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. 14, 1997
Filed:
Aug. 08, 1996
George Barbehenn, Vancouver, WA (US);
John Eaton, Vancouver, WA (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
In thermal inkjet printing, an energy source supplies voltage pulses to a set of resistors in a printhead. The resistors are not necessarily equal-valued. The subset of energized resistors changes from pulse to pulse as a function of the printable data. As the subsets vary, resulting in a varying load on the energy source, this causes undesirable variations in the energy supplied to individual resistors, even when a regulated source is used, because of residual impedances in the source and wiring. The invention compensates for such energy variations, using information about which subset of resistors is to be energized during a pulse. By determining the electrical load presented by the subset, and by referring to a predetermined relation between the load value and the voltage drop in the residual impedances, the invention maintains nominally constant energy in individual pulsed resistors by an appropriate adjustment of the pulse width.