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:
Jan. 20, 2004
Filed:
Aug. 15, 2000
James B. McGinn, Portland, OR (US);
Sander G. den Hartog, Eindhoven, NL;
David S. Jun, Portland, OR (US);
Gerald G. Magera, Portland, OR (US);
Gregory A. Schwind, Portland, OR (US);
FEI Company, Hillsboro, OR (US);
Abstract
A electron emission cathode includes an emitter having an apex from which electrons are emitted. The emitter is attached to a heating filament at a junction and extends from the junction both forward toward the apex and rearward. A reservoir of material that lowers the work function of the emitter is positioned on the rearward extending portion of the emitter. By positioning the reservoir on the rearward extending portion, the reservoir can be positioned sufficiently far from the junction to reduce its temperature and thereby greatly increase the useful life, of the emitter without adversely affected the emission characteristics of the source.