A METHOD FOR GRADUALLY CLOSING DOWN A FOCUS CONTROL LOOP OF AN OPTICAL DRIVE SYSTEM

摘要

The present invention relates to a method for operating an optical drive system (12) capable of reproducing/recording information from/to an optical carrier (1), wherein the optical drive system includes a focus controller (PID) for controlling a focus actuator (4), and a focus memory loop (ML) for applying a stored correction signal to the focus actuator (4). The method aims at avoiding impacts between the focussing means (3) and the optical carrier (1), by gradually stopping the focus control loop in response to an event, such as a user initiated ejection of the optical carrier. The gradual stop of the focus control loop is achieved by gradually reducing a memory loop parameter of the focus memory loop (ML), and by gradually reducing a controller parameter of an integrating part (I) of the focus controller (PID). It is an advantage of the invention that the phase of the stored correction signal is synchronized with the angular position of optical carrier (1) during the gradual stopping.