| 摘要 |
The smoke detector is provided in particular for issuing fire alarms. It is provided with a radiation source (4, 5, 6) with a conical ring-shaped radiation characteristic and with a radiation receiver (R) which is arranged in the axis (A) but outside the direct radiation and receives scattered radiation from smoke particles in the conical ring-shaped radiation area (C). In order to avoid the increase in the interference radiation level brought about by the slow filling with dust of the interior of the detector, a system of concentric webs (S) which are arranged rotationally symmetrically with respect to the axis of the cone and have a circular ring-shaped cross-section are provided, which webs (S) terminate the radiation area (C) and are constructed in such a way that a reduction in the interference radiation impinging on the radiation receiver (R) is brought about and deposition of dust on the elements (S) which are struck by direct radiation is avoided. <IMAGE> |
