| 摘要 |
PURPOSE:To increase the reliability of signal transmission, by connecting a photocoupler to each of photocouplers in series connection with opposite polarity to switch the signal transmitting direction. CONSTITUTION:A light emitting element 21 is connected to each of light emitting elements 11 in series connection with opposite polarity. A photodetecting element 12 is located to each of the elements 11 and a photodetecting element 22 is located to each of the elements 21 to consitute photocoupler groups A, B. Current switching circuits 32, 33 are connected to the photocoupler groups A, B to consitute a current direction switching circuit 30 with a switching circuit 31. Thus, if the light emitting elements are defective in off-state, the signal transmission can be made by the switching of signal transmitting direction, and if the light emitting elements are defective in on-state, the affect on other stations can be avoided and the reliability of the signal transmisssion can be increased. |
