JPH09197766A - Discharge electrode device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce stain on a discharge electrode by air current and to improve the durability by guiding air into a shielding case from an air introducing means formed on the back surface of the shielding case reverse to a discharge direction. SOLUTION: An air introducing means K through which air is introduced into the shielding cases 30 of an electrifying charger 3 and a transfer charger 5 are constituted on the back surfaces of the cases 30 reverse to the discharge direction. A ventilating slit 30a or a ventilating hole 30b is formed in a range showing the size equal to or above the electrode width and/or the electrode length of the discharge electrode 32. The size and the shape of the slit 30a or the hole 30b are set so that the air discharged from the case 30 by the corona discharge by the electrode 32 may be sufficiently supplied. Then, air is introduced into the case 30 from the slit 30a or the hole 30b formed on the back surface of the case 30 reverse to the discharge direction by the electrode 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge electrode device used in an image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art Conventionally, as a discharge electrode device used in an image forming apparatus such as a copying machine or a printer, a discharge electrode mounted on an insulating substrate is arranged in a shield case facing an image carrier. There is one that applies a voltage to this discharge electrode to generate a corona discharge.

[0003]

In such a discharge electrode device, even if the electrodes are contaminated by corona discharge, it is difficult to contact and clean them. Further, particularly in the case where the discharge electrode has a needle-shaped or sawtooth-shaped discharge tooth tip, the discharge electrode is easily damaged and has a problem of durability. Therefore, the discharge electrode of the discharge electrode device is prevented from being contaminated and the durability is improved. There is a need.

The present invention has been made in view of the above points, and provides a discharge electrode device capable of reducing dirt on the discharge electrode and improving durability by utilizing an air flow generated by corona discharge. Is intended.

[0005]

In order to solve the above problems and to achieve the object, the invention according to claim 1 is mounted on an insulating substrate in a shield case facing the image carrier. In the discharge electrode device for arranging a discharge electrode and applying a voltage to this discharge electrode to generate a corona discharge,
Air introducing means for guiding air into the shield case is formed on the back surface of the shield case surrounding the discharge electrode, which is opposite to the discharge direction. By the corona discharge of the discharge electrode, air is introduced into the shield case from the air introduction means formed on the back surface opposite to the discharge direction of the shield case, and this air flow can reduce the discharge electrode and improve the durability. . Further, since air is introduced into the shield case from the air introduction means formed on the back surface opposite to the discharge direction of the shield case, the air flow does not obstruct the movement of the ozone flow due to the corona discharge, and the air flow cleans the discharge electrodes. Can be reduced.

A discharge electrode device according to a second aspect of the present invention is characterized in that the discharge electrode has a needle-shaped or sawtooth-shaped discharge tooth tip. It is possible to easily reduce the dirt on the discharge electrode by the air flow and improve the durability without damaging the needle-shaped or saw-tooth-shaped discharge tooth tip of the discharge electrode.

The discharge electrode device according to a third aspect of the present invention is characterized in that the air introducing means is a ventilation slit or a ventilation hole. The air introduction means is a ventilation slit or a ventilation hole, and a simple structure using a shield case can reduce the contamination of the discharge electrode by the air flow.

A discharge electrode device according to a fourth aspect of the present invention is characterized in that the air introducing means is formed in a size range equal to or larger than the electrode width and / or the electrode length of the discharge electrode. Contamination of the discharge electrode can be effectively reduced by the air flow from the air introducing means.

A discharge electrode device according to a fifth aspect of the present invention is characterized in that a dustproof filter is attached to the air introducing means. The dust filter can reduce the contamination of the discharge electrode with a clean air flow.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an image forming apparatus to which the discharge electrode device of the present invention is applied will be described below. FIG.
2 is a cross-sectional view of the schematic configuration of the image forming apparatus, FIG. 2 is a cross-sectional view of the discharge electrode device, and FIG. 3 is a plan view of the discharge electrode device.

This embodiment exemplifies a case where the present invention is applied to a color laser printer as the image forming apparatus 1. The color laser printer according to this embodiment includes an image carrier 2 as shown in FIG. 1, and the outer peripheral surface of the image carrier 2 is irradiated with light 60 from a document (not shown) by optical scanning. . The image carrier 2 has a drum-shaped base made of a conductive material such as aluminum as a material for rotatably supporting the photoconductive layer formed of OPC (organic photoelectric body) on the peripheral surface of the base. , Is configured to be rotationally driven in the direction A in the apparatus.

The image carrier 2 is adapted to form an electrostatic latent image on the outer peripheral surface according to the image pattern of the original by exposing the charged outer peripheral surface with light from the original. . Around the image carrier 2, a charging charger 3 that charges the outer peripheral surface of the image carrier 2 to a predetermined potential, and the electrostatic latent image formed on the image carrier 2 is visualized as a toner image by the toner T. The developing unit 4, the transfer charger 5 that transfers the toner image formed on the image carrier 2 onto the transfer paper P, and the cleaner unit 6 that collects the toner T remaining on the image carrier 2.
And a charge eliminating lamp 7 for eliminating charges remaining on the image carrier 2.
And are respectively arranged.

Further, the transferred toner image is fixed onto the transfer paper P on the downstream side of the transfer paper P conveyed between the image carrier 2 and the transfer charger 5 in the carrying direction (direction B). A fixing unit 8 is provided. The charging charger 3 and the transfer charger 5 are each composed of the discharge electrode device of the present invention.

The charging charger 3 includes a shield case 30 having a U-shaped cross section, an insulating substrate 31 made of glass, epoxy, or the like supported in the shield case 30,
It is attached to the insulating substrate 31 and has a high voltage power supply +
It is composed of a stainless steel discharge electrode 32 to which Vcc is connected. The discharge electrode 32 has a needle-shaped discharge tooth tip 32a as shown in FIG. 2 (a) or a saw-tooth shaped discharge tooth tip 32b as shown in FIG. 2 (b). The charging charger 3 applies a high voltage to the discharge electrode 31 from the high voltage power supply + Vcc to generate corona discharge from the tips of the discharge teeth to charge the outer peripheral surface of the image carrier 2.

The transfer charger 5, like the charging charger 3, has a shield case 30 having a U-shaped cross section, an insulating substrate 31 made of glass or epoxy supported in the shield case 30, and an insulating substrate 31. And a discharge electrode 32 made of stainless steel to which a high voltage power source + Vcc is connected. Similar to the charger 3, the discharge electrode 32 has a needle-shaped discharge tooth tip as shown in FIG. 2A or a sawtooth-shaped discharge tooth tip as shown in FIG. 2B. The transfer charger 5 is
By applying a high voltage to the discharge electrode 32 from the high voltage power supply + Vcc, corona discharge is generated from each discharge tooth tip to charge the back surface of the transfer paper P, and the toner formed on the outer peripheral surface of the image carrier 2 is charged. The image is transferred onto the transfer paper P.

The shield case 30 of the charging charger 3 and the transfer charger 5 is provided with air introducing means K for guiding air into the shield case 30 on the back surface opposite to the discharging direction. The air introduction means K is a ventilation slit 30a as shown in FIG. 3 (a) or a ventilation hole 30b as shown in FIG. 3 (b). The ventilation slit 30a or the ventilation hole 30b has an electrode width D of the discharge electrode 32 and / or
Alternatively, the electrode length L is formed in a range larger than the size. Further, the ventilation slit 30a or the ventilation hole 30b.
The size and shape are set so that the air discharged from the inside of the shield case 30 by the corona discharge of the discharge electrode 32 can be sufficiently supplied.

Therefore, due to the corona discharge of the discharge electrode 32, the air is guided into the shield case 30 from the ventilation slits 30a or the ventilation holes 30b which are the air introducing means K formed on the back surface of the shield case 30 opposite to the discharge direction. As a result, it is possible to reduce the contamination of the discharge electrode 32 by this air flow and improve the durability. Further, since air is introduced into the shield case 30 through the ventilation slit 30a or the ventilation hole 30b formed on the back surface of the shield case 30 opposite to the discharge direction, the movement of the ozone flow due to the corona discharge is not obstructed by the air flow. It is possible to reduce the contamination of the discharge electrode 32 due to the air flow.

Further, the air introducing means K is the ventilation slit 30a or the ventilation hole 30b, and the shield case 3
With a simple structure using 0, it is possible to reduce the contamination of the discharge electrode by the air flow. Further, by forming the ventilation slits 30a or the ventilation holes 30b in a range of the electrode width D and / or the electrode length L of the discharge electrode 32 or more, the ventilation slits 30a or the ventilation holes 30b.
It is possible to effectively prevent the discharge electrode 32 from being contaminated by causing the air flow from the air flow toward the entire discharge electrode 32.

FIG. 4 is a sectional view of another embodiment of the discharge electrode device. In the discharge electrode device of this embodiment, the dustproof filter 50 is fixed to the outside of the shield case 30 so as to cover the dustproof filter 50, and the dustproof filter 50 is attached to the ventilation slit 30a or the ventilation hole 30b which is the air introducing unit K. The dust filter 50 can clean the air guided to the shield case 30 and reduce the contamination of the discharge electrode 32 by a clean air flow. In addition, it is fixed so as to cover the dustproof filter 50 inside the shield case 30,
The dustproof filter 50 may be attached to the ventilation slit 30a or the ventilation hole 30b.

[0020]

As described above, according to the first aspect of the present invention, the air can be guided into the shield case by the corona discharge of the discharge electrode from the air introduction means formed on the back surface opposite to the discharge direction of the shield case. It is possible to reduce the discharge electrodes by this air flow and improve the durability. Further, since air is introduced into the shield case from the air introduction means formed on the back surface opposite to the discharge direction of the shield case, the air flow does not obstruct the movement of the ozone flow due to the corona discharge, and the air flow cleans the discharge electrodes. Can be reduced.

According to the second aspect of the present invention, the contamination of the discharge electrode can be easily reduced by the air flow and the durability can be improved without damaging the needle-shaped or sawtooth-shaped discharge tooth tip of the discharge electrode. .

According to a third aspect of the invention, the air introducing means is:
It is a ventilation slit or a ventilation hole formed in the shield case, and it is possible to reduce the contamination of the discharge electrode by the air flow with a simple structure using the shield case.

According to a fourth aspect of the invention, the air introducing means is
The discharge electrode is formed in a range having a size equal to or larger than the electrode width and / or the electrode length, and the air flow from the air introduction unit can effectively reduce the contamination by hitting the entire discharge electrode.

According to the fifth aspect of the present invention, since the dustproof filter is attached to the air introducing means, the dustproof filter can reduce the contamination of the discharge electrode by a clean air flow.

[Brief description of drawings]

FIG. 1 is a sectional view of a schematic configuration of an image forming apparatus.

FIG. 2 is a cross-sectional view of a discharge electrode device.

FIG. 3 is a plan view of a discharge electrode device.

FIG. 4 is a cross-sectional view of another embodiment of the discharge electrode device.

[Explanation of symbols]

 1 Image Forming Apparatus 2 Image Carrier 30 Shield Case 31 Insulating Substrate 32 Discharge Electrode K Air Introducing Means

Claims (5)

[Claims] 1. A shield case facing an image carrier,
A discharge electrode mounted on an insulating substrate is arranged, a voltage is applied to this discharge electrode, and in a discharge electrode device for generating a corona discharge, on the back surface opposite to the discharge direction of the shield case surrounding the discharge electrode, A discharge electrode device, characterized in that an air introducing means for guiding air into the shield case is formed. 2. The discharge electrode device according to claim 1, wherein the discharge electrode has a needle-shaped or sawtooth-shaped discharge tooth tip. 3. The discharge electrode device according to claim 1, wherein the air introducing means is a ventilation slit or a ventilation hole. 4. The air introducing means is formed in a range having a size larger than an electrode width and / or an electrode length of the discharge electrode. Discharge electrode device. 5. The discharge electrode device according to claim 1, wherein a dustproof filter is attached to the air introducing means.