JP2002347965A - Paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeder providing construction suppressing unusual noises or multiple feeding in a friction pad separation system. SOLUTION: A friction pad central portion 1b having contact with a paper feed roller 4b and both end portions 1c having no contact therewith are used to form a level difference. The paper feed roller 4b narrower than the friction pad central portion 1b and the friction pad central portion 1b are used to perform nip separation of paper and an edge 5 of the level different at both friction pad end portions 1c having no contact with the paper feed roller 4b causes an edge separation effect of hitching the paper 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder for separating transfer paper by a friction pad separation system.

[0002]

2. Description of the Related Art
2. Description of the Related Art In a paper feeder of an image forming apparatus such as a copying machine, a friction pad separation system is often used as a separation system of a paper feed unit. FIG. 1 is a schematic perspective view of this kind of friction pad separating section. The receiving table 2a to which the friction pad 1a is attached is separated by a separation spring 3 into a feeding roller 4a.
a. Friction pad 1a and paper feed roller 4
The widths w1 and w2 of a are generally 50 mm, for example.

[0003] This separation system employs a friction pad 1a.
This is known as a mechanism in which squeal (abnormal noise) easily occurs. The squeal is reduced by reducing the friction coefficient of the friction pad 1a, but double feed is more likely to occur as a side effect thereof.

As a device for suppressing the squeal, the double feed, and the non-feed, a portion from the vicinity of the nip to the downstream side in the sheet conveying direction is cut off at both ends of the friction pad as disclosed in Japanese Patent Laid-Open No. 2000-198560. The structure is considered.

However, this structure is possible when the length of the nip (width of the feed roller) is about 50 mm as in the illustrated device, but it is possible to reduce the cost and reduce the size of the feed roller. Accordingly, when the width of the paper feed roller, that is, the length of the nip in the separation unit is less than half, it is difficult to suppress squeal, double feed, and non-feed. this is,
If the length of the nip, which greatly contributes to the separation performance, becomes short, double feed is likely to occur, but if the friction pad pressure (separation pressure) is raised to suppress it, squeal will easily occur, making it difficult to balance these. That's why.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet feeder having a structure capable of suppressing the occurrence of squeal (abnormal noise) and double feed in a friction pad separation system.

[0007]

According to a first aspect of the present invention, there is provided a paper feeder, comprising: a paper feed roller for feeding paper; and a friction pad for separating the fed paper. In the sheet feeder provided with a separating portion having a step, a step is provided at a center portion and both end portions of the friction pad that comes into contact with the sheet feed roller.

According to a second aspect of the present invention, in order to achieve the above object, in the paper feeder of the first aspect, a center portion and both end portions of the friction pad are formed of different materials. I do.

According to a third aspect of the present invention, in order to achieve the above object, in the paper feeder according to the first aspect, a step is provided at both ends of a center portion of a sticking place where the friction pad is stuck. It is characterized by becoming.

[0010]

Embodiments and examples of the present invention will be described below with reference to the drawings. In the following, description will be made by assigning common reference numerals to parts common to the conventional example. FIG. 2 is a schematic perspective view of a friction pad separation unit in one embodiment of the paper feeder according to the present invention, and FIG. 3 is a view of the friction pad separation unit viewed from the downstream side in the sheet conveyance direction (the direction of arrow X in FIG. 2). It is an outline sectional view. The width w4 of the paper feed roller 4b of this embodiment is 20 mm, and the friction pad central portion 1b (width w
3 = 25 mm), and a step is provided at both end portions 1c which are not in contact with each other.

The nip separation of the paper is performed between the paper feed roller 4b and the friction pad central portion 1b, which are smaller than the width of the friction pad central portion 1b, and the edge 5 of the step portion of the friction pad both end portions 1c that does not contact the paper feed roller 4b. Causing an edge separation effect in which the paper 6 is caught,
Even if the nip length is short, double feed is suppressed by compensating for the reduction of the separating action, and the occurrence of squeal is suppressed by eliminating the need to increase the separating pressure.

FIG. 4 is a schematic perspective view of a friction pad separating section of another embodiment of the sheet feeding apparatus according to the present invention. In the present embodiment, the material is different between the friction pad central portion 1b and both end portions 1d. As a result, even when the desired edge separation effect cannot be obtained with the same material, the load resistance at the edge 5 can be changed by changing the material, and the desired edge separation effect can be obtained.

FIG. 5 is a schematic perspective view of a friction pad separating portion of still another embodiment of the sheet feeding device according to the present invention. In the present embodiment, the friction pad both ends 1
c is a part of the receiving base 2c, and both ends of the friction pad attaching portion of the receiving base 2c, and the friction pad central part 1
b is provided with a step. As a result, the receiving stand 2c has an edge separating effect, eliminating the need to attach a plurality of friction pads to the receiving stand 2c, thereby achieving cost reduction.

[0014]

As described above, the paper feeder according to the first aspect of the present invention has a step at the center of the friction pad in contact with the paper feed roller and at the other end portions, so that the edge is formed by the edge. The edge separation effect that paper is caught is created, and even if the nip length is short, the reduction of the separation effect can be compensated for and the double feed can be suppressed. Since the separation pressure does not need to be increased by that amount, the occurrence of squeal can be suppressed.

In the paper feeder according to the second aspect, as described above, since the material is different between the center portion and both end portions of the friction pad, the load resistance at the edge is changed by changing the material in addition to the common effect. As a result, it is possible to achieve a desired edge separation effect.

In the paper feeder according to the third aspect, as described above, since there is a step between the both ends of the friction pad where the receiving pad is attached and the center part of the friction pad, in addition to the above-mentioned common effects, the receiving device has Since the table has an edge separation effect, it is not necessary to attach a plurality of friction pads to the receiving table, and cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a conventional friction pad separation unit.

FIG. 2 is a schematic perspective view of a friction pad separating unit in one embodiment of the sheet feeding device according to the present invention.

FIG. 3 is a schematic cross-sectional view of a friction pad separation unit as viewed from a downstream side in the sheet conveyance direction.

FIG. 4 is a schematic perspective view of a friction pad separation unit of another embodiment of the sheet feeding device according to the present invention.

FIG. 5 is a schematic perspective view of a friction pad separating section of still another embodiment of the sheet feeding device according to the present invention.

[Explanation of symbols]

 1a, 1b, 1c, 1d Friction pad 2a, 2b, 2c Receiving stand 3 Separation spring 4a, 4b Feed roller 5 Edge 6 Paper

Claims (3)

[Claims] 1. A sheet feeding device comprising a sheet feeding roller for feeding a sheet and a separating portion having a friction pad for separating the fed sheet, a central portion of the friction pad abutting on the sheet feeding roller. And a sheet feeder characterized by providing a step at both ends. 2. The sheet feeding device according to claim 1, wherein a central portion and both end portions of the friction pad are formed of different materials. 3. The sheet feeding device according to claim 1, wherein a step is provided at both ends of a center of a receiving portion where the friction pad is attached.