1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Why rainbows in Plasmas?

Discussion in 'Plasma TVs' started by Orangelo, May 17, 2005.

  1. Orangelo

    Orangelo
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    I have made a search and I have seen that some of the members have identified this artifact in Plasma screens. At first I thought that I was being misled (so much time with DLP PJs can seriously harm your senses :rolleyes: ), but the more Plasmas I see the more obvious it becomes that the artifact is there.

    Anyone has an explanation for this? I'm curious... in (single chip) DLP PJs the cause for rainbows is sequential color, but in Plasmas, the electric signal should excite the R, G and B subcells at the same time. In any event, they are a different kind of rainbow, in Plasmas it's a yellowish - greenish (mustard I would say) flash on bright whites. The beginning of the League of Extraordinary Men is a particularly good test.
     
  2. Gussie

    Gussie
    Member

    Joined:
    Oct 19, 2004
    Messages:
    1,236
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    48
    Ratings:
    +80
    I too would like an explanation of this phenomenon.

    Even the proper name for it would be a help!

    Maybe you've seen my posts on this. I returned a TH-42PWD7 because of this and some other issues.

    I've been fortunate enough to have seen various plasma panels at home in my lounge - and they all seem to do this - even one HD 1024x768 I had.

    But it seems LCDs dont suffer from this - I played with a Samsung 40" LCD for one day and where you see this effect on plasma panels - it (like CRTs) just showed the expected grey blur on the moving edge. However I'm not advocating LCDs - it had other issues which were much worse in comparison with this plasma effect e.g. no blacks - artificial colours - smearing.

    I'm now waiting to see the new Panasonic 500B - to see if they've fixed this.

    Gussie :)
     
  3. MrNPG

    MrNPG
    Active Member

    Joined:
    Apr 13, 2005
    Messages:
    714
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    31
    Location:
    Poole, Dorset
    Ratings:
    +44
    I "suffer" from the rainbow effect too with my Panny 42PE50. It's pretty frustrating but I presume I will just have to live with it as, from what I understand, it is not an actual fault with the TV, just that my eyes are more sensitive to this "side effect" than other people's eyes are. :(
     
  4. Timmy C

    Timmy C
    Well-known Member

    Joined:
    Oct 10, 2003
    Messages:
    4,396
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    86
    Ratings:
    +199
    Does it spoil your viewing? I used to get rainbows from my old Sim2 pj but since upgrading to a newer model I hardly notice them. I'm looking to buy a PE50 this week but if rainbows are a problem with plasmas then maybe I'll stick with my old telly.
     
  5. Enquirer

    Enquirer
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
  6. MrNPG

    MrNPG
    Active Member

    Joined:
    Apr 13, 2005
    Messages:
    714
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    31
    Location:
    Poole, Dorset
    Ratings:
    +44
    Yes Timmy C, it does spoil my viewing a bit. Like I said though, I will just have to learn to live with it as I've just paid out £2K on the TV so can't really do much else.

    Does anybody know any steps that can be taken to reduce the "rainbow" effect?? Change room lighting, reduce/increase contrast/brightness/colour settings on the TV??
     
  7. nicke20

    nicke20
    Active Member

    Joined:
    Oct 11, 2003
    Messages:
    874
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    21
    Ratings:
    +13
  8. Orangelo

    Orangelo
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Oh, thanks for the link, nicke20 :smashin:

    So the explanation available is that different phosphors decay at different times. Makes perfect sense to me. Especially because in the beginning of the League of Extraordinary Men, the artifact is most visible as the bright white areas (torches of guards, credits) move out of the screen or fade away, not when they appear.

    But why do different phosphors decay at different times? Should they not have the same persistence?
     
  9. LV426

    LV426
    Administrator Staff Member

    Joined:
    Jul 14, 2000
    Messages:
    12,754
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Somewhere in South Yorkshire
    Ratings:
    +4,908
    First up - unlike LCDs, plasmas do flicker to a degree. Some, worse than others. The early Panachronics were the worst I've seen. If they flicker, there must be something intermittent about how the Plasma cells emit their light. They must flash on and off, in fact.

    Although I've no way of knowing for sure, I wouldn't be at all surprised if the three colours aren't energised at the same time. Hence, each colour subpixel would flash on at a different moment to its partners. If true, this would cause the same effect (by somewhat different means) as on DLP.

    I'm equally convinced that some (or all?) 3-tube CRT projectors don't refresh their three tubes at the same time. They, too, emit rainbows.
     
  10. Stephen Wilde

    Stephen Wilde
    Active Member

    Joined:
    Nov 15, 2003
    Messages:
    1,810
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    48
    Ratings:
    +93
    On a close inspection of crt, projector,lcd and dlp technologies they all seem to show artifacts of one sort or another or have inadequcies of their own. CRT has the advantage of having it's drawbacks partially disguised by smaller screen sizes.
    The presence of some defects is inevitable whatever you buy.
     

Share This Page

Loading...