Planar apparatus for uniformly emitting light with angular color-separation

This study proposes a slim planar apparatus that can function as a color-separation backlight for the color-filter-free liquid-crystal display (LCD) system. It has a two-level folded configuration comprising a composite light-guide plate (LGP) and light-emitting diode (LED) couplers. The LED couplers generate the highly collimated beams of the three primaries (R, G, and B) that enter the composite LGP at their separate angles; then the three primaries were uniformly extracted out of the top surface of the LGP at their respective angles differing in the longitudinal direction. In the simulation, a lenticular lens array was used to focus the three primaries onto their respective subpixels; each pixel of the LC panel comprised three subpixels, identical to the traditional layout. The proposed apparatus can be applied in backlight modules with a maximal diagonal dimension of 39 inches and a thickness of 15.5 mm. The simulation results indicated that the spatial uniformities of the three primaries ranged between 84% and 87%, the area of the color gamut of the LCD system was 99.5% of that defined by the National Television System Committee, and the total optical efficiency was 41%, as the double of a traditional LCD system. Thus, the proposed apparatus improved the total optical efficiency markedly and provided the LCD system with a wide color gamut.