| 摘要 |
PURPOSE:To prevent occurrence of an error in data reading, by providing a zero crossing detecting circuit which operates during the period of focus searching only in response to search signals outputted from a focus searching circuit. CONSTITUTION:A zero crossing detecting circuit 30 is constituted in such a way that it detects the zero crossing point of a focus error signal FE from a focus error detecting circuit 22 and its operation is optionally switcheable from the outside. Search signals FS which are outputted from a focus searching circuit 34 for searching focus point and indicate the start and completion of searching operations are used as the operation switching signals of the circuit 30. Therefore, the zero crossing detecting circuit 30 can be operated at the time of focus searching only and generation of zero cross signals FZC in a reproducing state can be prevented. Accordingly, influences of the zero cross signals FZC to the reproducing state can be evaded.
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