Transducer
First Claim
1. A passive electrically operable monitoring means for use with a transducer for monitoring a physical parameter, the monitoring means having an inherent resistance and a characteristic capacitance and inductance only, the characteristic capacitance and inductance being responsive to variations in the physical parameter such that the monitoring means has a natural frequency of oscillation that varies in accordance with variations in the physical parameter.
1 Assignment
0 Petitions
Accused Products
Abstract
A passive electrically operable monitoring means has an inherent resistance and a characteristic capacitance and inductance only, so that the monitoring means has a predetermined natural frequency of oscillation. Variations in a physical parameter being monitored by the monitoring means will cause the characteristic capacitance and/or inductance to vary thereby varying the natural frequency of oscillation of the monitoring means. A transducer includes an excitation means for exciting the monitoring means and a sensing means for sensing the natural frequency of oscillation of the monitoring means. The excitation means includes a pulse generating means for exciting the monitoring means with a string of pulses having a repetition rate suitably lower than the natural frequency of oscillation of the monitoring means so that damped oscillations occur in the monitoring means.
29 Citations
26 Claims
- 1. A passive electrically operable monitoring means for use with a transducer for monitoring a physical parameter, the monitoring means having an inherent resistance and a characteristic capacitance and inductance only, the characteristic capacitance and inductance being responsive to variations in the physical parameter such that the monitoring means has a natural frequency of oscillation that varies in accordance with variations in the physical parameter.
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16. A method of monitoring a physical parameter which includes
energising a passive electrical monitoring means having only a characteristic capacitance and inductance and an inherent resistance so that the monitoring means oscillates at a natural frequency of oscillation; -
causing the characteristic capacitance and the characteristic inductance to vary in response to variations in the parameter being monitored thereby to vary the natural frequency of oscillation of the monitoring means; and sensing the variations in the natural frequency of oscillation of the monitoring means to provide an indication of the value of the parameter being monitored. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification