Development of the novel backlight unit for the liquid crystal display

Abstract

Since the technology of liquid crystal display was developed, the demands to the liquid crystal panel which is thinner, and cheaper in low cost, have been increased. One of the challenges is to implement the thin backlight unit with good optical characteristics using the micro-pattern. The previous works satisfy the needs, but they are still expensive to fabricate. In this thesis, we proposed a new backlight unit to fulfill the mentioned demands and developed the fabrication technology of the component of a new backlight unit in a low cost. The proposed structure is made of two components, a light-guide plate with microlens array, and a conical microlens array sheet. In this backlight unit, the number of optical sheets is decreased. Therefore, the optical characteristics of the proposed backlight unit were expected to improve. According to concept of each sheet, the microlens array makes to advance the viewing angle, and the slanted angle of conical microlens array calibrates the optical characteristics. Among the various methods of the microlens fabrication technology, the diffuser lithography was used. The 3D diffuser lithography could be performed simply by putting on the diffuser on the photo mask. The diffuser randomized the direction of the collimated UV light, and the exposed region was formed the rounded cross-section. The shape and the size of were well controlled by kind of diffuser, UV exposure dose, and the pattern of the mask. Therefore the diverse applications of 3D diffuser lithography were investigated. Also, using this method, the microlens array mold for proposed unit was fabricated. The fabrication technology for conical microlens array was developed. Using the method, a proximity lithography, to make a slanted structure, the conical microlens array which was formed the cone, was fabricated. The proximity lithography could be implemented by making a gap between the photo mask and the photoresist. The gap diffracted the collimated ...