JPS5859474A - Magnetic brush developing device - Google Patents

Abstract

PURPOSE:To reduce the devloper filming and prevent an electrode from coming away, by providing a prescribed insulating thin film covering uniformly the surface of a developing sleeve and smoothing the surface of the developing sleeve to reduce the load given to the developer. CONSTITUTION:An insulating thin film 21a covering conductive dispersing electrodes 14a and an electrode dispersed layer 15a is provided on the surface of a developing sleeve 5a. By this constitution, the surface of the developing sleeve 5a becomes smooth because the surface of the outermost layer is covered with the insulating thin film 21a through the developing sleeve 5a has two kinds of materials of conductive dispersing electrodes 14a and the electrode dispersed layer 15a. Consequently, the load given to a toner in a developing vessel 11 having a blade 9 and an agitating means 10 is reduced to lessen the toner filming. A magnetic brush is formed on an insulating layer 21 of the sleeve by a magnetic pole 4 to develop the latent image on a photosensitive layer 2 of a photoreceptor 3.

Description

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

Generally speaking, in this type of developing device, as shown in FIG. A developing sleeve (5) with a built-in developer (4) is provided, and in front of the developing sleeve (5), a magnet (4) is rotated to convey the developer (6), and the developer (6) is transferred to the surface of the photoreceptor (3). The latent image (7) is developed as a toner image (8). Here, (9) is a doctor that regulates the layer thickness of the developer (6) on the developing sleeve (5), and αq is a stirring blade provided in the hopper α3. Also, (6)
is the developing bias power supply.

In this case, according to U.S. Pat. No. 3,246,629, conductive particles such as iron powder, aluminum, copper, nickel, etc. It is known that the developing sleeve (5a) is provided with an electrode dispersion layer (15a) formed of dispersed resin, rubber, etc. as a dispersion electrode (14a).

Figure 1) shows a modification in which an insulating layer (16a) is interposed. In this way, by optimizing the developing electric field and reducing the effective developing efficiency, an image with good low contrast reproducibility and good gradation can be obtained.

In addition, as shown in FIG. 3, a nonmagnetic insulating base (174)
Conductive divided electrodes (184) are arranged circumferentially on the surface of the doctor (94), and a current collector (194) and a bias power source are grounded and can contact the conductive divided electrodes (184) near the doctor (94). (124) and a current collector (204) that can contact the conductive divided electrode (184) at the development position near the photoreceptor (3) is proposed by the present applicant in Japanese Patent Laid-Open No. 54 It is known from the publication No.-158197. According to this, the electrode potential of a part of the doctor and the electrode potential of the development position can be set to different values, so, for example, the electrode potential when injecting with the injection electrode can be optimized, and at the same time, the influence of this can be applied to the electrode during development. It is possible to optimize the potential of the electrode during development without applying a high concentration, and a good image with high density can be obtained.

However, in the case of these conventional methods, the developing sleeve (5
a) (54) has two types of materials exposed on the surface: a conductive dispersion electrode (14a), an electrode dispersion layer (15a), a conductive split electrode (No. 18), and a nonmagnetic insulating substrate (17+), respectively. Therefore, the surface becomes uneven, and as a result, a large load is applied to the developer toner, and toner filming, which has an adverse effect on the image such as density unevenness, is likely to occur.

In addition, a conductive distributed electrode (14a) and a conductive divided electrode (14a)
84) may come off from the developing sleeves (56) (54).

The present invention has been made in view of the above-mentioned problems, and it prevents detachment of the electrodes of a developing sleeve having conductive dispersed electrodes or conductive divided electrodes, and improves image quality due to developer filming on the surface, etc. The object of the present invention is to provide a magnetic brush developing device that can reduce the adverse effects of.

The present invention provides a predetermined insulating thin film that uniformly covers the surface of the developing sleeve, thereby smoothing the surface of the developing sleeve, reducing the load on the developer, and reducing developer filming. In addition, the structure is such that detachment of the electrode can be prevented.

An embodiment of the present invention will be described based on FIGS. 4 and 5. 1, and the same parts as those shown in FIG. 3 are denoted by the same reference numerals, and explanations thereof will be omitted. This example is shown in Figure 2 (
This is applied to the a1 method, and the developing sleeve (5a)
A conductive dispersion electrode (14g) and an electrode dispersion layer (
15a) is provided with an insulating thin film (21a) covering it. Here, the doctor gap DG is preferably α5mj or less, and the development gap Po is from α0IIUl to 1.5mj, which is about the toner particle size. Approximately out is preferable. The developer (6) is styrene, vinyl ester, a-
Methyl aliphatic monocarboxylic acid esters, vinyl ethers, vinyl ketones, N-vinyl compounds, etc. or copolymers or mixtures thereof, rosin-modified phenol-formalin resins, epoxy resins, polyurethane resins, cellulose resins, polyethers Although the resin, polycarbonate resin, epoxidized phenol/formaldehyde resin, polyolefin resin, polyamide resin, rubber, etc. are the constituent elements, the insulating thin film (21M) is equivalent to or It is made of resin or rubber with higher specific resistance. More preferably, the resin constituting the developer and this insulating thin film (21g) can be made of the same material. In addition, the film thickness of the insulating thin J[(21a) is very thin compared to the layer thickness of the developer (6) (preferably 30 μm to 10 μm),
Preferably, the average film thickness is 2 μm or less.

According to such a configuration, even if the developing sleeve (5a) has two types of substances, the conductive dispersion electrode (14a) and the electrode dispersion layer (tSa), the outermost layer surface is covered with the insulating thin film (21a).
), giving it a pure surface. Therefore, the load on the toner is small, toner filming is reduced, and the negative effect on image quality is reduced.

Furthermore, since the conductive dispersion t* (14a) is almost completely covered with the insulating thin film (21a), even if this electrode is large or made of magnetic material, the developing sleeve (5a) I'm worried that I'll break away from ＼
do not have. Furthermore, since this insulating thin film (21a) has high resistance and is very thin, the creeping resistance on the surface of the developing sleeve (5a) is high enough to secure the conductive dispersion electrode (14a), and the thickness is The thin film resistance in the direction is not so large as to have a large effect on the development gap and development characteristics.In the end, the resistance of this insulating thin film (21a) has little effect, and it is possible to achieve high density and good gradation. An image is obtained. In this case, if the insulating thin film (21a) is made of the same material as the developer resin, toner filming can be further prevented, and even if filming occurs, problems such as uneven development are unlikely to occur. be.

Figures 6 and 7 are 1, Figures 2 (4) and 3, respectively.
This shows a modification applied to the diagram method. Here, in FIG. 7, the developing sleeve (s4) Fi insulating base (
17+) has a non-magnetic conductive support layer (22+) on the inner peripheral side, and this conductive support layer (224) is connected to the development bias power supply VBI (234), and the conductive division on the surface side The electrode (184) is the developing bias power supply VB!
(1u). Here, the potential of the conductive divided electrode (184) after development is made uniform, and VB
2 may be a static elimination power source. Note that the conductive divided electrode (184) may be a fine float electrode (preferably finer than 200 meshes) that is also divided in the axial direction, and in this case, the developing bias power supply VB, (
124) is unnecessary.

In the present invention, as described above, the surface of the developing sleeve is provided with an insulating thin film coated with a substance having a resistivity higher than that of the resin constituting the developer, so the surface of the developing sleeve 16 is smoothed and the load applied to the developer is reduced. Therefore, it is possible to prevent developer filming and eliminate negative effects on images, and it is also possible to prevent the electrode from detaching from the developing sleeve. If it is made as thin as possible, the influence of the resistance of this insulating thin film will be reduced, and images with high density and good gradation can be obtained.

[Brief explanation of drawings]

Figure 1 is a vertical side view schematically showing the developing device, and Figure 2 (α
) Body) is a partially enlarged vertical sectional side view showing an example of the conventional model.
Fig. 3 is a partially enlarged vertical sectional side view showing the other side of the conventional
FIG. 4 is a schematic longitudinal sectional side view showing one embodiment of the present invention, and FIG.
The figure is a longitudinal side view showing an enlarged view of the main part, and FIGS. 6 and 7 are longitudinal side views showing modified examples. 3... Photoreceptor, 5... Developing sleeve, 6... Developer, 14a... Conductive dispersion electrode, 184... Conductive divided electrode, 21... Insulating thin film procedure amendment form ( Voluntary) November 11, 1931, Haruki Shimada, Commissioner of the Japan Patent Office1, Indication of the case 1982 Patent Application No. 1592582, Title of the invention3, FdiTE Kess, Inc. Related to Magnetic Pushbutton Development Retention Incident 7 Patent Applicant, i,ll#', deceased 1-3 Nakamagome, Ota-ku, Tokyo
No. 6 No. 4 Deputy Attorney 〒107 Name t211 Patent Attorney Akira Aiki 5,
Date of amendment order None 8 Contents of amendment As shown in the attached sheet, the description and drawings of this application are amended as follows. Note 1: In the specification, on page 7, line 11 or line 12, the re surface side is connected. "The conductive split electrode (1sJ) on the surface side is connected to the development bias power supply Vm * (IN) via the current collector (2 drums) at the end not covered by the insulating thin film (214). .” 2.Amend Figure 7 in the drawings as shown in the attached sheet.

Claims (1)

[Scope of Claims] L A magnetic brush developing device in which a developing sleeve that rotates close to a photoreceptor and conveys developer is provided with a conductive dispersed electrode or a conductive divided electrode, in which a developer composition is formed on the surface of the developing sleeve. A magnetic brush developing device comprising an insulating thin film coated with a substance having a resistivity higher than that of a resin. 2. The magnetic brush developing device according to claim 1, wherein the thickness of the insulating thin film is set to be equal to or less than the thickness of the developer layer conveyed by the developing sleeve.