Patent ID: 8638436

Claim:
A smoke sensing system comprising: a light-projecting means for projecting detection light toward a monitored area; a plurality of light-receiving means for receiving the detection light scattered by particles existing in the monitored area at the same timing, the plurality of light-receiving means being arranged such that the angles between the light-receiving axes of the plurality of light-receiving means and the light-projecting axis of the light-projecting means are different from one another; a smoke type determining means for determining a type of smoke generated in the monitored area based on output values output from the plurality of light-receiving means; and a fire determining means for determining whether or not a fire has occurred in the monitored area, based on the output values output from the plurality of light-receiving means; and an obstacle determining means for determining whether or not an obstacle exists in the monitored area, based on the output values output from the plurality of light-receiving means, wherein the smoke type determining means determines the type of smoke generated in the monitored area based on a ratio between the output values output from the plurality of light-receiving means and, wherein the obstacle determining means determines whether or not an obstacle exists in the monitored area, based on the total of the output values output from the plurality of light-receiving means.