EP 0079010 B1 19860611 - SMOKE DETECTOR
Title (en)
SMOKE DETECTOR
Publication
Application
Priority
CH 724881 A 19811111
Abstract (en)
[origin: ES8401656A1] A smoke detector is disclosed having a radiation source operated in a pulsed mode. Externally of a direct radiation region of the radiation source there is arranged a radiation receiver which, in the presence of smoke or other particles emanating from a combustion process and located in the radiation region, is impinged by scattered radiation and delivers an output signal to an evaluation circuit. The evaluation circuit contains switching elements which, when the number of source output signals or pulses exceeds a predetermined threshold value for the number of source output pulses, delivers an alarm signal. Near to the radiation receiver there is arranged a reference cell in the direct radiation beam of the radiation source, this reference cell controlling the emission of radiation by the radiation source. Further, there is provided circuitry which, in the presence of a slow change in the amplitude of the receiver output pulse, adjusts an amplitude threshold value set for the amplitude of the receiver output pulse at a rate corresponding to a time-constant of more than one minute. Consequently, there is obtained an output signal of the radiation receiver which is dependent upon the smoke density and which is independent of the contamination or soiling of the smoke detector.
IPC 1-7
IPC 8 full level
G01N 21/53 (2006.01); G08B 17/10 (2006.01); G08B 17/107 (2006.01); G08B 29/00 (2006.01); G08B 29/04 (2006.01); G08B 29/24 (2006.01)
CPC (source: EP US)
G08B 17/107 (2013.01 - EP US); G08B 17/113 (2013.01 - EP US); G08B 29/043 (2013.01 - EP US); G08B 29/24 (2013.01 - EP US)
Designated contracting state (EPC)
AT BE DE FR GB IT LU NL SE
DOCDB simple family (publication)
EP 0079010 A1 19830518; EP 0079010 B1 19860611; AT E20398 T1 19860615; AU 556838 B2 19861120; AU 9017682 A 19830519; BR 8206536 A 19830927; CA 1208334 A 19860722; CH 655396 B 19860415; DE 3271683 D1 19860717; DK 502382 A 19830512; ES 517587 A0 19831216; ES 8401656 A1 19831216; FI 823837 A0 19821109; FI 823837 L 19830512; IL 67158 A0 19830331; JP S5888641 A 19830526; NO 156149 B 19870421; NO 156149 C 19870805; NO 823753 L 19830513; NZ 202365 A 19850913; US 4555634 A 19851126; YU 252382 A 19851031; ZA 828097 B 19830928
DOCDB simple family (application)
EP 82110013 A 19821029; AT 82110013 T 19821029; AU 9017682 A 19821104; BR 8206536 A 19821110; CA 414877 A 19821104; CH 724881 A 19811111; DE 3271683 T 19821029; DK 502382 A 19821111; ES 517587 A 19821109; FI 823837 A 19821109; IL 6715882 A 19821102; JP 19686782 A 19821111; NO 823753 A 19821110; NZ 20236582 A 19821102; US 43905982 A 19821103; YU 252382 A 19821110; ZA 828097 A 19821104