| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to set pit tracks and groove tracks at respectively optimum pitches so that the pitch of the former is made narrower than the pitch of the latter and to make the density higher by disposing a mirror region at the boundary between a first recording region having a writable groove tracks of projecting and recessed shapes and a second region having reproduction-only pit tracks. SOLUTION: The optical disk 101 is divided into a RAM region 102 and a ROM region 103. The boundary region 104 consisting of the mirror part is set at the boundary between the RAM region 102 and the ROM region 103, thereby, the boundary between the RAM region 102 and the ROM region 103 can be easily detected and the tracking control and recording reproducing processing in both regions 102 and 103 with good accuracy can be easily executed. As a result, the pitch Tb of the tracks 112 is set at the optimum arbitrary pitch narrower than the track pitch Ta of the groove tracks 111, 110 of the recessed or projecting shape, thereby, the higher density can be attained in both of the ROM region 103 and the RAM region 102. |
