| 摘要 |
PURPOSE:To eliminate errors in detection owing to sticking of water drops in a detector for liquid levels wherein there is reflection of incident light when a prism is in liq. and there is reflection of the incident light when the prism is out of the liq., by providing a projecting part which does not interfere the conducting passage for light to the prism. CONSTITUTION:A prism 1 consisting of a conductive passage forming part 1b which forms a passage for light and a water drop sticking part 1c is provided in a vessel 7 in order to measure the level of the liq. 8 in the vessel 7. The light from a light emitting element 4 is made incident to the prism 1 via an optical connector 61, an optical fiber 31, and a collimator 21. The incident light is totally reflected in a direction X, and is detected with a photodetector 5 via a collimator 22, an optical fiber 32 and an optical connector 62. When the prism 1 is in the liq., the incident light advances into the liq. without total reflection by a leading end part 1a, and when the prism is out of the liq., the light is totally reflected thereby and is detected with the photodetector 5, whereby the level of the liq. is detected. Since the water drops that may stick on the prism 1 stick only on the part 1c that has no relation with the passage of the light, the erroneous detection owing to the sticking of water drops is prevented. |
