Granted Patent
Utility
US 4,623,991 · App. 06/676,729
Delta-shaped geophone spring
Inventor:
Frederick A. Vitringa
Patented Case
View Patent ↗
Granted: Nov 18, 1986
Filed: Nov 30, 1984
Inventor
Frederick A. Vitringa
Assignee (at issue)
Geosource, 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.