Granted Patent
Utility
US 4,393,324 · App. 06/185,956
Spark plug with a sphere-like metal center electrode and manufacturing process thereof
Inventors:
Kanemitsu Nishio, Shunichi Takagi, Yasuhiko Suzuki
Patented Case
View Patent ↗
Granted: Jul 12, 1983
Filed: Sep 10, 1980
Inventors
Kanemitsu Nishio
Shunichi Takagi
Yasuhiko Suzuki
Assignee (at issue)
NGK SPARK PLUG CO., LTD.
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.