Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
200 words
An optical information-recording medium including a substrate, and a lower protective layer, a recording layer, an upper protective layer and a reflective layer, formed on said substrate, said recording layer exhibiting different optical properties dependent on different thermal histories of a rise and a fall in temperature caused by irradiation of a laser beam on said substrate, wherein said optical information-recording medium has a layer structure constructed such that reflectivity of said optical information-recording medium and a phase of light reflected therefrom vary with said change in said optical properties of said recording layer, with absorptivity of light of said recording layer being larger when said recording layer is in a crystalline state than when said recording layer is in an amorphous state, and at the same time, reflectivity exhibited when said recording layer is in said crystalline state being 10 % or higher; and wherein said reflective layer has a thickness set such that a value of reflectivity of said reflective layer exhibited in the form of a single layer is 90% or more of a value of reflectivity of a bulk form of a substance of said reflective layer, or to a value of 40 nm or larger.
Claim 2
Dependent Claim
17 words
The optical information-recording medium according to claim 1, wherein the substrate is formed of a polycarbonate resin.
Claim 3
Dependent Claim
54 words
The optical information-recording medium according to Claim 1 or 2, wherein the lower and the upper protective layers are formed of a single substance selected from nitrides, for example, Si₃N₄ and AlN, which are transparent, oxides, for example, SiO, SiO₂ and Ta₂O₅, and chalcogenides, for example, ZnS, ZnSe, and MnS, or a mixture thereof.
Claim 4
Dependent Claim
61 words
The medium according to claim 1, 2 or 3, wherein the recording layer is formed of a substance which has its optical properties changed depending on different thermal histories of a rise and a fall of temperature caused by irradiation of a laser beam thereto at different energy levels, e.g. a compound containing a chalcogen-series atom, for example, Se and Te.
Claim 5
Independent Claim
64 words
The medium according to any one of claims 1 to 4, wherein the reflective layer is formed of a single substance selected from metals, for example, Al, Au, Ti, Cr, Mo, W and Ta, or a mixture of such a substance and an additive, or an alloy of such a substance, or semiconductors, for example, Si and Ge, which are high in refractive index.
Claim 6
Independent Claim
84 words
The medium according to any one of claims 1 to 5, wherein the substrate is formed of a polycarbonate resin; the lower protective layer is formed of ZnS-20at%SiO₂ or Ta₂O₅ with a thickness of 5-300 nm; the recording layer is formed of Ge₂Sb₂Te₅ or Ge₁Sb₄Te₇ with thickness of 15-40 nm; the upper protective layer is formed ZnS-20at%SiO₂ or Ta₂O₅ with a thickness of 15-30 nm; and the reflective layer is formed of Al or Au with a thickness of not less than 40 nm.
Claim 7
Independent Claim
25 words
The medium according to any one of claims 1 to 6, wherein the reflective layer is covered with a layer of an ultraviolet ray-cured resin.