JPS59204859A - Electrostatically charging device on brush of copying machine - Google Patents

Abstract

PURPOSE:To prevent deterioration of a photosensitive body and sagging of a conductive brush by making a tracking roll of both ends of the brush contact by pressing to a cam having a shunting part of the end part of the photosensitive body, and shunting the brush from the photosensitive body when copying stops. CONSTITUTION:A tracking roll 5 provideed on both ends of a conductive brush 2 is made to contact by pressing to a cam 7 having a shunting part 7a fixed to the end part of a photosensitive body 1. Accordingly, at the time of copying, the roll 5 contacts by pressing to a core circle part of the cam 7, the brush 2 contacts with the photosensitive body 1, and electrostatical charging is executed, but when copying stops, the shunting part 7a is rotated to a position of the brush 2, the roll 5 runs on the shunting part 7a, and the brush 2 is shunted from the photosensitive body 1. Therefore, it is prevented that the brush 2 contacts with the photosensitive body 1 for a long period of time, deterioration of the surface of the photosensitive body 1 and sagging of the brush are prevented, and also deterioration of electrostatical charging characteristics is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a brush charging device for a copying machine that charges the surface of a photoreceptor using a conductive brush.

Prior Art Conventionally, corotrons using discharge wires such as tungsten are often used as charging devices for electronic copying machines.
Ozone is generated during discharge, and toner and other substances adhere to the discharge wire, deteriorating the charging characteristics, which requires periodic cleaning and other problems that require a lot of effort for maintenance and inspection.

To solve this problem, a brush charging device using a conductive brush has recently been proposed. As shown in Figure 1, this brush charging device charges the photoconductor by bringing the conductive brush α into contact with the photoconductor, so there is little damage to the photoconductor surface due to ozone generation due to discharge or spark discharge, and it is easy to maintain. It has characteristics such as 'easy to use'.

However, since the conductive brush α is in contact with the surface of the photoconductor even when copying is paused, the surface of the photoconductor may deteriorate or the conductive brush α may become damaged due to external force applied to the conductive brush α (see Fig. 2). As shown in Figure 2, there were problems such as deterioration of charging characteristics due to stagnation.

Purpose of the Invention The present invention has been made for the purpose of improving the above-mentioned problems.The conductive brush is separated from the surface of the photoreceptor when copying is stopped, thereby preventing the surface of the photoreceptor and the conductive brush from deteriorating. The present invention aims to provide a brush charging device for a copying machine.

Structure of the Invention A tocking roll that contacts a cam provided at the end of the photoreceptor is provided at the shaft end of the conductive brush that is supported movably in the direction toward and away from the photoreceptor, thereby making contact between the photoreceptor and the conductive brush. In addition, by providing a retraction cam part that separates the conductive brush from the photoconductor at the part that stops at the position of the conductive brush when copying is paused, long-term contact between the photoconductor and the conductive brush can be prevented. A brush charging device for a copier.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to the drawings shown in FIG. 3 and below. In the figure, l is the photoreceptor of the electronic copying machine,
A brush charging device consisting of a conductive brush 2 is provided around the photoreceptor 10, which has a drum shape.

The conductive brush 2 has a large number of brush bodies 2h made of conductive fibers planted on the surface of a roll 2α.
As the brush body 2b rotates, the tip of the brush body 2b comes into contact with the surface of the photoreceptor 1, so that the surface of the photoreceptor I is uniformly charged.

On the other hand, both ends of a shaft 2C protruding from both ends of the roll 2α of the conductive plastic 2 are rotatably supported at the tips of a pair of arms 4 whose proximal ends are rotatably supported by a support shaft 3. A tracking roll 5 is provided at the tip of a shaft 2C that is rotated in a fixed direction by a drive system (not shown) and that protrudes from the roll 2α, and attaches the tip side of the arm 4 to the photoreceptor 1 side. The photoreceptor 1 is pressed against the curved surface of a cam 7 provided at both ends of the photoreceptor 1 by a biasing means 6 such as a tension spring.

The cam 7 has a center circle with a larger diameter than the outer periphery of the photoreceptor 1, and the tracking roll 5 is attached to the photoreceptor 1 at a portion where the cam 7 stops at the position of the conductive brush 2 when the copying operation is stopped.
A protruding retraction portion 7α that presses in the direction of separating from the retracting portion 7α is provided in a protruding manner.

That is, during the copying operation, the tracking roll 5 provided on the shaft 2C of the conductive brush 2 is in contact with the center circle of the cam 7 as shown in FIG.
The contact state of the cam 7 is maintained, and the cam 7 is kept in contact with the cam 7 when copying is stopped.
As shown in FIG. 5(B), the tracking roll 5 rides on the retracted portion 7α, separating the conductive brush 2 from the photoreceptor 1, so that the photoreceptor 1 and the conductive brush 2 are out of contact with each other.

Effects of the Invention As described in detail above, the present invention utilizes the central circular portions of the cams 7 provided at both ends of the photoreceptor 1 to bring a conductive brush into contact with the surface of the photoreceptor 10, and when copying is stopped, a protruding brush is brought into contact with the surface of the photoreceptor 10. Evacuation section 7α
Since the conductive brush 2 is spaced apart from the surface of the photoconductor 1, the surface of the photoconductor 1 may deteriorate due to long-term contact between the photoconductor 1 and the conductive brush 2, and the conductive brush 2 may become worn out. This makes it possible to prevent the charging characteristics from deteriorating.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams showing defects in a conventional brush charging device, and FIG. 3 is a side view showing an embodiment of the present invention.
FIG. 4 is a front view of the same, and FIGS. 5(a) and 5(b) are action explanatory views. 1 is a photoreceptor, 2 is a conductive brush, 2C is a shaft, 5 is a tracking roll, 7 is a cam, and 7α is a retraction part. Applicant Fuji Xerox Co., Ltd. Agent Patent Attorney Masaaki Yonehara Patent Attorney Tadashi Hamamoto

Claims (1)

[Claims] In a device that uniformly charges the surface of the photoreceptor 1 with a conductive brush 2, the shaft 2C of the conductive brush 2 is connected to the photoreceptor 1.
A cam 7 is supported movably in the approaching and separating directions, and a tracking roll 5 is provided on the shaft 2C, and this tracking roll 5 is attached to the end of the photoreceptor 1 by means of a biasing means 6.
A copying machine comprising a retraction portion 7α that presses the tracking roll 5 in the direction of separation from the photoreceptor 1 at a portion of the cam 7 that stops at the position of the conductive brush 2 when copying is stopped. brush charging device.