| 摘要 |
PURPOSE:To execute stable tracking control, by detecting a tracking signal from a synchronizing bit for tracking, which has been recorded in advance, and recording an information signal between the synchronizing bits, executing the tracking. CONSTITUTION:A tracking signal is obtained from the sum RF of signals generated from 4-divided photodetectors 14, 15, 16 and 17, and a difference signal DF, by which the correction is executed so that an optical spot comes to the center of a track. On the other hand, in order to record an information bit by an information modulation pulse 28' between a synchronizing bit 27 and a synchronizing bit 27, an information write timing pulse 2 is generated by use of an edge pulse 32' generated by one end of the synchronizing bit 27, and timing time T1-T2 for recording the information modulation pulse 28' is generated. In this way, it becomes possible to write an information bit between the synchronizing bits while detecting a tracking signal from the synchronizing bit. |
