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LED Replacement for LCD projector Bulbs
radiojock asks: "OK, I've got a question -- has anyone ever seen a way to replace a LCD projector's bulb (they burn out way too easily) with the new superbright LEDs ? this should be very possible, take a group of the LEDs and mount them on a board. Would this be able to replace the bulbs? And would the LCD projector manufacturers allow this? Think of the energy savings, and the heat reduction ... Just a thought." I would pay a lot of money for such a replacement bulb, and I suspect a lot of others would too -- which leads me to suspect that such LED arrays really aren't ready yet, or they would be on the market. I hope someone can contradict this -- are LEDs up to the task? I bet the LCD manufacturers would be eager to supply them if so.
with a magnesium-burning chamber. You have to do daily refills of magnesium powder, but man, what a bright projector you'd get!
I think you would need a minimum of 50 LEDs.
LumiLeds Lighting Produces 17 Lumen White LED
But projector bulbs seem to start at around 1000 lumens and some projectors go up to 5000
http://www.thehungersite.com
There are a few reasons why you couldn't do this:
/very/ specific wavelengths. The color filters on the LCD will likely NOT match the LED colors closely enough to produce a good rendition. Projecter bulbs produce a nice even and wide band of wavelengths from just below visible to just above visible.
1) Even superbright LEDs are not nearly bright enough. Find your favorite LED manufacturer, and check out the specs. The projecter bulbs are several hundred (if not thousand) of times brighter than even the brightest white LED. The array would be huge.
2) Superbright LEDs are not true white. They are white one of two ways: either three LEDs in the package (RGB) or a blue LED with phospher to emit RGB. So what? Well, the colors emitted by an LED are
3) Lastly, the lenses in the projector are designed for a specific shape of light, whether it's point source, straight filament (and orientation), bent filament, etc. You'd have to add your own lens system to make an array of LEDs look like whatever bulb you're trying to emulate, and it likely won't fit into the space set aside for the regular bulb.
In short, you'll end up trying to fit a round peg into a square hole. Not only will it not fit, but it won't work well if you can make it fit.
You'd spend far less money and time buying a few bright 19" screens, setting them up in array, placing fresnel lenses in front of each of them, and lining everything up perfectly so their images overlay each other (for brightness). And the monitors are rated for a lot more usage... Of course, you couldn't call it portable, but you now know how much portable really costs.
-Adam
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Two tips to make the bulbs last longer:
- when installing a new bulb, go to extreme measures to avoid touching the bulb directly; use a piece of clothe, etc. The reason is that the oil on your skin will stick to the bulb, and when heated with cause a non-uniform distribution of heat which causes the bulbs to die more quickly
- turn the projector off if it won't be needed for a while. It's easy to forget, but don't leave the projector running if it won't be in use for a while. This seems like a silly thing to say, but a lot of people forget about how fragile the bulbs in the projector are.
I bet the LCD manufacturers would be eager to supply them if so.
I doubt that. How many LEDs are bought on a day to day basis? How many do you have in your home, your work, the shop you use for supplies and so on and so forth. There's a lot of LEDs in the world - and more every day.
The increased revenue from making a few million LED 'bulbs' is hardly worth the effort of developing it - especially since they won't burn out for a long time.
Ian Woods
LCD projectors are actually extremely picky about bulbs. Not only is all of the above true, but the spectrum of light is especially critical as projector manufacturers "tune" the LCD based on the light they expect to have coming through it.
This is why a cheap (off-brand)replacement bulb will sometimes cause a slight tint in the picture no matter how much you play with the color controls.
You could, in theory, redefine the light parameters used by the projector, but I've never heard of anyone even trying.
The turning off is a valid point, but just as with car engines and computers, the heating and cooling cycle does damage to a bulb as well. I don't know of a good rule of thumb (and I'm sure it varies from one type of bulb/projector to the next) but if I'm not using it for only ten minutes or so I probably wouldn't.
Over a half-hour, then definitely.
Twenty-minutes? That's a toss-up...
Dude, your site's down.
The highest power white LED announced so far has a 17 lumen output with one Watt input. This is a much lower efficiency that is achieved by arc lamps, so to get equal screen brightness the LED's would actually produce more heat. If you wanted to project onto a very small screen it might make some sense.
50 LEDs seem like a lot, and whether there would be more or less heat with that many LEDs would probably be an issue...
But what if you made a "light box" of some type, that had the LEDs in the box, focused and/or collumnated via a lens arrangement, then fed the light to the projector via a light pipe or fiber optic bundle? Would such a contraption work?
Seems impractical, too me (and I thought the thing up), but interesting, all the same!
Reason is the Path to God - Anon
This is probably the kind of thing you're talking about; this is definitely NOT the right size to put into a projector, but it could be adapted. The advantage of this one, being RGB as opposed to white, is that it's very easy to achieve the right color balance. The manufacturer would probably need to get a custom run of the LEDs to match the LCD wavelengths, but that wouldn't really be all that difficult... just a matter of changing the doping materials in very minor ways...
I am disrespectful to dirt! Can you see that I am serious?!
Halogen light bulbs (as used in most projectors) will actually not last as long if you run them at a lower voltage. There's a cutoff point at which the halogen scavenging doesn't work anymore, and the filament will plate out on the bulb...
http://www.theledlight.com/ They seem to be willing to engineer solutions.