| 摘要 |
PURPOSE:To detect a liquid level from the filling to the emptying continuously, stepwise by converting the change of the liquid level into the distance from a detecting window to a reflecting plate and detecting the output of an opticalsensor. CONSTITUTION:A float 10 is turned corresponding to the liquid level of a liquid 6 contained within a tank 1 and the distance from the detecting window 5 to a changing part 14 of a reflecting plate 13 is changed. On the other hand, the distance from the detecting window 5 to an unchanging part 15 of the reflecting plate 13 is unchanged. Reflected light to the changing part 14 is made incident on a reflection type optical sensor 11a and the reflected light to the unchanging part 15 is made incident on a reflection type optical sensor 11b. The output signals of the reflection type optical sensors 11a and 11b are processed with a signal processing part 12 and the liquid level can be detected from a relative value between the outputs. For instance, a design is made so that the distance from the sensor 11b to the unchanging part 15 is set at the position to make the output level 100% and the distance from the sensor 11a to the changing part 14 is changed at a part longer than this distance by which the distance from the sensor 11a to the changing part 14 can be detected.
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