Why such poor resolution on HDTVs?

Discussion in 'Displays' started by John Royster, May 9, 2003.

  1. John Royster

    John Royster Screenwriter

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    I've been really curious about this. If we have cheap computer monitors that have a whole slew of sync rates and can display pixel perfect 1920x1080p and higher then why can't HDTVs do the same?

    For less than 600 bucks you get a 21" HD monitor with every sync frequency imaginable. But if you want a 32" HDTV with far less resolution then you're paying 1800?

    How about CRT based projection tvs? Thousands of dollars and they still can't do 1920x1080 interlaced.

    DLP, LCD and plasma are all very cool technologies but they have the same problem in most are 1200x768 at best. 10 thousand dollars or more for what is essentially 1980s resolutions.

    Can anyone the factors behind this? My numbers might be a little off but I'm sure you will get the point.

    Thanks in advanced.
     
  2. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    It's called light output.

    Regards
     
  3. DaveF

    DaveF Moderator
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    The cost and difficulty of manufacturing the vacuum tubes (for direct-view sets) increases significantly with size.

    I was recently talking with a guy who previously worked at a Sony manufacturing plant. He said a glitch occurred in the 36" tubes during one run, and so they exploded (imploded) when the vacuum was being pulled. This caused the destruction of a number of the tubes and a lot of damage to the manufacturing equipment.
     
  4. Allan Jayne

    Allan Jayne Cinematographer

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    The CRT's in CRT projection TV's (both front and rear) are typically 7 to 9 inches diagonal. Especially with the 7 inch size, the electron beam spot cannot be made as small as 1/1920'th the screen width whcih you need to really do 1920x1080.

    Next, to maintain convergence to within 1/1920'th the screen width is difficult and therefore expensive to provide.

    For RPTV's the fine ribs on the screen surface impose a limit on horizontal resolution.

    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  5. David Lorenzo

    David Lorenzo Stunt Coordinator

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    Texas Instruments has already demo'd next gen DLP chips that have slightly more than 1920x1080 pixels. I'd imagine products arriving sometime next year.

    The only restriction I can think of with plasmas would be cost and maybe lower yields. Once prices fall more I think some full resolution panels will show up. Light output shouldn't be a problem for a big plasma screen.

    There are CRT FPs that can achieve full HD res, but they are very expensive. Allan hit the high points as to why CRT RPTVs are limited in resolution.

    Sony's new direct view sets coming out this summer should have higher resolutions than any other direct view as of yet, but it still doesn't support 720p native. I couldn't even guess when crt direct views will be able to do 1920x1080 fully. Besides PC monitors of course.
     
  6. Allan Jayne

    Allan Jayne Cinematographer

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    Compared with 1080i, beam spot size is less critical for 720p (1280 x 720) but bandwidth of the electronics is more critical, 37 MHz needed. For comparison, 480p needs 13 Mhz. For computer monitors, 1024 x 768 non-interlaced, nearly 720p, has been around for a long time. I don't see any reason why ordinary TV sets can't be made to do 720p native other than skimping to reduce costs. Drawing 1080i on the screen is not much more difficult than 480p if we are not concerned with small details running into each other. Total prevention of the latter in 1080i also needs 37 MHz for electronics and a much finer electron beam spot and, for direct view, a finer shadow mask.
     
  7. Todd Alexander

    Todd Alexander Stunt Coordinator

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    I am researching this forum and other areas for info on getting an HDTV. I am still not yet sold on anything quite yet. I will say however, my Dell 17" flat panel, which can be bought now for about $450 is an AWESOME way to watch DVDs. The color is rich, the resolution is very accurate and a lot of detail is visible that is normally lost when watching DVDs on my 35" Mitsubishi TV (CRT). The large screen I have is nice and all, but nothing like the computer flat panel. To me, that is the standard I would like to measure things to. The only weakness is that it is only 17", so you have to sit just a foot or two away. I would hope within a year or two you could get a flat panale of same/better quality in a 45"+ version for ~ $4000. That to me would be the ultimate HDTV.
     
  8. Max Leung

    Max Leung Producer

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    I've seen a CRT front projector that fully supports 1920x1080p (yes, progressive scan). 9" CRTs, 5 feet long, and retails for $120,000 CDN.

    Go pick one up John, tell us how you like it. [​IMG]

    The picture it produces is stunning. It was mated to one of the best video processors I've even seen. It looked better than film, and better than any monitor I've ever seen. It was rear-projected onto a 100" diagonal glass screen that is worth the price of a small car. I couldn't see any fresnel structure.
     
  9. DaViD Boulet

    DaViD Boulet Lead Actor

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    CRT 1080P, as others have mentioned, requires excellent and accurate electonics which usually = $$.

    HOWEVER,

    1080P *digital* displays, like Plamsma, LCD, DLP etc. don't really need anything more than their 720P brothers already have. What has been keeping most 1920 x 1080 digital dipslays off the market so far are 2 things:

    1. manufacturing yelds go down as 1920 x 1080 has more than twice the pixels of 1280 x 720...and so is more prone to defects.

    2. manufactures just don't "get it" that 1080P is where we should all be.

    Having said that, get ready, because in about a year you will have a HOST of full 1920 x 1080 digital display options.

    Sony will be coming out with SXRD (their version of LOCS) at the 1920 x 1080 level for both front and rear projection. Sanyo and other companies will be offering LCD front/rear projection displays that will be full 1920 x 1080. I'm sure in no time we'll have some Plasma and direct-view options that go the way of 1920 x 1080 as well. TI has demonstrated a 2.35:1 aspect-ratio chip with 1080 res but it's intended only for professional projection (it will probably be a few years before we see a consumer DLP machine priced < $10K that does 1920 x 1080).

    Keep the faith. 1080P displays are coming and they're coming fast. I'm waiting. I made a vow that my first digital front-projector would provide 1920 x 1080 resolution and so it shall...

    -dave [​IMG]
     
  10. John Royster

    John Royster Screenwriter

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    So its about the precision required in the cathode ray tube itself coupled with "need more light"?

     

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