| 摘要 |
PURPOSE:To separate a sensor part from a liquid to improve the reliability by providing an oscillator whose resonance circuit includes a capacitor consisting of >=2 electrodes formed on the outside surface of an insulating tube, and changing the electrostatic capacity in accordance with the liquid level in the tube to change the oscillation frequency. CONSTITUTION:A capacitor 2 consisting of electrodes 2a and 2b is connected to an oscillator 3 and is a constituting element of the resonance circuit of the oscillator 3. The frequency of the oscillator 3 is changed in accordance with the electrostatic capacity of the capacitor 2, and for example, the oscillation frequency is lower according as the capacity of the capacitor 2 is smaller. When the liquid level in a tube 1 is high, the electrostatic capacity of the capacitor 2 is increased by the dielectric constant of the liquid because the liquid extents more between electrodes 2a and 2b. Consequently, the oscillation frequency is made lower according as the liquid level in the tube 1 is higher. The output frequency of the oscillator 3 is counted by a frequency counter 4, and the measured result is latched in a latch circuit 5 and is taken out to the external.
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