| 摘要 |
PURPOSE:To hold the amplitude of a reproducing signal, etc., constant against the variance of a light source, etc., by controlling the quantity of light of a light emission part according to the specular surface reflection level of a reproducing signal and the difference voltage based on a reference voltage. CONSTITUTION:A light quantity control circuit 8 detects the amplitude level (specular surface reflection level) of a signal reproduced by an optical pickup light reception part 4 and outputs the difference voltage based on the reference voltage to control the quantity of light of the light emission part 5 which controls a driving circuit 7 for the pickup light emission part 5 with the output of the control circuit 8. For the purpose, the quantity of light of the light emis sion part 5 is so controlled that the specular surface reflection level is equal to the reference voltage; and the amplitude level of the reproducing signal is controlled to a control value for a disk which is different in reflection factor and modulation degree. Even if the light source has variation in characteristics, the amplitude of the reproducing signal, etc., is held constant. |
