Granted Patent
Utility
US 4,239,329 · App. 06/060,881
Optical nonreciprocal device
Inventor:
Takao Matsumoto
Patented Case
View Patent ↗
Granted: Dec 16, 1980
Filed: Jul 26, 1979
Inventor
Takao Matsumoto
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.