Granted Patent
Utility
US 4,375,735 · App. 06/254,425
Air lock door control apparatus
Inventor:
James Rhoads
Patented Case
View Patent ↗
Granted: Mar 8, 1983
Filed: Apr 15, 1981
Inventor
James Rhoads
Assignee (at issue)
Dorma Door Controls, 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.