(19)

(11)

EP 0 664 918 A1

(12)

(43) Date of publication: 02.08.1995 Bulletin 1995/31 (21) Application number: 93922994.0 (22) Date of filing: 14.10.1993

(51) International Patent Classification (IPC):  G08B 3/ 06( . ) G10K 9/ 04( . ) (86) International application number: PCT/GB1993/002120 (87) International publication number: WO 1994/009479 (28.04.1994 Gazette 1994/10)

(84) Designated Contracting States: DE FR IT NL (30) Priority: 15.10.1992 GB 19920021623 (71) Applicant: WORTHINGTON, John Alfred Ware, Hertfordshire SG11 1JF (GB)	(72) Inventor: WORTHINGTON, John Alfred Ware, Hertfordshire SG11 1JF (GB) (74) Representative: Hooper, John Peter Lindesay  5 Haslingfield Road Harlton, Cambridge CB3 7ER Harlton, Cambridge CB3 7ER (GB)