JPS60220587A - Brush charger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a brush charging device for charging a photoreceptor of an electronic copying machine using a conductive brush.

Conventional technology As a device for charging the photoreceptor of an electronic copying machine, a corotron using a discharge wire such as a Tanges wire is known. Since it has a simple structure, it is widely used as a charging device.

However, with this corotron, ozone is generated during discharge, and foreign matter such as toner adheres to the discharge wire. Since the characteristics deteriorate, it is necessary to periodically clean it, and each maintenance inspection requires a lot of effort.

In particular, when charging organic photoreceptors, acid photoreceptors, zinc photoreceptors, etc., the above-mentioned problems become extremely serious because they are negatively charged.

As a charging device for solving this problem, a brush charging device is known in which a conductive brush is brought into contact with a photoreceptor to charge the photoreceptor.

This brush charging device has the advantages of less ozone generation due to discharge and less damage to the photoreceptor due to discharge, and easy maintenance.

However, on the other hand, since the conductive brush is charged by contacting the photoreceptor, the charging uniformity of the photoreceptor is inferior to that of the corotron.

That is, since a large number of contacts constituting the conductive film come into contact with the photoreceptor, portions that are not in contact with the contacts are not charged, resulting in streak-like charging unevenness and poor uniform charging performance.

OBJECT OF THE INVENTION It is an object of the invention to prevent streak-like charging unevenness and to improve uniform charging performance.

Structure of the invention 4 N property 7 - DC voltage and its DC voltage
0% or higher AC voltage at a frequency of 500 Hz or higher.

Embodiment FIG. 1 is a sectional view of a brush charging device, in which a conductive brush 2 is in contact with a photoreceptor 1, and this conductive brush 2 is supplied with a DC power source 3 and an AC power source 4. A pulsating voltage that is a superimposition of an AC voltage on a DC voltage is applied.

The conductive brush 2 has a resistivity of +00 to +04 Ωm, and contacts 5 made of conductive fibers with a thickness of 3 to lod are arranged on a flat plate 6 at a density of 50,000 to 200,000 pieces 1/cn6h". It is planted in

In the above-mentioned brush charging device, since the number of contacts that come into contact with each unit area of the photoreceptor is limited, streak-like charging unevenness that looks like the brush strokes tends to occur on the photoreceptor, and it is difficult to ensure uniform charging. Charging properties will be poor.

However, as described above, if a pulsating voltage obtained by superimposing an alternating current voltage on a direct current voltage is applied to the conductive brush, the above-mentioned streak-like charging unevenness can be prevented and uniform charging performance can be improved 7j.

Specifically, when the frequency of the AC voltage was set to lKz and the ratio of AC voltage to DC voltage was varied, the uniform charging property was measured.
Since a pulsating current voltage superimposed with an AC voltage of 0% or more was applied, the uniformity of charging could be improved.

Note that if the superimposed AC voltage is too high, the leakage current in the photoconductor will increase dramatically, and the dielectric breakdown of the photoconductor will occur due to spark discharge between the photoconductor and the conductive brush. The maximum voltage when multiplied by DC voltage must be within a range below the spark discharge generation voltage in the photoreceptor.

For example, in the case of a Se thread photoreceptor, the maximum applied voltage is 2500
If the voltage is around V, spark discharge will occur, so it is necessary to keep it below 2500V.

In addition, when the AC voltage was set to 300 V RM8 and the frequency was changed, the charging uniformity became as shown in 3-. From this, when the AC frequency was less than 500 Hz, charging unevenness occurred due to the father flow period. Therefore, it turns out that the frequency needs to be 500 Hz or higher.

Effects of the Invention It is possible to prevent streak-like charging unevenness from occurring on the photoreceptor and improve uniform charging performance.

[Brief explanation of the drawing]

One side shows an embodiment of the present invention, Figure 1 is a cross-sectional view of a brush charging device, and Figure 2 is a table showing the uniformity of charging depending on the ratio of AC voltage to DC voltage. The third quotient is a table showing the uniformity of charging depending on the frequency of AC voltage. 1 is photoreceptor % 2 is conductive brush. Applicant Fuji Xerox Co., Ltd. Agent Patent Attorney Masaaki Yonehara Patent Attorney Tadashi Hamamoto

Claims (1)

[Claims] In a brush charging device that charges a conductive brush 2 by contacting it with a photoreceptor 1, the conductive brush 2 is charged with an fc pulsating current voltage by superimposing an AC voltage of 20% or more of the DC voltage on a DC voltage at a frequency of 500Hz or more. A brush charging device characterized in that it applies .