| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a read-only optical recording medium which has high compatibility with a BD and wherein data can be reproduced by a DVD device or a CD device. <P>SOLUTION: The optical recording medium is provided with a first light transmission layer 4, a second light transmission layer 5, a first information carrier surface 2 for performing reproduction by using a blue light beam, and a second information carrier surface 3 for performing reproduction by using a red light beam. Stable reproduction is made possible by the DVD device and compatibility with the BD is made high by specifying the reflectance R<SB>1R</SB>of the first information carrier surface 2 to be R<SB>1R</SB>≤1-(0.5/R<SB>2R</SB>)<SP>1/2</SP>and specifying the reflectance of the first information carrier surface 2 to the blue light to be ≥3%, when the first light transmission layer 4 has 0.08 to 0.12 mm thickness, the second light transmission layer 5 has 0.43 to 0.57 mm thickness and the first and the second information carrier surfaces 2 and 3 have reflectance R<SB>1R</SB>and R<SB>2R</SB>, respectively, to red color light. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
