Importance

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Abstract

Disclosed is an improved electrostatic ink jet printing system which provides a potential barrier to block static charges built up on a recording medium from influencing the electric field which draws a liquid imaging material from an ink jet nozzle to the recording medium. The system's ink jet nozzle is supplied with a liquid imaging material at a hydrostatic pressure such that a meniscus of the imaging material forms at the tip of the ink jet nozzle. A conductive platen is positioned in front of the exit oriface of the ink jet nozzle and the recording medium is interposed between the conductive platen and the tip of the ink jet nozzle. A potential difference is applied between the platen and the ink jet nozzle in order to generate the electric field. The potential barrier is effected by providing a conductive plate having an aperture between the recording member and the ink jet nozzle, the platen and plate maintained at an identical potential level. The plate serves to block charges built up on the recording medium from influencing the electric field between the plate and the ink jet nozzle. Once the liquid imaging material has been drawn through the aperture, it has gained sufficient momentum such that it is not effected by the static charges built up on the recording medium. Also disclosed is an alternate embodiment of the invention incorporating a plurality of ink jet nozzles and a corresponding number of potential barrier shields. In addition to blocking each nozzle from static charges built up on the recording medium, each shield serves to isulate the electric field generated between the platen and its respective nozzle from the influence of an electric field generated between the platen and one or more adjacent ink jet nozzles.

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First Claim