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. 21, 1981
Filed:
May. 03, 1978
Applicant:
Inventor:
George Miram, Atherton, CA (US);
Assignee:
Varian Associates, Inc., Palo Alto, CA (US);
Primary Examiner:
Int. Cl.
CPC ...
H01J / ; H01J / ;
U.S. Cl.
CPC ...
313293 ; 313107 ; 313348 ; 313444 ; 313448 ;
Abstract
In an electron gun having a control grid in contact with the face of the cathode, unwanted thermionic emission from the cathode can be effectively suppressed by applying a thin (1 micron) coating of boron nitride to the surface of the control grid. The boron nitride has low thermionic emission itself and, in addition, has an unusual ability to shed or eliminate any deposits of emissive material such as barium or its oxides which come in contact with the boron nitride layer. For optimum performance and longest lifetime, the boron nitride layer is applied over a pyrolytic graphite layer which may be the conductive grid itself.