Granted Patent
Utility
US 4,493,615 · App. 06/557,581
Electro-rheological transducer
Inventor:
James E. Stangroom
Patented Case
View Patent ↗
Granted: Jan 15, 1985
Filed: Dec 2, 1983
Inventor
James E. Stangroom
Assignee (at issue)
NATIONAL RESEARCH DEVELOPMENT CORPORATION
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.