U.S. Philips Corporation

Hans J Hirsch

Horst Dannert

Electrostatic charge images of identical shape but opposite sign are generated on both sides of a transparent, highly insulating foil. Subsequently, pigment is deposited on both sides of the foil by means of oppositely charged developers. The optical density of an electrophotographic image on a transparent insulating foil is increased, as compared to densities achieved in the past, for a given surface charge density by establishing a charge exchange between one side of the foil and an electrode. On the other side of the foil a charge image is generated and the foil. The electrode are separated from each other prior to development.

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Selfkant-Tuddern, Germany

Hans J Hirsch