METHOD AND APPARATUS OF FOCUS JUMP IN PHOTO-DISK SYSTEM HAVING DOUBLE-LAYER STRUCTURE

摘要

PURPOSE: A method and apparatus of focus jump in photo-disk system having double-layer structure is provided to perform focus jumping with safety by controlling jump speed referring a focus error signal and a level of radio frequency(RF) in acceleration range. CONSTITUTION: In the method of moving focus of a laser beam among record layers, the focus jumping method is comprising steps of accelerating an objective lens to a target record layer by applying pulse to desired direction of actuator, decelerating the objective lens for stopping at focus point of the target record layer from an insert point after deciding if the objective lens is in focus inserting region of the target record layer referring a focus error signal generated from a photo-pickup, speed controlling for the objective lens to be stopped by referring the RF signal generated from the photo-pickup at a point which a level of the RF signal returns to a normal level.