Electrophotography – Image formation – Development
Patent
1998-10-23
2000-03-07
Pendegrass, Joan
Electrophotography
Image formation
Development
430120, G03G 1508
Patent
active
060351721
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a developing roller employed in a developing device which is incorporated in electrophotographic apparatus such as duplicators, printers, receivers for facsimiles or the like, and precisely to a non-magnetic developing roller employed in a developing device in which toner carried on the surface of the roller being or not being kept in contact with a photoreceptor is transferred at least to the photoreceptor.
BACKGROUND OF THE INVENTION
Electrophotography is grouped into two types; in one type, employed are both magnetic working force and electric working force for the transference of developers, while in the other type, employed is only electric working force. In the former type where both magnetic working force and electric working force are employed, any of two-component developers comprising magnetic carrier and non-magnetic toner, or one-component developers comprising only magnetic toner may be used. As opposed to this, in the latter type where only electric working force is employed, one-component developers comprising only non-magnetic toner (hereinafter referred to as non-magnetic one-component developers) may be used.
FIG. 2 shows the constitution of a developing device and its peripheral devices in a printer or a duplicator in which is used a non-magnetic one-component developer. The illustrated constitution is first described below.
On the surface of a photoreceptor 1, which is an electrostatic latent image-carrying device, a photoconductive insulating layer is formed. The photoconductive insulator for the layer is a substance which is electrically insulating in ordinary condition but, when exposed to light, becomes conductive. The photoreceptor 1 rotates in the rotating direction 1a, and its surface is uniformly charged by the charger 2.
When the surface of an original manuscript is scanned with light, the surface of the photoreceptor 1 is exposed to the reflected light via an optical system (not shown) in the direction 10, whereupon the exposed site of the surface of the photoreceptor 1 becomes conductive to lose the charge, and an electrostatic latent image is formed on the surface of the photoreceptor 1. For example, in a laser printer, the exposure 10 is effected by optical beams of which the strength is modulated in accordance with the image to be recorded. In a duplicator, the reflected light that results from the optical scanning of the surface of an original manuscript is led to the surface of the photoreceptor 1 via an optical system, by which the surface of the photoreceptor 1 is exposed as in 10. When the charged powdery toner of a non-magnetic one-component developer is transferred by the developing roller 33 onto the electrostatic latent image formed on the surface of the photoreceptor 1, the latent image is developed into a visual image.
The toner having been transferred onto the surface of the photoreceptor 1 is further transferred onto recording paper 4. In this transferring step, electrostatic attraction is applied to the back surface of the recording paper 4 by means of the transfer device 5. A cleaning device 6 such as a cleaning blade or the like is disposed around the photoreceptor 1 in the site downstream the transfer device 5 in the rotating direction 1a. The cleaning device 6 is to remove the toner having been adsorbed on the surface of the photoreceptor 1 but not transferred onto the recording paper 4, from the surface of the photoreceptor 1.
The recording paper 4 onto which the toner has been transferred is conveyed to a fixing device 7. The fixing device 7 comprises a hot roller 8 and a pressure roller 9, between which the recording paper is passed so that the transferred toner is fixed on the recording paper 4.
The developing device 3 is so constructed that the toner container 31 that contains toner 12 therein is combined with the developing roller 33, in which the surface of the developing roller 33 is contacted with the photoreceptor 1 whereby the toner 12 is transferred onto the surface of the photorecept
REFERENCES:
patent: 4505573 (1985-03-01), Brewington et al.
patent: 5270786 (1993-12-01), Kikuchi et al.
Fukuda Susumu
Kobayashi Kenji
Mimura Kazuyoshi
Ogoshi Hiroshi
Tawada Yoshihisa
Kaneka Corporation
Pendegrass Joan
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