(19)

(11)

EP 0 800 694 A1

(12)

(43) Date of publication: 15.10.1997 Bulletin 1997/42 (21) Application number: 96925845.0 (22) Date of filing: 26.07.1996

(51) International Patent Classification (IPC):  G08B 17/ 113( . ) G08B 26/ 00( . ) (86) International application number: PCT/GB1996/001800 (87) International publication number: WO 1997/005587 (13.02.1997 Gazette 1997/08)

(84) Designated Contracting States: DE GB (30) Priority: 27.07.1995 GB 19950015391 (71) Applicant: THORN SECURITY LIMITED Sunbury-on-Thames, Middlesex TW16 5DB (GB)	(72) Inventor: BAYLEY, Stephen, John Middlesex UB5 6QR (GB) (74) Representative: Marsh, Robin Geoffrey  Q.E.D. Patents Limited Dawley Road Hayes, Middlesex UB3 1HH Hayes, Middlesex UB3 1HH (GB)