| 摘要 |
An intruder deterrent system of the type which generates a smoke screen in response to detection of an intruder comprises: smoke screen density regulating means having a smoke screen density sensor 10 to sense the density of the smoke screen and control means 9 responsive to the sensed density to adjust the output of the smoke screen generating means to maintain the smoke screen density at a desired level. Smoke is generated by feeding a glycol/water mixture from reservoir 2 via pump 4 to a heating block 6 where it is vapourised. Pumping is cycled on and off to maintain smoke density at a desired level and may also be controlled in accordance with the temperature of the heating block 6 to ensure complete vapourisation. |
