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AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsNoboru Yamada, Kenichi Nishiuchi, Shigeaki Furukawa, Nobuo Akahira, Eiji Ohno, Kenichi Nagata, Rie Kojima
Estimating the term…
In an optical information recording medium such that a recording layer undergoing an optically detectable phase change by absorbing a laser beam is formed on a transparent substrate having geometrically concavo-convex groove tracks concentrically or spirally formed on its surface, the shapes of the groove tracks are variably determined continuously or stepwise depending on the material of the substrate, the structure of the recording layer, and the radial locations of the tracks so that the thermal diffusivity of heat generated in the recording layer becomes larger in an inner part than in an outer part whereby the differences of recording characteristics between in an inner part and in an outer part are suppressed, and the effective recording area is enlarged. There is also disclosed an optical information recording medium having outer zone in which the groove width decreases monotonically or stepwise as recording radius decreases and inner zone in which the land width increases monotonically or stepwise as recording radius increases.
An optical information recording medium having a transparent substrate having concentric or spiral grooves with geometrically concave-convex structure, thereby forming concentric or spiral tracks each consisting of land and groove portions of said geometrically concave-convex structure, a dielectric layer, a rewritable recording film made of a material which undergoes a reversible phase change responding to a heat of a laser beam, and a reflecting layer for reflecting the laser beam back into said recording film, said reflecting layer being formed as a thermal diffusion layer for diffusing a heat transmitted from said recording film wherein the thermal diffusivity of each track located in a radially inner area of said recording medium is greater than that of each track located in a radially outer area.
An optical information recording medium having a transparent substrate having concentric or spiral grooves with geometrically concave-convex structure, thereby forming concentric or spiral tracks each consisting of land and groove portions of said geometrically concave-convex structure, a dielectric layer, a rewritable recording film made of a material which undergoes a reversible phase change responding to a heat generated by a laser beam, and a thermal diffusion layer for diffusing a heat transmitted from said recording film through said dielectric layer, wherein the radial width of information recording portion of each track, on which information is recorded, is large in a radially inner area of said recording medium as compared with that in a radially outer area when the recording portion is groove portions, and is small in a radially inner area of said recording medium as compared with that in a radially outer area when the recording portion is land portions.
An optical information recording medium having a transparent substrate having concentric or spiral grooves with geometrically concave-convex structure, thereby forming concentric or spiral tracks each consisting of land and groove portions of said geometrically concave-convex structure, a dielectric layer, a rewritable recording film made of a material which undergoes a reversible phase change responding to a heat of a laser beam, and a reflecting layer for reflecting the laser beam back into said recording film, said reflecting layer being formed as a thermal diffusion layer for diffusing a heat transmitted from said recording film wherein the area in which said tracks are formed is divided into at least two concentric ring zones and information is recorded on groove portions of said tracks located in one zone of said at least two concentric ring zones and on land portions of said tracks located in another zone of said at least two concentric ring zones.
Dependencies are inferred from the claim text.