Patent ID: 8947244
Filing Date: 2015-02-03
Classification: G01N,G08B

Abstract:
1. A smoke detector comprising: a housing; disposed within the housing, a light source configured to direct light outside of the housing, the directed light comprising a plurality of different wavelengths, wherein the light source is configured to emit an interior portion of light within the housing substantially without emission therefrom; disposed within the housing, one or more light detectors configured to detect light from the light source that is reflected back into the housing, at least one said detector being configured to detect light from the interior light portion within the housing; and an evaluation circuit for determining the presence of smoke particles outside the housing based at least in part on (i) a difference between a luminance of a first wavelength of the detected light and a luminance of a second wavelength of the detected light, wherein the second wavelength is different from the first wavelength, and (ii) a luminance of light detected from the interior light portion.