| 摘要 |
<p>PURPOSE:To eliminate the inversion of polarity of a tracking control signal for each track by changing the generating timings of two signals which are not adjacent to each other for the pilot signal to be mixed to the writing order of four different types of pilot signals. CONSTITUTION:An extracted pilot signal is mixed at the 2nd mixing circuit 11 with pilot signals f1-f4 to produce a beat component of a mixed double frequency containing two frequency differences fT1 and fT2 and ¦f3-f1¦ or ¦f4-f2¦. The output signals of wave deecting circuits 20 and 21 are supplied to a comparator 22, and a tracking control signal which varies centering on the reference value and in response to the difference of level is delivered. In this case, the changing amount of the tracking control signal shows the difference of amplitude between differences fT1 and fT2. This shows a tracking shift. Then the tracking control signal undergoes the inversion of polarity through an inverting amplifier 23 and is supplied to a motor control circuit 4. A capstan motor 3 is controlled in response to the control signal to corrects the tracking shift.</p> |
