Electricity: measuring and testing – Magnetic – Displacement
Patent
1993-10-01
1995-12-12
O'Shea, Sandra L.
Electricity: measuring and testing
Magnetic
Displacement
324252, 338 32R, G01B 700, G01R 3302, H01L 4300
Patent
active
054753040
ABSTRACT:
A giant magnetoresistant displacement sensor includes at least one layered structure. This layered structure includes a harder magnetic (ferromagnetic or antiferromagnetic) layer having a fixed magnetic state, a second, softer, magnetic layer, and a metal layer interposed between and contacting these two layers to prevent exchange coupling between the two layers. The sensor also includes one or more indexing magnets for inducing a domain wall, at a measurand position, between regions of nonaligned magnetic fields in the softer magnetic layer; and an ohmmeter for measuring electrical resistance between points on opposite sides of the structure. In operation, the indexing magnets for inducing a domain wall are positioned relative to the giant magnetoresistant strip. The resistance across the strip is measured, and from this resistance measurement the position of the domain wall is determined. The present invention is also a variable resistor, which is operated by positioning the magnets for inducing the domain wall at a selected position, to set the resistance across the strip to a desired value.
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Karasek John J.
McDonnell Thomas E.
O'Shea Sandra L.
Patidar Jay M.
The United States of America as represented by the Secretary of
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