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Discussion Starter · #1 ·
A question has come up in several threads. Why would a 3-chip DLP RPTV cost more then three, single-chip DLP RPTV's? Here's a theory I thought of. It is just pure speculation.


A digital micromirror device (DMD) is an array of n x m mirrors. The TI Mustang chip is 1280 x 720 mirrors. In order to get acceptable convergence from a 3-chip RPTV, each of the three mirrors at a particular pixel position must align closely. This alignment must happen at all pixel positions. If the manufacturing process for DMDs has a lot of variability in mirror-to-mirror spacing, you will have a hard time finding three DMDs where you can get acceptable convergence at each pixel position.


For existing 3-chip DLP front projectors, the manufacturer might be doing some kind of DMD binning process to get matched sets of devices. The "yield" for alignable 3-chip DMD families could be very low. This results in a very high price for a 3-DMD matched set.


It's just a theory.
 

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Hhhmm... Interesting theory mrock12. Another possibility is that it is not just the spacing but also the tilt. The "on" angles for all three would have to be very similar. But this should be important for single chip DLP systems too (for uniform brightness across pixels) and they seem to have that licked.


And semiconductor fabrication is extremely precise, so...


Maybe the real reason is economics, not engineering. Not many people will buy a TV that costs 3xDLP, so the sweet spot to maximize profit turns out to be a higher price than 3xDLP.


I would also like to know what TI is charging for these DMDs. It is probably a lot since they are the only supplier. There might be enough of a markup to make yields not really a factor on price.


Maybe LCoS technology will force them down in the coming years.


Just thinking out loud.


Sooke
 

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Having worked in the semiconductor manufacturing business (for TI no less, but not in their DLP group... just down the street though), I seriously doubt it's a precision issue, at least not in the chip manufacturing arena.


More likely it's a combination of optics and demand... what's the demand for a $20-30k FP system? Or a $10k+ RP system? Not much. So you have to bump your prices up, often by a considerable margin, in order to make it worthwhile to manufacture.
 

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Profits come from volume more than margin. Sure no one wants to buy a $10k RP but I bet everyone who spent $3-$5 on a Dlp and probably all of the people who got LCD's would've bought a 3-chip tv if it was comparibly priced. Sell more for less not the other way around.
 

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There is virtually no demand among the Samsung buyers for 3 chips instead of 1. They make more money, selling more units with fewer DMDs.
 

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How much would a 3 chip DLP FP cost relative to a 3 chip DLP RP? If its similar, I'd rather get the former.


BTW, where'd you get the information that 3 chip DLP RP systems costs more than 3 times that of 1 chip DLP RP's? Did anyone make a prototype?
 

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Quote:
Originally posted by arkid
Profits come from volume more than margin... Sell more for less not the other way around.
Can be true, but certainly not always. Profit from volume is driven by overhead cost absorption. If your costs are fixed, then more volume spreads the costs better and allows for more profit per unit. If, however, your capital investments are a step function of your volume, then more profit may not always be realized. You would then have volume "sweet spots". If your costs won't allow you to price such that you hit that next sweet spot, you could do yourself more harm than good. It is a fine juggling act.
 

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My understanding is the challenge is the light path. Remember that DLP is just a reflector and has to dump the light when a pixel is "off" someplace. With a three chip design you not only have to pack the chips close together for alignment so this limits how to dispose of the excess light.
 

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Discussion Starter · #9 ·
ConceptVBS,


I've heard of no prototypes. There was just some speculation in a couple of threads about what the price would be if a 3-chip DLP RPTV were produced.


Rogo,


There are a lot of people that are very happy with the 1-chip DLP from Samsung and others. But then, there is also a market for the 3-chip LCD and 3-chip LCOS products that perhaps could be eaten into if a manufacturer were to produce a 3-chip DLP. I might be tempted to go with a 3-chip DLP if it had better PQ than 3-chip LCD or a cheaper price than 3-chip LCoS.
 

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3 Chippers would be hard, but not impossible, to do in a RPTV setup. I think the light leakage issue is keeping this setup in the commercial applications on bigger screens. The only 3 chip designs I have seen, have all been designed for very high output, so a 3 chip design for RPTV application would be more scaled down. Maybe with some refining of LCOS, they will be motivated to offer a better product. I don't understand why we all don't have 3 chip native 1920X1080 Progressive displays for our center pieces. Or at least a 70" native 1080P Plasma (Go Samsung). And until the technology comes down even more, they should all be given price caps of 2K, so there is still enough money left over for you to have me come out and calibrate it.
 

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Seth, you are right it would be hard. The light path of 3-chip DLP is the most complex of any projection technology that currently exists.


Also, the primary advantage of 3-chip DLP is light output -- not a huge issue on existing models (though I find the 61" Samsung wanting). 3-chip offers a lower contrast ratio than 1-chip.


And with HD2+ to mitigate dithering, there is really only a limited benefit to doing this.


It absolutely costs more than 3x a 1-chip model to do a 3-chip model. You pay more for the chipsets from TI and you have to build a much more complex light path. That colorwheel may be "archaic" but it offers simple elegance.


Certainly, if 3-chip LCOS is ever proved commercially viable in RPTVs, then TI would indeed react. But in the meantime, they are finally making it plausible for the $25,000 3-chip DLP projector to be real. And those things are huge....


Holding one's breath is not recommended.


Mark
 

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Quote:
Originally posted by rogo
There is virtually no demand among the Samsung buyers for 3 chips instead of 1. They make more money, selling more units with fewer DMDs.
There is no demand because there is no product. It's Hobsons choice.
 

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I have been forunate enough to have worked on many 3 chip DLP's. Can you imagine $30K.....that was just for the anamorphic lens. Most 3 chippers are 5X4 aspect. I'm not sure if they have released a 3 chip HD2 yet. But at this point, I am expecting to see a native chip very soon.
 

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3 chip DLPs spell relief for the minority of users who do see rainbows. I see them all the time. The 3 chip systems are expensive now because the economies of scale are not here yet. The chip itself is very large compared to an IC, and they have no problems aligning the masks of an IC so thats not an issue. As for the light path - equipment like modern autofocus SLRs with eyeball tracking technology are just as sophisticated but are quite affordable. I think over time, LCOS and DLP and Plasma will displace all CRT sets. 3 chippers might be within range of most enthusiasts.
 

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* The light path is not in common at all with a modern SLR. No SLR has three different light sources that are created from one lamp where it has to reflect back the light part of the time and dump it part of the time.


* The demand is miniscule, even if products emerge. Virtually no one has problems with the 1-chip products -- especially among RPTV buyers.


* The plethora of new products at CEDIA with 3 HD2 DMDs still didn't result in any of them being at all inexpensive.
 

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Quote:
Originally posted by rogo


* The demand is miniscule, even if products emerge. Virtually no one has problems with the 1-chip products -- especially among RPTV buyers.
Rainbows?

Especially among RPTV buyers.
 

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Discussion Starter · #18 ·
Quote:
Originally posted by rogo
* Virtually no one has problems with the 1-chip products -- especially among RPTV buyers.
Somebody must be having a problem with 1-chip DLP, otherwise why are people buying 3-chip LCD with screen door and inferior blacks and 3-chip LCoS at a much higher price?
 

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Arkid: Go shopping for these for awhile. Talk to salesman and customers. Ask how many see rainbows.


Mrock: Well, those 3-chip LCDs are either (a) much less $$$ per inch or (b) branded Sony. So far neither of those factors convinces me that the 1-chippers have problems.


As for 3-chip LCOS, it's better. It has higher resolution. Oh, and it's not for sale at any price.
 

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Quote:
Originally posted by rogo
Arkid: Go shopping for these for awhile. Talk to salesman and customers. Ask how many see rainbows.


I did shop for one, for months. Guess what, I never saw rainbows. I tried hard but never could, I wanted to be sure I wouldn't if I was going to buy one.

The very last time I went to CC to check out the new Panny & DLP side by side before I dived in I saw them, after all that time. I wasn't even trying to see them but I did so I went with the other tv.


The question is though....

Are you going to seriously argue that they don't exist after the millions of posts in this forum from people that have seen them?



(by millions I mean lots, before you jump on me)
 
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