Liquid crystal displays (LCDs) are available to display arbitrary images (as in a general-purpose computer display) or fixed images with low information content. Arbitrary images are made from a matrix of small pixels, while other displays have larger elements.

A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers to display information. Liquid crystals do not emit light directly, but instead use a backlight or reflector to produce images in color or monochrome.

Twisted nematic field effect

The twisted nematic effect (TN-effect) was a major technological breakthrough that made the manufacture of large, thin liquid crystal displays practical and cost competitive. By the 1990s, TN-effect LCDs were largely universal in portable electronics, although since then, many applications of LCDs adopted alternatives to the TN-effect such as in-plane switching (IPS) or vertical alignment (VA). Many monochrome alphanumerical displays without picture information still use TN LCDs.

TN displays benefit from fast response times and less smearing than other LC display technology, but suffer from poor color reproduction and limited viewing angles, especially in the vertical direction. Colors will shift, potentially to the point of completely inverting, when viewed at an angle that is not perpendicular to the display. Viewing the display from above whitens colors, and viewing the display from below dims colors.

Wikipedia says: “LCDs are used in a wide range of applications, including LCD televisions, computer monitors, instrument panels, aircraft cockpit displays, and indoor and outdoor signage. Small LCD screens are common in LCD projectors and portable consumer devices such as digital cameras, watches, calculators, and mobile telephones, including smartphones. LCD screens have replaced heavy, bulky and less energy-efficient cathode-ray tube (CRT) displays in nearly all applications.”