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. 10, 1990
Filed:
Sep. 26, 1988
Applicant:
Inventors:
Brian S Ahern, Boxboro, MA (US);
David W Weyburne, Maynard, MA (US);
Attorneys:
Primary Examiner:
Int. Cl.
CPC ...
H01J / ;
U.S. Cl.
CPC ...
313336 ; 3133 / ; 313353 ;
Abstract
A high emissivity cold cathode has alternating cylindrical tube layers, deposited by vapor deposition, of a refractory metal such as niobium and a refractory insulating material such as alumina. The metal layers have a thickness of less than or about 1,000 angstroms such that the electric field strength at the exposed end is sufficient, in combination with a low work function metal to emit electrons when a voltage of about 2,000 volts is applied.