| 摘要 |
A smoke detector comprising a radiation source producing a directed radiation beam and a scattered radiation receiver arrangement having directional characteristics. An evaluation circuit is operatively connected with the receiver arrangement for delivering a signal whenever there is exceeded a predetermined degree of radiation scattered at smoke particles within the radiation beam. Either the radiation source, the radiation receiver arrangement, or both, have such directional characteristic and the evaluation circuit is constructed such that the radiation received from two fields of view of the radiation receiver arrangement are compared with one another. These two fields of view are differently situated relative to the radiation beam and both fields of view contain a markedly different amount of scattered radiation, but receive at least approximately the same spurious radiation from at least approximately the same background. |
