US Patent 7680294 Acoustic transducer

An acoustic transducer includes a magnetic circuit part and a voice coil operatively connected to the magnetic circuit part. A tubular casing accommodates the magnetic circuit part and the voice coil. An annular first support spring has an outer peripheral portion embedded and secured in the casing. The first support spring extends radially inward from the inner peripheral surface of the casing and has an inner peripheral portion abutting on and fixed to the magnetic circuit part. An annular second support spring has an outer peripheral portion abutting on and fixed to one end portion of the casing. The second support spring extends radially inward and has an inner peripheral portion abutting on and fixed to the magnetic circuit part.