| 摘要 |
PURPOSE: To provide a level gage excellent in sensitivity by mounting a photosensitive element inside a main body in such a way that it receives totally reflected light from the inner peripheral surface of an empty translucent pipe element. CONSTITUTION: A main body 1 made from a nontranslucent material is mounted with its inner peripheral surface 1c fitted over the outer peripheral surface B1 of a translucent pipe element B, and a light-emitting element 2 and a photosensitive element 5 are placed opposite each other near the outer peripheral surface B1 of the pipe element B. With this constitution, of light beams projected from the light-emitting element 2, those (a) which, when the pipe element B is empty, are transmitted through the outer and inner peripheral surfaces B1, B2 of the pipe element B while being refracted, and totally reflected light beams (b) totally reflected by the inner peripheral surface B2 can be received by the photosensitive element 5. When the pipe element B is filled with liquid, the light beams (a) and the totally reflected light beams (b) propagate almost rectilinearly and are not received by the photosensitive element 5, so that with an increase in the difference between the light beams received, an excellent sensitivity can be secured. Desirably, covers 6 made from a nontranslucent, light-absorbing material are removably mounted on each end of the main body 1. |
