Granted Patent
Utility
US 4,233,642 · App. 06/007,359
Safety interlock system
Inventor:
Thomas R. Ellsberg
Patented Case
View Patent ↗
Granted: Nov 11, 1980
Filed: Jan 29, 1979
Inventor
Thomas R. Ellsberg
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.