Granted Patent
Utility
US 4,680,374 · App. 06/765,802
Optical disc substrate made of a copolycarbonate
Inventors:
Masayoshi Hasuo, Seiichi Mukai, Hiroshi Urabe, Seiji Yoshida, Masahiro Nukui
Patented Case
View Patent ↗
Granted: Jul 14, 1987
Filed: Aug 15, 1985
Inventors
Masayoshi Hasuo
Seiichi Mukai
Hiroshi Urabe
Seiji Yoshida
Masahiro Nukui
Assignee (at issue)
Mitsubishi Chemical Industries, 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.