This week I was looking into buying a new TV. I know for sure that I’m not looking at a plasma. When the sales representative was explaining the different TVs she started describing LED TVs as better TVs. This led to the question, isn’t a LED TV a LCD display. The answer I got was no it is better than a LCD, that it worked like a LED stop light that the LEDs change colour.

This is wrong! All LED TVs are LCD TVs but all LCD TVs are not LED TVs.

What is LCD? It is basically like the old fashion calculators, as an electric current hits a liquid crystal (the LC in LCD) it rotates the crystal changing the wave lengths to make a RGBK {Red, Green, Blue, and Black} (or in a few RGBYK {adds Yellow})  to the back light.

Then what’s the diff?

The difference is in the back-light. A TV referred to by the store as a LCD TV is in-fact a lit in the back by a fluorescent back-light. This back-light will last a ;long time but will eventually burn out.  This is similar to the monitor that you are likely reading this on, like a laptop or cell phone screen (most anyways).

The LED (Light Emitting Diode) is the light bulb used to light the LCD panel. Seems to simple eh? While it is, there are two main types of LED TVs edge lit and local dimming. With edge lit the LED Bulbs are around the edge of the display and light the display. Where local dimming has lots of smaller regions that can be dimmed on and off to give a better black.

A really good website that for further reading is LCD TV Buying Guide.