Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Patent
1980-11-24
1983-02-22
Shoop, William M.
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
310330, 310800, H01L 4122
Patent
active
043750427
ABSTRACT:
A body of polymeric piezoelectric material is nonuniformly poled by establishing a temperature gradient greater than about 10.degree. C. and less than about 100.degree. C. across the thickness of the body and applying an electric field across the thickness of the body in an amount and for a time sufficient to induce nonuniform polarization in the material, whereby a portion of the body near the surface maintained at a lower temperature receives relatively stronger polarization than a portion near the surface maintained at a higher temperature.
In a preferred embodiment of the invention, after poling in one direction in a temperature gradient to more strongly polarize a portion of the material near one surface, the temperature gradient and the field polarity are reversed, to polarize a portion of the body near the opposite surface in an opposite direction.
Flexure mode elements comprising continuous bodies of polymeric piezoelectric material nonuniformly poled according to the method of the present invention exhibit relatively strong flexure mode response to applied fields. A novel flexure mode element produced by one of the methods of the present invention is characterized by having relatively strong polarization near one surface in a direction pointing into the body of material. Another novel flexure mode element produced by one of the preferred methods of the present invention is characterized by having relatively strong polarization in portions near opposite sides of the body and in opposite directions pointing inward toward the body of the material.
REFERENCES:
patent: 2659829 (1953-11-01), Baerwald
patent: 3365633 (1968-01-01), Anderson et al.
patent: 3458915 (1969-08-01), Miller et al.
patent: 3781955 (1974-01-01), Lavrinenko et al.
patent: 4079437 (1978-03-01), Sheffield
Article by C. P. Germano, "Flexure Mode Piezoelectric Transducers", IEEE Transactions on Audio and Electroacoustics, vol. AU-19, No. 1, Mar. 1971.
Article by H. Sussner and K. Dransfeld, entitled "Importance of the Metal-Polymer Interface for the Piezoelectricity of Polyvinylidene Fluoride", Journal of Polymer Science: Polymer Physics Edition, vol. 16, 529-543, (1978), John Wiley & Sons, Inc.
Close Thomas H.
Eastman Kodak Company
Shoop William M.
Wong Peter S.
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