Patent ID: 7345266
Filing Date: 2008-03-18
Classification: G11B

Abstract:
1. An optical medium judging method comprising: positioning an optical focusing unit at a first position, wherein the optical focusing unit comprises an objective lens and an actuator, and the objective lens focuses a laser beam; driving the actuator to move the objective lens to an optical disk by a driving circuit so as to make the laser beam focus a spot on the optical disk; detecting a reflection value by a reading unit; exerting a predetermined voltage difference to the actuator by the driving circuit so as to make the objective lens move a distance relative to the predetermined voltage difference when the reflection value is greater than a predetermined value, wherein the distance is greater than a thickness of the optical disk and smaller than a distance between the objective lens and the optical disk; and continuing to detect the reflection value to judge the type of the disk, wherein the optical focusing unit is located to avoid the lens colliding with the optical disk.