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Active matrix is a type of
addressing scheme {{unreferenced, date=June 2009, bot=yes There are three different addressing schemes for display devices: ''direct'', ''matrix'', and ''raster''. The purpose of each scheme is to set (or maintain) the state of a pixel to either black/white or, mor ...
used in
flat panel display A flat-panel display (FPD) is an electronic display used to display visual content such as text or images. It is present in consumer, medical, transportation, and industrial equipment. Flat-panel displays are thin, lightweight, provide better l ...
s. In this method of switching individual elements (
pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the s ...
s), each pixel is attached to a
transistor upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink). A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch ...
and
capacitor A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals. The effect of a ...
''actively'' maintaining the pixel state while other pixels are being addressed, in contrast with the older passive matrix technology in which each pixel must maintain its state passively, without being driven by circuitry. Active matrix technology was invented by
Bernard J. Lechner Bernard J. Lechner (25 January 1932 – 11 April 2014) was an electronics engineer and formerly vice president, RCA Laboratories, where he worked for 30 years covering various aspects of television and information display technologies. Biogra ...
at
RCA The RCA Corporation was a major American electronics company, which was founded as the Radio Corporation of America in 1919. It was initially a patent pool, patent trust owned by General Electric (GE), Westinghouse Electric Corporation, Westin ...
, using
MOSFET The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor (FET), most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate, the voltage of which d ...
s (metal-oxide-semiconductor field-effect transistors). Active matrix technology was first demonstrated as a feasible device using
thin-film transistor A thin-film transistor (TFT) is a special type of field-effect transistor (FET) where the transistor is thin relative to the plane of the device. TFTs are grown on a supporting (but non-conducting) substrate. A common substrate is glass, becaus ...
s (TFTs) by T. Peter Brody, Fang Chen Luo and their team at the Thin-Film Devices department of
Westinghouse Electric Corporation The Westinghouse Electric Corporation was an American manufacturing company founded in 1886 by George Westinghouse. It was originally named "Westinghouse Electric & Manufacturing Company" and was renamed "Westinghouse Electric Corporation" i ...
in 1974, and the term was introduced into the literature in 1975. Given an ''m'' × ''n'' matrix, the number of connectors needed to address the display is ''m'' + ''n'' (just like in passive matrix technology). Each pixel is attached to a switch-device, which ''actively'' maintains the pixel state while other pixels are being addressed, also preventing
crosstalk In electronics, crosstalk is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel. Crosstalk is usually caused by undesired capacitive, in ...
from inadvertently changing the state of an unaddressed pixel. The most common switching devices use TFTs, i.e. a FET based on either the cheaper non-crystalline
thin-film A thin film is a layer of material ranging from fractions of a nanometer ( monolayer) to several micrometers in thickness. The controlled synthesis of materials as thin films (a process referred to as deposition) is a fundamental step in many a ...
silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ...
( a-Si),
polycrystalline A crystallite is a small or even microscopic crystal which forms, for example, during the cooling of many materials. Crystallites are also referred to as grains. Bacillite is a type of crystallite. It is rodlike with parallel longulites. Stru ...
silicon ( poly-Si), or CdSe
semiconductor A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. ...
material. Another variant is to use diodes or resistors, but neither diodes (e.g. metal insulator metal diodes), nor non-linear voltage dependent
resistor A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias activ ...
s (i.e.
varistor A varistor is an electronic component with an electrical resistance that varies with the applied voltage. Also known as a voltage-dependent resistor (VDR), it has a nonlinear, non- ohmic current–voltage characteristic that is similar to that ...
s) are currently used with the latter not yet economical, compared to TFT. The
Macintosh Portable Macintosh Portable is a laptop designed, manufactured, and sold by Apple Computer, Inc. from September 1989 to October 1991. It is the first battery-powered Macintosh, which garnered significant excitement from critics, but sales to customers ...
(1989) was perhaps the first consumer laptop to employ an active matrix panel. Since the decline of
cathode ray tubes A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms (oscilloscope), p ...
as a consumer display technology, virtually all TVs, computer monitors and smartphone screens that use LCD or
OLED An organic light-emitting diode (OLED or organic LED), also known as organic electroluminescent (organic EL) diode, is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound that emits light ...
technology employ active matrix technology.


See also

*
AMLCD An active-matrix liquid-crystal display (AMLCD) is a type of flat-panel display, the only viable technology for high-resolution TVs, computer monitors, notebook computers, tablet computers and smartphones with an LCD screen, due to low weight ...
*
AMOLED AMOLED (active-matrix organic light-emitting diode, ) is a type of OLED display device technology. OLED describes a specific type of thin-film-display technology in which organic compounds form the electroluminescent material, and active matr ...
* QLED * TFT-LCD * Passive matrix addressing * Pixel geometry *
Comparison of display technology This is a comparison of various properties of different display technologies. General characteristics Major technologies are CRT, LCD and its derivatives (Quantum dot display, LED backlit LCD, WLCD, OLCD), Plasma, and OLED and its derivati ...


References

{{Reflist Display technology