JPH0743981A - Corona electrifier for electrophotographic device - Google Patents

Abstract

PURPOSE:To increase a corona current flowing through a photoreceptor by arranging a shield plate between respective wires and grounding the plate. CONSTITUTION:The electric discharge wires 2 and a metallic shield plate 3 are provided and the plate 3 is provided so as to surround three sides of the plural wires 2 arranged in parallel. Besides, the shield plate 4 is arranged between the respective wires 2. Then, the voltage of several kV is impressed on the wires 2 and the plate 4 is maintained to be at ground potential. When the voltage impressed on the wire 2 is gradually increased and an electric field on the surface of the wire 2 arrives at a discharge start electric field, electric discharge is generated. When the voltage is increased more, an electric discharge current is increased. By increasing the number of wires 2 and making a distance between the wire 2 and the plate 4 short, the electric discharge is apt to generate to obtain more corona currents even in the case of the size equal to that of a corona electrifier shown by figure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corona charger for an electrophotographic apparatus.

[0002]

2. Description of the Related Art FIG. 5 is a perspective view showing a corona charger of a generally known electrophotographic apparatus. A discharge wire 2 is provided so as to face the photoconductor 1, and a metal shield plate 3 is provided so as to surround three faces of the discharge wire 2 other than the photoconductor-facing face. Further, in an electrophotographic apparatus for high speed printing, a corona charger in which a plurality of discharge wires 2 are arranged in parallel in a shield plate 3 is used as shown in the sectional view of FIG.

[0003]

In the corona charger used in the electrophotographic apparatus for high speed printing, a plurality of discharge wires 2 are arranged in parallel in the shield plate 3 and flow into the photoconductor as described above. I was trying to increase the corona current. Therefore, there is a problem that the corona charger becomes large.

Therefore, an object of the present invention is to provide a corona charger which is small in size and capable of obtaining a large corona current.

[0005]

In the corona charger of an electrophotographic apparatus, which comprises a plurality of wires arranged in parallel and a shield plate surrounding the wires, a shield plate is arranged between the wires. In addition, it is achieved by grounding the shield plate between the wires.

[0006]

According to the above structure, by disposing the shield plate between the wires and grounding the shield plate between the wires, the electric field between the wires and the shield plate is increased, and the electric field on the wire surface is also high. Is likely to occur and a large corona current can be obtained.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the corona charger according to the present invention. Reference numeral 2 is a discharge wire, and 3 is a metal shield plate. A shield plate 3 is provided so as to surround three sides of the plurality of discharge wires 2 arranged in parallel, and a shield plate 4 is provided between the respective discharge wires 2.
Are arranged. A voltage of several kV is applied to the discharge wire 2, and the shield plate 4 is kept at the ground potential. When the voltage applied to the discharge wire 2 is gradually increased, discharge occurs when the electric field on the surface of the discharge wire 2 reaches the discharge start electric field. Furthermore, when the voltage is increased, the discharge current increases.

Further, as shown in FIG. 2, even if the size is the same as that of the corona charger of FIG. 1, by increasing the number of discharge wires 2 and decreasing the distance between the discharge wires 2 and the shield plate 4, the discharge is generated. It is more likely to occur, and more corona current can be obtained.

5 and 6 are sectional views showing another embodiment of the corona charger according to the present invention. In FIG. 5, the shield plate 4 arranged between the respective discharge wires 2 is
It is a little shorter than the shield plates 3 at both ends surrounding the discharge wire 2. According to the above configuration, it is possible to prevent the lateral spread of the corona current from being obstructed.
Further, in FIG. 6, the tip of the shield plate 4 arranged between the discharge wires 2 is formed of plastic 5. According to the above configuration, since the surface potential of the plastic 5 rises, the corona current easily wraps around and flows into the photoconductor.

[0010]

According to the present invention, since the shield plate is arranged between the wires and the shield plate between the wires is grounded, the corona current flowing into the photoconductor can be increased.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a corona charger according to the present invention.

FIG. 2 is a sectional view showing another embodiment of the corona charger according to the present invention.

FIG. 3 is a sectional view showing another embodiment of the corona charger according to the present invention.

FIG. 4 is a sectional view showing another embodiment of the corona charger according to the present invention.

FIG. 5 is a perspective view showing a corona charger according to the related art.

FIG. 6 is a cross-sectional view showing a corona charger according to the related art.

[Explanation of symbols]

1 is a photoconductor, 2 is a discharge wire, 3 and 4 are shield plates, 5
Is plastic.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masanori Nakamura 1060 Takeda, Katsuta City, Ibaraki Prefecture Hitachi Koki Co., Ltd.

Claims (3)

[Claims] 1. A corona charger for an electrophotographic apparatus comprising a plurality of wires arranged in parallel and a shield plate surrounding the wires, wherein a shield plate is arranged between the wires and a shield between the wires is provided. A corona charger for an electrophotographic device, characterized in that the plate is grounded. 2. A corona charger for an electrophotographic apparatus according to claim 1, wherein the shield plate between the wires is shorter than the shield plates at both ends surrounding the wire. 3. A corona charger for an electrophotographic apparatus according to claim 1, wherein the tip of the shield plate between the wires is formed of plastic.