Granted Patent
Utility
US 4,571,721 · App. 06/418,898
Composite concentration system
Inventors:
Tadahiko Yasui, Shizuo Ito, Akira Horiki, Hajime Yamada, Takashi Usami
Patented Case
View Patent ↗
Granted: Feb 18, 1986
Filed: Sep 16, 1982
Inventors
Tadahiko Yasui
Shizuo Ito
Akira Horiki
Hajime Yamada
Takashi Usami
Assignees (at issue)
Nippon Telegraph and Telephone Public Corporation
NIPPON ELECTRIC CO., LTD.
HITACHI, LTD.
OKI ELECTRIC INDUSTRY CO., LTD.
Fujitsu Limited
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.