When you look at where we’ve come from, the modern LCD panel is a wondrous achievement. Not too long ago we had CRT monitors that literally took up half your desktop real estate but thankfully now we have larger, clearer and higher fidelity screens that take up hardly any room at all.
Admittedly the first LCD panels to come along were pretty subpar – but they’ve evolved into what we have now and do a great job at keeping us visually stimulated. At their core all LCDs basically function the same way - that is a Liquid Crystal is sandwiched between glass panels which are then stimulated to light up and produce a colour. These are called pixels, and are themselves made up of subpixels for the colours red, blue and green. An LCD screen has millions of these pixels and it’s the turning off and on of these pixels and subpixels that make you able see images and video on your screen. The technology behind the LCD panel has gone in several different directions during its evolution leading to today where we have several distinct avenues vying for your purchasing dollar. Let’s take a look at 3 of most popluar technologies that drive modern LCD’s.
The first LCD panel type we will look at is Twisted Nematic (TN). This is by far the most popular type of LCD as it is the cheapest and offers very fast response times – making it a great choice for gaming. With Twisted Nematic, the Nematic Liquid Crystal is placed vertically between 2 polarizing filters, with one at 90 degrees to the other. In an off state, when light is applied to one side it passes through the filter, then twists 90 degrees through the Nematic Liquid Crystal (hence the name Twisted Nematic) and is blocked from exiting the other side. This would show as a black pixel on the LCD screen as no light has exited. In an On state, when an electrical charge is applied, the TN cells realign so they are no longer twisting 90 degrees and therefore the light can pass through the pixel and is displayed as a colour on the screen. The amount of charge applied determines the amount of light that exits.
The advantages of TN are, as mentioned, fast refresh rates – up to 144Hz, and that they are cheap to produce. The main drawback with TN displays however is the poor viewing angles and colour reproduction can be a little off. TN cannot display all 16.7 million colours of the 24-bit true colour standard (which the more expensive LCD panels can do) but tries to fool you through a process called dithering Unfortunately – we can’t be fooled that easily.
Vertical Alignment (VA) LCD panels are the next step up from TN. With VA, the Liquid Crystals are suspended perpendicular to the glass substrates. In this “off” state, no light can pass through and will shows as black. When a current is applied, the liquid crystals rearrange themselves into a vertical position (alignment) which will allow light to pass through.
The advantages of VA LCD panels are that they are very bright, and offer great colour representation. Viewing angles with a VA panel is also a major benefit, as they don’t suffer the “bleed off” effect of TN panels. It’s not all roses however as VA technology is considered slow in terms of refresh rates and therefore don’t suit applications such as gaming. Ghosting and artifacts (the leaving behind of images once new images appear) are known issues with VA panels.
Several manufacturers have been steadily working on the VA technology and have their own updated versions. But the truth of the matter is that VA panels are becoming less popular now that In-Plane Switching technology has come down in price and more widely available.
You’re probably already familiar with In-Plane Switching (IPS) panels. They are the LCD panels that most modern tablets and higher end televisions use. They work in a similar fashion to TN panels except that the liquid crystal cells are kept horizontal and parallel to the glass substrate, thus allowing a straighter, cleaner path for light to travel through. IPS uses two transistors, one at each end of the liquid crystal to move it, which helps keep it in parallel. This is different to TN which uses only one transistor to apply a current to the liquid crystal and can result in uniform twisting. Also, IPS liquid crystals are not anchored to the glass substrate so can move freely when a charge is applied, unlike TN which is anchored to the lower glass substrate.
What results is spectacular colour representation and very wide viewing angles (which can actually be a bad thing when you’re privately trying to watch an episode of Black Sails while in public).
Put an IPS panel next to a TN panel and you’ll definitely notice the difference. Colours appear more vibrant and true to life (since it can display all 16.7 million colours of the True-Colour range).
As with all technology – not all is perfect and there are some disadvantages. Like VA, IPS suffers from slower refresh rates compared to TN panels. While this is not an issue when playing most games it can become noticeable during fast paced sessions. It also requires more power. As it uses two transistors the light needs to be brighter to be pushed through – which means more juice is needed.
For the most part TN monitors do a great job and most users would be fine using one of these monitors. Admittedly – if you are into fast paced gaming then TN really is your only option. IPS panels however are coming down in price and for the average gamer – and for people that use their PC for other things then stretching the budget will certainly reward you with clean, clear and vibrant coloured visuals. If you’re in the market for a new monitor go into your local retailer and look at the different LCD technologies side by side and decide what suits you best.