(19)

(11)

EP 0 543 822 A1

(12)

(43) Date of publication: 02.06.1993 Bulletin 1993/22 (21) Application number: 91910739.0 (22) Date of filing: 14.06.1991

(51) International Patent Classification (IPC):  H01J 63/ 00( . ) (86) International application number: PCT/GB1991/000959 (87) International publication number: WO 1991/020092 (26.12.1991 Gazette 1991/29)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB GR IT LI LU NL SE (30) Priority: 19.06.1990 GB 19900013677 (71) Applicant: GE LIGHTING LIMITED Enfield, Middlesex EN1 1SB (GB)	(72) Inventors: TAMBINI, Antony Leicester LE4 7YF (GB) HOPKIN, Ian Cornwall PL14 6DG (GB) (74) Representative: Pratt, Richard Wilson  London Patent Operation G.E. Technical Services Co. Inc. Essex House 12/13 Essex Street London WC2R 3AA London WC2R 3AA (GB)