(19)

(11)

EP 0 419 496 A1

(12)

(43) Date of publication: 03.04.1991 Bulletin 1991/14 (21) Application number: 89905424.0 (22) Date of filing: 02.05.1989

(51) International Patent Classification (IPC):  G06K 9/ 62( . ) (86) International application number: PCT/GB1989/000461 (87) International publication number: WO 1989/010596 (02.11.1989 Gazette 1989/26)

(84) Designated Contracting States: AT BE CH DE FR GB IT LI LU NL SE (30) Priority: 30.04.1988 GB 19880010357 (71) Applicant: THE VICTORIA UNIVERSITY OF MANCHESTER Manchester M13 9PL (GB)	(72) Inventors: HICKEY, David, Stephen Manchester M14 6PT (GB) PRENDERGAST, David, Jeremy Sheffield S10 1WH (GB) (74) Representative: Allman, Peter John  MARKS & CLERK, Sussex House, 83-85 Mosley Street Manchester M2 3LG Manchester M2 3LG (GB)