Colour sensing apparatus and method
OwnerPeter Hemingwayinventor
Life of this patent
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Abstract
Using a plurality of relatively narrowband light sensors having overlapping response characteristics, accurate and self-calibrating colour measurements may be carried out. With sufficient measurements, simultaneous equations may be solved to derive a light intensity measurement at portions of the spectrum at which the overlapping sensor responses intercept. Using LEDs as light sensors provides cheap narrowband sensors and provides the additional advantage that the LEDs may also be used to illuminate a source to provide additional cross-reference measurements. Using sensors and/or illumination sources directed at several angles may also be used to improve sensing accuracy by mitigating the effects of surface texture and/or fluorescence.
Claims11
A colour sensor having a plurality of photosensitive devices of differing and overlapping spectral responses and switching means arranged to read the electrical output of each photosensitive device separately and wherein the photosensitive devices are LEDs.
A colour sensor having a plurality of LEDs each oriented to illuminate a sample to be sensed, from at least two different angles, the sensor further including LEDs arranged to sense light reflected from the sample.
A colour sensor comprising a plurality of LEDs, constructed to provide differing spectral light emissions and each oriented to receive reflected light from a predetermined sensing location.
A method of sensing colour comprising illuminating a sample to be sensed and arranging for at least one LED to receive reflected light from the sample whereby the electrical output of the LED is used to provide an indication of the reflected light energy in the emission band of the LED.
Dependencies are inferred from the claim text.