| 摘要 |
PURPOSE:To obtain an accurate tracking error signal when reproducing the information signal by means of the coupled revolving heads that rotate with a phase difference of 180 deg. between each other by utilizing the reproduction output of the secondary revolving head that traces at an location shifted by a half of the tracking interval. CONSTITUTION:Heads Hc and Hd are delayed in rotating phase by 90 deg. to heads Ha and Hb. In case reproducing by the heads Ha and Hb, the condition for that the heads go to on-track is that the 2 kinds of pilot signals to be reproduced by the heads Hc and Hd are of equal levels. In other expression, by comparing the levels of reproduction of these 2 kinds of pilot signals by the heads Hc and Hd, the magnitude of deviation of the heads Ha and Hb from the main track can be detected. Accordingly, if only, additionally, the direction of the tracking error is detected, the result of the above comparison can be used as a tracking error signal.
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