ELECTROSTATIC PHOTOGRAPHIC PROCESS, PHOTOSENSITIVE MATERIAL FOR USE THEREIN AND TRANSFER SHEET BEARING A FIXED IMAGE PREPARED EMPLOYING SAID PROCESS OR MATERIAL

摘要

Various problems occur when multiple copies are obtained by conventional electrostatic photographic processes in which imagewise exposure is conducted only once per original to be copied, due to difficulty in erasing the photomemory of the photosensitive materials employed. An electrostatic photographic photosensitive process is now disclosed in which the photomemory effect is not utilised An electrostatic photographic photosensitive layer (1) carried by an electrially conductive substrate (2) is subjected to a combination of negative charging (A), positive charging (B), and imagewise exposure (C) to form an electrostatic latent image of a positive polarity The photosensitive layer comprises a a photoconductive zinc oxide-resin binder dispersion layer, has memory resistance of at least 90% and has such charging characteristics that the photosensitive layer can be positively charged by negative charging and positive charging is rendered substantially impossible by irradiation with light. The photosensitive layer can be subjected to positive charging (B) a predetermined number of times without further imagewise exposure so as to form an electrostatic latent image thereon the same number of times in order to prepare multiple copies of one original.