The Design Of Optics And Cut-off Line Gradient Based On LED Automotive Headlamp

With the development of social economy,automobile cars have become an indispensable transportation in human society.As Automobile lighting system have the lighting and signal Indication functions,it is an important part of automobile safety.The headlamp provides far and near lighting.In order to provide enough illumination for the specified areas and avoid vertigo for opposite driver because of significant variation of lamp brightness,strict and mandatory standards were put forward for the high beam and low beam by the lamp industry of automobile cars.Based on the requirements of regulations,an optical system was designed,which meets the optical standard and brightness Cut-off line requirements.The system can provide good visual scope for driver and avoid vertigo for opposite driver.The driving security was improved effectively.The main research contents in this article were summarized as follows:1.The optical requirements of LED high beam and low beam in GB 25991 and brightness cut-off line in ECE R112 were introduced.Two kinds of common optical systems in LED Headlamp were illustrated.2.Based on the basic theory of optical design,the optical surfaces were separated and the model of optical system was built by CATIA software.The design of optical surfaces for KINK,BASE low beam and high beam were finished by Lucid Shape software.3.The optical surfaces were tested by OPTRONIK SMS 10 C optical checking equipment.Test Result showed all the luminance values of measurement points were within the limits required by the GB 25991.It verified the rationalization of the design of optical surfaces.4.In order to improve vertigo problem,the effect of focal length on the gradient was researched by simulation.The result shows,when the focal length f=17 mm for the Low Beam KINK reflector,the gradient of Cut-off line was maximum,the Cut-off line was most distinct and the value was in the required range of ECE R112.It is more beneficial for safe driving.5.The simple and convenient adjective structure was designed.The gradient of low beam cut-off line was measured by OPTRONIK SMS 10 C optical checking equipment.The maximal gradient value was 0.34;the minimum gradient value was 0.22.All the values of measurement points were within the limits from 0.13 to 0.4.It met the requirement of ECE R112 and verified the feasibility of the design of brightness cut-off line.