| 摘要 |
PURPOSE:To drive a disk motor at high efficiency and lower power consumption by detecting that a synchronizing signal pattern included in pickup data is deviated from a normal pattern by more than a specified value and selecting high driving voltage. CONSTITUTION:APC signals and AFC signals formed from pickup data by a PLL circuit 15, a CLV servo circuit 16 etc., are processed by an adder 17 and control signals are generated. The signals are converted to PWM signals by a PWM modulation circuit 18, and the level is controlled by a BTL driving circuit 20 to which low voltage V1 is supplied from a change-over switch 24, and a disk motor 12 is servo driven at high efficiency by an optimum duty ratio signal. On the other hand, when a synchronizing signal pattern included in pickup data outputted from the circuit 15 is deviated from a normal pattern by more than a specified value by deviation from the state of servo drawing, the switch 24 is changed by a detecting circuit 25, and high voltage V2 is supplied to the circuit 20 instead of low voltage V1, and the motor 12 is driven at high efficiency by high gain control. Power consumption can be lowered by this high efficiency driving.
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