基于双自由曲面的LED大角度光学透镜设计

针对直下式LED背光源的均匀照明系统,采用双自由曲面组合,设计了一种大角度光学透镜结构。通过近光源面的自由曲面将光发散成的c/cos3(θ)型光场分布,再利用远光源面实现目标面的均匀分布。这样可以在短距离条件下实现大面积的均匀照明,相对于传统的单自由曲面设计,有效地避免了全反射的发生,提高了照明区域的面积。采用光线追迹软件对所设计的结构进行仿真,通过对模拟结果的分析,在灯箱厚度为15mm时,单透镜均匀照明面积可以达到60mm。采用正三角阵列分布,整个目标面均匀度达到87.5%。相对于传统的大功率器件的直下式光源方式,提高了照明的均匀度,同时大大减少了箱体的厚度。

Optical Lens Design of LED Direct Backlight Based on Two Free Surface

An optical lens with big angle is developed for the uniform illumination system of LED direct backlight based on two free surface.The light of LED is firstly diverged by near free surface with the light distribution of c/cos3(θ) type.Then,the uniform illumination of target is achieved by far free surface.With this design,the uniform illumination is achieved on short distance,the angle of total reflection is avoided and the area of lighting is enlarged in compared with the design of single free surface.The structure is simulated by ray tracing software.The triangle LED layout from the result of simulation,the area of LED light reaches 60 mm in diameter on condition of single lens and the target area reaches 87.5% uniform degree with triangle LED layout in only 15 mm height of backlight box.So,in compare with traditional direct structure of high power LED,the uniform degree of lighting is enhanced and the height of back light box is decreased by using the structure of this lens for high power LED.