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Discussion Starter · #1 ·
Hello everybody,

i just saw a talk helt by someone who develops LCD panels for the last 10 years.

He said and I quote: "All LCD display panels and also LCOS panels will have some failing pixels after a long time exposure of 3000+ hours to the intense illumination of modern UHP projection lamps. This will result in misalignment problems of those affected pixels.


Guys this scares the hell out of me and I am wondering if there are long term LCD owners here who have used their projectors over 4000 hours and have those pixelmisalignment problems??? (probably will show up as blobs)


Kjelt.
 

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I have heard stories of relatively short life for LCD panels (not as short as 3000 hrs though). I've heard it enough that I kind of believe it, but have never seen any real evidence.



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Steve
 

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Kjelt, as a PhD photochemist I can tell you that I would be surprised if an intense light exposure of LCD or silicon panels over many hours does NOT result in some deterioration.


We're talking 200-400W UV lamps emitting tightly-focused, highly energetic light onto 1 inch panels over thousands of hours!!!


This type of light wreaks havoc with many molecules, LCD and silicon-type included.
 

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Basically a bump.

This is potentially an important issue, and I'm hoping someone else will be able to provide some info.



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Steve
 

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Discussion Starter · #7 ·
I talked to the same guy and he said that also DILA or better LCOS (since that is the technology) panels would be influenced but somewhat less since they reflect the light instead of passing through or absorbing. It would generally take a longer time to see the same influences.


DLP will NOT be influenced but that is not LCD technology.


Kjelt.
 

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The military utilizes a lot of 20" Barco LCD falt panel displays. The 10,000 hours mean time to failure for the backlighing is by far the dominate failure mechinism and the LCD panel really doesn't come into play. Of course the lighting is not as intense and it also really matters what you consider a failure. A bad pixel here or there may be acceptable.
 

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LCD has to BLOCK ALL of the light to go "black", which basically means to ABSORB all of that energy. A flat panel typically uses a relatively tiny light source, so it can last almost forever. However, try to put a black piece of paper near a 200+ watt light - foom! A business FP will be tossed before 3000 hours (i.e., resold to one of us!), but I'm seriously worried about this for HT.


However, there should be someone out there who has run a 400Q or whatever for over 3-4Khrs - any actual experience?
 

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I don't know if it means anything but if laptop screeens are anything to go by lcd screen lifetime is about 4 years. We had a load of old laptops which had been returned after being replaced with new ones. 80% of the screens were really poor.


Jeff


[This message has been edited by JeffY (edited 06-07-2001).]
 

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What's really interesting to me about this thread is that NO ONE who has displayed any credentials about LCD panels has given any indication that LCD panels in high output projectors are reliable. The silence is deafening! I can't believe major manufacturers don't have someone who follows this forum. If there is no problem, why hasn't someone come forth?



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Steve
 

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I have had some recent experience with some 1024 LCD units which all posess the same failure point. It was from running the blue screen for extended periods of time. The Dichromatic element before the blue LCD panel was-and is- hosed... burned actually. So.. the PJ's have about 500 use on them, max. All three have their original bulbs, and are quite clean inside. So, the 500 hours is a guess, but i have seen enough doust inside of various units to predict the useage to some degree of accuracy. If I am off by 20%.. that ain't much in the way of hours, no matter what. BTW.. the LCD block is avialable in these particular units as a single unit only,and clocks in at $7k CDN. (about $4.7K US).


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Ken Hotte

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Quote:
Originally posted by steve5097:
What's really interesting to me about this thread is that NO ONE who has displayed any credentials about LCD panels has given any indication that LCD panels in high output projectors are reliable. The silence is deafening! I can't believe major manufacturers don't have someone who follows this forum. If there is no problem, why hasn't someone come forth?

Yeah, but on the flip side, with all the LCD projectors out there, where's the real evidence this is real widespread problem?
 

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Well, I just cleaned down a 1024 X 768 1400 ANSI unit that has over 7500 Hrs on it and is now running on its 5th lamp. Its used as a set of three for an eighteen foot window display, the other two have similar hours aswell and there is no pixel droput on it, The other two of them have only two edge located pixel failures on one unit!.

Remember keep those filters clean!! they are the life of a lcd projector, under bad conditions and locations I have seen filters start to have a serious dust accumulation after only two hours use!


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Paul O'Hale
Your lies are like bananas,they're yellow and come in big bunches!

Leslie Neilson,Wrongfully accused
www.mcgahon-oneill.com
 

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How about three 1024x768 800 lumen units that ALL HAVE LAZY PIXELS in the blue panels, and all three are SCREWED, and ALL THREE have about 500 hours on their original lamps. Hows that for CRAP!!!?!?!


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Ken Hotte

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jonmx,

Good point. In this thread there is a response that has seen the problem and one who has not. Anyone out there who has more than 3000 hours on an LCD without having a problem? Also, anyone else who has seen a problem, when did it occur? Maybe we can build a mini-data base.



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Steve
 

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Ken

3 dead blues!, then substitute a red its the same panel only the green is different.


Paul


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Paul O'Hale
Your lies are like bananas,they're yellow and come in big bunches!

Leslie Neilson,Wrongfully accused
www.mcgahon-oneill.com
 

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AH HA! Thanks Paul, that really pulls my ass out of the fire here. I also aligned the panels on a small screen, and re-adjusted the focus to compensate for the angle of mount (to check panel alignment... all the time checking for liniarity to the prism. Afterwards... I take it to the big room... why is the top out of focus?.. and then/or the bottom?...damn.. I forgot about the rake. oh well.. back to the drawing board.


Well, at least I have the spare red I need... this way I can get at least one going.. what is a panel on these puppies worth? I need a panel and a dichroic(sp ?) for the blue to get the second one going. The third is beat, I guess.


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Ken Hotte

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[This message has been edited by KBK (edited 06-09-2001).]
 

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Doesn't the light first go through the red, green, or blue cellophane (or colored glass) before hitting the approx. 1 inch square LCD panel, so the panel is spared most of the energy it would otherwise have to absorb when black?


Other video hints: http://members.aol.com/ajaynejr/video.htm
 

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One should be cautious and restrained on this topic in this category.So here goes.....

"And the hits just keep coming"

(Tom Cruise-A few good (Projectors)MEN(sorry).
http://www.avsforum.com/ubb/smile.gif


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Ron

"Your priorities will be different-its the weighting that counts!"
 
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