Lightsource for DIY LCD Projector 34
xpndsprt asks: "I'm trying to develop my own projector (i've been reading DIYAudio forums for a while and finaly decided to put together my own), but it seems that people are having problems with light source. The Slashdot crowd seems to always have interesting answers to problems at hand, so to get to the point: Does anyone know of a powerful lightsource (200w+) which would produce a high temperature light (5000K+) and would not heat up too much (ppl seem to be using mag.Hylide bulbs, but those seem to heat up tempreture in the room by about 10F. Xenon lights are out of question, since too hot and not bright or white enough. If someone could help, it would be greatly appreciated."
A few [cheapass] ideas... (Score:3, Insightful)
White LED's? lots of them. Probly not so cheap though.
Some old scanner bulbs? If you look in the right places you might be able to grab a few. AFAIK they are pretty cold.
Theft. Find a suitable projector light source at work, disconnect it inside the case. Complain that it's broken, get a replacement, reconnect the wire, pocket the brand new bulb :) Repeat as necessary.
Ali
Re:A few [cheapass] ideas... (Score:1)
Re:A few [cheapass] ideas... (Score:1)
The 'bulb' was flourescent. Why not a flourescent bulb of some sort. RealGoods, and some of the efficent energy companies sell extremely powerfull flourescent bulbs, and they stay fairly cool. I am not sure if they are powerfull enough, but its worth a try.
Overhead projectors? (Score:2)
LCD + OHP (Score:4, Interesting)
Fat boy Matt made a network controled version [man.ac.uk].
Re:LCD + OHP (Score:1)
Re:LCD + OHP (Score:1)
cheers,
kitsch
Re:LCD + OHP (Score:2)
200W in = 200W out (Score:2)
Re:200W in = 200W out (Score:1)
Re:200W in = 200W out (Score:2)
Or am I wrong about this? IANAPOAE.
Re: 200W in = 200W out (Score:1)
200W input == 200W output == (x degrees heat + y Lumens light + z Watts other energy)
The trick this project needs is to find a light source that outputs a given number of ANSI Lumens (as I believe they're called), but that doesn't give out heat (or any other form of energy, such as sound or motion!)
Re: 200W in = 200W out (Score:1)
You can find many bulbs that are very bright, but don't consume nearly as much juice as an incandesant bulb of the same brightness.
Just stating the obvious (Score:3, Interesting)
Having said that...
The only high color temperature light source you'll find suitable for this type of work will be arc lamps. HMI, MRI, HID, etc. In terms of heat:light output ratios, arc lamps put out the most light per btu of heat of any other point source lamp. Point source is important. Light from a diffuse source (flourescent, multiple LED, etc) is nearly impossible to deliver through optics in an orderly fashion.
As you've probably found, getting the lamp is easy. Matching it to a suitable power source is difficult.
Additionally: No matter what lamp you use, your LCD panels and optics will also need some cooling
Once again, I've been of no help.
HID Light Source (Score:1)
Expensive. This thing is $400. But, it's 1/4 the power (and heat) as halogen
Big. As the parent stated, the ballast for these things is important.
Not too good on the color rendition. It's important to remember that you don't just want to look for color temperature, you also need to make sure that the light gives good color rendition; that it has good spikes not only on the blues, but also the reds and greens.
Good luck...
Three suggestions: (Score:3, Interesting)
Well if that's a +3 from a high-karma user... (Score:1)
Is there an echo in here?
OK where was I? Oh yeah, explaining the sheer stup^H^H^H^Himpracticality of trying to use the sun as a light source for a projector.
First off, you need to gather the light, the best option being a huge mirror: a bit unweildy. It would have to be reflecting the sun directly into the projector, through a screen to diffuse the light so theres no light/dark areas, then through the slide and onto a screen. A fair chunk of light would be lost that way, but it might suffice for a very dark room. the mirror would also have to move to track the sun.
And you're almost certinly gonna need line of sight to the sun, which could be screwed up by blinds [meaning excess light in the room], being in an internal room, furniture, wrong side of the building, other buildings, clouds, and night time! Oh and you'd need L.O.S. from the mirror to the projector.
If your post was just the Sun suggestion, it might have been worth a +3 Funny.
Ali
Re:Three suggestions: (Score:1)
Re:Three suggestions: (Score:2)
-russ
hmm (Score:2, Informative)
its hard to get enough in a small enough space to do much good, and you would require at least 75-150$ worth to get enough light to use the projector in daylight.
IF you had enough space, you could group 150-200 white LEDs in a tight slightly curved mount the same arc as a compressing lense , then focues that light onto a diffuser, spread the beam to a freznel the size of your LCD screen and hope for the best.
this would get expensive as a set of high quality lenses would be in the 100$ price range and 200 LEDs would run about $300, plus time.
though youre light source would be good for 150,000+ hours, and would just slowly degrade when the LEDs got old and failed.
and powering 200LED lights would not be too difficult, with the use of a PC power supply you can have 3.3/5/8.3/10/12/15.3/17/20.3/24 volt outputs , enough to drive many arrays of LED lights without any problem.
Over-clocking LEDs (Score:2)
Steve
Suggestions (Score:3, Interesting)
Which is to say: A 200W light bulb may produce various amounts of light at various levels of quality, but will always produce 200W of heat.
Your best bet? I'd vote on hitting a DJ supply store (or a guitar shop, or audio rental place - wherever you find musicians, DJs, or both) either online or locally. Note, however, that if all they have is a collection of PAR cans (glorified coffee cans with common flood lights), you're in the wrong place.
More complicated DJ lights have to deal with the same problems you have: efficiency (heat inside the fixture), color temperature, lifespan, cost, and durability. They need to be close to point-source, so that the gobo patterns they project will be easier to focus. And they need to be extremely bright.
I, once upon a time, had a Martin Robozap mounted on the wall at home. This fan-cooled light weighs 20-25 pounds, IIRC, and has a servo-driven mirror with two 150W overhead projector bulbs aimed at it. Whenever I fired it up, I had to increase air circulation in the room else it would get terribly warm, fairly quickly. I imagine the same would happen with a 300W floor lamp...
Locally, the bulbs were fairly expensive, but I was able to find the type online for ~$10 from some specialty lighting shop that primarily just sold light bulbs. They were a halogen bulb, with an integral reflector. IIRC, it's a pretty common type for overhead projectors.
Speaking of overheads, why not use one? You've appearently got an LCD display - just lay it on top of an overhead projector. Should be cheap, if buying used. Just clean up the optics and re-arrange the innards so that it's concentrating as much light as possible on the LCD display, and things should be peachy.
I hope it's obvious, but it appearently isn't because at least two posters have mentioned it: don't use white LEDs. You'll -never- achieve even satisfactory focus using an array of LEDs, let alone good focus. Now, if it were possible to make them bright enough that you'd only need one for the project, it'd be a different story...
Photographic Enlarger (Score:2, Insightful)
Distributed light via fibre-optic? (Score:3, Interesting)
I can't take credit for this - I seem to recall seeing a diagram years back suggesting this for a car, with a central light source feeding all the car lights. Google searches bring up these links:
http://www.halfbakery.com/idea/Fibre_20optic-lit_
http://www.ind-auto.com/news/sept2000.html
Matt
Think Lumens, not Watts (Score:3, Insightful)
The mount of light that is output by a light source is measured in lumens, not watts. Other posters have mentioned that all light eventually gets converted into heat, but some light sources are more efficient than others when it comes to how much actual light they produce for a given unit of energy consumed (think watts). You need to identify how much light you need (in lumens), and then find a light source with a low lumens/watts ratio that produces enough light at the right spectrum to satisfy your application.
HID Lamps (Score:2, Interesting)
Advantages of HID lights are: You can mount the ballast remotely - this help because the ballast generates almost as much heat as the bulb. The bulbs are relatively small, though certainly not as small as a halogen. HID's make lots of light for the amount of power they draw - ie: a 400W HPS (High pressure sodium makes 50,000 lumens, while a 100W incandescent makes about 2,000 lumens - that's 125 watt/Watt for the HPS and 20 lumens / Watt for the incandescent).
The three popular types of HID lamps are metal halide, high-pressure sodium, and mercury vapor.
Only drawback here is that the color temp stinks. You will have trouble finding bulbs that do better than 2500k. You might want to look into something called Sun-Argo, which is a HPS / MH hybrid kind of thing. You also might want to look into something called compact fluorescents - these provide a better color temp, but unfortunately, they are florescent, so they are kinda big.
Good Luck.
Try this! (Score:2)
The theatrical discharge fixtures usually have a lower color temperature (3000-4000k), but you trade that for cheaper, longer lasting lamps and better lamp availability.
SD