Dental handpiece switch

Claim 1

A dental handpiece switching apparatus for controlling an ultrasonic dental prophylaxis handpiece in which a substantial portion of the volume of the handpiece contains a magnetostrictive stack and a stack energizing coil comprising: a thin membrane contact assembly that is retained in a generally circumferential arrangement in the outer portion of the handpiece to minimize the size of the handpiece and including (1) a first metallic foil contact mounted on a coextensive insulating backing, (2) a second metallic foil contact mounted on a coextensive insulating backing, said first and second contacts being arranged in circumferential facing relationship and (3) a thin, non-conducting separator between said contacts and having an opening therein to permit electrical communication between said first and second contacts; actuation means for controlling the electrical communication between said first and second contacts including (1) an actuation finger attached to the handpiece and cantilevered over said contact assembly and having a free end with (a) a flat tip generally facing said assembly in proximity to the opening in said separator and (b) an end surface adjacent said tip that is inclined with respect to said assembly, (2) a slideable moveable actuator that surrounds said handpiece and is moveable to strike said inclined surface to force said tip into contact with said assembly so that electrical communication is realized between said first and second contacts and (3) biasing means in contact with said handpiece and said actuator for normally biasing said actuator away from contact with said finger.