| 摘要 |
<P>PROBLEM TO BE SOLVED: To detect the liquid level in a linear manner with an inexpensive constitution. Ž<P>SOLUTION: A liquid level detection device 100 comprises a liquid level switch 102 which determines whether or not the local liquid level Lp in a reservoir tank is equal to or higher than the predetermined reference liquid level Ls, and outputs the ON-OFF signal consisting of the OFF-signal when the local liquid level Lp is equal to or higher than the reference liquid level Ls, and the ON-signal when the local liquid level is below the reference liquid level Ls, a duty ratio computation unit 108 which receives the ON/OFF signal from the liquid level switch 102 and computes the duty ratio D of the ON-signal, a storage unit 112 for storing the relative relationship between the duty ratio D and the actual liquid level Lr in advance, and a liquid level estimation unit 110 for estimating the actual liquid level Lr from the duty ratio D computed by the duty ratio computation unit 108 by referring the relative relationship stored in the storage unit 112. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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