(19)
(11) EP 0 919 969 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
03.05.2000 Bulletin 2000/18

(43) Date of publication A2:
02.06.1999 Bulletin 1999/22

(21) Application number: 98309021.8

(22) Date of filing: 04.11.1998
(51) International Patent Classification (IPC)7: G08B 13/183
(84) Designated Contracting States:
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
Designated Extension States:
AL LT LV MK RO SI

(30) Priority: 26.11.1997 GB 9725027

(71) Applicant: SECURITY ENCLOSURES LIMITED
Sutton, Surrey SM1 2UE (GB)

(72) Inventor:
  • Grant, John Thomas
    Reepham, Norfolk, NR10 4LD (GB)

(74) Representative: Jones, David Colin et al
Withers & Rogers, Goldings House 2 Hays Lane
London SE1 2HW
London SE1 2HW (GB)

   


(54) Infra red intrusion detection system


(57) An infra red intrusion detection system employs a transmitter unit having a plurality of transmitters (At, Bt, Ct, Dt) arranged in a transmitter housing and a plurality of receivers (Ar, Br, Cr, Dr) arranged in a receiver housing that is separate from the transmitter housing. A transmitter controller (2, 4, 6, 8) causes the transmitters to transmits in a predetermined sequence and at a predetermined transmit rate. A receiver controller (20, 22, 24, 26) is arranged to read the receiver inputs in a predetermined sequence and at a predetermined receive rate. By arranging for the transmit and receive rates to be different, the need for a synchronising link between the transmitters and the receivers is avoided, thus providing simplification.






Search report