Importance

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Abstract

In an ink jet printer, a print head comprises a front nozzle member having a front channel, a housing secured to the front nozzle member, and a rear nozzle member which defines with the housing a liquid chamber and further defines with the front nozzle member a laminar airflow chamber. The rear nozzle member has a forwardly projecting nozzle and a rear channel extending from the liquid chamber through the projecting nozzle in axial alignment with the front channel to form a meniscus at the front end. The airflow chamber is connected to an air supply for directing air to a point between the front and rear channels so that it creates a sharp pressure gradient along a path therebetween. A dead air region is created in a location adjacent the exit end of the rear channel to cause the meniscus to take a dome-like shape which is stabilized against vibrations and transients. An electric field gradient is established between the front channel and the meniscus to cause the latter to extend toward the front channel and expelled through the front channel. A portion of the front nozzle member is rendered liquid-repellant to prevent the field distribution from being seriously disturbed by an ink layer formed on it by stray liquid particles.

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First Claim