Granted Patent
Utility
US 4,252,641 · App. 06/064,241
Pressurized screen
Inventor:
Andrew Martin
Patented Case
View Patent ↗
Granted: Feb 24, 1981
Filed: Aug 6, 1979
Inventor
Andrew Martin
Assignee (at issue)
Black Clawson Company, 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.