Abstract：LCD has gradually become the main trend in flat panel display

and its important component BLU(Back Light Unit)

also play an decisive part. Nowadays

new-generation light source LED has been more and more applied in middle-large LCD field

such as LCD-TV

LCD-Exhibit screen

showing a very nice market outlook. This article designs a 46’ direct type BLU for semi-outdoor LCD. Using 0.5W High-Ra LED and without the packaging lens

the optical length can be within 25mm and the centre lightness can get 20000nits above. By optical

drive and thermal design

we got a direct type BLU design with feature of high lightness

nice display quality

good heat dissipation and low-cost

giving strong support to outdoor and semi-outdoor LCD-Exhibit use.