| 摘要 |
PURPOSE:To detect the liquid level stably for a long time with high accuracy by means of a liquid level sensor easy in mounting, by converting the shift of the liquid level to the pressure which requires only a compact structure with few components, not to the rotary motion for which a bulky structure accompanied by mechanical components such as bearings is needed, and optically detecting the pressure. CONSTITUTION:A permanent magnet 106 is made to float in a liquid 116 to be detected within a container 105, which operates in accordance with the up-and-down movement of the liquid level S. A ferromagnetic body 107 which moves in association with the permanent magnet 106a is provided outside the container. An expansible bellows 108a in the precise structure is mounted to the ferromagnetic body 107. A specific gas G is sealed inside the bellows 108a. The shift of the ferromagnetic body 107 is converted to the change of the pressure of the specific gas. The bellows 108a is provided with confronting optical fibers 102a, 102b with an optical path 114 propagating in the gas inside the bellows. The light from a semiconductor laser source 101 having the absorption wavelength of the gas as the oscillating wavelength is passed through the optical fibers. The change of the absorbing amount of light due to the change of the pressure of the inside gas is obtained by a photodetector 103. Thus, the detecting liquid level is calculated. |
