Converting video projectors to LED lamp ?

Don't even bother. It is totally impossible to retrofit an off the shelf LED 'light engine' into the existing projector optics. You *will* be wasting your time. The original short-arc, ultra-high pressure mercury or metal halide lamps will have lumen outputs typically 20-30x the best you could achieve with an LED 'cluster'. Even if you got the lumens from the LEDs, the optical source 'dimensions' would be far too massive for the existing lens system to focus on. The thermal issues would be 'interesting' too as you would be looking at at least 200W of LED to achieve anything like the original screen brightness, even with an optical system matched to the larger LED source.

JB

hours

brightness

the

LED

the

The active window for the colour wheel / light tunnel is usually of the order 10 mm diameter. At least with a single LED cluster you can direct the majority of its light into that 10mm aperture. Compared to discharge lamp , not point source, reflected off non ideal dicroic reflector with an open-end diameter of the lamp reflector 60mm or larger, how much of the discharge lamp light gets to the 10mm active window and how much is wasted. ? Off-the shelf current generation of manufacured projectors with LED lamp sources rated 200 lumens are sufficiennt for 6 foot diagonal screens in dim not dark rooms,(room-light level where you can just read a book)

Not of homogenous white light you can't.

These short arc HID lamps with integral ellipsoidal dochroic reflectors are about as efficient as it is possible to get for this type of application. when you have a bare arc-tube producing 25-35kLm, who cares that your optical efficiency is typically

More specs at

But 1300 lumens is still a long way from a typical video projector. eg the NEC NP64 is supposed to put 3000 lumens on the screen, that includes all the optical losses along the way.

--
Regards,

Adrian Jansen           adrianjansen at internode dot on dot net
Note reply address is invalid, convert address above to machine form.

hours

replacement

brightness

the

I still cannot find the half-power beam angle. It 15 degrees fine but if 120 degrees then back to all the optics losses business

the

direct

or

are

application.

tips/pitfalls ?

current)

temperature

of

eg

includes

120

Due to the physics of the bare LED, about 45 to 60 degrees. With the fancy lens maybe 20 to 30 degrees, but that is a WAG.

?-)

? 120

Due to the physics of the bare LED, about 45 to 60 degrees. With the fancy lens maybe 20 to 30 degrees, but that is a WAG.

?-)

++++

As that light source can be placed within 2 or 3 mm of the apertured mask over the rotating colour wheel then sounds promising. If like a short arc lamp , has to be set back 50 to 80mm then that 20 to 40 degrees would be a no-no

I've seen a powerpoint presentation via one of these

801.001/version.asp in a dim but not dark room and was perfectly acceptable, allowing for the poorish resolution. Certainly not a jokey gimmick gadget