| 摘要 |
PURPOSE:To make it possible to continuously detect the liquid in a tank from a filled state to an empty state, by converting the change of a liquid level to the change in the distance from a detection window to a reflective plate and detecting the liquid level from the output of a light receiving element. CONSTITUTION:A float 10 moving corresponding to the change in a liquid level to be detected is provided in a liquid storage tank 1 having a light previous detection window 5 mounted to the side wall thereof in a movable manner. A reflective plate 5 is provided so that the distance thereof from the detection window 5 changes with the movement of the float 10 and a light receiving element 11 and a plurality of light emitting elements 12, 13 are provided to the outside of the tank 1 so as to be directed to the reflective plate 15 through the detection window 5. A plurality of the light emitting elements 12, 13 are successively lighted one at a time and, from the relative values of the output of the light receiving element 11 at each lighting time, the position of the liquid level to be detected is detected by a signal processing part 14. By this method, the liquid in the tank 1 can be continuously detected from a filled state to an empty state.
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