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Hi-Def CRT displays???

Discussion in 'Televisions' started by 00fjackson, May 4, 2005.

  1. 00fjackson

    00fjackson
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    Hi-Def CRT display?

    When HD hit the UK I will be looking for an integrated HDTV CRT set. I know that there might not be many but there is a market for them in the US and surely a few will filter through to here. Anyway, the reason I am set on a CRT is:

    1) Better picture than any flat panel display- it will probably take five years for LCD to catch up.
    2) Can display interlaced material as interlaced (i.e. not line doubled) at 100Hz as well as progressive frames at 50Hz. :smashin:
    3) Can display 4:3 material without processing.

    My one concern is the horizontal resolution. Of course it will be able to scan 1080 vertical lines, but after looking at US models, I am not sure whether they have the full 1920 columns of physical phosphors (i.e. 1920 RGB strips.) I know that this is not as important as vertical lines but still I would not like an HDTV which cannot display full HD if I could buy an LCD where I know the resolution (soon we will have 1080*1920 LCDs and at least we will know it!)

    If anyone knows the answer please post. :thumbsup:

    P.S. Sorry if this has been asked before.

    P.P.S. Out of interest does anyone know how pure flat CRTs avoid ‘pincushion’ effect? :confused:
     
  2. Nick_UK

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    Samsung have announced that they are to be selling slimline hi-def TV's this summer, if that's any help. You can see what they are like by looking at Samsung's US web pages.
     
  3. Welwynnick

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    The JVC HV-36P38 and smaller brothers will fit the bill, but it only has HD component inputs, no HDMI / DVI / HDCP compatibility, but that's no showstopper. It does support the full 1920 x 1080 resolution. All CRTs have to have lots of complicated geometry corrections to give a straight picture. Plasmas and LCDs are still slightly better in this one respect, but CRTs are good enough.
     
  4. NicolasB

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    At present there are no properly HD-compatible CRT TVs in the UK at all. The nearest you'll get is something like the JVC set mentioned above - but it only accepts 1080i (it can't do 720p) and it also doesn't have any HDCP-compatible digital inputs, so you probably won't be able to use it with Sky HD or HD disc players at all.
     
  5. 00fjackson

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    Thanks but I know there arn't any in the UK yet. My question was about the horizontal res. of U.S. soon to be UK sets.
     
  6. Quickbeam

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    Can display interlaced SD material at 100Hz. I will be surprised if we ever see CRT TVs that can display 1080i at 100Hz.
     
  7. Pooon

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    I bet that they are not going to be priced the same as the US versions though :mad: i saw one of the 36" version for sale @ bestbuy(iirc) for $999. Even if you change the $ for £ i think we'd be lucky.
     
  8. Stephen Neal

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    AIUI only one of the Sony range of CRT HD sets on sale in the US claims to be able to fully display the 1920 horizontal resolution of 1080i source material.

    The current Sony DRC sets on-sale in the UK are effectively partially HD sets internally. They support 576/50i input only and then offer the choice of conversion to 576/100i or 1152/50i (both of which have the same line-rate - which is a significant factor in CRT design)

    I wouldn't expect any HD CRT sets to support 1080/100i - as this has the same line-rate as 1080/50p - twice that required for 1080/50i or 576/100i (which is close enough to 540/100i to be sensible)

    I don't think you will see any HD sets on-sale that can display 576/50i material as 576/50i - as this would require a CRT system that can cope with a 2:1 difference in line-scanning rates - which is much more difficult to engineer.
     
  9. Wilt

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    There is no 36inch model in the US, only a 32inch. Have a look at the Samsung website.
    Home Cinema Choice states the Euro version will cost £600, and won't display HD due to it's limited resolution, and also the HDMI input has been dropped.
     
  10. Pooon

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    My mistake, it was one of these TX-R3079WH that i saw advertised, and it is clearly a 30" not "36. doh!
     
  11. Welwynnick

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    I have a CRT which I believe can display 1080 x 1920 progressive at 50 Hz. Like to know what it is?

    It's a Sony monitor with enormous horizontal refresh rate and RGB bandwidth. I can't sit too far away, and it needs a good PC or scaler to drive it, but I bet it gives the best picture around.

    BTW, the big JVC DOES resolve 1920 columns interlaced.
     
  12. Hopkins

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    Yeah, it annoys the hell out of me that the TV industry is so lazy. Maybe there is a good reason why the fantastic CRT technology that is now so cheap in computer monitors just doesn't seem to be reflected in the TV industry? I have a two year old Iiyama 19" monitor with a mitsubishi tube that can handle 1600x1200 at 100Hz and costs a little over 200 quid now.

    Which leads me on to another question: why can't we seem to find Mitsubishi TVs in the UK? Their tubes are great!
     
  13. NicolasB

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    It's simply a matter of size. To be able to accurately steer an electron beam to high-def resolution across a screen with a 36" diagonal you'd need a tube 3 and a half feet long, and the TV would weigh about 200 pounds. A 50" screen would need a tube 5 feet long. The typical consumer cares much more about having a TV that doesn't take up much space in the living room than he cares about the quality of the picture.
     
  14. Hopkins

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    Haha, fair enough! Yes, I think even I would be concerned about those dimensions. Even my 19" monitor is bloody big and heavy - and that's way too small to be a TV in a medium sized living room.
     
  15. 00fjackson

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    Great, do you know what model? Why do you think only 1 or maybe it's the only one labled as it. Supposedly the others don't metion res. if they ain't got nothing to boast about and its not expected (unlike LCD/plasmas). I clouldn't see any evidence of 1080i on the JVC mentioned but seen as it does 576/p its practically the same scan rate so likely it does. How does it handle 50i inputs? I couldn't see 100Hz- must line double- stupid?

    I'm not an expert but I'm sure they can aproximately double the scan rate from 576/100i or 576/50p to 1080/100i or 1080/50p? And the real reason I want 100Hz interlaced is because it will come with 1080/50p (fixed scan rate)- they are the same, as you point out.

    As I've said I don't expect a muli-scan display- it would upscale SD/50i to 1080/100i. I didn't mean display in native res., just as native interlaced.

    P.S. Anyone got an explanation of pure flat CRT tube tech? :smashin:
     
  16. Welwynnick

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    The horizontal scanning frequency is one of the most significant performance parameters for a display. TVs only manage about 15.6 kHz, or 31.4 kHz for prog scan displays, which a limitation on picture quality. Move up to CRT and panel monitors and projectors, and this figure can increase to over 100 kHz - but you have to pay for it. It's not just a question of tweaking a clock.

    Flat screen TVs are not what they seem. Apparently the internal surface of the screen is still curved, and the scanning electronics have lots of non-linear compensation to correct the effects. That's why there there are so many service adjustments, and why they sometimes get it wrong.
     
  17. 00fjackson

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    Well if they doubled the scanning speed for 576/50p / 576/100i / 1080/50i then hopefully they will again for 1080/50p / 1080/100i.

    Can't believe it so there is not such thing as a flat picture from a CRT? Oh well the flat screens look flat and the PQ is awsome.
     
  18. Welwynnick

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    Yup, it does work. I've got a Sony 36FS70, and it's still the best TV picture ever. If you want even more scanning speed, just get a big multiscan monitor like 33" or 37" Mitsubishi or NEC.
     
  19. 00fjackson

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    Sorry, what do you mean by more scanning speed? 567/50i double to 100 Hz? or even higher- if thats doubled its enough for 1080/50p!

    Do you have the model of those multi-scans? And can Stephen Neal supply the model of the US CRT which claims true 1920 h-res.?
     
  20. Stephen Neal

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    Bit hazy at the model name - it was a US 34" Sony XBR series ISTR. They made two versions - one was brighter, but softer, with the lower luminance version had a finer dot-pitch and was 1920 capable?

    If you do a search on the AVS Forum site in their direct view CRT section I suspect there will be a lot of talk about it if it is still current - that is where I read about it a little while ago (2004?)
     
  21. Abit

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    They are the four Super Fine Pitch models that start with KD-.......

    http://www.sonystyle.com/is-bin/INT...-Start?CategoryName=tv_hdtv_tube&Dept=tvvideo
     
  22. Frank2

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    An integral part of the CRT tube is the shadow mask. This is a thin metal sheet with tiny holes. There a 3 holes per pixel (One for each of the primary colours). These holes are round on a standard tube and rectangular on a Sony CRT. The rectangular holes cover a larger area than the round ones (This is the reason why the Sony CRT appears to be brighter). As a result of these larger rectangles there is much more "hole" than metal sheet in the Sony CRT. Therefore the Sony CRT shadow mask requires support by 2 thin horizontal metal wires. These are placed 1/3 from the top and 1/3 from the bottom. Anybody with a Sony PC monitor can see these wires when a bright white is displayed. They can only be found in a TV but are less evident.
    It is this shadow mask that gives the CRT its true maximum resolution.
     
  23. Stephen Neal

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    Hmm - what about PIL tubes as used on non-Sony SD sets? Certainly Picture In Line tubes were common on Philips 4:3 sets in the 80s and 90s. Round dot shadow mask designs were most definitely on the way out by then - have they returned?

    The Sony Trinitron tube design does pre-date PIL tubes by a long time - and has continued to be employed by them - as you say with universally visible support wires. These seem to be more visible on the Trinitron PC monitors than TVs - but I think this is because PC monitors running Windows often display full-frame white whereas TV images are more varied.
     
  24. Frank2

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    As far as I can remember, the sony crt was invented later. The patent has only expired 10 years ago or so.
    Philips and the like (I guess they will never adopt the sony crt!) still employ the original crt design (3 round dots per pixel). You only need to look close at a white area to see the dots.
    Shadow masks are still part of all CRTs. The reason is that electron beams stray from there intended path (Unlike laser, they also get wider as they travel farther) and would otherwise affect the neighbouring pixels.

    TVs tend to have a bigger CRT than most PCs. The glass is therefore much thicker too. Perhaps this affects the visibility of the supporting wires.

    From next year, all electronic products in Europe have to be lead-free to comply with CE law. This also includes the CRT glass (Lead is used in the CRT glass to avoid exceeding safe radiation levels). I don't know what will happen to large CRTs when this becomes law. Perhaps an incentive to manufacturers to put more emphasis on lcd and plasma screens.
     
  25. Stephen Neal

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    Yep - I understand the basic physics of colour CRTs - I just disagree that all non-trinitrons use dots.

    The Philips TVs we owned in the 80s didn't have 3 round dots per pixel - they had stripes.

    The difference between shadow mask and trinitron style tubes isn't stripes vs dots, it is how the "masking" is performed. Trinitron tubes use a mesh of wires (themselves supported by wires), whereas shadow mask style tubes use a metal perforated sheet. This sheet (and the phosphors associated with it) can be formed as triad dots or triple stripes - and the 80s Philips sets we had (the last ones before we moved to Sony TVs) - all had strips rather than dots.
     
  26. Abit

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    The Sony Super Fine Pitch models I linked to above have like three or four wires holding the mask (grille) just in case anyone may be interested. The lines are really tiny compared to standard trinitron tubes. They put out the best picture I've seen from a crt tv.

    I believe Samsung is introducing some new HD crts with with an equally smaller mask.
     
  27. 00fjackson

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    Firstly, this is right. The only difference I can see is that the grill allows more horizontal resolution on smaller TVs. However the support wires on Trinitron monitors are damn annoying.

    After looking up the two Sony XBRs mentioned by Stephen Neal, it seems that the earlier one to come out (the 910) was the highest ever res. But was surpassed in '04 by the 960 which has 1400 phosphor stripes.

    So, they aren’t there yet but I’m sure it’s not that hard and won’t be too long now. (those new samsungs maybe?).

    As for 1080/50p scan speed- well if the depth of tube doesn’t increase from 567/50i to 576/50p (or 100i or 1080/50i) then why should it when they double the speed again?

    Anyone know why LCDs cannot display native interlaced? Surely they can handle various speeds?
     
  28. isko

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  29. Stephen Neal

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    Tube depth isn't the only issue - there is also the whole electrical infrastructure - such as EHT supplies, flyback transformers etc. Also there is the issue that the faster you move the spot, the less time there is for the electron beam to excite the phosphor, and thus the image will either be dimmer, or you'll have to run the electron beam at a higher energy level to deliver the same brightness as a lower line-rate tube ?

    "Pixel based" displays - such as LCDs, Plasma, DLP etc. can't display interlaced material as interlaced, as unlike CRT displays, the scan lines can't be made to overlap - so the "missing" lines in each field would appear as black lines and be very visible. (There is also the issue that Plasma and DLP don't run at the field/frame rate of the broadcast material - they run at higher field/frame rates internally - for colour wheel / sub-field greyscale reasons)

    CRTs work differently both horizontally and vertically. Horizontally they employ a continuous scanning motion - rather than jumping from phosphor triplet to phosphor triplet in lumps, so the relationship between source samples and phosphors isn't as direct as it might be between source samples and LCD/DLP/Plasma "pixels" on a panel display. Vertically CRTs designed for interlaced material usually employ scanning spots taller than a single display line (though the centre of the spot is brighter than the edges so it is a more "analogue" effect), so that the lines of one field don't have black lines between them in the same way that a pixel addressed panel would.
     
  30. 00fjackson

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    Awesome if those 2 TVs above have 1080/50p scan speed- they are no deeper than normal sets. So we almost have the resolution, got the scan speed- almost there to the ultimate CRT!

    Yes, I can see that the power to the electron beam must increase for faster scan speeds. Sorry, I never realised that interlacing, effectively line doubles in the simplist possible way! So does that mean that if the shadow mask is for progressive (1 phosphor per scan line) it cannot do this properly? Or if the shadow mask is interlaced it screws up the progressive image? If so, digitally line doubling and then scanning at 1080/50p should be better than 100i on a progressive display (and with each pixel getting direct 'excitement' twice it should be an equal quality image), but 100Hz should be better on an interlaced display because the overlaping scan lines will mess up the image.

    Unless when scanning progressively the beam focusses sharper to stop the overlap? Then you can run both properly on an 'interlaced' shadow mask? :confused:

    Anyway thanks guys thats kinda answered my question.
     

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