Patent ID: 7766490

Claim:
A projection system for displaying a full color image using only three primary light sources, the system comprising: three light modulators, a first light modulator for modulating light from a first primary light source, a second light modulator for modulating light from a second primary light source, and a third light modulator for modulating light from a third primary light source, each of the light modulators being controlled by at least one processor to simultaneously provide modulated light at primary light pixel locations in a display, there being no additional primary light sources; the first primary light source comprising at least one red light emitting diode (LED) and at least one non-red LED that emits light at a wavelength shorter than red and longer than green, light from the at least one red LED and light from the at least one non-red LED being combined into a single beam; the second primary light source comprising at least one green LED; the third primary light source comprising at least one blue LED; at least one driver for energizing the at least one red LED, the at least one non-red LED, the at least one green LED, and the at least one blue LED; the at least one processor adapted to receive image signals and, in response, control the three light modulators to create a projected image, and control the at least one driver to vary relative brightness levels of the at least one red LED and the at least one non-red LED over a period of time to change a light mixture emitted from the first primary light source, wherein the at least one processor is adapted to dynamically vary the mixture is based on colors in a particular image to be displayed, wherein the at least one processor is adapted to cause the first primary light source to have an increased color component from the at least one red LED when an image to be displayed requires a red component unable to be provided by the at least one non-red LED, and wherein the at least one processor is adapted to cause the first primary light source to have a decreased color component from the at least one red LED when an image to be displayed does not require a red component produced by the at least one red LED, wherein the at least one processor controls the second light modulator to modulate light from the second primary light source and controls the third light modulator to modulate light from the primary light source to compensate for changes in the light mixture emitted from the first primary light source.