Differential reluctance motion detector

Claim 1

A displacement detecting system yielding an electrical output signal that is linearly proportional to the extent of an applied input motion, said system comprising: A a differential reluctance motion transducer having a pair of symmetrically arranged transformers, each having a core, a primary, a main secondary and an auxiliary secondary, and an armature laterally movable in accordance with said input motion from a neutral position between the cores to a position toward one of the cores and away from the other; B an oscillator generating a high-frequency a-c drive voltage which is applied to the primary of each transformer to cause an excitation current to flow therein which is a function of the position of said armature, said excitation current causing a voltage to be induced in said main and auxiliary secondaries which is a function of the inductance of the primary of each transformer as well as the coupling coefficient between the primary and secondaries thereof, the induced voltage being a function of said excitation current and giving rise to a non-linear relationship between the motion of said armature and the induced voltage; and C means to reduce said non-linear relationship including a feedback loop having a regulator comparing a feedback voltage derived from said auxiliary secondaries connected in series coincidence with a reference voltage to produce a control voltage which is applied to said oscillator to regulate said drive voltage.