What is LED?

Answer 1

An LED is a Light Emitting Diode. It is a semiconductor device designed to produce a certain type, wavelength, etc. of light.

As opposed to an LCD which is a Liquid Crystal Display, does not emit light of any real intensity, although excitation methods have been developed for use in TV's, cellphones, etc. More common now than LED's. The major difference is that LED's have to have power all the time to emit. LCD's just need power to change. So, they are more energy efficient.

Answer 2

Light Emitting Diodes, special composite semiconductor diodes that emit light when forward biased. The exact composite semiconductor used depends on the desired color. One composite semiconductor used in some LEDs is Gallium Aluminum Indium Phosphide.

In ordinary silicon or germanium diodes when an electron and a hole recombine at the junction a low energy photon way in the far IR is emitted. It does not travel far though as these semiconductor materials are totally opaque, so it is absorbed and all it does is heat the diode.

In LEDs however things are much different. In LEDs when an electron and a hole recombine at the junction a higher energy photon of the desired color is emitted (IR, visible light, UV). For this photon to escape and be useful the semiconductor material must also be transparent at its wavelength, or it would only be absorbed and heat the semiconductor.

The forward bias knee voltage of a diode is proportional to the energy of the photons it emits when an electron and a hole recombine at the junction:

1. germanium 0.2V - far IR
2. silicon 0.7V - far IR
3. IR LED 1.0V - IR
4. Red LED 1.5V - Red
5. Orange LED 2.0V - Orange
6. Yellow LED 3.0V - Yellow
7. Green LED 4.5V - Green
8. Blue LED 6.0V - Blue
9. UV LED 7.0V - UV

White light LEDs are manufactured in one of two ways:

• package three different LEDs together - Red, Green, Blue so it looks to humans as white
• package a UV LED inside a phosphor coating, which converts the UV photons to visible light photons (similar to florescent lights)

Answer 3

LED stands for Light Emitting Diode. This is a piece of semiconducting material that will emit photons when electricity is passed through it. An LED display is simply a display that consists of more than one LED used to display information or sometimes images. A large scale application are sometimes seen in sports stadiums.

Answer 4

An LED bulb is made up of one or more light-emitting diodes, encased in plastic for protection. LEDs produce light much more efficiently than incandescent bulbs, with about 90% less heat, and are beginning to replace them in many applications.

Answer 5

Changes electric energy to light. Visible or IR or UV

Used as a simple indicator on/off warning, etc.

In an array to create digits, like a display on your DVD player.

In opto isolators, shines on phototransistor to control high voltages with a small signal

Soon, as a very cost effective source of light for homes- better than CFL of today.

Answer 6

LED Stands for Light Emmiting Diodes and Displays are the screens are made of Light emitting techniques.LED Displays are one of the best medium for promoting our business locally or glabally.Generally LED stands for Light Emitting Diode is a semiconductor light source and LED also a chemical compound that gives off light when an electrical current passes through it.

Some Common points of LED Are :

• pixel?
• Standard Definition
• High Definition
• Viewing angle

Answer 7

LED stands for Light Emitting Diode. LED displays text, images, and videos, if the lights on the LED display screen are lit at the same time, it means that the display screen is a static screen. it uses the characteristics of human visual persistence to light up each row of the LED display in a short period of time, which means that the screen is a screen.

Answer 8

led is something that is in a macanical pencil and it writes!!you must be really stupid or what?