DIY Rear Projection TV - diyAudio
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Old 8th November 2003, 04:42 AM   #1
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Default DIY Rear Projection TV

I'm here to help anyone who is interested in building a rear projection, I have succesfully build a rear projection tv use a design I found at www.draperinc.com. I don't know if there are calculation that you can use to figure out how far your projector from the I just used trail and error and it works.
To start out figure how big you want screen, 40" to 50" inches are easy to make but 60 and up are harder, unless you are going to but the projector directly behind you screen. After you figure out how big you want your screen find a mirror that is a couple of inches smaller than your screen or one the size of screen. You need a large mirror if you want to keep it small and keep the image bright.
Now for the projector, first build it so that the image will show correctly on the this mean that it shows up on the wall like a regular tv. Mine is made with the Sony PSone Lcd, a 42 watt(2700 lumen) compact floruescent light bulb and the Figinon rear projection tv lense.
Build a frame for the screen just something to hold it up, my screen was made from a piece of plex-glass and a opaque show curtain. Now here is were the trail and error come in, you have to figure out how to position your mirror and projector to get a image that fits you screen and is focused. Once you get it just right build the rest of your frame around it.
Once you get it build you notice that the screen is %100 viewable from a distance and at eye level, this is because the light rays coming from the projector are not the same length, thats why the center is brighter than the other areas around the screen. The longer the light rays are the darker they are when they reach your eyes. You would need a larger fresnel lense the size of screen to make the light ways equal when they reach your eyes.

I wish could add pictures but I dont how to but more than one image on a single post.
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Old 8th November 2003, 04:45 AM   #2
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This the draper inc design wish my could be this pretty.
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Old 8th November 2003, 06:17 AM   #3
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could you give more details on the screen you made? Thanks!
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Old 8th November 2003, 05:54 PM   #4
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My screen was made out of a piece of plexi-glass and a opaque shower curtain I got from Wal-mart, iron the wrinkles out of the shower curtain frist then place over the plexi-glass. Another idea is to use sand blasted plexi-glass or the acrylic diamond glass that go over flourescent fixtures.
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Old 8th November 2003, 08:27 PM   #5
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Default rmccol

heya bud, glad to see you have made one of the rear projection tv's! somthing that there isnt much about in here and congrats on your effort and research, im interseted in such a device but i had a slightly different plan, basically the thing was going to be the shape of a crt screen at the back and not using any mirrors, not sure if it would work but i think it could give us run for our money in the optics and trying to get them right, it would be good to set one up so its inbuilt into a wall that way it is like a flat screen just on the wall, either that or cabinet ect, either way there is alot of potentional here for this and i think it would be good if more wer into it, as for your screen it sounds spot on to me, i was going to go with the sandblasted plexi for a front projection screen but here where i am right now its abit hard to get hold of a sandblaster so ill wait till i go back to aust, anyway keep us posted and lets get the ideas in this flowing.

Trev
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Old 8th November 2003, 08:42 PM   #6
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I hung a shower curtain and projected a 40-50in image. The quality was incredibly well, sharp and bright. But the midle is obviously brighter than the edges. I believe it is because the plastics refract lights, and at eye level, more refracted light from the center of the curtain will get to eyes than those from the sides. So I folded the curtain to make a two-layer, and the screen is more evenly lightened. but you have to make two layers closely together, otherwise the image is fuzzy. I would try to strech it on a frame.

rmccoll: is the plaxiglas used for supporting the curtain?

and do you know the price range of draper's rear projection products? I think they use big fresnles to make rear projection screens.
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Old 8th November 2003, 09:32 PM   #7
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Default 18wheeler

huh interesting, i think what we need ultimatly is a good difuser that wont eat too much light yet yeald a bright image that is even, i have tried plexi painted white on one side for the front projection system but plexi uses light, it was 3mm thick plexi, i think ultimatley a 1mm or 1.5mm thick plexi would do the trick, maybe plexi in the white coulor or a difused plexi, i did try to see what it was like on the other side of the plexi to see if i could see much of a picture on the otherside and yess quite bright actually and clear, i dont know how evenly lit it was as it was only on a small piece of scrap but i think its got potentional, i maybe going to get more plexi this week so ill have a look and see if i can get a few samples to try different types and to see whats best or if this idea is worth persuing, an idea i had was the chistmas spray u put on your windows at christmas for the snow afect, this stuff is quite translucent and difused, abit like the phosfourus in a crt so maybe this will work, the only thing is it will have to be evenly spayed, another idea yeah yeah they keep coming eh? lol is to use the contact u put on school books, use the white that is quite transmisive too and easy to aply, anyway any thoughts keep them coming.

Trev
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Old 8th November 2003, 09:46 PM   #8
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My show curtain is taped to the plexi-glass and mounted to the frame.

The price of the RPS depends on the size of your screen, you have fill out a order form and they send the price to you, but i know its probably really high.

The screen I made is not good, you need something that can get the light to your eyes like a large fresnel lens, I believe edmund scientific sells a large fresnel for a solar oven.

Here is another picture, I bought a $20 camera to take the pictures thats why they're so bad.
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Old 8th November 2003, 09:48 PM   #9
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paint will block too much light. I would sand the plexiglas. to experiment, maybe sand half with coarse sandpaper, another half with fine sandpaper see which side is better.
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Old 8th November 2003, 11:33 PM   #10
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Default 18wheeler

ive tried the sanding but u see the sanding marks thats the only prob, as for the painting idea the snow paint that i was talking about is the best cos it dont block much light as its translucent, normal paint will depending how thick u put it.

trev
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