| 摘要 |
PURPOSE:To obtain a brushless motor drive circuit which can detect the positional signal of a rotor accurately by comparing the voltage at the end of a stator coil with a predetermined potential for each phase. CONSTITUTION:When the voltage at the end of each stator of a brushless motor 106 is compared with a predetermined potential in order to detect the positional signal of a rotor, a pulse generation circuit 1 generates a pulse of predetermined width in the vicinity of rise and fall of the positional signal. The pulse is fed, as a time constant switching signal, to a low-pass filter 104 in order to switch the time constant thereof to a larger one. Consequently, the noise components are removed from the drive signal in the vicinity of rise and fall of the positional signal. This constitution realizes accurate positional detection of the rotor in a brushless motor and enhances the rotational accuracy. |
