OPTICAL SMOKE DETECTOR Russian patent published in 2010 - IPC G08B17/10 

FIELD: physics; signaling.

SUBSTANCE: invention relates to fire detection devices, and specifically to optical smoke detectors with scattered optical radiation. The smoke detector has a measurement chamber with a cover, a bottom with openings for smoke penetration and a closed side guard. Inside the measurement chamber there is an optical radiation source and a photodetector in holders, lying at an angle to each other such that, the optical axis of the radiation source lies outside the field of vision of the photodetector. The measurement chamber also has peripheral elements which reflect optical radiation, lying on a section between holders of the optical radiation source and photodetector. The inner surface of the side guard on the section where there are peripheral reflecting elements is toothed and has the shape of adjacent triangular teeth radially directed relative the point of intersection of optical axes of the radiation source and photodetector in the horizontal cross sectional plane of the measurement chamber. The peripheral reflecting elements are made in form of laminated partitions radially directed relative the said point and the laminated partitions have in the horizontal cross-sectional plane of the measurement chamber a rectangular shape with a rhomb-shaped end, which adjoin peaks of the inner toothed surface of the side guard directed inside the working volume of the measurement chamber with formation of cells which absorb optical radiation, the inner surface of each of which is formed by the inner surface of the tooth of the side guard and oppositely lying surfaces of two neighbouring partitions. Mutual angular position and dimensions of faces of the multifaceted inner surface of the said cells are selected from the condition that, beams from the radiation source falling into their cavities undergo multiple reflection on their inner surfaces.

EFFECT: reduced background illumination signal of the smoke detector.

2 cl, 1 dwg