Making Strides Toward Low-Cost LED Lighting 398
Roland Piquepaille writes "You all know that incandescent bulbs are pretty inefficient, converting only 10% of electricity into light — and 90% into heat. Light-emitting diodes, or LEDs, could soon replace incandescent and compact fluorescent bulbs in our homes. They are more efficient and environmentally friendly. But LED lights are currently too expensive because they are using a sapphire-based technology. Now, Purdue University researchers have found a way to build low-cost and bright LEDs for home lighting. According to the researchers, the LED lights now on the market cost about $100 while LED lights based on their new technology could be commercially available within a couple of years for a cost of about $5. It would also help to cut our electricity bill by about 10%."
Light vs. heat scale (Score:3, Interesting)
LED = Luxury Goods (Score:5, Interesting)
Take a hint from the car manufacturers. Today, high-end cars are using LED tail lights. They are also used on trucks. The main advantage is they do not burn out.
However, for most people in the world a burned-out tail light bulb is a minor safety issue and a minor expense. Replacing the bulb takes 10 minutes and maybe the owner's manual if you are truely clueless about how to do it. Also, many people own a car for 5+ years without ever having to replace a single bulb.
Compare this to the cost of a minor traffic accident where a tail light is cracked. No, you cannot replace the lens or any individual part, just the whole assembly. Instead of $100-$200 for an incandescent bulb assembly expect to pay $1500-$2000 for the LED tail light.
Sure, over the life of many vehicles it is a minor issue that bulbs will never burn out. But over the same number of vehicles it is far, far more likely that a lamp assembly will have to be replaced. The result is a far more expensive part to replace.
With trucks there is a certain amount of sense to be made with claiming that the bulbs do not have to be replaced. Replacing a bulb on a truck or semi-trailer can be a real hassle requiring a ladder and tools. However, again the likelyhood the bulb would ever need to be replaced vs. the lens being damaged is about the same as for cars. Basically, it is a complete rip-off.
Expect to see wired-in LED systems in household lamps where the fixture must be replaced because the bulbs cannot be. Expect to see the fixtures sold to builders with non-replacable bulbs will cost the builder only slightly more when bought in huge quantities but the homeowner will be faced with $1000 lamp fixtures should they ever need or desire to replace them.
It's Roland the Plogger, wrong as usual (Score:4, Interesting)
It's so Roland the Plogger.
The "breakthrough" this time is that someone made gallium nitride substrates that might, someday, be useful for LEDs. After they solve the problem that their material cracks during cooling. However, Panasonic did that last year [compoundse...ductor.net], and has been shipping white LEDs using that approach in sample quantities.
Do LEDs blink ? (Score:5, Interesting)
So, suck it up, I hear you say. Right, except that each blink leaves an annoying remanent patch on my retina that lasts for a few seconds. Imagine driving at night in a city, 10 cars in your field of vision, look left, right and suddenly you have 200 spots in your field of vision. Awesome to know what's going on, right ?
I loathed the xenon high beams when they first came out a few years ago. You know, those tiny very concentrated blue lights ? Leaves a retina trail that lasts for 20 seconds. I'm so glad that they are gone now. I've never heard if they were made illegal or if they just went out of fashion, but I hope LEDs (which are a good technology) are applied in a good way...
Re:LED = Luxury Goods (Score:3, Interesting)
Re:Yea, (Score:4, Interesting)
Poster saith:
TFA saith:
Me: "I live in Canuckistanbul - we NEED the heat, you ignorant clods!"
Electricity costs less than oil or gas here ... it's cheaper to get some extra BTUs from incandescents in the winter months ...
Re:Is it white, though? (Score:2, Interesting)
Another thing I imagine might be to make the LED as an integrated circuit - an array of LEDS with each junction a slightly different gap than the preceding, so while you don't really get a true continuum, a few million different colors would be awfully close (and besides the frequency that an LED produces does have a band width, so if each color is close enough, you do get a continuum with enough colors.)
Anyone know if anyone is working on either method?
Re:Yea, (Score:5, Interesting)
CFL Color (Score:5, Interesting)
I really like the color you get when a 2700 & 5000 degree light are in the same fixture, everything looks bright and colorful.
Link (Score:3, Interesting)
Luxim Plasma [treehugger.com]
Re:Yea, (Score:5, Interesting)
Well, they won't flicker, they won't contain mercury, and they won't be too big to fit in many light fixtures.
Even if LEDs aren't any more efficient than current CFLs, they'll be a lot more attractive to people who don't like or can't use fluorescent lights.
Have you actually looked at high-quality CFL bulbs? A good daylight bulb is a thing of beauty. No flicker (and, you know, CFL bulbs have never had flicker because they are run at much, much higher frequencies than you visual sytem can see), proper color balance, small, reliable, quiet.
Note that I'm not talking about the two or four foot long fluorescent bulbs that you might have in your office. Those are probably not daylight balanced and probably flicker at 120 Hz (yes, 120 Hz, not 60 Hz, because both half cycles push current; unless you're in part of the world which runs on 50 Hz mains, in which case they flicker at 100 Hz). Their ballasts also have a tendency to buzz.
Good CFLs are wonderful.
Note, also, that many LED bulbs you can get these days are simply awful because they flicker at 60 Hz (yes, 60 Hz, because they're arranged in cascading diode fashion and only conduct on every other half cycle) and the phosphors are terrible. They also lose brightness at an astonishing rate and are horribly temperature sensitive (hotter chip, lower light output). The 60 Hz issue can certainly be fixed with better circuitry (ie, bridge rectifiers and some low-pass filtering) and one hopes that the phosphors and lifetime improve.
Wait, phosphors in an LED? What am I smoking? Yes, it's true, most white LED bulbs for sale are actually UV emitters that excite phosphors. And just like fluorescents, the better the phosphors, the better the output spectrum. While it is possible to generate white-ish light from a combination of red, blue, and green LEDs, because the aging curves are different for the three classes of emitters, the color balance is dynamic over the bulb lifetime. And, also, the spectrum is terrible -- even the spectrum from fluorescents is better -- because it's essentially three isolated wavelengths instead of a continuous spectrum.
LEDs have a long, long way to go before they can be used in living or working spaces.
Re:Yea, (Score:3, Interesting)
I've never had a CFL burnout
They will do. My parents were early adopters (must be over 15 years since we had them), I think the only incandescent light in their house is in the microwave.
I remember the first ones cost about £10 and were massive, heavy things and they did flicker, and take five minutes to warm up. But the ones made in the last 5 years or more are brighter, white, don't flicker, and don't buzz. They do (eventually) burn out though.
Yellowy incandescent lights remind me of my grandma's house; admittedly the yellow effect was enhanced by her cigarette smoke.
Re:LED = Luxury Goods (Score:5, Interesting)
They are. I've seen some in nightclubs and at concerts, the brightness and the instant on/off effect is fantastic.
It's probably even better with ecstasy.
Re:Do LEDs blink ? (Score:1, Interesting)
The blinking circuit is too allow different brightness levels such as the difference between braking and having the tail lights at night. It is much cheaper to simply use pulse width modulation with the already available ECU then it is to build a variable current analog circuit.
I bought two $30ish LEDs - they suck (Score:3, Interesting)
Very dim. About 50% of the amount of light they advertised to put out.
Even adding a lot of these wouldn't increase the light above "dismal" level-- the intensity of the light was just lower than that put out by CFL and incandescent.
I want LED to work-- they last a long time, they use no power, and they have no mercury.
These might be okay for a porch light-- dim but always on.
Re:CFL Color (Score:5, Interesting)
Here's some links:
A white LED's spectrum [sci-toys.com]
A CFL's spectrum [sci-toys.com]
Re:LED = Luxury Goods (Score:3, Interesting)
For what it's worth, one reason trucks have gone to LED's is that they don't die because of vibration, like incandescent bulbs do. We don't really know how long LED's will last, but if they're correctly designed, they should still have at least 50% brightness at 50,000 hours of operation.
All the LED lighting solutions my company is building, and all the ones from our competitors that we've been buying and taking apart, are screw-in replacements for existing bulbs. Every single one, without an exception. If car companies wish to make their cars more proprietary by specifying custom LED lights, well, they're free to, but I think it'd be a stupid move.
Re:Concerns about LEDs... (Score:3, Interesting)
Dimming LED's.
LED's are commonly dimmed in headlamps. I have right next to me a Petzel Tikka XP Headlamp that has multiple LED light settings. And yes, each of those settings is a different dim setting. The LED can also be "over-driven" for a short period, putting out more light than normal.
So, parent poster is correct, LED's do dim, and they dim quite well.
Re:Do LEDs blink ? (Score:5, Interesting)
What you are seeing is the pulse-width-modulation dimming of the taillights applied with insufficiently high frequency. Cheap chinese flashlights like the Jetbeam C-LE (which has gone through three revisions prior to current - and is an absolutely excellent little LED torch) have been using increasingly high PWM frequencies to get around that; more expensive ones use current regulation (which averages the current of the PWM circuit over a few tenths of a second to produce a flat current (and therefore brightness) curve when viewed on an oscilloscope. The advantage of lower PWM frequencies is that the eye hands them off to the brain via a high-priority nerve link that results in people noticing them significantly (tenths of a second or so, IIRC) faster, theoretically reducing both the number and severity of accidents. The fact that many of them are bright enough to impair normal night vision seems to be lost on auto designers.
HID headlights have not gone away, but their implementations have been getting better - projecting beams on a down-angle so they don't nail people in the eyes, lowering the operating temperature of the bulb, making them less blue and more yellow-white without making them dimmer (actually, lower-temperature HID bulbs are more efficient than the blue-tinted ones). HIDs are popular for bulb life being insane, since headlight replacement was getting to be a significant drain in carmaker's warranty claims, and being brighter and having a longer effective range, which is good when there's no streetlights.
Entirely different is the blue-tinted halogen bulbs that are simply normal bulbs with a light blue paint applied - these are the ghetto-fabulous attempt to make it look like you've got an expensive HID conversion for an older car, and are about 30% dimmer than normal halogen headlights despite being harder on other drivers' eyes. I have no forgiveness for people who use these because they think it looks good.
dental fillings (Score:4, Interesting)
That's all well and good but you would be surprised at how much mercury gets into the environment from dental fillings and how few people will pay the extra $15.00 to get composite fillings!
Not everyone knows dental fillings contain mercury. I got into an argument with someone over that, I had to prove to them mercury was used. And not all dentists use composite fillings [wikipedia.org].
Falcon
Re:Yea, (Score:2, Interesting)
Funny thing, that.
The dutch wikipedia site shows they do:
Dutch article on Ledlamps [wikipedia.org]
See the table...
Re:Yea, (Score:3, Interesting)