| 摘要 |
PROBLEM TO BE SOLVED: To provide a liquid level detection sensor of simple structure capable of detecting not only a liquid level but also that the liquid level is in the process of an increase or decrease. SOLUTION: A light guiding down-path 101 and a light guiding up-path 102, each having a solid rod-like shape and a refraction index different from that of a measured liquid, form rectilinear light guiding paths 101a and 102a, respectively, on their one end sides positioned in the air and curved light guiding paths 101b and 102b, respectively, on the other end sides positioned on the measured liquid side, and are disposed with end faces of the curved paths standing opposite to each other. A light emitting element 103 is provided on the one end side of the down-path to launch a sensing beam thereinto while a light receiving element 105 is provided on the one end side of the up-path to detect the beam propagated through its curved path. A float guide 108, provided between the end faces of the opposite disposed curved paths, is equipped with a float 109 vertically movable according to liquid level variations and capable of interfering with an optical path from the end face of the curved path of the down-path to the end face of the curved path of the up-path to completely block the optical path.
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