JPS569759A - Electrophotographic method - Google Patents

Abstract

PURPOSE: To enable 2-color copying as well as high-quality, stable single-color copying by conducting copying in a given process using a 3-layer structure photoreceptor.

CONSTITUTION: Photosensitive drum 10 composed of 3 laminated layers of a conductive substrate, a photoconductive layer chargeable to both polarities, and an insulating layer is negatively charged and illuminated by white light, imagewise exposed to light through red light shielding filter 6 at the same time as positive charging with secondary charging and simultaneously imagewise exposing unit 12, and subsequently exposed to light with imagewise exposing unit 13 provided with red light filter 8. As a result, negative and positive latent images are formed and developed with positive and negative red and black toners in the first and the second developing units 15 and 16 to conduct 2-color copying. On the other hand, drum 10 is positively charged with unit 11, illuminated by white light, negative by charged and imagewise exposed with unit 12 freed of filter 6, and further illuminated by white light with white light uniform exposing unit 14, thus permitting a positive stable latent image to be formed on the insulating layer, and to be developed with unit 16, and consequently 2-color copying as well as high quality stable single-color black copying to be effected.

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