BRIEF DESCRIPTION OF THE DRAWINGS
The structure, operation, and methodology of the invention, together with other objects and advantages thereof, may best be understood by reading the following detailed description in connection with the drawings in which each part has an assigned numeral or label that identifies it wherever it appears in the various drawings and wherein:
FIG. 1 is a diagrammatic plan view showing a 3-color LED projection light source acting as the input to a lens system that relays the LED light to the plane of a digital imaging device such as a Digital Micromirror Device (DMD) that, in turn, produces an image through a projection lens onto a video screen;
FIG. 2 is an enlarged diagrammmatic perspective view of the LED projection light source of FIG. 1 shown in more detail 3 rectangular compound parabolic concentrators (CPCs), a waveguiding X-Cube, and a mixing pipe;
FIG. 3 is a diagrammatic perspective view showing a single rectangular CPC used in the light source of FIG. 2 to provide light at equal output angles;
FIG. 4 is a diagrammatic plan view showing a raytrace of the system of FIG. 2 for the straight through case;
FIG. 5 is a diagrammatic plan view showing a raytrace of the system of FIG. 2 for one of the orthogonal cases;
FIG. 6 is an exploded diagrammatic perspective view showing the system of FIG. 2 interfaced to heat sinking and packaged;
FIG. 7 is a diagrammatic perspective view of a hollow rectangular CPC and a section view thereof;
FIG. 8A is a three-dimensional plot showing the near field intensity distribution of the rectangular CPC of FIG. 3;
FIG. 8B is a two-dimensional plot showing the variation of intensity taken along orthogonal axes in FIG. 8A;
FIGS. 9A and 9B are two dimensional topographical plots of the far field intensity distribution of the CPC of FIG. 3;
FIG. 10A is an isometric view of a rectangular CPC having an asymmetric far field;
FIG. 10B is an Iso Candela plot of the rectangular far field of the CPC of FIG. 10A;
FIGS. 11A and 11B are diagrammatic perspective views comparing, respectively, a full rectangular CPC with a theta by theta rectangular CPC, which collects less than the full angular distribution of a Lambertian source of increased dimension;
FIG. 12 is a straight tapered concentrator for the purpose of comparing the performance to the rectangular CPC of FIG. 3;
FIGS. 13A and 13B show the far field distribution of the tapered concentrator of FIG. 12;
FIG. 14 is a diagrammatic perspective view of alternative embodiment of the invention that may be used as the LED source of FIG. 2;
FIGS. 15A and 15B show diagrammatic isometric and cross sectional views, respectively, of an LED die with a thin conformal encapsulant for the purpose of extracting more LED light;
FIGS. 16A and 16B are diagrammatic perspective views showing rectangular CPCs designed from more than two CPC curves for the purpose of obtaining a substantially circular far field while maintaining a rectangular near field;
FIG. 17A is a diagrammatic perspective view showing the CPC of FIG. 11B with an input extension of rectangular cross section for the purpose of providing improved uniformity;
FIG. 17B is a ray trace through the extended CPC of FIG. 17A;
FIG. 18 is a plot of the total integrated power for a Lambertian source as a function of the collection angle;
FIG. 19 is a plot showing the increase in luminous emittance for constant étendue as a function of collection angle and also indicates the associated increase in drive power to the LED;
FIG. 20 is a diagrammatic plan view of an X-Cube beam coupling system for producing a white light output;
FIG. 21 is a diagrammatic plan view of an X-Plate beam coupling system for producing a white light output;
FIG. 22 is a diagrammatic plan view of a beam coupling system using 2 standard dichroic beam splitters in conjunction with RGB sources to generate a white light output;
FIG. 23 is a diagrammatic plan view of a transmission grating coupler for an RGB LED projection source;
FIGS. 24A and 24B are diagrammatic views showing a piezo electric actuated total internal reflection active beam splitter for coupling two independent beams;
FIGS. 25A, 25B, and 25C are diagrammatic views showing a piezo electric actuated total internal reflection active beam splitter for coupling three independent beam paths, for example red, green, and blue light;
FIG. 26 is a diagrammatic view of a galvanometric actuated mirror for color sequential coupling of two or more color LED source beams;
FIG. 27 is a diagrammatic view of a servo motor actuated beam coupling system that allows the LEDs to lie in the same plane for simplified cooling geometry;
FIG. 28 is a diagrammatic elevational view of an LED package which incorporates one or more layers of thermal impedance material between the LED die and the metal substrate;
FIG. 29 shows a diagrammatic exploded perspective view of the layers of an LED board design which allows the LED die to be attached directly to the metal substrate for improved thermal performance;
FIG. 30 is a plot of optical output versus electrical input to an LED indicating the benefit of attaching the LED die directly to a metal substrate;
FIG. 31 is a plot of the 1931 CIE Chromaticity diagram showing the color gamut of an LED based projection system relative to the NTSC standard;
FIG. 32 is a spectral plot of blue, green, and red LED die used in an LED projection system;
FIG. 33 is the photopic response of the human eye; and
FIG. 34 is a plot indicating the differences between blue, green, and red LED die with respect to thermal coefficients.
Patent Application
20070206390
