Difference Between LCD TVs and LED TVs

LCD TV vs LED TV | LCD and LED TVs | LED Televisions consumes less power

Many consumers get confused with the jargons used in the Television market, such as LCD, LED, OLED, Plasma, HDTV etc. Especially, the terms LCD TV and LED TV baffle them more. What you need to know is technically both are LCD TVs (LCD stands for Liquid Crystal Display). The only difference between LCD and LED is the Back Lighting Technology of the display.


An Image of LED Tv

Both LCD and LED TVs use Liquid Crystal Display technology. The screens are made of liquid crystal display; a LCD display has two thin plates of polarized material joined together with a liquid crystal solution between them. When an electric current passed through the liquid, the crystals align and block the light from passing through them. Therefore each crystal act a shutter, either allowing light to pass through or blocking the light. This is the technology used in LCD TVs to display the pictures.

But these crystals are not self illuminating, so the light is send from a series of lamps at the back of the LCD screen. The back lighting technology is what makes the difference between LCD and LED TV.

In the traditional LCD TV the lamp at the back of the screen is the Cold Cathode Fluorescent Lamp (CCFL), It consists of a series of fluorescent tubes laid horizontally across the screen.

When Plasma TV was introduced to market, it started to attract the consumers with its bigger flat screen and better picture quality. The picture quality in Plasma TV was amazing due to the high contrast ratio. LCD TVs couldn’t do this because of the CCFL backlighting system.

The LED backlight technology was introduced in LCD TVs to face the bigger challenge created by Plasma TVs. LED back lit LCD TVs are able to create contrast ratios closer to Plasma’s contrast ratio; still Plasma TVs better in that aspect.
In the LED TV the lights at the back of the screen are Light Emitting Diodes (LED).

Three types of LED lighting are used to provide the back lighting to the screen, RGB Dynamic LED, Edge lighting and Full Array lighting.

In Dynamic RGB LED lighting LEDs are placed behind the LCD panel and separate LEDs for Red, Green and Blue are designed to create brighter colours. This method allows dimming to happen locally in specific areas and thus improve contrast ratio.

In Edge lighting, white LEDs are placed around the edge of the screen and the light is diffused across the screen by a special panel to produce uniform colour across the screen. This method facilitates extremely slim design that we can see in the market.

In Full Array lighting, LEDs are placed in the back of the screen like Dynamic RGB LED, but it does not allow local dimming to occur. In this design the energy consumption may be low but it has not improved the picture quality.
The introduction of LED backlighting technology in TVs brought in a dramatic impact on the TV design. The TVs became thinner in size, brighter, better colour gamut, consume less power, but are quite expensive.

Technologies are continuously changing; new technologies are introduced at a fast pace to improve the product design.Sony Corporation has announced this month (December 2010) that they have developed “Hybrid FPA (field-induced photo-reactive alignment)”, a new liquid crystal alignment technique which enables a significantly faster response time for liquid crystal displays.

This facilitates the stable and even alignment of the liquid crystal molecules, thus achieving improvements in both liquid crystal response time and the contrast ratio. In addition, this has made it possible to eradicate the Mura (uniformity problem) in the display as well as to eliminate the ‘sticking image’ that can occur after long-term use.