Patent ID: 6036296
Filing Date: 2000-03-14
Classification: B41J,G01F

Abstract:
A fluid level detection system for determining a volume of a fluid in a container (V.sub.FLUID), comprising:a container in which a fluid is disposed;a reference chamber, the reference chamber having a volume (V.sub.R);a pressure chamber in which the container is disposed, the pressure chamber having a volume (V.sub.P);an air source;an air management system including at least one orifice, the air management system being configured to selectively couple the air source to the reference chamber to pressurize the reference chamber to at least a first reference chamber pressure (P.sub.R1), to selectively couple the air source to the pressure chamber to pressurize the pressure chamber to at least a first pressure chamber pressure (P.sub.P1), to selectively couple the reference chamber to the orifice to discharge the reference chamber, and to selectively couple the pressure chamber to the orifice to discharge the pressure chamber;a pressure sensor configured to sense pressure;a time measurement device configured to determine an elapsed time (.DELTA.t.sub.R) for a pressure in the reference chamber to drop from pressure (P.sub.R1) to a lower pressure (P.sub.R2), as sensed by the pressure sensor, and to determine an elapsed time (.DELTA.t.sub.P) for a pressure in the pressure chamber to drop from pressure (P.sub.P1) to a lower pressure (P.sub.P2), as sensed by the pressure sensor; anda computing device configured to determine a volume of air in the pressure chamber (V.sub.AIR) based upon the reference chamber volume (V.sub.R), the elapsed time (.DELTA.t.sub.R), the elapsed time (.DELTA.t.sub.P), and the pressures (P.sub.R1), (P.sub.R2), (P.sub.P1), and (P.sub.P2), and further configured to determine the volume of fluid in the container (V.sub.FLUID) based upon the pressure chamber volume (V.sub.P) and the volume of air in the pressure chamber (V.sub.AIR).