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:
Jun. 30, 1987
Filed:
Mar. 20, 1986
Applicant:
Inventor:
Niels J Nielsen, Corvallis, OR (US);
Assignee:
Hewlett-Packard Company, Palo Alto, CA (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G01D / ;
U.S. Cl.
CPC ...
3461 / ; 137854 ; 137526 ;
Abstract
A preloaded check valve disposed in a valve body between an ink reservoir and a printhead has a valve opening pressure or 'cracking' pressure at least sufficient to overcome the hydrostatic pressure due to gravity of ink in the reservoir. This prevents depriming or leakage of ink at the orifices of the orifice plate forming part of the ink ejecting mechanism. Ejection of ink during printing creates a pressure differential across the valve sufficient to cause it to open and replenish the ink supply at the ink ejecting mechanism.