Magnetoresistive displacement sensor and variable resistor using a moving domain wall
US5936400A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 23, 1996 |
| Grant date | Aug 10, 1999 |
| Priority date | — |
| Expiry date | Dec 23, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B7/30
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The displacement sensor employing a magnetoresistive effect laminate structure consisting of a bottom ferromagnetic layer with a field oriented in one direction, a middle non-magnetic layer, and a top softer magnetic layer. The top softer magnetic layer has two regions of opposing magnetic fields separated by a domain wall, where the magnetic field in one region is aligned with the bottom layer magnetic field. The resistance of the laminate structure changes as the location of the domain wall changes. In one improvement, the domain wall is induced by a pair of opposing semicylindrical magnets magnetized along their semicylindrical surface, forming parallel field lines and leading to a stronger domain wall. In another improvement, there are four laminate structures in an electrical bridge configuration. The bridge is excited by an alternating current source and the output is synchronously measured. The laminate structures are arranged in either a stack or such that pairs of laminate structures are deposited on opposite sides of a common substrate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.