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. 07, 1992
Filed:
Feb. 07, 1991
Robertus A Keijser, Eindhoven, NL;
Petrus A Weerdestein, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
The invention relates to a switching arrangement for operating a high-pressure sodium lamp which radiates white light in stable operating conditions. The switching arrangement is provided with switching means for switching current through the lamp by means of a drive signal generated in a drive circuit, which signal is based on a comparison between a reference value C and drive signal V+.beta.I, in which V is the lamp voltage, I is the lamp current, and .beta. is a constant. According to the invention, C may be adjusted in steps in dependence on the lamp voltage. Thus the duration over which the lamp radiates white light can be prolonged and brought into better accordance with the electrical lamp life.