Granted Patent
Utility
US 4,933,975 · App. 07/196,438
Dynamic loudspeaker for producing high audio power
Inventor:
Douglas J. Button
Patented Case
View Patent ↗
Granted: Jun 12, 1990
Filed: May 19, 1988
Inventor
Douglas J. Button
Assignee (at issue)
Electro-Voice, 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.