(19)

(11)

EP 0 502 044 A1

(12)

(43) Date of publication: 09.09.1992 Bulletin 1992/37 (21) Application number: 90917313.0 (22) Date of filing: 15.11.1990

(51) International Patent Classification (IPC):  G02F 1/ 015( . ) G02F 1/ 21( . ) H01L 21/ 20( . ) H01L 31/ 0352( . ) G02F 1/ 017( . ) G02F 3/ 00( . ) H01L 27/ 15( . ) H01L 31/ 18( . ) (86) International application number: PCT/GB1990/001759 (87) International publication number: WO 1991/007688 (30.05.1991 Gazette 1991/12)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB GR IT LI LU NL SE (30) Priority: 20.11.1989 GB 19890026183 (71) Applicant: BRITISH TELECOMMUNICATIONS public limited company London EC1A 7AJ (GB)	(72) Inventors: REJMAN-GREENE, Marek, Andrzej, Zbigniew Ipswich Suffolk IP2 9DY (GB) SCOTT, Edward, Geoffrey 56A The Laurels Hadleigh Suffolk IP7 6BS (GB) (74) Representative: Miselbach, Roger George  British Telecom Intellectual Property Unit 13th Floor 151 Gower Street London WC1E 6BA London WC1E 6BA (GB)