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Learn what is LED, how it works, and what are its advantages over incandescent lamps. Explore the types, colours, and applications of LEDs with examples and diagrams.
- LEDs have a wide range of applications ranging from your mobile phone to large advertising billboards. They mostly find applications in devices tha...
- LEDs work on the principle of Electroluminescence. On passing a current through the diode, minority charge carriers and majority charge carriers re...
- Electroluminescence is an optical phenomenon, and electrical phenomenon where a material emits light in response to an electric current passed thro...
- LEDs consume less power, and they require low operational voltage. No warm-up time is needed for LEDs.
Main article: Light-emitting diode physics. In a light-emitting diode, the recombination of electrons and electron holes in a semiconductor produces light (be it infrared, visible or UV), a process called " electroluminescence ". The wavelength of the light depends on the energy band gap of the semiconductors used.
- What Is A Light Emitting Diode (LED)?
- How Does A Light Emitting Diode (LED) Work?
- Color of An Led
- Dimming
- Reliability
- White LEDs
- Luminous Efficacy
Older LED technologies used gallium arsenide phosphide (GaAsP), gallium phosphide (GaP), and aluminum gallium arsenide (AlGaAs). LEDs generate visible radiation by electroluminescence phenomenon when a low-voltage direct current is applied to a suitably doped crystal containing a p-n junction, as shown in the diagram below. The doping is typically ...
When the forward biased current IF is applied through the p-n junction of the diode, minority carrier electrons are injected into the p-region and corresponding minority carrier electrons are injected into the n-region. Photon emission occurs due to electron-hole recombination in the p-region. Electron energy transitions across the energy gap, call...
The color of an LED device is expressed in terms of the dominant wavelength emitted, λd (in nm). AlInGaP LEDs produce the colors red (626 to 630 nm), red-orange (615 to 621 nm), orange (605 nm), and amber (590 to 592 nm). InGaN LEDs produce the colors green (525 nm), blue green (498 to 505 nm), and blue (470 nm). The color and forward voltage of Al...
LEDs may be dimmed to give 10% of their rated light output by reducing the drive current. LEDs are generally dimmed using Pulse Width Modulation techniques.
The rated maximum junction temperature (TJMAX) is the most critical parameter for an LED. Temperatures exceeding this value usually result in damage of the plastic encapsulated LED device. Mean Time Between Failures (MTBF) is used to find out the average life for LED. MTBF is determined by operating a quantity of LED devices at rated current in an ...
White LEDs are being manufactured now using two methods: In the first method red, green, and blue LED chips are combined in the same package to produce white light; In the second method phosphorescence is used. Fluorescence in the phosphor that is encapsulated in the epoxy surrounding the LED chip is activated by the short-wavelength energy from th...
Luminous efficacy of LED is defined as the emitted luminous flux (in lm) per unit electrical power consumed (in W). Blue LEDs have a rated internal efficacy in the order of 75 lm/W; red LEDs, approximately 155 lm/W; and amber LEDs, 500 lm/W. Taking into consideration losses due to internal re-absorption, the luminous efficacy is on the order of 20 ...
Jul 4, 2024 · Commonly available colors of LED are red, green, blue, yellow, amber and white. The light from red, blue and green colors can be easily combined to produce white light with limited brightness. The working voltage of red, green, amber and yellow colors is around 1.8 volts. The actual range of working voltage of a light emitting diode can be ...
Jul 17, 2024 · LED, in electronics, a semiconductor device that emits infrared or visible light when charged with an electric current. LED displays began to be used for consumer electronic devices starting in 1968, when Hewlett-Packard (HP) introduced the first LED display. Visible LED lights are used in many electronic devices as indicator lamps, car brake ...
- The Editors of Encyclopaedia Britannica
Learn how light emitting diodes (LEDs) produce light by moving electrons in a semiconductor material. Find out how LEDs are more efficient, durable and versatile than incandescent bulbs and other lighting options.
Learn how to use LEDs, the bacon of electronics, in your projects. Find out about polarity, current, resistance, and how to make LED circuits without math.
