Specifications

Video Display Technologies
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your LCD monitor for group presentations. To improve the horizontal viewing area, several ven-
dors have developed patented improvements to the basic TFT display, such as Hitachi’s in-plane
switching (IPS), Fujitsu’s multidomain vertical adjustment (MVA), and Mitsubishi’s FFD—all of
which have been licensed to other leading LCD makers.
■ A high-contrast ratio (luminance difference between white and black) makes for sharper text and vivid
colors. A typical CRT has a contrast ratio of about 245:1. Although LCD panels in the May 23,
2000 PC Magazine test had contrast ratios ranging from a low of 186:1 to a high of 370:1, newer
LCD panels have even higher contrast ratios (up to 400:1). Panels could be viewed at an average
horizontal angle of as much as 129° without loss of contrast.
■ Features such as integrated speakers and Universal Serial Bus (USB) hubs are pleasant additions, but
your eyes should make the final decision about which panel is best for you. Because reviews of LCD
panels often don’t provide detailed analysis of horizontal and vertical viewing angles and con-
trast ratios, check display units in stores yourself. Be sure to view the displays from several
angles. If you’re adding the panel as a second display, be sure to check its off-axis image quality.
■ Look for pivoting displays that enable you to rotate the display to match an upright page layout if you
use your computer for text-editing or page layout. This feature is supported by many LCD panels—
particularly those that are 17'' or larger—but the display performance in portrait mode is usually
lower than in normal landscape mode, especially for rapid motion. If possible, test the display
in portrait mode if you plan to use this mode frequently.
LCD and DLP Projectors
Originally, data projectors were intended for use in boardrooms and training facilities. However, with
the rise of home theater systems, the increasing popularity of working from home, and major price
reductions and improvements in projector technology, portable projectors are an increasingly popular
alternative to large-screen TVs and plasma displays. They can be used with Windows XP Media Center
PCs and video players as well as their traditional partners, conventional laptop and desktop computers.
Two technologies are used in the construction of data projectors:
■ Liquid crystal display (LCD)
■ Digital light processing (DLP)
Instead of using triads of subpixels as in a flat-panel or portable LCD, an LCD projector works by sep-
arating white light into red, green, and blue wavelengths and directing each wavelength through a
corresponding LCD panel. Each LCD panel’s pixels are opened or closed according to the signals
received from the signal source (computer, DVD, or video player) and are combined into a single RGB
image that is projected onto the screen.
LCD projectors are relatively low in cost (some 800×600 SVGA models are available for under $1,000)
but require some cool-down time before they can be stored.
The other major technology for presentation and home theater projectors uses Texas Instruments’
own digital light processing (DLP) technology. DLP projectors use a combination of a rapidly spinning
color wheel and a microprocessor-controlled array of tiny mirrors known as a digital micromirror device
(DMD). Each mirror in a DMD corresponds to a pixel, and the mirrors reflect light toward or away
from the projector optics. Depending on how frequently the mirrors are switched on, the image varies
from white (always on) to black (never on) through as many as 1,024 gray shades. The color wheel
provides color data to complete the projected image. Compared to LCD projectors, DLP projectors are
more compact, are lighter, and cool down more quickly after use; however, they are more expensive.
Figure 15.5 illustrates how a DLP-based processor produces the image.
Chapter 15
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