JPH08101560A - Electrostatic charging brush device - Google Patents

Abstract

PURPOSE: To prevent uneven electrostatic charging on a photoreceptor and to obtain an excellent image without irregularities by conductively coupling a conductive sheet to a brush mounting fitting and bringing it into contact with the front and rear sides or the rear side of the brush. CONSTITUTION: This device is constituted of a brush 1 for electrostatic charging, the metallic mounting fitting 2 for attaching the brush 1, the conductive sheet 3 and the drum-like photoreceptor 4. The brush 1 is made of rayon conductive fiber, and conductively stuck and fixed to the fitting 2 with conductive adhesive. The brush 1 comes in contact with the photoreceptor 4 while holding a fixed bite amount. The sheet 3 is arranged on the front side of the brush 1, stuck and fixed to the fitting 2 holding the brush 1 with the conductive adhesive, and comes in contact with the brush 1 with fixed stress, and its leading edge does not come in contact with the photoreceptor 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging brush device for charging a drum-shaped photosensitive member in an electrophotographic copying machine, an electrostatic recording system and the like.

[0002]

2. Description of the Related Art In an electrophotographic process in a copying machine, a printer or the like, the surface of an electrostatic latent image carrier such as a photoconductor is usually charged by a charging device, and the charged area is imagewise exposed to electrostatic latent image. An image is formed, the electrostatic latent image is developed into a visible image, and the visible image is transferred to a transfer material.

Conventionally, the charging device used in most of the electrophotographic apparatus is a non-contact type charging device represented by a corona charging system such as a corotron or a scorotron. These chargers have the advantages of simple structure and stable charging performance. However, since a high voltage power supply of -5 kv to -10 kv is used, there is a problem in safety, and ozone generated during corona discharge may cause deterioration of components such as the photoconductor and may be harmful to humans. There was a problem like that.

Therefore, in recent years, the generation of ozone, which has an adverse effect on the human body, is extremely small as compared with the corona charging device.
A fixed type that can be charged at a low voltage and has little deterioration of the photoconductor,
A contact charging method in which a contactor such as a rotary brush is brought into contact with a photoconductor has been actively studied.

[0005]

However, in the structure of the conventional brush type charger, the surface of the photosensitive member is uniformly charged because the microscopic brush density of the surface in contact with the photosensitive member is not uniform. Therefore, there is a problem in that uneven charging occurs and vertical streaks occur in the image. Here, the charging unevenness is a range of variation of the surface potential on the photoconductor.

An object of the present invention is to solve the above problems and to provide a charging brush device capable of preventing the generation of vertical stripes in an image.

[0007]

In order to solve the above problems, the charging brush device of the present invention includes a charging brush that contacts a drum-shaped photosensitive member, a brush mounting bracket for mounting the brush, and a brush mounting bracket. A conductive sheet electrically conductively bonded is provided, and a part of the conductive sheet is brought into contact with a charging brush.

[0008]

With the above structure, the charging brush device of the present invention is
The variation range of the surface potential of the photoconductor can be set to 200 V or less, and the generation of vertical stripes in the image can be suppressed.

[0009]

Embodiments of the charging brush device of the present invention will be described below with reference to the drawings, taking a non-magnetic one-component developing device as an example. Here, this developing device is not limited to the non-magnetic one-component developing system, but includes a magnetic two-component system, a magnetic one-component system, and various other systems.

First, the structure and each member of the charging brush device of the embodiment of the present invention will be described. FIG. 1 is a front view showing the structure of a charging brush device according to an embodiment of the present invention. In FIG. 1, 1 is a brush for charging, 2 is a metal fitting for attaching the brush 1, 3 is a conductive sheet,
Reference numeral 4 is a drum-shaped photoconductor.

Here, the brush 1 is made of rayon-based conductive fiber or the like, and is electrically conductively adhered and fixed to a metallic mounting member 2 by a conductive adhesive. The material of the brush 1 is not limited to rayon, and nylon, acetate, vinylon, vinylidene, etc. can be used.

Here, the conductive sheet 3 is made of a polymer material or the like in which a conductive material or the like is dispersed so as to have conductivity. Examples of the polymer material include nylon, rayon, acetate, vinylon, vinylidene,
Examples thereof include, but are not limited to, fluorinated ethylene, polyurethane, polyester, polyethylene, polyvinyl chloride, and polypropylene. Further, as the conductive material dispersed in the above material, carbon black, carbon fiber, metal powder or the like can be used, and the conductive sheet 3
The volume resistance value is adjusted to about 10 ³ to 10 ¹⁰ Ω · cm. The materials described above are the most suitable, but the materials are not particularly limited, and the same effect can be obtained with other materials.

FIG. 2 is a side view when the charging brush 1 and the conductive sheet 3 are related to the photoconductor 4.
As shown in FIG. 2, the charging brush 1 is in contact with the photoconductor 4 while keeping a certain amount of bite, and the conductive sheet 3 is arranged in front of the charging brush 1 and 1 is attached and fixed to a metal mounting bracket 2 holding 1 by a conductive adhesive or the like, and is in contact with the charging brush 1 with a constant stress.
I try not to come into contact with.

The shape of the conductive sheet 3 is not particularly limited, and for example, the shape of the portion contacting the brush 1 may be an arbitrary shape such as an arc shape or a triangular shape. Then, a DC voltage is applied to the brush 1 and the conductive sheet 3 through the mounting bracket 2. As the value of the DC voltage, a positive or negative value of about 700 to 2 kV is selected.

Next, a printing apparatus using these members will be described. FIG. 3 shows a schematic configuration diagram of the printing apparatus.
In FIG. 3, reference numeral 5 denotes a DC power source for applying a voltage to the charging brush 1, which voltage is Vc. Reference numeral 6 denotes a DC power source for applying a voltage to the developing roller 7 in contact with the surface of the drum-shaped photosensitive member 4 on the downstream side of the brush 1, and the voltage is Vb. Reference numeral 8 is an exposure device. The surface potential on the photoconductor 4 after exposure by the exposure device 8 is VL. The printing patterns used in the examples will be described below.

As shown in FIG. 4, this pattern has a width of 85 μm (corresponding to an ldot diameter of 300 dpi resolution) and a length of 7 in the main scanning direction of the laser beam of the exposure device 8.
A pattern in which the inch line is drawn as shown in FIG.
Further, in this width scanning direction, the line width is 85 μm and the length is 2 inc.
There are two types of patterns in which the line h is drawn as shown in FIG.

The vertical stripes in these patterns will be described below. When uneven charging in the main scanning direction occurs during charging, in FIG. 4A, a part of the line is interrupted or the line width becomes thick, and the line looks like a vertical stripe.
Further, in FIG. 4B, the line widths are partially different, and it looks like a vertical stripe as a whole. (Test Example 1) As a specific test example, Table 1 shows the results of a test performed using the PET conductive sheet in the apparatus shown in FIG. The charging brush used was composed of a bundle of rayon fibers containing conductive carbon black, and the resistance value was adjusted to about 10 ⁶ Ω · cm. It is set to bite 1 mm. The development method used in the test is non-magnetic one-component contact development, and reversal development is performed. The photoconductor drum is a negative charging type organic photoconductor. The toner used is a negatively charged polyester toner. The results of vertical stripes in (Table 1) were evaluated as follows. ◎: No vertical stripes ○: Virtually no vertical stripes △: Vertical stripes are observed ×: Vertical stripes are noticeable

[0018]

[Table 1]

Test Example 2 As shown in FIG. 5, the conductive sheet 3 was placed behind the brush 1 and the same test as in Test Example 1 was conducted, but similarly good results could be obtained. .

[0020]

As is apparent from the above description of the embodiments, the charging brush device of the present invention has a structure in which the conductive sheet is conductively coupled to the brush mounting member and is in contact with the front side or the rear side of the brush. Therefore, when the photoconductor is charged by this charging brush device, it is possible to prevent charging unevenness on the photoconductor, and as a result, it is possible to provide a good image without image dripping.

[Brief description of drawings]

FIG. 1 is a front view of a charging brush device according to the present invention.

FIG. 2 is a side view of the charging brush device.

FIG. 3 is a block diagram of an electrophotographic apparatus using the same charging brush device.

FIG. 4 is a schematic diagram of an evaluation pattern.

FIG. 5 is a configuration diagram of an electrophotographic apparatus including a charging brush device according to another example of the present invention.

[Explanation of reference symbols] 1 brush for charging 2 brush mounting bracket 3 conductive sheet 4 photoconductor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Noda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Tetsuhiro Tsuru, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 72) Inventor Iku Kawamura, 1723 Kitatahara-cho, Ikoma-shi, Nara Toei Sangyo Co., Ltd.

Claims (4)

[Claims] 1. A brush mounting member for applying a voltage, a charging brush in contact with a photosensitive member, and a conductive sheet conductively coupled to the brush mounting member. The conductive sheet contacts the charging brush. Charging brush device characterized by 2. The conductive sheet has a resistance value of 10 ³ to 10 ^10.
The charging brush device according to claim 1, wherein the charging brush device has a range of Ω · cm. 3. The charging brush device according to claim 1, wherein the conductive sheet is arranged on the front side of the charging brush with reference to the rotation direction of the drum-shaped photosensitive member. 4. The charging brush device according to claim 1, wherein the conductive sheet is arranged on the rear side of the charging brush with reference to the rotation direction of the drum-shaped photosensitive member.