Illumination system and display system employing same
View Patent ↗A compact, light weight, efficient and cost-effective illumination system for optical displays is disclosed. The illumination system is capable of producing a self-luminous light beam of selected cross-section and spatial distribution in terms of intensity and angle. The illumination system can efficiently couple light from light sources having wide variety of sizes and shapes into light valves of various shapes and sizes. The illumination system includes a light recovery system or a polarization conversion system or a suitable combination of the foregoing.
1. An illumination system for use in optical display systems, comprising:
a light guide having two ends;
a reflective plate mated to one end of the light guide, the reflective plate having a reflective surface with a transparent aperture formed therein for admitting input light from a light source into the light guide; and
a micro-guide plate mated to the other end of the light guide, the micro-guide plate including one or more optical elements formed and positioned in a predetermined arrangement on at least one surface of the micro-guide plate for altering at least one optical characteristic of the input light, wherein the micro-guide plate includes:
a first plate mated to the light guide, the first plate having a reflective surface with a plurality of transparent apertures formed therein; and
a second plate including the optical elements, each of the optical elements being mated to one of the apertures in the reflective surface.
2. The illumination system of claim 1 , further comprising a reflective coating applied to sidewalls of the optical elements.
3. The illumination system of claim 1 , wherein the optical elements are placed in a predetermined arrangement to compensate for optical aberrations selected from the group consisting of Keystone distortion, illumination overfill, illumination drop-off and any combination of the foregoing.
4. The illumination system of claim 1 , wherein the micro-guide plate includes at least one million optical elements.
5. The illumination system of claim 1 , wherein optical elements include optical elements selected from the group consisting of apertures in a reflective coating, micro-guides, light guides, tunnels, lenses, prisms and any suitable combination of the foregoing optical elements.
6. The illumination system of claim 1 , further comprising a reflective coating covering surface area of the micro-guide plate between adjacent optical elements.
7. The illumination system of claim 1 , further comprising a polarizing unit at the exit face of the micro-guide plate, wherein the polarizing unit passes light with a predetermined polarization state and reflects the remaining light back toward the light guide.
8. The illumination system of claim 7 , wherein the polarizing unit comprises a reflective polarizer, two polarization beam splitters, or a mirror and a polarization beam splitter.
9. The illumination system of claim 1 , further comprising a quarter-wave plate and a polarizing unit;
wherein the polarizing unit is located at the exit face of the system and passes light with a predetermined polarization state and reflects the remaining light back toward the light guide; and
wherein the quarter-wave plate is located after the exit face of the reflective plate and before the entrance face of the polarizing unit.
10. The illumination system of claim 9 , wherein the polarizing unit comprises a reflective polarizer, two polarization beam splitters, or a mirror and a polarization beam splitter.
11. The illumination system of claim 1 , wherein the reflective plate comprises at least one optical element formed and positioned in a predetermined arrangement on at least one surface of the reflective plate.
12. An illumination system for use in optical display systems, comprising:
a light guide having two ends;
a reflective plate mated to one end of the light guide, the reflective plate having a reflective surface with a transparent aperture formed therein for admitting input light from a light source into the light guide; and
a micro-guide plate mated to the other end of the light guide, the micro-guide plate including one or more optical elements formed and positioned in a predetermined arrangement on at least one surface of the micro-guide plate for altering at least one optical characteristic of the input light, wherein each of the optical elements of the micro-guide plate comprises an entrance aperture, an exit aperture away from and parallel to the entrance aperture, at least one sidewall connecting the entrance and exit apertures and a reflective coating on the at least one sidewall.
13. The illumination system of claim 12 , wherein the optical elements include at least one hollow micro-guide comprising an entrance aperture, an exit aperture away from and parallel to the entrance aperture, at least one sidewall connecting the entrance and exit apertures and a reflective coating on the at least one sidewall.
14. The illumination system of claim 12 , further comprising a reflective coating covering surface area of the micro-guide plate between adjacent optical elements.
15. The illumination system of claim 12 , further comprising a polarizing unit at the exit face of the micro-guide plate, wherein the polarizing unit passes light with a predetermined polarization state and reflects the remaining light back toward the light guide.
16. The illumination system of claim 15 , wherein the polarizing unit comprises a reflective polarizer, two polarization beam splitters, or a mirror and a polarization beam splitter.
17. The illumination system of claim 12 , further comprising a quarter-wave plate and a polarizing unit;
wherein the polarizing unit is located at the exit face of the system and passes light with a predetermined polarization state and reflects the remaining light back toward the light guide; and
wherein the quarter-wave plate is located after the exit face of the reflective plate and before the entrance face of the polarizing unit.
18. The illumination system of claim 17 , wherein the polarizing unit comprises a reflective polarizer, two polarization beam splitters, or a mirror and a polarization beam splitter.
19. A method of operating an illumination system, comprising:
receiving input light at a reflective plate mated to one end of a light guide, the reflective plate having a reflective surface with a transparent aperture formed therein;
admitting a portion of the input light through the transparent aperture into the light guide;
outputting the admitted input light from an exit end of the light guide into a micro-guide plate having a plurality of optical elements formed and positioned in a predetermined arrangement on at least one surface of the micro-guide plate, wherein each of the optical elements of the micro-guide plate comprises an entrance aperture, an exit aperture away from and parallel to the entrance aperture, at least one sidewall connecting the entrance and exit apertures and a reflective coating on the at least one sidewall; and
the optical elements altering at least one optical characteristic of the light output from the light guide.
20. The method of claim 19 , further comprising:
blocking a portion of the light output from the light guide with a reflective coating applied to a surface of the micro-guide plate.