JPH0558488A - Paper feed device - Google Patents

Abstract

PURPOSE:To enable even a sheet material high in friction factor width a separation pad to be fed by fitting the separation pad onto a separation pad pressing arm in such a way as to be arranged in an area at a sheet material approaching side when the longitudinal center line of the side force of a paper feed roller in the axial direction is made a division line. CONSTITUTION:When one side of the longitudinal center line O, which is made a division line, in the side face of a paper feed roller 1 in the axial direction, is made to be an area A at a sheet material approaching side, and when the other side is made to be an area C at a sheet material delivery side, a separation pad 2 is fitted onto a separation pad pressing arm 7 in such a way as to be arranged in the area A at the sheet approaching side. There therefore exists no separation pad 2 in the area C of the paper feed roller 1 at the sheet material delivery side. By this constitution, frictional force given to the sheet material S by the separation pad 2 can be reduced to a range required by paper feeding function, the carrying force of the paper feed roller 1 will be strong enough to overcome frictional force between the separation pad 2 and the sheet material S, even if the sheet material S high in friction factor with the separation pad 2, is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device provided in an image forming apparatus such as a copying machine, a printer or a facsimile.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer or a facsimile, a conventional sheet feeding device used for feeding a manually fed sheet material to an image forming portion is shown in FIG.
And shown in FIG.

The present paper feeding apparatus has a paper feeding roller 1 which rotates in a sheet feeding direction (arrow direction), a separation pad 2 which comes into contact with the paper feeding roller 1 at a predetermined pressure, and an upstream of the separation pad 2. On the side, an intermediate plate 3 arranged so as to be able to come into contact with and separate from the paper feed roller 1 is provided.

The sheet feeding roller 1 is for feeding the uppermost sheet of the sheet material 5 manually fed onto the substantially horizontal intermediate plate 3 from the inclined manual feeding tray 5 through the curved guide 6 to the downstream side. When a start signal for image formation is input, the rotation starts.

The separation pad 2 is for separating the uppermost sheet of the sheet material S manually inserted on the middle plate 3 from other sheet materials S, and is attached to the separation pad pressing arm 7.

The separation pad pressing arm 7 is attached to the front side plate 9A and the rear side plate 9B of the image forming apparatus main body so as to be rotatable in the vertical direction about a support shaft 10 and a pressing spring (coil spring) 11 is provided. The separation pad 2 is always brought into contact with the paper feed roller 1 at a predetermined pressure by being urged upwards by.

In this case, the central portion of the separation pad 2 serves as a nip portion between the paper feed roller 1 and the separation pad 2. That is, the central portion of the separation pad 2 is arranged on the vertical center line of the side surface of the paper feed roller 1 in the axial direction.

The middle plate 3 guides the leading edge of the sheet material S manually fed from the manual feed tray 5 into a V-shaped space portion (wedge-shaped portion) 12 formed between the paper feed roller 1 and the separation pad 2. The eccentric cam 13 performs the contact / separation operation with respect to the paper feed roller 1.

The middle plate 3 is a front plate 9A of the image forming apparatus main body.
Further, it is attached to the rear side plate 9B so as to be rotatable in the vertical direction about the support shaft 15 and is pushed upward by a push-up spring (coil spring) 16 to be in contact with the eccentric cam 13 at a predetermined pressure.

As shown in FIG. 4, such an intermediate plate 3 has
When the smallest diameter portion of the eccentric cam 13 that rotates 180 degrees in the direction of the arrow comes into contact with the feed roller 1,
The tip of the sheet material S is guided into the V-shaped space 12. Further, when the maximum diameter portion of the eccentric cam 13 comes into contact, the paper feed roller 1
It becomes a departure state against.

A spring clutch (not shown) is provided on the eccentric cam 13.
Rotational power is transmitted via the motor, and as described above, it is rotated by 180 degrees. When a start signal for image formation is input, the eccentric cam 13 rotates to a position where the smallest diameter portion comes into contact with the middle plate 3 as shown in FIG. 4, and after a predetermined time elapses, the largest diameter portion comes into contact with the middle plate 3. Rotate to position.

The sheet material S to be manually fed is the manual feeding tray 5
When it is placed on and slid on, it is sent to the middle plate 3 through the guide 6 by its own weight, and its tip is positioned near the V-shaped space 12.

In this case, one end of the sheet S is guided by the guide 6
The sheet material S is regulated at the other end of the sheet material S by sliding it in the direction of the arrow (see FIG. 5) by sliding the slide 19 provided on the upper surface of the guide 6 against the side regulation plate 17 provided on the upper surface of the sheet. ..

The sheet material S manually fed as described above is guided by the manual feed guides 20 and 21 provided on the upper surfaces of the manual feed tray 5 and the intermediate plate 3.

The sheet material S fed by the paper feed roller 1 passes through the upper and lower guide plates 22 and 23 and is fed to the pair of registration rollers 25 which are not rotating. The registration roller pair 25 sends the image to an image forming unit (not shown).

[0016]

However, in the sheet feeding device of the above-mentioned conventional example, for the sheet material S such as OHP paper having a high friction coefficient with the separation pad 2, the feeding force of the sheet feeding roller 1 is larger than that of the sheet feeding roller 1. However, since the frictional force between the separation pad 2 and the sheet material S becomes larger, there is a problem that the sheet cannot be fed.

The conventional separation pad 2 is, as described above,
The separation pad pressing arm 7 is attached so that the central portion thereof serves as a nip portion between the paper feed roller 1 and the separation pad 2.

In such a structure, as shown in FIG.
In one sheet material entrance side area A having a vertical center line O on the axial side surface of the paper feed roller 1 as a division line, a function of separating the plurality of entered sheet materials S is made, and a central portion (nip portion) In B, the sheet material S is sandwiched between the sheet material roller 1 and the sheet material S, and a predetermined pressing force is applied to the sheet material roller 1 to generate a conveying force. The action of giving a frictional force to S comes to be performed.

As described above, in the conventional separation pad 2, even the sheet material sending side region C unnecessary for the sheet feeding function has the sheet material S.
Since the frictional force is applied to the sheet material S, as described above, the sheet material S having a high friction coefficient with the separation pad 2 cannot be fed.

Therefore, the present invention has been made in view of the above circumstances, and an object thereof is to provide a sheet feeding device capable of feeding even a sheet material having a high coefficient of friction with a separation pad. To do.

[0021]

According to the present invention, a sheet feeding roller (1) rotating in a sheet material conveying direction and a separation pad (2) contacting the sheet feeding roller (1) at a predetermined pressure are provided. The present invention relates to a sheet feeding device of a type that separates and feeds a plurality of sheet materials (S) supplied between the sheet feeding roller (1) and the separation pad (2) into one sheet.

In the present invention, in order to achieve the above object, one of the separation pads (2) having a vertical center line (O) on the axial side surface of the paper feed roller (1) as a section line is used. When the sheet material entry side area (A) and the other sheet material delivery side area (C) are attached to the separation pad pressing arm (7) so as to be arranged in the sheet material entry side area (A) It is characterized by.

Further, a sheet material pressing member (27), which comes into contact with the sheet feeding roller (1) at a predetermined pressure and has a friction coefficient smaller than that of the separation pad (2), feeds the sheet material of the sheet feeding roller. It is characterized in that it is attached to the separation pad pressing arm (7) so as to be arranged in the side region (C).

The sheet material pressing member (27) is
A cushioning member (2) having a higher elastic modulus than the separation pad (2).
It is characterized in that it is attached to the separation pad pressing arm (7) via 6).

Further, the separation pad (2) is rotatably attached to the separation pad pressing arm (7) in the sheet material conveying direction, and contacts the sheet material feeding side region of the paper feed roller (1). It is characterized in that it is installed on a pad base (30) having a contacting part (30A) that operates.

[0026]

According to the above construction, the separation pad (2) does not exist in the sheet material feeding side region (C) of the paper feed roller (1).

As a result, the frictional force applied to the sheet material (S) by the separation pad (2) can be reduced within the range necessary for the paper feeding function, and the sheet material having a high friction coefficient with the separation pad (2). Even in the case of (S), the feeding force of the paper feed roller (1) overcomes the frictional force between the separation pad (2) and the sheet material (S).

[0028]

Embodiments of the present invention will be described below with reference to the drawings.

<Embodiment 1> FIG. 1 shows a paper feeding apparatus according to Embodiment 1 of the present invention.

In this paper feeding apparatus, the same members as those of the above-described conventional paper feeding apparatus are designated by the same reference numerals, and the description of those having the same functional configuration will be omitted.

In this paper feeding device, the separation pad 2 is attached to the separation pad pressing arm 7 so as to be arranged in the sheet material entrance side area A of the paper feeding roller 1.

The separation pad 2 used here is 25 to 35.
% Of cork, the friction coefficient with the sheet material S is about μ = 1.2.

The separating pad 2 has a strip plate shape with a thickness of 2.5 mm, a length of 54 mm and a width of 5 mm, and its end portion is a vertical center line of the axial side surface of the paper feed roller 1. It is fixed to the upper surface of the separation pad pressing arm 7 with an adhesive or the like so as to be located on O.

Further, the separation pad 2 for the paper feed roller 1
Contact pressure (the pressure applied to the separation pad pressing arm 7) is P =
It is 260 g / cm ² . The nip width at this time is 2.5 mm.

Generally, the frictional force is considered to be the product of the friction coefficient and the vertical force (F = μN), but in the case of an elastic body such as rubber, it is greatly affected by the contact area. When the separation pad 2 is not provided in the sheet material feeding side region C of the paper feeding roller 1 as in the present paper feeding device, the frictional force applied to the sheet material S of the separation pad 2 is significantly reduced.

<Embodiment 2> FIG. 2 shows a main part of a paper feeding apparatus according to Embodiment 2 of the present invention.

In this embodiment, the separation pad pressing arm 7 is used.
A sheet having a smaller friction coefficient than that of the separation pad 2 via a cushioning member 26 having a higher elastic modulus than that of the separation pad 2, for example, a sponge or the like, at a portion corresponding to the sheet material feeding side region C of the paper feed roller 1. A material pressing member 27 is provided.

In such a structure, the sheet material pressing member 2
7 presses the sheet feeding roller 1 via the sheet material S with a pressing force smaller than that of the separation pad, and the sheet material S has a conveying force received from the sheet feeding roller 1 rather than a resistance force received from the sheet material pressing member 27. Since it is large, a large carrying force can be obtained.

<Embodiment 3> FIG. 3 shows a main part of a paper feeding apparatus according to Embodiment 3 of the present invention.

In this embodiment, the separation pad 2 is not directly attached to the separation pad pressing arm 7 but is attached to the separation pad pressing arm 7 so as to be rotatable about the support shaft 29 in the sheet material conveying direction. It is fixed to one side of the pad base 30 with an adhesive or the like.

On the other side of the pad base 30, there is an inclined portion (contact portion) 30A which comes into contact with the sheet material feeding side region C of the paper feed roller 1.
Is provided.

With such a structure, the positional relationship between the paper feed roller 1 and the separation pad 2 can be easily set. Also, support 2
By changing the position of 9, it is possible to arbitrarily change the balance between the contact force of the separation pad 2 relating to the sheet material separating performance and the pressing force of the inclined portion 30A relating to the sheet material conveying performance.

[0043]

As described above, in the sheet feeding device of the present invention, the separation pad is arranged only in the sheet material entrance side area of the sheet feeding roller, so that the frictional force of the separation pad against the sheet material can be reduced. it can. Therefore, even a sheet material having a high friction coefficient with the separation pad can be fed.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a paper feeding device according to a first embodiment of the invention.

FIG. 2 is a vertical sectional side view of a main part of a sheet feeding device according to a second embodiment of the invention.

FIG. 3 is a vertical cross-sectional side view of a main part of a sheet feeding device according to a third embodiment of the invention.

FIG. 4 is a vertical sectional side view of a conventional paper feeding device.

FIG. 5 is a plan view of the paper feeding device.

FIG. 6 is a vertical cross-sectional side view of a main part for explaining a problem of a conventional paper feeding device.

[Explanation of symbols]

 1 Paper Feeding Roller 2 Separation Pad 7 Separation Pad Pressure Arm 26 Cushioning Member 27 Sheet Material Pressing Member 30 Pad Stand 30A Inclined Part (Contact Area) A Sheet Material Entry Side Area of Paper Feeding Roller Sheet Material Sending Side of Paper Feeding Roller Area O Vertical center line of paper feed roller S Sheet material

Claims (4)

[Claims] 1. A sheet feeding roller that rotates in a sheet material conveying direction, and a separation pad that comes into contact with the sheet feeding roller at a predetermined pressure, and is supplied between the sheet feeding roller and the separation pad. In a sheet feeding device of a type in which a plurality of sheet materials are separated and fed, one of the separating pads is a sheet material entrance side region with a vertical center line of an axial side surface of the sheet feeding roller as a dividing line. A sheet feeding device, characterized in that, when the other is a sheet material feeding side area, it is attached to the separation pad pressing arm so as to be arranged in the sheet material entering side area. 2. A sheet material pressing member, which comes into contact with the paper feed roller at a predetermined pressure and has a smaller friction coefficient than the separation pad, is arranged in a sheet material delivery side region of the paper feed roller. The sheet feeding device according to claim 1, wherein the sheet feeding device is attached to a separation pad pressing arm. 3. The sheet feeding device according to claim 2, wherein the sheet material pressing member is attached to the separation pad pressing arm via a cushioning member having a higher elastic modulus than the separation pad. .. 4. The pad pad having a contact portion that is rotatably attached to the separation pad pressing arm in the sheet material conveying direction and has a contact portion that comes into contact with a sheet material feeding side region of the paper feed roller. The sheet feeding device according to claim 1, wherein the sheet feeding device is installed.