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:
Apr. 28, 1992
Filed:
Sep. 14, 1990
David R Otis, Jr, Somerville, MA (US);
May F Ho, La Mesa, CA (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A thermal technique for reducing print density shifts due to print wait time in thermal ink jet printers. The ink jet firing resistors of the printhead are driven with warming pulses having a pulse width insufficient to cause ink drop firing at the warming pulse frequency. They are driven for an interval that depends on the amount of time that has elapsed since printing by the printhead last occurred, or an interval that depends on the amount of decrease in the printhead temperature since printing stopped. In a particular embodiment of the printhead warming technique, the warming pulses have the same amplitude as the ink drop firing pulses, and a higher frequency.