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The End Of The Light Bulb?
sdmonroe wrote to mention an MSNBC article discussing the likely eventual replacement of common light bulbs by LEDs. That replacement is likely to come quicker thanks to an accidental discovery announced this week. From the article: "Michael Bowers, a graduate student at Vanderbilt University, was just trying to make really small quantum dots, which are crystals generally only a few nanometers big. ... When you shine a light on quantum dots or apply electricity to them, they react by producing their own light, normally a bright, vibrant color. But when Bowers shined a laser on his batch of dots, something unexpected happened. 'I was surprised when a white glow covered the table,' Bowers said. 'The quantum dots were supposed to emit blue light, but instead they were giving off a beautiful white glow.'"
I have been impressed with the LED lights over florescent or incandescent. The subdued lighting is fine with me and the energy consumption / bulb longevity is the best part. When my wife and I move (build a house), we will go 100% LED.
Click here or here.
I will go to leds when they meet my budget....just a matter of time.
White LEDs are already 3 times as efficient as mercury fluorescent, and fluorescent tubes are 3 times as efficient as incandescent. They (fluorscent and LEDs) can get pretty good colour accuracy, too, if they want to. The only thing holding them back is price. I'm not sure what this new invention might bring to the table in that regard.
Have you ever tried an LED light? They suck!!! They do not cast nearly enough light. The light color is a disturbing and unnatural color, usually with too much blue in it.
Florescent tubes are FAR superior to LED lights and yet so many people prefer good old incandescent lights to even florescent tubes. Hell, even something as simple as a flash light. Try an LED flash light and then try a xenon Mag Light and tell me which one rocks your socks.
LED lighting is one of those technology "revolutions" that are for the sake of technology. They are NOT better.
at my workplace, a hotel on the beach.
We had for many years yellow colored standard bulbs, as they don't attract bugs.
we started replacement with yello fluro twist bulbs, to save on electricity and replacement costs.
in research, it turns out, we can use white fluro-- as they only emit light in a very narrow spectrum of white light, unlike an ordinary filament bulb.. and the range they do emit light on, suitable for humans, does not attract bugs.
I'd guess these low power led lights also emit white light on a very narrow band....
every day http://en.wikipedia.org/wiki/Special:Random
About 7 Years ago I brought a LED Headlamp to a spelunker convention. They were leery at first but when I didn't change my batteries once during the entire weekend they were sold. The next year there were about 10/50 of us on LED. Now everyone has an LED lamp.
If the manufacturing breakthough talked about in this article pans out, the cost of Quantum Dot manufacture will drop from $2,000 to $400 per gram. That's huge improvement, but I still wouldn't expect to see Quantum Dot lightbulbs on ThinkGeek anytime soon...
Disadvantages include:
Low candle power. LED lights are lacking in their production of, well, light.
Unnatural color. LED lights have unnatural and sometimes disturbing colors. Incandescent lights have a warm glow that is closer to natural light and "full spectrum" incandescents produce something very near sun light.
Expense! Producing an LED "bulb" with the same candle power as an incandescent bulb is FAR more expensive than the incandescent.
Possible health issues due to the poor light quality. A plant will grow under incandescent light, it will not grow under an LED.
I have an led flashlight.
led's emit a very cold light. Fourescent light is described as cold and "vitamin burning", but led light is even worse in this respect.
It works for headlights, emergency beacons, and select areas, but generalized room lighting is not one of those areas.
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Actually LEDs do produce heat, albeit the ratio of heat/light is much lower than with incandescent bulbs. The common LED is designed for a maximum current of 20 ~ 30mA, and at these currents the heat production is negligible. You can drive them at a higher current, but then the heat production becomes significant and can cause the LED to burn out (and at real high currents, the junction simply breaks down immediately). The more performant Luxeon LEDs are attached to a tiny heatsink and the high power ones (3W and 5W) require an additional heatsink to use them beyond 1W.
I'm a professional firefighter and a lot of the guys have started using LED flashlights. I had just purchased my own (out of my pocket and not the city's) rechargeable StreamLight that uses a halogen bulb. When I started seeing the LED's showing up I thought I had made a mistake. They "seem" bright but after seeing them more and more I'm convinced it's just because the light is so white (slightly blueish) and clean.
However even though it looks brighter in fact it's less so and seems to accentuate shadows MUCH more.
I really haven't discussed power consumption with anyone yet but for now........ at least in this application....... I'll stick with the older technology.
Anyone who tries (like me) to build small lighting devices with LEDs rapidly discovers lots of practical difficulties. To equal the light output of one cheapo fluorescent tube you need hundreds of the little blighters. It is not easy to make their output look even, rather than dotty. And with that large number, reliability is a real problem. Even a 1% failure rate (amplified to 3% or 5% by the LEDs often being in series) rapidly translates into major unevenness. Even production lines struggle to make large arrays of LEDs stay 100% alight, but little people often get sold the bin ends, which fail rapidly in service.
Also LEDs are NOT yet more efficient than fluorescents. Their data sheets never give the one number that really matters: what percentage of input energy actually emerges as light? The answer is usually frighteningly low. Therefore LED devices tend to cook themselves to death if run really bright.
To run LEDs stably requires either a wasteful series resistor or an expensive semiconductor constant-current device. And cheap low-voltage power supplies are actually badly life-limited by their electrolytic capacitors. In my experience many LEDs die prematurely because of a failing power supply and hot sunshine.
Don't get me wrong. LEDs are the future, but you must be wary of calling them energy-saving, long-lasting, or easy to use!
(I hate scientifically-illiterate journalists.)
Time is Nature's way of keeping everything from happening at once... the bitch.
When I was finishing up my PhD (on InfraRed LED's) about 5 years ago, HP was making high-efficiency Red LED's with 50% light output efficiency. At the same time commercially available blue (GaN) LED's were only 10% efficient. Green LED's were somewhere inbetween.
I should really google for the state-of-the art visible LED efficiency, but am hoping for someone to post a more informative post following this one.
Were they placed horizontal or base-up? When CFs are installed base-up, the heat from the bulb rises and tends to cook the ballast, shortening lifetime. They do a lot better in base-down or horizontal installations.
I have a huge 45w (200w equivalent) CF in my garage. Going on 3 years, still works great. And it's even base-up.
I've had a few CFs burn out within a few months, too. I think some of them just have manufacturing defects.
DRM 'manages access' in the same way that a prison 'manages freedom'
Once they're up and running, they're bright, nicely colored, and cool to the touch. But having to wait a full minute for the stairwell bulb to get bright is pretty suboptimal.
Are these "features" of all CF bulbs, or is the brand I've been buying really crummy?
Dewey, what part of this looks like authorities should be involved?
CFL's do not like enclosed fixtures - I live in a rental, so I am not inclined to change them, but *every* cfl I put in those fixtures failed. I did post-mortens on them, some seemed to have unsoldered themselves (wires off the board) and others just seemed to have died. They never seemed to feel hot enough to melt solder, but the conditions in the base while running might have been pretty rough. So 15 have failed, 2 survived (in open socket applications). Many rooms in my house have regular tube fluorescents, which rarely give me trouble.
AC has it's advantages, especially for long distance transmission. But in a house, it's gradually losing out. If you don't count lightbulbs, I'd say I have more DC things plugged in than AC. So many of the outlets are connected to "bricks" or "wall warts" to change the high voltage AC to low voltage DC. Things that don't have an exterior brick, like the DVD player or TiVo just do the conversion internally. While the higher voltage AC might have some benefits of lower loss in the wires, I'd think that umpteen separate transformers and rectifiers are negating a large percentage of that benefit.
If lighting were go to DC, then a re-think of the home wiring would really be in order. If there were a "standard" DC voltage and current available to lower power devices, we might not have wall transformers with anything from 3v-12v hanging off our surge supressors.
So in-house DC makes lots of sense. Send the AC to things like ovens and clothes dryers, and DC to most everything else.
The frequency distribution of this light is so much more natural than the other low-energy alternatives! I wonder if it could be made to match the frequency distribution of sunlight more closely by just rearranging the mixture of the sizes of the quantum dots. Anyway, this is excellent news. It's because of the spectrum distribution of fluorescent bulbs that I refuse to use them. It's not that I like wasting energy, but even without ugly light, winter is depressing enough in upstate New York!
I know what you mean though. I do hate the way they look. The orange glow even makes trees look creepy.
I disagree with your like. I find the white lights to be over
bright and obnoxious. I much prefer the muted look of the
sodium vapor lights. Especially from the air. The yellow
lights are much more pleasant to view. What would be really
nice is if we could change them to our liking. I have one
of those bright white lights in the street outside my house.
If it had knobs on it where I could change its spectrum, that
would be cool. My ex-wife's neightborhood has no street
lights at all - which I really prefer.
Thanks for the link, I bookmarked the homepage to explore the site. I noticed one thing on the page where it says there's a problem with Fluorescent lights, "Use halogen lighting for outdoor applications where temperature causes problems with fluorescents." I lived in Florida and never had a problem using them outdoors and I currently live in Minneasota and haven't experienced problems here either. I've lived and used CFLs in both heat and cold without problems.
FaclonShould there be a Law?