Method of smoke detection with direct detection of light and detection of light reflected from an external sampling volume

摘要

In accordance with certain embodiments, a smoke detector comprises a housing, a light source, one or more light detectors, and an evaluation circuit for determining the presence of smoke particles outside the housing based on light emitted from and reflected back into the housing, as well as light emitted within the housing without emission therefrom.

主权项

1. A method of smoke detection, the method comprising:
emitting a first light portion to an external sampling volume disposed outside of a housing; emitting a second light portion to one or more light detectors without reflection of the second light portion from the external sampling volume; detecting light from the first light portion reflected back to at least one said light detector; detecting light from the second light portion with at least one said light detector; and determining the presence of smoke particles outside the housing based at least in part on (i) at least one of a luminance or a rate of change of luminance of detected light from the first light portion, and (ii) a luminance of detected light from the second light portion.