vehicle LED lighting and the problems facing the measures

vehicle LED lighting and the problems facing the measures

Vehicle LED lighting technology as a breakthrough of the new technology has significance has been most of the car manufacturers and consumers accept, more and more upscale cars are equipped with LED lights. But because of the special requirements of automotive application environment to really achieve vehicle LED light source, and instead of traditional many technical difficult problem to solve.

1 The cost problem

The global scope, LED a decline in the cost of production vehicle speed will be in effect for large scale application LED one of the major factors. Just components in itself, LED lamp price higher than other traditional light source. Such as: Moksan 1 W power white LED the market price of the covenant is incandescent light bulb ten times to dozens of times before, so LED chips with a lot of space, the main way price for development: (1) the big chip large current. Now the chip generally in 0.5 mm to 1.5 mm, chip, to increase the small current, this is LED to single obstacle to the development of high power. If not the lower efficiency under the premise of the chip to do big through more current, increase the power of single LED, so the number used lamps and lanterns LED will significantly reduced, help to a decline in the cost of lamps and lanterns. (2) the design of new substrate. Now China has started price cheaper Si substrate, and hopes to replace expensive sapphire or SiC. In addition to cheap outside, Si also can produce than sapphire or SiC substrate size more big substrate, in order to improve the utilization rate of MOCVD, so as to improve the core tube production rate of [18]. In addition, because of the hardness of Si than sapphire and SiC low in processing, also can save cost. According to one foreign well-known company estimates, use silicon substrate production cost of manufacture GaN LED light than sapphire and SiC substrate low 90%. (3) continue to extend the life of the LED. In theory, the life has LED more than car service life, but in the real car environmental application, LED the service life would be further developed. If the actual use LED lives to the life of the vehicle in the car without changing the light source, life period from the aspects of the cost of maintenance, will be more economy.

The whole vehicle LED lighting system is concerned, must reduce the system LED driving scheme level, in order to improve the cost of the technology market competitiveness.

One of the ways to reduce the cost of scheme is as far as possible to reduce the number of the drive, and it also components is helpful to improve the system reliability, because on the PCB each components may be a system failure point.

2 heat dissipation problems

Usually high power LED the input power convert about 20%, the remaining 80% are light energy to heat energy conversion, which is more than the traditional light source is much higher. If this part of heat energy cannot export, will make LED to high temperature, affecting interface product life cycle, the luminous efficiency and stability, and, as a result, the entire automotive lighting system can be severely affected [19]. Current vehicle LED lamps and lanterns to improve the main ways of heat:

(1) LED the improvement of their own. First of all, improve encapsulation structure. Traditional straight insert LED encapsulation structure thermal resistance is as high as 250 ¡æ / W ~ 300 ¡æ / W, and the new package structure of the low resistivity, high thermal conductivity of the material in the chip, binding chips with copper or aluminum heat sink, and USES the packets of sealing structure, greatly improving the LED the cooling capabilities of [20-21]. Second, the improvement of production materials, the LED ultra-thin, high thermal conductivity, high dielectric ceramic chips for basement, increase the cooling effect; Developing quantum conversion efficiency high, can withstand the temperature of the phosphor, improve the maximum allowable temperature, increase the node temperature cooling design allows, in order to reduce the difficulty of the cooling design.

(2) the improvement of cooling device. Mainly has: consider adopting appropriate forms, such as heat pipe heat, fan, water cooling, etc, to ensure that will send out quantity of heat quickly go out, and at the same time the heat radiator can steadily work [22-23]; Consider the structure of the heat sink shape and size, to ensure enough heat area, and at the same time to come loose hot effect is better; Consider the circuit board design, can format printed circuit board design for the upper and lower levels, the special happened in signal circuits, upper of LED dot matrix circuit, such as can effectively avoid because the heat transfer LED to the driver, to its chips damage.

3 photosynthetic efficiency problem

Ascension LED the luminous efficien is the key to the development of vehicle LED technology, is the starting point and the vehicle LED industrialization driving force. From the packaging technically, the packaging should try to reduce LED light in their internal total reflection, increase substrate substrate, so as to make the light can reflectivity as transmission out the luminous efficiency, increase LED. In February, the company has announced its own Cree laboratory results LED efficacy has reached 081 m 2 / W, believe that this is not limit, will also have higher ascension space, but need new technical breakthrough.

4 electromagnetic interference problems

Car environment also faced ElectroMagnetic Interference problems EMI (ElectroMagnetic Interference). Vehicle electronic products is very sensitive to noise, especially navigation system, wireless circuit and AM radio band receiver. In order to maximize reduce happen the possibility of some noise, LED drive IC by constant frequency switching topology structure. In addition, users also can be in 200 kHz ~ 2 MHz within the range of the set the switch frequency, in order to make the switch away from key frequency noise (such as AM radio band).

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