Granted Patent
Utility
US 4,957,211 · App. 07/378,057
Vacuum-indicating closure
Inventors:
Len Ekkert, Charles A. Webster, Paul R. Hansen
Patented Case
View Patent ↗
Granted: Sep 18, 1990
Filed: Jul 11, 1989
Inventors
Len Ekkert
Charles A. Webster
Paul R. Hansen
Assignee (at issue)
American National Can Company
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.