Granted Patent
Utility
US 4,628,265 · App. 06/487,699
Metal detector and classifier with automatic compensation for soil magnetic minerals and sensor misalignment
Inventors:
David E. Johnson, Richard Williams
Patented Case
View Patent ↗
Granted: Dec 9, 1986
Filed: Apr 22, 1983
Inventors
David E. Johnson
Richard Williams
Assignee (at issue)
FRL, 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.