2012年10月 – 第7页 – LED Lighting Blog

India announced the latest trends of the LED lighting industry

Electronics For You is a flagship magazine of EFY Group. Recently, EFY has published a latest report for the LED lighting industry in India. Although LED lighting technology has a lot of advantages compared with other traditional lamps, like longer service life, more environmental friendly, more energy efficient, and less health-hazarded, LED products still cannot be mass produced in India as a result of the over-expensive initial production costs. Therefore, in India, almost every LED makers are eager to create a kind of LED lighting products that are completely competent for commercial operations, just like incandescent bulbs does. They still need innovations on the road to achieving this goal.

The luminous efficiency and output luminous flux of LED lights doubled every 36 months, as well as the total performance, which is consistent with Moore’s Law. In the past few years, LED lighting technology has been improved in many aspects: performance, color and quality. Based on different application solutions, the color temperature can be fixed within the range of 2700K to 6500K. And 70-95 for color rendering index (CRI). The life cycle of White-ray LED lighting applications have reached up to 100,000 hours, which dramatically reduces maintenance and replacement costs.

The report pointed out that the entire LED lighting industry is very optimistic, full of innovations:

1) Omni-directional LED lights, just like incandescent lights does. If LED lights want to be the benchmark of general lighting industry, omni-directional lighting is necessary. Only the omni-directional LED lamp technology is able to provide solutions for multi-directional lighting modes. As a matter of fact, the LED lighting industry in India was followed this direction all the time, from the very early stage of development to now, from the simple equivalent LED lighting technologies to traditional lamps, from single-color LED lights to RGB LED applications, from lamps to intelligent lighting system.

2) Organic LED. It is expected that this kind of LED lights can be the most environmental friendly lighting technology in the future due to their small size and high performance.

3) Clever design. This provides an alternative for traditional incandescent lamps, similar parameters and output optical energy.

4) Non-contact phosphor technology. This technology was mainly invented to reduce the cost.

5) AC LED lamps. These lamps can maintain the same output optical output with DC LED lamps. There will be no need to conduct the AC to DC conversion.

The surge of China’s LED chip production triggered global overcapacity crisis

LED chips produced by China’s manufacturers and led enterprises can generally be divided into two types: 1. cheap but low performance. Mainly used as backlight of keyboards, children’s toys, shoes, and power indicators; 2. good quality LED chips used in high-end products. Normally, manufactures produce this type of LED chips would co-operate with large foreign companies. Currently, the soared increasing of China’s LED chip production led to the global market overcapacity. Dropping prices of LED chips is inevitable.

In recent years, governments all around the world made great efforts to support the LED industry, subsidized related infrastructure, improved the efficiency of LED chips, drove the penetration in emerging markets, established special funds to develop industry standards, etc. The goal is attracting more LED manufacturers to invest and build factories.

The Chinese Government is undoubtedly the most hard-working government in the world that in the promoting of LED lighting technology. On one hand, every domestic manufacturer that invested the new epitaxial reactors could get a 1.5 million USD from the government, which has occupied nearly 75% of the total cost. On the other hand, the government expected a rapid development of every LED manufacturer and provided low-interest loans, tax breaks and ultra-low prices of land rent (or even free) for new-born LED manufactures. It can be said that the substantial support of the Chinese Government that indirectly the surge of China’s LED chip production and accordingly the overcapacity crisis in the global lighting market.

Ross Young, senior vice president of IMS Research indicated that “All of these LED chip makers can benefit from the growth of LED equipment investment. A large amount of Chinese LED companies have declared to enter the sapphire market (a typical LED chip material). They must have seen the opportunities and huge potentials behind the market.” Among these enterprises, a large part is successful poly-silicon manufacturers with potential advantages in the development of sapphire substrates. As for the organic metal, gas sources and MOCVD equipments, China’s LED chip manufacturers still relied on overseas imports. Mr. Young also indicated that applied materials companies have handed over the first set of MOCVD to the Chinese Government. Korea epitaxy reactor vendor Jusung started to target the Chinese market due to the falling of domestic sales. Meanwhile, Taiyo Nippon Sanso from Japan also turned to the Chinese market.

The America Government decided to installed LED road lighting applications to reduce urban crime rate

The American Austin City Police Department and Austin Energy Board cooperated recently to provide more protections to their residents. Since 2011, the crime rate of Austin was significant increased. In order to control this phenomenon, these two institutions planned to installed LED road lighting applications at three most dangerous places in Austin.

Austin Energy spokesman Carlos Cordova announced that “criminals do not like to commit offenses in broad daylight and also in well-lit places. They do not want to be seen when they do bad things.”

According to the requirements of local Police Department, Austin Energy erected 25 pieces LED street lights in three “most dangerous places”. “LED lights are more energy efficient. That is the reason why at the same power consuming level, LED lights send out more light than other traditional lamps.” It has also been proved that, places that installed LED road lighting applications are much brighter than before. Cordova also said that “in good lighting environment, people can enjoy their recreational activities, need not to worry about security issues.”

The test results of the 8^th and the 9^th Avenue were really satisfactory. It seems that urban lighting projects also became one of a series of policies against urban crime. From 2011 to the early of 2012, the violent crime rate of Austin grew by 15%. But by July, 5 months after LED street lights have been installed, the violent crime rate only grew by 7.8%. The local government indicated that they were planning an even larger LED-technology involved city lighting project, in which around 70,000 pieces LED lamps will be updated. This project will still be conducted by Austin Energy and supported by the local government.

This new LED lighting products can reduce the crime rate effectively. Japan is the first country that applied this technology to reduce the exaggerated urban crime rate. At first, these lamps have been named as LED guard lights, gradually replaced traditional fluorescent lamps and were installed in narrow streets. Besides, it has been proved that blue-rays can make people calm down. Some LED guard lights would be made in blue light.

In the mean time, City of Pontiac, Michigan, USA also replaced some of their traditional road lamps with LED street lights. Totally 112 pieces LED street lamps (approximated $68,3800) were used.

Analysis of LED resin luminous words

Resin luminous words have several requirements for lighting sources:

1) The complex constructions and various specifications of LED resin luminous words requested that the lighting source should have versatility.

2) Since the maintenance of fully installed LED resin luminous words is extremely inconvenient, in order to reduce the maintenance cost, lighting sources should have longer service life than other lighting sources.

3) LED resin luminous words should have sufficient brightness to be readable.

Resin luminous words are mostly used in super-tine light-emitting advertising boards. Similar to other applications used for commercial purposes, resin luminous words usually need to maintain normal working conditions for a long time. In order to reduce the electrical cost, merchants were looking for lighting sources with longer service life and higher energy efficiency. LED resin luminous words emerged at this moment.

There are several things need to be noticed for using LED technology making resin luminous words in addition to the stability: setting beam angle according to the specific requirements; brightness and wavelength should within the allowed range. Only choosing right LED products in different specifications can guarantee the final effect and minimize the production cost at the same time.

Outdoor landscape LED lighting systems is a hot topic in the current society, which may impact the sustainable development of human. For the power-relied lighting industry, energy-saving green lighting technologies were always the followed direction. The birth of semiconductor green lighting sources has been considered as a great revolution in the lighting history. Gradually, semiconductor light emitting diodes (LED and order led ) transmitted from the special lighting market to the general lighting market, known by more and more people. They have good future. Among them white-ray LED lighting products have demonstrated huge performance advantages, strong momentum of development and rapid growth in market demand. LED lamps may probable become the mainstream in the lighting market in the next five years.

As one of the latest LED lighting sources, compared with other traditional lighting sources, white-ray LEDs can save more than 20% energy than the former and have much longer lifetime (100,000 hours, nearly 10 times longer than incandescent lights). In addition, they are more reliable, saving more costs in maintenance. Working under low DC voltage (no more than 5V) makes them portable. Therefore most emergency lights choose to use white-ray LEDs as lighting source.

Three development steps of LED ceiling panels

With the continuous innovation in LED lighting technology, LED gradually took place of some traditional lighting products both in the commercial area and in the industrial area. In many developed countries, LED has been treated as main lighting applications. LED ceiling panels, LED track lights, photonic crystal led ,LED bulbs, LED tubes and other LED indoor lighting applications have been widely used in some commercial places in where the over-expensive electrical bills were always a big trouble for managers. In this article, we will discuss about the three development steps of LED ceiling panels.

First step: in the very early stage of development, LED was praised for features of high lighting efficiency (low power consuming) and long service life. But the over-expensive selling prices (high production costs) drove them apart from the residential market. Most of people still could not afford them. But during this period, LED ceiling panels began to attract the attention of commercial users. Compared with traditional lighting sources, LED lamps are more energy effective and more durable. Thus they are more popular among commercial applications.

In the second stage, LED lighting applications has been recognized and accepted by the lighting market, especially for LED ceiling panels. More features of LED lamps have been gradually prominent, like environmental protection, small size, high reliability, etc. LED manufacturers developed a series of products that completely different from traditional lighting sources, extending the developing space for the lighting industry. It was in this period that LED started to be recognized as the 4^th generation lighting source. It made people realize that lighting sources did not only play the role of lighting tools any more, they were also a part of decorations of your house.

With the development of new technology (internet of things), as a semiconductor industry, LED will also catch a tour of such high-speed train and present the characteristic of high controllability. Form household decoration to office construction, from streets to tunnels, from assisted lighting tools to major lighting tools, LED ceiling lamps with intelligent control systems will bring more sophisticated services to us. Other LED lamps will complete the transformation from making products to design products, providing more comprehensive and more advanced solutions for us.

Brightness controlling design for LED street lighting products

At present, in the area of high-brightness LED street lighting drivers, there are two major solutions that widely used in the world: “special power chip” and “switching power supply with discrete electrical components”. In order to meet the needs of intelligentization, single chip microcomputers (SCM) are usually embedded into devices as the CPU. Thus both of these two solutions can be classified as “system supervisory + power controlled traditional multi-chip technology program”. However, this sort of sophisticated solution has a lot of disadvantages: multiple chips and complex constructions. When using on LED street lighting products that need to drive multiple LED strings with high brightness, this shortcoming is particularly prominent.

The new Piccolo TMS320F2802x/3x MCU adapted the latest architecture technology and enhanced peripherals. The minimum package size is 38 pins, providing 32-bit real-time control functions for low cost LED street lighting products. The real-time control are usually embedded with intelligent devices, like solar micro-inverters, LED lighting applications light solution , large household appliances, hybrid board battery industry, automotive applications, etc. to realize the implementation of advanced algorithms, higher system efficiency and accuracy.

The Buck-type switching power supply is one of the most widely used power solutions. This type of power supply can make the entire system work in the continuous inductor current mode by choosing correct output inductor and switching frequency. LED lighting Demo based on TMS320F28027 fully adapted working principles of Buck-type switching power supplies, combined with multi-PWM channels (8 channels tops) and ADC modules (16 channels tops) to realize the closed-loop control of current.

This single-chip solution for high-brightness LED street lighting products combined system management and power supply control, dramatically reducing the complexity of hardware constructions and meanwhile improving the flexibility of driver circuit designs. LED street lighting products applied this solution can automatically control multiple parameters, like current amplitude, on-off period, on-off mode, ambient brightness and system temperature by changing the memory of CPUs. They have basic properties as below:

1) Low cost – single-chip realize multiple constant current control, eliminating the need for a dedicated constant current chip, which effectively reduces the production cost.

2) High efficiency – non-insolated power supplies, without any magnetic flux leakage loss causing by transformers. The overall efficiency can reach up to 95% at fully loaded.

3) Strong driving ability – 8-channel non-isolated current driver output can drive 8 strings (not less than 14 chips per string). The total output power is not less than 100W.

Power consumption and costs control of multi-LED applications

In this article we will introduce to you an effective method to control the brightness and consequently the power consumption and costs of multi-LED applications. Providing each LED a PWM controller and converting input voltage to LED current via this controller is a traditional brightness control method for multi-LED applications. This application applied voltage-controlled PWM controllers. Usually, led pn junction will be cascade with a current-sensing resistor, which will send feedback voltage signals to controllers. Basically, this type of controllers operated in the voltage mode and maintained the feedback voltage signal at a fixed value, stabilizing the internal current.

Using multiple RGB LEDs to generate white rays is a common application. In addition to red rays, green rays and blue rays, there will be 1-2 more LED chips that used to swift LED white rays into a certain tone. In order to simulate the proportion of red rays, green rays and blue rays in the white ray spectrum, working current for these three different types of LED chips will be fixed at a certain ratio by three controllers. Normally, the output green rays occupy 50-64% of total, 25-40% for red rays, and blue rays only account for 5-15%. In this way, at least three PWM controllers are needed, which increases the production costs virtually. Each controller provides power for each colored LED. In addition, the control system also needs to change the brightness of LED lamps by adjusting the load cycle of PWM controllers.

Another approach is applying single-current driver onto theses cascaded LED chips. The brightness of each LED chip is controlled by FET switches, which is connected with these chips in parallel. When FET is turned on, current will pass through it, stopping the parallel connected LED chip. On the contrary, switching off FETs will drive the current to pass through LED chips. Another system is responsible for the control of on-time ratio of LEDs in each clock cycle, including the three cascaded single-current controlled LEDs. The brightness of each LED will be adjusted by each FET. Compared with the three individual PWM controllers mentioned above, multi-LEDs with one PWM controller but multiple FETs will costs much less and save more power consumption. Removing each PWM controller will reduce the load dramatically and reduce the power consuming accordingly.

Nine tips for high quality LED bulb drivers

1) High efficiency and less heat;

LED bulbs drivers are usually embedded within the lamp body, connected with LED chips. Thus the heat generated by LED chips and drivers will add up together, which make the cooling designs more difficult. In normally conditions, the heat generation and dissipation will be in a balance, which will be the working temperature of LED bulb. In the meanwhile, the working temperature of LED bulbs also determined the service life of them.

2) Power suppliers and long service life;

According to the bucket theory, the shortest plank decided how much water can this bucket hold. Power supplier is the shortest plank of LED lamps when judging its service life. Thus for many LED manufacturers, designing or choosing a right power supplier is significant for LED lights.

3) Small current pulse amplitude;

Current pulse amplitude is another important parameter when judging the quality of LED bulb drivers. Normally, small current pulse amplitude can not only improve the quality of the illumination but also prolong the lifetime of this device, thus extending the life time of LED bulbs.

4) Internal current with high frequency;

Current ripple with high frequency can reduce or even eliminate flickers, which will be captured by human eyes and cause damages. Certainly, high quality LED bulbs should not have substantial current ripple.

5) High power factor;

Improving the power factor of LED bulb drivers can increase the energy efficiency of power grid, reducing invalid loss. At present, many countries have their own regulations for the power factor of electrical appliances, including LED lighting products. For example, according to the related standard of Germany, every electrical devices that imported into Germany should have a power factor larger than 90.

6) Electrical isolation;

LED drivers are usually powered by the power grid, directly working under high voltage AC. While LED work under DC. Electrical isolation is necessary between them. Normally, designers will design isolated circuits between the input end and the output end of LED drivers.

7) Protection;

Generally, LED derivers should have protection measures for over-temperature and over-current.

8) Small size;

Generally LED bulb drivers are small sized, since only small drivers can be integrated built into LED bulbs.

9) Low production costs;

Low costs will have good market performances, which is the universal law of the Chinese market and cannot be varied in the short term. LED companies must adapt this.

LED lighting source will change the style of indoor decoration

Lighting is always one of the key points in the residential decoration, a crowning touch at which housewives are hard working. Lighting sources are definitely the most important part of LED lamps. For example, most people would like to use crystal lights, thus energy-saving lamps are definitely not suitable for them. Because of the narrow spectrum and weak penetration of energy-saving lamps, it is very hard for them to present the glittering and translucent of crystal lamps. Thus housewives that loyal to crystal lights have to choose incandescent lighting sources, since the refraction of crystal can make incandescent light more bright and colorful. However, the exaggerated power consumption of incandescent lighting sources is also heartbreaking. In order to avoid expensive electrical bills, many housewives choose to shut off these lamps until guests’ visits. Spending a lot but obtaining a little, it is really an unspeakable feeling. These embarrassing situations have not been improved until the invitation of the LED lighting source.

LED lighting source have many advantages: long service life, good light penetration, high energy efficiency and environmental friendly. Most residential LED lights such as outdoor led spotlights are small sized. They brought new concepts to lighting designs.

In the past, lighting designers needed to consider of many factors during the designing process, like the translucent effect of lampshades, the artistry of lamps, the strength structure. In addition, they had to take into account of the spatial position of lighting sources and visual influences. Among these, it is the visual influences caused by lighting sources that drove designers crazy mostly. The light-emitting part of LED lamps is LED chips. Compared with the large sized lamp body, their size can be ignored (cooling maybe the only problem needs to be considered). That means the whole lamp body is equivalent to the lamp. Neither chips nor wires will bring no visual influences. Using LED lighting source, designers can only focus on the design of lamp bodies. The final results are much better than using energy-saving lighting sources or even incandescent lighting sources. In addition, designers also can choose to use multiple LEDs as lighting source, which provide more imagination space for them.

LED lighting source will change the style of indoor decoration and also the LED lighting market. Far-sighted LED producers should foresee this and prepare in advance.

Southeast Asia and Africa: emerging markets for LED lighting applications

In 2012, the gross market size of Thailand lighting market is approximate 250 million USD. The LED penetration rate is around 10%. It is estimated that by 2015, the penetration rate of LED lighting applications in Thailand market will increase to more than 45%. Currently, the Thailand Government is actively planning a series of city lighting projects by using LED lighting applications. A lot of local LED makers and LED manufacturers from other regions, especially from China and Taiwan have engaged into these projects. China’s LED companies mains led lighting with local certificate of origin can enjoy a zero tariffs when exported their products into Thailand. But lighting sources that exported to Thailand still need to provide the local certification.

Since most regions of Thailand have a tropical monsoon climate, hot and rainy, LED lighting applications that exported into this country should strengthen the protection of heat and moisture. LED manufacturers need also take into account of exporting LED emergency lights, LED flashlights and other portable LED devices to Thailand.

The Vietnam Government has recently announced a draft of “2011-2020 plan for the national urban development”, hoping to realize a 38% urbanization in the whole country in 2015. Thank to this draft, Vietnam has been considered as another emerging market for LED lighting applications in Southeast Asia. A large number of LED producers from the mainland and Taiwan region have entered into this market, promoting public lighting concepts and industrial lighting products.

In Africa, about 90% rural population is lacking of electricity supply. Small streets or country road are illuminated by nothing. Basic lighting market and municipal lighting market are the two most potential markets in Africa, waiting for development. For a long time, the lighting market of Africa has been in a low-level stage. They do not have many strict requirements in product performances and functions. Products with low production costs, basic lighting functions, longer service life and simple operation can fully meet the need of local markets. United Nations have launched a series of development lighting programs in Africa, supplying more energy efficient LED lighting applications to users from Africa. Off-grid solar LED lighting products, indoor and portable LED lamps, 1W-5W solar LED bulbs and LED emergency lights are very popular in African market.

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月份：2012年10月