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LED Replacement for LCD projector Bulbs

Posted by timothy on from the pipedream-but-a-good-one dept.

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.

3 of 20 comments (clear)

  1. 50 by Karma+50 · · Score: 2, Interesting

    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
  2. LEDs aren't ready yet... by stienman · · Score: 5, Interesting

    There are a few reasons why you couldn't do this:

    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 /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.

    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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  3. LED output power doesn't match arc lamps by lotsolens · · Score: 3, Interesting

    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.