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PJ Fundamentals

Discussion in 'Projectors, Screens & Video Processors' started by stuart-f, Sep 28, 2001.

  1. stuart-f

    stuart-f
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    It would appear that there are 4 main projector technologies, CRT, LCD, DLP and DiLA, (there maybe others but I haven't seen them mentioned here). Now, in relation to absolute picture quality there seem to be a general consenus that CRT is the best.

    The question that I am interested in is:

    Is CRT better because it is fundamentally better or is it just that it is a mature technology while all of the others are relatively immature?<br />Or will one or more of the other technologies catch up and perhaps beat CRT?

    (I have a Sony VPL10 and while I still enjoy using it my memories of the Cine7 at the event still haunt me) <img src="mad.gif" border="0">
     
  2. Roland @ B4

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    LCD requires light to be shone through and DLP and DILA reflect off their medium. <br />At present they all have problems achieving a reduction in light sufficient to call Black. This reduces the contrast (the difference between black and white measured as a ratio)

    An immense amount of R&D is being thrown at these technologies to improve their short falls and we are seeing improvements all the time.

    CRT as a technology is as you say well established. It has one clear advantage over the other technologies in that it starts black and creates light by making phosphor glow. The level of low light gray available in CRT is far better than the other technologies.

    When studios perform the transfer of film to Disk it is graded via a high quality (though you might question that for R2) CRT monitor. People watching on a CRT television buy most DVD’s. It follows the most accurate colors will come from a CRT device. In fact that is the colors the digital technologies are trying to recreate.

    But get the crystal ball out and see where this is going to go in the future. <br />LCD with its comparatively low contrast and slow response is never going to become the standard for future projection. CRT has to die just by it sheer size and production techniques, already key manufactures have pulled the plug and would rather go for the mass production routes.

    <br />This leaves DLP and DILA. Only time will tell already DLP is well established and has made some great progress. My feeling is to watch DILA carefully a number of the big names like Runco have announced products based on DILA. It has the possibility to achieve much higher resolutions and in theory higher contrast levels. It comes from a company JVC that understands video. Rather than a calculator company (I know, I know)

    My personal feeling is that we will see loads of DLP boxes using the same engine. (Very few companies can buy just the chips from Texas Instruments) but with different electronics and varying build and image qualities. Then we will see a few low-end DILA projectors and some pretty fancy high end ones, which will give top end CRT a run for its money.

    CRT produces the image closest to film at the moment but stay tuned.
     
  3. Nic Rhodes

    Nic Rhodes
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    Well I will attempt to put my 2 p worth forward. I started looking at all this at Christmas last year, I have done many demos, most have been a waste of time, some have been very fruitful. I have learned much about the different technologies and have gone into them in depth. I am a research engineer by profession so I always like to know how things work and appreciate good engineering. I am not pro or anti technology, and I sell no products.

    Re picture quality<br />CRT is best and will be for some time yet. I think this all down to bandwidth and the analogue nature of the device. Analogue technology is CRTs biggest strength and it's biggest weakness. CRT is a mature technology but it is also a successful technology. High bandwidth devices are available over 100MHz are easily possible, some up to 200MHz in the domestic market. A quality analogue signal will very closely resemble the actual source signal and will therefore look better. A poor signal however will look terrible. I see lots of similarities here with the turntable vs CD debate. A properly set up turntable nearly always beats a top CD player. I currently have a top CD player, which is about to have a major upgrade, which may make it the best CD player I have ever heard. Currently it is number two, by a very short margin. My turntable betters this performance, so I think I can speak with some conviction. I suggest we avoid any debate on vinyl vs CD for this thread.

    When set up a CRT can look stunning. Any CRT in a pub will show you that it can also look terrible. It is therefore down to how you do it. Anyone at the event will know CRT ruled the roost re picture quality, however for most people domestic / design considerations are more important but here as an engineer I am concentrating on the engineering behind picture quality.

    CRT quality can go from very poor to stunning. It is analogue.

    LCD is starting to become a mature technology. I think that it's lower pricing will mean it will dominate the lower end of the market. The Sanyo PLV30 is an excellent example of this. Generally it is a relatively low-resolution device and is now approaching a stable period of evolution / manufacture. It goes up to 1365 x 768 in the domestic markets.

    DLP (DMD) and D'ILA have some technical advantages over LCD, primarily down to the fact they reflect rather than transmit light. None produce light, unlike CRTs. The first domestic wide-screen panels are now coming in these technologies, at. 1350 x 800 or 1000 ish. Technically these devices are better than what we have seen previously from panel display deices but still can't compete the quality end of the CRT market. They are bettering the cheap CRTs however (interlaced only CRTs below the Ellie). D'ILA has demonstrated some much higher resolution panels in the professional arena and I expect these can compete with top CRTs.

    On a more practical note I have high hopes for the new Sharp I think Jeff is getting and the Sim2 300 as being excellent devices re picture quality, but also small, portable etc. £6k to £10k worries me though. However long term I think they will need to push the resolution a bit further for the ultimate enthusiast projector, say 1800 x 1200 or 3 x current DVD resolution. Higher resolution panels than this will just show up the limitations of the current low def material we have in the UK. At 4k x 2k panels you see the film grain anyway!. Long tem D'ILA looks particularly impressive and I see this as the better of the panel based technologies. However the only example I have seen to date looked crap! Technically it is an impressive solution however. I think of D'ILA as light reflected off an LCD rather than transmitted through an LCD.

    Panel projector quality is more consistent in quality than CRTs but perhaps doesn't reach the same heights as CRTs. It is digital. An all or nothing technology.

    I personally look forward to the day with a panel projector can match CRT at an affordable price, we will all benefit. My money is on D'ILA but I think it will &gt; 5 years yet. Hey I still buy many records for similar reasons.<br /> <img src="biggrin.gif" border="0">
     
  4. simoncope

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  5. Roland @ B4

    Roland @ B4
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  6. Jeff

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    Roland,

    I hear that Barco are moving into the Single chip DLP home theatre market, have you seen any prototypes yet?

    Jeff
     
  7. Jagular

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    Hi Stuart,<br />I would like to congratulate Nick on a superb explanation of current display technology.<br />The only comment I can add is on pure observation, and that is, CRT when given a pure signal gives the nearest to the truth, the whole truth, and other technologies lie in a most convincing way.<br />In other words, edge effect on a CRT is w.y.s.i.w.y.g. Warts-an-all.<br />Convincing though it is, LCD etc. looses this edge information due to its digital structure (uniform over each pixel). Although the higher the pixel count, the less this becomes obvious.

    Jagular
     
  8. Roland @ B4

    Roland @ B4
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    Barco have anounced a intention to build a single chip DLP they showed a prototype in germany recently. I would expect to see something 4th Qtr this year. 16x9 chip 1000 ansi lumens. but a few clever things with processing that will make it a bit different. Like all Barco product it will never be low end.

    They have also decided to announce a plasma too. Can't help feeling that train has already left the station.

    High band width in CRT can be a big problem. 70 mhz is about max you could ever need for HDTV. but how do you measure it? Across the RGB amplifiers? Over the whole circuit.

    The sooner these DVD transfer houses find the off button for Edge enhancments the better.

    [ 29-09-2001: Message edited by: Roland@B4 ]</p>
     
  9. stuart-f

    stuart-f
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    Thanks guys for all the info. It seems that if I go the CRT route next year, (assuming I can muster the finance and get the wifes approval), I am unlikely to feel that I am missing out on some newer and better technology.

    Gordon has posted some comments here and there about wide-screen on CRT and he seems to have some reservations about this. Is this because heavy wide-screen use means that the top & bottom of the lens is burnt less and can result in an uneven picture when watching 4:3 material, (please excuse the flimsy grasp of the technicalities)? Also how long on average do CRT tubes last? (This has probably been answered before but without the search facility things are a bit tricky).

    On a more specific point, i.e. the subject of costs, Roland you said that a Cine7 with LimoPro was about £10,000 - where does that price come from? The price list I got from Barco was nearer £11,500. What about running the Cine7 with someone elses scaler, e.g. vigatech or quadscan?

    Cheers.
     
  10. Guest

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    some crts like the barco cine 6 and 7 can manipulate the picture to any format, with a crt with this capability you can have a 14x9 screen which is a comprimise you can fill the screen with a 4x3 picture you would lose some information top and bottom , and for 16x9 you would lose some information on the sides this would give more even use of the tubes it works very well in practice
     
  11. Roland @ B4

    Roland @ B4
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    As soon as you display and image on a CRT projector the phosphor is being worn away little by little. In an average HC setup the tubes will decay to about 50% of their original light output at about 7-10,000 hrs (it will still be a stunning image) <br />(There's Scary stuff for LCD chaps below too.)

    I think the warning that Gordon and I have tried to give out in the past is by using multiple aspect rations which most modern CRT’s are able to do You can end up with some areas of the tube face wearing more than others. As most of your display material for HC will be wide screen this should not be a problem. The amount of good quality 4x3 is diminishing so rapidly now that it should not be a problem soon.

    One of the joys that LCD manufacturers and even their owners take in slamming down CRT is tube wear. Little do they realise that the polarizing filters within their devices are made of an organic material that when put under ultraviolet light will decay. (one of the best sources of Ultraviolet light is at the back of the projector trying to get through). Put up a white field on an older LCD and look for the tell tale yellowing in the center.

    No technology is perfect yet !.

    (Oh put a DLP projector is pause (blanked for an hour) and ask where the other 50% of the light went for next two whilst it recovers) put the lens cover on rather than making the mirrors do the work.

    Another thought about lamped machines is that as the lamps loose their brightness, which they do very qickly from new then slow down, the colour temperature changes. so will your overall colour balance.

    My aim is to get the best possible image out of any device things like the above keep me awake at night.
     
  12. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Roland: Good morning...I spent the last 20 minutes writing a huge explanation about tube wear if using a 16:9 screen to display 4:3 material and how this is what stops me using a 2.35:1 screen myself. Of course, the damn PC bombed out as I posted it....Oh well.. You did the job for me.

    The only other comment I would make is that you can trash a CRT tube very quickly through misuse. I know of one UK shop who had to replace every tube in their dem unit after leaving a DVD menu on screen over a weekend.....oops!
     
  13. Roland @ B4

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    Gordon wish you had I didn't think mine explained it as well as I had it my head.I'd be intereseted in your thoughts on Callibrating lamped devices do the need doing every 100/500/1000hrs

    stuart-f <br />You are quite right about UK list price for Cine 7 with LiMopro at @ £11,156.63 inc vat.

    of course if you wanted one.... <img src="wink.gif" border="0">
     
  14. Nic Rhodes

    Nic Rhodes
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  15. gwbailey

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  16. Roland @ B4

    Roland @ B4
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    Woah chaps be careful hear. <img src="graemlins/evil.gif" border="0" alt="[Evil]" /> <br /> <br />I'm happy to help on tech questions on Barco's and CRT's etc as best I can.<br />Most of know what I do for a living and I'm gratefull to all the forum members that have bought from me. (I'm esspecially greatful to the ones who thought my jokes were funny - both of you).

    Please don't expect direct pricing. - send me an email.

    But to answer a generic how much should I budget to mount my CRT projector?

    Between £500 and £2000. Depends on what is included in that price. <br />Things like ceiling mounts, cables, strengtening, equipment hire all have to be taken into consideration. Do cables have to be hidden? Is the projector to be calibrated? Does the price include a follow up visit to align the projector once it has settled in?
     
  17. Roland @ B4

    Roland @ B4
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  18. Nic Rhodes

    Nic Rhodes
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    Roland

    I entirely agree with your calc and thinking, I was coming at this from a HCPC / CRT problem I am trying to better understand at the moment.
     
  19. Nic Rhodes

    Nic Rhodes
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