active matrix LCD

Type of colour liquid crystal display (LCD) commonly used in laptop computers. Active matrix displays are made by sandwiching a film containing tiny transistors between two plates of glass. They achieve high contrast and brightness by applying voltage across the horizontal and vertical wires between the two glass plates, balanced by using a small transistor inside each pixel to amplify the voltage when so instructed.

To create VGA colour, each pixel must also integrate colour filters; essentially, each logical pixel is made up of three physical pixels, one for each of red, blue, and green, the primary colours of light. The consequence of this – and the reason active matrix screens are such expensive options – is that a VGA display requires approximately a billion transistors, and even minute imperfections render the screens useless for computing purposes. A high refresh rate means that the screens are extremely responsive, so the cursor does not disappear as a mouse is moved quickly across the screen.

Active matrix displays began to appear on laptops in 1992, and are expected by many eventually to replace the older cathode-ray technology for television sets as well as display monitors.