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Discussion Starter · #1 ·
In a recent thread Mark Hunter said this...

Quote:
IMO, you really need three separate primaries creating your color for best results. This only includes 3-chip DLP and D-ILA in the digital camp.

By itself, LCD isn't a 'three separate primaries' technology, although it can have very good colors in its own right.

Unless the projector has three separate chips, a polarized beam splitter, dichroic lenses and other advanced optics, it probably can't have three separate primaries. I don't know of an LCD projector that uses these techniques.
I already was aware that my technical knowledge is sorely lacking. But after reading this I now realize that I know even less than I thought. I've always had the understanding that the LCD projectors we're using do utilize three separate panels. If this is not the case I'm hoping someone will explain Mark's comments to me.


p.s. I'm purposely not addressing this question to Mark because he's hard at work putting the finishing touches on Dilard calibration and I don't want him to take time out from that to teach Kindergarten. http://www.avsforum.com/ubb/smile.gif


Bob Wood




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Discussion Starter · #3 ·
Now I'm thoroughly confused.

Didn't know Kindergarten was going to be this hard.


Bob


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[This message has been edited by RobertWood (edited 08-25-2001).]
 

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Bob, I think what we have here is just an honest mistake. My understanding is that LCD projectors have three panels. How many times have you read the spec for an LCD " 480,000 x 3" (for an SVGA LCD)to get the pixel count, multiplying the panels resolution times the number of panels, treating each primary as a stand alone source of resolution.


I wanted to add that I have no doubt Mark knows what he is talking about.


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[This message has been edited by Wireless (edited 08-25-2001).]
 

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As the above quote from Mark was based upon my posting pointing out that some LCD projectors were 3 chip/panel projects not just DLP and DILA, I too would like clarification on Marks comments. I have been operating on a simple (but perhaps wrong) assumption that the basic physics/design of the light engines and optics of 3 chip/panel systems e.g. LCD/dlp/dila systems were basically the same. A light source is split into primaries through a prism block processed by the R,G,B LCD/dlp/dila component, recombined and the little photons are sent through the lens to the screen. Where single chip/panel LCD/DLP systems shoot light through or off the chip/panel and out through the lens. With the only big difference being that a 1 panel LCD has RGB pixels like a very tiny laptop screen, whereas a 1 chip DLP projector requires frequency synched color wheels to produce strobes of red, green and blue.


Perhaps Mark is the only one who can truly elaborate on this and clarify if he just made an honest mistake in not knowing or forgetting about 3 panel LCD’s or if there is really something fundamentally different (other than the reflective nature of DLP/DILA) about the optics and light engine of 3 panel LCD system from its' sister 3 chip dlp/dila systems.


Bob as the originator of this thread, perhaps you can drop Mark a PM asking when he has the time if he would not mind coming over and clearing up the confusion.


Anyone seen the finger paint? Bob stop eating the glue.


Best Regards,


Brian


P.S. On a side note for those who have never seen inside a 10ht or the sanyo, if you look at Mike's great picture, the square in the center srounded by red green and blue is the prism block. Does anyone have a picture like Mike's of a 3 chip DLP or dila?



[This message has been edited by btmoore (edited 08-25-2001).]
 

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Discussion Starter · #6 ·
Quote:
Perhaps Mark is the only one who can truly elaborate on this and clarify if he just made an honest mistake in not knowing or forgetting about 3 panel LCD’s or if there is really something fundamentally different


I think you can bet your life on one thing, Brian. The chances that Mark Hunter does not know there are three panels in an LCD projector are going to be greater than tonight's Powerball odds (80 million to one). http://www.avsforum.com/ubb/smile.gif

So he's obviously talking about something other than just that.

I'll email him and see if I can twist his arm to come over here and explain to us what he meant.


p.s. speaking of the Powerball - if your ticket wins which projector will you buy?

I'll probably get a couple more AmPros. http://www.avsforum.com/ubb/smile.gif


Bob



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[This message has been edited by RobertWood (edited 08-25-2001).]
 

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Quote:
Originally posted by RobertWood:



p.s. speaking of the Powerball - if your ticket wins which projector will you buy?

I'll probably get a couple more AmPros. http://www.avsforum.com/ubb/smile.gif


Bob

No powerball in CA http://www.avsforum.com/ubb/frown.gif but if I were to win 200M, screw the projector just buy the local neighborhood IMAX. Then invite and fly in the rest of the Kindergarten class for a field trip. After that you would have at least 198.5M left over.


Regards,


Brian
 

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Sorry I've been missing this thread. The topic didn't catch my eye. Thanks for the heads-up, Bob.


Here's the good news...everybody's right!


As an MCT (software trainer) for years, I've used projectors for quite a while, and I had always used CRT or Single Panel TFT LCD projectors in my work. Color fidelity was never a big concern in that line of work.


Apparently, Polysilicon LCD is another class of LCD projectors that uses three panels to produce the image, instead of one.


So, the three digital technologies that use three separate primaries to produce the image are:
  • 3-Chip DLP
  • D-ILA (perhaps other LCOS projectors as well)
  • Polysilicon three panel LCD


There is some great (short) information on the topic of single and three panel LCD projectors here .


I would expect that all of the LCD projectors that get "recommended" on this forum fall into the Polysilicon LCD category. The color fidelity of Single Panel TFT LCD projectors was never very impressive.
 

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Discussion Starter · #9 ·
To everyone who is going to buy a Powerball ticket tonight.

There is actually one thing you can do to improve your wager. Choose only numbers higher than 31. Research has shown that most who pick their numbers are picking, birthdays, anniversaries, etc. (in other words numbers which represent days, months and years). Pick numbers above 31 to avoid days and months. That way should your number combination be drawn then statistically you will share the win with fewer winning tickets.


Bob


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[This message has been edited by RobertWood (edited 08-25-2001).]
 

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I just wanted to drag this further OT and point out another thing about lotto's (I love number games and calculus / number puzzles are a geek fascination that just makes me wish I had stayed straight and sober in my teenage years and not spent college in a technicolor daze http://www.avsforum.com/ubb/eek.gif ) which I never BTW play due to the fact that management fees make it a loosers gamble...


There is a wonderful story (and very good BBC documentary) about a time when the Irish (it would have to be) lottery was running a system that no one had truly statistically checked... A racing syndicate worked out that it was possible to cover the bets and guarantee yourself a win without staking as much as the system was paying out BUT... The physical act of placing so many numeretical sequenced bets, without attracting attention, was very difficult and the act of placing the bets became the gamble.. Being a racing syndicate and finding suitable 'risk based investors' they tried... at the close of the booths they had only cover 90 - 95 % of the bets and put millions of punt into the system but lady luck smiled and they took the pot without having to share... They made no secret of the fact that they had systemized (lose fingers in Vegas) and the population celebrated them as hero's...


I know this is way OT and probably not of interest to the many but the story of calculation and risk really touched me (plus I know the Irish personality well having descended from the blood pool and living there a few times) and I know how the tale sums up so many of the qualities I love of the emerald isle...


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[This message has been edited by Phat Phreddy (edited 08-25-2001).]
 

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Quote:
Originally posted by Wireless:

Bob, I think what we have here is just an honest mistake. My understanding is that LCD projectors have three panels.

I don't think Mark/milori is unaware of that. I think that he's saying that you can't get the best color unless the color source is split into three separate beams (usually R,G,B) and then have the light from each beam processed separately.


I don't know whether he's right that this doesn't happen with LCD's, and that on LCD's each panel has the full spectrum of light from the bulb passed through it while the panel absorbs the unwanted colors and lets the desired colors through. (Or maybe I've missed his point entirely.)


I'm not even sure why that method would necessarily result in less accurate color even if it was what 3 panel LCD's used. And I doubt whether it is what they do, since it would be very inefficient with lots of wasted light (like 1-chip DLPs) and unnecessary unless some design constraint (as with 1 chip DLP's) required it. -- Herb


After thinking about it (and reading BTMoore's post below) I can't see any reason for using 3 panels if you're _not_ splitting the light into three separate beams. It would just complicate the process, why not use a single panel if you're not splitting the light. . .




[This message has been edited by hsitz (edited 08-25-2001).]
 
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