Patent ID: 8496367

Claim:
A novel LED based color-pixel backlight system, with suppression of color mixing, for color filter-less liquid crystal display, comprising: a light guide, having four edges and two broad surfaces, with at least one edge transmitting UV or NUV rays and assembled with a multiplicity of UV or NUV emitting LEDs and the other three edges, opposite to and adjacent to the transmitting edge, coated with reflector, reflecting UV, NUV and visible rays, with its bottom broad surface coated with UV, NUV and visible light reflecting mirror and its top broad surface roughened through etching or other means to create pixelated square patterns for extracting UV or NUV light from the light guide; said light guide having its top broad surface coated with two layers one over the other, comprising a reflective layer at the bottom and a black layer at the top of the reflective layer; said two layers being coated everywhere except in the pixelated areas; means for connecting said UV or NUV LEDs to electrical power to emit UV or NUV radiation; said etched square patterns containing aluminum islands with a coating of phosphor layers on top of aluminum islands and the phosphor layers having a protective coating on their top surface; said aluminum islands reflecting the visible light generated within the pixel and suppressing the different color of visible light, other than the color of light generated within the pixel, entering the pixel either directly from adjacent pixels or through multiple reflections at the internal surfaces of the light guide from other pixels; said aluminum islands having sufficient space between them allowing sufficient UV or NUV rays entering the pixel; said phosphor layers containing red, blue and green phosphors that convert the UV or NUV rays incident on them in to visible red, blue and green colors of light, with pixel patterns, that travel upward towards a sheet of micro-lens; said sheet of micro-lens, said etched pattern on the surface of the light guide and the color filter-less LCD, are all assembled such that the said sheet of micro-lens, said etched pattern on the surface of the light guide and the LCD are kept substantially in alignment to provide color pixel backlighting to the said color filter-less LCD.