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LED Evolution Could Spell The End For Bulbs
An anonymous reader writes "USA Today is running a story discussing how LED lamps were unthinkable until the technology cleared a major hurdle just a dozen years ago. Since then, LEDs have evolved quickly and are being adapted for many uses, including pool illumination and reading lights, as evidenced at the Lightfair trade show here this week. More widespread use could lead to big energy savings and a minor revolution in the way we think about lighting."
I know that this is true because I read it in the Bible. They did not evolve, they were created by God.
I guess we are going to start having "illumiphiles" who will try to tell us that the incandescent lightbulbs of yesteryear are somehow "warmer" and that humans can tell the difference between LEDs and vacuum tubes.
an illuminating article...
--- Asking inconvenient questions for over 30 years...
I'd buy them for that capability alone.
I wonder when we might see LEDs with enough brightess to serve as a projector lamp?
-jcr
The only title of honor that a tyrant can grant is "Enemy of the State."
the lightbulb industry lobbies the congress to ban LED technology that will ruin the market for lightbulbs.
Dvorak on Doomtech
I used to think of LEDs as cute little indicator lights. A nice tiny, soft green LED light tells me that my monitor is on, or blinkenlights let me know that packets are flowing through my router. An orange LED might alert me to standby mode on a device. None of them were really all that visible unless I was looking directly at them, and certainly none put out any ambient light.
Then I got my newest computer. This thing has a single blue LED backlighting an area the size of a dime, behind the power button on the case. When I turn off all the lights, after a minute or so of my eyes adapting, the single blue LED gives off enough light to illuminate half the room. For the first week or so, I had trouble getting to sleep because of the light... From one blue LED.
As the technology gets better I can imagine LED lamps coming in vogue. I seriously doubt that the end of the bulb will come anytime soon, though. Probably not in my lifetime.
"BSD: Free as in speech. Linux: Free as in beer. Windows 10: Free as in herpes." --Man On Pink Corner in #52607549.
This is no surprise... it's been this way in flashlights (hand torches, to you brits) for a while, particularly the higher-end ones and those designed for specialty applications.
As an example, some of the weapon-mounted lights being used by the military are also going to LEDs. Some of the regular incandescent bulbs just don't hold up as well to the punishing recoil of most weapons... you were forever changing bulbs. The higher end incandescent lights like the Sure-Fire lights could take the shock, but forget mounting anything like a mag-lite on a weapon.
Best thing about them: they're easy on the batteries. Batteries are heavy, and there's nothing worse than having to carry too many spares. Every ounce counts when you're carrying it on your back.
Even if a man chops off your hand with a sword, you still have two nice, sharp bones to stick in his eyes.
"On a very hot day you might want blue light to cool it down a bit."
And if street noise is distracting you, a green LED will quiet that right down.
I think one of the main issues with LED lights is the incompatibility with existing lamps.
Sure you buy new lamps every once in a while, but a real breakthrough will come when you can get LED 'bulbs' that fit in a normal 220/110V socket on a normal lamp.
The same thing happened with those energy-saving bulbs, it seems they only really took off (at least here in Denmark where electricity is expensive) when they became available in versions that looked like normal bulbs and fit most lamps.
Another example is the wire spot halogen lights, once they became available in 220/110V versions they took off. Nobody seemed to want those bulky 220->12V transformers around.
Unfortunately, like the article says, the first cost is still prohibitive in a lot of cases, although the savings in energy would seem to make it worthwhile. LEDs also tend to get very, very hot in large quantities if they're used for a long period of time, so air circulation is a common problem as well.
Hopefully some of you computer engineers and programers can come up with a cheap way to produce and control LED arrays so I can start using them in practice! Building owners would be extremely happy if power consumption in buildings would go down significantly and if they had the ability to control the color and brightness (they are easily and cheaply dimmable, unlike flourescents) of any room individually.
This article contains material on evolution. Evolution is a theory, not a fact, regarding the origin of living things (and light sources). This material should be approached with an open mind, studied carefully, and critically considered.
So which way am I better off? Just using lower wattage "classic" lightbulbs, or with dozens of 120V AC->5V DC converters wasting energy everywhere.
The adapter for my iBook puts out more heat then the iBook. More of the heat from my AMD64 is from the power supply vs. the CPU and Gfx.
Almost nothing I own needs over 12V anymore. When will I be able to just have one nice 120->12V spaceheater and run everything else in the room off 12V?
- Adam L. Beberg - The Cosm Project - http://www.mithral.com/
They haven't been used as sources of illumination because they, for a long time, could not produce white light -- only red, green and yellow. Nichia Chemical of Japan changed that in 1993 when it started producing blue LEDs, which combined with red and green produce white light, opening up a whole new field for the technology.
This is certainly one way to produce a white LED but it is not the common method today. Most white LEDs use a phosphor to convert a blue or ultraviolet LED into a white one. A quick google found the following page that talks about this in more detail:
http://www.marktechopto.com/engineering/white.cfm
I would speculate that for normal home lighting using a phosphor will give better results as:
Just this week, researchers at the Lighting Research Center at Rensselaer Polytechnic Institute in Troy, N.Y., said they had boosted the light output per watt of a white LED to almost six times that of an incandescent light bulb, beating even a compact fluorescent bulb in efficiency.
I thought white LEDs are usually blue LEDs, which are coated with a scintillator, which converts parts of the blue light to yellow. Wikipedia seems to support my impression.
Regarding efficiency, I refer once more to Wikipedia: "In 2002, 5-watt LEDs were available with efficiencies of 18-22 lumens per watt. [...] In September 2003 a new type of blue LED was demonstrated by the company Cree, Inc. to have 35% efficiency at 20 mA. This produced a commercially packaged white light having 65 lumens per watt at 20 mA, [...]".
"Between strong and weak, between rich and poor [...], it is freedom which oppresses and the law which sets free"
Q: "How many Californians does it take to resolder an LED?"
A: "Californians don't resolder in LEDs. They resolder in hot tubs."
One can only pray for a GFI failure.
Q: "How many trailer trash rednecks does it take to resolder an LED?"
A: "They still use lightbulbs!"
Okay, that one's still okay.
This is not my sandwich.
Warm and cool are really terms used to describe white light. When you talk about white the question becomes what is it? A blend of all the colours is an elementary explination, but the fact is they aren't all present in equal levels, from any source.
The way that it is talked about, is called colour temperature, and it is spoken of in kelvins. The idea is if you heat a black body radiator to that temperature, that's the kind of white you get. The lower the temperature, the more red in it, the higher the temperature, the more blue.
On most monitors that aren't connected via DVI, you can see colour temperature changes for yourself. In its configuration there should be a colour temperature option, generally with three presets: 5000k, 6500k and 9300k. PLay with them and notice the change. You'll probably find that changing from the one you are used to looks "wrong", either too red or too blue depending on. That's an illusion, however. If you go away for awhile and come back, or just ignore it and keep working, you'll find your eyes adjust and consider that to be white.
With bulbs, it gets more complex because it's not just a function of the temperature of the white, but of it's spectral composition. Most incandesant bulbs have a spectrum that is low on the high frequencies (near violet) and high on the low frequencies (near red). Other lights, like many floursecants, have an uneven spectrum, with peaks all over.
Now ideally what you are shooting for usually is light as close to sunlight as you can get. That's what humans would generally think of as "normal" or "correct" lighting. Easier said than done, of course.
So I don't know what the spectrum for any of the varities of white LEDs looks like, but it is very possible, even likely, that they are different than an incandescant bulb. It may be that they have a generally higher temperature and thus really are cooler, colourwise.
Mostly true. When viewed directly, the eye perceives any color in the color space defined by the three LED colors. But the actual light is still trichromatic, so it won't light up the objects in the room the way you expect them to. A beautiful yellow light might make an object of that same beautiful yellow look like a dingy brown, becuse there's no actual light of that color to reflect off the object.
Try it yourself: Tonight, set your screen background to various colors, turn off the other lights in the room, and see what things look like when lit only by the monitor. The effect isn't as pronounced, but it's still observable.
I have an interestiung anecdotal from ye olden days. Way back when, I had a girlfriend who was an artist, and going to an art school. They had a black tie affair for the students faculty and parents,so we went. Hey, free food and champers! Me in a tux, too funny! Anyway, one of the students mom's there lost a diamond out of a setting, fell on the floor someplace. So here's a couple dozen people in gowns and tuxes all bent over squinting at the floor. We saw it, went over to ask "what's up"? Got told about the loose stone, girlfriend glanced down, immediately spotted it, went over and picked it up, like one second. She saw it from her extraordinary ability to see colors. She had been tested in the school and won, ran 10,000 colors in ROYGBIV sequence not missing a single shade, the only student to get all of them correct.
There are also more subtle issues at work with the 'R/G/B mixing' approach to colour generation. You can read more about them here.
To summarise; consider that the red, green and blue receptors are sensitive to a *range* of colours; the sensitivity curve for each receptor is roughly bell-shaped, peaking on red, green or blue light. There is also some overlap between the red and green sensitivity curves, and between green and blue (not red and blue IIRC).
This is of course essential. Sensitivity narrowly focused on R, G or B would leave us unable to see intermediate colours (e.g. yellow!).
Reasonable overlap is necessary, or
(A) there would be certain intermediate frequencies that were not covered sufficiently by either receptor (e.g. certain shades of yellow in the valley between the red and green curves would be very hard to see), and
(B) Colours would be quantised into 'red group', 'green group', or 'blue group' (think about it...)
Because of the (necessary) sensitivity-curve overlap, the green receptor is slightly sensitive to red light, and so on. Where is this leading, you ask?
True cyan has a frequency between blue and green. This is within the sensitivity range of both blue and green receptors; the brain can use the 'ratio' to figure out that it's looking at cyan. But true cyan is (to all intents and purposes) outside the red receptors' range, so the red receptor is not stimulated.
Simulated cyan is made up of green and blue light. This stimulates the green and blue receptors in the same ratio as true cyan would, so in theory looks just like the real thing. However, the red receptor is also slightly sensitive to green light; thus, unlike with real cyan, the RGB-mixed version also stimulates the red receptor.
This is (supposedly) what makes certain RGB-generated colours less convincing (hence the linked story above).
This isn't even counting the fact that our colour receptors aren't exactly R, G and B, and therefore to simulate certain colours using RGB is impossible, as it requires one or more components to be negative. (If the receptors were exactly R, G and B, that would not be the case).
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It will be some years before we reach this tipping point in price however as current costs are about $100-$200 a bulb for 65watt equivalent LED bulbs
10 years after most bulbs are LED conventional bulbs will seem anachronistic and stone age. One of the few things in the last 100 years to just be out and out replaced by a new technology. Granted we have lots of bright shining new things in our modern world, but they general have been added to what we already have or evolved slowly from what came before. The switch to transistors from tubes is about the only other thing that comes to mind where this has happened, and perhaps this should just be seen as one of the last hold outs of filaments in tube to be displaced by solid state. All that is left to go are CRTs and this too will happen relatively soon.
In need of a similar revolution: Cars that run without gas - this is a hard one, but we are finally starting to make some progress; Energy production from other than Oil, Gas, Coal, and Uranium. Fusion is about the only way to go here, but it isn't doable at any price today. None of the other energy alternatives have a chance of displacing the big 3 fossil fuels or remaining conventional nuclear plants; Getting to Space without conventional rocket technology. Do all these things and we will have finally arrived in the 21 Century.
Letter To Iran
I think all the new stoplights in town are LED stoplights. Most of the brakelights on trucks around town are too. Did this story fall through a time-rift from seven years ago?
What other lights?
I doubt it, at least not the kind of person the grandparent is referring to. If you are you should be calling a research lab and asking for bids to be a guinea pig. Tetrachromats are extremely rare.
This hypothesis sounds more likely (from http://www.physics.utoledo.edu/~lsa/_color/18_reti na.htm
Rods and all three cone types readily absorb ultraviolet radiation, photons of which are energetic enough to damage these delicate cells. The reason we cannot see in the UV is because the eye lens is opaque in that wavelength range. In addition, the cells in a region called the macula surounding and including the fovea contain a yellow pigment that further prevents short wave radiation from reaching the photo-receptors. Some people with less of this yellow pigment and those who have had their lenses replaced with plastic inserts can see further into the UV than normal people can.