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LCD CTR:
LCD projector systems have a couple of big advantages, when compared with
CRT projectors:
Lower-cost front projectors: Although CRT front projectors can cost an
arm and three legs, you can buy a quality LCD front projector for less
than $2,000.
More-compact RPTVs: Because the LCD panels and the lamp are small,
LCD RPTVs can be much thinner than CRT RPTVs. Although many CRT
systems can be 3 or more feet deep, LCD systems can be less than 15
inches deep. That helps a lot both in small rooms and with the SAF
(spousal acceptance factor).
210 Part III:Watching and Listening: Display and Control Devices
Brighter than CRT: The separate lamp used in CRT projectors puts out a
ton of light. (You wouldn’t want to have someone shine one in your eyes
close up!) The result is a brighter picture that can tolerate more ambient
light in your home theater.
For the best brightness and color reproduction, look for LCD projectors
(typically only RPTVs) that use LED backlights instead of traditional
bulbs.
Don’t need to be converged: Despite the fact that an LCD projector contains
three LCD panels, it has only one light source. So you don’t need to
converge the picture like you do with a CRT projector. This makes the
setup much easier for mere mortals.
Burn-in isn’t a big issue: Plug in that Xbox or PlayStation and play all the
games you want. Because LCD systems don’t use phosphors, they can’t
get permanent burn-in like CRTs (or flat-panel plasma systems) can.
Of course, there’s got to be a downside, right? LCD projectors don’t do a
couple of things well:
Relatively poor black performance: LCD projectors, like LCD directview
sets, can’t display true black tints well. Dark scenes end up being
gray instead. So when the Orcs are sneaking up on Frodo from the
mouth of that dark cave, you can’t see them all that well.
Limited resolution: Today’s LCD panels can reach HDTV resolutions (at
least 720p resolutions), but most can’t display the full resolution of 1080i
content. To do so, the LCD panels need a resolution of 1920 x 1080, and
none we know of are there yet.
The lamp will wear out: Nothing lasts forever, and the high-output
lamps on LCD projectors tend to wear out after a few thousand hours of
use. That lifespan is a lot less than the one for tubes on a CRT, but LCD
projector lamps cost a lot less to replace (hundreds instead of thousands
of dollars).
The “stuck pixel” problem: If you own a laptop computer (or a desktop
computer with an LCD display), you may be familiar with the issue of
stuck pixels. These are usually minor manufacturing defects that cause
individual pixels to not light up when the display tells them to. Because
the relative size of pixels in a projection system is large, you may notice
a dead pixel on your screen (and be very annoyed by it). Many manufacturers
think that having a few stuck pixels is just part of doing business,
and they will not replace your LCD panels except in extreme cases. As a
result, it is a good idea to find out the manufacturer’s “dead pixel policy”
before you buy.
The “screen door”: When LCD images are projected onto big screens (like
the ones you find in a front-projector system), you can begin to see the
pixel structure of the LCD itself. By this we mean the physical structure of
the LCD that separates the individual pixels. Because of the way LCDs are
constructed, you can look closely at a large projected image and see dots
of lighter and darker areas — like you’re looking at the world through a
metal screen door. We should emphasize that this isn’t a huge issue. This
“screen door” effect is sort of like the scan lines on a CRT system in that
you really notice it only if you’re too close to a big image.
For more information on LCD projection displays, a listing of current models,
and more good old-fashioned marketing talk than you can shake a stick
at, check out 3LCD.
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