| 摘要 |
PURPOSE:To detect a specified liquid level without receiving the effect of a measuring capacitor, by connecting one of capacitors, which are connected in series, to the measuring capacitor in parallel, and connecting the parallel capacitor to a reference point. CONSTITUTION:A measuring capacitor C0 is connected in parallel with a capacitor C2, which is connected with a capacitor C1 in series, between a measuring electrode an a reference grounding point. The capacitor C2 is also connected to the reference grounding point. The resonant output of a frequency corresponding to a total capacitance C based on the expression I is outputted from an oscillator circuit 4. The detected output of a specified liquid level is generated from an output circuit 7 through a filter circuit 5 and a rectifier circuit 6. The order of the magnitudes of the capacities is C1>C2>C0. When the liquid level is not contacted with the measuring electrode, the capacity C becomes equal to the capacity C2. When they are contacted, the capacity C0 becomes infinite, and the capacity C becomes equal to the capacity C1. By the jump of the capacity C, the reaching to the specified liquid level can be detected excellently without the effect of the measuring capacitor. |
