Linear capacitance displacement transducer
US4961055A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 4, 1989 |
| Grant date | Oct 2, 1990 |
| Priority date | — |
| Expiry date | Jan 4, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/2412
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A linear capacitance displacement transducer for measuring absolute displacement is formed from a coaxial variable capacitor and a precision capacitance measuring electronic circuit. The plates of the coaxial capacitor are attached to the members of an assembly whose displacement relative to one another is to be determined. Linear displacement of the members causes a linear displacement between the capacitor plates which is reflected in a linear capacitance change. A capacitor controlled oscillator utilizes the coaxial variable capacitor at its input. The capacitor controlled oscillator whose period of oscillation is been determined by the capacitance and locked in phase with changes of capacitance is utilized as a precision measure of capacitance. The period of the square wave output of the oscillator is a linear function of the capacitance of the variable capacitor at any time. The transducer may be adapted to determine the absolute position of a piston rod in a hydraulic cylinder.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.