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Projector Torture Test: LCD versus DLP
An anonymous reader writes "A ten month torture test of five LCD and two DLP projectors shows LCD images deteriorate during extended use." Not surprisingly, if you run an LCD projector for 4000 hours, it deteriorates... of course, if you're staring at a projecter 8 hours a day, for 500 straight days, maybe you should go outside ;)
And, they are right.
The lamps degrade over time, as well as the panels.
I see so many projectors fail due to non-cleaning.
panel overheats are an issue... because no end user really owns a projector, they usually use one at work and none of these people bother to clean the units filter.
This just adds to the speed of the failure. most projectors I see have failures of the lamp and ballast units before the panels, probably because I get these downed projectors, find them filthy, clean and repair them before it kills the panels.
I have seen many, many kinds of projectors in both LCD and DLP, and the ones that seem to last longer are DLP units.
LCD units start biting the bullet after 3-4 years and usually after 2 years the image quality is starting to degrade.
My recommendation to anyone that has ant of these projectors is to clean them regularly, allow them to cool properly (another BIG problem) and, replace the lamp after the recommended usage.
some are 3,000 hours... some are 2,000...
If you do not replace the lamp after the usage limit, you risk an exploding lamp, damaged ballast, or main power supply. if its a DLP unit the color wheel can be shattered by an exploding lamp. I have had to replace quite a few of these because of this.
The projectors I find that fail the LEAST are made by Sharp and Toshiba. these are well made units that have lifespans of 10 years or more.
I see 10 year old sharps all the time. altho, the panels are about wasted.
Remember, keep the filters clean, allow the units to cool properly and change the lamps when recommended, and your unit should function for many years before needing service.
I hope that someone finds this infoarmation informative and useful.
The short answer is that there's a small panel (DMD, digital mirrored device) with one tiny mirror per pixel (aka, over a million). Each mirror is individually motorized and flutters back and forth. One position reflects the light from the bulb down through the optics and to the screen. In the other position, it reflects the light into what's basically a light absorber.
Total light output is modlated by how much time the mirror is in the on position. The can each litterally flutter on and off over a thousand times a second. On dark areas of dark scenes you can see little scintelations of when individual mirrors flutter to the on position for a fraction of a second.
The fancier projetors have a light beam that's broken into red blue and green which then bounces off of three DMD panels before being recombined. The cheapie (less than $15K) ones have just one light beam that passes through a color wheel.
The color wheels typically have either RGB, RGBW (white), or RGBRGB. Better projectors have the RGBRGB wheels and spin at a higher rate. The result is that the projector winds up displaying a red image, a blue image and a green image in sequence. On fast moving items certain people (like me) are suscepible to seeing the different colors individually unless they spring for a higher speed color wheel, a triple DMD projector, or some other technology like LCD.
One last tidbit on the color wheel is that there is a new scroll color wheel coming out where at any given time there is a red, blue and green section being displayed over one third of the screen. They look like a pinwheel or one of those swirly lollypops. The trick to them is that the colors are actually dichoric mirrors so that only one given color light passes through while the other colors are then reflected back and hopefully recycled through one of the other two colors. It should more than total brighness while also lessening the effect of a slower speed colorwheel. Should be interresting.