Granted Patent
Utility
US 4,480,156 · App. 06/319,783
Echo canceller system
Inventors:
Kenzo Takahashi, Takashi Sakamoto
Patented Case
View Patent ↗
Granted: Oct 30, 1984
Filed: Nov 9, 1981
Inventors
Kenzo Takahashi
Takashi Sakamoto
Assignee (at issue)
Nippon Telegraph and Telephone Public 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.