| 摘要 |
A smoke detector which has a rate detector for detecting the rate of increase of smoke concentration. In one embodiment of the invention an alarm signal is provided when the rate of increase of smoke concentration exceeds a predetermined rate. In another embodiment of the invention, the smoke detector has means for providing an alarm signal if the smoke concentration reaches a predetermined value, and also has means responsive to d rate of increase of smoke concentration above a predetermined rate to cause said alarm to be actuated at a smoke concentration substantially lower than said predetermined concentration. |
