| 摘要 |
PURPOSE:To ensure the stable jump of a light beam to another track on a disk with high reliability when a retrieving action is carried out in the recording, reproducing and erasing modes, by forming a continuous groove of the prescribed width in a single or plural areas and providing the pits for tracking control alternately at both sides of the track center line with prescribed spaces in other areas. CONSTITUTION:The pits 2a, 2b, 3a and 3b are formed alternately at the right and left sides with prescribed distances to the center lines 1a and 1b of tracks and in a cycle t1(sec). At the same time, the continuous grooves 4a and 4b having the prescribed length t2(sec) are formed on the center lines of tracks with the length larger than the width of the jump pulse used for shift of the light beams over the tracks. Then, a jump pulse is produced at the continuous proove parts 4 in a retrieving mode of an optical head. In a normal recording/ reproducing mode, the light beam has no shift from the track center line of the light beam for tracking control owing to those pits set with mutual shifts in the right and left sides from the center lines 1a and 1b. Thus, the scan is carried out on the track center line. |
