JPS5860770A - Magnetic brush developing device - Google Patents

Abstract

PURPOSE:To prevent the bad influence upon the image quality, by providing conductive split electrodes in a developing sleeve and forming these electrodes with a binding material including conductive fine particles to prevent these electrodes from break away. CONSTITUTION:A developing sleeve 5 incorporating a magnet 4 is provided so as to face closely to a photoreceptor 1 of a developing device. In respect to the developing sleeve 5, a conductive base material 12 is used as a base, and conductive split electrodes 15 which are split by an insulating net 14 on an insulating thin film 13, are provided on this base. In this case, conductive fine particles are dispersed in a binding material to give a specific resistance of <=10<12>OMEGAcm to conductive split electrodes 15 and 18. Thus, the bonding force between electrodes and the insulating material which separates them from one another is increased to prevent electrodes from break away, and the bad influence upon the image quality is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic brush developing device using a -component developing agent.

Conventionally, this type of developing device often uses a developing sleeve. For example, as shown in U.S. Pat. No. 3,246,629, an insulating coating is provided on the conductive developing sleeve, and this Some conductive dispersed electrodes are constructed by dispersing conductive powder such as iron powder into the resin that constitutes the coating. In addition, Japanese Patent Application Laid-Open No. 54-158197 proposed by the applicant
As shown in the above publication, there is also a device in which a conductive divided electrode formed by a plurality of conductors arranged in the circumferential direction is provided on the front side of a non-magnetic insulating sleeve. However, since such a dispersion electrode is made of a conductive material with a particle size of several tens to several hundred micrometers, each divided electrode is made of a single conductive material, and each dispersion electrode or divided electrode is separated. The bonding force with the insulating material is small, causing problems such as detachment of these electrodes, which has an adverse effect on image quality, such as density unevenness.

The present invention was made in view of these points.

It is an object of the present invention to provide a magnetic brush developing device which can prevent detachment of a current sleeve having conductive dispersion electrodes or conductive divided electrodes. .

The present invention is configured such that by forming the electrodes from a binding material containing conductive fine particles, the bonding force with the insulating material separating each electrode can be increased and the detachment of the electrodes can be prevented. This is what I did.

An embodiment of the present invention will be described based on the drawings.

First, a drum-shaped photoreceptor (1) is placed on a grounded conductive layer (2).
) and a photosensitive layer (3), and rotates in the direction of the arrow. A developing sleeve (5) having a built-in magnet (4) is provided in close opposition to the photoreceptor (1). In this embodiment, it is assumed that the developing sleeve (5) rotates in the direction of the arrow.
The magnet (4) side may rotate. This developing sleeve (5) is provided in a hopper (7) containing a high-resistance toner (6) as a developer, and by conveying the toner (6) by the rotation of the developing sleeve (5), the toner (6) is transferred onto the photoreceptor (11). The hopper (7) is equipped with a developing sleeve (5).
A doctor (G) for regulating the thickness of the upper toner (6) layer is provided, and a stirring blade (C1,) is further provided.

Here, as the developing sleeve (5), as shown in FIG. 2 (α), a conductive substrate (preferably non-magnetic) (
2) as a base, an insulating thin film α3 (preferably less than rooμm) is provided on this conductive substrate (2), and a conductive divided electrode Q divided by an insulating network α4 is formed on this insulating thin film 03. It is constructed in such a way that there is a

The insulating net 4 is preferably a synthetic fiber net of 100-800 mesh. Here, the conductive substrate (6) is connected to a developing bias power supply αQ. This figure 2 (a
According to the developing sleeve (5) shown in ), the developing electrodes are separated from each other and are in a floating state because they are separated from each other and are interposed between the conductive substrate θ and a thin insulating thin film, and an appropriate float bias is applied. Since it is superimposed on the bias voltage, it is effective in obtaining images with less background smudge and excellent low contrast reproducibility.

Furthermore, the developing sleeve (5) can also be constructed as shown in FIG. 2 (6). That is, a conductive substrate (b) is used as a base, an insulating support made of resin or rubber for electrode division is provided on this conductive substrate α, and conductive parts divided in the circumferential direction are provided on the surface of this insulating material α. It is equipped with sex-dividing electrodes. According to the developing sleeve (5) shown in FIG. It is possible to optimize the electrode potential during injection without affecting the electrode during development, resulting in a high density and good image. can be obtained.

Here, the doctor gap DG is preferably 0.5 or less, and the development gap pa is 0.0 as the toner particle size increases.
1m to 1. OB grade is preferable.

Therefore, in this example, the conductive divided electrode (g) Ql is one in which conductive fine particles are dispersed in a binding substance to have a specific resistance of 1012Qc1n or less, and preferably the volume content of the conductive fine particles is 10vol! % or more. As the conductive fine particles, fine powders of carbon, iron, nickel, aluminum, etc. are used.

Its volume is much smaller than that of each electrode Cl5CI barrel, and preferably its particle size is 1 μm or less. Also,
As the material for binding the conductive fine particles, resins such as epoxy resin, polyurethane 11&, cellulose resin, polyether, or rubbers can be used, similar to the insulating material for electrode division.

In this way, each segmented electrode (c) a barrel is formed from a binding material containing extremely fine conductive particles, so compared to conventional methods, the insulating network separating the segmented electrode (g) The conductive split electrode (2) has a strong bond with CI4, insulating material αη, etc., and a camphor developing sleeve (5)
Even if desorption occurs, only the conductive fine particles in the outermost layer will be desorbed, and the image quality will not be adversely affected.

By the way, the melting point of the binding material that makes up the split electrode is the melting point of the insulating material used to split the electrode. - If the temperature is also lowered, at the time of manufacturing, first a recess is made on the surface of this insulating material, and the recess is filled with cross-wire pulverized particles of the binding material and conductive fine particles, and heated and melted. The divided electrodes that are the object of the present invention can be easily formed.

In the present invention, as described above, the conductive dispersion poles or the conductive divided electrodes are formed using a binding material containing conductive fine particles, so that the bonding force with the insulating material separating each electrode is increased. It is possible to prevent its detachment, and therefore, it is possible to eliminate the adverse effect on image quality.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic longitudinal sectional side view, and FIGS. 2(a) (4)h are partially enlarged perspective views. 1... Photoreceptor, 5... Current sleeve, 15... Conductive split electrode, 18... Conductive split electrode hanging person Ricoh Co., Ltd. )

Claims (1)

[Claims] In our magnetic brush development apparatus, a developing sleeve that rotates close to the photoreceptor and conveys developer is provided with a conductive electrode or a conductive divided electrode. A magnetic brush developing device characterized in that: