| 摘要 |
PURPOSE:To eliminate trouble such as oscillation of circuit by providing means for driving a motor synchronously at the time of starting, a counter electromotive force detecting means, and means for switching from driving through the starting means to driving through the counter electromotive force detecting means thereby effecting switching of driving after confirmation of the rotation of motor. CONSTITUTION:At first, a CPU 1 outputs a three-phase synchronous driving rotation signal which is then selected by a selector 2 and applied through a driver 3 onto a motor 3. The motor 4 is driven untill a predetermined rotational speed is reached. Driving of the motor is once turned OFF completely, before driving through counter electromotive force takes place, in order to prevent erroneous detection of the motor rotation due to a voltage induced by the driving current. At that time point, the CPU 1 takes in a digital output from an A/D converter 7 and makes a judgment whether the digital value is higher than or equal to a predetermined value. |
