Linear variable displacement transducers including phase shifting series connected coils

Abstract

A displacement transducer has a movable slug which varies the mutual inductance of two coil sections. The coil sections are connected in a network which causes a variation of phase shift in a signal from an oscillator on movement of the slug. A phase detector detects this phase shift. The use of a variable phase design overcomes the need for high gain linear amplification and the problem of noise in conventional variable amplitude linear variable displacement transducers. The variable phase shift network obviates the need for balanced amplitude quadrature input signals of one known variable phase transducer, while giving a linear phase shift wihtout the need for a specially shaped slug as in another known variable phase transducer.

Dependencies are inferred from the claim text.