DIY Video Projector

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vdi_nenna

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2000-10-10 7:27 pm
PA, USA
Hi,

If there is anybody out there that is interested in sharing ideas on DIY video projectors, please let me know. I have several sources for parts, info and theory. I'd like to network with others who'd like to try this or who has worked on this type of project in the past.

I have been told that it is difficult to constructing a projector. Quote- "...it's the equivant to building a car."
I don't think that's true anymore.

Many parts are readily available. The info is out there. A person who is interested needs only to know the basics. It's kind of like putting a PC together from parts.

I can get mirrors and lenses of all types, specifically for projection systems, and they are not expensive. Depending on the approach taken, I think a system could be made for a few hundred dollars.

I'm looking forward to hearing from anyone who'd like to share ideas on this forum or via email.

Vince
 

vdi_nenna

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2000-10-10 7:27 pm
PA, USA
LCD Projectors

There is much to look at, but the best thing to start w/ is the sharp site for an example of a 3 panel projector. I want to try w/ one LCD first. Less parts less cost, but I hear the quality isn't too bad. I'm only interested in using it for movies.

I'm going to start at the end of the month to gather parts.
let me know what you think.

[email protected]

http://sharp-world.com/sc/library/lcd_e/s1_4_5e.htm

LCDs:

http://www.amitm.com/

http://aeicomp.com/index.asp

http://www.crystaloid.com/prod_tft.html

http://www.flat-panel.com/index.html


Mirrors and Lenses:

http://www.optosigma.com/mirrors/ColdMirrors.html

http://www.edmundoptics.com/


Bulbs:

http://interx.net/~pope/bulbs/

Theory:

http://www.tecdis.com/product.htm

http://sharp-world.com/sc/library/lcd_e/indexe.htm

http://www.ee.washington.edu/circuit_archive/text/LCD.html

http://www.edmundoptics.com/techsup/tsb/qtip.cfm

[Edited by vdi_nenna on 05-18-2001 at 03:06 PM]
 
sounds interesting

I'm very interested, so keep me posted. I've thought about doing this, but I've often wondered about how difficult it would be, especially in getting the optics right. I'll have to read through the links you posted and then get back to you. With any luck, I can have time to work on this in six months :)
 

vdi_nenna

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2000-10-10 7:27 pm
PA, USA
Very cool. I'd like to hear any impressions or ideas you have on the topic. I learned a lot of information in a week. If you have any questions, email me or post it. I'm no expert, but I've been all over the internet trying to get info. Half of it is already posted here.

Vince
 

vdi_nenna

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Paid Member
2000-10-10 7:27 pm
PA, USA
Light Sources

I don't like the idea of heat in these projectors, so I was looking around for another light source last week. I found that recently, scientist have been able to come up w/ a white light LED. Typically able to put out about 10 lumens each. I read about one that recently came out that outputs 17 lumen. The best part about these LEDs is that there is almost no heat, and run off of about 3-4v & 30mA, elimianting the need for cold mirrors and UV filters because there is no UV radiation, but still it is the closest thing to artifical light that come close to sun light.
Clusters of about 24 to 36 are being used to light large rooms. Another nice aspect of the LEDs is that the light radiates in one direction, with little light dispersion. That might be a problem for lighting up a room, but not for projecting an image.

I have a link to place that make clusters of these.
this is a quote I found from a Q & A:

Cheap LCD projectors? (12:43am EST Thu Dec 14 2000)
Will high-power white LEDs eventually be used to produce cheap, bright LCD projectors that don't need a $400 bulb replacement every 500 hours? Forget these big, bulky TV boxes, just put a white sheet on the wall and attach a projector to the ceiling. - by Kirk

Re. Cheap LCD projectors (2:17am EST Thu Dec 14 2000)
And the best about it: The fan making the noise won't be necessary if the LED-"bulb" doesn't heat up like the current ones do. The biggest issue about projectors usually is that they make way too much noise for comfortable home use.
- by kke

I think it can be done now. I'm going to give it a shot as soon as I can find the brighest LEDs avalable. Just think, these LEDs last 90,000 hours.

let me know what you guys think.

Vince


http://www.hollysolar.com/lowvolt.htm
 
This is a great idea. I'll let you be the pioneer here, but I'll be next.

I looked at the super bright white LEDs. That's great, but who is manufacturing the LEDs themselves? These guys are just putting them into nice packages. I would buy some to play with if they weren't $8 a piece.

Too bad there aren't blue LEDs. I think someone has them, but they aren't widely available yet. Then you could probably do the same thing with three boards of LEDs. Red/Blue/Green. Then adjust the current to each board until you get a white light out. I know they have 3500 milliCandella red LEDs.

pixie
 

vdi_nenna

Member
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2000-10-10 7:27 pm
PA, USA
WHITE LIGHT LEDs

I just found a place where they sell them 6 at a time for just under $18. There are a tons of OEMs and several sellers of individual LEDs. I found a guy who sells them for 1.75 each. Once I get more on this, I'll send out some links. For now. goto http://www.google.com and type in:
ultra bright white LEDs. See what comes up.

late

Vince

ps. the only way to invent the white light LED is to invent the blue first. Red, green, blue makes white light. Blue light passes through Phosphorus to make white light. That's sort of what I read. Blues have been around since the early '90's. White LEDs have only been around since last spring.

If I can pull this off, it will be totally cool! If not, I learned something too.

[Edited by vdi_nenna on 05-21-2001 at 03:54 PM]
 

vdi_nenna

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2000-10-10 7:27 pm
PA, USA
Update

I ordered 50 ultra bright, white light LEDS and a 5.6" diameter LCD screen yesterday. I need to pick up a projection lens to do some initial testing. It won't be long before I have more to report on whether or not this project has or has not worked.

I also have a great source for 7" 16:9 aspect ratio screens for $400 w/ driver board. A bit pricey for a DIY project, but not too bad if the results are good. The 5.6" was only $159.

I'll let you know more as I progress.

Any questions, let me know.

Vince
 
Forget these big, bulky TV boxes, just put a white sheet on the wall and attach a pro

How about putting an array of three colour high-power LED's directly onto the wall in a cluster of say 16*9 feet ...

With the going rate of projectors, this would probably be cheaper and you don't even need to have any optics, no fans etc.

I am concerned with the time constant of LED's, though. I don't know how fast you can switch them on/off

Traffic lights are usually LED these days. I once read that HP sends most of their LED's to traffic light manufacturers!

Another alternative is laser LED's in the projector.

Petter
 

vdi_nenna

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2000-10-10 7:27 pm
PA, USA
That's the spirit! Innovation, that's what I'm talkin' about!

But I wouldn't know a thing about controlling RGB LEDs to form images in a cluster. There is probably some computer controller that handles processing of a video signal.

I do know that LED Cluster screens need a minimum of 10ft from the viewer for the LEDs to be undiscernable.

Passing light through a LCD module is the route I'm taking.
With 48 ultra bright white LEDs I can get about 240 Candalas. (5000mcd each) 5cd x 48= 240. That's bright, but I'll have to see just how bright once it's passing through an LCD panel.

I'm hoping it will be bright enough to work in a theatre style darkened room. I'm not interesed in doing presentations with it, just entertainment!! ;)
 
BG Micro has White LED-5,600 mcd typ. LED1044.......$2.49 ea
http://www.bgmicro.com/lmad.htm
as this is in their Lets Make A Deal section bulk prices might be pretty good.

They also have a len system at:
http://bgm.bgmicro.com/prodinfo.asp...8142947&prodid=LEN1005&page=1&cri=LEN&stype=2
<i>"This "double throw down" lens assembly was apparently manufactured for a very large defense contractor. This assembly was one of the main parts of a "Buck Rogers" projection system, which was computer driven."</i>
at US$ 5.50 they might be worth investigating?

Hope this helps

Regards James
 

vdi_nenna

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2000-10-10 7:27 pm
PA, USA
Thanks James, I'll look into that lense. Late last night, while I was working, I went to the All Electronics web site. I found 3 lenses. I was so surprised. I picked up 2 of the 3. One was $5.50 and the other was $6.00. The last one was $55.00. I'm going to check out the 2 cheaper lenses first and look at the $55 one later, as there was no description for it. The lesser priced ones had nice specs.

I picked up 50 White Light LEDs from

http://www.whitelightled.com/ for $1.50 each.

I also picked up a 47 watt power supply w/ +12v @ 2amps output for $8 from All Electronics. That enough to power the LCD screen and 48 LED. It has a built in power switch. All I have to do is mount it in an enclosure and turn it on.

I'd like to get my hands on a condenser lense that will work w/ a 5.6 diag. screen to concentrate the light through it. I'm hoping the LCD has a Polarized screen on the front, it should on the back. But, do to the light orientation during normal operation, the light passes through the back, so I might need to pick up some polarizig film from Edmund Optics. I have a link for them in another post above.

I'm starting my vacation on Thursday. I hope to have some or all the parts by then! Putting the lamp together will take some time, but I should have something together shortly.

So far this experiment has only cost about $250. It has a good chance of working w/out too much more monitary input.

Vince
 

vdi_nenna

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2000-10-10 7:27 pm
PA, USA
Progress Report

Hi,

I don't know how much interest there is in this project, but I just wanted to let you know that my preliminary test have worked. I built the LED light source while on vaction...my girlfriend is the greatest! So far I have a cluster of 12 white light LEDs. I have 48 total, but only 12 going so far. I quickly set up the parts to a 12 volt power supply and it worked ok. I need to build a jig to hold everything steady, but there was a projected image on my (light green) wall :) I guesstimate it to be about 8 to 10 feet wide from 8 to 10 feet distance from the projector.

I found 2 projector lenses at All Electronics. One for $5.50 and another for $6.00. They were probably used for projection TVs or rear projection. You can see them on their web site.

I think I'm going to need to purchase a condenser or fernel lens to condense the light source to the LCD screen.

Anyway, I'm going to build a containment unit for this project tonight. I'll let you guys know tomorrow what happens.

later,

Vince
 

vdi_nenna

Member
Paid Member
2000-10-10 7:27 pm
PA, USA
Hey there,

Like I said, I only spent $250 so far. The light source
will last 10+ years if you leave it on day and night. Most other light sources will last about 2 to 3 years (2000 to 3000 hours), and start to go yellow before they burns out completely. The cost of replacing a metal halide lamp costs about $200 to $500 or more, and they are hot! I paid $75 for 50 of the brightest LEDs available. Best price anywhere. You can buy them as a kit from sites that I have posted in this thread for $200+.

But...I'm not going to get too ahead of myself here. There are caveats to this project, just like any other. Like light output and pixelation issues. This may only work in a darkened room, like a theatre environment- shaded room or 'night time viewing only' at worst case senerio. The pixelation problems can be helped w/ a corrective lense availible from Cygnus Imaging, but they are expensive, about 2 times the cost of this project. Or line doublers, like DVDO for around $500 to $600. But they need S-VIDEO or RGB inputs. I only have a composite input right now, but most LCDs have the ability to accept C and Y inputs (S-VIDEO). I haven't figured out how to do this yet, but I know a site where there is a forum where all they talk about is LCDs. This question has come up before.

I need to get my hands on a descent digital camera to document the process for my web site.

I'll keep you posted.





[Edited by vdi_nenna on 06-25-2001 at 12:21 PM]
 
I saw 2 cheap(?) condenser lenses at: http://www.goldmine-elec.com/
Catalogue Pages 69 & 70

Baush & Lomb Large Condenser len
This lens concentrates light into a projected beam for use in projectiors, spotlights, enlargers, IR systems, etc.
38mm made of Pyrex G8384 $5.95
or
Rectangular condenser 2.24" x 1.98" x 0.78" Focal Length approx 2.75"
G9576 $2.00 ea
they have a few other optical goodies you might like as well.


HowStuffWorks has a good section on Projection TV http://www.howstuffworks.com/projection-tv.htm
includes Microelectromechanical Systems, Grating Light Valve (GLV) and Liquid Crystal on Silicon (LCOS).

Regards
James
 
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