JPS5515151A - Electrophotographic method - Google Patents

Abstract

PURPOSE:To obtain two-color copying at high speed and with ease by forming the composite image latent images of both negative and positive images by the specific method on an electrophotographic photoreceptor. CONSTITUTION:For example, an insulation layer 4 is charged to positive 6 and a photoconductive layer 3 to negative 7 in a photoreceptor 1 by a corona discharger 5 or the like. Next, when negative charging of the opposite polarity from the foregoing one is performed by a corona discharger 8 or the like while the positive images (image light 9) and negative images (image light 10) are being exposed, then it becomes that the charges of the photoconductive layer 3 are released to a conductive substrate 2, wherein the positive charges 11 remain in the region A where the images rays 9, 10 of the surface of the insulation layer 4 are both unradiated, the negative charges 12 remain in the radiated ration B of the image lights 10 and the region C radiated with both image lights 9, 10 is charged 12 to positive or negative or negative depending upon the magnitude of the quantity of exposure light. The radiated region D (background of positive, negative image) of only image light 9 is adjusted so that it quantity of exposure of image light 9 becomes zero. Next, when full surface exposure 13 is done, the charges corresponding to the charges of the photoconductive layer 3 remain on the insulator 4. This is developed with the toners having been respectively charged to positive and negative and is then transferred, whereby two-color recording is obtained.