Stable Rotation of Optical Disks over 15000 rpm

Abstract

A high data transfer rate is constantly demanded for optical disk drives. One of the solutions is to rotate a disk at a high rotational speed. We need a stable rotation of optical disks and a robust servo control to realize high-rotation-speed optical disk drives. It is difficult to rotate conventional polycarbonate optical disks, whose thickness is 1.2 mm, over 15000 rpm without vibrations. We measured and analyzed disk vibrations at high rotational speeds, and found a condition for suppressing the vibrations of the disks. We confirmed the stable rotation without vibrations up to 20000 rpm under this condition. We also conducted an experiment on tracking servo control at high rotational speeds. We used a double-boosted high-gain servo controller to suppress disturbances at high rotational speeds, and confirmed the robust servo control at 21000 rpm with this controller. #

Focusing control system for suppressing multi-harmonic disturbances in high speed optical disk systems

“…Therefore, in this paper, a 2nd-order plant system model P 2 (z) considering only the first resonant frequency is used to design the control system. The 2nd-order plant system is expressed as (1).…”

“…Hence, a next-generation 0.1-mm-thick optical disk has been developed. Rotation speed of this thin optical disk of over 15,000 rpm has been achieved [1], [2]. Therefore, the fastest data rate, 252 Mbps, is realized by the high rotation speed of the thin optical disk.…”

Design of a feedforward control system considering dead time for optical disc systems

“…[1], [2], [3] NFR miniaturizes the laser beam spot using light with an numerical aperture (NA)≥1 by generating evanescent light. NFR operates at about a quarter or less of the wavelength of light in the gap in the disc and SIL.…”

Robust Adjacent Track Servo System with Linear Positioning Method

“…[1][2][3][4][5] However, it requires a more advanced servo control system than the conventional one. 6) Various servo controllers have been studied for optical disk drives to realize higher performance using higher gain [7][8][9][10][11][12] or a feed-forward controller. [13][14][15][16][17] However, they all require a guide groove system.…”