Granted Patent
Utility
US 4,816,675 · App. 07/119,224
Quadrupole mass filter with unbalanced R.F. voltage
Inventors:
William J. Fies, Michael S. Story
Patented Case
View Patent ↗
Granted: Mar 28, 1989
Filed: Nov 4, 1987
Inventors
William J. Fies
Michael S. Story
Assignee (at issue)
Finnigan 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.