(19)

(11)

EP 0 919 067 A2

(12)

(43) Date of publication: 02.06.1999 Bulletin 1999/22 (21) Application number: 97936783.0 (22) Date of filing: 18.08.1997

(51) International Patent Classification (IPC):  H01J 49/ 40( . ) (86) International application number: PCT/GB1997/002182 (87) International publication number: WO 1998/008244 (26.02.1998 Gazette 1998/08)

(84) Designated Contracting States: DE FR GB (30) Priority: 17.08.1996 GB 19960017312 (71) Applicant: Millbrook Instruments Limited Blackburn, Lancashire BB1 5QB (GB)	(72) Inventors: STEELE, Timothy, Andrew, 227 Avenue Road Extension Leicestershire LE2 3ER (GB) UNWIN, Ronald, Charles Cheshire SK9 2NS (GB) ECCLES, Adrian, John Anglezarke PR6 9DF (GB) (74) Representative: Chugg, David John, et al  Appleyard Lees, 15 Clare Road Halifax, West Yorkshire HX1 2HY Halifax, West Yorkshire HX1 2HY (GB)