Electret assembly

Abstract

A tiny electret assembly for an electroacoustic hearing aid transducer, either a microphone or a sound reproducer, includes a thin, flexible, planar diaphragm and a planar backplate, the diaphragm and the backplate constituting the electret electrodes. One of the two electrodes is permanently charged to a given differential voltage relative to the other and the two electrodes are mounted, in the transducer, in fixed, spaced, substantially parallel relation to each other; the differential voltage between the electrodes pulls a central portion of the diaphragm toward the backplate, tensioning and stiffening the diaphragm. The mount for the diaphragm permits movement of the diaphragm rim in the plane of the diaphragm but precludes movement of the rim of the diaphragm perpendicular to the plane of the diaphragm (and the backplate) so that the diaphragm cannot buckle. Different rim mounts for the diaphragm are described.

Dependencies are inferred from the claim text.