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. 01, 1993
Filed:
Oct. 07, 1991
Applicant:
Inventors:
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H01J / ;
U.S. Cl.
CPC ...
3133 / ;
Abstract
The present invention improves the stability among the qualities of the electron tube cathodes in which the barium scandate is dispersed and contained in the alkali earth metal oxide layer provided on the surface of the base metal, by making the shape and average particle size of the barium scandate similar to those of the carbonate used to form the alkali earth metal oxide, and it avoids the deterioration of the electron emission property for a long time, by setting the concentration of the barium scandate in the alkali earth metal oxide layer to zero at the position close to the surface of the base metal.