| 摘要 |
PURPOSE:To preclude misdetection by a simple structure and a simple circuit by detecting the variation of a magnetic field by a magnet ring which rotates associatively with a steering wheel, etc., by plural magneto-resistance elements which are arranged opposite to the magnet ring. CONSTITUTION:A guide 6 with which the magnet ring 5 is coupled by utilizing the elasticity of a notch part 25 provided in a peripheral direction is fitted and locked in a cam 4 which rotates associatively with the rotation of the steering wheel of a vehicle. The cam 4 is fitted to a switch main body 1 by engaging a fall-preventive part 12 with the cam lock part 11 of a main body boss 10. Then a sensor unit 8 is fitted to the main body 1 so that magneto- resistance elements 13 and 13a face the ring 5 at all times. This main body 1 is fixed right below the steering wheel through the boss 10. Consequently, when the steering wheel is rotated, the cam, guide 6, and ring 5 also rotate in response to it and the intensity of the magnetic field which operates on the resistance elements 13 and 13a varies. This variation is converted by a pulse generating circuit 14 into a pulse signal, which is transferred to the controller for a microcomputer, etc.
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