Granted Patent
Utility
US 3,977,432 · App. 05/540,388
Breathing mask and variable concentration oxygen diluting device therefor
Inventor:
Claude Vidal
Patented Case
View Patent ↗
Granted: Aug 31, 1976
Filed: Jan 13, 1975
Inventor
Claude Vidal
Assignee (at issue)
American Hospital Supply Corp.
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.