| 摘要 |
PURPOSE:To enable switching to a light source on a redundant side without instantaneous interruption when an active side light source is abnormal by providing an optical switch between the redundant side light source and a photocoupler and providing a control circuit to separately control the ON/OFF of two light source driving circuits for driving the optical switch and the light sources. CONSTITUTION:This device is equipped with a first light source N 2 on the active side, second light source E 4 on the redundant side, and an optical coupler 6 to couple and transmit the optical signals of the first and second light sources N 2 and E 4. In this case, an optical switch 5 is provided between the second light source E 4 and the optical coupler 6 so as to control ON/OFF. Further, a control circuit 7 is provided to control ON/OFF control timing for this optical switch 5, second light source E 4 and first light source N 2 while shifting it for fixed time and to execute control for switching the first and second light sources N 2 and E 4 without instantaneous interruption when the first light source N 2 is abnormal. Thus, when there is abnormality in the active side light source, it can be switched to the redundant side light source without considering the state of a line at a terminal station. |
