Patent ID: 7431463

Claim:
A projection display system, comprising: a light-recycling illumination system, wherein said light-recycling illumination system further comprises: a plurality of light-emitting diodes, wherein each of said light-emitting diodes emits internally generated light, wherein each of said light-emitting diodes has a first reflecting electrode and a second reflecting electrode that reflect externally incident light, wherein each of said light-emitting diodes has a maximum intrinsic source luminance and wherein the total light-emitting area of said plurality of said light-emitting diodes is area A LED ; a light-recycling cavity, wherein said plurality of said light-emitting diodes is disposed on the inside surfaces of said light-recycling cavity and wherein said light-recycling cavity and said first reflecting electrodes and said second reflecting electrodes of said light-emitting diodes reflect and recycle a portion of said internally generated light back to said light-emitting diodes as said externally incident light, thereby increasing the effective brightness of said light-emitting diodes; and a light output aperture, wherein said light output aperture is located in a surface of said light-recycling cavity, wherein the area of said light output aperture is area A O , wherein said area A O is less than said area A LED , wherein said light-emitting diodes and said light-recycling cavity direct at least a fraction of said internally generated light and said externally incident light out of said light-recycling cavity through said light output aperture and wherein said fraction of said internally generated light and said externally incident light exits said light output aperture as uncollimated light having a maximum exiting luminance; a light-collimating means, wherein said light-collimating means has an input area that is adjacent to said light output aperture that accepts said uncollimated light, wherein said light-collimating means partially collimates said uncollimated light and wherein said light-collimating means has an output area through which the partially collimated light is transmitted; and an imaging light modulator, wherein said imaging light modulator is located in the optical path of said partially collimated light, and wherein said imaging light modulator spatially modulates said partially collimated light to form an image.