ELECTRET TRANSDUCER AND METHOD OF MAKING AN ELECTRET TRANSDUCER

摘要

In order to facilitate the manufacture of an electret transducer backplate and to improve the performance and reliability of the transducer, the backplate (6) is made of a thermo-softening plastics material rendered electrically conducting by electrically conducting particles distributed therethrough. An electret foil diaphragm (7) is mounted on the backplate (6) and the relative flexural rigidities of the diaphragm (7) and the backplate (6) are such that, in use, the deflection of the diaphragm is at least twenty times as great as the deflection of the backplate. A method of making the transducer involves heating an electret foil, bonding the electret foil to a retaining ring while the foil is hot and securing together the retaining ring and the backplate.