Optical smoke detector

Abstract From the Canadian patent

An optical smoke detector including a plurality of walls extending from a dark chamber in which an optical smoke sensor is located, The walls form passages in the detector which extend from smoke entrances on the outer perimeter to smoke ports that feed into the dark chamber, In construction the smoke, entrances extend substantially continuously around the perimeter of the smoke detector to allow the free entry of smoke into the dark chamber, Each wall is arranged to overlap the next so as to obstruct the direct rays of light from entering the dark chamber and a screen is disposed around the perimeter of the detector to prevent the entrance of insects into the dark chamber.