SELF-MONITOR DEVICE OF LIGHT SIGNAL TRANSMISSION DEVICE

摘要

PURPOSE:To monitor the light signal transmission device up to light output without deteriorating the light output and without increasing the device scale. CONSTITUTION:An input signal 11 is converted to multiple signals 13 by a multiple circuit 12. These signals are converted to a light signal by a laser driving circuit 1 and a laser diode 15. The output light signal of the laser diode 15 is converted to an electric signal by a photo diode 16 built together with the laser diode 15 in a laser module 23. The output of the laser diode 15 is stabilized by an automatic output regulating circuit 17 in accordance with this signal. The output of the photo diode 16 is amplified by an amplifier circuit 18 and is separated to a signal 20 of the same type as the type of the input signal 11 in a multiplex sepn. circuit 19. The input signal 11 and the signal 20 are compared in a comparator circuit 21 and the fault of the light signal transmission device is detected.