| 摘要 |
PURPOSE: An optical disc is provided whereby positioning conditions for the border area between rewritable area and read-only area are defined so that mixing data from both areas does not occur, and the rewritable area and the read-only area are positioned substantially adjacent, or via a land having a predetermined width, so that the efficiency of using the optical disc does not deteriorate. CONSTITUTION: An optical disc is disclosed to have rewritable area(2), read-only area(3) and rewritable area(4) near the transition line(26). The transition line(26) is an imaginary line defining the transition between land(11) and groove(12). And a rewritable track always begin with a groove and always end with a groove. The pitch(Pa) between land(11) and the adjacent groove(12), i.e., the distance between the center line of land(11) and the center line of groove(12), is 0.74 micro meter. This means that the pitch between lands(11), and between grooves(12), is twice the track pitch or 1.48 micro meter. The surface level of the land is the same as the level of the read-only area side of the boundary line. As a result, the boundary line between the rewritable area and the read-only area will never contact the groove. And the transition from the end track land(11) and the beginning of the read-only area(3) following thereafter also occurs at this transition line(26). The transition between the rewritable area and the read-only area thus always occurs at transition line(26). So the mixing data from both areas does not occur.
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