SEP 25

Even though it involves the use of Cadmium I think it's a great green step forward.

They may have Cadmium in them but much like CFLs last longer than incandescents, don't LEDs last even longer than CFLs? I have a couple devices from the 90s with LEDs that still work perfectly. So theoretically because of their longer life span less of these will be thrown out. With their lower energy consumption and low heat output LEDs should take over once they can manufacture them at a reasonable price.

PS: Don't forget to attribute that image! :)

http://en.wikipedia.org/wiki/I...e_LEDs.jpg

Also, isn't cadmium very expensive? I know cadmium based pigments are ridiculously expensive, and even in small quantities it can't be very economical.

Lets just hope adding these chemicals doesn't have some weird side-effect 30 years down the track when everyone has been under their light each and every day.

Is 70,000 hours really that long of a life. Seems like if corporations made incandescent lights correctly, with a pure vacuum, instead of tainting them with some oxygen, they would burn forever. I know some have been burning for a long time, those made in the old days. Russian bulbs reputedly last a *lot* longer than bulbs made in the US.

That's right, we can attain a pure vacuum.

Oh wait, no we can't. Your bad.

how big is a LED? i mean the actual diode? it is smaller then a pin head. the rest is just colored plastic. the cadmium would be sealed in plastic. unless someone chews on it there will not be any problem. and like plama screen, they do not leak. even if it used platinum, the amount is soo small in comparisson to the rest of the LED. yes there is a price increase. but not big. oh hey guess what, you know integraded circuits? like CPUs and GPUs? guess whats on the inside? gallium, arsenic, GOLD!!!! and there is neve a problem cuz it is sealed in silicon. oh and in circuit boards... high tech ones (a comp mobo is low tech I have worked in a circuit board facility so yes i would know) like telecoms and cell phones, the wires are copper and plated in GOLD!!! oh noes!!!. you know those air ionizers... STOP THE PRESS THEY ARE PLATINUM PLATED!!!!
basically they article mentions they are currently inefficent and thus they dont commercialize it yet. no ware did it mention safty, enviromental or cost an issue.

Led's are being sold in the USA and Canada. I found this web page where they are available at reasonable prices now. www.ledKoolight.com
there is a full range and all of the specifications are listed there as well as charts and graphs of light output and longevity. regards. Nick

Wikipedia sucks HUGE Donkey's Balls!! 8)

ther is no oxygen. the white hot tugnsten would burn instantly. the air in ther is an inert gas. most commonly argon. this has been done since the beggening. actully 11 months after edison introduced his bulb. yes bulbs can be made to last longer but they are inefficent. even moden incadecent bulbs are 8% efficent. CFL are between 40-60%. LEDs are in the range of 80-95%.

White LEDs were invented years ago. They're already out in the market for sale.

http://www.thinkgeek.com/clearance/7aa8/
http://www.ccrane.com/lights/led-light-bulbs/index.aspx

Chris.
How right you are. Here i am viewing this on my LED backlit LCD Screen'd Apple Macbook Pro.

I've seen white LED's before. Can you quantify "whiteness"

Mmmmmm, Cadmium....love chocolate bars.

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Sancho: "the cadmium would be sealed in plastic. unless someone chews on it there will not be any problem."

Like plastic is eternally harmless. And when the plastic polymers break down, releasing hormone altering toxins, and the cadmium is released, our great(x10^3) grandmutants will be really happy about your musings.

Currently, white LEDs actually emit ultraviolet but have added materials that fluoresce with a white spectrum.

This development is significant because the energy is emitted directly as white light, so not as much energy is required.

I'm going to have to disagree. We haven't always had white light from bulbs. Generally incandescent bulbs emit far more yellow light, same with early generations of fluorescent. While fluorescents have gotten nice and white, incandescent bulbs have always needed a blue coating on the glass to fake the white color. Even those frosted bulbs, look right at them and you'll see yellow in the center.

Seems Indian scientists are in the news lately, good deveopment, dr from bangalore devlops HIV destroying enzyme few days back and now white LED developed by Indians, thats really GREAT !

Led's are being sold in the USA and Canada... but where can i find some of this in europe ?

"LEDs are in the range of 80-95%."

No. LEDs are NOT more efficient than compact fluorescent, or HID lighting ... yet. The best output currently appear to be the Philips Lumiled Rebels at somewhere around 75 lumens per watt (http://www.luxeon.com/pdfs/DS56.pdf). HID lighting and can yield around 100 - 150 lumens per watt, and CFL can be around 80 - 100. This also ignores the fact that, even factoring in the service life of LEDs, the total cost of ownership is about twice that of CFL.

This article is about what is commonly referred to as the CRI (Color Rendering Index) of a light source. CFL lamps are in the 80% complete range while tungsten is closer to 100% complete but lacking in blue. What this all means is that the range of frequencies in these new LEDs is complete. That is, it has a broad spectrum of red, green, and blue primary colors.

In the past, LEDs only made one color. Red, green, and blue can be combined to make white, but there may be frequencies missing between narrow RGB bands. Those missing frequencies will make the light seem a bit colorless. It will not make colored objects look the same as if lit by sunlight. Yes, it is possible to quantify what makes white.

LEDs are more efficient at lower wattages and can attain very impressive numbers but the efficiency goes down at higher energy levels. The area where white LEDs will provide benefit is where point sources are needed. Small spot lights like those under cabinets or in track lighting that illuminate something like a wall portrait don't really work with CFLs. CFL lamps are a very general soft source of light and aren't good for projecting a beam. They also are impossible to make very small. As you know, LEDs can be very small and cool while making a respectable amount of light. CFLs always will need a ballast which makes them large.

There goes Amateur astronomy. y dont they stick with narrowband leds??

I concur with comments above,
white LEDs already came out a few years ago. I have a white LED flashlight.

"I've seen white LED's before. Can you quantify 'whiteness'"

Yes, you can. It's color temperature. The white of an incandescent lamp is fairly high, about 5500K, while the bluish white achieved from mixing a red, blue, and green led (the most common technique) is much lower, around 3,200K (think of those bluish white headlights people see occasionally).

This is not the first attempt at white led, either. Others make them already, and some have developed a coating which makes the white light achieve that 5,500k temp that is so desirable. The difficulty there is that it is difficult and expensive to apply.

Close, lighting guy, but you have your color temps and the associated color backwards. The bluish light from the newer xenon headlights is actually closer to 5500K, while traditional incandescent lamps are around 3200K.

It's a bit odd that what people call the "cool" blue-white color is the higher Kelvin temperature, while the "warm" yellow-white has the lower K temp, but that's just the way it is.

That's certainly an eye-catching ad off there to the right. I might get in trouble with that on my screen at work, though!

The most common white LEDs are *not* three-chip units - they're usually a single blue LED with an appropriate amount of yellow phosphor. "Incandescent white" (i.e. yellowy-white) LEDs have been around for quite a while as well, although they're not true full-spectrum devices.

Great idea, but, Cd is super rare. It will cost a lot to produce a cheap Cd LED.

not to mention all the Zinc!

Where do they plan to ship these.? Cadmium is restricted under RoHS directive.

The article doesn't provide much detail on the spectral output of the new LEDs, but we must assume they produce balanced amounts of red, green and blue. Thus, they probably produce a spectrum similar to a good fluorescent lamp, which is very spiky, not smooth. CRI is a poor judge of "whiteness", since it uses incandescent light as the ideal. Very yellow-looking light from a table lamp gets 100 CRI. Gamut area and full-spectrum color index are two other measures of color appearance that are often more accurate.

Thanks to Railer@Digg for the link to the journal article about this technology. The spectrum they show actually is one big hump rather than three spikes. Interesting.

Confused because when I adjust the color temp on my raw images in Adobe Photoshop's raw image editor, raising the Kelvin temp makes the colors warmer, not colder.

I appreciate the work of indian scientists and wish they come up with a better descendant of Edison's Bulb ;) . As far as limitations are concerned, restrictions on cadmium can be lifted and it can also be made economical in a number of ways.

I feel the world is slowly but gradually gaining some pace in getting things right for Mother Nature :)

Since when were people worried about cadmium? NiCd batteries have been used for years, have shorter lives than LEDs and contain much more cadmium!

High power White LED's already exist, and have so for quite some time.
I have used a few over the last 4 years.
google lumileds, those are the main ones we use.

I even have a high powered white led bike cateye flashlight.

This just sounds like a company trying to promote its products, and not really a breakthrough. :P

I've got some friends that are lighting their house with LED lighting, but they need AC-DC transformers all over the place, which really adds up the expense and bulkiness. Ideally, homes would start having DC current wired in, then these things would really take off -- also other electronics might not need bulky adapters either.

perhaps I'm a dinosaur but who really wants pure white light? I despise the "white light" of florescent bulbs preferring regular old light bulbs- when will make one that is that color white????

Maybe people think they have "white lights" but really the are a light shade of blue?

they already have those. theyre called infared leds. sure humans cant see it but whats the big deal?
:P

Your article is very good. But the CRI of LEDs is often bad. Around 70-80.
The LEDs which have 90 of CRI are "warm white" and they efficiency is low (arond 50 lm/W).

Thank you for the great website - a true resource, and one many people clearly enjoy.

The optimal color distribution is that of sunlight. Human vision and perception is optimized for that. But its quite flexible, so 'good enough' lighting works perfectly well.

http://www.meta-fx.com
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"White" does not specify any particular spectra. The human eye can identify an almost infinite combination of colors as "White" The ICI chromaticity diagram is a 2 dimensional plot of waveleghts that will allow you to see what color would result from the combination of various wavelengths. If a line joining two points (wavelengths) on the curve goes through the region that we call white, then white can be created with merely those two wavelengths by adjusting their relative brightness. The point is, that although your eye would see the light as "white", if you put it through a prism, you would not get a rainbow band. You'd get just two lines. There is no "pure" white.

I'd like to comment on some themes I read above. Cadmium is extremely expensive. This is a bad thing for buying them, but a good thing fro recyling them. I suspect broken LEDS will still have a value making it stupid to siply toss them.

And in response to how long bulbs can last. It is very possible to buy light "regular" light bulbs that last an incredibly long time. In fact there is a light bulb in a firehouse somewhere in the US that has been burning continously since the 1903 or 1907.

But there is a trade off. the smaller the filament, the less electricity they use, but the shorter the lifespan. The larger the filament, the more electricity they use, but the bulb lasts a long time. the current bulbs sold today are a balance between those two competing issues. It's not a conspiracy of planned obsolescence.

Haven't they said about 10 years ago, that LED would never succeed because it wasn't NEARLY as efficient as compact-fluorescent bulbs?

From what I know about HID car headlights GBS is correct.

4300K puts out the most lumens and is the closest to sunlight at high noon. The lower you go the more yellower a light will get and the higher you go them more bluish to eventually purple it will get.

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really the are a light shade of blue

Can you buy some of this LEDs? Or they didn't got in shops yes? Do you know something about it? I look forward to buy some. ;D

Sure you buy leds household lights. problem is poor illumination...www.directlights.net

They may have Cadmium in them but much like CFLs last longer than incandescents, don't LEDs last even longer than CFLs? I have a couple devices from the 90s with LEDs that still work perfectly. So theoretically because of their longer life span less of these will be thrown out. With their lower energy consumption and low heat output LEDs should take over once they can manufacture them at a reasonable price.

Hi:

I wonder if it is at all possible to generate pure white light [that will display a rainbow band if I put it through a prism] without using any incandescence. White incandescence displays rainbow in a prism but is extremely inefficient -- most of the energy is lost as heat. Only a fraction is converted to light.


Thanks,

Green Xenon

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Thank you for the great website - a true resource, and one many people clearly enjoy.

Very interesting! thx!

Hi i visit through your blog and i found it quite interesting on Led light, I am looking forward to know more about Led light and hope to see it soon on your blog.

Interesting and informative site!

Unfortunately, this combination includes cadmium, which is toxic, though it is likely to be an extremely small amount, much smaller than the amount of mercury currently in CFLs.

pure white light LEDs can be seen everywhere

Very interesting and hope soon leds will be 250Lm/W