METHOD AND APPARATUS FOR DETECTING LIQUID LEVELS IN LIQUID-STORAGE CONTAINERS

摘要

A method and apparatus(10) for sensing different levels of liquids in their respective containers (BC1-BC4) in a liquid-consuming and/or producing instrument system. According to a preferred embodiment, an elongated liquid-sensing probe (P) having axially spaced electrodes (E1-E3) adapted to sense liquid a multiple levels is arranged in each container of liquid. A controller (i.e. a suitably programmed microprocessor) operates to selectively poll different pairs of electrodes (E1-E3) carried by the probe (P) to determine if the polled electrode pairs (E1-E3) are immersed in the contained liquid. Preferably, the polling circuit comprises an electronically- controlled resistor that serves to normalize the level-sensing output signal for liquids of different bulk resistivity.