| 摘要 |
The smoke detector contains at least one electromagnetic radiation source (18), a measurement- (22) and reference-radiation path (20) with equal-length radiation paths in the measurement and reference beam. After travelling along the respective radiation path, the radiation is received in each case by a receiver (24, 26). To compensate for the effects of dirt on windows (48, 50) which cover certain parts of the radiation path, and on deflecting reflectors which extend the radiation paths, the condition must be satisfied wherein the total formed from the number of dirt-exposed window surfaces and the number of dirt-exposed reflectors which are metal-coated on the front and twice the number of dirt-exposed reflectors which are metal-coated on the back is equal in both radiation paths. The smoke detector is preferably used for fire alarms. <IMAGE> |
