JPS60233676A - Developing device using nonmagnetic one component developer - Google Patents

Abstract

PURPOSE:To prevent uneven density even during use for a long period by maintaining a developer carrying body and a layer forming auxiliary member at same potential. CONSTITUTION:A bias power supply 5 is connected to the carrying body 5 and the layer forming auxiliary member 4 to maintain both at same potential. The member 4 is rubbed with the body 5 to triboelectrify the developer always to a proper polarity. Therefore, a prescribed amt. of developer is always fed, and the rest of the developer can be recovered from the body 5. As a result, an amt. of developer to be conveyed with the body 5 can be made always uniform and a reproduced image free from uneven density and image whitening can be stably formed.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a non-magnetic component developing device for developing an electrostatic latent image formed on an image bearing member using a non-magnetic component developer. be.

(Prior Art) In this type of developing device, in order to improve the reproducibility of high-density, wide-area solid black images, a layer-forming auxiliary member is provided on the carrier as shown in FIG. For this purpose, developer is supplied and collected.

In FIG. 1, first and second blades 3-1 and 3-2 are fixed to both sides of an opening 2a of a hopper 2 that stores the developer 1, and the lower part of the hopper 2 carries the developer 1. The carrier 5 and the layer forming auxiliary member 4 are in pressure contact with each other and are rotatably provided, and the first blade 3-1 is in contact with the carrier 5, and the second blade 3-2 is in contact with the layer forming auxiliary member 4. A holder 7 holding an electrostatic latent image 6 is rotatably provided facing the carrier 5, and a bias voltage obtained by superimposing an AC voltage on a DC voltage is applied to the carrier 5 by a bias power supply 8. That's how it is.

The developer 1 is a non-magnetic component type developer, in which a polarity control agent such as a pigment such as carbon or a metal-containing azo dye is dispersed in various thermoplastic resins such as styrene resin or acrylic resin.
It is made into a size of 5 to 20μ by crushing and classification, and in some cases, hydrophobic silica may be added to the developer particles in an amount of 0.5 to 2.0% by weight to improve fluidity. be.

The first blade 3-1 is a stainless steel plate with a predetermined thickness,
The second blade 3-2 serves as a layer forming member that presses against the carrier 5 with a predetermined contact pressure to form a thin layer of the developer 1 with a predetermined thickness, and the second blade 3-2 prevents the developer 1 from spilling. It is in contact with the layer forming auxiliary member 4 with a certain linear pressure.

The layer forming auxiliary member 4 includes an elastic body 4 on a metal core 4a.
b has a cylindrical shape and is pressed against the surface of the carrier 5 with a predetermined pressure.

The developer 1 in the hopper 2 is supplied by gravity onto the elastic body 4b of the layer formation auxiliary member 40 and onto the carrier 5, and is triboelectrically charged by the rubbing between the layer formation auxiliary member 4 and the carrier 5. After being applied, the developer is sent to the first blade 3-1 (layer forming member), and a thin developer layer of a predetermined thickness is formed by the first blade 3-1. Frictional electrification is also applied between the carrier 5 and the carrier 5 to give an electric charge. For this reason, the developer layer becomes sufficiently charged.

This developer layer is sent to the holder 7 by rotating the carrier 5 while applying a bias voltage to the carrier 5, and the electrostatic latent image is formed by the electric field between the electrostatic latent image 6 and the carrier 5. 6, and as a result, the electrostatic latent image becomes a visible image.

However, in such a developing device, the potential of the layer forming auxiliary member is in a floating state, and there is a potential difference between it and the carrier, so that appropriate triboelectric charging is not performed due to rubbing with the carrier, resulting in poor development. This causes problems such as the agent electrostatically adhering to the surface of the layer-forming auxiliary member. Such problems occur particularly when used for a long period of time, and as a result, the amount of developer supplied to the carrier becomes uneven, resulting in uneven density, white spots, etc. in reproduced images, and the image quality is significantly degraded.

(Objective of the Invention) The object of the present invention has been made to eliminate such drawbacks, and to provide a non-magnetic material that does not cause density unevenness even after long-term use and can always obtain high-quality reproduced images. - To provide a component developing device.

(Structure of the Invention) The non-magnetic component developing device of the present invention supplies a developer to a carrier, forms a thin layer of developer on the carrier by a layer forming member, and applies an electric charge to the developer. The layer is sent to a carrier holding the electrostatic latent image, a developer is applied onto the electrostatic latent image to develop it into a visible image, and a thin layer of the developer is further formed on the carrier by the layer forming member. In a developing device provided with a layer forming auxiliary member for supplying and collecting developer to and from the carrier, the carrier and the layer forming auxiliary member are held at the same potential prior to the development. That is.

(Example) Examples of the present invention will be described below with reference to the drawings.

FIG. 2 shows an embodiment of the present invention, in which the present invention is applied to the apparatus shown in FIG. As shown in the figure, in this example, a bias power supply 8 for applying a bias voltage to the carrier 5
By electrically connecting the support member 5 and the layer formation auxiliary member 4 and applying a bias voltage to the layer formation auxiliary member 4, the potentials between the carrier 5 and the layer formation auxiliary member 4 are made the same.

With this configuration, the layer forming auxiliary member 4 can always frictionally charge the developer to an appropriate polarity by rubbing against the carrier, so that a predetermined amount of developer is always applied to the carrier 5. The developer remaining after development can be recovered from the carrier. Therefore, the amount of developer conveyed by the carrier is always uniform, and the quality of the reproduced image is maintained without uneven density or white spots.

In this embodiment configured as described above, the present inventor used a material in which conductive carbon was dispersed in phenol resin as the carrier 5, and a material in which conductive carbon was dispersed in ethylene propylene rubber as the layer forming auxiliary member 4. resistivity to 10
A selenium (Se) based photoreceptor was used as the holder 7 for the electrostatic latent image, and its surface potential was set to (10)900■, and the electrostatic latent image was continuously applied 100,000 times. I made a copy. As a result, no density unevenness or white spots occurred in the reproduced images, and high-quality reproduced images were always obtained.

(Effects of the Invention) As explained above, according to the present invention, in a non-magnetic component developing device equipped with a layer formation auxiliary member, the developer carrier and the layer formation auxiliary member are held at the same potential. Therefore, even after long-term use, density unevenness does not occur, and high-quality reproduced images can always be obtained. Therefore, it is possible to provide a developing device that does not require maintenance or inspection even after long-term use.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a developing device equipped with a conventional layer forming auxiliary member, and FIG. 2 is a schematic diagram of a developing device according to an embodiment of the present invention. 1 developer, 2 hopper, 3-1 blade (layer forming member), 4 layer forming auxiliary member, 5 carrier, 6 electrostatic latent image, 7 holder, 8 bias power source. Patent applicant Fuji Xerox Co., Ltd.

Claims (1)

[Claims] A developer is supplied to the carrier, a layer forming member forms a thin layer of the developer on the carrier and gives an electric charge, and this developer charge is sent to the carrier holding the electrostatic latent image, and the electrostatic latent image is transferred to the carrier. Before depositing a developer on the image and developing it into a visible image, and further forming a thin layer of developer on the carrier by the layer forming member, supplying and recovering the developer to the carrier. 1. A non-magnetic component developing device, characterized in that the support member and the layer forming assisting member are held at the same potential.