JPS56110954A - Formation of electrostatic latent image - Google Patents

Abstract

PURPOSE:To obtain a sharp copied image free from any photographic fog in the background by beforehand uniformly charging an electrostatic latent image acceptive dielectric for a fixed surface with the charge of the polarity opposite to that of the charge of the latent images in the electrostatic transfer of simultaneous voltage application and image exposure in electrophotography. CONSTITUTION:Even in the dark state under no irradiation of light, the DC voltage as much as it is sufficient for gaseous discharge is loaded between a photoreceptor 10 and electrostatic transfer paper 20 for a predetermined short time, after which an electrode plate 12 and a conductive sponge pad 31 are short-circuited and the surface of the transfer paper is exposed over the entire surface until the electric field in the photoconductive layer 13 goes substantially zero, whereby the surface of the transfer paper is uniformly charged. In order to increase this surface potential much higher, these are repeated n-times. Thence, the voltage of the polarity opposite to that of the previous charge is applied with a DC voltage power source 41, and at this same instant, the transfer paper is exposed with the images of a positive original 1, whereby the light irradiated parts on the transfer paper 20 are neutralized by the gaseous discharge of the air gap, whilist the charge is transferred.