In the pressure, on-demand type ink-jet printers or the like, the driving voltages applied to respective electrostrictive means of print head or nozzle units are shifted in time so that constructive interferences of sound waves produced by the pressure waves which in turn are generated bu respective...http://www.google.fr/patents/US4300144?utm_source=gb-gplus-shareBrevet US4300144 - Multiple-nozzle ink-jet recording apparatus
