Granted Patent
Utility
US 4,382,171 · App. 06/188,793
Arc welding current supply
Inventor:
John B. G. Hedberg
Patented Case
View Patent ↗
Granted: May 3, 1983
Filed: Sep 19, 1980
Inventor
John B. G. Hedberg
Assignee (at issue)
Thermal Dynamics 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.