LCoS, HD-ILA, SXRD, Bulb Life, 3LCD?

Discussion in 'Displays' started by BrianTwig, Jun 28, 2006.

  1. BrianTwig

    BrianTwig Second Unit

    May 1, 2006
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    In the past I have been 100% against an RPTV. They just didn't do it for me, and I disliked strongly the 'off angle' viewing of them. Be it DLP, LCD, or old school CRT. I hated them.

    But recently JVC's HD-ILA and Sony's SXRD versions of LCoS have really caught my eye and I am giving them strong consideration for my upcoming TV purchase instead of a plasma.

    Here is my question/concern on the LCoS based systems.

    I have read repeatedly (but often in old articles and reviews as finding recent ones on LCoS is proving difficult for me) that the blub life on LCoS systems is pretty darn short (like 2,000 hours). Best case scenario for me, that would be all of one years viewing if it didn't crap out early on me.

    Is this correct that LCoS bulbs are running about 2,000 hours? If I am incorrect, what is the avg lifespan on these bulbs?

    Does JVC and/or Sony have any new generation TVs in the pipeline with much longer bulb life, or switching to an LED source as some LCD manufactureres have to eliminate the color wheel? And yes, I know the LCoS does not have a color wheel.

    Also, is there a substantial difference between LCoS and 3LCD? What is 3LCD and how does it differ from regular LCD? How about compared to LCoS?

  2. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

    Mar 16, 2000
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    Calgary, Alberta
    Real Name:
    Michael Chen

    The bulbs in front projector systems are rated in the 2000 to 3000 hour range.

    The bulbs in RPTVs are rated in the 6000 to 8000 hour range. They don't have to be nearly as bright as the FP units.

    YMMV though ... since how you treat the set affects the bulb life. Too many on /off cycles will reduce the life ... poor ventilation ... ditto ....

  3. Allan Jayne

    Allan Jayne Cinematographer

    Nov 1, 1998
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    As far as I know, 3LCD is simply another term for what we know as "just" LCD in an RPTV or FPTV. There are three of the little film frame sized panels and the light beam is split three ways to go through the respective panels and then recombined to continue on to the screen.

    LCoS works the same way as as projection LCD except that the liquid crystals are on a (LCD panel sized) mirror and the light has to pass through them twice on the way to the screen thus doubling the contrast ratio. LCoS also has three panels.

    LED/DLP offers more image formation time than "regular" DLP since there is no wasted time when a boundary between colored celliphanes on a color wheel is traversing the light beam and all the pixels have to "be black". The result is greater achievable brightness and possibly less dithering. Dithering occurs because gray on DLP is achieved by fluttering the micro mirrors.

    All RPTV's these days have a "rib pitch" analogous to the dot pitch of direct view CRT. Depending on how fine it is, it could make a noticeable difference in the resolution of HDTV shows.

    Video hints:
  4. Leo Kerr

    Leo Kerr Screenwriter

    May 10, 1999
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    One of the big advantages LCoS has is that its fill factor is much higher than conventional LCD or DLP. Less screen-door-effect for just about anything else.

    Second advantage to LCoS, they've been making 1080 panels for a long time, now.

    I would believe that "3LCD" is a marketing gimmick, for those who don't like color wheels on DLP displays.

    And trust me, right now, you don't want to even pretend to use LEDs to drive any sort of front or rear-projector. I've actually got one of the Mitsubishi DLP/LED projectors on my desk at work. It's great for some things, but not that you'd ever want to watch anything on it! (It's really a "road-warrior" type thing for doing small Powerpoint demos.)


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