(19)

(11)

EP 0 250 461 A1

(12)

(43) Date of publication: 07.01.1988 Bulletin 1988/01 (21) Application number: 86906388.0 (22) Date of filing: 23.10.1986

(51) International Patent Classification (IPC):  G02B 5/ 30( . ) G02F 1/ 01( . ) H04B 10/ 148( . ) G02B 26/ 00( . ) G02F 1/ 09( . ) (86) International application number: PCT/GB1986/000656 (87) International publication number: WO 1987/002787 (07.05.1987 Gazette 1987/10)

(84) Designated Contracting States: AT BE CH DE FR IT LI LU NL SE (30) Priority: 24.10.1985 GB 19850026231 (71) Applicant: PLESSEY OVERSEAS LIMITED Ilford Essex IG1 4AQ (GB)	(72) Inventor: RYSDALE, Leslie, John Brierly Hill West Midlands DY5 2LR (GB) (74) Representative: Allen, Derek  The Plessey Company plc Intellectual Property Department Vicarage Lane Ilford Essex, IG1 4AQ Ilford Essex, IG1 4AQ (GB)