Friday, February 26, 2010
LED Stuff - Rocking The World !!!
LED Stuff - Rocking The World !!!
The innovation in electronic devices has always driven a good market all over the world. When incandescent bulbs were being replaced by CFLs, another technology was pushing its head to replace the newest one–LED. Light Emitting Diode technology has now emerged as a major replacement in many products and has changed the perspective of electronics consumer market. In this article, we provide comprehensive knowledge about LED, its applications, products, market scenario, industry overview and what’s there for new players who want to enter into the business of LED products.
What is LED
LED or Light Emitting Diode can be understood as an electronic device that gets lighted up while passing electricity through it. LED is a semiconductor light source used as indicator lamp in a number of devices. Today, LEDs are increasingly used for general lighting purpose. In the year 1962, LED found its place into the electronic industry as a practical electronic component. During its early stages, LEDs emitted low-intensity red light. With the advancements in technology, today we find a number of versions of LEDs including visible, ultraviolet and infrared wavelengths offering very bright light. Also, the fact that LEDs are small in size makes them a good choice to display images. LEDs do not burn out like other lights, while they burn on significantly lower power compared to conventional light sources.
There are a number of advantages in LED when compared to incandescent light sources. Some of them are longer lifetime, enhanced robustness, quicker switching, lower energy utilization, smaller size, more durability and reliability. On the other hand, LEDs need an accurate heat and current management as against conventional light sources. Also, the market price of current LED products is expensive when compared to the fluorescent lamp sources of equivalent output.
Basics and History of LED
LEDs are based on the principle that a semiconductor chip emits light while conducting current through it. LEDs are deemed highly versatile with regard to their capacity to emit almost all spectrums of light. As a diode is switched on, electrons are made to recombine with holes in a given device resulting in the release of energy that is available in the form of photons. Called as electroluminescence effect, the process emits light in different colors depending on the gap of the semi conductor. Usually, the diodes of LED are spaced less than 1mm or 2mm. There are a number of integrated optical components used to shape the resulting radiation pattern and to help in reflection.
Though LEDs that emit a practical spectrum of visible light are being developed since 1960s, it is only recently that LED technology is able to produce lighting sources that are able to emit acceptable levels of illumination which can effectively replace the conventional primary lighting sources in homes and businesses. Today, LEDs are increasingly finding their applications across a diverse range of lighting requirements to replace the conventional light sources. Especially, the prominent applications of LEDs include indicators and traffic signals. Since 2007, Airbus has been using LED lightning in its A320 aircrafts, while Boeing has plans to use the same in the 787.
Over and above, the smaller size of LEDs has enabled the development of innovative text and video displays and sensors, while the high switching rates of LED comes as a welcome factor in using LED in the arena of advanced communications technology. Called as Solid State Lighting (SSL), a new phase of innovative technology in the arena of LED illumination is seen developing at an amazingly fast pace. For instance, the latest bulbs that we can see in the market from EarthLED did not exist a year ago.
How it works
LEDs are commonly seen around us in a number of gadgets. LED is a semiconductor diode that emits light under the process of electroluminescence while passing current through it. In this process, the semiconductor works as the medium for the electrons to move and fall into other energy levels during their transit across the p-n junction. As the electrons jump to a lower energy level, they emit a photon of light. This photon or pack of light might either be in the infrared or ultraviolet or anywhere within the visible spectrum of light. Therefore, we need to pick up a color when we manufacture them to meet our varied requirements. Usually, LEDs are manufactured to emit one color of light, though manufacturing bicolor ones and others can easily be done. In addition, there are ways to increase the intensity of light as well. Therefore, the possibilities of broadening their application in the lighting arena are enormous.
LEDs found in normal applications are not at all voltage dependent. LEDs are manufactured according to the buyer’s color needs. Red, green and blue are the most popular colors in LED, while there are also other colors possible. Big LED color displays make use of a three-LED pixel. With this system, a number of colors can be obtained by driving them in the 3-LED assembly.
Classification of LED
One can classify LED products according to light emitting colors, diode structures, outer surface features, luminous intensity, chip material, function, and operating current, etc.
Colors of the diode:
LEDs are available in red, orange, green and blue in addition to several others. Under green colors, there are three types including pure green, standard green and yellow-green. There are also a few light emitting diodes or chips that can emit two or three colors. Also, the plastic body can be designed in many ways with or without a scattering agent, colored or colorless and so on. Therefore, the resulting classification of LEDs based on the color can be understood under four heads namely colored transparent, colorless transparent, colored scattering and colorless scattering.
Outer Surface features:
According to the features of the outer surface, LEDs can be classified into round, square, rectangular, surface LED, side LED and surface mount subminiature LED besides a number of others. Round LEDs come in different diameters ranging from φ2mm、φ4.4mm、φ5mm、φ8mm、φ10mm and φ20mm. Round LED manufactured with a diameter of φ3mm is usually referred as T-1, while φ5mm is noted as T-1(3/4) and φ4.4mm is noted as T-1(1/4).
Types according to the angle distribution of the luminous intensity:
There are three types of LEDs based on the angle distribution of their luminous intensity. A) High directivity LEDs are packed either in sharp head epoxy packaging or metal reflection cavity packaging. Usually, they are available without light scattering agent. The viewing angle of this kind of LED ranges from 5° or 20° or even smaller. These types can find their use as local illumination source or to construct an automated detecting system combined with a light detecting device. B) Standard type LEDs are usually found in indicator lamps with the viewing angle varying between 20° and 45°. C) Scattering type is generally used as indicator lamps that require comparatively larger viewing angle ranging from 45° to 90° or even larger. This type makes use of more light scattering agents than the other two types.
Based on their structure, LEDs can be classified as full epoxy resin packaging, ceramic base epoxy resin packaging, metal base and glass packaging.
According to the luminous intensity, there are three types of LEDs namely standard brightness LED (where luminous intensity is less than 10mcd), high brightness LED (where luminous intensity is between 10mcd and 100mcd) and ultrahigh brightness LED (where luminous intensity is more than 100mcd).
Based on the power that operate LEDs, they can be classified into two types namely the standard type that works on an operating current ranging from more than ten mA to tens mA; low current LED which is operated at an operating current below 2mA (In this case, the brightness is almost same as the standard LED type).
Types of LED products
1. LED Lighting Applications
Manufactured using an appropriate technology, LED can be used as a better alternative to replace a number of conventional lighting gadgets. Though the concept started its voyage primarily as indicator lights, today LEDs have found versatile application across a wide range of lighting requirements. The three main areas where LED has come as a one stop solution to the lighting requirements are traffic control devices covering barricade lights, stop lights, pedestrian signals and road hazard signs; variable message signs that display information regarding commodities and news and in automotive applications.
LED Cove Lighting is one of the fast growing applications where LED is used for hard to reach lighting applications, which would bring down maintenance costs and hassles. In several regards, LEDs are more advantageous than fluorescents and cold cathode lighting. To mention one of the most suitable examples of this application, one can mention the Atmosphere product of Albeo Technologies. This is deemed as the best example for SSL cove light that is highly preferred in terms of price, performance, installation methods, uniformity and durability.
SIGN and Display Applications:
LEDs enjoy a number of incredible advantages over traditional fluorescent sign lighting. Some of the unique features of LEDs that are useful to this arena include their Visibility, durability, enhanced efficiency, and unbelievably less maintenance. Most interestingly, LED Initiative in this field has offered the best back and internal signage lighting solution for real time applications.
2. LED applications for Museums:
LEDs do not have the hazards of forward heat and UV radiation, which renders it the best alternative for sensitive artworks meant for museums. Tested replacement SSL lamps are deemed the best for retrofit applications at museums.
LEDs for Office Lighting:
Using LED lighting fixtures at offices remove tough maintenance requirements and the concerns regarding tiring fluorescent lighting. While there is no need to store lamps and ballasts at offices, LED lighting also helps keep the workforce feel pleasant and more productive. Greenlight Initiative in the LED arena have significantly brought down the power consumption of lighting gadgets used in the office spaces by as much as 40% over the conventional incumbent fluorescent systems.
Hotels and Restaurants:
While the lighting requirements are always lit type, LED lighting products come to the rescue by enormously bringing down operating costs. LED lighting solutions have the advantages of being highly versatile besides meeting the requirements of bright or warm, colorful or crisp. The longevity and bright appearance of LEDs can add elegance to the establishments besides reducing the operating expenses to the bottom line.
Stairwell Lighting is often required to be kept on round the clock though used infrequently. LEDs have come as a solace for the building operators and management companies who rely on the products to save up to 60% of energy while ensuring continuous safe lighting levels. Over and above, LEDs are useful in applications including elevators, corridors and other similar infrastructure where the lighting adds up to the terra Watts of disused energy waste.
Over and above, applications including outdoor, pathway, security and cold weather render fluorescent lighting useless. LED lighting solutions can effectively replace the high maintenance options like HID or halogen lighting thereby ensuring unparalleled maintenance savings. LEDs have also started meeting the typical lighting requirements of parking lots and garages, hospitals and healthcare facilities, factories and large facilities, roadway lighting and bridges and tunnels.
With the evolution of solid state lighting, LED technology can effectively replace most of the conventional lighting on the planet. This can help in making enormous energy and maintenance savings in addition to bringing down carbon emissions to unprecedented low levels.
1. Long Life
Industry estimates say that all LEDs can enjoy a 50,000+ hour lifespan, when you will have to buy more than 50 regular incandescent bulbs or 5 compact florescent bulbs. LEDs do not have ignition hassles while it can work under a harsh condition of -40oC to +45oC. Since LEDs do not have filaments or tubes that might break, they are more durable. LEDs are encased in unbreakable high strength optical grade resin. Since there is no glass or filament that will break, LED light sources come as perfect solutions for lighting environments that are rugged or installations that are difficult to access.
2. Energy Efficiency
LEDs are burn on far less energy when compared to standard light bulbs, thereby bringing down energy costs. Also, LEDs need far less energy to manufacture at the industries when compared to other light sources, thereby once again bringing down the environmental impact of artificial lighting. The most powerful of LED replacement bulb consumes only 10 watts of electricity while performing equal to that of a 100 watt incandescent bulb. Moreover, conventional incandescent bulbs waste 98% of their energy by generating wasted heat, whereas LEDs generate very little heat. Also, the low power requirements of LED lighting gadgets make them ideal options for solar or wind powered installations.
3. Environmentally Friendly by Design
LEDs are considered the most environmentally friendly light source next to pure sunlight. Since LEDs do not use any hazardous substances in manufacturing, they are always RoHS compliant (a strict new standard meant to reduce hazardous substances).
4. Pure Light
LEDs come in white and warm light color temperatures. Irrespective of the temperature that we choose, we are assured of getting pure and clear light that renders reading or viewing objects easier to our the eyes.
5. Better Safety and Security
LEDs produce low levels of heat and burn on low voltages. Therefore, they are deemed perfect and safer sources of light. With LEDs, we do not have any glass to break. There are no concerns regarding hot filament, gas or candle flames and noxious fumes.
Industry Overview of LED
For quite some time since 2004, the high-brightness LED market witnessed a slow-growth phase as a result of the dominant position enjoyed by the mobile appliance market. However, the latter has come to a saturation point now. LED market experienced an overall uptick in growth from the year 2007. Still it continues to perform well and a range of its emerging applications promised the resumption of higher growth in the immediate future.
The global LED industry is seen to be clustered in Japan, EU and Taiwan. While Japan ranks first in the segment, Taiwan follows it. Philips and OSRAM are the backbones of LED sector in the EU. Top players in the LED industry in Japan include Nichia, Toshiba, Showa Denko KK, Sharp, CITIZEN and Toyoda Gosei. CREE is notable in the U.S.A.
LED industry is found highly dispersed in the mainland of China while we find thousands of LED manufacturers are found engaged in in LAMP packaging. Some of the dominant companies in this segment include Xiamen Hualian, COTCO Luminant Device (Huizhou), Jiangxi Lianchuang Optoelectronic, Ledman Optoelectronic, Golden Valley Optoelectronics, Foshan NationStar, Wenrun Optoelectronic, Ningbo Hepu Optoelectronic, Tianjin Tianxing Electronic, Refond Optoelectronics, and Leadfull Optoelectronic, besides a number of others. There are also the key manufacturers of LED including San’an Photoelectric, Dalian Lumei, Silan Azure, Epiligh Technology and Rainbow.
LED lights for numbers and alphabets
What is the market potential of LED products?
Over its development as a visible lighting source over the past three years, there is never a sign of slowing down in the LED segment. Though the Blue LED is available in production quantities only recently, they are expected to bring about an entire generation of innovative applications. Blue LEDs are known for their high photon energies (>2.5eV). They are also reported to have low eye sensitivity. The technology required to make these LEDs is very different and less advanced when compared to other LED materials. The blue LEDs available in the market today come with GaN (gallium nitride) and SiC (silicon carbide) construction with the brightness levels exceeding 1000mcd at 20mA. Blue is one of the primary colors apart from red and green. Therefore, blue LEDs will find their commercially viable applications in full color solid state LED signs and TVs in addition to medical diagnostic equipments and photolithography.
There are also enormous possibilities to manufacture other colors with the help of the same basic GaN technology and development processes. For instance, a high brightness green LED of about 500nm has been evolved, which is at present being evaluated for replacing the green bulb used in traffic signals. Other colors of LEDs that are possible include purple and white. Since blue LEDs have been introduced only recently, now the industry has the possibility to manufacture white by selectively combining red, green and blue light sources. This process might however need sophisticated software and hardware design to be commercially viable. One challenge in this segment is that the overall light output of each RGB might degrade at a different rate resulting in color unbalance over a period of time. There is yet another approach being implemented to achieve white light namely using a phosphor layer (Yttrium Aluminum Garnet) on top of a blue LED.
Today’s LED market can be identified under three segments namely general lighting, TFT-LCD backlight, and signal or data display, while TFT-LCD backlight is the most potential and rapidly evolving sector. The year 2009 saw a significant enhancement in LED luminescence efficiency and cost reduction, LED has started growing up strongly in the large-size sector. In the LED laptop field, the innovative designing of Dot typed light guide plate has effectively replaced V-cut design, thereby significantly bringing down the cost.
LEDs have already developed from infancy to adolescence and are witnessing the fastest market growth. By employing InGaAlP material along with MOCVD during the process of development and by combining it with efficient delivery of generated light and effective management of supplied power, the industry has today achieved some of the brightest, most efficient and highly reliable LEDs. In combination with other novel LED structures, this technology will ensure a wider application of LEDs across a variety of platforms. In addition, recent developments in the LED blue spectrum and white light will also ensure the continued growth in applications of LED light sources.
International scenario of LED Industry
In the year 2005, the LED industry was valued only at $205 million. Industry experts estimate that by 2011, this could be valued as high as $1 billion demonstrating 388% growth in a matter of just six years.
Most significantly, Walt Disney World has now resorted to LED lighting thereby wiring Cinderella’s Castle with more than 20,000 LEDs, which the firm says has helped in saving thousands of dollars.
The Times Square ball is today seen completely lit only with LED lighting, while it appears twice as bright using only half the energy.
The city of Boulder, Colorado is now seen switching over to LEDs for lighting its Downtown Pearl Street Mall.
It was indeed a welcome initiative to see China’s first high-definition system being installed in the Beijing Olympic Basketball Gymnasium, for displaying scores and other information at the venue during the Olympic Games. It is said that this system can easily meet the complete requirements of the National Basketball Association (NBA). LED system can also be used for theatrical performances, background imagery and real-time broadcasts.
Challenges faced by new players while entering LED industry
Today, more and more firms are rapidly changing over from different industries including traditional lighting fixtures and consumer electronics to SSL (Solid State Lighting) industry. Due to the sudden outburst of competition in the arena, the new and the present SSL players are undergoing tremendous pressure due to factors including price reduction, shorter life span of products, more need for new product innovation and Market Strengthening.