Importance

Loading Importance Indicators...

Abstract

Disclosed herein is a capacitance sensor which comprises a pulse generating circuit; a plurality of variable delay circuits, each including as a component thereof a variable capacitance transducer and adapted to delay a pulse from the pulse generating circuit by a time lag corresponding to a capacitance value of the transducer and then output the thus-delayed pulse; and a phase discriminating circuit adapted to discriminate a phase difference of the pulses output respectively from the plurality of variable delay circuits and then output measured information. This capacitance sensor can be used to measure various parameters. The capacitance sensor is particularly effective as a liquid level detection sensor for liquid containing bottles used to dispense intravenous substances in drop-wise fashion. It is not required for the above sensor to reset its detectable threshold level for every material or item to be measured, because unnecessary variables such as temperature changes and dielectric constant changes of the material or item are cancelled out. The present capacitance sensor can be reduced in size, weight and fabrication cost. It is also capable of detecting very small changes in capacitance.

Loading the Abstract Image...

First Claim