LED lamp

LED lamp
Name	LED lamp
Caption	A modern LED bulb with E27 screw base
Classification	Solid-state lighting
Inventor	Multiple contributors including Nick Holonyak
First production	1962 (first practical LED)
Related	Compact fluorescent lamp, Incandescent light bulb

LED lamp. A light-emitting diode lamp is an electric light that produces illumination using light-emitting diodes. These lamps are significantly more efficient than traditional incandescent light bulbs and can surpass even compact fluorescent lamps in longevity and energy savings. Their development represents a major shift in lighting technology, driven by advancements in semiconductor physics and materials science.

History

The foundational work began with early 20th-century discoveries in electroluminescence by H. J. Round and Oleg Losev. The first practical visible-spectrum LED was invented in 1962 by Nick Holonyak while working at General Electric. Throughout the 1970s and 1980s, researchers at corporations like Monsanto Company and Hewlett-Packard developed brighter red, yellow, and green LEDs. A critical breakthrough came in the 1990s with the invention of the high-brightness blue LED by Shuji Nakamura at Nichia Corporation, for which he, alongside Isamu Akasaki and Hiroshi Amano, later received the Nobel Prize in Physics. This enabled the creation of white light and spurred rapid commercialization, leading to widespread adoption following initiatives like the Energy Independence and Security Act of 2007 in the United States.

Technology and operation

An LED lamp's core component is a semiconductor diode chip housed within a package. When a forward voltage is applied across the p–n junction, electrons recombine with electron holes, releasing energy in the form of photons, a process called electroluminescence. The color of the light is determined by the energy band gap of the semiconductor material; for instance, aluminium gallium indium phosphide is used for red and yellow, while indium gallium nitride is used for blue and green. To produce white light, common methods include combining red, green, and blue LEDs or, more typically, using a blue LED coated with a phosphor such as cerium-doped yttrium aluminium garnet. The assembly includes a driver circuit, often with components from firms like Texas Instruments, to regulate current from the mains electricity supply.

Types and configurations

LED lamps are manufactured in a vast array of form factors to replace traditional bulbs, including shapes that mimic A-shape, globe, and PAR lamps. Common base types include the E26/E27 and B22. Specialized configurations include LED tubes designed to retrofit fluorescent lamp fixtures, integrated LED panel lights for office ceilings, and HID replacement lamps for stadiums. Decorative types include flexible LED strip lights and Christmas light strings. For outdoor and industrial use, robust fixtures from companies like Cree, Inc. and Signify (company) are prevalent.

Applications

Their efficiency and durability have led to ubiquitous use. In residential settings, they are common in table lamps and recessed light fixtures. Commercially, they dominate lighting in offices, retail stores like Walmart, and hospitals. Municipalities use them for street lights, as seen in projects by the Los Angeles Department of Water and Power. They are integral to automotive lighting for headlamps and traffic lights, and in electronics for backlights in televisions from Samsung and smartphones from Apple Inc.. Specialized applications include grow lights for agriculture and ultraviolet lamps for sterilization.

Comparison with other lighting technologies

Compared to an incandescent light bulb, an LED lamp uses about 75-90% less energy for the same luminous flux and can last 25 times longer. Against a compact fluorescent lamp, LEDs typically offer better color rendering index, instant full brightness, contain no mercury (element), and have a longer operational life, though initial cost is often higher. While halogen lamps have excellent color quality, they are far less efficient. Even compared to traditional fluorescent lamps, LEDs generally provide superior efficiency, durability, and directional control, leading to their rapid displacement in markets worldwide.

Environmental impact and efficiency

The primary environmental benefit is drastically reduced energy consumption, lowering greenhouse gas emissions from power plants. A typical LED lamp converting much of its energy directly to light minimizes waste heat. While their manufacture involves materials like gallium and arsenic, which require careful handling, the extended lifespan reduces waste frequency compared to other bulbs. Recycling programs, such as those promoted by the Environmental Protection Agency, aim to recover components. Their efficiency aligns with global standards like the European Union's Ecodesign Directive and has been a key factor in meeting the goals of the Paris Agreement on climate change.

Category:Lighting Category:Energy conservation Category:American inventions