JPH0524690A - Paper feeding device - Google Patents

Abstract

PURPOSE:To transport all documents without carrying out cleaning work, etc., by arranging a dummy sheet which is made of the material having the lower frictional coefficient than the transport rubber whose frictional coefficient with a document is lowered by the adhesion of dust, etc., so as to be positioned between a plurality of piled documents and a separating rubber. CONSTITUTION:A dummy sheet 27 is set on the final document 25. The documents 25, 25... in a tray are separated one by one by the revolution of a conveyor belt 5 and transported from the lowermost document toward a lamp. In this transport process, the graphite, etc., adhering on the document 25 are transferred and accumulated on the conveyor belt 5, and the frictional coefficients 25, 25... are transported successively, and the final document 25 comes to be transported, at the time, the frictional coefficient between the belt 5 and the final document 25 is assumed to be 0.6, for instance, because of the adhesion of graphite, etc. However, because the frictional coefficient between the document and the dummy sheet is 0.5 or less, the final document 25 shifts, accompanied with the revolution of the conveyor belt 5, and the document 25 is transported.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeding device used for facsimiles, image scanners, copying machines and other OA equipment.

[0002]

2. Description of the Related Art A sheet feeding device for separating one sheet from a plurality of stacked sheets and conveying the sheet is shown in FIG. 6, for example. In this paper feeding device, high friction materials such as rubber are arranged on the top and bottom, and one of them is used as a conveying rubber
The other one is made to face each other as the separating rubber 6. In this apparatus, the paper 25 in contact with the conveying rubber 5 is conveyed as the conveying rubber 5 moves.
As a general rule, the frictional force on the conveying rubber 5 side is made larger than the frictional force on the separating rubber 6 side. Therefore, the friction coefficient between rubber and paper is about 1.2 on the conveying side and 0.8 on the separating side. It is about degree. However, when a pencil-written original surface is fed to the conveying rubber 5 side, as the number of sheets to be fed increases, graphite powder, paper powder, etc. 26 on the original surface are transferred and accumulated on the conveying rubber surface, and friction gradually occurs. It is empirically known that the force decreases and finally the coefficient of friction between the conveying rubber 5 and the paper decreases to about 0.6 and becomes saturated. In such a state, the frictional force of the conveying rubber 5 becomes smaller than the frictional force of the separating rubber 6, and finally slips between the conveying rubber 5 and the paper feeding becomes impossible.

By the way, the above-described paper feeding failure occurs only when one original is present, and when there are two or more originals, the back side of the original is on the front side of the next original. Since they are in contact with each other, they are not directly affected by the frictional force of the separation rubber 6 and are slippery, so that the paper cannot be fed. That is, the coefficient of friction between manuscript papers is usually 0.4 to 0.5 or less,
Since the frictional force of the conveyed rubber 5 is smaller than that when the conveyed rubber 5 is reduced, the originals in contact with the conveyed rubber 5 are conveyed when there are two or more originals.

In order to prevent such document conveyance, conventionally, for example, the graphite powder or the like adhering to the conveyance rubber is wiped off with anhydrous alcohol or the like, or disclosed in JP-A-2-198.
As described in Japanese Patent No. 934, the method relies on a method of passing a cleaning sheet to temporarily recover the frictional force.

[0005]

However, in such a prior art, not only the maintenance-free required for OA equipment and the like is not taken into consideration, but also the user is forced to perform a troublesome cleaning work. Further, there is a problem that it is impossible to completely prevent the paper feed failure, and the operation of the OA equipment or the like must be frequently interrupted.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a paper feeding apparatus and a paper feeding method capable of feeding all originals without performing cleaning work or the like. And

[0007]

A paper feeding device for achieving the above object holds a plurality of stacked originals between a separating rubber and a conveying rubber, and at least drives the conveying rubber to drive a plurality of originals. In the paper feeding device that separates one sheet from the sheet and conveys it, a dummy sheet made of a material whose friction coefficient with the document is lower than that of the conveyed rubber whose friction coefficient is reduced by adhesion of powder etc. It is characterized in that it is arranged so as to be located between the original and the separation rubber.

Here, the paper feeding device is provided with a sensor for detecting the presence or absence of the document at the stacking position, and stop instruction means for stopping the document conveying operation when the sensor detects the absence of the document. It is preferable that the dummy sheet is provided with a cutout at a corresponding portion so that the sensor does not detect the presence of the document due to the presence of the dummy sheet.

The dummy sheet may be attached to a fixed portion of the main body of the apparatus, for example, a paper guide on the side of the document insertion port. It is preferable that the dummy sheet has a coefficient of friction with the document of 0.5 or less. The dummy sheet may be made of a transparent film.

[0010]

In general, the coefficient of friction between the conveying rubber and the original, the coefficient of friction between the separating rubber and the original, and the coefficient of friction between the original and the original are
It becomes smaller gradually in this order. For this reason, among the plurality of stacked documents, the one that is in contact with the conveying rubber is separated and conveyed as the conveying rubber moves due to the driving of the conveying rubber. However, during this conveying process, graphite powder and the like adhering to the original is transferred and accumulated on the conveying rubber, and the coefficient of friction between the conveying rubber and the original gradually decreases. This friction coefficient causes the friction coefficient between the separating rubber and the original. Can be smaller than When this phenomenon occurs, since the friction coefficient between the separation rubber and the document is large, the final document in contact with the separation rubber cannot be conveyed even when the conveyance rubber is driven. Therefore, in the present invention, a dummy sheet having a smaller coefficient of friction with the original than that of the conveyed rubber is disposed between the separation rubber and the final original. Therefore, by driving the conveying rubber, the final document is moved and conveyed as the conveying rubber having a friction coefficient relatively larger than that of the dummy sheet moves.

In the case where the dummy sheet is provided with a notch, even if there is a dummy sheet,
When the original is lost, the sensor can detect it. This paper-out information is of course used as information for paper-out display and also as information for outputting a conveyance operation stop instruction.

[0012]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 5. The present embodiment is an automatic document feeder used for an image scanner or the like. First, the schematic overall configuration will be described with reference to FIG. The operator places the originals 25, 25, ... With the reading surface facing downward on the tray 21 and pushes up the weight 7 and slides it while inserting it into the separating rubber 6 until the leading edge of the original 25 comes into contact with the original and sets it. When the original is set, the conveyor belt 5 is lower than the sheet guide 14 as shown by the solid line in FIG. 7 and does not contact the original 25, so that the original 25 can be easily inserted. Further, by setting the document 25, the lever 22 of the paper presence / absence sensor is pushed down like 22a, and the operation becomes possible. When started in this state, the conveyor shaft 1 rotates clockwise, and the conveyor belt 5 wound between the conveyor roller 3 and the driven roller 4 is rotated.
As the belt rotates, the conveyor belt 5a is pushed up as shown by the two-dot chain line in FIG. The original 25 is loaded on the lowermost original 25 and the conveyor belt 5 by the load of the weight 7.
Due to friction with the space, a conveying force is generated and is fed. Manuscript 2
When passing under the separating rubber 6 pressed by the spring 8, the sheets 5, 25, ... Are separated into only one sheet of the original document 25 at the lowermost stage, and the rollers 9, 9a and 10 are provided between the sheet guides 15 and 15a. , 10a, the paper is fed from the left side to the right side in FIG.
After being irradiated and read by the roller 1, the rollers 12, 12a are further guided by the sheet guides 16, 16a.
As a result, the paper is ejected like 25a. Note that the separation rubber 6
Is swingably provided on the main body, and is biased by a spring in that direction so that the intrusion side of the document 25 can apply a load to the document 25, so that the efficiency of separation and conveyance of the document 25 is improved. There is.

Characteristic portions of this embodiment will be described with reference to FIGS. 1 and 3. As shown in FIG. 1, the dummy sheet 27 is set on the final document 25. This set is used for the dummy sheet 2 when the final document 25 is conveyed.
7 may be additionally set, or may be first set on the originals 25, 25, .... Here, as the dummy sheet 27, one having a coefficient of friction with the original 25 of 0.4 is used. Further, when the apparatus is ready to convey the dummy sheet 27, that is, the tray 2
As shown in FIG. 3, a notch 28 is provided so that the lever 22 of the paper presence / absence sensor can be operated in the paper out detection state when the original 25 is left on the document 1 and only the dummy sheet 27 remains.

Next, the operation of this embodiment will be described.
The originals 25, 25, ... Inside the tray 21 are separated one by one from below by the rotation of the conveyor belt 5 and are conveyed toward the lamp 31. During this conveyance process, graphite powder and the like adhering to the document 25 are transferred and accumulated on the conveyance belt 5, and the coefficient of friction with the document 25 gradually decreases. As described above, it has been confirmed that the friction coefficient saturates at about 0.6 and does not decrease any further.

When the originals 25, 25, ... Are successively conveyed to become the final original 25, the friction coefficient between the conveying belt 5 and the original 25 becomes, for example, 0.6 due to adhesion of graphite powder or the like. Suppose However, the manuscript 25 and the dummy sheet 2
Since the friction coefficient with 7 is 0.4, the final manuscript 25
Are moved and conveyed as the conveyor belt 5 rotates.
When the final document 25 is conveyed as described above,
The paper presence / absence sensor detects the absence of paper, and the operation of conveying the document is stopped. That is, since the notch 28 is formed in the dummy sheet 27, the lever 22 of the paper presence sensor is not interfered with by the dummy sheet 27 as shown in FIG. To do. Therefore, the dummy sheet 27 remains without being conveyed. The paper-out detection information from the sensor is sent to the CPU provided in the apparatus main body, and the CPU instructs the transport mechanism section to stop the transport operation.

Next, a modification of the dummy sheet 27 set will be described with reference to FIGS. As shown in FIGS. 2 and 4, the end portion of the dummy sheet 27 is bent, and this bent portion 27b is attached to the paper guide 29 on the side of the document insertion port. By doing so, it is possible to save the trouble of setting the dummy sheet 27 each time. It should be noted that the dummy sheet 27 is also provided with a cutout 28 as shown in FIG. 4 so that the lever 22 of the sheet presence sensor can be operated in the state of detecting the absence of the sheet, as in the case described above. 27 is prevented from being conveyed. Further, as a method of attaching the dummy sheet 27 to the apparatus main body side, it is also possible to attach the dummy sheet 27 by using, for example, a tape or a screw, without bending as in this modification.

As described above, according to the present embodiment, even if graphite powder or the like adheres to the conveyor belt 5 to reduce the frictional force with the original 25, the presence of the dummy sheet 27 causes a plurality of originals to be stacked. It is possible to separate one document from 25, 25, ...

In this embodiment, the invention is applied to the image scanner. However, the invention can be applied to any one that conveys a paper on which something is drawn. It can also be applied to copiers and facsimiles. As the dummy sheet, any material may be used as long as it has a coefficient of friction with the original 25 smaller than that of the transport belt 5 having a reduced coefficient of friction. , Resin, etc. may be used. In particular, when the dummy sheet is made of a transparent plastic film, the operator can easily visually check the paper feeding state and the durability is improved so that the dummy sheet can be repeatedly used. Further, although the separation rubber does not rotate in the present embodiment, it goes without saying that the present invention can also be applied to a separation rubber that rotates.

[0019]

As described above, according to the present invention,
By arranging the dummy sheet between the manuscript and the separation rubber, it is possible to convey all the manuscripts without performing a cleaning operation of the conveyor belt on which graphite powder or the like adheres.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a paper feeding device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a paper feeding device according to another embodiment of the present invention.

FIG. 3 is an overall perspective view of a dummy sheet according to an embodiment of the present invention.

FIG. 4 is an overall perspective view of a dummy sheet according to another embodiment of the present invention.

FIG. 5 is an overall sectional view of an image scanner of one embodiment according to the present invention.

FIG. 6 is a perspective view of a main part of a conventional paper feeding device.

[Explanation of symbols]

5, 5a ... conveying belt, 6 ... separating rubber, 21 ... tray,
22 ... Lever of paper presence / absence sensor, 25 ... Original, 27 ... Dummy sheet, 27b ... Bent portion, 28 ... Notch.

Claims (6)

[Claims] 1. A paper feeding device for sandwiching a plurality of stacked originals between a separating rubber and a conveying rubber, at least driving the conveying rubber to separate one sheet from the plurality of originals, and conveying the separated originals. A dummy sheet made of a material whose coefficient of friction with the original document is lower than that of the conveying rubber whose friction coefficient is reduced due to adhesion of powder or the like is arranged so as to be located between the plurality of stacked original documents and the separation rubber. A paper feeding device characterized in that 2. A sensor for detecting the presence / absence of the original document at a stacking position, and a stop instruction means for stopping the operation of conveying the original document when the sensor detects the absence of the original document. 2. A notch is provided in a corresponding portion so that a sensor does not detect the presence of the document due to the presence of the dummy sheet.
The paper feeder described. 3. The paper feeding device according to claim 1, wherein the dummy sheet has a coefficient of friction with an original document of 0.5 or less. 4. The paper feeding device according to claim 1, 2 or 3, wherein the dummy sheet is formed of a transparent film. 5. The dummy sheet is attached to a fixed portion of a main body of the apparatus.
Alternatively, the paper feeding device described in 4. 6. A paper feeding method for holding a plurality of stacked originals between a separating rubber and a conveying rubber, at least driving the conveying rubber to separate one sheet from the plurality of originals, and conveying the separated originals. Before the final original of the plurality of originals is conveyed, a dummy sheet made of a material whose coefficient of friction with the original is lower than that of the conveying rubber reduced by adhesion of powder or the like is provided between the final original and the separation rubber. A paper feeding method characterized by arranging in