(19)

(11)

EP 0 454 750 A1

(12)

(43) Date of publication: 06.11.1991 Bulletin 1991/45 (21) Application number: 90902319.0 (22) Date of filing: 16.01.1990

(51) International Patent Classification (IPC):  G01B 21/ 20( . ) A61B 5/ 117( . ) G06T 1/ 00( . ) G07C 9/ 00( . ) A61B 5/ 11( . ) G06K 9/ 00( . ) G06T 7/ 00( . ) G10H 1/ 00( . ) (86) International application number: PCT/GB1990/000066 (87) International publication number: WO 1990/008366 (26.07.1990 Gazette 1990/17)

(84) Designated Contracting States: CH DE FR GB LI (30) Priority: 16.01.1989 GB 19890000866 (71) Applicant: NATIONAL RESEARCH DEVELOPMENT CORPORATION London SE1 6BU (GB)	(72) Inventors: CLAYDEN, David, Oswald Middlesex TW7 5PH (GB) CULLIS, Roger Surrey GU6 8BZ (GB) (74) Representative: Cullis, Roger  Patents Department British Technology Group Ltd 101 Newington Causeway London SE1 6BU London SE1 6BU (GB)