| 摘要 |
PURPOSE:To control a light spot stably during information recording and reproduction, by eliminating the influence of an information pit during the reproduction and the influence of recording power during the recording. CONSTITUTION:During the reproduction, signals are passed through control signal correcting circuits 24, and 35. The time constants of filter circuit in this circuit are much greater than the period of signal variation due to the information pit and much less than a band required for a control circuit, a signal 22 (23) is converted into a signal 51; and the level of reflection from a metallic film is held during the period of said time constants and the influence of the presence/absence state of information bits is removed. For recording, the signals are passed through filter circuits 25 and 26 whose time constants as much less than the frequency band of an information signal and much greater than the band of a control system to follow up the control system sufficiently and the influence of recording pulses is eliminated. |
