Modulation of laser power in accordance with a linear velocity b

Details Modulation of laser power in accordance with a linear velocity b Modulation of laser power in accordance with a linear velocity b

1996-04-01

1998-12-08

Nelms, David C.

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

369 54, 369 59, G11B 700, G11B 1110

Patent

active

058480439

ABSTRACT:
An optical recording process for recording data on a recording medium of phase-change type employs laser power modulation scheme for mark-length modulation recording. The process selects one of pulse division schemes for modulating the laser power in accordance with a linear velocity on the disc. The recording laser includes m pulses for nT mark having a power level Pw and a duration of .alpha..sub.i T, with m intervals .beta..sub.i T sandwiched therebetween, wherein on condition that m=n-k and .SIGMA..alpha..sub.i +.SIGMA..beta..sub.i =n-j, .alpha..sub.i or bias power Pb.sub.i is changed in accordance with the linear velocity, Pb.sub.i being a bias power level for modulation, k and j being an integer and a real number, respectively, both selected between 0 and 2. A large range of the linear velocity margin can be obtained for the disc without changing either the composition of the phase-change material or multi layer structure on the disc.

REFERENCES:
patent: 5561656 (1996-10-01), Hurst, Jr.
patent: 5568464 (1996-10-01), Horie
International Symposium on Optical Memory, pp. 33-34, 1995, Bor-Wen Yang, et al., "Readout Scheme by Pulsed Irradiation Center Aperture Detection on Magnetically Induced Super Resolution MO Disks."
The Japan Society of Applied Physics and Related Societies, 29a-B-4, p. 1014, 1982 N. Morishita, et al., "Study of Write Compensation Method in Phase Change Optical Disk".
Japanese Journal of Applied Physics, vol. 30, no. 4, pp. 677-681, April, 1991, Eiji Ohno, et al., "Multipulse Recording Method for Pulse-Width Modulation Recording on an Erasable Phase Change Optical Disk".
Japanese Journal of Applied Physics, vol. 31, no. 2B, pp. 584-589, February, 1992, Hisataka Sugiyama, et al., "Analysis of Leading Edge/Trailing Edge Independent Detection Method in Optical Disk".
Proc. Int. Symp. On Optical Memory, pp. 291-296, 1991, Kenichi Nishiuchi, et al., "Feasibility Study of Ge-Sb-Te Phase-Change Optical Disk Medium for One-Pass Overwrite Digital Audio Recording".

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