| 摘要 |
PROBLEM TO BE SOLVED: To shorten the adjustment time of a gain. SOLUTION: A disk unit 10 includes a DSP 36, and the DSP core 36a of the DSP 36 generates a focus control pulse and a tracking control pulse in response to a feedback input from a pickup 12. That is, a focus servo loop and a tracking servo loop are formed. The DSP core 36a detects the phase difference between the sine wave of a target frequency and a sine wave on which a input signal is overlapped, and adjusts the gain of the servo loop so that the DC component of a correlative signal correlated with the phase difference may be a zero level. Specifically, when the DC component of the correlative signal is over a predetermined threshold, the amount of gain adjustment is set large and is brought extremely close to the zero level. Meanwhile, when the DC component of the correlative signal is equal to or less than the predetermined threshold, the amount of gain adjustment is set small and brought close to the zero level little by little.
|
