Granted Patent
Utility
US 4,551,583 · App. 06/587,373
Control signal transmission system for key telephone system
Inventors:
Koichi Sekiguchi, Hikaru Takematsu, Kazuyuki Yamamoto, Teruyuki Kubo
Patented Case
View Patent ↗
Granted: Nov 5, 1985
Filed: Mar 8, 1984
Inventors
Koichi Sekiguchi
Hikaru Takematsu
Kazuyuki Yamamoto
Teruyuki Kubo
Assignees (at issue)
Telegraph & Telephone Pub. Corp.
Iwasaki Tsushinki Kabushiki Kaisha
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.