The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 14, 2000
Filed:
Oct. 31, 1996
James P Axtell, Portland, OR (US);
Preston D Seu, Vancouver, WA (US);
Hewlett-Packard Company, Fort Collins, CO (US);
Abstract
A fluid level detection system for determining the volume of fluid in a container, is disclosed. An embodiment includes a fluid container, a reference chamber, a pressure chamber, an air source, an air management system including at least one orifice, a pressure sensor, a time measurement device, and a computing device. The air management system selectively pressurizes the reference chamber or pressure chamber and selectively discharges the reference chamber or pressure chamber via the orifice. The time measurement device determines elapsed time (.DELTA.t.sub.R) for pressure in the reference chamber to drop from pressure (P.sub.R1) to pressure (P.sub.R2) and elapsed time (.DELTA.t.sub.P) for pressure in the pressure chamber to drop from pressure (P.sub.P1) to pressure (P.sub.P2). The computing device determines a volume of air in the pressure chamber based upon the reference chamber volume, elapsed time (.DELTA.t.sub.R), elapsed time (.DELTA.t.sub.P), and pressures (P.sub.R1), (P.sub.R2), (P.sub.P1), and (P.sub.P2), and determines the volume of fluid in the container based upon the pressure chamber volume and the volume of air in the pressure chamber. A printing device incorporating an embodiment of the fluid level detection system is also disclosed, as is a method for determining the volume of fluid in a container based upon the volume of air in a pressure chamber. An apparatus for use in a printing device is disclosed that includes a printing composition container, a printing composition port coupled to the container, a pressure chamber around the container, and an air port coupled to the pressure chamber.