Patent ID: 8072869

Claim:
An optical pickup which is capable of correcting spherical aberration, comprising: an objective lens condensing light beams emitted from a light source to a recording surface of an information recording medium; a plurality of aberration correction lenses correcting spherical aberration of laser light condensed to the recording surface by the objective lens; a movable portion in which at least one lens of the plural aberration correction lenses is held; a fixed portion in which the movable portion is arranged so as to be slidable and in which the aberration correction lens which is not held by the movable portion is held; a shaft arranged at the fixed portion in parallel to an optical axis of the light beams, supporting the movable portion so as to be rotatable about an axis of the shaft as well as to be slidable in a direction of the axis of the shaft; a feed screw arranged in parallel to optical axes of the plural aberration correction lenses, having spiral grooves; an engaging portion provided at the movable portion, having convex portions to be engaged with the spiral grooves of the feed screw from one direction; and a coil spring fitted to the outside of the shaft, pressing the movable portion in the direction of the axial of the shaft, and wherein one end portion of the coil spring includes a rotation prevention portion engaged with the fixed portion for preventing rotation, the other end portion of the coil spring includes a torque biasing portion engaged with the movable portion for biasing force rotating the engaging portion in the side of the feed screw about the shaft, the coil spring is installed in a twisted state in advance, and the convex portions serve as teeth, and on an occasion of failure, the teeth come off the spiral grooves of the feed screw, thereby preventing breakage.