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Pressure transducer with an invariable reference capacitor

  • US 4,422,125 A
  • Filed: 05/21/1982
  • Issued: 12/20/1983
  • Est. Priority Date: 05/21/1982
  • Status: Expired due to Term
First Claim
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1. A pressure transducer with an invariable reference capacitor comprising:

  • a first substrate of insulative material and a second substrate of insulative material;

    wherein at least one substrate is flexible and will deform in response to a pressure change;

    wherein said substrates are positioned to oppose each other across a gap;

    an annular frit joining said substrates and forming a chamber between them by sealing said gap to a reference pressure, said annular frit comprising an insulative material with a dielectric constant in excess of one;

    at least one sensing capacitor plate formed of a conductive material disposed on one of the substrates and located entirely within the area defined by said chamber;

    at least one reference capacitor plate formed of a conductive material disposed on said one substrate and located entirely within the annular area defined by the frit;

    at least one common plate formed of a conductive material disposed on said other substrate and opposing said sensing plate in the area defined by said chamber to provide a sensing capacitance between said one common plate and said sensing plate; and

    another common plate formed of a conductive material disposed on said other substrate and opposing said reference plate in the area defined by the frit annulus to provide a reference capacitance between said other common plate and said reference plate.

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