Pulsed droplet ejecting systems are described of the type in which a conduit conducts liquid from a reservoir to an orifice. The liquid is under zero or slightly negative pressure, and surface tension in the orifice prevents flow in the absence of other forces. An electroacoustic transducer is coupled...http://www.google.com.au/patents/US3974508?utm_source=gb-gplus-sharePatent US3974508 - Air purging system for a pulsed droplet ejecting system
