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DTV Television Learning Center
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By February 17, 2009, broadcasters will be required to convert all of their
programming to DTV and will no longer broadcast analog signals. As a result, to
receive TV programming, some consumers will need to make changes in some of the
equipment they currently use. Click here to Learn more about DTV
Use our AV Forum to talk about latest technologies. Click Here
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Liquid Crystal Display (LCDs) Projectors
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It
become popular over the past decade for small hand held TV sets and as the
displays on camcorders. At the other end of the display size, LCD based video
projectors have become increasingly popular. From the beginning Sharp has been a leading manufacturer of
such projectors. LCD projectors have improved with the current units having
improved resolution and producing a brighter picture as compared to older units.
LCD projectors offer the convenience of small size and light weight as compared
to CRT projectors. However the image quality has generally been mediocre in
comparison to a good CRT projector. LCD projectors' images have tended to appear
course with obvious visible pixels when displayed on a large screen. This is due
to the relatively small size of each pixel as compared to the relative large
black area surrounding each pixel.
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Liquid Crystal on Silicon (LCoS) Projectors
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In an improved LCD technology that offers improved images as compared to
conventional LCDs but at a somewhat higher price. LCoS displays typicall have a
smaller space between individual pixels resulting in less of a 'screen door'
effect in the displayed image. LCOS image quality, in terms their native
contrast ratio and its ability to display true blacks, falls short of the latest
generation of DLP projectors (i.e., those using the HD-2+ imaging chip) and far
short of the best CRT projectors. However Sony has introduced LCoS front and
rear projectors that incorporate an internal motorized iris that dynamically
varies the overall light output from the projector's lens and this does result
in a significant subjective improvement in the contrast ratio and black levels.
The LCoS imaging chips are very difficult to manufacture in mass production and
until the successful yield rate improves the prices for LCoS projectors will
remain high
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Drive Image Light Amplifier
(D-ILA) Projectors
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It
is an technology developed by Hughes and JVC. This is one variation of the LCoS
technology. All sales of D-ILA projectors are handled by commercial division of
JVC
and a few other companies licensed by JVC. D-ILA projectors use reflective LCDs
(on CMOS chips), rather than the transmissive LCD used on conventional LCD
projectors. The result is a technology similar to DLP in several ways. D-ILA
projector prices start at about $15,000 and go up from there. Currently higher
resolutions are available in D-ILA projectors than in DLP or conventional DLP
projectors. The overall quality of the project image with D-ILA is quite good
and very bright. The most expensive D-ILA projectors are suitable for use with
very large screens intended for use in commercial cinema's. Models intended for
home use offer display chips of up to 788 by 1400 pixels (model
DLA-HX1U - shown below) with a new 1080 x 1920 pixel HD-chip
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Digital Light Processor (DLP) Projectors
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It
was the second new consumer television display technology that appear in 1997.
The basic DLP module is being produced by Texas
Instruments (TI). DLP based projectors designed for displaying computer
graphics went on sale in 1997 by several companies, with products aimed at the
computer graphics presentation market. Currently DLP projectors with the
essential features for home theater use start with units producing a nominal 600
X 843 pixel image in a non-widescreen 3 x 4 aspect ratio. However, these entry
level units do have have adequate resolution for anything greater than standard
definition video. While some of these units can accept an HDTV input the image
is downscaled to standard definition for display. In the middle of the line up
of DLP models are projectors capable of 1024x768 pixels with a non-widescreen 3
x 4 aspect ratio. A 16 x 9 medium resolution version of DLP designed for home
theater use employs the "Matterhorn" DLP chipset with 1024 x 576 pixels.
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