JP2863218B2 - Electrophotographic developing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for developing an electrostatic latent image formed on a photoreceptor surface in an apparatus such as electrophotography and electrostatic recording.

[Conventional technology]

In order to develop the electrostatic latent image formed on the photoreceptor surface, charged developing toner is supplied to the latent image surface, and the developing toner is electrostatically attracted to the developing toner in accordance with the pattern potential on the latent image surface. Adsorb and form a toner image. The toner image on the photoreceptor surface is transferred to a transfer material in a transfer section, and the transfer material on which the toner image has been transferred is fixed by means such as heat and pressure.

In a device in which a two-component developer composed of a mixture of a toner and a carrier is used as a developing means, and a magnetic brush is formed on a surface of a developer carrier which is a conductor, scratches and pinholes are present on the surface of a photoreceptor. In such a case, the magnetic brush contacts the conductive base material of the photoreceptor, thereby causing a development in which a developing bias leaks, thereby causing an abnormal image.

In order to prevent this bias leak, measures are taken to apply an insulating layer to the surface of the developer carrying member (developing roller).

Although the method of applying the insulating layer has the effect of preventing bias leakage, this insulating layer causes development that is charged by friction of the developer.

Usually, in a developing device having two or more developing devices,
When one developing unit is performing the developing operation, in the other developing unit not performing the developing operation, the mechanism for eliminating the spikes of the magnetic brush, that is, the ear-cutting mechanism operates, so that only the developing unit in operation is operated. Are configured to function as magnetic brushes.

The occurrence of the above-described charged development makes the operation of the above-mentioned non-operating developing device inoperable by the cutting-off mechanism, resulting in development in which these cutting operations cannot be performed.

By forming the insulating layer on the surface of the developer carrier, the developer electrostatically adheres to the insulating layer due to the triboelectric charging, and the cutting of the ears cannot be completely performed, so that an abnormal image such as a rubbed image occurs. Would.

Therefore, in practice, it is necessary to replace or repair a damaged photosensitive member in order to avoid forming an insulating layer on the surface of the developing roller which is a developing carrier and to prevent leakage of a developing bias. The situation.

[Problems to be solved by the invention]

The present invention uses a magnetic brush method and, in a developing apparatus having a plurality of developing units, a means for preventing leakage of a developing bias due to scratches on a photoreceptor and solving a problem of cutting off due to charge-up of the surface of a developing carrier. It is an object of the invention to provide an extremely inexpensive and simple configuration.

[Means for solving the problem]

In order to achieve the above object, the present invention provides an electronic device comprising a magnetic brush on a surface of a developer carrier and two or more developing devices for supplying a developing toner to a photoreceptor surface on which an electrostatic latent image is formed. In a photographic developing device, a developer carrier having a conductive coating layer having an insulation resistance of 10 ⁶ to 10 ⁹ Ω having a function of removing static electricity is formed on the surface of a non-magnetic conductive substrate that supplies a developing toner to a photoreceptor surface. It is characterized by having.

[Action]

According to the configuration of the present invention, the presence of one conductive coating layer having a predetermined insulation resistance provided on the surface of the conductive substrate prevents the development bias from leaking due to scratches on the surface of the photoreceptor, and
The unused developing roller can be reliably cut off.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

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

Reference numeral 1 denotes a drum-shaped photoconductor, and a color developing device that can develop an electrostatic latent image formed on the surface of the photoconductor 1 is indicated by A.

The color developing device A has a configuration in which the yellow developing unit Y, the magenta developing unit M, and the cyan developing unit C are respectively disposed around the photosensitive member 1 so as to be adjacent to each other.

The yellow developing section Y contains a yellow two-component developer, the magenta developing section M contains a magenta two-component developer, and the cyan developing section C contains a cyan two-component developer. Each developing unit has the same configuration except that the developer is different, and the yellow developing unit Y will be described.

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

The three developing units Y, M, and C are housed in the unit frame plate 7, are unitized, and are detachable from the apparatus main body.

In the color developing device A having such a configuration, first,
The rotation of the developer transport rotation member 3Y of the yellow developing section Y in the direction of the arrow causes the yellow developing section to be supplied to the developing roller 2Y rotating in a counterclockwise direction, which has a built-in magnet, and develops the surface of the developing roller 2Y forming a magnetic brush. The electrostatic latent image on the photoconductor 1 is developed by the agent. Therefore, a yellow color image is formed on the photoconductor 1.

The yellow color image of the photoconductor 1 is transferred to a predetermined transfer paper by a transfer unit.

Next, the magenta developer is supplied to the developing roller 2M that rotates in a counterclockwise direction including a magnet by the rotation of the developer conveying rotation member 3M of the magenta developing unit M, and the developing roller 2M that forms a magnetic brush develops the surface of the developing roller 2M. By the agent, the electrostatic latent image on the photoconductor 1 is visualized in magenta.

At the time of development by the magenta developing unit M, the developer on the developing roller 2Y of the yellow developing unit Y, which has been developed earlier, is cut off by the cross-cut method by the reverse rotation of the developing roller 2Y, and has already been lost. Does not affect the development of the magenta developing section M.

Then, the magenta color image of the photoreceptor 1 is transferred to a predetermined transfer sheet by the transfer unit.

Further, by the rotation of the developer transport rotating member 3C of the cyan developing section C, the cyan developer is supplied to the developing roller 2C which rotates in a counterclockwise direction and has a built-in magnet, and the developer on the surface of the developing roller 2C constituting the magnetic brush is formed. Thereby, the electrostatic latent image on the photoconductor 1 is visualized in cyan.

During the development by the cyan developing section C, the developer on the developing roller 2M of the magenta developing section M, which has been developed first,
The ears are cut off by the head cutting method by the reverse rotation of the developing roller 2M, and are already lost, so that the development of the cyan developing section C is not affected.

Then, the cyan color image of the photoreceptor 1 is similarly transferred to a predetermined transfer paper by a transfer unit.

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

Next, an embodiment of the configuration of the developing roller 2 used in the above-described developing device in the present invention will be described.

Figure 2, as shown in FIG. 3, the aluminum of the non-magnetic conductive base 2 ₁ on the surface, the electro-pack (DaiYasushi manufactured Kako Co.) by applying the conductive coating layer is electrostatically removed paint it is obtained by forming a 2 _2.

This electropack is a liquid paint comprising a primer EX-115 and an electropack 360A, which has a function of immediately removing static electricity that is likely to be generated on the surface of the object and preventing electrification. After applying, 100-150
Bake for about 1-2 hours at a temperature of ° C. The primer is a binder for the electropack.

In the present invention, it is necessary to prevent the development bias from leaking through the carrier when a dent or a pinhole on the surface of the photoconductor 1 is formed. by the respective film thicknesses of the primer portion and electro packing unit in the electro pack 30 [mu] m, and 50 [mu] m, when the insulation resistance of a value of 10 ^7, can prevent leakage of the developing bias,
In addition, the effect of removing static electricity was exhibited.

FIG. 4 shows experimentally the relationship between insulation resistance, leakage resistance, and short-cutting resistance of the material provided on the surface of the conductive substrate of the developing roller. The insulation resistance that satisfies the leak resistance and the short-cut resistance is 10 ⁶ to 10 ⁹ Ω
The resistance value can be obtained by selecting the film thickness of the electropack, which is a paint for removing static electricity. FIG. 5 shows the relationship between the film thickness and the leak resistance and the short-cut resistance.

Such a structure of the developing roller, the conductive base body 2 ₁ on the surface, due to the provision of the conductive coating layer 2 ₂ having a predetermined insulation resistance, if the dent and pinholes of the photosensitive member 1 surface is formed To prevent the developing bias from leaking through the carrier, the static electricity generated by the friction with the developer is not stored on the surface of the developing roller 2, and the developer is There is no occurrence of poor cutting.

As the conductive coating layer, other than the electropack, other static elimination paints having similar properties can be used.

〔effect〕

In the configuration of the present invention, a conductive coating layer made of a static elimination paint is formed on the conductive substrate of the developing roller to prevent leakage of the developing bias and to prevent the developer spikes from appearing on the surface of the unused developing roller. This has the effect of preventing poor cutting.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an embodiment of a color developing device to which the configuration of the present invention is applied, FIG. 2 is an external view of a developing roller of the present invention, FIG. FIG. 4 is a graph showing the properties of the conductive coating layer of the present invention, and FIG. 5 is a graph showing other properties of the conductive coating layer of the present invention. 1 photoconductor, A color developing device, Y yellow developing unit, M magenta developing unit, C cyan developing unit
2 ...... developing roller, 2 ₁ ...... conductive substrate 2 ₂ ...... conductive coating layer.

Claims (1)

(57) [Claims] A magnetic brush formed on a surface of the developing carrier,
In an electrophotographic developing device having two or more developing units for supplying a developing toner to the photoconductor surface on which an electrostatic latent image is formed,
On the surface of the non-magnetic conductive substrate for supplying the developing toner to the photoreceptor surface, a developer carrier having a conductive coating layer having an insulation resistance of 10 ⁶ to 10 ⁹ Ω having a function of removing static electricity is provided. Developing device for electrophotography.