| 摘要 |
PURPOSE:To switch the driving current of each driving coil at an accurate timing even when the torque is generated in reverse direction to the rotational direction in a brushless motor drive circuit wherein the driving current of the driving coil is switched through utilization of counter electromotive force induced in the driving coil. CONSTITUTION:Control is made so that the zero-cross point of counter electromotive force is detected upon finish of driving current supply to each driving coil while detection of the zero-cross point is inhibited upon detection of the zero-cross point of the counter electromotive force or upon start of driving current supply based on thus detected zero-cross point. Consequently, zero-cross point can be detected only when switching of the driving current is required. |
