| 摘要 |
PROBLEM TO BE SOLVED: To enable tracking and reproduction even it is a reproducing device by using a phase difference detecting method for a reproduction only optical information recording medium such as DVD-ROM. SOLUTION: In reproducing a phase transition type optical information recording medium having a recording layer in which a spiral groove is formed on a transparent substrate, by making the medium a focusing offset so that the amplitude of a push-pull signal before/after recording and the amplitude of a phase difference signal after recording become 70%-95% of the maximum values, respectively, tracking of the phase transition type optical information recording medium by a phase difference detecting method and reproduction of even a reproduction only reproducing device by the phase difference detecting method, while having a small error, are performed. |
