Focus servo recovery processing method for optical disc device and optical disc device

摘要

In an optical disc device employing a CLV method, executing pickup return processing when focus drop occurs during recording poses problems of increased waiting time for rotation and increased focus servo recovery processing time. When defocusing occurs and focus pull-in cannot be achieved by retry, a first rotation frequency at a radial position thereof is calculated. Next, a second rotation frequency at the innermost circumferential position at the current speed is calculated. Next, a third rotation frequency at a radial position where recording is restarted after focus servo recovery is calculated. Next, a fourth rotation frequency at pickup return position at a different speed is calculated. Next, based on the relationship among the first to fourth rotation frequencies described above, a rotation speed at pickup return is selected so that a rotation frequency difference becomes the smallest in all conditions: at pickup return from defocusing, servo recovery after pickup return, and access operation after the servo recovery.