MULTILAYERED OPTICAL RECORDING AND REPRODUCING DEVICE AND METHOD, AND MULTILAYERED OPTICAL RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To solve the problem that a multilayered optical recording medium takes processing time periods for the number of recording layers to adjust off-center of the recording tracks within the specified limit and is often its off-center exceeds the limit resulting in low production yield as the number of recording layers increases.

SOLUTION: The multilayered optical recording medium 9 decreases in advance the number of the recording layers (servo area added layers 36, 37) having asperity sections showing the addresses and radial locations and satisfies the relational expression X≥D when X represents the shorter one of the movable distances of the center of the recording and reproducing beam focused back and forth in its moving direction to satisfy the specified property level and D the largest distance between the recording layers among the recording mediums. Since the number of the servo area added layers of the multilayered optical recording medium is made half the total number of the recording layers or less (in the case of X≥D), the production yield can be improved in the centering process of the recording layers when forming multilayers.

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