| 摘要 |
PURPOSE:To increase the detecting sections of the tracking error signals TE and to reduce the influence of the identification signal to the signal TE, by increasing the total section length of the pit parts of an identification signal part of an optical disk in comparison with the total section length of other parts than the pit part. CONSTITUTION:The identification signals used by an optical disk are produced by the grooves 1 having optical depths excluding lambda/4 and pits 3 having optical depths excluding l/4. The total section length of the pit parts of the identification signal part is increased compared with the total section length of other parts than the pit part. Then, a beam is transmitted through the identification signal for detection of a tracking error signal TE. In case a tracking error X is detected before the beam enters the identification signal part, the optical depths are set at '0' at the parts other than pits 3. Then, the signal TE is equal to '0' and these signals TE emerge only at the pit parts 3. Furthermore, the TE shift DELTAX is reduced after the beam passes through the identification signal part and therefore the beam never gets out of a subject track. Thus the stable tracking characteristics are secured. |
