Granted Patent
Utility
US 6,557,174 · App. 09/775,020
Replaceable, self-contained expanded viewing light shield cartridge for welding helmet
Inventors:
Edward L. Martin, Frederick P. Edgar
Patented Case
View Patent ↗
Granted: May 6, 2003
Filed: Feb 1, 2001
Inventors
Edward L. Martin
Frederick P. Edgar
Assignee (at issue)
Optical Engineering Company, 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.