Optimization of LED assembly for LCD backlight using photo-electro-thermal modeling and simulation

With the continuous size increase of LCD (Liquid Crystal Display) screens, backlight applications have to keep up with the demand for higher luminous intensity. High quality applications demand uniform light distribution over the visible screen surface. This paper presents a design and optimization method for LED backlight assemblies with the goal of improving luminous intensity uniformity on LCDs in high-demand applications. Our approach is to eliminate the need for custom made diffusers and PCB redesign by a more detailed evaluation on the LED behavior in the first design stages of the backlight assembly. This approach implies defining a photo-electrothermal simulation model that can accurately predict luminous intensity based on electrical and thermal conditions. The multidomain parameter interactions are considered in a composite SPICE model. The results of the optimization process are translated in to layout design directives and verified using FEM simulations.