| Summary: | 博士 === 國立交通大學 === 機械工程系所 === 95 === This study aims to realize near-field optics and solves the requirement of data increasing recording capacity. For near-field recording, the distance between the slider and optical disk surface, i.e. the flying height must maintain stable. As a flying height actuator, a piezoelectric bender is used to implement the flying height control in near-field optical disk drives.
Firstly, this study designs a flying pickup head including a piezoelectric bender to complement VCM to control both focusing and track-seeking/track-following motions simultaneously. The pickup head structure differs from traditional CD-ROM and DVD-ROM pickup heads. Secondly, the pickup head is very close to an optical disk whose surface contains numerous grooves. Thus the dynamics between the optical disk and the pickup head must be investigated. Different from laser Doppler interferometers, an optical lever method using two quadrant photodetectors is developed to measure the flying height variation of a pickup head above a rotating disk. Finally, adaptive inverse control and PID control are used to implement focusing and track-following, respectively. Coupling between focusing and track-following is incorporated in derivation and computer simulation.
This study analyzes the effect of grooved surface on flying, carries out experiments for flying height measurement and control with the pickup head, and investigates effects of horizontal deflection of the bender on track-following. For air bearing disturbance canceling, the proposed method is validated. Regarding simulation, dealing with air flow disturbance the previous method only cancels 43 %. By contrast, the proposed method can cancel disturbance up to 80 %. In experiments, the proposed method yields tracking error of 13 %, in contrast to 27 % by using the previous method.
|
|---|
