| 摘要 |
PURPOSE:To resolve the difficulty of signal transmission due to surrounding light with much light quantity or any unwanted operation at the time of change in the quantity of surrounding light. CONSTITUTION:Corresponding to an electric signal, a driving circuit 3 drives a light emitting element 1 and emits an optical signal. The light emitted by the light emitting element 1 is light in a non-polarized state but converted to light in a right circularly polarized state by being transmitted through a polarizing filter 2. Since the light in the right circularly polarized state is transmitted at a polarizing filter 5, the light transmitted through the polarizing filter 2 is transmitted through the polarizing filter 5 and made incident to a light receiving element 4. On the other hand, since a polarizing filter 7 can not transmit the light in the right circularly polarized state, the light transmitted through the polarizing filter 2 can not be transmitted through the polarizing filter 7 and can not arrive at the light receiving element 6. |
