Light-emitting diode
hideA light-emitting diode (LED) (pronounced /ˌɛliːˈdiː/, or just /lɛd/), is an electronic light source. The LED was first invented in Russia in the 1920s, and introduced in America as a practical electronic component in 1962. Oleg Vladimirovich Losev was a radio technician who noticed that diodes used in radio receivers emitted light when current was passed through them. In 1927, he published details in a Russian journal of the first ever LED.
All early devices emitted low-intensity red light, but modern LEDs are available across the visible, ultraviolet and infra red wavelengths, with very high brightness.
LEDs are based on the semiconductor diode. When the diode is forward biased (switched on), electrons are able to recombine with holes and energy is released in the form of light. This effect is called electroluminescence and the color of the light is determined by the energy gap of the semiconductor. The LED is usually small in area (less than 1 mm2) with integrated optical components to shape its radiation pattern and assist in reflection.
LEDs present many advantages over traditional light sources including lower energy consumption, longer lifetime, improved robustness, smaller size and faster switching. However, they are relatively expensive and require more precise current and heat management than traditional light sources.
Applications of LEDs are diverse. They are used as low-energy indicators but also for replacements for traditional light sources in general lighting and automotive lighting. The compact size of LEDs has allowed new text and video displays and sensors to be developed, while their high switching rates are useful in communications technology.
For more information about Light-emitting diode, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with led
Solar Cells with LEDs Provide Inexpensive Lighting
Nov 09, 2009 |
4.4 / 5 (17) |
2
(PhysOrg.com) -- Of the 1.5 billion people in developing countries who do not have electricity, many rely on kerosene lamps for light after the sun goes down. But now, researchers from Denmark have designed ...
Sony optimistic on 3-D TVs, in-house display
Nov 26, 2009 |
4.7 / 5 (3) |
0
(AP) -- A third to a half of the Sony Corp. TV sets sold annually will be packed with 3-D features by the year ending March 2013, a senior executive said Thursday.
Search results for led
Defibrotide improves response rate in patients with severe veno-occlusive disease of the liver
2 hours ago |
not rated yet |
0
Defibrotide, a novel drug which modulates the response of blood vessels to injury, was markedly more effective than standard treatment in post-stem cell transplant patients with hepatic veno-occlusive disease, a life threatening ...
Absence of evidence for a meteorite impact event 13,000 years ago
Space & Earth / Earth Sciences
4 hours ago |
5 / 5 (5) |
5
An international team of scientists led by researchers at the University of Hawaii at Manoa have found no evidence supporting an extraterrestrial impact event at the onset of the Younger Dryas ~13000 years ...
Combination therapy with midostaurin improves survival of AML patients with FLT3 mutations, phase 1
4 hours ago |
not rated yet |
0
A targeted drug that is active against acute myeloid leukemia (AML) is particularly effective when teamed with chemotherapy in patients whose cancer cells harbor a key genetic mutation, researchers at Dana-Farber Cancer Institute ...
Getting a 'Head Start' on obesity prevention
5 hours ago |
not rated yet |
0
Almost 1 million preschool children from low-income families are enrolled in Head Start, a national program for young children that readies them for school. While the program provides them with educational and social skill ...
Severity of H1N1 flu in US during current flu season may be less than feared
5 hours ago |
not rated yet |
0
A new study from researchers at the UK Medical Research Council and the Harvard School of Public Health (HSPH) projects that the severity of the H1N1 flu during the autumn-winter flu season in the U.S. will likely be less ...
Self-destructing bacteria improve renewable biofuel production
5 hours ago |
5 / 5 (1) |
1
An Arizona State University research team has developed a process that removes a key obstacle to producing lower-cost, renewable biofuels. The team has programmed a photosynthetic microbe to self-destruct, making the recovery ...
Researchers finds hidden sensory system in the skin
5 hours ago |
5 / 5 (2) |
0
Researchers report that the human body has an entirely unique and separate sensory system aside from the nerves that give most of us the ability to touch and feel. Surprisingly, this sensory network is located throughout ...
Coroner: Self-help course led to woman's suicide
6 hours ago |
5 / 5 (3) |
0
(AP) -- An Australian coroner said Tuesday that participation in an intense self-help course led a woman to suffer a psychotic breakdown before she stripped naked and leaped to her death from an office window ...
Validity of cost-effectiveness models based on randomized clinical trials
8 hours ago |
not rated yet |
0
Cost-effectiveness studies are widely used to guide prescribing policy in many countries, as part of health technology assessment programmes. However, a new study published this week in PLoS Medicine by Tjeerd-Pieter van St ...
Decline in breast cancer: Not just because of hormone therapy
8 hours ago |
not rated yet |
0
Between 2002 and 2003, American women experienced a 7 percent decline in breast cancer incidence, which scientists attribute to the publicity surrounding results of the Women's Health Initiative (WHI).
List of search results for led
