| 摘要 |
PURPOSE:To narrow a track width, and to rise a recording density by recording low frequency signals for three kinds of tracking of each different low frequency by superposing them on a recording signal, and applying a closed loop servo for positioning a head, based on this signal. CONSTITUTION:A head output is amplified by a reproducing amplifier 14 and divided into two, and one and the other are inputted to the processing circuit of an information signal, and an LPF 15, respectively. By the LPF 15, only a low frequency tracking signal is fetched, divided into three, and inputted to filters 1, 2 and 3 for fetching each frequency component of xHz of 3n tracks, yHz of 3n+1 tracks, and zHz of 3n+2 tracks, respectively. As for the output of respective filters 1-3, a voltage is measured by an rms voltmeter 17, and its output is inputted to an input signal switching and comparing circuit 18. The circuit 18 compares two kinds of signals except the input signal of the maximum level, and when two kinds of signals are in the same level, an R/W head is in an on-track state, and when the signal level of them is larger, a head positioning signal is sent to a head positioning device so that a head position is moved to the track of a smaller level.
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