Granted Patent
Utility
US 6,218,797 · App. 09/410,806
Crossing guard maintenance system and associated method
Inventors:
N. Rodger Williamson, III, Charles R. Drafts
Patented Case
View Patent ↗
Granted: Apr 17, 2001
Filed: Oct 1, 1999
Inventors
N. Rodger Williamson, III
Charles R. Drafts
Assignee (at issue)
Union Switch & Signal, 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.