| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent pirated media from being produced by peeling by recording data needed for reproduction to a reflecting film. <P>SOLUTION: A sub-code symbol on an optical disk molded by stamping is (0x47). Pits P4 and P5 are formed corresponding to a 14-bit pattern obtained by imposing EFM modulation on its 8 bits. The land L1 between the pits P4 and P5 is irradiated with a laser beam. The reflection factor of the L1 decreases and after recording, the two pits are combined into one pit P6 when reproduced. Then (0x07) is obtained by imposing EFM demodulation on 14 bits after additional recording. As to a channel Q, '1' is obtained when the symbol is (0x47) and '0' is obtained when (0x07). Assuming that the subcode after the additional recording is correct, an uneven pattern on a substrate is not correct and a pirated medium can be manufactured even by using the substrate. <P>COPYRIGHT: (C)2003,JPO |
