execution determination unit 173 is a part for determining whether or not to perform a square spine formation operation. Further, the corner spine formation operation execution determination unit 173 determines whether or not the sheet bundle 19 is thicker than a predetermined threshold stored in the storage unit 171, and the sheet bundle 19 is thicker than the threshold. In such a case, it is determined that the spine forming operation can be performed. On the other hand, when the thickness of the sheet bundle 19 is smaller than the threshold value, the square back forming operation execution determination unit 173 determines that the square back forming operation cannot be executed, and the back support member movement control unit 175 determines the back support member 144. The movement from the third position (position shown in FIG. 6) is restricted.

  The roller rotation control unit 174 is a part for controlling the rotation of the pair of folding rollers 142. Specifically, the roller rotation control unit 174 rotates the pair of folding rollers 142 in the direction of arrow C in FIG. 4 (the direction in which the sheet bundle 19 is moved in the first direction) when folding the sheet bundle 19. When forming the square back on the back portion of the sheet bundle during the corner back forming operation, the pair of folding rollers 142 is moved in the direction of arrow D in FIG. 8 (the direction in which the sheet bundle 19 is moved in the second direction). Rotate. When the sheet bundle 19 is discharged, the roller rotation control unit 174 rotates the pair of folding rollers 142 in the direction of arrow C. Further, the roller rotation control unit 174 increases the difference between the speed at which the pair of folding rollers 142 conveys the sheet bundle and the movement speed of the backing member 144 as the value of the detection result of the sheet bundle thickness detection unit 172 increases. The rotational speed of the pair of folding rollers 142 is decreased so as to increase.

  The back support member movement control unit 175 is a part that controls the moving direction of the back support member 144 and the speed at the time of movement. Further, the back support member movement control unit 175 performs the second operation from the first position (see FIG. 4) so as to press the back portion of the sheet bundle 19 folded in half by the folding blade 141 during the square back forming operation. Move to position (see FIG. 5). Further, when ejecting the sheet bundle, the backrest member movement control unit 175 moves from the second position (see FIG. 5) to the first position and the third position moved in the direction of the arrow E perpendicular to the second direction (FIG. 6). The back support member 144 is moved to (see). Further, the back support member movement control unit 175 controls to move the back support member 144 at a speed faster than the conveyance speed of the sheet bundle 19 by at least one pair of folding rollers 142.

[Operation]
Next, the operation of the multifunction device 1 will be described.

  When an image of a document is read by the document reading unit 2 and image information is acquired or image information is sent from a computer connected to the outside of the multi-function device 1, the image is electrostatically applied on the photosensitive drum 31 based on the image information. A latent image is formed. Specifically, the surface of the photosensitive drum 31 is charged by the charging device 32, and laser light is irradiated from the laser unit 33 to the photosensitive drum 31 based on the image information. When the electrostatic latent image is formed on the photosensitive drum 31 in this way, the developer is supplied from the developing roller 342 of the developing device 34 to the electrostatic latent image. When the developer is supplied from the developing device 34 to the electrostatic latent image, a toner image is formed on the photosensitive drum 31.

  Then, the toner image on each photosensitive drum 31 is transferred to the transfer belt 41. Then, the toner image on the transfer belt 41 is transferred to a sheet. The sheet on which the toner image is transferred is conveyed to the fixing device 7 by the sheet conveying unit 6. After the toner image is fixed on the paper by the fixing device 7, the toner image is conveyed to the discharge unit 8. The sheet conveyed to the discharge unit 8 is discharged out of the multifunction machine 1.

[Folding processing operation, stapling processing operation and square spine forming operation]
A flowchart of the staple processing operation and the corner spine forming operation is shown in FIG. The operation of the post-processing apparatus will be described with reference to the flowchart of FIG. In the following example, a case where a sheet is conveyed vertically will be described.

  The sheet discharged to the outside of the multifunction device 1 by the operation of the multifunction device 1 enters the inside of the post-processing device 10 through the passage port 111 (S1). Then, it is determined whether or not a staple processing instruction or a half-fold processing instruction has been made (S2). When the staple processing command and the middle folding processing command are not issued (NO in S2), the second transport unit 12 transports the sheet to the first discharge unit 15. The sheet conveyed to the first discharge unit 15 is discharged from the first discharge unit 15 to the outside of the post-processing apparatus 10 and is stacked on the first discharge tray 152.

  On the other hand, when at least one of the staple processing command and the half-fold processing command is issued (YES in S2), the sheet is transported to the staple processing unit 13 by the second transport unit 12. At this time, it is determined whether or not the command is a staple processing command (S3). If it is a staple processing command (YES in S3), the staple processing is performed on the sheet bundle 19 according to the command (S4). Here, when a booklet is created from a plurality of sheets, stapling is performed on a substantially central portion of the sheet bundle 19. On the other hand, if the command is not a staple processing command (NO in S3), the paper is conveyed to the paper support tray 143 and held until a predetermined number of sheets are collected in the paper support tray. When a predetermined number of sheets (sheet bundle 19) are collected in the sheet support tray, the folding operation is performed on the sheet bundle 19 after step 6.

  It is determined whether or not the sheet bundle 19 that has undergone stapling processing has been subjected to a half-folding processing command (S5). If the middle-folding processing command has not been issued (NO in S5), the paper that has undergone stapling processing is determined. The bundle 19 is returned to the second transport unit 12 by a transport roller (not shown), transported to the first discharge unit 15 by the second transport unit 12, and discharged from the first discharge unit 15. On the other hand, when a half-fold processing command has been issued (YES in S5), the sheet bundle is conveyed to the sheet support tray 143, and the processes in and after step 6 are performed.

  For the sheet bundle 19 of the job for which the half-fold processing command has been issued, the thickness of the sheet bundle 19 is detected (S6). Specifically, the folding blade 141 moves by a predetermined distance in the first direction. With the movement of the folding blade 141, the sheet bundle 19 is in a state where the central portion in the transport direction is slightly bent. At this time, the pair of folding rollers 142 can increase the distance between them. In this state, the distance between the pair of folding rollers 142 is detected by a sensor (not shown), and the thickness of the sheet bundle 19 is calculated from the distance between the pair of folding rollers 142. That is, T in FIG. 4 is detected, and the thickness of the sheet bundle is calculated from T.

  Then, it is determined whether or not the thickness of the sheet bundle 19 is larger than the threshold value stored in the storage unit 171 (S7). If it is determined that the thickness of the sheet bundle 19 is equal to or less than the threshold value (NO in S7), it is determined that the square spine forming operation is not necessary, and only the half-folding processing operation is performed (S10). Specifically, the folding blade 141 that has moved by a predetermined distance further moves in the first direction, and the folding blade 141 presses the substantially central portion in the transport direction of the sheet bundle 19. Here, the predetermined distance means a specific distance between the retracted position (position in FIG. 3) and the position where the sheet bundle 19 contacts the backrest member 144. At this time, as the folding blade 141 moves, the pair of folding rollers 142 sandwich the sheet bundle 19 while rotating in the direction of arrow C in FIG. Folded. At this time, the backrest member 144 is retracted from the second position to the third position (see FIG. 6). Thereafter, the pair of folding rollers 142 further rotate in the direction of arrow C, and the sheet bundle 19 is discharged onto the second discharge tray 161.

  On the other hand, when the thickness of the sheet bundle 19 is equal to or greater than the threshold value (YES in S7), a square spine forming operation is performed. Specifically, the folding blade 141 moved by a predetermined distance further moves in the first direction so as to press the substantially central portion in the longitudinal direction of the sheet bundle 19. At this time, the sheet bundle 19 is folded in half by sandwiching the sheet bundle 19 while the pair of folding rollers 142 rotate in the direction of the arrow C at the same time.

  When the sheet bundle 19 is folded in two, the back support member 144 moves while sandwiching the sheet bundle 19 between the folding blade 141 in the second direction from the second position toward the first position, and at the same time a pair of sheets. The folding roller 142 rotates in the direction of arrow D in FIG. Simultaneously with the movement of the back support member 144 in the second direction, the folding blade 141 also moves in the second direction (the direction of arrow B). At this time, the moving speed of the backing member 145 and the rotating speed of the pair of folding rollers 142 are determined based on the thickness of the sheet bundle 19 (S8), and the moving speed of the backing member 144 is determined by the pair of folding rollers. The speed is faster than the sheet transport speed of 142. At this time, as shown in FIG. 8, the pair of folding rollers 142 tries to move the sheet bundle 19 in the direction of arrow B, and the backing member 144 tries to press the back portion of the sheet bundle 19 in the direction of arrow B at a higher speed. To do. Therefore, as shown in FIG. 8, the sheet bundle 19 is formed with a square back and is folded halfway (S9). When the square back is formed in the sheet bundle 19, the folding blade 141 further moves in the second direction, and the backrest member 144 moves in the first direction. Further, the pair of folding rollers 142 rotate in the direction of arrow C, and convey the sheet bundle 19 in the first direction (see FIG. 9). Thereafter, the back support member 144 is retracted from the second position to the third position (see FIG. 6), and the sheet bundle 19 having the square back formed thereon is discharged onto the second discharge tray 161.

[effect]
Since the back portion of the sheet bundle 19 is formed with a square back, the balance is good even when a plurality of paper bundles 19 are stacked and stacked, and the possibility of collapsing is reduced as compared with the paper bundle 19 without the square back. I can do it. Further, since the square back can be formed without adopting a complicated configuration when the sheet bundle 19 is folded in two, it is possible to prevent the entire apparatus from becoming large and complicated due to the formation of the square back. Further, it is possible to prevent the cost from increasing.

  Since the thickness of the sheet bundle 19 can be detected by using a pair of folding rollers 142, it is not necessary to separately provide a sensor or the like for directly detecting the thickness of the sheet bundle 19, thereby preventing an increase in cost. it can. Furthermore, since the back support member 144 can move to the third position when the sheet bundle 19 is discharged, the back support member 144 can be prevented from obstructing the discharge of the sheet bundle 19.

  Then, the stapling process is performed at a substantially central portion in the conveyance direction of the sheet bundle 19, and the stapling process is performed by the folding blade so that the stapling process is performed not only by the back support member 174 but also by the folding blade. Can be prevented from being damaged.

[Other Embodiments]
(A) In the above embodiment, a plate-like member is used as the back support member 144, but the present invention is not limited to this, and the area of the end face facing the folding blade, that is, the area of the end face for forming the square back. For example, a member having a plurality of side surfaces with different areas as shown in FIG. 11 may be used. Here, the back support member shown in FIG. 11 is formed of a plate-like member having a step extending in parallel with the rotation axis of the folding roller and having a different thickness on both sides thereof, and is rotated in parallel with the rotation axis of the folding roller. It can rotate around its axis. Then, the back support member movement control unit determines which side of the back support member is to be formed according to the thickness of the sheet bundle.

  The back support member is moved by driving the rotating shaft in the first direction, the second direction, and the third direction perpendicular thereto.

  (B) In the above embodiment, the thickness of the sheet bundle is detected by the distance between the pair of folding rollers. However, the present invention is not limited to this, and the thickness of the sheet bundle is calculated by calculating from the number of printed sheets. You may ask for it.

  (C) In the above-described embodiment, the roller rotation control unit 174 controls the rotation speed of the pair of folding rollers 142, so that the detection result of the sheet bundle thickness detection unit 172 becomes larger, the pair of folding rollers Although the control is performed so that the difference between the conveyance speed of the sheet bundle 142 and the movement speed of the back support member 144 is increased, the present invention is not limited to this, and the back support member movement control unit 175 controls the back support member 144. By increasing the moving speed, the difference between the moving speed of the pair of folding rollers 142 and the moving speed of the backing member 144 increases as the value of the detection result of the sheet bundle thickness detecting unit 172 increases. Anyway.

  (D) In the above embodiment, an example in which the post-processing device 10 is attached to the multifunction machine 1 is illustrated. However, the present invention is not limited to this, and a post-processing device such as a copier or the like that can form an image on a sheet is used. May be attached.

1 MFP (image forming device)
3 Image forming unit 7 Fixing unit 10 Post-processing device 12 Second transport unit (paper transport unit)
13 Staple processing unit 14 Folding processing unit 100 Image forming apparatus 141 Folding blade (pressing member)
142 A pair of folding rollers (a pair of folding rollers)
143 Paper support tray (paper holding part)
144 Backing member 172 Sheet bundle thickness detector (sheet bundle thickness detector)
172a Interval detection unit (interval detection means)
174 Roller rotation controller

Claims (10)

A post-processing apparatus that performs post-processing on a sheet having an image formed on a surface thereof,
A paper transport unit for transporting paper on which an image is formed on the surface;
A paper holding unit capable of temporarily holding the paper conveyed by the paper conveying unit;
A staple processing unit that performs a staple process on a predetermined position of the sheet bundle held by the sheet holding unit;
A pressing member that presses a substantially central portion in the sheet conveyance direction of the sheet bundle subjected to the stapling process in the staple processing section in a first direction substantially orthogonal to the paper surface of the sheet bundle, and arranged in a direction substantially orthogonal to the first direction. A folding roller pair that sandwiches the sheet bundle pressed by the pressing member and folds the sheet bundle,
The sheet bundle is disposed so as to face the pressing member, is movable in a second direction opposite to the first direction and the first direction, and the sheet bundle is folded in two by the middle folding processing unit. A backrest member that moves in the second direction so as to press the back portion of
The folding roller pair is rotated in a direction to move the sheet bundle in the first direction during the middle folding process, and the sheet bundle is moved in the second direction when the backrest member presses the back portion of the sheet bundle. A roller rotation control unit that rotates the pair of folding rollers in a direction to be moved to
A post-processing apparatus. The backrest member has a higher moving speed when the roller pair moves in the second direction than the speed when the roller pair conveys the paper in the second direction,
The post-processing apparatus according to claim 1. When the pressing member moves in the first direction so as to fold the paper bundle in half, the back support member moves in the second direction while sandwiching the paper bundle with the pressing member,
The pressing member moves in the second direction in accordance with the movement of the backrest member in the second direction.
The post-processing apparatus according to claim 1 or 2. As the thickness of the sheet bundle increases, the movement speed of the back support member increases so that the difference between the movement speed of the back support member and the conveyance speed of the sheet bundle of the roller pair in the second direction increases. To
The post-processing apparatus according to any one of claims 1 to 3. As the thickness of the sheet bundle increases, the difference between the moving speed of the backing member and the conveyance speed of the pair of rollers in the second direction increases so that the second bundle of the roller pair has the second speed. Slow down the conveyance speed in the direction,
The post-processing apparatus according to any one of claims 1 to 4. A sheet bundle thickness detecting means for detecting the thickness of the sheet bundle;
When the detection result by the sheet bundle thickness detection means is not more than a predetermined threshold, the backrest member is prohibited from moving in the second direction.
The post-processing apparatus according to any one of claims 1 to 5. The sheet bundle thickness detecting means includes
The roller pair in which the distance between the shafts changes when the sheet bundle is sandwiched;
An interval detecting means for detecting an interval between the respective axes of the roller pair;
The post-processing apparatus of Claim 6 provided with. The backrest member has two or more side surfaces with different areas, and the contact surface with the sheet bundle can be changed according to the thickness of the sheet bundle.
The post-processing apparatus according to claim 6 or 7. A discharge unit for discharging the sheet bundle to the outside of the apparatus on the first direction side of the roller pair;
After a square spine is formed at the end in the first direction of the sheet bundle,
The back support member moves to a retracted position so as not to prevent paper discharge,
The pressing member moves in the second direction;
The roller rotation control unit rotates the roller pair in a direction in which the sheet bundle moves in the first direction;
The post-processing apparatus according to any one of claims 1 to 8. An image forming unit capable of forming an image based on image data;
A fixing unit for fixing an image formed by the image forming unit to a sheet;
A post-processing device according to any one of claims 1 to 9, wherein post-processing is performed on a sheet on which an image is fixed;
An image forming apparatus.

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