Mitsubishi Chemical Corporation

Haruo Kunitomo

Takashi Ohno

Michikazu Horie

Hironobu Mizuno

Masae Kubo

Masaaki Mizuno

Natsuko Nobukuni

Hideyuki Kubo

Ken-Ichi Takada

Masao Komatsu

Kenichi Takada

Ken' Ichi Takada

Ken'Ichi Takada

The present invention relates to an optical recording medium having a protective layer and a phase-change recording layer on a substrate, said protective layer containing a metallic oxysulfide and an optical recording medium having a protective layer and a phase-change recording layer, said protective layer being formed by sputtering using a target comprising a metallic oxysulfide.

Optical recording medium and production method of the same

An optical phase-change disc comprises a substrate having thereon a spiral groove or concentric grooves for guiding a focused light beam, and a layer structure including a recording layer and protective layers sandwiching therebetween the recording layer. The groove has wobble for recording ATIP (absolute time information) or ADIP (address information). The following relationship between the groove width GW, beam diameter R.sub.0 and wobble amplitude a.sub.w :

Optical phase-change disc

Optical phase-change disc having a grooved substrate, with the groove

An optical information recording medium for recording, retrieving and erasing mark length-modulated amorphous marks, which comprises a substrate, and a lower protective layer, a phase-change recording layer, an upper protective layer and a reflective layer having a thickness of from 40 to 300 nm and a volume resistivity of from 20 to 150 n.OMEGA..multidot.m, formed in this sequence on the substrate.

Optical information recording medium

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.

Modulation of laser power in accordance with a linear velocity by pulse

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 multilayer structure on the disc.

Optical recording process and optical recording system

The disclosure describes an optical recording medium for recording, erasing and reading-out information by irradiation a laser beam, comprising:

Growing community of inventors

Okayama, Japan

Haruo Kunitomo