| 摘要 |
An optical smoke detector (10) is provided that comprises a light source (154), a light receiver (172), and a control circuit (130) for controlling operation of the detector. The control circuit (130) is configured to apply an unregulated voltage to the to cause it to emit light, to monitor the current through said light source (154) so as to monitor the light emitted by said light source (154); and to monitor the current generated by light received by said light receiver (172) so as to monitor the light received by said light receiver (172). The control circuit (130) generates a ratio signal representative of the ratio of the monitored currents; and compares the ratio signal with a reference value and generate a smoke detection signal in dependence thereon. |
