JPH0611623B2 - Paper feeder for copier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Prior Art) The present invention presses a separation member made of an elastic material such as rubber against a feed roll to elastically deform it, and to copy a copy sheet between the feed roll and the elastic deformation portion of the separation member. The present invention relates to a sheet feeding device for a copying machine that separates sheets one by one and conveys them to a transfer unit.

(Prior Art) As a conventional paper feeding device for a copying machine, there is, for example, a device using a separation claw (snubber) or a retard pad such as rubber, and a plurality of copy papers stored in a paper feeding cassette are used. Each sheet is separated and fed to the transfer section.

With the separation claw, separation claws are provided at two corners of the paper feed direction of the paper feeding cassette, and the leading end of the uppermost copy paper fed by the feed roll is restrained by the separation claw to form slack in the copy paper. However, when the constraint of separation cooling is released due to an increase in the amount of slack, the copy paper in the lower layer is separated and fed in the paper feed direction.

However, in this separation method, since it is necessary to cause slack in the uppermost copy sheet, a space for forming slack is required on the paper feed tray inside the copying machine,
There is a risk of increasing the size of the copier itself.

Further, in the case of using the retard pad system, when the copy paper is moved by the rotation of the feed roll, the leading end of the copy member is provided with a separating member (this separating member has a friction coefficient greater than that between the feed roll and the copy paper). It is composed of a rubber material that has a small friction coefficient with the copy paper, and the contact pressure with the feed roll is adjusted by a pressure adjustment mechanism that uses a spring etc.) and the lower copy paper moves. Therefore, the uppermost copy sheet is separated from the lower copy sheet and fed in the paper feeding direction.

However, this retard pad system requires a pressure adjusting mechanism for adjusting the contact pressure of the separating member with respect to the feed roll, which complicates the internal mechanism of the copying machine and increases the number of parts. Has the drawback of being high.

(Object and Structure of the Invention) The present invention has been made in view of the above, and in order to prevent an increase in size and cost of a copying machine, a separation member made of an elastic material such as rubber is pressed against a feed roll and elastically deformed. The present invention provides a sheet feeding device for a copying machine, which separates copy sheets one by one between the feed roll and the elastically deforming portion of the separating member.

Hereinafter, the sheet feeding device for a copying machine according to the present invention will be described in detail.

(Embodiment) FIGS. 1 (a), (b), (c), and (d) show an embodiment of the present invention, in which copying is performed by an original scanning optical system A, a copy image forming system B, and a copy paper feeding system C. The pad 2 provided on the copy paper feeding system C of the machine (FIG. 1 (a)) and having a length substantially corresponding to the lateral length of the paper feeding cassette 7 is a paper transport chute 3
Are supported by holding protrusions 4a and 4b formed at one end of the. The chute 3 is fixed to the main body of a copying machine (not shown) and serves as a conveyance path for the copy paper 5 carried out by the feed roll 1 and the pad 2. An elastically deforming portion 2a is provided on the upper portion of the pad 2 and has a curved (arch) shape so that the copy paper 5 can be easily conveyed, and inside thereof is elastically deformed by a relatively small contact pressure and buckled. When the space 6 is provided so as to generate stress and is brought into pressure contact with the feed roll 1, the elastically deformable portion 2a is deformed as shown in FIG. A support space 2b is formed in the lower part of the pad 2 and is supported by the protrusions 4a and 4b of the chute 3 inserted therein, and is composed of, for example, polyurethane rubber, silicon rubber, foamed polyurethane, or the like. The chute 3 is made of, for example, stainless steel.

FIG. 4 shows the contact pressure and deformation amount characteristics of the elastically deformable member according to the present invention.

The figure shows the contact pressure on the vertical axis and the deformation amount on the horizontal axis. As is clear from the figure, the amount of deformation increases substantially in proportion to the contact pressure up to a predetermined contact pressure, but when buckling occurs in the arched portion, the amount of deformation is significantly larger than the amount of increase in contact pressure. Will increase.

The present invention is characterized in that the elastically deformable member has such a property.

The elastically deformable portion 2a has a wall thickness t of about 1 ± 0.5 mm.
This is a normal waist-strength copy paper (100 in the fiber direction).
mm length, width of 40 mm, and a predetermined contact pressure between the feed rolls 1 when the length of the other end is about 20 mm when supported at one end in the length direction. It is necessary to occur. When the wall thickness t is made thinner than this, the elasticity of the pad 2 becomes poor and causes multiple feeding. When the wall thickness t is made thicker than this, the contact pressure of the pad 2 becomes large and the copy paper 5 may not be conveyed. . On the other hand, the paper feed cassette 7 is provided with a slit 8 in the lower portion as shown in FIG. 1D, and a pressure applying member 9 provided in the copying machine places the copy paper 5 through the slit 8. The bottom plate 10 is elastically lifted so that the copy sheet 5 is always in contact with the feed roll.

In the above configuration, when the feed roll 1 rotates and the copy sheet 5 moves, the leading end of the feed roll 1 is pinched by the elastically deforming portion 2a of the pad 2 and the nip portion 11 of the feed roll 1,
A predetermined contact pressure is applied to the copy sheet 5 by the buckling stress of the elastically deformable portion 2a. The frictional engagement force between the feed roll 1 and the uppermost copy sheet 5 based on this contact pressure is larger than the frictional engagement force between the lower layer copy sheet 5 and between the copy sheet 5 and the elastically deformable portion 2a. Only the upper copy paper 5 is sent out in the paper feeding direction, and the lower copy paper 5 is fed.
Is stopped at the elastically deforming portion 5 at the moment. Second
The figure shows an example of the structure of the chute 3. One end of the chute 3 is supported, the chute 3 is pivotally supported at a fulcrum 3a at a substantially central portion, and the cam 12 is provided at the other end. for that reason,
When the cam 12 has the posture shown by the dotted line, the chute 3 and the pad 2 are in the state shown by the dotted line, and the pad 2 can be prevented from coming into contact with the feed roll 1. Therefore, when the sheet is not fed, it is possible to suppress the deterioration due to the elastic deformation of the pad 2 by setting the dotted line state. In FIG. 3, the pad 2 is attached to one end of the chute 3 and is provided.

As described above, according to the sheet feeding device for a copying machine of the present invention, the upper portion of the elastically deformable member is formed in an arch shape having an internal space, and the arched portion has a relatively small contact pressure. Since it is assumed that the elastic deformation causes buckling stress,
When a predetermined contact pressure is applied, the arched portion is deformed by a necessary amount and deformed sufficiently. Therefore, it is possible to keep the state of being in pressure contact with the feed roll while the contact pressure hardly changes. Therefore, unlike the case of using a solid elastic deformation member, it is not necessary to separately provide position adjusting means for bringing the elastic deformation member into contact with the feed roll at a predetermined pressure, and the number of parts can be reduced, Since the adjustment range can be widened, it is not necessary to accurately set the positional relationship between the feed roll and the elastically deformable member at the time of assembly, and the assembly can be carried out very easily. Therefore, it is possible to prevent the copying machine from increasing in size and cost.

[Brief description of drawings]

FIG. 1 (a) is an overall view of a copying machine provided with the copying machine paper feeding device of the present invention. FIG. 1B is a perspective view of the sheet feeding device for a copying machine according to the present invention. FIG. 1C is a sectional view of the pad of the present invention. FIG. 1D is an explanatory view showing a state in which the pad is pressed against the feed roll. FIG. 2 is an explanatory view showing the structure of the chute. FIG. 3 is an explanatory view showing another embodiment of the present invention. FIG. 4 is a characteristic diagram of the elastically deformable member. Explanation of symbols 1 ... Feed roll, 2 ... Pad, 3 ... Chute, 5 copy paper, 7 ... Paper feed cassette, 8 ... Slit, 9 ... Pressure applying member, 10 ... Bottom plate.

Claims (1)

[Claims] 1. A sheet feeding device for a copying machine, which separates copy sheets one by one and conveys them to a transfer section, wherein an upper portion is arched by an internal space, and the arched portion is elastically deformed by a relatively small contact pressure. A sheet feeding device for a copying machine, wherein an elastically deformable member that generates buckling stress is provided in pressure contact with a feed roll.