| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a liquid level sensor capable of reducing cost of a detection circuit by reducing a chip area by summarizing analog circuit parts, and improving liquid level measurement accuracy. Ž<P>SOLUTION: This liquid level sensor includes: a first pulse generation means 38 for generating alternately a first pulse having a pulse width in proportion to a capacitance of a first detection electrode 22 always put in liquid to be measured, and a third pulse having a pulse width in proportion to a capacitance of a third detection electrode 24 always put out of the liquid to be measured; and a second pulse generation means 41 for generating a second pulse having a pulse width in proportion to a capacitance of a second detection electrode 23 for measuring the level of the liquid to be measured. In the sensor, operation is repeated, for charging as long as a time from fall of the third pulse until fall of the second pulse, and for discharging as long as a time from fall of the second pulse until fall of the first pulse. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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