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A Technical Perspective.

Discussion in 'Projectors, Screens & Video Processors' started by Vince M, Jun 2, 2005.

  1. Vince M

    Vince M
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    found this on the AVS forum,which I think explains nicely the differences in technologies(crt/digital).
    The die hard crt`ers in here will be well aware of this already im sure,but still makes for an interesting read -especially if you are just getting into or deciding whether or not to get into crt.

    "Here is an engineering perspective, - at this time all digital projectors suffer from several fundamental design challenges.

    The compartment housing the bulb cannot be made absolutely 100% light efficient. In other words, some percentage of light that the bulb generates does escape. We call it leakage. This leads to problems with contrast and we all know that those problems manifest themselves with blacks that look more like grey. It does not matter if we are looking at $25k 3-chip projector or if it’s a lowly 1-chip unit. It also does not matter if it’s a DLP or LCD technology. The servo-controlled iris helps a bit but it does not solve the problem in fundamental way. At this time there is no solution for this problem that I am aware off.

    I often think of a conceptual analogy that can be made between the Digital Projectors and modern 24-bit D/A chips used in audio. Yes, those 24-bit converters had internal 24 bit architecture boasting a theoretical 144 dB S/N, but due to high internal clocks the lower 4-6 bits (or sometimes more) are completely masked by noise resulting in a 16-bit converter and that is on a good day! Similar picture exists in a digital video world. Yes, the internal matrix, be it a DLP or a LCD engine can theoretically resolve the grey scale all the way down to zero, but the noise or leakage of light kills that considerably.

    Another fundamental problem is bulb design. The inability to turn the current off instantaneously only compounds the problem of inferior contrast. This is the area that holds the most promise, but the technology that can achieve what we all need is outrageously expensive and there is no way to tell when it will become cheaper if ever. Right now most people are content with inferior blacks so there is no impetus out there to change anything dramatically.

    Mind you, in order to fix the light leakage problem the thinking behind the design of Digital Technology must completely change. I do not have a clue how to fix this. 3-chip digitals will get you the same or nearly the same colors as the CRT, a bit better sharpness, particularly in the corners and comparable overall impression from the bright scenes, but this is where it ends. The fundamental engineering shortcomings that cannot be solved at this time will cripple the dynamic range of any digital projector out there regardless of the price.

    With this in mind our CRTs will continue to reign supreme since the CRT technology is the only one so far that has the dynamic range somewhat approximating the resolving ability of our eyes. The Digital Projectors do not even come close on this score."
     
  2. Roland @ B4

    Roland @ B4
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    For the less wordy.

    DLP's leak light CRT's don't, so they are better
     
  3. Vince M

    Vince M
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    :confused: :confused:
     
  4. crispybig

    crispybig
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    Less words, less clarity. :lesson:

    "DLP's leak light CRT's don't, so they are better".

    The object of the sentence is DLPs, so Roland is saying DLPs are better.

    But I'm darn sure Roland is thinking that CRTs are better.

    An alternative wording would be "DLPs leak light, CRTs don't, so CRTs are better".

    Just didn't want projectiondream to get the wrong idea.....

    (Unless Roland really has gone over to the grey side :rotfl: )
     
  5. Jonesthegas

    Jonesthegas
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    Phrasing hasn't always been Roland's forte ("bare with us").

    However, installing projectors is.

    Martin
     
  6. Roland @ B4

    Roland @ B4
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    Mistake noted :boring: :suicide:
     
  7. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Actually I think the mistake is to assume that CRT's are better because DLP's leak light......but lets not go there....it's been done to death.

    Gordon
     
  8. Vince M

    Vince M
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    Hence the reason for my question marks..perplexed? you will be? :D :D
     
  9. Vince M

    Vince M
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    Go on Gordon,let your hair down!..I mean we are in the crt forum after all..shouldnt we stand proud? :clap: :clap: :clap:
     

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