月份：2012年10月

The working principle of LED wall washer

With the development of high power LED lighting technology, high power LED lighting applications have been widely used. High power LED wall washer is just one of the most favorable applications. In this article, we will introduce to you some basic knowledge of LED wall washer and their working principles.

 

With the development of high power LED lighting technology, high power LED lighting applications have been widely used.

 

LED wall washing lights are also called linear LED flood lights, as a result of the long strip shape. This type of lights is usually used in the architectural and decorating lighting area. They have very similar functions with LED flood lights, outlining the contours of large buildings or walls, and also very similar technical parameters. The only difference is the shape of the spot. LED flood lights have circular spot, while the stripe structure of LED Panel Light wall washing lights make the cooling work become easier.

 

Currently used LED wall washer basically use 1W high-powered LED tubes (each LED tube has a PMMA lens with a high luminous efficiency, the main function of which is secondary distribution of the light emitted by LED tubes). These tubes are single-line arranged. Most LED wall washing lights use same heat radiator with LED tubes. However, there are some manufacturers will apply separated cooling devices for these them. There are two general beam options: narrow (about 20 degrees, with the farthest projection distance of 15-20 meters), medium (50 degrees) and wide (around 120 degrees). The normal power specifications are 8W, 12W, 24W, 36W. The normal length specifications are 300mm, 500mm, 600mm, 1000mm. Buyers can choose different length and power density according to their specific engineering applications.

 

High-powered LED wall washing applications have two control modes: internal control and external control. Internal control mode needs no external controllers and embedded multiple changing modes (six tops), while external control mode needs external controllers to change the color, but can have hundreds of changing modes. Thus LED wall washing applications on the current market is usually external controlled.

 

LED wall washer realized the automatic control through the built-in microchip, achieving a series of lighting effects: gradual transition, color flashing, random flashing, alternating dynamic effects. All these functions can also be controlled by DMX consoles. The main application areas: the monomer architecture, historical buildings, indoor/outdoor lighting, green landscape lighting, billboard lighting, medical/cultural/specialized facilities lighting, bar and other entertainment atmosphere lighting.

Comparisons between LED grow lamps and HPS

Scientists have already developed a series of plant-gardening lighting technologies. LED grow lamp is one of these technologies, which is usually compared with traditional HPS (high-pressure sodium lights). LED grow lights combined red rays and blue rays. Normally, they will be settled on the ground, or places near plants. What are the differences between LED grow lighting products and HPS? What advantages that LED grow lights have?

 

Scientists have already developed a series of plant-gardening lighting technologies.

 

1)       Plants under the LED-light will grow faster. Various data shows that LED grow lamp is a superior technology, which make plants grow better and faster. The Department of Horticultural Science of the University of Minnesota has recently published a related study report of plant lighting. In this study, LED grow lights and LED Panel Light HPS have been comprehensively compared in different conditions. They compared plants (after 7 weeks) from two different local plant bases using these two kinds of lamp relatively and found out that, the average growing speed of LED-used plants will be higher than that of HPS-used plants. The difference is noticeable.

 

2)       LED costs less. Indeed, the initial production cost of LED lamps is usually higher than that of HPS lighting sources. But if take the operation cost into account, high-quality LED grow lamps can save more money in this part. With the same output luminous flux, high-quality LED grow lights consume only 1/8 of energy that HPS needed, and more durable than HPS. Usually, grow lights should work in 24 hours. In the long term view, the initial cost of LED light sources can be ignored.

 

3)       LED grow lamps are lighter. Traditional grow lighting sources are relatively heavy, since HID, MH and HPS need ballasts to maintain a normal working condition; reflectors to concentrate light towards plant pools; other assisted tools or equipments. Gardening lamps usually need to hang on certain places, like the close top of plants. The weight is a must-be-considered factor. Some high-quality LED grow lights have embedded ventilators, negating the need of air-cooled reflector or pipelines.

 

LED grow lamps make things much easier, generating sufficient red and blue rays that needed by plants, intelligent self-control system and manual adjusting system, saving more maintenance and replacement cost for users.

The future of LED lighting technology

Here in this article, we will continue the interview of Professor Holland Yake from the University of Illinois, who is an expert of laser and light emitting diode (LED Panel Light ). The topic of today’s interview is the future of LED lighting technology.

 

Here in this article, we will continue the interview of Professor Holland Yake from the University of Illinois

 

Is there anything we can do to improve the LED lighting technology?

 

There are a lot of things that we can do to make them more competent to be the best and brightest lighting source in the world. Currently, we are looking for better wafers, committing crystal chemical researches, etc.. I made an alloy in GE. Then I made other semiconductor alloys, they are getting better. They can emit red-orange light, and also yellow light. Some other people who were doing similar works tried to use other types of alloys, which are able to send out blue rays. But when they tried to convert these blue rays into green, they met with big problems. No one presently can solve this problem very well and obtain yellow rays.

 

After these years development, has LED been the mainstream lighting source?

Basically, LED is beginning to take over the lighting market, from special lighting to ordinary lighting. For now, the whole world is using this technology, in various forms and various colors.

 

Is it possible for us to see the continuous growth of LED lighting technology?

You can treat them as a kind of lighting source, but also can use them as laser, just like in the field of surgery and photosensitizing. This is the biggest feature of LED, since incandescent bulbs cannot do these staffs. You can use LED to make a lot of things, both in the medical area, the instrumental area the automobile area. All lights used on vehicles can be replaced by LED lights. As a matter of fact, LED lamps are more advanced in automobile applications due to their small sized and flexibility in forms and designs. LED headlights and taillights are more durable compared with traditional high-pressure sodium lamps. This is not the end of the story. To be honest, LED is in her infancy. It seems that LED has already stepped into her adolescence, but trust me, she needs more time to grow up. The only thing we can do now is just wait.

History of LED lighting technology

As early as 1962, about 50 years ago, Nick Holonyak together with his team in GE developed the first Light Emitting Diode (LED). Today, LED lighting technology can be seen everywhere in the world – from bridges to vehicle headlights, from keychain to flashlight. As the 4th generation lighting source, LED is even supposed as the lighting source that brighter than the sunlight. But the initial research and development works were full filled with uncertainty and competitive. At that moment, LED lighting technology was just a result from another pioneering technology – laser. However, in the followed days, LED Panel Light has been in the constant evolution and now has been one of the major lighting applications in many areas. What the history of LED? About this question, reporters interviewed Professor Holland Yake from the University of Illinois:

 

As early as 1962, about 50 years ago, Nick Holonyak together with his team in GE developed the first Light Emitting Diode (LED).

 

What the initial reaction that LED received from the market?

When I noticed that I am working on the way of LED development, I have already defeated the entire world by applying my alloy technology in the field of laser. One editor of the “Reader’s Digest” called me in February 1963 and pointed out to me that LED lighting technology will one day cover the entire spectrum and become the most suitable lighting source for white-rays. I believed his words. But in my opinion, this will take more than 50 years.

 

About the Laser?

It has been recognized for a very long time that light has no coherence. Otherwise, they cannot be captured by our eyes. Since human eyes can only sense incoherence light. In 1962, Lincoln Laboratories of MIT was still under the leadership of Robert Rediker. They invented a kind of diode that can self-emit multiple rays and used it to send out IR signals. When they published a copy of relevant report in July, we predicted that this new device will make the coherence light be possible.

 

How big is the first LED?

Very small. Of course, if you want, you can make it much bigger. Actually, people are now doing this job. You know, in the area of semiconductor application, semiconductors are always the final winner and swept the electronic products.

 

What was the original LED looks like?

LED you see today is on a relatively cheap platform, which is just a formality. In fact, LED can be made in various forms, various colors, various geometries.

Future development: low carbon applications of OLED display technology

Working principles of OLED is sandwiching an organic light-emitting layer between two electrodes. The collision of positive electrons and negative electrons will generate photons. OLED screens have very strong anti-interference capacity, showing clear images even in the strong sunlight. OLED is free from lead, mercury, cadmium and other harmful materials. In addition, the energy consumption of OLED is much smaller than LCD and plasma display devices and has been globally recognized as the most green low-carbon equipment in the display industry.

 

Future development: low carbon applications of OLED display technology

 

OLED display technology has the followed advantages:

 

1)       Thinner, clearer, brighter;

The unique production process gave OLED a lot advantages compared with other traditional display devices, thinner, clearer, brighter, lighter weight and lower manufacturing costs. The panel structure and divers of OLED screens are all under accurate calculations and special designs. Technicians can maintain the thickness of OLED screens within a relatively thin level and meanwhile make them high-brightness, high-resolution and high contrast. OLED is self-luminous without any backlight. OLED display technology consumed much less power than LCD, but the optical output is three times than that of LCDs.

 

2)       Ring, ribbon, and other curve surfaces heterosexual installations.

OLED display system uses a unique modular structure, which can be customized as any size or shape (ribbon, ring, erected, spherical, etc.), any ratio of height and width, seamless stitching. Spaces and places where display applications were totally incompetent, nowadays have been installed all kinds of large-scaled OLED screens. OLED display technology provides more creativity for designers in space design.

 

As a new generation display technology, OLED has high-brightness, consume less power, can work under low input voltage, have longer service life, have high impact resistance and stable performance. OLED screens have been widely used in the advertising and commercial area. Presently, many domestic manufacturers started the research and development works for OLED display technology, including the TV News giant CECV. In the near further, mature OLED and LED Panel Light products will finish the process of commercialization and be put on the market. OLED display industry and application market is enjoying a rapid development. Thank to the highly sophisticated stability and product performance, OLED screens with high quality and high IP level have already been used in the field of intelligent traffic security system. It is believed that OLED display applications have broader prospects in the security area.

Intelligent applications: LED traffic guidance screens in the intelligent transportation

The production and application of LED traffic guidance screens involved multiple technologies, including: semiconductor, optoelectronic technologies, integrated circuit, image processing and transmission, computer network communication, and manufacturing of electronic products. LED screens of different types and different performances will have huge differences in the aspect of material constitution, production process and control. Even products with same types and same performances but from different manufacturers, still have differences due to the different technologies used by these companies. LED traffic guidance screens can accurately transmit the real-time traffic information to drivers. They have following characteristics:

 Intelligent applications: LED traffic guidance screens in the intelligent transportation

 

 

1)       High brightness, reasonable visual angles:

Road traffic-induced information is mainly oriented to vehicles traveling on the road. They have less demand on visual angles. ±30o is sufficient. LED screens outside traffic guidance rooms should work in 24 hours. In the condition of direct sunlight, the display contents should be visible. It is required that LED traffic guidance screens should have a certain level of brightness. The visual distance under normal circumstances should be around 200m.

 

2)       Red, green yellow will be three major display colors

The release of traffic information is mainly oriented to dynamic vehicles. Within the visual distance, dynamic vehicles stay for a very short time. Complex multi-grayscale graphics and animation content should be replaced by simple graphic logos or texts. Red, green and yellow are three prime colors that used in traffic signs, red represents stop, green represents suggestion, and yellow represents warning.

 

3)       The brightness of screens can be automatically adjusted

LED traffic guidance screens normally worked on 24 hours in any environmental conditions. Makers should make sure that these their products are clearly visible during the sunny daytime with the maximum brightness, and also avoid the glare in rainy days and nights. Thus it requests that these screens should be capable of automatic adjusting. In normal conditions, the automatic adjusting range should not less than 8.

 

4)       Remote control, intelligent detection

The installation passion of LED traffic guidance screens is distributed over a large area. Remote intelligent control systems are necessary. The widely distribution of LED screens makes the daily testing and maintenance work become more difficult. Remote control system can intelligently detect faults and do some simple adjustments. It is also a very important part of the intelligent transportation system.

New area of LED display applications: the Road Security

In 2011, China outdoor LED electronic display advertising market reached 1.215 billion yuan, an increase of 35.5% over the previous year. According to statistics, the size of the advertising market is expected to reach 1.55 billion yuan at the end of 2012, a growth of 27.6%. In recent years, with the government support in green lighting projects, the LED lighting industry enjoyed a vigorous development and formed a complete LED industrial chain system. LED application area gradually expanded, especially in the field of traffic safety, LED display applications became more and more popular as assist of intelligent transportation systems.

 

In 2011, China outdoor LED electronic display advertising market reached 1.215 billion yuan

 

LED screen is a good security monitor, the market development directly impact the direction of the security industry. Outdoor LED Panel Light screens have unparalleled advantages in intelligent transportation systems, which is also an important development direction of LED display applications. With the unprecedented prosperity of LED technology, LED display products are widely used in commercial advertising, life broadcast, traffic induce, stage interpretation, etc.. So far, LED screens presented some obvious characteristics:

 

1)       Large-scale production;

Chinese LED display industry are not only dominated in the mainland market, but also occupied in the market of other countries and regions, gradually forming stable exports. Product quality and reliability have been significantly improved. Manufacturers of LED display applications from the mainland had very good performances in large projects and in the global competitions.

 

2)       Technological innovation has played a positive role in leading and promoting the development of the industry.

China’s LED display technology kept path with the international development for a very long time. New products have been promoted continuously in the past two years, active innovations, improved developing capacities. Key technologies and mainstream products have more mature developments.

 

3)       The standardization and intensification of the LED display industry.

LED display industry associations actively promoted the products and technological exchanges and carried out standardization works. Standardization led to the upgrading of the level of industrialization. The industrial layout is in the process of intensification. There are a large number of large-scaled LED enterprises concentrated in Shenzhen. The most significant feature of China’s LED display application industry in recent years is the obvious increase of the number of large-scaled LED enterprises, and the sharply reduction mid-sized LED companies. In addition, the number of small-sized LED companies was also increased.

How to estimate the general lifetime of LED lamps

Is Lumen maintenance rate the only parameter that determine the lifetime of LED lamps? Normally, LED lights are composed of dimmers, power supplies, LED modules, drive components and cooling sections. These modules are connected in series or in parallel within the lamp body. Each module has its own function and reliability. The fault of anyone of them will cause the failure of the entire lamps. Just like the short board effect, the shortest board determines the capacity of the bucket. The one with the shortest lifetime among these modules will determine the service life of the lamp, totally different with traditional incandescent lights. If we treat LED lamps as electronic products, which parts are usually the main reasons for the failure of the lamp?

Is Lumen maintenance rate the only parameter that determine the lifetime of LED lamps?

Common failures of LED lights include: unreasonable cooling section designs, over-load applications, faults of driver circuits, power supplies’ failures and bad components or compartments. Failures frequently happed on electronic appliances will also occurred on LED Panel Lights. These defects can be solved via the laboratory reliability tests for electronic appliances. Another failure is usually caused by the defect of electrical characteristics. Take LED lamps for example, defects of electrical characteristics include: the lumen maintenance rate, color temperature variations, shift of power parameter offsets, etc.. Environmental reliability tests are more accurate for these defects. Therefore, from the past experience of reliability tests for electronic products, LED lighting products should also follow the traditional environment and reliability tests designed for electronic products to verify their reliability and service life.

 

As the new-born 4th generation lighting source, LED has just been touched or used in many countries and regions all over the world. Thus, it is not easy to find a large number of fault data of them. A recent large-scale failure data happened in Ellwood City, Pennsylvania, in the eastern United States. According the statistics, among the failure records of 5400 pieces outdoor LED lighting applications currently used in Ellwood City, 59% is caused directly by faults of power supplies/drivers, 31% is caused by insufficient heat dissipation, 10% caused by bad LED components. Thus, for outdoor LED products, environmental simulation tests and service life tests are more important. Only take the lumen maintenance rate into account will bright about huge errors.

LED lighting industry enjoys high position

LED lighting industry in China is just like a raging fire starting from April 28th this year. There is a program that The Ministry of science and technology in 16 provinces, municipalities directly under the central government, the 21 city start lighting applications project, which makes LED Panel Light on the hot trend.

LED lighting industry enjoys high position

By n Lasheng’s fiery situation, LED drive power market also presents great opportunities. LED drive power is the guarantee for the development of LED industry chain, LED power quality directly restricts the LED product reliability, therefore, LED industry chain gradually improve today, LED driving power of childish is crucial. LED lighting industry will bring related industries to a fiery trend. LED driving power will enter into a new era as its heart is generally important parts.

As a kind of energy saving and environmental protection products, LED will save energy about 7 %. The project office of special investigation shows, Kuniteru Aki of electricity each year in more than 3000million degrees, not only save 1/3 percent, which is equivalent to a total investment of over 2000billion annual power output. Undoubtedly, the real energy saving and environmental protection will be accelerated LED lighting.

At this stage, the price of LED lighting equipment is much higher than many radical lighting, LED lighting products also need to heat, power and lens and other peripheral components, therefore, general lighting market in the short-term priming also has the certain difficulty. Interest is the biggest problem which may block the LED lighting LED landscape . LED road lamp is developed rapidly in the field of application. Because the price of the landscape lighting products is cheap, so it has a strong market competitiveness. At the same time, the world urbanization process of China is one of the fastest, driven by government policies, the country for high power, high brightness. Energy-saving LED lights is in extremely demand related data display. There is no doubt that the LED will also make great progress in the near future.

The 50th anniversary for led lightings invention: the great people and the great invention

50 years ago now, Nick HolonyakJr — the United States Ge Corp ( General ElectricCany, GE ) , an ordinary researchers, research produced the world’s first red LED, and opened the LED Panel Light history. Now 50 years past, LED industry really like he prophesied before that ” LED will have many different colors of light, incandescent lamp, the future will be replaced by LED”. Now, in the low carbon energy trends, LED industry has become a country competing development products. As the fourth generation light source, LED has been widely used in a variety of display and illumination field, also lies in that in people’s life to bring a new round of lighting revolution.

The 50th anniversary for led lightings invention

On the occasion of the 50 anniversary of the LED method, we cannot forget that in 50 years of development of the road, the promotion of the LED step by step towards the revolutionary breakthrough of those great scientists and their great invention.

Red led lightings inventor —Nick HolonyakJr.

The invention in 1962 of LED Nick HolonyakJr., he was only the United States manufacturers Ge Corp ( General ElectricCany, GE, also known as the singular ), just an ordinary researchers. He created the first red LED, but he also believes that the future can emit light of the other wavelength, it means that LED will have many different colors of light, future incandescent light must be replaced by LED.

Yellow light inventor —-George Craford LED

George Craford the United States famous electrical engineer, in the field of led lightings contributions made by the most prominent. In 1972, Dr. Craford invented the yellow light and red and orange light LED. His graduate and doctoral students are enrolled in the United States of America Illinois University, specializing in physics, who obtained master’s degree 1963, doctorate in 1967. After graduated, he joined Monsanto chemical company, the company is the world’s first mass production of light emitting diode ( LED ) company, his team in 1972 developed nitrogen-doped GaAsP ( GaAsP ).

The father of the OLED – Deng Qingyun

In early 1979, Dr. Deng found OLED. That’s one evening in 1979, Dr. Deng is on the way to home. He suddenly thought of something forgotten in the laboratory, then returned to the laboratory. He found in the dark with a bright thing, that the original is an experimental organic battery in the light. Thus began the research on OLED.