Electrographic printer matrix circuit

Claim 1

A matrix circuit for driving the styli of an electrographic printer for selectively depositing electrostatic charge in image configuration on a web having a dielectric surface, said web being passed between said styli and a platen with said styli in contact with said dielectric surface, said styli being arranged in N groups of M styli, comprising: a first set of M selectively actuable driving circuits each having its output voltage at a first level normally and near a reference potential when the driving circuit is actuated; a second set of N selectively actuable driving circuits each having an output voltage at a second level noRmally and near a reference potential when the driving circuit is actuated; unidirectionally conductive means connecting the styli of each of said N groups to the corresponding driving circuits of said set of N driving circuits; and resistive means connecting corresponding styli from each of said N groups to corresponding driving circuits of said set of M driving circuits, said platen being held at a voltage level near the normal voltage level of said styli, the actuation of related ones of said first and second sets of driving circuits operating to impose a voltage difference having a magnitude at least equal to the voltage necessary to cause charge deposition in said web between the styli connected to simultaneously actuated driving circuits of said first and second sets of driving circuits and said platen.