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:
Aug. 03, 1999
Filed:
May. 30, 1997
Peter N Wood, Rolling Hills Estates, CA (US);
International Rectifier Corporation, El Segundo, CA (US);
Abstract
A lamp ballast circuit drives at least one gas discharge illumination device and includes first and second MOS-gated power semiconductor devices connected in a half-bridge configuration and coupled across a d-c supply with a common terminal located at the node between the devices for supplying an output signal to the illumination device. A self-oscillating driver circuit includes respective outputs for driving the power semiconductor devices and has at least one operating voltage supply terminal. When the illumination device fails or is removed, a protection circuit, electrically coupled to the illumination device, removes the operating voltage supplied to the supply terminal. The protection circuit includes a transformer/inductor coupled to the illumination device or a switch that is responsive to the voltage across the illumination device. Additionally, a soft-starting circuit can be provided for gradually increasing the voltage across the illumination device prior to igniting the illumination device.