Granted Patent
Utility
US 4,638,207 · App. 06/841,137
Piezoelectric polymeric film balloon speaker
Inventor:
Peter F. Radice
Patented Case
View Patent ↗
Granted: Jan 20, 1987
Filed: Mar 19, 1986
Inventor
Peter F. Radice
Assignee (at issue)
Pennwalt 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.