Electricity: electrical systems and devices – Electric charge generating or conducting means – Use of forces of electric charge or field
Patent
1976-04-30
1978-03-14
Goldberg, Gerald
Electricity: electrical systems and devices
Electric charge generating or conducting means
Use of forces of electric charge or field
29 2535, H05F 102, H05F 302
Patent
active
040794377
ABSTRACT:
An apparatus and method for rapidly and continuously poling a film of polymeric material exhibiting at least one of pyroelectric and piezoelectric characteristics to yield a poled film having a high coefficient of at least one of pyroelectric and piezoelectric properties, and a high degree of uniformity of polarization throughout its thickness. The method of the present invention includes applying an electric field greater than 1000 K volts/cm across the film for less than 180 seconds. The apparatus of the present invention includes a drive for advancing the film and a pair of electrodes that establish an electric field across the film. In a first embodiment, a hot poling roller serves as a high voltage electrode and a grounded roller contacts a conductive layer coated on the other side of the film to provide the second electrode. In a second embodiment both electrodes are provided by hot poling rollers with one being connected to a high voltage potential and the other to ground potential. Both embodiments utilize ambient air to cool the film while such pyroelectric and piezoelectric properties exist in the film. A third embodiment is similar to the first except that the hot poling roller of the first embodiment is a cold poling roller and a radiant source heats the film during poling. In all three embodiments the high voltage electrode is separated from direct physical contact with the film by a resistive layer in order to avoid serious damage to the film due to electrical arcing that can occur through a defective or thinner than normal area of the film.
REFERENCES:
patent: 2648097 (1953-08-01), Kritchever
patent: 3521126 (1970-07-01), Granzow et al.
patent: 3885301 (1975-05-01), Murayama
patent: 3899969 (1975-08-01), Taylor
patent: 3985914 (1976-10-01), Sasaki et al.
Journal of Polymer Science "Persistent Polarization in Polyvinylidene Fluoride" by Murayama et al. vol. 13, May, 1975, pp. 1033-1047.
Applied Physics Letters "Room-Temp. Poling & Morphology Changes in Pyroelectric PVF" by Southgate, vol. 28, No. 5, Mar. 1, 1976, pp. 250 to 252.
Applied Physics Letters, vol. 24, No. 10, May 15, 1974, pp. 456-458.
Journal of Applied Physics, vol. 44, No. 5, May 1973, pp. 2064-2071.
Alexander Cruzan
Goldberg Gerald
Kirn Walter N.
Minnesota Mining and Manufacturing
Sell Donald M.
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