What precautions needed for a new lcd?

Discussion in 'LCD & LED LCD TVs Forum' started by Rob20, Aug 4, 2004.

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  1. Rob20

    Rob20
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    It seems that you need to set the brightness and colours down low for the 1st 200 hours on plasma screens in order to protect from screen burn etc. What precautions do I need to take when I receive my new Pan 26" lcd? :confused: is screen burn an issue with lcd screens? what other considerations are there?
     
  2. Eyeball

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    No screen burn with LCD which was my main reason for an LCD purchase. I've asked around quite a bit and the main issues that were pointed out with LCD's are smearing and tearing in fast scenes. Also, only Sharp LCD's alllow you to change the bulb, all others don't. Sharp bulbs have a lifespan of around 60000 hours.

    S
     
  3. LV426

    LV426
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    None, in other words. As screen technologies go, LCD are arguably the most robust and don't suffer damage from anything you might do (or not do) with the user controls.
     
  4. Rob20

    Rob20
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    so does that mean I don't have to worry about setting the screen to bright or the contrast up to high?
     
  5. Dr Downey

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    That's right Rob, no problems with doing anything you want to the contrast, brightness, or any other setting you want!

    Cheers!
     
  6. Rob20

    Rob20
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    ok, but what about static images from consoles etc...I know these are dumb questons I probably already know the answer to....just I don't want to ruin a £1,300 investment if it could have been avoided. Cheers. :rolleyes:
     
  7. AgentCool

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    I don't own an LCD TV but I've been using an LCD computer monitor for a few years which is essentially the same thing. I've never had any problems with static image damage and I have been known to leave it on the desktop screen for hours with no movement. However, when you're talking about a £1300 investment it's better to be cautious so I would recommend not leaving it on the same screen for hours on end.

    There will probably be something about this issue in the LCD TV manual I would have thought if it was a problem.

    I look forward to your opinion of this TV as I may buy one myself at some point!
     
  8. TheBoingoBandit

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    If you'd said Samsung then I would have said yes, but for the Panasonic the answer is no.
     
  9. Prodigal

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    LCD is never a problem on burn-in for static image, becasue each pixel on LCD is not a emitting device as plasma or CRT, they only perform blocking & unblocking the lights going through the glasses,while the light is provided by the backlight device of the panel.

    The only worry on LCD is the DC component, never feed any DC signal directly into the LCD module as this can damage it, but I'm sure 99% of the LCD panel users would not open the box and feed the DC into it. :D
     
  10. GaryB

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    If you're buying from a local dealer, make sure you see your particular set working to check for pixel defects before you hand over the cash. Most manufacturers allow a few bad pixels before the set is considered faulty and you may have difficulty getting it swapped if you find one or two bad pixels. You need to check them cold, just after switch on, and hot, after the set has been on for at least half an hour, preferably longer as pixel faults can vary with temperature.
     
  11. Prodigal

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    Rob20

    Although the burn-in is not an issue on the LCD panel, need to take care the brightness and contrast, if they are turned up to excessively high level, this may shorten the life span of the backlight device, or the brightness level would drop faster than normal use. As I know some LCD panel makers ( for PC ) deliberately overdrive the backlight circuit to impress the buyers, but I don't think any reputed LCD TV maker would do this.
     
  12. Rob20

    Rob20
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    cheers for all the replies. Will be careful with the brightness, contrast etc..
     
  13. LV426

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    For most LCDs, Prodigal's observation isn't right (with apologies):

    Adjusting brightness and contrast, on most LCDs, adjusts the properties of the LCD pixels themselves - it doesn't do anything at all to the intensity of the backlight, which will continue to illuminate at its normal, full, extent. There are some devices where the backlight can be adjusted, but most (all?) TV's I've seen don't do this.

    And adjusting the way the LCD pixels are driven has ABOSLUTELY NO effect on their predicted lifespan, which has never been calculated, because it simply isn't a critical factor - they last almost (if not absolutely) indefinitely irrespective of how they are used.

    Just to recap:

    Screen burn-in isn't an issue on LCDs - no, not even on Samsung panels. There is nothing you can do with the user controls that will extend or shorten the life of the LCD panel - no way you can "abuse" the set. Some Samsung LCDs can exhibit a short-term memory but this is NOT a permanent burn-in; it's latent, and disappears with the next screen refresh. And isn't affected by brightness and contrast. And isn't visible in normal use, unless you study the image unrealistically.

    IF (and, as I say, it's rare on TVs) any user control adjusts the brightness of the backlight then you may extend its life by reducing it. However, (for example) Sharp claim 60,000 hours use from their backlights. Although other makers don't make similar claims, it does seem likely that they will all have a similar life.

    Frankly, I just wouldn't concern myself. Aside from checking, when you buy or receive the set, that there are no DOA pixels, there are no precautions you need to take. Unless it makes you psychologically more comfortable.
     
  14. Rob20

    Rob20
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    How many dead pixels is acceptable. It's one aspect that worries me about buying an lcd.
     
  15. GaryB

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    Depends who you ask. The exact spec. depends on the colour, distance between and a few other factors but if we're talking about random light or dark pixels, most manufacturers will allow around 6, hence my comments earlier about checking yours before taking it home. In my experience, the vast majority of LCDs that have defects have only one.
     
  16. GaryB

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    Many recent sets have two brightness controls to allow this. The ones I have experience of call them imaginatively Brightness 1 and Brightness 2. One adjusts the contrast of the pixels as you say, the other varies the backlight.
     
  17. LV426

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    "Acceptable" bad pixels is the only real concern with LCD. I've been fortunate - I don't have any on my several LCD devices (*).

    Acceptable to you, I'd suggest is determined by whether or not you can see it in normal use. If yes - unacceptable; if no - acceptable. However, most manufacturers have a different policy.

    The trick with LCD is to recognise that pixels rarely fail in use; bad ones are usully DOA. So you need to buy either

    a) from a retailer that has an enlightened returns policy - I understand, for example, that John Lewis are pretty good at this OR

    b) from a retailer that has stock in the store, and will allow you to briefly test YOUR set before you pay for it OR

    c) from a distance retailer (internet or phone) with a good reputation for dealing with the Distance Selling Regulations properly. (These rules allow you to cancel the deal and obtain a refund in full within 7 days of receipt, without necessarily giving a reason, although many retailers will try their best to wriggle out of this responsibility, citing such things as "you've opened it" as reasons - this isn't valid by the way).

    (*) actually, my projector has one, but it isn't visible in normal use, even though I know where it is - hence, it's "acceptable" to me.
     
  18. reckless

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    The new sony has a separate backlight control and I found this most useful when I demod the screen. Managed to get details into the white objects in a white room demo they were displaying. It wasn't fully variable, just 100%, 75%, 50% etc if I remember correctly.

    My LCD computer screen doesn't have this and, as a result always looks slightyly too bright to me.
     
  19. Rob20

    Rob20
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    I've bought mine from unbeatable and having it delivered today sometime. Unfortuantly I can't see the delivery guy hanging around for me to set up and check for dead pixels.
     
  20. LV426

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    You don't need him to wait. If you unpack it carefully, without damaging any of the materials.....

    only take out the TV itself, not the remote, batteries etc,

    connect it up to power and turn it on

    set it to an AV channel using fascia controls (assuming it has some) or PC input if available

    in other words, so the backlight is lit, but there's no signal (a plain black screen) and look for bright pinpricks.

    If yes, pack it up again as closely as you can to how you received it, and then call them and demand your rights to cancel under the terms of the DSRs - and confirm in writing.

    Here's hoping you don't need to do any of this.
     
  21. Prodigal

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    Nigel,

    I do agree the contrast has nothing to do with the brightness, it only adjusts the voltage applied between the upper and lower plates of the "liquid crystal display" which is to allow or block the amount of light going in to achieve the contrast effect, Having said that I did mention that the backlight got nothing to do with the LCD pixels or the panel itself, however, the backlight tube do have the risk to get damaged or deterioate faster than the normal decay period if they are overdriven. Again, I have mentioned that I don't think the reputed LCD TV manufacturer would overdrive them, but this is also one of the precaution to take on a new LCD TV for having a long pleasure viewing experience.

    Just my 2 cents. ;)

    some useful info in this linkSome useful info. here
     
  22. LV426

    LV426
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    I'm not denying that if there is a backlight adjustment, keeping it low may prolong lamp life. I was just observing that, for the most part (sets I've seen) there is no such adjustment, so anything one might do with the user controls will have no meaningful effect on the life of the set. In answer to the original question.

    Also, if Sharp claim 60k hours from their backlights, it seems probable that others will be similarly long-lived. Even at half this life (30k hours) that represents 10k days at 3 hours per day and 10k days is just shy of 27 years. Or 14 years at 6 hours per day. etc. Just to put it into context.
     
  23. Rob20

    Rob20
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    The toshiba has an adjustment for brightness, and one to adjust the backlight, (between 1-15). So I guess to prolonge the life of the bulb you should keep the backlight down to an acceptable minimum?
     

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