Patent ID: 7960807

Claim:
A light detector to detect light within a first range of wavelengths, comprising: a first sensor including complementary-metal-oxide semiconductor (CMOS) photocells that are covered by a colored filter layer of a first color that has a first transmittance that allows both light within the first range of wavelengths and light outside the first range of wavelengths to pass; and a second sensor including further CMOS photocells, which include both a first group of CMOS photocells and a second group of CMOS photocells, wherein the first group of the CMOS photocells of the second sensor are covered by both a colored filter layer of the first color and a colored filter layer of a second color, stacked one above the other in either order, where the colored filter layer of the second color has a second transmittance that allows at least a first portion of the light outside the first range of wavelengths to pass, and wherein the second group of the CMOS photocells of the second sensor are covered by both a colored filter layer of the first color and a colored filter layer of a third color, stacked one above the other in either order, where the colored filter layer of the third color has a third transmittance that allows at least a second portion of the light outside the first range of wavelengths to pass; and wherein the CMOS photocells of the first sensor are not covered by a colored filter layer of the second color; wherein the CMOS photocells of the first sensor are not covered by a colored filter layer of the third color; wherein the first group of the CMOS photocells of the second sensor are not covered by the colored filter layer of the third color; wherein the second group of the CMOS photocells of the second sensor are not covered by the colored filter layer of the second color; wherein when light both within the first range of wavelengths and outside the first range of wavelengths is incident upon the detector the first sensor, which includes CMOS photocells that are covered by the colored filter layer of the first color, produces a first photocurrent (i 1 ), the first group of the CMOS photocells of the second sensor, which are covered by both the colored filter layer of the first color and the colored filter layer of the second color, produce a second photocurrent (i 2 ), and the second group of the CMOS photocells of the second sensor, which are covered by both the colored filter layer of the first color and the colored filter layer of the third color, produce a third photocurrent (i 3 ); and further comprising circuitry configured to receive the first photocurrent (i 1 ), the second photocurrent (i 2 ) and the third photocurrent (i 3 ), and configured to produce a differential photocurrent indicative of a difference between the first photocurrent and a summation of the second and third photocurrents, wherein the differential photocurrent has a spectral response with at least a majority of the light outside the first range of wavelengths cancelled.