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. 28, 1988
Filed:
Jul. 24, 1981
Wolfgang Witz, Easton, PA (US);
Fortunato J Micale, Bethlehem, PA (US);
John P Leuenberger, Bethlehem, PA (US);
Koh-I-Noor Rapidograph, Inc., Bloomsbury, NJ (US);
Abstract
Improvements in stylographic technical writing pens, particularly through a venting channel design which provides for a pressure balancing, or equalization, between an ultimate ink reservoir pressure and the total pressure at the writing tip; as writing depletes ink within the reservoir. Particularly, a venting channel, extending from the reservoir to ambient air, has the size of its cross-sectional shape vary as a function of the distance from its communication with the reservoir, with the variation calculated to offset gravitational forces attendant to a moving ink meniscus inside the vent channel. The balancing of total pressures also provides a constant ink flow through the writing tip when writing since the total pressure at the tip is maintained constant by the vent channel configuration. The present invention is characterized by the novel approach, of beginning with the insight that a varying static pressure, from a varying level of ink to a vent channel, must exactly offset by the capillary forces at the meniscus of that ink level in the vent channel, and then creating a total vent structure that can follow that relationship.