"phosphors provide more diffuse light, which is desirable for many applications. Remote phosphor designs are also more tolerant of variations in the LED emissions spectrum. A common yellow phosphor material is cerium-doped yttrium aluminium garnet (Ce:YAG). White LEDs can also be made by coating near-ultraviolet (NUV) LEDs with a mixture of high-efficiency europium-based phosphors that emit red and blue, plus copper and aluminium-doped zinc sulfide (ZnS:Cu, Al) that emits green. This is a method analogous to the way fluorescent lamps work. This method is less efficient than blue LEDs with YAG:Ce phosphor, as the Stokes shift is larger, so more"
"emitted from an LED is neither coherent nor monochromatic, but the spectrum is narrow with respect to human vision, and for most purposes the light from a simple diode element can be regarded as functionally monochromatic. Electroluminescence as a phenomenon was discovered in 1907 by the British experimenter H. J. Round of Marconi Labs, using a crystal of silicon carbide and a cat's-whisker detector. Russian inventor Oleg Losev reported creation of the first LED in 1927. His research was distributed in Soviet, German and British scientific journals, but no practical use was made of the discovery for several decades. In"
"produced within the junction to appropriate areas of the light fixture. Conventional LEDs are made from a variety of inorganic semiconductor materials. The following table shows the available colors with wavelength range, voltage drop, and material: The first blue-violet LED using magnesium-doped gallium nitride was made at Stanford University in 1972 by Herb Maruska and Wally Rhines, doctoral students in materials science and engineering. At the time Maruska was on leave from RCA Laboratories, where he collaborated with Jacques Pankove on related work. In 1971, the year after Maruska left for Stanford, his RCA colleagues Pankove and Ed Miller demonstrated"
"2002, the National Christmas Tree sported a gold, green, and red design (again) with gold garland and wreath-shaped ornaments. For the first time, light-emitting diodes (LEDs) were used as part of the lighting scheme. Two strands of red LED lights were entwined with the garland. The incandescent tree lights changed from gold to green and back again continuously. The garland and lighted ornaments remained lit without a color change. The tree consumed enough power nightly to light two homes. The following year, the 80th anniversary of the tree-lighting ceremony, a nostalgic and simplified lighting design featuring 13,000 incandescent blue, gold,"
"Until 1968, visible and infrared LEDs were extremely costly, in the order of US$200 per unit, and so had little practical use. The Monsanto Company was the first organization to mass-produce visible LEDs, using gallium arsenide phosphide (GaAsP) in 1968 to produce red LEDs suitable for indicators. Hewlett-Packard (HP) introduced LEDs in 1968, initially using GaAsP supplied by Monsanto. These red LEDs were bright enough only for use as indicators, as the light output was not enough to illuminate an area. Readouts in calculators were so small that plastic lenses were built over each digit to make them legible. Later,"
"the two inventors were issued U.S. patent 3,293,513 for the GaAs infrared (IR) light-emitting diode. Most other organized research seeking LEDs at the time used II-VI semiconductors like cadmium sulfide (CdS) and cadmium telluride (CdTe), while Biard and Pittman's patent used gallium arsenide (GaAs), a III/V semiconductor. After filing the patent, T.I. immediately began a project to manufacture infrared diodes. In October 1962, they announced the first commercial LED product (the SNX-100), which sold for a price of $130 per unit. The SNX-100 employed a pure GaAs crystal to emit a 900 nm light output. It used gold-zinc for the"
"to news that the inventors of the blue LED were awarded the 2014 Nobel Prize in Physics, instead of his fellow LED researchers. Nick Holonyak Nick Holonyak Jr. (born November 3, 1928) is an American engineer and educator. He is noted particularly for his 1962 invention of a light-emitting diode (LED) that emitted visible red light instead of infrared light; Holonyak was then working at General Electric's research laboratory in Syracuse, New York. He is a John Bardeen Endowed Chair Emeritus in Electrical and Computer Engineering and Physics at the University of Illinois at Urbana-Champaign, where he has been since"
"M. George Craford M. George Craford is an American electrical engineer known for his work in Light Emitting Diodes (LEDs). Craford received his MS (1963) and PhD (1967) degrees in physics from the University of Illinois in 1967, began his professional career at the Monsanto Chemical Company, then in 1979 joined Hewlett Packard, where in 1982 he became the research and development manager of the HP Optoelectronics Division. When Lumileds Lighting (now Philips Lumileds Lighting Company) spun out from HP in 1999, Craford was named the company's Chief Technical Officer (CTO). In 1972 Craford invented the first yellow LED as"
"to a separate lead so they can be controlled independently. A four-lead arrangement is typical with one common lead (anode or cathode) and an additional lead for each color. RGB LEDs are tri-color LEDs with red, green, and blue emitters, in general using a four-wire connection with one common lead (anode or cathode). Others, however, have only two leads (positive and negative) and have a built-in electronic control unit. Decorative-multicolor LEDs incorporate several emitters of different colors supplied by only two lead-out wires. Colors are switched internally by varying the supply voltage. Alphanumeric LEDs are available in seven-segment, starburst, and"
"Nick Holonyak Nick Holonyak Jr. (born November 3, 1928) is an American engineer and educator. He is noted particularly for his 1962 invention of a light-emitting diode (LED) that emitted visible red light instead of infrared light; Holonyak was then working at General Electric's research laboratory in Syracuse, New York. He is a John Bardeen Endowed Chair Emeritus in Electrical and Computer Engineering and Physics at the University of Illinois at Urbana-Champaign, where he has been since leaving General Electric in 1963. In addition to introducing the III-V alloy LED, Holonyak holds 41 patents. His other inventions include the red-light"
"or yellowish light was given off at the contact point. Round had constructed a light emitting diode (LED). However he just published a brief two paragraph note about it and did no further research. While investigating crystal detectors in the mid-1920s at Nizhny Novgorod, Oleg Losev independently discovered that biased carborundum and zincite junctions emitted light. Losev was the first to analyze this device, investigate the source of the light, propose a theory of how it worked, and envision practical applications. He published his experiments in 1927 in a Russian journal, and the 16 papers he published on LEDs between"
"but with rising power output, it has grown increasingly necessary to shed excess heat to maintain reliability, so more complex packages have been adapted for efficient heat dissipation. Packages for state-of-the-art high-power LEDs bear little resemblance to early LEDs. Blue LEDs were first developed by Herbert Paul Maruska at RCA in 1972 using gallium nitride (GaN) on a sapphire substrate. SiC types were first commercially sold in the United States by Cree in 1989. However, neither of these initial blue LEDs were very bright. The first high-brightness blue LED was demonstrated by Shuji Nakamura of Nichia Corporation in 1994 and"
"1989, during systematic characterisation of a newly synthesised conductive polymer, Chloe Jennings working in Holmes' research group observed that the polymer emitted light when a current was passed through it. An intensive period of research in Holmes' group, and other polymer chemistry groups, led to the discovery of differently-coloured light-emitting polymers that spanned the visible colour spectrum. A subsequent collaboration with physicist Richard Friend and co-workers at Cambridge's Cavendish Laboratory revealed the potential of these conjugated polymers for applications such as organic LEDs and rollable displays. Friend and Holmes co-founded the company Cambridge Display Technology for commercial exploitation of these"
"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 red and green frequencies creating a light that appears white. Isamu Akasaki, Hiroshi Amano and Nakamura were later awarded the 2014 Nobel Prize in Physics for the invention of the blue LED. China further boosted LED research and development in 1995 and demonstrated its first LED Christmas tree in 1998. The new LED technology application then became prevalent at the start of the 21st century by US (Cree) and Japan (Nichia,"
"Light-emitting diode A light-emitting diode (LED) is a two-lead semiconductor light source. It is a p–n junction diode that emits light when activated. When a suitable current is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence, and the color of the light (corresponding to the energy of the photon) is determined by the energy band gap of the semiconductor. LEDs are typically small (less than 1 mm) and integrated optical components may be used to shape the radiation pattern. Appearing as"
"student of Holonyak, invented the first yellow LED and improved the brightness of red and red-orange LEDs by a factor of ten in 1972. In 1976, T. P. Pearsall created the first high-brightness, high-efficiency LEDs for optical fiber telecommunications by inventing new semiconductor materials specifically adapted to optical fiber transmission wavelengths. The first commercial LEDs were commonly used as replacements for incandescent and neon indicator lamps, and in seven-segment displays, first in expensive equipment such as laboratory and electronics test equipment, then later in such appliances as TVs, radios, telephones, calculators, as well as watches (see list of signal uses)."
"capacitance diode) in 1959. In 1955, Jun-ichi Nishizawa invented the first solid-state maser. In 1957, Nishizawa invented the semiconductor laser, and discovered semiconductor inductance. The continuous wave semiconductor laser was invented by Izuo Hayashi and Morton B. Panish in 1970. This led directly to the light sources in fiber-optic communication, laser printers, barcode readers, and optical disc drives, technologies that were commercialized by Japanese entrepreneurs. In 1992, Japanese inventor Shuji Nakamura invented the first efficient blue laser (blue LED). Nakamura invented it with Isamu Akasaki and Hiroshi Amano, for which the three of them were awarded the 2014 Nobel Prize"
"both the Optoelectronic branch and the MOS branch in the Semiconductor Research and Development Lab (SRDL) at Texas Instruments (TI). In 1964, TI's Opto branch developed a monolithic visible LED element consisting of a 3x5 array of red LEDs capable of displaying the numbers 0-9. The device was lacking a means of driving the array, so Dr. Biard and Bob Crawford (from the MOS branch) designed a P-channel MOS circuit using binary coded decimal inputs to turn on the appropriate 15 output lines. The MOS circuit worked on the first pass and was implemented into a simulated cockpit altimeter. In"
"through, maintaining a more constant colour over the life of the lamp. These are usually referred as ceramic metal-halide lamps or CMH lamps. The concept of adding metallic iodides for spectral modification (specifically: sodium - yellow, lithium - red, indium - blue, potassium and rubidium - deep red, and thallium - green) of a mercury arc discharge to create the first metal-halide lamp can be traced to patent US1025932 in 1912 by Charles Proteus Steinmetz, the ""Wizard of General Electric"". The amount of mercury used has lessened over years of progress. Most types are fitted with an outer glass bulb"
"was only in the main regions. It was later that year on 2 December for the full country to receive colour transmissions, and because of these different dates, it is difficult to see when this ident was introduced. The ident was originally a cube with a '2' on each face, each a different colour. The ident would start by three light spots of red, green and blue, the three primary colours for television. These light spots then merge to form a white spot. Around this spot, a blue numeral '2' would form up by drawing it. The 'COLOUR' legend would"
"court in a lawsuit brought by veterans in 1984. In 1968, it became the first company to start mass production of (visible) light-emitting diodes (LEDs), using gallium arsenide phosphide. From 1968 to 1970, sales doubled every few months. Their products (discrete LEDs and seven-segment numeric displays) became industry standards. The primary markets then were electronic calculators, digital watches and digital clocks. Monsanto became a pioneer of optoelectronics in the 1970s. Between 1968 and 1974, the company sponsored the PGA Tour event in Pensacola, Florida, which was renamed the Monsanto Open. In 1974, Harvard University and Monsanto signed a 10-year research"
"light of a blue-emitting LED are transformed by quantum dots into small-bandwidth green and red light such that the combined white light allows for a nearly ideal color gamut generated by the color filters of the LCD panel. In addition, efficiency is improved, as intermediate colors (wavelengths) are not present anymore and don't have to be filtered out by the RGB color filters of the LCD screen. US company QD Vision worked with Sony to launch LCD TVs using this technique under the marketing label ""Triluminos"" in 2013. At the Consumer Electronics Show 2015, Samsung Electronics, LG Electronics, the Chinese"
"spectrum have been available since the invention of the ruby laser in 1960. In 1962 the red helium–neon laser was invented, and these two types of lasers were widely used in many scientific applications including holography, and in education. Red helium–neon lasers were used commercially in LaserDisc players. The use of red laser diodes became widespread with the commercial success of modern DVD players, which use a 660 nm laser diode technology. Today, red and red-orange laser diodes are widely available to the public in the form of extremely inexpensive laser pointers. Portable, high-powered versions are also available for various"
"lamps used colored glass. Light-emitting diode (LED) holiday lights are quickly gaining popularity in many places due to their low energy usage, long lifetime, and associated low maintenance. Colored LEDs are far more efficient at producing light than their colored incandescent counterparts. There are two types of LEDs: colored LEDs and white LEDs. Colored LEDs emit a specific color light (monochromatic light), regardless of the color of the transparent plastic lens that encases the LED's chip. The plastic may be colored for cosmetic reasons, but does not substantially affect the color of the light emitted. Holiday lights of this type"
"LCDs are not self-illuminating (unlike pure-LED systems). There are several methods of backlighting an LCD panel using LEDs, including the use of either white or RGB (Red, Green, and Blue) LED arrays behind the panel and edge-LED lighting (which uses white LEDs around the inside frame of the TV and a light-diffusion panel to spread the light evenly behind the LCD panel). Variations in LED backlighting offer different benefits. The first commercial full-array LED-backlit LCD TV was the Sony Qualia 005 (introduced in 2004), which used RGB LED arrays to produce a color gamut about twice that of a conventional"
"semiconductor laser, usually called the laser diode (used in CD and DVD players and cell phones) and the shorted emitter p-n-p-n switch (used in light dimmers and power tools). In 2006, the American Institute of Physics decided on the five most important papers in each of its journals since it was founded 75 years ago. Two of these five papers, in the journal ""Applied Physics Letters"", were co-authored by Holonyak. The first one, co-authored with S. F. Bevacqua in 1962, announced the creation of the first visible-light LED. The second, co-authored primarily with Milton Feng in 2005, announced the creation"
"disc. The lamp units and background on a mounting system known as a ""spider,"" were integrated into a single unit. A system combining aspects of the colour and position systems was developed on the Baltimore and Ohio Railroad (B&O) in 1920 and was patented by L.F. Loree and F.P. Patenall. It is similar to the position light system with the central light removed and the resulting pairs of lights colored in correspondence to the angle they make: green for the vertical pair, amber for the right diagonal pair, and red for the horizontal pair. An additional pair, colored ""lunar white"","
"1978, James P Mitchell described, prototyped and demonstrated what was perhaps the earliest monochromatic flat panel LED television display LED Display targeted at replacing the CRT. The basic idea of using three monochrome images to produce a color image had been experimented with almost as soon as black-and-white televisions had first been built. Among the earliest published proposals for television was one by Maurice Le Blanc in 1880 for a color system, including the first mentions in television literature of line and frame scanning, although he gave no practical details. Polish inventor Jan Szczepanik patented a color television system in"
"the first blue electroluminescence from zinc-doped gallium nitride, though the subsequent device Pankove and Miller built, the first actual gallium nitride light-emitting diode, emitted green light. In 1974 the U.S. Patent Office awarded Maruska, Rhines and Stanford professor David Stevenson a patent for their work in 1972 (U.S. Patent US3819974 A) and today, magnesium-doping of gallium nitride remains the basis for all commercial blue LEDs and laser diodes. In the early 1970s, these devices were too dim for practical use, and research into gallium nitride devices slowed. In August 1989, Cree introduced the first commercially available blue LED based on"
"color gamut. A widespread practical application is using quantum dot enhancement film (QDEF) layer to improve the LED backlighting in LCD TVs. Light from a blue LED backlight is converted by QDs to relatively pure red and green, so that this combination of blue, green and red light incurs less blue-green crosstalk and light absorption in the color filters after the LCD screen, thereby increasing useful light throughput and providing a better color gamut. The first manufacturer shipping TVs of this kind was Sony in 2013 as ""Triluminos"", Sony's trademark for the technology. At the Consumer Electronics Show 2015, Samsung"
"June 1929 using three complete systems of photoelectric cells, amplifiers, glow-tubes and color filters, with a series of mirrors to superimpose the red, green and blue images into one full color image. The first practical hybrid system was again pioneered by John Logie Baird. In 1940 he publicly demonstrated a color television combining a traditional black-and-white display with a rotating colored disc. This device was very ""deep"", but was later improved with a mirror folding the light path into an entirely practical device resembling a large conventional console. However, Baird was not happy with the design, and as early as"
"the NTSC 1953 color gamut. Using white LEDs as the backlight improves this further. In September 2009 Nanoco, a UK company, announced that it had signed a joint development agreement with a major Japanese electronics company under which it will design and develop quantum dots (QD) for use in LED backlights in LCD televisions. Quantum dots are valued for displays, because they emit light in very specific Gaussian distributions. This can result in a display that more accurately renders the colors that the human eye can perceive. To generate white light best suited as an LCD backlight, parts of the"
"involving 1,2-dioxetanedione (note that many side-groups of the aromatic rings are not shown.): The reaction rate is pH dependent, and slightly alkaline conditions achieved by adding a weak base, e.g. sodium salicylate, will produce brighter light. Developed by American Cyanamid in the 1960s, the formulation containing CPPO, a fluorescor, and a glass capsule containing hydrogen peroxide and a base catalyst, all in dialkyl phthalate solvents, was marketed as Cyalume. The following colors can be produced by using different dyes: Bis-(2,4,5-trichloro-6-(pentyloxycarbonyl)phenyl)oxalate Bis-[2,4,5-trichloro-6-(pentyloxycarbonyl)phenyl]oxalate (also known as bis(2,4,5-trichloro-6-carbopentoxyphenyl) oxalate or CPPO) is a solid ester whose oxidation products are responsible for the chemiluminescence"