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'''Active matrix''' is a type of [[addressing scheme]] used in [[flat panel displays]]. In this method of switching individual elements ([[pixel]]s) of a flat panel display, each pixel is attached to a [[transistor]] and [[capacitor]] which ''actively'' maintain the pixel state while other pixels are being addressed. This is to be contrasted with the older [[passive matrix]] technology in which each pixel must maintain its state passively, without being driven by circuitry.
'''Active matrix''' is a type of [[addressing scheme]] used in [[flat panel displays]]. The term describes a method of switching individual elements of a [[flat panel display]], using a [[Cadmium selenide|CdSe]] or [[Silicon]]-based [[thin-film transistor]] (TFT) for each [[pixel]]. The technology was invented and first demonstrated by Hungarian emigré [[T Peter Brody]] and his Thin-Film Devices department at [[Westinghouse Electric Corporation]] in 1968, and the term was introduced into the literature in 1975.<ref name=OEDActiveMatrix>{{cite web|title=[http://www.oed.com/viewdictionaryentry/Entry/1953#eid19485882 Active Matrix]|year=2011|work=[[OED]]|publisher=[[Oxford University Press]]}}{{subscription required}}</ref><ref name=Castellano>{{cite book|last=Castellano|first=Joseph A.|title=Liquid gold : the story of liquid crystal displays and the creation of an industry|year=2005|publisher=World Scientific|___location=New Jersey [u.a.]|isbn=978-981-238-956-5|pages=176|url=http://www.amazon.com/Liquid-Gold-Displays-Creation-Industry/dp/9812389563|edition=[Online-Ausg.]}}</ref><ref>{{cite doi|10.1109/T-ED.1975.18214}}</ref>▼
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Given a ''m'' × ''n'' matrix, the number of connectors needed to address the display is ''m'' + ''n''. Each [[pixel]] is attached to a switch-device, which ''actively'' maintains the pixel state while other pixels are being addressed, which also prevents [[crosstalk]] from inadvertently changing the state of an unaddressed pixel. The most common switching devices are [[Thin Film Transistor|Thin Film Transistors (TFT)]], i.e. a [[field effect transistor|FET]] based on either the cheaper [[amorphous|non-crystalline]] [[thin-film]] [[silicon]] ([[amorphous silicon|a-Si]]), [[polycrystalline]] silicon ([[polycrystalline silicon|poly-Si]]), or [[Cadmium selenide|CdSe]] [[semiconductor]] material.▼
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Another variant is to use diodes or resistors, but neither [[diode]]s (e.g. [[Metal insulator metal diode]]s), nor non-linear voltage dependent [[resistor]]s (i.e. [[varistor]]s) are currently used. The latter of these is not yet economical when compared to TFT.
The [[Macintosh Portable]] (1989) was perhaps first consumer laptop to employ an active matrix panel. Today virtually all TVs, computer monitors and smartphone screens that use [[LCD]] or [[OLED]] technology employ active matrix technology.<ref>{{cite web|title=What is OLED TV?|author=|date=1 March 2012|work=Cnet.com|url=http://reviews.cnet.com/8301-33199_7-57386898-221/what-is-oled-tv/}}</ref>
== See also ==
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* [[Pixel geometry]]
* [[LCD]]
* [[Comparison of display technology]]
==References==
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