Design Of New LED Car Headlamp Optical System

Double beam system of vehicle headlamp with one lens to control both high beam and low beam is widely used on premium automobiles. The system with a compact structure can not only achieve the goal to switch low beam and high beam freely, but also available for AFS system. Since this structure use baffle to achieve the switch of low beam and high beam, a great number of lights have lost, and the luminous efficiency is only about 30%. In order to enhance the efficiency, it is need to optimize the design. In addition, HID source is usually used as the light source of double beam system, if using energy-efficient LED source to replace HID. the advantage of both double beam system and LED can be combined.The main work of this paper is using LED as the light source of double beam system to achieve the lighting requirement of GB25991-2010"LED headlamp". Two light source module is used to switch low beam and high beam which can avoid the loss of light energy.Firstly, the model of projective high beam system includes parabolic reflector and rotational symmetric freeform lens is built. Through analyzing every parameter that can affect the result of light distribution, the optimized model of projective high beam system is objected. Then, based on the optimized model of projective high beam system, double beam system is designed. According to the design method of non-rotational symmetric freeform surface, the lens of low beam part is designed. Based on the area division in standard, then using the law of conservation of energy and Snelll’s law, the coordinate relations on the freeform lens are obtained from building the coordinate relations among emitting angle, freeform lens and the receiving screen. MATLAB software is used to get the discrete points on the surface of freeform lens. Solidworks software is used to fit the points from MATLAB and build the entity model. Based on the design method of freeform lens in projective high beam system, the lens of high beam part is designed. Finally, Tracepro software is used to analyze the result of the model.The result shows that the generated light type and luminance distribution of both high beam and low beam can meet the requirement of standard. When producing low beam, the cut-off line on HV-H1-H2-H4 is generated.