Editing TFT LCD (section)

===Twisted nematic (TN){{anchor|TN}}===
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[[File:Dell axim LCD under microscope.jpg|thumb|TN display under a microscope, with the transistors visible at the bottom]]

The [[twisted nematic]] (TN) display is one of the oldest and frequently cheapest kind of liquid crystal display technologies. TN displays have fast pixel response times and less smearing than other types of LCDs like [[IPS display]]s, but suffer from poor color reproduction and limited viewing angles, especially in the vertical direction. When viewed at an angle that is not perpendicular to the display, colors will shift, sometimes to the point of completely inverting. Modern, high end consumer products have developed methods to overcome the technology's shortcomings, such as [[Response Time Compensation|RTC (Response Time Compensation / Overdrive) technologies]]. Modern TN displays can look significantly better than older TN displays from decades earlier, but overall TN has inferior viewing angles and poor color in comparison to other technology like IPS.

Most TN panels can represent colors using only six [[bit]]s per RGB channel, or 18 bit in total, and are unable to display the 16.7 million color shades (24-bit [[24-bit color|truecolor]]) that are available using 24-bit color. Instead, these panels display interpolated 24-bit color using a [[dither]]ing method that combines adjacent pixels to simulate the desired shade. They can also use a form of temporal dithering called [[Frame Rate Control]] (FRC), which cycles between different shades with each [[refresh rate|new frame]] to simulate an intermediate shade. Such 18 bit panels with dithering are sometimes advertised as having "16.2 million colors". These color simulation methods are noticeable to many people and highly bothersome to some.<ref>{{cite web|url=http://www.xbitlabs.com/articles/monitors/display/lcd-guide_11.html|title=X-bit's Guide: Contemporary LCD Monitor Parameters and Characteristics (page 11)|author=Oleg Artamonov|publisher=Xbitlabs.com|date=2004-10-26|access-date=2009-08-05|url-status=dead|archive-url=https://web.archive.org/web/20090519104937/http://www.xbitlabs.com/articles/monitors/display/lcd-guide_11.html|archive-date=2009-05-19}}</ref> FRC tends to be most noticeable in darker tones, while dithering appears to make the individual pixels of the LCD visible. Overall, color reproduction and linearity on TN panels is poor. Shortcomings in display color [[gamut]] (often referred to as a percentage of the [[RGB color space|NTSC 1953 color gamut]]) are also due to backlighting technology. It is common for older displays to range from 10% to 26% of the NTSC color gamut, whereas other kind of displays, utilizing more complicated CCFL or LED [[phosphor]] formulations or RGB LED backlights, may extend past 100% of the NTSC color gamut, a difference that is easily seen by the human eye.

The [[transmittance]] of a pixel of an LCD panel typically does not change linearly with the applied voltage,<ref name="matuszczyk">Marek Matuszczyk, [http://www.mc2.chalmers.se/pl/lc/engelska/applications/Displays.html Liquid crystals in displays] {{Webarchive|url=https://web.archive.org/web/20041223045600/http://www.mc2.chalmers.se/pl/lc/engelska/applications/Displays.html |date=2004-12-23 }}. Chalmers University Sweden, c. 2000.</ref> and the [[sRGB]] standard for computer monitors requires a specific nonlinear dependence of the amount of emitted light as a function of the [[RGB]] value.