| 摘要 |
PURPOSE:To provide the optical signal input interruption detection circuit whose operation is stable against a characteristic fluctuation due to a temperature characteristic or the like. CONSTITUTION:This detection circuit is provided with a photoelectric converter 71 converting a received optical signal into an electric signal, an amplifier 72 amplifying an output signal of the photoelectric converter 71, a peak detector 73 detecting a peak of an output signal of the amplifier 72, a comparator 74 receiving the output signal of the peak detector 73 at its one input, an amplifier 27a receiving a threshold level signal, and a 2nd peak detector 73a detecting a peak of an output signal of the amplifier 72a. And an output of the 2nd peak detector 73a is connected to the other input of the comparator 74. |
