JPH0451066A - Electrophotographic developing device - Google Patents

Abstract

PURPOSE:To prevent the leakage of a develop ement bias caused by the damage etc., of the face of an photosensitive body by forming an unelectrified insulating layer having surface resistivity >= 10<9>OMEGA, on the surface of a nonmagnetic conductive substrate, as the developer carrier of a developing unit supplying developing toner to the face of the photosensitive body. CONSTITUTION:The unelectrified insulating layer 22 having the surface resistivity >=10<9>OMEGA on the surface of the nonmagnetic conductive substrate 21, as the devel oper carrier of the developing unit supplying the developing toner to the face of the photosensitive body. Thus, high insulating properties are obtained, the leakage of the developing bias can be effectively prevented, and simultaneously, The insulating layer 22 has properties not to be electrified. Therefore, static electricity is not stored on the surface of the unelectrified insulating layer 22, but the miscutting of the napping of a developer can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device suitable for developing or cleaning an electrostatic latent image formed on the surface of a photoreceptor in an apparatus for electrophotography, electrostatic recording, or the like.

[Conventional technology]

To develop the electrostatic latent image formed on the photoconductor surface, a charged developing toner is supplied to the latent image surface, and due to the electrostatic adsorption action of the developing toner, the developing toner corresponds to the pattern potential on the latent image surface. adsorbs and forms a toner image. The toner image on the surface of the photoreceptor is transferred to a transfer material in a transfer section, and the transfer material to which the toner image has been transferred is fixed by heat, pressure, or other means.

When there are scratches, pinholes, etc. on the surface of the photoreceptor in a device that uses a two-component developer consisting of a mixture of toner and carrier as a developing means and has a magnetic brush on the surface of a conductive developer carrier. When the magnetic brush comes into contact with the conductive base material of the photoreceptor, a phenomenon occurs in which the developing bias leaks, resulting in the generation of abnormal images.

In order to prevent this bias leak, a measure has been taken to provide an insulating layer on the surface of the developer carrier.

Although the method of applying an insulating layer certainly has the effect of preventing bias leakage, this insulating layer causes a phenomenon in which it becomes charged due to friction of the developer.

Normally, in a developing device equipped with two or more developing devices, when one developing device is performing a developing operation, the other developing device that is not performing a developing operation has a mechanism to prevent the magnetic brush from standing up. The brush cutting mechanism is activated so that only the developing device in operation functions as a magnetic brush.

The occurrence of the above-mentioned charging phenomenon makes it impossible for the above-mentioned ear cutting mechanism in the inactive developing device to function, resulting in the phenomenon that these ears cannot be cut.

By forming an insulating layer on the surface of the developer carrier, the developer electrostatically adheres to the insulating layer due to frictional electrification, making it impossible to completely cut the spikes, resulting in abnormal images such as scratched images. Put it away.

Therefore, in reality, in order to avoid forming an insulating layer on the surface of the developing roller, which is the developer carrier, and to prevent leakage of the developing bias, it is necessary to replace the photoreceptor with scratches and repair the scratches. This is a major cause of cost increases.

[Problems to be Solved by the Invention] The present invention uses a magnetic brush method in a developing device having a plurality of developing devices, in which an insulating layer is provided on the surface of the developer carrier in order to prevent leakage of developing bias due to scratches on the photoreceptor, etc. The purpose is to extremely easily form a layer and prevent the generation of static electricity on the insulating layer, and to provide a developer carrier that can eliminate defective cutting caused by charge-up on the surface of the developer carrier, and to significantly reduce costs. It is intended to enable reductions.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention provides an electrophotographic photographic device comprising a magnetic brush on the surface of a developer carrier and two or more developing devices that supply developing toner to the surface of a photoreceptor on which an electrostatic latent image is formed. In the developing device, an uncharged insulating layer having a surface resistivity of 109Ω or more is formed on the surface of a nonmagnetic conductive substrate as a developer carrier of the developing device that supplies developed toner to the surface of the photoreceptor. It is something to do.

[For production]

In the structure of the present invention, the uncharged insulating layer having a predetermined surface resistivity provided on the surface of the conductive substrate prevents leakage of developing bias caused by scratches on the surface of the photoreceptor, and moreover, the uncharged insulating layer has a predetermined surface resistivity. Therefore, the unused developing roller can be reliably trimmed without accumulating static electricity.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a developing device equipped with the developer carrier of the present invention.

1 is a drum-shaped photoreceptor, and a color developing device capable of developing an electrostatic latent image formed on the surface of the photoreceptor 10 is indicated by A.

The color developing device A has a structure in which a yellow developing section Y, a magenta developing section M, and a cyan developing section C are arranged adjacent to each other around the photoreceptor 1.

A yellow two-component developer is used in the yellow developing section Y.
A magenta two-component developer is placed in the magenta developing section M.
The cyan developing section C accommodates a cyan two-component developer, and except for using different developers, each developing section has the same configuration.The yellow developing section Y will be explained below. do.

The yellow developing section Y contains a yellow two-component developer in a developing casing 4Y, and is provided with a developing roller 2Y having a built-in magnet that rotates in the direction of the arrow, and a developer conveying rotating member 3Y. 5Y is toner density sensor, 6
Y is a doctor that regulates the amount of developer supplied to the surface of the developing roller 2.

The three developing sections Y, M, and C are housed in a unit frame plate 7, and are formed into a unit that can be attached to and detached from the main body of the apparatus.

In the color developing device A having such a configuration, first, by rotating the developer conveying rotating member 3Y of the yellow developing section Y in the direction of the arrow, the yellow developer is supplied to the developing roller 2Y, which has a built-in magnet and rotates counterclockwise. The developer on the surface of the developing roller 2Y, which constitutes a magnetic brush, causes the photoreceptor 1 to
The upper electrostatic latent image is developed. Therefore, a yellow facial image is formed on the photoreceptor 1.

The yellow face image on the photoreceptor 1 is transferred to a predetermined transfer paper at a transfer section.

Next, by the rotation of the developer conveying rotating member 3M of the magenta developing section M, the magenta developer is supplied to the developing roller 2M that has a built-in magnet and rotates in a counterclockwise direction, and develops the surface of the developing roller 2M that constitutes a magnetic brush. The electrostatic latent image on the photoreceptor 1 is visualized in magenta color by the agent.

At the time of development by this magenta developing section M, the developer on the developing roller 2Y of the yellow developing section Y, which was developed earlier, is cut off by the ear cutting method by reverse rotation of this developing roller 2Y, and has already been reduced to nothing. , should be configured so as not to affect the development of the magenta developing section M.

Then, the magenta facial image on the photoreceptor 1 is similarly transferred to a predetermined transfer paper at the transfer section.

Further, by the rotation of the developer conveying rotating member 3C of the cyan developing section C, the cyan developer is supplied to the developing roller 2C that has a built-in magnet and rotates in a counterclockwise direction, and the developer on the surface of the developing roller 20 that constitutes a magnetic brush is As a result, the electrostatic latent image on the photoreceptor 1 is visualized in cyan color.

During development by the cyan developing section C, the developer on the developing roller 2M of the magenta developing section M that was developed first is
It is necessary to configure the structure so that the spikes are cut by the spike-cutting method using the reverse rotation of the developing roller 2M, and are already gone, so that they do not affect the development in the cyan developing section C.

The cyan facial image on the photoreceptor 1 is also transferred to a predetermined transfer paper at the transfer section.

As described above, facial images of each color are sequentially obtained on the photoreceptor 1, and these facial images of each color are sequentially transferred to a predetermined transfer paper.
A color image on transfer paper is obtained.

Therefore, when scratches or pinholes occur on the surface of the photoreceptor 1 shown in FIG. 1, the developing rollers 2Y and 2M.

When 2C has a nonmagnetic conductive substrate 21 on its surface as shown in FIG. 2, the developing bias applied to the developing roller leaks.

Therefore, in the present invention, as shown in FIG. 3 (□□□), on the surface of the nonmagnetic conductive substrate 2I of the developing roller 2 shown in FIG.
Coating.

Non-magnetic conductive substrate 2. The non-magnetic conductive base 2. consists of a sleeve-shaped base made of extruded aluminum. A ceramic having a surface resistivity of 10'4 Ω is coated on the surface as an uncharged insulating layer 2□ having a surface resistivity of 10 9 Ω or more.

As a result, the uncharged insulating layer 2□ with a surface resistance of 109Ω or more provides high insulation properties, effectively preventing leakage of developing bias, and this insulating layer has the property of not being charged. Therefore, the uncharged insulating layer 2□
Static electricity does not accumulate on the surface of the developer, and defective tip cutting of the developer can be effectively prevented.

With this configuration of the developing roller, the uncharged insulating layer 2□ is provided on the surface of the conductive substrate 2, so that even if a dent or pinhole is formed on the surface of the photoreceptor 1, the developing bias can be applied via the carrier. This prevents leakage, and also prevents static electricity generated by friction with the developer from being stored on the surface of the developing roller 2, thereby causing defective developer tip cutting on the surface of the unused developing roller. There is no.

Specifically, silica glass (S) has a surface resistivity of 1014Ω or more, a dielectric constant of 4 or less, and excellent electrical properties.
ing) is preferred. This material is coated to a thickness of about 30 μm on a conductive substrate made of aluminum by a processing method called plasma spraying.

Basically, as a coating material, the higher the surface resistivity and the lower the dielectric constant, the better, so a rubber material or a resin material may be used. However, since it is used on the surface of a developing roller for two-component development, ceramic, which is more durable, is suitable.

Although the present invention has been described as a developing roller of a developing device, it can also be applied to a cleaning sleeve using a magnetic brush in a cleaning device.

〔effect〕

In the configuration of the present invention, by simply coating the surface of the conductive substrate with an uncharged insulating agent to form an uncharged insulating layer,
It has the effect of preventing leakage of developing bias due to scratches etc. on the surface of the photoconductor, and prevents defective developer tip cutting due to charge-up on the surface of the developing roller, and is used to prevent leakage of developing bias due to scratches on the photoconductor. , has the advantage of significant cost savings compared to conventional means that required replacement or repair of the photoreceptor.

1. Developing section, M... Magenta developing section, C... Cyan developing section, 2... Developing roller, 2. ... Conductive substrate, 2
2...Uncharged insulating layer.

Claims (1)

[Claims] In an electrophotographic developing device equipped with two or more developing devices, each of which has a magnetic brush on the surface of a developer carrier and supplies developed toner to the photoreceptor surface on which an electrostatic latent image has been formed, the developed toner is supplied to the photoreceptor surface. An electrophotographic developing device characterized in that an uncharged insulating layer having a surface resistivity of 10^9 Ω or more is formed on the surface of a nonmagnetic conductive substrate as a developer carrier of a developing device.