JPS5576359A - Developing system - Google Patents

Abstract

PURPOSE:To make possible color copying of two colors by forming the positive and negative latent images corresponding to the original images of two colors of chromatic color and black on a photoreceptor having a photosensitive layer highly sensitive to chromatic colors and a photosensitive layer insensitive to chromatic colors and developing these with the toners of mutually different polarities. CONSTITUTION:For example, in performing color copying of two colors of red and black, a photosensitive layer 3 highly sensitive to red color is provided on the conductive substrate 2 of a photosensitive drum 1 and a photosensitive layer 4 insensitive to red color is provided thereon. While red light is being radiated through a red filter 17 from a light source 16, the layer 4 is negative-charged with a primary charger 5, thence it is dark-charged with a secondary charger 6, after which it is subjected to the exposure 7 of two-color original images. In correspondence to the red, white and black of the original images, the regions of positive and negative charging and zero charging are formed on the surface of the layer 4. The multicolor development of red, white and black may be accomplished by using the red and black toners of mutually different polarities with developing devices 8 and 9. If the black toners of mutually different polarities are used with the developing devices 9 and 10, the black and white development in which the portions of red are not dropped out may be accomplished. Next, the images are evenly charged with a charger 11 before transfer and the transfer is accomplished with a transfer unit 18.