White light backlights and the like with efficient utilization of colored led sources

A white light backlight having an output illumination area, comprising:

• a plurality of colored light sources disposed to emit light into the output illumination area;
• and
• a drive circuit connected to the plurality of colored light sources;
• wherein the plurality of colored light sources have a first number n1 of first LED light sources, a second number n2 of second LED light sources, and a third number n3 of third LED light sources, the first, second, and third LED light sources (i) emitting light of a first, second, and third color respectively, the first, second, and third colors being non-white and substantially different from each other, and (ii) having first, second, and third maximum drive characteristics, respectively, with corresponding first, second, and third maximum output characteristics;
• wherein the circuit is configured to drive the first LED light sources within 10% of the first maximum drive characteristic, and drive the second LED light sources within 10% of the second maximum drive characteristic, and drive the third LED light sources within 10% of the third maximum drive characteristic;
• and
• wherein n1, n2, and n3 are selected so that light from the energized first, second, and third LED light sources, when combined, is substantially white.