How would you know? Are you sure? Would you notice if the CPU on your motherboard shifted 0.001 mm or raised one corner a few fractions of seconds of arc? I bet the chips on a typical circuit board do shift in relation to each other across a 60 degree F range enough to be optically detected. More to the point, I bet they shift a lot more in relation to the case, or maybe the hard drive.

Whether they shift an amount that is significant I couldn't say, but to say absolutely something is perfectly aligned (hint - not possible) and never moves is silly.



From the illustration on the DLP site I can see at least (1) variations in manufacturing the housing that holds the prizm and (2) variations in the prizm and (3) possible thermal shifts due to the housing expanding and contracting that could (actually will) happen. Now I've not examined an accurate drawing or done any math to see whether it's likely to be 0.1 pixel or 0.0000001 pixel error in the worst case, but error will be present due to unavoidable variations in manufactured parts.



This comment was intended with regard to the paragraph immediately preceeding it regarding color rendition. CRT phosphor fades (I'm told) as they age.



Actually the on/off nature of DLP is one of its' strongest good points to my mind, as accurate linear control of duration is simple compared to analog control of intesity.


[This message has been edited by charlie (edited November 22, 2002).]

As interested as I am in measurable and repeatable results I'm afraid I must decline your kind offer.

I really have to disagree on this one. I expect to see FP become more and more marginalized until at some point it will probably even disappear from theaters, if we still have theaters by then. There may be a short surge in interest if we see the price drop in the near future, but in the long haul (50-100 years) I expect it to go the way of the vacuum tube.

Most folks don't want to mess with it. My 'ideal 2D display' would be a paper thin and flexable direct view system.

If i was putting together my 'Ultimate CharlieWare Home Theater' (tm) I'd certainly use FP, but I'm not an average TV consumer either. Most folks have a life and don't want to bother with all that fuss.

C'mon Charlie,

You can't win a debate by getting into goofy definitions...

You said 3 chip systems must have convergence problems and they must have adjustments to the convergence.
This is wrong and I was just trying to explain to you why they need no convergence EVER. If you want to nitpick what I say (which was only meant to help you understand), then I'll just leave it at you're wrong about 3 chip convergence problems.

Now you ignore this FACT and get into some dim playing with definitions of the word 'perfect'. That's just sad you sink so low trying to make yourself feel 'right'.

"Whether they shift an amount that is significant I couldn't say, but to say absolutely something is perfectly aligned (hint - not possible) and never moves is silly."

Yes, nothing's perfect. DUH. At an atomic level everything's shifting. Thanks Mr. Wizard.

Let's stick with the'real world' aplication though ok?

My point remains unchanged... 3 chip systems have NO convergence adjustments, because they have NO convergence problems. This is 'perfect convergence' in 'real world' terms since you will never see the fringing error.

"Now I've not examined an accurate drawing or done any math to see whether it's likely to be 0.1 pixel or 0.0000001 pixel error in the worst case, but error will be present due to unavoidable variations in manufactured parts."

As I already said... if the original chipset is perfectly converged it won't change. Obviously flaws in manufacturing will happen.
Those flaws don't get used though (or you can tell a chipset's bad if it does get used). Either way, your 'point' is pointless and you're just grasping at microscopic straws.

Just admit you didn't know what you were talking about and drop the convergence subject. You were just wrong. Pick a new detail to debate (...and to be wrong about -heh).

You're right about FP's, but then I made those points a few posts earlier. At least give me some credit by saying you agree with me before you just reword what I write ok?

"Actually the on/off nature of DLP is one of its' strongest good points to my mind, as accurate linear control of duration is simple compared to analog control of intesity."

So?
You make this point after my quote about DLP vs. GLV which is also digital . My point was that GLV is a more advanced version both technically and mechanically.

If you want to relate DLP to analog like CRT then I'll say...
CRT despite being analog produces a wider grayscale than DLP can (though DLP is getting really close as of late).
It's my opinion an all digital system will be better than CRT eventually, but we're still not there yet, and once there we'll still have to wait for it to get cheaper than CRT so we're a long way off from the death of CRT.

"This comment was intended with regard to the paragraph immediately preceeding it regarding color rendition. CRT phosphor fades (I'm told) as they age."

I thought you were still talking about convergence. I'll have to re-read that post.

Anyway, yeah I agree that phosphors do fade over time. It's VERY slow and over looong time though.

So I supose you then think a one-chip DLP wins in this respect then?

Well DLP color isn't digital... What do you think happens to that spinning color wheel that's being bombarded w/ a super high power/burning hot lightbulb 100% of the time when running?

Do you think the color wheel won't fade from this? It does.

It may in fact fade more than CRT does. I don't know which is worse, but both degrade over time yet last long. The color wheel has no 'real world' advantage over CRT here.

Remember the DLP's bulb dims over time too (and isn't uncommonly known to 'pop' before it's rated hours ...something CRT almost never does).

And color convergence problems due to a one chip DLP system is why many people (note- I didn't say 'all' OR 'most') have problems w/ rainbows with DLP.

Of course zero people have rainbow problems w/ 3 color systems like CRT, LCD, 3chip DLP etc...

I'm not sure what you're looking for in a display. Maybe we should talk about that?

Or maybe take my $3K 65" Mitsu. You don't like CRT I guess..., so tell me what would you want to make this set better in your opinion?

And I don't mean just tossing around 'specs'. I mean talking about points that will actually result in a better display for hopefully a better price.

IMO, CRT vs DLP is kinda like in audio speakers debating dipoles vs. monopoles or cones vs panels or ribbons vs. domes.
None are perfect, and some of it is opinion/preference, but speaker for speaker you can get down to 'real world' details and debate which elements are better.

Thousandths or ten thousandths of an inch are important when each pixel in the device is about 0.001" square. One ten thousandth of an inch shift would be 0.1 pixel....

Or, to assure no more than 0.01 pixel of misconvergence the original alignment would need to be within 0.00001" and stay that close forever. Do you have any idea how small that is? I'm not sure how much misconvergence one can see, but I suspect it falls somewhere between these figures.

[The pixels on an HD2 device are actually smaller than 0.001 by almost half IIRC]

I'm not here to win a debate. I'm here to discuss topics of interest. Maybe that's the problem.



Wrong! Nice strawman, although a bit rushed. If you work into it more slowly you can sometimes get them to bite before you burn it down.

What I said is:



Which is true. I've not seen any proof otherwise. If the system is carefully manufactured it my be a vanishingly small problem, but I don't know, nor do you, apparently. If you do, how much is the typical 3 chip DLP misconvergence? An answer of zero is the same as you don't know, BTW.



Not just at an atomic level. It is not uncommon in systems that have lots of thermal cycles to suffer stress related failures on the traces, devices and sockets. There is tremendous research on newer, lower coefficeint of expansion cicuit board materials for some classes of applications. Have you ever worked with really precision optics? I'm not talking small format SLR camreas either. I suspect the part of the board where the light hits the chips gets quite hot .... but who knows for sure? TI I suppose.



How many 3 chip DLP systems have you viewed. More to the point, how many have you serviced? Can you even cite a source?



Dunno - if I tried to answer I'd be guessing. Cite your source.

FWIW I never said the color wheel was a better solution - look back over the thread. I said they both have potential issues and I'm excited to see which is better once the technology matures. The reason (and I agree it's true) CRT has the lead at this moment is simply decades of R&D and millions of unit experience. It is about as good as it will ever get, and one or more of these emerging technologies will surpass it in the relatively near future.



Do you know what color misconvergence is? It's not the source of the rainbow phenomenon. Unless you're somehow redefining color convergence as something applicable to the temporal domain.



I have a RP CRT and I like it fine. I don't mean to hurt you feelings about your set - I'm sure it's better than what I'm currently using. Feel better?

I also drive a car with a gasoline powered internal combustion engine, but I'm not touting it as the future of powerplants, either.

BTW - I find your condescending attitude childish. I'm sure you're better than that, probably just having a bad day. Have a drink or two and enjoy your HT.


[This message has been edited by charlie (edited November 26, 2002).]

You're not the first or last to say this. Cope with it.

"If I were a betting person I'd bet the DLP theater systems have a convergence adjustment (maybe even a mechanical one) somewhere."

This is exactly what you said. This is exactly what I meant by you're wrong.

"I'm not sure how much misconvergence one can see, but I suspect it falls somewhere between these figures."

Well, again... you 'suspect worng.
Like I said... lets' stick with the 'real world'.
3 chip systems look perfectly alligned to everyone. Ask around. There's millions of LCD projector owners out there. And lots of 3 chip DLP theaters across the country.

"I'm not here to win a debate. I'm here to discuss topics of interest. Maybe that's the problem."

If we disagree on an issue and we try to make points about how we're correct and the other isn't then we're 'dabating' these issues.


quote:
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You said 3 chip systems must have convergence problems and they must have adjustments to the convergence.
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"Wrong! Nice strawman, although a bit rushed. If you work into it more slowly you can sometimes get them to bite before you burn it down."

I answered this in my post above.

"Which is true. I've not seen any proof otherwise. If the system is carefully manufactured it my be a vanishingly small problem, but I don't know, nor do you, apparently."

But I do know. I've told you over and over that all LCD projecotrs are 3 chip systems and no one has any problems with convergence. That's the 'real world' proof.

"If you do, how much is the typical 3 chip DLP misconvergence? An answer of zero is the same as you don't know, BTW."

Ooooh, a 'trick' question. hehe. My answer is -"Less than the human eye can perceive at any normal viewing distance". If you say that's not 'perfect' enough for you then you're fooling yourself or trying to fool me.

"How many 3 chip DLP systems have you viewed. More to the point, how many have you serviced? Can you even cite a source?"

You've already made it clear you have NO experience with these systems so why challenge me when you couldn't pass your own challenge???

I certainly don't need to service any DLPs to make the points I'm making. You're just being silly now.

I've seen several LCDs and the 3 chip DLP system that floats around the local theater chain. Zero convergence problems to the human eye at any normal distance.

You'll see pixel gaps before you see color fringing -since I actually walked up to the theater screen to look at the pixel structure out of curiosity and there was no color error.

quote:
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Well DLP color isn't digital... What do you think happens to that spinning color wheel that's being bombarded w/ a super high power/burning hot lightbulb 100% of the time when running?
--------------------------------------------------------------------------------

Dunno - if I tried to answer I'd be guessing. Cite your source."

The color wheel's plastic film. There's no plastic that can withstand this level of heat and light without fading over time.


quote:
--------------------------------------------------------------------------------
And color convergence problems due to a one chip DLP system is why many people (note- I didn't say 'all' OR 'most') have problems w/ rainbows with DLP.
--------------------------------------------------------------------------------

"Do you know what color misconvergence is? It's not the source of the rainbow phenomenon. Unless you're somehow redefining color convergence as something applicable to the temporal domain."

I was trying to put it into simple terms that a color wheel causes color rainbow problems for people. This 'seeing color where it shouldn't be' could be called a diff. kind of color convergence problem though diff. from the 3 color overlay issue we've been talking about. Not too hard to understand it you tried.


quote:
--------------------------------------------------------------------------------
Or maybe take my $3K 65" Mitsu. You don't like CRT I guess..., so tell me what would you want to make this set better in your opinion?
--------------------------------------------------------------------------------

"I have a RP CRT and I like it fine. I don't mean to hurt you feelings about your set - I'm sure it's better than what I'm currently using. Feel better?"

Who's calling who childish and condescending? You must be joking. That last remark was as bad as anything I've written. I don't claim to be a boyscout, but you can't make that 'high road' claim either.

I also don't claim my set's the best display imaginable. I certainly loved the picture of the HD DLP FP's I've seen (though still had some minor rainbow problems). I saw a 3 chip LCoS JVC FP's that looked amazing.

"BTW - I find your condescending attitude childish. I'm sure you're better than that, probably just having a bad day. Have a drink or two and enjoy your HT."

See my comments above. P.S.... I don't drink, but hey whatever you need to help get you through your day. -heh

quote:
--------------------------------------------------------------------------------
You're right about FP's, but then I made those points a few posts earlier. At least give me some credit by saying you agree with me before you just reword what I write ok?
--------------------------------------------------------------------------------

"You're not the first or last to say this. Cope with it."

My point was that I just posted these ideas in this very thread only a few posts before you. That's very diff. from me claiming I was the first person to ever think of these points, but you'll twist whatever I say to try to make a defence.



[This message has been edited by azryan (edited November 26, 2002).]

Supposing they probably have adjustments (what I said) and saying they must absolutely have adjustments are two quite different things. Can you see that?

Your assertion:



vs.



and



Also, be aware that adjustments can often take the form of an added step in 'final assembly' in the making of precision systems, which then become a potential area of re-adjustment later.

As I noted above, I doubt even modern manufacturing finds locating multiple devices in relation to each other with tolerances less than 0.0000055" (0.01 pixel error on HD2 chip) easy or simple. Magnify the need for precision by projecting the beam a few inches from a PCB to an prism/lens/etc. and the level of precision required is incredible.

Could it be done? Probably. Will it be done on a practical high volume of units scale? Tough to say.

Just out of curiosity, how big physically are the actual optical parts of LCoS and LCD devices?

Again, I'm not being intentionally combative, I just want constructive dialog.

OK. So must the convergence error be greater than 0.1 to be visible, or are errors smaller than 0.01 visible? You really didn't add any useful info here.