Granted Patent
Utility
US 5,920,955 · App. 08/802,333
Self-evacuating vacuum cleaner
Inventor:
Robert C. Berfield
Patented Case
View Patent ↗
Granted: Jul 13, 1999
Filed: Feb 11, 1997
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.