A piezoelectric speaker including a plurality of piezoelectric vibrating elements, each including a piezoelectric vibrating plate and a weight connected to near the point of center of gravity thereof through a viscoelastic layer, and having the vibramotive force designed to be taken out of the outer...http://www.google.fr/patents/US4654554?utm_source=gb-gplus-shareBrevet US4654554 - Piezoelectric vibrating elements and piezoelectric electroacoustic transducers
Piezoelectric vibrating elements and piezoelectric electroacoustic transducers
