Electrostatic electrographic printing

This paper describes the empirically observed characteristics of electrographic printing in which electrostatic charge patterns are deposited onto a dielectric surface via a contacting electrode and subsequently made visible by toning. The process exhibits a threshold effect that may be used in simplifying the addressing circuitry. An equivalent circuit of the electrode and dielectric coated-paper combination that incorporates the threshold effect is presented. Typical printers using this electrographic process are described, and some requirements of the drive circuitry necessary for such printers are discussed.