Reduction in Rolling Tilt of Objective Lens Actuators for Optical Disc Drives

Abstract

It is necessary to reduce the inclination of the objective lens in high-density optical disc drives to improve recording and reading characteristics. We have developed a new objective lens actuator that is equipped with an optical disc drive and that moves the objective lens electromagnetically. This actuator has a configuration in which the tracking coils and magnets on one side of the actuator are arranged in reverse to those on the other side to reduce the rolling tilt of the objective lens. The rolling moments generated in the tracking coils on both sides of the actuator occur opposite to each other, and the resulting rolling moment is reduced. We confirmed through numerical analysis and experiments that the rolling tilt amplitude at the rolling resonance of the developed actuator was 90% less than that of the value for a conventional actuator.