Granted Patent
Utility
US 4,924,137 · App. 07/307,709
Cathode for electron tube
Inventors:
Keiji Watanabe, Keiji Fukuyama, Masako Ishida, Ryo Suzuki, Masato Saito
Patented Case
View Patent ↗
Granted: May 8, 1990
Filed: Feb 8, 1989
Inventors
Keiji Watanabe
Keiji Fukuyama
Masako Ishida
Ryo Suzuki
Masato Saito
Assignee (at issue)
MITSUBISHI ELECTRIC 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.