月份：2012年8月

How to produce LED chips by using photonic crystals LED

Photonic crystals have three chemical features, can be used in various areas through manual controls. 1) Block the light through optical energy gaps. Usually, technicians utilized this characteristic to lock light in a fairly narrow region, like integrated circuit. 2) The photonic crystal anisotropy of photonic crystals. Light emitted from photonic crystals will be scattered in different directions. Because the translucency of photonic crystals is variable with the polarization of the light. Thus the light transmitting and the light blocking occurred alternatively. 3) The curve of photonic crystals is complicated changeful. Because of the fast and irregular changes of photonic crystals curves, slightly changes in we light wavelength will cause huge angle shift of the input light. The biggest advantage of photonic crystals is that their size are much smaller than 1/1000 of integrated circuits. In another words, the integration will be 1000 times higher than before. Besides, the refraction coefficient will be 1000 times larger than more, as well.

 

Photonic crystals have three chemical features, can be used in various areas through manual controls.

 

Photonic crystals have other features. In fully use of these features can create photonic crystal LED. These LED lights can be divided into two major parts: (Light Emitting Diode) LED and Laser Diode (LD). LD can continued to be divided into Photonic crystal DFB LD and Photonic crystal defect LD. The DFB value of Photonic crystal DFB LD can be maintained in a rather low level to complete the lunch, with which we are very familiar. This structure must have optical energy gaps. It is very hard to achieve commercialization under such circumstance.

 

However, creating photonic crystals LED is much simpler. Some people may confuse this process with Photonic crystal DFB LD and consider of using specific frequency or wavelength and create photonic crystals LED. The answer is no. The incident and diffracted light of Photonic crystal DFB LD and Photonic crystal LD is limited. It is impossible to make use of certain frequencies or wavelength to enhance efficiency. This property is rather important for LED.

 

During the creating process of photonic crystals LED, scientists found that the application of transparent electrodes has litter effects on the final lighting efficiency. According to this result, scientists usually covered a tiny layer of transparent electrodes on photonic crystals. Use sapphire as substrates. And then create photonic crystals LED through MOCVD, EB and RIE ETCHING process.

Common sense of buying LED spot lighting products

The color temperature of the interior lighting can be divided into three groups: 1. Less than 3300K, which is also defined as Warm White. This soft light can make people a warm and comfort feeling, typically used in living rooms, bedrooms, wards, bars and restaurants. 2. 3300K-5300K, Natural White. This light is quite closed to the sunlight and has the highest CRI, suitable for working places and labs, like offices, classrooms, libraries, consulting rooms, laboratories, processing workshops, etc. 3. Larger than 5300K, Cool White. This color can provide the brightest light compared with the other two colors, mostly used in hot processing workshops and high illuminating places.

 

The color temperature of the interior lighting can be divided into three groups: 1. Less than 3300K, which is also defined as Warm White.

 

Usually LED spot lighting products are used as interior lighting devices. Thus their color temperature choices are concentrated on 2700K, 3000K, 4000K and 5700K. The “GB50034-2004 architectural lighting design standards” explicitly indicated that the CRI of lamps used in long-used working rooms/places should more than 80. In industrial construction sites with a light fixture mounting height more than 6m, CRI can be less than 80.

 

During the purchase of LED spot lighting products, costumers should carefully read the instructions and packing information provided by manufacturers, checking the input voltage and related production parameters. These parameters included luminous flux, color temperature, power consumption, CRI (color rendering index) and beam angle. This first thing need to be noticed is whether the LED spotlight can work under AC directly or need a transformer. Normally, LED spot lighting products have four bases: E27, E14, GU10 and MR16, in which MR16 based lights should work under DC (normally 12V). Secondly, customer need to check the light head and beam angle, comparing with their own requests. In the last step, customers need to choose suitable color temperature, CRI according to the “GB50034-2004 architectural lighting design standards” to achieve a reasonable lighting effect. If buyers had little or no acknowledge in light fixture’s parameters, they can check the equivalent marks on wraps. There will be some general estimation of what Watt traditional lamps can be replaced by this LED lighting products.

 

As for MR16 spotlights, which are usually equipped with an electronic transformer or frequency transformer, customers need to make sure the compatibility of them before purchasing the light. The incompatibility will cause flickers. As for spotlights with SCR dimming function, customers need to consider the compatibility between dimmer and lamps.

The standardized interfaces of LED spot lighting products

LED spot lighting products were mainly produced to replace the traditional halogen spotlights. Restricted by the traditional light shapes, light heads and installation methods, the design works of LED spot lamps are harder. Within the range of existing spotlights size standards, it is difficult to make these lamps in high power consumption and high luminous flux. In the mean time, there are other design difficulties in light distribution, heat dissipation, electrical security, etc. Under such circumstances, the properties of long service life, high lighting efficiency cannot be fully expressed, which exerted a negative effect on the healthy development of LED spot lighting products.

 

LED spot lighting products were mainly produced to replace the traditional halogen spotlights.

 

LED is a new lighting technology. LED spotlights are one of the oldest LED lighting applications. It is necessary to draw up a new set of interface standards for them in accordance with LEDs’ properties. Lay out explicitly terms for product dimensions, modular blocks, electrical and optical parameters and interfaces, realize the modularization and interchangeability of LED spot lighting products and promote the development.

 

Presently, the international ZHAGA Union attracted hundreds of manufactures and industry enterprises from lighting, lighting source and LED module fields. The majority of them are from North America, Asia and Europe. ZHAGA Union was committing themselves to improve the LED lights modules and the compatibility of controls within machinery, tests and parameters. A large number of relevant technical specifications have been published and modified for several times.

 

As LED technology matures, costs reduces, LED lighting products has acquired an initial popularity. A lot of LED lamps have been applied in various occasions. However, the development and popularization of LED spotlights still faced with problems. How to solve the cooling problem of LED spot lamps with high power consumption and high luminous flux? How to realize the modularization and interchangeability? How to fully present the advantages of LEDs: long service life, high lighting efficiency, controllable, etc. In order to solve the cooling problem and the power supplier problem, many producers will design lamp shapes without following the IEC 60630 standard.

 

As the main force of interior lighting applications, LED spot lighting products were responsible for making people’s life brighter and more colorful. Producing lights which are more cost-effective and more reliable still needs endeavors of LED manufacturers.

The growth rate of Russian LED lighting market will exceed 28%

In accordance with a recent research report published by Economic Research Center of Moscow University, the growth rate of Russian LED lighting market will exceed 28% in 2012. In fact, an increasing number of industrial giants (including Philips, NVC, OSRAM, etc.) put forward various marketing plans to exploit Russian LED lighting market. In their point of view, it is an emerging market with powerful potentials. In the mean while, experts concerned about the industrial competitions will destroy the early booming of this market. After a set of comprehensive researches, economists of Russian concluded two characteristics of their lighting market.

 

The growth rate of Russian LED lighting market will exceed 28%

 

1)       The fluorescent tube market of Russia had a large maintain volume, but lacking of advanced recycling technologies and facilities. The wasted lead and mercury of scrapped tube glass caused serious and long-term damages to environment. In order to figure out some effective solutions for this problem, experts suggested that some processing centers should be established, the number and size should refer to the capacity. For the reason of lacking of capital, the growth rate of selling is further exceeded to the growth rate of recycling. The environmental issue will become the “bottleneck” that block the development of fluorescent lighting products in the long run.

2)       The pursuit of profit has become one of the biggest obstacles of the market. The majority of Russian LED manufacturers competed for the lucrative professional lighting market, but paying much less attention to the mass energy-efficient lighting market. At the same time, the mass market had not been ready for a complete energy-saving-oriented transforming. Since Russian LED lighting market is an emerging market, ­­­most products sold in high prices. A standard LED lights cost 50 times more than ordinary incandescent lamps and 10-15 time more than fluorescent lamps, causing these products hardly be accepted by ordinary people. However, dealers did not take it seriously. They are more willing to concentrate on large public procurements of energy efficient lighting project, since these orders were mainly from buyers from public industries (like railway industry, chemical industry, electric power and oil industry, storage industry and public construction, etc.) who with “deep pockets”. Take Esi Waite Lanna photoelectric enterprise for example, this company have already signed more than 100 lighting contracts with Russian railway company.

Drivers and cooling section of LED spot lighting products

At present, most LED spot lighting products used embedded drivers (power suppliers). This type of lights was named as self-ballasted spotlights. The embedded drivers usually adapted switching power suppliers to realize the power on/off. These drivers can be divided into two parts: isolated and non-isolated. The first and second level of isolated power suppliers are blocked by a small electrical interlayer. In the design of LED spotlights, designers only need to consider some effective ways to isolate the first level circuit and the sell from human bodies (full protection is needed) to prevent an electric shock. While the second level circuit worked under safety voltage, only simply protections are needed. Relatively, this type of power suppliers has less risk possibility, but in the case of larger space and lower efficiency. Another type of power suppliers is non-isolated. That means between first level circuit and second level circuit, there is no isolated blocks applied. Thus this type of power suppliers required more strict protection measures. Tiny mistakes may cause serious damages. Non-isolated drivers have their advantages, such like higher efficiency, small size. There are many other LED driver techniques used in LED lighting industry. But they have lower security and reliability compared with isolated/non-isolated drivers. Besides, due to the built-in drivers, the working temperature of electrical components is higher than the normal, which will direct impact the durability and reliability of LED lights, including LED spot lighting products. In order to solve this problem, many companies adopted a way of filling plastic to improve the cooling capacity of power suppliers, and improve the thermal insulation between built-in circuits and cooling shells.

 Drivers and cooling section of LED spot lighting products

Because of the controllability of LED devices, a large number of manufacturers designed and produced dimmable LED spot lighting products. The existing dimming methods can be classified as: SCR dimming, PWM dimming, 0-10V dimming, DALI dimming, DMX51dimming and power line dimming etc. All these methods are capable of changing the brightness of LED lights by controlling the input current or input voltage of drivers.

 

Cooling devices are the biggest challenge for LED producers. The majority of cooling sections (heat sinks, heat fins) were made of aluminum alloy, through organic processing and molding. In the design of high-power LED spotlights, designers usually utilized heat fins.

Outdoor LED display media have irreplaceable value in outdoor applications

Among all advertising media, outdoor advertising is the oldest one. It was born together with trade and rooted in the city, which is closely related with people’s economic activities, cultural and social life. It is the promoting media of brands and products and also a bright sign of city’s prosperous. These characteristics formed the unique and irreplaceable value of the outdoor media.

 

Outdoor LED display media have irreplaceable value in outdoor applications

 

As a new information terminal, outdoor LED display media developed and rapidly spread all over the world in 1990s. This technology combined with modern high-tech, having advantages of energy-saving, environmental friendly, multi-color, able to display dynamic images and test, a wide range of sense, etc. Outdoor LED display advertising normally has large screens, shock visual effects, can fully attract the attention of the audience.

 

Outdoor LED display media also has the advantage of high effective reaching rate, and less cost compared with other media, like TV, newspaper, magazine, etc. The Times Square and nearby CBD core area of New York, the Ginza of Tokyo have been fully decorated by numerous outdoor LED lights screens, continuously playing advertisements, news and other entertainment shows, sport event reports in 24 hours. These LED screens play an important part of merchandising and also, the brand symbolic of famous companies. Enterprises only took dominant places in the industry are be able to broadcast advertising on these special LED screens. Broadcasting advertising is a way of emphasizing the global influence of their brands.

 

Unlike traditional outdoor media, full-colored outdoor LED screens do not only serve for commercial purpose. They also have properties and advantages of TV and other communications media. However, full-colored outdoor LED panel light screens are not just a derivation of traditional outdoor media and communications media. They have larger creative spaces and interacting spaces with customers, with new transmitting concepts in the digital age.

 

As the main force of security monitoring, the market development will directly impact the direction of security industry. Outdoor LED display media give LED display industry unparalleled advantages in sporting area, which had already been fixed as a main developing direction of outdoor LED applications. With the further improvement of LED display technology, it is believed that outdoor LED screens (led projects) will bring more convenience to our daily lives.

The developing prospect of LED display industry

1)       The deepening and diversification of products. Chengdu in Sichuan Province of China has a relatively sophisticated LED display industry. LED display manufacturers there have advanced LED lights display products and core technologies with international levels. However, they are weaker in product processes compared with overseas competitors, having obvious disparities in product standardization, the complete system design, reliability, manufacturing processes and tests. The constant improvement of LED display technology and LED displays’ performances provided a good foundation for the deepening and improving of Chengdu LED display industry. In the mean time, LED display applications have been widely used in various areas of social life. The development of semiconductor lighting industry offered more opportunities to this area. Thus most people expected that LED display industry have a positive developing prospect in China.

 

he deepening and diversification of products. Chengdu in Sichuan Province of China has a relatively sophisticated LED display industry.

 

2)       Standardization of the conventional products and specialization of specific applications in professional fields. The implementation and promotion of relevant standards will stimulate the standardization of LED display products. Among conventional LED display products, standardized displays and control systems will receive more rapid developments. It is expected that in next ten years, integrated LED display products will share most part of the market. The standardization of LED displays and the specialization of labor division of marketing services will become more obvious in next several years. In professional applications, in order to meet the requirements of professional applications, the level of specialization will continue to increase, combined with specific application requirements to form new LED display technology, such like large-sized LED displays used for city lighting engineering, the stadium’s LED displays and LED displays for transportation area. It is expected that LED display industry may usher in its peak in near future.

3)       Rational division of labor within the industry and the formation of new industrial patterns. In the entire industry chain, the establishing of leading enterprises of LED display products will redefine the labor diversion of upstream and downstream industry, highlighting specialized labor diversion and collaboration. Perhaps, in the early stage of semiconductor lighting industry, manufacturers of LED components and display products may present vague boundaries between specialized labor diversion and collaboration. But with the continuous development of market and technology, these boundaries will become clear.

Analysis of LED photonic crystal technology

In order to avoid the Blue-ray LED lights and phosphor technology patent of Nichia, many LED manufacturers involved into researches of other White-ray emitting LED technologies. Currently, UV LED is the most anticipated technology among all. But it has two fatal defects: light leakage and low brightness, which will be hard to overcome in the short-term. Scientists was striving to solve these problems and meanwhile looking for other effective solutions to send out White-rays.

 

In order to avoid the Blue-ray LED and phosphor technology patent of Nichia, many LED manufacturers involved into researches of other White-ray emitting LED technologies.

 

In 1987, two scientists from different country Eli Yablonovith and Sajeev John find the breakthrough almost at the same time. Theoretically, they found out that the periodical propagation state of electromagnetic waves in dielectric materials had band structures. They used two or more materials (with different refraction coefficients/dielectric constants) to compose the substance that contained photonic bands. The Photonic Crystal technology has been exiting for 20 years. Nowadays, it is the one of the most important core technologies which is highly concerned. This technology can be used in many other industries beside the LED lighting industry. Using second order photonic crystals to achieve White-rays was proved feasible. LED photonic crystal technology has become the focus of public attention and expected to be an effective method to get rid of the Nichia’s patent problem.

 

In following sections, we will discuss about the general construction of photonic crystals. Photonic crystals may have different periodic structures with different wavelengths, can be developed into first order crystals, second order crystals and third order crystals. Among these structures it is third order photonic crystals that have the most useful functions and can be used in various areas. But the manufacturing and commercialization of third order photonic crystals are almost impossible according to the current technology. Thus, instead of third order photonic crystals, it is second order crystals that are widely used in many industries, including LED lighting industry. The current LED photonic crystal technology is actually based on second order crystals working principles.

 

Generally, normal materials have fixed constructions, so these materials have a certain level of refractive coefficients. When electromagnetic waves travelled through these media, the wave number and frequency of these waves will impact the original refractive coefficients. Since photonic crystals have periodic structures, thus when light went through them, there must be multiple refractions.

Requirements of LED spot lighting technology

Current LED spot lights are mainly used to replace traditional halogen lamps. Among LED lighting products, LED spot lighting technology has a relatively long developing history. A series of comprehensive standards all referred to the traditional lighting requirements and also be in accordance with the properties of LED lamps. At present, the two major authorized Certification of LED spot lamps are CE Certification from Europe and UL Certification from America.

 

Current LED spot lights are mainly used to replace traditional halogen lamps. Among LED lighting products, LED spot lighting technology has a relatively long developing history.

 

CE Certification includes two parts: LVD(EN60968) and EMC(EN55015, EN61547, EN61000-3-2 and EN61000-3-3). Besides LED lights usually need to satisfy IEC 62471 standard and conducted photobiological tests. In north America, UL Certification and FCC electromagnetic compatibility Certification are necessary.

 

In addition, LED spot lighting technology have many standards in performances. America has ENERGY STAR requirements and China has energy-saving requirements. These standards had strict limitations on color temperature, CRI, initial luminous flux, lighting efficiency, central light intensity, standard working power, power factor and so on.

 

The service life of many electrical appliances was judged by “broken time”. LED is an advanced lighting source that may work for a long time without any failure. But its light intensity will be receded with time. We named this phenomenon as “light attenuation”. Normally, in LED lighting industry, technicians will define the service life of LED as the working period until light attenuate to 50% of the original light intensity. With the development of LED technology, light attenuation has been dramatically slowed down. However, giving out a specific time of LEDs’ service life is infeasible. Currently, scientists can only estimate this value by a set of tests. Basically, this process begin with a series of short-term aging tests, taking average value of light attenuation, then estimate the general time of light attenuating to 50% through exponential functions.

 

Usually, take measurement of Lumen Maintains (LM) after a 6000-hour aging test. In accordance with the exponential law, if LM>91.8% after the 6000-hour aging test, then the estimated service life of tested LED will be 25,000 hours. If LM>94.1%, then the estimated service life will reach up to 35,000 hours. The estimated time should no more than 6 times of the aging test time. Therefore, 36,000 hours will be the maximum estimated service life for a 6000-hour aging test. If you obtain a final LM result larger than 95%. That means you have to extend your aging test’s time.

LED bridge lighting used on the new bay bridge in San Francisco

The new bay bridge in San Francisco is under construction, and expected to be open to traffic before the end of 2013. Last Thursday night, the new bay bridge bathed in radiant white light, attracting a lot of travelers and passengers stopped to watch from afar. The soft and bright light was provided by the thousands of LED lamps installed on the bridge. “Since LED is a kind of one-direction lighting source, the light generated by them is more soft, without any infrared and ultraviolet rays or flickers. ” Said Mr. Shelly, one member of the design group, “Another reason for using LED bridge lighting is that they can effectively reduce the traffic accident rate because of lacking of glares.”  Electrical contractor Bleyco is responsible for the lighting part of this $7 billion project. They joint up with famous lighting producer Musco and applied the most advanced bridge lighting system in history.

 

LED bridge lighting used on the new bay bridge in San Francisco

 

The initial design concept was to use advanced directional lighting technology to provide carriageway solid white rays for drivers. In this way, glares on zebra crossings and windshields can be eliminated to a large extent. In 2008, it was the first time that Bleyco had contacted with Musco. But, unfortunately, such lighting technology has not been developed at that moment. Not until the end of 2009, Musco put forwards a LED lighting plan, which was proved feasible and received positive responds from Bleyco. But in 2009, Musco was still lack of core technology to control multiple LED lamps by one chip. They conducted a series of experiments on 25-50 pieces Cree XM-L LED street lights built on one country road in Ohio. The LED bridge lighting system of new bay bridge is very special: each lamp pointed to different directions, with different “cap” and different lens, equipped with several layers of metal plates at the top, sandwiched between nylon to suppress the vibration. The pentagonal shape design matched up with the central tower of the bridge, seven fixtures on each pole represented the seven pillars on the central tower. Not only that the entire lighting system has long service life but also it is safer and more beautiful.