Patent ID: 6611123
Filing Date: 2003-08-26
Classification: G11B

Abstract:
A servo control apparatus which determines a reproduction gain of a focus servo loop or a tracking servo loop of a disk apparatus, comprising:a phase difference detecting means for detecting a phase difference between an input sine wave and a sine wave being fed-back; an adjusting means for adjusting a loop gain of a servo loop for determining said reproduction gain in accordance with said phase difference; a generating means for generating a correlation signal correlated with said phase difference at every time that said loop gain is adjusted by said adjusting means; a determining means for determining whether or not a DC component of said correlation signal generated by said generating means exceeds a predetermined threshold value; an adjusting amount setting means for setting an adjusting amount of said loop gain to a first predetermined amount when it is determined that the DC component of said correlation signal exceeds the predetermined threshold value, and setting said adjusting amount to a second predetermined amount smaller than said first predetermined amount when it is determined that the DC component of said correlation signal is equal to or smaller than said the predetermined threshold value; a polarity detecting means for detecting a polarity of the DC component of said correlation signal generated by said generating means; a polarity comparing means for comparing said polarity of this time detected by said polarity detecting means and said polarity of last time; and a gain determining means for determining said loop gain adjusted last time or said loop gain adjusted this time as said reproduction gain when a comparing result of said polarity comparing means indicates a reverse in polarity and also said second predetermined amount is set.