JPS6444816A - Magnetic rotary encoder - Google Patents

Abstract

PURPOSE:To obtain a high resolution by finding three-phase outputs different in phase at a 120 deg. electrical angle and by subjecting them to an electric circuit processing. CONSTITUTION:In a magnetic sensor 2 for magnetoelectric conversion, magnetore sistance elements A1-A4 and B1-B4 whose electric resistance is varied in accordance with the intensity of a magnetic field are arranged at an equal pitch Ps as two magnetosensitive elements 2a and 2b in one line in the longitudinal direction of the magnetoresistance elements, in such a manner that a structure wherein the magnetoresistance elements are arranged symmetrically with respect to the central axes Cx and Cy in the directions X and Y respectively is obtained. The sensor 2 thus prepared is disposed opposite to a magnetic drum 1 having N-poles and S-poles formed alternately and uniformly at a distance L in multi-pole magnetization, with a gap formed between them. A prescribed voltage is impressed on series-connected circuits of B1 and B2, A2 and A3, and B3 and B4, and the respective intermediate connection points U, V and W are used as voltage detecting terminals. From these terminals, three-phase outputs of U, V and W phases being different in phase at a 120 deg. electrical angle and corresponding to the amount of rotating movement of the drum 1 can be obtained by one pulse for each one of the N- or S-poles.