| 摘要 |
PURPOSE:To improve overshoot and undershoot at start and stoppage of motor by controlling the rotary speed of motor based on first and second frequency signals having different frequencies corresponding to the rotary speed. CONSTITUTION:When a spindle motor 12 is started, a CPU 16 provides a start command and a selecting circuit 17 selects first frequency signal while a reference frequency generator 20 outputs a first reference signal. Consequently, a control circuit 18 provides output continuously to a motor driver 13 until the first frequency signal and the first reference signal are equalized, thus starting rotation of the spindle motor 12. When the frequency of the first frequency signal reaches to a specific value, the CPU 16 selects a second frequency signal through the selection circuit 17 and the reference frequency generator 20 produces a second reference signal having frequency 1/24 times that of the first reference signal. Thereafter, rotary speed of the spindle motor 12 is controlled so that the second frequency signal and the first reference signal are equalized. |
