Granted Patent
Utility
US 4,475,724 · App. 06/380,189
Wire spring assembly for sofa sleeper mattresses
Inventor:
William L. Hancock
Patented Case
View Patent ↗
Granted: Oct 9, 1984
Filed: May 20, 1982
Inventor
William L. Hancock
Assignee (at issue)
Hoover Universal, 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.