JPS6416919A - Rotational angle detector - Google Patents

Abstract

PURPOSE:To preclude misdetection due to dust, etc., by providing plural magneto-resistance elements opposite a gear-shaped rotor and providing a circuit which converts the variation of a magnetic field detected by those magneto- resistance elements into a pulse signal. CONSTITUTION:Sensors 24 and 24a consists of the magneto-resistance elements 18 and 18a and pulse generating circuits 19 and 19a. The pitch of the two elements 18 and 18a is p/2, where (p) is the tooth-to-tooth pitch of the gear- shaped rotor 14 and p/2 is the tooth width of the rotor 14. Further, a magnet 20 is mounted on the same substrate with the sensors 24 and 24a. Then when the rotor 14 passes in a constant magnetic field produced by the magnet 20, the variation of the generated magnetic field is detected by the element 18 and 18a and converted by the circuits 19 and 19a into pulse signals, which are sent to an external controller. The controller computes and detects the quantity of rotation of a steering angle from the number of pulses and the rotating direction from the timing of the pulse generation of the sensors 24 and 24a.