JP2002187638A - Paper feeding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely feed paper sheet P one by one without overlap feed, even if the sheets of paper P have different friction coefficients such as recycle paper. SOLUTION: A pressing roller 5 is disposed on the downstream side of a feeding direction of a feeder roller 4, and a flexible roller 6 is disposed on the downstream side of the pressing roller 5. When starting the feeding, the pressing roller 5 and the flexible roller 6 are brought into contact with the paper sheet P with the pressing roller stopping, and the flexible roller 6 rotates in the feeding direction to bend the paper sheet P to be fed and feeds the paper P sheet one by one. Therefore, even if the sheets of paper have different coefficients, the overlap feed of the paper sheet P is surely prevented.

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 which prevents double feeding of sheets having different friction coefficients.

[0002]

2. Description of the Related Art Today, printers, copiers, facsimile machines, and the like often have a configuration in which a plurality of standard paper sheets are stocked and fed one by one in accordance with an image forming operation to form an image.

[0003] Such paper stock and paper feeding are performed by a paper feeding device, and various papers such as a friction pad separation system and a corner claw separation system are provided so that the paper is fed one by one when the paper feeding operation is started. A paper separation mechanism has been proposed.

For example, in Japanese Patent Application Laid-Open No. Hei 7-315608, a pickup roller that comes into contact with the uppermost sheet and feeds the sheet in the sending direction, a sheet feeding / separating unit including a feed roller and a separation roller, and a cassette An inclined portion provided at the upper end of the cassette front fence positioned at the leading end in the sheet feeding direction, a presser filler positioned above the inclined portion and pressing the sheet between the inclined portion, and a case where the sheet is double-fed. There is disclosed a configuration in which retraction means for retreating a pressing filler from a paper feed path together with a pickup roller for separating the paper are provided.

[0005]

However, the above-described paper separating mechanism has a problem that double feed cannot be completely prevented when papers having different friction coefficients are mixed.

That is, from the viewpoint of resource reuse in recent years, back paper or recycled paper is often used as paper.

[0007] The backing paper or the like is not always the same quality paper backing paper, but is often a backing paper of various papers. In the case of recycled paper, the coefficient of friction of the surface of the paper depends on the ratio of used paper and the like. It is mixed.

Therefore, it has been difficult to sufficiently prevent double feeding of such a sheet by using a conventional sheet separating mechanism.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet feeding device capable of reliably preventing double feeding of sheets even when the friction coefficient differs for each sheet.

[0010]

According to a first aspect of the present invention, there is provided a sheet feeding apparatus for stocking a plurality of sheets and feeding the sheets by a sheet feeding roller. A pressing roller is provided on the downstream side in the paper feeding direction, and a flexible roller is provided on the downstream side of the pressing roller. By rotating the paper to be fed by bending it to separate the paper, the double feeding of the paper can be reliably prevented even when the friction coefficient is different for each paper, for example. I do.

According to a second aspect of the present invention, by rotating the flexible roller for a predetermined time, the amount of deflection of the paper to be fed is controlled by the rotation time of the flexible roller, so that the friction coefficient differs for each sheet, for example. In such a case, it is possible to reliably prevent double feeding of paper even in a case where it is difficult.

According to a third aspect of the present invention, there is provided a height sensor for detecting a bending height of a sheet bent by a bending roller, and the bending roller is rotated until the height sensor detects the sheet. In addition, the amount of sheet deflection is controlled so that double feeding of sheets can be reliably prevented even when the coefficient of friction differs for each sheet.

According to a fourth aspect of the present invention, a blower for sending air is provided between a sheet bent by a bending roller and a sheet below the sheet to reduce the distance between sheets. For example, the coefficient of friction differs for each sheet. In such a case, double feed of sheets can be reliably prevented.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically showing a main part of a sheet feeding device according to the present invention.

The paper feeder has a cassette 1 for stocking a plurality of sheets, and a bottom plate 3 on which the paper P is placed is provided in the cassette 1. The bottom plate 3 is urged upward by the pressure spring 2.

A paper feed roller 4 is provided above the bottom plate 3 so as to sandwich the paper P, and the paper P is fed and conveyed by the paper feed roller 4.

However, in the case of backing paper or recycled paper, which has been frequently used in recent years as the paper P, it is difficult to eliminate double feeding of the paper P using only the paper feed roller 4 because the friction between the papers varies. Has become.

Such double feeding is likely to occur when there is a difference in the coefficient of friction between the upper sheet P and the lower sheet P, and the coefficient of friction of the lower sheet P is small.

Therefore, in the present invention, the pressing roller 5 provided on the paper feeding direction side and the flexible roller 6 provided behind the pressing roller 5 are provided so that the friction coefficient differs or the paper can be surely separated. .

That is, the pressing roller 5 and the bending roller 6
Before the paper feed roller 4 starts feeding the paper P, the paper P
To come into contact with.

When the paper is fed, the flexible roller 6 rotates appropriately in the paper feeding direction while the pressing roller 5 is in contact with the paper P and is stopped.

As a result, the sheet P to be fed is bent as shown in FIG. 2 to form a bridge.

Of course, if the flexible roller 6 is rotated or the pressing roller 5 is stopped in any state, normal feeding cannot be performed, so that it is necessary to control these.

As such a control method, it is possible to provide a timer (not shown) to rotate the bending roller 6 for a predetermined time, thereby bending the sheet P by a certain amount.

Further, a height sensor 7 may be provided as shown in FIG. 3, and the flexible roller 6 may be rotated until the height sensor 7 detects the sheet P. This is because the rotation of the flexible roller 6 causes the paper P to bend, so that the height position changes according to the amount of bending.

After the sheet P is bent as described above, the sheet feeding roller 4 rotates to feed the sheet. The rotation of the paper feed roller 4 is preferably started after the elapse of the time when the timer is provided to rotate the flexible roller 6 for a predetermined time, and the height sensor 7 is provided to determine that the paper has bent by a predetermined amount. When the detection is performed, it is preferable after the height sensor 7 detects the sheet.

When the paper feed roller 4 rotates, the pressing roller 5 and the flexible roller 6 rotate in synchronization with the paper feeding speed, and stop when the paper P being fed passes.

By bending the sheet P in this manner,
Since friction does not act on the bent portion, the frictional resistance when the paper feed roller 4 is rotated to feed the paper is reduced, such as recycled paper or back paper having a different friction coefficient between papers. However, double feed can be prevented.

After the paper P is bent by the flexible roller 6, the flexible roller 6 and the pressing roller 5 may be separated from the paper P after a predetermined time has elapsed.

In this case, the bending of the paper P is eliminated, but since air once enters between the paper P to be fed and the lower paper P, the upper and lower papers P are not immediately bent. Are not closely adhered to each other, so that the frictional force is also reduced, so that double feed can be suppressed.

After the paper P is bent by providing the blower 8 as shown in FIG.
May be separated from the sheet P.

When the sheet P is bent, the air from the blower 8 enters between the bent sheet P and the sheet P below the sheet P, and forms an air layer therebetween. It is possible to realize more reliable paper feeding performance.

[0033]

As described above, according to the first aspect of the present invention, a paper feed roller is provided downstream of the paper feed roller in the paper feeding direction and a flexible roller is provided downstream of the paper feed roller to start paper feeding. Sometimes, the pressing roller comes into contact with the paper in a stopped state, and the flexible roller comes into contact with the paper, and rotates in the paper feeding direction to deflect the paper to be fed, thereby separating the paper. Thus, even when the friction coefficients are different from each other, it is possible to reliably prevent the double feed of the sheets.

According to the second aspect of the present invention, the amount of bending of the paper to be fed is controlled by the rotation time of the flexible roller by rotating the flexible roller for a predetermined time. Even in a different case, double feeding of sheets can be reliably prevented.

According to the third aspect of the present invention, a height sensor for detecting the bending height of the sheet bent by the bending roller is provided, and the bending roller is rotated until the height sensor detects the sheet. Thus, since the amount of bending of the sheet is controlled, it is possible to reliably prevent the double feeding of sheets even when the coefficient of friction differs for each sheet.

According to the fourth aspect of the present invention, since a blower for sending air is provided between the sheet bent by the bending roller and the sheet below the sheet, the space between the sheets is reduced. Even when the coefficients are different, it is possible to reliably prevent the double feed of the sheets.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of a sheet feeding device applied to the description of an embodiment of the present invention.

FIG. 2 is a diagram illustrating a state in which a sheet is bent.

FIG. 3 is a diagram illustrating a state in which the amount of sheet deflection is controlled by a height sensor.

FIG. 4 is a diagram showing a configuration for reducing a frictional force between sheets by a blower.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cassette 2 Pressure spring 3 Bottom plate 4 Paper feed roller 5 Push roller 6 Flexible roller 7 Height sensor 8 Blower

Claims (4)

[Claims] 1. A paper feeder for stocking a plurality of papers and feeding the papers by a paper feed roller, comprising: a pressing roller downstream of the paper feeding direction in the paper feeding direction; and a bending roller downstream of the pressing roller. A roller is provided to abut the paper with the pressing roller stopped at the start of paper feeding and the flexible roller abuts to rotate in the paper feeding direction to deflect the paper to be fed to perform paper separation. A sheet feeding device characterized by the above-mentioned. 2. The paper feeding apparatus according to claim 1, wherein the bending amount of the paper to be fed is adjusted by rotating the bending roller for a predetermined time. 3. A method according to claim 1, further comprising the step of: providing a height sensor for detecting a bending height of the sheet bent by the bending roller, and rotating the bending roller until the height sensor detects the sheet. The sheet feeding device according to claim 1, wherein 4. The sheet feeding device according to claim 1, further comprising a blower for sending air between the sheet bent by the bending roller and a sheet below the sheet.