Glossary definition of LCD

Also known as: Liquid Crystal Display

Liquid Crystal Display (LCD) is a type of technology used to produce flat-panel display screens. LCDs are often used to make simple alphanumeric displays, in which several segments can be switched on or off ' such displays are found in many clocks and calculators. The LCD display can also be arranged as a grid of dots (pixels) to reproduce images on the screen, and such displays are particularly useful in battery-powered equipment, such as mobile phones and notebook computers, because they are thin, lightweight and low in power consumption. LCDs are available in monochrome or colour versions.

The LCD is constructed from a liquid crystal material sandwiched between two thin layers of glass. Passing an electric current through a particular pixel or segment of the display causes the crystals to realign, and depending on the design this results in the screen becoming either opaque or transparent to light. An LCD does not produce any light itself, but must be viewed using the light reflected from its surface (e.g. dark segments against a light background), or it may have a backlight and be viewed by means of the light transmitted through it.

An LCD is made in two versions, with either a passive matrix or an active matrix display grid, depending on how the luminance of each pixel is to be controlled. The active matrix LCD-also known as a thin film transistor (TFT) display-is the superior technology, with a transistor controlling each pixel. An active matrix LCD can respond more quickly than a passive matrix LCD to changes in the image on the screen, i.e. it has a faster refresh time, because the transistors can switch the pixels more rapidly than the passive version.

Phones tagged with LCD