JPS55135849A - Composite photoreceptor for electrophotography - Google Patents

Abstract

PURPOSE: To obtain a superior 2-color image without using any filter in imagewise exposure, by composing a first photoconductive layer of a specified charge generating layer and a specified charge transfer layer using 2 photoconductive layers different in sensitivity to a chromatic color light.

CONSTITUTION: Charge generating layer 21 containing copper phthalocyanine and a binder is formed on electroconductive substrate 1 and charge transfer layer 22 containing an electron donor and an electron acceptor is provided on layer 21 to form first photoconductive layer 2 having sensitivity to a chromatic color light (e.g., a red light). Second photoconductive layer 3 having sensitivity to the other chromatic color light (a nonred light) and transmitting the red light is formed on layer 2 to prepare a photoreceptor. This photoreceptor undergoes the following processes: e.g., negative first corona charging, uniform exposure to the red light, second corona discharge reverse to the first in polarity for charging as shown in figure (b), exposure to the light image of original 4 for bearing a latent image, and development of the surface with black toner 6 and red toner 5 reverse to each other in polarity in accordance with the polarities of the charged layers corresponding to the black, white, and red parts of original 4. Thus, a red and black 2-color image is obtained.

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