Granted Patent
Utility
US 6,481,049 · App. 09/589,492
Self-evacuating vacuum cleaner
Inventor:
Robert C. Berfield
Patented Case
View Patent ↗
Granted: Nov 19, 2002
Filed: Jun 7, 2000
Inventor
Robert C. Berfield
Assignee (at issue)
SHOP VAC 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.