Patent ID: 6012801
Filing Date: 2000-01-11
Classification: B41J,G03G

Abstract:
A direct electrostatic print unit comprising:a particle source;a back electrode;a background voltage source connected to the back electrode to produce an electric potential difference between the back electrode and the particle source;a printhead structure positioned between the back electrode and the particle source, comprising:a substrate layer of electrically insulating material having a top surface facing the particle source and a bottom surface facing the back electrode;a plurality of apertures arranged through the substrate layer;a first printed circuit arranged on said top surface of the substrate layer, including a plurality of control electrodes, each of which at least partially surrounds a corresponding aperture;a plurality of control voltage sources, each of which is connected to a corresponding control electrode to supply variable electric potentials to control the stream of charged toner particles through the corresponding aperture during at least one development period wherein the stream of charged toner particles are transported toward the back electrode;at least one voltage source connected to the control electrodes to supply a periodic voltage pulse to cut off the stream of charged toner particles after the at least one development period;a second printed circuit arranged on said bottom surface of the substrate layer, including at least two sets of deflection electrodes;at least one deflection voltage source connected to each set of deflection electrodes to supply deflection potentials which control the transport trajectory of toner particles; andat least one voltage source connected to each set of deflection electrodes to supply a periodic voltage pulse to cut off the stream of charged toner particles after said at least one development period.