Which type of digital projector gives a more accurate all around image for NTSC, DVD, 1024x768? The old three gun CRT projectors still look pretty good, but LCD seems to be eclipsing. Is there a reason for this? And WTF is DLP? Will the projector I buy this year be obsolete by next year or is that curve leveling off? Thanks for your consideration.
In a cost-no-object comparison, CRT still wins in the quality area. Unfortunately, it has several disadvantages, which is why other projector technologies are around:
- Cost. A good quality CRT projector that can handle a true HDTV signal can cost over $25k.
- Complexity. CRT projectors need to be converged, not only on setup, but also as the tubes age. While this is a lot easier to do than it was 10 years ago when all controls were analog, it’s still beyond the capabilites of most people.
- Portability. A CRT projector needs to be permanently installed. It’s not the thing you’d tote around for business presentations.
- Size. CRT projectors are significantly larger than their competition.
- Brightness. These days LCD and DLP projectors are brighter than their CRT counterparts. Ideally you need a perfectly dark room to view the output of a CRT projector.
LCD’s main disadvantage is what some people refer to as the “screen door effect”. Basically, since there are spaces between each LCD pixel, those spaces project through as a grid visible on the screen. As LCD technology improves the grid becomes thinner and less noticeable.
DLP, Digital Light Processor, is a technology developed by Texas Instruments, that is essentially a memory chip with micro-mirrors on top; each mirror corresponds to one memory location on the chip. The mirror can tilt depending on whether there is a 1 or 0 in the corresponding location; tilting one way it would reflect light onto the screen; tilting the other way it would reflect it away. One, two or three chip configurations are available; a 3 chip configuration uses one chip each for red, green & blue; one and two chip setups use a rotating color wheel. To get shades of colors the mirrors are rapidly tilted back and forth. Since the mirrors can be placed closer to each other than LCD pixels (at least at present), the grid is less noticeable than with LCD. Also, DLP is supposed to be brighter than LCD. And if it means anything to you, I believe that DLP is the techology of choice for digital movie theater projection.
There’s another relatively new technology called D-ILA (Digital Image Light Amplifier) which I believe is basically a reflective LCD. JVC is the proponent of this technology; I don’t know much about it yet. However, they seem to be gaining popularity with the high-end home theater crowd that doesn’t want go the CRT route.
Other disadvantages with both DLP and LCD are bulb life and cost; bulbs typically last 1000-2000 hours and can cost several hundred dollars each. D-ILA bulbs cost about $800 each for about the same life. CRT tubes have a “half-life” at about 6000 hours; this means that at 6000 hours of use they will have half their “new” brightness. This doesn’t make them unuseable, but the projector would need to be readjusted. The brigher you make the picture on a CRT projector, the shorter the tube life. You can probably get about 10,000 hours on a CRT projector before the tubes would need to be replaced. Tube replacement is a complicated procedure and costs a significant percentage (more than 50%) of the purchase price of the projector.
There are places on the web that sell used CRT projectors for very reasonable prices; sometimes these have even been refurbished with new tubes.
If you’re seriously considering purchasing a video projector, I highly recommend checking out the AV Science forums at http://www.avsforum.com
Excellent answer frogstein.
As an aside wasn’t the JVC technology and the Texas Instrument technology showcased when Star Wars: The Phantom Menace came out? I seem to remember that two theaters (one for each technology) got George Lucas to make a special digital ‘print’ of the film to show the movies with this technology instead of the usual film.
IIRC the reviews were pretty bad. Neither technology seemed to be up to spec to beat out film for quality but someday it might. If it does the huge cost of making multiple prints of films can be done away with and theaters could download a movie or get them on much cheaper DVD data discs.
Just curious if this is the same stuff you were talking about.
Sorry for the hijack…