×

Elastic surface wave pressure gauge and pressure sensor for such a gauge

  • US 4,382,386 A
  • Filed: 09/25/1980
  • Issued: 05/10/1983
  • Est. Priority Date: 09/28/1979
  • Status: Expired due to Term
First Claim
Patent Images

1. An elastic surface wave pressure gauge comprising:

  • a plug-in unit including two delay lines formed by interdigitated comb shaped transducer electrodes placed on a first main face of a piezoelectric wafer, the wafer resting by its second main face on the periphery of a chamber communicating with a pressure inlet, andtwo amplifier circuits oscillating at two different frequencies, one amplifier being connected to each delay line, the difference between these two frequencies being detected by a mixer stage which supplies a measuring signal indicative of a pressure within said chamber,the amplifier circuits and the mixture stage being mounted on a circuit board having a ground plane and provided with connections surrounding an orifice providing a passage for the pressure inlet,the pressure inlet being being formed as part of the plug-in unit and being constituted by a metal pipe fixed to a rigid metal header, whose periphery is provided with pins which are inserted in said connections, the pins and metal pipe extending outwardly from the piezoelectric wafer, said header having a support for the piezoelectric wafer between the pins, this support having a central depression communicating with the pipe, the metal pipe and header being electrically connected with the ground plane of the board to provide electrical shielding for minimizing pull-in between the two amplifier circuits oscillating at different frequencies.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×