What is LCOS?

Discussion in 'Archived Threads 2001-2004' started by alan halvorson, Jun 8, 2002.

  1. alan halvorson

    alan halvorson Cinematographer

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    I've been out of the display game for a few years and now I want to upgrade to a front projector. My situation won't allow for a CRT. I have pretty much eliminated DLP. That leaves D-ILA, LCD and a new projection technology called Liquid Crystal On Silicon (LCOS).
    1.) What is it?
    2.) What are the advantages/disadvantages?
    3.) How does it compare to other digital front projection technologies in performance, reliability, etc.?
    4.) What are some good examples? I see HomeTheaterProjection.com lists some Hitachi's in my price range. These any good?
    5.) Got any recommendations for LCD in the $5,000 or less range (although I might be able to go $6,000 if the improvement is worth it)?
    6.) Alternatively, if I go cheap, what are my best options under $3,000?
    Thanks
     
  2. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    1. D-ILA is JVC's branded name for LCOS, just like Kleenex is Kimberly-Clark's own brand of tissue paper.

    2. Advantages are just like D-ILA. No rainbows, excellent colors, >93+ fill rate. D-ILA projectors do use Xenon bulbs though, which tend to not change color temperatures over their lifetime. LCOS (hitachi's at least) use UHP, which don't have quite the same color stability. On the flip side, the bulbs are cheaper and longer lasting.

    3. Performance is very good. Colors are excellent. Contrast on 12 degree and HD1 DLP units is still better. Fill rate is extremely high.

    4. Hitachi makes one, and OEM's it for Dukane. Christie Digital also makes one they call the Digital Red. Hitachi's is very good, though they have some issues with the blacks being a bit purplish/blue.

    5. The Sanyo PLV-70HT should be out soon. It should be 2200 ANSI lumens, 900:1 contrast, and 1366x768 resolution. Specs aren't set it stone, and may change. This may be a good choice. Other than that, I can't think of a better choice than the Hitachi.

    6. The new BenQ may be a good choice. It's much like the Infocus LS110 (dual res DLP chip, 848x480 and 800x600).
     
  3. alan halvorson

    alan halvorson Cinematographer

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    Excuse my projector ignorance - what are "12 degree and HD1 DLP units"? What is fill rate (I think I can guess what this means but I want to know for certain)?
     
  4. Allan Jayne

    Allan Jayne Cinematographer

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    Fill rate: How much the active part of the pixel fills the space allotted for it. The gaps between the active areas of pixels account for the "screen door effect".
    LCOS (I believe) Instead of light shining through the LCD panel like a transparency, the LCOS has the LCD material on top of a mirror so light is shined onto the panel and it reflects off the mirror behind to continue through the optical system. Contrast is better because the light has to go through the crystal on the mirror surface twice.
    Not to be confused with DLP which instead of crystals has tiny mirrors that physically swing back.
    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  5. Jay Sylvester

    Jay Sylvester Supporting Actor

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    I'm also looking at the Hitachi CP-SX5500W (that's the LCOS model they rebadge for Dukane). It seems that the latest batch of them has greatly reduced the purplish/bluish blacks, and with a 20cc green lens filter, it practically becomes a non-issue. Pair a 5500 with green filter and an anamorphic lens, and you have a fine home theater PJ.

    Jason over at the AVS forum is running a powerbuy on these right now. You might want to check it out. There's tons of info in their hi-end projector forum on this model. People really like it over there. I'll be buying a PJ within the next week myself, and it very well may be the 5500.
     
  6. alan halvorson

    alan halvorson Cinematographer

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    So, it seems the Hitachi 5500 is a good choice. Is it a better choice over a similarly priced LCD or DLP?

    What would a green lens filter cost and how difficult is to fit/align?

    How does this "anamorphic lens" work? How difficult is it to mount/align? How would I switch between anamorphic/non-anamorphic sources (I watch a lot of laser discs and full-screen stuff)? Anything else (other than, of course, a screen, cabling and ceiling mount) needed or suggested?

    In other words, I want to know the full extent of what I would be getting into, if I went this route (which sure isn't a given at this point).
     
  7. Allan Jayne

    Allan Jayne Cinematographer

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    An anamorphic lens is what commercial theaters use for anamorphically shot or printed films. It is fitted over the exposed lens barrel of the projector manually and the picture is projected as stretched sideways. The anamorphic picture then appears correct.

    If the overall picture is a bit purplish, a greenish cellophane placed over the lens will correct it.
     
  8. Jay Sylvester

    Jay Sylvester Supporting Actor

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    Have you ever seen an anamorphic DVD played back on a 4:3 TV without the 16:9 squeeze engaged and the DVD player set to 16:9 mode? The image is stretched vertically. When played back on a 4:3 projector, it would look the same. An anamorphic lens takes that stretched image and corrects its aspect ratio so everything appears normal. The advantage to this kind of setup is that you use the entire pixel resolution of the projector instead of wasting resolution on the "black bars."

    There are two primary contenders in the anamorphic lens category at the moment: Panamorph and ISCO. The Panamorph takes the image and stretches it out, increasing horizontal width while maintaining the original height. The ISCO compresses the image vertically while maintaining the width, also shortening the throw distance of the projector in the process (the Panamorph doesn't affect throw distance). The lenses are mounted inside casings that sit in front of the projector. The lenses aren't cheap. Even used lenses run close to $1000, so you have to decide whether or not the increased resolution justifies the higher cost.

    As Allan said, a green filter helps suppress purple tints. They aren't expensive (as little as $15 for a cellophane filter). Hitachi is actually releasing an attachment in the near future with a filter. They originally designed the 5500 for business use, and apparently business PJs that are going to be hooked up to computers look better with a blue push to them. They had no idea so many people would be interested in the 5500 for home theater usage.

    I'd very much like to get an anamorphic lens with the 5500, but the extra grand is a bit tough to swallow. Even without the lens, the resolution of the 16:9 rectangle at the middle of the 4:3 panel is still as high as any other projector (1365 x 768 I think). The extra 300 or so lines probably make a significant difference though.

    I'd suggest you visit the AVS projector forums. They have enough background info there to keep you busy for some time. You'll discover--as I did--that buying a projector takes a lot more research and forethought than any RPTV ever would.
     
  9. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    The 12 degree DMD units are new. With a higher tilt angle (most are 10 degrees), less light that should have been rejected ends up hitting the screen, giving you better contrast.

    The new HP XB31 has a 12 degree DMD chip and thanks to that (and some other optimizations), they were able to get 1800:1 On/Off contrast, something previously only hit by CRT units (and some custom tweaked units).

    The HD1 chip is TI's 1280x720 native resolution chip. Contrast tends to be good on these as well, something in the area of 1000:1 to 1200:1. TI just released their new HD2 chip, but it's supposedly just to reduce costs. Manufacturers will, no doubt make improvements in their projectors, and when we see them equipped with the HD2 chip, they'll probably have better colors and higher contrast.
     
  10. alan halvorson

    alan halvorson Cinematographer

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    Ok, Jay - I understand (I've known about film and video anamorphic for quite a while - no explanation needed as to how or why). I just didn't know how an anamophic lens attached to a front projector worked.

    But, once again - if a projector is set up with an anamophic lens in front of it, what is most commonly done when non-anamophic sources are viewed? What I mean is, is the lens moved out of the way, is there an adjustment on the lens that says "don't stretch" or "don't squeeze" (depending on the lens)? Or do people just not watch non-anamorphic sources on these projectors? If it isn't recommended that the lens be moved, and there isn't an adjustment, that pretty much rules out the projector with an anmorphic lens out for me, and maybe rules out the projector altogether.

    Thanks for the AVSForum tip - I have been visiting there for about a week now. It's a lot of stuff to wade through and try to understand and it's going to take a while to become knowledgeable.
     
  11. Jay Sylvester

    Jay Sylvester Supporting Actor

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    For non-anamorphic letterbox sources, you have two choices. The easiest option is to simply slide the lens out of the way. I think the ISCO comes on a rail that lets you slide it back and forth. Not sure about the Panamorph. For this to work with 4:3 sources (like a TV show or a Kubrick film), you'd need a 4:3 screen. For 16:9 sources, the image would occupy the center of the screen with the top and bottom having blank space. Keep in mind that your 4:3 image size will be much taller than your 16:9 material, and some people find that this diminishes the "wow" effect of watching movies on the big screen.

    The second option is to leave the lens in place all the time and use some type of video processor (like an outboard scaler or HTPC) to convert the image. For non-anamorphic letterbox sources, such as older DVDs and most LDs, the processor would remove the "black bars" and stretch the remaining portion of the image, then upconvert that portion to a higher resolution. The net result would be a stretched image like an anamorphic DVD, which the lens would then correct.

    I'm not exactly sure how you'd handle 4:3 sources in this scenario, but I'm guessing it involves manipulating the source so that it's distorted in a way that the lens is able to correct.
     
  12. alan halvorson

    alan halvorson Cinematographer

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    Thanks for the replies - very helpful. Just one more question: Is the Hitachi (and others of the ilk) worth the hassle? Do they output enough of a better picture than a comparably priced DLP or LCD to make them the choice among digital projectors?
     
  13. Jay Sylvester

    Jay Sylvester Supporting Actor

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    Depends on what criteria by which you judge the competition. LCOS projectors have a higher fill ratio than DLP or LCD, so for the most "film-like" image they're hard to beat. From just a few feet away, it's difficult to make out any type of pixel structure. DLP is good in this regard also, while LCDs are the worst (the phenomenon is typically referred to as "screen door," and minimum viewing distance for LCD PJs is usually 1.5 to 2 times screen width).

    The latest DLPs have better contrast ratios than LCOS or LCD, so blacks will be darker and shadow detail should be better. DLPs also have dead-on flesh tones from what I hear. However, there is the dreaded rainbow/headache issue that affects a very small percentage of users, so you should definitely sit in front of one for at least 30-60 minutes to determine if you're susceptible to this problem.

    I haven't researched LCD PJs much, but if I recall correctly they tend to have very bright, bold colors. Don't quote me on that though. I did just see Panasonic's new LCD-based RPTV at Best Buy, and it was razor-sharp with eye-popping color. I could make out the screen door though.

    Even if you don't get an anamorphic lens, a 5500 with a green filter is still one hell of a projector for the money. I'll probably be jumping on one myself.
     
  14. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    The newer MLA equipped LCD's have come a long way in terms of fill rate.

    D-ILA's are up above 93%. DLP's tend to be about 85-90, and MLA equipped LCD's are about 80-85. LCD's without this technology, especially older LCD's, have downwards of 60-75% fill rate.
     
  15. Jay Sylvester

    Jay Sylvester Supporting Actor

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    Just a quick update. I mixed up the functionality of the two lenses. The Panamorph compresses vertically while maintaining the original width, while the ISCO stretches the image out horizontally maintaining the image height. Sorry about that.
     
  16. alan halvorson

    alan halvorson Cinematographer

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    Again, expressing my projector ignorance - what is MLA and can anyone give me some examples of projectors that use it? How about the Sony VW11HT (which I recently was exposed to for a very short audtion and was mightily impressed with)?
     
  17. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    MLA is short for Micro Lens Array. It increases brightness and decreases screendoor for LCD type projectors. Actually quite a few LCD projectors use it now.
    Although Sony doesn't say for sure (their spec list is absolutely horrid), I don't believe the VPL-VW11HT uses MLA technology:
    Sony VPL-VW11HT
    The older VPL-VW10HT definitely does not:
    Sony VPL-VW10HT
    The 1.3" WXGA 1366x768 LCD panels in the VPL-10HT are used in the Sanyo PLV-60HT which does not use MLA. Sanyo decided to ditch Sony with their upcoming PLV-70HT (proposed specs: 2200 lumens, 900:1 contrast, 1366x768 res) and buy MLA equipped LCD panels from Epson.
     

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