Granted Patent
Utility
US 4,916,234 · App. 07/363,650
Chromogenic dicyanomethylenepyrazolinones
Inventors:
Hans Junek, Manfred Klade
Patented Case
View Patent ↗
Granted: Apr 10, 1990
Filed: Jun 8, 1989
Inventors
Hans Junek
Manfred Klade
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.