Proximity detector employing magneto resistive sensor in the central magnetic field null of a toroidal magnet
US4857841A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 29, 1987 |
| Grant date | Aug 15, 1989 |
| Priority date | — |
| Expiry date | Dec 29, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/9517
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
The present invention is a proximity sensor employing a magneto resistive structure. This proximity sensor includes a toroidal magnet having a central aperture, an inner circumference and an outer circumference. This toroidal magnet has a first magnetic pole at the inner circumference and a second magnetic pole at the outer circumference thereby creating a magnetic field null at a center portion of the central aperture. A magneto resistive structure is disposed at the magnetic field null in the central aperture of the toroidal magnetic. This magneto resistive structure has a resistance dependent upon magnetic flux. The proximity of a magnetically permeable target to the toroidal magnet shifts the position of the magnetic null, thereby causing a large change in the magnetic flux through the magneto resistive structure. An electrical detection circuit detects changes in this resistance for indication of the proximity of the magnetically permeable target.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.