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. 08, 2003
Filed:
Aug. 06, 2001
John G. Konopka, Deer Park, IL (US);
Osram Sylvania Inc., Danvers, MA (US);
Abstract
A ballast ( ) for powering a gas discharge lamp includes a lamp-out detection circuit ( ) that quickly responds to a lamp-out condition. Lamp-out detection circuit ( ) receives a portion of the lamp current and provides a detection voltage. The detection voltage remains at a first average level while the lamp is conducting current in a normal manner, but quickly decreases below a second level if the lamp ceases to conduct current. In a preferred embodiment, ballast ( ) includes an inverter ( ) and a resonant circuit ( ) that are normally operated at a high frequency. The detection voltage is coupled to an enable input ( ) of an inverter drive circuit ( ), and the inverter ( ) is either shut off or operated in a low-power mode within less than ten high frequency cycles after occurrence of a lamp-out condition.