JP4722786B2 - Sheet processing device - Google Patents

Description

  The present invention relates to a sheet processing apparatus such as a sheet folding apparatus, and more particularly to a sheet processing apparatus that can perform tri-fold processing on a sheet while having a simple configuration.

  2. Description of the Related Art Conventionally, a sheet folding apparatus that performs a tri-fold process on a sheet (including a sheet bundle) is known (see Patent Document 1). This sheet folding apparatus includes first, second, and third folding rollers in a Z-folding processing portion, and these rollers have a large-diameter portion in the axial direction thereof. Each roller is provided with a total of three regions having a large roller diameter (that is, a large-diameter portion) at the sheet conveyance center portion and the sheet conveyance both end portions. The first to third folding rollers secure a clearance for the pressure of the sheet due to the sheet folding pressure by reducing the contact area of the sheet with the roller when the sheet is sandwiched at the nip portion. Configured to prevent occurrence.

  As described above, the sheet folding apparatus includes the three rollers, the first to third folding rollers, to perform the tri-folding process, thereby preventing folding and preventing instability and conveyance failure when stacking sheets. It is configured as a stable and highly accurate dedicated device that is less likely to cause problems.

  Here, with reference to FIG. 5, the three-fold process by the sheet folding apparatus will be described. FIG. 5 is a schematic side view for explaining the operation of the conventional sheet folding apparatus, and (a) to (e) show respective processes for sequentially folding the conveyed sheet into three.

  That is, in the sheet folding apparatus, as shown in FIG. 5A, first to third folding rollers 901 to 903 are disposed between the first folding path 907 and the second folding path 908. . The first folding roller 901 and the second folding roller 902, and the second folding roller 902 and the third folding roller 903 are disposed in pressure contact with each other.

  As shown in FIG. 5A, when the leading edge of the sheet S conveyed to the first folding path 907 comes into contact with the first sheet stopper 904, the sheet S is moved to the rear side by the conveying roller pair 906. Pressed further. For this reason, the sheet S swells toward the nip portion between the first folding roller 901 and the second folding roller 902 that rotate in opposite directions while being in contact with each other. As shown in FIG. 5B, when the bulging portion is drawn into the nip portion, the sheet S is folded at the front side portion, and the folding portion is second as shown in FIG. It is sent to the folding path 908.

  When the leading edge of the folded sheet S comes into contact with the second sheet stopper 905 in the second folding path 908, the sheet S is further fed at the rear part by the first and second folding rollers 901 and 902. As a result, as shown in FIG. 5 (d), the sheet S bulges to the nip portion side between the second folding roller 902 and the third folding roller 903, and this bulging portion is drawn into the nip portion. Folded as shown in FIG. By discharging the sheet S as it is, the sheet S is subjected to a tri-fold process in which two portions at approximately equal distances from both ends are respectively folded.

JP 2002-193544 A

  However, in the sheet folding apparatus disclosed in Patent Document 1, for the purpose of performing the tri-folding process, a dedicated tri-folding in which three folding rollers, the first to third folding rollers 901 to 903, are arranged close to each other. The structure of was required. For this reason, it is necessary to provide a relatively expensive three folding rollers 901, 902, and 903 and a complicated driving device for driving these three folding rollers 901 to 903, which increases the number of parts, As a result, the manufacturing cost may increase.

  The present invention has been made in view of the above circumstances, and can be applied not only to a dedicated device but also to a general-purpose device. It is possible to reduce the number of parts, particularly the number of folding rollers, thereby reducing the manufacturing cost. An object of the present invention is to provide a sheet processing apparatus configured to solve the above-described problems.

The present invention includes a sheet conveying path, a rotatable folding roller pair and a second direction to return the sheet in a first direction and the sheet conveyance path for applying the fold to the pull the sheet from the sheet conveying path Write-sheet, wherein from the nip portion of the pair of folding rollers hand sheet conveying path is movable between a first position spaced apart a predetermined distance, and a second position adjacent to said pair of folding rollers side than the first position, and a member out can be butt protruding toward the front Symbol nip portion and the stopper member, the sheet before Symbol sheet conveying path capable of abutting the leading edge of the sheet to be conveyed to the sheet conveying path, the stopper member In the first position , the pair of folding rollers is rotated in the first direction, the protruding member is protruded toward the nip portion, and the first end of the sheet comes into contact with the stopper member. Fold After form, wherein the pair of folding rollers is rotated in the second direction back to the sheet to the sheet conveying path, further, in the state in which switches the stopper member to the second position, the said folding roller pair first is characterized in Rukoto forming form a second fold in the sheet of the ejection member is rotated in one direction protrudes toward the nip portion.

  According to the present invention, a pair of folding rollers composed of two rollers and a stopper member that abuts the leading end of the sheet at different positions are arranged corresponding to the sheet conveying path, and perform a preset operation on them. With this, it is possible to perform an appropriate tri-fold process on the sheet. Thus, while the conventional three-folding process requires three relatively expensive folding rollers, the present invention can execute the same three-folding process with only two folding rollers. Is greatly simplified and can be applied not only to a dedicated device but also to a general-purpose device. Therefore, it is possible to reduce the number of various parts including a relatively expensive folding roller and to reduce the manufacturing cost.

  Hereinafter, an embodiment of a sheet folding apparatus as a sheet processing apparatus according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a side view schematically showing the configuration of the sheet folding apparatus in the present embodiment.

  As shown in FIG. 1, a sheet folding apparatus (sheet processing apparatus) 2 is used in a state where it is connected to an image forming apparatus 1 such as a copying machine, a printer, or a printing apparatus. The image forming apparatus 1 includes a paper discharge roller 1a and a paper discharge roller 1b that is pressed against the paper discharge roller 1a to discharge a sheet on which image formation or the like has been performed to the sheet folding device 2 side. ing.

  The sheet folding device 2 includes a sheet introducing portion at the upper part of the frame 8 so as to face the nip portion between the sheet discharge roller 1a and the sheet discharge roller 1b. An inlet flapper 3 that is rotatably supported as a center is provided. The inlet flapper 3 is connected to an inlet solenoid (not shown), and is switched to the regular mode or the stack mode by turning ON / OFF the power supplied to the inlet solenoid, that is, the discharge guide 4 and the first guide. Switching of the route to any one of the conveyance routes 201 is executed.

[Stack mode configuration]
A stacker discharge roller 5 and a stacker discharge roller 6 are disposed on the downstream side of the sheet discharge guide 4. A stacker tray 7 for stacking sheets discharged from the stacker discharge roller 5 is disposed on the upper side of the frame 8 so as to protrude outward. A sensor 84 for detecting the sheet is disposed in the paper discharge guide 4.

[Composition of copy mode]
When the sheet is discharged from the nip portion between the discharge roller 1a and the discharge roller 1b on the image forming apparatus 1, the sheet is guided by the flapper 3 rotated to the position indicated by the solid line in FIG. It is introduced into the guides 11 and 12. On the downstream side of the sheet guides 11 and 12 in the sheet conveying direction, a conveying roller 13 that rotates about a rotation shaft 13a and a conveying roller 14 that is pressed against and pressed against the conveying roller 13 are disposed.

  Upper sheet guides 34 and 35 are arranged so as to continue from the sheet guides 11 and 12. An upper switching flapper 15 and a lower switching flapper 16 are disposed inside the upper sheet guides 34 and 35. A switching solenoid (not shown) is connected to the upper switching flapper 15 and the lower switching flapper 16. When the corresponding switching solenoid is turned ON or OFF by an electrical signal, the upper switching flapper 15 or the lower switching flapper 16 is configured to be switched between the one-dot chain line position and the solid line position in FIG.

  The sheet guides 11, 12, 34, and 35 described above constitute a first conveyance path 201 with the sheet guides 20 and 21 that are positioned below in the drawing. In the first conveying path 201, elastic rollers 17a and 22a made of a sponge-like rubber material are disposed. The elastic members 17d and 22d are arranged in a state of being elastically biased at positions facing the elastic rollers 17a and 22a, respectively.

  A staple unit 18 provided with a staple needle and a motor (not shown) is disposed inside the elastic roller 17a. The stapling unit 18 is configured to be swingable about a rotating shaft 18a, and its operation is controlled by a CPU 200 as control means. An anvil 19 is disposed on the seat guide 21 so as to face the staple unit 18. The anvil 19 has a mold surface 19a, and has a function of crushing the staple bundle with the tip end of the staple being guided by the mold surface 19a when the sheet bundle is stapled by the staple 18.

  The above-described sheet guides 20 and 21 are disposed on the downstream side of the staple unit 18, and a width adjusting member 24 is disposed on the sheet guides 20 and 21. The width adjusting member 24 is configured to hold both sides of the sheet conveyed into the first conveying path 201 and align the sheets. Prior to sheet processing by the staple unit 18 or the like, the CPU 200 Operated by a signal from

  A sheet stopper 23 as a stopper member is disposed below the width adjusting member 24 in the drawing. The sheet stopper 23 is a member that positions the sheet in the first conveyance path 201 by bringing the leading end of the sheet that has entered between the sheet guides 20 and 21 into contact therewith. A sensor 63 that detects the lowermost position of the sheet stopper 23 is disposed near the lowermost portion of the first conveyance path 201.

  The sheet stopper 23 is configured to move along the sheet guides 20 and 21 in the direction of the arrow a for sheet positioning when stapling with the staple unit 18 and sheet positioning during sheet folding processing. Has been. A motor 23c that is controlled by the CPU 200 is disposed in the vicinity of the sheet guides 20 and 21, and a rack 23d is formed on the sheet stopper 23 so as to extend in the vertical direction and extend toward the motor 23c. ing. A rack and pinion is configured by meshing with the rack 23d and a pinion gear 23b fixed to the rotating shaft of the motor 23c. The sheet stopper 23 has a pair of upper and lower rollers 23a inside the rack 23d, and these rollers 23a are guided in guide grooves (not shown) formed in the frame 8 so as to be in the direction of arrow a. It can be moved smoothly. A leading edge detection sensor 85 that detects the leading edge of the sheet that has been conveyed through the first conveyance path 201 is disposed at the center of the sheet guides 20 and 21.

  A second conveyance path 202 is branched from the middle of the first conveyance path 201. A pair of upper and lower folding rollers 26 and 27 (hereinafter referred to as folding roller pairs 26 and 27) that are controlled by the CPU 200 and pressed against each other with a predetermined pressure are provided on the branching portion 203 side of the second conveyance path 202. Is called). On the left side of the pair of folding rollers 26 and 27, a discharge guide 28 that constitutes the second transport path 202 is disposed. The discharge guide 28 guides a sheet (or a sheet bundle) discharged to the discharge tray 32 side through the pair of folding rollers 26 and 27 between the nip between the discharge roller 30 and the roller 31.

  A protruding unit 25 having a protruding member 25 a is disposed at a position facing the branching portion 203 of the second conveyance path 202. The protruding member 25a is formed long (at least about the width of the sheet) in the back-to-front direction of FIG. In the vicinity of the protrusion unit 25, a motor 73a for moving the protrusion member 25a toward and away from the nip portion of the pair of folding rollers 26 and 27 is disposed. The ejecting unit 25 drives the motor 73a controlled by the CPU 200 so that the projecting member 25a is moved from the opening 37b formed in the sheet guide (guide surface) 21 (see FIG. 4) before the sheet folding process is performed. Retract to the outside. Then, when the sheet folding process is executed, the sheet is projected to just before the nip portion of the pair of folding rollers 26 and 27.

  Disposed between the pair of folding rollers 26 and 27 and the discharge roller 30 and the roller 31 is a discharge sensor 29 that detects the front and rear ends of the sheet (sheet bundle). A discharge tray 32 for stacking sheets (sheet bundles) discharged through the nip portion of the discharge roller 30 and the roller 31 is disposed on the lower side of the frame 8.

  A folding roller cover 33 serving as shutter means for opening and closing the branch portion 203 is disposed near the branch portion 203 of the second transport path 202. The folding roller cover 33 covers the space between the pair of folding rollers 26 and 27 and the opening 37a (see FIG. 4) and partitions from the first conveyance path 201, thereby connecting the sheet guide 20 straight in the vertical direction. Accordingly, the sheet conveyed on the first conveyance path 201 functions to prevent inconvenience that the sheet is caught on the folding roller pairs 26 and 27. On the other hand, when the folding operation of the sheet bundle is executed, the driving motor 61 of the folding roller cover 33 is driven under the control of the CPU 200, so that the folding roller cover 33 is branched (that is, the opening 37a). To open.

[Folding roller cover drive mechanism]
Here, a driving mechanism for driving the folding roller cover 33 will be described with reference to FIGS. 1 and 2. FIG. 2 is a plan view showing the pair of folding rollers and the vicinity thereof.

  As described above, the folding roller cover 33 functions to prevent a problem that the leading edge of the sheet that has entered the first conveyance path 201 from between the sheet guides 34 and 35 is caught by the folding rollers 26 and 27. As shown in both figures, the folding roller cover 33 has a plurality of rollers 33a rotatably attached to both ends thereof, and these rollers 33a are guided by grooves (not shown) formed in the frame 8. Thus, the slide movement is performed along the first conveyance path 201.

  Racks 91 are provided at both ends of the folding roller cover 33 (not shown in FIG. 2). Further, the folding roller cover 33 is provided with a shaft 33c along the width direction (the left-right direction in FIG. 2). Pinion gears 33b are fixed to both ends of the shaft 33c, respectively. It rotates together with it. The racks 91 at both ends of the shaft 33c mesh with the two pinion gears 33b.

  A folding roller cover gear 33d is fixed to one end (left side in FIG. 2) of the shaft 33c on the outside of the frame 8. A folding roller cover motor 61 made of a stepping motor is disposed in the vicinity of the folding roller cover gear 33d, and the folding roller cover gear 33d meshes with the pinion gear 62 fixed to the rotating shaft of the motor 61. Yes. Further, a flag is formed on a part of the folding roller cover 33, and when the folding roller cover 33 reaches the home position, the flag is detected by a folding roller cover home sensor (not shown). .

  Therefore, when the folding roller cover motor 61 is rotationally driven, the driving force is transmitted to the pinion gear 33b via the pinion gear 62, the folding roller cover gear 33d, and the shaft 33c. Thereby, the left and right racks 91 are moved, and the folding roller cover 33 is moved in the vertical direction in FIG.

[Operation overview]
Next, an outline of the operation of the sheet folding apparatus 2 according to the present embodiment will be described with reference to FIGS. 1 to 3. FIG. 3 is a schematic side view for explaining the operation of the folding process for the sheet bundle. (A) shows a sheet bundle before folding in the sheet conveyance path, (b) shows a state in which sheets are further collected in the sheet conveyance path, and (c) shows a first fold formed in the sheet bundle. The process to perform is shown.

  First, the sheet S discharged from the image forming apparatus 1 is conveyed by the conveying roller 13 and the elastic rollers 17a and 22a, and the leading end of the sheet S contacts the sheet stopper 23 (see FIG. 1), thereby positioning the sheet bundle. Made. Then, the sheet bundle is stacked so that the center position (half position) of the length (width) in the conveyance direction of the sheet bundle can be stapled by the stapler unit 18. At this time, the folding roller cover 33 is stopped at a position that covers the pair of folding rollers 26 and 27 as shown in FIG. 3A. Therefore, the sheet S conveyed through the first conveyance path 201 is curled. Even if the sheet is bent, the sheet is not caught by the folding roller.

  Next, as shown in FIG. 3B, when a predetermined number of sheets S are stacked on the first transport path 201, the stapler unit 18 thereafter staples the sheet bundle. Then, when the sheet stopper 23 moves downward for the folding operation of the staple-bound sheet bundle, the folding roller cover 33 also moves downward, and this folding roller cover 33 hinders the folding operation of the protruding unit 25. Stop at no position.

Subsequently, the sheet stopper 23 is stopped at a position where the center position of the sheet bundle overlaps the nip portion of the pair of folding rollers 26 and 27. Thereafter, the ejecting unit 25 is operated, and the ejecting unit 25 pushes and feeds the sheet bundle into the nip portion of the folding roller pairs 26 and 27 that are pre-rotated in the first directions A ₁ and A ₂ . Accordingly, as shown in FIG. 3C, the pair of folding rollers 26 and 27 pulls the sheet bundle and performs the folding operation.

  The sheet bundle folded in this way is discharged onto the discharge tray 32 via the discharge roller 30 and the discharge roller 31, thereby completing a series of sheet folding operations related to the folding process.

  Next, the tri-folding process executed by the sheet folding apparatus 2 according to the present invention will be described with reference to FIG. Here, an example of an equally spaced tri-fold process will be described. Although one sheet S will be described instead of the sheet bundle, the following processing can of course be executed similarly on a sheet bundle obtained by bundling a plurality of sheets.

  FIG. 4 is a schematic side view for explaining the operation of the tri-fold process for the sheet. (A) shows the sheet before the folding process in the sheet conveying path, (b) shows the step of forming the first fold on the sheet, and (c) shows the sheet on which the first fold is formed on the sheet conveying path. The state returned to inside is shown. (D) shows the sheet before forming the second crease, (e) shows the step of forming the second crease on the sheet, and (f) shows the sheet after the trifold process.

The sheet folding apparatus 2 has openings 37a and 37b at portions of the first conveyance path 201 facing the sheet guides 20 and 21, and the pair of folding rollers 26 and 27, the sheet stopper 23, and the ejection unit 25 described above. Projecting member 25a. The pair of folding rollers 26 and 27 are disposed at a position facing the opening 37a, and return the sheet S to the first conveyance path 201 in the first directions A ₁ and A _{2 where} the sheet S is drawn from the first conveyance path 201. It is configured to be rotatable in the second direction B ₁ and B ₂ . As shown in FIG. 4C, a shaft 38a is provided at an oblique upper portion of the folding roller 26, and a flapper 38 that rotates about the shaft 38a is fixed to the shaft 38a.

  The sheet stopper 23 is separated from the nip portion 39 of the pair of folding rollers 26 and 27 within the first conveyance path 201 by a first position (FIG. 4A) and from the first position. The position is switched to the second position (FIG. 4 (d)) close to the folding roller pair 26, 27 side. The sheet stopper 23 thus moved and stopped and switched to the first position or the second position makes the leading edge of the sheet S conveyed in the first conveying path 201 abut. The protruding member 25a is disposed at a position facing the opening 37b, and operates to protrude the sheet S in the first conveying path 201 toward the nip portion 39 at a preset timing.

  The first position is a position corresponding to a length of 2/3 from the leading end of the total length L of the sheet S before the folding process in which the leading end is in contact with the sheet stopper 23. Further, the second position is a position corresponding to a length of 1/3 from the leading end of the full length of the sheet S before the folding process in which the leading end is in contact with the sheet stopper 23.

  When the user selects and inputs the size of the sheet S and the tri-fold processing at equal intervals from an operation panel (not shown) provided in the image forming apparatus 1, the information is transmitted to the CPU 200. Under the control of the CPU 200, the following operations are executed.

That is, as shown in FIG. 4A, the driving of the motor 23c under the control of the CPU 200 switches the sheet stopper 23 to the first position corresponding to the length of 2/3 from the front end of the total sheet length L. In this state, the pair of folding rollers 26 and 27 are controlled to rotate in the first directions A ₁ and A ₂ .

Next, as shown in FIG. 4B, the CPU 200 rotates and drives the motor 73a (see FIG. 1) in a state where the pair of folding rollers 26 and 27 are rotated in the first directions A ₁ and A ₂ . The member 25a is controlled to project to the left in the drawing. As a result, the sheet S having the leading end abutted against the sheet stopper 23 is folded at a third portion from the rear end of the entire sheet length L to form a _first fold f ₁ . At this time, when the trailing edge S _{1 of the} sheet S remains 2 mm from the nip point of the nip portion 39 of the pair of folding rollers 26 and 27 (that is, in the branching portion 203), the pair of folding rollers 26 , 27 is stopped. As a result, the sheet S is properly conveyed even when the roller is later rotated in reverse.

As shown in FIG. 4C, the CPU 200 rotates the flapper 38 clockwise about the shaft 38a and rotates the pair of folding rollers 26 and 27 in the second directions B ₁ and B ₂ , so that the sheet S Is controlled to return to the inside of the first conveyance path 201 while being brought into sliding contact with the flapper (sliding contact member) 38. That is, before the reverse rotation of the pair of folding rollers 26 and 27, the flapper 38 that has rotated and waited outside the first conveyance path 201 is driven by a drive mechanism (not shown) based on the control of the CPU 200. Rotate from an initial position indicated by a broken line to an operating position indicated by a solid line. For this reason, the returned sheet S is appropriately guided into the first conveyance path 201. Then, the flapper 38 rotates so as to return to the initial position (the broken line position in FIG. 4C) again when the sheet S is stabilized.

Subsequently, as shown in FIG. 4D, the CPU 200 operates and stops the motor 23c so that the sheet stopper 23 is switched to the second position corresponding to the length of 1/3 from the front end of the total sheet length L. To do. Further, in this state, the pair of folding rollers 26 and 27 are rotated in the first directions A ₁ and A ₂ and the protruding member 25a is operated to protrude. As a result, as shown in FIG. 4E, the sheet S with the leading end abutted against the sheet stopper 23 is folded at a third of the sheet from the leading end of the total sheet length L to form a _second fold line f _2. Is done.

After that, the CPU 200 controls the folding roller pairs 26 and 27 so as to continue to rotate in the first directions A ₁ and A ₂ . As a result, the sheet S (see FIG. 4 (f)) formed with the first and second folds f ₁ and f ₂ and subjected to the three-fold process is discharged through the discharge roller 30 and the roller 31 to the discharge tray 32. Discharged to the top.

  As described above, in the present embodiment, the pair of folding rollers 26 and 27 including two rollers and the sheet stopper 23 that abuts the leading end of the sheet S at different positions are arranged corresponding to the first conveyance path 201. is doing. And it is comprised so that the appropriate tri-fold process with respect to a sheet | seat (or sheet bundle) can be performed only by making them perform the operation | movement set beforehand.

  As described above, the conventional three-folding process requires three relatively expensive folding rollers, but according to the present embodiment, only two folding roller pairs 26 and 27 are used to perform the same three-folding. Processing can be executed. As a result, the structure is greatly simplified and can be applied not only to a dedicated device but also to a general-purpose device. Therefore, the number of various parts including a relatively expensive folding roller can be reduced, and the manufacturing cost can be reduced. It becomes possible to reduce.

1 is a side view schematically showing a configuration of a sheet processing apparatus according to the present invention. The top view which shows a folding roller pair and its vicinity site | part. FIG. 10 is a schematic side view illustrating an operation of folding processing for a sheet bundle. (A) shows a sheet bundle before folding in the sheet conveyance path, (b) shows a state in which sheets are further collected in the sheet conveyance path, and (c) shows a first fold formed in the sheet bundle. The process to perform is shown. It is a schematic side view explaining the operation | movement of the trifold process with respect to a sheet | seat. (A) shows the sheet before the folding process in the sheet conveying path, (b) shows the step of forming the first fold on the sheet, and (c) shows the sheet on which the first fold is formed on the sheet conveying path. The state returned to inside is shown. (D) shows the sheet before forming the second crease, (e) shows the step of forming the second crease on the sheet, and (f) shows the sheet after the trifold process. It is a schematic side view explaining the operation | movement of the trifold process in a prior art. (A) thru | or (e) has shown each process which processes and sequentially folds the conveyed sheet | seat.

Explanation of symbols

2 Sheet processing device (sheet folding device)
21a, 21b Guide surface 23 Stopper member (sheet stopper)
25 Extrusion unit 25a Extrusion member 26, 27 Folding roller pair 37a, 37b Opening portion 38 Flapper 39 Nip portion 200 CPU
201 Sheet transport path (first transport path)
A ₁ , A ₂ first direction B ₁ , B ₂ second direction f ₁ first crease f ₂ second crease S sheet

Claims (3)

A sheet conveyance path ;
A rotatable folding roller pair and a second direction to return the sheet in a first direction and the sheet conveyance path for applying the fold to Write-sheet pull the sheet from the sheet conveying path,
From the nip portion of the pair of folding rollers hand to the sheet conveying path is movable between a first position spaced apart a predetermined distance, and a second position adjacent to said pair of folding rollers side than the first position a stopper member which can be abutted against the leading edge of the sheet to be conveyed to the sheet conveying path,
And a member out can be butt protruding toward the front Symbol nip the sheet before Symbol sheet conveying path,
With the stopper member in the first position , the folding roller pair is rotated in the first direction, and the protruding member is protruded toward the nip portion, so that the leading end of the sheet contacts the stopper member. After forming the first fold, the folding roller pair is rotated in the second direction to return the sheet to the sheet conveying path, and the folding member is switched to the second position. that forms form a second fold in the sheet of the ejection member to rotate the roller pair in the first direction protrudes toward the nip portion,
A sheet processing apparatus. The first position is a position corresponding to a length of 2/3 from the front end of the full length of the sheet before folding with the front end in contact with the stopper member;
The second position is a position corresponding to a length of 1/3 from the front end of the full length of the sheet before the folding process in which the front end is in contact with the stopper member.
The sheet processing apparatus according to claim 1.   After the first fold is formed on the sheet, when the pair of folding rollers is rotated in the second direction to return the sheet to the sheet conveyance path, the rear end of the sheet is moved to the first fold. Provided with a sliding contact member that is slidably guided so as to be positioned on the leading end side of the sheet,
  The sheet processing apparatus according to claim 1 or 2.

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