(19)

(11)

EP 0 423 166 A1

(12)

(43) Date of publication: 24.04.1991 Bulletin 1991/17 (21) Application number: 89907224.0 (22) Date of filing: 15.06.1989

(51) International Patent Classification (IPC):  G11B 5/ 02( . ) (86) International application number: PCT/GB1989/000668 (87) International publication number: WO 1989/012886 (28.12.1989 Gazette 1989/30)

(84) Designated Contracting States: AT BE CH DE FR GB IT LI LU NL SE (30) Priority: 21.06.1988 GB 19880014723 20.04.1989 GB 19890008975 (71) Applicant: THE GOVERNORS OF PAISLEY COLLEGE OF TECHNOLOGY Paisley, Renfrewshire PA1 2BE (GB)	(72) Inventor: PETTIGREW, Archibald, McGilvray,''West Glen'' Renfrewshire PA13 4DE (GB) (74) Representative: Pacitti, Pierpaolo A.M.E.  Murgitroyd and Company 373 Scotland Street Glasgow G5 8QA Glasgow G5 8QA (GB)