Granted Patent
Utility
US 5,977,721 · App. 07/728,042
Controlled power-factor-corrected ballast
Inventor:
Ole K. Nilssen
Patented Case
View Patent ↗
Granted: Nov 2, 1999
Filed: Jul 8, 1991
Inventor
Ole K. Nilssen
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.