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Rainbows question

Discussion in 'TVs' started by mr_sockochris, Oct 13, 2005.

  1. mr_sockochris

    mr_sockochris
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    I got a Samsung Sp46l6hx a month or so ago and when I first got it I could see rainbows, especially with TV broadcasts, DVD's and games were less noticiable for some reason. It wasn't bad enough to even consider taking it back, but I could see them now and again if I wanted to. Now however, I can't even see them on anything. Is this because I'm used to it or is it just because the bulb has 'worn in' over the past few weeks of use?

    Just curious :)
     
  2. LV426

    LV426
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    Knowing broadly how these things work gives me no reason to suppose that anything might happen during a "running in" period to change the set's rainbow performance. It certainly cannot be bulb related. I believe the only cause is you who has got used to it, stopped looking for it, whatever.
     
  3. Starfleet

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    :hiya:

    I still see rainbows but only when i force myself or inadvertently move quickly looking away from the screen.

    Definitely not bulb related or colour wheel, as been to currys who have had their screen on continously for last 3 months. still can see rainbows on them.


    I dont think the rainbows will disappear completely more like we'll say oh look a rainbow rather than aaargh another rainbow.
     
  4. logiclee

    logiclee
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    Over a few low quality demos of Sagem and Samsung DLP's I didn't see any Rainbows.

    The first good demo I had was on a 50L6HX watching Titanic on DVD, as the ship sank the picture is dark with white peaks on the sea. I could see rainbows flashing off the sea. There is no way I could sit and watch it so I had to rule DLP out.

    I may have got used to it but there is no way I could justify spending £1500 - £2000 on something that I might not be comfortable watching.

    Cheers
    Lee
     
  5. the_pauley

    the_pauley
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    This is one I've been considering. As LV states, it's probably nothing to do with the bulb burning in. One possibility is it could be the colour wheel "running in" and becoming that tiny bit smoother / faster in its rotation.

    :confused:
     
  6. JayList

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    I both agree and disagree (me on the fence then!). I understand your point, although I am purchasing a DLP on the understanding that all will be well.

    If not then theres always the return policy. But you would get ghosting and pixellation in LCD's for example, or screen burn in Plasma.

    They all have defects, it's a question of which one you are prepared to put up with in context of everything else.

    I like the quality/size/price aspects of large dlps that I can't see anything close at this point.
     
  7. logiclee

    logiclee
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    I've gone for the Sony 3LCD high definition rear projection tv.

    For me seeing the rainbows wasn't just annoying I couldn't even watch the screen as it was making me dizzy.

    It seems that some people can't see them at all, some people get the odd flash of colour and a few people are really effected by them.

    Cheers
    Lee
     
  8. blearyeyes

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    The 'rainbow' effect is caused by the colour wheel in DLP sets which has to cope with the three primary colours since there is only on dlp chip. The eye is susceptable to seeing these under certain circumstances in peripheral vision. However I assume that if the dlp chips become cheap enough i.e when a Taiwanese manufacturer manages to produce a copy of the original Texas Instruments devices then then future rpro sets might incorporate 3 seperate DMDs, one for each colour which would entirely eliminate this effect. However I suspect that by this time some other technology will have been developed to replace dlp. :thumbsup:
     
  9. JayList

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    Me I'm waiting for retinal laser projection aka Virtual Retinal Projection VRD, an inifinite and infinitley adjustable view size then!

    Military have single colour lasers at the moment, but three laser colours should do it. Then no more screens, just a little implant at the side of the eye.

    http://www.hitl.washington.edu/projects/vrd/project.html :thumbsup: :cool:
     
  10. JayList

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    I hear you. I am just crossing my finginers that I don't suffer from it.
     
  11. LV426

    LV426
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    Equally unlikely. The rotation of the colour wheel has to be very tightly controlled so as to synchronise exactly with the image applied to the DMD. If it didn't, then the colour balance of the image would go very wrong. And the speed is determined by the specified behaviour of the TV, wheel, DMD. The video processing will send sequential images to the DMD at a given and fixed rate*. And the wheel has to spin to coincide exactly with this fixed rate.


    3xDMD front projectors have been available for a little while and, more interestingly, have just been re-priced to about half their original price. It isn't the DMDs that are costly, I gather. It's the other optics (prisms, colour filters, whatever) that are harder to produce than those used in 3LCD systems. That's their excuse, anyway.


    * In a 6x system, for example, this rate, for PAL video, is 6 x red, 6 x blue, and 6 x green components (i.e. a total of 18 frame refreshes) in every 1/25 second (frame of video). In the same system, if the wheel has 6 segments (2 of each colour), then it must do exactly 3 complete rotations in every 1/25 second. Hence, the wheel presents the DMD with 3 x 2 = 6 occurrences of red, blue and green, per 1/25 second (video frame).
     

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