Granted Patent
Utility
US 5,719,657 · App. 08/816,888
Progressive power lens
Inventors:
Yasunori Izawa, Moriyasu Shirayanagi
Patented Case
View Patent ↗
Granted: Feb 17, 1998
Filed: Mar 13, 1997
Inventors
Yasunori Izawa
Moriyasu Shirayanagi
Assignee (at issue)
Asahi Kogaku Kogyo 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.