LCD Screen Quality Degredation

Discussion in 'Displays' started by Steven_J, Oct 11, 2004.

  1. Steven_J

    Steven_J Auditioning

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    I have read the test done at Texas Instruments that shows how LCD projectors loose picture quality and over time you would have to replace components inside the projector that will be costly over time if the projector is not under warranty. This really scared me being that I was about to buy the Panasonic PT-AE700U. Is there anything someone can tell me that will restore my hope? Other wise i'm looking at the InFocus ScreenPlay 4805. Thanks.

    -steve-
     
  2. Leo Kerr

    Leo Kerr Screenwriter

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    1. I can confirm that the LCD panels do degrade over time.

    2. "over time" in our case seemed to be 6k hours of 9 hour days for a 3k ANSI lumen projector with poor air flow. That violated every one of the manufacturer's recommendations. (Turned out that they had an undocumented duty cycle of 2-3 hours on, 6 hours off. At least, thats what they said when we returned three projectors for warranty service!)

    If you run under normal home-theater operations (that is, not all the time - 2-4 hours in a shot, once a day,) they will tend to degrade slower.

    If you run in a lower power mode, or even not a 3000 ANSI lumen projector like the AE700, you should see a boost in panel life.

    Another way to look at it is, suppose it lasts you 4 lamps... 12,000 hours, that's three thousand two-movie nights - 8.2 years of two movies a night, every night., without fail. At that point, you may very well be prepared to replace the AE700 with a QHDTV resolution projector, anyway.

    Personally, I will take TI's report with a great deal more interest when they start selling 3-chip DLP projectors for the same price as 3-panel LCD projectors - right now, for the cost of a 3-chip DLP, I'd rather get a three-panel JVC D-ILA projector.

    Leo Kerr
     
  3. Steven_J

    Steven_J Auditioning

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    Thats exactly what I was thinking. The colors you get with a
    3-panel LCD totally blow away single chip DLP projectors. The Panasonic PT-AE700U gets 1 billion colors I believe and the ScreenPlay 4805 gets what most single chip DLP projectors get 16.7 million. Theres a huge difference and thats why I was really disheartened to hear about the panel degredation.

    The only real problem I have is like you said I can get three thousand two-movie nights; well knowing that the movie on night two thousand is a much lower quality than the movie was on night one thousand just bugs the hell out of me. Especially if i'm going to spend a couple thousand dollars on the projector.

    Thats why I like DLP being that it will not loose image quality over that small a period of time, the image quality would probably outlast the life of the projector, thats still the only hang up I have. Thanks alot.

    -steve-
     
  4. Leo Kerr

    Leo Kerr Screenwriter

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    The degredation shows up in a number of fashions.

    1. optical block delamination. I don't know if this is what it really is, but it looks that way. This manifested as 'blue clouds' slowly forming in the two projectors that began to show this problem.

    2. polarizer decay. Slowly the black level of the individual color channels begins to decay; usually in a slightly uneven fashion.

    Now, here's another issue that will be an even worse plague on your mind than panel decay:

    Lamp decay. Unless you get a projector that runs a xenon arc, you will have serious lamp problems - color, brightness, stability, and start-up / warm-up time - long before the lamp reaches the 'end' of its life. How any of these will affect a specific lamp serial number is unknown until it does happen, but it will happen.

    Now, as a consolation, here's how I'm addressing these issues at a subconsious level.

    I have an LCD projector at home. I would NEVER EVER get another LCD projector for work, where we put a minimum of 3200 hours/year on the projector.

    But at home? In my situation, here are the fact(or)s.

    1. Nominal 3000 hour lamp.
    2. Average 12 hours/week.
    3. Estimated 4.8 years/lamp, +/- 1 year, just to be safe.
    4. Lamp cost: currently ~$400
    (5: current hours, 1000)
    (6: current estimated lamp-change: Sept 2007)

    Question: What will be available in the home projection market in the fall of 2007 for under $3000?

    Is it worth replacing the lamp (1/6th purchase cost) when for half the purchase cost I can get a newer, better projector?

    The worst thing I've discovered about the whole home theatre craze is: once you commit to something, you'll worry about it for a long time.

    My advice here? Buy the projector you think looks best.
    AND DON'T LOOK AT THE PROJECTOR MARKET FOR AT LEAST 6 MONTHS AFTER PURCHASE!!!

    Second-guessing can kill.. if not you, your happiness. Enjoy your projector; that's what this is all about. And unless you're getting a $25,000 projector, don't be afraid to consider replacing it in the near future... (~5 years or so.)

    Leo Kerr
     
  5. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    I suggest if you give it good ventilation and keep to the higher fan speed, you will be fine. If not ... degradation can set in as little as 500 hr into the life of the unit.

    These are observations made from the Panasonic AE 100 and AE 300 units that I have owned over the past 2.5 years. The AE300 started to show signs of polarizer degradation at about 500 hours ... and at about 700 hours, I went to high fan speed and added and external fan for better air flow around the unit. This seems to have slowed down the decay considerably.

    Just think of it as another wear and tear item ... like brake pads on a car ...

    Don't let a $90 part dictate to you how you will make a purchase.

    It is also quite an over statement to say that LCD colour "blows away" DLP ... It doesn't ... and the differences are far more subtle.

    Regards
     
  6. Steven_J

    Steven_J Auditioning

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    The panel is $90? I wasn't really sure how much the actual parts would cost that I would have to replace. To tell you the truth $90 isn't bad at all. I was thinking I would be looking at a $500 cost or maybe more.

    Honestly though, too many things can go faulty with an LCD display. The panel degradation for one, but also individual pixels can burn out. I'm just not sure I want to have to worry abou that many problems. I think i'll go DLP. Yet....still undecided! I need to sleep on it.
    Thanks alot guys.

    -steve-
     
  7. Leo Kerr

    Leo Kerr Screenwriter

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    In my experience, the DLP mirrors are probably about as likely to break as the LCD cells stop working. (In my case, I've had zero pixel failures in either.)

    I haven't persued parts before for rehabing LCD projectors; the earlier time it was on a now 5 year old model, and the manufacturer dealt with it by, in essence, replacing the entire optical assembly at half or more the new purchase cost. (Except it was under warrantee.)

    Leo
     

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