Granted Patent
Utility
US 4,557,121 · App. 06/524,907
Electric fail-secure/fail-open lock mechanism
Inventor:
Newton W. Charlton
Patented Case
View Patent ↗
Granted: Dec 10, 1985
Filed: Aug 22, 1983
Inventor
Newton W. Charlton
Assignee (at issue)
Security Engineering, 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.