CRT replacement
When thinking of upgrading a video system or just replacing a worn-out
one, there's a lot to be learned about new technology and what is currently
available for purchase. Why change viewing from traditional cathode ray
tubes (CRTs) when, to date, they provide the best images (Sound and
Vision magazine)?
CRT alternatives are becoming popular because thin is in. CRTs large
enough for a home theater are heavy and require a large space. Many
consumers are opting for the new thin video displays, but the decision
to go thin is not that simple. Many thin alternatives are on the market.
These thin, new technology choices include plasma, digital light procesing
(DLP), liquid-crystal display (LCD), and liquid-crystal on silicon (LCoS).
Each of these technologies is featured in a separate article in this
newsletter.
What's HDTV?
Any discussion of next generation video displays should explain how
high-definition TV (HDTV) fits into the picture. Gary Brown, author
of "How HDTV Works," describes it as high-resolution digital
television (DTV) combined with the Dolby Digital surround sound (AC-3).
For an explanation of resolutions used in video formats, see the
article "Resolution". "HDTV is the highest DTV resolution
in the new set of standards," (electronics.howstuffworks.com). Knowing
about HDTV is important when faced with purchasing a video display and deciding
what types of jacks are need on the back of it. These jacks are different
from the component-video, S-video, and RGB jacks used on analog displays
because they are connecting high-definition tuners, cable boxes, and satellite
receivers.
RGB connectors have been used for computer imaging with dense pixel counts that
need more than NTSC requirements. The jacks provide for horizontal and vertical
synchronization, as well as red, green, and blue signals. These wires are contained
in a single cable.
Component video uses the three RCA-type connectors on the back of the display. The
red, green, and blue make up the components. Movie studios expressed concern for
sending and displaying digital movies because it would allow piracy in a high resolution
format. Digital visual interface (DVI) has been enhanced to provide copy-protection
(Sound and Vision magazine).
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Flat-panel video displays are thin, allowing versatile placement (Sound
and Vision magazine, photo by Tony Cordosa).
Interlace or progressive
Since the phosphors used to display shades in first-generation televisions
responded slowly, generating an entire video picture created a flicker that
moved down the screen (www.divx.com). To correct this undesirable strobe
effect, the analog television was displayed in two passes (fields), with
odd numbered lines in the first field and then the even lines projected
between them in the second pass to create a full frame.
This is called interlaced scanning. It gives the
phosphors time to recover between the two fast scans.
Thirty overall images or frames per second (30 FPS) can be
displayed with interlaced scanning. Thirty frames per second is the requirement
for full motion video.
Digital displays use progressive scanning. The lines are
displayed sequentially so the frame appears all at the same time. This
allows the display of 60 FPS to create an exceptionally sharp picture.
Find additional information on Connectors, click here.
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These photos illustrate video image interlacing. The first image is a photo
with only one pass of a frame (called a field). When the second pass is made
the picture appears to be complete (images from www.divx.com).
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Editorial
"Just because we can, should we?" attributed to Everett M. Rogers,
is a valid question for converting to flat panel displays.
They have memorable increased quality and, as mandated by the government,
are compatible with current analog systems while being targeted for digital
images. Research companies will assure that application of their innovations
is easy to use or risk their own demise.
Yes, the costs are high for the new products, as expected by early adopters.
As with many new inventions, emphasis is placed on making the technology work,
then on making it cost efficient for the early and late majorities.
There is a point of no return to the past once a consumer accepts and expects
the quality and convenience of a thin video display. It's not because they can't
return to the past. They can return, at least for a while. But, just because
they can go back, should they? Without acceptance and adoption of new technology,
there is no progress to build more new technology.
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