Digitized displacement transducer

Claim 1

Means for converting a displacement directly into a digital signal that accurately represents the magnitude of the displacement comprising, a differential inductive transducer having first and seconds legs that each include inductive and resistive elements, said legs being arranged in a bridge configuration with a common input and separate outputs, and said inductive elements of each of said legs having a variable inductance, means for producing and applying an electrical excitation signal to said common input, said signal being a train of step-voltage pulses of substantially constant maximum amplitude and pulse interval, said excitation signal producing first and second transient signals at said outputs of said first and second legs, respectively, means for producing a constant reference voltage associated with said excitation signal, means for producing a timing signal associated with each of said legs that is derived from a comparison of said transient output signal to the reference voltage, said transient signal having a duration that corresponds to the time constant of the leg and is a direct measure of the instantaneous displacement of said leg, and means for converting said timing signals into a digital count.

Claim 11

The method of operating a differential inductive electro-mechanical transducer of the type comprising two motion-sensing variable inductances that directly convert changes in the physical position of a body into a high-accuracy digital representation of the magnitude and direction of said displacement, said method comprising the steps of: forming an input terminal of said transducer by connecting the two said inductances at a common point, forming a pair of output terminals of said transducer by connecting a resistor in series with each said inductance, exciting the three-terminal transducer so formed at its input terminal by a step voltage, providing a reference voltage, comparing the transient response at each said output terminal to said input step voltage against said reference voltage, emitting a first and second comparison signal when each said transient response equals said reference voltage, the difference in time between said signals being proportional to said physical displacement, and converting the difference in said comparison signals into said high-accuracy digital representation of the displacement of said body.

Claim 12

The method of operating a differential inductive electro-mechanical transducer of the type comprising two motion-sensing variable inductances that directly convert changes in the physical position of a body into a high-accuracy digital representation of the magnitude and direction of said displacement, said method comprising the steps of: forming an input terminal of said transducer by connecting the two said inductances at a common point, forming a pair of output terminals of said transducer by connecting a resistor in series with each said inductance, exciting the three-terminal transducer so formed at its input terminal by a step voltage, providing a reference voltage, comparing the transient response at each said output terminal to said input step voltage against said reference voltage, emitting a first and second comparison signal when each said transient response equals said reference voltage, the difference in time between said signals being proportional to said physical displacement, and converting the difference in said comparison signals into said high-accuracy digital representation of the displacement of said body.