GERÄT UND VERFAHREN ZUR WIEDERGABE VON DATEN VON MEHRSCHICHTIGEN PLATTEN

A method for moving the focus of an object lens from one layer to another in a disk having data recorded on a plurality of layers comprises: a first step for accelerating an object lens in a first direction; a second step for detecting that a focus error signal surpasses a first voltage and for accelerating the object lens in a second direction different from the first direction; a third step for detecting that the object lens has moved for a predetermined duration of time and for accelerating the object lens in the first direction; and a fourth step for detecting that the focus error signal surpasses a second voltage and for starting focus servo control. The method and apparatus can reliably catch the just-focus point of a layer and reduce the time required for movement from one layer to another.