| 摘要 |
<p>PURPOSE:To stably control the titled device by varying the gain of an amplifier for a control loop according to increase or decrease of an average direct current voltage of the addition of detected and rectified crosstalk signals of both side recording tracks adjacent to the recording track concerned. CONSTITUTION:Pilot signals having their respective frequency differences fH and 3fH from right and left tracks adjacent to a scanning track are inputted to a terminal 2 and sent via an LPF 3 to a balanced modulator circuit 4 where multiplied by reference signal inputted from a terminal 5 and then inputted to detection rectifier circuits 15 and 16 through their respective tuning amplifiers 6 and 7 for tuning fH and 3fH respectively. An average direct current voltage E as the result of adding direct current voltage outputs from the circuits 15 and 16 via an equivalent value of their respective resistors RA and RB is inputted to a variable amplifier 17. On the other hand, the outputs of the circuits 8 and 9 are compared by a comparator circuit 10 for level comparison which output as a track error signal is then inputted to the amplifier 17 via an analog inversion circuit 11 and switch 12. The gain of the amplifier 17 is varied in accordance with the fluctuation of the mean direct current voltage E, and a constant tracking error signal is hence outputted from a terminal 18.</p> |
