Granted Patent
Utility
US 5,244,602 · App. 07/624,816
Photochromic naphthopyrans
Inventor:
Barry Van Gemert
Patented Case
View Patent ↗
Granted: Sep 14, 1993
Filed: Dec 3, 1990
Inventor
Barry Van Gemert
Assignee (at issue)
PPG Industries, Inc.
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.