Rotation Detecting Apparatus

摘要

Sensors for motor and a reference position sensor are integrated in a sensor magnet for detection. An annular sensor magnet is formed with a magnetized zone M1 corresponding to sensors 11U, 11V, and 11W for motor and with a magnetized zone M2 corresponding to a reference position sensor 12. The individual magnetized portions of the magnetized zone M2 are shifted as a whole in a leftward direction by a distance D from the magnetized zone M1. However, the direction of shifting has been partly reversed. Specifically, the magnetized portion 23 of the magnetized zone M2 is shifted in the right direction so that the magnetized portions 24 and 25 are narrowed accordingly. In this magnetized structure, the level of an output of the reference position sensor 12 is determined by generating triggers E1 to E6 on the rising edges of the sensor 11W for motor. Since the level is determined to be LOW only at one position, the output of the reference position sensor is fetched based on the determination.