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Environmentally sealed variable capacitance apparatus

  • US 4,359,720 A
  • Filed: 04/29/1981
  • Issued: 11/16/1982
  • Est. Priority Date: 04/29/1981
  • Status: Expired due to Term
First Claim
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1. A key actuatable capacitive circuit board comprising:

  • flexible dielectric sheet means having first and second parallel proximate portions each with first and second surfaces arranged so that the first surfaces are adjacent and the second surfaces are separated by at least the first and second portions;

    first and second patterns of electrically conductive material on the first surface of the first portion of said sheet means and the second surface of the second portion of said sheet means respectively, selected portions of said first and second patterns being aligned in a direction perpendicular to the portions of said sheet means so as to form first and second plates of an array of capacitors;

    first spacer means interposed between the first surfaces of the first and second portions of said sheet means so as to normally maintain a predetermined separation between the first surfaces, said spacer means being of a design which permits the spacing between the first and second plates of capacitors in the array to be varied; and

    sealing means for sealing the first and second portions of said sheet means and said first spacer means together so as to prevent exposure of the spaces between the first and second capacitor plates to the environment surrounding said sheet means.

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