| 摘要 |
PURPOSE:To cancel a phase difference between main and subgaps, by arranging secondary higher subgaps at positions set at equal distances from the main gap on both sides thereof to add up signals obtained from the subgaps. CONSTITUTION:Subgaps 2 are arranged at an equal distance on both sides of a main gap 1 along the radius of a disc. A recording/reproducing circuit is connected at both ends of a coil produced by connecting windings 4a and 4b of the subgears 2 in series, reproduction signals from subtracks 13a and 13b are added up with a coil to make a reference signal and a phase error of a recording medium is measured on the basis of this signal. Thus, a signal can be obtained with the phase the same as a signal of the main gap by adding reproduction signals obtained from the subgaps. A reference signal is generated following the signal, thereby removing adverse effect due to a positional deviation between the main and subgaps.
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