| 摘要 |
PURPOSE:To perform normal signal recording and reproducing when a guide groove is recessed as well as projected, by switching the polarity of an off-track servo system which traces the guide groove in accordance with the signal from a means which detects the recessed or projected shape of the guide groove. CONSTITUTION:Recessed shape and projected shape detecting levels D' and E' of a guide groove shape detecting circuit 14 are in the high level and the low level respectively when the guide groove is projected, and they are in the low level and the high level respectively when the guide groove is recessed. Recessed shape and projected shape detection signal levels D' and E' are impressed to respective switch control terminals of an analog switch 133. Since the analog switch 33 is turned for the low level, the input of an off-track signal TR is turned on as it is when the guide groove is projected, and the input inverted by an inverter 134 is turned on when the guide groove is recessed, and thus, the polarity is switched between the recessed shape and the projected shape. A track loop on control signal from a higher device is supplied to an analog switch 135 provided following the switch 133, and an off-track servo circuit 13 forms a closed loop to start tracing tracks.
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