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What the hell is a CRT Projector?

Discussion in 'Projectors, Screens & Video Processors' started by kmhtkmhtkmht, Oct 4, 2005.

  1. kmhtkmhtkmht

    kmhtkmhtkmht
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  2. Welwynnick

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    Do you mean to say there are any other sorts?
     
  3. Mad Mr H

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    Im not sure but I have heard of 2 types of projector

    1. CRT Projector

    2. Cinema projector - of course this uses a film roll



    There are of course other projectors - like a tank - that projects missiles but thats just silly talk.

    oh!
    I did once hear of someone putting a bulb in theirs, I presume this helped them see inside it, cant think of any other use.
     
  4. Gary Lightfoot

    Gary Lightfoot
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    That's a film projector like at the cinema. :)

    CRT = Cathode Ray Tube, much like your big old tv at home in case that's what the OP meant.

    Gary.
     
  5. Welwynnick

    Welwynnick
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    Ho ho ho.
    And what kind of contrast do you get from one of those?
    Nick
     
  6. Gordon @ Convergent AV

    Gordon @ Convergent AV
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  7. Thunder

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    So you'd like a 12" now Gordon? :D Have you seen one of these in action?
     
  8. fortean

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    A CRT projector is unique in that it projects CRT's (Carbonised Radioactive Teleromes), usually on to a black screen. The screen of course looks white because it reflects all frequencies of the visible light spectrum. As everyone knows a surface of a particular colour can not reflect light of the same colour.

    When these CRT's hit the screen they change the density of the molecules at the point of impact. As the density of a molecule increases it traps more and more light until it is at almost infinite density at which point enough light is trapped to make it appear black. By varying the amount and type of CRT's at any given point an image can be created on the screen.

    One of the dangers of early projectors was that when they were left on without a source signal they bombarded the screen with massive amounts of CRT's to create a black image. This resulted, after a few hours, in the screen achieving critical mass and collapsing in to a black hole. This black hole, ex screen, would then fall through the floor and continue until it reached the centre of the planet. Luckily a screen would reduce to less than a nanometre in diameter and so the damage to the floor, and the planet, was insignificant. To get around this problem modern CRT projectors produce a blue screen when there is no source signal present.
     
  9. Welwynnick

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    :D
    12" CRT - bet they didn't sell very many of those!
    287 lbs, but still "only" 120 MHz RGB bandwidth - not exactly the ultimate.

    Nick
     
  10. Chris Frost

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    Yes, we lost two cats and Grandma that way. It was tragic :rolleyes:




    ;) LOL
     
  11. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Hi Thunder,

    I've done a couple of them.....the pcture doesn't do it justice....it's HUGE....Think of each tube as being like a portable TV and you get an idea of the size.

    Gordon
     
  12. Ed Selley

    Ed Selley
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    In our case, we kept the output strong and created a stable quantum singularity that has powered the office for the last six years as well as allowing me to go on holiday to Alpha Centauri this year.
     
  13. Thunder

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    Whats the PQ like mate?
     
  14. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    One was run from a Faroudja3000 the other from a Faroudja 5000 an HD Leeza and now a Lumagen HDP Pro. Not seen it with the Pro...Looked nice with HD and the Leeza. With the Faroudja's they were both BRIGHT. I liked them in a clunky sort of way.

    The current verson is 912 I think. Never seen one of those.

    Gordon
     
  15. Nic Rhodes

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    Post of the day :clap: :)
     
  16. Siamese Cat

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  17. Gary Lightfoot

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    If you mean from a cineam projector, then generaly maybe up to around 2000:1. Apparently the film or Hi Def cameras used are only capable of 1000:1, so if true, any CR over that is achieved via processing of the film stock for better black and higher CR, though that doesn't create any more image detail.

    Gary.
     
  18. johann1979

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    This is probably the dumbest and most uninteresting question anyone has asked, but I am completely new to all this and i have just been doing a little bit reading so far. I am in the market for a new projector and have been looking at LCD and DLP projectors until now...

    Can somebody explain to me whether a CRT projector also makes use of lamps like LCD and DLP?

    Sorry if this question seems really stupid... ;)
     
  19. Gary Lightfoot

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    No, it uses an electron beam and phosphor which is stimulated to one degree or another and will glow accordingly. Phosphors vary in performance and are not all the same.

    Anyone know if the gamut range of phosphours has improved in the last 50 years?

    Gary.
     
  20. Thunder

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    No they use Cathode Ray Tubes like a conventional television set. The projector has three of these, one each for red, green and blue. The light from the tube face is used to project the image through three lenses and the three images are converged onto a screen to provide a full colour image :thumbsup: No bulbs = superior contrast + three dimensional image and a much longer life span :smashin:
     
  21. LV426

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    3-d image? I doubt it. Otherwise, true.

    Plus, drifting convergence, inability to move the projector without having to repeat the prolonged setup routine, inability to use anything but a fixed screen, tubes that do deteriorate over time (phosphor burn), refresh flicker, rainbows (and no, I'm not getting confused with DLP)...........
     
  22. alexs2

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    Not sure about the longer life span either,as the tubes tend to be driven pretty hard,although maybe not as hard as those in RPTVs....maybe someone like Gordon or Roland could give an idea of average lifespan?
     
  23. Thunder

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    Well I know several people that use non fixed screens. I wouldnt say that 15000 hours is a short lifespan. Mines been up for nearly a year and hasnt needed any convergence adjustment yet. They definately give a more three dimensional image in my and most other eyes. The only one I will conceed is size and difficulty in set up. Otherwise its no contest :)
     
  24. alexs2

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    I do agree about the image and contrast,plus the lack of rainbows,but the other drawbacks like tube burn and replacement costs are irritating....I do of course speak from the viewpoint of CRT based RPTVs
     
  25. Thunder

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    15000 hours! They don't really suffer from screen burn any more than a conventional television set. I play x-box on mine regularly with no detrimental effects :)
     
  26. Gary Lightfoot

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    Don't forget that DLPs have better ANSI contrast (if the room allows it) which allows for better contrast within scenes that contain both dark and bright material within the same frame (i.e halo effect or lens scatter even with LC machines) and this helps with depth of field as well. Considering that the source material probably doesn't exceed 3500:1, higher CR doesn't amount to more detail, but better black and possibly the impression of better depth, though I've not seen more depth or detail in higher CR displays when doing a direct comparisons (and I've been looking for it).

    DLPs also have excellent white and colour uniformity which CRTs can struggle with, especially if they don't have excellent contrast modulation. CRTs look smoother but on some models this can look softer in comparison to a DLP, though that can be a preference rather than deficiency either way. DLPs also can track D65 greyscale accurately too which is usefull for a constant colour temp from black (uh-hum) to white, though some higher end CRTs can do this admirably as well. CRTs do better blacks of course and this is what gives the superior contrast, though DLPs can be brighter if you want that (or need to watch with ambient light).

    All projectors have their pros and cons and none are perfect, but 8" and 9" LC CRTs deliver an overall better package IMHO, all things considered, provided you have the room for them. Don't think that digitals are point and shoot either - they can be to a point, but ideally need to be set-up correctly, as do CRTs of course.

    Gary.
     
  27. kmhtkmhtkmht

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    I bought a Barco once - 45000 new, I paid 800 quid for it - it needed a lamp change and it needed factory refurbing and stuff that would've cost me 600 quid - I binned the thing - it was a POO.

    4500 Lumens or something ridiculous too!
     
  28. LV426

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    So, you already knew the answer to your original question, then?
     
  29. Nic Rhodes

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    well that was a waste of time then :( Enjoyed the one post though
     
  30. kalW

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    Here's a good CRT primer to learn the ins and outs of CRT's vs DLP/LCD/etc:

    http://www.curtpalme.com/CRTPrimer.htm

    Kal
     

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