FTInc has six (6) U.S. Patents on security features for checks, and other negotiable documents.  Here are links to the six patents with the date of issue:

U.S. Patent No.:	5,538,290	July 23, 1996
U.S. Patent No.:	5,575,508	November 19, 1996
U.S. Patent No.:	5,641,183	June 24, 1997
U.S. Patent No.:	5,785,353	July 23, 1996
U.S. Patent No.:	5,984,364	November 16, 1999
U.S. Patent No.:	6,030,000	February 29, 2000

All FTInc Patents (PDF)