JP2001130817A - Sheet aftertreatment device and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To crush air layers and curls generated in sheets stacked on a stack tray and to reduce the up-and-down movement amount of the stack tray for gaining the height of a device. SOLUTION: Sheet holding paddles 10, 11 are provided for holding downward a bunch of sheets stacked on the stack tray 4 and the stack tray 4 is moved down in the state of holding the bunch of sheets by the paddles. After a pawl 7a of a bunched sheet carrying belt 7 is passed on the bunch of sheets, the stack tray 4 is moved up to keep the uppermost face of the bunch of sheets in position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet post-processing apparatus provided in an image forming apparatus for forming an image on a sheet, such as a copying machine, a facsimile, and a printer.

[0002]

2. Description of the Related Art In recent years, in an image forming apparatus such as a copying machine, for a plurality of sheets on which images are sequentially formed by an image forming means, for example, the ends of the sheets are aligned, and stapling (stapling) is performed on the aligned sheets. ) And a post-processing such as punching, and discharging a post-processed sheet bundle (hereinafter, referred to as a sheet bundle) onto a stack tray. ing.

Hereinafter, such a conventional sheet post-processing apparatus will be described with reference to FIG. FIG. 13 is a side sectional view showing the outline and operation of a conventional sheet post-processing apparatus connected to an image forming apparatus. In FIG. 13, reference numeral 3 denotes an alignment tray on which sheets on which images have been formed are stacked, reference numeral 73 denotes a stapler unit for performing staple processing on each sheet on the alignment tray 3, and reference numeral 4 denotes a sheet bundle processed by the stapler unit 73. The stack tray 7 is a sheet bundle transport belt that transports the sheet bundle on the alignment tray 3 to the stack tray 4. Reference numerals 5 and 6 denote JOG plates for aligning the sheets on the alignment tray 3 in the width direction.

In this sheet post-processing apparatus, a sheet on which an image is formed by an image forming unit is sequentially conveyed by a guide unit and rollers (not shown), and is placed on an alignment tray 3.

In the sheet post-processing apparatus, when an image-formed sheet is placed on the alignment tray 3, the JOG plates 5, 6 are moved by a motor (alignment motor) (not shown) in the sheet conveying direction (arrow (f)). Direction), the sheets are sandwiched by the JOG plates 5 and 6, and alignment in the width direction is performed on each sheet sequentially sent. In the alignment of each sheet in the transport direction, the abutting sheet is returned in a direction opposite to the transport direction and is pushed to a predetermined reference position by rotating a return roller (not shown) disposed above the alignment tray 3. Do it by hitting it.

The stapler unit 73 includes the alignment tray 3
A predetermined number of sheets are stapled at the upper left corner of the image surface of the stacked sheets.

The sheet bundle conveying belt 7 is stretched around a driving pulley 7b and a driven pulley 7c driven by a conveying motor (not shown), and the driving pulley 7b is driven to rotate clockwise in FIG. 13 by the conveying motor. As a result, the sheet rotates in the same direction, and conveys the sheets stacked on the alignment tray 3 to the stack tray 4. Note that the sheet bundle conveying belt 7 has a claw 7a for locking the rear end of the sheets stacked on the alignment tray 3, and this claw 7a is used when the sheet is conveyed. The rear end of the sheet is pushed out to the base end of the stack tray 4.

The stack tray 4 includes a support member (not shown),
The rail 15 is formed by the wall 15 and slidably supports the support member, and is configured to be vertically reciprocable with respect to the wall 15 by a motor for driving the support member and the like.

A sheet upper surface pressing member 201 shown in FIG. 13 is displaceably supported above the base end side of the stack tray 4. This sheet upper surface pressing member 201
The drive unit (not shown) is configured to be displaced so as to reciprocate in the front-rear direction of the wall 15.

[0010] In the sheet post-processing apparatus, as shown in FIG.
03 is provided. Here, the sheet contact member 202 is rotatably disposed about a fulcrum 202a, and an urging member (not shown) such that one end of the sheet contact member 202 contacts the uppermost sheet surface on the base end side of the stack tray 4. Powered by On the other hand, the sensor unit 2
03 is normally shielded from light by the end of the sheet contact member 202 opposite to the sheet contact portion, and the sheet contact member 202
Is rotated to release a predetermined detection signal when the light blocking state is released.

In the sheet post-processing apparatus, when a stapling process is instructed, a predetermined number of sheets stacked on the alignment tray 3 and aligned (sheet bundle) are stapled by the stapler unit 73 at the upper left corner of the image plane. The part is needled. When the sheet bundle conveying belt 7 is driven, the post-processed sheet bundle is discharged onto the stack tray 4. If the stapling process is not instructed, the aligned sheet bundle on the alignment tray 3 is
When the sheet bundle conveying belt 7 is driven without performing stapling by the stapler unit 73, the sheet bundle is discharged onto the stack tray 4 in a state where it is not bound.

In the sheet post-processing apparatus, every time a sheet bundle is discharged to the stack tray 4, the sheet upper surface pressing member 201 is displaced, the stack tray 4 is raised and lowered,
The rotation operation of the sheet bundle conveying belt 7 and the like are performed. Less than,
The operation of each unit at the time of discharging to the stack tray 4 will be described in detail with reference to FIGS.

FIG. 13A shows that the aligned sheet bundle 210 is pushed out in the direction of arrow (f) by the claw 7a provided on the sheet bundle conveying belt 7, and
5 shows a state in which the sheet is discharged onto the already loaded sheet bundle 211 existing in FIG. At this time, the rear end side of the sheet bundle 210
It is located on the sheet upper surface pressing member 201.

FIG. 13B shows a state in which the stack tray 4 moves downward thereafter. That is, in the sheet post-processing apparatus, when the sheet bundle is discharged onto the stack tray 4, the stack tray 4 starts descending in the direction of the arrow (d) after a predetermined time has elapsed. At about the same time,
When the sheet upper surface pressing member 201 retracts in the direction of the arrow (G), the leading end of the sheet bundle 210 is stacked on the already-stacked sheet bundle 211.

In the sheet post-processing apparatus, when the upper surface of the sheet bundle 210 descends, the sheet contact member 202 rotates clockwise in FIG.
03 is released, a predetermined detection signal is output from the sensor unit 203, and when this detection signal is output, the lowering operation of the stack tray 4 stops. That is, when the upper surface of the sheet bundle 210 is lowered to a predetermined position,
The lowering operation of the stack tray 4 ends. At this time, the sheet bundle conveying belt 7 rotates clockwise in FIG.
The claw portion 7a is turned back by the driven pulley 7c to form the sheet bundle 2
After passing above the position 10, it stops at a predetermined position and prepares for the next bundle processing (sheet alignment).

From this state, the sheet upper surface pressing member 2
13 moves in the direction of the stack tray 4 from the retracted position, and stops in a state where it protrudes from the wall 15 to a predetermined position with respect to the stack tray 4 as shown in FIG. Next, the stack tray 4 starts to rise in the direction of the arrow (e), and the uppermost sheet surface of the loaded sheets (sheet bundles 211 and 210) is pressed by the sheet upper surface pressing member 201. The ascent is stopped. Thus, the ends of the sheet bundle 211 and the sheet bundle 210 are compressed.

In addition to the function of compressing the end of the sheet bundle stacked on the stack tray 4 as described above, the sheet upper surface pressing member 201 is used to make the upper sheet of the already stacked sheet bundle particularly the unbound bundle ( In the case of a bundle that has not been staple-bound, it has a function of preventing the sheet bundle to be discharged next from being taken out in the discharge direction and causing misalignment in the transport direction.

[0018]

However, in the conventional sheet post-processing apparatus, when the stack tray 4 is lowered, there is nothing to press the sheet bundle. Therefore, as shown in FIG. In the case of a sheet bundle, air accumulates between each sheet, an air layer is formed, and the thickness 11 of the leading end of the sheet bundle 212 increases. (2) Particularly, a curled sheet bundle In the case of (1), the sheet is bulky in the stacking height direction by the amount of the curl. (3) Furthermore, particularly in the case of a curled sheet bundle, the leading end side thereof leans against the wall portion 15; And other problems.

As a result, in the conventional sheet post-processing apparatus,
Since the proper sheet height cannot be detected and the descending amount of the stack tray 4 is increased by the air space or the curl amount, the height of the entire image forming apparatus is increased by the moving amount of the stack tray 4 up and down. Need to be higher.

When the image forming apparatus such as a copying machine or a facsimile is provided with an image reading means (scanner section) for reading an image of an original, the image forming means (printer section) and the scanner section are provided. If a sheet post-processing apparatus is to be disposed between the scanner unit and the stack tray, the position of the scanner unit must be increased by the amount of movement of the stack tray 4 up and down, which may deteriorate user operability such as document setting. become. Furthermore, to avoid this, stack tray 4
, The number of sheets stacked on the stack tray 4 needs to be reduced, and the specification must be reduced.

An object of the present invention is to provide a sheet post-processing apparatus which improves the stackability of sheets stacked on a stack tray and reduces the amount of movement when the stack tray is moved up and down, and a sheet post-processing apparatus. An object of the present invention is to provide an image forming apparatus.

[0022]

According to a first aspect of the present invention, there is provided a sheet post-processing means for performing a predetermined post-processing on a sheet, and the sheet passing through the sheet post-processing means is discharged. A stack tray movable in the vertical direction, and sheet pressing means for pressing the uppermost sheet surface discharged onto the stack tray, wherein the sheet pressing means removes the uppermost sheet surface discharged onto the stack tray. The stack tray moves downward in a pressed state.

[0023]

Embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiment, an example in which the present invention is applied to an electrophotographic image forming apparatus (copier) will be described.

First, an overall configuration of a copying machine 100 according to an embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, the copier 100 includes a printer unit 101 having an image forming unit 106 for forming an image on a sheet,
Scanner unit 1 as an image reading unit that reads an image of a document
Further, the sheet binding unit 1 serving as a sheet post-processing device for performing post-processing on a sheet on which an image has been formed by the image forming unit 106 is provided between the lower printer unit 101 and the upper scanner unit 102. The configuration is such that it is arranged in the housing 100a. In the figure, reference numeral 102a denotes the scanner unit 1.
02 is the bottom plate and the top plate of the sheet binding unit 1.

The printer unit 101 includes the image forming unit 10
6 and a sheet feeding unit 105 for feeding sheets to the image forming unit 106. In the copying machine 100, four cassette feeding units 105A, 105A, 105B, 105C, and 105D, and a manual feed unit 105E above the cassette feed unit 105D are provided.

Each cassette feeding section 10 of the printer section 101
5A to 105D are picked up by a sheet stacking cassette 110 detachable from the housing 100a, a pickup roller 111 for picking up the top sheet stacked in the sheet stacking cassette 110, and a pickup roller 111, respectively. A separation roller pair 112 that separates the sheet into one sheet, and a conveyance roller pair 113 that conveys the sheet separated into one sheet by the separation roller pair 112 to a sheet conveyance path connected to the image forming unit 106 are provided. The sheet fed by each of the cassette feeding units 105A to 105D is conveyed to the image forming unit 106 by a conveyance roller pair 114 arranged in a sheet conveyance path.

The manual feed unit 1 of the printer unit 101
The image forming unit 05E includes a sheet mounting tray 115 detachably attached to one side surface of the housing 100a and a sheet manually mounted on the sheet mounting tray 115.
6 is provided with a conveyance roller 116.

During the image forming operation, the printer unit 101 controls each of these feeding units 10 under the control of a CPU (not shown).
The sheet is fed to the image forming unit 106 by any one of the feeding units 5A to 105D.

The image forming unit 106 of the printer unit 101
An image of the document read by the scanner unit 102 is formed on a sheet by an electrophotographic method. Image forming unit 106
As shown in FIG. 1, a laser scanner 121 that emits laser light corresponding to image information of a document read by the scanner unit 102, and a laser scanner 121 that synchronizes with an image forming operation.
A registration roller 122 that conveys the sheet fed by the feeding unit, a photoconductor drum 123 that forms an electrostatic latent image based on a laser beam emitted from a laser scanner 121, and a surface of the photoconductor drum 123 are charged. And a developing device 125 for developing the electrostatic latent image on the photosensitive drum 123, and a fixing device 126.

In the image forming unit 106, a laser beam corresponding to the image information of the document is emitted from the laser scanner 121, and scans the surface of the photosensitive drum 123, so that the uniformly charged surface of the photosensitive drum 123 is scanned. An electrostatic latent image is formed. Then, this electrostatic latent image is developed
, A toner image is formed on the photosensitive drum 123.

Further, the toner image on the photosensitive drum 123 is transferred by the transfer charger 124 to the sheet fed by the registration roller 122 which rotates in synchronization with the rotation of the photosensitive drum 123, The image is transferred to the first surface of the sheet. The sheet to which the toner image has been transferred is conveyed to the fixing device 126, and is heated and pressed by the fixing device 126, so that the toner image on the sheet surface is fixed. The sheet on which the toner image has been fixed by the fixing device 126 of the image forming unit 106 is guided to a sheet binding unit 1 described later in detail via a conveyance path, and after a predetermined post-processing is performed, the sheet is discharged to a sheet discharging unit. It is discharged from 108.

On the other hand, the scanner unit 102 includes a scanning light source unit 131 including a scanning light source and a mirror, and a housing 100a.
Platen glass 132 attached to the upper surface of the document as a document table, housing 100a and platen glass 132
A document pressure plate 133 that pivots openably and closably with respect to a reflection mirror 134 that reflects light from the scanning system light source 131;
Scanning light source 131 reflected by reflection mirror 134
135 that collects and outputs light from
The photoelectric conversion device 136 includes a photoelectric conversion element 136 that is a light receiving unit that receives the light from the scanning system light source unit 131 condensed by 35, and an image processing unit (not shown) that processes an output signal from the photoelectric conversion element 136.

In the scanner section 102, with the original pressure plate 133 opened, the original is placed on the platen glass 132 such that the surface to be copied is on the lower side.
Is closed, and the original is pressed so that the original does not move. Then, when a reading start key (not shown) is pressed, in the scanner unit 102, the scanning system light source unit 131 scans the lower part of the platen glass 132 to read image information on the document surface. The image information of the document surface scanned by the scanning light source unit 131 is projected on the light receiving element 136 by the reflection mirror 134 and the lens 135 and the image information is read. The image information is processed by the image processing unit, converted into an electric signal, and transmitted to the laser scanner 121 of the image forming unit 106 described above.

[First Embodiment] Next, a first embodiment of a sheet binding section (hereinafter, referred to as a sheet post-processing apparatus) 1 disposed between the printer section 101 and the scanner section 102 described above. An embodiment will be described with reference to FIGS.

As shown in FIGS. 1 and 2, the sheet post-processing apparatus 1 includes a conveyance guide unit 71 for guiding a sheet on which an image has been formed by the image forming unit 106, and a conveyance guide unit 71.
Aligning means including an alignment tray 3 as a sheet stacking table and JOG plates 5 and 6 as sheet aligning units for stacking image-formed sheets that have passed through and aligning the ends of the sheets; The sheet that has passed through the unit 71 is stapled to a transport roller 72 and a return roller 74 that transport the sheet to the alignment tray 3 and a bundle of aligned sheets stacked on the alignment tray 3 (hereinafter, referred to as a sheet bundle). A stapler unit 73 serving as a sheet binding unit that performs processing (staple processing) to bind sheets, a stack tray 4 on which sheets post-processed by the stapler unit 73 are discharged and stacked, and a post-processed sheet on the alignment tray 3 And a sheet bundle transport belt 7 and 8 for transporting the sheet bundle to the stack tray 4.

Here, a sheet detection sensor 75 for detecting the passage of a sheet is disposed in the conveyance guide section 71, and a sheet presence / absence sensor 77 for detecting the presence / absence of a sheet is disposed in the stack tray 4. The detection signals from these sensors 75 and 77 are transmitted to the CPU.

The sheet on which an image has been formed by the image forming unit 106 of the printer unit 101 is supplied to the conveyance guide unit 71 with the image surface facing downward. At this time, the leading edge and the trailing edge are detected by the sheet detecting sensor 75. . A detection signal output from the sheet detection sensor 75 based on this detection is used as a reference for detecting a sheet jam, timing for accelerating or decelerating a discharge motor, and timing for subsequent sheet alignment, stapling, and sheet bundle conveyance.

The sheet on which an image has been formed after passing through the transport guide 71 is transported by a transport roller 72 disposed above the transport guide 71 on the downstream side in the sheet transport direction and a transport guide 7.
The sheet is conveyed to the alignment tray 3 located below the return roller 74 by the return roller 74 disposed below the downstream side in the sheet conveyance direction.

Here, the conveying roller 72 is driven to rotate in the counterclockwise direction in FIG. 1 by a discharge motor (not shown), and the sheet passing through the conveying guide 71 is moved to the lower alignment tray 3.
Transport to On the other hand, the return roller 74 has a predetermined coefficient of friction μ, and is driven to rotate clockwise in FIG. 1 by a motor (not shown) so that the sheet placed on the alignment tray 3 is moved to the sheet rear end reference position. Return to position.

The stapler unit 73 is provided with a stapling unit (not shown) for binding sheets on the side of the transport guide unit 71 in FIG. Can be stapled at the upper left corner of the image plane.

The alignment means of the sheet post-processing apparatus 1 is JOG
It is composed of plates 5 and 6, a reference plate, a rack, a home position sensor, and a matching motor. In the matching means, JOG
When the plates 5 and 6 are moved in a direction orthogonal to the sheet conveying direction by an alignment motor (not shown), the sheets stacked on the alignment tray 3 are brought into contact with the reference plate and aligned.

The sheet bundle conveying belts 7 and 8 have claw portions 7a and 8a for holding the end side of the sheet, and are rotatably attached to driving pulleys 7b and 8b driven by a conveying motor (not shown). Between the driven pulleys 7c and 8c. A home position sensor (not shown) for detecting the positions of the claw portions 7a, 8a is attached near the sheet bundle conveying belts 7, 8, and the conveying motor is controlled based on a detection signal of the home position sensor. It has become so. The initial state of the sheet bundle conveying belts 7, 8 is set so that the claw portions 7a, 8a are located at the sheet rear end reference position. Then, the sheet bundle conveying belts 7, 8
When the drive pulleys 7b and 8b are driven to rotate clockwise in FIG. 1, they rotate in the same direction to rotate the respective sheets stacked on the alignment tray 3 so that the stack tray 4 rotates.
Conveyed and discharged.

The stack tray 4 includes a tray 10
A support member (not shown) for supporting at 0a, a rail member for supporting the support member slidably with respect to the housing 100a, and a driving unit including a motor are supported so as to be vertically movable in the height direction of the apparatus. I have.

In the sheet post-processing apparatus 1, when a sheet is detected on the stack tray 4 by the sheet presence / absence sensor 77 on the stack tray 4, a new job is not accepted.

In the sheet post-processing apparatus 1, the wall 15
A stack tray lower limit sensor (not shown) is provided at the lower stack tray lower position. When the stacked sheet amount increases, the stack tray 4 is lowered, and when the stack tray 4 reaches the stack tray lower limit position, the stack tray lower limit sensor detects the stack tray 4 and stops the vertical movement of the stack tray 4 to take out the stacked sheet bundle. Thus, a display suggesting to the user is performed on the display unit (not shown).

Further, the sheet post-processing apparatus 1 is provided with a sheet height detection sensor having a sheet contact member 12 and a sensor section 13, as shown in FIG. here,
The sheet contact member 12 is a substantially L-shaped member that is rotatably arranged around a fulcrum 12 a, and one end of the sheet contact member 12 contacts the uppermost sheet surface on the base end side stacked on the stack tray 4. It is urged by an urging member (not shown) so as to be in contact therewith. On the other hand, the sensor unit 13 is normally shielded from light by the other end of the sheet contact member 12, and outputs a predetermined detection signal when the sheet contact member 12 is rotated to release the light-shielded state. Has become.

Note that, as shown in FIG.
Convex ribs 14 and 16 are formed. This rib 1
Reference numerals 4 and 16 denote friction compensation between the sheet end and the wall 15 when the stack tray 4 moves up and down when the end of the sheet stacked on the stack tray 4 abuts on the wall 15. It is for reducing.

In the sheet post-processing apparatus 1, the detection signal from the sheet height detection sensor is set to CP so that the uppermost surface of the sheets stacked on the stack tray 4 is maintained at a predetermined position.
U, and the position of the stack tray 4 is controlled by the CPU by the stack tray driving means based on the detection signal, so that as the amount of sheets stacked on the stack tray 4 increases, the stack tray 4 The position has been lowered.

In the sheet post-processing apparatus 1, as shown in FIG. 2, a drive shaft 9 driven by drive means (not shown) is provided above the wall 15 and above the base end of the stack tray 4. I have. Driven pulleys 7c and 8c are rotatably mounted on the drive shaft 9, and sheet pressing paddles 10 and 11 are mounted on both ends thereof so as to rotate integrally with the drive shaft 9.

Here, the sheet holding paddles 10, 11
Is for pressing the sheet bundle stacked on the stack tray 4 from above, and as shown in FIG.
It is formed of a plate-like elastic member (for example, rubber) 21 and fixedly supported by a flange portion 20 that rotates integrally with the drive shaft 9.

The sheet holding paddles 10 and 11 rotate integrally with the drive shaft 9 when the drive shaft 9 is driven to rotate clockwise in FIGS. 1 and 2 by the drive means. Further, the position of the sheet holding paddles 10, 11 is detected by a home position sensor (not shown) disposed in the vicinity thereof, and the driving means is controlled based on a detection signal of the home position sensor, so that a predetermined position is obtained. You can stop at.

In each embodiment, two sheet holding paddles are provided. However, the number of sheet holding paddles is not limited to this.
Or a configuration in which three or more components are additionally provided at the center of the drive shaft 9.

Next, the operation of the sheet post-processing apparatus 1 in the copying machine 100 will be described. When an image forming process is performed and a sheet is output from the printer unit 101, the sheet passes through the conveyance guide 71 and passes through the sheet detection sensor 75.
And is conveyed by the discharge roller 72 and discharged onto the alignment tray 3. The return roller 74 makes one rotation (or several rotations) after a predetermined time from the time when the sheet trailing edge of the sheet detection sensor 75 has passed the sheet trailing edge, thereby returning the sheet on the alignment tray to the paper trailing edge reference side (left side in FIG. 1). Performs alignment in the sheet transport direction. Thereafter, the JOG plates 5 and 6 are operated, and alignment in the sheet width direction is performed.

In the sheet post-processing apparatus 1, when a predetermined number of sheet bundles are formed after the sequentially fed sheets are aligned one by one by the above operation, if an instruction to perform staple processing is given, Stapling is performed by the stapler unit 73, and thereafter, the sheet bundle conveying belt 7 is driven,
The stapled sheet bundle is discharged onto the stack tray 4. At this time, the claw portions 7a of the sheet bundle conveying belts 7, 8
8a pushes out the end of the sheet bundle, and the claw portions 7a,
When the roller 8a comes to the position of the driven rollers 7c, 8c, the end of the sheet bundle falls onto the stack tray 4, and is discharged and stacked.

When the stapling process is not instructed, the sheet bundle conveying belt 7 is driven without performing the stapling by the stapler unit 73, and
A predetermined number of sheet bundles are discharged and stacked on the stack tray 4 as they are.

Next, the operation of the sheet post-processing apparatus 1 when discharging a sheet bundle will be described in detail with reference to FIGS. 4 (A) to 4 (C) and FIG.
FIGS. 3A and 3B show the operation of the sheet post-processing apparatus 1 according to the first embodiment at the time of discharging a sheet bundle in chronological order.

FIG. 4A shows that the sheet bundle 17 after the alignment process and the stapling process is conveyed in the direction of the arrow by the rotation of the belts 7 and 8, and is discharged onto the already loaded sheet bundle 18 on the stack tray 4. It shows the state where it was turned on. At this time, the new sheet bundle 17 is discharged to the upper part of the sheet holding paddles 10 and 11 pressing the already-stacked sheet bundle 18. Here, the sheet holding paddles 10 and 11 are shown in FIG.
As shown in (A), since the loaded sheet bundle 18 is pressed from above, it is in an elastically deformed state.

Then, the sheet bundle 17 is moved to the stack tray 4
When the sheet is ejected upward, after a lapse of a predetermined time, as shown in FIG. 4B, the sheet holding paddles 10 and 11 start rotating clockwise and make one rotation. At the end of this rotation,
The sheet holding paddles 10 and 11 are elastically deformed after their leading ends contact the uppermost sheet of the sheet bundle 17, and the sheet bundle 18 discharged onto the stack tray 4 as shown in FIG. And the sheet bundle 17 discharged thereon is pressed from above.

Further, after a lapse of a predetermined time from the end of rotation of the sheet holding paddles 10, 11, the stack tray 4 starts lowering as shown in FIG.

At this time, in the sheet post-processing apparatus 1, since the position of the uppermost sheet of the sheet bundle placed on the stack tray 4 is lowered, the sheet contact member 12 of the sheet height detection sensor is moved The sensor unit 1 is rotated in the
3 is released, and the detection signal from the sensor unit 13 becomes CP.
Output to U. Then, based on the detection signal, the CPU determines that the upper surface of the sheet bundle 17 has reached a predetermined position, and controls the stack tray driving means so as to stop the operation of the stack tray 4. Is completed. This stop position is determined by the claw portions 7a, 8a.
Is a position that does not interfere with the sheets on the stack tray 4 at least.

When the lowering operation of the stack tray 4 is completed, the belts 7 and 8 are driven in preparation for the next bundle processing (sheet alignment), and start rotating clockwise in FIG. The claw portion 7a of the belt 7 passes above the stacked sheet bundle 17 and stops at a predetermined position.

In the sheet post-processing apparatus 1, when the lowering operation of the stack tray 4 is completed, next, the raising operation of the stack tray 4 is started in order to return the upper surface of the stacked sheets to a predetermined position. This raising operation is performed based on a detection signal from the above-described sheet height detection sensor. Specifically, as the stack tray 4 is raised, the sheet contact member 12 of the sheet height detection sensor moves in the opposite direction of FIG. The stack tray 4 is controlled so as to stop rising when the sensor unit 13 rotates clockwise and the light blocking state of the sensor unit 13 is restored.

By this detecting operation, the stack tray 4
, Always stops at a constant height irrespective of the stacking amount. The reason that the top surface of the stack tray 4 and the sheets stacked on the tray 4 are always raised to a certain height position is that the stack tray 4 or the sheet surface stacked on the tray 4 is aligned with the alignment tray. 3 is also used.

In order to make the sheet post-processing apparatus as small as possible, it is necessary to reduce the size of the alignment tray 3. However, when the size of the alignment tray 3 is reduced, the leading end of the sheet discharged onto the alignment tray 3 projects from the alignment tray 3 and hangs down.
The stackability of the upper sheet is deteriorated. Therefore, by arranging the stack tray 4 or the sheet surface stacked on the tray 4 at a position where the level difference from the alignment tray 3 is reduced, the leading end of the sheet protruding from the alignment tray 3 is held and the alignment tray 3 is held. 3 can be prevented from being deteriorated. Therefore, each time a sheet is discharged onto the tray 4, the stack tray 4 descends to a position where the claw 7a of the belt 7 can pass, and then rises again to a predetermined position.

FIG. 5B shows a state in which the stack tray 4 is raised and stopped at a predetermined position. The sheet holding paddles 10 and 11 have a function of compressing an end portion of the sheet bundle stacked on the stack tray 4, and the upper sheet of the already stacked sheet bundle is particularly an unbound bundle (not staple-bound). In the case of (bundle), it also has a function of preventing the sheet bundle to be discharged next to be taken out in the discharge direction and causing a misalignment in the transport direction.

Further, the state of the sheet bundle stacked on the stack tray 4 in operation will be described with reference to FIGS. 6 to 8, illustration of the above-described seat height detection sensor is omitted for convenience of description. For comparison, FIG. 8 shows a state of the stack tray 4 in the conventional sheet post-processing apparatus.

FIG. 6A shows a state in which the stack tray 4 is moving down, and FIG. 6A shows a state of the leading end portion (closer to the wall 15) of the stacked sheet bundle 19 in this state.
(B) shows an enlarged view. As described above, in the sheet post-processing apparatus 1, before and during the lowering operation of the stack tray 4, the sheet press paddle 10 is elastically deformed to press the sheet bundle by the urging force, so that the air layer between the sheets is formed. As a result, the thickness l2 becomes smaller than the thickness l1 of the sheet bundle in the conventional sheet post-processing apparatus shown in FIG.

By making the thickness 12 smaller than the thickness 11 of the sheet bundle in the conventional sheet post-processing apparatus, the lowering amount L2 of the stack tray 4 is also reduced by the lowering amount L1 of the stack tray in the conventional sheet post-processing apparatus. Can be less than.

In the conventional sheet post-processing apparatus, since there is no member for pressing the stacked sheet bundle before and during the lowering operation of the stack tray, the stacked sheet bundle contains an air layer. When the sheet bundle is curled or curled, the sheet height detection unit that detects the height of the sheet bundle by contacting the uppermost sheet surface of the sheet bundle loads more sheet bundles than the actual stacking height of the sheet bundle. Therefore, the thickness of the sheet bundle cannot be accurately detected. If it is detected that the sheet bundle is stacked higher than the actual sheet bundle height,
The amount of downward movement of the stack tray becomes larger than the actual amount of downward movement.

On the other hand, in the sheet post-processing apparatus according to the present invention, the uppermost sheet bundle is pressed by the sheet holding paddle 10 before and during the lowering operation of the stack tray 4. It is possible to prevent inaccuracy in detecting the height of the sheet bundle due to the existing air layer or curl. Therefore, accurate detection can be performed by the sheet height detecting means for detecting the height of the sheet bundle stacked on the stack tray 4. As a result, the amount of downward movement of the stack tray 4 is also an appropriate amount of movement, and the operation time of the stack tray 4 can be reduced as compared with the conventional sheet post-processing apparatus. Can be provided.

When the stack tray 4 is lowered, if the sheet holding paddle 10 does not lose its pressing force on the sheet bundle, that is, if the sheet holding paddle 10 keeps its elastic deformation, the lowering amount is set as follows. No shift between bundles occurs. Therefore, the loadability can be improved.

FIGS. 7A to 7C show the stack tray 4.
Shows a state in the middle of rising again after completion of the lowering operation in chronological order. In the sheet post-processing apparatus 1, FIGS.
As shown in FIG. 3C, the sheet bundle whose leading end is curled on the stack tray 4 by the raising operation of the stack tray 4 is forced downward by the dashed arrow from the sheet holding paddle 10 and the wall 15 (sheet). The bundle receives resistance, and the curls gradually collapse. As described above, in the sheet post-processing apparatus 1, the curl of each sheet is broken by the raising operation of the stack tray 4, and the amount of lifting and lowering of the stack tray 4 during the post-processing of the sheet bundle can be reduced.

As described above, in the sheet post-processing apparatus 1, the air layer of the sheet bundle stacked on the stack tray 4 and the curl of the curled sheet bundle are crushed before the lowering operation of the stack tray 4 is started. The loading height can be reduced. In addition, the curl of the curled sheet bundle is crushed to prevent the sheet from leaning on the wall portion 15, and the amount of movement of the stack tray 4 when ascending or descending can be reduced. Furthermore, since the sheet bundle is constantly pressed by the sheet holding paddle 10 during the lowering and raising operations of the stack tray 4, the stacking performance of the sheets on the stack tray 4 is improved, and The movement amount can be reduced.

Therefore, in the copying machine 100 provided with the sheet post-processing apparatus 1, the position of the scanner unit 101 and the height of the entire apparatus do not become unnecessarily high, and the operability of the user such as a document set is good. There is no need to reduce the number of sheets stacked on the stack tray 4, and the specifications are maintained. Further, since the amount of movement of the stack tray 4 is reduced, the post-processing time can be reduced.

In the first embodiment, the sheet holding paddles 10 and 11 are configured to use the plate-like elastic members 21 so that the entire elastic members 21 are elastically deformed. A configuration in which an elastic member is provided only in a portion to be made to work may be adopted.

[Second Embodiment] Next, a second embodiment of the sheet post-processing apparatus will be described with reference to FIGS. In the sheet post-processing apparatus according to the second embodiment, only the sheet holding paddle is different from that of the first embodiment. Therefore, the description of other parts will be omitted as appropriate.

In the second embodiment, as shown in FIG. 9A, a sheet holding paddle 50 which is bent at a predetermined position is used. Specifically, this sheet holding paddle 50
Like the sheet holding paddles 10 and 11 of the first embodiment shown in FIG. 3, is formed of a plate-like elastic member 51 (for example, rubber), and its base end is fixedly supported by the flange portion 52. . However, the elastic member 51 is formed with a concave groove portion 51c which is concave in the thickness direction of the member, and when a constant force is applied to the distal end portion 51b, the concave groove portion 51c is formed.
Elastically deforms so as to bend at the point. Other configurations and operations are the same as in the first embodiment.

The state of discharging the sheet bundle in the sheet post-processing apparatus of the second embodiment using the sheet holding paddle 50 will be described below with reference to FIGS. FIGS. 10 and 11 show the operation of discharging the sheet bundle in the sheet post-processing apparatus of the second embodiment in chronological order. FIG. 12 shows the operation of the first embodiment for comparison. 2 shows a state of the sheet holding paddle 21 during operation of the sheet post-processing apparatus according to the embodiment.

That is, in the first embodiment shown in FIG. 12, when a curl is formed at the leading end (the wall 15 side) of the sheet bundle, the leading end of the sheet bundle floats upward. On the other hand, in the second embodiment in which the sheet holding paddle 50 is used, as shown in FIG. 11B, the sheet holding paddle 50 is bent at the bent portion 51c, and the sheet bundle is entirely formed at the front end 51b. Hold the leading ends of 55 and 56. As a result, the air layer can be reliably crushed and curling can be suppressed, so that the amount of vertical movement of the stack tray 4 can be further reduced for a curled (particularly upper curled) sheet bundle.

Further, according to this configuration, when the sheet holding paddle 50 makes one rotation, it is possible to prevent the already loaded sheet from being entangled even when the upper curl is particularly large.

Further, as in the first embodiment shown in FIG. 12, the sheet bundle 26 newly discharged onto the already stacked sheet bundle 25 rides on the inclined surface of the sheet holding paddle 21 and is discharged in the discharge direction ( It can also be prevented from shifting to the right side of the figure).

FIGS. 9B and 9C show another example of the structure of the sheet holding paddle which is bent at a predetermined position. FIG.
In the sheet holding paddle 60 shown in (B), the base end 61 a and the front end 61 b of the elastic member 61 are connected to the rotating hinge 62.
By being connected by the bending portion 61b, it is configured to bend at the bending portion 61c. In addition, in the sheet holding paddle 60,
In a normal state, the base portion 61a and the tip portion 61b are linear, and when a constant force is applied to the tip portion 61b, the spring member is attached to the rotating hinge 62 so as to bend and elastically deform at the bent portion 61c. Is attached.

The sheet holding paddle 65 shown in FIG. 9C has a plate-like elastic member 6 fixedly supported on a flange 67 similarly to the sheet holding paddle 50 of FIG. 9A.
6 (for example, rubber). Here, the elastic member 66 is provided with concave portions 66a, 66 concaved in the width direction of the member.
b is formed, and the width of the member is locally reduced. Thus, in the sheet holding paddle 65, when a constant force is applied to the distal end of the elastic member 66, these concave portions 6
Due to 6a and 66b, the member is bent and elastically deformed at the narrowest point.

In the sheet post-processing apparatus according to the second embodiment, the same effect can be obtained by using the above-described sheet holding paddle 60 or 65 in place of the sheet holding paddle 50.

In the above-described embodiment, the case where the present invention is applied to an electrophotographic image forming apparatus has been described. However, the present invention is not limited to this. For example, the present invention can be applied to an ink jet type image forming apparatus. Of course.
Further, although an example of a copying machine has been described as an image forming apparatus, it goes without saying that the present invention can be applied to a printer or a facsimile machine.

Further, in the above-described embodiment, the sheet post-processing apparatus for performing the staple processing of the sheet bundle by the staple binding as the sheet post-processing has been described. However, the present invention is not limited to this. The present invention is also applicable to a sheet post-processing apparatus that performs post-processing such as folding.

In the first and second embodiments described above, the sheet post-processing apparatus according to the present invention will be described using a configuration in which the sheet post-processing apparatus is disposed between an image reading section (scanner section) and an image forming section. However, the present invention is not limited to this, and a similar effect can be obtained even with a conventional type sheet post-processing apparatus attached to the side of the housing of the image forming apparatus.

[0088]

As described above in detail, according to the present invention, the sheet post-processing which improves the stackability of the sheets stacked on the stack tray and reduces the moving amount when the stack tray is moved up and down is realized. It is possible to provide an apparatus and an image forming apparatus including the sheet post-processing apparatus.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an overall configuration of an image forming apparatus including a sheet post-processing apparatus.

FIG. 2 is a perspective view for explaining an embodiment of the sheet post-processing apparatus of the present invention, and is a configuration diagram in which a stack tray is partially cut away.

FIG. 3 is an external perspective view of a sheet holding paddle.

FIGS. 4A and 4B are diagrams illustrating an operation of the first embodiment of the sheet post-processing apparatus. FIG. 4A illustrates a state in which a new sheet bundle is stacked on a stack tray, and FIG. FIG. 4C shows a state in which the paddle has started to rotate, and FIG. 4C shows a state in which the sheet pressing paddle is pressing the top of a new sheet bundle.

5A and 5B are diagrams illustrating an operation of the first embodiment of the sheet post-processing apparatus. FIG. 5A illustrates a state in which the stack tray starts lowering and the sheet bundle conveying belt starts rotating. B) shows a state in which the stack tray is raised to press the sheet bundle.

6A and 6B are diagrams illustrating the operation of the sheet post-processing apparatus and the state of the sheet bundle. FIG. 6A illustrates a state when the stack tray is lowered, and FIG. B) shows an enlarged view.

FIGS. 7A and 7B are diagrams illustrating the operation of the sheet post-processing apparatus and the state of the sheet bundle. FIG. 7A is an overall view illustrating a state where the stack tray is raised, and FIGS. This shows how the curl of a curled sheet bundle is crushed.

FIG. 8 is a diagram illustrating a state in which a stack tray is moved in a conventional sheet post-processing apparatus in order to explain the sheet post-processing apparatus of the embodiment in comparison with a conventional example.

FIG. 9 is an external perspective view showing another embodiment of the sheet holding paddle, in which a sheet holding paddle having a concave portion formed in the thickness direction in FIG. (B) shows a sheet press paddle provided with a hinge portion, and (C) shows a sheet press paddle having a recess formed in the width direction.

FIGS. 10A and 10B are diagrams illustrating the operation of the second embodiment of the sheet post-processing apparatus. FIG. 10A illustrates a state in which a new sheet bundle is stacked on a stack tray, and FIG. Shows a state in which the top of the new sheet bundle is pressed by one rotation.

FIGS. 11A and 11B are diagrams illustrating an operation of the sheet post-processing apparatus according to the second embodiment. FIGS. 11A and 11B are overall views when a stack tray is lowered and raised to press a sheet bundle. 2 shows an enlarged view of a sheet holding paddle.

FIG. 12 is a diagram for explaining an operation of the sheet post-processing apparatus according to the second embodiment in comparison with the first embodiment, and illustrates a sheet press that presses a sheet bundle according to the first embodiment; Indicates the state of the paddle.

13A and 13B are side cross-sectional views illustrating the outline and operation of a conventional sheet post-processing apparatus. FIG. 13A illustrates a state in which a new sheet bundle is stacked on a stack tray, and FIG. At the same time, the sheet holding member is retracted, and the state in which the sheet bundle conveying belt starts rotating is
(C) shows a state where the stack tray is raised and the sheet pressing member presses the sheet bundle.

[Explanation of symbols]

REFERENCE SIGNS LIST 100 copier (image forming apparatus) 100a housing 101 printer unit 102 scanner unit (image reading unit) 105 sheet feeding unit 105A, 105B, 105C, 105D cassette feeding unit 105E manual feed unit 106 image forming unit 108 sheet discharge Unit 110 Sheet Loading Cassette 111 Pickup Roller 112 Separation Roller Pair 113 Transport Roller Pair 114 Transport Roller Pair 115 Sheet Loading Tray 116 Transport Roller 121 Laser Scanner 122 Registration Roller 123 Photosensitive Drum 124 Transfer Charger 125 Developer 126 Scanner 131 Scan System light source unit 132 Platen glass 133 Original pressure plate 134 Reflecting mirror 135 Lens 136 Light receiving element 1 Sheet binding unit (sheet post-processing device) 3 Alignment tray 4 Stack tray 5, 6 Alignment means 7, 8 Sheet bundle conveying belt (sheet conveying means) 7a, 8a Claw portion 7b, 8b Drive pulley 7c, 8c Followed pulley 12 Sheet contact member (sheet height detecting means) 13 Sensor section (sheet height detecting means) 15 Wall section 17 , 18, 19, 26 Sheet bundle 10, 11, 50, 60, 65 Sheet pressing paddle (sheet pressing means) 20, 52, 63 Flange 21, 51, 61, 66 Elastic member 51c Depressed groove 62 Rotating hinge 71a, 71b Depressed portions l1, l2 Sheet thickness L1, L2 Stack tray lowering amount 71 Conveyance guide unit 72 Conveyance roller 73 Stapler unit 74 Return roller 75 Sheet detection sensor 77 Sheet presence sensor 77

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshinori Isobe 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H071 BA27 DA01 DA02 DA05 DA21 DA24 EA04 3F054 AB01 AC02 AC03 AC05 BA04 BD02 BG02 DA01 5C062 AA05 AB17 AB22 AB29 AB32 AB35 AC65 AD01 AD06 BA00

Claims (19)

[Claims] 1. A sheet post-processing means for performing predetermined post-processing on a sheet; and a sheet having passed through the sheet post-processing means is discharged.
A stack tray movable in the vertical direction; and a sheet presser for pressing the uppermost sheet surface discharged on the stack tray, wherein the uppermost sheet discharged on the stack tray is provided by the sheet presser. A sheet post-processing apparatus wherein the stack tray moves downward while a surface is pressed. 2. The sheet presser according to claim 1, wherein the sheet presser includes a sheet presser configured to contact and press an uppermost sheet surface stacked on the stack tray, a holding member rotatably holding the sheet presser, and the holding member. A pressing member driving unit that drives a member, and when a sheet is discharged onto the stack tray, the pressing member driving unit drives the holding member,
2. The sheet post-processing apparatus according to claim 1, wherein rotating the sheet pressing member makes contact with and presses the uppermost surface of the sheet discharged onto the stack tray. 3. 3. A sheet height detecting means for detecting a height position of sheets discharged and stacked on the stack tray, wherein the downward movement of the stack tray is performed by detecting the sheet detecting means. The sheet post-processing apparatus according to claim 1, wherein the sheet post-processing is stopped based on the condition. 4. The sheet post-processing apparatus according to claim 2, wherein the sheet pressing member has an elastic portion that elastically deforms and presses a sheet surface on the stack tray. 5. The sheet post-processing apparatus according to claim 2, wherein the sheet pressing member has a bent portion that bends and presses a sheet surface on the stack tray. 6. The sheet post-processing apparatus according to claim 5, wherein the bent portion of the sheet pressing member has a concave shape in a thickness direction and / or a width direction of the sheet pressing member. 7. The sheet post-processing means includes: a sheet stacking table on which a sheet on which an image is formed by the image forming apparatus is discharged and stacked; and a discharge direction and a width direction of the sheet discharged and stacked on the sheet stacking table. 2. The sheet post-processing apparatus according to claim 1, further comprising: a sheet aligning unit that aligns the sheets, and a sheet binding unit that staples and binds the sheets aligned by the sheet aligning unit. 3. 8. A sheet conveying means for conveying sheets stacked and discharged to a sheet stacking table of said sheet post-processing means to said stack tray.
8. The sheet post-processing apparatus according to any one of claims 1 to 7. 9. The image forming apparatus according to claim 1, wherein the sheet conveying unit includes a rotator provided on the sheet stacking table and configured to rotate in a direction of the stack tray to convey sheets stacked on the sheet stacking table to the stack tray. The sheet post-processing apparatus according to claim 8, wherein 10. The sheet conveying means includes: a belt member having a protruding portion that abuts a sheet stacked on the sheet stacking table; a pulley member that rotatably stretches the belt member; and a pulley member. The sheet post-processing device according to claim 8, further comprising a pulley driving unit that rotates the sheet. 11. The sheet conveying means includes: a belt member having a protruding portion that comes into contact with a sheet stacked on the sheet stacking table; a pulley member that rotatably stretches the belt member; A pulley driving unit that rotates the pulley member, wherein the holding member of the sheet pressing unit is the pulley member that drives the pulley member by pivoting, and the pressing member driving unit of the sheet pressing unit includes the pulley. The sheet post-processing device according to claim 8, wherein the sheet post-processing device is a driving unit. 12. The lower position where the stack tray moves is a position where the projecting portion provided on the belt member of the sheet conveying means does not interfere with the sheets stacked on the stack tray. A sheet post-processing apparatus according to claim 11. 13. The stack tray moves downward in a state where the sheet pressing member presses the uppermost sheet surface stacked on the stack tray, and based on the detection of the sheet height detection means. The sheet post-processing apparatus according to any one of claims 3 to 12, wherein after the movement is stopped, the sheet pressing member moves upward while maintaining a pressed state of the sheet pressing member. 14. The upward movement of the stack tray is stopped by the sheet height detection means detecting that the uppermost position of the sheets stacked on the stack tray has reached a predetermined position. The sheet post-processing apparatus according to claim 13, wherein: 15. A sheet post-processing apparatus according to claim 1, further comprising: an image forming unit configured to form an image on the sheet and to supply the image-formed sheet to the sheet post-processing apparatus. An image forming apparatus comprising: 16. The image forming apparatus according to claim 15, wherein the sheet post-processing apparatus is disposed outside a frame constituting the image forming apparatus. 17. An image reading apparatus, comprising: an image reading unit that reads image information, wherein the sheet post-processing device is disposed in a space provided between the image reading unit and the image forming unit. The image forming apparatus according to claim 15. 18. The image forming apparatus according to claim 17, wherein the image reading unit, the sheet post-processing device, and the image forming unit are arranged in this order from above the device. 19. The image reading device according to claim 1, further comprising a light receiving unit that forms an image of reflected light from the document on a photoelectric conversion element, and forms an image based on an image information signal from the light receiving unit. An image forming apparatus according to claim 17.