ELECTROSTATIC IMAGING METHOD

Disclosed is a novel high speed method for the formation of an electrostatic image in a photosensitive plate comprising a grounded conductive substrate having on its surface a layer of photoconductive material overcoated with a layer of an insulating resin. The process involves the consecutive steps of:a) applying an initial electrostatic charge of one polarity to the surface of the plate to provide an initial potential which is solely across the insulating layer;b) applying an electronic field of either alternating current or direct current of polarity opposite that of the polarity of the initial charge to drive the initial potential to a potential included in the range extending from a potential less than the initial potential through zero to a chosen potential opposite in sign to the polarity of the initial potential;c) exposing the plate to imagewise activating radiation thereby forming an imagewise potential distribution across the layer of photoconductive material;d) applying to the surface of the plate an electronic field of either alternating current or direct current of polarity opposite that of the polarity of the initial charge to drive the imagewise potential to a potential included in the range extending from a potential less than the initial potential through zero to a chosen potential opposite in sign to the polarity of the initial potential; ande) forming an imagewise potential distribution across the insulating layer by uniformly exposing the plate to activating radiation or allowing the inherent dark decay of the photoconductor to establish the imagewise potential distribution.