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:
Feb. 15, 1983
Filed:
May. 19, 1980
Peter A Tielemans, Eindhoven, NL;
Cornelis A Jacobs, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
High-pressure sodium vapor discharge lamps having a color temperature of 2250 to 2750 K. and a color rendition index Ra of 60-85 emit light of a strongly reduced Ra already after approximately 2000 hours in operation. As compared with the life of normal, yellow high-pressure sodium vapor discharge lamps, this period is very short. The discharge vessel contains sodium, mercury and a rare gas, the weight ratio Na/Hg being from 1/1 to 1/9 and the sodium pressure during operation of the lamp being from 4.times.10.sup.4 to 10.7.times.10.sup.4 Pa. The rare gas pressure in the discharge vessel at 300 K. is between 1333 and 1333.times.10.sup.2 Pa. By using an emitter which contains oxygen-bound strontium and oxygen-bound tungsten in a molar ratio from 3/1 to 50/1, the initial properties of such white-light-producing lamps are maintained for a long period of time.