Optical improvements to compact smoke detectors, systems and apparatus
Device for improving an optical detecting smoke apparatus and implementing thereof. Apparatus and methods for detecting the presence of smoke in a small, long-lasting smoke detector are disclosed. Specifically, the present disclosure shows how to build one or more optimized blocking members in a smoke detector to augment signal to noise ratio. This is performed while keeping the reflections from the housing structure to a very low value while satisfying all the other peripheral needs of fast response to smoke and preventing ambient light. This allows very small measurements of light scattering of the smoke particles to be reliable in a device resistant to the negative effects of dust. In particular, geometrical optical elements, e.g., cap and optical deflection elements, are disclosed.
1. An optical smoke detector configured to detect a scattering of smoke particles comprising:
a first light source having a top surface, the first light source configured to emit a first light in a conical shape in a direction normal to the top surface;
a first photodetector having a top surface disposed in substantially a same plane as the top surface of the first light source;
a septum disposed in between the first light source and the first photodetector;
a barrier disposed directly above the top surface of the first light source which substantially blocks the first light emitted from the first light source in a center of the conical shape of the first light; and
a circuit configured to:
receive electrical communication from the first photodetector; and
predominantly weigh the scattering at angles less than 90 and greater than 50 degrees to incident light rays;
wherein the barrier forms an enclosing chamber over the first light source,
wherein the enclosing chamber has at least a partially arcuate shape; and
wherein the partially arcuate shape ends at least partially over the first light source to block vertical light emanating from the first light source.
2. The optical smoke detector of claim 1 , further comprising a second light source and a second photodetector.
3. The optical smoke detector of claim 2 , wherein the second photodetector is disposed further away from the second light source relative to a distance between the first light source and first photodetector, and wherein the circuit is further configured to more heavily weigh the electrical communication from the first photodetector than the second photodetector.
4. The optical smoke detector of claim 2 , wherein the first light source and the second light source emit light at different bandwidths.
5. The optical smoke detector of claim 2 , wherein the circuit is further configured to control the first light source and the second light source.
6. The optical smoke detector of claim 2 , wherein the second photodetector is disposed so as to capture light scattered at greater than 90 degrees.
7. The optical smoke detector of claim 1 , further comprising an optical filter.
8. The optical smoke detector of claim 1 , further comprising a lens configured to increase an optical collection efficiency of the first photodetector.
9. The optical smoke detector of claim 1 , further comprising one or more further barriers configured to block light from at least one or more of the first light source.
10. The optical smoke detector of claim 1 , wherein at least a first portion of the enclosing chamber is cantilevered by a second portion of the enclosing chamber to be at least partially directly over the first light source.
11. The optical smoke detector of claim 1 , wherein the septum forms a coplanar barrier disposed between the first light source and the first photodetector with two places facing the first light source.
12. The optical smoke detector of claim 1 , further comprising a thin film interference coating disposed over the first photodetector.
13. A method for detecting scattered smoke particles, the method comprising:
emitting a first light from a first light source at a first wavelength, the first light source having a top surface, the first light source configured to emit the first light in a conical shape in a direction normal to the top surface;
scattering the first light;
collecting first scattered light at a first photodetector having a top surface disposed in substantially a same plane as the first light source;
disposing a septum in between the first light source and the first photodetector;
blocking a portion of the first light which is emitted from the first light source via a barrier, wherein the portion of the first light that is blocked is directly above the top surface of the first light source in a center of the conical shape of the first light;
receiving electrical communication from the first photodetector; and
predominantly weighing the scattering at angles less than 90 degrees and greater and 50 to incident light rays;
wherein the barrier forms an enclosing chamber over the first light source,
wherein the enclosing chamber has at least a partially arcuate shape; and
wherein the partially arcuate shape ends at least partially over the first light source to block vertical light emanating from the first light source.
14. The method of claim 13 , further comprising:
emitting a second light from a second light source at a second wavelength; and
scattering the second light and collecting the second scattered light at a second photodetector disposed in substantially the same plane as the second light source.
15. The method of claim 14 , wherein the second photodetector is disposed further away from the second light source relative to a distance between the first light source and first photodetector, and the method further comprises more heavily weighing the electrical communication from the first photodetector.
16. The method of claim 14 , further comprising optically filtering at least one of the first wavelength and the second wavelength.
17. The method of claim 14 , further comprising controlling the first light source and the second light source.
18. An optical smoke detector, comprising:
a first light source and a second light source;
a first photodetector disposed in substantially the same plane as the first light source;
a second photodetector disposed further away from the second light source relative to a distance between the first light source and first photodetector;
a septum disposed in between the first light source and the first photodetector;
a blocking member which substantially blocks orthogonally emitted light from the first light source; and
a circuit configured to:
receive electrical communication from the first photodetector;
predominantly weigh the scattering at angles less than 90 and greater than 50 degrees to incident light rays; and
more heavily weigh the electrical communication from the first photodetector than the second photodetector;
wherein the blocking member forms an enclosing chamber over the first light source,
wherein the enclosing chamber has at least a partially arcuate shape; and
wherein the partially arcuate shape ends at least partially over the first light source to block vertical light emanating from the first light source.