Electricity: measuring and testing – Magnetic – Magnetometers
Patent
1993-01-06
1995-04-04
O'Shea, Sandra L.
Electricity: measuring and testing
Magnetic
Magnetometers
324235, 323294, G01R 3306
Patent
active
054041023
ABSTRACT:
A method and apparatus for electrically exciting a magneto-resistor (MR) device that is adapted to sense variations in a magnetic field. Electric current is delivered to flow through the MR device and produce a voltage drop across the resistance the MR device, where the voltage drop varies in accordance with changes in the flux density of the sensed magnetic field. The current flowing through the MR device is limited to a predetermined maximum current value to prevent damage to the MR device due to self heating at elevated operating temperatures. When the delivered current is less than the predetermined maximum current value, the current flowing through the MR device is controlled to maintain a measured characteristic of the voltage drop appearing across the MR device at a desired value. This increases the sensitivity of the MR device over its operating temperature range to variations in the sensed magnetic field. In one embodiment, the delivered current is controlled to maintain the peak voltage appearing across the resistance of the MR device at a desired peak value. In another embodiment, the delivered current is controlled to maintain the average voltage appearing across the MR device at a desired average value.
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Gokhale Kalyan P.
Schroeder Thaddeus
Edmonds Warren S.
General Motors Corporation
Gorbatoff Timothy G.
O'Shea Sandra L.
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