Granted Patent
Utility
US 4,417,072 · App. 06/306,846
Hydroquinone derivatives and their use in photographic materials
Inventors:
Stephen Postle, Patrick D. P. Thomas, Brian R. D. Whitear
Patented Case
View Patent ↗
Granted: Nov 22, 1983
Filed: Sep 29, 1981
Inventors
Stephen Postle
Patrick D. P. Thomas
Brian R. D. Whitear
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.