5.3: A New Cost‐Effective Optical Plate for High Performance LCD‐TVs

objective of the research presented in this paper is to design a highly efficient LCD-TV backlight unit (BLU) which minimizes lamp count without light leakage from the BLU. A new optical plate helps to successfully distribute spatial luminance in a 46inch LCD-BLU consisting of only 20 CCFLs. 1. Introduction There is no doubt that demand for large panel LCD-TVs is growing rapidly; however, excessive supply has caused pricing pressure on the panel suppliers. The price of large size panels and BLU components are also continuing to fall. As a result, it is desirable to reduce the number of optical elements by combining components within the BLU to cut cost of the backlighting system, which accounts for nearly half of the total cost of an LCD-TV module. The BLU system has several components including light sources such as CCFLs, electrical circuits such as inverters, optical elements, and mechanical structures including a diffuser plate, diffuser films, brightness enhancement film (BEF), dual brightness enhancement film (DBEF), chassis, mold frames, and so on. The CCFLs and their attached components, including inverters and connectors, are important key cost elements in large size BLUs (1). For competitive pricing of LCD TV, it is obvious that any unnecessary components should be removed or combined, for example the BEF and DBEF in the BLU. However, it has not been possible to reduce the number of CCFLs in large sized BLUs considering the lamp image can be detected if the current module structure's dimension is maintained while decreasing the number of light sources. Therefore we must determine what functions are necessary to reduce the quantity of CCFLs without changing current mechanical dimensions of the BLU, yet maintaining luminance levels over 500 cd/m 2 (nits). To solve these problems, the following issues should be considered: First, screening of light leakage from CCFLs even though the lamp pitch increases with reduction in the total number of CCFLs. Second is to increase relative luminance even though the total power of the light source has been decreased. For this, we have focused on development of a new concept of a light diffusing plate using practical simulator analysis. The goal of developing the transparent plate is to design the new optical pattern on the surface of the plate. Spatial luminance emitted from the newly developed pattern plate normally stays in the range of less than 10% of luminance fluctuation and converges at the center of the module without assistance from other films. In this way, the new plate, which we call "Lentix", provides BEF-like functionality. It is able to eliminate BEF-type film from the BLU's optical system and can maintain luminance over 500nits.