Granted Patent
Utility
US 4,447,679 · App. 06/360,847
Subscriber line testing system
Inventors:
Takafumi Kojima, Shigeru Yoshida, Masayuki Mizoguchi
Patented Case
View Patent ↗
Granted: May 8, 1984
Filed: Mar 22, 1982
Inventors
Takafumi Kojima
Shigeru Yoshida
Masayuki Mizoguchi
Assignees (at issue)
HITACHI, LTD.
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.