Granted Patent
Utility
US 4,641,021 · App. 06/693,540
Variable bandwidth low-pass filter for line tracer accuracy control
Inventor:
Enn Vali
Patented Case
View Patent ↗
Granted: Feb 3, 1987
Filed: Jan 22, 1985
Inventor
Enn Vali
Assignee (at issue)
Westinghouse Canada Inc.
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.