JP2000053269A - Sheet feeding device and sheet processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate variance in separating capability depending upon sheet loading. SOLUTION: The front end of a sheet S loaded in a cassette 301 is brought into contact with a sheet front end contact surface 301-2 of the cassette 301. The sheets S in the cassette 301 are delivered sequentially from the top sheet by a feeding roller 302 which rotates counterclockwise. The feeding roller 302 is rotatably-mounted at the front end of an arm member 304 which vertically- rotates about a spindle 303 and comes into contact with the top sheet at all time. The sheet front end contact surface 301-2 is formed into an arc shape so as to meet the track of the feeding roller 302 while the arm member 304 is being dropped by its dead weight. The buckling strengths of the sheet S at the time of full loading, medium loading, and little loading are set so as to be almost constant, thus it is possible to eliminate variance in separating capability depending upon sheet loading.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus provided in a sheet processing apparatus for performing a predetermined process on sheets fed one by one.

[0002] A typical example of the sheet processing apparatus referred to here is, for example, an image forming apparatus (printer, copier, facsimile machine) for forming an image on a sheet (recording material) fed one by one. And the like, and a document image reading device that reads an image of a sheet (document) fed one by one.

[0003]

2. Description of the Related Art FIG. 5 shows a configuration of a conventional sheet feeding apparatus provided in an image forming apparatus.

The sheet feeding apparatus 200 includes a cassette 201 for stacking and storing sheets S, and a feeding roller 202 for sequentially feeding out the sheets S stacked and stored in the cassette 201 from the top sheet. Have been.

The cassette 201 has a sheet stacking portion 201-1 for stacking the sheets S, a sheet leading end contact surface 201-2 for contacting the leading end of the sheet S, and a sheet trailing end for regulating the rear end position of the sheet S. And a regulating portion 201-3.

[0006] The sheet leading end contact surface 201-2 is an inclined surface and is inclined so as to fall upward in the sheet feeding direction downstream. The sheet trailing end regulating portion 201-3 is also inclined in accordance with the inclination of the sheet leading end contact surface 201-2.

[0007] The feed roller 202 has a support shaft (fixed shaft) 20.
The arm member 204 is rotatably attached to a distal end portion of the arm member 204 which is attached so as to be rotatable up and down around the center 3.

Drive from a drive source (not shown) is transmitted to the feed roller 202 via a gear train or the like incorporated in the arm member 204, and the feed roller 202 is moved in a counterclockwise direction (the direction of an arrow). It is designed to rotate.

The feed roller 202 is always in contact with the uppermost sheet at a predetermined pressure due to the lowering of the arm member 204 by its own weight. In this state, the feed roller 202 rotates.

When the feed roller 202 which is in contact with the uppermost sheet rotates, the uppermost sheet is rotated by the feed roller 20.
The sheet abutment surface 201-
Pressed on 2. By this pressing, the uppermost sheet buckles and is fed out along the sheet leading end contact surface 201-2.

In the case of the sheet feeding apparatus 200, the sheet S
Is affected by the buckling strength of the sheet S, and the smaller the buckling strength, the higher the separating performance.

[0012]

However, in the above-described conventional sheet feeding apparatus, the buckling resistance of the sheet S differs depending on the amount of the loaded sheet S, and the separation performance varies depending on the loaded amount of the sheet S. There was a problem that would occur. This will be described in detail with reference to FIGS.

First, the buckling resistance of the sheet S will be described with reference to FIG. The buckling strength of the sheet S is determined by the point P1 at which the feed roller 202 is in contact with the sheet front end abutting surface 2.
01-2, the distance L of the sheet S to the point P2, and the inclination angle θ of the sheet leading end contact surface 201-2.
Etc. are determined.

Next, the buckling resistance of the sheet S at full load, medium load, and small load will be described with reference to FIG.

The feed roller 202 descends along an arc-shaped trajectory Q shown by a dotted line. For this reason, the distance from the point P1 to the point P2 is different from L1, L2, and L3 between the full load, the medium load, and the small load, and the inclination angle θ of the sheet leading end contact surface 201-2 is constant. Therefore, a difference occurs in the buckling resistance of the sheets S at each loading.

Accordingly, the present invention has been made in view of the above circumstances, and provides a sheet feeding apparatus in which the buckling resistance of sheets does not change even if the stacking amount of sheets changes, and stable separation performance can be obtained. The purpose is to do.

[0017]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a sheet stacking means for stacking sheets in a state where the leading end of the sheet abuts against the sheet leading end abutting surface, and the sheet stacking means. A feed roller that comes in contact with the uppermost sheet and feeds the sheet in order from the uppermost sheet, and separates the sheet by feeding the sheet along the sheet leading end abutting surface with the feeding force of the feed roller. The present invention relates to a sheet feeding device.

According to the present invention, in order to achieve the above object, the distance between the point at which the feed roller of the uppermost sheet comes into contact with the sheet abutting surface and the point at which the sheet abuts against the sheet abuts on the sheet. The buckling strength of the sheet, which is determined by the inclination angle of the front end abutting surface, is substantially constant regardless of whether the sheet loading amount is large or small.

In order to achieve the above object, the present invention provides a sheet stacking means having a sheet leading end abutting surface for regulating the leading end of a sheet to be stacked, and a sheet contacting means which contacts the uppermost sheet of the sheets stacked on the sheet stacking means. Feeding means for feeding out the sheet in order from the top sheet, and the sheet is separated by feeding the sheet along the sheet leading end abutting surface by the feeding force of the feeding means.

According to the present invention, in order to achieve the above object, the inclination angle at the position where the uppermost sheet of the sheets stacked on the sheet stacking unit abuts on the sheet leading end abutting surface is set to the full sheet loading state. The shape is such that it becomes smaller as the load capacity decreases.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an overall schematic configuration of an image forming apparatus (laser beam printer) provided with a sheet feeding device of the present invention. 2 and 3 show the configuration of the sheet feeding apparatus.

First, the image forming apparatus will be briefly described.

In the main body 100 of the image forming apparatus, two sets of the sheet feeding device 300 of the present invention are provided. The sheet feeding device 300 includes a cassette 30 for stacking and storing the sheets S.
1 and the sheets S loaded and stored in the cassette 301
Roller 302 that feeds the sheets in order from the top sheet
And is provided. These will be described in detail later.

The sheet S fed out by the feeding roller 302 is conveyed by the conveying roller pairs 101 and 102 and reaches the registration roller pair 103 in a rotation stopped state.

The sheet S that has reached the pair of registration rollers 103 stops moving when a predetermined amount of loop is formed by the leading edge of the sheet abutting the nip of the pair of registration rollers 103. By forming this loop, the skew state of the sheet S is corrected.

The sheet S whose skew has been corrected is sent to a transfer portion between the photosensitive drum 104 and the transfer roller 105 by the registration roller pair 103 which starts rotating at a predetermined timing. Then, the toner image on the photosensitive drum 104 is transferred by the transfer roller 105 to the sheet S passing through the transfer unit.

A toner image is formed on the photosensitive drum 104 as follows. That is, the laser scanner 106 emits laser light based on image information sent from a host computer (not shown) and irradiates the photosensitive drum 104 rotating clockwise.
As a result, an electrostatic latent image is formed on the photosensitive drum 104, and the electrostatic latent image is developed (toner image) by the developing sleeve 107.

The sheet S to which the toner image has been transferred after passing through the transfer section is sent to the fixing device 108. The toner image in the unfixed state is fixed on the sheet surface by being heated and pressurized while passing through the fixing nip of the identification attaching device 108.

The sheet S that has been subjected to the fixing process and passed through the fixing device 108 is sent to the upper portion of the image forming apparatus main body 100, and is discharged onto a discharge tray 110 outside the apparatus by a discharge roller pair 109.

Next, the sheet feeding apparatus 300 of the present invention will be described with reference to FIGS.

The cassette 301 has a sheet stacking portion 301-1 for stacking the sheets S, a sheet front end abutting surface 301-2 for abutting the front end of the sheet S, and a sheet rear end for regulating the rear end position of the sheet S. And a restricting portion 301-3.

The sheet leading end contact surface 301-2 is an inclined surface, and is inclined so as to fall upward in the sheet feeding direction downstream. The sheet leading end contact surface 301-2 is an arc-shaped surface. Seat trailing edge regulating section 301
-3 is also inclined in accordance with the inclination of the sheet leading end contact surface 301-2.

The feed roller 302 has a support shaft (fixed shaft) 30.
The arm member 304 is rotatably attached to a distal end portion of the arm member 304 which is attached to be rotatable up and down around the center 3.

Driving from a drive source (not shown) is transmitted to the feed roller 302 via a gear train or the like incorporated in the arm member 304, and the feed roller 302 moves in a counterclockwise direction (the direction of an arrow). It is designed to rotate.

The feed roller 302 is always in contact with the uppermost sheet at a predetermined pressure due to the lowering of the arm member 304 by its own weight. In this state, the feed roller 302 rotates.

FIG. 4 shows the trajectory Q of the feed roller 302 when the arm member 304 descends by its own weight. The trajectory Q has an arc shape, and the sheet leading end abutting surface 301-2 has an arc along the arc of the trajectory Q.

When the feeding roller 302 which is in contact with the uppermost sheet rotates, the uppermost sheet is pressed against the sheet leading end contact surface 301-2 by the feeding force of the feeding roller. Due to this pressing, the uppermost sheet buckles and is fed out along the sheet leading end contact surface 301-2.

FIG. 4 shows the distance L and the inclination angle from the point P1 to the point P2 in the sheet feeding apparatus 300 according to the present invention when the sheet stacking amount is full, medium, or small. Indicates θ.

At the time of full loading, the distance is L1 and the inclination angle θ1. At the time of medium loading, the distance is L2 and the inclination angle θ2. At the time of small loading, the distance is L3 and the inclination angle θ3. Here, L4
>L5> L6, and θ1>θ2> θ3.

The larger the distance L, the smaller the buckling resistance of the sheet, and the larger the inclination angle θ, the larger the buckling resistance of the sheet. For this reason, the buckling strength of the sheet at the time of full loading, medium loading, and small loading becomes substantially constant, and the separation performance is stabilized.

[0042]

As described above, according to the present invention,
The sheet leading end abutting surface of the sheet stacking means is positioned at a distance from a point where the feed roller of the uppermost sheet comes into contact to a point where the sheet abuts against the sheet leading end abutting surface, and the inclination angle of the sheet leading end abutting surface. Since the buckling resistance is made almost constant when the sheet loading capacity is large or small,
The separation performance does not vary depending on the sheet loading amount.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an overall schematic configuration of an image forming apparatus (laser beam printer) including a sheet feeding device according to the present invention.

FIG. 2 is a perspective view illustrating a configuration of a sheet feeding apparatus according to the present invention.

FIG. 3 is a cross-sectional view illustrating a configuration of a sheet feeding apparatus according to the present invention.

FIG. 4 is a cross-sectional view illustrating the buckling strength of the sheet when the sheet loading amount is full, medium, or small in the sheet feeding device of the present invention.

FIG. 5 is a perspective view illustrating a configuration of a conventional sheet feeding apparatus.

FIG. 6 is a cross-sectional view illustrating conditions for determining a buckling resistance of a sheet in a conventional sheet feeding apparatus.

FIG. 7 is a cross-sectional view illustrating the buckling strength of a sheet when the sheet stacking amount is full, medium, or small in the conventional sheet feeding apparatus.

[Explanation of symbols]

 Reference Signs List 300 sheet feeding device 301 cassette (sheet stacking means) 301-2 sheet abutting surface 302 feed roller (feeding means) 303 support shaft 304 arm member S sheet

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 2C059 AA04 AA05 BB11 2H072 BA01 BA12 BA19 BB01 JA02 JA04 JA05 3F343 FA02 FA03 FB02 FB03 FB04 GB01 GC01 GD01 HC22 HE07 HE08 HE09 HE12 JA01 JA14 JD13 KA03 KA06

Claims (6)

[Claims] 1. A sheet stacking means for stacking sheets in a state where the sheet leading end abuts against a sheet leading end abutting surface, and comes into contact with an uppermost sheet stacked on the sheet stacking means and is fed out in order from the uppermost sheet. A sheet feeding device, comprising: a sheet feeding device that separates a sheet by feeding out a sheet along the sheet front end abutting surface with a feeding force of the feeding roller. The buckling resistance of the sheet, which is determined by the distance from the point where the feed roller of the upper sheet comes into contact with the point where the sheet abuts against the sheet, and the inclination angle of the sheet abutment surface, are not often large. A sheet feeding apparatus characterized in that the sheet feeding apparatus has a substantially constant shape in any case. 2. A sheet stacking means having a sheet front end abutting surface for regulating a front end of a sheet to be stacked, and a sheet feeding unit that comes into contact with the highest sheet of the sheets stacked on the sheet stacking unit and sequentially feeds out the top sheet. A sheet feeding device that separates a sheet by feeding out a sheet along the sheet front end abutting surface with the feeding force of the feeding unit, wherein the sheet front abutting surface includes the sheet stacking unit. A sheet feeding apparatus characterized in that the inclination angle at the position where the uppermost sheet of the sheets stacked on the means abuts decreases as the stacked amount decreases from the full sheet state. 3. The sheet feeding device according to claim 1, wherein the sheet front end abutting surface has an arc shape. 4. The sheet feeding roller is rotatable around a support shaft on the sheet front end abutting surface side, and is attached to a front end portion of an arm member that descends by its own weight to reduce the number of sheets. The sheet feeding device according to claim 1, wherein the sheet feeding device descends along with the sheet feeding. 5. The sheet feeding device according to claim 4, wherein the sheet leading end contact surface forms an arc-shaped surface along an arc-shaped trajectory when the feeding roller descends. apparatus. 6. A sheet processing apparatus for performing a predetermined process on sheets fed one by one, wherein the means for separating and feeding the sheets one by one is provided. A sheet processing apparatus provided with the sheet feeding apparatus of (1).