(19)

(11)

EP 0 519 018 A1

(12)

(43) Date of publication: 23.12.1992 Bulletin 1992/52 (21) Application number: 91909443.0 (22) Date of filing: 20.02.1991

(51) International Patent Classification (IPC):  G11B 7/ 0045( . ) G11B 11/ 03( . ) G11B 9/ 10( . ) G11B 11/ 08( . ) (86) International application number: PCT/US1991/001021 (87) International publication number: WO 1991/013440 (05.09.1991 Gazette 1991/21)

(84) Designated Contracting States: DE FR GB (30) Priority: 20.02.1990 GB 19900003829 20.02.1990 GB 19900003831 20.02.1990 GB 19900003832 (71) Applicant: TECHNOLOGY DEVELOPMENTS COMPANY Houston, TX 77000 (US)	(72) Inventor: DESTY, Denis Henry Surrey KT 12 5DT (GB) (74) Representative: Feakins, Graham Allan, et al  RAWORTH, MOSS & COOK RAWORTH HOUSE 36 Sydenham Road Croydon, Surrey CRO 2EF Croydon, Surrey CRO 2EF (GB)