Dennison Manufacturing Company

Fred Miekka

Richard A Fotland

Leo A Beaudet

Method and apparatus for charged particle generation, particularly for use in electrographic imaging, in which a drive electrode and an isolation electrode are substantially in contact with opposite sides of a solid dielectric member, and a discharge electrode is placed on the same side of the solid dielectric member as the isolation electrode to define a discharge region. A high voltage time varying potential is imposed between the drive electrode and the discharge electrode to produce charged particles in the discharge region, and the isolation electrode is capacitively coupled to the drive electrode but otherwise is electrically isolated. The discharge electrode and isolation electrode are not coplanar and the discharge region does not border on the solid dielectric member. In a first embodiment, a dielectric shelf is placed intermediate an apertured discharge electrode and the isolation electrode, to facilitate the inception of discharges. In an alternative embodiment the discharge electrode is an elongate structure placed over the isolation electrode and supported by an apertured dielectric layer.

Method and apparatus for charged particle generation

Method and apparatus for charged particle generation, particularly for use in electrographic imaging, in which charged particles are generated in a discharge region and extracted to form an electrostatic image, wherein a controlled gas is introduced into the discharge region for improved operation and service life. The controlled gas may consist of nitrogen, an elemental noble gas (or mixture of such gasses, or a mixture of nitrogen with one or more noble gasses. In the preferred charged particle generator designs, a high voltage alternating potential (drive voltage) is applied between driver and control electrodes separated by a solid dielectric member to induce glow discharges within apertures in the control electrodes. The charged particle generator may include only the driver and control electrodes, or may further include screen electrodes to regulate the extraction of charged particles. Injection controlled gas into the various discharge sites dramatically reduces the threshold voltages for charged particle generation as well as the corrosion and fouling of electrodes and dielectrics, providing a more durable device and improved electrographic print quality. Nitrogen and nitrogen-argon mixtures are preferred, particularly nitrogen-argon mixtures of about 2:1 volume ratio. The controlled gas may be injected at relatively low concentrations with advantageous results, as well as at higher concentrations.

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Boxborough, MA, United States of America

Fred Miekka