(19)

(11)

EP 1 012 540 A1

(12)

(43) Date of publication: 28.06.2000 Bulletin 2000/26 (21) Application number: 97919531.0 (22) Date of filing: 23.04.1997

(51) International Patent Classification (IPC)7: G01D 5/26 (86) International application number: PCT/GB9701/123 (87) International publication number: WO 9740/344 (30.10.1997 Gazette 1997/46)

(84) Designated Contracting States: AT BE CH DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE (30) Priority: 23.04.1996 GB 9608370 10.03.1997 GB 9704937 (71) Applicant: R.D.P. Electronics Ltd. Wolverhampton WV10 0PY (GB)	(72) Inventors: WHITE, Ian, Hugh Somerset BA1 2YD (GB) GRIFFITHS, Roger, Phillip Neath SA10 6DN (GB) (74) Representative: Shaw, Laurence  5th Floor,Metropolitan House,1 Hagley Road,Edgbaston Birmingham B16 8TG Birmingham B16 8TG (GB)