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US 2015/0103346 A1Published application
Smoke detector with external sampling volume and ambient light rejection
AssigneeValor Fire Safety, LLC
InventorMatthew Erdtmann
Life of this patent
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Abstract
In accordance with certain embodiments, a smoke detector determines the presence of smoke particles outside its housing based on measurements of light detected at different wavelengths and corrected based on an ambient light level.
Claims35
A smoke detector comprising:
- a housing;
- one or more light emitters for emitting, outside the housing, light of a first wavelength and a second wavelength longer than the first wavelength;
- one or more light detectors for detecting (i) light emitted from the one or more light emitters reflected back to the one or more light detectors from a sampling volume outside of the housing, thereby providing measurements of reflected light including the first and second wavelengths, and (ii) an ambient light level outside of the housing;
- one or more optical elements configured to alter a position of at least a portion of the sampling volume by altering an emission trajectory of light emitted from at least one of the one or more light emitters;
- and
- an evaluation circuit for (i) correcting a measurement of reflected light including the first wavelength based on the detected ambient light level, thereby producing a corrected first-wavelength measurement, (ii) correcting a measurement of reflected light including the second wavelength based on the detected ambient light level, thereby producing a corrected second-wavelength measurement, and (iii) determining the presence of smoke particles outside the housing based on a ratio of the corrected first-wavelength measurement to the corrected second-wavelength measurement.
3 more elements
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A smoke detector comprising:
- a housing;
- one or more light emitters for emitting, outside the housing, light of a first wavelength and a second wavelength longer than the first wavelength, wherein a portion of at least one said light emitter is disposed substantially flush with a surface of the housing or protrudes out of the housing;
- one or more light detectors for detecting (i) light emitted from the one or more light emitters reflected back to the one or more light detectors from a sampling volume outside of the housing, thereby providing measurements of reflected light including the first and second wavelengths, and (ii) an ambient light level outside of the housing;
- and
- an evaluation circuit for (i) correcting a measurement of reflected light including the first wavelength based on the detected ambient light level, thereby producing a corrected first-wavelength measurement, (ii) correcting a measurement of reflected light including the second wavelength based on the detected ambient light level, thereby producing a corrected second-wavelength measurement, and (iii) determining the presence of smoke particles outside the housing based on a ratio of the corrected first-wavelength measurement to the corrected second-wavelength measurement.
2 more elements
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Dependencies are inferred from the claim text.