| 摘要 |
PURPOSE:To ensure accurate tracking control, by minimizing the degree of DC offset that is based on the inclination of a disk produced in a tracking error signal. CONSTITUTION:The reflected light beams of a disk are detected by photodetecting parts 7A and 7B. The detecting signals SA and SB have the same level when the disk has no inclination and then have the levels deflected from the normal level if the disk has some inclination. For each of these detecting signals, the level is detected at the part minimum in level fluctuation degree. Then a tracking error signal is obtained based on the difference between the levels of both detecting signals. The fluctuation component is small for each of extracted both levels. As a result, the offset generated in the tracking error signal owing to the inclination of the disk is extremely reduced. |
