| 摘要 |
PURPOSE: To reduce the number of mechanical parts, to improve the driving force of a brushless motor and to improve a sensing accuracy, in relation to a rotor-position sensing device utilizing the change of the magnetic force of the rotor magnetic pole of the brushless motor. CONSTITUTION: In the output waveform of the rotational position signal outputted from a magnetisum sensing means 18 by a position sensing magnetic- pole 5M, a recessed deformed portion is generated in the previous stage to a peak of each period. On the other hand, the voltage at a predetermined point of the previous stage to the peak of each period in the output waveform of the rotational position signal is held in a sampling way as a reference voltage by a reference voltage generating means 19. Then, the reference voltage is compared with the voltage of the rotational position signal by an index signal synthesizing means 20. In this case, the voltage in the vicinity of the peak of the rotational position signal which appears just after the deformed portion becomes higher than the reference voltage, and as a result, an index signal is generated from the index signal synthesizing means 20. |
