Chapter 16: Monitors and Displays^389
Vector graphic monitors are very expensive and are typically reserved for use on
engineering workstations and other high-end applications, such as GIS (geographic
information systems).Analog versus Digital CRTs
In contrast to the rest of the PC, the monitor has evolved from digital to analog, which
does seem to go against the grain a bit. PCs are digital devices and for a while monitors
were digital devices, too, but when the demand grew for more than 64 colors about the
time of the VGA standard, monitors became analog. Using an analog signal allows the
CRT to develop more shades of red, green, and blue.
Theoretically, an analog signal can represent an unlimited number of colors and
shades.However,standardanalogcolorislimitedto256colorvariationsofeachof65,536
colors (16-bit color), which means that over 16 million different colors are encoded in the
analog signal. Virtually all monitors in use today are analog monitors.Flat-Panel Displays
The technologies used in flat-panel displays are completely different from those used in
CRTs. For one thing, there is the obvious: a flat-panel display may be only 1 inch deep as
opposed to the CRT that may be as much as 18 inches deep. However, the primary difference
is in how the displayed image is formed on the screen.Liquid Crystal Display (LCD)
Liquid crystal displays (LCD) are used in many products, including wristwatches, micro-
wave ovens, CD players, and even PC monitor displays. In fact, virtually all PC flat-panel
monitors sold today have an LCD screen. LCD is popular because it is thinner, lighter,
and requires less power than other types of displays, especially the CRT.
LCD monitors are more expensive than CRT monitors simply because they cost more
to produce. To increase the size of a LCD screen, more transistors must be added. As the
number of transistors in a display increases, so does the potential for bad transistors.
Manufacturers reject as much as 40 percent of LCDs on the production line, which has a
direct impact on the retail price.Liquid Crystal
Although the name is seemingly an oxymoron, liquid crystal is a material that exists
somewhere between a solid and a liquid. Crystals are normally rock-hard, slightly
opaque solids, but liquid crystal is not really that kind of crystal. Liquid crystal is created
by applying heat to a suitable substance to change it from a solid into a liquid crystal
form. Not much more heat is needed to turn the liquid crystal into a complete liquid,
which is why liquid crystals are sensitive to temperature changes; this is what makes