Electrophotographic process with a.c. charger producing greater positive charge

An electrophotographic process employing an electrophotographic photosensitive member comprised of a conductive support, and a photoconductive layer and a transparent insulator layer sequentially applied to said support so that said photoconductive layer is between the transparent insulator layer and the conductor support, said process comprising the steps of:

• uniformly charging the exposed surface of said transparent insulator layer with a charge whose polarity is the same as the source used for charging whereby a uniform charge of the opposite polarity is developed at the interface between the insulator layer and the photoconductive layer;
• charging the exposed surface of said insulator layer concurrently with an image-wise exposure thereof, said charging being applied in an alternating polarity fashion in accordance with an a.c. voltage comprised of alternately occurring positive and negative half waves, wherein the time duration of one of said positive and negative half waves is reduced as compared with the remaining alternating half waves, so that the charging period of the half waves reduced in time duration is shorter than the charging period of the remaining half waves in order to increase the number of corona ions of positive polarity;
• and
• thereafter exposing said insulator surface to uniform radiation, thereby forming an electrostatic latent image on the surface of said transparent insulator layer.