Everything you ever wanted to know about LCD monitors

Everyone loves a nice LCD monitor. And why not?

You can now bag yourself a half-decent 22 inch LCD monitor for under £150.

But how much do you really know about the technology that goes into these widescreen wonders? The next time you buy an LCD monitor, will you have a clue what you're buying? Or will you be winging it based on little more than size, price and maybe the number of input options?

Fear not - we're going to give you all the information you need to sort the good LCD panels from the bad.

Monitor makers may have a nasty habit of fluffing up spec sheets with all manner of distracting disinformation. But we'll help you keep them honest with the most powerful weapon of all – knowledge.

Not all LCD monitors are the same

If you come away with just one insight from this LCD technology expose, for the love of liquid crystal make it the appreciation that not all LCD monitors are the same.

In fact, there are three major types of LCD panel technology - TN, IPS and VA. Each has its own very distinct characteristics in metrics such as pixel response, contrast and viewing angles. No single panel type is superior across the board.

However, before we trot out the various pros and cons, it's worth understanding the basic principles that underpin any LCD display, from a simple monochrome panel in an ancient pocket calculator to the latest high screens with millions of eye-popping colours. LCD, of course, stands for liquid crystal display. Each picture element, or pixel, in an LCD panel is made up of just that, a cell containing liquid crystals.

On a desktop LCD monitor, there are thousands – if not millions – of these pixels, arranged in a grid pattern. Behind this grid is a light source, literally the backlight. When an electric current is passed through the crystals courtesy of a pair of transparent electrodes, they realign themselves. Precise techniques vary between panel types, but the idea is that there are two basic positions or states the crystals can assume. In one, light is allowed to pass through, in the other it's blocked out.

OK, it's actually a little more complicated than that. The crystals don't block light, they polarise it in a certain plane, and in combination with static polarisation filters, light either passes through the LCD panel or is blocked. What's more, the crystals can assume intermediate positions, allowing some but not all light to pass through. But you get the idea.

Now, on a full colour LCD panel, every pixel is actually made up of three individual elements, each with a colour filter – red, green and blue. However, these elements are so tiny, the light emitted by them is amalgamated at normal viewing distances. Hence, by varying the intensity of light that passes through these elements, a full palate of hues is generated and Bob's your mother's technicolour brother.

Those principles all LCD panels share, but there are lots of detail differences. For instance: some panel types block light more efficiently, allowing deeper blacks and greater contrast.

In others, the liquid crystals change state more rapidly, delivering better pixel response and hence sharper moving images. Still others offer finer control of the positions that the crystals assume, giving superior colour accuracy. But which are best in what areas?