EL and gas-plasma technology are more expensive and thus are not used as often as LCD technology.

Flat-Panel Displays: If CRTs were the only existing technology for computer screens, we would still be carrying around 25-pound “luggables” instead of lightweight notebooks, subnotebooks, and pocket PCs. CRTs provide bright, clear images but they consume space, weight, and power. Compared to CRTs, flat-panel displays are much thinner, weigh less and displays are made up of two plates of glass with a substance in between then, which is activated in different ways.
 

Flat-panel displays: Flat-panel displays are distinguished in two ways: (1) by the substance between the plates of glass and (2) by the arrangement of the transistors in the screens.

Flat-panel displays


Substances between plates- LCD, EL, or gas plasma: There are three types of technology used in flat-panel display screens: liquid-crystal display, electroluminescent display, and gas-plasma display.
LCD, EL, or gas plasma


Liquid-crystal display: Liquid-crystal display (LCD) consists of a substance called liquid crystal, the molecules which line up in a way that alters their optical properties. So, light- usually backlighting behind the screen is blocked or allowed through to create an image.
Liquid-crystal display


Electroluminescent display: Electroluminescent (EL) display contains a substance that glows when it is charged by an electric current. A pixel is formed on the screen when current is sent to the intersection of the appropriate row and column. The combined voltages from the row and column cause the screen to glow at that point.

Electroluminescent display


Gas plasma display is like a neon bulb which the display uses a gas that emits light in the presence of an electric current. That is, the technology uses predominantly neon gas and electrodes above and below the gas, when electric current passes between the electrodes, the gas flows. At present, EL and gas-plasma technology are more expensive and thus are not used as often as LCD technology.
 
Arrangement of transistors- active-matrix or passive-matrix: Flat-panel screens are either active-matrix screens are much brighter and sharper than passive-matrix screens are much brighter and sharper than passive-matrix screens, but they are more complicated and thus more expensive. In a passive-matrix display, a transistor controls a whole row or column of pixels. The advantage is that passive-matrix displays are less expensive and use less power than active-matrix displays.

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