Granted Patent
Utility
US 5,139,293 · App. 07/789,564
Armature assembly for electromagnetic door holder
Inventors:
Michael Zimmerman, Mark A. New
Patented Case
View Patent ↗
Granted: Aug 18, 1992
Filed: Nov 8, 1991
Inventors
Michael Zimmerman
Mark A. New
Assignee (at issue)
Von Duprin 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.