JP3956874B2 - Sheet binding method and sheet post-processing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet post-processing apparatus that performs post-processing of a sheet on which an image has been output by a sheet pre-processing apparatus such as a copying machine, a printer, or a combination machine thereof. The present invention also relates to a sheet binding method in which a plurality of sheets are stacked to form a sheet bundle after the sheet is creased, and then the sheet bundle is stapled.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a sheet post-processing apparatus (finisher) attached to a sheet pre-processing apparatus such as a copying machine, folds are made at the center of the sheet supplied from the sheet pre-processing apparatus, and the sheets are then stacked. There has been proposed one that performs a saddle stitching process by driving a staple into the fold line (see, for example, Patent Document 1).
[0003]
In this sheet post-processing apparatus, creases are made by a sheet folding unit disposed on the conveyance path in a state where the end portion of the sheet carried into the apparatus is regulated by a regulating plate. Thereafter, the sheet is discharged to the processing tray. Such an operation is performed on a plurality of sheets, and a plurality of sheets are stacked on the processing tray to form a sheet bundle. Subsequently, the sheet bundle is aligned with the end portions regulated by a regulating plate, and then conveyed to a stapler, and staples are driven onto the folds.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-12111
[Problems to be solved by the invention]
However, the sheet state (for example, heat curling or undulation may occur in the sheet in order to fix the toner image on the sheet by the heat and pressure method in the sheet pre-processing apparatus) and the sheet type (for example, normal Due to factors such as paper, thin paper, thick paper, etc., when a crease is made on a sheet, a crease may be formed at a position where the distance from the end of the sheet deviates from a desired distance. In the above configuration, both the crease process and the staple process are performed after the sheet is positioned with reference to the end portion of the sheet, so that there is a possibility that the staple is not driven onto the fold.
[0006]
SUMMARY An advantage of some aspects of the invention is that it provides a binding method in which a staple can be reliably driven onto a fold even for different sheet states and types.
[0007]
Another object of the present invention is to provide a sheet post-processing apparatus having a mode for binding a sheet bundle by such a binding method.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a binding method according to the present invention includes:
In a method of stapling and binding a plurality of sheets,
A step of making a crease on a predetermined portion of each sheet in the sheet folding unit;
Collecting a plurality of creased sheets to form a sheet bundle;
A step of conveying the sheet bundle in a predetermined direction along the conveyance path;
Detecting a fold of the sheet bundle with a detecting means having a detection position on the conveyance path;
And a step of relatively moving the stapler and the sheet bundle based on an output value from the detection means, and driving a staple into the sheet bundle by the stapler.
[0009]
The sheet post-processing apparatus according to the present invention includes:
In a sheet post-processing apparatus having a mode for stapling and binding a plurality of sheets,
A sheet folding unit that creases a predetermined portion of each sheet;
A stacking unit that stacks a plurality of sheets creased by a sheet folding unit in a state in which the end portions are aligned to form a sheet bundle;
Conveying means for conveying the sheet bundle formed by the stacking unit in a predetermined direction along the conveying path;
Detecting means for detecting a fold of the sheet bundle conveyed in the conveying path;
A stapler for driving staples into a sheet bundle conveyed through the conveyance path;
And a control unit for controlling the conveying unit and the stapler so as to move the stapler and the sheet bundle relative to each other based on an output value from the detection unit and drive a stapler needle into a fold of the sheet bundle.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. In this specification, terms indicating directions (for example, “up”, “down”, “right”, “left”, and other terms including these terms) are used. It is intended to indicate direction only and the present invention should not be construed in a limited way by these terms.
[0011]
FIG. 1 shows the entire image processing system 2. The image processing system 2 includes a sheet pre-processing device (hereinafter referred to as a pre-processing device) 4 and a sheet post-processing device (hereinafter referred to as a post-processing device) 6. In the present embodiment, the preprocessing device 4 is a copying machine that reproduces an image of a document on a sheet, and includes an automatic document conveyance unit 8 disposed on a housing 7 that forms the appearance of the system 2, and an automatic document conveyance unit 8. And an optical system 10 for reading a document conveyed from a document feed tray 9 to a document reading position (not shown). The document scanned by the optical system 10 is discharged to the document discharge tray 11 of the automatic document feeder 8.
[0012]
The pre-processing device 4 also outputs an image to the sheet based on image data obtained by reading a document placed on the lower portion of the housing 7 and the sheet feed tray 12 on which the sheets S are stacked and arranged in the approximate center of the housing 7. The image forming unit 14 includes a transport system 16 that transports the paper feed tray 12 to the post-processing device 6 through the image forming unit 14.
[0013]
The post-processing device 6 is a finisher that performs post-processing such as folding a predetermined part of the sheet pre-processed by the pre-processing device 4 or stapling a predetermined number of sheets. In the illustrated example, a part of the post-processing device 6 is provided between the optical system 10 of the pre-processing device 4 and the image forming unit 14, and a part of the post-processing device 6 protrudes from the left side wall of the housing 7.
[0014]
According to such an image processing system 2, predetermined preprocessing (image formation or the like) is performed on the sheet in the preprocessing device 4. Next, the pre-processed sheet is supplied from the pre-processing device 4 to the post-processing device 6, and the post-processing device 6 performs crease processing, stapling processing, and the like.
[0015]
Next, the detailed configuration of the post-processing device 6 will be described with reference to FIGS.
[0016]
As shown in FIG. 1, the post-processing device 6 is provided with a first conveyance path 20 that extends linearly from the right side of the housing to the left side. Along the first conveyance path 20, the sheet is disposed in the vicinity of the right end of the first conveyance path 20 in order from the upstream side to the downstream side along the sheet conveyance direction (hereinafter also referred to as a first forward direction). The first conveying roller pair 22 that receives and conveys the sheet discharged from the pre-processing device 4, the sensor 23 that detects the sheet, the second conveying roller pair 24, and the punch for making a punch hole in a predetermined portion of the sheet In the vicinity of the left end of the unit 26 (the description of the configuration is omitted in the present application), the sheet folding unit 28 for folding a predetermined portion of the sheet, the third conveyance roller pair 30, and the first conveyance path 20. A fourth conveyance roller pair 32 is provided.
[0017]
As shown in detail in FIG. 2, the sheet folding unit 28 is arranged so that the line connecting the rotation axes is parallel to the first conveyance path 20 and slightly below the first conveyance path 20. In addition, a pair of sheet folding rollers 34 capable of rotating in the forward and reverse directions, and an abutting member 36 capable of advancing to the vicinity of the nip portion of the roller pair 34 in the direction orthogonal to the first conveying path 20 are provided. The roller pair 34 and the abutting member 36 are drivingly connected to a motor 38 that can rotate forward and backward.
[0018]
In the present embodiment, the first and second transport roller pairs 22 and 24 are drivingly connected to a common motor 40 that can rotate forward and reverse. One roller of the second transport roller pair 24 is connected to the motor 40 via the clutch 42, and thereby the second transport roller pair 24 is stopped in a state where the motor 40 is driven, and the second transport roller pair 24 is stopped. The sheet S is guided to the sheet folding unit 28 after skew correction is performed by bringing the leading end of the sheet into contact with the nip portion of the conveying roller pair 24.
[0019]
In the present embodiment, the third and fourth transport roller pairs 30 and 32 are drivingly connected to a common motor 44 that can rotate forward and reverse.
[0020]
The motor 38 is a DC motor and is controlled by the controller 46. On the other hand, the motors 40 and 44 are stepping motors and step according to pulses input from the controller 46. The controller 46 also receives a detection signal from the sheet detection sensor 23. Further, the controller 46 is configured so that a standard sheet length L ₀ (for example, 210 mm × 297 mm A4 sheet, which is post-processed by the post-processing device 6, based on a user instruction, is set so that the longitudinal direction of the sheet is parallel to the transport direction. In the case of transporting as described above, information of L ₀ = 297 mm) is transmitted from the preprocessing device 4.
[0021]
Returning to FIG. 1, a second conveyance path 50 that linearly extends diagonally downward from the left side to the right side is disposed on the lower left side of the fourth conveyance roller pair 32. In order to align the ends of a plurality of sheets discharged to the second conveyance path 50 at the right end of the second conveyance path 50, which is obliquely below and to the right of the fourth conveyance roller pair 32, as will be described later. A regulating member 52 is provided. As shown in detail in FIG. 3, on the upper side near the right end of the second conveyance path 50, the sheet is brought into contact with the upper surface of the sheet dropped from the first conveyance path 20 onto the second conveyance path 50. An alignment mechanism 54 is provided for transporting the sheet toward the regulating member 52 so as to ensure that the sheet end is in contact with the regulating member 52. The alignment mechanism 54 includes an endless belt 56 and rollers 58 and 60 that support the belt 56, and the driving roller 58 rotates in the direction of the arrow in the drawing to contact the sheet via the belt 56. The driven roller 60 rotated in the direction of the arrow in the drawing brings the sheet into contact with the regulating member 52. With the above configuration, the right end of the second conveyance path 50 constitutes a stacking unit that stacks sheets in a state where the ends are aligned by the regulating member 52 to form a sheet bundle. As will be described later, when the sheet bundle S1 with the end portions aligned is conveyed obliquely upward (hereinafter referred to as a second forward direction) from the right side to the left side along the second conveyance path 50, the driven roller 60 is configured to be driven by a sheet. Retreats from the position where it touches.
[0022]
On the left end side of the second conveyance path 50, a stapler 62 is disposed for performing staple processing by driving staples into the folds of the sheet bundle S1. Between the stapler 62 and the regulating member 52, a fifth conveyance roller pair 64 for conveying the sheet bundle S1 on the conveyance path 50 in the second forward direction on both sides of the second conveyance path 50. Is arranged. The upper roller of the fifth conveyance roller pair 64 can be retracted from a position close to the second conveyance path 50 so as not to interfere with a sheet falling from the first conveyance path 20 to the second conveyance path 50. It has become. The fifth transport roller pair 64 is drivingly connected to the motor 66. The motor 66 is a stepping motor and steps according to a pulse input from the controller 46.
[0023]
The stapler 62 is disposed below the second conveyance path 50, and a head 68 for passing the staple needles through the sheet bundle S1, and the staples facing the head 68 and penetrating the sheet bundle S1 are bent to form a sheet bundle. And an anvil 70 for binding S1. The head 68 and the anvil 70 of the stapler 62 are controlled by the controller 46 and can move in a direction perpendicular to the second conveyance path 50 between a position where the sheet bundle S1 is clamped and a position where they are separated from each other. It has become.
[0024]
A distance measuring sensor 71 is provided below the second conveyance path 50 in the vicinity of the upstream side of the stapler 62 with respect to the second forward direction. The distance measuring sensor 71 in the present embodiment is an ultrasonic sensor, and a voltage value corresponding to the distance from the sheet bundle (the lower surface thereof) at the detection position on the second conveyance path 50 is temporally transmitted to the controller 46. Output discretely. The distance measuring sensor 71 outputs a higher voltage as the distance is shorter.
[0025]
A sensor 72 for detecting a sheet is provided in the vicinity of the upstream side of the distance measuring sensor 71 with respect to the second forward direction. The detection signal of the sheet detection sensor 72 is input to the controller 46.
[0026]
Near the left end of the second conveyance path 50, a discharge roller pair 74 for discharging the saddle stitched sheet bundle S1 to the discharge tray 73 is provided. The upper rollers of the discharge roller pair 74 can move in accordance with the thickness of the sheet bundle S1, and press the sheet bundle S1. The discharge roller pair 74 is also drivingly connected to a stepping motor 75 that steps according to a pulse input from the controller 46. The discharge roller pair 74, together with the fifth conveyance roller pair 64, also when conveying the sheet bundle S <b> 1 along the second conveyance path 50 in order to set the sheet bundle S <b> 1 at a predetermined position with respect to the stapler 62. Used.
[0027]
In FIG. 1, a tray 76 that protrudes from the left side wall of the housing 7 is for discharging sheets or sheet bundles that the image processing system 2 has pre-processed and post-processed in modes other than the saddle stitching mode. .
[0028]
Next, the operation in the saddle stitching mode of the post-processing device 6 configured as described above will be described with reference to FIGS.
[0029]
First, in step S401, the sheet S that has been pre-processed is guided into the post-processing apparatus 6. The sheet S is conveyed along the first conveyance path 20 until the sheet detection sensor 23 located on the upstream side of the sheet folding unit 28 in the first forward direction detects the rear end (steps S402 and S403). [FIG. 7A]. In step S <b> 404, the controller 46 receives the signal from the sheet detection sensor 23 and stops the rotation of the first to fourth transport roller pairs 22, 24, 30, and 32. As shown in FIG. 7 (a), at the time of stopping, the trailing edge of the sheet S has passed the detection position P ₁ of the sheet detection sensor 23. Controller 46, the first to fourth conveying rollers 22,24,30,32 is reversely rotated, the trailing edge of the sheet S passes the detection position _{P 1} of the sheet detection sensor 23 (step S405, S406) [ Figure 7 (b)], (step S407) after sending in the opposite direction further _{L 1} only the sheet S and the first forward, the rotation of the first to fourth conveying rollers 22,24,30,32 Is stopped (step S408) [FIG. 7 (c)]. The feed amount L ₁ of the sheet S in the reverse direction is determined by the standard sheet length L ₀ specified by the user via a display panel (not shown) attached to the image processing system 2, for example, and the folding position P of the sheet folding unit 28. ₂ (folding position of the first conveying path 20 opposing the nip portion of the roller pair 34) and the detected position _{P 1} of the sheet detection sensor 23 a distance _{L 2} Prefecture _of the _{L 1 = L 0/2-} L 2 Calculated. Controller 46 that enter a predetermined number of pulses to the motor 40 and 44 based on the value of _{L 1,} to rotate the first to fourth conveying rollers 22,24,30,32 predetermined rotation angle in, to move a predetermined amount L ₁ in the right direction of the rear end of the sheet S (the reverse direction). Alternatively, the rotational speed of the motor 40, 44 at the time of conveying the sheet S in the reverse direction at a constant, the controller 46 controls the drive time of the motor 40 and 44 based on the value of L _1, thereby Sheet the rear end in the opposite direction may be allowed to L ₁ moves.
[0030]
Thus, in the crease process, the sheet is positioned with reference to the trailing edge of the sheet. In practice, however, the crease may be made at a position slightly deviated from a desired position due to the state or type of the sheet. Even in such a case, in the present embodiment, the staple can be surely driven onto the fold in the staple processing described later.
[0031]
In step S409, the post-processing device 6 performs a crease process. Specifically, with reference to FIG. 2, 7 (d), the sheet S is disposed at a predetermined position (. The seat portion of the distance L _0/2 from the sheet trailing edge is set to the position P ₂ fold) In this state, the controller 46 controls the motor 38 to move the abutting member 36 downward toward the nip portion of the folding roller pair 34 and rotate the folding roller pair 34 in the arrow direction in the figure. At the same time, the first to fourth transport roller pairs 22, 24, 30, 32 are rotated in the direction of the arrow in FIG. As a result, the sheet S protrudes from the abutting member 36 and is inserted into the nip portion of the folding roller pair 34 while being sandwiched between the folding roller pair 34 to be creased.
[0032]
Thereafter, the controller 46 controls the motor 38 to rotate the pair of folding rollers 34 in the reverse direction and move the abutting member 36 upward. Further, the first to fourth conveyance roller pairs 22, 24, 30, and 32 are rotated forward, and the sheet is conveyed in the first forward direction in the first conveyance path 20 and discharged to the second conveyance path 50 ( Step S410). At this time, the upper roller of the fifth conveyance roller pair 64 is placed at a location away from the second conveyance path 50 (a dotted line position in FIG. 3).
[0033]
Referring mainly to FIG. 3, the first sheet discharged from the first conveyance path 20 via the fourth conveyance roller pair 32 (FIG. 1) has its own weight along the second conveyance path 50. Is stopped at the position where the tip abuts against the regulating member 52. Subsequently, the second sheet is creased in the same manner as the first sheet following the pre-processing, and then discharged to the second conveyance path 50 via the fourth conveyance roller pair 32. The second sheet slides diagonally to the right on the first sheet due to its own weight. At this time, the belt 56 of the aligning mechanism 54 rotates and contacts the upper surface of the second sheet, and the end of the second sheet is surely moved to the position of the regulating member 52, thereby the first sheet. And the second sheet are aligned. By repeating such an operation, that is, the operations in steps S401 to S410 for the third and subsequent sheets, a predetermined number of sheets are stacked on the second conveyance path 50 (step S411). Subsequently, the sheet bundle S1 is conveyed along the second conveyance path 50 and supplied to the stapler 62 (step S412).
[0034]
The operation of supplying the sheet bundle S1 to the stapler 62 will be described in detail with reference to the subroutine of FIG. 6 and FIGS. First, in step S <b> 601, the controller 46 presses the upper roller of the fifth conveyance roller pair 64 against the upper surface of the sheet bundle S <b> 1, rotates the fifth conveyance roller pair 64, and moves along the second conveyance path 50. Then, the conveyance of the sheet bundle S1 in the second forward direction is started [FIG. 8 (a)]. 8 and 10, the dotted line shown at the center of the sheet bundle S1 indicates the position where the crease is provided. Further, among the sheet bundle portions on both sides across the crease, particularly the portion not pressed by the fifth conveying roller pair 64 and / or the discharge roller pair 74 is conveyed in a curled state. 8 to 10 are schematically shown.
[0035]
It passes through the detection position _{P 3} of the tip sheet detecting sensor 72 of the sheet bundle S1 (Step S602) [FIG. 8 (b)], (step S603) further predetermined amount _{L 3} advanced at the time, the controller 46 calculates the distance measurement Measurement by the sensor 71 is started (step 604). This L ₃ is calculated based on the sheet length L ₀ specified by the user and the distance L ₄ between the detection position P ₃ of the sheet detection sensor 72 and the detection position P ₄ of the distance measurement sensor 71. , after the sheet detection sensor 72 is the tip detection, the fold position, as shown in FIG. 8 (c), a conveying amount of the sheet bundle S1 required to reach the detection position P ₄ near the distance measuring sensor 71. The controller 46 inputs a predetermined number of pulses to the motor 66 and / or the motor 75 (FIG. 3) based on the value of L ₄ to rotate the fifth transport roller pair 64 and / or the discharge roller pair 74 by a predetermined rotation. by rotating angle, to move the predetermined amount L ₄ along the second forward direction of the sheet bundle S1 tip. Alternatively, the rotational speed of the motor 66 and / or motor 74 at the time of conveying the sheet bundle S1 in the second forward constant controller 46 controls the drive time of the motor based on the value of L ₄ , thereby may be made to L ₄ moves the sheet bundle S1 tip in a second forward. Such motor control is similarly applied to an operation described later for conveying the crease to a staple position (position to staple the staple).
[0036]
In step S605, the controller 46 determines whether or not the voltage value discretely sent in time from the distance measuring sensor 71 after the start of measurement is larger than the previous voltage value. In the folding unit 28, but the folds are formed so as to be convex downward, as shown in FIG. 9 (a), in a state the convex portion is in the detection position P ₄ of the distance measuring sensor 71, distance sensor Since the distance between 71 and the sheet bundle S1 is minimized, the output voltage value is maximized. However, when a voltage value smaller than the previous voltage value is sent to the controller 46, as shown in FIG. 9B, the sheet bundle S1 is further moved to L ₅ (the crease position and the fold position). the distance between the distance measuring position P ₄₎ are willing. Therefore, controller 46, as the distance _{L 6} between the stapler position _{P 5} and the distance measuring position _{P 4,} further conveys the sheet bundle S1 by L _{7 =} L 6 -L ₃ (step S606), the conveyance of the sheet bundle S1 Stop (step S607) [FIG. 10 (a)]. As a result, the fold position is set to the stapling position P _5. When the folding position reaches the vicinity of the distance measuring position P _4, the sheet bundle S1 is only the right portion of the folding position are conveyed in a state of being pressed to the conveying roller pair 64 of the fifth. That is, the left portion of the crease position is not pressed against the second conveyance path 50 side by a roller or the like, and is therefore conveyed in a curled state so as to protrude upward from the crease position toward the tip. The folding position can be easily determined based on the output voltage value from the distance measuring sensor 71.
[0037]
In the example shown, the fold has reached the tip of the sheet bundle S1 to the discharge roller pair 74 before reaching the stapling position P _5, the discharge roller pair 74, together with the conveying roller pair 64 of the fifth, followed by single Then, the sheet bundle S1 is conveyed.
[0038]
Further, the conveying speed of the measurement interval and the sheet bundle S1 in the distance measuring sensor 71, that the protrusion of the sheet bundle S1 between two consecutive measurements is set so as not to pass through the ranging position P ₄ desirable. However, even if the projections to pass through the ranging position P ₄ is generated, the sheet bundle by the second forward conveying in the opposite direction, once the protrusion distance measuring position P ₄ after setting, the sheet bundle S1 by sending only further L ₆ in the second forward _(distance between the distance measuring position P ₄ and the staple position P _5), can be set crease position in the staple position P _5.
[0039]
Returning to FIG. 5, in step S413, the controller 46 drives the head 68 and the anvil 70 of the stapler 62, and drives the staples onto the folds attached to the substantially central portion of the sheet bundle S1, thereby performing saddle stitching. [FIG. 10 (b)].
[0040]
As described above, the stapling process is performed after detecting the fold position of the sheet bundle on the second conveyance path 50. Therefore, the staple can be reliably driven onto the fold.
[0041]
Finally, in step S <b> 414, the discharge roller pair 74 rotates to discharge the saddle stitched sheet bundle onto the tray 73.
[0042]
The above description relates to an embodiment of the present invention, and the present invention is not limited to this and can be variously modified. For example, in the above-described embodiment, the saddle stitching mode in which a crease is formed in the substantially central portion of the sheet has been described. However, in the scope of the present invention, a crease is formed in another position of the sheet and a staple is driven into the crease position. Is also included.
[0043]
In the above embodiment, the sheet bundle S1 is moved with respect to the stapler 62 after the fold line is detected by the distance measuring sensor 71 in order to match the fold position and the staple position. Instead, the stapler 62 is moved to the second position. The stapler 62 may be configured to move with respect to the sheet bundle S1. In this case, after detecting the crease by the distance measuring sensor 71, the stapler 62 is moved to the crease position and moved in the direction opposite to the second forward direction by L ₇ [FIG. 9B]. Alternatively, both the stapler 62 and the sheet bundle S1 may be moved.
[0044]
Further, although the ultrasonic sensor is used as the distance measuring sensor 71, it is only necessary to detect the distance between the sheet bundle conveyed along the second conveyance path 50 and the height of the fold, and for example, a reflective optical sensor may be used. Good. The present invention is not limited to the distance measuring sensor as long as the position of the fold can be detected.
[0045]
In addition, the sheet creasing process is not limited to the above embodiment.
[0046]
【The invention's effect】
According to the present invention, it is possible to reliably drive the staple needle onto the fold even for different sheet states and types.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an image processing system having an embodiment of a sheet post-processing apparatus according to the present invention.
FIG. 2 is an enlarged view showing a sheet folding unit of the sheet post-processing apparatus of FIG. 1 and its peripheral configuration.
3 is an enlarged view showing a stapler and its peripheral configuration of the sheet post-processing apparatus of FIG. 1. FIG.
FIG. 4 is a flowchart showing a first part of one embodiment of the binding method according to the present invention.
FIG. 5 is a flowchart showing a second part of one embodiment of the binding method according to the present invention.
FIG. 6 is a flowchart showing a subroutine of step S412 in FIG.
FIG. 7 is a process diagram showing a sheet folding operation in an embodiment of a binding method according to the present invention.
FIG. 8 is a process diagram showing a sheet supply operation to staples in an embodiment of a binding method according to the present invention.
FIG. 9 is a process diagram showing a sheet supply operation to staples in an embodiment of a binding method according to the present invention, and shows an enlarged projection formed at a fold position.
FIG. 10 is a process chart showing a sheet supply operation to staples in an embodiment of a binding method according to the present invention.
[Explanation of symbols]
2: image processing system 4: sheet pre-processing device 6: sheet post-processing device 20: first conveying paths 22, 24, 30, 32, 64: conveying roller pair 23, 72: sheet detection sensor 28: sheet folding unit 46 : Controller (control means)
50: Second transport path 62: Stapler 71: Ranging sensor (detection means)
74: Discharge roller pair

Claims (5)

In a method of stapling and binding a plurality of sheets,
A step of making a crease on a predetermined portion of each sheet in the sheet folding unit;
Collecting a plurality of creased sheets to form a sheet bundle;
A step of conveying the sheet bundle in a predetermined direction along the conveyance path;
Detecting a fold of the sheet bundle with a detecting means having a detection position on the conveyance path;
A sheet binding method including a step of relatively moving the stapler and the sheet bundle based on an output value from the detection means, and driving a staple into the sheet bundle with the stapler. In a sheet post-processing apparatus having a mode for stapling and binding a plurality of sheets,
A sheet folding unit that creases a predetermined portion of each sheet;
A stacking unit that stacks a plurality of sheets that are creased by the sheet folding unit in a state where the end portions are aligned, and forms a sheet bundle;
Conveying means for conveying the sheet bundle formed by the stacking unit in a predetermined direction along the conveying path;
Detecting means for detecting a fold of the sheet bundle conveyed in the conveying path;
A stapler for driving staples into a sheet bundle conveyed through the conveyance path;
And a control unit for controlling the conveying unit and the stapler so as to move the stapler and the sheet bundle relative to each other based on an output value from the detection unit and drive a stapler needle into a fold of the sheet bundle. Sheet post-processing device. 3. The sheet post-processing apparatus according to claim 2, wherein the detection means is a distance measuring sensor that measures a distance from the sheet bundle conveyed on the conveyance path. 4. The sheet post-processing apparatus according to claim 2, wherein the conveyance unit is a pair of conveyance rollers disposed on the upstream side of the detection unit with respect to the predetermined direction with the conveyance path interposed therebetween. 5. The sheet post-processing apparatus according to any one of claims 2 to 4, wherein the sheet folding unit folds a substantially central portion of each sheet.

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