Kaman Sciences Corporation

Kaman Instrumentation Corporation

Kaman Corporation

William A Holmgren

Gregory H Ames

John S Hasling

A Lee Widener

Richard W Denny

A novel thin, three-terminal capacitive transducer which is positioned in a clearance gap to be measured is presented. This transducer comprises an insulated assembly having three parallel conductive planes with the first and second plane each containing a single electrode and the third plane containing a pair of spaced electrodes. Preferably, each electrode is composed of a thin layer of copper mounted on an insulated substrate such as an epoxy-glass composite. An air space is provided between each of the pair of electrodes in the third plane and the single electrode in the second plane. Another important feature of the present invention is a novel electronic circuit for use in conjunction with the novel three terminal capacitive transducer. This circuit provides a means of 'synthetic resonance' whereby a small capacitance (such as generated by the three-terminal capacitive sensor of this invention) functions as if it were at or near series resonance with a synthesized large inductance. This is achieved by using a synthesized network (which is a variation of a known twin-tee circuit) in the feedback path of a high gain amplifier, thereby inverting the normal rejection notch into a resonance-like peak at a frequency determined mathematically.

Capacitive sensor and electronic circuit for non-contact distance

An inductive displacement sensor includes an oscillator circuit that is characterized by primary and secondary pairs of coils disposed on opposing surfaces of adjacent optical segments. Each coil in both coil pairs is alternately positioned along a respective axes perpendicular to a segment displacement axis. The secondary coils are respectively tuned to frequencies above and below the oscillator circuit resonant frequency. Any motion between segments along the displacement axis induces a detectable change in phase between the current and voltage of the oscillator signal.

Inductive sensor for detecting displacement of adjacent surfaces

This distance measurement system employs the principle of electromagnetic induction to sense distances between an inductive transducer and an object. The inductive transducer forms a part of a signal phase network, and a means for comparing the signal of the inductive transducer to a reference signal provides linear output of the dimension between the transducer and an object. A circuit element such as a capacitor is connected in parallel with the inductive transducer to enhance the sensitivity and resolution of the measurement, to significantly reduce or eliminate error due to temperature, and to provide a high degree of output linearity relative to the distance measured.

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Colorado Springs, CO, United States of America

William A Holmgren