Granted Patent
Utility
US 6,434,238 · App. 08/909,480
Multi-purpose transaction card system
Inventors:
David Chaum, Niels T. Ferguson, Jelte Willem Jan Van Der Hoek
Patented Case
View Patent ↗
Granted: Aug 13, 2002
Filed: Aug 11, 1997
Inventors
David Chaum
Niels T. Ferguson
Jelte Willem Jan Van Der Hoek
Assignee (at issue)
Info Space, Inc.
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.