LED Projector?

[jborts]

My name is Josh Borts. I am currently working for a non-profit organization called GeekCorps Mali. We provide technology solutions to rural Mali in an effort to better disseminate important health and economic information. One such project is investigating the use of satellite televisions. The hope is that these systems will be used by a large number of individuals and as such a large screen is desirable. Purchasing a television with an adequate screen size is outside the budget of our operation and would not be suitable for the largely nomadic users. As such, we are investigating the use of projectors and have become interested in the cost savings that LED based systems can offer.

As you are undoubtedly aware, typical halogen based projectors burn through bulbs quickly and require costly replacements. We cannot burden these poor communities with such a technology. As well, the heat produced by the bulbs, combined with the hot and dusty working environment in Mali makes these projectors lousy solutions. Recently, I read of new projectors that will be built using LEDs. While these commercial versions are not yet available and are expected to be priced out of our range, we are interested in the basic concept. I have read about others attempting DIY LED projectors but have not found any successful examples. This combination should lower both up-front and future costs allowing us to complete our project goals without heavily taxing the Malian community.

Does anyone have any suggestions?

[ancorp]

Hi Josh,
And welcome to the Forum

About the bulbs - most projectors here use Metal Halide bulbs, very power and heat efficient, and cost about 30-40 $ (more or less...), plus will last 10,000 to 20,000 hours!!! A 100w MH bulb vs a halogen bulb wil be atleast 5 times brighter (right? no first hand experiencs, just reading...)

Cheers,
Alex

[SGSeeker]

It "MAY" be possible to build a LED projector out of the newest LED's (20,000mcd narrow viewing angle or the 15,000mcd with a wider) but because they only put out ~2-3 lumens, you would have to throw the whole 3200 behind a 15" lcd giving you a good 6-9,000 lumens to work with before dealing with light loss. A 17" would accommodate more but we still don't know how well LED light projects compared to standard bulbs. They're basically tweaked blue LED's so the color reproduction will most likely be poor compared to say a metal halide bulb. Also 3,000+ LED's WILL put out quite a bit of heat, draw a bit of current (60+ amps), and just the initial cost will be up around $8-900USD after the LED's, resistors if used, etc

I don't think they're worthwhile until they hit at least 5 lumens each for a standard LED and it still depends on how much light we can use per LED. If there's high losses through the lcd panel, then it may just be a lost cause

[Stocker]

There have been several long threads on this board, including one fellow who built his own, very small, LED-lit projector with results IIRC.

Try searching with any keywords you can think. I am afraid it may take a while to dig up the proper threads.

[jborts]

Thank you for the help. If what you say about Metal Halide bulbs is true then that would certainly be a good choice. Can these be used as replacement bulbs in commercial systems?

As for the LED system, I have looked through this site and was unable to find any finnished product. In any case, I have been in discussion with LumiLeds about their products. They have built a prototype mini projector using three of there Luxeon LEDs that outputs around 15 lm and should be capable of being raised to 24 lm. However, Metal Halides do seem like a better/simpler choice.

[SGSeeker]

the type of MH bulbs used around here wouldn't fit in a newer lcd projector since they're so compact. The only way would be to have the bulb externally and try to direct all the light in to where the stock bulb shines

yeah, I don't think there are any actual finished LED projects yet and even if you used a couple Luxeon's, you'd still have a really dull image. Think about how most commercial projectors are over 1,000 ansi lumens. If you're only starting with say 3x60lumen LED's, thats still only 180 to work with from the beginning, and probably around 50, at best, ansi. If I had $400 to blow right now, I'd try projecting my 10.5" lcd with 1500 led's and compare it to my 250w MH but until something like that happens, it'd be best to stick with whats known to work

[cbm5]

I don't see LEDs being a viable projection source quite yet. With the larger screens we use, it is more of a possibility, since the required power density is WAY off for use with the tiny elements in a commercial projector. However, if OLED screens get cheaper and brighter, we have a screen that actually emits light on its own. Obviously the brightness would be far beyond what people would normally want to look at, so I don't know if we'll ever be able to use a OLED monitor for this purpose. Another possibility is somehow creating a sheet of mass-produced miniature LEDs, which could be used as a very bright diffuse source. Again, probably not something that will ever be produced en masse, and cheaply.

One more possibility, probably the most expensive of all unless mass-produced: make the screen itself active. Each element would be independent except for power and ground planes. The element would sense infrared and translate to an RGB spectrum depending on the wavelength of the IR. So you project an invisible beam, no great intensity required, onto the projection surface and the surface itself lights up with the image. The advantage of this is that every element on the screen is identical, so you could tile as many sheets together as needed. Also, there is no massively complex control scheme needed to power and modulate the RGB LEDs. Granted, this is nowhere near DIY possibilities. But it's one way displays could go.

[Stocker]

you have to have been here to read the thread to remember the keywords to search for.

Witness a successful LED lit projector.

Successful LED/PSONE projector.

dang, no screenshots! Where is this cat anyhow?

[cbm5]

He dangled this in front of everyone and then never showed any pictures of the resultant image. Maybe he sells Luxeons?

[Inkog]

For your efforts in "disseminating important health and economic information" to rual areas, I would think a standard overhead projector and LCD projection panel designed for this use would be your best bet. These can be purchased very cheaply, <$300 USD for both, and readily available, even over seas.

I think a DIY projector is a little overkill for your needs.