Beverage dispenser with capacitive level sensor and display and method

摘要

A beverage dispenser (10) with a beverage quantity indicating display (30) controlled by a microprocessor (66) in response to variations in capacitance of a plurality of sensing capacitors (72) detected by a capacitive sensing circuit (70) including one of a general purpose input/output integrated capacitive touch-key sensor, and a general purpose, integrated, input/output port expander with an integrated capacitive touch-key for reduced power consumption, sensitivity and reliability. A reference capacitor (C8) is located above the maximum height (52) of the beverage (74) to keep it spaced from the beverage (74) in air is used to compensate for changes in capacitance of the sensing capacitors (72) due to variations in temperature. All the capacitors (72, C8) are formed from pairs of planer conductive plates (54, 56) respectively mounted to opposed parallel interior surfaces (58, 60) of a sensing tube (36) attached to a down tube (34).