| 摘要 |
PROBLEM TO BE SOLVED: To provide an electrostatic level detector which requires no zero adjustment. SOLUTION: In a level detector, a capacitance-frequency (C/F) converter 11 outputs a frequency signal that is reversely proportional to the capacitance between a housing container 6 and a main electrode 2 and a first counter 12 counts the cycle number of the output signal of the converter 11 during first counting time T1 and holds the count value C1. Then a second counter 13 successively counts the cycle number of the output signal of the converter 11 during every second counting time T2 set to be longer than the first count time T1 byΔT and a comparator 16 compares the second count value C2 with the first count value C1 and, when the count values become C1>=C2, outputs a level detecting signal (a).
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