| 摘要 |
PURPOSE:To detect sector and retrace positions with high accuracy by providing ion a sector mark part a first sector mark SM1 indicating that it is the leading sector of the track and a second sector mark SM2 indicating the leading position of the remaining sector. CONSTITUTION:An optical disk 1 has a spiral guide track which is divided by sector ID parts ID1-IDn into an (n) number of sectors S1-Sn. The track is divided into sectors S1-Sn consisting of a sector ID part 2, a data field part 3 and gaps 4, 5 for absorbing fluctuations in the number of revolutions of the disk. The sector ID part 2 is made up of sector marks SM1, SM2 and an address field part AF. Recording is made only at the leading sector S1 of the sector mark SM1 while the sector mark SM2 is recorded in the remaining sectors S2-Sn. I such a manner, after termination of data recording/reproduction into the sectors, the optical head may hold the track of the ultimate processing sector. In such a manner, the leading one of the track and that of the sector may be sensed accurately to improve address detection reliability. |
