日期：2012年8月28日

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.

London Olympics: outdoor LED display industry had special performance

During the London Olympics, outdoor LED display technology has been widely used, that left a deep impression to people all around the world. Since 2009, large-sized outdoor LED displays have emerged in the market in many countries and gradually became a main force of the display industry. Outdoor LED display industry was always the target of being propped up and have become the important constitutes of large entertainment, sporting events and Square Theme Shows. With the continuous applying of new technologies, the new-formed outdoor advertising continued to emerge, full-colored LED tubes display media resulted from this trend. In this article, we will give a small talk about the market prospect of outdoor LED display industry.

 London Olympics: outdoor LED display industry had special performance

Outdoor LED displays as a type of high-tech products and also the trend of the next generation of LED display applications. They have two obvious merits: longer service life, lower power consumption, higher lighting efficiency, etc.. These properties much more sophisticated than other traditional display products. As an emerging industry, LED has come into an integrity and maturity chain of the industry. The layout of the outdoor LED display industry supply chain mainly performed in five aspects:

1)       Currently, there are no biddings in upstream business (raw LED lights materials like sapphire, MO sources). Industry experts paid more attention on some upcoming enterprises.

2)       Midstream: the fierce competitions in chip industry cause overcapacity of the market. Attention was more focused on high-power, White-Ray LED companies.

3)       Downstream: packaging industry still focused on White-Ray, COB factories.

4)       Too many LED lighting application manufacturers, those who had transporting channel advantages or benefit from the government support policies may have a more smooth development.

5)       LED equipment and instrument industry. Less biddings. Similar to upstream industry, upcoming companies with more advanced production line and product process received more attention.

In the view of global point, most core technology of LED panel display techniques are still controlled in the hands of giant international companies. In the backdrop of the global energy conservation, many counties have issued filament-forbidden plans and started to promote LED technology. Thank you to current support from the government, outdoor LED display industry will enjoy a rapid development in the future.

Japan introduced railway LED lighting and new semiconductor technology

Japan’s railway enterprises have applied themselves to energy-saving area for many years. Compared with other transportations, transportation energy consumption per capita of railways is the lowest one. For instance, transportation energy consumption per capita of the Shinkansen is only 1/25 of that of aircrafts. In order to achieve a more environment friendly effect, the Japan Government decided to replace all traditional railway lighting systems with railway LED lighting technology.

 

Japan introduced railway LED lighting and new semiconductor technology

 

Take Ginza Line “1000” for example. In order to improve the ride comfort, designers increased the output power of air conditions within compartments. Meanwhile installed 17-inch widescreen LCDs to improve the audience effect. After strengthening these functions, the total power consumption of the entire trains grew up numerously. Thus, Ginza Line “1000” adapted a series of technologies with more powerful energy-saving functions. One of them is railway LED lighting technology. Tokyo Metro explained that it is the first time that LED lighting technology was employed in railways in the human history. They also indicated that LED lights would be continued to applied in other public transportations, such like subways, buses, and even some taxies.

 

The new installed LED head lights for trains are only 32W each with two other assisted lamps, which are 16W each. But they provided equivalent brightness to previously used 150W high pressure sodium head lamps. Compartment lights also guaranteed the brightness that equal to or larger than the previously used fluorescent tubes but consumed only 40% of them. The average service life of compartment lamps is around 40000 hours, which is 3.5 times of traditional fluorescent tubes.

 

Beyond that, designers from Tokyo Metro also needed to take railway stations and other ancillary facilities into account. How to effectively reduce the power consumption is as important as that for trains.

 

Presently, in order to cope with the income reduction caused by the low birth rate and the aging problem, Japan’s railway operators engaged in transportation business and meanwhile strived to expand non-transportation business. The ongoing activities included additional shops and other commercial facilities in stations, enlarged the digital signage and improved the high-speed communication network. The power consumption of these facilities occupied an increasing proportion of the total power consuming. Station power consuming accounted for approximately 20% of the commercial power arrangement of rail operators. In order to prevent this trend, rail operators started to apply photovoltaic system and railway LED lighting technology on stations.