| 摘要 |
PURPOSE:To detect an absolute position within one revolution by a method wherein a magnetoresistance element positioned opposite to a rotor magnet is provided and the sensitivity of the magnetoresistance element to a magnetic pole is made to have a distribution width covering the whole circumference of the magnetic pole in relation to the direction of displacement of the magnetic pole. CONSTITUTION:When a magnetoresistance element 4 having a unit sensitivity is put at a position of an angle delta, a variation in the reluctance of the element 4 is expressed by a function of theta-delta when the rotational angle of a rotor magnet 1 is denoted by theta. The element 4 used herein consists of magnetoresistance bodies of (n) in numbers which have such a sensitivity distribution that the sensitivity Sj at the position of the angle delta in the direction of rotation of the element 4 is expressed by Sj=alpha+betacos(delta+2pi.j/n) (wherein alpha is an arbitrary real number, beta a real number not being zero, (n) an integer of 3 or above, and (j) an integer of 0-n-1). An AC voltage is impressed on the terminals on one side of the magnetoresistance bodies, the terminals on the other side thereof are connected together respectively with respect to all of the magnetoresistance bodies, and a rotational angle is determined form a phase difference between an AC signal obtained at each connecting point and the impressed AC voltage.
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