Granted Patent
Utility
US 5,481,294 · App. 08/144,289
Audience measurement system utilizing ancillary codes and passive signatures
Inventors:
William L. Thomas, Daozheng Lu
Patented Case
View Patent ↗
Granted: Jan 2, 1996
Filed: Oct 27, 1993
Inventors
William L. Thomas
Daozheng Lu
Assignee (at issue)
A.C. Nielsen Company
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.