Patent ID: 9047883
Filing Date: 2015-06-02
Classification: G11B

Abstract:
1. An optical pickup device comprising: a light source that emits a light beam of a predetermined wavelength; a single objective lens that focuses the light beam from the light source to irradiate a disk-shaped recording medium; an objective lens actuator that drives the objective lens; a photodetector that receives, via the objective lens, a light beam reflected by a recording surface of the disk-shaped recording medium to converts the received light into an electric signal; and an optical base that holds the light source, the objective lens actuator, and the photodetector, wherein the objective lens actuator comprises: a lens holder that holds the objective lens; a support mechanism that supports the lens holder so that the lens holder is movable in a focusing direction, which is a direction perpendicular to the disk-shaped recording medium, and a tracking direction, which is a radial direction of the disk-shaped recording medium; a focusing coil that is fixed to the lens holder and drives the lens holder in the focusing direction; a tracking coil that is fixed to the lens holder and drives the lens holder in the tracking direction; an actuator base that holds one end of the support mechanism; and a magnet that is held on the actuator base and disposed at a position opposing the focusing coil and/or the tracking coil, and also applies a magnetic field to the focusing coil and/or the tracking coil, a first gap and a second gap are formed between the lens holder and the objective lens, when the disk-shaped recording medium rotates clockwise, and in an xy plane in which the center of the objective lens is defined as an origin, the tracking direction is defined as an y axis, and the tangential direction of tracks of the disk-shaped recording medium is defined as an x axis, a center side of the disk-shaped recording medium is defined as a positive direction for the y axis, a direction obtained by rotating the positive direction of the y axis clockwise through 90° is defined as a positive direction for the x axis, and four regions obtained by dividing the xy plane by the x axis and the y axis are defined as a first quadrant, a second quadrant, a third quadrant, and a fourth quadrant in the counterclockwise direction, the first gap is positioned at least in the first quadrant, and the second gap is positioned at least in the third quadrant, a center of the first gap is positioned on a straight line obtained by rotating a positive-direction portion of the x axis counterclockwise through 30°, and a center of the second gap is positioned on a straight line obtained by rotating a positive-direction portion of the x axis counterclockwise through 210°.