Views: 0 Author: Site Editor Publish Time: 2024-08-01 Origin: Site
All things in nature follow their inherent laws of development. With the EU's ban on halogen lamps, LED headlight technology has ushered in new development opportunities. However, some car owners still have a special preference for halogen lamps, especially in the rainy southern regions, where they consider the strong penetration of halogen lamps to be one of their few advantages. However, this does not necessarily mean that LED headlights are inferior to halogen lamps in terms of penetration. In fact, choosing the appropriate color temperature can improve the penetration of LED headlights and avoid using excessively white light sources. If car owners still have concerns about this, they can consider installing color changing lights to adapt to different weather conditions.
In addition, some car owners are also concerned about the issue of LED headlights' light decay. As is well known, significant achievements have been made in the application of semiconductor materials in the LED field. However, everything has its two sides, and the defects of semiconductor materials are equally evident. Due to the high temperature requirements of semiconductor materials, they require a stable working condition, which is also applicable to LED headlights. This means that the performance of LED headlights is largely influenced by their cooling system. Therefore, designing efficient heat dissipation solutions is crucial for ensuring the long-term stable operation of LED headlights.
1. Analysis of LED car headlight light attenuation
One undeniable feature of LED headlights is their long lifespan, which can reach up to 30000 hours, several times longer than the lifespan of traditional light sources, and there is basically no need to replace the lighting fixtures. Moreover, it is energy-saving, environmentally friendly, radiation free, and has a relatively fast response time. In addition, due to its small size, it has high plasticity and naturally diverse shapes. Car LED headlights can be said to occupy a mainstream position in current car headlights, and high-power LED headlights like this have low energy conversion efficiency. Automotive LEDs typically only convert 10% -25% of electrical energy into light energy, while the remaining electrical energy is converted into heat energy.
The heat generated by traditional halogen lamps is much higher than that of LEDs, but the output brightness of halogen lamps does not change due to heat, and their heat design is mainly focused on the uniform temperature design inside the housing. However, the light output of LED will be affected by its own heat or high temperature from the engine compartment, which will affect the stability of its PN junction temperature. Important parameters such as LED luminous flux and wavelength are directly affected by the PN junction temperature. This poor temperature cycle will lead to a sharp decrease in luminous efficiency and lifespan. This situation is generally referred to as light decay. How can we solve the problem of light attenuation caused by high temperature? There are two methods, one is to design the heat channel, and the other is to use materials with better thermal conductivity.
The design of heat circulation is essentially aimed at creating a more efficient path for thermal energy discharge, ensuring that heat can be quickly dissipated or effectively cooled. In the automotive industry, the front grille of a vehicle is a typical example, which utilizes the airflow during driving to remove heat energy from the engine compartment, making it an efficient thermal management strategy. Similarly, installing a fan on an LED light is similar in principle to an air intake grille, but the key is that the fan itself cannot directly absorb the high temperature of the PN junction, but relies on a thermal conductive material to transfer heat to the fan. This requires the use of high-performance thermal conductive materials, because if heat cannot be effectively conducted, the heat dissipation effect will be greatly reduced.
The LED beads have the closest contact with the substrate and lens. However, the lens itself does not have thermal conductivity, so it is necessary to choose a substrate with excellent thermal conductivity to address the heat dissipation challenge. At present, there are three main types of substrates used for LED lights: aluminum substrates, ceramic substrates, and double-sided copper substrates. Which substrate is more suitable for car LED headlights? We can analyze them based on their respective characteristics and advantages.
2. Ceramic substrate
Advantages: Aluminum substrate has nearly a hundred times higher thermal conductivity, high temperature resistance, and strong mechanical strength.
Disadvantage: The current domestic production capacity is not sufficient to supply such a huge LED industry chain.
3. Aluminum substrate
Advantages: Compared to epoxy resin substrates, metal substrates are significantly more reliable, have better stability, and excellent thermal conductivity.
Disadvantage: An insulation layer needs to be made before it can be put into use, and the overall thermal conductivity is still determined by the insulation layer. The thermal conductivity is approximately 2-3W/(m • K). Unless thermoelectric separation is carried out, but in terms of process cost, the entire process is somewhat unprofitable.
4. Double sided copper substrate
Advantages: It can achieve efficient heat dissipation and super concentrated light, and the thinness in the middle is very close to that of halogen filaments; Double sided copper has more advantages and has been regarded as the development direction of LED car lights in the future. LED headlight copper strip heat dissipation is a passive heat dissipation method, and the larger the copper strip heat dissipation area, the better the heat dissipation effect.
Disadvantage: High cost.
5. Summary
The above contrast is obvious. Will metal substrates be replaced by ceramic substrates? However, double-sided copper substrates are the development direction of LED headlights, and they are still one of the best substrates on the market, so the price is naturally not cheap. When purchasing LED car lights, car enthusiasts are required to pay attention to their capabilities. In terms of brightness, if it is not a color changing light, try not to buy a color temperature greater than 7000K to avoid insufficient penetration.
