光ディスク用軸しゅう動レンズアクチュエータの二段トラッキング制御特性の改善

概要

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Positioning accuracy of a two-stage tracking control system using a rotary lens actuator is degraded by impact vibration due to the small clearance of the slider bearing. This paper presents the design of a rotary lens actuator with preload in the tracking direction in order to improve the two-stage tracking control characteristics. The stiffness of the bearing, which is described as a nonlinear spring element, mainly depends on the amount of preload. The preload needed for stable and precise two-stage tracking at 1800 rpm is estimated to be equivalent to 20% of the moving mass of the lens actuator. The transfer functions of the lens actuator in the tracking and focusing directions showed no degradation due to preloading, while the transfer function of the positioner was greatly improved. The tracking and focusing errors caused by preloading are sufficiently small compared with the allowable positioning errors.
1994-08-25