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Difference between TN and IPS screens

LCD technology is constantly developing, evolving and bettering itself. It's no secret that when the first LCDs came out, their only real advantage over the older bulkier tubes was portability. They were black and white, small sized, coarse pixel panels that offered little more image fidelity than a typical calculator display. Liquid Crystals Displays produce an image by controlling the opacity of individual pixels (cells) to regulate the amount of light passing through each pixel. The solution of liquid crystals contained in every LCD panel is transparent when observed through a polarizing filter from one angle, but becomes opaque from another angle. The electric current that flows from a negative terminal to a positive terminal in an LCD cell is able to coax the solution of liquid crystals to switch positions and thus control the transparency. Each pixel on an LCD panel can be thought of as a window with electric shutters.

The era of modern colour LCDs began with TN panels. Twisted Nematic is a method of positioning the shutters formed by the liquid crystal solution when electricity is applied to each individual pixel. One of the notable characteristics of TN screens is that they are normally transparent, unless activated. TN panels provide the fastest rate of switching (response rate) and can cycle the shutters with-in 2ms or less. But at the same time TN panels provide limited viewing angles, with picture having the best quality only when observed at the direct right angle to the screen. But as soon as you look from the side or from an angle below or above, the colors begin to fade, lighting becomes odd or even inverted, contrast becomes milky. That is the effect of the shutters - while they are intended to be open to unblock the light from direct front they also start blocking the light when observed from the side due to their positioning.

To address the disadvantage of the TN method LCD manufacturers started introducing In Plane Switching (IPS) panels. Some of the manufacturers have their own proprietary brands of the IPS technology, like PLS (Plane to line switching) by Samsung and AHVA (Advanced Hyper Viewing Angle) by AUO. But the principle behind the technology is the same - the blinds have been repositioned sideways, becoming opaque by default and opening up when electricity is applied. This change has significantly improved the viewing angles, allowing great picture even from the most extreme 90 degree angles and a great colour reproducibility due to the improved transparency. The disadvantage of IPS type panels is that they are not as fast switching as the TN panels, individual pixels (cells) can take as long as 20ms to switch states. That is why the majority of high refresh rate panels such as 120Hz, 144Hz and even 240Hz are all still mostly TN panels. However, newer IPS displays are catching up and there are 120Hz panels available on the market that use IPS technology.

When it comes to ordering the correct screen for your laptop, we always recommend to replace it with the same type and the same resolution. However, if your laptop released with both types available from the manufacturer, our website will offer both versions. In such cases the IPS is likely going to be a preferred option, provided that your old screen has the same video connector pin count as the option you are considering.


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