1 Introduction
With the rapid development of the automotive industry and the continuous improvement of LED light efficiency [1], the application of LED in automobiles is becoming more and more popular. At present, almost all car manufacturers using LEDs in the whole car are European companies, which are used in external lighting. In terms of LEDs, European and Japanese cars have changed the ratio of third brake lights to LEDs by more than 80%. Compared with foreign countries, domestic automotive application LEDs have to lag several years. From the development status and trend of LED lamp technology, China's LED high-position brake lamps have begun to spread further, and LED rear brake lights, turn signals and fog lamps have begun to be commercialized. LED car lamps are developing in the direction of personalization and art.
At present, the key research direction of LED automotive lamps is LED headlamps, among which high-efficiency, high-power, high-reliability LED component research, lamp and special heat dissipation technology and optical design are the key [2]. In this paper, the optical structure design of high-power LED automotive headlamps is studied. The optical model of the headlamps is established by ASAP[3] software. The multi-light group single lamp and combined light distribution analysis are carried out.
2 LED light source
After trial and error, it was found that the LED packaged in the multi-chip linear package is the best source for the headlamps. Because it is similar to the filament, we use 5 single 1 watt LED chips, which are linearly packaged in series on one substrate. Become an LED. The chip package arrangement length is 5.5mm. The spectral characteristics and radiation distribution of the encapsulated LED source are shown in Figures 1 and 2.
3 LED automotive headlamp optical design
3.1 High beam design
In order to overcome the difficulty that the existing automobile lamps can not directly replace the light source with the LED light source, the high beam and the position light are combined to save space and meet the luminous flux requirements of the high beam, and can achieve higher effectiveness.
The method adopted in the design is: combining the high beam and the position lamp in the same lamp room, the position lamp is composed of 8 LEDs, each LED is equipped with an independent reflective bowl, and the position lamp meets the light distribution requirement through reflection and direct light. . The position lamp is placed under the heat sink of the high beam LED. The light source of the high beam is a multi-chip package high-power LED, which adopts the side light-emitting method. The light source is reflected by the free-form surface, and all the light is reflected and concentrated to achieve the high-beam light distribution requirement.
3 is a mechanical structure diagram of a high beam lamp, in which 1 is a frame, 2 is a high beam reflection surface, 3 is a front position light reflection surface, 4 is a position light LED, 5 is a high beam heat sink, and 6 is a multi-chip large Power LED.
