| 摘要 |
PURPOSE:To make it possible to detect the presence of transparent liquid accurately and readily based on the change in refractive index of light rays corresponding to the presence or absence of the liquid in a glass tube. CONSTITUTION:A long liquid-level monitoring glass tube 3 is provided in the vertical direction on one-side surface 6 of a liquid tank 5 so that the lower part of the tube is communicated to the lower part of the liquid tank 5. A light projector part 1 of a photoelectric tube is arranged so that light 7 is emitted in the horizontal direction which is deviated from the radiating direction of the tube 3 at a level where the inflow of liquid into the tube 3 is detected. A light receiving part 2 of the photoelectric tube is arranged at the opposite side of the light projector pat 1 for the tube 3. When the light 7 of the projector part 1 is emitted on the tube 3, the light 7b is transmitted through the wall surface of the tube 3 and the gas in the tube 3, when the liquid is less than the level, in an approximately straight line. When the liquid exceeds the level, the light is refracted as the light 7a by the wall surface of the tube 3 and the liquid in the tube 3. Therefore, whether the liquid reaches the specified level or not can be detected with a light receiving pat 2 shown by a solid line or a dotted line. |
