(19)

(11)

EP 0 054 558 A1

(12)

(43) Date of publication: 30.06.1982 Bulletin 1982/26 (21) Application number: 81901692.0 (22) Date of filing: 19.06.1981

(51) International Patent Classification (IPC):  G01R 13/ 00( . ) G02F 1/ 1343( . ) G09G 3/ 36( . ) G01R 13/ 40( . ) G09G 3/ 20( . ) (86) International application number: PCT/GB1981/000105 (87) International publication number: WO 1982/000206 (21.01.1982 Gazette 1982/03)

(84) Designated Contracting States: CH DE FR LI NL (30) Priority: 27.06.1980 GB 19800021073 (71) Applicant: NATIONAL RESEARCH DEVELOPMENT CORPORATION London SE1 6BU (GB)	(72) Inventor: SHANKS, Ian Alexander Malvern Worcestershire (GB) (74) Representative: Gunning, William John  Procurement Executive, Ministry of Defence Patents 1A(4), Room 1932 Empress State Building Lillie Road London SW6 1TR London SW6 1TR (GB)