IPS (In-Plane Switching Or Super-TFT)
Figure 2 : If voltage is applied, the molecules align themselves parallel to the substrate.
IPS, or "In-Plane Switching" technology was developed by Hitachi and NEC. It is one of the first generations of LCD technology intended to iron out the worst problems posed by TN + film. But the fact of the matter is that, while the viewing angle has expanded to 170°, the remaining features are still stuck at their old levels. The response time for these displays ranges from 50 to 60 ms, while the actual display of colors is still mediocre.
If no voltage has been applied to an IPS system, the liquid crystals don't rotate at all. The second filter is always perpendicular to the first one, thus keeping the light from passing through it. The screen itself displays a deep, perfect black. This is another area in which these displays are better than their TN rivals - if a transistor burns out, the "dead" pixel won't be a piercing, distracting white, but a subtler black.
When the subpixels are exposed to voltage, the two electrodes applying the electric field cause the crystals to rotate into a position perpendicular to their resting position. They are then aligned with the polarizing filter and the light can pass through.
The problem with this system is that actually applying the electric field using two electrodes gobbles up lots of power and, even worse, takes a while to have an effect. This explains why IPS monitors often, if not always, react more slowly than TN screens.
On the other hand, however, IPS's perfect alignment of the crystals with the filter makes for a substantial improvement in the viewing angle.