| Summary: | 碩士 === 國立中興大學 === 機械工程學系所 === 104 === Thin-film-transistor liquid-crystal display (TFT-LCD) itself has a thin, light and high brightness and many other advantages, How to get better display, development of high-brightness, high-uniformity, saving and thin backlight system is the goal of many engineers. Because of the cold cathode fluorescent (CCFL) or high-efficiency light-emitting diode (LED) backlight module in the long light-driven state, the temperature of the lamp or LED will affect the micro-optical structures deformation, resulting in uneven brightness and screen display abnormal behavior. Wherein the light guide plate main material is PMMA (Poly-methyl Methacrylate), however, this material is also easily affected by temperature and humidity impact the size variation. Consider the current LCD TV monitors with 42 "TV sales as the main dimensions, this study will be 42 "size light guide plate as the main dimensions.
This study was divided into two parts do investigate, the first part focused on the light guide plate material properties study. Experimentally that, the light guide plate absorption rate and size of the expansion really affected by temperature and humidity, In particular, a greater impact with humidity. Experiments were first guide plate for temperature and humidity to find the coefficient of thermal expansion and water absorption. The second part of the study guide plate PMMA due to heat, moisture expansion strained, to find the corresponding for stress, strain relation between elastic cushioning material (high-density foam), In addition to the light guide plate in the backlight module fixed to the outside position, and can be absorbed by the light guide plate, heat, moisture expansion should be variable, to prevented light guide plate deformation.
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