METHOD FOR MANUFACTURING ELECTRET DEVICE

摘要

To overcome the problems in prior electret devices resultant from non-uniform distribution of the surface potential on the electret there is provided a method for manufacturing an electret device in which a DC voltage is applied by a power applying circuit across metal layers on both surfaces of a dielectric material film. The power applying circuit is then opened, while the DC voltage is being applied, to stop applying the DC voltage, thereby obtaining an electret in which the surface potential is well controlled in correspondence with the applied voltage. Also disclosed is a condenser type electro-acoustic transducer having reduced high harmonic distortion, this transducer having electrets as the stationary electrodes which are provided by the above method.