US PATENT SUBCLASS 381 / 173
.~.~ Piezoelectric or ferroelectric

Current as of: June, 1999
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381 /   HD   ELECTRICAL AUDIO SIGNAL PROCESSING SYSTEMS AND DEVICES

150  DF  ELECTRO-ACOUSTIC AUDIO TRANSDUCER {18}
369  DF  .~ Microphone capsule only {10}
173.~.~ Piezoelectric or ferroelectric

DEFINITION

Classification: 381/173

Piezoelectric or ferroelectric:

(under subclass 168) Subject matter having an element made of either (a) a material which produces a voltage when subjected to a mechanical stress or (b) a material having a spontaneous electrical polarization.

SEE OR SEARCH THIS CLASS, SUBCLASS:

190, and 191, for reproducer or generic transducer of the piezoelectric or ferroelectric type, respectively.