Granted Patent
Utility
US 4,431,939 · App. 06/287,562
Structure and method for eliminating blocked apertures caused by charged particles
Inventor:
Karl G. Hernqvist
Patented Case
View Patent ↗
Granted: Feb 14, 1984
Filed: Jul 28, 1981
Inventor
Karl G. Hernqvist
Assignee (at issue)
RCA 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.