Browse Definitions :
Definition

light-emitting diode (LED)

Also see laser diode.

A light-emitting diode (LED) is a semiconductor device 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 blue-violet (about 400 nanometers). Some LEDs emit infrared (IR) energy (830 nanometers or longer); such a device is known as an infrared-emitting diode (IRED).

An LED or IRED consists of two elements of processed material called P-type semiconductors and N-type semiconductors. These two elements are placed in direct contact, forming a region called the P-N junction. In this respect, the LED or IRED resembles most other diode types, but there are important differences. The LED or IRED has a transparent package, allowing visible or IR energy to pass through. Also, the LED or IRED has a large PN-junction area whose shape is tailored to the application.

Benefits of LEDs and IREDs, compared with incandescent and fluorescent illuminating devices, include:

  • Low power requirement: Most types 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.

Typical applications include:

  • Indicator lights: These can be two-state (i.e., on/off), bar-graph, or alphabetic-numeric readouts.

  • LCD panel backlighting: Specialized white LEDs are used in flat-panel computer displays.

  • 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 main unit.

  • Optoisolator: Stages in an electronic system can be connected together without unwanted interaction.

This was last updated in September 2005
SearchNetworking
SearchSecurity
  • man in the browser (MitB)

    Man in the browser (MitB) is a security attack where the perpetrator installs a Trojan horse on the victim's computer that is ...

  • Patch Tuesday

    Patch Tuesday is the unofficial name of Microsoft's monthly scheduled release of security fixes for the Windows operating system ...

  • parameter tampering

    Parameter tampering is a type of web-based cyber attack in which certain parameters in a URL are changed without a user's ...

SearchCIO
  • e-business (electronic business)

    E-business (electronic business) is the conduct of business processes on the internet.

  • business resilience

    Business resilience is the ability an organization has to quickly adapt to disruptions while maintaining continuous business ...

  • chief procurement officer (CPO)

    The chief procurement officer, or CPO, leads an organization's procurement department and oversees the acquisitions of goods and ...

SearchHRSoftware
SearchCustomerExperience
  • first call resolution (FCR)

    First call resolution (FCR) is when customer service agents properly address a customer's needs the first time they call.

  • customer intelligence (CI)

    Customer intelligence (CI) is the process of collecting and analyzing detailed customer data from internal and external sources ...

  • clickstream data (clickstream analytics)

    Clickstream data and clickstream analytics are the processes involved in collecting, analyzing and reporting aggregate data about...

Close