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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 ;)
I go outside plenty. Just because a projector is run 8 hours a day doesn't mean I don't. The pool hall I hang out at has gone through dozens of projectors in the couple years I've been going there. It doesn't take long before a new one starts looking like crap.
Here's one. Hardly technical (the site is a high level type site) but very interesting.
8 hours a day for 500 days is about equal to 15 hours a day for 10 months (approximately 300 days).
If you stare at a CRT for that long, the radiation will most likely cause an inoperable brain tumor...
Only if it's a color CRT (which, even with modern designs, generates a non-trivial amount of soft X-rays due to the electrons slamming into the shadow-mask).
Black-and-white monitors make much less X-rays, due to the lower accelleration voltage, lower beam current (i.e. fewer electrons) and lighter target. Meanwhile, the charge on the screen tends to suck the dust out of the air in front of the user's face. There is still some X-ray from the screen. But some studies have estimated that the reduction in risk of lung cancer from radioactive and/or chemically-reactive particles of inhaled dust more than compensates for any increase in risk from the small amount of X-rays from a B&W CRT.
Of course who uses a monochrome monitor these days?
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Does anyone have a page that lists the technical details of how DLP works? The picture of the slide wasn't very technically detailed. I'd like to see how these work.
There's a fair amount of info on DLP at dlp.com. They have a rather high level "Technical overview", but if you look in the right place, you can also find a small White Paper Library, which has a number of papers that are fairly technically detailed but (IMO) still quite understandable.
All the digital movie theaters I've ever been to use DLP technology and not LCD. That was the point of the study to prove that DLP would hold up better than LCD.
Jack Valenti and Orrin Hatch will be first up against the wall when the revolution comes.
Uh, so buy a DLP. That's the only device that'd be worth a damn on a big screen like that anyhow.
I wouldn't go near an LCD now that DLPs are available. Reflective rather than transmissive==good thing.
Why yes, I AM a rocket scientist!
Bulbs last around 2000 hours. In a way they are similar to inkjet printers because they have a "REPLACE BULB" feature built in to the projector.
After 2000 hours your projector tells you to replace the bulb, you can still use it, but run the theoretical risk of damaging the projector when the bulb blows.
Bulbs in the UK cost £2-300 approx to replace, which is one years use at 8 hours a day 5 days a week.
So while they are a cool toy, you could buy 2 CRTs or one large LCD a year, or a wide screen TV every couple of years for the cost of one bulb.
Plasma screens are interesting, but in my experience you need graphics cards with plasma screen modes otherwise they are unviewable other than in 800x600 large icon and super large text mode.
It has become appallingly obvious that our technology has exceeded our humanity. --Albert Einstein
Your impression is odd, I've never seen burn-in on any LCD type of display.
DLP usually has as good or better fill ratio than LCD, where the average DLP is about 85% fill ratio, LCD is typically around 60%. Go ask AVS Forum. If you see bigger "screen door" on a DLP, check to make sure that you are comparing the same resolution on the same projected area. When people complain about screen door, it is usually from the LCD crowd.
Now, DLPs do have a "rainbow" effect because all units below $10,000 new are single-chip and operate under the principle of flashing an entire screen full of one color before flashing the next screen full of the next color. In short, it is a very, very fast RGB strobe sequence that has no equivalent that I know of in any other display technology. DLPs also have some sort of flutter noise because the micromirrors flash on and off sequences to imitate brightnesses in between. But the thing is, not very many people really notice or complain about either problem.
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.
I hate to moan[0], but this is _really_ not news!
My flatmate got a DLP projector on eBay.
Before he bought it he did a little research on it, and I did too. We both came to the same conclusion - DLP is better than LCD.
If you look this up on Google I expect you'll find what we did - every retailer I checked said DLP was better (and that what small shortcomings it does have in comparison to LCD are being rapildy overcome with some new 'magical' rev 2 chipset[1] which seems to eliminate them).
I think that even after 5 min research on the web (or by asking your retailer) you'd know the answer to this question - and that all retailers and projectionists seem to be largely in complete agreement - so I don't think this article is newsworthy.
[0] That's a lie - I like to moan.
[1] The name of it escapes me.
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.
Oh, and the LCD and DLP projectors both use the same type of lamps, with the same lifespans and problems.
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Dude, totally different. The chroma bug is an artifact of the fact that colors on a DVD are actually at a different resolution than luminence (black and white) data. Most new DVD players are chroma bug free. The Panasonics are the safest bet.
Plasmas have actually come a long way since introduction and the lifespan is 25,000 to 50,000 (according to manufacturer studies) to the half-brightness point, which still isn't the end of the display's lifetime. Burn-in isn't really an issue if you take a reasonable amount of care with it (don't max out the contrast and if the station you're watching has bright static logos use the picture orbiter) and the off-axis viewing angle is 160 degrees. You still would not want to hit the screen though.
http://www.optomausa.com/DLP_demo/example_third_pa rty.htm
Basically a square of very tiny reflective mirrors with a spinning colour disc to colour the light they reflect.
DLP = Digital Light Processing.
[ The DLP mirrors always swivel because they can either be "on" and "off". To show a shade of grey or any non-white and non-white color, the mirrors have to swivel accordingly. ]
Correct. Furthermore, the mirrors "reset" everytime so that they may swivel to on or off. They can't swivel straight from on->off or off->on.
> Plasma's are good for about 10000 hours. But then again they get screen burn like a traditional CRT does
Oh please, stop with the outdated facts. They [Plasmas] are rated for 30,000 till half brightness.
Burn-in is *OVER-RATED* on a plasma. Check avsforums. Out of the 60,000 people posting there, only *1* had serious burn-in, and that's because his wife left the Plasma on for a *week*.
If you don't know jack about a technology, don't comment on it, especially if you don't own one.
One way to get a stereoscopic 3d image is to use two projectors, both aimed to the same place on a silver (polarization-preserving) screen. Each projector has a polarizing filter in front of the lens. You send the left image to one and the right image to the other. The viewer has to wear glasses that have perpendicular polarizing filters so each image gets to the correct eye.
If you want to experiment with using two projectors do this, you will have much better success with DLP.
I played around with it and found that the light coming out of my LCD projectors was somewhat polarized. I worked out a way to put the perpendicular filters in place on my LCD projectors, but the light level was cut significantly by the filter. Any decrease in intensity is supposed to be unnoticable using DLP.
Maybe it doesn't matter though... it was such a pain keeping the images from the two projectors properly registered that I gave up on it after some experiments. Also, there's not much in the way of software that works out for 3D this way. I tried it using the two projectors logically connected using Xinerama and a Java applet that let me choose to show 3d images side by side. It was fun but if the images don't register well you'll quickly get a headache.
In short, it is a very, very fast RGB strobe sequence that has no equivalent that I know of in any other display technology.
Some early color movies (filmed with the Kinemacolor system, before the Technicolor sandwich approach became feasible) had the same sort of strobe effect, except it was RG not RGB.
Will I retire or break 10K?