| 摘要 |
A predetermined signal pattern whose length is 9 T or more (signal level="1") of a modulation signal S2 modulated by a modulating circuit corresponding to a conventional information signal is varied corresponding to an output signal SC1 of a disc identification code generating circuit. When the signal level of the output signal SC1 is "1", a signal converting circuit varies the signal level at a nearly center position of the particular signal pattern to "0" for 1 T. Thus, a pit whose length is 9 T or more is converted into two pits and one blank and recorded on a compact disc. When a reproducing operation is performed, a nearly center position of a reproduction signal of a pit whose length is 9 T or more is sampled. Corresponding to the sampled result, the disc identification code signal is decoded. Since a binary signal of the reproduction signal is not affected by the conversion, a conventional information signal is correctly reproduced.
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