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Passive and Wireless Displacement Measuring Device

Abstract: 

A system that remotely measures displacement between two objects. A passive sensor is affixed between the objects. The internal sensor uses magnetic coupling between two sensor elements to measure their relative displacement. The sensors are either a) a permeable rod and a complimentary coil in parallel with a tuning capacitor; or b) two permeable rods, each having its own surrounding coil and a tuning capacitor. One of the sensor elements is affixed to each object which is to be monitored. When an interrogating device is placed near the sensors, a resonance can be measured whose frequency characteristics change in a reproducible manner with the relative displacement of the sensors. The resulting resonance characteristics can be calibrated in such a way as to enable the displacement of the objects to be determined.

Patent Number: 
6,656,135
Date Of Issue: 
12/02/2003
Inventors: 

Susan Zogbi; Larry D. Canady; Jerome A. Helffrich; Stephen A. Cerwin; Kevin S. Honeyager; Armando de los Santos; Christopher B. Catterson