Granted Patent
Utility
US 6,440,191 · App. 09/594,542
Vacuum cleaner filter assembly
Inventors:
Robert C. Berfield, Li H. Liu
Patented Case
View Patent ↗
Granted: Aug 27, 2002
Filed: Jun 14, 2000
Inventors
Robert C. Berfield
Li H. Liu
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.