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:
Oct. 28, 1997
Filed:
Dec. 18, 1995
Joseph F Stephany, Williamson, NY (US);
Gary A Kneezel, Webster, NY (US);
John H Slowik, Penfield, NY (US);
Xerox Corporation, Stamford, CT (US);
Abstract
A capacitor is created in an ink tank supplying ink to an ink jet printhead by placing parallel capacitive plates on sides of the tank with the ink therebetween acting as the capacitor dielectric. An electrical AC potential is applied across the capacitor. Changes in current flow through the plates are detected in a phase sensitive bridge circuit and digital signals are generated and sent to a processor for conversion into low ink level signals. The output signal is also used to identify a particular type of ink by either comparing points on a characteristic curve of the ink volume verses capacitance or, in a second embodiment, by periodically sweeping an applied oscillator voltage over a selected frequency range and comparing measured electrical resonance parameters for the ink tank capacitor with stored information about resonance parameters for different types of ink.