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:
Dec. 12, 1995
Filed:
May. 03, 1994
Applicant:
Inventors:
James N Lester, Merrimac, MA (US);
William J Roche, Merrimac, MA (US);
Assignee:
Osram Sylvania Inc., Danvers, MA (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H05B / ;
U.S. Cl.
CPC ...
3152 / ; 315224 ; 315225 ; 315307 ;
Abstract
A ballast includes an inverter for providing an AC voltage to a discharge lamp. As the lamp approaches end-of-life a DC voltage component develops across the lamp. The ballast includes circuitry for monitoring the condition of each of the cathodes by measuring this DC voltage component. After a predetermined increase in this DC voltage component, the inverter is disabled in order to prevent excessive heating of the cathodes.