Granted Patent
Utility
US 4,539,675 · App. 06/522,378
Echo canceller
Inventor:
David Fisher
Patented Case
View Patent ↗
Granted: Sep 3, 1985
Filed: Jul 15, 1983
Inventor
David Fisher
Assignee (at issue)
International Standard Electric 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.