Granted Patent
Utility
US 4,489,950 · App. 06/497,856
Ferrofluid-pole-piece-magnet apparatus
Inventor:
Alvan F. Chorney
Patented Case
View Patent ↗
Granted: Dec 25, 1984
Filed: May 25, 1983
Inventor
Alvan F. Chorney
Assignee (at issue)
Ferrofluidics 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.