An active-matrix

liquid-crystal display A liquid-crystal display (LCD) is a 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 equipmen ...

(AMLCD) is a type of flat-panel display, the only viable technology for high-resolution TVs,

computer monitor A computer monitor is an output device that displays information in pictorial or textual form. A discrete monitor comprises a visual display, support electronics, power supply, housing, electrical connectors, and external user controls. The di ...

s, notebook computers,

tablet computer A tablet computer, commonly shortened to tablet, is a mobile device, typically with a mobile operating system and touchscreen display processing circuitry, and a rechargeable battery in a single, thin and flat package. Tablets, being comput ...

s and

smartphone A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, whic ...

s with an LCD screen, due to low weight, very good image quality, wide color

gamut In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain ''complete subset'' of colors. The most common usage refers to the subset of colors which can be accurately represented in a given circ ...

and response time. The concept of active-matrix LCDs was proposed 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 the RCA Laboratories in 1968. The first functional AMLCD with thin-film transistors was made by

T. Peter Brody T. P. "Peter" Brody (18 April 1920 Budapest, Hungary – 18 September 2011 Pittsburgh, Pennsylvania, United States) was a British-naturalised physicist and the co-inventor of Active Matrix Thin-Film Transistor display technology together with F ...

, Fang-Chen Luo and their team at

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" in ...

in 1972. However, it took years of additional research and development by others to launch successful products.

Introduction

The most common type of AMLCD contains, besides the polarizing sheets and cells of liquid crystal, a matrix of thin-film transistors to make a

thin-film-transistor liquid-crystal display A thin-film-transistor liquid-crystal display (TFT LCD) is a variant of a liquid-crystal display that uses thin-film-transistor technology to improve image qualities such as addressability and contrast. A TFT LCD is an active matrix LCD, in cont ...

. These devices store the electrical state of each

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 smal ...

on the display while all the other pixels are being updated. This method provides a much brighter, sharper display than a

passive matrix Passive matrix addressing is an addressing scheme used in early LCDs. This is a matrix addressing scheme meaning that only ''m'' + ''n'' control signals are required to address an ''m'' × ''n'' display. A pixel in a passi ...

of the same size. An important specification for these displays is their viewing-angle. Thin-film transistors are usually used for constructing an active matrix so that the two terms are often interchanged, even though a thin-film transistor is just one component in an active matrix and some active-matrix designs have used other components such as

diode A diode is a two-terminal electronic component that conducts current primarily in one direction (asymmetric conductance); it has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other. A diode ...

s. Whereas a passive matrix display uses a simple conductive grid to apply a voltage to the liquid crystals in the target area, an active-matrix display uses a grid of transistors and capacitors with the ability to hold a charge for a limited period of time. Because of the switching action of transistors, only the desired pixel receives a charge, and the pixel acts as a capacitor to hold the charge until the next refresh cycle, improving image quality over a passive matrix. This is a special version of a sample-and-hold circuit.

References

{{reflist

External links

Eduard Rhein Stiftung 1988 Technology Award Dr. T. Peter Brody: Basic development of TFT liquid crystal display
Liquid crystal displays

Introduction

See also

References

External links