Moving-Magnet Tracking and Focusing Actuators for Optical Recording Systems

Abstract

The need for a compact and high-capacity memory storage apparatus has generated much interest in recent years. Due to the increased track density made possible by recent developments, there has been an ongoing attempt to provide an actuator capable of rapid accessing time. To reduce the average accessing time of a memory storage device, a newly developed moving-magnet actuator using an air-core solenoid and multiple permanent magnets is implemented and tested. In a servo-control mechanism, hybrid control which consists of bang-bang, velocity and position controls is used. An advanced servo-control scheme which uses an analog state observer and a disturbance observer is applied to increase the tracking and focusing accuracy. A new linear actuator which theoretically can achieve an accessing time of less than 20 ms at the accuracy required for a 3.5-inch-disk magnetooptical drive is presented. © 1995, The Japan Society of Mechanical Engineers. All rights reserved.