JPH0221585B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present 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, corona chargers using corotrons have been widely used as charging devices for electronic copying machines.
However, since this corona charger uses a discharge phenomenon, it has problems such as generating ozone, polluting the atmosphere, and deteriorating the photoreceptor and discharge wire during discharge. In order to improve this problem, a brush charging device as shown in FIG. 1 has recently been proposed in which a large number of conductive brushes b are embedded on the surface of a roll core. The above-mentioned brush charging device is rotated in a fixed direction with a DC power supply c of 500 to 2 KV applied, and the tip of the conductive brush b is brought into contact with the surface of the photoconductor d, so that the surface of the photoconductor d is uniformly coated. Since it is electrically charged and uses contact charging, problems such as ozone generation and photoreceptor deterioration due to discharge phenomena are eliminated.

Further, the conductive brush b used in the brush charging device is required to have uniform charging and to not reduce the length of the bristles even after long-term use. However, in the conventional conductive brush B, conductive fibers made of bundles of 10 to 200 filaments with a single yarn denier of 1.5 to 20 d are implanted on the surface of a base fabric formed into a strip of insulating fibers such as rayon or polyester. Because the fabric is wound spirally around a roll core, there is a gap between the conductive brushes b as shown in Figure 2 at the winding e of each base fabric, making it impossible to charge the surface of the photoreceptor d uniformly. There was a problem.

OBJECTS OF THE INVENTION The present invention provides a brush charging device for a copying machine that does not create a gap between conductive brushes in the wound portion of a base fabric, thereby making it possible to uniformly charge a photoreceptor.

Structure of the Invention A conductive brush is formed by planting small-diameter fibers on both side edges of a strip-shaped base fabric, and large-diameter fibers between these small-diameter fibers, and then spirally winding these around a roll core. This is a brush charging device for a copying machine that has a brush roll, and since there are weak and thin fibers in the seam of the base fabric, there is no gap between the joints of the base fabric during charging. It becomes possible to uniformly charge the surface of the photoreceptor.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to the drawing shown in FIG. Conductive fiber 2 on the surface of
has been planted. The conductive fibers 2 are made of composite fibers in which conductive particles such as carbon are dispersed in rayon or acrylic, for example, and thin fibers 2a with a fiber diameter of about 10 μm are attached to both sides of the base fabric 1, and these fine fibers are The conductive brush 3 is constructed by uniformly planting large-diameter fibers 2b having a fiber diameter of about 40 μm between the fibers 2a.

The conductive brush 3 is wound spirally on the surface of the roll core 4a without creating a gap at the seam to form a brush roll 4 as shown in FIG. Since the small diameter fibers 2a with weak stiffness are present in the seam portion, when the photoreceptor 5 is brought into contact with the conductive fibers 2a to be charged, the small diameter fibers 2a with weak stiffness fill the gaps between the conductive fibers 2 that occur at the joints of the base fabric 1. As shown in the figure, since the photoreceptor 5 can be uniformly charged, the thick fibers 2b are used in other parts, so that the pile does not decrease during long-term use.

Effects of the Invention As described in detail above, the present invention has a conductive brush in which small-diameter fibers are implanted on both side edges of a base fabric and large-diameter fibers are implanted in other parts, and the conductive brush is wound spirally around a roll core. Because of the roll structure, when the photoreceptor is charged, the small diameter fibers provided on both sides of the base fabric fill the gaps that occur at the joints of the base fabric, making it possible to charge the photoreceptor uniformly, and also to charge the other parts. Since the brush roll uses large diameter fibers, the length of the bristles does not decrease even after long-term use, which also improves the durability of the brush roll.

[Brief explanation of drawings]

1 and 2 are explanatory diagrams of a conventional brush roll, FIG. 3 is an explanatory diagram of a brush roll according to an embodiment of the present invention, and FIG. 4 is a plan view of a conductive brush.
FIG. 5 and FIG. 6 are action explanatory diagrams. 1 is a base fabric, 2a is a small diameter fiber, 2b is a large diameter fiber,
3 is a conductive brush, 4 is a brush roll, 4a is a roll core, and 5 is a photoreceptor.

Claims (1)

[Claims] 1. In a device that charges the photoreceptor 5 by bringing the conductive brush 3 into contact with the surface of the photoreceptor 5, the conductive brush 3 is attached with small diameter fibers 2 on both side edges of the strip-shaped base fabric 1.
a, and large diameter fibers 2 between these small diameter fibers 2a.
A brush charging device for a copying machine, in which a brush roll 4 is formed by implanting a conductive brush 3 and a brush roll 4 by spirally winding the conductive brush 3 around a roll core 4a.