JPH0524694A - Paper feeding device - Google Patents

Abstract

PURPOSE:To supply a paper document sheet having a high frictional coefficient, suppressing the generation of abnormal noise. CONSTITUTION:A separating piece 4A which is pressed over a proper length on the outer peripheral surface of a paper feeding roller 3 is constituted of a rubber plate 4a and a plastic film 4b which is attached on the back surface of the rubber plate 4a and hardly to be extended, and when a document 1 having a high frictional coefficient is supplied, the separating piece 4A is prevented from being extended, even if pulled by the document 1, and the generation of abnormal noise is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeder for separating stacked sheets one by one in a facsimile machine, a copying machine or the like.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, an apparatus of this type is arranged so as to contact a paper feed roller 3 arranged at the lower end of a document table 2 on which a document 1 is placed, and the paper feed roller 3. A separating plate 4 made of a rubber plate, a pressing member 5 that bends the lower end portion of the separating plate 4 along the circumferential surface of the sheet feeding roller 3 and presses the circumferential surface, and a pressing force is applied to the pressing member 5. It was provided with a pressing spring 6 and the like for giving a plurality of originals 1 set on the original table 2 and separating them one by one to feed them between a lower feed roller 8 and a pinch roller 9. . Here, the separation of the manuscript means that the frictional force between the members is
[Friction force between originals] <[Friction force between originals and separation piece] <[Friction force between originals and paper feed roller].

Further, instead of bending the separating piece over a range of a certain length and pressing the separating piece against the outer peripheral surface of the paper feeding roller, the separating piece is supported flat by a leaf spring, and the paper feeding roller is supported. There is also known one configured to be in line contact with (see, for example, JP-A-60-102345).

Further, the entire separation pad corresponding to the separation piece is constrained by a holder, the separation pad is pressed against a paper feed roller, and serrated irregularities are formed on the surface of the separation pad to prevent double feeding of documents. A structure is also known (for example, see Japanese Patent Laid-Open No. 62-295841).

[0005]

However, there are problems in any of the conventional configurations. That is, in the paper feeding device having the configuration shown in FIG. 7, when an original having a high friction coefficient such as coated paper is used, the friction force between the separating piece and the original is large, so that the original is separated as shown in FIG. Manuscript 1 after
When the sheet passes between the paper feed roller 3 and the separating piece 4, the separating piece 4 is pulled by the original 1 and stretches, which causes a noise and a feeding failure.

Further, in the case of utilizing line contact as disclosed in Japanese Patent Laid-Open No. 60-102345, since the contact length between the paper feed roller and the separating piece is short, the feeding force applied to the original document is insufficient and the paper is fed. Sometimes it caused a defect. Furthermore, JP-A-62
Similarly, the one proposed in Japanese Patent No. 295841 has a problem in that a paper feed failure may occur and the apparatus is complicated and expensive.

The present invention has been made in view of the above problems, and is capable of excellent paper feeding with a simple structure.
Further, it is an object of the present invention to provide a sheet feeding device that causes less abnormal noise even when a document having a high friction coefficient is used.

[0008]

In order to solve the above-mentioned problems, the present invention provides a sheet feeding device of a type in which a separating piece is curved and is pressed against a circumferential surface of a sheet feeding roller for a certain length. The separation piece is composed of a rubber plate and a plastic film which is attached to the back surface of the rubber plate and is hard to stretch. The plastic film used here is also bendable by itself so as to allow the rubber plate to bend in order to press it against the circumferential surface of the paper feed roller, and is less stretchable than the rubber plate. As the thickness,
It is preferably about 0.1 to 0.5 mm.

The surface of the rubber plate constituting the separating piece facing the paper feed roller is usually made smooth, but if the original to be used has a very large friction coefficient, a plurality of small irregularities should be provided. Is preferred.

[0010]

According to the present invention, the separating piece is in contact with the circumferential surface of the sheet feeding roller for a certain length by the above-described structure, which enables good separation and sheet feeding, and the separated document is When passing between the paper feed roller and the separating piece, the coefficient of friction of the original document is large, so even if a large pulling force acts on the separating piece, the plastic film on the back side of the separating piece will not stretch and this will cause abnormal noise. Can be suppressed.

If a large number of concaves and convexes are formed on the surface of the separating piece facing the paper feed roller, when a document having an extremely high friction coefficient is fed, the convex portion contacting the document is deformed to feed the document. It is possible to prevent a paper feed failure.

[0012]

1 is a schematic side view of a sheet feeding device according to an embodiment of the present invention, in which the same parts as those in the conventional example shown in FIG. 7 are designated by the same reference numerals. In FIG. 1, 1 is a manuscript and 2
Is a document table on which the document 1 is placed, 3 is a sheet feeding roller arranged at the lower end of the document table 2, and 4A is a separating piece arranged so as to contact the sheet feeding roller 3. This separation piece 4A is shown in FIG.
As shown in enlarged form, it is composed of a rubber plate 4a having flat surfaces on both sides and a plastic film 4b attached to the back surface thereof. As the plastic film 4b, one that is bendable but less stretchable than the rubber plate 4a is used. The thickness is preferably about 0.1 to 0.5 mm.
5 is a pressing member that bends the lower end portion of the separating piece 4A along the circumferential surface of the sheet feeding roller 3 and presses it against the circumferential surface; 6 is a pressing spring that applies a pressing force to the pressing member 5; A feed roller 9 for conveying the formed document further downstream, and a pinch roller 9.

The operation of the sheet feeding device configured as described above will be described below. The lower end portion of the separation piece 4A is pressed by the pressing member 5 over a predetermined length range of the outer peripheral surface of the paper feed roller 1 to form a separation area having a predetermined length. A plurality of originals 1 set on the original table 2 are fed between the paper feed roller 1 and the separating piece 4A, separated one by one as in the conventional case, and the lower feed roller 8
And paper is fed between the pinch roller 9. Here, since the separation area is present over a certain length in the circumferential direction of the paper feed roller 1, the separation and the paper feed are reliably performed. As shown in FIG. 3, the original after being separated is fed with the paper feed roller 1 and the separating piece 4 as shown in FIG.
Although it passes between A and A, the separating piece 4A is pulled by the passing document 1 at this time, and the separating piece 4A has an arrow F.
The force indicated by acts. This force F becomes extremely large when the original has a high friction coefficient such as coated paper. However, since the back surface of the separating piece 4A is provided with the plastic film 4b that is difficult to stretch, the separating piece 4A does not extend, which suppresses the generation of abnormal noise and does not cause a paper feed failure. Thus, good and stable paper feeding is performed.

By the way, in the paper feeding device having the above-mentioned structure, even a document having a high friction coefficient can be fed without the separating piece extending. However, when the friction coefficient is extremely high, the separating piece and the document surface can be fed. In some cases, the frictional force between and becomes too great to feed the original. In that case, the separating piece 4B shown in FIG. 4 is used in place of the separating piece 4A having a flat surface. This separating piece 4B also has a rubber plate 4a similar to the separating piece 4A.
And a plastic film 4b attached to the back surface of the rubber plate 4a, the surface of the rubber plate 4a facing the paper feed roller is provided with irregularities made of a plurality of elongated projections 10.

A sheet feeding operation using the separating piece 4B will be described with reference to FIG. FIG. 5 is an enlarged view of a portion of the separating piece 4B which is in contact with a sheet feeding roller (not shown).
(A) shows a state in which the paper feed roller is stopped. In this state, the protrusion 10 is upright. When the paper feed roller starts to rotate, the driving force P is applied to the document 1 as shown in FIG.
The driving force P moves the document 1 and the projection 10 on the surface of the separation piece 4B is deformed by the frictional force F, and a restoring force T is generated on the projection 10. When the paper feed roller further rotates, the deformation of the protrusion 10 and the restoring force T increase, and eventually F = T as shown in FIG. 5C. Since the frictional force F fluctuates, momentarily F <T and slippage occurs between the document 1 and the projection 10, and the projection 10 is restored by a small displacement as shown in FIG. Get caught.
Hereinafter, the document is fed by repeating this operation. In this way, by utilizing the local deformation of the protrusions on the surface of the separating piece 4B, it is possible to stably and reliably feed even a document having an extremely high friction coefficient.

Although the projections and depressions are formed by the elongated protrusions 10 in the above embodiment, the shape of the projections and depressions is not limited to this and can be variously changed. For example, as shown in FIG. Alternatively, as shown in FIG. 6 (b), the protrusions and recesses 10B having a small columnar shape may be used to form the unevenness.

[0017]

As is apparent from the above description, according to the present invention, a separating piece is curved in a curved surface and is pressed against the circumferential surface of the sheet feeding roller for a certain length. Is composed of a rubber plate and a plastic film that is attached to the back surface and is hard to stretch, which enables good separation and feeding of originals, and the separated originals are fed by a paper feed roller and a separating piece. Since the original has a large coefficient of friction when passing between and, even if a large pulling force acts on the separating piece, the plastic film on the back side of the separating piece will prevent stretching and thereby suppress the generation of abnormal noise. Therefore, it is possible to stably feed a document having a high coefficient of friction without producing abnormal noise.

If a large number of irregularities are formed on the surface of the separating piece facing the paper feed roller, when a document having an extremely high friction coefficient is fed, the convex portion contacting the document is deformed to feed the document. And has the effect that even a document with an extremely high friction coefficient can be stably fed.

[Brief description of drawings]

FIG. 1 is a schematic side view showing a sheet feeding device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an exploded view of a separation piece 4A used in the above embodiment.

FIG. 3 is a schematic side view showing an enlarged sheet feeding portion in the above embodiment.

FIG. 4 is a schematic perspective view of a separation piece 4B used in another embodiment of the present invention.

5 (a), (b), (c) and (d) are respectively,
4 is a side view showing an enlarged state of a part of the separating piece 4B which is in contact with the sheet feeding roller, for explaining a state of feeding by the separating piece 4B shown in FIG.

6 (a) and 6 (b) are schematic perspective views showing modified examples of unevenness formed on the separation piece 4B.

FIG. 7 is a schematic side view showing a conventional paper feeding device.

FIG. 8 is a schematic side view showing an enlarged paper feeding portion in the conventional example.

[Explanation of symbols]

1 manuscript 2 Platen 3 paper feed rollers 4, 4A, 4B Separation piece 4a rubber plate 4b plastic film 5 Pressing member 6 Pressing spring 8 feed rollers 9 pinch rollers 10 protrusions

Claims (2)

[Claims] 1. A paper feed roller, a separation piece provided so as to contact the paper feed roller, and a pressing member which bends the separation piece along the circumferential surface of the paper feed roller and presses it against the circumferential surface. And a separation sheet made of a rubber plate and a plastic film attached to the back surface of the rubber plate, which is hard to stretch. 2. The sheet feeding device according to claim 1, wherein the surface of the separating piece facing the sheet feeding roller is provided with a plurality of irregularities.