I am using 3 1:150 panels, run *flat out* (ie quite high driving voltages - for an LCD)
I would love some 400:1 panels to play with though )
Think series panels, two active panels, and one passive.
Works like such. Quick reminder that inactive LCD rotates polarisation 90 degrees, active passes without affecting (much) polarisation.
Linear light path, parallel converged panels...
Light engine shown only...
(1) (2) (3) (4) (5) (6)
1) V polariser
2) Panel - Active
3) H polariser
4) Panel - inactive unpowered (polariser rotator)
5) Panel - Active same as (2)
6) H Polariser
Polarisation directions assuming unpowered panels
1-2) V polarised
2-3) H polarised
3-4) H polarised
4-5) V polarised
5-6) H polarised
Contrast ratio/black levels drastically increased, panel 4 is (eventually) to be used for 16:9 masking, or can be simple passive LCD single pixel 'sandwich'.
Of course, if (5) is reversed, and driven with a mirror image of the video, panel 4 could be dropped as input light polarity is now correct. I am too lazy to do this and I like the idea of eventually using panel 4 as 16:9 masking. (assuming 1:400 panels all, how does 1:1200 masking sound?)
In future - the projector whose guts are spread over the table has the red and blue panels in mirror reverse (due to optics) - might ditch passive panel and try this instead (passive panel loses light unfortunatly) - also will try running all three panels instead of just two.
Anyone else making anything like this - would like to swap ideas/parts...
Contrast ratio is well and good but nobody has said anything about absolute black level yet. Am I wrong in thinking the new PLV-70 from Sanyo achieves that number because of the 2000 lumens output rather than having a low absolute black? Ie, they've gotten the bright bits brighter but the black bits no blacker. Pure speculation on my part, I'm wondering if that might not be the case...?
You may be correct that a large reason for the increase in contrast ratio between the PLV-60 and the upcoming PLV-70 is due to increased brightness levels rather than darker blacks (if we keep black levels constant and increase light output by 2-fold, then there will also be a 2-fold increase in measured contrast ratio). I find that my PLV-60 has ample brightness. If I were to go with a PLV-70 I would add a neutral density filter to cut 30-40% of the on-screen light output which would also result in a corresponding darkening of black levels.
Scott, this would be correct...Math says 1200 lumens ----> 2000 lumens (close to 2X) and the contrast is 500:1-----> 1000:1 (although Sanyo has YET to put that in writting so the 1000:1 might not be what it actually turns out it be. Remember that the PLV-60HT was originally 1300 lumens and 700:1 instead of 1200 lumens and 500:1 that it is speced now.) Sounds like absolute black levels will be the same.
I suspect that you are correct regarding the absolute black levels between the PLV-60 and the upcoming PLV-70. Even if absolute black levels are the same on the two projectors, perceived black levels will appear lower on the PLV-70 which will have higher light output and contrast ratio.
Just as an FYI to all.... many times I am uder a hush order on things....please take into consideration that I might be in knowlege of information that is not be available to the general public yet when I make comments that that one above. I can state that I do know that the specs that have been spoken of regarding the PLV-70HT are very likely not the specs that you will see when he projector is produced. Sorry I can't be more specific than that. As soon as I am told I can say more, I will.
It sounds like some of you think getting higher CR by more brightness is easy and maybe even "cheating".
It is neither. Putting in a brighter lamp (if it the same size/shape arc) will increase blacks as much as brights and leave CR unaffected.
CR can only be improved by improving the performance of the chip and associated optics and/or paying better attention to stray light control.
Your idea of using panels in series has been discussed before. Besides complexity there is a big heat in light output. Do a search on usrname "Thumper" for more explanation. I think you'll find his other posts interesting.
Yes Noah, not what we (well at leasy myself) were saying. I know that it's not easy doing what they did, but I also know that if you do the math the absolute black level isn't decreased, the contrast is, but not the lumens of black. Not a huge deal but it was answering the guys question. I certainly don't think it was saying anything negative at all.
Nor was I implying it wouldn't be a step forward to get double the light output but keeping absolute black where it was. I suspect though they are exaggerating the contrast numbers and that Sanyo hasn't managed to keep black level equivalent to the PLV-60.
I am however a cynic and I guess we'll know once someone gets their hands on one of these (or gets released from their NDA's )
A forum community dedicated to home theater owners and enthusiasts. Come join the discussion about home audio/video, TVs, projectors, screens, receivers, speakers, projects, DIY’s, product reviews, accessories, classifieds, and more!