| 摘要 |
PURPOSE:To avoid the malfunction of an electronic device although a fault arises to an optical coupling element, by providing a light receiving part that receives the light from a light emitting part while a control signal is supplied, an oscillating circuit, etc. CONSTITUTION:An optical coupling element 5 includes a light emitting part 5a where the light is emitted in accordance with a proces signal S3 and a light receiving part 5b where the light is received from the part 5a wile the signal is supplied to a control signal input terminal 6. An oscillating circuit 7 applies an intermittent signal to the terminal 6 of the element 5. Furthermore circuits 8-11 deliver the signal delivered from the part 5b in the form of an internal process signal S4 after converting it into a signal which is in accordance with the signal S3. For instance such circuits 8-11 are constituted as shown in the diagram to avoid obtaining an output signal S4 during an open fault at the part 5a or 5b as well as during a connection fault at the part 5b. |
