Optical Design Of LED-based Automotive Headlamps

Benefited from the flourishing development of semiconductor & automobile industry, much attention is being paid to the LED's application in automobiles, research on LED-based automotive headlamp has particularly become a hotspot. In terms of being utilized as light source of automotive headlamp, LED certainly owns greater advantages over the traditional HID, halogen and incandescent lamps etc. LED is of smaller size, longer lifetime, less energy-consumption, shorter response time, zero pollution, which contribute to streamline the automobile profile, lower the cost, provide safer drive and promote sustainable development. Additionally, LED is now undergoing price decrease and luminous efficiency increase, providing itself with more potential in automotive front lighting. Although LED is of tremendous benefit, optical design of LED-based automotive headlamp still faces great challenge. For the unique photometric characteristics of LED, we need to redesign its automotive optical system, thus exploratory study on optical design of LED-based automotive headlamp is conducted in this paper, which can be listed as follows:First mainly investigate the component, development history and current research status of LED headlamps; simply compare the world's two main automotive regulations, namely SAE and ECE standard; specifically study the requirements for LED headlamps stated in GB25991-2010. Vertical and horizontal spread angle of low beam are calculated according to GB25991-2010, so does the minimum size of automotive optical system.Then ray-tracing procedure, Monte Carlo simulation and computer modeling of multi-reflector in Lucidshape are investigated. Based on LE UW U1A4 01 LED, two multi-reflectors are respectively designed via Lucidshape to implement the low- and high-beam function, required low- and high-beam distribution are generated, optical collection efficiency for low- and high-beam are 76.3% and 86.9%, size of both optical system is found to be 72 mm ? 45 mm.Next LED high-beam headlamps based on TIR(Total Internal Reflection) lens array are designed. Initially calculate the TIR profile via numerical computation based on vector formulations of reflection and refraction, then sweep the profile into TIR lens by using Solidworks. After that, separately design a 3 ? 4 TIR lens array with 1 ? 1mm lambertian LED and a 4 ? 5 TIR lens array with Cree XLamp XPE LED(d=3.5mm) to realize high-beam illumination, Tracepro simulation results are in line with the requirements stated in GB25991-2010, optical efficiency for each become 90.6% and 89.7%. Finally attempt to realize low-beam illumination with TIR lens but failed.