JPS55135848A - Composite photoreceptor for electrophotography - Google Patents

Abstract

PURPOSE: To obtain a 2-color copy without using any filter in imagewise exposure, by forming a photoreceptor having 2 photoconductive layers different in sensitivity to a chromatic color light, and providing as the second photoconductive layer a dispersion layer consisting of ZnO exhibiting a specified photoconductivity, a sensitizer, and a binder.

CONSTITUTION: First photoconductive layer 2 is formed on electroconductive substrate 1 using a charge transfer type photoconductive material consisting mainly of an electron donor sensitive at least to a chromatic color light e.g., a nonred light transmitted through upper second photoconductive layer 3, and an electron acceptor. On layer 2, layer 3 consisting mainly of ZnO made by treating a ZnO powder in H₂S gas and chargeable to both polarities, a sensitizer (sensitizing to red), and a binder is formed to prepare a photoreceptor. Layer 3 is sensitive to red. This photoreceptor undergoes first corona charging as being irradiated e.g. by red light A, subsequent second corona charging for charging surface 3 negatively, and the interface between layers 3, 2 positively, and exposure to the light image of original 4, and a black, white, and red 2-color image is obtained by developing the parts different in surface potential corresponding to black, white, and red using toners 6, 5 different in polarity.

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