| 摘要 |
An alarm device (K) is actuated by an integrator (T) only if a photocell (C) receives a plurality of successive light pulses, reflected by smoke. In the disconnected mode, a light source (LED) is fed by a pulse generator (P) with low frequency. A first light pulse reflected by smoke occurring triggers via the photocell (C) a flip-flop (F), the output signal of which closes a switch (S1) in order to reduce the distance from the next pulse emitted by the pulse generator (P). Thus, if smoke persists, the number of pulses which the integrator (T) requires to set off the alarm is received in a shorter time. In another embodiment, the pulse frequency is increased by the first light pulse reflected by the smoke for the duration of a predetermined number of pulses or for the duration of a predetermined period of time. In both embodiments, the time required for the alarm to be set off is thus reduced, without increasing the power consumption of the detector device in the disconnected mode and without reducing the service life of the pulsating light source. <IMAGE> |
