| 摘要 |
<P>PROBLEM TO BE SOLVED: To enable handling of information on a two-layer HD DVD and a one layer DVD by one sheet of disk. <P>SOLUTION: The fundamentals are as follows; (1) this is an optical disk of three layer structures in which a light transmission layer, a first recording layer accessed by a first laser beam, a second recording layer and a third recording layer which are accessed by a second laser beam are arranged in order in the incident direction of laser beam, (2) a distance of the light transmission layer from an optical plane of incidence to the first recording layer is 550 μm at a minimum, (3) a space between first recording layer and the third recording layer is 72 μm at a maximum, (4) a space between the second recording layer and the third recording layer is 19 μm at a minimum, (5) a space between the first recording layer and the second recording layer is approximately 28-38 μm, (6) a reflectivity from the first recording layer by a first laser beam is 45% or more, and (7) area recording densities of the second recording layer and the third recording layer are more than three times of the area recording density of the first recording layer. <P>COPYRIGHT: (C)2007,JPO&INPIT |
