A LED lifetime tester

[Longbow]

Re: A LED lifetime tester

But regarding LED failures in recent TV's, I am sure the makers will have done their homework. The LED's will be being pushed close to their limits with the knowledge that, statistically, some will fail. But the cost saving on a large production run will hopefully (for them) outweigh that of an occasional warranty claim.

I disagree. Running backlighting LED's at or above their maximums in a hot, enclosed environment isn't exactly great engineering. As usual, the final product development stages are conducted by the end user. One great example of that approach is my cell phone which just underwent an O/S upgrade. All of a sudden my battery would be dead in 3 hours. Oooops, sorry we screwed up. There's another update waiting that will fix that now. Or...modern consumer submarine control panels all ship out before the firmware is even done. They arrive with half the features disabled. That's another story.

[RJARRRPCGP]

Re: A LED lifetime tester

This is looking good! I may be able to replace all my lights with those guys!

http://www.soraa.com/about/company

Looks like I can say "buzz off!" to Cree and Philips! (Because their LEDs are made in PRC)

[RJARRRPCGP]

Re: A LED lifetime tester

This is looking good! I may be able to replace all my lights with those guys!

http://www.soraa.com/about/company

Looks like I can say "buzz off!" to Cree and Philips! (Because their LEDs are made in PRC)

Not available until spring... Must wait, folks...

[Jack Crow]

Re: A LED lifetime tester

CW
If I may draw back to your first question...

"2 LG and 2 Samsung LED TVs bring-in (different time over this year), said LED screen blinking, TESTed all day worked, I charged the full repair bill by doing nothing, BUT I gave them one year warranty.( those tvs will come back eventually) How can you do? I need build A LED lifetime tester, (A equipment will show in the future of which LEDs will not work.)!, can anyone HELP!!!.."

Lifetime tester for an LED.

Are you young enough to have ever done any color photography at home? At one time it was a fairly exotic but not too strange thing to do.
We had 'color heads' for various enlargers with special lamps that kept the came color temp (degrees kelvin if memory is any good) and special filters to make it all come out right.

As the bulbs would age, the color temp would drift. The system would have to be re balanced every so often.

My question is, do LED's change color over operating life?

The idea for a quick and dirty test would be to fabricate up a cheap spectrum analyzer for the LED.

AKA run it into an optical prism.

Look up the cover art for Pink Floyds "Dark Side of the Moon" album will give you the idea.

https://www.google.com/search?q=cove...siiGc-seL3M%3A

White light goes into the prism, and is broken out by spectra.
Welcome to cheap optical spectrum analysis.

Now let's do that with a single frequency solid state laser.
Bet most of the energy stays on just the one spot.

I have no idea how many 'colors' are mixed to give us a red, green, or blue LED effect.

But if you can establish such a rig, have it shine on a wall in a darkened room, you could make pencil marks where the color (s) show up. Let it run for 100 hours and see if the colors shift over time. It might give you some kind of baseline as to if the color is shifting due to operation.

It's the only test rig that I can come up with that can be done on the cheap.

These are not at all cheap but it's the first thing that came to mind. For example you may not want anything with UV or IR absorption in it.

http://www.edmundoptics.com/optics/p...e-prisms/3406/

This is more along the lines of the real world.
http://www.ebay.com/itm/Neewer-4-Opt...0AAOSwV0RXqpul

Anyhow it's an idea.
Lots of good information in old Kodak photography books. Color charts, 18% gray scales. More than you ever wanted to know about the quality of light.

Hope that helps
Jack Crow in Virginia Beach.

[capwizard]

Re: A LED lifetime tester

Love your ideas, If I use prism to check each LED in the screen, pretty quick I will have monochromacy sight! .......... ..............

"My question is, do LED's change color over operating life?" No! LEDs just fade away.

"a cheap spectrum analyzer for the LED.White light goes into the prism, and is broken out by spectra. cheap optical spectrum analysis."

With this cheap a single frequency solid state laser optical spectrum analyzer, we can find out the LED which layer doping of semiconductor has inferiority and causes the problem.......but I think this is the project MIT is working on it....