| 摘要 |
PURPOSE:To execute an exact tracking even if a head width is narrow against a track pit, by deriving a tracking error signal, based on an output from a main track, and executing tracking control based on a non-linearity characteristic in acocrdance with it. CONSTITUTION:The difference between an RF output 17 reproduced from a main track and the maximum value 21 of the RF output which is set in advance is used as a tracking error signal, and a reference voltage VR2 is set a little lower than the maixmum value 21. When a head is moved from a position 51 to 53 against a shift quantity X of the head center, a slight shift is left and the RF output is also lowered a little, but a stable tracking can be executed. A direction for moving the head is obtained through inversion/non-inversion maplifiers 42, 43 and an exclusive logical gate 44, the gain of an adder 46 is determined from its non-linearity characteristic, and by executing the tracking by an error signal 48, and head can execute exactly positioning to the track irrespective of the position of a dead body.
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