| 摘要 |
PURPOSE:To detect a malfunction state, by converting a potential of a LED forward voltage, comparing emission and extinction signals of a LED by ringing or emitting light for indication when those signals are different. CONSTITUTION:When an emission and extinction signal Vs is input to an input terminal 17, a transistor 12 is rendered to be conductive when the signal Vs is on. Then, a base current flows into a transistor 11 by serial resistance 14 and 15 and the transistor 11 is rendered to be conductive. Then, the LED 10 emits light which is then lead to an optical fiber 16. When a potential Va is applied to one input terminal (-) of a comparator 20 and a reference potential Vb is applied to the other input terminal (+), there is provided an off signal at a conversion voltage Vc when the potential Va is higher than the reference potential Vb and there is provided an on signal at a conversion voltage Vc when the potential Va is lower than the reference potential Vb. Then, when the conversion voltage Vc and the emission and extinction signal Vs are input to an exclusive OR element 30, it outputs no signal when both signals conform and outputs pulse signal when they do not conform. A detector 31 is operated by driving a transistor 32 with a buzzer and an LED for indication. |
