Granted Patent
Utility
US 4,283,653 · App. 06/076,356
High emissivity filament for energy conserving incandescent lamps with infrared radiation returning envelopes
Inventor:
Jack Brett
Patented Case
View Patent ↗
Granted: Aug 11, 1981
Filed: Sep 17, 1979
Inventor
Jack Brett
Assignee (at issue)
Duro-Test Corporation
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.