Piezoelectric polymer membrane stress gage
First Claim
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1. A stress gage for detecting acoustic pressure waves in a body of water, comprising:
- a compressible generally cylindrical pad having a bottom and a top;
a first pair of flexible sheets of a piezoelectric polymer being stretched over the top of said pad under a tensile stress, each sheet of said first pair of flexible sheets having an evaporated metallic film deposited on each face thereof;
a second pair of flexible sheets of the piezoelectric polymer stretched over the bottom of said pad under the tensile stress, each flexible sheet of said second pair having an evaporated metallic film deposited on each face thereof;
means for joining said first pair of flexible sheets and said second pair of flexible sheets along the circumference of said compressible pad;
a plurality of openings in said first pair and said second pair of flexible sheets along the circumference of said compressible pad; and
means for extracting electrical signals from said first pair and said second pair of flexible sheets when said stress gage is subjected to acoustic pressure waves.
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Abstract
Apparatus and method for detecting pressure variations because of acousticaves by modulating a preset tensile stress in a stretched thin sheet of a piezoelectric polymer. The modulation is provided by the changing stress caused by an impinging acoustic signal or the like. The piezoelectric polymer sheet under a preset tension acts effectively as a membrane resulting in a high output combined with a high resonance frequency and a wide operating frequency range.
29 Citations
6 Claims
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1. A stress gage for detecting acoustic pressure waves in a body of water, comprising:
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a compressible generally cylindrical pad having a bottom and a top; a first pair of flexible sheets of a piezoelectric polymer being stretched over the top of said pad under a tensile stress, each sheet of said first pair of flexible sheets having an evaporated metallic film deposited on each face thereof; a second pair of flexible sheets of the piezoelectric polymer stretched over the bottom of said pad under the tensile stress, each flexible sheet of said second pair having an evaporated metallic film deposited on each face thereof; means for joining said first pair of flexible sheets and said second pair of flexible sheets along the circumference of said compressible pad; a plurality of openings in said first pair and said second pair of flexible sheets along the circumference of said compressible pad; and means for extracting electrical signals from said first pair and said second pair of flexible sheets when said stress gage is subjected to acoustic pressure waves. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification