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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.'"
Considering that the average lightbulb creates more heat than light, this is great!
Yes Francis, the world has gone crazy.
are not followed by 'Eureka' , but by "Hey, that's funny" .
The Dutch will inherit the earth. If not, we'll settle for a bit of ocean. Beta delenda est!
One of the unfortunate side effects of the 1970s was the replacement of all the soft white street light bulbs with orange-yellow sodium vapor bulbs. Sodium vapor bulbs use less energy. All the night lighting went from soothing soft white to light orange. Orange, as you may recall, is the color of madness.
I've never liked yellow-orange streetlights. It's one of those things that never gets noticed. But the difference can be really appreciated if you go to a wealthy neighborhood where white light bulbs are still used. However, unless you're older and white, it's going to be a short time before the 'security guards' drive up with tasers and ask you what you're doing. If you're truthful and tell them that 'you're digging the cool white groove of the light, baby', then they will do what all mercenaries do when encountering a civilian harmlessly enjoying life, they will kidnap and assault you for their amusement.
Anyway, a return to soft white lighting in the night will be most welcome.
I can definitely see the benefits of LEDs when compared to other forms of electric light. They do produce more lumens per watt than most other sources, but they do produce a good deal of heat when combined together into a large array, despite what people may tell you. They also have the added benefit of efficiently producing (since they only produce light in a certain wavelength) just about any color you would want through color mixing of different color LEDs (check out the tunnel in the Detroit airport if you'd like to see a well done example). Personally, though, I would love to see more daylight in spaces rather than a push for the latest and greatest in electric light. If done properly, daylighting can greatly increase light levels in the workplace and lower energy consumed by electric light. Generally, this will lead to an increase in cooling load, but this is almost always smaller than the amount of energy saved by eliminating electric lighting (again, if done properly). So while I'm all for more efficient electric lighting, it would be nice to see no electric lighting used during daylight hours when the sun is readily available.
From a senior project I did in a few years ago, we dimmed an array of 300 high-powered LEDs (Lumileds)with no flicker at any level. They definitely didn't run totally cool, though they did have a fair amount of heat. As far as dimmers go, most standard dimmers use SCRs or triacs for dimming instead ofa rheostat anyhow, and that should work just fine for LEDs. Whatever supporting circuitry is used can easily provide dimming capabilities already built-in.
Sure, I imagine a hundred years ago the fact that incandescent bulb gave 2800K to candle's 1200K really hindered its adoption. Because candles were what people came to expect.
No, the sibling poster is right - daylight is the real measuring stick here, not 100-year old human technology.
No- many things are holding back LEDs.
I know everyone thinks they are the second coming of Christ, and they do have some wonderful applications (like traffic signals and car brake lights)...but they're not the end-all be-all.
Please help metamoderate.
Fluorescent lamps are not really suitable for applications (think toilet room/stairwell lighting) where the light only needs to be on during a few minutes, and is turned on/off many times a day. Even with the better fluorescent bulbs that have their full output immediately, there's still the problem that they'll wear out much quicker when turned on and off many times. The rated lifetime is most often estimated on a typical usage pattern where the light is turned on and off only once or twice a day, and burns continuously during a few hours. For such applications, a simple incandescent bulb is perfect. You won't save much anyway by replacing it with something more energy-efficient, if the bulb only burns a few minutes a day. You might even end up spending more money because you have to replace these more expensive bulbs faster than expected.
The main reasons why White LEDs are still not ready for general purpose lighting are:
Low CRI (Color Rendering Index) that means bad illumination compared to incandescent
Low temperature of operation (120-150C max)
Most electronic design that include hi power LEDs (such as LUXEON http://lumileds.com/) need to take in account hheat transfer.
....Tag.
Considering that the average lightbulb creates more heat than light... Kind of like most slashdotters!
I tried to moderate your comment and had to give up in the End as i couldnt decide whether You were Funny or Insightful.We need a new "Funny Because True" Tag.
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