Granted Patent
Utility
US 4,990,426 · App. 07/463,564
Di- and tricationic negative charge control agents for electrophotographic developers
Inventors:
Arthur F. Diaz, Adolfo R. Gutierrez, Dennis McKean
Patented Case
View Patent ↗
Granted: Feb 5, 1991
Filed: Jan 11, 1990
Inventors
Arthur F. Diaz
Adolfo R. Gutierrez
Dennis McKean
Assignee (at issue)
International Business Machines 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.