Granted Patent
Utility
US 4,688,350 · App. 06/892,142
Collapsible revolving door
Inventors:
Marwan E. Hattem, Calvin R. Rushford
Patented Case
View Patent ↗
Granted: Aug 25, 1987
Filed: Jul 29, 1986
Inventors
Marwan E. Hattem
Calvin R. Rushford
Assignee (at issue)
Tubelite Division of Indall, 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.