Specifications

878
Chapter 15 Video Hardware
Figure 15.5 How a typical DLP projector works.
The earliest DLP projectors used a simple three-color (RGB) wheel, as shown in Figure 15.5. However,
more recent models have used a four-segment (RGB and clear) or a six-segment (RGBRGB) wheel to
improve picture quality.
Note
For more information about digital light processing, see the official Texas Instruments Web site about DLP technology at
http://www.dlp.com.
Plasma Displays
Plasma, the latest technology for large wide-screen displays, actually has a long history. In the late
1980s, IBM developed a monochrome plasma screen that displayed orange text and graphics on a
black background. Toshiba used this display in its T3100 and T3200 laptop computers, which featured
double-scan CGA/AT&T 6300-compatible 640×400 graphics.
Unlike the early IBM monochrome plasma screen, today’s plasma displays are RGB devices capable of
displaying 24-bit or 32-bit color, TV, or DVD signals. Plasma screens produce an image by using elec-
trically charged gas (plasma) to illuminate triads of red, green, and blue phosphors, as shown in
Figure 15.6.
The display and address electrodes create a grid that enables each subpixel to be individually
addressed. By adjusting the differences in charge between the display and address electrodes for each
triad’s subpixels, the signal source controls the picture.
Typical plasma screens range in size from 42'' to 50'' or larger. Because they are primarily designed
for use with DVD, TV, or HDTV video sources, their resolution is typically 852×480 with a 16:9
aspect ratio (some 50'' units have 1366×768 resolution WXGA resolution). Although 852×480 is too
low for mainstream computer applications, many displays can accept VGA and DVI inputs as well
as S-video or composite inputs, so they can be used with a PC for DVD or similar entertainment
applications.
Light source
Condensing lens
Color wheel
Shaping lens
DMD micromirror array
Processor
SRAM Memory
Projection lens
16 1738 ch15 7/30/04 10:31 AM Page 878