LED lamp
An LED lamp or LED light is an electric light that produces light using light-emitting diodes. LED lamps are significantly more energy-efficient than equivalent incandescent lamps and fluorescent lamps. The most efficient commercially available LED lamps have efficiencies exceeding 200 lumens per watt and convert more than half the input power into light. Commercial LED lamps have a lifespan several times longer than both incandescent and fluorescent lamps.
LED lamps require an electronic LED circuit to operate from mains power lines, and losses from this circuit means that the efficiency of the lamp is lower than the efficiency of the LED chips it uses. The driver circuit may require special features to be compatible with lamp dimmers intended for use on incandescent lamps. Generally the current waveform contains some amount of distortion, depending on the luminaires' technology.
The LED lamp market is projected to grow from US$75.8 billion in 2020 to US$160 billion in 2026. LEDs come to full brightness immediately with no warm-up delay. Frequent switching on and off does not reduce life expectancy as with fluorescent lighting. Light output decreases gradually over the lifetime of the LED.
Some LED lamps are drop-in replacements for incandescent or fluorescent lamps. LED lamps may use multiple LED packages for improved light dispersal, heat dissipation, and overall cost. The text on retail LED lamp packaging may show the light output in lumens; the power consumption in watts; the color temperature in kelvins or a color description such as "warm white," "cool white," or "daylight;" the operating temperature range; whether the lamp is dimmer compatible; whether the lamp is suitable for humid/damp/wet conditions; and sometimes the equivalent wattage of an incandescent lamp delivering the same output in lumens.
History
Before the introduction of LED lamps, three types of lamps were used for the bulk of general lighting:- Incandescent lights produce light with a glowing filament heated by electric current. These are very inefficient, having a luminous efficacy of 10–17 lm/W, and also have a short lifetime, typically 1000 hours. They are being phased out of general lighting applications. Incandescent lamps produce a continuous black body spectrum of light similar to sunlight, and so produce high Color rendering index.
- Fluorescent lamp produce ultraviolet light by a glow discharge between two electrodes in a low pressure tube of mercury vapor, which is converted to visible light by a fluorescent coating on the inside of the tube. These are more efficient than incandescent lights, having a luminous efficacy from 50 to 100 lm/W, have a longer lifetime of 6,000–15,000 hours, and are widely used for residential and office lighting. However, their mercury content makes them a hazard to the environment, and they have to be disposed of as hazardous waste.
- Metal-halide lamps, which produce light by an arc between two electrodes in an atmosphere of argon, mercury and other metals, and iodine or bromine. These were among the most efficient white electric lights before LEDs, having a luminous efficacy of 75–100 lm/W and a relatively long bulb lifetime of 6,000–15,000 hours; because they require a 5–7-minute warmup period before they reach full output, metal-halides are not used for residential lighting, but for commercial and industrial wide area lighting and, outdoors, for security lights and streetlights. Like fluorescents, they also contain hazardous mercury.
The first low-powered LEDs were developed in the early 1960s, and only produced light in the low, red frequencies of the spectrum. In 1968, the first commercial LED lamps were introduced: Hewlett-Packard's LED display, which was developed under Howard C. Borden and Gerald P. Pighini, and Monsanto Company's LED indicator lamp. However, early LED lamps were inefficient and could only display deep red colors, making them unsuitable for general lighting and restricting their usage to numeric displays and indicator lights.
The first high-brightness blue LED was demonstrated by Shuji Nakamura of Nichia Corporation in 1994. Isamu Akasaki, Hiroshi Amano and Nakamura were later awarded the 2014 Nobel Prize in Physics for the invention of the blue LED. The existence of blue LEDs and high-efficiency LEDs led to the development of the first 'white LED', which employed a phosphor coating to partially convert the emitted blue light to lower frequencies, creating white light. New LED lights entered the market near the start of the 21st century in the US and Japan, and then starting in 2004 in Korea and China In the US, the Energy Independence and Security Act of 2007 authorized the Department of Energy to establish the Bright Tomorrow Lighting Prize competition, known as the "L Prize", challenging industry to develop replacements for 60 W incandescent lamps and other lamps. Products meeting the competition requirements would use just 17% of the energy used by most incandescent lamps of that time.
Philips Lighting ceased research on compact fluorescents in 2008 and began devoting the bulk of its research and development budget to solid-state lighting. On 24 September 2009, Philips Lighting North America became the first to submit lamps in the category to replace the standard 60 W A-19 "Edison screw fixture" light bulb, with a design based on their earlier "AmbientLED" consumer product. DOE awarded Philips the prize after 18 months of extensive testing. Many other similarly efficient products followed.
Early LED lamps varied greatly in chromaticity from the incandescent lamps they were replacing. A standard was developed, ANSI C78.377-2008, that specified the recommended color ranges for solid-state lighting products using cool to warm white LEDs with various correlated color temperatures. In June 2008, NIST announced the first two standards for solid-state lighting in the United States. These standards detail performance specifications for LED light sources and prescribe test methods for solid-state lighting products.
Also in 2008 in the United States and Canada, the Energy Star program began to label lamps that meet a set of standards for starting time, life expectancy, color, and consistency of performance. The intent of the program is to reduce consumer concerns due to variable quality of products, by providing transparency and standards for the labeling and usability of products available in the market. Energy Star Certified Light Bulbs is a resource for finding and comparing Energy Star qualified lamps.
A similar program in the United Kingdom was launched to identify lighting products that meet energy conservation and performance guidelines. Ushio released the first LED filament lamp in 2008. Philips released its first LED lamp in 2009, followed by the world's first 60 W equivalent LED lamp in 2010, and a 75 watt equivalent version in 2011. The Illuminating Engineering Society of North America in 2008 published a documentary standard LM-79, which describes the methods for testing solid-state lighting products for their light output, efficacy and chromaticity.
, in the opinion of Noah Horowitz of the Natural Resources Defense Council, new standards proposed by the United States Department of Energy would likely mean most light bulbs used in the future would be LED. By 2019 electricity usage in the United States had decreased for at least five straight years, due in part to U.S. electricity consumers replacing incandescent light bulbs with LEDs due to their energy efficiency and high performance. In 2023 Signify N.V. introduced the highly efficient LED lamps with EU efficiency class A, which requires an efficiency of at least 210 lm/W.
Examples of early adoption
In 2003, the first surgical goggles with LEDs were demonstrated. Audi showed the Audi Nuvolari concept car with LED headlights. In 2004, Audi released the first car with LED daytime running lights and directionals, the 2004 Audi A8 W12.In 2005, an LED lamp was installed to illuminate the Mona Lisa. LEDs were in use at the Casino Breda in The Netherlands, the Vienna State Opera, and the venue for the Shanghai Grand Prix, for example. LED flashlights and headlamps for people were available. In 2006, some of the first LED spotlights for use in stores were released. Toyota's Lexus LS 600h L was the first production car with LED headlights. In 2007, Audi was the first car manufacturer to offer headlights that solely used LEDs, used in the Audi R8. In the same year, Toshiba released the first commercial white LED lamp for homes.
In 2008 Sentry Equipment Corporation in Oconomowoc, Wisconsin, US, was able to light its new factory interior and exterior almost solely with LEDs. Initial cost was three times that of a traditional mix of incandescent and fluorescent lamps, but the extra cost was recovered within two years via electricity savings, and the lamps should not need replacing for 20 years. In 2009 the Manapakkam, Chennai office of the Indian IT company, iGate, spent to light of office space with LEDs. The firm expected the new lighting to pay for itself within 5 years.
In 2009, Audi was the first manufacturer to offer a car that exclusively used , the 2009 Audi R8. In 2009 the exceptionally large Christmas tree standing in front of the Turku Cathedral in Finland was hung with 710 LED lamps, each using 2 watts. It has been calculated that these LED lamps paid for themselves in three and a half years, even though the lights run for only 48 days per year. In 2009 a new highway was inaugurated in Aveiro, Portugal; it included the first European public LED-based lighting highway.
By 2010 mass installations of LED lighting for commercial and public uses were becoming common. LED lamps were used for a number of demonstration projects for outdoor lighting and LED street lights. The United States Department of Energy made several reports available on the results of many pilot projects for municipal outdoor lighting, and many additional streetlight and municipal outdoor lighting projects soon followed.
In 2016, the Indian government launched their Ujala LED bulb scheme, with the goal of replacing all incandescent and CFL bulbs in the country in favor of LED bulbs. According to Narendra Modi in March 2022, the scheme had distributed 370 million LED bulbs free to households and reduced power bills in middle class and poor households by. The Ujala scheme also encouraged the expansion of domestic LED production in India.