DISC DEFECT PREVENTING DEVICE AND METHOD THEREOF

摘要

PURPOSE: A disc defect preventing device and a method thereof are provided to take measures for situations possibly generating defect on a disc by close approach of an objective lens. CONSTITUTION: A method for preventing defect of a disc includes the steps of carrying out focus pull-in operation by a pickup, and forcibly moving the pickup away from a disc by applying a strong DC current to an actuator. During the focus pull-in, if the pickup approaches the disc suddenly by external impact, a focus error signal exhibits a waveform dropping from a predetermined DC level and a pull-in signal level drops to an initial value smaller than a threshold value. If the dropped level of the pull-in signal continues for a predetermined time, the pickup moves to the disc and an objective lens comes into contact with the disc. Therefore, before the objective lens contacts the disc, the strong DC current is applied to the actuator.