Granted Patent
Utility
US 4,957,316 · App. 07/340,499
Armature for electromagnetic lock
Inventor:
George Frolov
Patented Case
View Patent ↗
Granted: Sep 18, 1990
Filed: Apr 19, 1989
Inventor
George Frolov
Assignee (at issue)
Harrow Products LLC
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.