JPH0238231A - Paper feeding device - Google Patents

Abstract

PURPOSE:To prevent paper sheet from being overlappingly sent with high probability by using a separating claw and a separator with a torque limiter in a paper feeder. CONSTITUTION:A paper feeding roller 1 rotates at first when paper is fed. The paper sheet makes a loop between a separating claw 11 and the roller 1. The sheets are almost completely separated here. After the sheet is completely separated by the separating claw 11, it is sent between a separating roller 3 and a carrier roller 2. Since friction between the paper sheet and the roller is larger than torque of a torque limiter, the separating roller 3 rotates in a direction of fed paper.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a paper feeding device installed in an image forming apparatus.

[Conventional technology]

Conventionally, a paper feeding device installed in an image forming apparatus includes a paper feeding roller 1. as shown in FIG. Conveyance roller 29 Separation roller 3
．． Lifter plate 5. It has a paper feed guide 4. The user loads the paper P on the lifter plate 5, and the lifter plate 5 loads the paper P when feeding the paper.
It will rise so that the paper surface is at the optimal position for paper feeding. First, the paper feed roller l rotates. Then, as shown in Fig. 7, when the force exerted by the paper feed roller on the paper is F, the uppermost paper P has a force of μrpXF (μrp is the coefficient of friction between the paper and the roller) from the paper feed roller 1. A force of magnitude is applied in the paper feeding direction, and from the second sheet of paper P2 from the top in the opposite direction, μppXF(μ
pp is the friction coefficient between the top paper P1 and the second paper P2)
The force is applied. Here μrp > μpp. The second paper P2 has μppF in the paper feeding direction from the top paper P1.
The force of μm:l is applied from the third sheet of paper in the opposite direction to the paper feeding direction.
Receives the force of p' F. (μpp is the second paper P2
and the third sheet of paper P3) where μpp”μpp
Then, the force applied to P2 becomes 0, and the third sheet of paper P
It is fixed for 3. If the friction coefficients of the sheets stacked in this manner are the same, the sheets will be fed without double feeding.

Next, as shown in FIG. 8, the nth sheet of paper P from the top and the (n+1)th sheet of paper P from the top. Friction coefficient μpp with +1
However, Pl and P2. P2 and P3. P3 and P4 +...
, p, -1 and P. Unlike the friction coefficient μpp, μpp>μ
If pp, there is a slip plane between Pn and Pn++' P l + P 21 ”' PTI-1, Pn
will be shipped in duplicate.

As shown in FIG. 9, the double-fed sheets are returned in order from the lowest sheet Pn by the separation roller 3. Due to the action of a torque limiter (not shown), the separation roller 3 rotates in the paper feed direction as shown in Figure 2 when one sheet of paper is inserted, and as shown in Figure 3 when multiple sheets of paper are input. It is set to rotate in the return direction as shown in the figure.

The above is a separation method using separation rollers, but there is another separation method using separation claws.

As shown in FIG. 4, a separating claw 11 is provided, and a loop is formed between the claw and the paper feed roller to separate the uppermost paper.

[Problem that the invention is trying to solve] However,
In the conventional separation method using separation rollers, a large number of sheets of paper enter and the paper is returned one by one from the bottom, so it takes time to return all the papers starting from the second sheet from the top, resulting in double feeding. Sometimes. In addition, the separation method using separation claws can be used when there is a large difference in the coefficient of friction between paper
As shown in FIG. 5, a small number of sheets may be fed multiple times.

In addition, since a plurality of sheets of paper always enter the separation roller portion, the separation roller constantly rotates forward and backward, resulting in severe wear of the separation roller.

[Means for Solving the Problems (and Effects)] According to the present invention, since the torque limiter separation is performed after the separating claws have separated to some extent, double feeding can be prevented with a fairly high probability.

〔Example〕

FIG. 1 shows a first embodiment of the present invention, in which numeral 1 is a paper feed roller located above paper P and feeds paper P, 11 is a separation claw for separating paper, and 2 1 is a conveyance roller for feeding the fed paper; 3 is a separating roller that can be rotated forward and backward by the action of a torque limiter (not shown); and 5 is a roller that moves up and down to optimize the paper surface height when feeding paper. The sliding lid plate and 4 are guide plates.

When feeding paper, the paper feed roller 1 first rotates. Then, the paper forms a loop between the separating claw 11 and the row 51 as shown in FIG. Here, the paper is almost separated. When the paper is completely separated by the separation claw 11, it is sent between the separation roller 3 and the conveyance roller 2 as shown in FIG. (not shown) and rotates in the paper feeding direction. If the difference in μ between the two papers is too large, the separating claw may not be able to completely prevent it. At that time, compared to when there is no separation claw, fewer sheets of paper are fed in duplicate and sent between the separation roller 3 and the conveyance roller 2, and the separation roller 3 rotates in the direction of returning the paper as shown in FIG.
Put back the paper one by one starting from the bottom.

〔Effect of the invention〕

As explained above, the paper feeder has a separation claw and a torque limiter.
By using the separating means, it was possible to prevent electrical transfer with a fairly high probability, and also to suppress the wear of the separating roller.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the paper feed section in which the present invention is implemented, Figs. 2 and 3 are explanations of torque limiter separation, Figs. 4 and 5 are explanations of die separation, and Fig. 6 is a conventional paper feed section. A cross-sectional view of the paper section, Figures 7 and 8 are explanations of electrical transmission, and Figure 9 is an explanation of paper feeding and separation using the conventional paper feeding section.
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・Paper feed roller 2 ・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・Conveyance roller separation roller separation claw

Claims (1)

[Claims] A separation claw for separating the paper is located at the top end of the stacked papers in a paper feeding device attached to an image forming apparatus, and a separation means is provided using a torque limiter located behind the separation claw in the paper feeding direction. A paper feeding device characterized by: