Granted Patent
Utility
US 5,822,280 · App. 08/642,914
Long term rapid color changing time indicator employing dye absorbing layer
Inventor:
David J. Haas
Patented Case
View Patent ↗
Granted: Oct 13, 1998
Filed: May 6, 1996
Inventor
David J. Haas
Assignee (at issue)
Temtec, 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.