| 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 19, 23, and switch 14, switch 27 for spare transfer charger 26, and switch 29 for transfer charger 25 are set to a potential corresponding to each copying mode, and color (b) intercepting filter 15 is changed over to render the surface potentials of parts of color (a) and color (b) of a 2-color original reverse in polarity, and to set to near zero the surface pontetials of the original ground and the part erasion of which is desired. Composite photoreceptor 1 is prepared by laminating on conductive substrate 1a the first photoconductive layer 1b having no sensitivity to said 2 colors, but sensitivity to the other visible light, and the second photoconductive layer having high sensitivity to color (b), and an electrostatic latent image is formed by subjecting photoreceptor 1 to primary and secondary charging and imagewise exposure under the color (b) light. |
