| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent recorded data from being taken into a computer by disabling the reading in the high-speed reproduction, and to protect the copyright. <P>SOLUTION: The films of transparent dielectric film 11 (Si<SB>3</SB>N<SB>4</SB>, the thickness of equal to 10 nm)/phase change film 12 (Ge<SB>2</SB>Sb<SB>2</SB>Te<SB>5</SB>, 10 nm)/transparent dielectric film 13 (Si<SB>3</SB>N<SB>4</SB>, 130 nm)/metal reflective film 2' (Ag, 60 nm) are deposited on a substrate 1. The film 12 is not deposited on the inner circumferential side, and the metal reflective film 2' is exposed. The film 12 as deposited is in an amorphous state, and is changed from the amorphous state to a crystalline state by an initialization process. The reflectance of the film 12 in the crystalline state is lower than that in the amorphous state. In the reproduction at one-fold velocity, the amorphous phase is generated by the thermal energy of a laser beam to increase the reflectance, and the reproduction can be performed. In the CD-ROM device, the amorphous phase is not generated due to the high-speed rotation, and the reflectance remains low. Therefore, the reproduction cannot be performed. <P>COPYRIGHT: (C)2003,JPO |
