Granted Patent
Utility
US 6,743,281 · App. 10/213,615
Air filtration indicator
Inventor:
David W. Miller
Patented Case
View Patent ↗
Granted: Jun 1, 2004
Filed: Aug 7, 2002
Inventor
David W. Miller
Assignee (at issue)
Delta International Machinery Corp.
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.