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Expired Canadian patentCanada

Reactance measurement circuit

CA 1181132 A · Owner: Rosemount Inc. · Inventors: Grindheim, Earl A.; Frick, Roger L.; Ruesch, James R.

CIPO record

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Its claims, description and drawings are in the Canadian Patents Database.

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Abstract From the Canadian patent

A circuit for measuring the reactance of an AC reactance sensor which varies responsive to a condition to be sensed such as, pressure, is disclosed. The circuit comprises an oscillator coupled to the sensor for providing a time varying oscillator signal having a variable frequency and a substantially constant peak to peak voltage to the sensor, and a plurality of rectifiers coupled to the oscillator and to the sensor for providing the oscillator signal as a charging signal to the sensor and for providing discharging signals from the sensor, the discharging signals being a function of the reactance of the sensor, and an amplifier coupled to the rectifiers and to the oscillator for providing …

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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.

Why it's free to use

  • Granted January 15, 1985. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended January 15, 2002.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledJanuary 22, 1982
GrantedJanuary 15, 1985
Term endedJanuary 15, 2002
Patent numberCA 1181132 A
Classification (IPC)G01L9/12 +1 more

Timeline

Timeline From CIPO dates

1983198519871989199119931995199719992001Application filedJan 22, 1982Patent grantedJan 15, 1985Term endedJan 15, 2002

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Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.