Multiple capacitor transducer

摘要

A capacitive type pressure, force or displacement sensing transducer comprised of a mating pair of spaced dielectric elements each carrying a pair of capacitive elements forming two like capacitors of variable capacitance value depending upon the variable spacing distance between the dielectric elements and two like capacitors of fixed capacitance value. The pair of variable value capacitors and pair of fixed value capacitors comprise all of the capacitance elements of a Wheatstone bridge circuit in a single structural unit in which such capacitive elements are all subjected to the same temperature and pressure environment and which is not sensitive to stray capacitances. Each pair of capacitors forms opposing sides of the Wheatstone bridge circuit. A source of alternating current of constant voltage and set frequency is applied across a first set of bridge terminals at opposite corners of the bridge and a current detection circuit is connected across a second set of bridge terminals independent of the first set of terminals and at opposite corners of the bridge. Detection and measurement of the current value of the bridge circuit is translated into a value of force, pressure or motion applied to the transducer unit in direct linear relationship with the current value as determined by the separation distance between the spaced dielectric elements of the transducer.