DIY Video Projector

[fender4]

Good stuff, Zeco! I looked for some info on the MLA's...here is a good description with pic:

http://www.nsgamerica.com/pml.shtml

It seems that it is just an array of tiny lenses etched into a transparent medium that concentrates the light to each individual pixel, minimizing light lost to the pixel "machinery" . Unfortunately, it seems like this would be a custom job for each panel, but I might be wrong.

I am still amazed at the projector in my auditorium at school. It is an Eiki LC-X1000 that puts out 3500 ANSI lumens. It produces a picture larger than most movie theaters that is viewable with enough ambient light to easily take notes. But this is what blows my mind...it only has a 200watt bulb! It is a UHP bulb, and I'm sure they pay a high premium for that bad mammajamma. Well, back to the real world...

Pod,
Good job on the MH mod. Are you using a reflector with it? You're not kidding about the heat with this DYS bulb. I would love to upgrade to the MH.

BTW, I noticed my OHP fresnel has some wear-and-tear "opacities" on it...enough to notice when the projection is in very fine focus. Watch out for that when buying an old OHP!

Here is a pic of the bulb assembly in my OHP, if anyone is interested. Note the small, simple reflector.

-f4

[pod184]

I don't have a reflector on it yet, but it is in the works. Actually, the original DYS bulb in my ancient 3M ohp did not have a reflector either.
The case is still being built. I need to make sure it is strong enough to hold the weight of the ballast, which must weigh about 10-12 lbs. As soon as I get more stuff mounted in the case, I will try to post some pics.

Pod

[ZeCo]

earlier projectors would all have condenser lens (fresnel).

Those microlens would replace the fresnel. That would also mean that we must use fresnel, in contrary of some think. I might be wrong, but it seens this way.

Projectors will either use fresnel (condensers) or lens array.

A brand new fresnel cost around $50. I'm pretty sure that MLA would cost a lot more.

Another thing I got was the specifications for the condenser (fresnel)

f = 0.5
facet pitch = 0.2 mm to 0.5mm
material = acrylic or polycarbonate

Each OHP use different fresnel. Mine is DC 1703 and has a facet pitch of 0.5 mm and effective focal lenght of 178.4mm

I dont know what those numbers would mean (as far as quality goes).

Im now almost convinced that we must use fresnel (from overhead projectors, not those magnifier lenses). Unless of course I get my hands on those MLA.

The ellipsoidal reflectors seems to be more useful on those very small panels (2.5" or smaller), so I am also almost convinced that unless we work on the polarizer/wave retarder, the reflector to go is parabolic.

What i need to figure it out is what to use as field lens and projector lens.

What focal lenght type should I look for? and how big the diameter of the lens? And, can I just use a projector lens? If so, what would the specifications be?

I know that those Delta and Fuji would not really work as they need to be very close to the panel and since the diameter is smaller than the panel, we would not be able to fit the whole screen.

Once I figure that out (with you guys help) Im going to design the projector and start spending some money.

PS: I bought an old projector. Should get tomorrow. Im going to take a look on its inside and perhaps use parts of it (or just re-sell after a while)

It uses a 6.4" panel and the not so very good FXL halogen.

PS2: Have you guys thought on using Xenon short arc lamps? cinema projectors use that lamp, but hehe, Im not going to buy a 100,000W lamp or my electric bill will kill me

[gtwolf99]

I have the opportunity to buy this unit but the remote is missing. Is the remote necessary for this unit to function properly? (i.e. Are there functions on the remote that is not on the panel?)

Whats the reports on this unit, does anybody have one? Are you pleased, displeased?

Can these units be used as a standalone without the ohp, like a car lcd? (just curious)

Thanks all....

[Gunawan W]

Undream, you're right about LCD panel resolution.
LCD panel has fixed size according to it's resolution (pixel).
Most desktop LCD panel has pixel size around 0.3x0.3mm, so if the resolution is 1024x768, the size is 1024x0.3=307.2mm=12" horizontal and 768x0.3=230mm=9" vertical, with ratio 4:3, diagonal size become: 12/4x5=15".
Nowdays 15" LCD monitor is the common and the best price we can buy, but IMO it's too big for DIY projector ( need bigger fresnel panel and lens diameter), I think 12" is the best fit (with 4:3 ratio, it's become 9.6"x7.2" size or 800x600 resolution).
Until now, I can't find 12" size with latest spec and low price (don't say about notebook LCD panel, it's useless), please let me know where I can buy it.
Or, I just buy 15" size and sacrify some resolution to fit the size (12" diagonal = 800x600).
Any better idea?

[gav]

http://cgi.ebay.com.au/ws/eBayISAPI....tem=1355212565

has anyone come across this before??

[ChuckReese]

ZeCo:

Parabollic reflectors only make sense if you have a small LCD panel. If you are going the large panel/OHP route, then use an ellipsoidal reflector and a condensor lens (fresnel).

For the projection lens, just find a cheap plano-convex lens. In order to know what focal length you need, you must first specify the distance to the screen and the magnification. If you want a magnification of 4:1 and throw of 8 feet, then the projection lens will need to be 24 inches in from the LCD. The focal length will be approximately given by: 1/f = 1/u + 1/v, where u,v are 8' and 2'

Gunawan:

The problem with smaller XGA displays is they have inferior contrast ratio. The only way to get decent CR is if you use a 15" display. If you find a 13.3" display with good CR (350:1) then tell me about it.

In order to use all of a 15" LCD, you will need to rip out the OHP fresnel and use bigger ones. There is a good 18" fresnel from fresneltech that goes for $120, but you need two of them. If this increases the total system cost too much, you will just have to get use to losing the pixels at the edge.

CR

[Timtimes]

[QUOTE]Originally posted by Atomos
[B]Is there any reason you guys aren't using the 1000 or 1500 watt metal halide bulbs?

I'm guessing that most folks in this forum are trying to build a video projector, not a space heater.

Enjoy.

[multiplexor]

OH GOD! I cannot believe i just spent many days and nights reading every single freaking post. Damn you all for getting me interested in this! ARG!

From what i've read, the lighting is the hardest part to figure out.

I'm going to be starting this project pretty soon hopefully. And after reading EVERY SINGLE POST! I feel confident that i'm going to get a decent image out of an OHP and LCD screen. Seems the standard way to go.

Though I haven't started yet, i'm not too worried about the lighting. I've been a little too creative and inventive since i've been very young. I'm sure i'll find some cool solution. hehe

I must say though, this thread is incredible. As a thought though,
you should probably create another thread only to post about lights and which you've used and thoughts on each. then this thread can revert back to trying to find a plan to create a good projector. focusing mainly on the projector and less on the light needed for it.

just a thought hehe


Question: I didn't see a response as to why you could not use the light from a motorcycle. like the hyabusa mentionned earlier.
It uses a projection lens system which i thought was very good. Used by BMW, and some integras. The way the light comes out of these things is usually pretty damn bright.

I know there was some mention to headlight before... but i don't see those working, not bright enough. But the projection lens car lights function a little differently.

Instead of using one bright light, anyone try just using 2 lights and less brightness? enough to equal one bright light though.

I look foreward to reading this thread and other DIY projector threads as it progresses.

[tomithy83]

the reason that you guys are haveing problems with lighting is that because your useing HUGE LCD"S just a thought its cheaper for the small ldc's anyway
les res quality but thats the trade off for better\cheaper light quality