Editing Active-matrix liquid-crystal display (section)

{{refimprove|date=July 2007}}

An '''active-matrix liquid-crystal display''' ('''AMLCD''') is an extremely common type of [[Liquid-crystal_display#Active-matrix_technologies|liquid-crystal display]] ('''LCD'''). Having supplanted [[Liquid-crystal_display#Passive-matrix|passive-matrix LCDs]] in general use, in common vernacular, an active-matrix LCD is also simply referred to as a '''LCD'''. As of 2025, the term "AMLCD" is uncommon as a matter of [[Jargon|technical jargon]]; instead, due to their ubiquity, different ''types'' of active-matrix liquid crystal displays are usually specified — [[TFT LCD]], [[IPS LCD]], [[MicroLED]], and [[Quantum_dot_display|QLED]] are but just a few examples.

Various types of AMLCDs are used as [[Flat-panel_display|flat-panel displays]] in many different applications, including [[television]]s, [[computer monitor]]s, [[In-car_entertainment|in-vehicle infotainment system]]s, [[Notebook_(laptop)|notebook computer]]s, [[tablet computer]]s and [[smartphone]]s. AMLCDs are a relatively [[mature technology]], and desirable in the above applications due in part to their low weight, flexibility, thinness, [[luminous efficacy]], [[pixel density]], image quality, range of possible color [[gamut]]s, and quick [[Response_time_(technology)#Display_technologies|response time]]s.

In comparison to other contemporaneous display technologies, most AMLCD technologies struggle with contrast. Because an AMLCD requires a [[backlight]], one typically cannot display [[Black#Physics|true black]] — instead, dark gray is shown.

{{Further|Comparison of CRT, LCD, Plasma, and OLED}}

Among other reasons, due to their smaller size, lower power consumption, lower toxicity, and higher overall brightness, AMLCDs produced since the late 2000s use [[Light-emitting_diode|LED]] backlights instead of [[CCFL]]s.

The utilization of LED backlighting enables some AMLCDs (mostly televisions) to employ methods like [[Backlight#Backlight_dimming|localized dimming]] to increase their perceived [[contrast ratio]]. When the display's controller detects darkness in the frame or [[Group_of_pictures|GOP]] being displayed, groups of LEDs comprising the display's backlight are dimmed at the corresponding physical location (the number of localized dimming zones the display provides is typically in the hundreds but varies heavily, typically increasing proportionally to the display's [[MSRP]]). Unfortunately, it is not uncommon for localized dimming to cause portions of the image (for example, subtitles during a dark scene) to be incorrectly and undesirably dimmed to a level where the image is not clearly visible. Displays where localized dimming cannot be disabled are therefore unsuitable for applications like [[non-linear editing]] or [[color grading]], where [[Color_calibration#Display|color accuracy]] and [[Gamma_correction#Standard_gammas|correct gamma]] are required.

The issue is very well-known, having plagued AMLCDs for decades. Amongst other technologies, it contributed to the development of [[MicroLED]] displays, a type of AMLCD. A MicroLED display uses one LED per pixel as its backlight, so a MicroLED display is capable of displaying black by simply turning the relevant LED off — rendering the corresponding pixel completely dark. However, as of February 2025, MicroLED displays have not been widely adopted and are considerably more expensive than other AMLCD displays.

The concept of [[active-matrix]] LCDs was proposed by [[Bernard J. Lechner]] at the [[RCA Laboratories]] in 1968.<ref>{{Cite web |url=http://www.ieee.org/about/news/2011/honors_ceremony/releases_nishizawa.html |title=IEEE Jun-ichi Nishizawa Medal |website=[[Institute of Electrical and Electronics Engineers]] (IEEE) |access-date=2013-11-01 |archive-url=https://web.archive.org/web/20130912052239/http://www.ieee.org/about/news/2011/honors_ceremony/releases_nishizawa.html |archive-date=2013-09-12 |url-status=dead }}</ref> The first functional AMLCD with [[thin-film transistor]]s was made by [[T. Peter Brody]], Fang-Chen Luo and their team at [[Westinghouse Electric Corporation]] in 1972.<ref>{{Cite journal|date=1972-10-10|title=Liquid crystal image display panel with integrated addressing circuitry|url=https://patents.google.com/patent/US3840695A/en |website=Google Patents}}</ref><ref>{{Cite journal | doi = 10.1109/T-ED.1975.18214 | last1 = Brody | first1 = T. P. | last2 = Fang Chen Luo | last3 = Szepesi | first3 = Z. P. | last4 = Davies | first4 = D. H. | title = A 6 x 6-in 20-lpi electroluminescent display panel | journal = IEEE Transactions on Electron Devices | volume = 22 | issue = 9 | pages = 739 | year = 1975| s2cid = 1378753 }}</ref> However, it took years of additional research and development by others to launch successful products.