2010 Beijing Auto Show, BMW showed a concept called the Gran Coupe four-door sports car. Gran CoupeGran Coupe night at the BMW design deliberately creating an atmosphere of coming out, the focus naturally falls on its visual style and sharp LED headlights. More than BMW, Mercedes-Benz, Audi, Lexus also introduced a variety of models equipped with LED headlights. Released from the Audi R8 first use of LED headlights have been more than 2 years, known as the 4th generation of the LED is automotive lighting, emerging high-end models.

BMW Gran Coupe Concept four-door sports car LED headlights.

Automotive light sources in the lighting field occupies a pivotal position, with its output accounting for about 10% of the total output of about lighting. If a car changed all the lighting LED, out of about 400 to 600 required LED. In fact, as early as 10 years ago, LED on the scaled journey into the automotive field. Currently, LED lighting inside and outside the vehicle has exceeded the proportion of 80%.

Green LED headlights add durability horizon

The car headlights for the LED, it has always been a hard nut to crack. Because of distance and luminance lighting, LED headlamp lighting rarely used.

Tony Armstrong: high efficiency through the use of the drive can cope with heat dissipation

"There is no doubt that most of the headlights is still incandescent." Linear Technology products, power products marketing director Tony Armstrong, frankly, "However, this advantage will be from now on from the high intensity discharge (HID ) lamps and high-brightness (HB) LED front light pressure. "HID lamps in the late 90s of last century the first to be used as car headlights. However, the production and manufacture of such lamps are very expensive, so their use has been limited to high-end cars.

"Currently about 15% of the new car is equipped with HID." Automotive Semiconductor product marketing engineer Paul Decloedt estimates. However, HID light output too, on the close of cars, pedestrians constitute the risk of glare.

In addition, HID moment of starting to 35,000 volts of high pressure, may interfere with car stereos and other electrical appliances. It tried the owners of said xenon lamp, xenon lamp in the rain and fog weather conditions are relatively poor penetration. Paul Decloedt Paul Decloedt said: "The poor did not feel that the number of halogen lamps."

Therefore, Tony Armstrong is more optimistic about the HB LED, he believes in the HB LED will replace the HID headlights applications. He said: "HB LED headlight in the next 10 years will be extremely high rate of growth."

Paul Decloedt: LED light beam and the former is the main bottleneck in thermal management

Not difficult to find, LED headlights are mostly in high-end cars, especially sports cars are more common. Paul Decloedt said: "The use of LED headlamps can get more respect in the vehicle model changes." As LED headlights than incandescent, HID and more compact, more cars overall design flow can also be linear. Paul Decloedt further pointed out that the "compact" is not only smaller LED lamp itself, but also in optical components and electronic circuits with the use of LED and the corresponding weight.

In addition, LED there are many other advantages, such as an instant turn-on, no warm-up, easier to control brightness and so on. Also, do not forget the LED lighting industry into killer - a long life.Because LED long life, eliminating the replacement headlight "light bulb" issue.

Sheng automotive world wind blowing energy saving, LED appearance was in line with the green and efficient environmental requirements. "LED is green light, good color spectrum, there is no excess IR, UV and other spectra, does not contain harmful substances mercury, radiation is also very little." Shenzhen Secom Telecom Co., Ltd., said Liu Wei, Senior Application Engineer, LED light source with more high-lumen, and the LED is solid state lighting, HID lamps with different quartz glass is not fragile moving parts, with excellent shock resistance, failure is very low, almost maintenance-free.

Brightness LED headlight is still controversial

In the standard LED headlamp Lexus RX450h forum, is hot RX450h of LED headlamps. "Even if the car hit the front bumper tone, the tangent is also very light blue under the light type, with the corner of my headlights is better than it recognizable." Netizens such a description of Lu Yu RX450h LED headlamp practical results. The owners rejected another RX450h Road, "as long as the open RX450h owners must be very clear, LED headlights bright, very focused, though not very bright side looks like. LED than HID light source even focus, in particular the traffic light to stop According to the car in front bumper along the very bright, very bright open mountain is safe. "The owner of the original double-B fans (BMW, Benz), since a big difference on the Lexus.

To compare the performance of LED headlamps and HID, recruited two more hearts softened factory equipped with HID headlights and LED models tested in the evening at 17:30. 20m away from the concrete wall outside the test results show, LED headlight brighter than the HID, but a little more back than HID headlights LED on the.

Consumption per unit of electricity generated LED light output is indeed higher than incandescent, but to more than a single LED, LED light output edge is not so impressive. In order to obtain sufficient brightness, LED modules to be used the way lighting.  "A LED module failed to function for the low beam to provide sufficient light. Therefore, you have to almost light beam for each function using multiple LED modules." Paul Decloedt that since the application of automotive headlights is the beam, Each LED module requires an optical component (lens or mirror).  "This is the LED beam light and high beam prices remain a major cause of expensive." Furthermore, the characteristics of the LED lighting module is also difficult to define the lead vehicle regulations LED headlamp with multiple module for damage.

Difficult heat dissipation LED Headlamp

In addition, for 5 minutes after the test, LED headlights of the temperature is very hot. Paul Decloedt said, LED light beam and the former is the main bottleneck in thermal management. Only after the LED brightness will reduce fever and, more importantly, their life may be significantly reduced.

Tony Armstrong calculations for vehicle manufacturers LED headlight system power off. Each headlamp system includes optimized for all lighting needs 5 LED lights that beam lights, high beam, turn assist lamp, daytime running lights and turn signal lights. Standard headlights typically require 35W to 50W of power, high beam headlights and standards typically require the same or slightly higher than its power, and turn assist lamp, daytime running lights and turn signal lights need less power. In total, the whole front light system may consume more than 200W of electrical power, which could lead to a huge thermal power consumption.  "This LED headlights have fatal consequences, because the LED light output and operating life with high temperature and rapid deterioration will be." Tony Armstrong emphasized.

Heat is the most direct way. However, Tony Armstrong reminded the headlamp designers, the traditional cooling devices will be introduced other problems, including heat and material costs caused by the rise in the total weight of the system.  "Responding to the most effective cooling method is by using a high efficiency drive (over 93% efficiency) to minimize the heat generated LED driver circuit." Tony Armstrong think the heat after this method can be less LED lights installed in front of a small printed circuit board copper radiator can easily generate the heat to escape. Linear Technology LT3755-2 LT3756-2, and when in boost mode can provide more than 94% efficiency, so without any external cooling measures.

Commercialization of LED headlamps overseas not long, China's domestic automakers do not have any follow up action, most companies are still on the sidelines. Liu said, LED headlamp is much higher than the price of HID, but not high temperature, require large heat sinks. "Limited to the actual thermal design, LED light failure, electrical control design and other factors, LED own advantage in the real remains to be seen reflected."

HID headlights and LED par

Although the process of domestic and international use LED headlights are different, but the ON Semiconductor, Linear Technology, Secom Telecom agree, the future trend of headlights are HID, LED-based. "In particular, HID has a high price, should be more common applications, LED will be applied in the high-end models." Liu said, now have home-made mid-class car manufacturers to consider installing HID car the light off.

Although the cost-sensitive car is likely to continue to use halogen lamps to provide a low beam lights function, but mid-range cars are concerned, Paul Decloedt that will be the HID and LED in the world. 20W HID appearance, eliminating the automatic dimming function and spray cleaner (spray washer), so that the overall cost of HID more attractive. Paul Decloedt expected number of new cars equipped with HID in the next three or four years to double.

The home LED headlamp in other applications, such as fog lights, steering assist lamp, turn signal, daytime running lights (DRL), outline marker lamps (Position Light) and so on. Paul Decloedt expected, these non-high beam / low beam light features LED applications will quickly climb, the adoption rate of more than HID.  "5 years from now, 30% of the cars will be equipped with multiple LED headlamp features" but in the LED light beam and the near side, Paul Decloedt expect the adoption rate will be less than HID.

In fact, people who have had driving experience will know, in addition to the brightness of headlights related to traffic safety, headlight range and intensity of lighting is also important. The actual results compared LED and HID headlights 1.5 Drive: 2 lane of view, LED, there is still room for improvement in the breadth. In summary, LED headlights process also depends on the LED to further reduce prices, solve the heat and the second optical system improvements.
 

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