| 摘要 |
PURPOSE:To improve S/N, to detect a level, and to improve reliability, by providing both a light emitting part and a light receiving part at the bottom surface of a prism, utilizing the reflection and refraction of light, and detecting liquid. CONSTITUTION:Both a light emitting part 12 and a light receiving part 13 are contacted with a bottom surface 10a of a transparent prism 10 and provided in a head 11. The light from the light emitting part 12 reaches one slant surface 10b of the prism 10. When silicone oil is present at the outside of the slant surface 10b, the light reaching the slant surface 10b is refracted at the slant surface 10b and outputted into the silicone oil. Therefore the light is not detected by the light receiving part 13. When air is present at the outside of the prism 10, the light is reflected by the slant surface 10b and a slant surface 10c as shown by a dotted line. The light is guided to the light receiving part 13 and detected. Therefore, the light receiving part 13 is linked to a signal generating device and liquid is detected. By using a pluraliry of the devices, a level can be checked. The sensor is hard to be affected by disturbance light, and reliability is improved. |
