| 摘要 |
PURPOSE:To remove the effect of the change in the intensity of an optical signal by making a comparison reference voltage follow up the change in a photoelectric conversion signal level to be compared which accompanies the change in the optical signal. CONSTITUTION:When first to third optical signals (a)-(c) are approximate sine waves, for instance, an output signal Va of a first inversive amplifier 5 becomes a sine wave as shown in Fig. (a), while output signals Va of second and third inversive amplifiers 6 and 10 become since waves shifted in a phase of 180 degrees from the one of Fig. (a). The output signals of the amplifiers 5 and 6 are put in an adder 7 and added up thereby to be an output of Va/2, which turns to be a comparison reference voltage of a comparator 11, while the output signal from the amplifier 10 turns to be a comparison voltage. The output of the adder 7 turns to be a non-inverted input signal of the voltage comparator 11, while the output of the amplifier 10 turns to be an inverted input signal. By making the comparison reference voltage of the voltage comparator 11 follow up a change in an input signal to be compared, in this way, an optical comparator having a stable accuracy in detection irrespective of a change in the intensity of an optical signal can be realized.
|
