JPS5543579A - Photoreceptor for electrophotography - Google Patents

Abstract

PURPOSE: To turn a dichromatic original into latent image and visible image by one exposure alone, by specifying the photoreceptor and charging and exposing methods.

CONSTITUTION: A photoreceptor 1 having a first photoconductive layer 11, which has sensitivity to light of color A, e.g., red color light under the state of positive charge and possesses electron or Hall transporting ability, and a second photoconductive layer 12, which has sensitivity to light of color B, e.g., blue color light and has scarce sensitivity to the red color light under the state of negative charge, transmits red color light, and possesses both positive and negative charging characteristics, laminated on a conductive substrate 10 is positively charged by a charger 2 under uniform radiation of red color light. Then, negative charge is applied by a charger 3, and a white color picture image is exposed. The potential of the photoreceptor surface corresponding to the white color part of the original is nearly 0. In the unexposed part, the negative surface potential due to secondary charging is preserved. The part corresponding to the red color part of the original returns to the state of primary charge, so that positive potential appears. Respective latent images thus formed are developed by developers for red color and blue color, TR, TB, which are of reverse polarity to the latent images.

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