JPS6211869Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a paper feed section of a copying machine or the like. When feeding paper in a copying machine, for example, transfer paper must be intermittently fed one by one to a transfer position in synchronization with the rotation of a photosensitive drum. However, since transfer papers are usually placed on the paper feed table in a stacked form, when using a simple feeding method, several sheets are sent to the transfer position at the same time (hereinafter referred to as multi-feeding). Fear emerges. Therefore, various measures to prevent this have been considered in the past. For example, metal claw members may be provided at both front corners of the stacked transfer paper.
Alternatively, a device is known that utilizes the difference in the static friction coefficient between the transfer paper and a rubber belt and the static friction coefficient between the transfer paper and a non-rotating member. It is also known that the interaction between the rubber belt and the non-rotating member described above is replaced by simply pressing a rubber piece against the transfer paper feed roller with a weak spring. In addition, a fixed roller system is also well known. However, in the case of the method using claw members, if the shapes of the left and right claws are uneven, paper is likely to bend, requiring precise adjustment to account for variations in paper size, and the operability of paper replenishment is poor. The disadvantage is that the separation action is not always reliable, and the method using a rubber belt not only complicates the structure, but also has the limitation that the contact area between the belt and the non-rotating member cannot be made that large. In the case of the method of press-welding, a drawback appears to be that it requires installation and adjustment of a weak spring force. In addition, with the fixed roller method, when two sheets are fed out, they are almost separated, but when three or more n sheets are fed out, only the one sheet that contacts the fixed roller is separated, and the remaining n-1 sheets are fed. Paper may be used. The reason for this is that when the rollers contact each other, there is only one chance of separation due to line contact.

It is an object of the present invention to provide a paper feed double feed prevention device with a simple structure that eliminates these drawbacks.

The present invention utilizes the advantages of the conventional method of press-contacting rubber pieces and fixed roller method, and combines them to actively increase the contact width (area) between the drive roller and the conveyance blocking member, thereby making it easier to This is an attempt to give more chances to separate the transfer sheets that have been fed in duplicate.

Hereinafter, the present invention will be explained with reference to the illustrated embodiments.

FIG. 1 is a diagram showing the entire paper feeding device, and FIG. 2 is an enlarged view of the double-feed prevention device. In the figure, 1 is a large number of sheets of transfer paper stacked in a cassette without reference numerals, and 2 is a lifting arm biased by a spring or the like (not shown), one end of which is stored in the cassette. The transfer paper is urged upward through a partition plate (no reference numerals). Reference numeral 3 denotes a feed roller, which is in contact with the transfer paper 1 with enough pressure to feed out at least one sheet of transfer paper. 4 and 5
is an element constituting the double feed prevention device according to the present application, which is placed in front of the feed roller, and is a driving (rotating) element.
A roller and an arcuate rubber plate are shown respectively, and the relationship between the roller and the transfer paper is as follows: μ ₁ is the coefficient of static friction between the drive roller 4 and the transfer paper, μ ₂ is the coefficient of static friction between the rubber plate 5 and the transfer paper, and the relationship between the roller and the transfer paper is as follows: If the coefficient of static friction between papers is μ ₃ , the material of the rubber is appropriately selected so that μ ₁ > μ ₂ > μ ₃ , and a sufficient contact width (area) between the drive roller 4 and the rubber plate 5 is obtained. It is set by auxiliary means (not shown). As for the rubber plate 5, experimental results showed that urethane rubber with a thickness of 1 mm (width 30 mm) and a rubber hardness of 60° had a great effect on handling performance. 6 is a rubber plate 5
The support member 7 is a partially cut-out cylindrical support member for fixing by gluing. The material for the conveyance roller is, for example, neoprene rubber with a rubber hardness of 40° and a rough surface.

If it is desired to replace the entire pile of paper due to changes in paper size, etc., a lever (not shown) is used to release the contact between the drive roller 4 and the rubber plate 5, thereby preventing the contact between the drive roller and the rubber plate. Transfer paper can be easily taken out.

Next, its effect will be explained. First, one or more sheets of transfer paper are guided by the feed roller 3 to the double-feed prevention device. In this case, multiple sheets of transfer paper may be sent out, for example, if the accumulated transfer paper is not removed sufficiently, or if abnormal pressure is applied between the delivery roller and the stacked transfer paper. .
When a plurality of sheets of transfer paper are sent, the double-feed prevention device first removes the lowest transfer paper (closest to the rubber plate) by the rubber plate 5, since μ ₂ > μ ₃ .
The rest moves forward, and when the next transfer paper comes into contact with the rubber plate 5, it is separated again, and finally, since μ ₁ >μ ₂ , only the uppermost transfer paper escapes from there and is fed. The drive roller 4 has a one-way clutch between it and the drive shaft, and if the drive is stopped when the conveyance roller 7 applies conveyance force to the transfer paper, the second and subsequent sheets of transfer paper continue. It does not move out and remains in that state until the next rotational force is applied.

As described above, by using the present invention, a double feed prevention device that is simple and greatly improves reliability has been realized.

It should be noted that the illustrated embodiments are merely examples, and the present invention is not limited thereto, and modifications within the range of the gist of the present invention are included in the present invention. For example, the present invention can be used not only for paper feeding devices for copy paper, but also for a wide variety of paper feeding devices.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the entire paper feeding device, and FIG. 2 is an enlarged sectional view of the double-feed prevention device. 1... Deposition transfer paper, 2... Lifting arm, 3...
...Feeding roller, 4... Drive roller, 5... Rubber plate, 6... Support member, 7... Conveyance roller.

Claims (1)

[Scope of utility model registration request] A conveyance prevention member composed of a solid support member and an elastic member integrally provided so that at least a part of the support member has a gap with respect to the support member surface and has a curved surface. The conveyance blocking member is fixed by pressing the surface of the elastic member corresponding to the gap against the surface of a rotating roller provided on the movement path of the transfer paper, and using the gap, the elastic member is moved according to the surface shape of the rotating roller. A double feed prevention device for copying machines, etc., which is made by deforming the paper into a concave shape.