High-Speed Recording up to 15,000 rpm Using Thin Optical Disks

Abstract

We propose a high-speed optical disk system using thin flexible optical disks (HS-FOD) recording up to 15,000 rpm. The thin optical disk system is composed of three technical elements: media employing a thin and flexible substrate 0.1 mm thick, a mechanical stabilizer, and a high-speed tracking servo employing a feed-forward control with zero phase error tracking (ZPET-FF control). The HS-FOD system has an optical head with numerical aperture (NA) of 0.85 and is compatible with the optical system of a Blu-ray disc or a broadcast-use optical disk. We have successfully performed disk rotation stably and have performed precisely a focus servo and a tracking servo at 15,000 rpm. We also achieved writing and reading data at 15,000 rpm and recording 252 Mbps of random pattern data and could get small values of jitter below the tolerance. These results are enough to record professional high-definition television (HDTV) video signals in formats such as HD-D5 for broadcast-use.

Servo techniques for optical disk drives —high‐speed and precise optical beam‐positioning control—

“…The residual tracking error of the ZPET-FF control was less than that of FB control over entire disk rotation speeds. As compare with the tracking error of the FB control was beyond 9 nm of the tolerance at 10,800 rpm, the tracking error of the ZPET-FF control was suppressed below the tolerance at 10,800 rpm [9].…”

“…We could achieve and perform the tracking servo at 15,000 rpm. This system could record 252 Mbps of high data transfer rate data of high-definition television signal for broadcast-use [9].…”

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.…”

Recording characteristics of high-density thin optical disk using near-field optical recording

“…Thin optical disks that have a thickness of about 0.1 mm can rotate at high speed, [24][25][26] and have demonstrated high-data transfer rate recording. [27][28][29] Although the NFR optical disk has a fourfold higher data capacity per recording layer than that of Blu-ray disk, the 20 nm gap servo control between the SIL optical head and the disk surface meant that there were difficulties with obtaining a high disk rotational speed for high-data transfer rate recording when the conventional method was used. [30][31][32][33][34] We have proposed a precise gap servo system of reducing harmonics of an axial run-out disturbance-feed-forward control (RHD-FFC) system for the NFR drive.…”