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Sonic Orifice for Ink Jet Aspiration

IP.com Disclosure Number: IPCOM000087219D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Hendriks, F: AUTHOR

Abstract

The use of a sonic orifice in an ink jet aspiration system prevents variation of mass flow due to environmental changes of pressure and temperature.

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Sonic Orifice for Ink Jet Aspiration

The use of a sonic orifice in an ink jet aspiration system prevents variation of mass flow due to environmental changes of pressure and temperature.

As illustrated in Fig. 1, an ink jet printing system 2 includes an ink jet head 3 and an ink jet aspirator 4, with pressurized gas (from a source not shown) being applied to a pressurized gas inlet 5 on the aspirator 4. Ink droplets 6 emanating from the jet head 3 are passed through the aspirator 4 with a regulated collinear gas stream 7 being applied to the aspirator for reducing aerodynamic disturbances on the ink droplets.

Fig. 2 is a detailed cross-sectional representation of the pressurized gas inlet 5, illustrating the calibrated sonic orifice 8.

It is of prime importance to reliable long term operation of an aspirated ink jet printer that the gas stream surrounding the ink droplet stream be closely regulated. Conventional pressure regulators, e.g., the diaphragm type, regulate only within 0.1 pounds per square inch (psi), and are also relatively expensive. The pressure regulator described, that is the use of a calibrated sonic orifice, is relatively inexpensive and has a very small orifice diameter, i.e., less than one millimeter.

The principle of operation of the sonic orifice is that the mass flow through the orifice becomes saturated when the gas velocity reaches the speed of sound (mach 1). Should the down stream pressure decrease, no variation in mass flow occurs, sinc...