Proximity detection system utilizing a movable magnet for saturating an inductor core wherein the rise time of a plurality of such inductors are compared
US4140971A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 10, 1977 |
| Grant date | Feb 20, 1979 |
| Priority date | — |
| Expiry date | Nov 10, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/08
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus and method is disclosed for determining the position of a mechanical part from among a plurality of discrete positions. An inductor with a saturable core is placed in proximity to each position so that a permanent magnet attached to the part saturates only the core nearest the part, thereby reducing the inductance of that particular inductor. The variation in inductances are detected by comparing voltage rise times across a current limiting resistor serially connected to each inductor. The voltage across the resistor connected to the inductor nearest the position of the part will have the shortest rise time. In a two position embodiment, the variation in rise times is detected by a R/S flip-flop with each input coupled to one each of the inductors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.