| 摘要 |
PURPOSE:To simplify circuit constitution and to eliminate the influence of the nonlinearity of a servo signal, by generating the position error signal of a body to be driven on the basis of the counted value of a clock signal counted in response to time predetermined by the peak value of the servo signal obtained from a servo track. CONSTITUTION:The peak value Vp of the servo signal supplied to a comparing circuit 13 is supplied to a voltage correcting circuit 14. The peak value Vp is multiplied by a constant K through an operational amplifier 15 to supply the product to an operational amplifier 17, and the both perform such amplification that Vs=-(KVp-VREF). The output voltage when Vp is lower than a voltage V0 as the upper limit of a straight line part is clamped to a specific value and inputted to a diode function circuit 19. The output voltage Vc of the circuit 19 is constant and the clock frequency of a voltage-controlled oscillator 7 is constant; when the voltage Vp rises above V0, it is inputted to the diode function circuit 19 through a voltage limiter circuit 18 within such a range that E1-K'< Vs<E2+K'. Then, a voltage shown in a figure is generated from the output of the circuit 19 and does not have any relation with the nonlinearity of the servo signal. |
