| 摘要 |
PURPOSE:To make a discriminating circuit unnecessary in accordance with each photodetector, and to simplify the constitution, by constituting a synthesizing circuit by connecting the photodetector which corresponds individually to each optical fiber is connected by at least series or parallel connecting state, and discriminating a level of an output from said circuit by a level discriminting circuit. CONSTITUTION:A level discriminating circuit 13 compares voltage V1 with reference voltage V2, and when the voltage V1 exceeds the reference voltage V2 (V1>=V2), a signal of a high level is generated to an output line 17 and a light emitting diode 18 is made to emit light. The level discriminating circuit 13 generates a signal of a low level to the output line 17 when the voltage V1 is less than the reference voltage V2, and puts out the light emitting diode 18. Another output line 19 of the level discriminating circuit 13 outputs an inverted signal of the output line 19, by which a state for light-emitting and putting out a light emitting diode 20 is opposite to a state of the light emitting diode 18. Light from the light emitting diodes 18, 20 is led out by optical fibers 21, 22, respectively. |
