| 摘要 |
PURPOSE:To eliminate the turbulence of a control signal by regulating the diameter and arrangement of a light beam for tilt servo and the size of a group area and that of a recording/reproducing area in prescribed manner. CONSTITUTION:Assuming the diameter of the light beam 7 for tilt servo as (a), distance between the light beam 7 for tilt servo and the center of a main beam 6 in the radius direction of a disk as (d), it is desirable that Rou+a<Rgo and a<2d. By employing such constitution, it is possible to eliminate the turbulence of a detection signal by a mirror area 15 and also, influence can be hardly applied only by placing the light beam 7 for tilt servo in the group are 12, or it is overlapped slightly on the mirror area 15 at an outer periphery even when the main beam 5 is located at the recording track 23 at the outermost periphery of the recording/reproducing area 13. |
