Brightness enhancement film (BEF) has been manufactured in foreign factories for backlight module of liquid crystal display (LCD), then it only have some interior factories to put in exploitation. Because of this, the study presents a precision machining and new step-imprint hot embossing process to fabricate pyramid-shaped microlens array. First, a tungsten (W) steel material is manufactured by precision machining. The dimension of a pyramid-shaped microlens on the W steel are about 300 £gm in the base line of three side, 222 £gm in bevel edge of three side, 139 £gm in height of bottom to top, 180 £gm in pitch of the left and right sides between two pyramid-shaped microlens tips, and 85 degree in top angle of three bevel. The W steel mold is used as the first mold. Second, the pyramid peaks of first mold pattern are transferred on bulk metallic glass (BMG) using step-imprint hot embossing method with position adjustable mechanism to form a smaller concave pyramid-shaped microlens array, it can avoid arc radius of cutting tools which is used as the second mold. Another the pyramid peaks are transferred on PMMA (Polymethylmethacrylate) for concave pyramid-shaped microlens array of optical film in the hot embossing system. Finally, the second mold is fabricated to emboss convex pyramid-shaped microlens array of optical film on PMMA. The foregoing method is provided for backlight module of optical films process.

In this paper, we searched the parameter of BEF (Brightness enhancement film) using commercial FRED server for backlight module. The pattern analysis was carried out to understand its characteristic. The current structures used in LCD backlight are double-layer BEF. In addition, BEF of 3M takes the lion¡¦s share. But this may increase the thickness and cost of backlight module. In order to avoid those disadvantages, we tried to design single-layer BEF and characterize the effect through parameters study by using FRED software simulation. pyramid-shaped microlens array of BEF was constructed. Therefore, the effect of the variation of the structure parameters can be analyzed, such as prismatic degree (£c), prismatic structure on the brightness enhancement. It can be found from the result of simulation that the changes of the prismatic degree (£c) of 85 degree influence the brightness enhancement the most.