Patent ID: 7791985
Filing Date: 2010-09-07
Classification: G11B,H01F

Abstract:
1. An objective lens driving apparatus comprising: an actuator movable unit including a lens holder holding at least one objective lens and a plurality of driving coils, wherein a magnetic circuit that includes a first magnet and a second magnet fixed to the actuator frame to form an effective magnetic field for the plurality of driving coils, the first and second magnets facing the first and second side surfaces of the lens holder, respectively; and a rolling canceling coil that is so mounted on the lens holder as to act on the effective magnetic field formed by the magnetic circuit such that a driving force is generated in a tilt direction that cancels rolling generated when a drive signal is supplied to the tracking coils to drive the actuator movable unit in the tracking direction, wherein the first and second side surfaces, the respective driving coils, and the rolling cancelling coil are disposed symmetrically with respect to a virtual line passing through a light axis of the objective lens in the tracking direction, wherein respective winding center axes of the tracking coils and the rolling canceling coil are orthogonal to the light axis of the objective lens, and wherein the first magnet and the second magnet include regions of opposite magnetic polarity such that each tracking coil faces a boundary between regions of opposite magnetic polarity parallel to the light axis of the objective lens and the rolling canceling coil faces a boundary between regions of opposite magnetic polarity orthogonal to the light axis of the objective lens.