Servo apparatus for optical disk player having both open loop coarse gain control and closed loop fine gain control

摘要

A servo apparatus for an optical disk player which coarsely adjusts the loop gain in advance in an open state of a servo loop, and then closes the servo loop to finely adjust the loop gain. This ensures accurate and sure gain control even if there are differences between reflection factors of the recording surfaces of disks being played or is a stain or the like on an objective lens of the player.