| 摘要 |
PURPOSE:To reduce an information recording error rate due to the increase of sector position detecting capacity and to reduce collectively hardware by forming a sector mark based upon wobbling pits on the head of a sector address information preformat part. CONSTITUTION:Grooves 1 are optical guide grooves for optional three tracks on an optical disk and pits 2, 3 are wobbling pits due to optical slight pits. On the other hand, a pit 4 is an optical slight pit constituting the original part of sector address information and is also a PLL synchronizing VFO (sink) part. Since the pits are slightly eccentricated in the wobbling pit parts, a tracking error signal corresponding to the eccentricity is outputted. Namely, reflected light beams from the optical disk are made to incident upon a tracking signal photodetecting diode 6, a tracking error is obtained from the output of a differential amplifier 7 as a tracking error signal 9 and an information signal is obtained from the output of an additional amplifier 8 as a tracking sum signal and can be easily distinguished from a normal signal. |
