Granted Patent
Utility
US 4,243,321 · App. 06/069,925
Handy refractometer
Inventors:
Minoru Okuda, Mikio Ito
Patented Case
View Patent ↗
Granted: Jan 6, 1981
Filed: Aug 27, 1979
Inventors
Minoru Okuda
Mikio Ito
Assignee (at issue)
Nippon Kogaku K.K.
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.