Abstract: An optical recording medium having a recording layer which comprises an Sb—Te alloy containing excess amount of Sb over the vicinity of Sb70Te30 eutectic composition and shows reversible phase changes on light beam irradiation between a crystalline state and an amorphous state differing from each other in optical properties, a method of writing and erasing information using the same, and a process of producing the same are described.

Abstract: An optical recording method for recording mark length-modulated information on a recording medium by using a plurality of recording mark lengths.

Abstract: The subject matter of the invention is to provide an optical recording medium with improvements in repeated overwrite characteristics, write power margin, archival stability and the like.

Abstract: An optical recording method for recording mark length-modulated information on a recording medium by using a plurality of recording mark lengths. The optical recording method comprises the steps of: when a time length of one recording mark is denoted nT (T is a reference clock period equal to or less than 25 ns, and n is a natural number equal to or more than 2), (i) dividing the time length of the recording mark nT into &eegr;nT,&agr;1T, &bgr;1T, &agr;2T, &bgr;2T, . . . , &agr;1T, &bgr;1T, . . .

Abstract: For an optical recording medium having a phase change type recording layer on its a substrate and having as read only area and a writable area in a recording area, a data recording method is provided which records data in the writable area. This data recording method comprises a transfer step of transferring program data recorded in the read only area in a practical form to an external computer, and an execution step (step A10) of automatically executing the program data in the external computer to record data in the writable area, which can facilitate manufacturing and reduce the possible of destruction or falsification of ROM data.

Abstract: An optical recording method for recording mark length-modulated information on a recording medium by using a plurality of recording mark lengths.

Abstract: An optical information recording medium having a multilayer structure comprising at least a lower protective layer, a phase-change type optical recording layer, an upper protective layer and a reflective layer, on a substrate, wherein the phase-change type optical recording layer has a composition of Zn&ggr;1In&dgr;1Sb&zgr;1Te&ohgr;1, where 0.01≦&ggr;1≦0.1, 0.03≦&dgr;1≦0.08, 0.5≦&zgr;1≦0.7, 0.25≦&ohgr;1≦0.4, and &ggr;1+&dgr;1+&zgr;1+&ohgr;1=1, whereby overwrite recording is carried out by modulation of light intensity of at least strong and weak two levels, so that a crystalline state is an unrecorded state, and an amorphous state is a recorded state.

Abstract: A multilevel recording method based on a novel principle utilizing a phase change medium. The method comprises the steps of: radiating a recording energy beam against an information recording medium having a recording layer to locally melt the recording layer, the recording layer being adapted to produce a phase change between a crystalline state and an amorphous state upon being radiated with an energy beam; and forming an amorphous mark by cooling during a solidifying process to record information in the medium; wherein the size of the amorphous mark is controlled mainly by a competition between a recrystallization process and an amorphization process during the solidifying process; wherein an intensity of reflected light from a reproducing light beam radiated region is controlled in three or more multiple recording levels according to an optical characteristic difference between a crystalline region and a amorphous region and their areas.

Abstract: An optical information recording medium having a multilayer structure comprising at least a lower protective layer, a phase-change type optical recording layer, an upper protective layer and a reflective layer, on a substrate, wherein the phase-change type optical recording layer has a composition of Gef(SbdTe1−d)1−f, where 0.65≦d≦0.85, and 0.01≦f≦0.20, whereby overwrite recording is carried out by modulation of light intensity of at least strong and weak two levels, so that a crystalline state is an unrecorded state, and an amorphous state is a recorded state.

Abstract: A high-density optical disk comprises a transparent substrate having a guide groove having a depth of 100 to 200 nm, width of 0.2 to 0.4 &mgr;m arranged with a track pitch of 0.7 to 1.0 &mgr;m. A recording layer is made of an organic pigment exhibiting a specific main weight reduction in a thermogravimetric analysis and a specific exothermic peak in a differential thermal analysis.

Abstract: An optical recording medium comprising a transparent substrate and at least a recording layer containing an organic dye, a reflecting metal layer and a protective layer sequentially laminated on the substrate in this order, which has the following characteristics (a) to (c): (a) the substrate has a tracking groove with a track pitch of from 0.7 to 1.0 &mgr;m and the recording layer shows a modulation amplitude of EFM signal of at least 50% when recording is carried out by a laser beam with a wavelength of from 600 to 700 nm, and has a reflectance of from 45 to 65%; (b) in a thermogravimetric analysis of the dye, the inclination of the weight reduction to the temperature in the main weight reduction process is at least 2%/°C.; and (c) in the thermogravimetric analysis of the dye, the total weight reduction in the main weight reduction process is at least 25%.

Abstract: An optical information recording medium having a multilayer structure comprising at least a lower protective layer, a phase-change type optical recording layer, an upper protective layer and a reflective layer, on a substrate, wherein the phase-change type optical recording layer has a composition of Zn.sub..gamma.1 In.sub..delta.1 Sb.sub..zeta.1 Te.sub..omega.1, where 0.01.ltoreq..gamma.1.ltoreq.0.1, 0.03.ltoreq..delta.1.ltoreq.0.08, 0.5.ltoreq..zeta.1.ltoreq.0.7, 0.25.ltoreq..omega.1.ltoreq.0.4, and .gamma.1+.delta.1+.zeta.1+.omega.1=1, whereby overwrite recording is carried out by modulation of light intensity of at least strong and weak two levels, so that a crystalline state is an unrecorded state, and an amorphous state is a recorded state.

Abstract: 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 :0.25.ltoreq.GW/R.sub.0 .ltoreq.0.45 or 0.65.ltoreq.GW/R.sub.0 ; and0.03.ltoreq.a.sub.w /GW.ltoreq.0.08hold for preventing distortion of the groove caused by repeated overwriting operation to improve reliability of the optical disc.

Abstract: An optical information recording medium comprising a substrate provided with periodically wobbling guide grooves with a track pitch of 1.6.+-.0.1 .mu.m, and a lower protective layer, a phase-change type recording layer, an upper protective layer and a reflective layer formed in this sequence on the substrate, for recording, retrieving and erasing amorphous marks in the guide grooves by modulation of light intensity of at least two levels by means of a focused light having a wavelength of 780.+-.30 nm applied from the side of the substrate opposite to the recording layer side so that a crystalline state with a reflectance of from 15 to 25% is an unrecorded state, and an amorphous state with a reflectance of less than 10% is a recorded state, wherein the grooves have a depth of from 25 to 45 nm and a width of from 0.4 to 0.6 .mu.m.

Abstract: 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 :0.25.ltoreq.GW/R.sub.0 .ltoreq.0.45 or 0.65.ltoreq.GW/R.sub.0 ; and0.03.ltoreq.a.sub.w /GW.ltoreq.0.08hold for preventing distortion of the groove caused by repeated overwriting operation to improve reliability of the optical disc.

Abstract: An optical information recording medium comprising a substrate provided with periodically wobbling guide grooves with a track pitch of 1.6.+-.0.1 .mu.m, and a lower protective layer, a phase-change type recording layer, an upper protective layer and a reflective layer formed in this sequence on the substrate, for recording, retrieving and erasing amorphous marks in the guide grooves by modulation of light intensity of at least two levels by means of a focused light having a wavelength of 780.+-.30 nm applied from the side of the substrate opposite to the recording layer side so that a crystalline state with a reflectance of from 15 to 25% is an unrecorded state, and an amorphous state with a reflectance of less than 10% is a recorded state, wherein the recording layer is a thin film of an alloy of My.sub.y (Sb.sub.x Te.sub.1-x).sub.1-y where 0.ltoreq.y<0.3, 0.5<x<0.

Abstract: 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.

Abstract: 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 :0.25.ltoreq.GW/R.sub.0 .ltoreq.0.45or0.65.ltoreq.GW/R.sub.0 ;and0.03.ltoreq.a.sub.w /GW.ltoreq.0.08hold for preventing distortion of the groove caused by repeated overwriting operation to improve reliability of the optical disc.

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.

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 multilayer structure on the disc.