Granted Patent
Utility
US 5,047,639 · App. 07/455,072
Concentration detector
Inventor:
Jacob Y. Wong
Patented Case
View Patent ↗
Granted: Sep 10, 1991
Filed: Dec 22, 1989
Inventor
Jacob Y. Wong
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.