Granted Patent
Utility
US 4,307,406 · App. 05/964,545
Multistyli recording systems
Inventor:
John Ruffell
Patented Case
View Patent ↗
Granted: Dec 22, 1981
Filed: Nov 29, 1978
Inventor
John Ruffell
Assignee (at issue)
Bell and Howell, LLC
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.