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Why can't plasmas do 'real' blacks?

Discussion in 'Plasma TVs' started by chedmaster, Jul 11, 2005.

  1. chedmaster

    chedmaster
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    If I remember my howstuffworks reading correctly, the "pixels" themselves are light emitters, so why can't they be "switched off" to produce a real black?
     
  2. ikon66

    ikon66
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    if the pixel is turned off, how quickly will it come on and then change when the colour changes?
     
  3. Mep

    Mep
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    also, I don't think 'off' is true black anyway
     
  4. Sulis

    Sulis
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    That's the problem. There needs to be a 'standby' charge to get it ready to fire in as short a time as possible (remember how plasmas used to smear movement?). Even CRTs aren't REALLY black - there's a lot of stray light floating around inside, as you can tell when you turn them off (and they're not actually black then, just a dark gray). LCD have a different problem, which is trying to block the light from the backlight - some of it still gets through. What matters is the perceived blackness - which is why Philips use a backlight behind their sets to avoid you seeing the darker black of an unlit room (at night, that would be).
     
  5. Welwynnick

    Welwynnick
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    Frustrating, isn't it? The pixels must always be active; they cannot be switched off completely. It's intrinsic to the mechanism of light generation within plasma cells, which would discharge otherwise.

    Every illumination sub-field that is addressed to each pixel consists of an addressing period, a light emission period and a reset or priming period. During the reset period, a brief write pulse is required to maintain charge within a cell that may have been off for some time, otherwise it will not be able to respond to the next command pulse.

    Panasonic seem to be more effective than other manufacturers with cell discharge management, only sending recharging pulses when necessary in dark scenes, but it seems there's still some way to go.

    Nick
     
  6. Pat Marcus

    Pat Marcus
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    Some always do blacks better than others. Pio XDE does them pretty well, as do Pannys and my own Fujitsu. When the screen is set up properly, blacks are quite achievable. Another reason why its worth having the panel ISFed
     
  7. chedmaster

    chedmaster
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    thanks for all the replies, really informative, ta.
     
  8. Rahmorak

    Rahmorak
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    I certainly find the Blacks on my Fuji excellent. While they may not be the ideal they are considerably better than the blacks I see on many badly setup TVs.
     
  9. chedmaster

    chedmaster
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    i understand that a lot of plasmas are brilliant at it (relatively speaking) for example even my dad's old pw4, when you turn it on there is the slightest change of brightness, but when watching the blacks easily good enough to not cause distraction. I love his screen, but still think my £250 2nd hand tosh is better. If only it were bigger.
     
  10. Rahmorak

    Rahmorak
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    You want to EAT your cake Sir?! Pffft. :)

    Although I have some grumbles about my Fuji, the size, slimness, geometry, HD capabilities and sheer wow factor means I would never go back to CRT for slightly better blacks. It is all about compromise and what is most important to you. :)
     
  11. Jazz Monkey Jr

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    I watched Meet the Fockers and Constantine over the week-end and the black levels and colour still impresses me.
     
  12. chedmaster

    chedmaster
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    if i could afford a £4000 50" fuji and a £1000 scalar im sure id be pretty happy with it. but getting £30 a week fo a paper round and cleaning a pub i cant _quite_ afford it!
     
  13. Mep

    Mep
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    which Pub Ched...Red Lion or Bricklayers?
     
  14. spylab

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    Not perfect black levels is a side effect of the aperture ratio, thas is the ratio of active versus non active(space between pixels) area of the panel valid for
    lcd or plasma panels.There is a leak of light between the pixels that spoils black levels.
    In HD panels the black suffers more cause the space between pixels is more.(biger aperture ratio)
    So it is more dificult for a HD panel to have good blacks.
    One other side effect is the visible pixels from sort distance.

    Maybe some of the profesionals can comment? :)
     
  15. Rahmorak

    Rahmorak
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    A PW7 probably isn't that much different to my Fujii 50" for SD material but is one of the cheapest panels around.

    I agree it would be nice to have true blacks, but in reality they are never a big concern for me and I imagine most people with the relatively cheap PW7s would agree. Far more important for me are the posterisation and rainbow issues but I still wouldn't go back to CRT. :)

    However if budget is limited and you don't mind CRT bulkiness I wouldn't be looking at Plasmas anyway, I would probably be looking at a 2nd hand Sony WEGA 36" CRT, a DLP RPTV (after making sure rainbows are not a huge issue for you) or some equivalent.
     

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