Research On Design Of LED Automobile Headlamp Optical System

With the rapid development of new energy automotive industry, there has been a huge demand for new energy vehicles to society and the market. As a high ground of new energy, LED is a green light that can reduce the power consumption, it has several advantages such as energy-saving, durability, safety and so on, the free modeling lights also can enrich the whole car. LED illumination has become the development trend of modern automobile headlamp, since the light emitting properties of the LED is completely different from traditional light source, existing lighting system design can not reach the light distribution requirements of national standard, secondary optical design of LED headlamp system is in need. Therefore, research on design of LED headlamp optical system has very important significance.This paper has analyzed and summarized GB 25991-2010 "automotive LED headlamp" national standards, to the high beam system, presented a design method that consists of fresnel collimator lens and micro free-form surface array. Compared with the total reflection lens in the previous research programs, fresnel lense as the collimating system, the light needs to go through a longer optical path before reaching the total reflection surface, therefore, it is more conducive to the premise that the LED is designed as a point light source in the optical design in this paper. In addition, fresnel lens can greatly reduce the size and weight of the optical system, the system is more compact and cost savings. Then the aligned light was distributed to particular region by the micro free-form surface array, the whole high beam system consists of same three modules that arranged in an equilateral triangle, the simulation results shows that the energy utilization of high beam system has been 90.58%, which reached a new height; The low beam system presents a new projection scheme that consists of ellipsoid reflector of mutative focal length, free-form surface lens, shielding plate and reflective surface plate. The ellipsoid reflector of mutative focal length has achieved the distribution that long in the horizontal direction and short in the vertical direction; the shielding plate is designed to be curved to offset the impact of lens distortion, it makes the 15°cutoff line very clear; use the free-form surface lens to control the ray direction to reach the light distribution that expected of low beam system and prevent glare. Optimized the design of reflector through varying the interval of angle, at the same time, reflective surface plate reuse the light blocked by the shielding plate to optimized the light efficiency of the system. The results shows that the light utilization of low-beam system has increased by nearly 8%,reached 84.87%, compared to the traditional projected low-beam system with the highest luminous efficiency, the light utilization of this system has increased by nearly 5%.Both systems have formed the preset light distribution pattern on the receiving screen that 25 m far from the system, the illumination distribution of the test points and areas completely satisfied the requirements of the national standard. The program is proved feasible and effective, which has solved the problems in the traditional design process and improved the energy utilization.