JPS5491330A - Copying method for dichroic zerography - Google Patents

Abstract

PURPOSE: To solve the problem that nothing but an image having an insufficient density can be obtained for a portion having an orange red color by removing a light of a preset wavelength range from the flux of light for exposing a photosensitive element.

CONSTITUTION: The photosensitive element 1, which is composed of a conductive substrate 11, a photoconductive layer 12 and a second conductive layer 13 having no sensitivity to a red color so that at least one portion of the red color may pass therethrough, is irradiated uniformly with a red color to have its surface potential charged to a negative value by a charger 2. Then, positive charges are applied in the dark by a charger 3 to reverse the polarity of the surface potential to a positive value while leaving the negative charges on the photosensitive element 1 by the primary charge. Then, the exposure of an optical image upon an original, which has an information pattern of red and black color upon a white background, is carried out through a dichroic filter, which blocks the light in the wavelength range of 570 to 600 nm, to form an electrostatic latent image. The latent image, which has a substantially zero potential at the surface of the photosensitive element corresponding to the white background of the original, is visualized with both black toners TB, which is charged negative, and red toners TR which is charged positive.

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