To certainly detect drought by solving the following existing problems: when muddy water or the like is used in a circuit detecting the drought, a motor current value is varied by a cause different from the drought, a conductor and an end are made conductive if foreign matter gets stuck therebetween, and a dielectric constant is changed by a water quality change due to opacity of the foreign matter.
From an inner pole 7A exposed in a vessel, one end is connected to a power supply through an inner pole resistor R1, and also the other end is grounded through an outer pole resistor R2. The partial pressure output of each of the inner pole resistor R1 and outer pole resister R2 is connected to a comparator 7B. Even if the outer pole resistor R2 is varied by water quality, the inner pole resistor R1 detects whether or not the drought is caused within the variation range of the outer pole resistor R2. Therefore, erroneous detection is prevented.
| JPH09152367A | 1997-06-10 | |||
| JP2006266177A | 2006-10-05 |
Yoshinori Iwahara
Susumu Yamamoto
Kazuhiro Emura
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