| 摘要 |
PURPOSE:To simplify the timing control of a focus OK signal with simple constitution by using a focus servo means which performs the control to pull an objective lens in its focal position in accordance with a focus error signal produced from the output signal of an optical pickup. CONSTITUTION:The output of a switch control circuit 62 is set once at level H at a time point T1 among those time points T1-T2 and keeps the level H despite pulse signals attain to levels H and L. Thus the output of the circuit 62 is finally kept at the level H up to the time point T2. When the output of a timing circuit 58 is set at a level L at the time point T2, the output of the circuit 62 is naturally kept at level H regardless of the output of an NOT circuit 52. In such a way, the focus OK signal at the level H is outputted. Then a focus search mode is switched to a focus servo action mode. In such a way, the stable disk reproduction is executed. |
