LCD vs DLP projectors

If you've been thinking about buying a home theater projector, perhaps to connect
to an HDTV tuner, and have read
reviews or done a little bit of research, you'll be aware that there are two
technologies competing for the contents of your wallet.

Both LCD and DLP are used in projectors suitable for home theaters, but they work
in quite different ways and produce slightly different results. If you ask around '
particularly in electronics stores, you're likely to be provided with a mass of
information that's confusing and often just plain wrong. So here, in an effort to
clear the fog surrounding projectors, is our guide to LCD v DLP.

LCD

LCD projectors have three separate LCD panels, one for red, one for green, and one
for blue components of the image being processed by the projector. As light
passess through the LCD panels, individual pixels (or picture elements) can be
either opened or closed to either allow light to pass through or be filtered out. In
this way the light is modulated and an image projected on to the screen.

LCD projectors have historically had three main advantages over DLP. They produce
more accurate colors (due to the three separate LCD panels), they produce a slightly
sharper image (although this is as good as undetectable when watching movies) and
they are more light-efficient, which means they produce brighter images using less
power.

However, LCD projectors also have some disadvantages, although as the technology
improves these are becoming less and less relevant. The first of these is pixelation,
or what's known as the screen door effect. This means that sometimes you can see
the individual pixels and it looks as though you are viewing the image through a
'screendoor.' The second historic disadvantage of LCD v DLP is that LCD doesn't
produce absolute black, which means that contrast is less than you would get with
DLP.

However, the advent of higher resoltion LCD projectors (particularly 'HD-ready'
projectors which have a horizontal resolution of 768 pixels or greater) means that
pixelation is less of a problem than it used to be. And the improved ability of LCDs
to produce high-contrast images is also allowing them to be taken more seriously
by home theater enthusiasts.

DLP

Digital Light Processing (DLP) is a technology developed by Texas Instruments and it
works by projecting light from the projector's lamp onto a DLP chip, made up of
thousands of tiny mirrors. Each mirror represents a single pixel and directs the light
projected onto it either into the lens path to turn the pixel on or away from it to turn
it off. Most DLP projectors have only one chip, so in order to reproduce color, a
color wheel consisting of red, green, blue and sometimes, white filters is used. The
wheel spins between the lamp and the chip and changes the color of the light
hitting the chip from red, to green, blue. Each mirror on the DLP chip tilts towards
or away from the lens path depending on how much of a particular colour light is
required for that pixel at any given instant.

The key advantages DLP has in the LCD v DLP debate is that DLP projectors tend to
be smaller and lighter, have better contrast, and don't suffer the same pixelation
problems as LCD projectors. There is one problem that some users report with DLP
projectors, although it appears to only affect a very small number of people.
Because of the way DLP works, at any given instant, the image on screen is either
red, green, or blue. However, the images change so quickly, that the human eye
doesn't detect this and your brain puts the red, green and blue images together to
make a complete frame of video. Unfortunately, some people can see the individual
colours, and others can detect them enough to cause eye-strain and headaches.
However, technology has improved significantly with the introduction of six-color
wheels and faster rotation speeds. The rainbow effect should be a problem for even
fewer people. The best way to find out if you're affected is to try out a DLP
projector, perhaps by hiring one, before you buy.

Technology in both LCD and DLP projectors is improving all the time. However, at
the time of writing DLP still has a slight edge in the home theater market.

Kenny Hemphill is the editor and publisher of http://www.the-hdtv-tuner.com">The HDTV Tuner, a site which aims to cut through
the confusion surrounding HDTV and provide surfers with up to date, accurate and
easy to read information on HDTV.

Spam emails More free articles

Related articles