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Pressure sensing cell using brittle diaphragm

  • US 4,578,735 A
  • Filed: 10/12/1984
  • Issued: 03/25/1986
  • Est. Priority Date: 10/12/1984
  • Status: Expired due to Term
First Claim
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1. A differential pressure sensor assembly having first and second sensor portions;

  • said first and second sensor portions each comprising a pair of plates, a first of which is a brittle semiconductor material, and a second of which is a rigid insulating material, said plates initially being substantially contiguous to each other along first surfaces of said plates and sealed together along an encompassing line with portions of said first surfaces being unconnected to permit movement of said first semiconductor plate of each sensor portion relative to the other plate of the same sensor portion to form first and second chambers, respectively, in each of the first and second sensor portions;

    each of said second plates having capacitive electrode means on the first surfaces thereof facing said semiconductor plates of the respective sensor portion to permit measuring differences in spacing of said facing surfaces by measurement of capacitance between the semiconductor plate and the capacitive electrode;

    fluid conduit means for connecting said first and second chambers, respectively;

    a quantity of substantially incompressible fluid filling said first and second chambers and to said fluid conduit means to space the semiconductor plates from the second plates;

    housing means to permit subjecting at least one of the plates of each sensor portion to a pressure tending to move the plates forming each sensor portion together, the pressure acting on the respective sensor portion being at least at times different from the pressure acting on the other sensor portion, whereby the incompressible fluid will be forced into one chamber from the other chamber and cause increase in bending stress of the plates in one of said sensor portions and a decrease in bending stress of the plates of the other sensor portion; and

    said other sensor portion reaching a condition wherein the first and second surfaces of the plates forming the other chamber are substantially contiguous before either of the plates forming the one sensor portion reach an excessive stress level.

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