| Summary: | 碩士 === 南台科技大學 === 光電工程系 === 99 === The main function of optical films of the LCD backlight unit (BLU) is to increase luminance and luminance uniformity. Recently, in order to reduce the cost and thickness of BLUs, the trend for the development of optical films is to combine the functions of light diffusion and brightness enhancement together in an optical film, called multi-functional optical film. In this research, we use the professional optical simulation software, ASAP from Breault Research Organization, to simulate multi-functional optical films. Our purpose is to understand the relationship between structural parameters and intensity gain and haze, and find the optimal structural parameter.
In this research we focus on parabolic and elliptical structures and compare their results with that of hemispherical structure, the main structure employed by the current multi-functional optical films. For the analysis of intensity gain and haze, the effects of structural parameters and surface roughness are studied. Analysis and simulation of haze measurement is based on the standard ASTM-D-1003-07. Finally high performance multi-functional optical films are designed.
According to the simulation results, the factor affecting the intensity gain of parabolic structure is its shape ratio, defined as base radius divided by the absolute value of the radius of curvature, not base radius or radius of curvature itself. The intensity gain is highest when the shape ratio is 2.5. For elliptical structures with half ellipsoid, conic constant is the only structural parameter to affect the optical performance of the optical film, and the intensity gain is highest when the conic constant is -0.25~0. For elliptical structures with their heights shorter than half ellipsoid, conic constant and shape ratio are the structural parameters to affect the optical performance of the optical film.
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