Method and apparatus for continuously measuring distance utilizing eddy current and having temperature difference influence elimination
US4567435A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 23, 1984 |
| Grant date | Jan 28, 1986 |
| Priority date | — |
| Expiry date | Feb 23, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B7/102
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The distance between the tip of a probe and a high-temperature object of measurement is continuously and accurately measured by arranging the probe comprising a primary coil and a pair of secondary coils substantially vertically to the object of measurement; inducing an AC voltage (e.sub.1) and an AC voltage (e.sub.2) respectively in the pair of secondary coils by means of an AC magnetic field of the primary coil excited by an output voltage (e.sub.out) of a positive feedback amplifier; generating an eddy current in the object of measurement by means of the AC magnetic field of the primary coil to generate another AC magnetic field in the direction opposite to that of the AC magnetic field of the primary coil; impressing an equal DC voltage onto each of the pair of secondary coils to detect respectively a DC voltage (E.sub.1) and a DC voltage (E.sub.2) of the pair of secondary coils; calculating an error voltage (e.sub.4) corresponding to the difference in temperature between the pair of secondary coils, on the basis of the output voltage (e.sub.out) and a value of difference (E.sub.3) between the DC voltages (E.sub.1) and (E.sub.2); and feeding a value of difference (e.sub.3") bet…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.