Get rid of light and heat technology barriers LED street light system design Great Leap Forward

Due to the advantages of power saving, energy saving and environmental protection, LED light source is expected to replace the traditional light source to become the mainstream of the new generation of street lamps. However, the current market products are different, and the system design technologies of light, machine, electricity and heat still need to be broken. Among them, the technical difficulty of light and heat is the highest. Fortunately, the technical bottleneck has made a major breakthrough, which will help accelerate the expansion of the street lamp market in the future.

In the era of high oil prices and high electricity prices, how to effectively improve the efficiency of lighting equipment has become an important task in energy conservation and carbon reduction. With the improvement of LED luminous efficiency and life, LED lights that can only be used for indication or auxiliary use are gradually extended to general lighting, which can achieve street lighting facilities that provide nighttime traffic safety lighting and maintain nighttime security, improve overall city appearance and save electricity. , energy saving and environmental versatility.

LED street lights are of mixed quality

LED street lights must be tested by high and low temperature differences and weather conditions in the sun and rain. Some products fail after less than half a year of installation. LED street lights are mixed, resulting in insufficient user confidence and weak market demand. Some experts believe that the current luminous efficiency of LEDs is still different from that of high-pressure sodium lamps. It is used as decorative lighting and some ambient lighting. However, as road lighting, it is only suitable for hospital (garden) or secondary roads. As a functional road lighting (main road), there are still many technical problems to be overcome, such as heat dissipation, secondary light distribution, uniformity, etc., so it is not suitable for main road lighting.

Light/machine/electricity/heat four technical bottlenecks to be solved

Because of the illuminating characteristics of LEDs, about 80% of the input electric energy is converted into thermal energy, and the LED dies are semiconductor materials, so they are not resistant to high temperatures, and the luminous efficiency will decrease as the temperature of the chip rises. The primary consideration of heat dissipation becomes LED street lamps. . Secondly, the application of street lamps must comply with the road lighting regulations. According to the regional and road conditions, there are different regulations according to illumination and illumination uniformity. Therefore, optical design becomes the second biggest challenge for LED street lamps. Others such as LEDs require DC drive, so the arrangement and power supply selection are technical priorities, as well as safety considerations such as wind pressure resistance, lightning strike resistance, and vibration resistance, all of which increase the difficulty of designing LED street lamps.

Simply put, LED lamps are to consider heat, light, electricity, and machine. The highest technical bottlenecks in the current market are heat and light. The following two technical parts will be discussed.

Solve heat dissipation problems with heat dissipation mechanism / passive heat dissipation / components

The highest temperature that the LED chip can withstand is about 125 to 150 °C. In the application of LED street lamps, the ambient temperature can reach above 35 °C, and even in the high temperature region above 40 °C, if the heat can not be effectively cooled (control junction temperature), the life of the LED will be rapidly decreasing. According to Cree's data (Figure 1), if the junction temperature of the light-emitting chip can be controlled at 65 °C, the overall life of the LED will reach 100,000 hours (calculated as 30% of light decay).

Data source: Cree
Figure 1 LED life chart

The LED light starts to heat up from the chip, and the heat sink dissipates the heat. The entire heat transfer diagram is shown in Figure 2. The front section is related to LED package design from LED chip to LED base. Therefore, selecting the temperature-resistant chip, phosphor, package material and package design with low thermal resistance is the primary requirement. At present, the thermal resistance can generally reach 10K/W or less. Good technology has reached the level of 5K/W. The rear LED base to the air end is related to the heat dissipation mechanism.

Figure 2 LED simple heat transfer diagram

Product application:
â– Products for commercial,household,lighting
 
Product features:
â– High strength,impact resistance and thermal stability
--Panel material using high quality polycarbonate
â– High resistance to deformation
---Long term use without obvious distortion       
â– Flame retardant grade
----The flame retardant grade of panel is in line with UL94-V2
â– Adaptation property
----American Standard socket adapter all accord with NEMA
Standard