| 摘要 |
PURPOSE:To render a light beam stable by a method wherein a light beam projected from a light source consisting of plural luminous structures is detected by a corresponding photo-detecting region, and when a portion of the light beam is detected by the part other than the corresponding photo-detecting region, a device of this design is structured so that the portion detected is removed as a noise. CONSTITUTION:Detection signals consisting of a reproducing detection signals level mixed with a portion of recording detection signals level as a noise are are generated from a reproducing photo-detecting region 24A, and other detection signals consisting of a recording detection signals level mixed with a portion of a reproducing detection signals level as a noise are produced from a recording photo-detecting region 24B. The detection signals from the reproducing photo-detecting region 24A through the intermediary of a preamplifier 35B are supplied to a bottom level detection circuit 41 for the removal of the recording detection signal as a noise therefrom. The detection signals from the recording photo-detecting region 24B are supplied to a subtraction circuit 60, where a reproducing light component is removed from the detection signals as a reproducing light component has been applied onto the circuit 60 as a noise. |
