| 摘要 |
The mark-length recording system whereby information is recorded by changing the lengths of a recorded portion and an unrecorded or erased portion has a problem that, when new information is recorded in an already recorded region, the newly recorded information may deteriorate in reliability because the length and width of the newly recorded mark are different from those of the previously recorded mark and a part may exist that is not completely erased at the time of overwriting. The invention widens a setting freedom of the recording power and controls the length and width of the recorded mark by making the effective recording pulse length (the length from a rise of a first pulse to a fall of a last pulse) satisfy a relation: (effective recording pulse length)<(recording code length, i.e., the length of data to be recorded)-2T(twice the reference clock cycle).
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