Electrophotographic method for reversal or positive-positive image formation.

摘要

An electrophotographic reversal copying method as illustrated in Fig. 1, utilising a photoconductive recording layer (22), characterised in that the method comprises the following steps : (I) uniformly exposing the photoconductive layer (22) to light in the photosensitivity range said layer, which means in a range below the range wherein the differential quotient of optical density decrease (minus DELTA D) of the photoconductive layer (22) with respect to wavelength increment ( DELTA lambda in nm) is at least 0.02, (II) uniformly electrostatically charging said layer (22) by means of a corona charge unit (10), (III) imagewise exposing the layer (22) to light of a light source (11) whose wavelength(s) is (are) shorter than the wavelength(s) of the light used in step (I); (IV) repeating step (I) using a light source (13), (V) repeating step (II) using a corona charge unit (16); the doses and wavelength difference of the light to which the layer (22) is exposed in steps (I) and (III) being such that this step (V) results in a condition in which areas of the layer (22) which were exposed in step (III) bear electrostatic charges greater than charges borne by areas which were not exposed in that step.