Advantages and restrictive factors of LED headlamp application

LED headlamp after verification technology in recent years, the concept car exhibition finally ushered in the development stage, is expected to be applied to the production car market prospects, the landmark event three: TOYOTA's Lexus LS600h is the world's first use of LED headlamp light source listed car, it is not only in the on the application of the LED, is still a remote light source halogen lamp. Audi R8 with full LED headlamps as its main features, and automotive lighting LED is used by Lumileds and OSRAM. Cadillac EscaladePlatinum platinum SUV, is the first use of LED headlamp suv. Hinder the rapid development of LED light vehicle market adverse factors

Does the milestone event mean that the LED headlights will be the dominant technology in the field of car light? According to experts predict: perhaps not. Because even the cost of LED according to the rate predicted by Moore's law continued to decline, it is lower to HID (high intensity discharge) the same price match also are years of xenon lamp; and the LED family to cost down to be able to be roughly the same with the halogen lamp, need time course after a period of prolonged.

According to HELla (Hella) CEO Fischer LED said the vehicle currently accounts for only a small share of the scale of the source market of a few percent, so to mass models (Malibu models such as Chevrolet models such as GM/ Department) the matching supply of great interest. But LED wants to reach the bulk of the supply to Malibu models, still need to overcome a series of technical and cost problems, at least ten years to go.

Visteon pointed out that the pace of the LED market is indeed slower than originally expected, we had predicted in 2004: LED lights will soon blow into the market, and the HID out. Obviously, the current situation is not the case, although the LED technology has been expected to evolve faster than the reality. It appears that the high cost of LED is not the only factor to hinder the market, there are still challenges in terms of technical performance needs to be overcome. For example, a single light source, LED light intensity is still insufficient. The single point is difficult to reach the light is not wishful thinking: cut the number of light sources LED combination lamp will help narrow the automobile occupied space and easy and flexible layout, and can simplify the wiring and installation of lighting system and reduce the production cost.

The current mainstream status of LED supply chain: LED light source element Hella general Cadillac Escalade models is supplied to OSRAM (Osram) procurement; and Koito automotive lamp (Koito) light source products LED Nichia company, and then matched with the TOYOTA LS600h models; PHILPS Lumileds LED AL (automotive lighting supply source) company, then the latter for the Audi R8 headlight configuration system. According to the European and American business manager Koito said, they will not be restricted and self defined types of procurement and manufacturers of the light source, no matter who (produced from PHILPS, OSRAM, TOYOTA or Gosei) can be bought. Obviously, a lighting system components suppliers are trying to keep their own procurement source components flexibility, want to take the opportunity to look at: which light source device vendors can progress the fastest, highest price.

Today's LED batch of goods for photoelectric conversion (light energy density) index reached 80 lumens per watt (80lm/W) or more, while the HID lamp is 90lm/W, halogen lamp is 201m/W. According to the Index Research Bulletin: Hella the latest prototype of LED has reached 161lm/W. Hella also forecast: in the next 3-5 years, the light intensity will be LED from the same chip power consumption increased by 50%. This not only means that LED lamps will be more bright, but also reflects the reduction of its energy consumption, thereby improving the fuel economy of the vehicle.

It is estimated that the use of LED to replace halogen lamps can improve the vehicle's mpg (the number of miles per gallon of fuel) index of about 0.25. While the implementation of the law during the day to turn on the lights in Europe, but also to enhance the value of the mpg to 0.5. Lexus models manager pointed out, has a great contribution to improve the application of LED lamps will be on the fuel economy.

However, the higher the intensity of the LED is to emit more heat, and the compact arrangement of the lamp makes the area of heat dissipation smaller. The heating of low energy LED devices indeed belonging to a semiconductor category of less than HID or halogen lamps, but most of the heat is generated in the lamp outside the device, while LED is low power consumption is less heat to heat in her tiny silicon chip inside conduction.

LED thermal management is a big problem

Even smaller heat to the chip size on conduction and divergence, due to the heat capacity of small device will cause the LED temperature rise. The working temperature of LED must be kept below 150 DEG C. The utility model has the advantages that the utility model has the advantages that a plurality of LED light emitting elements are used in a lamp, so that the heating quantity of a single piece is small, and the utility model can be arranged in a larger space to make the heat dissipation easy. This is the Koito automotive lamp used in TOYOTA's Lexus LS600h supporting headlight technique.

Cadillac EscaladePlatinum each headlight by 7 LED light tubes, 5 of them for short beam, the other 2 are as remote light source. They all have their own active heat sink cooling fan (similar to the built-in small fan in the desktop).

According to Hella, thermal management design field makes them special trouble, Hella in scheme selection focuses on virtual simulation means to assess the optimization in simulation tools (simulation software) the selection must be through enough experimental data research. He pointed to the challenges of thermal management