An Optimum Design and Fabrication of Focus Lens for High Intensity Light-Emitting Diodes

A maximum output intensity of high-power light-emitting diodes (LEDs) with high-efficiency focus lens is demonstrated. A commercial software package of Trace Pro and one-factor method are used to simulate the focus lens. The optimum parameters of focus-lens design are the radius curvature, cavity depth, and lens height are 2.75, 2.45, and 5.7 mm, respectively. For the fabrication of focus lens with injection molding, the optimum parameters are simulated by adapting Taguchi's method of the smaller-the better algorithm in a software package for Moldex 3D. By employing both optimum design and fabrication of the focus lens, a maximum peak intensity for 64.6 cd for a 1 W blue LED module was realized under a constant driving current of 320 mA and the voltage of 3.2 V. In comparison with a commercial focus lens used in high-power LEDs under the same test conditions, the high-power LEDs with proposed focus lens exhibits about 2-3 times improvement in the output intensity. This study may provide a practical guideline for design and fabrication of a high-efficiency focus lens used in high-intensity high-power LED modules. (C) 2009 The Japan Society of Applied Physics