JPH09197800A - Image forming device developing roller - Google Patents

Abstract

(57) Abstract: A developing roller used in a non-magnetic one-component system image forming apparatus is capable of obtaining an optimum amount of adhesion and an amount of charge on a developer carrier and capable of forming a better image quality. To do. SOLUTION: A large number of convex dielectric parts 11 made of fluorocarbon resin are formed on the outer circumference of an aluminum roller 10. Dielectric part 11
The base portion is embedded in the aluminum roller 10 and the top portion is projected from the outer peripheral surface of the aluminum roller 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing roller used in a developing device of an image forming apparatus such as a copying machine using an electrophotographic process, a plain paper facsimile and a printer.

[0002]

2. Description of the Related Art A developer carrying member having a dielectric portion whose surface is regularly or irregularly distributed in a minute area and a conductive portion which is grounded, and the developer carrying member are brought into contact with each other. A developing roller of an image forming apparatus having a developer supplying member that rotates in a rotating manner and which visualizes an electrostatic latent image by a developer carried on a developer carrying body is disclosed in, for example, JP-A-4-127177. There is a technique disclosed in the publication.

However, in the current developer carrier including the above-mentioned technique, the dielectric part and the conductive part are initially on the same plane for manufacturing reasons, but when completed, the dielectric part has a concave shape. Therefore, contact with the developer supply member may be insufficient, and the amount of insufficiently charged toner may increase. Also,
Since it is a hard roller, it is not suitable for contact development with a drum photoreceptor.

In view of the above-mentioned conventional problems, the present invention provides a developing roller for a non-magnetic one-component image forming apparatus capable of obtaining an optimum amount of adhesion and an amount of charge on a developer carrier and having a better image quality. The purpose is to provide.

[0005]

The developing roller of the image forming apparatus of the present invention according to claim 1 has a dielectric portion whose surface is regularly or irregularly distributed in a minute area, and a conductive portion which is grounded. And a developer supply member that rotates in contact with the developer carrying member, and visualizes an electrostatic latent image by the developer carried on the developer carrying member. In the developing roller of the image forming apparatus, the dielectric portion of the developer carrier is convex outward in the circumferential direction.

Further, the developing roller of the image forming apparatus according to the second aspect is characterized in that the dielectric portion of the image carrier is made of an elastic body.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments and examples of a developing roller of an image forming apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a view showing the periphery of a developing roller of an image forming apparatus to which the present invention is applied. In the figure, 1 is a photoconductor, 2 is a developing roller, 3 is a toner supply roller, 4 is an agitator, and 5 is a layer thickness leveling member. The photoconductor 1 rotates in the direction of the arrow at a linear velocity of 120 mm / sec, for example, and the developing roller 2 rotating at the same linear velocity with the photoconductor 1 at a predetermined developing gap (for example, 0.1 mm) has a developing area 6 After the development is completed, the toner rotates in the direction of the arrow and reaches the contact portion with the toner supply roller 3.

The toner supply roller 3 rotates in the forward direction at a linear velocity approximately 0.5 to 1.0 times that of the developing roller 2, and friction with the developing roller 2 charges the minute dielectric portion of the developing roller 2. A microfield is formed on the developing roller 2, the toner attached to the toner supply roller 3 is charged, and the charged toner is electrostatically adsorbed to the microfield on the developing roller 2 and is attached in multiple layers. The developing roller 2 further rotates, and the layer thickness leveling member 5 uniformly controls and regulates the thickness of the adhered toner, and reaches the developing area 6 again.

2A and 2B are views showing the constitution of the first embodiment of the developing roller of the image forming apparatus according to the present invention. FIG. 2A is a sectional view and FIG. 2B is a plan view showing the arrangement of the dielectric portion. is there. In the developing roller of this embodiment, as shown in FIG. 2A, a large number of convex dielectric parts 11 made of a fluororesin are formed on the outer periphery of an aluminum roller 10 having a diameter of 25 mm, for example.
The dielectric portion 11 has a base portion buried in the aluminum roller 10 by 100 μm and a top portion projected by 100 μm from the outer peripheral surface of the aluminum roller 10. The layout is
As shown in FIG. 2B, for example, the pitch is 300 μm,
The distance is 130 μm.

As a method of manufacturing such a developing roller,
A method of thermally expanding as shown in FIG. 3 and a method of forming a surface by etching as shown in FIG. 4 can be adopted.

In the method of thermal expansion shown in FIG. 3, a large number of concave portions 12 are formed on the surface of the aluminum roller 10 and then the dielectric portion 11 is formed.
The fluororesin (including thermally expandable microcapsules) 13 and the fluororesin 14 for forming the composition are sequentially coated, dried at 100 ° C. for about 30 minutes, and then, as shown in FIG.
As shown in (A), the roller surface is cut to expose the conductive surface (the surface of the dielectric portion is dented), and then at about 160 ° C for about 1
Heat for 0 minutes. Then, as shown in FIG. 3B, the fluororesin is softened and the microcapsules expand (diameter 15 μm is 50 μm) to form the dielectric portion 11. As the fluorine-based resin, for example, Lumiflon LF200 manufactured by Asahi Glass, and as the microcapsule, for example, Expancel DU (461) manufactured by Nippon Ferrite can be used.

In the method of forming the surface by etching as shown in FIG. 4, a large number of concave portions 12 are formed on the surface of the aluminum roller 10, and then a fluorine-based resin 14 for forming a dielectric portion is coated on the surface of the aluminum roller 10. As shown in FIG. 4C, the roller surface is cut to expose the conductive surface, and the aluminum portion is removed by etching to make the fluorine-based resin 14 convex as shown in FIG. As shown in FIG.

In the case of the developing roller of this embodiment, since the dielectric portion 11 has a convex shape on the outer side in the circumferential direction of the roller,
The contact between the dielectric portion 11, the toner and the toner supply roller 3 was improved, and when the toner was used experimentally, the amount of insufficiently charged toner was reduced. Further, since the surface area of the dielectric part 11 is increased, the toner adhesion amount is increased. As a result, the degree of reverse bias background stain is improved, and even if an image having a high image area ratio is output, the density is lowered during the output. Has decreased. FIG. 5 shows how the toner 15 adheres to the developing roller, and FIG. 6 shows the difference in toner charge distribution. 5 (A) and 6 (A) where the dielectric portions are not convex, FIG. 5 (B) and FIG.
(B) shows the case where each of the dielectric portions has a convex shape.

FIG. 7 is a sectional view showing the structure of the second embodiment of the developing roller of the image forming apparatus according to the present invention. The developing roller according to the present embodiment is suitable for use in an image forming apparatus in which the amount of the dielectric portion that penetrates into the photoconductor 1 during development is set to, for example, 0.1 mm. And a fluorine-based resin 14 having a thickness of, for example, about 10 μm.

As a method of manufacturing such a developing roller,
A method of thermally expanding as shown in FIG. 8 can be adopted, and the forming method is the same as that in the case of FIG.

The developing roller of this embodiment exhibits the same performance as that of the developing roller of the previous embodiment, but even if the developing roller of the present embodiment comes into contact with the drum-shaped photosensitive member 1 due to the elasticity of the silicon rubber 16, It is possible to perform contact development in which neither roller 2 is damaged and an image with better reproducibility is obtained than in non-contact development.

[0017]

In the developing roller of the image forming apparatus according to the first aspect of the present invention, since the dielectric portion is convex outward in the circumferential direction, the contact between the dielectric portion, the toner and the toner supply member is improved, This has the effect of reducing toner that is insufficiently charged. Further, since the surface area of the dielectric portion increases, the toner adhesion amount increases, and as a result, the degree of reverse bias background stain is improved, and even if an image with a high image area ratio is output, the density may drop during output. There is an effect of decreasing.

In the developing roller of the image forming apparatus according to the second aspect, since the dielectric portion is an elastic body, in addition to the common effects described above, both the photosensitive body and the developing roller are damaged even when they come into contact with the photosensitive body. The effect is that contact development can be performed without any problem and an image with better reproducibility can be obtained than in non-contact development.

[Brief description of drawings]

FIG. 1 is a diagram showing a periphery of a developing roller of an image forming apparatus to which the present invention is applied.

FIG. 2 is a first development roller of the image forming apparatus according to the present invention.
2A and 2B are views showing the configuration of the embodiment of FIG.
FIG. 4 is a plan view showing a disposition state of a dielectric portion.

3A and 3B are a sectional view and a perspective view showing a manufacturing method by thermal expansion of the developing roller of the embodiment of FIG.

FIG. 4 is a cross-sectional view showing a method of manufacturing the developing roller of the embodiment of FIG. 2 by etching.

FIG. 5 is a cross-sectional view showing how toner adheres to the developing roller when the dielectric portion is concave and when the dielectric portion is convex as in the embodiment of FIG.

6 is a diagram showing a difference in toner charge distribution when the dielectric portion is concave and when it is convex as in the embodiment of FIG.

FIG. 7 is a second development roller of the image forming apparatus according to the present invention.
It is sectional drawing which shows the structure of 1st Embodiment.

FIG. 8 is a cross-sectional view showing the manufacturing method by thermal expansion of the developing roller of the embodiment of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Development roller 3 Toner supply roller 4 Agitator 5 Layer thickness leveling member 6 Development area 10 Aluminum roller 11 Dielectric part 12 Recesses 13 and 14 Fluorine resin 15 Toner 16 Silicon rubber

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Akira Sawada 1-3-3 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (2)

[Claims] 1. A developer carrying member comprising a dielectric part whose surface is regularly or irregularly distributed in a small area and a conductive part grounded, and a developer supplying member which rotates in contact with the developer carrying member. And a developing roller of an image forming apparatus for visualizing an electrostatic latent image with the developer carried on the developer carrying body, the dielectric part of the developer carrying body is projected outward in the circumferential direction. A developing roller of an image forming apparatus having a shape. 2. The developing roller for an image forming apparatus according to claim 1, wherein the dielectric portion of the image bearing member is made of an elastic material.