INFORMATION RECORD REPRODUCING UNIT AND METHOD FOR REPRODUCING INFORMATION RECORD

摘要

An information record reproducing unit (1) controls a focus actuator (12) for driving an object lens (11) in an optical axis direction of an optical beam in accordance with a focus error signal corresponding to a clearance between the object lens and a recording surface of a revolving disk (100), thereby performing the focus servo control converging the optical beam onto the recording surface to record information on the recording surface by means of the optical beam or reproduce information recorded on the recording surface. The information record reproducing unit especially includes storage means (201, 10, 232) to prestore AC component for following unintentional movement of the revolving disk in a focus drive signal that is a drive signal for the focus actuator corresponding to a rotation angle of the revolving disk while the focus servo control is turned on, and arithmetic addition means (24, 25, 26) to add stored AC component to the focus drive signal corresponding to the rotation angle of the revolving disk while the focus servo control is turned off.