How to apply LED technology to car headlights smoothly
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Automotive light sources occupy a pivotal position in the field of lighting, and their output accounts for about 10% of the total output of the entire lighting source. If you change the lighting of a car to LEDs, you need to use 400 to 600 LEDs. In fact, as early as 10 years ago, LED has entered a journey into the automotive field. At present, the proportion of LEDs inside and outside the vehicle has exceeded 80%.
LEDs as a vehicle headlight source still have objections. It can be seen that the vehicle body control system control must be designed according to the light source with different power requirements. From another angle, from the application of LED in the car, although the LED in the application of the third brake light, to the taillights of the car, the turn signal to the brake light, step by step to create LED for interior and exterior lighting.
At the 2010 Beijing Auto Show, BMW presented a four-door concept sports car called GranCoupe. GranCoupe emerged in the atmosphere of the nightly design that BMW deliberately created, and the visual focus naturally falls on its sharp LED headlights. More than BMW, Mercedes-Benz, audi, and lexus have also introduced a variety of models equipped with LED headlights. It has been more than two years since Audi released the first LED headlight R8. The LEDs known as the 4th generation of automotive lighting sources are appearing on high-end models.
On the LexusRX450h forum with standard LED headlights, the LED headlights of the RX450h are being discussed. "Even if you hit the bumper on the front of the sound car, the tangential line is a very light blue light type, even my headlights have better recognition of the residual light." A netizen encounters the RX450h's netizens to describe the LED headlights. actual effect. The other RX450h owner replied, "As long as the owner of the RX450h is clear, the LED headlights are super bright and very focused, although the side looks too light. The LEDs are more concentrated than the HID light source, especially the traffic lights stop. According to the front of the car, the underside of the bumper is very bright, and the mountain road is very safe and bright." The owner was originally a BMW B, and has since changed the Lexus.
In order to compare the performance of LED headlights and HID, it is better for those who have found two models with HID and LED headlights to test at 17:30 in the evening. Test results outside the cement wall 20m show that the LED headlights are brighter than the HID, but some LEDs are not as good as the HID headlights.
The light output per unit of electrical energy consumed by LEDs is indeed higher than that of incandescent lamps, but the advantage of the light output of LEDs is less pronounced than for individual LEDs. In order to obtain sufficient brightness, it is necessary to use LED module illumination. “An LED module does not provide enough light for the high beam and low beam functions. Therefore, you need to use multiple LED modules for each of the low beam and high beam functions.†Paul Decloedt points out that since the car headlights are beam applications, each One LED module requires an optical component (lens or mirror). “This is a major reason why LED low beam and high beam prices are still relatively expensive.†In addition, due to the characteristics of LED modular lighting, it is difficult for automotive regulations to define whether LED headlamps with multiple modules are damaged.
Solving the problem of LED heat dissipation is the key to future development. Since about 90% of the input energy of LEDs must be discharged, this is much higher than that of traditional light sources. In addition, LED chips are classified into semiconductor materials and cannot withstand high temperatures. (<120 °C), the heat removal from the grain to the atmosphere only allows a temperature difference of about 50 °C, which is much lower than the traditional light bulb. Therefore, the heat dissipation design is one of the subjects that distinguish the LED light source from the traditional light source, plus Lamps can not be cooled by fans, and the lighting products should be popularized in the automotive market. It is necessary to further consider the appearance design and the optical design principle of the lamps, which will be extremely troublesome for high-power LED lighting equipment.
Strictly speaking, the heat source generated by the traditional lamps is actually much higher than the LED; however, the traditional lamps will not reduce the output power of the light source because of the high temperature, but the light output of the LED will cause the LED due to its own interface problem. Luminous efficiency is affected. How the heat generated is dissipated to the external environment is closely related to its packaging structure materials, involving the use of heat-dissipating materials and related appearance. The concept of thermal resistance, when representing the input W power, needs to increase how much K temperature is enough to dissipate heat. With the existing packaging technology, the maximum allowable LED operation is 185 ° C (Lumiled K2), but generally because of the relationship between the package adhesive, the allowable operating temperature is about 125 ° C, in addition to considering the light source output efficiency, the package must also be considered. The deterioration of the rubber material is, for example, an aging phenomenon which is likely to occur at a high temperature when the resin material is used as a coated LED crystal.
At present, some manufacturers have developed the effect of “heat-temperature uniform temperature superconducting technologyâ€, which can heat the heat generated by LEDs; that is, when the temperature difference of LED lamps is between plus and minus 1 degree, The forced cooling technology uses the dust-shielded semi-open space designed by the luminaire to perform the air venting action, that is, the convection of the air can be achieved, and the heat dissipation effect can be achieved. This development concept is like the heat dissipation of the human body. In addition to relying on the skin to dissipate heat, it also relies on the lungs of the second space to breathe for forced heat dissipation.
Nowadays, although there are many problems to be solved in LED, it is an indisputable fact that LED has been applied to high-end cars (sports cars). How to reduce the cost of LEDs and achieve smooth popularity depends on solving heat dissipation and improvement of secondary optical systems.