Granted Patent
Utility
US 4,928,033 · App. 07/272,231
Thermionic ionization source
Inventors:
Glenn E. Spangler, John P. Carrico, Donald N. Campbell
Patented Case
View Patent ↗
Granted: May 22, 1990
Filed: Nov 15, 1988
Inventors
Glenn E. Spangler
John P. Carrico
Donald N. Campbell
Assignee (at issue)
Environmental Technologies, LLC
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.