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AssigneeTektronix, Inc.
InventorsHue P. Le, Jeffrey J. Anderson, Guenther W. Wimmer, Monte J. Rhoads, Ted E. Deur
Estimating the term…
An ink jet head 10 has an ink chamber 14 which receives ink from an ink inlet passageway 38. Pressure pulses applied to the ink chamber cause the ejection of ink drops from an ink drop forming orifice 23 and toward printing medium. A purging outlet 41 communicates with the ink chamber through a purging passageway 40. During purging, ink flows in a vortical path through the ink chamber 14 from the ink inlet passageway 38 to the purging outlet passageway 40. This sweeps air bubbles and contaminants from the ink chamber walls and removes them from the ink chamber. Ink pressure within the ink chamber 14 may be elevated to increase the flow of ink during purging. Also, a negative pressure may be applied to the purging outlet during purging. Variable frequency pressure pulses may also be applied to the ink chamber to assist the purging process.
A method of purging air bubbles and contaminants from an ink jet head with a body having a wall which defines an internal ink chamber, an orifice passageway leading from the ink chamber through which pressure pulses are transmitted in response to electrical signals applied to a piezo-electric crystal which is in mechanical contact with ink in the ink chamber, an ink inlet through which ink is delivered, to the ink chamber, and a normally closed purging outlet through which ink is selectively removed from the ink chamber without passing through the orifice passageway, comprising:
An apparatus for purging air bubbles and contaminants from an ink jet head of the type with a body having a wall which defines an enlarged internal ink chamber having a longitudianl axis and first and second ends, an orifice passageway leading from the second end of the ink chamber through which pressure pulses are transmitted in response to electrical signals applied to a piezo-electric crystal which is in mechanical contact with the first end of the ink chamber and with ink in the ink chamber and an ink inlet through which ink is delivered to the ink chamber, the apparatus comprising:
An ink jet head including a single compartment ink chamber which has an ink supply inlet for receiving ink under pressure, the ink chamber having an ink chamber wall with a valve free ink orifice pasasgeway leading to an internal ink drop-forming orifice outlet, the ink chamber also having an ink purging outlet through which ink is selectively removed to purge air bubbles and contaminants from the ink chamber, the ink supply inlet and ink purging outlet being located to communicate with one another along a path through the ink chamber which path does not include the ink orifice passageway, means for selectively opening the purging outlet to allow purging of air bubbles and contaminants through the ink chamber, an actuator which applies a pressure pulse to th ink chamber so as to cause ink to flow through the ink orifice passageway and produce an ink drop at the internal ink drop-forming orifice outlet, an air chamber with an air chamber wall through which an external ink jet head orifice is provided in axial alignment with the internal ink drop=forming orifice outlet, the air chamber being adapted to receive pressurized air which flows inwardly from the sides of the air chamber to form a generally coaxial air stream surrounding the internal ink drop-forming orifice outlet and which air stream is directed out of the external ink jet head orifice, the air stream carrying ink drops produced at the internal ink drop-forming orifice outlet, in response to the pressure pulses, outwardly through the external ink jet head orifice and toward printing medium.
Dependencies are inferred from the claim text.