What I’m proposing is not new; is basically, an Un-split folded pj design with some modification.
I was thinking if we can apply the same principle as in DLP technology.
As all you know, (or most of you), DLP PJs uses a rectangular array of hinge-mounted microscopic mirrors coordinated with a digital video or graphic signal, a light source, a color wheel, and a projection lens. More info here: http://www.dlp.com

Now, the idea is simple; to get our LCD panel to be as transparent as possible, (no AG, no Polars), that means that when you feed your panel with a full screen white image, it will be completely transparent... (If you hold the panel and see trough it).
Now, if we put a mirror right behind it, and lit the panel from the bottom through Fresnel, and let the panel (and the mirror) project the reflected image on the screen, (see Sketch up below), we're in some way reflecting pixels on the screen in the same way DLP works, but with the color wheel and all its electronic involved out of this equation.

I don't know if it is possible to get a lcd panel completely transparent when you feed it with a full screen white image, after remove AG and polars; I don’t know if a lcd panel can work without the polars either, I don’t even build my first PJ yet, but, it make a lot of sense to me, and, the quality should be better in theory, since we don’t have any Fresnel on front that can compromise the quality of the image. Any suggestion ?.

Sketch up

Some ray tracing...

Warning!!

If you are Newbie.. Read this:

Polarizers are necesary for the LCD to work; you can safely remove AG (AntiGlare) coating from the LCD, but Do not remove Polarizers, unless you're planning to replace them.

Due the polarizers, LCDs can only pass light up to something like 7 degrees, so unless you could make your source within 14 degrees of the triplet this wouldn't work

I think, that passing light thru LCD to mirror and then back could't work. But if it can work, surrely the image will be heavily distorted (keystone) and cannot be focused.

What about this? The light gets straightened by one fresnel, then bounces off the mirror/ LCD, then goes through the other fresnel, into the projection lens, which projects it. And then keystone using the fresnel before the lens (after the LCD)

I miss typed it should have been because of the polarizer, some how I typed fresnel. The only way this could work would be to have the hight source pretty close to the triplet

I must be missing something, i'm not seeing what we would gain from this...
Forgive me for being stupid, but could you tell me how passing light through the LCD twice, would make the image any better?

-Aaron

No one would be bothered by 'overbright-projection', and the dual-ghosting viewed through red/blue-cardboard glasses may result an interesting/psychedelic '3-D effect'? <g>

Since i have a little 2.5" lcd and a very samll fs mirror i might be temped to try this just to see if it will work (i dont think it will but it does seem worth it to try.) Ill get back to you guys tommarrow; ill go see if a lens.

Nice idea,but There ae a couple of issues that I can see.
The angle that the light is being transmitted through the panel may not be within the polarizers "FOV",and the light will pass through the lcd,projecting an image,which s bounced off the FS mirror,through the lcd again(?),projecting another image,giving 2 x images projected,both with different focal distances.
However,that is the point of these forums,discussing,and disproving/proving theories,so give it a go!
Cheers P

paul77;

1 try your ideas(invest time money)(its what being a diyer is).
2 show your results(that we can all learn).
3 don't give up(sucess only happen if you keep going)(Winner never Quit and Quitters never Win).

As for you design, to me, it look flawed(ghosting problems)(strait shooter might work(lcd might heat up too much cuz of the intence light))

best of luck tho. lets see the results.

brilliantfarmer

I read the thread 3 times, I still can´t find a single reason to think this is going to work.

Computek, I like how you're trying to find better ways of building - but I'm afraid I am with kv29. The reason is that the liquid crystals in LCD panels are designed to refract light on a straight path through the panel. What you're suggesting would take light in on an angle (and probably dim the light in the process) and emit light on another angle (where the light is dimmed again after it hits the mirror). Granted, a lot of the active matrix screens allow you to look at them from the side, light coming at 45 degrees and leaving at 45 degrees might not only be very dim, but also possibly discolored due to the angled light the liquid crystals were not made to refract. Imagine a bunch of tiny prisms that look one way when a light is behind it, but an entirely different way with a light at 45 degrees.

Sorry!!!