(19)

(11)

EP 0 653 098 A1

(12)

(43) Date of publication: 17.05.1995 Bulletin 1995/20 (21) Application number: 93917959.0 (22) Date of filing: 30.07.1993

(51) International Patent Classification (IPC):  H01F 6/ 00( . ) H02J 15/ 00( . ) (86) International application number: PCT/GB1993/001619 (87) International publication number: WO 1994/003910 (17.02.1994 Gazette 1994/05)

(84) Designated Contracting States: DE FR GB IT NL (30) Priority: 31.07.1992 GB 19920016299 (71) Applicant: OXFORD INSTRUMENTS PLC Witney, Oxford OX8 1TL (GB)	(72) Inventors: MCDOUGALL, Ian, Leitch 16 Lees Heights Oxon OX8 1EL (GB) HANLEY, Peter Gloucestershire GL15 5JQ (GB) (74) Representative: Skone James, Robert Edmund  GILL JENNINGS & EVERY Broadgate House 7 Eldon Street London EC2M 7LH London EC2M 7LH (GB)