Granted Patent
Utility
US 6,315,821 · App. 09/758,888
Air filtration device including filter change indicator
Inventors:
Lawrence M. Pillion, Michael Ellis Smith
Patented Case
View Patent ↗
Granted: Nov 13, 2001
Filed: Jan 11, 2001
Inventors
Lawrence M. Pillion
Michael Ellis Smith
Assignee (at issue)
Hamilton Beach/Proctor Silex, Inc.
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.