| 摘要 |
PURPOSE:To obtain accurate tracking error information, by providing a delaying means which detects the output given from a photodetector and then delaying one of a pair of arithmetic outputs obtained by giving a desired calculation to the output of the above-mentioned detection by an amount equivalent to the delay time of a sample pulse generating means. CONSTITUTION:A delay circuit 11 of a signal B containing the tracking error information is equal an integration type circuit consisting of a resistance R1 and a capacitor C1. Then the corresponding time constant is set so as to obtain a delay amount equivalent to the delay time of a sample pulse generator. This delay output is supplied to sample holding circuits 7 and 8 to be turned into a signal to be sampled. The output pulses C and D of the sample pulse generator are used via an amplifier 12 to control sample switches Q2 and Q3 of the circuits 7 and 8, respectively. Such constitution ensures the generation of the accurate tracking error information G with no error of sampling timing. |
