Patent ID: 6031812
Filing Date: 2000-02-29
Classification: G11B

Abstract:
An actuator for use on an optical pickup to move an objective lens, comprising:a lens holder for holding the objective lens;a shaft axially coupled to said lens holder;a plurality of magnets for producing magnetic fields, wherein the N and S poles of said magnets are in a direction perpendicular to a longitudinal axis of said shaft;a focusing coil which has four sides and interacts with the magnetic fields from said magnets when excited to thereby produce a magnetic force that moves said lens holder along said shaft to perform a focusing action, wherein the face of said focusing coil is perpendicular to the longitudinal axis of said shaft, and each side of the focusing coil corresponds to one of said magnets;a tracking coil which interacts with the magnetic fields from said magnets when excited to thereby produce a magnetic torque that rotates said lens holder about said shaft to perform a tracking action, wherein the face of the tracking coil is parallel to the longitudinal axis of said shaft;a magnetic-levitation structure including at least a first magnetically-attractable bar and a second magnetically-attractable bar, which are disposed in relation to said magnets in such a manner that the magnetic force acting on said first magnetically-attractable bar is equal in magnitude and opposite in direction to the magnetic force acting on said second magnetically-attractable bar, thereby allowing said actuator to be restored to a neutral position after a focusing and tracking operation is completed.