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:
May. 20, 2003
Filed:
May. 25, 2001
Frank Edward Anderson, Sadieville, KY (US);
Thomas Austin Fields, Winchester, KY (US);
Paul William Graf, Lexington, KY (US);
Yimin Guan, Lexington, KY (US);
George Keith Parish, Winchester, KY (US);
Kent Lee Ubellacker, Georgetown, KY (US);
Lexmark International, Inc., Lexington, KY (US);
Abstract
A thermal ink jet printing apparatus maintains stable printing output as certain characteristics of the apparatus change over its operational lifetime. The apparatus includes an ink jet print head with resistive heating elements for receiving electrical energy pulses having a voltage level and for transferring heat energy pulses having a desired energy level into adjacent ink based on the electrical energy pulses. The print head includes nozzles associated with the resistive heating elements through which droplets of the ink are ejected when the heat energy pulses are transferred into the ink. The apparatus further includes a printer controller in electrical communication with the print head. The printer controller determines a pulse count indicative of a number of electrical energy pulses, applies the electrical energy pulses having a first pulse width to the resistive heating elements when the pulse count is less than a threshold value, and applies the electrical energy pulses having an adjusted pulse width to the resistive heating elements when the pulse count exceeds the threshold value. The difference in the first and the adjusted pulse widths compensates for changes in the electrical resistance of the resistive heating elements over time.