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Discussion Starter · #1 ·
You must correct me if I am wrong, but isn't dilas history in the presentation and simulation market?


In these markets I guess the most important design parameters are brightness and resolution. Less attention must have been focused on contrast and black lever.


In this thread I found an interesting discussion on the possibility of increasing the contrast of lcd and dila based projectors.

http://www.avsforum.com/avs-vb/showt...ght=polarizers


Now there are tweaked projectors based on DILA technology aimed at the home theater market, but my accusation is that they are not designed for it. The technolgy has just been somewhat adapted to better suit the home theater market.


Who is spending research dollars to apply DILA or LCOS for the home theater market from the ground and up so to speak, anybody?


To me the JVC QX1G is a simulation projector that happens to be a decent projector for d-cinema.
 

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Quote:
Originally posted by Ohlson
You must correct me if I am wrong, but isn't dilas history in the presentation and simulation market?


Now there are tweaked projectors based on DILA technology aimed at the home theater market, but my accusation is that they are not designed for it. The technolgy has just been somewhat adapted to better suit the home theater market.
Ohlson,


It's not the chip design that determines whether the projector is a capable HT projector - but the calibration.


The D-ILAs in their many incarnations, are very good HT projectors when calibrated.


The G-series D-ILAs are not sold as HT projectors, but as business presentation projectors. To this end - these

projectors are calibrated by JVC to give maximum light output.


However, that's not what you want for a HT projector - you want one where the 3 primary colors have been balanced.


Fortunately, JVC provided a calibration table - the so-called "gamma curve" table. The D-ILA projector takes

the input signal and then looks up what voltage to apply to the D-ILA chip in the "gamma curve" table.


Because of this - master D-ILA calibrators like William Phelps and his associates, or Cliff Plavin can turn a G-series

D-ILA into a very impressive HT projector.


JVC didn't design a HT theater projector - they did better. They designed a projector that is versatile enough to be

either a presentation projector or a HT projector.


Dr. Gregory Greenman

Physicist
 

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Discussion Starter · #3 ·
I recognize that the dilas are great projectors for home theater, I am merely wondering if they could not work more on the contrast ratio.


In a white paper in a thread about laser-dila JVC outlines the history of the technology and talks about the future with e-cinema. In a diagram they seem to work towards a contrast ratio of 1500:1. After that the diagram displays a flat line showing no future development with regards to the contrast. Do you think they will work towards achieving 1500:1 and then be satisfied, should they be satisfied? What is the physical limit for the contrast ration of dila designs, assuming super chips, optics and polarizers and filters?
 

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Quote:
Originally posted by Ohlson
I recognize that the dilas are great projectors for home theater, I am merely wondering if they could not work more on the contrast ratio.


In a white paper in a thread about laser-dila JVC outlines the history of the technology and talks about the future with e-cinema. In a diagram they seem to work towards a contrast ratio of 1500:1. After that the diagram displays a flat line showing no future development with regards to the contrast. Do you think they will work towards achieving 1500:1 and then be satisfied, should they be satisfied? What is the physical limit for the contrast ration of dila designs, assuming super chips, optics and polarizers and filters?
Ohlson,


When talking about contrast ratios, one has to be careful.


You can talk about the contrast ratio for the chip itself - however, there's more to determining the contrast ratio of

the projector as a whole than just the chip.


The design of the whole optics block comes into play. The chip may try to make a given pixel "black", but the light

energy has to go somewhere - and often it finds its way to the screen anyway. Often a 1000:1 contrast ratio chip ends

up in a projector with a 500:1 contrast ratio, or lower.


You also have to look at what the contrast ratio of the software you are trying to display. The camera that shot

the movie doesn't have infinite contrast ratio. The digital data on the DVD has a certain bandwidth. Additionally there's

also the limits to what the human eye can perceive.


Pretty soon, further improvements in the chip technology is just "gilding a lilly" - you can make enhancements, but they

don't result in true improvements because of other factors.


JVC set their target at 1500:1, which sounds reasonable.


Dr. Gregory Greenman

Physicist
 

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Mattias,


To add another factor...different manufacturers weigh the accuracy/bragging rights ratio differently. Some of them are very conservative in their specs, and others use a "best case scenario" set-up that is actually not possible in an actual installation, and their specs become mostly marketing fodder.


JVC is in fact extremely conservative in their specs. The popular G15 projector has a contrast spec of 350:1, but can actually do double that. Considering the conservative spec history of JVC, it will be interesting to see what the 800:1 spec on the SX21 can actually do.


I have other projectors here that are the opposite...no matter what you do to them, they absolutely can not be coaxed to even meet (much less exceed) their spec.


Just another factor to consider.
 

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Discussion Starter · #6 ·
In the white paper mentioned above, JVC talkes about a sequential contrast ratio of 1330:1 using lasers with dila modulators. What is meant by the term sequential contrast, how does it differ from the usual full on / full off?
 

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I've seen some 3 chip DLPs that are rated at 400:1 but appear better than some of the 1 chippers I've seen rated at over 1000:1.


I have little faith anymore in the CR spec except for marketing hype.
 

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Quote:
Originally posted by Mark Hunter


JVC is in fact extremely conservative in their specs. The popular G15 projector has a contrast spec of 350:1, but can actually do double that.
More than that, even. I just Optimized an M15 that achieved 812:1, with NO filters! Best blacks I've seen in a D-ILA so far, reminded me of the early production G15's that hit over 700:1. Sure wish I could figure out what was different about this one...


William
 
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