| 摘要 |
PURPOSE:To obtain a correct focus even if the reflection factor or the like is changed when a recording medium is replaced, by adjusting the offset of a focus loop on a basis of the amplitude detection value of a reproduced signal so that the amplitude is maximum. CONSTITUTION:A recording signal on a disc 9 is reproduced while keeping the offset at the recording time as it is, and the amplitude value obtained by an amplitude detector 4 is binarized by an A/D converter 5 and is taken into a control microcomputer 6 and is stored in an internal memory 1. Next, the instruction which increases the offset by a certain value is outputted to a D/A converter from the microcomputer 6 to apply an offset voltage to a servo circuit 8, and the signal in this state is reproduced, and the amplitude is stored in an internal memory II of the microcomputer 6. The operation which increases or reduces the applied offset is repeated in accordance with the result from comparison between contents of memories I and II to adjust the offset. |
