LED is a kind of reliable source of LCD backlight. The characteristics of LED determine the color gamut and brightness of LCD TV. At present, the mainstream of white LED mainly uses blue chip coated with YAG phosphor to get white light, which can only guarantee the color gamut to 72%NTSC. Based on the color characteristics of backlight module, the method of calculating the color gamut of backlight module are introduced in detail. Coating blue chip by different kind of phosphors, a new LED backlight for LCD TV is developed. The color gamut is improved to more than 80%NTSC or more. At the same time, through the optimization of combination of blue chip with selected green phosphor and red phosphor excitation peak, this white LED solution can get the different color gamut and the highest color gamut, which will be 88%NTSC at most. This technique has been applied to a LCD TV.
A High Luminance White Light source for Etendue limited application has been demonstrated in this research paper by using blue InGaN laser diode beam over static source of phosphor Ce: YAG layer. Phosphor target has kept static because moving phosphor target light output is not constant and uniform. Different color temperatures had been obtained by varying phosphor concentration and thickness of the layer. When laser beam has focused on phosphor target spot, it induced very high temperature at that spot area. Temperature induced in the layer by laser beam depends on the layer thickness. All the layer thickness, surface temperature, output light flux, efficiency, and light color temperature are interrelate with each other. Uniform laser beam distribution, surface temperature, laser spot size, phosphor layer thickness are successfully calculated. Luminous efficiency, light color temperature, flux, wavelength spectrum, and light output power of laser driven white light source had been successfully observed at different laser beam powers.
Holographic stereogram receives much attention in autostereoscopic display with large scale and wide field of view (FOV). However, its property of FOV is constantly restricted by optical elements used in recording step. After analyzing drawbacks of the available methods nowadays, a novel method of edge-in reflection optical element for overlay projection is proposed. The feasibility is confirmed by optical simulation. And property of manufactured reflection surface has also been tested. Then it’s been used to generate horizontal-parallax-only stereogram. The final holographic stereogram with 73 degree viewing angel range is acquired.
We propose a molecular dynamics method incorporating a variable radius technique to generate the dot patterns printed on the bottom surface of the light guide plate for the large scale edge-lit light-emitting diode (LED) backlight unit. In addition, this method is also incorporated with the cell division technique and r-cut technique to help reduce the computational time for optimization. The process, including adjustment in the dot radius according to the feedback from an illuminance result of the optical software, which compares to the other methods, can reduce the time for computation and the process can be incorporated into an optical design phase quite easily. By employing the above method, the time for obtaining a random dot distribution for a 42-in. LED backlight with a thickness of 4 mm and uniform illuminance of 80%, is significantly shortened.
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