Granted Patent
Utility
US 5,239,172 · App. 07/689,878
Light converging filter and method for manufacturing the same
Inventors:
Toshio Yokota, Hajime Mori
Patented Case
View Patent ↗
Granted: Aug 24, 1993
Filed: May 17, 1991
Inventors
Toshio Yokota
Hajime Mori
Assignee (at issue)
Dai Nippon Printing 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.