Pulsed aperture for an electrostatic ink jet system

Abstract

Disclosed is an electrostatic ink jet printing system which provides improved frequency response of the mass flow of ink deposited on a recording medium. In accordance with the invention, an ink jet nozzle is conductively connected to an ink reservoir. A conductive platen maintained at a reference voltage level is positioned in front of the nozzle. A sheet of paper is positioned on the surface of the platen. Positioned between the paper and nozzle is a conductive plate having an aperture through which ink emanating from the nozzle is directed. A video data signal input to the system is amplified and biased before being applied to the nozzle. At the same time, the video data signal is also inverted, then fed through a differentiator and finally amplified before being applied to the conductive plate. As a result of the voltage signals applied to the nozzle and plate, a unique electric field is generated between the tip of the nozzle and the plate. This electric field exerts a force on the ink at the tip of the nozzle causing a mass flow of the ink. As a result of the unique characteristics of the electric field, the frequency response of the mass flow is improved, thereby producing sharper images on the paper.