Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Electrostrictive – magnetostrictive – or piezoelectric
Patent
1991-11-15
1994-02-01
Ng, Jin F.
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Electrostrictive, magnetostrictive, or piezoelectric
381191, 381173, 310324, H04R 2500
Patent
active
052838358
ABSTRACT:
An acoustic transducer is formed by a rigid substrate and a strip of a laminated sheet material including an intermediate layer of a ferroelectrical material sandwiched between inner and outer layers of a conductive material. Two lines of conductive epoxy supply an AC signal across the full height of the inner and outer layers. The ferroelectric layer is preferably a piezoelectric plastic such as PVDF with a preferred direction of displacement oriented laterally across the strip. The strip is preferably secured in a groove in the substrate by a cement having acoustical properties closely matching those of the strip and the substrate. The strip is curved in a parabola by its own tension. The strip is sufficiently stiff to be self supporting without the use of a foam or rubber backing layer. The conductive layers are preferably each a layer of copper overlayed with a layer of nickel. The substrate preferably includes a sound chamber mounted on its back side opposite the strip and has a set of holes to transfer sound energy to the chamber. The material forming the substrates has a speed of sound closely matching that of the strip, but preferably slightly less. The substrate material is also lossy to dampen the acoustical energy.
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Le Huyen D.
Ng Jin F.
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