Question

Light Emitting Diode(LED)

Answer 1

Light Emitting Diode(LED)

LED is a type of LCD that actually accompanies the advancement of technology. This replaces the fluorescent tube with backlight technology, which produces a clearer picture than the LCD. LED have wider viewing angle than the LCD. It have better black level and contrast in comparison to LCD LCD display. LED delivers better color accuracy in comparison to the LCD.

LED is a device which emits when current passes through it. It is a semiconductor device.

The size of the LED is small, so we can easily make any display unit by arranging a large number of LEDs.

LED consumes more power compared to LCD. LED is used on TV, smartphones, motor vehicles, traffic light, etc.

LEDs are powerful in structure, so they are capable of withstanding mechanical pressure. LED also works at high temperatures.

Working Principle

A light-emitting diode is a two-lead semiconductor light source. It is a p–n junction diode that emits light when activated. When a suitable voltage is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence, and the color of the light (corresponding to the energy of the photon) is determined by the energy band gap of the semiconductor.

Advantages of LEDs

1. Very low voltage and current are enough to drive the LED (Voltage range – 1 to 2 volts. Current – 5 to 20 milliamperes.)
2. Total power output will be less than 150 milliwatts.
3. The response time is very less – only about 10 nanoseconds.
4. The device does not need any heating and warm up time.
5. Miniature in size and hence lightweight.
6. Have a rugged construction and hence can withstand shock and vibrations.
7. An LED has a lifespan of more than 20 years. 

Disadvantages

1. A slight excess of voltage or current can damage the device.
2. The device is known to have a much wider bandwidth compared to the laser.
3. The temperature depends on the radiant output power and wavelength.

Difference between LED and LCD

S.NO	LED	LCD
1.	LED have better response time than LCD.	LCD is slower than LED in terms of response time.
2.	LED consumes more power in comparison to LCD.	Whereas it consumes less power in comparison to LED.
3.	LED delivers good picture quality in comparison to the LCD display.	LCD also delivers the good picture quality but less than LED.
4.	LED is costlier than LCD.	While it is less costlier than LED.
5.	LED have better black level and contrast in comparison to LCD.	While it have not good black level and contrast as LED.
6.	LED delivers better color accuracy in comparison to the LCD.	While it also delivers good color accuracy, but we can notice the difference if we compare these two.
7.	LED have wider viewing angle than the LCD.	While in LCD, the wide angle decreases with 30 degrees from the center in the image then the contrast ratio.

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