Granted Patent
Utility
US 4,891,508 · App. 07/213,405
Precision infrared position detector apparatus for touch screen system
Inventor:
John W. Campbell
Patented Case
View Patent ↗
Granted: Jan 2, 1990
Filed: Jun 30, 1988
Inventor
John W. Campbell
Assignee (at issue)
Hewlett-Packard Company, L.P.
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.