Key Technology Research On Direct-lit LED Backlight Module

Direct-lit LED backlight is widely used in LCD TVs, flat light, advertising light boxes, signs, and other fields. High-performance direct-lit LED backlight technology is not yet fully mature, issues like how to improve the performance of LED backlight to achieve the light mixing distance to further reduce, and increase the brightness uniformity of the backlight are very crucial. It is great significant to study the related methods. This paper mainly focuses on the issues of dual-chip LED package and the design and optimization of backlight lens. Works in the research are as follows:(1) Analyzed and tested the steady-state thermal properties of the single-chip and the dual-chip 2835 backlit LED source devices, the results show that the dual-chip LED package of 2835 has better thermal properties.(2) Studied the effects of the chip gap in the dual-chip 2835 light beads on the thermal properties, the results show that a best thermal performance can be made by controlling the chip gap of dual-chip LED.(3) Simulation analysis for carrying out the variation of the phosphor characteristic parameter to the color of single-chip and dual-chip 2835 show that to obtain the same color of single-chip LED, dual-chip LED need to increase the particle size or concentration of phosphor.(4) Studied the effects of the chip gap in the dual-chip 2835 on flux values of light beads, the results show that a maximum flux value can be made by controlling the chip gap of dual-chip LED.(5) Based on the theory of non-imaging marginal rays and shearing method of free-form surfaces, designed and optimized a reflex type backlit lens with the mixing distance of 20mm; Based on the nine-point test method, used the surface imaging colorimeter to test the optical performance of the 32 inch backlit modules by using the lens previously mentioned. The results show that the back-lit lens can basically meet the requirements.(6) Designed lens to achieve uniform rectangular spot on the receiving surface. With uniform illumination of circular spots on the receiving surface which formed by multiple sets of curves corresponding rotation asymmetric lens as the optimize goals, the traditional design method requires optimization of a large number of discrete points is converted to the optimization of multiple sets of curve. To some extent, using this method overcomes the problem of the conventional methods are difficult to achieve optimization.