| 摘要 |
PURPOSE:To prevent the malfunction of an entire system by generating an alarm signal if a supply voltage drops abnormally, converting the signal into an optical signal and sending the result to a receiving side so as to allow the optical receiving side to apply signal processing. CONSTITUTION:A Zener voltage of a Zener diode 7 is a reference voltage lower by a prescribed value than a power voltage. So long as a normal power voltage is applied, the output of a voltage comparator 12 is not inverted and a signal generator 13 generates no alarm signal. Since the capacitance of a capacitor 11 is selected to a very larger value in comparison with the capacitance of a capacitor 14, if the power voltage drops, the capacitors 11,14 start discharging to form the state that the power voltage 9 is lower than a reference voltage 10. The state is detected by a voltage comparator 12 and the signal generator 13 raises an alarm signal. Since the alarm signal is an output of level 1, a gate 2b of a logic circuit 2 outputs a level 0, which is fed to a drive circuit 4, the signal is converted into an optical signal by a light emitting element 3 and sent to an optical fiber 5. |
