(19)

(11)

EP 0 223 812 A1

(12)

(43) Date of publication: 03.06.1987 Bulletin 1987/23 (21) Application number: 86903471.0 (22) Date of filing: 20.05.1986

(51) International Patent Classification (IPC):  H03K 5/ 13( . ) H03L 7/ 081( . ) H03L 7/ 197( . ) H03K 7/ 08( . ) H03L 7/ 187( . ) (86) International application number: PCT/GB1986/000283 (87) International publication number: WO 1986/007219 (04.12.1986 Gazette 1986/26)

(84) Designated Contracting States: AT BE CH DE FR GB IT LI LU NL SE (30) Priority: 22.05.1985 GB 19850012912 (71) Applicant: PLESSEY OVERSEAS LIMITED Ilford Essex IG1 4AQ (GB)	(72) Inventor: ATTENBOROUGH, Colin Cambridge CB5 9NX (GB) (74) Representative: Sorenti, Gino  Intellectual Property Department The Plessey Company plc 2-60 Vicarage Lane Ilford Essex IG1 4AQ Ilford Essex IG1 4AQ (GB)