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Discussion Starter · #1 ·
I have a Rock+ video processor and I use the bottom of the 4:3 panel of my JVC G-15 for a 16:9 image, primarily to work around a dead pixel in the top portion of the 4:3 panel. Is there a way with Dilard to turn off the top pixels that I am not using? I thought I saw references to mods that turned off certain pixels, but I don't remember a mod for this configuration. Does anybody know if this is easy to do?
 

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Smitty,


If you're not using the top third of the panel, those pixels are already "turned off". Dilard won't do anything more than your Rock+. Having said that, calibration (Dilard or professional) will lower your black level, which will make those unused pixels darker. Presumably you are bothered by the light spill above the screen. The 100% solution to this problem is an anamorphic lens (although you'd have your dead pixel back).


- Chris
 

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Hi Smitty,


Chris said it pretty well. If the Rock is putting out "black" in the blank areas, and the projector is projecting that black, that's about the best you can do.


On the other hand, if the source is putting out "dark gray" (like many DVDs do), turning off the pixels could allow you to decrease the luminance in those areas. Since the projector's lamp still outputs some light through the "black" pixels, they are not really completely turned off. I wish that it was possible to do this, but it isn't.


It sounds like you are already there.


Mark
 

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Discussion Starter · #5 ·
Thanks for the replies. The light spill is the only issue, as I have a white ceiling that is sloped that results in some light reflection. It sounds like there is nothing I can do but continue to use a little mask on the outside of the projector lens. I also may darken the ceiling at some point.
 

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Quote:
Originally posted by WanMan
Mark,


What we need is a light trap that 'recycles' light back into the light-source path! Unfortunately, that wouldn't any sense now would it!
WanMan,


In a way - that's what the second polarizer [ really it should be "analyzer" ] on a JVC G-15 D-ILA does.


The second polarizer scavenges another 50% output that gets by the first polarizer.


That's how a G-15 gets a 1500 lumen output vis-a-vis the G-11's ~1000 lumen output - even though they use the same

lamp. The 50% increase in power of a G-15 over a G-11 is because of this scavenging or "recycle" of light.


Dr. Gregory Greenman

Physicist
 

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Greg,


Having not seen the engineering on the G15, comparatively to the G11 and not, I had no idea it was polarizing the light source's output to isolate and minimize light spill. Kudos!


PS What area of Physics are you in?
 

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Quote:
Originally posted by WanMan
Greg,


Having not seen the engineering on the G15, comparatively to the G11 and not, I had no idea it was polarizing the light source's output to isolate and minimize light spill. Kudos!


PS What area of Physics are you in?
WanMan,


Yes - that's how the D-ILA chip works. The light that illuminates the chip is polarized. Depending on whether

a pixel is supposed to be "on" or "off", the D-ILA chip alters the polarization state of the light for that pixel.


Another polarizer [ analyzer ], then "sorts" the light by polarization state to determine what pixels to "dump" and

which to send to the screen. See:

http://www.jvcdig.com/technology.htm#whitepapers


The paper by Dr. W.P. Bleha states:


"The voltage applied to the selected pixel of the matrix makes the liquid crystal above the pixel change birefringence

and thus modify the polarization state of the projection light in the D-ILA." [ Page 3, second column ]


I'm a nuclear physicist.


Dr. Gregory Greenman

Physicist
 
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