LED
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Introduction
- A light emitting diode is a semiconductor devise that emits visible light when an electric current passes through it.
- The light is not particularly bright but, in most LEDs, it is monochromatic, occurring at a single wavelength.
- The output from an LED can range from red (at a wavelength of approximately 700 nanometers) to a blue violet (about 400 nanometers).
- Some LEDs emit infrared (IR) energy (830 nanometers or longer); such devices are known as an infrared-emitting diodes (IRED).
Technical Details
- An LED or IRED consists of two elements of processed material called the P-type semiconductors and N-type semiconductors. These two elements are placed in direct contact, forming a region called P-N junction. In this respect, the LED and IRED resemble most other diode types but there are important differences. The LED and IRED had transparent package, allowing visible or IR energy to pass through. Also, the LED and IRED has a large PN-junction area whose shape is tailored to the application.
- Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons.
Benefits of LED and IRED
- Low Power Requirement: Most can be operated with battery power supplies.
- High Efficiency: Most of the power supplied to an LED or IRED is converted into radiation in the desired form, with minimal heat production.
- Long life: when properly installed, an LED or IRED can function for decades
Other associated benefits
- Climate change
- Power deficiency help
- Mercury pollution protection (CFLs)
Typical Applications include
- Indicator lights: These can be two-state (i.e., on/off), bar graph, or alphabetical-numeric readouts.
- LCD panel backlighting: Specialized white LEDs are used in flat panel computer display
- Fiber Optic Data Transmission: Ease of modulation allows wide communications bandwidth with minimal noise, resulting in high speed and accuracy
- Remote Control: Most home entertainment “remotes” use IREDs to transmit data to the transmitter.
- Optoisolater: It is a semiconductor device that uses a short optical transmission path to transfer an electrical signal between circuits or elements of a circuit, while keeping them electrically isolated from each other.
- Lighting: LED bulbs (UJALA Scheme)