| 摘要 |
PURPOSE:To always ensure the space transmission line of an optical signal, and to prevent the intermission of an optical signal by providing a light reflection section having a shape reflecting an optical signal being radiated from an optical transmission section into free space in the direction of an optical reception section, at a position between the optical transmission section and the optical reception section. CONSTITUTION:An electric signal being a voice signal of a device 11 is converted into an optical signal 20 at an optical transmission section 12, and radiates from a light emitting element 13 into free space. When an obstacle 19 such as a person crosses an optical path in a space transmission path of the optical signal 20, the optical signal 20 made incident in a light receiving element 14 is shut out, part of an optical signal 21 being radiated in a direction of a ceiling 17 in a room from the light emitting element 13 reaches an optical reflection section 18, the optical signal 21 reaching the optical reflection section 18 is a reflected light, and part of the optical signal 22 reaches the rear side of the obstacle 19. As a result, the optical signal 22 is made incident in the element 14 and the signal transmission system is ensured. |
