Granted Patent
Utility
US 4,302,579 · App. 06/171,869
Optical brightening agents and photographic materials which contain these brightening agents
Inventor:
Graham Evans
Patented Case
View Patent ↗
Granted: Nov 24, 1981
Filed: Jul 24, 1980
Inventor
Graham Evans
Assignee (at issue)
Ciba-Geigy
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.