| 摘要 |
PROBLEM TO BE SOLVED: To provide a new reproducing method that can realize high density by providing multivalued information to a record mark and has compatibility with reproducing systems of a conventional CD system and DVD system. SOLUTION: A general photodetector 7 having light receiving areas a-d divided to four parts is used to a light recording medium 6 in which a record mark 10 formed by (i×j) kinds of mark varieties by the combination of length varieties i kinds and height varieties j kinds, and the length of the record mark 10 is discriminated based on the whole additional signals Sum of the light receiving area divided into four divisions. Based on a division signal Tpp/(Sum)<x> , where a subtractive signal Tpp of the additional signals of the light receiving areas a, d locating at the-side to an orthogonal direction to a record mark direction and the additional signals of the light receiving area b, c locating at the other side in the light receiving area divided into four divisions is divided by the additional signal Sum to the power of × (where x>1), the height of the record mark is simply discriminated and then the compatibility with the conventional CD system and DVD system for the discriminating method for length. |
