DIY Rear Projection TV

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dbc105

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Joined 2004
I have been looking at this for about a year. Have not done anything yet though. I have a bad Pioneer 42" big screen in the basement that looks like it would be perfect for a Lilliput retrofit. It is already setup with the lenses, front side mirror, screen, it's just not wide screen. I keep putting it off though because big screens keep getting cheaper. I would like to see one of the DIY projectors first so I would kow the resolution would be good enough after you enlager a 7" screen to a 42". Though about calling the rental place to see if they had an overhead and a panel to do some testing first. Just don't want to spend time and money on something I'm not going to be happy with.
David
 
Nads

Nads

Member
Joined 2004
Have not had time to read ALL of the posts, but as for diffussion, how about the glass spray etch? or a VERY large sheet of greaseproof paper. I have tried greaseproof paper at A3 size, the biggest I could find, and got very good results with an epson emp s1 projector with minor hotspot. the glass etch could be used on two pieces of glass, placed back to back if hotspot is not eliminated by just one. I bet that someone produces greaseproof paper bigger. Another suggestion, which is totally untested by me, is if you used bare fibreoptic cable or plexi rod to make a `sandwich` of rods running vertically. This may be totaly impractical or cost prohibitive, but if the rods were stuck to a plexi panel......l
 

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Nads

Nads

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Joined 2004
Some years ago, Tomorrows World, a BBC technology program demostrated a product that one of the universitys here in the UK was creating. I think it was Cambridge university, anyway the plastic film was placed half over a casio 2.5inch tv and the difference in quality was amazing. The plastic film was created by etching micro lens into the plastic using a laser. The process to give an image is very similar to collomation lenses, but on a microscopic scale. Now I have searched the net and not found anything to do with this, but someone must know what happened, anyway IF we could use a large scale injet printer to print some sort of polymer on to a clear acrylic sheet, the result of which would be a dot of liquid, which would dry and if I am correct it would pool in a lens shape. This may or may not be possible but if it could be done it would create some stunning rear projection screens for DIY RP tv`s. The beauty about this was the fact that it gave NO hotspot and when off, the plastic was opaque, which if you placed it on a window, the window would work as normal, but when an image was shone onto it via a projector, it would be displayed on the `screen`, and it worked as a FS screen too which would allow normal projection, but with higher brightness and contrast AND you could look directly at the projector light beam, as long as the screen was between you and the projector, which resulted in a bright vibrant image. The program aired circa 1986. The attached image is of what I can remember of the layout of the lenses
 

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Nads

Nads

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Joined 2004
rmccoll. I am fortunate that among the things that company I work for sells, we have a fabric shop. Find below the products I have `borrowed` to test for screen use (RP rear pro, FP front pro) compared to my commercialy available vynyl screen and my Epson EMP S1H and a small bit of 25% grey tint plexi/perspex:
6` width Commercial vynyl screen: very minor relection from screen. Annoying but livable. Cost £79.00. Ease of use: Good
6` width white cotton fabric roll down blind: FP. 5/10% less brightness, image quality similar. RP similar brightness, negligable hotspot, image quality very minor smudging, contrast bright without plexi, good with. Ease of use
60" width white blackout lining FP: good brightness/contrast with similar to commercial, but no reflection, good colour rendition. RP no good cos it blocks ALL light. Cost £5.00 mt ease of use, well i had to build a frame to hang it.
72" shower curtain: RP as its partially opaque, hotspotting was a big issue, with the sides being washed out and the center bright, FP was not any better, but now with reflection. In my case could not recommend. I also tried a white shower curtain, but due to the fact it had an embossed pattern, it coulnd`t be used seriously, but turned in similar FP results as the commercial, but RP was good, and better with the 25% plexi over the front
 
L

lesko

Member
Joined 2004
screen

Hello,
I have been using drafting velum for my LL front projection screen for a while now and love it...it comes at 56" high and lets alot of light through...but it pretty defused so there is really no hot shot at all...I painted the back side of mine with alum. paint and get deep rich bright colors...better than blackout cloth...BC sometimes gets to washed out...you can pick this stuf up at any large print house (here in phoenix It's called Thomas Repro graphics) so I guess any Repro Graphics print house will have it...just ask for Drafting Velum...You can get any size but wide but only 56" high...
Staple gun it to some wood and so on...
you can also find the defuser film in large sizes that is inside a lcd. that would work great also
http://www.gestructuredproducts.com/sp1/gesp_amer/index.jsp

anyway I just thought i would pass it on.

Lesko
 
K

KANA007

Member
Joined 2004
Hi Guys,

I have a dead 53 inch Sony crt rptv. Not widescreen. Can I
put an overhead projector in the bottom, on its side, and
shoot the image throuh the center crt lens? Leaving the center
lens where it is now mounted. It has a Delta78 with 4 inch lens.
I would like to use 15 inch lcd but a 7 inch lcd might fit better.

Here is a sketch.

Thanks
 

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ibleed

Member
Joined 2005
RPTV

Hello. New to this tread. Trying to understand things. Some people are talking about using lcd panels (ranging from 1.8" upwards) with 200W lamps or whatever and im wondering how they do this. Are these people taking the panels apart, removing the backlight and using one of their own?
 
A

ancorp

Member
Joined 2004
KANA007 said:
Hi Guys,

I have a dead 53 inch Sony crt rptv. Not widescreen. Can I
put an overhead projector in the bottom, on its side, and
shoot the image throuh the center crt lens? Leaving the center
lens where it is now mounted. It has a Delta78 with 4 inch lens.
I would like to use 15 inch lcd but a 7 inch lcd might fit better.

Here is a sketch.

Thanks
Click to expand...

Nope, that unfourtinately wont work. The CRT lenses are meant to be very close or completely up against the source, and only capture an image as big as its rear end. A 2-4" LCD might work (as far as I remember, a 4" lcd wont fit under a Delta 78)

Cheers,
Alex
 
A

ancorp

Member
Joined 2004
Re: RPTV

ibleed said:
Hello. New to this tread. Trying to understand things. Some people are talking about using lcd panels (ranging from 1.8" upwards) with 200W lamps or whatever and im wondering how they do this. Are these people taking the panels apart, removing the backlight and using one of their own?
Click to expand...


Yup, than slap on some proper optics, cooling, and wiring, and off they go :)

Cheersm
Alex
 
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