A walk through the lighting section of any hardware store, and you may be dazzled by not only the sparkling fixtures but also the sheer number of options with which you are presented.
A few of your choices include incandescent, fluorescent and LED lights. One of the most energy-efficient general lighting technologies – light-emitting diodes, or LEDs, use twenty-five to thirty percent of the energy of the halogen incandescents they replace. They are free of mercury, less prone to breakage, and boast a general life expectancy of fifty thousand hours – in other words – nearly fourteen years.
In the most simplified terms, an LED is a semiconductor device that emits light when an electrical current is passed through it. LEDs work on the principle of electroluminescence. This process can be described as a phenomenon in which a material emits light when an electrical current is passed through it.
The principle of electroluminescence was discovered in 1907 by Henry Joseph Round using silicone carbide and a so-called cat’s whisker detector (not actually made out of a cat’s whisker). The British inventor noticed that when voltage was applied to silicon carbide crystal, it emitted a dim yellow light. A more thorough investigation and proposed theory was later published by Russian scientist Oleg Vladimirovich Losev in his 1927 paper “Luminous Carborundum Detector and Detection Effect and Oscillations with Crystals”.
Many years passed before significant progress was made on light emitting diode research. It was not until 1962 that Gary Pittman and James Robert “Bob” Biard from Texas Instruments secured a patent for infrared LEDs. The first visible spectrum LED was developed by General Electric engineer Nick Holonyak, Jr.
In 1972, a former graduate student of Holonyak – M. George Craford – invented the first yellow LED and increased by ten-fold the brightness of red and red-orange LEDs. High brightness, high-efficiency LEDs were not created until 1976, when T.P. Pearsall designed them using his newly invented semiconductor materials. Shuji Nakamura of Nichia Corporation made the first blue LED in 1979 but it was too expensive for commercial use until 1994.
LEDs were initially too pricey to be used for any practical or everyday purposes. At over $200 per unit, all but the most expensive laboratory or scientific equipment could justify the expense. Later developments would allow for individual LED cost to be reduced to just 5 cents per unit.
During the years of 1962 to 1968 Hewlett Packard research teams investigated practical LED development. Led by researchers Howard C. Borden, Gerald P. Pighini and Mohamed M. Atalla, Hewlett Packard utilized gallium arsenide phosphide to create red LEDs suitable for indicators. In 1969, Hewlett Packard introduced the HP Model 5082-7000 Numeric Indicator – the first intelligent LED display, which would replace the Nixie tube and become the technological predecessor to LED displays.
Mohamed Atalla later joined Fairchild Semiconductor where he continued to build on LED development. While at Fairchild, Atalla made a breakthrough in his research to solve the problem of silicon surface states. His surface passivation method would become the basis for Jean Hoerni’s compound semiconductor chips which were fabricated using the planar process. Along with innovative packaging methods, these compound semiconductor chips would later allow Fairchild optoelectronic pioneer Thomas Brandt to achieve significant production and materials cost reduction.
After many iterations and improvements over several decades, LED technology has evolved to become a product that is compact, super-efficient, long-lasting and can emit not only visible light, but infrared and ultraviolet light. They claim the advantages of being able to switch quickly on and off, cover an expanse of color arrays and they are exceptionally durable. This makes them a popular and sensible choice for many applications.
LED usage and applications can be divided into four main categories. These include:
- Visual Signals – where LEDs are used to indicate a message or meaning. One example of a visual signal would be an on/off indicator for a device.
- Illumination – in which LEDs produce light for the purpose of increased or altered visibility. Interior and exterior home, auto and marine lighting are just a few of the examples of illumination using LEDs.
- Measuring – using LEDs to measure and interact with process not involving human vision.
- Sensors – instead of emitting light, LEDs respond to incident light by operating in a reverse-bias mode and by utilizing narrow band light sensors. Rapid real time detection of biological aerosols is made practical by the implementation of semiconductor UV optical sources, or SUVOS.
LEDs can replace almost any light source, for any purpose. Doing so provides advantages such as efficiency, durability, flexibility and sustainability.
The advent of high-powered and high-efficiency LEDs have allowed for myriad lighting applications. Prior to the 1970’s, LEDs were too expensive and dim to allow for use other than indicator lights on expensive lab equipment. As a result of many technological advances, LEDs lighting options are highly energy-efficient and application-rich.
As with incandescent lighting, LED lights allow for control over both warmth and wattage. Additional benefits to this type of technology is size – in architectural interior lighting applications, recessed lighting no longer means tedious installation and bulky housing, they are thin, lightweight and easy to install.
LED lighting is not limited to interior architectural applications. LED lighting technology can be found where any previous lighting technology is utilized, with manufacturers creating retrofit kits to allow consumers to upgrade their existing products to superior LED technology.
Television and Remote Controllers
The newest, highest technology televisions utilize OLEDs (a light-emitting dioide in which the emissive electroluminescent layer is a film of organic compound that emits light in response to an electric current). These OLED TVs represent a class of viewing devices as never seen before – deeper blacks and brighter whites mean OLED televisions provide an unmatched viewing experience.
LED lights can be turned on and off (modulated) very quickly, and are therefore appropriate for use in optical fiber and wireless data transmission. Infrared LEDs are used extensively for this purpose, which includes usage in remote controls for television sets.
You can also find LED lights serving as on/off indicator lights on your entertainment devices such as televisions, gaming consoles and stereo systems.
LEDs are a truly sturdy lighting option. Their longevity and mechanical stability makes them useful for not only street and home lighting, but also for use on cars, motorcycles and bicycles. LEDs are used in automotive headlights, brake lights, interior lights and indicator lights. LED headlights are the latest innovation in forward lighting for vehicles. They are bright, turn on instantly and use less power than their halogen predecessors. Another automotive application for LEDs are after-market light kits used by automotive enthusiasts to enhance and customize cars.
Automakers utilize LED technology in factories to create a safer and more efficient environment. An intelligent digital LED infrastructure helps to extend the service life of lighting fixtures and automatically adjust to the changing lighting needs of workers. LED sensors in conjunction with smart HVAC systems create automated alerts and flagging systems for excess CO2 or other chemical particulates inside industrial assembly line environments.
Cyclists use LEDs to increase visibility while riding their bicycles. The thin, lightweight and bright nature of LEDs allow for usage on bicycle bodies, headlamps, helmets and even wearable clip-on lighting. LEDs can even be used to light up bicycle wheels for both increased illumination and cosmetic enhancement.
LED billboards allow for an incredible increase in functionality over traditional printed or painted billboards. Their capacity for animation, bright color, and high resolution makes them an ideal display medium for outdoor advertising. LED billboards offer the distinct advantage of flexibility – gone are the days of sending out a crew to repaint and install large scale advertising. Now, a few simple keystrokes can illuminate and animate an outdoor visual spectacle.
In fast food and short order restaurants, LED screens are increasingly being used to replace wall menus. This allows for menus to be updated with seasonal items, change pricing to account for increases in ingredient costs, as well as changing graphics for an updated and fresh look. Advances in LED technology have made replacing wall menus not only affordable, but the new standard for the restaurant industry.
From kayaks to cruise ships, maritime vessels utilize LED lights in many different applications. The four types of navigation lights – sidelight, sternlight, masthead and all-around white lights – help boaters determine which is the give-way vessel in darkness or diminished visibility. As with automotive lights, the maritime industry is turning to LEDs for a durable, bright and efficient lighting option.
Additional uses in the aquatic industry include handheld and mounted lights to provide visibility and increased safety for boaters on open waters. Cruise ships utilize LED lighting for mechanical operation as well as ambient interior lighting in ballrooms and suites alike.
The maritime industry is increasingly moving towards using LEDs in safety mechanisms such as emergency flotation equipment including life vests and evacuation boats. The small and rugged LED improves the process of clearly marking emergency exits, ladders and rescue apparatus.
As with the maritime industry, the airline industry is seeing an increase in usage for the various lighting needs of both commercial airplanes and personal aircraft.
Newer Airbus and Boeing jetliners use LED lighting, which allows for flexible and durable cabin lighting. Older airplanes are being retrofitted with newer, high-efficiency LED lighting for updated cabin interiors and increased safety and efficiency.
Airport building lights are increasingly being updated with energy-efficient LEDs in both architectural lighting as well as airport advertising, storefront and restaurant displays.
LEDs are used for airport beacon and warning lights, which allow pilots to easily identify airports at night. Airport beacons are large, high-visibility, rotating lights. Public-use civilian airport beacons rotate alternating one green and one white, while military airports rotate two white lights for each green light. Heliports rotate between yellow, white and green lights. Additionally, airports use LEDs for taxiway edge lights, clearance bar lights, stop bar lights, runway guard lights, runway end identifier lights, high, medium and low-intensity runway edge lights, runway centerline lighting systems, touchdown zone lights, land and hold short lights, runway status lights and visual glide slope indicators.
Aircraft ground crewmembers use handheld LED beacons to guide and visually communicate with planes as they arrive or depart jet-way bridges.
While LEDs are super high performance, they are still exceptionally lightweight and produce very little heat – these qualities are among the few that make them an excellent choice for photographers and filmmakers.
The low heat output of LED camera and room lights makes them great choices for photographing or filming in small spaces – subjects can be brightly lit without shriveling under the heat of their incandescent light output equals. Lightweight and low-profile LED lights allow for multiple light sources, making them an optimal choice for product shots. Food photographers no longer have to worry about their Instagram-worthy spreads dehydrating to a withered and unappealing state while shooting under multiple lights.
Low heat also means that gels, cutouts or color films can be attached to lights without the risk of burning hands or starting fires. This same quality allows crews to disassemble and pack up after shooting without having to wait for lights to cool.
Sturdy LED lights withstand accidental breakage, making them an ideal choice high-action sets or camera operators on the go. Their high-efficiency and longevity means that your lighting investment costs less to operate and lasts longer, not to mention that LEDs are a more environmentally sustainable choice.
Plant cultivators are increasingly turning to LED grow lights because they give off very little heat. Regular incandescent lights are not used for indoor growing because their heat can burn delicate plants and seedlings. LED grow lights are especially useful for large indoor plant lighting needs because they use half the electricity of fluorescent tube lights. They are also largely shatter resistant and have the added benefit of longevity – they last up to five times longer than fluorescent bulbs.
Environmentally conscious farmers are increasingly turning to LED technology to help create a more sustainable model for indoor growing. LEDs seamlessly work with wireless technology so sensors can automatically communicate with lights to create an instant, automated adjustment to light sources.
LED lights are used in conjunction with high-pressure sodium lamps, or HPS lights, to boost high tech agricultural projects to shape how plants grow, when they bloom, and even alter their nutritional content and taste. They allow indoor farms to function year-round and boost crop production.
While indoor lights have been used for farming in the past, they have not been able to do so without creating a much larger carbon footprint by way of energy consumption. Newer LED technology is changing the face of indoor farming and creating a new focus for technological research. As technology improves, analysts expect LEDs to replace indoor farming lights in their entirety.
Farming equipment such as combines, loaders, tillers, planters, air drills, air carts, balers, windrowers, wheel rakes and mergers, forage harvesters and blowers, and mowers can all be retrofitted with LED lighting kits for higher-efficiency and increased performance. The lighter weight of LEDs help increase fuel efficiency by reducing the overall weight of machinery. Additionally, working hours can be extended with the use of bright, lightweight LED area lights and floodlights.
LED lights are used in the mining industry on heavy machinery and equipment such as draglines, electric rope shovels, wheel loaders, DC blasthole drills, dozers, hydraulic excavators and hauling trucks. They are used as brighter, more efficient, lighter-weight options for area, floodlights and danger lights. For wet locations, LEDs can replace traditional incandescent lights as they can be built to withstand moisture and can better endure accidental impact.
The mining industry also employs LED lights for mining infrastructure lighting such as wash bays, crushing sites and in processing plants. LED floodlights and area lights create a safer and more comfortable working environment for mining industry laborers. LEDs are also well-suited to hard hat and safety vest lighting.
Massive increases in performance and reduction of production costs has allowed for incredible innovation in LEDs for medical applications.
Hospitals utilize LED lights in exam rooms and surgical suites to replace traditional single-source lights, creating a more versatile lighting situation for medical doctors, nurses and technologists. In the surgical setting, traditional overhead single-source lights provide adequate illumination but present problems with heat production and shadowing. Because LEDs are lightweight and low-profile, overhead lights can be arranged in multiple direct view formation thus eliminating shadowing.
LEDs greatly reduce heat output from light sources while providing a more comfortable lighting source for surgeons and techs. Reduced heat output also helps to lower the risk of exposure-related tissue damage for the patient. LED color outputs can even be changed on-demand, to suit the needs of healthcare providers and in some cases aid in clearer imaging of surgical sites.
LEDs are being used in multiple phototherapy applications. Neonatal Intensive Care Units (NICU) use blue lights to treat Neonatal Hyperbilirubinemia, in which the livers of newborns are unable to process bilirubin, causing jaundice. These blue lights, or bilirubin lights, convert the bilirubin into a form that can be excreted through the body’s waste systems.
Dental healthcare providers use LED lights in much the same way as hospitals or other care providers, both in exam room lighting and for therapeutic and cosmetic modalities. LED lights are used in cosmetic dental applications to enhance the bleaching properties of medical grade hydrogen peroxide. Dentists and orthodontists also use LED curing lights to harden, or polymerize, resin-based composites. Additionally, LED UV lights are used as an aid to detect, repair or remove composite resin, which fluoresces under UV light. In the past, these repairs were tedious due to difficulty in fully identifying areas of composite resin.
In the dermatological setting, LED lights can be used to treat skin conditions such as psoriasis, eczema, and certain fungal skin infections. Medical estheticians in the newly emerging “cosmeceutical” or med-spa industry are turning to LED lights to augment cosmetic skincare procedures.
Assistive Listening Devices
Among the many uses of assistive listening devices are augmenting sound for the hard of hearing, broadcasting language interpretation for foreign language presentations and audio descriptions for the blind or sight-disabled.
Assistive Listening Devices generally utilize one of three technologies. Induction (Loop) Technology, RF (Radio Frequency) Technology, or IR (Infrared) Technology. IR systems use LEDs to produce infrared light signals that are radiated or broadcast into a room and are received by wireless receivers.
IR technology works by using an electrical signal which contains audio information from the chosen audio source, such as a microphone, stereo system or theater sound output system. This signal is then received by the modulator which then prepares the audio signal for infrared transmission.
The processed signal is then fed into the radiator, which uses IR LEDs to produce an infrared light and broadcast it into the room.
These broadcast signals are received by wireless receivers that convert the infrared light signal back into an electrical signal and subsequently into an audio signal.
The general advantages of using IR Technology is its relative low cost and ability to accommodate multiple simultaneous listening channels. This makes LED driven IR technology an ideal system to use in auditoriums, theaters or other large venues in which hearing assistance is anticipated or required. As hearing loss particularly affects the elderly, these technologies can be tremendous assets to any facility which strives to be inclusive of aging adults.
Machine Vision (barcodes)
LEDs are often used in machine vision systems, which require bright and even illumination. Machine vision is a technology in which hardware and software work together to help machines inspect, process and guide and act in response.
Barcode scanners are an example of machine vision application – they read barcodes, sending the data to a computer for processing. Product barcodes allow workers to quickly scan a product for price and information. Barcodes allow pricing and product information to be centrally updated, eliminating the need for individual product pricing updates.
Fiber optic LED illuminators are used to create a super versatile lighting source for fiber optic applications. Fiber optics can not only be used for communication applications, but also for architectural and sensory lighting.
Fiber optic fibers are long thin strands of carefully constructed glass about as thin as a human hair. These strands are housed inside casing and bundled in arrangements called optical cable.
LEDs can be used as the light emitter in any fiber optic system. In a communication system, this component converts the electrical signal into a light signal that can be used to illuminate the fiber in a corresponding fashion. LEDs are ideal for this application because of their small size, high radiance, ability to quickly modulate and high efficiency.
Fiber optics were originally developed in the 50’s for use in endoscopic procedures. This groundbreaking invention allowed physicians to perform exploratory procedures without making large incisions in patients’ bodies. It preceded and is used alongside the invention of minimally invasive arthroscopic surgery, which completely revolutionized surgery as a medical treatment.
LED fiber optic illuminators are also used for ambient lighting, display and architectural lighting as well as effects lighting. Producers of fiber optic lighting often offer illuminators capable of being retrofitted to existing systems, allowing users to convert to the more cost-effective and efficient LED choice.
Water and Air Purification
UVC (ultraviolet) LEDs are used to disinfect and purify both water and air. UVC refers to ultraviolet light with wavelengths between 200-280 nanometers. UVC LED lights provide fast and effective neutralization of microorganisms. When bacteria, viruses and protozoa (such as amoebas, flagellates, ciliates, sporozoans, and many other forms) are exposed to UVC wavelengths, they stop reproducing and infecting.
The advantages of LED UV lamps include high efficiency, lack of mercury, instantaneous peak to disinfection temperatures and selectable wavelengths.
Conventional UV lamps require anywhere from 110 to 240 volts to operate. However, since LED UV lamps require only low voltage direct current, they can operate using a small solar panel or battery.
Additionally, LEDs do not use mercury, so they do not pose the risk of contaminating water if they break. Traditional UV lamps not only contain mercury and require special disposal, they also last only roughly one year whereas LED UV lamps can last over ten years.
Traditional UV lamps take up to ten minutes to warm up to peak disinfection temperatures. LEDs take only nanoseconds to reach peak temps, allowing the UV lamp to instantly respond to undesirable water or air conditions.
Different bacteria responds to specific wavelengths. LED UV lamps have the ability to select wavelengths, creating a more efficient response to specific bacteria.
UVC LEDs help to provide surface disinfection in high-traffic public spaces. Proper disinfection of contaminated surfaces is essential to the maintenance of public health. Antibiotic resistant microorganisms can survive for weeks on certain surfaces. Hospital rooms and equipment, airports, schools and mass public transportation vehicles can all be sources of these dangerous antibiotic resistant microorganisms.
Traditional UVC lamps have been used in conjunction with chemical disinfection agents for 100 years. These lamps are expensive, contain mercury and have a short lifespan. UVC LED disinfection lights provide superior disinfection properties, while boasting a long lifespan, no mercury and low relative cost. The portability of UVC LEDs now makes UVC a viable choice for use in public spaces previously unable to benefit from UVC disinfection.
Wallpapers (interior design)
LED wallpaper integrates LEDs into a flat, flexible substrate (underlying layer of material) for the purpose of interior decoration. The progressive miniaturisation of LEDs and other low-voltage lighting options has created the possibility of experimentation within this realm.
These LED wallpaper materials can create a completely novel and stunning interior lighting effect. As a relatively new application, LED wallpapers are not yet widely available for commercial and direct to consumer purchase. The wallpaper that is available is restrictive in pricing, but further technological and production improvements may offer the same drastic reduction in cost as other LED applications.
LED lights are especially well-suited for holiday lights, such as the string lights used for decorating during Christmas. Their brightness, rugged structure and longevity make them ideal for both indoor and outdoor Christmas lighting needs.
Celebrating Hanukkah is made safer through the use of LED menorahs, which eliminate the need for candles or oil which are flammable and may be unsuitable for use in classrooms.
Diwali, which coincides with the Hindu New Year, celebrates new beginnings and the triumph of good over evil and light over darkness. LED lights can be used in place of fire in lighting deepa (clay lamps), for a safer experience.
Part of celebrating Chinese New Year involves brightly decorated and intricately shaped lanterns which used to symbolize people letting go of their past selves. LED lights provide a long-lasting and bright light source for this festive and culturally significant holiday.
With increased commercial viability and ever-decreasing production costs, LEDs are poised to continually expand their market base. Less than 10 percent of households utilize LED lights. As costs continue along the downward trajectory and applications widen, the LED light is expected to expand its market base exponentially over the next decade.
LEDs offer unmatched efficiency, an ever-broadening usage spectrum and overall cleaner power. They require less power to operate and will soon match or undercut costs of initial investments of traditional light sources. LEDs can be found anywhere lights, indicators or sensors are required. The lower power requirement, longevity and rugged structure means they are a much more eco-friendly option than other light sources.
Looking forward, we expect to see even more innovation in regards to LED technologies. The latest research into LEDs involves the usage of perovskites, which is a class of materials that have exciting properties such as superconductivity and magnetoresistance. Studies show future promise for LEDs that are even more cost-efficient, higher-performing and eco-friendly.
These technological improvements and innovations mean that the applications for LEDs will continue to grow with each year. In a world where a focus on environmental health is more imperative than ever, LEDs will help to light the way to a more sustainable and revolutionized future.