JPH0728295A - Contact charging device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a contact charging device having higher durability. [Structure] Sheet-like charging member 12 of contact charging device 10
Is fixed at both ends to the metal block 14 such that the intermediate portion projects downward, and the downward projecting portion is
It is pressed against the photoconductor layer 16. The sheet-shaped charging member 12 has elasticity due to the polyimide insulating layer 11 as a whole, and therefore, the intermediate portion protruding downward from the metal block 14 has elasticity. Therefore, the sheet-shaped charging member 12 pressed against the photosensitive layer 16 is deformed according to the unevenness of the surface of the photosensitive layer 16, and the sheet-shaped charging member 1 is formed.
The contact between the second resistance layer 15 and the photosensitive layer 16 is kept uniform. Further, the pressure contact force of the sheet-shaped charging member 12 with respect to the photoconductor layer 16 can be reduced, wear is reduced, and the life of the photoconductor layer 16 and the resistance layer 15 is extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device for an electrophotographic image forming apparatus such as a laser printer, a copying machine or a facsimile, and more particularly to a contact charging device.

[0002]

2. Description of the Related Art As a charging device in an electrophotographic apparatus,
From the viewpoint of the relationship between the charging electrode and the body to be charged, there are mainly two types: contact type and non-contact type. In general, the contact charging device is characterized in that the applied voltage is low and the amount of ozone generated is small as compared with the non-contact charging device.

As an example of such a contact charging device, Japanese Patent Laid-Open No. 2-28280 discloses a structure in which a contact charging member is pressed against an object to be charged by elastic flexibility of a leaf spring or the like. The configuration of such a contact charging device will be described below with reference to FIG.

The leaf spring 62 is fixed to a conductive holding member 63 by a pressing member 64 and a screw 65 so as to come into contact with the photosensitive layer 67 provided on the surface layer of the photosensitive drum 69 which is a member to be charged. ing. The photoconductor drum 69 is obtained by coating the surface layer of the aluminum tube 68 with the photoconductor layer 67. The leaf spring 62 is provided with a resistance layer 61 having elasticity so as to include a portion in contact with the photoconductor layer 67.
For the leaf spring 62, SUS or the like having a thickness of about 100 μm is used. The resistance layer 61 has a thickness of 50 to 100 μm.
Urethane rubber, NBR or the like having a resistance value of about 10 ³ to 10 ¹⁵ Ωcm at m is used. A power source 66 is connected to the holding member 63 via an electric wire. The voltage applied by the power supply 66 is generally about -500 to -2000V.

[0005]

However, in the above-mentioned conventional contact charging device, since the conductive member is pressed against the member to be charged by the leaf spring, the frictional resistance is large and the abrasion of the resistance layer and the photoconductor layer is a problem. became. Therefore, there is a drawback that the durability cannot be improved.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a contact charging device having higher durability.

[0007]

In order to achieve this object, a contact charging device of the present invention is a contact charging device for applying a voltage to a sheet-like charging member that is in contact with the surface of an object to be charged. The sheet-like charging member is elastically flexible and is formed of a multi-layer including at least an insulating layer and a resistance layer, and the sheet-like charging member is in contact with the surface of the member to be charged. The charging member holding means for holding the charging member on both sides of is provided.

[0008]

According to the contact charging device of the present invention having the above-mentioned structure, the pressure contact force between the sheet-shaped charging member and the member to be charged is small, which reduces the frictional resistance between them and the resistance layer due to abrasion. Little film loss on the photoconductor layer.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a contact charging device 10 embodying the present invention comprises a sheet-like charging member 12, a metal block 14 as a power feeding electrode for holding the sheet-like charging member 12, and a known photoconductor layer. Aluminum tube electrode 1 coated with 16
8 and a power supply 22 connected to the metal block 14
Etc.

The sheet-like charging member 12 preferably has a structure as shown in FIG. That is, the sheet-shaped charging member 1
2 is a polyimide insulating layer 11 having a thickness of about 50 μm and a thickness of about 0.3 μm laminated on the polyimide insulating layer 11.
Of the Cu metal layer 13 and a TaN resistance layer 15 having a thickness of about 0.3 μm laminated on the Cu metal layer 13. The surface resistivity of the resistance layer 15 is 10 ⁵ to 1
0 ¹² Ω / □, particularly preferably 10 ⁷ to 10 ¹⁰ Ω /
It has been adjusted to □. In this embodiment, the surface resistivity is 3 ×
10 ⁸ Ω / □ was used.

OPC (organic photoconductor), amorphous silicon, selenium, etc. are used for the photoconductor layer 16, but OPC is used in this embodiment. Photoconductor layer 16
Has a thickness of about 20 μm.

As shown in FIG. 1, the sheet-like charging member 12 has its both ends fixed to the metal blocks 14 so that the intermediate portion thereof projects downward, and the downward projecting portion is the photosensitive layer. It is pressed against 16. Further, electrically, the metal block 14 and the metal layer 13 of the sheet-shaped charging member 12 are in a conductive state. The metal block 14 is
The sheet-shaped charging member 12 is arranged parallel to the axis of the aluminum tube electrode 18, so that the sheet-shaped charging member 12 also extends in the width direction of the aluminum tube electrode 18. The sheet-like charging member 12 has elastic flexibility as a whole due to the polyimide insulating layer 11, and therefore, the intermediate portion protruding downward from the metal block 14 has elasticity.

Therefore, the sheet-like charging member 12 pressed against the photoreceptor layer 16 is deformed according to the unevenness of the surface of the photoreceptor layer 16, and the resistance layer 15 and the photoreceptor layer 16 of the sheet-like charging member 12 are deformed.
The contact is maintained uniform.

In the present embodiment, unlike the conventional example, a leaf spring or the like is not used, so that the sheet-like charging member 12 can be made very thin, and accordingly, the photosensitive layer 16 is easily deformed according to the unevenness, and the resistance layer 15 is formed. The contact between the photosensitive layer 16 and the photosensitive layer 16 can be kept more uniform. As a result, there is an advantage that uneven charging can be reduced. Furthermore, the pressure contact force of the sheet-shaped charging member 12 with respect to the photoconductor layer 16 can also be reduced, and therefore, the wear on both the photoconductor layer 16 and the resistance layer 15 is small, and the life of the photoconductor layer 16 and the resistance layer 15 is long. There are advantages.

Next, the operation of the contact charging device of this embodiment will be described. The photoconductor drum rotates in the direction of the arrow in the figure at a predetermined peripheral speed, for example, 47 mm / sec. Between the metal block 14 and the aluminum tube electrode 18,
A DC voltage is applied by the DC power supply 22. Therefore, a potential difference is generated between the metal layer 13 of the sheet-shaped charging member 12 and the aluminum tube electrode 18 which is grounded through the resistance layer 15, and therefore, between the resistance layer 15 and the photoconductor layer 16, The surface of the photoconductor layer 16 is charged by the charge injection at the contacting point and by the discharge at the contactless point forming the minute gap. At this time, the resistance of the resistor layer 15 controls that a large current is about to flow between the metal layer 13 and the aluminum tube electrode 18, so that spark discharge or arc discharge does not occur and stable corona discharge is generated. It can be carried out. Therefore, in order to perform stable charging, it is desirable to mainly charge by discharging.

As a result of actual charging using the contact charging device 10 of this embodiment, when the applied voltage was about -1400V, the charging potential was about -820V. The charge distribution is uniform, and the charge unevenness is 50 V or less, which is almost at the practical level.

Next, another embodiment shown in FIG. 3 will be described. The present embodiment is characterized in that the metal block holding the sheet-shaped charging member has a regular polygonal cross section, for example, a regular hexagonal shape. And explain.

The contact charging device 30 of this embodiment is constructed by winding the sheet-shaped charging member 12 around a metal block 32 as a power feeding electrode having a regular hexagonal cross section. A slit 34 extending from the top to the center of the metal block 32 is formed to extend in the longitudinal direction, and both ends of the sheet-like charging member 12 are inserted and fixed in the slit 34, The sheet-shaped charging member 12 is fixed on the metal block 32.

At this time, as shown in FIG. 3, the sheet-like charging member 12 is in contact with each top of the metal block 32 by its own elastic force, and fixed between the tops in a shape protruding outward. To be done. The contact charging device 30 is arranged such that the outwardly projecting portions of the sheet-shaped charging member 12 between the respective tops are in elastic contact with the photoconductor layer 16. Therefore, the sheet-shaped charging member 12 is deformed according to the unevenness of the surface of the photoconductor layer 16, and the contact between the resistance layer 15 of the sheet-shaped charging member 12 and the photoconductor layer 16 is kept uniform. In addition, electrically, the metal block 32 and the metal layer 13 of the sheet-shaped charging member 12 are in a conductive state, and the power supply 22 is connected to the metal block 32.

The operation of the contact charging device of this embodiment is the same as that of the above-mentioned embodiment, so the description thereof will be omitted. However, one of the features of this embodiment is that there are six discharge surfaces. If the battery is damaged or deteriorated, the life can be greatly improved by changing the discharge surface.

The present invention is not limited to the embodiments described in detail above, and various modifications can be made without departing from the spirit of the invention.

For example, in the present embodiment, the applied voltage was a DC voltage, but it is also possible to apply AC voltages in a superimposed manner. Also, the block does not have to be metal,
The cross section does not have to be a regular polygon.

[0024]

As is apparent from the above description, according to the present invention, the contact charging device having a longer life, excellent uniform charging, and higher reliability than the conventional contact charging device is economically inexpensive. A device can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a contact charging device embodying the present invention.

FIG. 2 is a diagram showing a charging film.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a diagram illustrating a conventional configuration.

[Explanation of symbols]

 10 Charging Device 12 Sheet Charging Member 14 Metal Block 16 Photoconductor Layer 22 Power Supply

Claims (2)

[Claims] 1. A contact charging device for charging a sheet-shaped charging member brought into contact with the surface of an object to be charged by applying a voltage, wherein the sheet-shaped charging member has elastic flexibility and is at least insulating. A contact charging device comprising a multi-layered structure including a layer and a resistance layer, and provided with a charging member holding means for holding the sheet-shaped charging member on both sides of a portion in contact with the surface of the member to be charged. 2. The contact charging device according to claim 1, wherein the charging member holding means has a regular polygonal shape.