About the mechanism of light-emitting LED light source

Now, with the LED industry supply with mature, low barriers to entry, a large influx of small businesses, resulting in excess of the LED bulbs, and because its production capacity utilization rate is low, certainly compete in the market giant Philips brand (Philips), Osram (Osram) and GE, these manufacturers through vertical integration or strategic alliance layout, the main active occupation of LED lighting market. Whether exploited or through gross margin much larger rivals, small factories and thus escape the huge market pressure.
China has rich resources of non-ferrous metals, gallium, indium-rich, the world's total reserves of 70% -80%, which makes the development of semiconductor lighting industry in China has the advantage of resources. By 2010, the Chinese LED industry output will exceed 150 billion yuan. As early as 2002, Japan spent ¥ 5 billion to implement white light illumination, the program's budget of 60 billion yen.
With the rapid growth of LED penetration, along with the price war will come in 2010, because unlike the traditional lamp and LED downlight source separate from the sales model, in this pressure, some companies can not take into account quality and price competitiveness, may will fall to the merger or be doomed.
May 7, 2010 -12, Henan Province, lighting, lighting experts and entrepreneurs learn to organize his party visited Japan Japanese lighting situation, found that Japan's current situation is not satisfactory LED lighting.
In recent years, in light of the most interesting event is the rise of the semiconductor lighting. The mid-1990s, Japan's Nichia Corporation Nakamura, who through unremitting efforts, broke through the manufacture of blue light-emitting diode (LED) of the key technologies, and thus developed a fluorescent material to cover the blue LED technology produces white light source .
led the LightEmittingDiode (light emitting diode) acronym. New solid-state light-emitting diode is a cold light source, LED's most notable feature is the long life, high photoelectric conversion efficiency, good seismic performance, ease of use in the lighting system more widely. Under the same illumination, LED tube and power consumption than incandescent and fluorescent lifetime have clear advantages.
White light of various methods of development, and development of next-generation phosphors, LED luminous efficiency has led to a substantial increase in current industrial products from 45lm / w up to 100lm / w (2009, Cree's cold white light efficiency when at 350mA over 100lm / W, while the warm white light is more than 75lm / W), the level of research 160lm / w, the highest level of expectations of the target 200lm / w or more. Life of 40,000 to 80,000 hours.

Power shortage, energy-saving products have become the "meat and potatoes"

Compared with ordinary fluorescent lamp, LED bulbs lamp energy saving, long life, safe and reliable. According to reports, a 15-watt fluorescent light with 40 LED fluorescent wap pass close to, but it's more than 50,000 hours service life is 5-8 times the normal fluorescent lamp. Although the LED lamp has many advantages, but the price of each one hundred and sixty seventy yuan will allow consumers to stay away? Lianzhong business manager Mao Yuehui optical calculations: a 15-watt LED lamp with a power less than 24 hours ordinary 40-watt fluorescent lamp for 40%. Electricity by industry 0.8 dollars each, LED fluorescent year, saving 210 degrees can save electricity more than 160 yuan, just the purchase cost of LED lamp. And some textile weaving business, shopping malls, hospitals and hotels and other high demand for lighting the place, the amount of fluorescent light is hundreds of branches, some large amount of textile enterprises and even up to thousands of sticks. These locations are used in ordinary fluorescent LED fluorescent replacement, energy-saving effect is very obvious.

LED street lamp market's future depends on the reliability issue is resolved

Government are currently carrying out most of the world lighting upgrade, the first step is to install LED lights in the new development area, then, LED light will replace the existing old street lighting. According to expect in the next five years, today most of the lights are LED lighting will be replaced.
However, LED lights are facing a big problem is the low reliability because it is mainly used for outdoor lighting, face a variety of extreme environmental conditions, such as long withstand sun and rain, thunder and lightning, temperature changes may be more so. LED lights to be recognized by the market and large-scale use, we must first solve the reliability issues.
TI Semiconductor Division Business Development Manager Liu Chao
TI High Performance Analog Semiconductor Division, Business Development Manager, Dr. Liu Xuechao, said: "LED street lamp market prospect, but must address reliability issues."
LED lights is an optical, thermal and electronics components of complex systems, although a longer LED life of its own, but if poorly designed LED driver circuit, such as the use of low-quality active or passive devices, and the overall life of the drive circuit not match with the LED, LED lights will affect the quality and life.
Furthermore, LED thermal management and heat dissipation is also very important, once the temperature higher than 100 ℃, LED itself, the reliability will be affected. Of course, LED early failure, and transient assembly of local defects and other factors, also led to the LED may fail occasionally, if not take appropriate protective measures diversion, a single LED failure will lead to a whole string of LED does not affect the overall effect of street lighting .
Liu Chao stressed that: "LED lamp is a complex system design, involving light, electricity, heat, mechanical and other fields. Mainly on the drive power in terms of efficiency and reliability problems. First, the driver power supply temperature is high (usually 70 degrees up and down), this way, I hope to drive power efficiency (including the constant voltage with constant current) efficiency reaches a certain height (eg> 90%), reducing the drive power of the temperature, increase reliability, and secondly, the traditional driver topology is more complex, including the PFC, PWM isolation and constant current DC / DC three circuits (see below), components and more, low reliability, especially electrolytic capacitors and opto-sensitive devices. "
Thus, in the process of designing LED bulbs, LED temperature must be well taken into account management or cooling problem, the LED operating temperature remains below its junction temperature (maximum junction temperature of 150 ℃), is generally recommended to be less than the LED operating temperature 100 ℃, avoid affected the reliability of the LED. In addition, LED spotlight circuit designer must carefully choose the circuit in the active or passive devices, to ensure match with LED life. For example, designers should avoid the use of electrolytic capacitors as much as possible, because the capacitor under the conditions in long-term use may cause leakage and result in shortened life expectancy.
Furthermore, LED lighting market in the overall, LED lights are all LED lighting applications the highest power, and therefore require multiple power levels and complex topology to meet the power factor correction (PFC), total harmonic distortion (THD) , 85 PLUS efficiency and other standards and regulations, and multi-string LED current constant demand.
Liu Chao also said: "To solve the problem of circuit reliability of LED lights, drive topology must improve, improve efficiency, reduce component count, while also further reducing costs."

What is a light-emitting diode (LED bulbs)?

To bring light, people immediately think of those colorful variety of lighting fixtures store. Although these lamps of various shapes, but the lighting of the main core of the --- in fact, only two light bulbs: incandescent and fluorescent lamps.

However, this situation will change soon, because the lighting of the star --- LED bulbs are to the practical stage. LED was invented in the 1960s, in the ensuing decades, its basic use is as tape recorders and other electronic equipment lights. To maximize the potential of LED lighting, recently, scientists have developed a new type of light-emitting diodes for lighting lamps. This bulb has a high efficiency, long life, continuous use 10 million hours longer than ordinary incandescent bulbs 100 times. It is estimated that, worldwide, LED bulbs 90 billion pounds of market prospects. In the huge business opportunities to attract, some bulbs such as Philips and other manufacturers have started to invest hundreds of pounds, research and development of household LED bulb. Scientists predict that in the next five years, this bulb is likely to become the mainstream of the next generation of lighting products. As we all know, since the American inventor Thomas Edison invented the incandescent lamp has 100 years, people still used the basic technology to produce Edison's incandescent light bulbs. Light bulb in the middle is a piece of tungsten wire, when the current through tungsten filament light bulb to heat activate the gas glow. However, LED light bulbs in terms of structure or in the light principle, with the traditional incandescent lamp is essentially different. Light-emitting diode is composed of several thin layers of doped semiconductor material, a layer with the excess electron, due to lack of electrons to form another layer of positively charged "hole", when a current is passed, the electron and hole combined with each other and release energy, which radiates light. For a long time, why people did not LEDs used for lighting, mainly because usually only red light-emitting diode light or yellow light, in order to obtain white light, must also be manufactured that emits blue light-emitting diodes. In this way, red, yellow, and blue light "hybrid", you produce white light. Now, the trouble has finally been solved people's problems. Scientists have discovered a new type of gallium nitride semiconductor material --- it can be treated properly in blue. Blue light is resolved, the questions have been made white hope. University of Cambridge Department of Materials Science of Colin John Humphreys said they have developed in the experiment can be made white LED street light, this light bulb is very close with the sun, with good prospects. He said the light-emitting diode bulbs on a semiconductor material, so that a small light-emitting device can do, and only a few millimeters, to be installed in the wall or ceiling, if you do not turn on the lights, hardly notice their existence, so it eliminates the incandescent lamp to prevent light to be coupled with barbed eye trouble. In addition, the bulb life is very long, after the placement of almost no change, in the future people may forget how changing light bulbs is one thing. Currently, he is calling on the British Government to increase investment in order to ensure the UK in the forefront of this technology. In addition to durability, this kind of energy-saving light bulb in there is great potential. It is calculated that if half of the U.S. light bulb in use LED bulbs, you can shut down 24 power plants, saving billions of dollars, carbon dioxide emissions will be decreased. For this reason, the U.S. has plans to 2006, all the traffic lights use LED light display, so that each intersection can save $ 750 per year. Despite the many advantages of this lamp, but really into ordinary families also face two major obstacles. First, the price is too high, and now the price of each bulb is 30 pounds, while only 35 pence ordinary incandescent bulbs, the gap is too large. Second, it is hard to produce white light suitable for home use hair bulb. But the developers believe that the price of this lamp can be reduced in the next five years, each 5 pounds. By then, the LED bulbs will light from the traditional electronics emerged as the lighting of the star.