Development status of high power LED street lamp application technology

LED light source as a solid illumination source, with its long life (theoretical average life is more than 50,000 hours), high luminous efficiency (theoretical value is greater than 200Lm / w), multi-light color and primary light distribution directional illumination function, can be safe and low voltage Work, can also be continuous switching flash, can achieve 0 ~ 100% dimming function, output light without stroboscopic and many other advantages, become a new generation of efficient, energy-saving light source development trend.

At present, low-power LED light sources have been widely used in landscape lighting. High-power LED street lamps are also becoming more and more mature with the rapid development of semiconductor materials application technology. In industrial applications, the light efficiency reaches 70--80Lm/w and the life span reaches 2.5-30,000 hours. It has gradually been applied to urban road lighting.

The number of companies is large but the scale is over 100 million.

There are more than 3,000 LED lighting industry-related enterprises in China, including more than 2,000 application companies, 600 large-scale packaging companies, and 42 extension and chip companies. Although the number of Chinese LED companies is large, the scale of enterprises is generally small. From the sales situation in 2009, there are very few manufacturers with sales of more than 1 billion yuan in China's LED industry. Only a few of them have annual sales of more than 500 million yuan. The annual sales of hundreds of millions of enterprises are 1~2. Billion.

At present, LED packaging, LED display, LED lamps and other products have maintained a good profit level. In 2010, with the increasing demand for LED lighting, companies that do LED packaging and LED display have also entered the field of LED lighting. At present, the number of companies that only do LED packaging in the Chinese market is very small, and most of the packaging companies have begun to develop and produce LED lighting products. The enterprise boundaries in the field of LED applications have become increasingly blurred, and the LED product lines of various companies have become longer and longer.

However, China's epitaxial materials, chips, packaging, lighting development and other aspects are out of touch, the upper, middle and lower reaches of the industrial chain are not in place, can not form an organic whole, domestic enterprises in the chip development process, chip packaging and other core technologies There is still a certain gap with foreign standards, which also seriously restricts the development of China's LED lighting industry.

With the rapid development of domestic LED street lamps in the past two years, many companies have begun to engage in production and R&D, but the quality of LED street lamps is uneven. Due to the limitations of capital and technical level, most of the small enterprises have not undergone strict professional design in light, electricity and heat, or they are not familiar with the quality requirements of road lighting and lighting of lamps. "Planning" other people's products, or subjective imagination of any combination, arrangement ... so from the test and practical application results to see a lot of problems. At present, only a few enterprises regard LED street lamps as their main business, strengthen investment in science and technology, form independent intellectual property rights, and obtain patents, which have contributed to the development of LED street lamps.

In addition, domestic LED street lighting companies rely mainly on invisible channels such as engineering for market development. The explicitization of brands and channels will eventually become one of the conditions for the widespread application of semiconductor lighting products. At the same time, brand and channel construction will also determine the competitiveness of enterprises. The key to development.

Light distribution, heat dissipation, light attenuation

To truly make full use of the advantages of semiconductor light sources, the secondary optical system design of LEDs is critical to the light distribution and optical output efficiency of LED street lights. At present, Ningbo Liaoyuan Lighting Co., Ltd. (hereinafter referred to as "燎原") LED street light mainly uses two kinds of light distribution design schemes: one is the LED street lamp adopts the axisymmetric total reflection lens and the reflector, and the LED lens module is arranged in the different lamp housing. The position, while using a total reflection lens to produce the required light distribution, maximizes the efficiency of light utilization. The disadvantage is that the arrangement of the LED modules makes the heat dissipation design and mechanical structure of the high power LED more troublesome. The second solution uses an asymmetric free-form lens that is directly integrated by a single LED optic. The whole lamp head only needs to simply arrange the LED modules on a flat plate. The LED street lamp is relatively simple in terms of mechanical structure, heat dissipation and power control. Road lighting of different grades of roads and different pole heights only needs to increase by different numbers. The LED module can be. The use of asymmetrical free-form secondary optics allows the light distribution of LED streetlights to be implemented directly on a single LED module.

LED light source is used in embedded lighting fixtures. High temperature causes deterioration of the performance of the chip itself and the encapsulating resin, which ultimately leads to a decrease in luminous efficiency and a shortened life. Therefore, "heat dissipation" becomes an important key technology for high-power LED street lamps. At present, LED street lamps adopt a monolithic and systematic heat dissipation design concept, and apply high-performance heat-conducting materials, such as aluminum die-casting molds, aluminum extruded toothed heat sinks, integral toothed heat sinks, and aluminum extruded profile cross-shaped heat sinks. The heat pipe long fin shape, the external tooth structure piece, the natural heat dissipation to the flow body, and the super alloy heat pipe (the heat conduction speed is 100 times of pure copper) combined with the high density heat dissipation aluminum fin. The heat generated by the chip is quickly converted from a point source to a line source, so that heat is evenly distributed to the heat sink.

LED light sources now have a common light fade problem. Some manufacturers' LED street lights have been installed for less than one year, and the brightness is seriously attenuated. LED lamps convert electrical energy into light energy and heat energy during operation. For every 2 °C rise in component temperature, lamp reliability will drop by 10%. When the operating temperature is raised from 63 °C to 74 °C, the average LED life will be reduced by 3/. 4, chip packaging, lamp cooling and other factors may cause light attenuation. Based on the patented heat-dissipation technology developed by the company, the LED street lamp is continuously lit for 3,000 hours, and the light decay is not higher than 3%. After 35,000 hours of continuous lighting, the luminous flux reaches 70% of the initial luminous flux.