Patent ID: 8614936
Filing Date: 2013-12-24
Classification: G11B

Abstract:
1. A pickup head, comprising: a plurality of light sources configured to irradiate light beams on an information recording medium comprising a plurality of information recording layers, the light sources including a first light source and a second light source, the information recording layers including a first recording layer and a second recording layer, the first recording layer and the second recording layer being in different positions in the information recording medium; a first objective lens configured to focus a first light beam from the first light source at the first recording layer to form a first light spot; a second objective lens configured to focus a second light beam from the second light source at the second recording layer to form a second light spot; a driving unit configured to move the first objective lens in a first direction and a second direction and to move the second objective lens in the first direction and the second direction, the first direction being parallel to the surfaces of the information recording layers and perpendicular to a data recording direction of a track of the information recording layers, the second direction being a stacking direction of the information recording layers; a first control unit configured to correct a displacement from target track along the first direction, the target track being irradiation target of a first light spot; a second control unit configured to control a position of the second light spot, the position being moved in the second direction; and one or more light receiving units configured to receive a first reflected light and a second reflected light, the first reflected light being a light beam that the first light beam is reflected by the first recording layer, the second reflected light being a light beam that the second light beam is reflected by the second information recording layer.