JPS59228677A - Electrostatic charging device of electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To greatly reduce fatigue of an electrically conductive brush and to prevent deterioration of chargeability characteristics by providing a charging roller optionally in or out of contact with the body to be charged, and bringing the roller into contact with said body by using a centrifugal force generated with rotation of the roller. CONSTITUTION:When a driving shaft 3 starts rotation in order to charge the body 1 to be charged, balls placed in the inside of each rotor 5a, 5b are given centrifugal forces, and these forces are directed in the direction of arrow (a) against springs for comprssing each rotor 5a, 5b and mounted movably along the driving shaft 3. The shaft 3 is bent toward the body 1 together with a charging roller 2 by the action of both inclined faces 8a of the guide members 8. As a result, the conductive brush 2a of the roller 2 comes into contact with the surface of the body 1 to charge it. When copying is finished and the shaft 3 is stopped, the centrifugal forces disappear, the rotors 5a, 5b are moved outward, and the shaft 3 and the roller 2 are withdrawn apart from the body 1 by the actions of the springs 7 and their own weights.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates primarily to a charging device for an electronic copying machine used to charge a charged object such as a photoreceptor.

PRIOR ART A corona charger has been used as a charging device for conventional electronic copying machines.However, since the corona charger uses a high-voltage power supply, it is not only dangerous, but also generates ozone when charging, which can cause damage to equipment. be. Therefore, charging devices using conductive brushes are being developed as an alternative to the corona charger, but in conventional charging devices, the conductive brush of the charging roller is always in contact with the photoreceptor even when the object to be charged is stopped. As a result, there were problems such as the conductive brush becoming flattened and the charging characteristics deteriorating.

Purpose of the Invention The present invention was made for the purpose of solving such problems, and it provides a charging device for an electronic copying machine in which the charging roller is moved away from the object to be charged when it stops, thereby preventing the deterioration of charging characteristics. This is what we are trying to prevent.

Components of the Invention An electronic copying machine is provided with a charging roller that can be moved toward and away from a charged object, and a charging roller is brought into contact with the charged object using centrifugal force generated as the charging roller rotates. In the charging device, since the conductive brush of the charging roller is separated from the object to be charged when close-up photography is stopped, sagging of the conductive brush can be greatly reduced.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to the drawings.
In the figure, 1 is a charged object such as a photoreceptor installed in an electronic copying machine (not shown), and 2 is a charging roller installed below this charged object 1, parallel to the axis of the charged object 1. It has a drive shaft 3 in the direction. Both ends of the drive shaft 3 are supported by guide holes 4 formed in a frame, etc., and the drive shaft 3 is movable along the guide holes 4 to direct the charged object 1 towards and away from it. A pair on each side of 3,
A total of four substantially dish-shaped rotating bodies 5 are provided so as to face each other. Among these rotating bodies 5, the outer rotating body 5α is fixed to the drive shaft 3, and the inner rotating body 5b
is attached to be movable in the axial direction of the drive shaft 3, and a plurality of balls 6 are housed between these rotating bodies 5α and 5b.

Further, between the end face of the core body 2b of the charging roller 2, on which a large number of conductive brushes 2α are implanted on the circumferential surface, and the rotary body 5b located inside, a compression spring 7 is provided which biases the rotary body 5h outward. The back surface of the rotating body 5b, which is fitted into the drive shaft 3 and located inside, is in contact with the inclined surface 8α of the guide member 8, and is rotated by the centrifugal force acting on the ball 6. When the body 5b is moved in the direction of the arrow α, the back surface of the rotating body 5h is guided by the inclined surface 8α, and the drive shaft 3 and charging roller 2 are configured to protrude toward the charged body i side.

Effects of the Invention Since the present invention has been described in detail above, when the drive shaft 3 starts rotating to charge the charged object I, each rotating body 5a
, 5b, a centrifugal force is generated in the ball 6, and the ball 6 is moved in the direction of the arrow α against the rotary compression spring 7 provided movably with respect to the drive shaft 3. As a result, the rotating body 5
Since the drive shaft 3 is pushed out together with the charging roller 2 toward the charged object 1 side by the inclined surface 8α of the guide member 8 that comes into contact with the back surface of the charging roller 2, the conductive brush 2α of the charging roller 2 When it comes into contact with a surface, it becomes electrically charged. Furthermore, when the copying is completed and the drive shaft 3 is stopped, the centrifugal force acting on the ball 6 also disappears, so the rotation body 5b is moved outward by the action of the compression spring 7, which causes the drive shaft 3 and the charging roller 2 to Since the conductive brush 2α of the charging roller 2 is moved away from the charged object 1 due to its own weight, urging means, etc., the conductive brush 2α of the charging roller 2 is pushed away from the charged object 1 and stops. As a result, the sagging appearance of the conductive brush 2 (Z) is greatly reduced compared to the conventional solid line (indicated by ri) even after long-term use, as shown by the broken line (6) in Accordingly, the deterioration of charging characteristics is also reduced.Furthermore, since the time during which the conductive brush 2α is in contact with the charged object 1 is shortened, the wear of the conductive brush 2α is also reduced, and the life of the charging roller 2 is extended. At the same time as it stretches, toner etc. attached to the surface of the charged object 1 attaches to the conductive brush 2cL side, and the conductive brush 2α
The risk of contamination of the liquid can be greatly reduced compared to conventional liquids that are constantly in liquid state.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic groove diagram, and FIG. 2 is a diagram showing the relationship between the number of copies and the amount of sagging. 1 is an object to be charged, 2 is a charging roller, and 2α is a conductive brush. Applicant Fuji Xerox Co., Ltd. Agent Patent Attorney Masaaki Yonehara Patent Attorney Tadashi Hamamoto

Claims (1)

[Claims] A conductive brush 2cL is placed on the surface of the charged object 1 in a contact manner,
In the device for charging the charged object 1, a charging roller 2 having the conductive brush 2α is movably supported in the direction of contact with the charged object 1, and a centrifugal force generated as the charging roller 2 rotates. A charging device for an electronic copying machine, in which a charging roller 2 is advanced to a position where a conductive brush 2α comes into contact with an object 1 to be charged.