OPTICAL DISK, OPTICAL DISK DEVICE, AND DIGITAL WORK PUBLICATION

摘要

PROBLEM TO BE SOLVED: To deal with information of an HD DVD and a two layer DVD by one disk.

SOLUTION: (1) A light transmission layer, first and second recording layers accessed by a first laser beam and a third recording layer accessed by a second laser beam are disposed sequentially in a laser beam incident direction. (2) The distance of the light transmission layer from a beam incident surface to the first recording layer is 550 μm or more. (3) A gap between the first and the third recording layers is 72 μm or shorter. (4) A gap between the second and the third recording layers is 15 μm or more. (5) A gap between the first and the second recording layers is nearly 31 to 40 μm. (6) Reflectance of the first laser beam from the first and the second recording layers is 18% or more and the ratio of the reflectance is nearly 1.15 or below. (7) The surface recording density of the third recording layer is 3 times as high as the surface recording density of the first and the second recording layers or higher.

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