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[Frankie]
Joined: 16 Jun 2014 Posts: 88 Location: Italia
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Link Posted: Tue Oct 10, 2017 12:56 pm Post subject: Passive 3D on CRT... worth a project? |
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Hi! I've got in mind this project these days. I saw on the internet that there are kits to transform a projector in a 3D Passive projector by means of one (or in this case 3) Liquid Crystal Shutter that goes up to 120Hz. I guess i could make it on my own a system like that, except for the fact that i can't find any Liquid Crystal Shutter. The only one i've found was on this site: http://www.liquidcrystaltechnologies.com/products/lcdshutters.htm . This company can produce Liquid crystal shutters at the size i need to. I still haven't asked the price but i guess it will be a bit expensive.
My idea was: I place three liquid crystal shutter plates in front of the tubes with polarized filters. Then i have bought a Kit from internet, the e-dimensional 3D wired kit with a dongle VGA that goes out with a 3,5mm Jack or a 3D Vesa Plug. I connect the three shutter plates with a circuit that pilots them (that i will build if it's not that hard) with the signal that goes out the 3D Vesa Plug. Then i send a HD Resolution (720p i suppose) at 96Hz or 120Hz to the projector. the Dongle between the projector and the HTPC will exit the sync signal to the controller of the shutter plates and then it should be over. The three shutter plates turns on and off at the sync signal. So there's passive 3D on the projector, is that correct?
Let me know if you have got some ideas or corrections! Thanks for any reply!
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[Frankie]
Joined: 16 Jun 2014 Posts: 88 Location: Italia
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Link Posted: Tue Oct 10, 2017 12:57 pm Post subject: |
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The projector that i think i'll use is a NEC XG 135 LC.
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AnalogRocks Forum Moderator
Joined: 08 Mar 2006 Posts: 26690 Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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Link Posted: Tue Oct 10, 2017 4:48 pm Post subject: |
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With LCD shutters it would be called active 3D wouldn't it?
_________________ Tech support for nothing
CRT.
HD done right!
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kal Forum Administrator
Joined: 06 Mar 2006 Posts: 17850 Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
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cmjohnson
Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s
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Link Posted: Tue Oct 10, 2017 5:05 pm Post subject: |
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120 Hz refresh rate at full HD requires almost 300 MHz bandwidth, well out of the range for almost any projector.
Fast P43 phosphors would be required for ghostless operation.
The LCD shutters will cause significant loss of brightness, too, as even in the "open" position they're not exactly fully transparent.
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garyfritz
Joined: 08 Apr 2006 Posts: 12024 Location: Fort Collins, CO
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Link Posted: Tue Oct 10, 2017 5:12 pm Post subject: |
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The ideal IMHO would be what Kal referred to as passive -- TWO projectors. Do a stack (both projectors aligned onto the same screen) with one showing left, one showing right. Then you just need passive polarizer screens in front of each lens and in your glasses. Each eye would see the full brightness of one projector, minus the loss of the polarizer. There wouldn't be any shutter flicker and you wouldn't need the 300 MHz bandwidth that CJ mentioned. But you would have to very carefully align the two projectors. Most stacks I know of used G90's, because of their geometry control and stability. You might be able to do it with a pair of XG's, but it would be a lot simpler to stack two G90's.
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[Frankie]
Joined: 16 Jun 2014 Posts: 88 Location: Italia
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Link Posted: Wed Oct 11, 2017 9:31 am Post subject: |
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I understand. I didn't want to do stacking.. but effectively i could. I have got an XG 110, a XG 135LC and a 9PG Xtra. The Xg 110 needs service and the 135LC needs at least a new green tube. I've found three new tubes of a 135LC on eBay few days ago and i see these days to buy them. Is there some guide on the internet on how to do the stacking with CRT Projectors? Later i'll search a bit anyway. And for you can it be done for example with the XG 135LC and the NEC 9PG Xtra eventually?
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garyfritz
Joined: 08 Apr 2006 Posts: 12024 Location: Fort Collins, CO
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Link Posted: Wed Oct 11, 2017 1:15 pm Post subject: |
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Yes I'm sure it could, but the geometry controls on the xg and pg mean they will be harder to align than a g90.
One thing I'm not sure about is how well the polarization stays aligned when it hits the screen. I assume it must work because it's been done, but it might require circular polarizes - not sure.
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barclay66
Joined: 27 Jun 2011 Posts: 1291 Location: Germany
TV/Projector: Marquee 9500 Ultra
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garyfritz
Joined: 08 Apr 2006 Posts: 12024 Location: Fort Collins, CO
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Link Posted: Thu Oct 12, 2017 1:10 pm Post subject: |
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Ya, that's what I suspected -- you can lose polarization when the light hits the screen, unless you use a special (and no doubt $ex$pen$ive$) screen material. Which is high reflectivity and thus has hotspotting issues.
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barclay66
Joined: 27 Jun 2011 Posts: 1291 Location: Germany
TV/Projector: Marquee 9500 Ultra
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Link Posted: Thu Oct 12, 2017 4:36 pm Post subject: |
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Hi,
There’s one exception to this rule: Dolby 3D (there’s a Wikipedia article explaining how it works)! It uses narrow-banded color filters.
Unfortunately, those filters -large enough for CRT lenses- are very expensive...
Regards,
barclay66
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AnalogRocks Forum Moderator
Joined: 08 Mar 2006 Posts: 26690 Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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Link Posted: Thu Oct 12, 2017 6:32 pm Post subject: |
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Didn't Clarence have some poarizers with a batch of CRT stuff he got once?
_________________ Tech support for nothing
CRT.
HD done right!
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harry27
Joined: 04 Aug 2019 Posts: 22 Location: Los Angeles, CA, United States
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Link Posted: Wed Jul 28, 2021 3:35 am Post subject: |
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I did some research on passive 3D a while ago. I found a company who apparently sells large size passive 3D polarized filters (both linear and circular polarizing), sizes up to 14" x 20" so they are more than large enough to cover CRT lenses. As long as there is no technical reason preventing CRT projectors from being used with silver polarized screen and polarized filters then it shouldn't be a problem as long as you have an external passive 3D processor and two HDMI cards.
Whether it's worth the investment/effort to get all those stars to align, well that's all up to the individual. It would be cool to see passive 3D at 72hz with CRT's good motion quality though. Also it might not be worth the potential sacrifice in image quality using a high gain polarized screen over a traditional gain screen.
https://www.apioptics.com/product-category/products/polarized-3d-filters-glasses/3d-passive-projection-filters/
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