(19)

(11)

EP 0 151 597 A1

(12)

(43) Date of publication: 21.08.1985 Bulletin 1985/34 (21) Application number: 84902811.0 (22) Date of filing: 19.07.1984

(51) International Patent Classification (IPC):  H03M 11/ 00( . ) (86) International application number: PCT/GB1984/000255 (87) International publication number: WO 1985/000713 (14.02.1985 Gazette 1985/04)

(84) Designated Contracting States: AT BE CH DE FR GB LI LU NL SE (30) Priority: 27.07.1983 GB 19830020294 (71) Applicant: PRUTEC LIMITED London EC1N 2NH (GB)	(72) Inventors: CASSEY, Martin C. Patscentre International Hertfordshire SG8 6DP (GB) NEWMAN, Perran, Vincent, Leonard Wittlesford Cambridge CB2 4NT (GB)