EP 0125485 B1 19870311 - SIGNAL SUPPRESSION CIRCUIT FOR OPTICAL SMOKE DETECTORS
Title (en)
SIGNAL SUPPRESSION CIRCUIT FOR OPTICAL SMOKE DETECTORS
Publication
Application
Priority
DE 3313137 A 19830412
Abstract (en)
[origin: EP0125485A1] 1. A circuit arrangement in a fire alarm system, for suppressing interference signals in optical smoke detectors (RM) with a luminescence diode (LED) which transmits in pulsed fashion and with a photo-diode (FD) which receives diffused light from the luminescence diode (LED), where, during cyclic interrogation from central control (Z), the individual alarms (Mi) of an alarm line (ML) are connected in cascade to the alarm line (ML) in a predetermined sequence with a time delay and where the delay time until the connection of the following alarm corresponds to the analogue alarm measured value in question, and in the central control the alarm measured value and the alarm address are determined from the time of the connection, characterised in that the optical smoke detector (RM) comprises a voltage supply device (SPV) ; a transmitting circuit (MMV1) driven by the alarm interrogation (UAB) and serves to produce transmitted pulses (US) for the luminescence diode (LED), where the duration (TP) of the transmitted pulses is substantially shorter than the interrogation duration of an alarm ; an instantaneous value store (SHS), connected to the output of the photo-diode (FD) via the amplifier (VER), driven by the transmitting circuit (MMV1) to temporarily store the analogue alarm measured value ; and a voltage/time converter (VTC) connected to the output of the instantaneous value store, which connects the following alarm (Mi) to the alarm line (ML) via a switch-through transistor (TR) with a delay in accordance with the alarm measured value.
IPC 1-7
IPC 8 full level
G08B 17/10 (2006.01); G08B 17/107 (2006.01); G08B 26/00 (2006.01); G08B 29/18 (2006.01)
CPC (source: EP)
G08B 17/107 (2013.01); G08B 26/005 (2013.01); G08B 29/24 (2013.01)
Designated contracting state (EPC)
AT BE DE GB IT NL
DOCDB simple family (publication)
EP 0125485 A1 19841121; EP 0125485 B1 19870311; AT E25885 T1 19870315; DE 3313137 A1 19841018; DE 3462637 D1 19870416
DOCDB simple family (application)
EP 84103961 A 19840409; AT 84103961 T 19840409; DE 3313137 A 19830412; DE 3462637 T 19840409