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. 23, 1991
Filed:
Nov. 28, 1989
Bruce Cowger, Corvallis, OR (US);
John H Dion, Corvallis, OR (US);
William E Peters, Corvallis, OR (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
An ink jet pen (10) having a primary ink reservoir (12) connected to a printhead (16) and to a chamber (18) containing a capillary volume element (20). The pressure within the capillary element (20) is greater normal sub-atmospheric pressure within the ink reservoir (12) but is less than atmospheric pressure. In operation within a normal ambient pressure and temperature range, ink from the reservoir (12) does not enter the capillary volume element (20). Outside of the normal range, the increased pressure within the reservoir (12) causes ink to be drawn into the capillary volume element (20). This enables the pressure of the reservoir (12) to remain substantially constant so that ink is not ejected from the orifice plate of the printhead (16). As the pressure or temperature falls again into the normal range, the ink is drawn back into the primary ink reservoir (12) from the capillary volume element (20).