| 摘要 |
PROBLEM TO BE SOLVED: To realize high resolution at a low cost, without shortening the period of magnetizing of a magnetic scale while keeping wide the air gap and without enlarging a magnetoresistive sensor. SOLUTION: A magnetic scale 20, consisting of permanent magnets alternatingly magnetized of N-poles and S-poles with a periodλmg and a magnetoresistive sensor 22 facing with an air gap, are combined. A magnetoresistance sensor has one or more sensor parts, in which two resistor parts are connected in series and one or both of the resistor parts consist of magnetoresistive elements. By impressing direct current voltage between two ends of the sensor parts, the voltage variation according to the relative movement is extracted from the intermediate connection point of both resistor parts. The resistance parts of the one or both sensor parts consist of a group of magnetoresistive elements which a plurality of magnetoresistive elements are arranged at intervalsλmg/2n in the relative movement direction and connected in series. Each magnetoresistive element has a characteristic, saturated magnetically in a range outside of±λmg/4n from the reference position opposite to the neutral zone of the magnetic scale.
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