Digital servo system for obtaining by calculation a control signal corresponding to a desired value on the basis of the change of a control signal and a controlled signal

摘要

A tracking servo system for controlling the positional difference between a recording track of an optical disk and a light beam emitted on the track, in which the amount of offset control applied to an offset adjusting amplifier provided in the servo loop is varied and the center value of the positive and negative peak values of a track error signal obtained at that time is computed. Then, the relation between the amount of offset control and the center value of the peak values of the track error signal is determined and the amount of offset control corresponding to the desired center value of the peak values of the track error signal is obtained on the basis of the determined relation. Further, a laser beam emission power adjusting system used for recording and/or reproducing in an optical disk apparatus is disclosed, in which the laser beam emission adjusting output is varied and the amount of beam emission power obtained at that time is detected. Then, the relation between the laser beam emission adjusting output and the amount of beam emission power is determined and the value of the laser beam emission adjusting output corresponding to the desired amount of beam emission power is obtained on the basis of the determined relation.