(19)

(11)

EP 0 951 688 A1

(12)

(43) Date of publication: 27.10.1999 Bulletin 1999/43 (21) Application number: 97913340.0 (22) Date of filing: 26.11.1997

(51) International Patent Classification (IPC):  H01L 27/ 14( . ) G06K 7/ 10( . ) G06K 19/ 07( . ) H01L 31/ 10( . ) G06K 7/ 08( . ) G06K 17/ 00( . ) G06K 19/ 077( . ) (86) International application number: PCT/GB1997/003228 (87) International publication number: WO 1998/024048 (04.06.1998 Gazette 1998/22)

(84) Designated Contracting States: DE DK ES FI FR GB IT NL SE (30) Priority: 26.11.1996 GB 19960024517 (71) Applicant: CENTRAL RESEARCH LABORATORIES LIMITED Hayes, Middlesex, UB3 1HH (GB)	(72) Inventor: GREEN, Ian, MacDonald London W3 6HW (GB) (74) Representative: Leaman, Keith  QED Patents Limited, Dawley Road Hayes, Middlesex UB3 1HH Hayes, Middlesex UB3 1HH (GB)