Granted Patent
Utility
US 5,144,253 · App. 07/631,319
Method and apparatus for determining interactions due to direct currents on adjacent buried metal structures
Inventor:
Michel Blanchard
Patented Case
View Patent ↗
Granted: Sep 1, 1992
Filed: Dec 21, 1990
Inventor
Michel Blanchard
Assignee (at issue)
Gaz de France
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.