| 摘要 |
PURPOSE:To prevent the mixture of an index signal into the input of a tracking signal detecting part by providing an index detecting part for detection of the fall of each index signal group and a gate which delivers a command for output of an external command part with the output timing of the index detecting part and performing the track jumping with said output timing of the index detecting part. CONSTITUTION:An index detecting part 11 detects the fall of an index signal T1 at an area passing time point t1 of an index part and delivers a pulse 9 to transmit a shift instruction through a jump control part 3 via a gate 12. In this case, a tracking signal waveform 10 equivalent to a track is delivered for the output waveform of a tracking signal detecting part 5. The shift executing time point is set at T3 and the area passing time point of a recording part is set at T2 respectively. Then the shift instruction delivered from an external command part 4 is controlled previously in order to satisfy T2>T3. Thus it is possible to avoid the mixture of an index signal into the input of the part 5.
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