| 摘要 |
<p>The invention relates to a particle or smoke detector which includes a light source illuminating a space, and a first photo-responsive device, such as a photo-resistive cell, a photo-generative cell, a photo-transistor, etc. associated electrical circuitry which produces a signal in response to the receipt by the photo-responsive device of light reflected from smoke or other particles. When the output of the first photo-responsive device exceeds the predetermined level, it energizes an alarm actuating means to provide an alarm output signal. A second photo-responsive cell is positioned to view ambient light. The second photoresponsive device is so connected into the circuitry of the first photo-responsive device as to cause a given smoke concentration to produce a greater output signal when the ambient light level decreases below a predetermined intensity compared to the output signal produced by the given smoke concentration when the ambient light level has a substantially higher intensity.</p> |
