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:
Mar. 20, 1990
Filed:
Jun. 11, 1987
Applicant:
Inventors:
Assignee:
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Primary Examiner:
Int. Cl.
CPC ...
H01J / ; H01J / ;
U.S. Cl.
CPC ...
313566 ; 313623 ;
Abstract
A high pressure sodium lamp includes a light permeable ceramic bulb wherein a pair of electrodes are oppositely arranged. One of the electrodes is inserted into one end of a metal tube, the other end of which is pinched. The center line average surface roughness of the inner surface of the metal tube is held below 2 .mu.m for preventing melted sodium-mercury amalgam condensed on the inner surface of the other end of the metal tube from moving along the inner surface of the metal tube by capillary action toward the one end thereof.