Lens actuator incorporated in optical information storage system for promptly canceling fluctuation of radial tilt angle of rotating disc

A lens actuator incorporated in an optical head used for an optical disc driven for relative rotation to said lens actuator, comprising:

• a lens unit including a lens for condensing light onto a target portion in said optical disc and a lens holder for retaining said lens;
• a stationary member on which an orthogonal coordinate system is represented by a focusing direction parallel to an axis of rotation in said optical disc, a tracking direction parallel to a radius of curvature of said optical disc and a tangential direction perpendicular to said radius of curvature;
• a first electromagnetic actuator having a first coil fixed to said lens holder and a first magnetic piece fixed to said stationary member, and urging said lens holder in a first direction parallel to said focusing direction;
• a second electromagnetic actuator having a second coil fixed to said lens holder and a second magnetic piece fixed to said stationary member, and urging said lens holder in a second direction parallel to said tracking direction;
• a third electromagnetic actuator having third coils fixed to both side surfaces of said lens holder so as to wound in parallel to said both side surfaces and third magnetic pieces fixed to said stationary member so as to be opposed to said third coils, and urging said lens holder to rotate about a third direction parallel to said tangential direction;
• and
• two sets of connecting rods formed of elastically deformable material, equivalent to one another from the viewpoint of a strength of materials, and connected between said stationary member and said both side surfaces in such a manner that a center of each of said third coils is on an extension line of a certain connecting rod of associated one of said two sets and that remaining connecting rods of said associated one of said two sets are symmetrically arranged with respect to said certain connecting rods.