| 摘要 |
PURPOSE:To prevent a mistake in counting so as to count accurately the number of traversed tracks by inputting the output signal holding the preceding frequency to a counter when a tracking signal is omitted or an unnecessary signal component is mixed with a tracking signal and holding the moving speed of a recording and reproducing head constantly. CONSTITUTION:During the holding operation of a sample holding circuit 23, a voltage controlling oscillator 24 outputs a signal holding the frequency at the holding operation starting time to a counter by means of a voltage held by the sample holding circuit 23 and a signal processing circuit 2 performs frequency holding operations. During the period of the frequency holding operations, a driving current controlling circuit 4 cuts the driving current driving a recording and reproducing head and maintains the moving speed of the head constantly. since the frequency of tracking signals holds a fixed value when the moving speed of the recording and reproducing head is maintained constantly, mistakes in counting can be prevented by maintaining the moving speed of the head and frequencies inputted to the counter 3 constantly.
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