JPS6145254A - Developing device - Google Patents

Abstract

PURPOSE:To prevent a deficiency in the conveyance amount of a developer by providing a developer carrier with a conductive layer and plural fine electrodes which are insulated electrically from the conductive layer and also insulated electrically from one another, and forming each fine electrode of particles dispersed in a conductive material. CONSTITUTION:A developer sleeve 5 has the conductive layer 8 which serves as a core agent, an insulating layer 9 laminated on it, and an electrode dispersed layer 11 which is laminated further thereupon; and this dispersed layer 11 has numbers of conductive fine electrodes 10 dispersed in an insulating material, e.g. epoxy resin. Therefore, respective fine electrodes 10 are insulated from one another and also insulated from the conductive layer 8, and they are placed in an electric floating state. Then, the fine electrodes 10 are put in the resin, so toner made of resin contacts fine electrodes made of the resin as well to cause the resin materials to contact each other, thereby the toner becomes easier to stick on fine electrodes 10. Thus, a deficiency in the amount of toner on the developer sleeve 5 which is conveyed to a development area is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a developer carrier carrying a one-component developer to be transported to a development area, and the carrier has a conductive layer and a conductive layer. The present invention relates to a developing device including a plurality of microelectrodes that are electrically insulated from each other and electrically insulated from each other.

BACKGROUND OF THE INVENTION It has been well known to use a developing device of the above type in an image forming apparatus such as an electronic copying machine or a printer. This developing device produces an effective edge effect during image formation, even when using a single-component developer that does not contain carrier, rather than a two-component developer that contains carrier and toner. It is possible to reproduce a shaped original image, that is, a line image, and a planar solid image in a state that meets the respective requirements (for example, Japanese Patent Application Laid-Open No. 57-1141
63), this effect is obtained by using a large number of conductive microelectrodes in an electrically floating state, and metal particles are most commonly used as these microelectrodes. However, when these metal particles are exposed on a developer carrier, the amount of developer carried on the carrier and transported to the development area is limited.

The amount becomes smaller than originally required, and there is a risk that the quality of the visible image formed will deteriorate.

One object of the present invention is to provide a developing device of the type described at the beginning, which eliminates the above-mentioned conventional drawbacks and prevents insufficient conveyance of developer.

The present invention proposes a configuration in which particles in which a conductive substance is dispersed is used as a microelectrode, and examples of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a case where the developing device according to the present invention is used in an electronic copying machine. Toner (or simply referred to as toner) is stored therein. tank 1
The toner 2 inside is stirred by an agitator 3, and a toner supply roller 4 rotates counterclockwise.

The structure of the developing sleeve 5, which is supplied to a developer carrier configured as a developing sleeve 5 rotating counterclockwise while in contact with the roller 4 (arrow A), will be described in detail later.

The toner supplied to the surface of the developing sleeve 5 is conveyed while being supported on the sleeve surface as the sleeve 5 rotates, and at this time, the toner is uniformly regulated to a predetermined thickness by the layer thickness regulating member 6.

The toner on the sleeve 5 that has passed through the layer thickness regulating member 6 forms a layer of toner having a predetermined thickness, and is charged to a predetermined polarity, for example, positively, by friction with the layer thickness regulating member 6. Therefore, when this single layer of toner reaches the developing area C facing the latent image carrier, in this example the photoreceptor 7, traveling in the direction of arrow B, it electrostatically transfers to the electrostatic latent image formed on the photoreceptor 7. Then, the latent image becomes a visible image.

As schematically shown in FIGS. 1 and 2, the developing sleeve 5 has a conductive layer 8 that also serves as a core material, an insulating layer 9 laminated thereon, and an electrode dispersion layer 11 laminated thereon. However, this dispersion layer 11 is made by dispersing a large number of conductive microelectrodes 10 in an insulating material, such as an epoxy resin. Therefore, each microelectrode 10 is insulated from each other.

It is also insulated from the conductive layer 8 and is in an electrically floating state.

By using the developing sleeve having the microelectrode 10, an effective edge effect can be obtained when visualizing a latent image even if a one-component developer is used, and the developing efficiency of line latent images in particular can be improved. be able to. Figure 3 is a graph showing the image density of the original to be copied on the horizontal axis and the density of the visible image obtained on the vertical axis. , I want a visible image with high density even when the density is low, as shown by the broken line X.

Conversely, from a planar solid image, it is normal to want to obtain a visible image with a density that corresponds to the density of the original image, as shown by the solid line Y, and a developing device using microelectrodes can meet this requirement. A matching or corresponding visual image can be formed. The principle is disclosed in detail in Japanese Patent Laid-Open No. 57-114163 mentioned above, and so the explanation thereof will be omitted here.

By the way, in order to enhance the function of the microelectrode 10, it has already been known that it is advantageous to expose at least a part of the microelectrode 10 on the surface of the developing sleeve 5 and bring the electrode 10 closer to the photoreceptor, as shown in FIG. Although it has been proposed, as described above, if metal particles such as copper particles are directly used as the microelectrode 10 and exposed on the sleeve surface, there is a risk that the amount of toner supported on the sleeve 5 will be insufficient. There is. Therefore, in the configuration according to the present invention, each microelectrode 10 is formed as follows. Namely.

As schematically shown in Figure 4, a conductive substance such as carbon black or metal powder is mixed with an insulating resin,
For example, it is dispersed in epoxy resin and
Grind into particles of about 150 μm.

This is used as the microelectrode 10. The entirety of such particles exhibits conductivity, and by dispersing them in the insulating material of the electrode dispersion layer 11 as shown in FIG. 2, they can be used as the microelectrode 10 without any problem. Moreover,
Even if the microelectrode IO is exposed on the surface of the sleeve 5, it will remain on the sleeve surface.

A required amount of toner can be attached, and deterioration in the quality of visible images due to insufficient amount of toner can be prevented.

The reason why the amount of toner adhering to the sleeve 5 can be increased as described above is not necessarily clear, but it is thought to be as follows.

Since the toner is made of resin, it is difficult to adhere to the metal particle microelectrodes directly exposed on the sleeve surface.

However, if the microelectrode 10 contains resin as shown in FIG. becomes easier to stick to. This fact has been confirmed by numerous experiments.

In addition to epoxy resin, appropriate resins such as acrylic and urethane can be used as the resin for dispersing conductive substances such as carbon black; In addition to epoxy resin, acrylic, urethane, acrylic-urethane,
A wide range of resins such as epoxy-silicon type and epoxy-Teflon type can be used as appropriate, but due to the frictional charging system, a resin that is separate from the toner is used, and the toner is also charged by the sleeve 5 or charged by the layer thickness regulating member 6. It is desirable to take care to prevent the charged state of the toner from becoming undesirable.

To manufacture the developing sleeve shown in Figure 2, an insulating resin with carbon black, metal, etc. dispersed therein is used.

For example, epoxy resin is crushed to create particles (Figure 4).
, these particles are further uniformly dispersed in the resin, and this is
Coating from above the insulating layer 9 laminated on the core material of the conductive layer 8,
After curing this, the outer peripheral surface is polished to obtain a sleeve 5 as shown in FIG.

Alternatively, for example, epoxy resin may be coated on the conductive layer 8 or the insulating layer 9 laminated thereon, particles may be uniformly scattered directly thereon, and the surfaces may be polished after being fixed.

Note that if an overcoat layer of an insulating resin is further laminated on the electrode dispersion layer 11, detachment of the microelectrodes 10 can be prevented.Moreover, even if metal particles are used as the microelectrodes, since the surface is made of resin, toner However, in order not to impair the effectiveness of the microelectrode, the thickness of the overcoat layer must be extremely thin, and it is difficult to coat such a thin layer with a uniform thickness. It is not easy to do so, and it inevitably increases the cost of the sleeve.

The insulating layer 9 shown in FIG. 2 adjusts the dielectric thickness from the conductive layer 8 to the photoreceptor 7 (FIG. 1) and adjusts the strength of the electric field formed between them. In some cases, the insulating layer may be omitted as shown in FIG.

Further, the conductive layer 8 does not necessarily have to be the core material of the sleeve 5; for example, as shown in FIG. 6, a cylindrical core material 14 may be provided below the conductive layer 8.

The entire developing sleeve 5 may be a rigid body, but at least a portion thereof, for example, FIGS. 2, 5, and 6
It is advantageous if each of the layers shown in the drawings and at least one of the overcoat layers are made of an elastic material to ensure smooth contact between the sleeve 5 and the photoreceptor 7 and to prevent damage to the photoreceptor.

For example, the resin used for the electrode dispersion layer 11 may be made soft by using an elastic epoxy resin, or the insulating layer 9 may be made of an elastic material such as rubber such as chloroprene rubber, foam, sponge, or elastic resin, as shown in FIG. The core material 14 can also be made of an elastic body such as elastic rubber, foam, or elastic epoxy resin.

The present invention can also be applied to a developing device using a magnetic component type developer (magnetic toner). Alternatively, a finely magnetized magnet called a rubber magnet or a plastic magnet may be integrally provided with the sleeve and driven to rotate. 1. The microelectrode according to the present invention can be used without any problem. Even when non-magnetic toner is used, the configuration in which various types of magnets are provided as described above can also be adopted in order to configure the regulating member with a magnetic material, attracting this with the magnet, and uniformly press the regulating member against the sleeve. . - In addition, when a developing sleeve having a microelectrode 10 is used, there is a risk that charge may accumulate on the microelectrode mainly due to the latent image charge on the photoreceptor 7, and if this is left untreated, the quality of the visible image will deteriorate. In the embodiment shown in FIG. 1, a power source 13 that applies a bias voltage to the sleeve 5 is connected to the static elimination brush 12 and the regulating member 6, and these members 12.6 remove the microelectrode IO or the insulating material around it. The static electricity is removed.

The present invention is widely applicable to a developing device having a developer carrier made of a belt, or to a developing device other than an electronic copying machine.

According to the present invention, with a simple configuration, it is possible to prevent the developer from running out on the developer carrier conveyed to the development area.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a developing device according to the present invention, FIG. 2 is an enlarged sectional view schematically showing a developing sleeve, and FIG. 3 is an enlarged sectional view schematically showing a developing sleeve.
The figure is a graph explaining the effect of the microelectrode, FIG. 4 is an enlarged schematic diagram of the microelectrode, and FIGS. 5 and 6 are sectional views similar to FIG. 2 showing other embodiments. 2...Developer 8...Conductive layer Diagram 1 procedure with opening (voluntary) November 19, 1980

Claims (1)

[Scope of Claims] A developer carrier carrying a one-component developer to be transported to a development area, the carrier being electrically insulated from a conductive layer and the conductive layer. A developing device comprising a plurality of microelectrodes that are electrically insulated from each other, wherein the microelectrodes are made of particles in which a conductive substance is dispersed in a resin.