Abstract: A phase-change optical recording medium capable of implementing record and readout operations of information data through reversible phase transition between amorphous and crystalline states induced by light beam irradiation in a recording layer included in the recording medium, including at least a transparent substrate and contiguous layers formed on the substrate in order as follows, a lower dielectric protective layer, the recording layer, an upper dielectric protective layer, and a reflective/heat dissipating layer, in which the upper dielectric protective layer essentially consists of a mixture of ZrO2 and SiO2, having a composition of (ZrO2)100−x (SiO2)x, where 0<x<60 (mole %).

Abstract: An optical information recording medium having a substrate, a first dielectric layer provided on the substrate, a recording layer provided on the first dielectric layer, a second dielectric layer provided on the recording layer, a light reflection and heat dissipation layer provided on the light reflection and heat dissipation layer, and a crystallization accelerating layer provided in contact with at least a portion of the recording layer and made of a material including a substance selected from Bi, Bi-containing compounds, Al, Al-containing compounds, In, In-containing compounds, Tl and Tl-containing compounds.

Abstract: An optical information recording medium is provided. This medium at least stores information that indicates a maximum recording linear velocity Vh. The medium comprises a substrate having a concentric circular guide groove. This guide grove has land portions and groves portions. At least a phase change type recording layer is formed on the substrate. The recording layer has such a composition and thickness that a dislocation linear velocity V satisfies the relation V≧Vh×0.85.

Abstract: A phase-change optical information recording medium capable of recording information therein, reproducing recorded information therefrom, rewriting recorded information, and erasing recorded information therefrom, which phase-change optical information recording medium is provided with a recording layer containing therein a phase-change recording material including Ge, Ga, Sb, Te, and one element selected from the group consisting of Mg and Ca, which recording material is capable of performing a reversible phase transition from a noncrystalline phase to a crystalline phase and vice verse with the application of an electromagnetic wave thereto.

Abstract: A sputtering target contains a target material including as constituent elements Ag, In, Te and Sb with the respective atomic percents (atom. %) of &agr;, &bgr;, &ggr; and &dgr; thereof being in the relationship of 0.5≦&agr;<8, 5≦&bgr;≦23, 17≦&ggr;≦38, 32≦&dgr;≦73, &agr;≦&bgr;, and &agr;+&bgr;+&ggr;+&dgr;=100, and a method of producing the above sputtering target is provided. An optical recording medium includes a recording layer containing a phase-change recording material which includes as constituent elements Ag, In, Te and Sb with the respective atomic percents of &agr;, &bgr;, &ggr; and &dgr; thereof being in the relationship of 1≦&agr;<6, 7≦&bgr;≦20, 20≦&ggr;≦35, 35≦&dgr;≦70, and &agr;+&bgr;+&ggr;+&dgr;=100, and is capable of recording and erasing information by utilizing the phase change of the recording material in the recording layer.

Abstract: A sputtering target contains a target material including as constituent elements Ag, In, Te and Sb with the respective atomic percents (atom. %) of &agr;, &bgr;, &ggr; and &dgr; thereof being in the relationship of 0.5≦&agr;<8, 5≦&bgr;≦23, 17≦&ggr;≦38, 32≦&dgr;≦73, &agr;≦&bgr;, and &agr;+&bgr;+&ggr;+&dgr;=100, and a method of producing the above sputtering target is provided. An optical recording medium includes a recording layer containing a phase-change recording material which includes as constituent elements Ag, In, Te and Sb with the respective atomic percents of &agr;, &bgr;, &ggr; and &dgr; thereof being in the relationship of 1≦&agr;<6, 7≦&bgr;≦20, 20≦&ggr;≦35, 35≦&dgr;≦70, and &agr;+&bgr;+&ggr;+&dgr;=100, and is capable of recording and erasing information by utilizing the phase change of the recording material in the recording layer.

Abstract: An optical recording medium including a recording layer which includes a reversible phase-change recording material, the recording layer being capable of writing information therein, reading written information therefrom, and rewriting written information by utilizing the reversible phase change of the phase-change recording material, wherein when a recording mark formed in the recording layer is repeatedly read 5000 times, using a continuous wave laser beam having such an intensity Pr that satisfies the condition of 1.1 ≦R≦2.0, in which R is &dgr;repeat/&dgr;1 as defined in the specification, the optical recording medium satisfies a relationship of d1>dow as defined in the specification. The phase-change recording material, a method producing the optical recording medium, and a method of writing information in the optical recording medium, reading written information therefrom and rewriting written information thereare are proposed.

Abstract: A sputtering target for fabricating a recording layer of a phase-change type optical recording medium contains a compound or mixture including as constituent elements Ag, In, Te and Sb with the respective atomic percent (atom. %) of &agr;, &bgr;, &ggr; and &dgr; thereof being in the relationship of 2≦&agr;≦30, 3≦&bgr;≦30, 10≦&ggr;≦50, 15≦&dgr;≦83 and &agr;+&bgr;+&ggr;+&dgr;=100, and a method of producing the above sputtering target is provided. A phase-change type optical recording medium includes a recording layer containing as constituent elements Ag, In, Te and Sb with the respective atomic percent of &agr;, &bgr;, &ggr; and &dgr; thereof being in the relationship of 0<&agr;≦30, 0<&bgr;≦30, 10≦&ggr;≦50, 10≦&dgr;≦80, and &agr;+&bgr;+&ggr;+&dgr;=100, and is capable of recording and erasing information by utilizing the phase changes of a recording material in the recording layer.

Abstract: An optical information recording medium includes a substrate with guide grooves thereon, a recording layer provided on the substrate, including a recording material of which phase is reversibly changeable from a stable state to a semistable state and vice versa, a heat-resistant dielectric protective layer provided on the recording layer, including a protective material which includes Zn, Si, S and O, and a light reflection and heat dissipation layer provided on the heat-resistant dielectric protective layer.

Abstract: A sputtering target for fabricating a recording layer of a phase-change type optical recording medium contains a compound or mixture including as constituent elemets Ag, In, Te and Sb with the respective atomic percent (atom. %) of .alpha., .beta., .gamma. and .delta. thereof being in the relationship of 2.ltoreq..alpha..ltoreq.30, 3.ltoreq..beta..ltoreq.30, 10.ltoreq..gamma..ltoreq.50, 15.ltoreq..delta..ltoreq.83 and .alpha.+.beta.+.gamma.+.delta.=100, and a method of producing the above sputtering target is provided. A phase-change type optical recording medium includes a recording layer containing as constituent elements Ag, In, Te and Sb with the respective atomic percent of .alpha., .beta., .gamma. and .delta. thereof being in the relationship of 0<.alpha..ltoreq.30, 0<.beta..ltoreq.30, 10.ltoreq..gamma..ltoreq.50, 10.ltoreq..delta..ltoreq.80, and .alpha.+.beta.+.gamma.+.delta.

Abstract: A phase-change optical recording medium has a substrate, and a lower heat-resistant protective layer, a recording layer capable of recording and erasing information by utilizing changes in the phase of a phase-change recording material in the recording layer, an upper heat-resistant protective layer and a light reflecting and heat dissipating layer, which are successively overlaid on the substrate in this order, the recording material including Ag, In, Sb and Te as the main elements, at least one additional element selected from the group (1) consisting of B, C, N, Al, Si and P, and at least one additional element selected from the group (2) consisting of halogen atoms and alkali metal elements.

Abstract: An optical recording medium includes a substrate, a first protection layer formed on the substrate, a recording layer formed on the first protection layer, a second protection layer formed on the recording layer, and a reflection heat radiating layer formed on the second protection layer. The recording layer is of a phase-change type in which the recording layer is changed from an amorphous state to a crystal state by a temperature raising and cooling process by projecting a laser beam onto the recording layer. The recording layer has an interface portion interfaced with one of the first and second protection layers. The interface portion has a thermal conductivity lower than that of a remaining portion of the recording layer.

Abstract: An optical information recording medium capable of recording information, reproducing recorded information, erasing recorded information, and rewriting recorded information, is composed of a substrate, a recording layer formed on the substrate, the recording layer including as the main component a four-component phase-change recording material comprising Ag, In, Te and Sb, and containing a crystalline phase composed of the microcrystallites of AgSbTe.sub.2 at the erasure of recorded information, an upper heat resistant protective layer formed on the recording layer, the upper heat resistant protective layer including a heat resistant material with a thermal conductivity of 1.0 W/cm.deg or more, and an optical reflecting layer formed on the upper heat resistant protective layer. Optical information can be recorded in this recording medium by applying a laser beam to the recording layer through the substrate at a linear velocity of disc rotation of 1.2 to 5.6 m/sec.

Abstract: A sputtering target, for forming a recording layer of an optical recording medium in which information is written and erased through a transition between two phases by utilizing electromagnetic wave energy, consists of a heat-treated and sintered composition represented by the formula:Ag.sub..alpha. In.sub..beta. Te.sub..gamma. Sb.sub..delta.wherein2.ltoreq..alpha..ltoreq.303.ltoreq..beta..ltoreq.3010.ltoreq..gamma..ltoreq.5015.ltoreq..delta..ltoreq.83.alpha.+.beta.+.gamma.+.delta.=100A method of producing the sputtering target, an optical recording medium having a recording layer formed through sputtering by use of the sputtering target, and a method of forming the recording layer are also disclosed.

Abstract: A device for initializing an optical recording medium includes a semiconductor laser diode, and an optical system which projects a laser beam emitted from the semiconductor laser diode onto the optical recording medium. A half-value width of a spot of the laser beam focused on the optical recording medium is equal to 1/2 to 1/6 times a half-value width of a near-field pattern of the semiconductor laser diode in a direction parallel to a junction interface of the semiconductor laser diode, so that the optical recording medium can be evenly initialized by the laser beam.

Abstract: A sputtering target for fabricating a recording layer of a phase-change type optical recording medium contains a compound or mixture including as constituent elements Ag, In, Te and Sb with the respective atomic percent (atom.%) of .alpha., .beta., .gamma.and .delta.thereof being in the relationship of 2.ltoreq..alpha..ltoreq.30, 3.ltoreq..beta..ltoreq.30, 10.ltoreq..gamma..ltoreq.50, 15.ltoreq..delta..ltoreq.83 and .alpha.+.beta.+.gamma.+.delta.=100, and a method of producing the above sputtering target is provided. A phase-change type optical recording medium includes a recording layer containing as constituent elements Ag, In, Te and Sb with the respective atomic percent of .alpha., .beta., .gamma.and .delta.thereof being in the relationship of 0<.alpha..ltoreq.30, 0<.beta..ltoreq.30, 10.ltoreq..gamma..ltoreq.50, 10.ltoreq..delta..ltoreq.80, and .alpha.+.beta.+.gamma.+.delta.

Abstract: When recording data according to the PWM recording system by modulating signals, pulse modulation for pulse modulation for recording for recording a 0 signal or the like having a signal width of nT (T: Clock time) after modulation is a continuous electro-magnetic wave at a power level e, a record signal pulse array for recording a 1 signal or the like having a signal width of nT after modulation comprises a pulse section fp having a time width x and a power level a, a multi-pulse section mp in which a low level pulse at a power level b and a high power pulse at a power level c having a time width T in total alternately appear (n-n') times in all with a duty ratio y, and a pulse section op having a time width z and a power level d, and x, y, z are integers satisfying the conditions of 0.5 T.ltoreq.x.ltoreq.2 T, 0.4.ltoreq.y.ltoreq.0.6 and 0.5 T.ltoreq.z.ltoreq.

Abstract: When recording data according to the PWM recording system by modulating signals, pulse modulation for pulse modulation for recording for recording a 0 signal or the like having a signal width of nT (T: Clock time) after modulation is a continuous electro-magnetic wave at a power level e, a record signal pulse array for recording a 1 signal or the like having a signal width of nT after modulation comprises a pulse section fp having a time width x and a power level a, a multi-pulse section mp in which a low level pulse at a power level b and a high power pulse at a power level c having a time width T in total alternately appear (n-n') times in all with a duty ratio y, and a pulse section op having a time width z and a power level d, and x, y, z are integers satisfying the conditions of 0.5T .ltoreq.x.ltoreq.2T, 0.4.ltoreq.y.ltoreq.0.6 and 0.5T.ltoreq.z.ltoreq.

Abstract: A sputtering target contains a target material including as constituent elements Ag, In, Te and Sb with the respective atomic percents (atom. %) of .alpha., .beta., .gamma. and .delta. thereof being in the relationship of 0.5.ltoreq..alpha.<8, 5.ltoreq..beta..ltoreq.23, 17.ltoreq..gamma..ltoreq.38, 32.ltoreq..delta..ltoreq.73, .alpha..ltoreq..beta., and .alpha.+.beta.+.gamma.+.delta.=100, and a method of producing the above sputtering target is provided. An optical recording medium includes a recording layer containing a phase-change recording material which includes as constituent elements Ag, In, Te and Sb with the respective atomic percents of .alpha., .beta., .gamma. and .delta. thereof being in the relationship of 1.ltoreq..alpha.<6, 7.ltoreq..beta..ltoreq.20, 20.ltoreq..gamma..ltoreq.35, 35.ltoreq..delta..ltoreq.70, and .alpha.+.beta.+.gamma.+.delta.=100, and is capable of recording and erasing information by utilizing the phase change of the recording material in the recording layer.

Abstract: An intensity of light reflected on a phase-changing type of information recording medium is changed since unrecorded and recorded portions of the recording medium have different phase states so that reflectivities of the unrecorded and recorded portions are different from each other. Such an intensity change takes place in a very short time immediately after a recording pulse is irradiated onto the phase-changing type of information recording medium. In a recording and simultaneous verifying method of the phase-changing type of information recording medium, the change in intensity of light reflected on the phase-changing type of information recording medium is detected by using this light reflected simultaneously with a recording pulse irradiated onto the phase-changing type of information recording medium. It is confirmed if the information is correctly recorded by detecting the reflected light. Thus, this information can be recorded to the information recording medium and can be simultaneously verified.