JP2001206608A - Sheet post-treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of the fear of breaking the uppermost sheet of the discharged sheaf of sheets due to the characteristic of the discharged sheaf of sheets, in discharging a sheaf of sheets to a discharge tray. SOLUTION: In discharging a stapled sheaf 80 of sheets to an offset tray 11, according to the sheet sheaf characteristic, the lift amount on the forward end side in the discharge direction is adjusted by a lift mechanism 76 to discharge the sheaf of sheets.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided in an image forming apparatus having the functions of copying, facsimile, and printer. The present invention relates to a sheet post-processing apparatus that performs post-processing and discharges sheets, and particularly relates to prevention of disturbance of sheets stacked on a discharge tray.

[0002]

2. Description of the Related Art In recent years, copying machines have been used to automate copying work,
In order to automate post-processing work such as stapling work or punching work on a sheet after copying, it is used in combination with an automatic document feeder and a sheet post-processing apparatus. This sheet post-processing apparatus performs post-processing such as stapling or punching.

In a sheet post-processing apparatus which performs post-processing such as stapling, bookbinding, and gluing on a sheet discharged from a copying machine, the sheet is discharged to a discharge tray by a discharge roller. If the leading end of the sheet bundle in the middle moves while rubbing the surface of the stacked sheet bundle discharged to the discharge tray first, the quality of the image fixed on the surface of the previously discharged sheet bundle may be deteriorated. is there. Further, if the leading end of the sheet bundle being discharged is caught on the staples of the stacked sheet bundle that has been discharged to the discharge tray first, the stacking state is disturbed.

A conventional sheet post-processing apparatus for solving such a problem is disclosed in, for example, JP-A-11-139.
No. 670 was described.

[0005] The sheet post-processing apparatus disclosed in the above-mentioned publication discloses a sheet bundle whose front end is bound in the discharging direction.
The sheet is discharged onto a discharge tray by a pair of discharge rollers. In this conventional sheet post-processing apparatus, in the discharge roller pair, the discharge speed of a lower roller is relatively increased with respect to the discharge speed of an upper roller, and the leading end side in the discharge direction of the sheet bundle during discharge is lifted to discharge. The above problem is solved by discharging the sheet bundle without disturbing the stack on the tray.

[0006]

However, with regard to the above-mentioned conventional sheet post-processing apparatus, the above publication discloses that the timing and the period of lifting the sheet bundle are adjusted to adjust the degree of lifting. However, it does not describe in detail how to lift a sheet bundle in the middle of discharging.

In fact, there are various types of sheet post-processing apparatuses which employ lifting means for making the discharge speed of the upper roller relatively smaller than the discharge speed of the lower roller as in the above-mentioned conventional sheet post-processing apparatus. When the characteristics of the sheet bundle, such as the number of sheets of the sheet bundle, the sheet size of the sheet bundle, the staple position of the sheet bundle, and the number of staple positions, are changed, the following problems may occur. found.

In addition to the characteristics of the sheet bundle,
It has been found that a problem occurs even if the state of the stacks already discharged to the discharge tray changes. (1) The problem that the top sheet of the sheet bundle being discharged is damaged The mechanism by which the sheet bundle being discharged is lifted is that the top sheet of the sheet bundle slides with respect to the second or lower sheet, and the top sheet has another Pulling the sheet.

Therefore, when the uppermost sheet pulls and curves another sheet, if the elastic force of the other sheet acting on the uppermost sheet becomes greater than the shear strength of the uppermost sheet, the uppermost sheet is damaged. I do. In particular, in the case of a sheet bundle bound by staples, since the sheet bundle is bound only at a specific portion (a portion of a staple),
The elastic force of the other sheets concentrates on the staple portion, and the uppermost sheet is more likely to be damaged.

By the way, the magnitude of the elastic force generated by the curl of a sheet (other sheet) other than the top sheet is a portion of the other sheet closer to the discharge roller than the discharge roller holding position, that is, already discharged. It is determined by the waist of the portion and the amount of lifting when the uppermost sheet lifts a sheet other than the uppermost sheet.

The waist of a portion of the sheet bundle being discharged other than the uppermost sheet on the discharge side from the discharge roller holding position is determined by the number of sheet bundles, the waist per unit area of the sheet, and the holding position by the discharge roller. It is determined by the length of the sheet bundle to the leading end on the discharge side and the width of the sheet bundle in the direction perpendicular to the conveyance direction.

Here, the waist per unit area of the single sheet is the thickness of the sheet, the fiber direction of the sheet (generally called the eye direction of the sheet. When the longitudinal direction of the fiber coincides with the longitudinal direction of the sheet). Is referred to as the longitudinal grain, and the case where the longitudinal direction of the fiber coincides with the lateral direction of the sheet is referred to as the lateral grain.) The fiber density (basis weight (sheet weight per unit area)) of the sheet is referred to as sheet thickness. (Value divided by).

The shear strength of the uppermost sheet varies depending on the type of fibers constituting the sheet, the manner of processing during the production of the sheet, the fiber density of the sheet, the size of the sheet, and the thickness of the sheet. That is, the shear strength of the top sheet is
It depends on the type of sheet.

Further, the easiness of breakage of the uppermost sheet is as follows.
It also changes depending on the difference in the binding form. When the form of binding is gluing, the presence or absence of breakage of the uppermost sheet is determined substantially by the shear strength of the uppermost sheet itself and the magnitude of the elastic force due to the bending of the sheets other than the uppermost sheet.

However, when the form of binding is staple, in addition to the shear strength of the uppermost sheet itself and the magnitude of the elastic force due to the curvature of the sheets other than the uppermost sheet, the number of staple positions and the number of staples are also reduced. This is a factor that determines whether the top sheet is damaged.

This is because, when the staples are bound with a staple, the total strength of the staples where the staples penetrate the sheet, and how the staples are struck in the eye direction of the sheet. This is because it affects the shear strength of the upper sheet.

Further, by binding with staples, the magnitude of the elastic force due to the curvature of a sheet other than the top sheet may be exceeded. For example, assuming that the staple location is a single location and the staples are bound so that the sheet penetrating location by the staples is in the same direction as the eye direction of the sheet, the elastic force due to the curvature of the sheets other than the topmost sheet becomes Since the sheet is pulled in a direction orthogonal to the direction of the eyes of the sheet, the sheet is more likely to be damaged than in a case where the sheet is pulled in a direction parallel to the direction of the eyes of the sheet. (2) The problem that the bundle of sheets during ejection is buckled If the stiffness of all the sheets other than the top sheet of the sheet bundle is small, the sheets other than the top sheet of the sheet bundle buckle and are already stacked on the discharge tray. In some cases, the stacked sheets may come into contact with the stacked sheets or sheet bundles to disturb the stacked state thereof, or the sheet bundle being discharged may be curled up onto the discharge tray and discharged.

In order to solve this problem, in one of the rollers of the discharge roller pair, both ends in the sheet discharge orthogonal direction are made larger in diameter than the central portion. Conventionally, a method of discharging a sheet bundle by waving it has been used.

However, the sheet bundle has a greater stiffness in the direction perpendicular to the conveying direction than when the sheet bundle is discharged alone. There is a problem that roller marks are formed on the sheet on the one roller side.

Also, if a relatively large number of sheet bundles are made to wave, the stiffness of the sheets other than the top sheet becomes very strong, and a very large tension acts on the top sheet when lifting the sheet bundle. However, there is also a problem that the uppermost sheet is easily damaged.

Further, the already ejected sheet is shifted, or the corner of the lowermost sheet of the sheet bundle is caught by the staple portion of the sheet bundle on the ejection tray,
There is also a problem that the corner is broken. (3) The problem that the image formed on the sheet on the discharge tray is rubbed by the binding member of the sheet bundle being discharged and the image is damaged is that the binding member of the sheet bundle being discharged is already discharged onto the discharge tray. When the image forming surface of the sheet is rubbed, the image formed on the sheet is damaged, and the image quality of the sheet deteriorates. This is because when the top stack on the discharge tray is a sheet bundle, the top sheet is more difficult to move than unbound sheets, so the top sheet moves when the sheet bundle is discharged. Rubbed without rubbing. Therefore, this problem becomes more prominent.

The above problems can be solved to some extent by the sheet post-processing apparatus disclosed in the above publication. However, depending on the state of the stack on the discharge tray, there are cases where the problem cannot be solved. For example, when a stapled sheet bundle is stacked at the same location and the stapling position is higher than other portions, if the lifting amount of the sheet bundle tip during ejection is small, the sheet bundle is ejected onto the ejection tray. Rubs the image forming surface of the sheet. (4) Problems caused by the state of stacks on the discharge tray The method of discharging must also be changed depending on the state of stacks stacked on the discharge tray. More specifically, in the case of a sheet on which the uppermost stack is not bound, the stacking state is disturbed even if the sheet bundle is lightly contacted. Further, when the uppermost stack on the discharge tray is a sheet bundle, depending on the binding position and the binding position, the sheet bundle being discharged is caught by the binding portion of the uppermost sheet bundle on the discharge tray and The bottom sheet of the sheet bundle breaks,
Or disturb the stacking state of the top sheet bundle on the discharge tray.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems. When a sheet bundle is discharged from a post-processing tray to a discharge tray, the state of the sheet bundle being discharged and the discharge state are determined using simple means. A sheet post-processing device capable of discharging sheets without disturbing the stacking state of the sheet bundles and sheets already discharged onto the discharge tray in accordance with the state of the completed sheet bundle and preventing damage to the top sheet. It is intended to provide.

[0024]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention performs a binding process on a discharge sheet discharged from an image forming apparatus, and discharges a bound sheet bundle to a discharge tray. A sheet post-processing device that raises the discharge speed of a lower roller relative to an upper roller of a discharge roller pair to lift the leading end side of a sheet bundle in a discharge direction, and stores information on sheet bundle characteristics obtained by initial setting and binding processing. And control means for adjusting the lifting amount of the sheet bundle according to the sheet bundle characteristics.

With the above configuration, when the sheet bundle is discharged to the discharge tray, the uppermost sheet of the sheet bundle slides with respect to the second or lower sheet by increasing the discharge speed of the lower roller relative to the upper roller. , The top sheet pulls the second and lower sheets. With such a configuration, the leading end side in the discharge direction of the sheet bundle is lifted. Accordingly, the leading end of the sheet bundle being discharged does not rub against the surface of the stacked sheets that have been discharged to the discharge tray first, so that the image quality of the surface of the stacked sheets does not deteriorate. . Further, the leading end of the sheet bundle being discharged does not catch on the staples of the stacked sheet bundle, so that the stacking state is not disturbed.

Further, the storage means stores the sheet bundle characteristics such as the number of sheets bound in the sheet bundle, the sheet size, the binding position of the sheet bundle, the thickness of the sheet unit, and the type of sheet. Information is stored. The sheet post-processing apparatus itself obtains such information on the sheet bundle characteristics at the stage when the user performs the initial setting and the binding process, and stores the sheet bundle characteristics in the storage unit.

When the sheet bundle is lifted, an elastic force generated by bending a sheet (other sheet) other than the uppermost sheet in the sheet bundle acts on the uppermost sheet of the sheet bundle. If this elastic force exceeds the shear strength of the top sheet, the top sheet will break. Therefore, the lifting amount of the sheet bundle is adjusted according to the sheet bundle characteristics stored in the storage means so that the elastic force does not exceed the shear strength of the uppermost sheet.

That is, when the shear strength of the top sheet is low or the elastic force of the other sheets is large, the lifting amount is reduced, and when the shear strength of the top sheet is strong or the elastic force of the other sheets is small. If so, increase the lift. Thus, it is possible to prevent the top sheet from being damaged when the sheet bundle is lifted.

According to the present invention, the discharging sheet discharged from the image forming apparatus is subjected to binding processing, and the discharging speed of the lower roller with respect to the upper roller of the discharging roller pair is adjusted while discharging the bound sheet bundle to the discharging tray. In the sheet post-processing apparatus for lifting the leading end in the discharge direction of the sheet bundle, storage means for storing information on the state of the discharged sheet on the discharge tray obtained by initial setting, binding processing, and discharging operation, and the discharged sheet Control means for adjusting the lifting amount of the sheet bundle in accordance with the state of (1).

With the above arrangement, the storage means stores information on the state of the discharged sheets already discharged on the discharge tray, that is, whether the load on the discharge tray is a sheet bundle or a single sheet, In the case of a bound sheet bundle, information such as the binding position and binding location is stored. The sheet post-processing apparatus itself obtains such information on the state of the discharged sheet through the initial setting, the binding processing, and the discharging operation, and causes the storage unit to store the state of the discharged sheet.

The control means adjusts the lifting amount of the sheet bundle in accordance with the state of the discharged sheet stored in the storage means. Thus, even if the top one of the stacked items on the discharge tray is, for example, an unbound sheet alone, setting the lifting amount to a large value allows the sheet to be discharged onto the sheet alone. The stacking state is not disturbed by the contact of the inner sheet bundle.

Further, for example, when all the sheet bundles stacked on the discharge tray have the same binding position, the binding positions overlap and the binding position portion is higher than the other portions. In such a case, by setting the lifting amount of the sheet bundle to be large, the sheet bundle being discharged is caught by the binding portion of the sheet bundle on the discharge tray, and the lowermost sheet of the sheet bundle being discharged is set. Will not break.

Therefore, the sheet bundle can be discharged without disturbing the stacked state on the discharge tray and without causing breakage of the sheet during discharging.

According to the present invention, the discharging sheet discharged from the image forming apparatus is subjected to binding processing, and the discharging speed of the lower roller with respect to the upper roller of the discharging roller pair is adjusted while discharging the bound sheet bundle to the discharging tray. In a sheet post-processing apparatus that raises the leading end of the sheet bundle in the discharging direction, the sheet bundle lifting operation is performed according to the rigidity of a portion of the sheet bundle being discharged between the position sandwiched by the pair of discharge rollers and the leading end in the discharging direction. Is provided.

According to the above configuration, the rigidity of the portion of the sheet bundle being discharged from the holding position held by the pair of discharge rollers to the leading end in the discharge direction is the position where the sheet bundle is held by the pair of discharge rollers. Can be considered as the waist of the sheet bundle from to the leading edge of the sheet.

For example, if the length from the nipping position to the leading edge of the sheet output side is too short and the stiffness of the sheet bundle is strong, that is, if the leading edge of the sheet bundle starts lifting operation at a very early timing after starting to output the sheet. However, there is a possibility that a large tension is applied to the uppermost sheet and the uppermost sheet is damaged. Therefore, the control means adjusts the timing of starting lifting according to the rigidity of the sheet bundle, thereby preventing the top sheet from being damaged.

The waist of the sheet is determined by the length of the sheet in the conveying direction, the width of the sheet bundle in the direction perpendicular to the conveying direction, the fiber direction of the sheet,
This depends on the number of sheets constituting the sheet bundle and the like. The length of the sheet width from the nipping position to the leading end in the discharge direction can be calculated, for example, by subtracting the time when the discharge roller pair detects the leading end of the sheet bundle from the current time at a constant conveying speed. is there. Further, the width of the sheet bundle in the conveyance orthogonal direction is information obtained in advance according to the sheet size, and the information regarding the number of sheet bundles is also given to the sheet post-processing apparatus itself by initial setting or the like.

According to the present invention, the discharging sheet discharged from the image forming apparatus is subjected to binding processing, and the discharging speed of the lower roller with respect to the upper side of the discharging roller pair is increased while discharging the bound sheet bundle to the discharging tray. In the sheet post-processing device that lifts the leading end of the sheet bundle in the discharge direction, the discharged length of the sheet bundle being discharged from the position pinched by the pair of discharge rollers to the leading end in the discharge direction is calculated. Length calculation means, when the discharged length is equal to or more than a predetermined length,
Control means for starting the lifting operation of the sheet bundle is provided.

With the above configuration, for example, for a certain sheet material and a certain number of sheets, the length from the holding position pinched by the discharge roller to the leading end in the discharge direction is used as a parameter, and the upper limit is a certain number of sheets. If the rigidity of the bundle is given to the control means in advance, the rigidity of the sheet bundle at the discharged portion can be determined by calculating the discharged length.

This makes it possible to optimally control the timing for lifting the sheet bundle being discharged. Therefore,
The control unit adjusts the timing of starting the lifting in accordance with the rigidity of the sheet bundle, thereby preventing the uppermost sheet from being damaged.

The present invention includes a speed adjusting means for gradually changing the speed of at least one of the upper roller and the lower roller.

With the above structure, when the speed of the upper roller is decreased or the speed of the lower roller is increased to raise the sheet to generate the relative speed between the two rollers, the relative speed gradually increases. So that it can be adjusted.

As described above, when the sheet bundle is lifted, the relative speed between the upper roller and the lower roller is not increased rapidly but is increased gradually, so that the peak of the tension acting on the uppermost sheet at the time of lifting is increased. By reducing the value, the maximum value of the tension can be suppressed.

Therefore, the possibility that the uppermost sheet of the sheet bundle being discharged is damaged from the binding portion can be reduced as compared with the case where the relative speed is suddenly changed. In addition, since there is no rapid increase in the relative speed, no extra force due to acceleration acts on the sheet bundle being discharged, so that the uppermost sheet of the sheet bundle is not damaged.

According to the present invention, the upper roller has a cushioning property in the rotation direction.

According to the above configuration, even when the relative speed between the upper roller and the lower roller suddenly increases, the tension applied to the uppermost sheet of the sheet bundle is increased by the upper roller having a buffering property in the rotating direction. (The roller has a buffering property against an increase in sheet tension). Therefore, the possibility that the uppermost sheet of the sheet bundle being discharged is damaged from the binding portion can be further reduced.

In the present invention, the upper roller has an elastic foam layer.

According to the above configuration, even when the relative speed of the lower roller with respect to the upper roller is sharply increased when the sheet bundle is lifted, the elastic foam layer is distorted in the conveying direction of the sheet bundle. The tension acting on the uppermost sheet becomes lower.

Therefore, the peak value of the tension applied to the uppermost sheet can be suppressed, so that the damage to the uppermost sheet can be suppressed with a simpler structure than a mechanical structure.

According to the present invention, the upper roller has a surface layer that moves in the rotational direction with respect to the axis of the upper roller when a predetermined force or more acts in the rotational direction.

According to the above configuration, the upper roller is provided with a buffer in the rotational direction by providing the upper roller with a surface layer that moves (slids) with respect to the shaft when a force in the rotational direction exceeding a certain level acts. .

With this arrangement, if an excessively large tension acts on the uppermost sheet during lifting of the sheet bundle, the surface layer moves together with the uppermost sheet in the sheet bundle conveying direction, so that the upper roller is applied to the uppermost sheet in contact with the uppermost roller. The tension becomes gentle, the peak value of the tension applied to the uppermost sheet can be suppressed, and the uppermost sheet can be prevented from being damaged during lifting.

According to the present invention, a flocked portion made of fiber is provided on the surface of the upper roller that contacts the sheet.

With the above structure, the flocked portion provided on the contact surface of the upper roller with the sheet (the upper roller surface) contacts the sheet bundle during unloading, and is pressed by the uppermost sheet to cause the fibers to move in the sheet bundle transport direction. Will be inclined to the opposite side. When this fiber occurs, it serves to slide the top sheet in the transport direction. With such a configuration, the upper roller has a cushioning property in the rotation direction.

Therefore, even if tension is suddenly applied to the uppermost sheet in contact with the flocking portion of the upper roller,
This tension will gradually change. Thus, the peak value of the tension can be suppressed, so that the uppermost sheet of the sheet bundle can be prevented from being damaged during lifting.

According to the present invention, at least one of the upper roller and the lower roller has an end in the direction perpendicular to the conveyance direction.
It is made of a material with lower rigidity than the central part in the direction perpendicular to the conveyance,
In addition, a wavy member that protrudes toward the sheet side from the central portion is provided.

According to the above configuration, in the case where the number of sheets to be discharged is small (thin), the number of sheets having a weak waist is small (thin). On the other hand, when the sheet bundle has a large number of stiff sheets (thick), the wavy member having a lower rigidity than the central portion is pressed by the sheet bundle due to the strong stiffness of the sheet bundle and is almost as large as the central portion. Pressed to the height of

Therefore, no trace of waving is generated in the sheet bundle,
Also, since the waist of the sheet bundle is not unnecessarily strengthened, it is not necessary to apply a very strong tension to the uppermost sheet in order to lift the sheet bundle. Damage can be suppressed.

According to the present invention, the wavy member is made of an elastic foam.

According to the above configuration, since the wavy member is made of elastic foam, it is possible to prevent the wavy member from being traced on the sheet bundle when a large (thick) bundle of sheets having a strong stiffness is discharged. can do.

[0061]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a sheet post-processing apparatus according to the present invention will be described with reference to FIGS.

The sheet post-processing apparatus 1 according to the present embodiment
As shown in FIG. 2, the copying machine 2 is installed on the sheet discharge port 3 side of a copying machine 2 as an image forming apparatus including, for example, a digital copying machine, a digital color copying machine, and other general copying machines. Post-processing such as stapling and sheet sorting are performed on sheets discharged from the machine 2 such as paper and OHP sheets.

The post-processing performed on the sheet by the sheet post-processing apparatus 1 may be a punching process, a gluing process, or the like, in addition to the above-described stapling process. A case where stapling processing is performed as post-processing will be exemplified.

Further, the sheet post-processing apparatus 1 has a structure which can be moved in and out of the copying machine 2 in the paper discharging direction when the copier 2 and the sheet post-processing apparatus 1 perform jam processing or staple replacement. When the sheet post-processing apparatus 1 is connected to the copying machine 2, an inclined rail mounted on the sheet post-processing apparatus 1 rides on a guide member on the copying machine 2 side, and a sheet discharge port 3 of the copying machine 2; The height with the sheet inlet 4 of the sheet post-processing apparatus 1 can be precisely aligned.

The sheet post-processing apparatus 1 has, for example, an offset tray 11 as a discharge tray capable of ascending and descending operations and offset sorting operations with a large number of stapled copies as a discharge destination.

In the offset tray 11, the driving force of the lifting / lowering motor 51 is controlled by the driving force transmission system 5 composed of gears and the like.
The lifting and lowering operation is performed by being transmitted by 2 and the driving wire 53.

Further, the offset tray 11 has a double structure of a lower offset tray reinforcing plate 11a and an upper offset tray plate 11b, and the offset tray plate 11b is offset by a driving force of an offset motor 54. The sheet can be moved horizontally relative to the tray reinforcing plate 11a in a direction perpendicular to the sheet conveying direction.

With this arrangement, when a plurality of sheets or a bundle of sheets are discharged and the sheets or the like are offset-sorted, the offset tray plate 11b is alternately left and right each time one sheet or the like is discharged. By moving the sheet, the discharged sheets and the like are accumulated on the offset tray 11 in a state where they are alternately shifted left and right. Therefore,
In particular, when the stapling process is not performed on the sheet bundle, the sorting of the sheet bundle becomes extremely easy.

The sheet post-processing apparatus 1 has two fixed trays, an upper fixed tray 12 and a lower fixed tray 13, in addition to the offset tray 11. That is, the copying machine 2 used in the present embodiment has an operation mode of a fax mode and a printer mode in addition to the copy mode. For example, the upper fixed tray 12 has a discharge destination tray in the fax mode. And the lower fixed tray 13 is set as a discharge destination tray in the printer mode.

The sheet post-processing apparatus 1 is provided with a plurality of sheets capable of various combinations according to the sheet size of sheets to be discharged, whether or not stapling is performed, whether or not reverse discharge is required, and a discharge destination tray. Of the plurality of paths, a desired path is combined from the plurality of paths to form one conveyance path, and the sheet is subjected to necessary processing and discharged.

The plurality of paths are, specifically, a direct path 21, a bypass path 22, an inversion path 23, a communication path 24, an upper fixed tray discharge path 25, a lower fixed tray discharge path 26, and an offset tray discharge path 27. , And a lower staple tray 15.

The direct path 21 extends downward from the sheet inlet 4 and passes through a reversing roller 42, as will be described later, a gap provided between the vertically extending upper staple tray 14 and the lower staple tray 15. It is connected to the part. Therefore, the sheet discharged from the copying machine 2 is conveyed to the lower staple tray 15 through the direct path 21 and the reversing roller 42.

The bypass path 22 extends upward from the sheet inlet 4 and curves around the upper end of the upper staple tray 14. After the bypass, the side surface of the sheet post-processing apparatus 1 on the tray side is used. The lower staple tray 15 extends downward in the vicinity, curves again in front of the upper side of the offset tray 11, and is connected to the lower end of the lower staple tray 15. In addition, the bypass path 22 extends from the sheet entrance 4 to the lower staple tray 15.
Detour paths 22a to 2a in the entire section up to the lower end of
It is divided into three parts 2c.

Then, the detour path 22a and the detour path 22b
The upper fixed tray discharge path 25 serving as a path for discharging sheets to the upper fixed tray 12 is branched from the connection portion with the upper fixed tray 12, while the lower fixed tray 13 is connected to the lower fixed tray 13 from the connection portion between the bypass path 22 b and the bypass path 22 c. A lower fixed tray discharge path 26 serving as a path for discharging sheets is branched.

The reversing path 23 is located in the vicinity of the reversing roller 42 at the lower end of the direct path 21, from the vicinity of the connection with the gap between the upper staple tray 14 and the lower staple tray 15, to the copying machine 2 side. It extends vertically. That is, the sheet conveyed on the direct path 21 may be conveyed to the reversing path 23 side other than the case where the sheet is conveyed to the lower staple tray 15.

Then, the sheet introduced into the reversing path 23 is sent out from the communication path 24 to the bypass path 22 by reversing the reversing roller 42. Therefore, the reversing path 23 and the communication path 24 are paths used when a sheet is once switched back to the bypass path 22 and fed.

The offset tray discharge path 27 extends from the lower end of the lower staple tray 15 through the lower side of the bypass path 22, and extends from the lower staple tray 15.
The sheet fed from the lower end of the tray 5 is discharged onto the offset tray 11 from the offset tray discharge path 27.

The switching of each transport path is performed by switching the direction of rotation of the transport roller and the gate provided at the branch of each path. The switching operation will be described in detail later.

The lower staple tray 15 is a part of a staple tray as a post-processing tray that extends vertically to temporarily stack a sheet bundle to be stapled. In the present embodiment, the lower staple tray 15 is It is used as a path that forms part of the transport route.

That is, in the present embodiment, the staple trays are arranged almost vertically near the upper portion of the sheet post-processing apparatus 1 in a state where the staple trays are separated into the upper staple tray 14 and the lower staple tray 15. Since a gap is provided between the upper staple tray 14 and the lower staple tray 15, as described above, it is possible to carry a sheet from the direct path 21 to the lower staple tray 15 through this gap. It is possible.

In the above-mentioned sheet post-processing apparatus 1, when a stapling process is performed on a sheet, the sheets are stacked on a staple tray. When sheets are stacked on the staple tray, the lower end of the sheet is placed on the sheet support 55, and the lower end of the sheet is aligned by the sheet support 55.

However, the sheet conveyed on the staple tray may not be sufficiently aligned on the sheet support table 55 due to static electricity or the like.
Each time one sheet is conveyed, a downward conveying force is applied to the sheet by the rotation of the paddle 56 (counterclockwise direction in FIG. 2), and the sheet is surely aligned. The paddle 56 applies a conveying force to the sheet by a flexible blade formed of an elastic material such as rubber. The paddle 56 rotates once each time one sheet is conveyed onto the staple tray.

The side ends of the sheet bundle placed on the sheet support table 55 are aligned by being held from the side surfaces of the sheet bundle by the alignment plate 57. Further, the staple tray 14 extends vertically as described above, and the upper staple tray 14
In this area, since only one side of the stacked sheets is supported, there is a possibility that the sheets fall down to the side opposite to the staple tray.

To prevent this, a paper guide 58 is arranged at least near the upper end of the sheets to be stacked, and the sheet is held between the staple tray and the paper guide 58 so as to be sandwiched therebetween. The paper guide portion 58 includes, for example, two connecting plates 58a and 58.
b and can be manually moved to the evacuation position at the time of jam clearance or the like.

A stapler 59 is disposed below the staple tray. When a predetermined number of sheets are stacked on the sheet support table 55, the stapler 5 holds the sheet bundle while the sheet support table 55 holds the sheet bundle.
The staple is moved down to the staple processing position 9. The sheet bundle stapled by the stapler 59 is returned to the position of the staple tray by moving up while the sheet support table 55 holds the sheet bundle. Then, the sheet bundle is discharged to the offset tray 11 through the offset tray discharge path 27 as the sheet support 55 descends.

Next, the paper output roller 70 of the sheet post-processing apparatus 1 of the present embodiment will be described in detail.

In the sheet post-processing apparatus 1 of the present embodiment, as shown in FIG. 2, the paper output roller 70 for discharging the sheet bundle to the offset tray 11 is composed of an upper roller 71 and a lower roller 72. In addition, each has the same outer diameter and can rotate independently of each other.

As shown in FIGS. 3 and 4, the upper roller 71 and the lower roller 72 are provided in a state of being pressed against each other along four roller shafts 71a and 72a extending in the left-right direction. A transport motor 73 for driving the upper rollers 71 and the lower rollers 72 is provided at the end.

A press roller 74a of a drive connecting portion 74 is provided on the motor shaft 73a of the transport motor 73 in a pressed state, and a drive gear 74b is provided coaxially with the press roller 74a.

The driving gear 74b meshes with an upper roller gear 71b fixed to a roller shaft 71a for the upper rollers 71.

A lower roller gear 75a fixed to a clutch 75 as switching means meshes with the upper roller gear 71b. This lower roller gear 7
The clutch 75 provided with the clutch shaft 5a is detachable from the roller shaft 72a inside the clutch 75 and has a roller shaft 72a.
The gripping mechanism has a gripping mechanism (not shown) for gripping the roller shaft 72a.

Therefore, when the clutch 75 does not grip the roller shaft 72a, the driving force of the lower roller gear 75a meshing with the driving gear 74b is not transmitted to the roller shaft 72a, so that the clutch 75 and the lower roller gear 75a are driven integrally. It is driven by the gear 74b. As a result, the lower rollers 72 rotate following the upper rollers 71 due to friction with the upper rollers 71.

On the other hand, when the clutch 75 grips the roller shaft 72a, the driving force of the upper roller gear 71b is transmitted to the roller shaft 72a via the lower roller gear 75a and the clutch 75. Therefore, both the lower rollers 72 and the upper rollers 71 rotate with a driving force.

Here, the lower roller gear 75a has a smaller diameter and fewer teeth than the upper roller gear 71b. As a result, when the driving force of the transport motor 73 is transmitted to the upper roller 71 and the lower roller 72, the lower roller 72 rotates faster while slipping than the upper roller 71. I have.

As described above, in the present embodiment, the transport motor 73, the motor shaft 73a, the drive connecting portion 74, the pressing roller 7
4a, drive gear 74b, upper roller 71,..., Roller shaft 7
1a, upper roller gear 71b, clutch 75, lower roller gear 75a, roller shaft 72a, and lower roller 72
.. Constitute a lifting mechanism 76 as lifting means.

The sheet output operation of the sheet bundle of the sheet post-processing apparatus 1 having the lifting mechanism 76 will be described.

First, as shown in FIG. 5, the sheet bundle 80 stapled at the front end is nipped by the conveying roller 43 and pushed out to the offset tray discharge path 27, and then, eventually, the upper roller 71 and the lower side. It passes between the rollers 72.

At this time, the upper roller 71 and the lower roller 72 are in a state in which the clutch 75 is separated from the roller shaft 72a as shown in FIG. Therefore, the driving force of the transport motor 73 is transmitted to the upper roller 71 via the drive connecting portion 74, the upper roller gear 71b, and the roller shaft 71a.
, And the lower roller 72 is driven by the upper roller 71.

Accordingly, the upper roller 71 and the lower roller 72 rotate at a constant speed, and the outer diameters of the upper roller 71 and the lower roller 72 are equal.
The sheet bundle 80 passing between the upper and lower rollers 72 passes at a uniform speed on both the upper surface side and the lower surface side.

Then, as shown in FIG.
When the vehicle approaches the rear end side, a signal is sent from a control unit (not shown) to the clutch 75 so as to perform connection with the roller shaft 72a. As a result, as shown in FIG. 3, the rotational driving force of the upper roller gear 71b is reduced by the lower roller gear 75b.
a, the clutch 75, and the roller shaft 72a.

Since the lower roller gear 75a has a smaller diameter and a smaller number of teeth than the upper roller gear 71b, the rotation speed of the lower roller gear 75a is higher than the rotation speed of the upper roller 71b (the pitch circle). Are the same.) Since the outer diameter of the upper roller 71 and the outer diameter of the lower roller 72 are the same, the speed of the roller peripheral surface of the lower roller 72 is higher than the speed of the roller peripheral surface of the upper roller 71. As shown in FIG. 1, the sheet bundle 80
The lower surface tends to move relatively faster than the upper surface.

As a result, as shown in FIG.
Since the upper side of the sheet bundle 80 is pulled by the upper roller 71, the leading end side of the sheet bundle 80 is inevitably lifted. That is, the stapled portion mainly lifts.

As a result, the sheet bundle 80 is discharged to a position where the leading end surfaces thereof are aligned without contacting the stacked sheets already discharged to the offset tray 11, and the trailing end of the sheet bundle 80 is eventually formed. Is placed on the already stacked sheet bundle 80 by leaving the paper output roller 70.

As a result, the newly discharged sheet bundle 80 is sequentially stacked without being in contact with the staples of the already stacked sheet bundle 80 and without being rubbed on the surface of the sheet bundle 80. .

As described above, in the sheet post-processing apparatus 1 of this embodiment, the sheets discharged from the copying machine 2 are stacked on the upper staple tray 14 and the lower staple tray 15, and the staple processing is performed as the post-processing. Then, usually, the staple portion 8 is located at the leading end side of the sheet bundle 80 in the discharge direction.
The sheet is discharged to the offset tray 11 by the sheet output roller 70 in a state where 0a exists.

Here, the paper output roller 70 is provided with a lifting mechanism 76 for lifting the front end side of the bound sheet bundle 80 in the discharging direction. For this reason, the sheet bundle 80 discharged by the paper output roller 70 is lifted at the leading end side by the lifting mechanism 76, and is discharged and moved without contacting the sheet bundle 80 already stacked on the offset tray 11.

Therefore, the leading end of the sheet bundle 80 being discharged does not rub against the surface of the stacked sheet bundle 80 that has been discharged onto the offset tray 11 first, and is fixed on the surface of the sheet bundle 80. It is possible to prevent the image quality from deteriorating, and also to prevent the sheet bundle discharged and stacked on the offset tray 11 from being turned upside down and turned upside down. .

Further, since the leading end of the currently discharged sheet bundle 80 does not catch on the staples 80a of the sheet bundle 80 that has been discharged to the offset tray 11 and stacked, the stacking state is not disturbed. .

Further, the lifting mechanism 76 is connected to the paper output roller 70.
Therefore, even when the offset tray 11 is provided outside the sheet post-processing apparatus 1, the lifting mechanism 76 is not exposed to the outside.

Therefore, when the sheet bundle 80 is discharged from the sheet post-processing apparatus 1 to the offset tray 11, it is possible to reliably prevent the image from being disturbed without using any obstructive means, and to prevent the sheet bundle 80 from being stacked. It is possible to provide the sheet post-processing apparatus 1 that does not cause the sheet 80 to be disturbed.

In the sheet post-processing apparatus 1 of this embodiment, the lifting mechanism 76 performs stapling on the leading end side in the discharging direction to lift the leading end side of the sheet bundle 80 bound in the discharging direction. Upper roller 7 in
The discharge speed of the lower roller 72 of the pair of paper output rollers 70 is relatively increased with respect to the discharge speed of 1.

Therefore, when the sheet bundle 80 passes between the upper roller 71 and the lower roller 72 of the pair of paper output rollers 70, the lower surface of the sheet bundle 80 moves quickly, and the upper surface of the sheet bundle 80 moves at the speed. Move slower than. As a result, since the leading end side of the sheet bundle 80 in the discharge direction is bound by the staples 80a, the upper side of the sheet bundle 80 is pulled by the upper roller 71, whereby the leading end side of the sheet bundle 80 is lifted.

As a result, a specific structure of the lifting mechanism 76 having a simple structure can be provided. Also,
Since the leading end of the sheet bundle 80 in the discharge direction can be lifted only by controlling the rotation of the paper output roller 70, a member such as a cantilever type for lifting the leading end of the sheet bundle 80 in the discharge direction is arranged on the discharge side. No need.

In the present embodiment, in order to lift the leading end of the sheet bundle 80 in the discharge direction, the output rollers 7 are set at a higher speed than the discharge speed of the upper roller 71 in the pair of output rollers 70.
As a lifting mechanism 76 in which the discharge speed of the lower roller 72 in the 0 pair is relatively increased, both the upper roller 71 and the lower roller 72 are rotated, and the rotation speed of the lower roller 72 is higher. I have to.

For this reason, since both the upper surface side and the lower surface side of the sheet bundle 80 move in the discharging direction to make a speed difference, as described later, it is necessary to stop the upper roller 71 and make a relative speed difference. In comparison, the sheets of the sheet bundle 80 do not shift while being sandwiched between the upper roller 71 and the lower roller 72. For this reason, the image fixed on the sheet is not rubbed, and the image quality is not degraded.

However, in the present invention, the lifting mechanism 7
6 is a lower roller 72 of the pair of paper output rollers 70 with respect to a discharge speed of the upper roller 71 of the pair of paper output rollers 70.
Since the discharging speed of the lower roller 72 is relatively high, the stopping of only the upper roller 71 during the rotation of the lower roller 72 is also included.

Thus, as the lifting mechanism 76,
For example, since it can be constituted by a brake means for applying a brake only to the upper roller 71, the structure of the lifting mechanism 76 can be further simplified.

Specifically, the lower roller 72 is used as a drive system and the upper roller 71 is used as a driven system.
For example, a brake shoe (not shown) as a brake means can be provided detachably.

Further, in the sheet post-processing apparatus 1 of the present embodiment, the lifting mechanism 76 has a discharge speed of the lower roller 72 between the pair of paper output rollers 70 with respect to a discharge speed of the upper roller 71 between the pair of paper output rollers 70. Is relatively large, and a clutch 75 is provided for switching between a case where the pair of paper output rollers 70 is set to a normal discharge speed.

Therefore, when the sheet is discharged to the offset tray 11 by the paper output roller 70 without performing the stapling process, the clutch 75 switches the pair of paper output rollers 70 to the normal discharge speed.

On the other hand, when the stapled sheet bundle 80 is to be discharged,
The lifting mechanism 76 is switched so that the discharge speed of the lower roller 72 of the pair of paper output rollers 70 is relatively higher than the discharge speed of the upper roller 71 of the pair.

Here, the sheet post-processing apparatus 1 according to the present embodiment further has the following characteristic configuration.
Hereinafter, embodiments of adjustment of the amount of lifting when the lifting mechanism 76 lifts the sheet bundle 80, and timing and period of lifting when the lifting mechanism 76 lifts the sheet bundle 80, which are characteristic parts of the sheet post-processing apparatus 1 according to the present embodiment, will be described. explain. <Embodiment 1> The memory (storage means) provided in the sheet post-processing apparatus 1 stores the characteristics of the sheet bundle 80 by the control unit based on information obtained by the user's initial settings and stapling processing. . The characteristics of the sheet bundle 80 include, for example, the number of sheets of the sheet bundle 80, sheet size, staple location, sheet thickness, sheet type, and the like. The control unit changes the lifting amount of the sheet bundle 80 by the lifting mechanism 76 according to these.

That is, the sheet bundle 80 stored in the memory
The control unit controls the transport motor 73 of the lifting mechanism 76 in accordance with the characteristics described above, and the driving force of the transport motor 73 is adjusted.

As a result, the relative speed between the upper roller 71 and the lower roller 72 can be adjusted according to the characteristics of the sheet bundle 80, and the lifting amount is adjusted according to the characteristics of the sheet bundle 80.

That is, an elastic force generated when another sheet of the sheet bundle 80 is bent by lifting acts on the uppermost sheet of the sheet bundle 80, and this elastic force exceeds the shear strength of the uppermost sheet. The lifting amount is adjusted according to the characteristics of the sheet bundle 80 so as not to occur.

Specifically, when the shear strength of the uppermost sheet is low or the elasticity of the other sheets is high, the lifting amount is adjusted to be small. On the other hand, when the shear strength of the uppermost sheet is high or the elasticity of the other sheets is low, the lifting amount is adjusted to be large.

Therefore, when the sheet is lifted at the time of discharging, the elastic force of the other sheet (tension acting on the uppermost sheet) does not become larger than the shear strength of the uppermost sheet. Damage can be suppressed. This can prevent the uppermost sheet from being lifted more than necessary and from being damaged. <Embodiment 2> Further, the state of the discharged sheets already stacked on the offset tray 11, that is, whether the stack on the offset tray 11 is a sheet bundle or a single sheet, or a stapled sheet bundle In some cases, the amount by which the sheet bundle 80 is lifted by the lifting mechanism 76 is adjusted according to the staple position, the staple position, the uppermost sheet thickness of the sheet bundle, and the like.

Specifically, the uppermost stack on the offset tray 11 is a single sheet, or the uppermost stack on the offset tray 11 is a sheet bundle, and the uppermost sheet thickness thereof is If is relatively thin, increase the lift. Thereby, the offset tray 1
This prevents the sheet bundle 80 being discharged from contacting the upper single sheet unit from disturbing the stacking state, and preventing the thin uppermost sheet of the sheet bundle from being inverted to form a folding habit.

If a plurality of sheet bundles at the same binding position are stacked on the offset tray 11, the lifting amount is increased. Thereby, the sheet bundle 80 is
The lowermost sheet will not be broken by being stuck at the binding position of the stack, which is higher than the other portions.

Further, when the uppermost stack on the offset tray 11 is a sheet bundle and the uppermost sheet is relatively thick (for example, in the case of cover paper), the lifting amount is reduced. Thus, when no problem occurs even if the top stack on the offset tray is rubbed as in this case, the sheet bundle is unnecessarily lifted,
The force applied to the staple portion of the sheet bundle can be reduced, and the damage to the sheet can be reduced.

The information on the state of the discharged stack as described above is stored in the initial settings of the user, when the stack is stapled, and when the offset tray 1 is controlled.
When the sheet is ejected to the sheet post-processing apparatus 1, it is stored in a memory provided in the sheet post-processing apparatus 1. In response to this information, the control unit operates the clutch and the brake, for example, as described above, so that the peripheral speed of the upper roller 71 is higher than the peripheral speed of the lower roller 72. And lower roller 7
The lifting amount is adjusted by adjusting the relative speed of No. 2.

As described above, by changing the lifting amount of the sheet bundle 80 in accordance with the state of the stacks already discharged onto the offset tray 11, the offset tray 1
For example, when a single sheet is stacked on the sheet 1, the stacking state may be disturbed by the sheet bundle 80 being discharged,
Alternatively, the sheet bundle 80 is caught on the staples of the sheet bundle stacked on the offset tray 11 and
It is possible to prevent the lowermost sheet of zero from being folded or the uppermost sheet of the sheet bundle on the offset tray 11 from being inverted and having a folding habit.

Next, an embodiment in which the timing for lifting the sheet bundle 80 is adjusted will be described. <Embodiment 3> Timing of starting lifting of the sheet bundle 80 by the lifting mechanism 76 in accordance with the rigidity of the portion of the discharged sheet bundle 80 from the position pinched by the paper output roller 70 to the leading end on the paper output side. Is adjusted by the control unit.

The rigidity of the portion from the holding position, which is held by the paper output roller 70 during the discharge, to the leading end on the paper output side can be considered to be the waist of the sheet bundle 80 at this portion. For example, when the length from the nipping position to the leading end on the paper exit side is too short and the stiffness of the sheet bundle is strong,
If the lifting of the sheet bundle 80 is started too early after the leading edge of the sheet starts to output paper, a very large force is required to lift the sheet bundle 80. As a result, a large tension may be applied to the uppermost sheet and the uppermost sheet may be damaged. Therefore, the above-described problem can be solved by enabling the adjustment of the lifting start timing according to the rigidity of the sheet bundle as described above.

The stiffness of a sheet depends on the length of the sheet in the conveying direction, the width in the direction perpendicular to the conveying direction of the sheet bundle, the fiber direction of the sheet, the number of sheets constituting the sheet bundle, and the like. In the present embodiment, the length from the nipping position of the sheet bundle 80 to the leading end on the paper output side is determined by using a transported length calculating means (not shown), for example, at a constant transport speed and from the current time to the paper output roller. The calculation can be performed by subtracting the time when the leading end of the sheet bundle 80 is detected by 70.

The width of the sheet bundle in the direction perpendicular to the transport direction is information obtained in advance according to the sheet size, and the number of sheet bundles can be obtained because it is stored in the memory.

Information such as sheet thickness can be obtained by, for example, setting the sheet thickness for each sheet supply tray, or such sheet information can be obtained from plain paper. , Thick paper or the like. Further, the thickness of the sheet may be actually detected. <Embodiment 4> In addition to the above-described timing determination method, for example, the upper limit number of sheets to be bound for a certain sheet material is determined, and the length from the holding position held by the paper output roller 70 to the paper output side tip is determined. The rigidity of the sheet bundle at the upper limit number of sheets to be bound is set in advance by using the length as a parameter.

Therefore, the rigidity of the sheet bundle 80 depends on the length of the discharged portion. Therefore, the length from the pinching position pinched by the paper output roller 70 to the paper output side front end is simply calculated using the unloaded length calculating means,
The optimal lifting timing can be adjusted by the control unit in accordance with the rigidity from the holding position of the sheet bundle 80 to the leading end of the sheet output side.

With such a configuration, the paper output roller 70
The timing for lifting the sheet bundle 80 can be determined in consideration of only the length of the sheet bundle 80 from the holding position to the leading end of the sheet output side. <Fifth Embodiment> Further, at the time of lifting, the rotation speed of the transport motor 73, which is a speed adjusting means, is adjusted so as to be gradually changed by the control unit.

As a result, when the sheet bundle 80 is lifted, the relative speed between the upper roller 71 and the lower roller 72 can be gradually increased instead of suddenly increasing.
The peak value of the tension applied to the uppermost sheet can be reduced. Therefore, the relative speed increases rapidly,
The top sheet will not be torn.

In the case of this method, if the upper roller 71 and the lower roller 72 are driven by separate motors, the relative speed can be adjusted more appropriately.

The upper roller 71 constituting the lifting mechanism 76 is configured as shown in FIGS. 6 to 9 so that the rotation speed of the transport motor 73 can be adjusted without lifting. It is also possible to moderate the peak value of the tension applied to the uppermost sheet of the sheet bundle 80. <Embodiment 6> As shown in FIG.
A roller core portion 71b made of rubber or the like, a sponge layer 71c as an elastic foam, and a roller outer layer 71d for giving a grip force to the upper roller 71 are arranged in order from the roller shaft 71 to the outside. To have a buffering property.

As described above, by providing the sponge layer 71c on the upper roller 71, the speed of the lower roller 72 is increased with respect to the upper roller 71 when the sheet bundle 80 is lifted, so that the relative speed is suddenly generated. However, since the sponge layer 71c is distorted in the conveying direction of the sheet bundle 80, the tension acting on the uppermost sheet with which the upper roller 71 is in contact is moderately applied. That is, the roller has a damping property in the rotation direction. Therefore, the peak value of the tension applied to the uppermost sheet can be suppressed, so that damage to the uppermost sheet can be suppressed.

In the present embodiment, the sponge layer 71c is provided in order to provide the upper roller 71 with a buffer. However, the sponge layer 71c is made of an elastic foam, which causes the upper roller 71 to provide a buffer in the rotational direction. If so, a layer made of another material may be used. <Embodiment 7> Further, as shown in FIGS. 7A and 7B, the upper roller 71 is arranged in order from the roller shaft 71a to the outside, a roller core portion 71e made of a hard material and a sheet body (film) 71f. , And the lower roller 72 can be pressed against the sheet body 71f.

When an excessively strong force acts in the rotation direction, the sheet body 71f and the roller body 71f slide so as to slide in the rotation direction with respect to the roller core 71e.
As described above, the upper roller 71 may have a buffering property as a configuration in which the coefficient of friction between the two rollers is set.

As described above, when a certain force or more in the rotation direction acts on the surface layer (sheet body 71f) of the upper roller 71, the upper roller 71 slides with respect to the roller core 71e together with the uppermost sheet. When the sheet bundle 80 is lifted, if an excessively large tension acts on the uppermost sheet, the upper rollers 71
Acts on the roller core 71e.

Accordingly, similarly to the configuration shown in FIG. 6, the tension acting on the uppermost sheet in contact with the upper roller 71 is gradually applied, and the peak value of the tension applied to the uppermost sheet is suppressed. Therefore, damage to the uppermost sheet can be suppressed.

Also, in the example shown in FIG.
1 is configured to slide with respect to the roller core portion 71e together with the uppermost sheet.
1a, the friction coefficient between the upper roller 71 and the roller shaft 71a is set so that, when too much force acts on the upper roller 71 in the rotation direction, the friction coefficient between the two is set in the same manner as described above. Alternatively, the upper roller 71 may have a buffering property.

Further, even if the configuration applied to the upper roller 71 in FIG. 7 is applied to the lower roller 72, it is possible to provide a buffering property for relaxing the tension acting on the uppermost sheet of the sheet bundle 80. it can.

As described above, when a certain force or more in the rotation direction acts on one of the upper roller 71 and the lower roller 72, the roller on the buffer side slides with the uppermost sheet. Thus, when an excessively large tension acts on the uppermost sheet when the sheet bundle 80 is lifted, the roller having the buffering property moves in the transport direction.

Therefore, similarly to the configuration shown in FIG. 6, the tension acting on the uppermost sheet in contact with the upper roller 71 is gradually applied, and the peak value of the tension applied to the uppermost sheet is suppressed. Therefore, damage to the uppermost sheet can be suppressed. FIG. 7 (b)
FIG. 7 is a cross-sectional view orthogonal to the transport direction of the paper output roller 70 employing the configuration shown in FIG. <Embodiment 8> Further, as shown in FIG.
1 in order from the roller shaft 71a to the outer side.
It is also possible to configure the upper roller 71 with a buffering property by using 1 g and the flocking portion 71 h. FIG. 9 is an enlarged sectional view showing a state in which the sheet bundle 80 is being conveyed by the upper roller 71 and the lower roller 72 having the configuration shown in FIG.

As shown in FIG. 9, the flocked portion 71h of the upper roller 71 is pressed by the uppermost sheet when the sheet bundle 80 is sandwiched, and the fiber is inclined in the direction opposite to the conveying direction.
When the fibers are generated, the uppermost sheet slides in the conveying direction, so that the same operation and effect as the configuration shown in FIG. 6 or FIG. 7 can be obtained. <Embodiment 9> Further, the upper roller 71 is configured as shown in FIG. 10 or FIG. 11, and the sheet bundle 80 to be output is a sheet bundle having a small number of weakly bound sheets (thin) or a sheet bundle having a strong waist. Regardless of the number (thickness) of the number of sheets, it is also possible to wait without causing a buckling, and to stack the sheets on the offset tray 11 without disturbing the stacked state.

As shown in FIG. 10, at both ends of the lower roller 72 in the direction perpendicular to the direction of conveyance, wavy members 72b each having a diameter larger than that of the lower roller 72 and made of a sponge material made of an elastic foam are arranged. . That is, the lower roller 72
Has a configuration in which the end portion protrudes toward the sheet bundle 80 side from the center portion.

When the lower roller 72 has this configuration, as shown in FIG. 11 (a), when the sheet bundle 80 is a sheet bundle having a small number of weakly bound sheets (thin), the sheet material 8
0 in a direction perpendicular to the conveying direction, and the sheet bundle 8
The waist of the 0 can be strengthened to prevent the waist from breaking. However, in this case, the sheet bundle is stiffened so that the tension acting on the uppermost sheet when lifting the sheet bundle 80 being discharged does not exceed the shearing force of the uppermost sheet, and the lifting amount is accordingly adjusted. Need to be adjusted.

Further, as shown in FIG. 11B, when the sheet bundle 80 has a large number of stiff binding sheets (thick),
Since the stiffness of the sheet bundle 80 is strong, the wavy member 72b
Is pressed to the same height as the central portion when paper is output. Therefore, no trace of waving is generated on the sheet bundle 80, and the waist of the sheet bundle 80 is not unnecessarily strengthened. Therefore, a very strong tension is applied to the uppermost sheet to lift the sheet bundle 80. It is no longer necessary to perform this, and it is possible to suppress damage to the uppermost sheet. Further, there is no trace of the waving member 72b on the sheet bundle 80. <Embodiment 10> Further, as shown in FIG. 12, a waving member 72c using a film body instead of a sponge material may be arranged. Further, the wavy member 72
c so that the outer peripheral portion of the lower roller 72 can be separated from the lower roller 72.
2 is not fixed to the outer peripheral portion. FIG.
FIG. 7B shows a state in which the wavy member 72c bends and separates from the lower roller 72 when a stiff sheet bundle is discharged.

Thus, when the sheet bundle 80 is a small (thin) sheet having a small number of stapled sheets, the same operation and effect as those shown in FIG. 10 can be obtained. If the sheet bundle 80 has a strong stiffness and has a large number of sheets (thick), the wavy member 72 is selected depending on the stiffness of the sheet bundle 80.
As shown in FIG. 13, the outer peripheral portion (the portion protruding from the sheet bundle 80) in FIG. 13c escapes in the direction away from the lower roller 72, so that the same operation and effect as in the case of the configuration shown in FIG. Obtainable.

In the present embodiment, the waving members 72b and 72c are provided on the lower roller 72 side, but they may be provided on the upper roller 71. The material used for the waving members 72b and 72c is not limited to sponge or film, but may be any other member having similar properties.

As described above, the sheet post-processing apparatus 1 according to the present embodiment uses the transport motor 73 of the lifting mechanism 76 and the clutch 75 when discharging the stapled sheet bundle 80 with the above-described configuration. Thus, the amount, timing and period of lifting can be adjusted.

As a result, the sheet bundle 8 at the optimal timing
0 can be lifted, and the amount of lifting can be adjusted to eliminate problems such as breakage of the sheet bundle 80 and breakage of the waist.

[0160]

According to the present invention, the discharge sheet discharged from the image forming apparatus is subjected to binding processing, and the lower roller is discharged from the upper roller of the discharge roller pair while the bound sheet bundle is discharged to the discharge tray. In a sheet post-processing apparatus that raises the speed and raises the leading end side of the sheet bundle in the discharge direction, a storage unit that stores information of sheet bundle characteristics obtained by initial setting and binding processing, and according to the sheet bundle characteristics,
Control means for adjusting the lifting amount of the sheet bundle.

According to the above configuration, when the sheet bundle is discharged to the discharge tray, the discharge speed of the lower roller with respect to the upper roller is increased so that the uppermost sheet of the sheet bundle slides with respect to the second and lower sheets. , The top sheet pulls the second and lower sheets. With such a configuration, the leading end side in the discharge direction of the sheet bundle is lifted. Accordingly, the leading end of the sheet bundle being discharged does not rub against the surface of the stacked sheets that have been discharged to the discharge tray first, so that the image quality of the surface of the stacked sheets does not deteriorate. . Further, the leading end of the sheet bundle being discharged does not catch on the staples of the stacked sheet bundle, so that the stacking state is not disturbed.

Further, the storage means stores the sheet bundle characteristics, specifically, the number of sheets bound in the sheet bundle, the sheet size, the binding position of the sheet bundle, the thickness of the single sheet, the type of sheet, and the like. Information is stored. The sheet post-processing apparatus itself obtains such information on the sheet bundle characteristics at the stage when the user performs the initial setting and the binding process, and stores the sheet bundle characteristics in the storage unit.

When the sheet bundle is lifted, an elastic force generated by bending a sheet (other sheet) other than the top sheet in the sheet bundle acts on the top sheet of the sheet bundle. If this elastic force exceeds the shear strength of the top sheet, the top sheet will break. Therefore, the lifting amount of the sheet bundle is adjusted according to the sheet bundle characteristics stored in the storage means so that the elastic force does not exceed the shear strength of the uppermost sheet.

That is, when the shear strength of the top sheet is low or the elastic force of other sheets is large, the lifting amount is reduced, and when the shear strength of the top sheet is high or the elastic force of other sheets is small. If so, increase the lift. Thus, it is possible to prevent the top sheet from being damaged when the sheet bundle is lifted.

According to the present invention, the discharge sheet discharged from the image forming apparatus is subjected to binding processing, and while the bound sheet bundle is being discharged to the discharge tray, the discharge speed of the lower roller with respect to the upper roller of the discharge roller pair is adjusted. In the sheet post-processing apparatus for lifting the leading end in the discharge direction of the sheet bundle, storage means for storing information on the state of the discharged sheet on the discharge tray obtained by initial setting, binding processing, and discharging operation, and the discharged sheet Control means for adjusting the lifting amount of the sheet bundle in accordance with the state of (1).

With the above arrangement, the storage means stores information on the state of the discharged sheets already discharged on the discharge tray, that is, whether the load on the discharge tray is a sheet bundle or a single sheet, In the case of a bound sheet bundle, information such as the binding position and binding location is stored. The sheet post-processing apparatus itself obtains such information on the state of the discharged sheet through the initial setting, the binding processing, and the discharging operation, and causes the storage unit to store the state of the discharged sheet.

Then, the control means adjusts the lifting amount of the sheet bundle in accordance with the state of the discharged sheet stored in the storage means. Thus, even if the top one of the stacked items on the discharge tray is, for example, an unbound sheet alone, setting the lifting amount to a large value allows the sheet to be discharged onto the sheet alone. The stacking state is not disturbed by the contact of the inner sheet bundle.

Further, for example, when all the sheet bundles stacked on the discharge tray have the same binding position, the binding positions overlap and the binding position portion is higher than the other portions. In such a case, by setting the lifting amount of the sheet bundle to be large, the sheet bundle being discharged is caught by the binding portion of the sheet bundle on the discharge tray, and the lowermost sheet of the sheet bundle being discharged is set. Will not break.

Therefore, the sheet bundle can be discharged without disturbing the stacked state on the discharge tray and without causing the sheet to be damaged during the discharge.

According to the present invention, the discharging sheet discharged from the image forming apparatus is subjected to binding processing, and the discharging speed of the lower roller with respect to the upper roller of the discharging roller pair is adjusted while the bound sheet bundle is being discharged to the discharging tray. In a sheet post-processing apparatus that raises the leading end of the sheet bundle in the discharging direction, the sheet bundle lifting operation is performed according to the rigidity of a portion of the sheet bundle being discharged between the position sandwiched by the pair of discharge rollers and the leading end in the discharging direction. Is provided.

According to the above configuration, the rigidity of the portion of the sheet bundle being discharged from the holding position where the sheet bundle is held by the pair of discharge rollers to the leading end in the discharge direction is the position where the sheet bundle is held between the pair of discharge rollers. Can be considered as the waist of the sheet bundle from to the leading edge of the sheet.

For example, if the length from the nipping position to the leading end of the sheet output side is too short and the stiffness of the sheet bundle is strong, that is, if the leading end of the sheet bundle starts the lifting operation at a very early timing after starting to output the sheet. However, there is a possibility that a large tension is applied to the uppermost sheet and the uppermost sheet is damaged. Therefore, the control means adjusts the timing of starting lifting according to the rigidity of the sheet bundle, thereby preventing the top sheet from being damaged.

The waist of the sheet is determined by the sheet length in the conveying direction, the width of the sheet bundle in the conveying orthogonal direction, the fiber direction of the sheet,
This depends on the number of sheets constituting the sheet bundle and the like. The length of the sheet width from the nipping position to the leading end in the discharge direction can be calculated, for example, by subtracting the time when the discharge roller pair detects the leading end of the sheet bundle from the current time at a constant conveying speed. is there. Further, the width of the sheet bundle in the conveyance orthogonal direction is information obtained in advance according to the sheet size, and the information regarding the number of sheet bundles is also given to the sheet post-processing apparatus itself by initial setting or the like.

According to the present invention, the discharging sheet discharged from the image forming apparatus is bound, and the discharging speed of the lower roller with respect to the upper side of the discharging roller pair is increased while discharging the bound sheet bundle to the discharging tray. In the sheet post-processing device that lifts the leading end of the sheet bundle in the discharge direction, the discharged length of the sheet bundle being discharged from the position pinched by the pair of discharge rollers to the leading end in the discharge direction is calculated. Length calculation means, when the discharged length is equal to or more than a predetermined length,
Control means for starting the lifting operation of the sheet bundle is provided.

With the above configuration, for example, for a certain sheet material and a certain number of sheets, the length from the holding position held by the discharge roller to the front end portion in the discharging direction is used as a parameter, and the number of sheets is limited to the certain number of sheets. If the rigidity of the bundle is given to the control means in advance, the rigidity of the sheet bundle at the discharged portion can be determined by calculating the discharged length.

This makes it possible to optimally control the timing for lifting the sheet bundle being discharged. Therefore,
The control unit adjusts the timing of starting the lifting in accordance with the rigidity of the sheet bundle, thereby preventing the uppermost sheet from being damaged.

The present invention is provided with speed adjusting means for gradually changing the speed of at least one of the upper and lower rollers.

According to the above configuration, when the speed of the upper roller is decreased or the speed of the lower roller is increased to raise the sheet to generate the relative speed between the two rollers, the relative speed gradually increases. So that it can be adjusted.

As described above, when the sheet bundle is lifted, the relative speed between the upper roller and the lower roller is not increased rapidly but is increased gradually, so that the peak of the tension acting on the uppermost sheet at the time of lifting is increased. By reducing the value, the maximum value of the tension can be suppressed.

Therefore, the possibility that the uppermost sheet of the sheet bundle being discharged is damaged from the binding portion can be reduced as compared with the case where the relative speed is suddenly changed. In addition, since there is no rapid increase in the relative speed, no extra force due to acceleration acts on the sheet bundle being discharged, so that the uppermost sheet of the sheet bundle is not damaged.

In the present invention, the upper roller has a cushioning property in the direction of rotation.

According to the above configuration, even when the relative speed between the upper roller and the lower roller suddenly increases, the tension applied to the uppermost sheet of the sheet bundle is increased by the upper roller having a buffering property in the rotating direction. (The roller has a buffering property against an increase in sheet tension). Therefore, the possibility that the uppermost sheet of the sheet bundle being discharged is damaged from the binding portion can be further reduced.

In the present invention, the upper roller has an elastic foam layer.

With the above configuration, even when the relative speed of the lower roller to the upper roller is rapidly increased when lifting the sheet bundle, the elastic foam layer is distorted in the sheet bundle conveying direction. The tension acting on the uppermost sheet becomes lower.

Therefore, since the peak value of the tension applied to the uppermost sheet can be suppressed, the damage to the uppermost sheet can be suppressed with a simpler structure than a mechanical structure.

According to the present invention, the upper roller has a surface layer that moves in the rotational direction with respect to the axis of the upper roller when a predetermined force or more acts in the rotational direction.

With the above structure, the upper roller is provided with a buffer in the rotational direction by providing the upper roller with a surface layer that moves (slids) with respect to the axis when a force in the rotational direction of a certain degree or more acts on the upper roller. .

Thus, if an excessively large tension acts on the uppermost sheet when lifting the sheet bundle, the surface layer moves together with the uppermost sheet in the sheet bundle conveying direction, and the upper roller is applied to the uppermost sheet in contact with the uppermost sheet. The tension becomes gentle, the peak value of the tension applied to the uppermost sheet can be suppressed, and the uppermost sheet can be prevented from being damaged during lifting.

In the present invention, a flocked portion made of fiber is provided on the contact surface of the upper roller with the sheet.

With the above structure, the flocked portion provided on the contact surface of the upper roller with the sheet (upper roller surface) contacts the sheet bundle during unloading, and is pressed by the uppermost sheet to cause the fibers to move in the sheet bundle transport direction. Will be inclined to the opposite side. When this fiber occurs, it serves to slide the top sheet in the transport direction. With such a configuration, the upper roller has a cushioning property in the rotation direction.

Therefore, even if tension is suddenly applied to the uppermost sheet in contact with the flocking portion of the upper roller,
This tension will gradually change. Thus, the peak value of the tension can be suppressed, so that the uppermost sheet of the sheet bundle can be prevented from being damaged during lifting.

In the present invention, at least one of the upper roller and the lower roller is provided at the end in the direction perpendicular to the conveyance direction.
It is made of a material with lower rigidity than the central part in the direction perpendicular to the conveyance,
In addition, a wavy member that protrudes toward the sheet side from the central portion is provided.

According to the above configuration, when the bundle of sheets to be discharged is a small (thin) sheet having a weak waist, the sheet bundle can be wavy in the direction perpendicular to the conveyance direction to strengthen the waist and prevent the waist from breaking. On the other hand, when the sheet bundle has a large number of stiff sheets (thick), the wavy member having a lower rigidity than the central portion is pressed by the sheet bundle due to the strong stiffness of the sheet bundle and is almost as large as the central portion. Pressed to the height of

Therefore, no trace of waving is produced on the sheet bundle,
Also, since the waist of the sheet bundle is not unnecessarily strengthened, it is not necessary to apply a very strong tension to the uppermost sheet in order to lift the sheet bundle. Damage can be suppressed.

In the present invention, the wavy member is made of an elastic foam.

According to the above configuration, since the wavy member is made of elastic foam, it is possible to prevent the wavy member from being attached to the sheet bundle when discharging a stiff and large (thick) sheet bundle. can do.

[Brief description of the drawings]

FIG. 1 is a view illustrating an embodiment of a sheet post-processing apparatus of the present invention, and is an explanatory view illustrating an operation of a lifting mechanism of the sheet post-processing apparatus.

FIG. 2 is an overall configuration diagram schematically showing the sheet post-processing apparatus.

FIG. 3 is a front view showing a structure of a lifting mechanism in the sheet post-processing apparatus.

FIG. 4 is a side view showing a structure of a lifting mechanism in the sheet post-processing apparatus.

FIG. 5 is an explanatory diagram showing a sheet bundle passing through a sheet output roller in the sheet post-processing apparatus.

FIG. 6 is a side cross-sectional view illustrating a structure of an upper roller in Embodiment 6 of the sheet post-processing apparatus.

FIG. 7A illustrates a sheet post-processing apparatus according to a seventh embodiment.
3 is a cross-sectional view of the structure of the upper roller in FIG.

FIG. 8 is a side sectional view showing a structure of an upper roller in Embodiment 8 of the sheet post-processing apparatus.

9 is an enlarged cross-sectional view illustrating a state in which a sheet bundle is being conveyed by an upper roller and a lower roller having the structure illustrated in FIG. 8;

FIG. 10 is a front view showing a structure of an upper roller and a lower roller in Embodiment 9 of the sheet post-processing apparatus.

11A is an explanatory diagram illustrating a state in which a sheet bundle having a low stiffness is conveyed by an upper roller and a lower roller having the structure illustrated in FIG. 10; FIG. FIG. 9 is an explanatory diagram illustrating a state in which a stiff sheet bundle is being conveyed by an upper roller and a lower roller.

FIG. 12 is a front view showing a structure of an upper roller and a lower roller in Embodiment 10 of the sheet post-processing apparatus.

13 is an explanatory diagram illustrating a state in which a stiff sheet bundle is being conveyed in the structure illustrated in FIG. 12;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sheet post-processing apparatus 2 Copy machine 11 Offset tray (discharge tray) 14 Upper staple tray (post-processing tray) 15 Lower staple tray (post-processing tray) 59 Stapler 70 Paper output roller (discharge roller) 71 Upper roller 72 Lower roller 76 Lifting mechanism

Claims (11)

[Claims] A discharge sheet discharged from an image forming apparatus is subjected to binding processing, and a discharge speed of a lower roller with respect to an upper roller of a discharge roller pair is increased while discharging a bound sheet bundle to a discharge tray. In a sheet post-processing apparatus that lifts the leading end side of the sheet bundle in the discharge direction, a storage unit that stores information of sheet bundle characteristics obtained by initial setting and binding processing, and adjusts a lifting amount of the sheet bundle according to the sheet bundle characteristics. A sheet post-processing apparatus, comprising: 2. A discharge sheet discharged from an image forming apparatus is subjected to binding processing, and a discharge speed of a lower roller with respect to an upper roller of a discharge roller pair is increased while discharging a bound sheet bundle to a discharge tray. In a sheet post-processing apparatus for lifting the leading end of the sheet bundle in the discharge direction, storage means for storing information on the state of discharged sheets on a discharge tray obtained by initial setting, binding processing, and discharging operation; And a control means for adjusting the lifting amount of the sheet bundle according to the following. 3. A binding process is performed on a discharge sheet discharged from the image forming apparatus, and a discharge speed of a lower roller with respect to an upper roller of a discharge roller pair is increased while discharging a bound sheet bundle to a discharge tray. In a sheet post-processing apparatus that lifts the leading end of the sheet bundle in the discharging direction, the sheet bundle lifting operation is performed according to the rigidity of a portion of the sheet bundle being discharged from the position sandwiched by the pair of discharge rollers to the leading end in the discharging direction. A sheet post-processing device comprising a control means for starting. 4. A process for binding a discharge sheet discharged from the image forming apparatus, and increasing a discharge speed of a lower roller with respect to an upper side of a discharge roller pair while discharging a bound sheet bundle to a discharge tray. In the sheet post-processing apparatus that lifts the leading end of the bundle in the discharging direction, the unloaded length that calculates the discharged length of the sheet bundle being discharged from the position pinched by the pair of discharging rollers to the leading end in the discharging direction. A sheet post-processing apparatus comprising: a calculating unit; and a control unit configured to start a lifting operation of a sheet bundle when the discharged length is equal to or longer than a predetermined length. 5. The sheet post-processing apparatus according to claim 1, further comprising a speed adjusting means for gradually changing the speed of at least one of the upper roller and the lower roller. 6. The sheet post-processing apparatus according to claim 1, wherein the upper roller has a buffering property in a rotation direction thereof. 7. The sheet post-processing apparatus according to claim 6, wherein the upper roller has an elastic foam layer. 8. The sheet post-processing apparatus according to claim 6, wherein the upper roller has a surface layer that moves in the rotation direction with respect to the axis of the upper roller when a force greater than a predetermined force acts in the rotation direction. . 9. The sheet post-processing apparatus according to claim 6, wherein a flocked portion made of fiber is provided on a surface of the upper roller that contacts the sheet. 10. At least one of the upper roller and the lower roller is made of a material having a lower rigidity at an end portion in the direction perpendicular to the conveyance direction than a center portion in the direction perpendicular to the conveyance direction, and has a sheet more than the center portion. 10. A wavy member projecting to the side is provided.
A sheet post-processing device according to the above. 11. The sheet post-processing apparatus according to claim 10, wherein the wavy member is made of an elastic foam.