LCD

Liquid Crystal Display is a display technology that relies on polarising filters and liquid crystal cells rather than phosphors illuminated by electron beams to produce an on-screen image (CRT). LCD displays utilize two sheets of polarizing material with a liquid crystal solution between them. An electric current passed through the liquid causes the crystals to align so that light cannot pass through them. Each crystal, therefore, is like a shutter, either allowing light to pass through or blocking the light.

CSTN

Short for color super-twist nematic, an LCD technology developed by Sharp Electronics Corporation. Unlike TFT, CSTN is based on a passive matrix, which is less expensive to produce. The original CSTN displays developed in the early 90's suffered from slow response times and ghosting. Recent advances in the technology, however, have made CSTN a viable alternative to active-matrix displays. New CSTN displays offer 100ms response times, a 140 degree viewing angle, and high-quality color rivaling TFT displays - all at about half the cost.

This passive matrix display is a common type of flat-panel display consisting of a grid of horizontal and vertical wires. At the intersection of each grid is an LCD element which constitutes a single pixel, either letting light through or blocking it. A higher quality and more expensive type of display, called an active-matrix display, uses at least one transistor to control each pixel.

Double-layer SuperTwist Nematic is a passive-matrix LCD technology that uses two display layers to counteract the colour shifting that occurs with conventional supertwist displays. Also referred to as dual-scan. In the mid-90s, it appeared that passive-matrix displays would eventually become extinct due to the higher quality of active-matrix displays. However, the high cost of producing active-matrix displays, and new technologies such as DSTN, CSTN and HPA that improve passive-matrix displays, have cause passive-matrix displays to make a surprising comeback.

TFT

Abbreviation of thin film transistor, a type of LCD flat-panel display screen, in which each pixel is controlled by from one to four transistors. The TFT technology provides the best resolution of all the flat-panel techniques, but it is also the most expensive. TFT screens are sometimes called active-matrix LCDs. This is a type of flat-panel display in which the screen is refreshed more frequently than in conventional passive-matrix displays.

HPA

A newer passive-matrix technology called High-Performance Addressing (HPA) offers even better response times and contrast than CSTN. Short for High-Performance Addressing, an passive-matrix display technology the provides better response rates and contrast than conventional LCD displays. Although HPA displays aren't quite as crisp or fast as active-matrix (TFT) displays, they're considerably less expensive to produce. Consequently, HPA is being used by a number of computer manufacturers for their low-end notebook computers.

RESOLUTIONS :

SVGA ( super video graphics array ) - 800 X 600
XGA ( extended graphics array ) - 1024 X 768
SXGA ( super extended graphics array ) - 1280 X 1024

XGA was designed to replace the older video standard. It provides the same resolutions (640 by 480 or 1024 by 768 pixels), but supports more simultaneous colors (65 thousand compared to the older 256 colors). In addition, XGA allows monitors to be non-interlaced. SXGA ups the resolution - see above.

Top of page

PC TECHNICAL HOME PAGE