OTHER TECH

How LCD Works RCA created the first experimental LCD in 1968, and in 1973 Sharp was the first company to sell a calculator with a liquid-crystal screen. An LCD contains rod-shaped molecules, initially all pointed the same way, that can change their orientation in response to small amounts of electricity.

There are basically two types of LCDs: reflective and transmissive. A simple reflective display consists of a layer of liquid crystals sandwiched between two transparent electrode layers, with the whole array contained between two pieces of polarized glass plus a mirrored back that reflects ambient light. When current runs through the electrodes, the liquid-crystal molecules change orientation ("untwist") and become dark, blocking light from passing through and producing, say, one of the hexagonal bars that make up digits on a calculator. Instead of having a mirrored back, transmissive flat-panel LCDs - including both TVs and computer monitors - contain a fluorescent backlight that shines through the panel so you can see the image onscreen even in the dark.

Early laptop-computer screens and portable TVs used a passive-matrix LCD design, but today most LCDs are active-matrix. Both types contain thousands or millions of tiny pixels, or picture elements, that together form an image. In a color LCD, each pixel actually consists of three subpixels - one each for red, green, and blue - that combine to create the spectrum of visible color.

In a passive LCD, the electrical charges travel down rows and columns of the display until they intersect at the designated subpixel and untwist it to the desired degree. But the current can also excite neighboring subpixels as it travels along the row or column, decreasing contrast and fuzzing the images.