The LED or bb> LED light bulb is an electric lamp for use in lights that produce light using a light-emitting diode (LED). The LED lights have a lifespan and electrical efficiency several times larger than incandescent, and are significantly more efficient than most fluorescent lamps, with some chips capable of removing more than 300 lumens per watt (as claimed by Cree and some other LED manufacturers). The LED lighting market is projected to grow more than twelve-fold over the next decade, from $ 2 billion in early 2014 to $ 25 billion by 2023, a compound annual growth rate (CAGR) of 25%. In 2016, LEDs use only about 10% of the energy required by incandescent lamps.
Similar to incandescent bulbs and unlike most fluorescent lamps (eg compact fluorescent tubes and fluorescent lights or CFLs), LEDs come into full brightness without the need for heating time; the age of fluorescent lighting is also reduced by frequent turning on and off. The initial cost of LEDs is usually higher. Degradation of LED dyeing and packaging materials reduces light output to some extent over time.
Some LED lights are made into direct drop-in replacements for incandescent or fluorescent lighting. A LED lamp pack can show lumens output, power consumption in watts, color temperature in kelvin or description (eg "warm white", "cold white" or "daytime"), operating temperature range, and sometimes equivalent watt incandescent lamps similar luminous output.
Most LEDs do not emit light in any direction, and their directional characteristics affect the design of the lamp, although omnidirectional lights that emit light above the 360 ​​° angle become more common. The light output from a single LED is less than incandescent and compact fluorescent lamps; in most applications, some LEDs are used to form a lamp, even if a high power version is available.
The LED, as its name implies operates as a diode, runs in direct current (DC), whereas the main current is an alternating current (AC) and usually at a voltage much higher than acceptable by the LED. Although low voltage LED lights are available LED lights can contain circuitry to convert AC power into DC at the correct voltage. This circuit contains a rectifier, capacitor and may have other active electronic components, which may or may not allow the lights to be dimmed.
Video LED lamp
Histori
Prior to the introduction of LED lights, three types of lights were used for most common (white) lighting:
- Incandescent light, which produces light with radiant filaments heated by electric current. It's very inefficient, has a luminous efficacy of 10-17 lumens/W, and also has a short lifetime of 1000 hours. They are being removed from general lighting applications. Incandescent lamps produce a continuous black body light spectrum similar to sunlight, resulting in a High Color rendering index (CRI).
- A fluorescent lamp, which produces ultraviolet light by an incandescent beam between two electrodes in a low-pressure mercury vapor tube, is converted to visible light by a fluorescent layer on the inside of the tube. It is more efficient than incandescent, has a luminous efficacy of about 60 lumens/W, and has a longer lifespan of 6,000-15,000 hours, and is widely used for residential and office lighting. But their mercury content makes them harmful to the environment, and they should be disposed of as hazardous waste.
- Metal halide lamps, which produce light by arcs between two electrodes in the atmosphere of argon, mercury and other metals, and iodine or bromine. It is the most efficient white light bulb before the LED, has a luminous efficacy of 75-100 lumens/W and has a relatively long bulb of 6,000-15,000 hours, but since they require 5 - 7 minutes of heating period before turning on, it is not used for residential lighting, but for the lighting of commercial and industrial areas, and outdoor security lights and streetlights. Like fluorescent, they also contain dangerous mercury.
Considered as an electrical energy converter, all of these existing lights are inefficient, emitting more of their input energy as heat waste than as visible light. Global electricity lighting in 1997 consumed 2016 terawatthours of energy. Lighting consumes about 12% of the electrical energy produced by industrialized countries. The increasing scarcity of energy resources, and the environmental costs of generating energy, in particular the discovery of global warming due to the carbon emitted by fossil fuel combustion, which is the largest energy source for power generation, creates an increasing impulse to develop more energy-efficient electric lamps.
The first low-powered LEDs were developed in the early 1960s, and only produced light in low, red frequencies of the spectrum. The first high brightness blue LED was demonstrated by Shuji Nakamura of Nichia Corporation in 1994. The existence of blue LEDs and high efficiency LEDs led to the development of the first 'white LED', which uses phosphor coating to convert a portion of the blue light emission to the red and green frequencies of creating light that looks white. Isamu Akasaki, Hiroshi Amano and Nakamura were then awarded the 2014 Nobel Prize in Physics for the discovery of blue LEDs.
China further encouraged the research and development of LEDs in 1995 and demonstrated its first LED Christmas tree in 1998. The application of new LED technology later became common in the early 21st century by the US (Cree) and Japan (Nichia, Panasonic, Toshiba, etc.). ) and then started 2004 by Korea and China (Samsung, Kingsun, Solstice, Hoyol, etc.)
In the United States, the 2007 Energy Independence and Security Act (EISA) authorized the Department of Energy (DOE) to establish the Light Sunday Illumination Competition, known as the "L Prize", the first government-sponsored technology competition designed to challenge industry to develop replacements for incandescent 60 W and halogen lamps PAR 38. The EISA law establishes the basic requirements and prize amounts for each of the two competition categories, and authorizes cash prizes of up to $ 20 million. The competition also includes the possibility for the winners to get federal purchase agreements, utility programs, and other incentives. In May 2008, they announced details of competition and technical requirements for each category. Lighting products that meet competition requirements can use only 17% of the energy used by most of today's incandescent bulbs. In the same year, DOE also launched the Energy Star program for solid-state lighting products. The EISA law also endorses the additional L Prize program to develop a new "21st Century Lamp".
Philips Lighting stopped its brief fluorescent research in 2008 and began devoting most of its research and development budgets to solid-state lighting. On September 24, 2009, Philips Lighting North America became the first to hand the lights in the category to replace the standard 60W A-19 "Edison screw fixture" light bulb, with designs based on their previous "AmbientLED" consumer products. On 3 August 2011, DOE won the prize in the 60 W replacement category to the Philips LED lamp after 18 months of extensive testing.
Early LED lights vary greatly in the chromaticity of the incandescent bulbs they replace. An developed standard, ANSI C78.377-2008, which sets the recommended color range for solid-state lighting products using warm to warm white LEDs with correlated color temperatures. In June 2008, NIST announced the first two standards for solid-state lighting in the United States. These standards describe 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 labeling lights that meet a set of standards for start time, life expectancy, color and performance consistency. The purpose of this program is to reduce consumer concerns due to product quality variables, by providing transparency and standards for labeling and usability of products available in the market. Energy Star Certified Light Bulbs are a resource for finding and comparing Energy Star quality lights. A similar program in the UK (run by the Energy Saving Trust) was launched to identify lighting products that meet energy conservation and performance guidelines.
The Illuminating Engineering Society of North America (IESNA) in 2008 published the documentary LM-79 standard , which illustrates methods for testing solid-state lighting products for their light output (lumens), efficacy (lumens per watt) and chromaticity.
In January 2009, it was reported that researchers at the University of Cambridge have developed LED lamps worth  £ 2 (about $ 3 US), 12 times more energy efficient than tungsten lights, and lasts for 100,000 hours.
By 2016, in the opinion of Noah Horowitz of the Natural Resources Defense Council, the new standards proposed by the US Department of Energy will likely mean most of the bulbs used in the future will be LEDs.
Initial adoption example
In 2008, Sentry Equipment Corporation in Oconomowoc, Wisconsin, USA, was able to illuminate the inside and exterior of new plants almost entirely with LEDs. The initial cost is three times that of the traditional incandescent and fluorescent mixture, but the additional cost has recovered within two years through electricity savings, and the lamp does not need to be replaced for 20 years. In 2009 Manapakkam, the Chennai office of Indian IT company iGate spent INR3.7 million (US $ 80,000) to light up 57,000 square feet (5,300m 2 ) office space with LEDs. The company expects new lighting to pay for itself in 5 years.
In 2009 a very large Christmas tree stood in front of the Turku Cathedral in Finland hung with 710 LED lights, each using 2 watts. It has been calculated that these LED lights pay for themselves in three and a half years, even though the lights are on for only 48 days per year.
In 2009 a new highway (A29) was unveiled at Aveiro, Portugal, that included Europe's first public LED lighting highway.
In 2010 the installation of bulk LED lights for commercial and public use became common. LED lights are used for a number of pilot projects for outdoor lighting and LED streetlights. The US Department of Energy made several reports on the results of many pilot projects for out-of-city lighting, and many public road and out-of-city lighting projects soon followed.
Maps LED lamp
Technology overview
LED lights are often made with LED module surface layers (SMD modules) that replace incandescent or compact fluorescent lamps, mostly replacing incandescent lamps that are increased from 5 to 60 watts.
A significant difference from other light sources is that the more directional light, that is, is emitted as a narrower beam.
White LED light
General purpose lighting requires white light. The first LED emits light in very narrow wavelength waves, the color characteristics of the energy band gap of the semiconductor material used to make the LED. LEDs that emit white light are made using two main methods: mixing light from multiple LEDs with different colors, or using phosphorus to convert some light into other colors.
RGB or trichromatic white LEDs use multiple LED chips that emit red, green, and blue wavelengths. These three colors combine to produce white light. The color rendering index (CRI) is poor, typically 25 - 65, due to the narrow wavelength range emitted. Higher CRI values ​​can be obtained by using more than three color LEDs to cover a greater range of wavelengths.
The second basic method uses LEDs in conjunction with phosphor to produce complementary colors from one LED. Some of the light from the LED is absorbed by the phosphorus molecule, causing them to fluoresce, emitting another color light through Stokes shift. The most common method is to combine blue LEDs with yellow phosphorus, producing a narrow blue wavelength range and a broad "yellow" wavewave that covers the spectrum from green to red. CRI values ​​can range from less than 70 to over 90, although a wide range of commercial LEDs of this type have color rendering indexes at around 82. After successive increases in success, which have reached 150 lm/W on production bases by 2017, this type has exceeded the performance of trichromatic LEDs.
Phosphorus used in white light LEDs can provide a color temperature in the range of 2,200 K (suitable incandescent light) up to 7,000K or more. The tunable lighting system uses individually controlled color LED banks, whether using separate banks of any color, or multi-chip LEDs with colors that are combined and controlled at chip level.
LED Driver
The LED chip requires DC-controlled and direct electric current and circuits suitable for converting alternating current from the power supply to the regulated, direct-current voltage used by LEDs.
The LED driver is an essential component of LED lights or figures. A good LED driver can guarantee long life for LED systems and provide additional features such as dimming and control. The LED driver can be inserted into a lamp or luminaire, called a built-in type, or placed outside, called an independent type. According to different applications, different types of LED drivers need to be applied, for example outdoor drivers for streetlights, indoor point drivers for down lights, and indoor linear drivers for panel lights.
Thermal management
Compared to other LED lighting systems should remain cool because high temperatures can cause premature failure and reduce light output. The thermal management of high power LEDs is needed to keep the junction temperature near ambient temperature. LED lights typically include heat dissipation elements such as heat sinks and cooling fins and very high power lamps for industrial use often equipped with cooling fans.
Limp Efficiency
The term "drooping efficiency" refers to a decrease in the efficacy of luminous LEDs when electric current rises above tens of milliamps (mA). Instead of increasing the current level, luminance is usually enhanced by combining multiple LEDs in a single lamp. Solving the problem of droop efficiency means that household LED lighting will require fewer LEDs, which will reduce costs significantly.
In addition to being less efficient, the operation of LEDs in higher electrical currents creates higher heat levels that harm LED life. Due to increased heating at higher currents, LEDs with high brightness have an industry standard operating only 350 mA. 350 mA is a good compromise between light output, efficiency, and long life.
The initial suspicion is that the LEDs droop caused by high temperatures. Scientists prove otherwise to be true - that, even though the life of the LEDs will be shortened, the increased temperature actually increases the efficiency of the LEDs. The mechanism that led to dull efficiency was identified in 2007 as Auger recombination, which was taken with mixed reactions. In 2013, a study conclusively identified Auger's recombination as the cause of dull efficiency.
Apps
LED lights are used for general and special lighting. Where colored light is needed, LEDs that inherently emit light from one color do not require filters that absorb energy.
White-light LEDs have a longer life expectancy and higher efficiency (more light for the same electrical) than most other lighting when used at the right temperature. Compact LED sources, which provide flexibility in designing lighting fixtures and good control over the distribution of light with reflectors or small lenses. Due to the small size of the LED, the control of the spatial lighting distribution is very flexible, and the light output and spatial distribution of an LED array can be controlled without loss of efficiency.
LEDs using the principle of color mixing can emit a variety of colors by changing the proportion of light generated in each main color. This allows full color mixing in lights with LEDs of different colors. Unlike other lighting technologies, LED emissions tend to be directional (or at least Lambertian), which can be beneficial or detrimental, depending on the requirements. For applications where non-directional light is required, either a diffuser is used, or some LED emitters are used to radiate in different directions.
Household LED Lights
Size and lamp base
LED lamps are made with standard lamp connections and shapes, such as Edison screw base, MR16 shape with bi-pin base, or GU5.3 (bi-pin cap) or GU10 (bayonet fitting) and are made compatible with the voltage supplied to the socket. They include driver circuitry to fix AC power and convert voltage to the appropriate value, usually switched-mode power supply.
In 2010 some LED lamps replaced higher wattage lamps; for example, one manufacturer claims a 16-watt LED lamp as light as a 150 W halogen lamp. [1] A standard general-purpose incandescent lamp emits light at an efficiency of about 14 to 17 lumens/W depending on its size and voltage. According to EU standards, energy-saving lamps that claim the equivalent of a 60W tungsten lamp should have a minimum light output of 806 lumens.
Some models of LED lights are compatible with dimmers such as those used for incandescent lamps. LED lights often have directional light characteristics. These lamps are more power-efficient than compact fluorescent lamps and offer a life span of 30,000 hours or more, reduced if operated at temperatures higher than specified. Incandescent lamps have a typical life of 1,000 hours, and compact fluorescent about 8,000 hours. Lights maintain the light intensity of output during their lifetime. Energy Star specifications require lamps to typically drop less than 10% after 6,000 hours or more of operations, and in the worst case no more than 15%. LED lights are available with various color properties. The purchase price is higher than most other lights, but higher efficiency can make the total cost of ownership (purchase price plus electricity cost and change lamp) lower.
Some companies offer LED lights for general lighting purposes. This technology is increasing rapidly and new energy-efficient LED lighting is available.
By 2016, in the United States, LED lights are almost adopted as a major light source due to falling prices and because 40 and 60 watt incandescent lamps are being removed. In the US, the 2007 Energy Independence and Security Act effectively prohibits the manufacture and import of the latest incandescent bulbs. LED lights have dropped substantially in price and many varieties are sold at subsidized prices from local utilities.
LED tube lamp
LED tube lights are designed to physically fit the equipment intended for fluorescent tubes. Some LED tubular lights are meant to be a drop-in replacement to the existing equipment if the right ballast is used. Other people need rewiring from equipment to remove the weights. An LED tube lamp generally uses many LED-Individual Surfaces that are oriented and require proper orientation during installation compared to Fluorescent tube lamps that emit light in all directions around the tube. Most available LED tube lights can be used in T5, T8, T10, or T12 markers, T8 is D26mm, T10 is D30mm, 590 mm (23 inches) long, 1,200 mm (47 inches) and 1,500 mm (59 inches).
Lighting is designed for LED
Newer lamp fittings designed for LED lights, or indeed with existing long-lived LEDs, have begun to be used because of the need for compatibility with existing equipment will be reduced. Such illumination does not require that every bulb contains a circuit to operate from an electric voltage.
Plant
Experiments reveal surprising performance and production of vegetables and ornamental plants under LED light sources. A large number of plant species have been assessed in greenhouse trials to ensure that the quality of biochemical and biochemical materials of such plants is proportional to, or even higher than, grown in the field. The performance of mint, basil, lentil, lettuce, cabbage, parsley and carrots is measured by assessing both the health and strength of the plant and the success of the LEDs in promoting growth. Seen also very many flowers of ornamental plants of choice including primula, marigold and stock.
Light emitting diodes (LEDs) offer efficient electrical lighting in desired wavelength (red blue) that support greenhouse production in minimum time and with high quality and quantity. Because the LEDs are cool, plants can be placed as close to the light source without overheating or as hot as possible. This saves a lot of space for intense cultivation.
Custom
White LED lights have reached market dominance in applications where high efficiency is important at low power levels. Some of these applications include flashlights, solar powered parks or streetlights, and bicycle lights. Monochromatic (colored) LED lights are now used commercially for traffic signal lights, where the ability to emit bright monochromatic light is a desirable feature, and in holiday light strings. LED automotive lights are widely used for longevity and small size (allowing for multiple lights), improving road safety. LED lights are also becoming popular in homes, especially for bathroom cabinet lighting and medicine.
Comparison with other lighting technologies
See glowing success for an efficiency chart comparing different technologies.
- The incandescent lamp (light bulb) produces light by passing an electric current through a resistive filament, thereby heating the filaments to a very high temperature so that it shines and emits visible light over various wavelengths. Incandescent sources produce "warm" yellow or white colors of quality depending on filament filament temperature. The incandescent lamp emits 98% of the energy input as heat. A 100 W bulb for a 120 V operation emits about 1,700 lumens, about 17 lumens/W; for 230 V lamps, the numbers are 1340 lm and 13.4 lm/W. The incandescent lamps are relatively inexpensive to make. The typical age of the incandescent AC lamp is 750 to 1,000 hours. They work well with dimmers. Most of the older light fixtures are designed for the size and shape of these traditional light bulbs. In the US, the regular sockets are E26 and E11, and E27 and E14 in some European countries.
- The fluorescent lamp works by passing electricity through mercury vapor, which in turn emits ultraviolet light. The ultraviolet light is then absorbed by the phosphor layer inside the lamp, causing it to glow, or fluoresce. Conventional linear fluorescent lamps have a life span of about 20,000 and 30,000 hours based on 3 hours per cycle according to NLPIP lamps reviewed in 2006. Neon induction relies on electromagnetism rather than the cathode used to start conventional linear neon. The new rare triphosphor linear separator lights made by Osram, Philips, Crompton, and others have a life expectancy of over 40,000 hours, when combined with a warm electronic ballast. Life expectancy depends on the number of life/death cycles, and lower if the light is often in-cycle. The efficacy of a combination of ballast-light systems for current linear fluorescent systems in 1998 tested by NLPIP ranged from 80 to 90 lm/W.
- The age of compact fluorescent lamps' typically ranges from 6,000 hours to 15,000 hours.
- The price of electricity varies in different regions of the world, and depends on the customer. In the US in general, the price of commercial electricity (0.103 USD/kWh) and industry (0.068 USD/kWh) is lower than housing (0.123 USD/kWh) due to less transmission loss.
- High-pressure sodium lamps produce about 100 lumens/watt which is very similar to LED lights. They have much shorter lifespan than LEDs, and their color rendering index is low. They are usually used for outdoor lighting and in growing lamps.
Comparison table
In keeping with the longevity claimed for LED lights, a long guarantee is offered. However, there is currently no standard testing procedure established by the Department of Energy in the United States to prove this claim by individual manufacturers. A typical domestic LED lamp is said to have an average "life" of 15,000 hours (15 years at 3 hours/day), and to support 50,000 switch cycles.
Incandescent lamps and halogen lamps naturally have a power factor of 1, but fluorescent lamps and LED lights use an input rectifier and this causes a lower power factor. Low power factor may result in additional costs for commercial energy users; CFL and LED lights are available with driver circuit to provide any desired power factor, or power factor correction in all areas can be done. EU standards require better power factor than 0.5 for lamp strengths up to 25 Watts and above 0.9 for higher power lamps.
Energy Energy Star Qualification
Energy Star is an international standard for energy-efficient consumer products. Devices carrying Energy Star service marks generally use 20-30% less energy than those required by US standards.
Energy Star Energy Qualifications:
- Reduce energy costs - use at least 75% less energy than incandescent, save on operating costs.
- Reduce maintenance costs - last 35 to 50 times longer than incandescent and about 2 to 5 times longer than fluorescent lamps. No replacement lamps, no stairs, no ongoing drainage program.
- Reduces cooling costs - LEDs generate very little heat.
- Guaranteed - comes with a minimum three-year warranty - way beyond industry standards.
- Offers convenient features - available with dimming on some indoor models and automatic shut-off daylight and motion sensors on some outside models.
- Durable - it will not break like a light bulb.
To be eligible for the Energy Star certification, LED lighting products must pass various tests to prove that the product will feature the following characteristics:
- The brightness is equal to or greater than the existing lighting technology (incandescent or fluorescent) and the light is distributed well above the illuminated area.
- The light output stays constant over time, only declining towards the end of the identifier (at least 35,000 hours or 12 years based on 8 hours usage per day).
- Extraordinary color quality. The shadow of white light is evident and consistent over time.
- Efficiency is as good or better than fluorescent lighting.
- The light instantly lights up when it is turned on.
- No flicker when dimmed.
- No off-state power sweepstakes. Fixture does not use power when turned off, with the exception of external controls, whose power should not exceed 0.5 watts off.
- The power factor is at least 0.7 for all 5W or larger lamps.
Limitations
Many will not work with an existing dimmer switch designed for higher power incandescent lamps.
The color rendering is not synonymous with the incandescent light that emits close to the perfect black body radiation from the sun and for what the eye has evolved. A measurement unit called CRI is used to state how the ability of a light source to produce eight color-coded chips is compared with a reference on a scale from 0 to 100. LEDs with CRIs below 75 are not recommended for use in indoor lighting.
The LED may blink. The effect can be seen in the slow motion video of such lights. The extent of the flicker is based on the quality of the DC power supply built into the lamp structure, usually located at the base of the lamp. A longer exposure to blinking light contributes to headaches and eye strain.
The efficiency of LEDs and life spans decreases at higher temperatures, which limits the usable strength in lights that physically replace the existing compact fluorescent types and filaments. The thermal management of high power LEDs is a significant factor in the design of solid state lighting equipment. LED lamps are sensitive to excessive heat, like most solid electronic components. LED lamps shall be checked for compatibility for use in equipment wholly or partially closed prior to installation because heat buildup may cause light and/or fire failure.
The old LED lifespan, estimated to be about 50 times that of the most common and far longer incandescent bulbs than the fluorescent type, is beneficial to the user but will affect the manufacturer as it reduces the market for substitution in the distant future.
The human circadian rhythms can be influenced by light sources. The effective daytime color temperature is ~ 5.700K (bluish white) while the tungsten light is ~ 2.700K (yellow). People who have sleep disorders of circadian rhythm are sometimes treated with light therapy (exposure to intense bluish white light during the day) and dark therapy (wearing yellow glasses at night to reduce blue light).
Some organizations recommend that people should not use bluish white lights at night. The American Medical Association opposes the use of bluish-white LEDs for city street lighting.
Research shows that since switching to LED streetlights attracts 48% more flying insects than HPS lamps, which can cause direct ecological impacts as well as indirect effects such as attracting gypsy moths to the harbor area.
See also
References
Further reading
-
E. Fred Schubert (June 8, 2006). Light Transmitter Diode . Cambridge University Press. ISBN: 978-1-139-45522-0. - Krigel, A; Berdugo, M; Picard, E; Levy-Boukris, R; Jaadane, me; Jonet, L; Dernigoghossian, M; Andrieu-Soler, C; Torriglia, A; Behar-Cohen, F (2016). "Light-induced retinal damage using different light sources, protocol and mouse strains indicates phototoxicity of the LED" (PDF) . Neuroscience . 339 : 296-307. doi: 10.1016/j.neuroscience.2016.10.015. PMID 27751961.
External links
- e-lumen.euÃ, - the website of the European Commission on second-generation energy-saving bulbs
- Some cities take another look at LED lighting after AMA warnings (Sept. 25, 2016), The Washington Post
Source of the article : Wikipedia
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