Editing TFT LCD (section)

==Construction==
[[File:TFT Matrix.svg|thumb|A diagram of the [[pixel]] layout]]

The liquid crystal displays used in calculators and other devices with similarly simple displays have direct-driven image elements, and therefore a [[voltage]] can be easily applied across just one segment of these types of displays without interfering with the other segments. This would be impractical for a large [[display device|display]], because it would have a large number of (color) picture elements ([[pixel]]s), and thus it would require millions of connections, both top and bottom for each one of the three colors (red, green and blue) of every pixel. To avoid this issue, the pixels are addressed in rows and columns, reducing the connection count from millions down to thousands. The column and row wires attach to [[transistor]] switches, one for each pixel. The one-way current passing characteristic of the transistor prevents the charge that is being applied to each pixel from being drained between refreshes to a display's image. Each pixel is a small [[capacitor]] with a layer of [[insulator (electrical)|insulating]] liquid crystal sandwiched between transparent conductive layers of [[Indium tin oxide|indium tin oxide (ITO)]].

The circuit layout process of a TFT-LCD is very similar to that of semiconductor products. However, rather than fabricating the transistors from [[silicon]], that is formed into a [[monocrystalline silicon|crystalline silicon]] wafer, they are made from a [[thin film]] of [[amorphous silicon]] that is deposited on a [[glass]] panel. The silicon layer for TFT-LCDs is typically deposited using the [[Plasma-enhanced chemical vapor deposition|PECVD]] process.<ref>{{cite web |url=http://www.plasma.com/classroom/fabricating_tft_lcd.htm |title=TFT LCD - Fabricating TFT LCD |publisher=Plasma.com |access-date=2013-07-21 |url-status=dead |archive-url=https://web.archive.org/web/20130502060952/http://www.plasma.com/classroom/fabricating_tft_lcd.htm |archive-date=2013-05-02 }}</ref> Transistors take up only a small fraction of the area of each pixel and the rest of the silicon film is etched away to allow light to easily pass through it.

[[Polycrystalline silicon]] is sometimes used in displays that require higher TFT performance. Examples include small high-resolution displays such as those found in projectors or viewfinders. Amorphous silicon-based TFTs are by far the most common, due to their lower production cost, whereas polycrystalline silicon TFTs are more costly and much more difficult to produce.<ref>{{cite web |url=http://www.plasma.com/classroom/what_is_tft_lcd.htm |title=TFT LCD - Electronic Aspects of LCD TVs and LCD Monitors |publisher=Plasma.com |access-date=2013-07-21 |url-status=dead |archive-url=https://web.archive.org/web/20130823203913/http://www.plasma.com/classroom/what_is_tft_lcd.htm |archive-date=2013-08-23 }}</ref>