CAPACITIVE NUMBER WHEEL ENCODER FOR UTILITY METERS

摘要

A number wheel assembly (10) for a counter mechanism has a plurality of number wheels (13-18), each number wheel (13-18) having a sleeve (48) around its circumference with a plurality of positions representing successive increments in a count, a substrate (26-31) opposite one surface of the number wheel (13-18), the substrate (26-31) carrying an electrode (42) that is spaced from the number wheel (13-18) to form an air gap for a variable capacitor, and wherein the number wheel (13-18) carries at least one dielectric element (46) that is rotated with the number wheel (13-18) to vary the capacitance of the variable capacitor according to the position of the number wheel (13-18). Circuitry for detecting the capacitance and the position of the number wheels (13-18) is provided on a circuit board (39) that is electrically connected to the number wheels (13-18).