JP2863255B2 - 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.

When 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 the surface of a development carrier, which is a conductor, when there is a scratch or a pinhole on the surface of a photoreceptor In this case, when the magnetic brush comes into contact with the conductive base material of the photoreceptor, a phenomenon occurs in which a developing bias leaks, and an abnormal image is generated.

In order to prevent this bias leak, measures have been taken to provide an insulating layer on the surface of the developing carrier.

Although the method of applying the insulating layer has the effect of preventing the bias leak, the phenomenon that the insulating layer is charged by the friction of the developer occurs.

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 charging phenomenon disables the operation of the above-described ear-cutting mechanism in the inoperable developing device, resulting in a phenomenon that these ear-cuts cannot be performed.

By forming an insulating layer on the surface of the development carrier,
The developer electrostatically adheres to the insulating layer due to triboelectric charging,
Since the ear cutting cannot be completely performed, an abnormal image such as a rubbing image occurs.

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 serving as a developing carrier and to prevent leakage of a developing bias. The situation.

[Problems to be solved by the invention]

INDUSTRIAL APPLICABILITY The present invention uses a magnetic brush method, and in a developing apparatus having a plurality of developing units, helps prevent leakage of a developing bias due to scratches on a photoreceptor, and eliminates a problem of cross-cut due to charge-up of the surface of a developing carrier, and It is another object of the present invention to provide a development carrier that effectively uses uneven portions formed on the surface of the development carrier to pump up the developer.

[Means for solving the problem]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a developing device for electrophotography, comprising a magnetic brush, and a developing device for cutting off a magnetic brush for supplying a developing toner to a photoreceptor surface on which an electrostatic latent image is formed. Wherein a static elimination coating layer is formed on a surface of a convex portion of a substrate having an uneven shape for supplying a developing toner to a photoreceptor surface.

[Action]

According to the configuration of the present invention, when the insulating layer is provided on the surface of the conductive substrate, the leakage of the developing bias caused by the scratch on the surface of the photoreceptor is prevented, and the static eliminator is provided on the surface of the convex portion of the developing roller. As a result, a small amount of the static electricity removing coating layer ensures that the unused developing roller is cut off, and a static electricity removing coating layer is formed on the uneven surface of the developing roller. By doing so, there is no effect on developer pumping and transportability.

〔Example〕

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

FIG. 4 shows a developing device provided with the developing 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 respective developing units of a yellow developing unit Y, a magenta developing unit M, and a cyan developing unit C are arranged adjacent to each other around the photoconductor 1.

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 yellow 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 an arrow, and a developer transport rotating member 3Y. 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 yellow developer is supplied to the developing roller 2Y which rotates in a counterclockwise direction and has a built-in magnet by the rotation of the developer transporting rotation member 3Y of the yellow developing section Y in the direction of the arrow, and develops the surface of the developing roller 2Y constituting the 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 section M, the developer on the developing roller 2Y of the yellow developing section 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.

On the surface of each developing roller 2 shown in FIG. 5, an uneven surface suitable for pumping up the developer from the developer transport rotation member 3 and transporting the developer to the photoreceptor 1 is formed.

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.

In the present invention, a configuration of the developing roller 2 of the developing device, the surface of the aluminum of the non-magnetic conductive base 2 ₁ formed with the uneven portion on the surface as described above (FIG. 3 (a)), hard anodized ( HAl treatment) and surface resistivity of 10 ⁹ Ω
The insulating layer 2 ₂ (FIG. 3 (b)) to provided, further, the insulating layer
On the 2 _2, in which subjected static eliminator coating layer 2 ₃ by applying the electro-pack is a static eliminator paint (manufactured by DaiYasushi Kako Co., Ltd.) (FIG. 1 (a)) a. In this case, the surface resistivity of the used electropack was 10 ⁶ Ω.

The nonmagnetic conductive substrate 2 ₁ of the surface forming the uneven portion 2 _ab,
As shown in FIG. 1 (a), together with the insulating layer 2 ₂ is provided, the static electricity removing paint layers 2 _3, which is coated on the insulating layer 2 _2,
It is applied only to the surface of the convex portion _2a of the concave / convex portion _2ab .

Thus, an antistatic coating layer 2 _3, when applied to the entire surface of the uneven portion 2 _ab which is provided with an insulating layer 2 ₂ (Fig. 1 (b)), the corners of the recess 2 _b of the concavo-convex part 2 _ab R becomes Jo, pumping of the developer, affects the transport properties, in the present invention, the static electricity removing paint layer 2 ₃ is applied only to the convex portion 2 _a surface of the uneven portion 2 _ab, uneven portions 2 _ab recess 2 _It is possible to smooth the pumping and transporting properties of the developer and remove static electricity generated in the insulating layer without impairing _b .

As in FIG. 1 (a), the concave-convex portion an antistatic coating layer 2 ₃
When forming only the convex portions 2 _a surface of 2 _ab, as shown in FIG. 2 (a), even if there is some variation in the doctor gap, but little change in the pumping amount of the developer, the as in Fig. 1 (b), as the case of forming an antistatic coating layer 2 ₃ on the entire surface of the uneven portion 2 _ab, shown in FIG. 2 (b),
A slight difference in the doctor gap results in a large change in the amount of developer pumped.

Incidentally, only the convex portions 2 _a surface of the uneven portion 2 _ab which is provided with an insulating layer 2 _2, by static electricity removing paint layer 2 ₃ is applied, the concave portion 2 _b
'S static electricity can be removed occur in the insulating layer 2 _2, because is grounded to the static elimination coating layer 2 ₃ of the convex portion 2 _a surface via a conductive carrier.

The electropack is a liquid paint comprising a primer EX-115 and an electropack 360A and having a function of immediately removing static electricity to be generated on the surface of the object and preventing electrification. And baking at a temperature of 100 to 150 ° C. for about 1 to 2 hours. The primer is a binder for the electropack.

Such a structure of the developing roller, since the conductive base body 2 ₁ a surface provided with an insulating layer 2 _2, is leak developing bias through the carrier when the dent and pinholes of the photosensitive member 1 surface is formed prevents, moreover, only the convex portions 2 _a surface of the uneven portion 2 _ab which is provided with an insulating layer 2 _2, by providing an antistatic coating layer 2 _3, scooping of the developer on the surface of the developing roller 2 , With a small amount of static-removing coating agent, the static electricity on the developing roller surface generated by friction with the developer is removed without impairing the transportability. It does not occur.

The results of the experiment, the surface resistivity of the insulating layer 2 ₂ provided on the conductive base body 2 ₁ Surface 10 ⁶ Omega above, the surface resistivity of the static eliminator coating layer 2 ₃ to achieve the effect in 10 ⁴ to 10 ⁹ Omega Can be.

Although the present invention has been described as the developing roller of the developing device, the present invention is also applicable to a cleaning sleeve using a magnetic brush in a cleaning device.

〔effect〕

According to the configuration of the present invention, in a developing device in which two or more developing rollers are sequentially used as magnetic brushes, when an insulating layer is provided on the surface of a conductive base, leakage of a developing bias due to scratches on the surface of a photoreceptor is prevented. Has the effect of preventing the developer scribing failure due to the charge-up of the developing roller surface without impairing the pumping property and transportability of the developing roller,
In order to prevent the developing bias from leaking due to the damaged photoreceptor, the present invention has an advantage of a significant cost reduction as compared with the conventional means which requires replacement or restoration of the photoreceptor.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are enlarged views showing the formation of a coating layer for removing static electricity and the shape of the uneven portion in the developing roller having the uneven portion, and FIGS. 2 (a) and 2 (b) are FIGS. FIGS. 3A and 3B are graphs showing the relationship between the doctor gap and the amount of developer pumping corresponding to FIGS. 3A and 3B. FIGS. 3A and 3B show a conductive substrate of a developing roller and an insulating layer on the surface of the conductive substrate. FIG. 5 is a schematic cross-sectional view of FIG. 5A-A, FIG. 4 is a cross-sectional view of one embodiment of a color developing device to which the configuration of the present invention is applied, and FIG. 5 is an external view of a developing roller. 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 ... insulating layer,
2 ₃ …… Static removal paint layer, 2 _ab …… Uneven part, _2a …… Protrusion, 2 _b …… Concave part.

Claims (1)

(57) [Claims] 1. An electrophotographic developing device comprising a magnetic brush and a developing device for cutting off a magnetic brush for supplying a developing toner to a photoreceptor surface on which an electrostatic latent image is formed, wherein the developing toner is applied to the photoreceptor surface. A developing device for electrophotography, wherein a static elimination coating layer is formed on the surface of a convex portion of a substrate having an uneven shape to be supplied to a substrate.