Gas density transducer
AssigneeCalogic Corporation
InventorRichard Jasmine
Life of this patent
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Abstract
An improved gas density transducer which compares the resonant frequency of an enclosed, reference tuning fork crystal oscillator with the resonant frequency of a detector tuning fork crystal oscillator exposed to the surrounding gas. The frequency of oscillation of the detector crystal oscillator exposed will vary in accordance with the gas density because of the motional resistance of the gas to vibrations of the tuning fork oscillator. The frequency of the detector oscillator can be compared to the frequency of the reference oscillator to determine the gas density.
Claims16
A gas density transducer comprising:
- a reference tuning fork crystal oscillator sealed within a chamber having a fixed gas density;
- a detector tuning fork crystal oscillator exposed to the density of the gas surrounding said transducer;
- and
- means for comparing the frequency of signals from said reference and detector oscillators and producing an output signal proportional to the difference in the frequencies of said signals.
A gas density transducer comprising:
- a reference tuning fork crystal oscillator sealed within a chamber in a substantial vacuum;
- a detector tuning fork crystal oscillator exposed to the pressure of the gas surrounding said transducer;
- a first amplifier coupled to said detector oscillator;
- a second amplifier coupled to said reference oscillator, said second amplifier including means for varying the frequency of said reference oscillator responsive to changes in temperature to substantially offset changes in frequency caused by variations in gas density due to said changes in temperature;
- and
- a mixer for producing a beat frequency proportional to the difference between the frequencies of output signals of said first and second amplifiers.
A gas density transducer comprising:
- a reference tuning fork crystal oscillator sealed within a chamber having a fixed gas density;
- a detector tuning fork crystal oscillator exposed to the density of the gas surrounding said transducer;
- means for comparing the frequency of signals from said reference and detector oscillators and producing an output signal proportional to the difference in the frequencies of said signals;
- and
- temperature compensation means for varying said output signal inversely proportional to the change in gas density with temperature.
A pressure transducer comprising:
- a reference tuning fork crystal oscillator sealed with a first chamber having a fixed gas density;
- a detector tuning fork crystal oscillator mounted in a second chamber filled with a gas and having an opening coupling the interior of said chamber to the exterior of said transducer;
- a flexible diaphragm covering said opening so that changes in pressure outside said transducer will move said diaphragm to change the volume of said second chamber and thus vary the gas density in said second chamber;
- and
- means for comparing the frequency of signals from said reference and detector oscillators and producing an output signal proportional to the difference in the frequencies of said signals.
Dependencies are inferred from the claim text.