| 摘要 |
PURPOSE:To improve the reliability of the pull-in operation of a phase-locked loop circuit and synchronization detection for recording, reproduction or erasure based on the output signal of a comparator by providing a recording area detection circuit and a comparison voltage generation circuit. CONSTITUTION:The optical head 12 of an information reproducing device 11 reproduces a bit of recording information on a magneto-optical disk, and inputs a reproducing signal 101 to an amplifier 13, and the signal 101 is amplified, and is generated as a reproducing signal 102, and it is waveform-processed at a waveform processing circuit 14, then, a reproducing signal 103 is outputted. Also, the signal 102 is also sent to the recording area detection circuit 27, and detection whether the reproduction is the one at the time of reproducing a recorded area or the one at the time of reproducing an unrecorded area is performed. And a recording area signal 111 and a plane signal 110 outputted from the circuit 27 are inputted to the comparison voltage generation circuit 16, and the signal 103 is converted to a comparison voltage 104 via an adder means, and is outputted. The comparator 15 compares the signal 103 with the voltage 104, and a binary pulse shaped digital signal 105 is outputted. In such a way, it is possible to improve the reliability of the pull-in operation of the phase-locked loop circuit and the synchronization detection for the recording, the reproduction, etc.
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