# How could I replace the lamp on a regular projector for a LED lamp?

I have a 1080p projector and I want to change the regular 230w lamp for a LED lamp that uses less energy and lasts longer.

How complex would this be? LED projectors with these specs are ridicously expensive, but only a few unknown brands offer them. Some have design issues and overheat or break.

I don't know why most companies don't offer these, maybe the money is in spare bulbs which can be as much as half what a new projector costs.

• Projectors tend to be designed for specific bulbs. While it's nice to save power and have longer life, this is not a place I would do this unless the manufacturer specifically lists a LED replacement. – Olin Lathrop Dec 3 '11 at 16:35

You'd need to provide brand and model of projector and bulb plus web links.

What you need to know, at least, is ANSI lumen rating of projector and present technology and rating.

All that said, this is getting more viable but is not something attempted lightly. The fact (as you recount it) that available solutions are from unknown makers and that they don't work may be because the conspiracy theory re bulbs is correct, but may also tell you something re difficulty.

Modern data projector bulbs are often "HID" (High Intensity Discharge) technology which is also found in car headlamps. This uses a small arc in eg Xenon gas with extremely high voltages and control gear to operate. (Bulb resrike when hot may required 10 kV+). HID bulbs for automotive use MAY provide a chaper projector solution but also may not - they are also qite expensive - but not as bad as projector bulbs generally.

Assume you have a 2000 ANSI lumen projector. This used to be a high spec but now is only OK for home theater etc. Assume that 50% of your 'bulb' light gets to the screen. That may be optimistic. Modern leading edge higher power LEDs are approaching 150+ lumen/Watt delivered. More realistically if you am at an out-of-module level of 100 l/W you are doing OK. So the LED wattage needed =

• Power = lumen x 2 / lumen-per-Watt = 2000 x 2 / 100 = 40 LED Watts.

In production volumes you can get a good LED for say $US1.50 for a 5 Watt unit - maybe cheaper. So LEDs alone would cost say$12 at the factory door or a retail cost of say 4x to 5x = say $50. Add support gear and that is liable to be hundreds and you are back into HID bulb cost area roughly. BUT that's not a tiny die size. You need to mount these so they constitute a point source comparable to a HID so ideally you'd pt those in a package yourself. If not (mot f us have problems packaging LED dies ourselves) and you wanted to mount them using available LEDs you'd probably be lucky to get under 3mm x 3mm LED positioning or for 9 in a 3x square say 9mm x 9mm. That's larger than a HID arc so the optics would not work so you are up for new custom optics to make a small linear (parallel beam) light source - a not modest lensing requirement. As well as "just doing it issues" you need high CRI (maybe mixed phosphors and special LEDs), good colour temperatures (links with CRI), drive electronics and more. You now have to cool it. LEDs cost$ (as above) a moderately large amount and yu want reasonable longevity. Say you opt for heatsink temperature of 50C. You need this in a housing that raises ambient and you want to be able to run this in Phoenix or Sammerkand or Nairobi in summer (maybe not Stovepipe Wells) without trashing the lamp. Say a modest 30C ambient. So delta t on heatink is 50-30= 20 C. So heatsink need is 20 C / 40 Watt = 0.5 C/W. That's a VERY nice heatsink, unless you have to pay for it. You'll certainly want to go to some lengths to stop hot spotting near the heat source. Heat pipe quite possible. Mere liquid cooling to a secondary air cool possibly. Blown air in volume certainly as well or alone.

Stop!

This is getting hard. There is a risk of these being ridiculously expensive and of having design issues and of overheating and breaking. Sounds familiar, no?

ie this is a demanding task. It can be done with existing state of the art LEDs and state of the art cooling and worse - but HID does a nice job and people are paying for them unhappily but as required. So it's a technology whose idea has just about come. Expect to see the great and capable Philips Gloeilampen Fabriken company who lost their way somewhat since starting 100+ years ago but who have now returned to being masters of their original field, come up with something suitable any year now. (They will label it Luxeon / Lumileds.). Cree will be there. Also Osram. Soon also Seoul semi. Nichia maybe (they can afford to live off the patents from the rest). HP under another name. Maybe Siemens under another name. And others.

The chances of you successfully joining them with a cost competitive trouble free product at this stage is low.

Double Flying Horse brand will be there but the LEDs will fail very early, colour temperatures will be suspect, die matching marginal, actual light output down, unforeseen technical problems excessive. You can buy them now.

• +1 Nice writeup. Also add the fact, that light path, and the overall dimensions of the projector casing were designed for the existing light source. Changing to a different light source most likely mean you have to heavily modify the casing of your projector just to fit the LED, cooling, and driving gear... – Akos Lukacs Dec 4 '11 at 9:26
• Six years later - if the the original author is still on line I would look forward to an update. I see 2 new developments: 1) 100W LED COB arrays are ~$20 and less. So making the switch is much cheaper and easier. But 2) the price of projectors has dropped. Some, albeit unsuitable for computer monitors, to less than$100. – st2000 May 9 '17 at 12:38
• @st2000 Present! :-). I have noted progress but not looked at practical implementation. You can now buy commercial LED based projectors including lowish cost Chinese sourced ones. My comments re cooling and light aperture still apply. It would be interesting to look at current commercial offerings to see what they do and what design compromises they make. – Russell McMahon May 9 '17 at 14:31
• @RussellMcMahon, do you still hold to the guess that 50% of the lamp light makes it to the screen? I have not been able to find the lumens of a lamp I want to replace with an LED. But the projector is listed as 4000 lumens ANSI and the 100W LED I've been looking at is about 8000 lumens. – st2000 May 9 '17 at 23:44
• @st2000 The 50% was an engineering guesstimate and depends greatly on the optics. A single lens or reflector will typically lose you 5-10% but much much less loss is possible but usually at great v\$. This Cree XHP70 is rated at about 1800 lumen at about 30 Watts with a dome emitter about 6mm dia (7mm truncated) and a near 180 degree radiation pattern but a large %age in the +/- 50 deree range. Trying something like that may be interesting and maybe even useful . ... – Russell McMahon May 10 '17 at 8:35