Converting video projectors to LED lamp ?

[N_Cook]

Like the ink-jet printer nonsense. Loads of nominally working video
projectors around where the lamp has worn out after its 1000 to 2000 hours
and a complete new projector is a little more than the cost of a replacement
discharge lamp .
Anyone done a conversion to high power LED emitter lamp? tips/pitfalls ?
Obviously a number of opto-coupler functions need fudging as well as
disconnecting the original lamp supply and HV ignitor sub-circuit
lamp supply input side optos , ignitor-on , lamp on, half/full brightness
output side optos , ignitor cct ok, lamp on (drawing correct current)
confirmation
Perhaps should only consider projectors that allow colour temperature
setting within the menu structures
any other considerations?
I just saw reference to this LED lamp cluster , anyone sen the spec of the
beam angle for it
http://www.ledengin.com/news-events/2012-08

 

[JB]

Like the ink-jet printer nonsense. Loads of nominally working video
projectors around where the lamp has worn out after its 1000 to 2000 hours
and a complete new projector is a little more than the cost of a
replacement
discharge lamp .
Anyone done a conversion to high power LED emitter lamp? tips/pitfalls ?
Obviously a number of opto-coupler functions need fudging as well as
disconnecting the original lamp supply and HV ignitor sub-circuit
lamp supply input side optos , ignitor-on , lamp on, half/full brightness
output side optos , ignitor cct ok, lamp on (drawing correct current)
confirmation
Perhaps should only consider projectors that allow colour temperature
setting within the menu structures
any other considerations?
I just saw reference to this LED lamp cluster , anyone sen the spec of the
beam angle for it
http://www.ledengin.com/news-events/2012-08

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

 

[N_Cook]

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

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)

 

[JB]

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.

Not of homogenous white light you can't.

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. ?

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 <40%. You simply can't get a better source
which can provide this level of lumen output.

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)

Comparing apples with oranges. A 200Lm (source lumens) LED projector is in
no way comparable to the output of an HID projector.

I'm not on a rant here! I'm trying to save you time and money and
considerable frustration. I have been working in the lighting industry
designing luminaires, lamps, and optics for over 30yrs and beleive it or
not, have gained some valuable experience in this time.


JB

 

[Adrian Jansen]

Like the ink-jet printer nonsense. Loads of nominally working video
projectors around where the lamp has worn out after its 1000 to 2000 hours
and a complete new projector is a little more than the cost of a replacement
discharge lamp .
Anyone done a conversion to high power LED emitter lamp? tips/pitfalls ?
Obviously a number of opto-coupler functions need fudging as well as
disconnecting the original lamp supply and HV ignitor sub-circuit
lamp supply input side optos , ignitor-on , lamp on, half/full brightness
output side optos , ignitor cct ok, lamp on (drawing correct current)
confirmation
Perhaps should only consider projectors that allow colour temperature
setting within the menu structures
any other considerations?
I just saw reference to this LED lamp cluster , anyone sen the spec of the
beam angle for it
http://www.ledengin.com/news-events/2012-08

More specs at http://www.ledengin.com/products/emitters/#LZ9

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.

 

[N_Cook]

More specs at http://www.ledengin.com/products/emitters/#LZ9

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.

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

 

[josephkk]

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 <40%. You simply can't get a better source
which can provide this level of lumen output.

Wow, a 400 W arc lamp. That is the rating and power input for that many
lumens for HID lamps. That lamp must power large screen movie theater
projectors. YCLIU

Comparing apples with oranges. A 200Lm (source lumens) LED projector is in
no way comparable to the output of an HID projector.

I'm not on a rant here! I'm trying to save you time and money and
considerable frustration. I have been working in the lighting industry
designing luminaires, lamps, and optics for over 30yrs and beleive it or
not, have gained some valuable experience in this time.


JB

I am not believing it.

?-)

 

[josephkk]

I still cannot find the half-power beam angle. It 15 degrees fine but if120
degrees then back to all the optics losses business

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.

?-)

 

[N_Cook]

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

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
http://www.acerdirect.co.uk/Acer_K11_-_DLP_Projector_-_200_ANSI_lumens_EY.K2
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