| 摘要 |
PURPOSE:To shift continuously a positioner and to decrease the positioning time by providing a circuit which multiplies a weight signal having 90 deg. phase difference of a weight signal circuit by a position signal of 90 deg. phase difference of the positioner and obtains the phase difference between both signals. CONSTITUTION:A tracking control circuit 14 obtains a tracking error signal from an optical head 13 to control a tracking mechanism and at the same time obtains a deviation signal from neutral position within the head 13 to supply it to a voltage comparator 16. The comparator 16 sends shift signals of positive and negative shift signals of a positioner or a stop signal to a weight signal generating circuit 17. The circuit 17 varies or stops the output voltage in accordance with the output signal of the comparator 16 if it receives no stop signal for variation of weight signal from a voltage comparator 21. Multiplying circuits 18 and 19 give multiplication to sine wave signals having 90 deg. phase difference between the circuit 17 and a position sensor 12. Then the difference of phase is obtained by a subtractor 20, and a positioner 11 is continuously shifted with the output of the subtractor 20, thereby decreasing the positioning time. |
