Question: How does HD television work?

Derek McKay-Bukowski answered on 16 Jun 2011:

HDTV (High-Definition Television) is a system that has a large number of squares on the screen (called pixels). For a modern system, this means 1920 pixels across and 1080 vertically. That’s 2,073,600 pixles. In order to have a smooth picture, these pixels need to be updated at least 25 times a second.

To get this to work, you need lots of things. Firstly, you need to eb able to send the signal from the television station to the HDTV set. This can be done with radio waves or via electrical signals down a cable.

Once the signals are received (one pixel a time), they need to put put onto the screen (getting them in exactly the right order… otherwise the picture would be scrambled like an unmade 2-million piece jigsaw!)

Each pixel, is actually made of three even smaller dots that are red, green and blue. Combined, these three will create the necessary colours.

The dots themselves are usually made of liquid crystal. That’s why these sorts of HDTVs are called LCD (Liquid Crystal Displays). There are other ways to do this too. One is to use plasma (ionised gas). This is a little bit brighter but it is very inefficient (= needs more electricity) so it is not as good for the environment.

By repeatedly sending new signals, the intensity of the dots change. This causes the colours of the pixels to change and thus you can animate (or reproduce) a moving image on the screen.

If you send several streams of signals, you can then choose which one you want to use. These are the channels, and they let different programmes be shown at the same time.