High-Speed Tracking Control System for Broadcast-Use Optical Disk Drive

概要

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A high-speed tracking control system using feed-forward control with the zero phase error tracking method (ZPET-FF control) has been applied to high-data-transfer-rate and high-density optical disk drives for broadcast use. To realize high-data-transfer-rate optical disk drives, the optical head must be controlled for track-following with an accuracy of less than 9 nm during high-speed disk rotation. We compared the characteristics of the tracking accuracy of ZPET-FF control with those of conventional feedback control at 15000 rpm and analyzed their frequency responses in a simulation. The results show that the ZPET-FF control is accurate and robust toward periodic disturbances at high speeds. Experimental results show that ZPET-FF control is more precise than feedback control, and the residual tracking error is suppressed to 8.02 nm at a linear velocity of 18.3 m/s in an optical disk drive having a blue-violet laser (wavelength: 405 nm), an object lens with a numerical aperture (NA) of 0.85, and media with a track pitch of 0.32 μm.
2006-02-15