Planar apparatus for uniformly emitting light with angular color-separation

Abstract

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.

Integrating Backlight With Color-Filter-Free Panel for Enhancing Performance of LCD

“…Moreover, they are not suitable for the broadband light source because the grating is very sensitive to wavelengths of the incident light. The approaches involved with geometrical optics use the geometric optical element such as a huge lenticular lens, a wedge-shaped light-guide plate (LGP) with a spherical thick end, or three independent collimating elements, to produce the required angularly separated collimated primaries that then focus onto the corresponding subpixels through a lenticular lens array [26]- [28]. Another approach applied in a direct-lit backlight is using a lenticular lens array with grouped lens elements to focus the linear light sources of the three primaries onto the corresponding subpixels directly [29].…”