JPS6152470B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transfer material separation device for an electrophotographic copying machine using a drum type transfer method, and an object of the present invention is to prevent wrinkles from forming on the transfer material during separation operation and to perform separation smoothly. .

The applicant first stretched the separation belt 3 from the front of the transfer position T toward the transfer position T.
A separation roller 2 is provided immediately after the separation belt 3 is turned in a direction away from the photosensitive drum 1,
A transfer material separation device has been proposed in which the side edge of the transfer material 4 sent to the transfer position T is guided to the separation roller 2 and separated by the separation belt 3 without contacting the photosensitive drum 1. In FIG. 1, 5 is a transfer charger;
Reference numerals 6 and 7 indicate pins that connect or connect both ends of the separation belt (or a wire may be used) 3, and 8 indicates a guide roller.

In the above configuration, the separation roller 2 is made of a material with a large friction coefficient such as rubber, and the circumferential speed V of the separation roller is made considerably higher than the circumferential speed v of the photosensitive drum 1 (V>v), and the transfer material 4 is The paper is separated by slipping against a separation roller 2. However, if the electrostatic adsorption force between the drum 1 and the transfer material 4 or the pressing force of the transfer roller is weak, the portion 4' of the transfer material sandwiched between the separation belt 3 and the separation roller 2 will come first, and the entire transfer material will be This causes tilt and transfer misalignment.
On the other hand, if the electrostatic adsorption force or pressure is strong, the holding force between the separation roller 2 and separation belt 3 against the side edge of the transfer material is small, resulting in poor separation such as portion 4' of the transfer material 4 coming off from the separation roller 2. It is easy to cause The latter problem can be relatively easily solved by using a material having a large friction coefficient, such as rubber, for the separation roller 2, but on the other hand, the former transfer deviation occurs. This phenomenon is particularly noticeable when the adsorption force of the transfer material to the drum is weak, such as in corona transfer.

On the other hand, the resolution of an electrophotographic copying machine is generally said to be 5 lines (5 lines can be seen within 1 m/m). That is, it is necessary that the 1/10 m/m line does not overlap the adjacent 1/10 m/m white line. Therefore, if the length of the contact arc of the transfer material 4 with the photosensitive drum 1 is t, the time required for passing through l·l, then 0.1 m/m during this time.
It is necessary that no movement error (shift) occurs.

Here, V=l+0.1/t v=l/t V/v=1+0.1/l From this relationship, to obtain the above resolution, the circumferential speed V of the separation roller 2 is the circumferential speed V of the photosensitive drum 1. It is theoretically clear that the speed should not be increased by more than 0.1/l x 100%.

The present invention is designed to ensure the separation effect by causing transfer deviation within a permissible range under such conditions and preventing slippage of the transfer material between the separation belt and the separation roller.

That is, where R: the radius of the photosensitive drum 1, N: the rotation speed of the drum 1, r: the radius of the separation roller 2, and n: the rotation speed of the roller 2, v=2πRN, V
= 2πrn, so under the condition that V<(1+0.1/l)v, that is, 2πrn<2(1+0.1/l)πRN, the transfer material between separation roller 2 and separation roller 3 is within the resolving power range. It is possible to apply the necessary holding force to the portion 4' and smoothly separate it.

However, even if the above conditions are met, if the gap C between the transfer material portion 4' and the surface of the photosensitive drum 1 is large, as can be seen from FIG.
The area near the boundary 4'' between the photosensitive drum and the transfer material that is in contact with the surface of the photosensitive drum appears to be attracted, and the speed of the 4' portion of the transfer material is high, causing wrinkles and kinks 4 at the area 4'' near the boundary. . To prevent this, the gap C must be made as small as possible.

In order to prevent the above-mentioned wrinkles and twists 4, the circumferential speed of the separation roller 2 is V2π(R+
C)N, so the above V<(1
+0.1/l)v is as follows: 2π(R+C)N<2(1+0.1/l)πRN ∴ C<0.1/lR. That is, by setting the gap C to be less than or equal to the value obtained by dividing 1/10 of the radius R of the photosensitive drum 1 by the arc length l of the contact of the transfer material 4 with the photosensitive drum 1, the above-mentioned wrinkles and kinks can be prevented from occurring in the transfer material. Separation is performed extremely smoothly with no transfer misalignment that poses a practical problem.

[Brief explanation of the drawing]

FIG. 1 is a side view of the device of the present invention, FIG. 2 is a sectional view taken along the line AA in FIG. 1, and FIG. 3 is a top view of FIG. 1 is a photosensitive drum, 2 is a separation roller, 3 is a separation belt, 4 is a transfer material, and 5 is a transfer charger.

Claims (1)

[Claims] 1. A separation belt is stretched from in front of the transfer position of the photosensitive drum toward the transfer position, and the circumferential speed v of the photosensitive drum is set immediately after the transfer position and at a position where the separation belt is separated from the photosensitive drum. A separation roller rotating at a faster circumferential speed V is provided to turn the separation belt in a direction away from the photosensitive drum, so that the side edge of the transfer material sent to the transfer position is not brought into contact with the photosensitive drum by the separation roller. In the transfer material separation device of an electrophotographic copying machine that conducts separation by guiding the photosensitive drum, the radius of the photosensitive drum is R, the number of rotations of the photosensitive drum is N, the distance between the separation roller and the photosensitive drum is C, and the transfer material is in contact with the photosensitive drum. A transfer material separation device for an electrophotographic copying machine, characterized in that, where the arc length is l, the following relationships are satisfied: V<2π(R+C)N and C<0.1R/l.