Granted Patent
Utility
US 4,720,356 · App. 07/058,629
Photochromic composition resistant to fatigue
Inventor:
Nori Y. C. Chu
Patented Case
View Patent ↗
Granted: Jan 19, 1988
Filed: Jun 4, 1987
Inventor
Nori Y. C. Chu
Assignee (at issue)
American Optical 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.