| 摘要 |
PURPOSE:To attain the highly efficient drive and the low power consumption of a focus actuator part by providing a power changeover means switching the 1st voltage level into the 2nd voltage level higher than the 1st voltage level when a detection signal is generated from an external vibration detection means. CONSTITUTION:The external vibration detection circuit 23 generates an L level detection signal when the external vibration given to a compact disk player is within a prescribed value and generates an H level detection signal when a prescribed value or over. Thus, when the external vibration is small, a power voltage V1 is fed to a BTL drive circuit 18, the peak of the pulse width modula tion signal is suppressed lower, the duty ratio is increased and the focus actuator part is driven with a high efficiency. When the external vibration is large, the power voltage V2 is fed to the BTL drive circuit 18 to increase the peak of the pulse width modulation signal and to increase the focus servo gain. Thus, the focus servo is applied with high efficiency and the power consumption is reduced. |
