Two color electrophotographic process and material

Abstract

A photoconductive material (11) coated on a drum, belt or sheet (22) is formed with a first photoconductive layer (11b) which is insensitive to red light, a second photoconductive layer (11d) which is sensitive to red light and a transparent insulating layer (11c) formed either between the photoconductive layers (11b), (11d) or on top thereof. The outer surface of the material (11) is radiated with white light while applying a first electrostatic charge thereto rendering both photoconductive layers (11b), (11d) photoconductive. Then, the material (11) is radiated with red light rendering only the second photoconductive layer (11d) photoconductive while applying an electrostatic charge of opposite polarity. Then, a third electrostatic charge of the same polarity as the first electrostatic charge is applied in the dark. The result is that electrostatic charges of opposite polarities are formed at the outer surfaces of the first and second photoconductive layers (11b), (11d). Radiation of a colored light image on the material (11) causes both photoconductive layers (11b), (11d) to conduct and dissipate charge in white image areas, only the second photoconductive layer (11d) to conduct in red image areas and no photoconduction in black image areas in such a manner that the surface potential is opposite in polarity in the red and black areas and zero in the white areas. Red and black toners of opposite electrostatic charge are applied to the material (11) to form a two color toner image which is transferred to a copy sheet (36) and fixed as required.

Dependencies are inferred from the claim text.