Abstract: Direct electrostatic printing apparatus including a cylindrically shaped donor structure for delivering imaging material such as toner particles to a printhead forming an integral part of the printing device. The printhead structure includes control electrodes and a shield electrode structure secured to opposite sides of an insulative base. The donor structure has a relatively small diameter compared to such devices of the prior art making it impossible to deliver adequate quantities of toner to some of the printhead apertures using electrical biasing techniques of the prior art. In the device disclosed, the printhead apertures are biased according to the aperture spacing from the donor structure. The magnitude of the bias or its duration applied to the apertures farther from the donor structure surface is such that toner delivery to those apertures is equal to that of all other apertures.

Abstract: A printhead for electrostatic printing comprises a membrane, made of a non-crystalline ceramic material, defining a first surface and a second surface, and defining a plurality of apertures therein. A plurality of addressable segmented electrodes are disposed on the first surface around substantially the periphery of an aperture on the first surface, each segment of the addressable segmented electrodes being isolated from each other segment. A conductive layer is disposed on the second surface around substantially the periphery of at least one aperture on the second surface. The ceramic membrane facilitates the incorporation of active electronic devices on the printhead.