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CRT TV versus CRT computer monitor

Discussion in 'Televisions' started by Chris Hedlund, Feb 14, 2005.

  1. Chris Hedlund

    Chris Hedlund
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    I was ranting on in another thread about all CRT TVs being imperfect in some way with convergence, geometry etc etc.
    It then occured to me that I sit looking at a near perfect CRT monitor all day on my computer. In fact its rare to find a poor computer monitor even cheap ones - and all this from just 18inches away :cool:
    Why cant the manufacturers use this technology in TVs or is it all about cost?
     
  2. GreenBars

    GreenBars
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    Cost is proportional to size. Computer monitors are usually small (rarely bigger than 19") and 4:3 in shape. A 32" 16:9 CRT built to computer monitor levels of quality would be prohibitively expensive (and sizewise would be much deeper). Better to buy a plasma or LCD.
     
  3. sambobo

    sambobo
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    monitors also work in a compleltley different way to tvs too, thats why you can change the res and refresh rate on a pc monitor
     
  4. Laurel&Hardy

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    Well no that's not strictly true.

    Essentially they both do the same thing - fire electrons at a phosphor coating. It's how it's done that makes them different. A TV works at a standard horizontal frequency of 15.625kHz for it's line resolution. This can be changed, and in the US you can get multi scan TV's because they have HD broadcasts already. However, there's no real point in the UK because our TV system is PAL 625 interlaced, so there's nothing to be gained out of increasing the scan frequency or resolution - we're stuck with the signal system we have and that is the real limiting factor at this time. The 100Hz trickery attempts to get around this but as many of us know this has limited success, and a sizeable number of people actually hate it.

    A monitor on the other hand refreshes much higher and, for the most part, scans in progressive mode - it's very rare now to see an interlaced resolution on PC's. So the horizontal frequency is much higher, in the case of my Iiyama VM Pro 454 it's 132Khz. This requires far higher standards of electronics to control. Also the hardware is capable of driving these higher resolutions - a modern graphics card will refresh at 1600x1200@100Hz easily, but remember there's no colour system to drive - it's all done digitally.

    In theory you could make a TV to monitor standards - there is no reason in electronic terms why it can't be done. It would cost a lot of money though, and that is the only reason why it will never be done. Better to buy a plasma...well that's subjective. But it's irrelevant anyway because you will never see a commercial large screen CRT TV built to monitor standard.
     
  5. red16v

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    Hi, you ask why crt computer monitors have better convergence/geometry (and purity) than a conventional crt tv ?. The answer is quite straight forward. PC crts are much longer than the equivalent "screen size" tv crt. This means the electron beams are deflected much less than on the equivalent screen size tv crt and therefore all these factors are not only less prevalent but easier to correct. So, the answer is simple - less beam deflection from the centre axis, smaller screen size = better geometry, convergence etc. If you were to produce a large screen size conventional tv crt to the same relative dimensions as a PC crt it would be much larger than the current models - probably much too large for the average front room. Regards, yt.
     
  6. Laurel&Hardy

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    Yes good point, most CRT's for TV use are about 102.5 degrees or something. Monitors are 90 or 95 degrees max. A 36" tube based on monitor specs would be well over 2 foot deep before it went into a cabinet!
     

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