An electroacoustic transducer includes a base plate made of insulating material, a stationary electrode formed on one side of the base plate and made of electrically conductive material, an annular support formed on the same side of the base plate and surrounding the stationary electrode, the annular...http://www.google.de/patents/US4615105?utm_source=gb-gplus-sharePatent US4615105 - Electroacoustic transducer and a method for manufacturing thereof
