| 摘要 |
PURPOSE:To optimize servo gain even in case of time aging of a laser output, the surface vibration of a disk and the variation of eccentricity occurs by rectifying and integrating a tracking error signal, and controlling the gain so that the integral value becomes minimum. CONSTITUTION:An error signal of tracking, etc. of a disk head 5, which is formed by an error signal generating circuit 12 is processed by a both wave rectifying circuit 22, an integration circuit 23 and a minimum value following circuit 24 for forming a feedback circuit in a servo-circuit. Subsequently, a feedback signal by which an output of the circuit 23 becomes minimum is outputted from the minimum value following circuit 24, a resistance value by an FET25 is varied, and the gain of the servo-circuit is brought to a feedback control. According to them, even in case of time aging of a laser output, a surface vibration of a disk and a variation of eccentricity, the gain of the servo-circuit is always optimized, and a tracking, a focusing control, etc. are executed satisfactorily. |
