Patent ID: 7206271

Claim:
An optical storage medium in which information is recorded by using a multi-pulse waveform of a light source driving power, the multi-pulse waveform including a front-end portion, a multi-pulse portion and a tail-end portion, the front-end portion having a first pulse width t 1 with a high-power write level Pw and starting from a middle-power erase level Pe, the multi-pulse portion including a sequence of write pulses each having a second pulse width t 2 with the write level Pw and a third pulse width t 3 with a low-power base level Pb, the multi-pulse portion having a given duty ratio z=t 2 /(t 2 +t 3 ), the tail-end portion having a fourth pulse width t 4 with the base level Pb and ending at the erase level Pe, and when a linear velocity of rotation of the medium is set substantially in a speed range higher than 5.6 m/s and up to 28 m/s, the first pulse width t 1 of the front-end portion ranging from 0.1T to 1T and the fourth pulse width t 4 of the tail-end portion ranging from 0.2T to 1.3T where T is a period of a write clock, the optical storage medium comprising: a substrate; and at least one recording layer of a phase-change material formed on the substrate, wherein the multi-pulse waveform of the driving power is applied to a laser light source to control emission of a laser light beam to said at least one recording layer, and an amorphous phase of the phase-change material is formed by the emission of the laser light beam so that the information is recorded in the medium and the recorded information can be reproduced from the medium.