(19)

(11)

EP 1 034 635 A1

(12)

(43) Date of publication: 13.09.2000 Bulletin 2000/37 (21) Application number: 98956257.4 (22) Date of filing: 27.10.1998

(51) International Patent Classification (IPC)7: H04K 1/00, H04L 9/00, G09C 5/00 (86) International application number: PCT/US9822/790 (87) International publication number: WO 9922/480 (06.05.1999 Gazette 1999/18)

(84) Designated Contracting States: AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE (30) Priority: 27.10.1997 US 63509 P (71) Applicant: The Trustees of Columbia University in the City of New York New York, NY 10027-6699 (US)	(72) Inventors: CHANG, Shih-Fu,Columbia University S.W. Mudd Building,Room 1312 (US) MENG, Jianhao New York, NY 10027 (US) (74) Representative: Howe, Steven et al Lloyd Wise, Tregear & Co.,Commonwealth House,1-19 New Oxford Street London WC1A 1LW London WC1A 1LW (GB)