CurtPalme.com Home Theater Forum

[tse]

http://cgi.ebay.com/LEXEL-IMAGING-81736-02-CRT-PROJECTOR-/350466378581?pt=LH_DefaultDomain_0&hash=item51996c8b55

These babies are used with a 1" x 0.8" mini raster that resolves 1280 x 1024. The raster follows the direction that the "pilots" eyes are looking in a flight simulator. Most are red, there are some green. No blue.

One could make a super sharp HD image with these. It would take a lot of work to make a projector system but it would rock.

Scott

[Spanky Ham]

Nash might be up for the challenge.

How hard would it be to put these in a Marquee?

[AnalogRocks]

[AnalogRocks]

[dvh99]

thats the tube and the lens in the pic with the neckboards, i suppose these are placed in a rack with the electronics being in a separate enclosure and the power supply in a separate enclosure too.

they are liquid coupled btw.

[cmjohnson]

The Surfbird lenses on those things are over 10,000 dollars each!

Tse could say for sure, but buying three of those just for the lenses would put an absolute end to the question of what
are the best lenses on a home theater CRT projector.

This assembly is the heart of the Marquee target projector.

The catch is, those tubes are (last I heard) only available with a red phosphor or a green phosphor, and NOT a blue phosphor,
but I'm sure that for the right (absurd) amount of money, Lexel would make one with blue phosphor, just for you.


In operation, these run a very small, high resolution raster which is dynamically shifted around the screen. While in theory this
gives some absurdly high resolution capacity like 12,000 x10,000, and the tubes and optics are indeed sharp enough to handle it,
you've got bandwidth limitations to contend with and no way to drive that kind of bandwidth at regular raster sizes.

If you did manage to overcome the input bandwidth limitations, you may still run into a brick wall in the form of a hard bandwidth
limitation on the cathode of the CRT itself.


They'd be a lot of fun to play with, for sure, and they have enormous potential for making the first ever 4K or greater CRT projector,
but without a blue tube of this type available, the best you could probably manage is to use a blue LUG in the system, which would
probably be quite tolerable.


Anyone with 1500 bucks to play with could have a fine time with those. It would probably be worth it just for the lenses. I'm reasonably sure that they'll mount up to HD10 mounts. Tse should be able to confirm that.


CJ

[draganm]

[cmjohnson]

Yes, just like that, only the raster, which is about the size of a postage stamp on the CRT face, can be shifted to any point on the CRT face.

I believe this is done by magnetic shifting via special coils that are part of those extremely fine Syntronics custom yokes.

Tse should be more technically "up" on these than I am but I think that's their mode of operation.


I believe that it's those custom yokes that make the magic happen. The dynamic deflection capacity of them is probably very small,
while the static deflection capacity is very large. So, with those yokes, you could probably not get an ordinary, full size raster out
of them.


I get what I'm saying here from a discussion I had with someone at Lexel a few years back. I actually asked about those tubes and he
said that the special deflection yokes were every bit as much of the system's magic as the high resolution CRT itself, that is, if I'm
remembering the discussion correctly.


The end result of it all is that it may not be possible to display a conventional picture on those CRTs with those yokes. They'll display
a small, very high resolution window which can be thrown anywhere on the CRT face, but that's all. The tiny raster is an intrinsic
feature of the yoke. It can't throw a standard sized raster. I think...


And, the static deflection system (driving the location of the raster) isn't going to be capable of moving the raster around at scan rate speeds. It won't have the bandwidth.


It all boils down to bandwidth limitations. Quick, what would be the horizontal scan frequency if you were attempting to project a 4K
signal at 60 Hz?

Full aperture 4K is a resolution of 4096 x 3112 with 12,746,752 displayed pixels. Multiply by 60 frames per second, and the raw
bandwith required, not even counting sync and timing overhead, is 764,805,120 pixels per second. You'd need 1 GHz of video bandwidth at least just to fully display 4K. You'd have to swing that 4096 pixels wide scan line across the CRT face more than 3112
times per second. A horizontal scan rate of over 186 KHz, and that's just at 60 Hz refresh!


The Marquee target projector, which uses this or a similar CRT and optical system, isn't remarkable in terms of its video channel performance. It's just one channel out of a Marquee, quite adequate for 1280x1024, but no way it'll handle even a 4K signal.
It doesn't have even that much bandwidth.

The targeting projector system is able to display the windowed equivalent of about 12,000 by 10,000 pixels. That'd be 7.2 billion
raw pixels at 60 Hz refresh, again, not counting sync and timing overhead.


To fully exploit the resolution capacity of that lens and CRT, you'd need a full 10 GHz system bandwidth just for 60 Hz refresh. Double
it for 120 Hz.


What's more practical is to just use the lenses and enjoy them. But I don't know if they have corner focus adjustments. They may be screen application specific and it may not be for a flat screen. They may also have a limited range of focal tolerance which may limit your screen size and projector location dramatically. It would be incredible if they're a drop-in replacement for HD-10GT17s in
terms of screen size and distance range, but I'd be surprised if that were the case.

Yeah, they'd be fun to play with, but they're highly specialized units and though they're very fine, they have certain definite limitations
to their abilities that aren't immediately apparent until you start analyzing how they have to work.


CJ

[zGman]

Some good points and neat stuff - seems to me that the lenses would be
designed to cover a large part of a simulator dome screen, so that the
hud would always be where the pilot is looking....?
G

[draganm]

[stefuel]

Look close. There's a awfull amount of parts there that resemble AmPro parts.
Look at the LC block and radiation shield

[AnalogRocks]

[AnalogRocks]

[stefuel]

[AnalogRocks]

[AnalogRocks]