Eddy current distance measuring device with temperature change compensation circuitry
US5043661A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 12, 1989 |
| Grant date | Aug 27, 1991 |
| Priority date | — |
| Expiry date | Jun 12, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D3/036
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The damping of a coil (L1) can be influenced by an object (1) so that the high-frequency voltage at the coil (L1) depends on the distance (a) of the object (1) from the coil (L1). A constant dc current is superimposed on the high-frequency current through the coil, the dc voltage drop at the coil (L1) which corresponds to the dc resistance of the coil (L1), damping the coil (L1), being influenced by the temperature. The high-frequency excitation (5, 6) of the coil (L1) is controlled by the dc voltage drop in order to compensate for the influence of the temperature on the high-frequency voltage so that the high-frequency voltage depends solely on the distance (a). The high-frequency voltage, having a nonlinear correlation to the distance (a), is linearized in a nonlinear member (15) with a semiconductor element with respect to the distance (a). In this connection, the effect of the temperature on the linearization is compensated for by means of a second semiconductor element.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.