| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that it is impossible to record information in an optical disk with a high density, in a conventional optical disk device unless the size of a converging spot diameter or the density of a signal mark is changed. SOLUTION: The starting and trailing ends 22S and 22E of a signal mark 22 are recorded by being shifted to the right of a track, and the starting and trailing ends 23S and 23E of a signal mark 23 are recorded by being shifted to the left of the same. When a converging spot 21 scans the signal marks 22 and 23, a sum signal 18S draws a signal waveform 24. From this signal waveform 24, the starting and trailing ends 22A, 22E, and 23S and 23E of the signal marks 22 and 23 are detected. In addition, when the converging spot 21 scans the signal marks 22 and 23, a difference signal 19S draws a signal waveform 26. From the difference signal 19S, the left/right shifting of each of the signal marks 22 and 23 are detected. Based on the left/right shifting, 4-value (0, R, C and L) signals are obtained. Thus, the high density of information is achieved. |
