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. 07, 1999
Filed:
Oct. 24, 1996
Anand K Upadhyay, Libertyville, IL (US);
Bhadresh Mehta, Hanover Park, IL (US);
John G Konopka, Barrington, IL (US);
Motorola Inc., Schaumburg, IL (US);
Abstract
An electronic ballast (10) for fluorescent lamps includes a rectifier circuit (100), a boost converter (200), and an inverter (500). The boost converter (200) includes a boost control circuit (400) and a shifting circuit (300). The shifting circuit (300) provides filament preheating by maintaining the boost output voltage at a first level for a predetermined delay period following startup of the boost converter, and then increasing the boost voltage to a second level upon completion of the delay period in order to ignite and operate the lamps. In a preferred embodiment, shifting circuit (300) comprises a shunt circuit (320) and a time delay circuit (360), and inverter (400) is a series resonant half-bridge inverter.