| 摘要 |
PURPOSE:To stop quickly the movement of a pickup when a track jump is over and to apply the tracking servo by producing a signal having a level approximately between plus and minus pole voltage peak level signals of a tracking error signal and adding this signal to the tracking error signal after inversion of polarity. CONSTITUTION:The plus and minus polarity peak detecting circuits 25 and 26 detect the plus and minus voltage peak levels of a tracking error signal T respectively and produce plus and minus voltage peak level signals V+T and V-T. These signals are supplied to a mixer/adder circuit 27 via buffer amplifiers IC2 and IC3 and resistances R6 and R7. In this case, a differential amplifier IC1 and a negative feedback resistance R8 produce the voltage signals having the value between both voltage levels and add these signals to the signal T after inversion of polarity. Then a tracking error signal (T+DELTAT) having the compensated offset voltage. A switching signal L is stopped after the track jump is over, and a switch S is turned off. At the same time, a tracking servo circuit 20 performs immediately and assuredly the tracking servo to the desired pit train since the plus and minus voltage control regions of the signal (T+DELTAT) are equal to each other. |
