| 摘要 |
PURPOSE:To freely change over a copying mode to an optional one for copying, by subjecting a composite photoreceptor made by laminating >=2 photoconductive layers to charging in >=2 times and exposure to form 3 kinds of electrostatic latent images of positive, negative, and zero potentials. CONSTITUTION:Each predetermined voltage is applied to primary and secondary charger 2, 3 and the first and second developing devices 17, 21, and switch 12, switch 24 for spare transfer charger 23, and switch 26 for transfer charger 23 are set to a potential corresponding to each copying mode, and color (b) intercepting filter 13 is changed over to set the surface potentials of parts of color (a) and color (b) of a 2-color original to reverse polarities, and the surface potentials of the background part of the original and the part to be erased to near zero. Composite photoreceptor 1 prepared by laminating on conductive substrate 1a the first photoconductive layer 1b having sensitivity not to color (b) but to the other visible light, and rectifying action on charge transfer, and the second photoconductive layer 1c having high sensitivity to color (b) light, but transmitting visible light, is subjected to primary and secondary charging and imagewise exposure to form an electrostatic latent image, and this image is developed with a charged fine powder of reverse polarity. |
