Granted Patent
Utility
US 4,560,397 · App. 06/641,205
Process to produce ultrahigh purity oxygen
Inventor:
Harry Cheung
Patented Case
View Patent ↗
Granted: Dec 24, 1985
Filed: Aug 16, 1984
Inventor
Harry Cheung
Assignee (at issue)
Union Carbide 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.