Abstract: An electrographic printhead is operated to focus charged particles on a print member. In one embodiment successive electrodes are maintained at potentials that define increasing electric field strengths in the successive regions along the particle trajectory. In another embodiment, a thick electrode face defines equipotential lines that shape a sharply focusing electrostatic field that penetrates the projection apertures of the printhead. Improved focusing diminishes charge spreading effects, and allows effective positioning of the printhead at greater spacings to reduce the risk of arcing without loss of print resolution.

Abstract: A dielectric imaging member of a printer receives a latent charge image that is preferably projected as a plurality of charge dots from a multi-electrode printhead. The member has charging characteristics that diminish the normal electric field component at the edge of charge dots deposited on its surface. The dielectric constant of a surface layer of the imaging member decreases with depth, either continuously, or in a stepwise manner. Various printing aberrations, such as voids in grey-scale images, fringing rings about dots, dot spreading and filling between dots are corrected, so that compensating image coding of printhead actuation sequences is not required to deposit a faithful electrostatic latent image.

Abstract: A DC operated printhead emits electrons by field emission at each crossing of first and second electrodes. Plural small electrode sets consisting of a cathode emitting cone and an anode aperture form a gap which less than the electron mean free path in an ambient atmosphere, and the sets are preferably closely spaced to form a substantially collimated beam. A third electrode preferably accelerates and cleans up the beam. Different gases may be used to increase emission or transport efficiency, and enhance electrode lifetime.

Abstract: A printer has a print cartridge with a plurality of electrically isolated screen electrodes extending in parallel strips and maintained at different potentials to define a uniform electric field in the gap between a print cartridge and a latent imaging member curved about an axis parallel to the strips. As charge carriers are generated, the potentials on a plurality of control electrodes located between the charge carriers and overlying screen electrodes are controlled to provide a fixed bias. This assures gating of a uniform quantity of charge from different apertures of the print cartridge, as well as uniform size of the charge dots formed on the imaging member.

Abstract: There is disclosed a print cartridge for use in charge transfer imaging comprising first and second electrodes on opposite sides of a layer of dielectric material. The first electrodes extend in a first direction and the second electrodes extend in a second direction, and edge structures are provided in the second electrodes at the locations where the electrodes cross. Various structures are described designed to improve the pattern of charge transfer to a receptor to enhance the accuracy of the image and the efficiency of the transfer.

Abstract: There is disclosed a multiple source charged particle generator having first electrodes and second electrodes separated by a dielectric. The second electrodes define independent discharge locations and each of the discharge locations comprises a plurality of discharge sites. The generator is particularly for use in charge transfer imaging of the type used in preparing a latent image on a dielectric, toning the image and transferring the toned image onto a receptor such as paper.