| 摘要 |
PURPOSE:To improve S/N ratio and to stabilize a servo, by superimposing a DC component formed on the basis of a tracking error signal on the tracking error signal, and increasing the entire level of the tracking error signal. CONSTITUTION:In an optical pickup detecting a tracking error signal at each pit of a disc information surface from the difference between optical sensor outputs divided into two depending on the optical spot scanning direction, the positive/negative part only of the tracking error signal Te is detected at half- wave linear detection circuits 21 and 22 respectively and inputted to limiter amplifiers 31, 32, and summed at an adder AD1 via clamp circuits 41, 42. The tracking error signal Te is superimposed on the summing output at an adder AD2, and after the entire level is increased, the resulting signal is inputted to a bridge detection circuit 50, allowing to make the level of the tracking servo signal Ts equal to the peak value of the tracking error signal Te. Thus, unstable servo due to the DC vomponent is eliminated. |
