JPH05147759A - Automatic sheet feeding and transporting device - Google Patents

Abstract

PURPOSE:To make feeding and transportation of a bundle of sheets certainly at all times irrespective of the thickness of the bundle by forming a tab on a resilient plastic film, through which the force of a pressurizing plate is to be transmitted to the bundle of sheets, and by transmitting the pressurizing force to the bundle of sheets through this tab. CONSTITUTION:An automatic sheet feeding and transporting device transmits the force of a pressurizing plate 3 to a bundle of sheets 5 through a resilient plastic film 9. In this resilient film 9, the front of the area where the pressurization part 3a of the plate 3 is in contact is separated from the two sides, and only the rear is coupled with the body of the film so as to form a tab 9a. This pressurization part 3a of the plate 3 is contacted by pressure with the bundle 5 of sheets through the tab 9a. If the thickness of the bundle 5 reduced, only the tab 9a is heaved, so that the pressurizing force can be transmitted effectively to the bundle 5 with no loss generated. Thereby feeding and transportation of bundle of sheets can be done certainly at all times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic paper feeding / conveying device for automatically feeding a document or recording paper to an image forming apparatus.

[0002]

2. Description of the Related Art As an automatic document feeder for an image forming apparatus such as an electrophotographic copying machine or a facsimile, a lower sheet feeding system capable of placing a stack of originals placed in a page-down direction and feeding them out in a page order from the bottom. Are advantageous. Also in the case of a recording paper feeding device, the lower paper feeding method is excellent in that the paper can be replenished during the feeding.

An example of a typical conventional lower sheet feeding type automatic sheet feeding / conveying apparatus will be described with reference to FIGS. The sheet guide member 2 is provided so as to face the upper surface of the sheet feed table 6, and the sheet bundle 5 is formed as shown in FIG.
6 is slid forward from the rear of the paper feed table 6 as shown in FIG.
As shown in FIG. 3, the paper is placed on the paper feed table 6 so that its front end contacts the paper feed roller 8 and the separation roller 1. Below the paper tray 6,
A pickup roller 7 having a circular cross section that can press the lower surface of the sheet bundle 5 set on the paper feed table 6 at the circumferential portion during rotation.
Is provided. A roller pair of the paper feed roller 8 and the separation roller 1 is provided on the downstream side of the pickup roller 7 in the conveyance direction. The rear end is pivotally supported at a position above the guide member 2 so as to press the sheet bundle 5 set on the paper feed table from above, and the front end portion branches into a fork shape as shown in FIG. The front end is bent upward through a plurality of escape holes provided in the pressurizing plate 3 that presses the upper surface of the sheet bundle with the pressurizing portion at the antinode of the bending portion so that the spring 4 rotates in the pressing direction. It is urged to. The rear end portion of the guide member 2 into which the sheet bundle is inserted obliquely rises upward, the rear end is fixed to the lower surface of the portion, and the elastic synthetic resin thin film (for example, polyethylene terephthalate) that extends forward while contacting the upper surface of the sheet bundle. : Product name Mylar) is provided. Therefore, the sheet bundle 5 has little friction with the pressing portion of the pressing plate and can be smoothly inserted and set on the paper feed table 6.
The sheet bundle 5 is pressed through the elastic synthetic resin thin film 9 by the pressing portion at the front end of the pressing plate 3 whose upper surface is biased by the spring 4.
When the sheet is fed, it is pressed against the rotating pickup roller 7 and is conveyed through the nip portion between the sheet feeding roller 8 and the separation roller 1 by frictional force to separate the double feed, and are fed one by one from the bottom.

However, when sheet feeding is repeated and the number of sheet bundles on the sheet feeding table 6 decreases as shown in FIG. 7, the pressing force by the pressing plate 3 is an elastic force generated by the elastic synthetic resin thin film 9 bending. Is not reliably transmitted to the sheet bundle 5, and the pressing force between the lower surface of the sheet bundle and the pick-up roller 7 becomes insufficient, which causes non-feeding.

[0005]

SUMMARY OF THE INVENTION The present invention has been conceived in view of the above-mentioned problems of the lower sheet feeding type automatic sheet feeder having the above-mentioned structure.
An object of the present invention is to provide an automatic sheet feeding / conveying device in which a sheet bundle is always reliably pressed against a pickup roller even when the number of sheets on the sheet feeding table is reduced, and non-feeding is prevented.

[0006]

In order to solve the above-mentioned problems, the present invention is directed to a portion of the automatic sheet feeding / conveying apparatus having the above-mentioned structure, which is in contact with the pressing portion at the front end of the pressing plate made of an elastic synthetic resin thin film. It is characterized in that the front portion and both side portions are separated from the surroundings, and a tongue-shaped portion connected to the synthetic resin thin film body is formed only at the rear end portion.

[0007]

With the above construction, the pressing portion of the pressing plate pushes down the tongue portion and presses the upper surface of the sheet bundle through this.
Since the tongue is connected to the synthetic resin thin film main body only at the rear end, it does not require a large force to the left to push down the tongue, and the pressing force of the pressure plate by the spring does not cause a large loss to the sheet bundle. It is transmitted, and the non-feeding is prevented without reducing the pressure contact force between the pickup roller and the sheet bundle.

[0008]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a plan view of an elastic synthetic resin thin film in the vicinity of a pressurizing portion of a pressurizing plate 3 of an embodiment in which the present invention is applied to the automatic sheet feeding / conveying apparatus described with reference to FIGS. The elastic synthetic resin thin film 9 has a tongue-shaped portion 9a which is connected to the synthetic resin thin film main body only at the rear portion, in which the front portion and both side portions of the portion of the pressure plate 3 with which the pressure portion 3a abuts are separated. .

Therefore, the pressing portion 3a at the front end of the pressing plate 3 is
Presses against the upper surface of the sheet bundle via the tongue portion 9a, and when the thickness of the sheet bundle decreases, only the tongue portion 9a reaches the upper surface of the sheet bundle by the pressing portion 3a of the pressing plate 3 as shown in FIG. Since the other parts of the synthetic resin thin film cannot be pressed down, the pressing force of the pressure plate 3 is transmitted to the sheet bundle with almost no loss, and the sheet is fed by the pickup roller without fear of non-feeding. It

As shown in FIG. 4, the width W of the tongue portion 9a becomes narrower or has a constant width from the root of the synthetic resin thin film body 9 toward the tip. Therefore, even if the side edge of the sheet happens to come into contact with the side edge of the tongue depending on the size of the sheet to be fed, there is no possibility that the sheet is caught in the tongue and causes a jam or a skew.

Instead of providing the tongue-shaped portion 9a on the elastic synthetic resin thin film 9, as shown in FIG. 3, the opening 9c is provided by cutting off the four circumferences of the portion of the pressure plate 3 corresponding to the pressure portion 3a, and adding the pressure plate. A synthetic resin thin plate piece 9b having a low friction coefficient is formed on the lower surface of the pressure portion 3a.
May be attached or a resin having a low friction coefficient may be coated.

In this way, when the thickness of the sheet bundle is reduced, the pressing portion 3a of the pressing plate 3 passes through the opening 9c of the elastic synthetic resin thin film 9 as shown in FIG. 4, and the synthetic resin thin plate piece 9b. Alternatively, the pressing force can be transmitted to the upper surface of the sheet bundle 5 through the coating layer without any loss. As the material of the synthetic resin thin plate piece 9b, polyethylene terephthalate, which is the same material as the elastic synthetic resin thin film, can be used.

[0013]

As described above, according to the present invention, the pressure applied by the pressure plate is reliably transmitted to the sheet bundle, and the pickup roller can feed the sheet with less possibility of non-feeding.

[Brief description of drawings]

FIG. 1 is a plan view showing the vicinity of a tongue-shaped portion provided at an abutting portion of a pressure plate pressing portion of an elastic synthetic resin thin film of an automatic sheet feeding / conveying device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating the operation thereof.

FIG. 3 is a plan view showing the vicinity of an opening provided at a position corresponding to a pressing plate pressing portion of an elastic synthetic resin thin film of an automatic paper feeding / conveying device according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating the operation thereof.

FIG. 5 is a cross-sectional view showing the configuration of a typical example of a conventional lower sheet feeding type automatic sheet feeding and conveying apparatus.

FIG. 6 is a cross-sectional view illustrating the operation thereof.

FIG. 7 is another cross-sectional view illustrating the operation thereof.

FIG. 8 is a perspective view showing the shape of a pressure plate of the automatic sheet feeding and conveying device.

[Explanation of symbols]

 1 Separation Roller 2 Guide Member 3 Pressure Plate 3a Pressure Unit 4 Pressure Spring 4 Paper Bundle 6 Paper Feeding Stage 7 Pickup Roller 8 Pickup Roller 9 Elastic Synthetic Resin Thin Film 9a Tongue 9b Synthetic Resin Thin Piece

Claims (3)

[Claims] 1. A paper feed table on which a stack of paper sheets is placed, and the lower surface of the paper stack placed on the paper feed tray is pressed into contact with a lower surface of the paper sheet bundle through an escape hole provided in the paper feed tray to rotate the paper in order from the bottom. A pickup roller that sends out, a guide member that faces the upper surface of the paper feed table and guides the paper that is sent out by the pickup roller to the paper feed roller, the rear end is pivotally supported above the guide member, and the front end is branched into a fork shape. Then, the pressing plate is bent upward and is biased by a pressing spring so as to press the sheet bundle placed on the sheet feeding table from above by the pressing portion at the antinode of the bending portion. In the automatic paper feeding / conveying device having an elastic synthetic resin thin film which is fixed and is pressed against the upper surface of the sheet bundle from above by the pressing portion of the pressure plate and transmits the pressing force of the pressing plate to the sheet bundle, The front part and both side parts of the part that comes into contact with the pressure part of the pressure plate It is characterized in that a tongue-shaped portion which is separated from the surroundings and is connected to the synthetic resin thin film main body is formed only at the rear end portion, and the pressure portion of the pressure plate presses the sheet bundle through the tongue-shaped portion. Automatic paper feeding and conveying device. 2. The automatic sheet feeding / conveying apparatus according to claim 1, wherein the width of the tongue portion is uniform in the sheet conveying direction or becomes narrower toward the front from the rear end. 3. The elastic synthetic resin thin film according to claim 1, wherein the tongue-shaped portion is formed, the opening of the synthetic resin thin film contacting with the pressurizing portion of the pressurizing plate is divided into four openings, and the pressurizing plate is applied. An automatic sheet feeding / conveying device characterized in that a synthetic resin thin film having a shape smaller than the opening is attached or coated on the lower surface of the pressure section.