Granted Patent
Utility
US 4,621,936 · App. 06/542,315
Zirconia pen balls
Inventors:
John Hansson, Herbert L. Johns
Patented Case
View Patent ↗
Granted: Nov 11, 1986
Filed: Oct 14, 1983
Inventors
John Hansson
Herbert L. Johns
Assignee (at issue)
Corning Glass Works
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.